quality aspects_parts_final.ppt

(1)

Quality And Reliability

OF Electronic

Components

C.A. Ignatious

DD, VSSC (SR)

(2)

Definitions



Reliability

--

The ability of an item to

perform its requir

perform its required function un

ed function under

der

defined conditions for a stated period

of time

..



Failure

–

– The termination of the ability

The termination of the ability

of an item to

of an item to perform its required

perform its required

function

(3)

Definitions



Reliability

--

The ability of an item to

perform its requir

perform its required function un

ed function under

der

defined conditions for a stated period

of time

..



Failure

–

– The termination of the ability

The termination of the ability

of an item to

of an item to perform its required

perform its required

function

(4)

Degrees of Failure

Failures may be

SUDDEN

(non-

(non-predictable) or

predictable) or

GRADUAL

(predictable).

They may also be

PARTIAL

or

COMPLETE

..

A

Catastrophic failure

is both sudden and

complete.

A

Degradation failure

is both gradual and

partial.

(5)

Causes of Failure

M i s u s e

–

failures attributable to the

application of stresses beyond the

stated capabilities of the item.

In h e r en t W e ak n es s

–

failures

attributable to weakness inherent in

the item itself when subjected to

stresses within the stated capabilities

of the item.

(6)

Cost-Reliabil

(7)

MTBF & MTTF

M

ean

T

ime

B

etween

F

ailures

–

Applies to

repairable items.

M

ean

T

ime

T

o

F

ailure

–

Applies to non-

Applies to

non-repairable items.

repairable items.

Both of these terms indicate the average

time an item is expected to function

before failure.

(8)

Failure Rate vs Time

Early Failures

Early Failures – – substandardsubstandard

components, manufacturing faults.

Random Failures

Random Failures – – this is thethis is the

useful lifetime of the item.

Reliability is predictable in this

region.

End-of-Life Failures

End-of-Life Failures – – itemsitems

reaching the end of their useful life.

Also called the

Also called the wear-out period.wear-out period.

Because of the characteristic shape, this

is commonly known as the “Bathtub C

(9)

Useful Lifetime

t m

R

e

  Reliability is predictable. R = reliability.

t = time for which equipment is run. m = MTBF

Note that R has no units. The prediction yields a number <1.

(10)

Examples

If an item of equipment has MTBF of 500hrs, then the reliability for 100hrs operation is :- ₁₀₀

500

e



= 0.8187 (81.87% probability of survival)

and if the equipment is operated for 1000hrs, the reliability will be

:-500 1000

e



(11)

Failure Rate

 Failure unit = 1 FIT = 1 failure/1000000000 (9 zeroes) device hrs  Example: System with 100,000 discrete parts, has one failure per

month, then the failure rate

 l = 1 failure / 100,000/(30x24 hrs) = 14 E -9 = 14 FIT

 Summary:

 FIT Failures/month # devices failing in 10 years  10 0.7 0.1%

 100 7.0 1.0%

 1000 70 10%

 A failure rate of about 10 FIT is needed.

 At 1000 FIT there are about 2 failures/day and the entire system

(12)

Testing Time to Reliability

 Testing and Proving Reliability is very Expensive as Illustrated

in These Tables

 Table 1: For 100 devices on test

FIT Test Time for 1 failure (Years)

10 114

100 11

(13)

Accelerated Testing

 Stresses are used to accelerate failure. For example

temperature cycling is used to accelerate mechanical failure.

 Temperature Acceleration  Voltage Acceleration

 Current Acceleration  Humidity Acceleration

 Different failure mechanisms may be accelerated by different

(14)

Accelerated Life

 The bathtub curve predicts a high

early failure rate.

 Elevated temperatures are used to

accelerate component aging and ensure that products move from the Early Failure area and into the

Useful Lifetime area.

 The technique is used to pre-screen

early failures during manufacturing.

High temperatures accelerate all known chemical

reactions. Almost all failure mechanisms associated

with semiconductor devices are the result of a

chemical reaction

(15)

Arrhenius Equation

=

Rate of the chemical reaction.

=

A constant.

e =

Activation energy in electron volts (eV) that is associated with the chemical reaction.

K =

Boltzman’s constant.

T =

Absolute temperature. 0 A E KT

r



r e

r



r

0 r

(16)

Acceleration Factor

is the elevated temperature. is the temperature for which the new reaction rate is calculated. Is the reaction rate at the

elevated temperature. Is the reaction rate at

1 T 2 T 1 r 2 r T ₂

The constant, , is the same for both temperatures and has been cancelled out of

the equation 0 r

















1 2

1

2

1 K

T

E

_A

e

r

(17)

Acceleration Fctor

 Acceleration Factor and Time Equivalent to 40 Years

Time Equivalent to Acceleration Factor 40 years in Hours

Temp (°C) Ea = 1.0 eV Ea=1.0 eV 300 2.2e6 0.2 250 3.2e5 1.1 200 3.1e4 11 150 1700 200 125 300 1,200 85 11.5 30,000  Temp Ambient = 60 °C

(18)

Failure Mechanisms



Electrostatic Discharge



Alpha-Particle-Induced Soft Errors



Radiation Hard Devices



Metal Electromigration



Sodium Metal Migration in Gate Oxide



Hot Electrons



Oxide Breakdown



Latch Up in CMOS Circuits



Metallisation Corrosion

(19)

Design &

Manufacture

Pre-Production Design Control of Production Working Tolerances Material Quality Component Quality Component Stress

Installation &

Environmental

Temperature Humidity Vibration Chemical Attack Interconnections

Factors Affecting

Reliability

(20)

Factors Affecting

Reliability

Installation

&

(21)

Temperature

Generally, Operation at higher

temperatures degrades reliability

performance. Internally generated heat must be removed by mechanisms such as cooling fins or forced-air.

In high ambient temperatures, the process of removing excess heat becomes more difficult.

Equipment operating in low ambient temperatures will need to be

designed using components

(22)

Humidity

Moisture can cause oxidation and corrosion and reduce insulation effectiveness. Particularly vulnerable are solder joints and connectors.

Equipment designed for use in areas of high humidity will use components and materials which are

selected for their resistance to damage by moisture.

Vulnerable components, such as circuit boards, can be protected by encapsulation e.g. in resin.

(23)

Vibration

Vehicles (cars, ships, aircraft etc) are particularly prone to vibration

damage.

Vulnerable equipment can use flexible mountings.

Components on a PCB can be made less susceptible to vibration by the use of encapsulation.

Vibration effects on electronic components has been minimised by the process of miniaturisation.

(24)

Interconnections

Interconnections are liable to degradation by vibration,

humidity and chemical factors. They are one of the

most vulnerable components in an electronic system.

(25)

Factors Affecting

Reliability

Design

&

(26)

Component Reliability

Typical Failure Rates of Electronic Components

Component Type Failure Rate (%/1000h)

Capacitors Ceramic 0.001 Paper 0.005 Tantalum 0.01 Electrolytic 0.01 Diodes Silicon 0.001 Resistors Carbon 0.001 Wirewound 0.001 Film 0.001

Transistors Discrete Silicon 0.01

Connections Soldered 0.001

(27)

Operating Stresses

Weighting Factors for Electronic Components

Component Operating Condition Weighting Factor

Resistors 0.1 of max. rating 1.0

Transistors 0.5 of max. rating 1.5

Diodes 1.0 of max. rating 2.0

Capacitors 0.1 of wkg voltage 1.0

0.5 of wkg voltage 3.0

max wkg voltage 6.0

}

System Failure Rate =

[

(Component Failure Rate) x (Quantity) x (Weighting Factor)

]



Mil std 217 gives very detailed system failure rate prediction based on component failure rate and end use

(28)

IC Fabrication – An

Introduction

(29)

Integrated circuit

showing

memory blocks,

logic and

input/output

pads around the

periphery

(30)

(31)

(32)

Silicon chip High lead solder die attach

Tin/lead plated copper leadframe

(33)



Front-End Processing (Wafer fabrication)



Back-End Processing (Assembly and

Testing)

Semiconductor Fabrication

Processes

(34)

A logic circuit diagram is drawn to determine the

electronic circuit required for the requested

function.

Once the logic circuit diagram is complete,

simulations are performed multiple times to test the

circuit’s operation.

Logic Circuit Design / Layout

Design

(35)

Photomask Creation



The photomask is a copy of the circuit pattern, drawn

on a glass plate coated with a metallic film.



The glass plate lets light pass, but the metallic film

does not.



Due to increasingly high integration and

miniaturization of the pattern, the size of the

photomask is usually magnified four to ten times the

actual size.

(36)

The

photomask

of a

RF IC

Chip

(37)

Wafer Fabrication



A high-purity, single-crystal silicon called

"99.999999999% (eleven-nine)" is grown from a

seed to an ingot.



The wafers are generally available in diameters of

150 mm, 200 mm, or 300 mm, and are

mirror-polished and rinsed before shipment from the

wafer manufacturer.

(38)

Deposition



the wafer is placed in a high-temperature furnace to

make the silicon react with oxygen or water vapor, and

to develop oxide films on the wafer surface (thermal

oxidation).



To develop nitride films and polysilicon films, the

chemical vapor deposition (CVD) method is used, in

which a gaseous reactant is introduced to the silicon

substrate, and chemical reaction produce the deposited

layer material.



The metallic layers used in the wiring of the circuit are

also formed by CVD, spattering (PVD: physical vapor

deposition)

(39)

Photoresist Coating



A resin called "photoresist" is coated over the

entire wafer. (~1μm thick coating.)



Photoresist is a special resin similar in

behavior to photography films that changes

properties when exposed to light.

(40)

Masking/Exposure



Placed over the photoresist-coated wafer, which

is then irradiated to have the circuit diagram

transcribed onto it.



An irradiation device called the "stepper" is used

to irradiate the wafer through the mask with

ultraviolet (UV) light.

(41)

Lithography area in clean room

(42)

(43)

Etching



"Etching" refers to the physical or chemical etching

of oxide films and metallic films using the resist

pattern as a mask.



Etching with liquid chemicals is called "wet

etching" and etching with gas is called "dry

etching".

(44)

Photoresist Stripping



The photoresist remaining on the wafer surface

is no longer necessary after etching is complete.

Ashing by oxygen plasma or the likes is

(45)

Device Insulation Layer

(Field-Oxide Film) Formation



After the oxide film and nitride film are

developed, a resist pattern is formed on the

regions that will become the device

insulation layer.



Ion implantation is performed on the wafer,

forming a p-type diffusion layer.



Next, the oxide film and nitride film on the

diffusion layer are etched.



Using the nitride film pattern as the mask,

the oxide film that will become the device

insulation layer is developed.

(46)

(47)

Transistor Formation



An insulation layer called "gate oxide" is first

formed on the wafer surface.



A polysilicon film is deposited onto the gate

oxide, and a polysilicon gate for controlling

the flow of electrons between the source

region and the drain region is formed by

lithography and etching.



After the polysilicon gate is formed, an

n-type diffusion layer consisting of both the

source and the drain regions is formed by

implantation of impurities

(48)

Polysilicon Gate

(49)

Metallization



Interconnecting the devices, such as transistors, formed

on the silicon wafer completes the circuit.



the wafer is first covered with a thick and flat interlayer

insulation film (oxide film). Next, contact holes are

drilled by lithograph and etching, through the

interlayer insulation film, above the devices to be

connected.

(50)

Wafer Inspection



Each IC on the completed wafer is electronically

tested by the tester.



After this inspection, the front-end processing is

(51)

(52)

Dicing



In back end processing, a wafer completed in

front end processing is cut into individual IC

chips and encapsulated into packages.

(53)

Mounting



After the IC chips are cut apart, they

are sealed into packages. The IC chips

must first be attached to a platform

called the "lead frame“.

(54)

Wire bonding



The mounted IC chips are connected to the

(55)

Encapsulation



The IC chips and the lead frame islands are

encapsulated with molding resin for

protection.

(56)

Characteristic Selection



The packaged IC chips are tested and

(57)

Printing and Lead Finish



The final step of IC chip manufacturing is the

printing onto the package surface and the

finishing of leads. After this step, the IC

chips are complete.

(58)

Types and Causes of Defects

Resistive open due to unfilled via [R. Madge et al., IEEE D&T, 2003]

Particle embedded between layers

(59)

Process and Operational Variations

Even if there isn’t a complete short

or open, resistance and capacitance

(60)

Yield and Its Associated Costs

15-30 cm 30-60 cm Silicon crystal ingot Slicer Processing: 20-30 steps Blank wafer with defects x x x x x x x x x x x 0.2 cm Patterned wafer (100s of simple or scores of complex processors) Dicer Die ~1 cm Good die ~1 cm Die tester Microchip or other part Mounting Part tester Usable part to ship

(61)

The dramatic decrease in yield with larger dies

Effect of Die Size on Yield

120 dies, 109 ood 26 dies, 15 ood

Shown are some random defects; there are also bulk or clustered defects that affect a large region

(62)

Effects of Yield on Testing and Part

Reliability

Assume a die yield of 50%

Out of 2,000,000 dies manufactured, 1,000,000 are defective

To achieve the goal of 100 defects per million (DPM) in parts shipped, we must catch 999,900 of the 1,000,000 defective parts

Therefore, we need a test coverage of 99.99%

Testing is imperfect: missed defects/faults (coverage), false positives Going from a coverage of 99.9% to 99.99% involves a significant

(63)

High-rel Parts



Space Grade parts Class S/JAN S



Mil grade parts ClassB/JANTX/JTXV



Qualified & Certified Production Line



Devices produced as per Qualified Process



Products Qualified to Mil/Space level



100 % Screening as per Mil Std/883 or Mil Std 750



LAT/ Certificate for every batch



Standard electrical/environmental Specification

(64)

Mil Standards for Avionics

Parts

(65)

QML Parts

 MIL-PRF-38535: "General Specification for microcircuits (IC)

Manufacturing" - Supersedes MIL-M-38510

 Microcircuits manufactured, assembled, and tested according to

MIL-PRF-38535 bear the "QML” certification mark

 Class Q: Hermetic products. Military level covered by

MIL-PRF-38535 main body + appendixes C, D, E, F, G, H, J.

 Class V: Space level: class Q + appendix B requirements.  Class M: covered by MIL-PRF-38535 appendix A. Require a

vendor self certification. DSCC performs verification audit only

 Class N: plastic parts.

(66)

MIL-PRF-19500: General Specification

for Semiconductor Devices

 Supersedes MIL-S-19500 ; Refers to MIL -STD-750 test

methods

 Quality levels: classes JAN, JANTX, JANTXV, JANJ,

JANS

 Class JAN: Military level QCI Only

 Class JANTX: Screening and QCI without Visual

inspection

 Class JANTXV: JANTX with Visual inspection

 Class JANJ: Space level product as defined in the

specification sheet that can pass test and inspections in Appendix E for JANTXV as a minimum. Not available for

all semiconductor devices.

(67)

Standards for Hybrids

MIL-PRF-38534/MIL-STD-883 are the controlling

specifications for hybrids.

Hybrids are made to class H or class K.

Class H requirements form the baseline.

The K level parts involve extra pre-build inspections of

components, post-build inspections and testing

(68)

Passive Parts : Established Reliability

 The reliability rating are established on the basis

of life tests for various Failure Rates

 Exponential distribution with 60% confidence level

and 10-percent producer's risk

 M : 1.0 % per 1000 hours  P : 0.1 % per 1000 hours  R: 0.01 % per 1000 hours  S : 0.001% per 1000 hours

 Weibull distribution with 90% confidence level

 B: 0.1 % per 1000 hours  C: 0.01 % per 1000 hours  D : 0.001% per 1000 hours

(69)

Style and Type Reference Specification

Fixed Ceramic Dielectric

CKR/CKS

>1uF, use CKS only

MIL- PRF-39014

Fixed Mica Dielectric CMR MIL-PRF-39001

Fixed Tantalum Solid Electrolytic

CSR MIL-PRF-39003

Fixed Ceramic Chip CDR MIL-PRF-55681

Fixed Tantalum Chip

_–

Solid Electrolytic

CWR MIL-PRF-55365

Fixed Tantalum-Non Solid Electrolytic

CLR MIL-PRF-39006

(70)

Fixed Carbon

Composition(Insulated)

RCR MIL-R-39008

Fixed Metal Film RLR MIL-PRF-39017

Fixed Wire Wound RWR MIL-PRF-39007

Fixed Wire Wound Power Type

RER MIL-PRF-39009

Variable - Film/Foil RJR MIL-PRF-39035

Variable

_–

Wire Wound RTR MIL-PRF-39015

Fixed ,Film Networks MIL-R 83401

Thermistor RTH MIL-PRF-23648

(71)

Power Inductors/

Transformers

MIL-PRF-27

MIL-PRF-21308

RF fixed colis

MIL-PRF-39010

Chip inductors

MIL-PRF-83446

Variable inductors MIL-PRF-15305

(72)

Connectors

Style and Type

Reference Specification

Circular

MIL-DTL-38999,MIL-C-26482

D Sub miniature

-Rectangular crimp type

-Flat type

MIL-DTL-24308

Microminiature

MIL-DTL-83513

Printed Circuit

Angled spills

MIL-DTL-55302,MIL-C-24308

Coaxial(RF connectors)

MIL-PRF-39012

MIL-STD-1553 Data Bus

MIL-PRF-49142

Push pull connectors

MIL-C-81703

(73)

Switches, fuses, wires and cables

Push switches

MIL-PRF-8805

Fuses

MIL-PRF-23419

Coaxial cable

MIL-C-17

PTFE / Spec 55 insulated wires

MIL-DTL-22759/86

MIL-W-16878

(74)

Quality level for launch

vehicles

Microcircuits Parts listed in QML class Q/B

Parts listed in ESCC/DSCC/ JAXA QPL including non-S

Discrete parts Jan TX/JTXV

Hybrids

Class H/ Indigenous Class B/S

Passive

Parts

Established Reliability level S / R

RF and

Microwave

(75)

Quality level for satellite

applications

Microcircuits Parts listed in DSCC QML Class V/S

or equivalent in QPL of ESCC /JAXA/ DSCC

Discrete parts Jan S

Hybrids

Class K/ Indigenous Class S

Passive

Parts

Established Reliability level S / R

RF and

Microwave

(76)

Parts to be avoided in new designs



Parts not qualified to MIL/ESA spec



Parts that are obsolete and not available



Parts listed in MIL/ ESA/ NASA/ ISRO alert

system for quality issue



Parts having export license issue



Parts for which criticality and / or quality issues

were faced in ISRO applications in the past (eg.

LT1086)

(77)

The Preferred Parts List

 Components listed in the VSSC Preferred Parts List (PPL) only

are used for launch vehicle applications.

 P a r t A : Parts listed in Part A are qualified as per

MIL/ESA-SCC/ISRO GSS/BS9000 (Hi-rel MIL specifications) and are available as standard MIL parts from manufacturers.

 P a r t B : Parts which are not qualified to Hi-rel MIL specifications.

These are non-MIL devices based on experience in usage and qualification tests conducted by VSSC.

 P a r t C : Parts which are not qualified to Hi-rel MIL specifications.

These are non-MIL devices. based on experience in usage and qualification tests conducted by VSSC. Recommended only for Non-critical applications.

(78)

Parts quality- NASA experience

 One study Reviewed DOD’s satellite and missile

systems and NASA systems

 Parts quality problems affected all 21 programs reviewed

 They caused cost over runs and schedule delays.

($250M and 2 year delay in one case)

 More problems were associated with electronic parts

(65%) than mechanical (15%) parts or materials (20%).

 Explained by presence of more electrical components than mechanical devices.

 US government recommends action for preventing,

(79)

Parts Quality Assurance

Requirements



Assurance of procurement from qualified

sources or their authorized distributors



Quality Conformance Inspection (QCI) to

ensure that each lot meets the spec



Receiving inspection to verify compliance

with the controlling specifications



Screening to remove defective parts



DPA to be performed when part is not QML

(80)

Application Criteria

Requirements

.

 Derating guidelines shall be met by the design

 Operating Environment requirement including

temperature, humidity, shock, and vibration should be met by the part spec.

 For most space applications, military qualified parts will

satisfy these requirements except for radiation

 Effects of the projected ionizing radiation on each part

shall be determined.

 Failure mitigation or a design margin shall be established by the project

(81)

Manufacturing and handling

requirements

 ESD control in accordance with MIL-STD-1686  Environmental controls such as temperature and

humidity during parts handling, packaging, and storage.

 Rescreening if a maximum period has elapsed since

screening

 Procured quantities should allow for nominal fallout of

parts in screening.

 Parts should be ordered from a single date code for

effectiveness of qualification

 Ensure part compatibility with planned manufacturing

processes.

 Parts affected by ALERTS shall not be used in

manufacturing

 Traceability : identifying which package contains specific

(82)

Pure Tin finish on IC leads



Pure tin (Sn) coatings mandated by

regulations on leads and other surfaces of

parts.



Pure tin electroplates develop tin whiskers.



May result in a visible "electrical short“



The short may result in fusing of the

whisker, but the device would have

damaged aleady.

(83)

Reliability analysis

 Failure mode effects and criticality analysis

 Analyses the effect of each part failure mode

 Ranks each failure mode based on criticality of the result and the probability of occurrence

 Worst case analysis

 Verifies the circuit operation at all combinations of input conditions and part parameters

 Carried out by dividing to smaller blocks

 Part Stress Analysis

 Failure rates increase exponentially with stress on part (voltage, current and power dissipation )

 Analysis ensures that stresses are below the maximum rating of the part

(84)

Failure rate of components - The bath

tub curve

(85)

Nature of failures during life

cycle



Initial failures result from contaminations and

process variations



Such devices are removed by high voltage stress

tests at wafer probing or by burn-in tests on

packaged device



Random failures are triggered by electrical noise,

electrostatic discharge and electrical overstress

and enhanced by minor defects



Wear out failures result from electro-migration, hot

carrier effect, time dependent dielectric break

down etc

(86)

Causes of field failure- EOS

and ESD

 An EOS event can be a momentary event lasting only

milliseconds or can last indefinitely.

 EOS can be the result of a single g event or the result

of ongoing periodic or non-periodic events.

 EOS is a lower voltage (<100V) and large peak current

(>10A) event that occurs over longer time frame (generally >1ms).

 ESD is a very high voltage (generally >500V) and

moderate peak current (~1A to 10A) event that occurs

(87)

Possible causes of EOS

o

Uncontrolled voltage surge on the power

supply.

o

Voltage spikes due to internal PCB switching.

o

Voltage spikes due to an external connection

o

capacitive charge on an external cable,

antenna pick-up of external switching noise,

inductive loads.

o

Poor grounding resulting in excessive noise.

o

Overshoot or undershoot during IO switching.

o

EMI due to poor shielding

o

ESD events that weaken the device.

o

Latch-up events

(88)

Non mil grade parts

 Availability of military standard electronic parts diminishing

 State of the art parts available only in commercial and industrial

grades

 Devices in small foot print packages available

 Initial (acquisition ) cost is less.

 Wider operating temperature range (-55°C to 125°C) than

(89)

Concerns with non mil parts



Time to obsolescence in some cases is as low

as one to two years; Re-procurement may not be

possible.



No alternate manufacturer for most parts



A manufacturer uses a number of fabs, packaging

houses, test houses etc. Reliability can vary

from lot to lot.



Traceability is poor. Many devices do not have

even date code information

(90)

Concerns with Non mil grade parts (contd..)

 Design compromises like reduced metallization and oxide

layer thickness reduce reliability.

 Design for a life of less than 5 years is normal

 Process changes incorporated by manufacturer are unknown to

customers and may have negative impacts for space applications.

 Device may not have sufficient EOS/ESD protection built in to its

design

 Lack of characterization data for space environment

 Radiation performance

 Insufficient environmental/ mechanical/ electrical testing

(91)

Additional Concerns with PEMS



Parts in plastic packages absorbs moisture leading to

corrosion



Popcorn effect due to absorbed moisture



Thermal cycling induced cracking, delamination, die

detachment or damage to metal conductors



Recommended to use metal clad PCBs



Traces of radio active materials in molding compound

(92)

Failure rate comparison : mil and non-mil



Failure rate of PEMs from reputed

manufacturers like Analog Devices,Texas etc.

are comparable to Mil std parts.



However, humidity and thermal cycling

(93)

NASA policy on usage of PEMs



Use of PEMs is permitted on NASA spaceflight

applications, provided

Each use is thoroughly evaluated for thermal,

mechanical, and radiation implications of the

specific application and if

found to meet

mission requirements.



PEMs shall be selected for their functional advantage

and availability, not for cost saving



The steps necessary to ensure reliability usually negate

any initial apparent cost advantage.



A PEM shall not be substituted for a form, fit and

functional equivalent, high reliability, hermetic device

in space flight applications.

(94)

VSSC policy for induction of Industrial

grade parts



Recommended for Telemetry applications only



Industrial grade parts of higher reliability or temperature range

(-55

°

C to 125

°

C) are preferred



QMB approves the usage after considering



Criticality of the parameter for which the particular part has

been selected



Manufacturer assessment



Destructive Part Analysis Result



Qualification test result

(95)

Use of non mil parts in NGC applications



More stringent control needed in procurement, storage,

qualification and screening for critical applications.



Procurement should be only from reputed manufacturers



Storage and ESD conditions prior to procurement should

be known



Procurement should be made in as few date code codes

as possible and each lot should subjected to sample

DPA and qualification.



Screening flow to incorporate C-SAM test, which is found

to be very effective in detecting cracks, debonds and

delaminations.

(96)

Non-ER versus ER parts : Example of

Multi-layer Ceramic Capacitors :

Attribute Non-ER MIL-ER Smallest Chip

Sizes 0201_{01005 (new to market)} 0805 Lowest Voltage

Ratings 6.3 V 50 V

No. of sources Numerous Few

Delivery time Days to weeks Weeks to Months Procurement

Costs Small large

Vendor Design

Rules Variable & Aggressive Stable &Conservative Qualification Basis Non Standard Standard

Process Material

Change More frequent, withoutnotice to user Less frequent,needs re qualification