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HALT & ALT Case Studies

David Rahe

Business Development Manager, DLi Labs

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Today’s Ask the Expert Presenter

David RaheBusiness Development Manager

DLi Labs

3201 Industrial Terrace, Austin, TX 78758

www.dlinnovations.com/labs/

drahe@dlinnovations.com

512-775-4001

© 2009 Qualmark Corporation

Presentation Summary

Introduction to Accelerated Life Testing

Product Life Cycle

Environmental Stress

Reliability Planning

HALT & ALT

HALT: Qualitative

ALT: Quantitative

Case Studies

HALT

ALT

Examples of Common HALT Failures

Q&A

© 2009 Qualmark Corporation3

Accelerated Life Testing

A higher stress produces the same failures as occur

at use stress, except occur more quickly

Time-to-fail at use stress multiplied by a constant

(the acceleration factor) to obtain the equivalent

time-to-fail at high stress

Based on product defined usage models

Linear relationship

Models (predicts time-to-fail as a function of stress):

Arrhenius

Eyring

Inverse Power

© 2009 Qualmark Corporation5

Accelerated Life Testing

► Coffin-Manson

► Halberg-Pecht

► Others

Manufacturing

Final Test

Storage

Packaging

Shipping

Installation

Calibration

Maintenance

© 2009 Qualmark Corporation

6

Normal Use

Portable vs. Stationary

Vehicle mounted (cab, engine, frame)

Controlled environments

(indoor/outdoor)

Space, sub-sea, desert, tropics, etc.

Mis-Use

Repair

Product Life Cycle

Temperature

Temperature Cycling

Humidity

Vibration

Shock

Dust

Water

Electrical

© 2009 Qualmark Corporation7

Sulfur

Altitude

Chemical

ESD

Impact

Wear

Environmental Stresses

Reliability Planning

Understand the Product Life Cycle

Identify the various stresses associated with each

phase of the Life Cycle

Consider how to accelerate those stresses

Develop a test strategy to apply the accelerated

stresses

Identify critical components (i.e. high stress, new

technology, high risk)

Number of samples

Product functional test/exercise defined

Test Budget

Scheduling © 2009 Qualmark Corporation8

HALT & ALT

Design Verification TestingDemonstration of performance to a specification

within product usage environments

Reliability Margin TestingInduce stress to identify design margins; design weaknesses

Quick results

Reliability Demonstration/Quantification

Determine warranty periodLong term testing; multiple samples

Product Test SuiteA Comprehensive Test Program Includes all 3 Phases

Minimal Testing

Better Product Testing

-20

0

20

40

60

80

100

12:0

7:16

PM

12:2

3:56

PM

12:4

0:35

PM

12:5

7:15

PM

1:13

:55

PM

1:30

:36

PM

1:47

:16

PM

2:03

:55

PM

2:20

:35

PM

2:37

:16

PM

2:53

:55

PM

Temp Setpoint °C

Vib Setpoint G

Vib Product G

Air Temp °C

Product Temp °C

#190 °C

#257 °C

© 2009 Qualmark Corporation11

Subjective: information gathering, exploratory

Discover Design Weaknesses

Strength vs. Stress Testing

Step Stress Test to Failure

Temperature Cycling with Multi-Axes Vibration

Failures provide understanding of margins

Product

Specs

Stress

Uppe

r

Destr

uct

Limit

Lower

Destruct

Limit

Destruct MarginDestruct Margin

Upper

Operating

Limit

Lower

Operating

Limit

Margin

Operating

Margin

Operating

Qualitative: HALT

HALT: Highly Accelerated Life Test

© 2009 Qualmark Corporation12

Objective: defined, statistics, pre-knowledge

Assess product life (hrs. or cycles/actuation)

Determine warranty period

Longer test duration with multiple samples

Time Compression (2 Methods)

1. Increase Cycles or Run Time

2. Increase Stress Level

ALT: Accelerated Life Test

Quantitative: ALT

Case Studies

*Customer case study details are DLi Labs confidential

Case Study Introduction

Case Study # 1: IT Product

Purpose: HALT and ALT during Design

Case Study # 2: Test/Measurement Product

Purpose: HALT of Production to Duplicate Field Failure and

Perform Failure Analysis of Failure

Case Study # 3: Payment Terminal Product

Purpose: HALT of Production to Duplicate Warranty

Problems and Perform Failure Analyses

Case Study # 4: Server Cabinet Rails

Purpose: ALT to Qualify Supplier Components

© 2009 Qualmark Corporation14

Case Study #1: IT Product

Product Details:

2u, 19” Rack Chassis

Major Life Cycle Stresses

Temperature – during use

Mechanical stress - during shipping

© 2009 Qualmark Corporation15

Case Study #1: IT Product

HALT Results

Temperature

Operating limits: -30°C to 65°C (component failure)

Vibration

Operating limit: 10Grms, daughter board mounting method

Interface Board: Piezo alarm leads shorting to chassis

Capacitor lead fractures (line filter CY1, CY13)

Connectors (Power, User Interface) backed-out

Internal ground strap floating, PEM nut not secure

© 2009 Qualmark Corporation16

Case Study #1: IT Product

17

Capacitor Damage Cable Release

Piezo Shorting & Cable Release Daughter Bd. Connector Release

Case Study #1: IT Product

ALT Stress

Temperature

Normal Use: 35°C

Accelerated: 60°C

ALT Results

Arrhenius method of modeling thermal effects on

electronic components

5 samples for 75 days

Acceleration Factor = 11

Weibull Analysis on ALT failures determined the

product Mean Time to Fail would be 19,329 hrs (2.2

years, or 805 days) under normal operation© 2009 Qualmark Corporation18

ReliaSoft Weibull++ 7 - www.ReliaSoft.com

Probability - Weibull

Time, (t)

Unre

liabil

ity, F

(t)

10000.000 100000.00010.000

50.000

90.000

99.000Probability-Weibull

Data 1Weibull-2PMLE SRM MED FMF=3/S=2

Data PointsProbability Line

Target Rel

Dave RaheSchlumberger10/26/200912:35:06 PM

Case Study #2: Test/Measurement Product

Bench Use

Major Life Cycle Stresses

Temperature – during use

Mechanical stress - during shipping, bench handling

HALT Results

Temperature

Operating limit: -45°C to 60°C (fan failure)

Vibration

Operating limit: 20 Grms

© 2009 Qualmark Corporation19

Case Study #2: Test/Measurement Product

Failure Analysis of Fan Circuit

Electrical Analysis

Measured voltage, current, power of circuit components

Comparison of both good and suspect fans

Result: Gate drive levels are proper/within spec.

Thermal Analysis

Thermocouple FETs and critical circuit components

Infrared analysis

Results: Failure temperature rise is 100°C (normal 30°C vs.

bad 130°C)

X-Ray Analysis

No evidence of wire bond, fractured or defective solder joints,

material voids, electro-chemical migration

© 2009 Qualmark Corporation20

Case Study #2: Test/Measurement Product

© 2009 Qualmark Corporation21

Thermocouple

FETsCurrent FETs

Thermal Image

X-Ray Controller IC

X-Ray

Controller IC

X-Ray FET

Case Study #2: Test/Measurement Product

Conclusion

Q1 output shorted, causes temperature rise beyond

specification (Tj=125°C)

Creates additional load share on 2nd phase motor drive

FET

NPN Silicon Switching Power Transistors (FET) are

defective on the failing fans

Die failure results in collector/emitter short

Manufacturing defect is related to 2 bad lot codes

© 2009 Qualmark Corporation22

Case Study #3: Payment Terminal Product

Credit Card Scan and Touch Screen

Production with Unacceptable Warranty Returns

#1 Premature Battery Field Failure (Primary)

#2 LCD Display (Secondary)

Major Life Cycle Stresses

Temperature, Humidity, Corrosive Gases – during use and

customer storage

Mechanical stress - during shipping and use

© 2009 Qualmark Corporation23

Case Study #3: Payment Terminal Product

HALT Results

Temperature

Operating limits: -20°C to 70°C (LCD failure)

Vibration

Operating limit: 25 Grms (Capacitor C6, C21 lead fractures)

Combined

Operating limit: 15 Grms and 70°C (backlight failure)

© 2009 Qualmark Corporation24

Case Study #3: Payment Terminal Product

ALT Stress

High Temperature & Humidity

Cold Temperature

Safety intrusion circuit electrical simulation

70°C and 85%RH for a period of 60 days

Normal usage environment of 25°C and 50%RH

Target 5 year product life

Acceleration factor of 71 using an aggressive Halberg-

Pecht model

Measure battery and product degradation over the 60 day

10 samples

© 2009 Qualmark Corporation25

Case Study #3: Payment Terminal Product

ALT Results

Battery:

Active load increased by ~1000% under stress

Intrusion circuit generated multiple open/short events

60% of samples developed battery failure

Recreated battery failures in < 26 days (12~14 months

estimated life)

LCD:

Recreated LCD Backlight failure in 7 of 10 samples

© 2009 Qualmark Corporation26Conclusion: Field failures occur due to storage conditions

Intrusion Drain Battery Voltage

0

0.5

1

1.5

2

2.5

3

3.5

4

24 36 48 60 72 144 156 168 180 192 204 216 228 300 324 348 372 636

Time in Hours

Batt

ery

Vo

ltag

e

BATT 7 BATT 8 BATT 9 BATT 10

Battery Drain Over Time

0

100

200

300

400

500

600

24 36 48 60 72 144 156 168 180 192 204 216 228 300 324 348 372 1164

Time in Hours

Cu

rre

nt

in u

Am

ps

DUT 6 IDC

Case Study #3: Payment Terminal Product

© 2009 Qualmark Corporation27Conclusion: Field failures occur due to storage conditions

Intrusion Component

Battery Voltage vs. Time

Battery Current vs. Time

Current Spike

Case Study #4: Server Cabinet Rails

Product Life Cycle Stresses:

Thermal, Humidity, Corrosive Gases

Qualify Plating Method

9 samples (galvanized, zinc plated, zinc w/clear chromate)

ALT Stresses: Corrosion

High Temperature & Humidity (90°C and 80% RH)

High Temperature & Humidity with Sodium Chloride (1% NaCl

35°C and 90% RH)

High Temperature & Humidity with Sulfur Dioxide (~100 ppb,

35°C and 90% RH)

High Temperature & Humidity with Sodium Chloride and Sulfur

Dioxide (~100 ppb, 1% NaCl 35°C and 90% RH)

© 2009 Qualmark Corporation28

Case Study #4: Server Cabinet Rails

ALT Results

Test Group A

Test Group B

Test Group C

Conclusion: Group A is a superior plating process

© 2009 Qualmark Corporation29

Examples of HALT Failures

Common HALT Failures

© 2009 Qualmark Corporation31

Capacitors

Common HALT Failures

© 2009 Qualmark Corporation32

Capacitors

Corrective

Action

Common HALT Failures

Crystals

Common HALT Failures

Power Transistors/FETS

Lead fracture damage

Electrical shorting

© 2009 Qualmark Corporation34

Common HALT Failures

Coils/Inductors: Lead fractures

© 2009 Qualmark Corporation35

Common HALT Failures

© 2009 Qualmark Corporation36

Heat Sink Dislodged

Plastic glass transitionDIMM dislodged

Broken Fan Blade

Damaged traces

Resister pack lead fractures

Chassis wear

ALT and HALT are both valuable tools

Each provide product reliability information

How to apply each process is critical

Both tests should consider the product Life Cycle

environment

Failure Analysis/Root Cause and Corrective Action

must be included

THANK YOU !!

© 2009 Qualmark Corporation37

Conclusion

Questions?

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© 2009 Qualmark Corporation

Today’s Speaker:

David Rahe, Business Development Manager

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