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International Disk Drive Equipment and Materials Association

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what’s

On the Road to Increasing Areal Density

10 Gb/in2 Slider Manufacturing

IDEMA Asia-Pacific offers Certificate ofCompetence in Storage Technology

Alliance with KnowledgeTek provides memberswith basic education classes at a reduced rate

Areal Density Beyond 10 Gb/in2

January/February 1999

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SeagateReserved Spot

1 year positioningINSIDE FRONT COVER

ince its inception in 1986, IDEMA has grown its support services for the storage industryinto a well-developed set of offerings. These services include the staging of our

industry’s successful tradeshow, DISKCON, standards development and documentation,and our various technical conferences and symposia. These services are all aimed atfacilitating communications and progress within our industry. This year, we will significantlyexpand our educational services.

We have listened to our members discuss their current challenges and their expectationsabout the future, and we have heard very clearly their concern about how to keep theiremployees abreast of the continual technological changes that characterize this industry.Some of our members are trying to cope with this issue by making investments in in-houseeducation programs. Others are looking to IDEMA to expand its educational services to helptheir employees keep pace with the technology demands.

So, in 1999, IDEMA is making a dramatic change to its education program. We have justbegun to offer a set of six basic classes designed to give students the understanding theyneed of disk drives and the primary component technologies. These basic classes will beaugmented by classes in specific areas such as microcontamination and ESD. I refer to thiseducation emphasis as dramatic because we will hold over 50 classes in the United States and40 classes in the countries of Singapore, Malaysia, Thailand, and China. IDEMA Japan willcontinue to build upon their education program, which was launched in 1998.

By the end of this year, IDEMA will have helped several thousand of our members’employees to be more productive in their jobs and better able to assimilate the technicalchanges going on in this industry.

departments6Marketplace

7Letter from the Editor

12Storage News

18Industry Calendar

20Volunteer Spotlight

22Standards Update

30Committee Focus

44IDEMA Asia-Pacific

46Technical Education

articles7Transforming the WasteLands of Excess Inventory

8On the Road to IncreasingAreal Density

14Laser Marking on Hard DiskMedia

21Getting to Higher DataRates: The Flex System

26Future High Speed Spindleand Components for HardDisk Drives

3210 Gb/in2 SliderManufacturing

LarryIDEMA President, Larry Eischen

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MarComm Manager/EditorNicole Flynn, [email protected]

Creative DirectorChris Carrig, [email protected]

Communications ChairWayne Fortun, Hutchinson Technology

Communications CommitteeDave Allen, KomagDave Brown, SeagateWayne Erickson, Phase MetricsJay Kimmal, HMT Technology

ArticlesArticle contributions arewelcome and are subject toediting by IDEMA.

AdvertisingAdvertising is offered to IDEMAcorporate members only. Adspace is available for theMarch/April issue. Ad closeFebruary 5. Due date for admaterials is February 12.Editorial calander andadvertising rates available at:www.idema.org.

SubscriptionINSIGHT is produced bimonthly.For your free subscriptioncontact Lindsay Brown,408.330.8103or [email protected].

INSIGHT is a free bimonthlyassociation magazine, published bythe International Disk Drive Equipmentand Materials Association (IDEMA).The goal of INSIGHT is to informIDEMA members and industryprofessionals worldwide aboutemerging technologies, upcomingIDEMA trade events, as well aseducational opportunities. INSIGHTis read by more than 14,000engineers, scientists, and technicalmanagers.

All rights reserved. IDEMA andDISKCON are registered trademarksof the International Disk DriveEquipment and MaterialsAssociation. Other product names orbrands used in this publication arefor identification purposes only andmay be trademarks of their respectivecompanies.

IDEMA Staff—U.S.PresidentLarry EischenExecutive DirectorJoan PinderDirector, EducationSally Bryant, Ed.D.AdministratorLindsay BrownCreative DirectorChristine CarrigFinance/Database ManagerGloria RodriguesMarComm ManagerNicole FlynnProgram ManagerDebbie LeeStandards ManagerSeth Ayers

IDEMA Staff—Asia-PacificExecutive DirectorS.H. GohAdele ZhuangE.K. Choo Lilian Lim

IDEMA Staff—JapanExecutive DirectorTatsuo SugiuraFinance/StandardsAkiko YamamotoEditor/SeminarNaoko Miura

IDEMA—U.S.3255 Scott Blvd., Suite 2-102Santa Clara, CA 95054-3013Phone: 408.330.8100Fax: 408.492.1425

IDEMA—Asia-Pacific1 Goldhill Plaza#03-35 Podium BlockSingapore 308899Phone: 65.356.3992Fax: 65.356.1340

IDEMA—JapanWataru Bldg., 6th Floor2-11-9, Nishi ShinbashiMinato-ku, Tokyo 105-0003JapanPhone: 81.3.3539.7071Fax: 81.3.3539.7072

Board of Directors—U.S.ChairmanJoel Weiss Seagate Recording Media Group

Vice ChairmanJohn Kurtzweil Read-Rite Corporation

TreasurerRuss Krapf Western Digital Corporation

SecretaryOz Fundingsland OSF International

Gil Argentina Pacific Ceramics, Inc.

Chris BajorekKomag, Inc.

Wendy Dewell IBM, SSD

Wayne Fortun Hutchinson Technology, Inc.

Mark Geenen TRENDFOCUS, Inc.

Ed Grochowski IBM Almaden Research Center

William Harry Exclusive Design Company

Dennis Hill LSI Logic

Shun Kaneko Iomega Japan

Brian Nixon Quantum Corporation

Don Perettie Admat

Norman H. Pond Intevac

Jim Porter DISK/TREND, Inc.

Barry Rossum Seagate Technology

John Schaefer Phase Metrics, Inc.

Management Committe—Asia-Pacific

Chin Tai Chua SCI Manufacturing

Gary Davis Davis Consultants Asia

Paul Dostie Phase Metrics Pacific Pte Ltd.

Melvin Gay 3M Singapore Pte Ltd.

Gaylord Ho Vector Magnetics Pte Ltd.

S.C. Lee Maxtor Peripherals (S) Pte Ltd.

Tay Bong LimMMI Holdings Ltd.

William LowIBM Singapore

Vince Mastropietro Western Digital (Singapore) Pte Ltd.

Chang Faa ShoonSeagate Technology

Dale Schudel K.R. Precision Public Company Ltd.

William Tan Megatech Electronics Pte Ltd.

Mike TroemelSeagate Technology

Alan Tay Hutchinson Technology Asia Inc.

Richard Wee Quantum Asia Pacific Pte Ltd.

Board of Directors—JapanChairmanSyun KanekoIomega Japan Corporation

Vice ChairmanTsuneo SuganumaHitachi, Ltd.

Vice ChairmanAkira KakehiFujitsu, Ltd.

AuditorHideki HaradaHitachi Metal Technox

Youichi InoAnelva Corporation

Toshio InoueMitsubishi Chemical Corporation

Yasuhiro OkamuraMA Disc, Inc.

Nobuhisa OnoueNippon Light Metal Company, Ltd.

Hiromi KamimuraToshiba Corporation

Shigeru KikuchiKobe Steel, Ltd.

Koichi SatohIBM Japan, Ltd.

Hajime ShinoharaHitachi Metals, Ltd.

Keiji TakatsukaAlps Electric Corporation, Ltd.

Tetsuo TsuruHitachi Electronics EngineeringCorporation, Ltd.

Masayuki NakayamaSony Corporation

Yuichi HyakusokuMediken Inc.

Toshihiko MakinoNEC Corporation

Hideaki YamazakiJTS Japan, Inc.

Joel WeissSeagate Recording Media Group

®

Dover InstrumentsAd

full year page 5

Shares Stock Calendar Year Price/Earnings Market Cal. 99 MarketOut. Price Earnings Per Share Ratio Cap Revs. Cap/

Industry Sector Company (MM) 12/7/98 1997A 1998E 1999E 1998 1999 ($MM) ($MM) 99 Revs

Disk Drives Maxtor 90.0 14.50 (4.28) 0.36 0.92 40.3x 15.8x 1,305 2,960 0.4

Quantum 169.0 22.00 2.07 0.39 1.50 56.4x 14.7x 3,718 5,600 0.7

Seagate Technology 246.0 31.63 1.72 0.45 1.65 70.3x 19.2x 7,781 7,560 1.0

Western Digital 89.0 17.13 0.83 (4.36) (0.85) NM NM 1,525 3,320 0.5

Components Applied Magnetics * 24.0 7.50 1.51 (6.42) (4.60) NM NM 180 275 0.7

HMT Technology 43.8 12.00 1.34 0.37 0.54 32.4x 22.2x 526 300 1.8

Hutchinson Tech. 19.8 32.00 1.02 (1.66) 2.65 NM 12.1x 634 700 0.9

Komag 53.4 8.50 0.40 (3.56) 0.05 NM NM 454 450 1.0

Read-Rite 49.0 14.25 1.75 (2.98) 0.52 NM 27.4x 698 960 0.7

Capital Intevac 12.0 7.25 0.94 0.08 0.00 NM NM 87 95 0.9

Equipment Veeco Instruments * 14.6 39.00 1.75 1.09 1.40 35.8x 27.9x 569 250 2.3

Removable Iomega 275.0 7.25 0.42 (0.17) 0.25 NM 29.0x 1,994 2,100 0.9

Average: 19.6x 14.0x 1.0

*No official H&Q coverage; First call estimates. “A”= actual; “E”= estimate

Statistical Summary Selected Data Storage Stocks

Data Storage Index

Leading trade analysts share their market perspective onthe data storage industry.

Hambrecht and Quist LLC

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unprofitable in 1997 andmost of 1998—yes.Sluggish—almost never. Theneed for greater storagecapacity has continued andwill continue to expand inmultiple directions anddimensions.

The RDD markets did notexperience a downturn in1997 and 1998 (as someindustry observers havemaintained). On the contrary,they grew. Demand actuallyincreased for most products innearly all market segments.But the RDD manufacturersmanaged (once again) tooverproduce; creating chaoticmarket conditions by buildingand shipping at levels thatexceeded the world’sgrowing, but far fromlimitless, appetite for storage.

All drive makers have beenplagued to some degree by aglobal surplus of available

The Profitless Perils of

Surplus—“It’s like a

combination of Alzheimer’s

disease and deja-vu: We’ve

forgotten how terrible it was

all over again.”

— Phil Devin, wryly (andwarmly) commenting onhuman frailty in the contextof industry overproduction

ome journalists andfinancial analysts haverecently characterized therigid disk drive (RDD)industry as “sluggish”.

Dataquest believes that theRDD industry is not currentlysluggish nor has it beensluggish at any time duringthe last three years.Challenging and largely

Transforming the Waste Lands of Excess InventoryRecent Developments in the Rigid Disk Drive Industry

from the editor

Nicole Flynn,MarComm Manager

and INSIGHT Editor

INSIGHT is taking on a whole new look and direction in 1999. To better serve our worldwideaudience of more than 14,000, INSIGHT is evolving from a technical journal to an associationmagazine. We will continue to feature technical articles contributed by our members, but themain focus of the magazine will be on IDEMA’s worldwide services, including symposia events,standards activities, and technical education.

Improvements have been made to INSIGHT’s editorial content and overall design. Newdepartments and sections have been added to provide our members with the information theyneed to be active in IDEMA and current with industry products and events. We have alsoexpanded our Far East coverage by featuring articles from our IDEMA Asia-Pacific and IDEMAJapan offices.

With the addition of Creative Director Chris Carrig in August, INSIGHT’s design has beenenhanced by limiting article jumps and raising the image resolution standard. In addition, colorand graphics are now being used as design elements to compliment articles, as well as tocreate a visual hierarchy.

We hope that you enjoy reading “the new” INSIGHT as much as we have enjoyed producing it.Please let me know if you like what we are doing or if you have any ideas on how we canfurther improve the publication. Send your comments or suggestions to [email protected].

John Monroe—Chief Analyst,Rigid Disk Drives, Dataquest

RDDs since March 1997. Tothe best of Dataquest’sknowledge, this has been themost protracted period ofcontinuous oversupply in thehistory of the RDD industry.

A large part of the problemhas been that too many well-funded drive makers havemanaged to achieve near-simultaneous technologicaland manufacturing might.Never before have so manyviable RDD manufacturersbecome so proficient inbeing able to expediteadvances in their mobile,desktop, and enterprisetechnologies, and actuallydeliver new products on timeand in strategicallysignificant volume.

In this industry, “normal”times are rare, not to saynonexistent. However, as ageneral rule—to which thereare many exceptions—we

can say that a normal yearfor the RDD industry wouldinvolve six or seven rathermediocre months (the end ofMarch through August orSeptember) and five or sixrelatively strong months(September or Octoberthrough January orFebruary). The demand fromthe traditionally strongDecember quarter oftenextends into the new year.The spring doldrums usually

continued on page 36

letterletter

Areal density growth ratescontinue at thephenomenal rate of 60percent annually.Technologically, thisgrowth will continue withthe implementation ofGMR heads, as well aswith continued decreasesin the overall magneticspacing losses from flyheight, PTR, DLC coatingthickness, and mediaroughness. However, thereal challenge will be toengineer these improvedtechnologies intoproduction. From amanufacturingperspective, increasingareal density requiresgreater process control. Toachieve these goals, theuse of high volumemetrology tied back to

production processes cansignificantly improveyields in wafer, slidermachining, and HGA.Examples of value addedmetrology include 100percent PTR screening forimproved HGA yields andfeedback to the lappingprocess.

Magnetically, arealdensity is driven by thelimitations of minimizingthe length and width ofthe transition signal at themedia. Traditionally, thethree most basic signalparameters affecting arealdensity have been signalamplitude, pulse width(PW50), and overwrite.The Karlquist model forPW50, as approximatedby the following

On the Road to Increasing Areal DensityThe Role of Pole-Tip RecessionDonald Zipperian—VEECO Metrology Group, Dallas Meyer—SEAGATE Technology

In general, the data storage market is a technologydriven industry producing commodity products.Therefore, the most profitable companies are the onesthat can get to market the fastest with the latesttechnology, while maintaining control overmanufacturing costs. In particular, the data storageindustry has seen the rapid transition from inductivethin film technology to magnetoresistive (MR) and giantmagnetoresistive (GMR) technologies, as well as thetransition from the nano form factor to the pico formfactor. Successful implementation of these technologiesrequires tighter manufacturing tolerances. To achievethese goals, increased pole-tip recession (PTR) metrologyhas been used to improve costs by sorting bad headsprior to head gimbal assembly (HGA) build, binninghigher performance parts for the high end products, andto provide feedback for improving manufacturing yields.By combining optical metrology for measurement speedwith the accuracy of the atomic force microscope forcalibration, tighter PTR control is contributingsignificantly to enhanced hard drive performance andreduced manufacturing costs.

equation, shows theimportance of gap lengthand spacing:

PW50 = (g2 + 4(d + δ) *d)1/2

Where: g = gap lengthd = separation or spacingδ = media thickness

Note that gap length andmagnetic spacing are notmutually exclusive. Shortergap lengths require smallerspacing (conversely,reduced spacing lossesallow for shorter gaps tobe engineered), resulting inincreased areal densities.Therefore from a designpoint, narrower gaps arerequired to increase arealdensity. From amanufacturing point ofview, reduced spacing andnarrower signals increaseareal density.

In addition, loweroverwrite loss relates toless residual noise from theprevious signal, which inturn, means that a lowersignal strength is required.Overwrite is themeasurement used todetermine the noiseremaining from previouslyrecorded data (1) afternew data is written (2).

Overwrite = 20 log10 [V1(original)/ V1(residual)]

Where: V1 - voltage amplitude of original 1 signal

On the technology side,

the transition from thinfilm inductive heads tothin film MR heads andGMR or spin value headsare leading the technologyrevolution in data storage.These technologiesbasically allow increasedareal density to beachieved by increasing thesensitivity of readingtransitions. Simply put, theamplitude of the readsignal is increased, whileminimizing its pulse width(PW50). Manufacturingthese heads requires amore detailed examinationand control of themagnetic features, such asPTR, gap smearing, polesurface finish, and polelateral dimensions.

In addition to theincreased sensitivity of MRand GMR heads, magneticspacing continues todecrease. The emphasisover the past five years hasbeen to decrease fly height.However, fly heights arenow approaching less thanone microinch (25 nm)with the application ofautomated static attitudeadjustments (Figure 1). Atthese levels, fly height isno longer the onlysignificant variableaffecting magnetic spacinglosses (Table 1).

As areal densityrequirements continue toincrease, a closerexamination and controlof PTR, gap smearing,

surface finish, pole-trimdimensions, aluminarecession and roll-off,overcoat thickness,slider/media texturizing, aswell as fly height, will berequired.

Pole-Tip Recession (PTR)Pole-tip recession is one ofthe variables which hasnow become a significantcontributor to magneticspacing losses. PTR isessentially determined orcontrolled by the lappingprocess used to obtain theproper stripe height (MR)and/or throat height(inductive). The effect PTRhas on the basic electricalparameters is shown inTable 2 for an inductivetransducer. The gap lengthof this transducer was

1.6 m. As shown, a 0.6in. improvement in PTRimproved amplitude by25 percent, overwrite by28 percent, and PW50 bysix percent. Therefore,controlling PTRsignificantly improvedyield and areal density.

Successful lappingaccomplishes: proper MRsensor stripe height,proper slider flatness(crown, cross-crown,twist), minimal(controlled) PTR, scratchfree/ damage free poles(MR sensor), minimalalumina recession androll-off, no smeared metalacross the gaps andmagnetoresistive element(shorting) and unalteredmicrostructure at the pole

surface (dead layer). Inaddition, successfullapping eliminates orminimizes defects, such asembedded diamondabrasive contamination,air bearing surface orpole-tip chips and cracks,metal contamination andother lapping debris. Thebasic lapping process issimilar for mostmanufacturers in the datastorage industry;however, the subtledifferences can alter theresults. Several of thesevariables include thelapping platecomposition, diamondparticle size, diamonddistribution, diamondcarrier, lapping plateroughness, lapping plateflatness, row barfixturing, distribution ofthe diamond, charging ofthe diamond, lappingpressures and speeds,lapping direction,lubricant application,swarf removal technique,and the cleaning process.

Therefore, the variabilityin the lapping process canonly be practicallyreduced by providing afeedback loop based onmeasurements, such asPTR, pole-tip surfaceroughness, and aluminarecession. In the past, asmall sampling was

sufficient to provideacceptable feedback to thelapping engineers.However, the need forhigher sampling and 100percent PTR productiontesting is now beingrealized. Not only can 100percent measurement sortout the outliers prior togoing to HGA (Figure 2),it can also providefeedback to lapping andwafer manufacturing.

Further investigation ofthese wafers showed aPTR to alumina recession(ALR) correlationcoefficient of R2 = 0.71.This indicates that asignificant amount of thevariation in PTR can beattributed to the aluminaproperties. Figure 3ashows ALR for theacceptable PTR wafer andFigure 3b shows the ALRrecession for theexperimental unacceptablewafer. Intuitively thissuggests that themachinability of aluminaplays a significant role inpole-tip recession. Thiscorrelation suggests thatgood alumina propertiesprotect the poles fromlapping damage.Therefore, the hardnessand fracture toughness(brittleness) of the aluminadictates to a large degreethe ability to control PTR.

Source Magnetic spacing % Contribution

Flying Height 25-50 nm (1-1.5 µin) 40

PTR 0-20 nm (0-0.8 µin) 21

Disk Overcoat 15-20 nm (0.6-0.8 µin) 21

Slider Overcoat 10 nm (0.4 µin) 10

Disk Roughness 5 nm (0.2 µin) 5

Lubricant Thickness 2.5 nm (0.1 µin) 3

Table 1. Contributions to Magnetic Spacing

PTR = –0.13 µin PTR = -0.7 µin % Improvement

Overwrite (dB) -30.2 -23.6 28

High Frequency 442.3 339.6 30Amplitude HFTAA (µVpp)

Low Frequency AmplitudeLFTAA (µVpp) 644.8 532.1 21

PW50 (nsec) 18.7 19.8 6

Table 2. PTR Effect on Electrical Parameters

Mini Nano PicoInductive MR GMR

Metrology SamplingABS 2-3% Some 100% 100%PTR 2-3% most 100%

Figure 1. Technology Trends vs. Metrology Requirements.


Additionally, alumina hardness and brittleness are relatedto the wafer level alumina deposition process (rate,stoichiometry, gas content, etc.).

In the past, one to three percent PTR sampling was usedto verify the lapping process or for qualifying a lappingplates performance. With this strategy, only majorprocess changes could realistically be detected. Thissampling rate was, in part, due to the limited throughputand lack of automation on the initial PTR tools.However, with the significant improvements inautomated handling, improved algorithms for locatingthe poles and increased processing speeds of desktopcomputers, 100 percent PTR is now both feasible andeconomically justifiable.

One hundred percent pole-tip inspection (in addition tosorting and binning) is being used to improve lappingissues such as:• row bar fixturing (facets on the bar)• transfer tools tolerance (strip height control)• lapping plate texture (PTR, alumina recession, pole surface

finish, and lapping plate life)• lapping plate contamination (random scratching and pole

damage)• PTR variability over the life of a lapping plate

(performance distributions)

Figure 3. 2-Dimensional Alumina Recession (ALR) Mapping(color coding: green-acceptable, blue-marginal and red-

unacceptable). Figure 3a (top) show the ALR mapping anddistribution for the Process A wafer. Figure 3b (bottom)

likewise shows the ALR data for the wafer from Process B.Process B shows a much higher number of ALR rejects (red)

and marginal (blue) sliders as compared to Process A.

Figure 2. 2-Dimensional PTR Mapping (color coding: green-acceptable, blue-marginal and red-unacceptable). Figure 2a(top) shows that most of the sliders from production wafer

Process A have acceptable PTR values. Conversely, Figure 2b(bottom) indicates that experimental wafer Process B has a

significant number of failed or marginal PTR values.

• lapping plate profiles (lapping plate wear)• lapping loads, speeds, relative velocities and direction of

lapping (PTR, ALR, and pole surface finish)• effect of lapping plate composition and microstructure

(plate life stability)• size, shape, and distribution effects of diamond (cut rates

and surface finish)• other lapping machine parameters (machine to machine

variations and damaged ELG sensors)

With the use of statistical process control, the PTRyields, as well as the tolerances can be improved.

PTR can also be used to monitor pole corrosion resultingfrom improper cleaning or wafer level issues associatedwith plating of the pole(s). As the metallurgy of themagnetic heads becomes more sophisticated with GMRhead designs, monitoring process changes, such as thecorrosion of shared pole to base pole becomes moreimportant. For example, corrosion during cleaning hasbeen measured by monitoring the shared shield recession.By monitoring this recession, the effectiveness of thecleaning process can be monitored.

Clearly, there are many more lapping problems whichcan be studied in this fashion. With the ability to collect100 percent pole-tip data, the science and technology oflapping can be better understood and thus improved. In

Figure 3a

Figure 3b

Figure 2aFigure 2a

Figure 2b

continued from page 9

VeecoMetrology

Group

Ad3.5 x 10

the end, one hundred percent PTR analysis can provide atruly value added benefit to the production process ofthin film magnetic heads.

To sustain the trend in areal density growth rates,engineering and production tolerances will continue tostress the limits of manufacturing technology. Continuedimprovements in these tolerances will require greaterautomation control and expanded metrology feedback tothe production lines. One important source of feedback isthe measurement of pole-tip features. One hundredpercent pole-tip inspection not only provides quantitativeinsight into slider machining, it is also economicallyjustifiable based on eliminating bad heads prior to HGA.In the end, manufacturing processes can be improved andtighter design tolerances can be established for greaterproduct performance. ●

Donald C. Zipperian, Ph.D.—is the Director of Data StorageMarketing for the Veeco Metrology Group. Dr. Zipperian hasbeen directing the effort to convert data storage metrology froma sampling process to a 100 percent manufacturing inspectionand processes feedback tool.

Dallas W. Meyer, Ph.D.—is the Executive Director of Pre-Production Engineering for Seagate Recording Heads inMinneapolis, MN. Dr. Meyer has directed the processconversion from nano to pico series slider form factors and hasbeen instrumental in improving MR and GMR magnetic headperformance through improved slider manufacturing processes.

Specialty Tape Division250 Chester StreetPainesville, Ohio 44077800 262-2400440 358-3295 (FAX)www.averydennison.com

Tiny New Passive Current ProbeMeasures to 2 GHz Tektronix, Inc.introduces theCT-6, a tinypassivecurrent probeoffering the 2GHzbandwidth thatengineersdesigning readchannels andread channelcomponentsneed toaddress thedisk driveindustry’sever-increasing signal speeds and ever-shrinkingdrive sizes. The CT-6 measures a mere 4.3 milli-meters (0.17”) by 17.8 millimeters (0.7”), just onetwentieth the physical size of the Tektronix CT-1passive current probe. In the U.S., contact Tektronixat (800) 426-2200 or visit www.tek.com/measurement.

New Airnet Aerosol ParticleSensor Offers SuperiorData TransmissionParticle Measuring Systems (PMS)announced Airnet, a family ofaerosol particle sensors providingunmatched performance formeasuring contaminantscontinuously at multiple locationswithin a cleanroom environment.Airnet features a full range of sizingsensitivities starting at 0.2 microns,

and flow rates are available at 0.1 or 1.0 CFM forsampling in critical production areas. PMS offers afacility monitoring software package called Facility-View that provides a comprehensive account of theenvironmental conditions within a cleanroomenvironment. Contact Particle Measuring Systems at(303) 443-7100.

New WYKO SFT4500ª WaferSubstrate Flatness Inspection SystemVeeco Metrology Group announces the WYKO®

SFT4500™ Wafer Substrate Flatness InspectionSystem. This non-contact instrument is the firsttool to improve process characterization of thinfilm head wafer substrates by providing single-or double-sided measurement of global and siteflatness across 4.5” square wafer substrates. Thefully automated system determines global, aswell as user-definable local site flatness, such asRz, Rt, slope, and radius of curvature in a singlemeasurement. Contact Veeco Process Metrologyat (520) 741-1044 or visit www.veeco.com.

New Particle Test Chamber TestsCleanroom Garment SystemsThe Particle Test Chamber by M-ConTechnologies is used to perform the IEST ParticleContainment Test, also referred to as the BodyBox Test, for evaluating cleanroom garmentsystems. The chamber can also be used to testthe particle generating characteristics ofcleanroom chairs and various types of processequipment. Contact M-Con Technologies at (949) 380-7944.

Texas Instruments Acquires Assets ofAdaptecÕs High-End TechnologySolutions OperationsTexas Instruments has acquired the assets of thehigh-end technology solutions operation ofAdaptec, Inc. Located in Irvine, Calif., thisproduct development group is focused ondesigning high-end hard disk drive digitalsolutions, including servo, fiber-channel and SCSIinterface controller ICs, and developing systemsimulation software capabilities for disk drives. Aspart of the agreement, Texas Instruments willacquire ownership of intellectual property relatedto certain products and obtain a license toproperty relating to other products.Approximately 35 people from Adaptec’stechnical staff will become part of TexasInstruments Storage Products located in Tustin,Calif. Visit www.ti.com for more information.

100 CD-Rs Automatically with the CDMASSter InfinityªIntelligent Computer Solutions (ICS) introducedCD MASSter Infinity, a high-volume (100 CD-Rs),stand-alone, multi-drive automated CD-R softwareduplication system. The system contains four 4XMatsushita (Panasonic)recorders. Itautomatically loads andunloads CD-Rs using itstechnologically advanced

robotic pick-and-place mechanism. The CD MASSter Infinitycomes standard with a 4 GM internal hard disk for imagestorage. Call ICS at (818) 885-7500 or visit www.ics-iq.com.

Nano SP1 Software Expands NanoindentationTesting CapabilitiesMTS Systems Corporation introduced Nano SP1 Finite ElementModeling software, a program designed to improve thescientific community’s ability to quantitatively measuremechanical properties of extremely thin materials, such asthose used in disk drives, optical coatings, and semi-conductors. Call MTS Systems Corporation at (612) 937-4000.

New Automatic Head Wafer Mapping SystemThe DMS Division of ADE Technologies has developed a newAutomatic Head Wafer Test System that maps the magneticproperties of head wafers for MR, GMR, and Spin Valve headwafers; a critical measurement for head manufacturers. Thenew system combines high field capability with highresolution, and the ability to use low fields to measure, forexample, the exchange field. The high and low field capabilityis very important for measuring advanced spin valve headwafers. Designed as a non-contact, class 10 clean roomproduction tool for advanced head manufacturing, the systemmeasures the free and pinned layer coercivity using fields upto 8,500 Oe. Visit www.ade.com.

Instrumented Substrates Measure Temperaturein LCD and Memory Disk Processing SystemsSensArray Corporation announces Process Probe® 2030substrates, instrumented with an array of embedded

thermocouples, fordirectly measuringthe temperature andtemperatureuniformity ofsubstrates in liquidcrystal display (LCD)and memory diskprocessing systems.Direct substratetemperaturemeasurements andtemperature profiles

are obtained over the entire thermal cycle. Coupled withSensArray’s data acquisition and analysis tools, the ProcessProbe 2030 instrumented substrate is used to characterize aprocess, calibrate temperature set points, optimize systemdynamic response, and establish substrate thermal models formodel-based control systems. Contact SensArray at (408) 330-5614.

Veeco Metrology Group Announces KeyPromotionsVeeco Metrology Group announces the promotion of LloydLaComb to the position of vice president and generalmanager at their Tucson, Ariz., facility and Tami Balter todirector of marketing, for the WYKO line of semiconductorand industrial products.

Adhesives Research Expands Web SiteAdhesives Research announced the expansion of its Web site,http://www.adhesivesresearch.com. The new site offersvisitors comprehensive information about the company, itscustom and standard pressure-sensitive adhesives, and themajor industries and applications served.

Texwipe Opens Philippine ManufacturingFacilityThe Texwipe Company LLC announced the opening of its newCleanroom Products Manufacturing Facility-Philippines.Located in Cabayao, on the island of Luzon, Laguna Province,the new 45,000 square foot construction is dedicated to themanufacture of ultra-clean, cost-effective wipers, swabs andother cleanroom consumables. Official opening of the facilitytook place on Saturday, July 25, 1998.

SpeedFam Elects New President and CEOSpeedFam International, Inc. announced the election ofRichard J. Faubert as president and chief executive officer.Makoto Kouzuma, president since 1993 and chief executiveofficer since 1997, has been elected vice chairman ofSpeedFam’s board of directors.

Enthone-OMI Appoints Vice President, U.S.SalesEnthone-OMI Inc., a subsidiary of Asarco, announced theappointment of Mark D. Boivin to vice president, U.S. sales.

MTI Appoints Business Development andMarketing ManagerManufacturing Technology, Inc. (MTI), announced theappointment of Mitch Marvosh to business development andmarketing manager. Marvosh was formerly engineeringmanager for the company and brings to this position nearly15 years of professional experience.

Carnegie Mellon University Names DataStorage Systems Center (DSSC) InterimDirector Carnegie Mellon University Professor of Electrical andComputer Engineering (ECE) and ECE Department Head inthe College of Engineering Robert White has been namedinterim director of the Data Storage Systems Center. Whitereplaces former Director Mark Kryder who was appointed tosenior vice president and director of Seagate Research inPittsburgh, Penn.

Laser Marking on Hard Disk Media Wee Teng-Soon—Laser Research Inc.

A new technique of ablation-free, laser-induceddeformation has been developed to create visualcontrast on the finished hard-disk media, withoutdestroying the multi-layered structure of the media.This technique is well suited for creating ID marks fortracking purposes on rigid media. Laser marking doesnot cause any short-term or long-term contaminationproblems.

This article will describe the laser process, the opticaldesigns and the technical analysis of the technique. Theeffects of laser irradiation on the surface of the mediaare carefully examined using atomic force microscopy(AFM), scanning electron microscopy (SEM) and Augerelectron spectroscopy (AES). The main consideration indeveloping a suitable process for our application lies incontaining the laser-induced deformation, such thatany disruption to the multi-layered structure is kept toa minimal.

In recent years, hard disk surface processing with lasershas gained popularity. Laser pulses have already beensuccessfully used to create landing zones with improvedtribology performance for data transducing heads [1-3].Lasers have also been identified as viable tools for themarking or labeling of hard disk surfaces [4]. There areseveral occasions where disks need to be individuallylabeled. A hard disk, for example, may containmarkings indicating the number of reworks it hasundergone. This will help the drive manufacturers indeciding if a particular disk is suitable for furtherrework. Marking an individual disk not only helps toclassify the disk, but it also allows drive and mediamanufacturers to identify the product type and to tracethe origin of the disk should mixing occur. Mediamanufacturers can easily and reliably trace faults thatresult in disks failure if relevant information is tagged tothe disks. This will greatly enhance their processevaluation and monitoring work.

Disks are currently marked manually using a markerpen. As great care has to be taken not to contaminatethe marked disks, the marking process is tedious andslow. A more efficient method of marking is needed andlaser marking can provide one such solution to ourproblem. Laser marking has the advantages of precisionand speed over the conventional method. As will bedescribed in the subsequent sections, laser-inducedsurface deformation can be used to establish the

required visual contrast for the marking process withoutintroducing contamination to the disk surface.

Laser-induced deformation [5-9] plays important roles inthe laser marking process. While such deformation bringsabout the desired end results of the process, it can alsobring about effects undesirable for the process. It istherefore essential to have a clear understanding of themechanisms at work during laser-material interaction inorder to keep those effects undesirable for the process toa minimum.

Description of the laser-marking systemFigure 1 is a schematic diagram of the optical moduleused for the marking system. A diode-pumped Q-switched laser operating in the Gaussian mode andemitting at a wavelength of 1064 nm is employed. Thebeam expander alters the size of the beam to achieve thedesired beam spot size after focusing onto the disksurface. This final beam spot size on the disk surfacedetermines the actual beam intensity used to mark thedisk surface.

A processor unit controls the emission of the laser. Thebeam intensity used for the marking process isdetermined by the amount of attenuation imposed by avariable optical attenuator. The beam intensity ismonitored by sampling part of the beam into a detectorand power meter arrangement. By using such a beamattenuation arrangement, beam intensity can be variedwithout turning the control knobs on the laser powersupply. Beam power instability which is undesirable forthe marking process can then be avoided. An opticalisolator is also used to prevent unwanted reflection fromtracing back into the laser head.

Laser Shutter Sampler

Beam expansion,attenuation and

isolation

Beam power detectionand monitoring

Processor

Galvanometer

Hard diskmedia

Figure 1. Optical setup for the laser marking system


VTC Inc.

The laser marking processis carried out using agalvanometer. Thegalvanometer isresponsible for positioningand focussing the beamspot onto the stationarydisk surface. On receivingthe instructions from theprocessor, the laser beamis scanned across thesurface to inscribe thedesired patterns on thedisk surface.

As the laser beam is madeup of pulses, the scanningof the laser beam acrossthe disk surface results inthe formation of laser-induced dot-like marksaligning along the line ofscan (Figure 2). Byscanning the laser alongclosely-spaced multiplelines, patterns ofalphabets and numberscan be formed for labelingpurposes (Figure 3). Thespacing between twoadjacent marks is

determined by the laser Q-switch frequency and thebeam scanning speed. Thisspacing will subsequentlyaffect the visual contrastof the marked patterns onthe disk surface.

Process analysisThe optical module hasbeen optimized to inducemarks on the multi-layeredhard disk surfaces withoutundesirable effects. Processanalysis carried out haveindicated that, with asuitable laser power andbeam size, the differentmetallic surface layers stillremain intact after themarking process. Thesurface rippling inducedon the top surface bringsabout the visible contrastrequired for the markingprocess.

A finished disk has analuminum substrate; andabove this substrate arefive layers of differentmaterials. The topmostlayer is an organiclubricant with a thicknessof only a few nanometers.Below the lubricating layeris a carbon layer having athickness of about 10 to30 nm. This carbon layerserves as a protectivecoating for the magneticlayer underneath. Themagnetic layer is mainlymade up of cobalt. It alsocontains some amount ofchromium and small tracesof platinum and/ortantalum. Below themagnetic layer is achromium layer (100 to200 nm) followed by anickel phosphorus layer(10 m).

During a typical lasermarking process, thetopmost lubricating layerevaporates. However, thevisual contrast obtained

Figure 2. SEM image of thelaser marks formed on thedisk surface by a scanning

pulsed laser beam.

Figure 3. Characters formedon the hard disk surface using

the laser marking system.

(Figure 3) in the markingprocess is not due to theloss of the lubricatinglayer. In fact, similarvisual contrast has beenobtained on disks wherethe lubricating layer isnot originally present(Figure 4).

Figure 5 shows a typicalsurface morphologyinduced by the lasermarking process. Thelaser fluence used wasabout 1 J/cm2. A circularripple structure wasobtained. Such a structureis linked to the axial-symmetricalGaussian-shaped intensitydistribution of the laserbeam. The rippleperiodicity is around 1 to2 m. No micro-crackswere seen in the vicinityof the structure. In fact,the magnitude of surfacedeformation around therim of the ripple structuresubsides graduallytowards the non-irradiated region. A crosssection taken along line bin Figure 5 indicates thatthe central region is atabout the same level asthe disk surface level. Thecross sections taken alonglines a and c indicate thatthe rippling occurs quitesymmetrically about thedisk surface level. Thisimplies that the volume ofthe disk material wasmore or less conservedbefore and after laserirradiation.

Since the melting pointsof carbon (3800 K),cobalt (1768 K), platinum(2041 K), tantalum (3290K) and chromium (2130K) are all higher than thatof the nickel phosphorus(1200 K, [10]), the laserfluence used might haveonly melted part of the

nickel phosphorus layer,while the upper threemetallic layers stillremained reasonably solid.The interfacial stressexerted by the upper threemetallic layers acts as arestoring force controllingthe movement of meltednickel phosphorus. Withina confined space, thevolumetric change duringrapid localized meltingand subsequent re-solidification thereforebrings about the ripplingobserved.

In fact, AES depthprofiling (Figure 6)performed on thestructure in Figure 5indicates that the carbonlayer has remained verymuch intact. Theinterfaces between themetallic layers are stillwell preserved. The laser-induced deformation ofthis type has been limitedto the formation of thesurface rippling requiredin the marking process.

Using higher laserfluences, the laser-induced

Figure 4. Laser marking ona hard disk surface which

does not contain alubricating layer.

Figure 5. AFM Image


structure with a different surface morphology (Figure 7)can be obtained. Such a structure has a circular centralregion surrounded by an annular rippling region. At thecircular central region, one or more of the upper metalliclayers might have melted together with the nickelphosphorus layer. AES (Figure 7) performed on thesurface of the central region indicates the presence ofcarbon, cobalt and chromium. This implies that severemass diffusion and material mixing have taken placeduring laser irradiation. Due to the fact that the differentlayers have either been melted together or inter-diffusedinto one another, no rippling was obtained. Theinterfaces between different layers are therefore no longerdistinguishable. As the carbon layer, serving as aprotective layer for the disk, has already been mixed withother materials, such a laser-induced deformation canlead to potential disk failures.

The laser marking process performed on hard disks can,in general, produce two kinds of surface deformation.Under sufficiently high laser fluence, the process canresult in severe inter-diffusion and melting of the uppermetallic layers. As the protective carbon layer has alsobeen melted, this can lead to possible reliability

problems. On the other hand, with suitably low laserfluence, the marking process can bring about thenecessary surface rippling without destroying the carbonlayer. ●

Figure 6a

Figure 6b

Figure 7. AES is performed on the surface at three locations,namely (a) the centre of the central region, (b) the rippling

region and (c) a non-irradiated region. The results show that atlocations b and c, only carbon is detected on the surface layer.On the other hand, a mixture of carbon, chromium, and cobalt

was found at the surface of location a.

Figure 6. AES depth profiling performed on (a) the structure ofFigure 5 and (b) a non-irradiated region on the same disk

specimen. The results indicate that the carbon, the magnetic,the chromium and the nickel phosphorus interfaces are still

preserved beneath the surface after laser marking.

Teng-Soon's research interest lies in the application of laser formaterial processing. He has previously developed numericalmodels for the laser etching of semiconductor materials. Hiscurrent work involves the use of laser on hard disk surface formarking purposes.

References

[1] T. D. Bennett, D. J. Krajnovich, C. P. Grigoropoulos, P.Baumgart and A. C. Tam. J. Heat Trans., 119, 589 (1997).[2] P. Baumgart, D. J. Krajnovich, T. A. Nguyen and A. C.Tam. IEEE Trans. Magn., 31, 2946 (1995).[3] R. Y. Ranjan and D. N. Lambeth. “Selectively texturedmagnetic recording media”, United States Patent No. 5,062,021dated 29 Oct 1991.[4] T. S. Wee, L. B. Koh, D. M. Liu, Y. Yuan, Y. F. Lu, J. K.Goh and K. T. Chang. “Laser marking on multi-layered hard-disk media”, patent pending.[5] M. Von Allmen. “Laser-Beam Interactions with Materials”,Springer Ser Material Science, Vol 2. (Springer Berlin,Heidelberg 1987) Chapter 2, p 41.[6] S. Lugomer. “Laser Technology: Laser Driven Processes”,Englewood Cliffs, N. J. : Prentice Hall 1990, Chapter 7.[7] J. E. Sipe, Jeff F. Young, J. S. Preston and H. M. van Driel.Physics Rev. B 27, 1141 (1983).[8] J. F. Young, J. S. Preston, H. M. van Driel and J. E. Sipe.Phys. Rev. B 27, 1155 (1983).[9] J. F. Young, J. E. Sipe and H. M. van Driel. Phys. Rev. B 30,2001 (1984).[10] K. Merchant, P. Mee, M. Smaliem and S. Smith. IEEETrans. Magn., 26, 2688 (1990).

Special thanks to Lighthouse WorldwideSolutions for sponsoring IDEMA's recenteducation classes in Singapore and Penang.

thank youthank you

January12 (on-going): Register now for Evergreen Valley College'sThin Film/Disk/Disk Drive Technology program. For moreinformation, call (408) 270-6490.

18-21 The International Symposium on Product Quality &Integrity, Washington Hilton & Towers, Washington, DC. Formore information, call Joan Harpham (847) 255-1699.

19 Deadline for ESD Symposium Call for Papers. Call SethAyers at (408) 330-8109 for more information.

19 Silicon Valley EOS/ESD Society Meeting, Ramada Inn,Sunnyvale, Calif. Cocktails 4:30 p.m., Dinner 5:30 p.m. andPresentation 6:00 p.m. For more information, visitwww.esdsv.org.

9 IEEE Magnetics Society Santa Clara Valley Chapter SeminarSeries, Quantum Corporation, Milpitas, Calif. Cookies andconversation at 7:30 p.m. Presentation at 8:00 p.m. For moreinformation, call Steven Stupp at (408) 324-7261 or send e-mailto [email protected].

19-21 Disk Drive Technology class, Santa Clara, Calif.Class instruction by KnowledgeTek. For more information, call(303) 465-1800 or visit www.knowledgetek.com.

25-26 Servo class, Longmont, Colo. Class instruction byKnowledgeTek. For more information, call (303) 465-1800 or visitwww.knowledgetek.com.

22-29 Technologies for Optical Disk Storage & RetrievalConference, San Jose Convention Center, San Jose, Calif. Anadvanced technical program co-sponsored by SPIE and IDEMA.For more information, call SPIE at (360) 676-3290 or visitwww.spie.org.

26 Register for San Jose State University’s continuingeducation class on Magnetic Materials and RecordingTechnology. For more information, call 1-888-999-SJCE and askabout MatE 297-03.

February1-3 The Write Process class, Santa Clara, Calif. Classinstruction by KnowledgeTek. For more information, call (303) 465-1800 or visit www.knowledgetek.com.

4 IDEMA Quarterly Dinner Meeting featuring Todd Bakar,Hambrecht & Quist, Santa Clara Westin, Santa Clara, Calif.Registration and no host cocktails at 6:00 p.m. and dinner at7:00 p.m. For more information, call IDEMA at (408) 330-8100.

4 The Write Process – Advanced Topics class, Santa Clara,Calif. Class instruction by KnowledgeTek. For more information,call (303) 465-1800 or visit www.knowledgetek.com.

5 Deadline for discount on IDEMA Membership Renewal. CallDebbie Lee at (408) 330-8108 for more information.

8-10 The Write Process class, Longmont, Colo. Classinstruction by KnowledgeTek. For more information, call (303) 465-1800 or visit www.knowledgetek.com.

10 GMR Heads and Media Symposium, Santa Clara Westin,Santa Clara, Calif. For more information, call IDEMA at (408) 330-8100 or visit www.idema.org.

11 The Write Process – Advanced Topics class, Longmont,Colo. Class instruction by KnowledgeTek. For more information,call (303) 465-1800 or visit www.knowledgetek.com.

16 IEEE Magnetics Society Santa Clara Valley Chapter SeminarSeries, Quantum Corporation, Milpitas, Calif. Cookies andconversation at 7:30 p.m. Presentation at 8:00 p.m. For moreinformation, call Steven Stupp at (408) 324-7261 or send e-mailto [email protected].

16 Silicon Valley EOS/ESD Society Meeting, Ramada Inn,Sunnyvale, Calif. Cocktails 4:30 p.m., Dinner 5:30 p.m. andPresentation 6:00 p.m. For more information, visitwww.esdsv.org.

23 IDEMA class, Disk Drives 101: What’s in the Box? Offeredat the IDEMA office in Santa Clara. To register, call LindsayBrown at (408) 330-8103 or visit www.idema.org.

23 IDEMA class, Building a Disk: An Introduction to Thin FilmMedia Manufacturing. Offered at the IDEMA office in SantaClara. To register, call Lindsay Brown at (408) 330-8103 or visitwww.idema.org.

24 IDEMA class, An Introduction to MR Head Technology.Offered at the IDEMA office in Santa Clara. To register, callLindsay Brown at (408) 330-8103 or visit www.idema.org.

24 IDEMA class, Building a Head: Understanding Thin FilmHead Manufacturing. Offered at the IDEMA office in Santa Clara.To register, call Lindsay Brown at (408) 330-8103 or visitwww.idema.org.

Do you know of a storage event or meeting that would be ofinterest to INSIGHT’s readers? Send your industry calendar itemsto [email protected].

speed famDATATECH Ad

Over the past 11 years, Ron has encouragedstorage professionals to take an active role inthe development of the data storage industry. Hehas recruited design engineers, operationspeople, and sales and marketing executives toparticipate in one or more of IDEMA’s manycommittees.

“Prior to IDEMA’s standards meetings andquarterly dinners, industry professionals did nothave a forum in which to share and discuss theircommon issues,” explained Ron. “Today,engineers and scientists come together atstandards meetings and workshops to exchangeinformation and to develop new standards tobenefit the industry.”

Ron served on the board of directors from 1986to 1997, and was granted director emeritusstatus in September 1997. He has over 25 yearsexperience in the data storage industry, and iscurrently working as a consultant specializing inheads and media issues.

IDEMA recognizes Ron for his dedication andleadership in developing an association rich invalue and integrity.

IDEMA co-founder and former MembershipCommittee Chairman Ron Dennison has activelyworked to help build IDEMA into the successfultrade association it is today.

As one of the eight founders, Ron has had theopportunity to be involved with several of IDEMA’sinitial events, including the first planning, board ofdirectors, and standards meetings. He alsoorganized and hosted the first quarterly dinnermeeting in 1986. The industry dinner was well-received; about 60 storage professionals were inattendance. Soon thereafter, Ron established adinner committee and served as its chairman forten years.

In 1994, Ron was elected chairman of theMembership Committee, and held this position untilDecember 1998. Under his leadership, IDEMAmembership grew to more than 800 corporate andindividual members worldwide. The growth inmembership was due in part to Ron’s diligence inenhancing the value of IDEMA membership. Someof the member benefits he helped to create, includethe Membership Directory, discounts on DISKCONbooth fees, and the World Map Calendar.

“IDEMA membership is really essential for anyonein the disk drive industry,” said Ron. “Theassociation offers a unique communicationschannel that encourages networking and fostersindustry growth. The opportunities to learn aboutthe data storage market and technology areunparalleled at IDEMA symposia, workshops,dinner meetings and DISKCON.”

In 1994, Ron was

elected chairman of

the Membership

Committee, and

held this position

until December

1998. Under his

leadership, IDEMA

membership grew to

more than 800

corporate and

individual members

worldwide.

Ron DennisonFormer Membership Committee Chairman

Getting to Higher Data Rates: The Flex System Greg Lee—VTC Inc.

We are moving into a new era. Ever increasing data ratesmean that careful consideration of high frequency effectson flex circuits is necessary to obtain the best performancefrom the preamp and the system it functions in. Thepurpose of this article is to provide insight into a few of themany issues we are or will be encountering as the requiredbandwidths increase toward the microwave region.

BypassingProper bypassing of preamp pins becomes much morecritical at high frequencies. Noise, writer performance,stability, and mode switching times can all be degraded byimproper bypassing. Using present rules of thumb, a datarate of 450 Mb/s would require a preamp read bandwidthof approximately 300 MHz. Consider a 0.01 uF ceramicchip bypass capacitor. Ideally it has a reactance of 0.05ohms at 300 MHz. If we look at the inductance of thetraces and bond wires connecting the capacitor to thepreamp, 5 nH is a reasonable estimate of the inductance ofthese connecting traces in series with the capacitor (on atypical flex circuit). At 300 MHz, the inductive reactanceof 5 nH is nearly 10 ohms. The capacitor has someinternal series inductance which adds to this. This totalseries inductance effectively decouples the capacitor fromthe circuitry it is supposed to bypass. In general, the largerthe capacitance, the higher the internal series inductance.Thus, in some cases, more bypass capacitance mayimprove low frequency effectiveness, but degrade highfrequency effectiveness. Several vendors offer capacitorswith reduced internal inductance (0.5 nH vs. 1.0 nH for atypical ceramic chip capacitor). Additionally, the use ofbumped die may allow closer placement of bypasscapacitors and consequently more effective bypassing.

Extraneous CouplingControl of extraneous coupling also becomes moredifficult at high frequencies. This can appear asoscillation, noise, poor mode switching behavior, orcrosstalk. Coupling from the signal lines between thepreamp and channel can be problematic, often appearingas stability-related problems. This is often due to the lackof a ground plane under this portion of the flex circuit,which can help suppress radiated fields (ground planesare not used here due to mechanical reliability issues).There are ways to improve the situation. Signal linesbetween the preamp and channel are almost alwaysdifferential. Differential systems have good commonmode rejection. Common mode induced coupling is whatwe usually need to worry about. To maximize commonmode rejection, the differential lines need to be

symmetrical or balanced. That is, each trace needs to havethe same characteristic impedance as its partner. Asfrequencies increase, this balance becomes harder tomaintain. Adjacent traces can affect characteristicimpedance and coupling; therefore, signal-carryingdifferential pairs need space between themselves andadjacent traces to minimize unwanted coupling. Groundedtraces can isolate the signal carrying pairs from nearbytraces. While these also provide some isolation fromunwanted coupling, their use requires some care.Grounding these “guard” traces at both ends can createground loops and act as inductive pickup loops, whichmutually couple noise into other flex traces. Anotherpotential problem is that at high frequencies the groundtraces can resonate and actually become antennas.

Traces Become Transmission Lines When the electrical length of the signal traces becomes asubstantial fraction of the signal wavelength, then thesignal traces become transmission lines. Transmission linescannot be accurately modeled as “lumped" circuitelements. An ideal transmission line has a characteristicimpedance that stays constant with length over a widerange of frequencies. If resistance is introduced into theline this impedance becomes a function of frequency. Asfrequencies increase a number of resistance terms becomemore important, making the transmission line behaviormuch different from the ideal case.

How the transmission line is “matched” to its source andload affects its behavior in passing signals. Well matchedsystems generally have better bandwidth characteristics and better group delay performance (i.e., less write pulsedistortion). Poorly matched systems can have undesiredresonances, bandwidth reduction, increased chance ofinstability, pulse distortion, etc. All of these could affect the bit error rate performance.

A perfectly matched system may not always be desirable or achievable, as it will deliver one-half of the sourceamplitude to the load. In a head/preamp system, one-halfthe signal will make it from the head to the preamp. Thismay create signal-to-noise issues, for which theimplications are not always intuitively obvious. Let’s lookat an MR head/interconnect/preamp system. In many cases,the media noise and the thermal noise of the head are thedominant noise sources. In a perfectly “matched” systemthese will be attenuated along with the signal. But there are other noise sources, such as amplifier noise sources,


Disk/Substrates CommitteeNext Meeting: TBD (check www.idema.org)

Revised standards for the 84mm and 95mm rigiddisk were recently approved. The Committee isworking on a proposal for standardizing thechamfer angle (45 degrees) and a definition for diskwaviness.

Lube Thickness & Control Stop Start(CSS) Testing SubcommitteeNext Meeting: January 29, 9:00 a.m. – Noon

The Subcommittee is working on a set of terms anddefinitions for lube thickness, CSS, and laser bumpheights. Three standards are also underdevelopment: Method for Measuring the Thicknessof Bonded Lubricant on Disk; Lubricant MeasurementMethod; and Bulk Characterization Method.

Disk Magnetics SubcommitteeNext Meeting: February 4, 9:00 a.m. – 11:00 a.m.

The Subcommittee is currently performing a DiskMagnetometer Pilot Study. The Study has threegoals: 1) Determine single-lab and multi-labcorrelation of magnetometers on selected samplesamong a limited number of laboratories; 2) Supportdevelopment of an IDEMA magnetometer testmethod for magnetic remanence, coercivity andremanent coercivity; and 3) Determine need for full-scale round robin test using the new test method.The initial results will be presented at the nextmeeting.

Optical Inspection SubcommitteeNext Meeting: January 14, 9:00 a.m. – NoonWorkshop: February 11, 9:00 a.m. – Noon

The charter of this new subcommittee is toinvestigate and evaluate the applicability of opticalinspection for characterization and measurement of

Checkwww.idema.orgfor upcomingIDEMA Standardsmeetings andagendas.

All meetings areheld at the IDEMAOffice—Directionsat www.idema.org

rigid substrates and finished disks, as well as forproduct and process evaluation and monitoring.The Subcommittee is currently developingterminology and definitions, optically-based testmethods, procedure for evaluating and monitoringsubstrate/disk products and processes, andmethods for producing and tracing defects.

Emitted Shock & Vibration CommitteeNext Meeting; February 23, 9:00 a.m. – Noon

The charter for the Committee is to create a usefulspecification which defines the vibration and shockenergy emitted by a storage device andtransmitted to the housing supporting the device.At the December 15 meeting, George Henderson,GHI, presented measured emitted shock andvibration data taken from samples of some recenthigh capacity drives. The presentation included adescription of the test setup and an interim reporton data taken. The Committee projects that theresults of this test activity will form the basis foran emitted shock and vibration test procedure.

Environmental, Health & Safety (EHS)CommitteeNext Meeting: TBD (check www.idema.org)Workshop: February 17, 9:00 a.m. – Noon

The Committee is developing a proposal formeasuring power consumption of a hard disk drive(i.e. watts per gig). The committee is also workingto establish several standards: EHS Terms &Definitions; EHS Questionnaire; and WaterRecycling.

Attend the Water & Air Workshop on February 17at the IDEMA office from 9:00 a.m. to Noon. Theworkshop will focus on regional and internationalmanufacturing of HDDs, disks, and heads.

Workshop agenda available on-line atwww.idema.org.

HDD Reliability CommitteeNext Meeting: January 27, 9:00 a.m. – Noon

The Committee is working on developingdefinitions for AFR and AFP, and BenchmarkReliability Tests for HDDs used in the desktop andportable computer market. They are alsodeveloping an AFR Summary document thatcontains philosophy and mathematics regardingAFR, AFP and ARR.

IDEMA’s Standards Program has grown to morethan eight committees and ten subcommittees/taskforces worldwide covering critical issues facingthe data storage industry today. Members areencouraged to take an active role in thedevelopment of industry standards by attendingmeetings and participating in technical symposiaoffered throughout the year.

Heads CommitteeNext Meeting: February 9, 9:00 a.m. – Noon

The Committee has developed two standard proposals: FemtoTransducer and Femto Bond Pad Location. These two proposalsare currently under review and will be on the ballot in early1999. The committee is also working on creating standards forFemto Pinout Locations and GMR Pinout and Head ElectricalConnection.

ESD SubcommitteeNext Meeting: January 20, 10:00 a.m. – 3:00 p.m.

The first meeting was held on November 11. The Subcommitteebegan work on four proposals: 1) MR and GMR Heads – ESDTesting; 2) Tweezers; 3) General Practices with GMR / MR Heads;and 4) ESD Materials for MR and GMR Heads. At the nextmeeting, the four proposals will be reviewed.

Femto Head-Substrate SubcommitteeNext Meeting: TBD (check www.idema.org)

The Subcommittee is working to develop a Femto Head-Substrate standard.

Rowbar Carrier SubcommitteeNext Meeting: TBD (check www.idema.org)

The Subcommittee is developing a rowbar carrier standard forthe Femto head generation.

Microcontamination CommitteeNext Meeting: February 4, 9:00 a.m. – 2:00 p.m.

The Committee recently approved four new standards:Extractable Ionic Contamination Test Method; General OutgasTest Procedure by Dynamic Headspace Analysis; ParticulateContamination Test Methods for Hard Disk Drive Components;and Special Cations Analysis. At the December 3 meeting, theCommittee established two new subcommittees. The first,Cleanroom Contamination, will focus on creatingrecommendations for cleanroom specifications (i.e. particulatecount and size requirements). The second, Lab Correlation, willfocus on developing a lab correlation procedure.

Cleanroom Contamination SubcommitteeNext Meeting: February 2, 9:00 a.m. – Noon

Lab Correlation SubcommitteeNext Meeting: February 3, 9:00 a.m. – Noon

Lube Thickness & CSS Testing SubcommitteeNext Meeting: January 29, 9:00 a.m. – Noon

Disk Magnetics SubcommitteeNext Meeting: February 4, 9:00 a.m. – 11:00 a.m.

Optical Inspection SubcommitteeNext Meeting: January 14, 9:00 a.m. – NoonWorkshop: February 11, 9:00 a.m. – Noon

Emitted Shock & Vibration CommitteeNext Meeting: February 23, 9:00 a.m. – Noon

Environmental Health & Safety (EHS) CommitteeWorkshop: February 17, 9:00 a.m. – Noon

HDD Reliability CommitteeNext Meeting: January 27, 9:00 a.m. – Noon

Heads CommitteeNext Meeting: February 9, 9:00 a.m. – Noon

ESD SubcommitteeNext Meeting: January 20, 10:00 a.m. – 3:00 p.m.

Microcontamination CommitteeNext Meeting: February 4, 9:00 a.m. – 2:00 p.m.

Cleanroom Contamination SubcommitteeNext Meeting: February 2, 9:00 a.m. – Noon

Lab Correlation SubcommitteeNext Meeting: February 3, 9:00 a.m. – Noon

2860 Zanker Road, Sui te 205 San Jose , CA 95134ph 408.434.1100 fax 408.434.1101

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which will not beattenuated. The effect ofamplifier current noise isdependent on matching andon flex circuit parasiticeffects. These parasiticeffects can be due to headbond wires,

preamp bond

wires, flex traces, deviceinput capacitance, etc. (seeFigure 1).

Parasitic effects become agreater issue as frequenciesincrease. While thereactances themselves donot create noise, currentnoise running through themwill create a frequencydependent noise term thatincreases the noise at thepreamp input. In addition,the transmission line(interconnect) sees theseparasitics as a significantpart of the source and loadat high frequencies. Theseparasitics can become the

limiting factor in achievingthe desired bandwidthperformance (see Figure2). Carefully consider thesignal path between thepreamp and channel asthis may be as importantas the path between theheads and preamp.

Voltage Sense or CurrentSense?A frequently asked questionis: Which of the sensingmethods, voltage orcurrent, will be the mostviable at future data rates?The input resistance of thepreamp reader plays a largerole in bandwidth andmatching. For voltagesense, the input resistance isfairly high (greater than 50ohms and can be 500 ohmsor greater). Current senseinput impedances are muchless than 50 ohms (typically2-10 ohms). Either scheme

should be workable to greater than 500 MHz bandwidthwith proper flex design. Noise tradeoffs also affect whichsensing scheme works better in a given situation.

One potential problem is control of MR head resistance,which is the source impedance. If it changes, thebandwidth and noise characteristics of the read systemwill also change, sometimes drastically. Accommodatingthe expected range of head resistances will become aneven more critical design goal as frequencies increase (seeFigure 3). Thus, there is no one preferable sense method.Careful modeling and measurement will help determinewhich works best in a given situation.

What About Writers?The writer portion of the flex system raises issues, whichare more difficult to deal with than the reader systemissues. For instance, the frequency components necessaryto sustain < 1 nS write pulse risetimes extend well past 1GHz. This is far higher than any reader bandwidths wecan expect to see in the near future. In addition, a writehead is a non-linear load whose inductance changes withcurrent and frequency, greatly complicating impedancematching of the load to the interconnect. As in the reader,parasitics have a greater impact as frequencies rise. Whilechip-on-suspension techniques may solve someinterconnect problems, they do not solve the bypassingproblem—and may make it more difficult. This is becausea limited number of components can be placed on thesuspension. There can also be pulse integrity issues due tothe write pulse reflecting off the head and returning to thesource (write driver) early enough to cause destructiveinterference. This should not be a problem in a properlydesigned system. Many believe the real answer to theseissues is alternative writer topologies.

There are a number of issues we will need to confront toaccommodate higher data rates. Measurement, modeling

HEAD FAN IN FLEX PACKAGEBONDWIRES PREAMP

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0.87n

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Figure 1: Model of Head, Interconnect, Preamp Subsystemand Parasitics

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0dB

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-8dB

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100MHz 300MHz 500MHz 700MHz 900MHz

The graph is a system model with a 100 ohm interconnect, characteristicimpedance, 50 ohm head, die on flex, and a voltage sensing preamp:

Red: Base model shown in Figure 1, 340 MHz bandwidth.Blue: Bonded die with flex, fan-in and packaging parasitics removed, 400MHz bandwidth.Green: Matched system with bumped die, 520 MHz bandwidth

GREEN = 520 MHzBLUE = 400 MHzRED = 340 MHz

Figure 2: Effect of Varying Factors on Model Bandwidth

Figure 3: Effect of Varying Head Resistance on Reader Bandwidth


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The graph is a system model with a 100 ohm interconnect, characteristicimpedance, die on flex, and a voltage sensing preamp:

Solid: 30 ohm head, 520 MHz bandwidth, undesirable peaking present.Dashed: 50 ohm head, 460 MHz bandwidth.Dotted: 70 ohm head, 400 MHz bandwidth.

GREEN = 70 OhmsBLUE = 50 OhmsRED = 30 Ohms

speed famSpeedFam Ad

7.5 x 5

As I poke through my free copy of INSIGHT, ("free" is a very important to we retiredpeople) seeing names and faces of former associates, nostalgia overcomes me, and I feelthe need to comment on my favorite technology industry.

You are not doing too well! Your three most significant industry activities during 1998 havebeen a 25GB drive for the desktop, a new disk drive company formed by Finis Conner,and firing Al Shugart. Each of these illustrate one of the industry's three basiccharacteristics. You have over capacity, you never quit, and you have no respect.

Personally, I like your first two characteristics. First, over capacity. With 25GB in my PC, Ishould be able to find at least a couple of sectors that I can actually read and write data on.

Second, without Finis active in the business, who would there to be to throw a reallyclassy party at Comdex? (Which, mercifully, I no longer attend).

I do not like the lack of respect. But, in the early 1980s, Al Shugart confided to me hethought the best personal financial security he had was his vested $200 a month IBMpension. I am pleased that he can now re-evaluate that.

For a serious note. I spend most of my time in volunteer work, mainly at senior centers inthe valley. I congratulate you on your activities devoted to charitable and communitywork. We desperately need to shake more than pocket change out of the business andtechnology community for community and charitable works of all kinds.

Warm regards to all my friends.Angelo Forlenza—[email protected]

letterto the editorand prototyping arebecoming very importantin creating flex systems inwhich the preamp canfunction to the best of itsability with the othersystem components.Prototyping at the frontend of a project becomesextremely important forearly identification ofproblems and allows thepreamp vendor toprovide timely assistance. ●

Greg Lee is currently aPrincipal ApplicationsEngineer with VTC . He has12 years experience in thedisk drive industry and waspreviously employed byMagneticPeripherals/Imprimis/Seagate andApplied Magnetics. Heholds a BSEET fromSouthwest State University(1980).

letter

Technology trends in high performance rotationalmagnetic recording systems include high data access andtransfer rates, high track densities (up to 25,000 TPI bythe year 2000), and system robustness, particularly inserver and portable applications. These trends requirespindle motors running at speeds more than 15,000 rpmwith a non-repeatable runout (NRRO) of less than 1.0micro inch. The following problems are associated withhigh RPM operation: 1) High frequency repeatablerunout (RRO) in one of several unbalanced spindlemotor configurations, 2) Elevated NRRO, 3) Sharpacoustic noise levels, 4) Excessive heat, 5) Aero-dynamically excited vibration of disks and actuator armsand head stack assembly (HSA), and 6) High currentelectronics. This article will address these high rpmoperation problems and will provide some designsolutions.

Fluid Film Bearing Spindle Motor Some hard disk drive (HDD) companies today aredeveloping high speed, up to 15k rpm, hard disk driveswith ceramic ball bearing spindle motors. Key issues withball bearing spindle motors are performance, reliability,and endurance. Non-repeatable runout, acoustic noise,and bearing induced resonance are also major concernswith ball bearing spindle motors. Information on how tosolve these issues is not publicly available at this momentin time. An alternative is the hydrodynamic bearingspindle. This spindle has many advantages over the ballbearing spindle, including low NRRO, moderate acousticnoise, better non-operational shock resistance, greaterspeed control, and increased damping of spindle motorstructure modes.

With areal density increasing at a rate of 60 percentannually and track density doubling every two years, theNRRO requirement will soon be at the sub-microinchlevel (Table 1). If disk fluttering at high speeds issubstantially reduced by utilizing either smaller platters,disks with enhanced stiffness, or media laminated with adamping layer, the NRRO budget might be increased tofour percent track pitch. The ball bearing spindle motorcan still be used in high performance hard disk drives fortwo to three years. It might be risky to make such aprediction if the assumption is only based on the NRRObudget. The departure of ball bearing spindle motorsfrom HDD applications may take place even sooner if theacoustic noise level in future high speed spindle motorsremains the same as or drops below the current noise

Future High Speed Spindle and Componentsfor Hard Disk DrivesChen Shi-Xin, Liu Zhe-Jie, Low Teck-Seng, and Zhang Qi-De—Data Storage Institute, Singapore

level. Therefore, the fluid film bearing spindle motor will bean indispensable commodity in future high performancehard disk drives.

There are three types of lubricants for fluid bearings: gas,liquid, and grease. The air-lubricated bearing is attractivebecause the difficulty of lubricant sealing is circumvented.However, the spindle motors with fully aerodynamicbearings have lower load capacity and bearing stiffnesscompared to those with liquid or grease lubricatedbearings. Moreover, the fully aerodynamic bearings do notprovide conductive paths for discharging the static electricalcharges accumulated during hard disk drive operation. Onthe other hand, the spindle motor with fully hydrodynamicbearings have a high bearing loss of about 25-35 percentof the total power input to the spindle motor. The runningcurrent is increased by a comparable percentage due to thebearing loss – it equals or exceeds the allowed value inelectronics chips available on the market today. Non-contact seals for both journal and thrust bearings aredifficult to design and implement. To overcome the above-mentioned problems, a hybrid hydrodynamic andaerodynamic bearing may be a good choice. In this fluidbearing system, air is used as lubricant for the conicalthrust bearings which have a spiral groove. Oil is used as alubricant for the journal bearings which feature aherringbone groove. This hybrid hydrodynamic andaerodynamic bearing system has about 70 percent of thepower loss of a fully oil-lubricated bearing system.

Year 2000 2002 2004

Gb/in2 10 25 64

KBPI 400 500 800

KTPI 25 50 80

Track Pitch-TP (µm) 1.016 0.508 0.3175

NRRO (µm/min) 0.02/0.8 0.01/0.4 0.00635/0.25(2%TP)

NRRO (µm/min) 0.04/1.6 0.02/0.8 0.0127/0.5 (4%TP)

Platter size (in) 2.5 2.5 2.0

Spindle speed (krpm) 15-20 20-25 20-25

Latency (ms) 2-1.5 1.5-1.2 1.5-1.2

Data Rate(Mb/s) 800-1060 1300-1620 1660-2080

Table 1. Predicted spindle speed, NRRO, and data rate requirements

However, the fullyaerodynamic bearings arethe best choice for highspeed spindle motordesigns.

Optimized ElectromagneticDesignInteraction between thestator lamination with anodd number of teeth, exceptfor 3(2k-1), and the magnetwith an even number ofpoles gives rise to anunbalanced radial magneticforce. This is caused by therotational asymmetricalstator structure. Figure 1shows the loci of theunbalanced radial magneticforce appearing in an 8-pole/9-slot 7,200 rpmspindle motor. Thisunbalanced radial magneticforce rotates at eight timesthe spindle speed, but in theopposite direction of therotation. The force is alsofluctuating eight times inone revolution. Runningcurrent has littlecontribution to theunbalanced radial force.Measured from a stationaryprobe, the repeatable runout of the spindle motor infrequency domain has ahigh peak at 960 Hz – eighttimes the spindle rotationalfrequency at 120 Hz.Position error signal (PES)

measured in a disk drivewith this type of motoralso has this harmoniccomponent at anirremissible level.

Table 2 illustrates how theincrease of spindle motorspeed causes a highfrequency RRO and PES.These frequencies aredifficult to control withtoday’s servo systems.Therefore, an 8-pole/9-slotconfiguration and otherunbalanced configurationshave become less popular,while balancedconfigurations, such as 4-pole/6-slot, 6-pole/9-slot,8-pole/12-slot, and 12-pole/9-slot are becomingfavorable choices. The 6-pole/9-slot configurationhas been adopted byseveral major HDDcompanies in highperformance disk drives.

The balancedconfigurations areassociated with a muchhigher cogging torquethan the unbalanced 8-pole/9-slot configuration.Effective parameters usedfor reducing coggingtorque are the pole-arc topitch-ratio of the magnetand stator tooth shapingand skewing of eithermagnet poles or statorteeth in the motor.Skewing is notrecommended for lowprofile or slim-line spindlemotors due to processdifficulties. Moreover, itmay be the source of axialvibrations in the spindlemotor and casingstructures.

Spindle motor iron loss isprimarily dependent onthe square of themultiplication of thespindle speed (inrevolution per second) and

the number of pole pairsin the motor. Iron losscompared to copper loss isdominant in high speedspindle motors. Figure 2shows the normalized ironloss vs. rpm for spindlemotors with 9-slots and avaried number of poles.Figure 3 illustrates the ironlosses of spindle motorswith 8-poles and adifferent number of slots.As shown, a spindle motorwith fewer pole pairs andslots have less iron loss.Therefore, the balancedconfigurations, 6-pole/9-slot, 8-pole/6-slot, and4-pole/6-slot are thepreferable choices for highspeed spindle motors. Forhigh speed spindle designs,the following motorconfigurations arerecommended: • 6-pole/9-slot• 4-pole/6-slot• 8-pole/6-slot• Slot-less stator• Iron-less stator

Effects of High RPM onOther ComponentsFor a fixed voltage supply,the torque constant of ahigh speed spindle is very

Spindle speed (rpm) 7,200 10,200 15,000 20,400

Spindle rotational 120 170 250 340frequency (Hz)

Frequency of RRO 960 1,360 2,000 2,720caused by UMF (Hz)

Table 2: Frequency of RRO caused by unbalanced radialmagnetic force (UMF)

Figure 1. Loci of theunbalanced radial magnetic

forces appearing in an 8-pole/9-slot 7,200 rpm

spindle motor for high enddrives. Solid curve: nocurrent applied. Dashed

curve: A running current of0.78 A is applied.

small. The running currentis increased significantly toproduce sufficient torqueto overcome the diskwindage and fluid filmbearing frictions increasingat a rate of twice tothreefold the spindle speed.For a high-end drive withseveral platters, therunning current is up to1.0 - 1.5 Amperes or morefor a 12 V supply. Thecurrent specs of a staringcurrent less than 2.0Amperes will have to bepushed up. Otherwise, thestaring torque would beabout two times therunning torque and thestaring time would bemuch longer. Even worsethe spindle motor will notbe started up if the quasi-static friction torque of thespindle bearings and thehead air bearing is high,and the motor coggingtorque is not wellcontrolled in its design.Therefore, the spindle drivechips are required to takehigher current and PWMcontrol is implemented inthe spindle drive. Switchinghigher current at higher

Figure 2. Normalized iron loss vs. rpm for the 9-slot spindlemotors (same size)


Figure 3. Iron loss vs. rpm for the 8-pole spindle motors (same size)

frequency may cause severe electro-magnetic interferenceproblems in the control logic circuit which is integratedwith the inverter bridge. Therefore, the electronicsrequire separate chips for the spindle driver and inverter,with regard to either the heat or EMI issue. This start-upissue of a high rpm spindle motor probably willnecessitate more R&D efforts in new control algorithmsand chip implementation.

The rate of data transfer between magnetic media andelectronics and among electronic components isdependent on linear recording density and spindle speed.By the year 2000, the bit density will be 400Mb/inch(Table 1). Figure 3 compares data rates to spindlespeeds. As spindle speeds and areal densities increase,R&D efforts in high rate media, read/write heads,electronics, and mechanics will be intensified.

Higher electronics loss due to high data rates is anadditional contribution to heat generation in a drive.Total power consumption in a high performance, highspeed drive with several 2.5 inch or 2 inch platters willnot be less than a 3.5 inch drive with lower spindlespeed. To meet the same temperature rise specs, a 2.5inch drive still needs a heat dissipation area comparableto a 3.5 inch drive. Therefore, the casing size for the 2.5inch drive will be similar to that of the 3.5 inch drive. Inthe future, a 2 inch drive may still have a 3.5 inch formfactor casing. As a result, there will be more room for apowerful voice coil motor (VCM) actuator! A powerfulsingle stage VCM actuator with high bandwidth

structures may be designed and used in higher TPI, say,25K TPI or higher servo systems.

Further R&D Efforts In high speed disk drive design, it is critical that effortsare made to reduce friction losses from windage andbearings, minimize disk and actuator structure fluttering,and balance the spinning mass. Further R&D is neededin the areas of high rate electronics, air flow andspacing, mechanical structure design, materialdevelopment, as well as in the processes ofmanufacturing, assembly and testing. ●

References 1. S.X. Chen and T. S. Low, “Some Considerations in theDesign of High Speed Spindle for Hard Disk Drives”,Proceedings of IDEMA’s Beyond 10 Gb/in2 Symposium, 10 June1998, the Decathlon Hotel, Minneapolis, MN USA. 2. S.X. Chen, "Designing Spindle Motors For High-performanceDrives", Data Storage Magazine, November/December 1996, pp39-44.3. Schirle and D.K. Lieu, “History And Trends In TheDevelopment Of Motorized Spindles For Hard Disk Drives”,Digests of the Asia-Pacific Magnetic Recording Conference,Singapore, 1995.4. Zhang Qide, Chen Shixin and Liu Zhejie, “Design of AHybrid Fluid Bearing System for HDD Spindles”, APMRC’98,Suntec City Convention Centre, Singapore, July 29-31, 1998.5. S.X. Chen, Q.D. Zhang, Z.J. Liu, H. Lin, "Design of FluidBearing Spindle Motors With Controlled Unbalanced MagneticForces", IEEE Transactions on Magnetics, Vol.33, No.5,September 1997, pg4317-4319.6. S.X. Chen and T.S. Low, “Analysis of Spindle MotorPerformance Sensitivity to Excitation Schemes”, IEEETransactions on Magnetics, Vol.34, No.5, September 1998,pg4317-4319.7. Z.J. Liu, S.X. Chen and Q.D. Zhang, “Design of BrushlessDC Spindle Motors for High Speed HDD Recording”, IEEETransactions on Magnetics, Vol.34, No.5, September 1998,pg4317-4319.8. S.X. Chen, T.S. Low, and B. Bruhl, “ The Robust DesignApproach for Reducing Cogging Torque in Permanent MagnetMotors”, IEEE Transactions on Magnetics, Vol.34, No.4, July1998, pg2135-2137.

Figure 4. Data rate vs. rpm and platter diameter (BPI= 400Mb/inch)

Take advantage of IDEMA’s expanded benefitsand services for 1999 by joining or renewingyour membership in the only international tradeorganization serving the data storage industry. Formore information on membership, call Debbie Leeat 408.330.8108 or send e-mail [email protected].

Errigo Executive Search GroupRichmond Technology, Inc.Rudolph Technologies


IDEMA membersn e w

MTI Ad

Q When was the Emitted Shock and VibrationCommittee (ESAV) formed?

A In 1997, the Disk Drive Handling Committeewas completing its work on establishing trainingmaterials and guidelines for protecting disk drivesfrom shock and vibration during handling. At oneof the meetings, I was asked to look into theproblems of shock and vibration caused by thestorage devices.

In large disk arrays, rotational vibration and shockimpulses from seek operations can adversely affectthe operation of other drives in the cabinet. Thesubject appeared inappropriate for the HandlingCommittee. At the conclusion of the committeework in early 1998, it was suggested that IDEMAcreate a new committee to examine emitted shockand vibration issues. The ESAV Committee wasformed in early 1998, and the first meeting washeld in March.

Q Why do you think the ESAV Committee isimportant?

A The shrinking mechanical dimensions of everincreasing recording densities reduce the toleranceof storage devices to shock and vibration.Unfortunately, the demand for increasedperformance has caused storage devices togenerate higher and higher levels of emitted shockand vibration. In applications incorporatingmultiple storage devices, the shock and vibrationemissions of one unit can adversely affect theoperation of other units.

The ESAV Committee hopes to create proceduresfor measuring and describing emitted shock andvibration, so that it can be controlled below acritical threshold. It is my hope that measurementmethods will result from the committee’s activities.With measurement tools, it may also be possible toestablish emitted shock and vibration guidelines.

Emitted Shock & Vibration Committee

Q What are some of the main goals for 1999?

A The Committee has three goals. The first is toestablish a theoretical foundation for emittedshock and vibration. The second is to developmeasurement methods to quantify emitted shockand vibration. The third is to describe deviceoperating modes to be used duringmeasurements. We hope to complete a draftprocedure sometime in 1999.

Q What has the Committee accomplished?

A The Committee has heard a number ofpresentations on emitted shock an vibration.Under the auspices of the Committee, GHISystems, Inc. has undertaken a project to makepreliminary tests on some sample disk drivesprovided by Seagate. The first-run results werepresented at our last meeting on December 15.

Q Who should participate in the Committeeand why?

A We hope to see strong participation fromdrive manufacturers and system integrators. Thekey to the Committee’s success relies uponcreating drive metrics’ that are useful to systemdesigners and supported by drive manufacturers.

Q Is the Committee lacking participation froma particular area?

A At the present time, we would like more helpfrom individuals skilled in the technical aspects ofemitted shock and vibration. There is a lot ofindustry knowledge about the effects andmeasurement of applying mechanical shock andvibration energy to a storage device, but emittedenergy appears to be a new area.

An interview with Committee Chairman JackClemens, Winchester Storage, Inc.

The Emitted Shock and Vibration Committee has asked GeorgeHenderson, president of GHI Systems, Inc., to produce andmanage a test plan aimed at measuring emitted shock andvibration of hard disk drives during seek operations. The datafrom this project will be used to develop a standard method forcharacterizing the emitted shock and vibration from hard diskstorage devices. In addition, drive designers will use thisinformation to develop server bay hardware, which willattenuate emitted shock and vibration.

The test plan is based on work in other industries where thistype of characterization has been taking place for severalyears. In the space industry, for example, this technology hasbeen used in the CASINI space probe and the Hubble SpaceTelescope planetary camera.

Henderson states that GHI Systems will measure the sourcespectral impedance of the hard disk drive when it is operatingin the worst case mode – during seeks. Impedance heads, atype of sensor, will be utilized to measure the drive’s combinedforce and acceleration rates. These specialized sensors arebeing loaned to IDEMA for the project by Kistler and Dytran.The high capacity drives used in the study are provided bySeagate.

The study involves attaching the hard disks to a large seismicmass. The impedance heads are used as coupling devices. Thedrives have been modified to enter a random seek mode whenpowered up. To accurately capture and analyze the resultingvibration data, GHI Systems will use some of their own datacapturing methods and analysis equipment for the project.

“When the drives are running,” said Henderson, “our datasystem will record both the forces and accelerations from theimpedance heads (four to six channels in parallel).” Theresulting digitized data will be processed to obtain severalforms of analytical results, including PSD’s, CSD’s, and thespectral ratios between the physical measurements from the twotypes of sensors. This will yield apparent mass and spectralimpedance.

Preliminary projects results will be reviewed at the next ESAVCommittee meeting scheduled for February 23 at 9:00 a.m. atthe IDEMA office in Santa Clara.

LaserResearch Ad7.5 x 5

GHI Systems to run ESAV test projectHigh capacity drives tested for emitted shock and vibration.

10 Gb/in2 Slider ManufacturingShanlin (Stanley) Hao, Ph.D.—Seagate Recording Heads

Head manufacturers arefaced with many challengesin the production of sliders.Increased areal density inmagnetic recording has leadto smaller designs of thesensor element, and stripeheights of 0.5 mm. In orderto establish adequateelectrical performance, it isrequired to achieve thespecified sensor height orMRE resistance target witha very tight tolerance. Tominimize the spacing loss,flying heights are reachingsub-minch level. Control offlying height variation iscritical to achieving thehead mechanical andelectrical performance.Efficient and reliable headperformance also requires asmooth finish on the airbearing surface (ABS).

In addition, higherwafer/bar densificationdriven by the requirementof improving productionthroughput and reducingthe manufacturing cost haslead to smaller, thinner,more flexible bars andsliders (full size, 70 series,50 series, 30 series, 20series). Bar shape and sliderABS profile are now moresensitive to process induceddisturbances, such asmechanical residual stressesfrom machining andthermal stresses frombonding. To meet highdensity head designrequirements and maintainprocess yield capability,head manufacturers mustreduce sensor heightvariation, improve thesurface finish, and reduce

the slider flatnessvariation.

Wafer FactorsMR/GMR transducers aretypically produced usingthin film depositiontechniques. In a typicalprocess, an array oftransducers are formed ona common substrate(square or round) throughwafer processing. Duringslider machining, thesubstrate is sliced toproduce bars. The bars arelapped to a specifiedsensor height target orresistance. After diamond-like carbon (DLC) coatingand advanced air bearing(AAB) processing, the barsare diced to produceindividual sliders.

Feature positioningvariation and growthcharacteristics duringwafer processing directlyaffect the final sensorheight variation. Figure 1shows the edge movementmeasured by an ElectricalLapping Guide1 (ELG) atthe wafer probe for tworows across a 4”x4” wafer.A complete wafer map isshown in Figure 2 for theinitial ELG error. Toimprove the sensor heightcontrol capability, featurealignment and growthvariation have to beminimized. It is also notedfrom Figure 2 thatdiscontinuities exist acrossstepper fields for featuresize and alignment. Tominimize the stepper fieldeffect on the sensor height

variation, matching lengthbetween the bar andstepper field is preferredfor slider processing.

SlicingWafer slicing introducesresidual stresses on the barsurfaces. Figure 3 showsthe bar curvature as afunction on ion-milletching depth for theetched side of the bar. Theresidual stress is normallycompressive and about 1-2mm deep. The magnitudeof this stress is a functionof slicing process variables,such as wheel condition(diamond size, binderhardness), wheel thickness,spindle speed, feed rate,cutting depth, and coolingcondition; all of whichchange constantly duringslicing. As a result, theresidual stress is non-uniform and varies fromone bar to another.

The effect of non-uniformslicing residual stresses ona bar is that the featureline on the bar is no longer“straight” (bar bow) in thefree bar status. The barbending stiffness is in acubic relationship to thebar thickness. Significantlyhigher bar bow magnitudeand higher order variationare observed whencomparing the bar bowdistributions after slicingbetween 30 series bars and50 series bars. To minimizethe slicing residual stressmagnitude and variation,process optimization onslicing is required. Double-

sided lapping, ion-milling orannealing is oftenintroduced in slidermachining as an extra stepto minimize the slicinginduced stress and itsvariation.

BondingThe bar is normallymounted on a transfer toolthrough a thermally orchemically activatedbonding process beforelapping. The bonding stressuniformity is anotherdifficult parameter to

Figure 1. Feature edgemovement of two rowsacross a 4”x4” wafer

Figure 1. Feature edgemovement of two rowsacross a 4”x4” wafer

Figure 3. Characteristics ofslicing induced residual stress

Figure 2. Wafer map of initiallap resistor error

control. It is dependent on the adhesive property (surfacetension, wetting characteristics, cure temperature),thickness uniformity, thermal cycle profile, interfacegeometry (waviness and roughness) and transfer toolproperty (thermal expansion coefficient). Due to thebonding stress variation, the feature line shape measuredoptically after bonding is different from that in the freebar status. The reduced stiffness from the smaller bars(50%, 30%, 20%) results in an increased variation instress.

Lapping—Sensor Height ControlLapping establishes the sensor height or resistance target,which is defined by the distance between the ABS and theback edge of the sensor elements. A technique known aswafer lap minimizes the effects of slicing and bonding onthe sensor height variation. The technique involveslapping the exposed ABS of a wafer to the sensor heighttarget before slicing individual bars from the waferserially. Wafer lap takes advantage of the bar straightnessat the wafer level and eliminates non-uniform bondingstress. During lapping, side-to-side pressure adjustment isintroduced to compensate for the linear-type sensor heightvariation. Wafer lap, however, is not able to compensatefor wafer processing induced feature variation and lapplate surface profile variation. The lap plate surfaceprofile is dynamically changing throughout the life of theplate. It is affected by plate preparation,charging/conditioning, lapping kinematics (RPM,oscillation profile), surface texture change, and wearcharacteristics. A conditional ring with profiled pressureadjustment is often used to minimize the plate flatnessvariation.

The dynamic nature of lapping dictates a real-time, closed-loop bar lap process to control the sensor height. Onecommon practice is to use an ELG and an on-line barbending mechanism [2, 3]. ELG’s are fabricated with actualMR transducers through the same wafer processing. Theycan predict sensor height. Based on the correspondingprofile, the system can compensate the sensor heightvariation by adjusting the bending mechanism.

As the slider form factor continues to decrease (50%,30%, 20%), bars become thinner and more flexible.There are more sliders per bar, and the bar shape is moresensitive to processing induced disturbances. To maintainand improve the sensor height control capability, moreactive control points are required during lapping. Figure 4shows the comparison of the sensor height variation for a30 percent bar between five and nine control points. It isbased on FEM modeling. The results indicate that thelapping process requires an independent slider control.

Lapping—Surface FinishLapping process conditions affect the finished ABS surfacequality (PTR, scratch, smearing). According to the systemkinematics, lapping processes can be classified into twobasic types: figure-8 motion and planetary motion. In a

figure-8 motion lapping system, the workpiece held on anarm oscillates on a rotating plate to ensure uniformlapping. The combined motion normally results in lappingacross the gap between the MR element and shields. In aplanetary motion lapping system, the self-spinningcapability of the workpiece holder promotes lappingparallel to the gap. The ABS texture and surfaceuniformity are affected by lapping kinematics. Figure 5shows Dual Stripe Magnetoresistive (DSMR) heads infigure-8 and parallel motion. To minimize smearing,kinematics promoting lapping parallel to the gap ispreferred for the bar lap process.

Lapping processes can also be classified according to thetype of abrasion, including free abrasive lapping and fixedabrasive lapping. Free abrasive lapping involves theapplication of diamonds suspended in a liquid carrierbetween the plate and the workpiece. Fixed abrasivelapping uses plates charged with diamonds and abrasive-free lubricant at the workpiece/plate interface. As shown inFigure 6 for the measured ELG signal comparison betweenfree abrasive lapping and fixed abrasive lapping, it is notedthat loose diamond particles tend to produce moresmearing (therefore worse PTR and surface finish) in thepole tip region. Fixed abrasive lapping is normally used forproducing the final slider ABS finish.

Other surface finish related lapping process variablesinclude plate material, plate configuration (flat/grooved),

Figure 4. Real-time closed loop lapping control simulation

Figure 5. Lapping kinematics and surface finish: left—parallel motion

right—figure-8 motion


plate flatness/surface texture, plate charging/conditioning,slurry size, pressure, speed (RPM), and environment(temperature, contamination). Slurry vehicle type andproperties (viscosity, pH level) also affect the surfacefinish. Water based slurry is normally used for its easycleaning and disposal, but it can corrode GMR elements.Oil based slurry produces a better surface finish, but itcan create lower material removal rates andcontamination issues.

As the surface finish requirement gets higher (PTR lessthan 0.1 µm), lapping process optimization is required.Surface quality is normally affected by the degree ofplastic deformation during the material removal process.In general, use of lower lapping pressure and smaller sizeof diamond slurry improves PTR and surfacesmoothness. However, surface finish optimization oftencomes with the compromise of process throughput.

Flatness ControlLapping produces the slider air bearing surface. Thesurface profile (crown, cross-curve, twist, flatness) isaffected not only by the lapping process variables, suchas plate surface profile, plate leveling, arm/machinedynamics, lapping pressure and kinematics(RPM/oscillation), but also by the stress condition onboth air bearing and non-air bearing surfaces. The ABSstress condition is affected by lapping and DLC/AABprocessing, and the non-ABS stress condition is affectedby slicing (or lapping) and bonding.

As the slider gets smaller and thinner, the ABS profile is

more sensitive to the process induced disturbances. Tocontrol the slider flatness variation, processoptimizations on slicing, bonding, lapping, AABpatterning and dicing are required. In many cases,additional process steps are introduced in slidermachining to reduce the stress and its variation. Forexample, double-sided lapping, ion-milling or annealingare often used to improve the non-ABS uniformity. To improve the slider flatness control capability, activeadjustment of the stress condition on the slider ABS ornon-ABS surface is preferred. For example, localizedlaser annealing can introduce tensile residual stresses anddiamond scribing can introduce compressive residualstresses. As the specifications for crown, cross-curve,twist and flatness get tighter, more active, independent,real-time, and closed-loop flatness control processes areneeded.

Efficient and reliable head performance for the advanceddesign of high areal density MR and GMR headsrequires very good process control of slider parameters,such as sensor height (resistance), surface finish, andflatness. The shrinking slider form factor has lead tosmaller/thinner bars and sliders with significantlyreduced stiffness. Sensor height control, surface finishand flatness control of slider machining are now moresensitive to process induced disturbances. Improvingprocess capability with cost effective solutions presentscritical challenges to slider engineering and technologydevelopment. ●

Shanlin (Stanley) Hao is a manager of slider mechanicaldevelopment at Seagate Recording Heads (Bloomington,Minnesota). He received a Ph.D. in mechanical engineeringfrom University of Minnesota. The author would like to thankhis colleague Lanshi Zheng for wafer probe data in Figure 2and Ray Moudry for surface finish pictures in Figure 5.

References1. Lance Stover, Beat Keel & Shanlin Hao, “Machining GuideMethod for Magnetic Recording Reproduce Heads,” U.S.Patent 5,722,155, March 19982. Douglas Hennenfent, Allan Holmstrad, & Alan Kracke,“Precision Lapping System,” U.S. Patent 4,536,992, April19853. Douglas Hennenfent, Allan Holmstrad, & Alan Kracke,“Workpiece Carrier,” U.S. Patent 4,457,114, July 1984

Figure 6. Lapping abrasion type and surface finish: a: freeabrasive, b: fixed abrasive


Reach the industry’s key decision makersthrough IDEMA’s Web site, www.idema.org.Take advantage of IDEMA’s low-cost Webadvertising opportunities today! To have yourcorporate message seen by the industryprofessionals worldwide, contact Nicole Flynnat (408) 330-8107.

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appear by mid-March, andoften “April is the cruelestmonth, breeding/Lilacs out ofthe dead land,mixing/Memory and desire,stirring/Dull roots with springrain”—to quote T.S. Eliot’sdismal (the lines march to thestately rhythms of anautopsy), yet ironicallybeautiful evocation of the“season of rebirth” from TheWaste Land.

The great allocations of1991/1992 and1996/1997 ended duringthe spring months. In bothApril 1992 and April 1997,RDD prices began todestabilize because of asudden decrease in demandthat caused inventories to beregarded as ”surplus” ratherthan “inadequate to meetmarket needs.”

In a good year, the RDDindustry may experience onlyone weak quarter, one or twostrong quarters, and one ortwo exceptional quarters inwhich the supply/demandpendulum swings heavilytoward the demand side. Anno Domini 1996 was justsuch a year. Initial RDDforecasts for 1996 were inthe 112 to117 million range,

but inadequate supplies ofmedia and heads, resulted ina shipment of 106.8 milliondrives. Actual worldwidehunger was probably for108 to 111 million drives in1996, creating a near-perfect (and highlyprofitable) supply/demandbalance that lasted throughthe first months of 1997.Precipitous price erosionsceased after May 1996 andpricing in all channelsremained relatively stableuntil March 1997. Virtuallyall drive makers reportedexemplary earnings during1996 and early 1997. Thestock prices of manypublicly-held RDDmanufacturers andcomponent vendors soaredto unprecedented levels.

It was an extraordinary year,but the glories of 1996 werefollowed by one of the worstyears in the history of thedrive industry. In 1997, RDDshipments grew to 128.3million, but real globaldemand was probably in the117 to119 million range. Toexacerbate the problem,there were more than 12million unshipped RDDsstacked in manufacturingand channel warehouses at

the end of December 1997(according to Dataquest’sconservative estimates). Thethree market share leaders(Seagate, Quantum, andWestern Digital) postedcombined net losses of$434.2 million in the lasthalf of calendar 1997; ayear in which overall unitshipments (not counting theremaining inventory)expanded by more than 20percent. This proved, onceagain, that the effects ofoverproduction can beruinous.

In 1997, too many drivemakers ignored the realgeographies of global needand greedily grasped at theevanescent grail of marketshare gains. The excesses of1997 generated globalmarkets in which RDDs wereconsistently undervalued.During the first three quartersof 1998, the industry mostlyfound itself mired in afamiliar quandary of beingunable to make decent anddeserved profits on itsamazing ability to deliveralmost magical advances intechnology.

As we entered the fourthquarter of 1998, Dataquest

began to see someprofoundly hopeful signs. Atthe highest executive levels,the industry seems to be farmore willing to rememberthe painful past and isstriving to transform itswasteful ways.

It is as if the drive makerscast a cold eye on theirmanifold strategic errors andsaid, “Another ‘victory’ likethat and we’re done for. Thishas got to change.” Andperhaps it will.

The Beginning of theEnd of a Chaotic CycleDuring the fourth quarter of1997, in December, pricedeclines wereuncharacteristically high. Theanticipated fourth quartersurge in demand and itsattendant allocation of keyproducts, which effectivelybalanced the industry’sbooks in 1995 and 1996,did not occur last year.Industry inventories were toolarge and too widespread;

Manufacturers Estimated 6/30/98 6/30/98. 6/30/98 Estimated 9/30/98 9/30/98 9/30/98Ranked by Total Q2/98 Estimated Mfg. Channel Estimated Q3/98 Estimated Estimated EstimatedQ3/98 Shipments Shipments Inventory Inventory Inventory % Shipments Mfg. Channel Inventory %

of Shipments Inventory Inventory of Shipments

Seagate 6,848.0 1,765.0 1,625.0 49.5 7,140.0 1,349.0 1,325.0 37.5Quantum 5,640.0 1,345.0 1,081.0 45.0 6,142.0 1,095.0 948.0 33.3Western Digital 4,383.0 498.0 875.0 30.0 4,580.0 719.0 795.0 33.1Subtotal for Top 3 16,871.0 3,608.0 3,581.0 42.6 17,862.0 2,813.0 2,858.0 34.9IBM 3,998.0 239.0 419.0 16.5 4,507.0 195.0 339.0 11.8Maxtor 3,750.0 279.0 281.0 14.9 4,317.9 769.0 245.0 23.5Fujitsu 3,075.6 269.0 235.0 16.4 4,007.9 189.0 197.0 9.6Subtotal for Next 3 10,823.6 787.0 935.0 15.9 12,832.8 1,153.0 781.0 15.1Samsung 2,142.0 203.0 198.0 23.7 2,117.0 119.0 88.0 9.8Toshiba 1,310.0 119.0 87.0 15.7 1,410.0 65.0 32.0 6.9Hitachi 535.4 93.0 68.0 30.1 699.1 35.0 29.0 9.2Other Vendors 245.0 74.0 80.0 62.9 148.0 19.0 35.0 36.5Subtotal for Others 4,232.4 489.0 433.0 21.8 4,374.1 238.0 184.0 9.6Totals 31,927.0 4,884.0 4,949.0 30.8 35,068.9 4,554.0 4,033.0 24.5Source: Dataquest (November 1998)

Table 1. Estimated Q2/98 and Q3/98 RDD Inventories (Thousands of Units)

The sleep of reasonbrings forthmonsters.— C.P. Snow



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involving too many different product categories, and demandwas simply not large enough.Channel and manufacturinginventories of RDDs and personal computers have steadilydeclined since March 1998. Unlike last year at this time, wheninventories were severely distended, the rate of price declinesis diminishing and the fourth quarter 1998 RDD market shouldexhibit its “normal” (or perhaps even greater than “normal”)double-digit rate of growth.

More importantly, all the major drive makers now seem to beremembering the recent, excruciating past and are exercisinga sanely disciplined restraint in the face of acceleratingdemand. If this mature and prudent trend continues it couldlead to some lucrative and lasting effects on RDD industryearnings.

Recent Shipment and Inventory Changes Table 1, provides asnapshot of estimated global inventories relative to secondquarter and third quarter 1998 shipments.

According to Dataquest estimates, overall third quarter 1998shipments increased 3.142 million units (almost 9 percent)over second quarter 1998 shipments. Fourth quarter forecastsfrom server, RAID, and PC OEMs remain strong and—at thetime of this writing (November, 1998)—continue to grow.Drive makers are reporting very healthy book-to-build ratios.Fourth quarter 1998 RDD shipments should be in the range of40 million units, and total 1998 shipments could exceedDataquest’s conservative forecast of 138.5 million units byseveral million drives.

The most compelling news is the shrinkage in inventory.Dataquest estimates that inventories as a percentage ofquarterly shipments declined more than 6 percent (to 24.5percent) at the end of September 1998 (compared to 30.8percent the end of June 1998). Estimated manufacturing andchannel inventories at the end of March 1998 were 31.3percent (10.530 million units) of quarterly shipments. Estimatedmanufacturing and channel inventories at the end of December1998 were 35.3 percent (12.058 million units) of quarterlyshipments. Estimated manufacturing and channel inventories atthe end of September 1998 had decreased 3.416 million units(more than 28 percent) from the end of December 1997, whilethird quarter 1998 shipments (35.069 million) exceeded fourthquarter 1997 shipments (34.148 million) by nearly a milliondrives. Some manufacturing inventories remained high at theend of September 1998 because of the just in time (JIT)delivery requirements of all major PC OEMs. Recent reportsindicate that both manufacturing and channel inventoriessubstantially diminished during October and November 1998and that demand is increasingly robust in all channels.

For the first time in many quarters, demand is high andinventory is relatively low. The fourth quarter of 1998 shouldgive all drive makers a chance to rebound from tough times.The question is—How long will these halcyon days endure?

Creating Sustainable ProfitsFrom a viewpoint of technology and value, the RDD industryregularly performs wonders. The sales organizations may be


ferociously contentious, butRDD technical marketing andengineering teams havemostly managed tocooperate, deepeningexisting markets andexpanding the potential fornew markets by creatingtimely new interfacestandards that offersubstantial speed and dataintegrity enhancementscombined with backwardcompatibility. In spite ofsometimes fierce rivalries, thedrive makers haveaccelerated the rate of RDDindustry standardization.And against enormous odds,the drive makers havequickened their alreadyastonishing pace of arealdensity advancement;legitimizing a product roadmap that promises shippableRDD designs with greaterthan 10,000 Mb/in2 arealdensities during the year2000.

From a market managementand profit perspective, theRDD industry has seldomdone well for very long andhas often performedabysmally, overproducingwith a regularity that rivalsthe seasons’. In fairness, itshould be said that it isstaggeringly difficult tomaintain an appropriatebalance of supply anddemand. The dynamics ofsurplus and allocation thattend to determine overallindustry earnings aresensitively dependent onmercurial (and unpredict-able) market conditions.Even very small changes inproduction or sales cyclescan have very large effectson pricing stability.

We now seem to be at theend of a painfully protractedchaotic cycle. Inventorieshave greatly diminishedsince December 1997 anddemand is robust. Allocationand a temporary pricestabilization seem near athand.

The duration of a fourthquarter allocation—inconjunction with the extent ofthe global hunger for thedrive configurations affectedby allocation—hashistorically had a hugeimpact on the industry’sannual earnings. If the drivemakers pay attention to thepast and temper theircollective tendencies towardexcess, the surplusinventories that causeinordinate price erosionsmight be kept in the future toa tolerable minimum; if thisoccurs, we should see someemerging RDD markets inwhich consistent profits canbe made.

At the very least—whileeffective cost-managementdisciplines are beingimplemented by virtually allRDD manufacturers, and thememory of monstrouslydisruptive markets in 1997and 1998 remains fresh witha power to inspire rationalrestraint—the drive makersnow have an opportunity togenerate new marketdynamics that could lessenthe severity of their futurelosses and augment theirfuture profits.

With this hopeful prospectin mind, Dataquest makesthe following recommend-ations and observations:

The drive makers shouldforget about “braggingrights” and put aside theirdifferences and implement auniversally acceptable newversion of SCSI.

The drive makers should alsohelp to standardize andimplement advanced andeasy-to-use “drive OK/drivenot OK” diagnostic routines.Anything that can attenuateend-user frustration andreduce the cost of needlessreturns will serve to increaserespect for and satisfactionwith the industry’s products

and should improveindustry wide earnings.

The industry should doeverything in its power toprevent a recurrence of thesurplus inventories thatgenerated such dismal mid-1997 to mid-1998 marketconditions. Competitive, yetresponsible buildmanagement is certainly aprofound step in the rightdirection.

No immutable law of natureordains that RDD pricesmust decline to dangerouslyunprofitable levels everyquarter; people (in the guiseof product line managementand sales executives)authorize RDD pricereductions.

Product line managers, whoare mostly responsible forpricing decisions in thisindustry, have to deal witha stupefying quantity ofdisinformation. It is alwayshard to judge the differencebetween a necessary and afoolhardy price reduction,because customers (andsalespeople) are prone tostrategic falsehoods. Excessunsold drives stacked in thewarehouse exacerbate theproblem, and thedesperation caused bysurplus inventories andchaotic markets often leadsto erroneous pricingdecisions. But times ofproduct allocation grantclarity and perspective, andthe industry discovers(rather, re-discovers) thatcustomers in variouschannels will pay a higherprice for RDD products ifthese products cannot befound at a lower price.

Allocation always preventsRDDs from being sold atdesperately discountedprices.

In the RDD industry, wars ofattrition have beenrepeatedly tried and haverepeatedly failed to create

profitable market conditionsfor the surviving suppliers.

Profitable supply/demandbalances usually becomeevident in September orOctober and tend to endduring the spring months.

Beware the Ides of March.

Monroe’s Law: As soon asthe RDD industry cansuccessfully ramp productionrates to fully satisfy anapparent increase indemand, the demandslackens, and healthy book-to-build ratios tend todisappear. Whenever theindustry can actually test thereality of a large backlog,the backlog dissipates (oftenwith disastrous results). Whythis happens is a mysteryand a matter of some debate(to Dataquest’s mind, it isanalogous to Heisenberg’sUncertainty Principle), but ithappens with disturbingfrequency.

It is almost always wiser tobuild with skeptical cautionin the face of a burgeoningdemand. The balance ofprofitable inventory andrevenue ratios is a delicateone and can be quicklydisrupted.

RDD manufacturers can fulfilldemand, but they cannottruly create it.

The widespread use of newInternet, multimedia, digitalimaging, and voicerecognition applications iswhat will create quantumleaps in future storagerequirements.

Magical escalations in RDDareal density will play acrucial role in enabling thedissemination of newtechnologies that requireenhanced capacity, but theywill not, in and ofthemselves, generate newcapacity needs.

The speed and cost-effective use of Internet pipelines will bemanaged to a large degree by immense multinationalcorporations that control—with differing strategic objectives—the majority of the connecting communication tissues.

Major and minor system and software firms will create the newstorage-intensive technologies.

Notwithstanding the system, software, and telecommunicationsdivisions of such multifaceted giants as Fujitsu, Hitachi, IBM,NEC, and Toshiba, drive makers do not own communicationnetworks and they do not manufacture “infotainment” content,nor do they have any ability to produce storage-intensive“killer applications” that will have a global impact in diversecommercial and consumer markets.

However, the RDD manufacturers do have the power toengender, in varying degrees, markets in which RDD pricing willbe more stable.

If the drive makers can manage a timely and accurateadjustment of their build plans to meet (and not exceed)evolving market requirements, they will have a chance totransform the surplus waste lands of the industry’s cyclichistory and create market conditions in which sustainableprofits can become a reality. ●

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IDEMA provides $40,000 in fellowships tograduate students in the data storage field.Applicants are judged on research relevance,technical content, and creativity. Hurry, donÕtdelay fellowship application deadline is March 15, 1999.

first place $25,000second place $10,000third place $5,000

Pick up the IDEMA fellowship application form fromyour academic counselor, submit completedapplication to:

Sally Bryant3255 Scott Blvd. Suite 2-102Santa Clara, CA [email protected]

fellowshipfellowshipapplications now accepted

Phase Metrics Ad

February 4, 1999Santa Clara WestinIDEMA is pleased to presentnationally recognized technology analyst Todd Bakar of Hambrecht & Quist as the February Dinner Meeting speaker. Todd has specialized in technology investment research with Hambrecht & Quist for more than 11years. In 1994, he was named managing director and threeyears later was asked to head the technology researchdepartment. In November 1998, he was promoted to director ofresearch. Todd now manages nearly 40 analysts, covering fourfocus areas: technology, healthcare, information services, andbranded consumer. He continues to have direct responsibilityfor the data storage industry coverage. While at Hambrecht &Quist, Todd has served as a member of the InstitutionalInvestor magazine’s All-American Research team and the WallStreet Journal’s All-Star Analyst team. Todd is a graduate ofthe University of California, Berkeley.

The February Dinner Meeting will be held at the Santa ClaraWestin located at 5101 Great America Parkway in Santa Clara,Calif. Cocktails at 6:00 p.m. Dinner at 7:00 p.m. For moreinformation or to register, visit the IDEMA Web site atwww.idema.org or call Lindsay Brown at (408) 330-8100.

Nationally recognizedtechnology analyst Todd Bakar

of Hambrecht & Quist.

Radisson Hotel, Bloomington, Minn.Wednesday, June 2, 1999

As the technology for disk drives continues to advance, and thedesire to increase volumetric storage has grown dramatically.MR and GMR heads have now made it possible to significantlyincrease areal density by increasing the BPI and TPI of themedia.

The main issue facing this increased density, is data access. Toaccess data at an acceptable rate requires higher rotationspeeds, as well as solutions to several critical issues, such asflutter, heat, NRRO, TMR and PES. The requirements for HighTPI Recording Symposium will address these issues as theypertain to higher TPI, and ultimately, high-density media andhigher capacity drives.

Heads1. Trail Edge Definitions2. Bit Aspect Ratio3. Secondary & Micro Actuators

Requirements for High TPI RecordingSymposium

for papers

Media1. High TPI Media2. Media Noise3. Grain Structure & Uniformity4. Patterned Media

Interested in presenting? Simply submit your 250-wordabstract, biography, and contact information to IDEMA byMarch 17. Mail to: 3255 Scott Blvd, #2-102, Santa Clara,Calif. 95054. Fax to 408-492-1425 or send electronically toSeth Ayers at [email protected].

Selected speakers will be notified by March 30 , 1999. A hardcopy of the final presentation is required by May 4. IDEMAaccepts the following presentation formats: slides, overheads,and multi-media productions. Papers which differ significantlyfrom the abstract or are sales oriented may be excluded fromthe final program.

callcall

Advertisers IndexSeagate inside front cover

www.seagate.comDover Instruments page 4

www.doverinstr.comAvery Dennison page 11

www.averydennison.comVeeco Metrology page 11

www.veeco.comVTC Inc. page 15

www.vtc.comDatatech Magazine page 19

www.dupont.com/vertrelErrigo Executive Search page 23

www.errigo.comSpeedFam page 25

www.speedfam.comMTI page 29

www.mtionline.comTexas Instruments page 35

www.ti.com/storage/c27x7023Veeco Process Equipment page 37

www.veeco.comADE Technologies page 39

www.adetech.comPhase Metrics page 40

www.phasemetrics.comDuPont page 42

www.fabtech.orgEFD back cover

www.efd-inc.com

Dupont Ad

The superparamagnetic limit, and continued growth inareal density and data rates have lead tomajor developments in head and media technologies.The most significant recent advancement is thegiant magnetoresistive (GMR) head, whichevolved from magnetoresistive (MR) head technology.Flying at less than one micro inch above the spinning,low glide disk, GMR heads offer twice the sensitivitythan MR heads. The ultra sensitive GMR sensorsmaximize the quantum nature of electrons to providethe high quality read-back signals needed to supportareal densities beyond 10 Gbits/in2. Thesesubstantive advancements in storage technology have,in turn, created additional challenges for head andmedia manufacturers.

IDEMA’s GMR Heads and Media Symposiumand hear about the latest advancements in head andmedia design and the challenges facing the storageindustry’s leading manufactures. You’ll also learn solutionsto the most critical head and media production issues,including thermal asperities, thin film process control, anddisk texturing.

Sign-up by February 2 and off the regular registration fee.

You may register on-line at www.idema.org. On-site registration available after February 8.

Attend

receive a discount

Westin, Santa Clara, California

IDEMA Asia-Pacific, inconjunction with SingaporePolytechnic, is launching aCertificate of Competence inStorage Technology program.The Certificate program isdesigned to provide thetechnical knowledge baseneeded to be effective andproductive in the storageindustry. The program isgeared towards individualswith little or no experience inthe data storage industry.Classes are developed anddelivered by instructors fromSingapore Polytechnic andtrainers from the storageindustry. Classes are reviewedand updated regularly toensure instruction on the lateststorage technology.

IDEMA Asia-Pacific’sCertificate program isnationally recognized in

IDEMA Launches Certificate ProgramSingapore, and is funded bythe governments ofSingapore and Malaysia.Individuals interested inobtaining a Certification ofCompetence in StorageTechnology must successfullycomplete all core classes plusthree elective classes. Anexam will be given for allcore classes. The total cost ofthe Certificate program isS$1500.

The program is available inSingapore, Malaysia, China,Thailand and the Philippines.Public classes in Singaporeand Malaysia will beannounced before January1999. IDEMA Asia-Pacificcan customize classes forcorporations wishing to offerthe full Certificate program in-house to their employees.Classes are also available

individually for continuingeducation. Governmentfunding is not provided toprofessionals not completingthe Certificate program.

IDEMA’s continuing educationprogram provides a

activities, including the Microcontamination Symposium and sixeducation classes in December. Due to the high demand fortechnical education, our classes are filling quickly.

One of IDEMA’s goals is to provide its members with high-quality, continuing technical education. To achieve this goal,we are offering symposia events, standards workshops, and anew, comprehensive certificate program. IDEMA Asia-Pacificand Singapore Polytechnic, the largest and oldest university inSingapore, joined forces to develop the Certificate ofCompetence in Storage Technology program. The Certificateprogram is designed to provide the technical knowledge baseneeded to be effective and productive in the storage industry.It is the first nationally recognized storage technology certificateprogram in Singapore, and it is funded by the governments ofSingapore and Malaysia. Individuals interested in obtaining aCertification of Competence in Storage Technology mustsuccessfully complete seven core classes plus three electiveclasses. The Certificate program will be launched in Singapore,January 1999, and offered in Malaysia in March.

From basic education classes to symposia events, IDEMA Asia-Pacific is providing its members with exciting new benefits in1999. And many of these new activities wouldn’t be possiblewithout the support of our dedicated member volunteers. Withtheir help and active participation, IDEMA Asia-Pacific willcontinue to grow and provide additional services in the yearsto come.

comprehensive technicalfoundation for those who areworking in the storageindustry. For additionalinformation, please send e-mail to [email protected] call Lillian at 65.3563992.

Seven Core Classes (8 hours per class)• Fundamentals of Magnetism • Fundamentals of Hard Disk Technology • Fundamentals of Heads Technology • HDD Manufacturing Basics • Disk Drive Handling • Microcontamination • ESD/EOS Control

Elective Classes (8 hours per class)• Tribology and Mechanics • Head Manufacturing Basics • Media Manufacturing Basics • PRML Basics • Basics of Optical, Magneto Optical Technology • Fundamentals of Removable Device Technology

Certificate program classes:

Asia-Pacific Asia-Pacific We have an active IDEMA organization in Asia. It is supportedby an Executive Management Committee that comprises all ofthe major HDD manufacturers and suppliers, including Seagate,Western Digital, Quantum, Maxtor, MMI, Phase Metrics,Megatech, and SCI. IDEMA Asia-Pacific membership has grownfrom 110 in December 1997 to 132 in December 1998.

Last year, IDEMA Asia-Pacific offered a number of new eventsand activities. At our largest event, the Asia Computer StorageConference (ACSC), we offered a tabletop exhibition and aTechnology Showcase featuring HDD innovation history. TheACSC is the largest event in Asia dedicated to the data storageindustry. This year, the conference will be called the DISKCONAsia Computer Storage Conference and Exhibition, and in theyear 2000, it will be officially renamed DISKCON Asia.

IDEMA Asia-Pacific also offered several technical events lastyear, including a seminar on disk handling and severalstandards workshops. In December, we presented our firstsymposium, held in both Singapore and Penang, which focusedon the critical issue of microcontamination. More than 130storage professionals attended each session. The response wentwell beyond our expectations.

In an effort to extend our services throughout the region, IDEMAAsia-Pacific created a steering committee in Penang. Thecommittee is led by Gary Davis, Singapore MC member. Davisand the committee members helped organize several IDEMA

news

Members Gain New and Improved Services in 1999S.H. Goh, Executive Director

Technical Members Non-Members On-SiteConference✝ S$450 S$495 S$545

Reception Only S$25 S$25 S$25

ESD Symposium Members Non-Members On-SiteS$130 S$170 S$190

ESD Class Members Non-Members On-SiteS$130 S$170 S$190

ESD Package✝

Symposium Members Non-Members On-Site& Class S$240 S$340 S$380

✝Registration includes lunch and proceedings.

The next decade promises accelerated manufacturing andtechnology requirements for magnetic hard disk drives to meetskyrocketing worldwide storage demands. To achieve amaximum in capacity per disk, drive designs will employ MRand GMR heads integrated with super smooth media, allowingflying heights to approach 1µm. An ultra clean,microcontamination-free manufacturing environment for driveassembly in combination with precision testing based onstatistics will ensure high yield production. As areal densitiesexceed 4 Gb/in2, emphasis will be directed towards EEPRMLdata channels for maximum signal amplitude detection withoptimum ECC.

IDEMA will present its annual DISKCON Asia ComputerStorage Conference and Exhibition in Penang and Singapore.The conference will feature three sessions, including a markettrends session with leading trade analysts sharing theirperspective on the Asian storage industry. IDEMA is alsopleased to present William Watkins, executive vice presidentand COO at Seagate Technology as the keynote speaker inSingapore. In addition, IDEMA will host a Roundtable Panelfeaturing Managing Director’s from the industry’s top storagecompany’s in Asia at the Penang conference.

And for the first year, IDEMA will sponsor a symposium onelectrostatic discharge (ESD) in magnetic recording. Thesymposium will focus on MR and GMR heads and will addresskey ESD issues, such as control plan development, prevention,damage assessment, and packaging. A 3-part ESD class, co-sponsored by the Silicon Valley EOS/ESD Society✱✱, will alsobe offered and will cover ESD basics, testing for ESD insemiconductor and magnetic recording, and ionizationapplications for the magnetic recording industry.

Hotel Equatorial, Penang, March 8Westin Stamford, Singapore, March 10-11

DISKCON® Asia Computer Storage Conference and Exhibition

Attend IDEMA's DISKCON Asia Computer Storage Conferenceand Exhibition and discover the latest advancements in harddisk drive manufacturing and technology from the industry'sleading design and production experts. Learn about ESD andthe techniques used to test, evaluate, classify, and control ESDin today’s manufacturing environments by attending the ESDsymposium and education class. Visit the tabletop exhibitionand find the solutions to your most critical manufacturing issues.

Prepare yourself for the next millennium of storage byregistering today to attend IDEMA's DISKCON Asia ComputerStorage Conference and Exhibition.

Technical Members Non-Members On-SiteConference✝ RM295 RM360 RM395

ESD Symposium* Members Non-Members On-SiteRM150 RM190 RM210

ESD Class* Members Non-Members On-SiteRM150 RM190 RM210

ESD Package*✝

Symposium Members Non-Member On-Site& Class RM270 RM380 RM420

*Located at PSDC in Penang.✝Registration includes lunch and proceedings.

Penang, MalaysiaSingapore

register on-line at www.idema.org

✱✱ In cooperation with the ESD Association.

head manufacturing process used in today’s disk drives.“Building a Disk” follows the production of a disk, step-by-step, from stamped aluminum blank to finished state-of-the-artmagnetic media.

We are pleased to provide an effective, proven set of classesto meet your technical training needs. For more information onthese classes, call Sally Bryant at 408-330-8106, or visit ourWeb site at www.idema.org. For information onKnowledgeTek’s advanced classes, call Verna Mahnke at 303-465-1800, or visit [email protected].

IDEMA Announces New Alliance with KnowledgeTekSally Bryant, Ed.D., Director of Education

February 23IDEMA office, Santa Clara, Calif.• Disk Drives 101: What’s in the Box?• Building a Disk: An Introduction to Thin Film

Media Manufacturing

February 24IDEMA office, Santa Clara, Calif.• An Introduction to MR Head Technology• Building a Head: Understanding Thin Film

Head Manufacturing

June 3Minneapolis, Minn. (site TBD)• Disk Drives 101: What’s in the Box?• Building a Disk: An Introduction to Thin Film

Media Manufacturing

June 4Minneapolis, Minn. (site TBD)• An Introduction to MR Head Technology• Building a Head: Understanding Thin Film

Head Manufacturing

Register on-line at www.idema.org or call (408) 330-8103 formore information.

IDEMA education classes can be delivered at yourlocation, and tailored to meet your needs. Call (408) 330-8106 to arrange for on-site class instruction.

upcoming classes

When we asked you what you wanted, you said

more classes, more often. IDEMA listened; and we are pleased toannounce our new alliance with KnowledgeTek, a proven leaderin the field of technical education in computer storage andinterface technologies. Effective January 1, IDEMA will be theexclusive provider of KnowledgeTek’s basic classes. IDEMA’sbasic classes will feature KnowledgeTek’s highly qualifiedinstructors and excellent course material. KnowledgeTek willcontinue to offer its advanced, two- and three-day classes. Thisalliance will allow IDEMA to offer you, our members, the classesyou asked for. We are working closely with KnowledgeTek tobring you a combination of basic and advanced classes that bestmeet your needs.

The IDEMA/KnowledgeTek classes explain how each of thedifferent storage components function and how they each fit intothe big picture. The basic classes provide a great introductionand overview to the data storage field. If you are new to theindustry or are interested in learning about a different aspect ofit, these classes will be valuable to you. They are appropriate toall levels, from entry level to upper management. The advancedclasses include more technical material, and are best suited toprofessionals with a deeper knowledge or understanding of thesubject. The focus of all classes is “real-life”, with instructorsbringing real applications to real problems. The instructors areengineers with an impressive track record in the industry, sothey know first-hand the issues you face. In addition to theirexcellent technical knowledge, each instructor is skilled inpresenting technical material to a variety of audiences.

Open enrollment classes are available at our office in SantaClara, California, as well as in Colorado, Minnesota, and Asia.Plan now to attend the basic classes in Santa Clara duringFebruary 23-25. Other open enrollment classes will be announcedthroughout the year. We also deliver classes to your employeesat your site. Want to combine a basic class with an advanced?No problem. We’ll create a schedule that meets yourrequirements.

Classes include “Disk Drive Basics”, an introductory class on diskdrives. No prior technical knowledge is needed. Take “AnIntroduction to MR Technology” to learn the basics of how MRheads work and why they are so important to the data storageindustry. “Building a Head” and “Building a Disk” are best suitedto those who have taken “Disk Drive Basics” and “Introduction toMR Technology” or have some background in the head or mediamanufacturing field. “Building a Head” walks you through the

Fish or

Cut Bait. Join or renew your IDEMA corporate membershiptoday.

IDEMA ¥ 3255 Scott Blvd., Suite 2-102, Santa Clara, CA 95054-3013fax: 408.492.1425 ¥ phone: 408.330.8100 ¥ www.idema.orgIDEMA is a registered trademark of the International Disk Drive Equipment and Materials Association. 12/98

IDEMA® corporate membership is one of the most valuabletools in your storage industry tackle box.

With new high-tech lures like on-line banneradvertising and custom Web pages, you are sure to getsome solid hits. Only corporate members are licensedto advertise in IDEMA’s redesigned associationmagazine, INSIGHT. New high-visibility ad positioninggets customers hooked on your corporatemessage—It’s up to you to reel ‘em in. And as acorporate member, your employees are entitled todiscounts on education classes, symposia proceedings,conference sessions and more!

From creative target marketing to professionaldevelopment opportunities, IDEMA corporatemembership offers you valuable savings on the servicesyou want and need to succeed in the data storageindustry. Apply for corporate membership today. ContactProgram Manager Debbie Lee at 408.330.8108 [email protected].

3255 Scott Blvd.Suite 2-102Santa Clara, CA 95054-3013Address Correction Required

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