Micro mechatronics 1part 2.2: substrates

manufacturing technologies

Prof. Fritz J. NeffDirector of the Laboratory for Micro mechatronics and Hybrid integrated thick film circuitSat the University of AppliedSciences Karlsruhe (FH), 16. August 2004

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 2

Manufacturing of ceramic substrates

finishing(Laser cutting or polishing)

99% of the parts are used "as fired"

sintering (fireing)(thermal treatment at 60% up to 75% of absolute melting temperature)

Al2O3 at about 1650°C

preparation of sintering processtake away organic pollutions and fixing agents, Temp. (150°C)<< max.

forming(green tape)

mechanical dressing(milling, mixing, granulating + additives)

(paste)

natural and synthetic raw materials(powder)

Green tapes

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 3

Preparation of the mass

milling, mixing, granulating, adding specialcompuonds

99,6% Al2O3 and 0,4% of additivesresult in best surfaces for thinfilm technology

Al2O3 SiO2MgO,CaO

96% + 4% glass

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 4

Realizing the dimensions

Determining of - length, - width,- thickness,- additional special

geometrics- bores.

Nominal thickness + 17%

cutting and boring

drying

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 5

Sintering / fireing

High purity compounds are treated by crushing, milling, granlating, reducing to dust that the result aregranularities between 1µm and 500µm

forming by hot pressing, pressure sintering, compressing by explosion, extruding and powder rolling

Sintering in box type furnaces (muffel) or continuousheat-treating furnaces

Process of tightening by adhesion of the particles, neck groove binding between the particles and tighteninguntil nearly all pores are closed

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 6

Sintering of preformed green tapes

Temperature-time-diagram: Al2O3-ceramics

Process timeh3 12 21

1600

400

°C

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 7

Characteristics of the substrates

Selection betweenAl2O3-, AlN- and BeO-ceramicsaccording to therequirements and also the costs areplaying an important ruleglasses

Thermal conductivity λ and dielectric constante ε

1 6 8 10 20 40 60 80ε0.01

0.1

1

10

100

1000

λW/mK

2

BeO

AIN

Al2O3

Polymere

Polymer laminated metal substrates

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 8

Geometric characteristics

Importantinfluence into thequality of thescreen printingprocess:- line width,- line hight,- sharpness of

edges.

dh

convexity f

f = h - d

DIN 86

Zulässig sind 0.1 mm Durchbiegung auf 25 mm Meßstrecke

surfae profile of substrates

Rautiefe Ra

Länge/µm200 400 600 800

1

2

3

4

5Ra/µm

DIN 86

3 Gruppen bzg. des Mittenrauwertes:

Gruppe 1: 0,8 bis 1,5 µm Gruppe 2: 0,5 bis 0,8 µm Gruppe 3: 0,25 bis 0,5 µm

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 9

Characteristics of technical ceramics

hohe Wärmeleitfähigkeit λ kleine Dielektrizitätszahl

hohe Biegefestigkeit

geringe Oberflächenrauhigkeit

hoher spezifischer elektrischer Widerstand

chemische Resistenz gegenüber verwendeten Pasten

temperaturbeständig gegenüber hohen Prozesstemperaturen

Umweltverträglich, weiterverwendbar, wiederverwertbar

Gleicher thermischer Ausdehnungskoeffizient wie die verwendeten Pasten und Bauelemente

geringe Kosten

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 10

Defects in surfaces of ceramicsubstrates

/acc. to Reichl and Bosch/

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 11

LTCCLow Temperature Co-fired Ceramics

Support of green tapeswith about s=50µm

(Green Tapes)

Support of green tapeswith about s=50µm

(Green Tapes)

Termal treatment at about 150°C

Termal treatment at about 150°C

Punching of vias with about20 Hz

thermal vias d=300µmel. vias 150µm<d<200µm

Punching of vias with about20 Hz

thermal vias d=300µmel. vias 150µm<d<200µm

Filling of the vias(Viafilldruck)

Filling of the vias(Viafilldruck)

Printing of conductorlines

100<b<150µm

Printing of conductorlines

100<b<150µm

Piling up4 up to 6 layers

Piling up4 up to 6 layers

Sintering at 950°C, 0,1 N/mm² up to

0,2 N/mm²

Sintering at 950°C, 0,1 N/mm² up to

0,2 N/mm²

further technologiesfurther technologies

Termal treatment 150°C,Reduction in z-direction about

30%

Termal treatment 150°C,Reduction in z-direction about

30%

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 12

handling of green tapes

green tape fromHeraeusTyp CT700

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 13

Manu-facturing of microhybrids

Keramikfolie

• punching of vias•Filling the vias•Printing the coductors

ajusting, piling upsintering

cutting

printing, fireing /BLU97/ mounting, bonding

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 14

LTCC – fine line

Widerstände

Thermische Vias

Ag mit Au-PlatingChip & Wire

Thermische Vias

Abdeckglass Widerstand

Ag

thermal Vias diameter / screen 300µm / 550µmfunctional Vias diameter / screen 130µm / 260µmConductor line (innen) width / screen 130µm / 260µmConductor line (außen) width / screen 130µm / 260µmsurface Plating NiPdAuBondpad 160µm x 360µm, screen 260µmResistor on rearside

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 15

Inner Layers of LTCC

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 16

Microhybride

Multi-layer

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 17

Technology of LTCC-Process

F

Pressure p = ca. 1,3 N/mm²and 950°C over more than12 Stundenvertical contraction about30%, in x- and y-dimension must be 0%

z

x

y

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 18

Substrate carrier GT1

Substrate carrier without (left) and with (right) Al2O3-substrate, 484 bores made by laser with diametrs of 200µm for low pressure

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 19

inside LTCC

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 20

rearside of LTCCwith resistors

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 21

Manufacturing steps of LTCC-substrate

Lot size of substrates

Screen printing conductor-lines on front side

fireing

Test of conductors

Screen printingovercoat

Fireing of resistorsand overcoat

Laser trimming

Scratching withdiamond

Optical inspection100%

Further steps of SMT-

Screen printing conductor-lines on rear side

Screen printing resistorson rear side

fireing

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 22/BLU97/

Developement of AntiBreakSystem

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 23

Developement of Motronic

/BLU97/

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 24

Requirements to the substrates

Carrying all printed layers,Chemical compatibility with all layers/pastes,Carying all SMD,Mechanical bonding of some elements,Functional (electrical, fluidic) bonding of some elements,High thermal conductivity,Coefficient of expansion should be the same like that of connected films and elementsOptimal peak-to-valley-hightHigh bending strengthProtection of all elements mounted on the surface,Respecting integration in Sensor-Actuator-System

Prof. Fritz J. Neff, Steinbeis TZ Mechatronik Karlsruhe 25

What did we learn?

Important materials for industrial used ceramicsubstrates?Difference between materials for constructionand materials for functionalities?What is causing different peak-to-valley-hightson the surface of the substrates?Manufacturing steps for ceramic substrates?Difference between sintering and fireing?Characteristics of the substrates and defects?