I Reliability

7/30/2019 I Reliability

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Reliability

Motivation - 35 Years AgoSection 2: RELIABILITY AND QUALITY ASSURANCE REQUIREMENTS

2.2 R&QA REQUIREMENTS FOR PHASED HARDWARE DEVELOPMENT

2.2.2 STUDY/DEFINITION PHASE REQUIREMENTS

b. Development of preliminary mathematical model and reliability predictions.

(NPC 250-1)

c. Establishment of reliability and safety goals and other R&QA requirements in

preliminary specifications. (NMI 5320.1, NMI 5330.1, NPC 500-1).

2.2.3 DESIGN PHASE REQUIREMENTS

e. Development of mathematical models and reliability predictions. (NPC 250-1,

RA006-007-1)

g. Apportionment of reliability goals to equipments and components. (NPC 250-1)

Office of Manned Space Flight - Apollo Program. NHB 5300.1A, July 1966

Apollo Reliability and Quality Assurance Program Plan


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Reliability - 35 Years Ago

Missions

Contractor Reliability Estimates

Subcontractor and Design Group Estimates

Apollo Program Office - R&QA

Model IntegrationCenter Estimates

SC LV LC GOSS

Apollo Program Office - R&QA Review

Center Review

Contractor Review

Apollo

Mission

Reliability

Estimates

LEVEL RELIABILITY ANALYSIS AND MODELING ACTIVITY HARDWARE

I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IV . . . . . . . . . . . . . . . . . .

Mission/LaunchVehicle/Spacecraft/

Ground SupportSystems/Stage/

Module/Subsystem

Launch Vehicle/

Spacecraft/GroundSupport Systems/Stage/Module/

Subsystem/Black Box

Stage/Module/Subsystem/Black Box/Component

Subsystem/Black Box/

Component/Part

Office of Manned Space Flight - Apollo Program. NHB 5300.1A, July 1966

Apollo Reliability and Quality Assurance Program Plan


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Reliability


4/23

Reliability

Introduction to Reliability

Historical Perspective Current Devices

Trends


5/23

The Bathtub Curve

Time

Failure

rate,

Constant

Useful life Wear outInfant

Mortality


6/23

The Bathtub Curve (2)

What is the "bathtub" curve?

In the 1950s, a group known as AGREE (Advisory Group for the Reliability of Electronic

Equipment) discovered that the failure rate of electronic equipment had a pattern similar to the death

rate of people in a closed system. Specifically, they noted that the failure rate of electronic

components and systems follow the classical bathtub curve. This curve has three distinctive

phases:

1. An infant mortality early life phase characterized by a decreasing failure rate (Phase 1). Failure

occurrence during this period is not random in time but rather the result of substandard components

with gross defects and the lack of adequate controls in the manufacturing process. Parts fail at a high

but decreasing rate.

2. A useful life period where electronics have a relatively constant failure rate caused by randomly

occurring defects and stresses (Phase 2). This corresponds to a normal wear and tear period where

failures are caused by unexpected and sudden over stress conditions. Most reliability analysespertaining to electronic systems are concerned with lowering the failure frequency (i.e., constshown in the Figure) during this period.

3. A wear out period where the failure rate increases due to critical parts wearing out (Phase 3).

As they wear out, it takes less stress to cause failure and the overall system failure rate increases,

accordingly failures do not occur randomly in time.


7/23

Introduction to Reliability

Failure in time (FIT)

Failures per 109 hours

( ~ 104 hours/year )

Acceleration Factors

Temperature

Voltage


8/23

Introduction to Reliability (cont'd)

Most failure mechanisms can be modeled using the

Arrhenius equation.

ttf - time to failure (hours)

C - constant (hours)

EA - activation energy (eV)

k - Boltzman's constant (8.616 x 10-5eV/K)

T - temperature (K)

ttf = C eEA/kT


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Acceleration Factors

ttfLA.F. = ------

ttfH

A.F. = acceleration factor

ttfL = time to failure, system junction temp (hours)

ttfH = time to failure, test junction temp (hours)


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Activation EnergiesFailure Mechanism EA(eV)Oxide/dielectric defects 0.3

Chemical, galvanic, or electrolytic corrosion 0.3

Silicon defects 0.3

Electromigration 0.5 to 0.7

Unknown 0.7

Broken bonds 0.7

Lifted die 0.7

Surface related contamination induced shifts 1.0

Lifted bonds (Au-A1 interface) 1.0

Charge injection 1.3

Note: Different sources have different values -

these values just given for examples.


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Acceleration Factor - Voltage

Oxides and Dielectrics

Large acceleration factors from increase in

electric field strength

A.F. = 10 / (MV / cm)

k - Boltzman's constant (8.616 x 10-5eV/K)

T - temperature (K)

= 0.4 e0.07/kT


12/23

Acceleration Factor: Voltage

Median-time-to-fail of unprogrammed antifuse vs. 1/V for

different failure criteria with positive stress voltage on top

electrode and Ta = 25 C.


13/23

Integrated Circuit Reliability

Historical Perspective

Application Reliability

Apollo Guidance Computer < 10 FITs Commercial (1971) 500 Hours

Military (1971) 2,000 Hours

High Reliability (1971) 10,000 Hours

SSI/MSI/PROM 38510 (1976) 44-344 FITs MSI/LSI CICD Hi-Rel (1987) 43 FITs


14/23

Device and Computer Reliability

1960's Hi-Rel Application

Apollo Guidance Computer

Failure rate of IC gates:

< 0.001% / 1,000 hours ( < 10 FITS )

Field Mean-Time-To-Failure

~ 13,000 hours

One gate type used with large effort onscreening, failure analysis, and

implementation.


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Device Reliability:1971

Reliability Level of Representative

Parts and Practices MTBF (hr)

Commercial 500

Military 2,000

High Reliability 10,000 (104 hours)


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MIL-M-38510 Devices (1976)

Circuit Types Description FITS

5400 Quad, 2-input NAND 60

5482 2-bit, full adder 44

5483 4-bit, full adder 112

5474 Dual, D, edge-triggered flip-flop 72

54S174 Hex, D, edge-triggered flip-flop 152

54163 4-bit synchronous counter 120

4049A Inverting hex buffer 52

4013A Dual, D, edge-triggered flip-flop 104

4020A 14-stage, ripple carry counter 344

10502 Triple NOR (ECL) 80

HYPROM512 512-bit PROM 280


17/23

Harris CICD Devices (1987)

Circuit Types

HS-6504 - 4k X 1 RAM HS-8155/56 - 256 x 8 RAM

HS-6514 - 1k x 4 RAM HS-82C08RH - Bus Transceiver

HS-3374RH - Level Converter HS-82C12RH - I/O Port

HS-54C138RH - Decoder HS-8355RH - 2k x 8 ROM

HS-80C85RH - 8-bit CPU

Package Types

Flat Packs (hermetic brazed and glass/ceramic seals)

LCC

DIP

FITS @ 55C, Failure Rate @ 60% U.C.L.

43.0


18/23

Actel FPGAs

Technology FITS # Failures Device-Hours

(m)

2.0/1.2 33 2 9.4 x 107

1.0 9.0 6 6.1 x 108

0.8 10.9 1 1.9 x 108

0.6 4.9 0 1.9 x 108

0.45 12.6 0 7.3 x 107

0.35 19.3 0 4.8 x 107

RTSX 0.6 33.7 0 2.7 x 107

0.25 88.9 0 1.0 x 107

0.22 78.6 0 1.2 x 107


19/23

Xilinx FPGAs

XC40xxXL

Static: 9 FIT, 60% UCL

Dynamic: 29 FIT, 60% UCL

XCVxxx

Static: 34 FIT, 60% UCL

Dynamic: 443 FIT, 60% UCL


20/23

UTMC and Quicklogic

FPGA

< 10 FITS (planned)

Quicklogic reports 12 FIT, 60% UCL

UT22VP10UTER Technology, 0 failures, 0.3

Antifuse PROM

64K: 19 FIT, 60% UCL 256K: 76 FIT, 60% UCL


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RAMTRON FRAMs

Technology FITS # Failures # Devices Hours Device-Hours

1608 (64K) 1281 1 100 103 105

4k & 16K

Serial 37 152

4257 103

4.3 x 106

Note: Applied stress, HTOL, 125C, Dynamic, VCC=5.5V.

1 The one failure occurred in less then 48 hours. The

manufacturer feels that this was an infant mortality

failure.

2 12 failures detected at 168 hours, 3 failures at 500

hours, and no failures detected after that point.


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Actel FIT Rate Trends


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Skylab Lessons Learned58. Lesson: New Electronic Components

Avoid the use of new electronic techniques and components in

critical subsystems unless their use is absolutely mandatory.

Background:

New electronic components (resistors, diodes, transistors,

switches, etc.) are developed each year. Most push the state-of-

the-art and contain new fabrication processes. Designers of

systems are eager to use them since they each have advantages

over more conventional components. However, being new, theyare untried and generally have unknown characteristics and

idiosynchracies. Let some other program discover the problems.

Do not use components which have not been previously used in a

similar application if it can be avoided, even at the expense of

size and weight.

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