selecting a robust and reliable display...

©2016 DfR Solutions 9000 Virginia Manor Rd Ste 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com

Selecting a Robust and Reliable Display Technology

Edward Wyrwas, [email protected]

Date: June 23, 2016

©2016 DfR Solutions 9000 Virginia Manor Rd Ste 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com1

Abstract

This webinar explores the technologies used in visual displays for modern electronic applications.

o LCD display constituents such as advanced glass substrates, human machine interfaces (HMI) like touch recognition and illumination improvements will be some of the topics of discussion.

o While quality has historically been the dominant factor for reliability, environmental response and the display’s use at the system level may impact lifetime and user experienceoutweighing quality control.

These factors need to be considered to select a robust and reliable display.


Mr. Wyrwas is a Senior Member of Technical Staff at

DfR Solutions. He leads DfR Solutions’ research on

integrated circuit wearout and has presented on

semiconductor failure mechanisms, silicon-based integrated

circuit reliability and failure analysis techniques to numerous

companies, organizations and at high reliability, space and

aerospace related conferences.

His research includes characterizing transistor failure behavior over a range of

technology nodes and IP blocks supporting both aerospace and military research

programs with over 50 publications. His specialties include computer-based stress

testing of electronic systems, failure analysis, innovative design and cybersecurity.

Ed participates in standards working groups for AEC, SAE, ISO and IPC.

Speaker Bio:


o Liquid crystal

o Substrates

o LCD Drivers

o Human-Machine Interfaces

o Illumination

o Manufacturing

o Environmental Impact

o Failure Signatures & Failure Analysis

Agenda


o The first documented example of a liquid crystal was reported by the Austrian Frederick Reinitzer in 1888

o Reinitzer was studying the properties of a cholesterol derivative, cholesteryl benzoate, and noticed that it behaved strangely as it melted

o The white solid first formed a cloudy white liquid phase at 145°C, which transformed into a clear liquid at 179°C .

o The transitions were completely reversible: cooling molten cholesteryl benzoate below 179°C caused the clear liquid to revert to a milky one, which then crystallized at the melting point of 145°C.

Basis for All LCDs – Liquid Crystal

Apply Heat

Opaque

Translucent

Opaque


o Liquid crystal is a substance made of complicated molecules

o Like water, liquid crystals are solid at low temperatures and melt when you heat them.

o When ice melts, it changes into a clear liquid. Liquid crystals, however, change into a cloudy liquid.

o At slightly higher temperatures, the cloudiness disappears, and they look much like any other liquid.

o Phases

o When the liquid crystal is a solid, its molecules are lined up parallel to one another

o In the intermediate cloudy phase (liquid), the molecules still retain this more or less parallel orientation

o Higher temperatures tend to agitate the molecules and thus make the liquid clear


o In an LCD, an electric current is used to switch segments of liquid crystals from a transparent phase to a cloudy phase, each segment forming part of a number or letter.

o The segments can also be in the shape of tiny dots or pixels, and the can be arranged in rows and columns.

o They are turned on and off individually to either block or allow polarized light to pass through. When the light is blocked, a dark spot is created on the reflecting screen.


o Nematic phase

o Have no positional order, but has orientational

order

o The mesogens (liquid crystal molecules) all point in

the same direction but have not defined layers

o Averaging molecular orientations gives a definite

preferred direction (called the director)

o Smectic phases

o Have orientational order, and some degree of

positional order

o Are distinguished by the presence of layers

perpendicular to the director

Crystal Types


o Because of their anisotropic structures, liquid crystals exhibit unusual optical and electrical properties.

o The intermolecular forces are rather weak and can be perturbed by an applied electric field.

o Because the molecules are polar, they interact with an electric field, which causes them to change their orientation slightly.

o Nematic liquid crystals, for example, tend to be relatively translucent, but many of them become opaque when an electric field is applied and the molecular orientation changes.

Image: http://chemwiki.ucdavis.edu


o Advantages

o The most common technology and also the oldest

o Provides the shortest response times

o In combination with LED back-lighting, TN monitors also offer high brightness and draw less power than competing technologies

o Cheap to manufacture, resulting in low prices for end users

o Disadvantages

o Color shifts that occur at wider viewing angles

o There are large differences in quality between different products, but the lower-end ones will exhibit color shift even at moderate angle changes

o A TN-based display can usually be identified through these color distortions when viewing the picture from above or from the sides

Twisted Nematic

http://www.dragonlcd.com/


o Advantages

o the technology offer noticeably better color reproduction as well as much better viewing angles.

o Response times have crept down considerably and the contrast is much better

o color display and the options to calibrate the colors are superior to the other panel types

o keep colors constant, even in sharp angles.

o Disadvantages

o Some difficulty to emphasize blacks, which means problems with the contrast

In-plane Switching (IPS)

https://i.ytimg.com/vi/b34UrVxFvSA/maxresdefault.jpg


o Advantages

o Combines the advantages of both TN and IPS

o Multi-domain Vertical Alignment (MVA) panels offer good viewing angles and generally better blacks and contrast than either TN or IPS panels.

o Disadvantages

o Their response times look good on paper, but unfortunately not in the real world

o Even if the response time for white to black is low, it is often considerably higher between two dark tones, leading to Ghosting effects

o Another weakness is the color reproduction, which in itself is better than TN but not as good as IPS

Vertical Alignment (VA)


o There are two general types of LCDs:

o Passive matrix (PMLCDs)

o newer Active matrix (AMLCDs)

o Passive Matrix

o Cross bar electrodes drive each pixel

o First types of LCDs

o Have contrast issues

o Active Matrix

o Use transistors and a capacitor behind each pixel to boost the image

o The manufacturing process for AMLCDs, however, is much trickier than that for passive matrix LCDs

o As many as 50 percent of those made must now be thrown out because of imperfections.

o One imperfection is enough to ruin an AMLCD. This makes them very expensive to manufacture.

o Brighter and easier to read

LCD Types


o In all LCDs, the liquid crystal is sandwiched between two pieces of glass or transparent plastic called substrates.

o Just any glass will not do

o If the glass has many sodium or other alkali ions, they can move to the glass surface, combine with any moisture that is there, and alter the electric field pattern and liquid crystal alignment

o To eliminate that, LCD makers either use borosilicate glass, which has few ions, or they apply a layer of silicon dioxide to the glass. The silicon dioxide prevents the ions from touching any moisture.

o "If you have a 1-millimeter sheet of plastic, it will take an oxygen ion [from moisture] a few hours to get through it. Moisture is terrible for electronics. If you have a 1-millimeter piece of glass, it will take 30 billion years.” – Corning Glass

Substrates


o 4-players make up 94% of the market

o Samsung Corning Precision Materials

o Asahi Glass

o Nippon Electric Glass

o Corning

o Proprietary fusion processes to make large flawless pieces of glass with full automation

o Most display glass is an alumina silicate formulation, which is made up of aluminum, silicon, and oxygen. The glass also contains sodium ions spread throughout the material.

o Gorilla glass has potassium ions rather than sodium ions (larger ions, creating compression within the glass)

Glass Making

http://www.technavio.com/report/large-area-lcd-display-market

https://www.corning.com/asean/en/products/display-glass/how-it-works.html

http://www.technavio.com/report/large-area-lcd-display-market

https://www.corning.com/asean/en/products/display-glass/how-it-works.html


o Thin strong heat resistant substrates prevent bulging of the

sandwiched substrates during assembly

o The strength also helps coplanarity for when things are

bonded to it

Glass Sandwiches

Heat & Pressure Accidental Bulge

First

Bo

nd

La

st B

on

d


1. Glass substrates

2. Horizontal polarizer

3. Vertical polarizer

4. RGB color filter

5. Horizontal control lines

6. Vertical control lines

7. Polymer layers

8. Spacers

9. Thin Film Transistors (TFT)

10. Front Electrode

11. Rear electrode

Z

Z

Controller

Ledge

Glass Plates

Z-Z Cross

Section


o The LCD’s electrodes are powered and controlled by a

driver circuit

o The general rule of thumb is to reduce the number of

interconnects to increase the LCD module’s reliability

Driver Circuitry


Chip on Board

(bond wires)

https://www.crystalfontz.com

Chip on Glass

(underside)

Chip on Flex

(flip chip with ACA)


Seen on smaller displays


Seen on larger displays


o Chip on Glass complexity

o Anisotropic Conductive Film (ACF) is used because there are many more terminals, the terminal pitch is fine and high precision junction is required

o ACF’s connection resistance is low and excels in heat resistance and connection reliability


o Hot Bar

o Anisotropic Conductive Adhesive (ACA) is an epoxy system used to make electrical connections between drive electronics and substrates such as chip on glass (COG) and flex on glass (FOG)

o Can be used for direct metal-metal bonds

Assembly Techniques

What takes place in this sandwiched interface is

depicted on the next slide


Hot Bar Process

Chip on Glass

Chip on Glass near Flex on Glass


Liquid Crystal Display Drivers: Techniques and Circuits, David J.R. Cristaldi, Salvatore Pennisi, Francesco Pulvirenti


o Process control is

important to ensure the

ACA, Glass, COG and

Hot Bar all are flat

o Process parameters

o Temperature

o Force

o x-y-z alignment

o z-travel

Anisotropic Conductive Adhesive


Flex Design Helps Reliability


o Human Machine Interface is the part of the machine

that handles the human–machine interaction

o Physical part of the Human Machine Interface which

we can see and touch.

o Membrane switches, rubber keypads and

touchscreens

o “Touch” interfaces discussed here-in

o Resistive

o Capacitive

Human Machine Interfaces


o Traditional touch screen technology is analog resistive

o These panels work by detecting how much the resistance to current changes when a point is touched

o When you push down on the outer film, it makes contact with the glass and completes a circuit

o The voltage of the circuit is measured, and the X and Y coordinates of the touch position is calculated based on the amount of resistance at the point of contact.

Resistive Touch

https://www.flickr.com/photos/intelfreepress/


o Instead of being based on electrical resistance, it relies on electrical capacitance.

o If you apply a charge to a conductor, and then bring another conductor near it, the second conductor will "steal" some of the charge from the first one

o Similar to an ESD shock between objects

o Works on the fact that an electromagnetic field "projects" above the plane of the conductive sensor layer

o The conductors are scanned in a rapid sequence so that all possible conductor combinations can be sensed concurrently

o Can detect multiple simultaneous touch points

o Can be a separate digitizer or integrated into the glass stackup

Projected Capacitance

or Plastic

or Plastic

or Plastic


Improvements to Reduce Manufacturing Steps

Separate Modules Sensor On Lens

On-Cell In-Cell

Alfred Poor, Computer World.com, 2012


o Sensor On Lens

o The display assemblers would just have to purchase a simple

cover glass with integrated touch to complete the display

o Modules can be larger than the LCD panel, providing room

for the dedicated touch points that are part of many

smartphone designs

o Can add a physical safety margin to LCD assembly where

strain relief epoxies can be added without reducing the

LCD’s active area

Advancements in Integration


o On-cell touch panels

o This approach means that LCD makers would have to make

two separate models of each panel:

o one with touch

o one without touch

o This could add cost to an industry that is already running on

razor-thin margins

o On-cell touch is limited to the size of the LCD panel


o In-cell touch panels

o One of the conductive layers actually shares the same layer as the thin film transistors (TFTs) used to switch the display's sub-pixels on and off

o These transistors are fabricated directly on the semiconductor backplane of the display

o This approach not only reduces the electromagnetic noise in the system, but also uses a single integrated controller for both the display and the touch system.

o This reduces part counts and can make the display component thinner, lighter, more energy efficient and more reliable.


o Capacitive Touch

o Resistive Touch

Comparison

Pros Cons

No moving parts or delamination risk Only works with capacitive surfaces

Fewer substrate layers More sensitive to ESD

Costs more $

Pros Cons

Works with any physical object Interface subject to analog drift

(user may need to recalibrate)

Inexpensive to make

(simply attach interface)

ITO in the conductors is not suitable for

bending, often causing cracks

Repairable – if desired Air gap between layers can distort light


o Most LCDs today use a source of light coming from the rear of the display (backlight), such as a fluorescent light, to make the liquid crystal appear darker against the screen when in its cloudy phase.

o LCD makers also use sheets of polarizer material to enhance this effect

o Polarization

o The goal here is to pass the light through the panel in such as way as to improve contrast, brightness and viewing angle

o Different Lights

o The bulb will fail before the LCD panel

o Dictates effective lifetime of the panel

Illumination


o In case you've been wondering where OLED displays fit into all this:

o An OLED display stack is somewhat different from an LCD stack – there isn’t a backlight, instead there are LEDs at each pixel and seldom an LCD

o In spite of all this, as far as touch screen technologies are concerned, OLEDs are more like LCDs than they are different:

o Both have active matrix TFT backplanes

o Both have a cover glass layer for protection


o LED Matrix Switching

http://what-when-how.com/display-interfaces/display-technologies-and-applications-display-interfaces-part-2/


o LED backlit displays &

Organic-LEDs

o LEDs are the critical

component from a user

perspective

o If the LEDs stop working, it

is perceived that the

product is no longer

working

o either the whole panel or

individual pixels go dark

Light Emitting Diodes (LEDs)

“stuck” pixel clusters

(LCD powered on)


o The maximum junction temperature tends to be 110°C

o Lifetime model is based on a modified Black’s equation for diffusion of

semiconductor materials

o Latent defects exist in the LED due to its fabrication process (diffusion vs

epitaxial growth) and the maturity of the process itself

o Process related defects and defects generated by electric fields (usage

of the LED) migrate within the crystal structure causing the light output to

diminish or stop working altogether

o Failure definition is typically a 50% reduction in brightness which directly

impacts the user’s perspective of color identification


o Most LEDs are rated to 50,000 hours at ambient temps and rated forward current

o This is MTTF lifetime

o Time to 5% failure can be half the time

o Activation energy can have large variations between product lines and vendors

o Range between 0.4 and 0.9eV (Avago recommends 0.43eV)


o Monte-Carlo analysis for various current-temperature combinations

191 185 180 175

90.0 363.0 3.83 4.08 4.31 4.56

87.5 360.5 4.21 4.49 4.74 5.01

85.0 358.0 4.64 4.94 5.22 5.52

82.5 355.5 5.11 5.45 5.76 6.09

80.0 353.0 5.65 6.02 6.36 6.73

77.5 350.5 6.25 6.66 7.03 7.44

75.0 348.0 6.92 7.38 7.79 8.24

72.5 345.5 7.68 8.18 8.64 9.14

Forward Current (mA)

Junction Temperature (°C,K)

Lifetime (years)

years


o Making passive matrix LCDs is a multi-step process.

o The surface and rear glass of the display is first polished,

washed, and coated (i.e. silicon dioxide)

o A layer of indium tin oxide (ITO) is evaporated onto the

glass and etched into the desired pattern.

o A layer of long chain polymer is then applied to allow the

liquid crystals to align properly, followed by a sealing resin.

o The spacers next are put into place, and the glass sandwich

is filled with the liquid crystal material.

Manufacturing Processes – Passive Screens


Many Automated Steps


o First, the two glass substrates must be cut to the proper

size, polished, and washed.

o Cutting can be done with a diamond saw or scribe, while

polishing involves a process called lapping, in which the glass

is held against a rotating wheel that has abrasive particles

embedded in it.

o After being washed and dried, the substrates are coated

with a layer of silicon dioxide.

Preparing the glass substrates


o The transparent electrode pattern must be made on the substrates.

o This is done by completely coating both front and rear glass surfaces with a very thin layer of indium tin oxide.

o Manufacturers then make a mask of the desired pattern, using either a silk-screening or photolithography process.

o They apply the finished mask to the fully coated glass, and areas of indium tin oxide that are not needed are etched away chemically.

o The patterns on the two substrates are designed to overlap only in specific places

o a design that ensures that the thin strips of indium tin oxide conveying voltage to each element have no electrode positioned directly opposite that might show up while the cell is working

Making the electrode pattern


o The substrates must be coated with a polymer

o The polymer allows the liquid crystals to align properly with the glass surface.

o Polyvinyl alcohol, polyamides, and some silanes can be used.

o Polyamides are the most popular agents

o Polyvinyl alcohol is subject to moisture problems

o Silanes produce a thin, unreliable coating

o After coating the glass, manufacturers then rub the polymer coat in a single direction

o This process forces the liquid crystals to lie parallel to the direction of the stroke

o If LCD makers want to align liquid crystals perpendicular to the glass surface, they coat the glass with an amphophilic material

o This is material whose molecules display affinity for water at one end of the molecule and repulsion from water at the other end

o One end adheres to the glass surface, while the other repels the liquid crystals which forms them into an alignment that is perpendicular to the glass surface

Applying the polymer


Polymer Rubbing for Alignment

http://pubs.rsc.org/en/content/articlelanding/2015/ra/c5ra08521g#!divAbstract


o A sealing resin is next applied to the substrates, followed

by plastic spacers

o Gives the liquid crystal cell the proper thickness;

usually 5-25 micrometers

o The liquid crystal material is injected into area between the

two glass substrates.

o Because proper thickness is crucial for cell operation and

because spacers don't always achieve uniform thickness, LCD

makers sometimes put appropriately sized glass fibers or

beads in the liquid crystal material.

Applying the sealant and injecting the liquid crystal


o To make LCDs more visible, polarizers are added.

o These are usually made from stretched polyvinyl alcohol

films that have iodine in them and that are sandwiched

between cellulose acetate layers

o Colored polarizers, made using dye instead of iodine, are

also available

o Manufacturers glue the polarizer to the glass using an

acrylic adhesive and cover it with a plastic protective film.

o They can make reflective polarizers, which also are used in

LCDs, by incorporating a simple metal foil reflector

Providing a Visual Boost


o After the polarizer film is attached, the unit is allowed to

age.

o Now, the glass display assembly is complete

o Then, it is mounted to the circuit boards containing the

control and drive electronics.

o Now the module is complete and can be incorporated into

another assembly… and so on

Final assembly?


o The process used to make an active matrix LCD (AMLCD)

is quite similar to that used for passive matrix LCDs

o The steps of SiO 2 coating, indium tin oxide application, and

the photoresist etching are replaced by a host of other steps

similar to semiconductor lithography

o In the case of AMLCDs, each LCD component has to be

changed to work properly with the thin film transistor and

electronics used to boost and clarify the LCD image

Process Differences – Active Matrix


o Active Matrix layers

o a polarizing film

o a sodium barrier film (SiO2)

o glass substrate incorporating a black matrix using TFTs, capacitors, ITO and bond wires

o second sodium barrier film

o a color filter

o a color filter overcoat made of acrylic/urethane

o a transparent electrode

o an orientation film made of polyamide

o plastic/glass spacers to maintain proper LCD cell thickness

o the actual liquid crystal material


Comparison

o Passive Matrix

o Active Matrix

Pros Cons

Relatively inexpensive Display contrast depends on drive

margin – a function of number of

rows

Typically only small panels

Pros Cons

No multiplexing limitations More parts (adds a capacitor and

transistor at each pixel) costs >$

Higher power requirement


Front-end Processes


Mid-Level Processes


o Panels cannot be reworked

o Liquid crystal is toxic, made up of dioxins and furans, which could be potentially dangerous when they emit toxic gases under high thermal condition

o Considered to be very difficult to biodegrade and hazardous to water and soil

o Mercury in CFL backlights

o It is estimated that CFL of different sizes contain nearly 3.5 to 13 mg of mercury per lamp

o Polymer Film Reflector

o Made of PET (polyethylene terephthalate), which is formed from ethylene glycol (EG) and terephthalic acid (TPA).

o These are potentially toxic to leach to soil and water

Environmental Impact

http://www.ijestr.org/IJESTR_Vol.%201,%20No.%207,%20July%202013/Liquid%20Crystal%20Display.pdf


o Failures are typically defect driven from a manufacturing

step or out-of-spec handling/use

o Most are mitigated by quality control

o Wearout failures are predicated by design and field use

o Marginal driver circuitry

o Interconnect issues including bond lines

o EOS/ESD

o Temperature-humidity related delamination

Failure Signatures


Defect Occurrence

(% of Total)

Point defect 32.6

Particles, scratches, dirt 24.7

Breakage 4.9

Line Defects 7.7

Faulty Cell Gap 6.1

Other 20.4

Common Defects in LCD Modules

Reference: Liquid Crystal Flat Panel Displays:

Manufacturing science and technology

By William C. O'Mara

o The failure mechanisms and defects discussed are:

o Spacers non-uniformity/Display bulging

o TFT delamination

o Cleanliness

o Bond line

o Moisture protection

o Constituent Failure

o Perimeter sealant

o Liquid crystal fill plug

o Ledge sealant

o Anisotropic conductive adhesive

o Chip on Glass

o Flex Assembly

o Any electrical or signal anomalies


Pixel Fault Definitions


o Defects of LCD panel come from the non-uniformity of the spacer thickness which depends on the liquid crystal’s filling state

o Gravity gap (G-GAP):

o the liquid crystal in the panel is pulled down and it enlarges the cell gap –this resembles overfilling of the liquid crystal cell

o Active Unfilled Area (AUA)

o Absence of liquid crystal

o If the spacer thickness is different in some areas on the panel, the over-filled or under-filled volume will be inversely proportional to the spacer thickness.

o Both AUA and G-GAP defects can occur as soon as the LCD is filled with liquid crystal or occur a few months after the LCD is made.

Uniformity of Spacers

[Causes black spots]

[Causes white blotches]

Extra liquid crystal Limited liquid crystal


Non-Uniformity of Spacers/Extra Spacers or Debris (Cont’d)

Green sub-

pixel spacers

Blue sub-pixel

spacers

Red sub-pixel

spacers aren’t

where they

should be

The spacers are supposed to be patterned on the color filter glass at each sub-pixel


o During manufacturing, thermo-mechanical compression of the glass sandwich causes deformation of the spacers.

o Spacers towards the center of the display are plastically deformed,

o Spacers towards its periphery elastically deform.

o The uniformity throughout the display is less than optimal.

o Liquid crystal’s function is based on the cell height at each pixel.

o If the spacers are non-uniform, then the light refraction through the liquid crystal is distorted.

o This effect can take place from external pressure on the screen or excessive internal cell pressure.

o The effect is a brownish/blackish blotch within the LCD viewable region.

“Touch Mura” Appearance

Customer’s Failed LCD


o A reference image of gate delamination due to poor adhesion of the deposited metals (grayscale)

o This failure mode takes place when there is a CTE mismatch between the substrate and the deposited materials.

o It also takes place when the substrate is not uniformly heated (or rapidly cooled) during the deposition process.

o Orientation of debris does not affect color filter as the colored rows are intact

o Field return (color image)

TFT Delamination


o Tooling damage is often identified on failed modules

Other Findings: Cleanliness, Damaged Components

Silicon

slivers

Chip-outs

Glass Ledge

Known Good Failed


o Anisotropic conductive particles will deform under heat and pressure. The expected shape is a slightly crushed “pacman” with uniformly sized particles.o The appearance of particle sizes varies

o The crush shape of the particles ranges from slightly deformed to completely flattened – indication of fast thermal ramp rates, non uniform heating and high bond force

Marginal Hot Bar Process

Misaligned no-connect COG Pad


The metallization bump on the COG is deformed at the interface

Particle Deformation Examples

Pressure：

Bump

Particle

ITO

Glass

6 MPa 40 MPa 100 MPa

Deformed Bump ⇒ Bump Short

IDEAL Suspect LCDs


o The perimeter of the glass sandwich is adequately sealed

o It is worth noting that the particulate matter seen in this image is on the surface of the glass

Perimeter Sealant

Sealant zone


o Though limited, the side ledge chip on glass is not as sufficiently covered with sealant as the bottom ledge chips.

o Allows for moisture ingress

Chip on Glass Protection

This region is not

covered in blue sealant

Appearance of peeling


o Note the voids beneath the COG

Poor ACA Fill


o Lifetime can be assessed using Peck’s Power Law with

testing in a temperature-humidity chamber

o Example: Corrosion of bond pads on the COG

Lifetime Expectancy

𝐴𝐹 =𝑅𝐻𝑡𝑒𝑠𝑡𝑅𝐻𝑓𝑖𝑒𝑙𝑑

−2.7

∗𝑉𝑡𝑒𝑠𝑡𝑉𝑓𝑖𝑒𝑙𝑑

1.5

∗ 𝑒𝑥𝑝𝐸𝑎𝑘𝐵

1

𝑇𝑡𝑒𝑠𝑡−

1

𝑇𝑓𝑖𝑒𝑙𝑑


o There are many challenges to select a reliable LCD

o Not all technologies have similar reliability

o Light or color degradation may dominate failure modes

o Materials will limit application environment

o Semiconductor and package scaling has increased

reliability/durability risks due to increased interconnects

o Bigger, higher resolution panels means more pixels are available

that can fail (all with the same probability of failure)

o Lot-to-lot qualification tests may be necessary to ensure reliability

(continuous monitoring)

o These challenges are manageable by applying best practices

in design for reliability early in the lifecycle

In Conclusion


ThanksEdward Wyrwas

301-640-5816

[email protected]

selecting a robust and reliable display...

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