The document presents an introduction to the physics of failure and reliability methods, highlighting the importance of understanding failure mechanisms to improve product integrity and reliability. It outlines various failure categories, the proactive approach of reliability physics, and the limitations of traditional product development processes in effectively detecting failures. The document encourages participation in reliability webinars and outlines the qualifications of presenter James McLeish, emphasizing the need for better engineering practices in product reliability.

1. Introduction to
Introduction to
Physics of Failure
Physics of Failure
y
Reliability Methods
James McLeish
©2011 ASQ & Presentation James
Presented live on Feb 09th, 2012
http://reliabilitycalendar.org/The_Re
liability_Calendar/Webinars_
liability Calendar/Webinars ‐
_English/Webinars_‐_English.html

2. ASQ Reliability Division
ASQ Reliability Division
English Webinar Series
English Webinar Series
One of the monthly webinars
One of the monthly webinars
on topics of interest to
reliability engineers.
To view recorded webinar (available to ASQ Reliability
Division members only) visit asq.org/reliability
) /
To sign up for the free and available to anyone live
webinars visit reliabilitycalendar.org and select English
Webinars to find links to register for upcoming events
http://reliabilitycalendar.org/The_Re
liability_Calendar/Webinars_
liability Calendar/Webinars ‐
_English/Webinars_‐_English.html

3. Webinar Series
• Next Sessions
English series
Thursday, March 8, 2012, Noon - 1:00 pm EDT
TOPIC: Field Failure Analysis Using Root Cause Pattern Diagrams
BY: Bob Lloyd
Thursday, Apr 12, 2012, Noon - 1:00 pm EDT
TOPIC: The Proper Analysis Approach for Life Data
BY: Dr. Huairui Guo
Chinese series
Beijing Time: Feb 15, 2012; 11:00AM – 12:00PM
TOPIC: Rapid Reliability Demonstration Tests (快速可靠性验证试验)
BY:Guangbin Yang (杨广斌) Reliability and Quality Supervisor （可靠性与质量主管）
• www.reliabilitycalendar.org under webinars and short courses
• for full schedule
• Recordings at www.asq.org/reliability under webinars or short
courses

4. Announcements
We are looking volunteers to support the following programs:
Webinars
Newsletter
The Reliability Calendar
Websites
New Member Welcome
And other programs
Discussion groups (ASQ forums & Linkedin)
We invite you to join our ranks as a member
visit www.ASQ.ORG/membership
Questions, comments, suggestions, or desire to volunteer
or presenter, please contact: chair@asqrd.org

5. Brought to you in part by…

6. Today’s Speaker
James McLeish
Bio: James McLeish is a senior technical staff consultant
and manager of the Michigan office of DfR (Design for
Reliability) Solutions, a Failure Analysis, Laboratory
Services and Reliability Physics Engineering Consulting
Firm headquartered in College Park Maryland.
Mr. McLeish is a senior member of the ASQ Reliability Division and a core
member of the SAE’s Reliability Standard Committee with over 32 years of
automotive and military E/E experience in design, development, validation
testing, production quality and field reliability. He has held numerous technical
expert and management position in automotive electronics product design,
development, vehicle electrical system integration, product assurance,
validation testing and warranty problem solving as an E/E Reliability Manager
and E/E Quality/Reliability/Durability (QRD) technical specialists at General
Motors.

7. Introduction to Physics of Failure
Reliability Methods
James McLeish ASQ Reliability Division Webinar Feb. 9, 2012
jmcleish@dfrsolutions.com
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ

8. Physics of Failure / Reliability Physics Definitions
o Physics of Failure - A Formalized and Structured approach to
Root Cause Failure Analysis that focuses on total learning
and not only fixing a current problem.
o To achieve an understanding of “CAUSE & EFFECT” Failure Mechanisms
AND the variable factors that makes them “APPEAR” to be Irregular Events.
o Combines Material Science, Physics & Chemistry
with Statistics, Variation Theory & Probabilistic Mechanics.
o A Marriage of Deterministic Science with Probabilistic Variation Theory
for achieving comprehensive Product Integrity and Reliability by Design Capabilities.
o Failure of a physical device or structure (i.e. hardware)
can be attributed to the gradual or rapid degradation of the material(s) in the device
in response to the stress or combination of stresses the device is exposed to, such as:
o Thermal, Electrical, Chemical, Moisture, Vibration, Shock, Mechanical Loads . . .
o Failures May Occur:
o Prematurely because device is weaken by a variable fabrication or assemble defect.
o Gradually due to a wear out issue.
o Erratically based on a chance encounter with an
Excessive stress that exceeds the capabilities/strength of a device,
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 7

9. Physics of Failure / Reliability Physics Definitions
o Reliability Physics (a.k.a. the PoF Engineering Approach)
- A Proactive, Science Based Engineering Philosophy
for applying PoF knowledge for the
Development and Applied Science of
Product Assurance Technology based on:
o Knowing how & why things fail is equally
important to understand how & why things work.
o Knowledge of how thing fail and the root causes of failures
enables engineers to identify and avoid unknowingly creating
inherent potential failure mechanisms in new product designs
and solve problems faster.
o Provides scientific basis for evaluating usage life and hazard risks of
new materials, structures, and technologies, under actual operating conditions.
o Provides Tools for achieving Reliability by Design
o Applicable to the entire product life cycle
o Design, Development, Validation, Manufacturing, Usage, Service.
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 8

10. The Traditional View of Quality, Reliability & Durability (QRD)
- Product Life Cycle Failure Rate “Bath Tub” Curve
Focuses on 3 Separate & Individual Life Cycle Phases
End of Useful Life
each with Separate Control & Improvement Strategies /Typ. Replacement
Decision Pt.
The Bath Tub Curve
Problem or Failure Rate
(Sum of 3 Independent Phenomena)
But “True” Root Causes Can Be Disguised by
Actuarial Assumptions to Make QRD Easy to Administer
This is an Inaccurate & Misleading Point of View
Durability = Wear Out
Quality = Infant Mortality
(End of Useful Life)
Reliability = Random or Chance Problems
(Constant Unavoidable)
Time 0 1 Year 2 Years 3 Years 4 Years 5 Years
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 9
9

11. A “PoF FAILURE MECHANISM” Based “REALISTIC” View
Reveals the True Interactive Relationships Between Q, R & D
- Real failure rate curves are irregular, dynamic and full of valuable information,
not clean smooth curves to simplify the data plots.
Manuf. Variation & Error Weak Designs That
Problem or Failure Rate
and Service Errors Start to Wear Out
That Cause Latent Prematurely
Problems Throughout Life
“Cause & Effect” Root Causes
Can Be Disguised by Actuarial Statistics
Once Problems Are Accurately Categorized
You Have Realistic Picture of “True Root Causes”
TRUE Random
Problems
Are Rare Once
Correlated to
“ACTS OF
GOD & WAR”
Time 0 1 Year 2 Years 3 Years 4 Years 5 Years
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 10
10

12. Traditional Reliability Growth in Product Development
Empirical “TRIAL & ERROR” Method to Demonstrate Statistical Confidence
4)
Faults No
1) Design 2) Build 3) Test
Detected
DESIGN - BUILD - TEST - FIX ?
(D-B-T-F) Yes
5) Fix Whatever
Breaks.
6) REPEAT 3-5
Until Nothing Else
Today, This Is Not Enough! Breaks Or You Run
1) All design issues often not well defined. Out Of
2) Early build methods do not match final processes. Time/Money.
3) Testing doesn’t equal actual customer’s usage.
4) Improving fault detection catches more problems, but causes more rework.
5) Problems found too late for effective corrective action, fixes often used.
6) Testing more parts & more/longer tests “seen as only way” to increase reliability.
7) Can not afford the time or money to test to high reliability.
8) Incremental improvements from faster more, capable tests still not enough.
It Is Time for a Change
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 11

13. QRD in Product Development
- Reliability Growth Verses the QRD Challenge
o Challenges:
o Increasing Electrical/Electronic Content & Complexity
o Increasing % of System Cost
o Increasing Device Complexity 90
o Increasing Power consumption (Heat)
o Increasing Functionality & Software Complexity 80
1st MY
70
o Rapid & Constant Technology Growth 2nd MY
3rd MY
o Lesson Learned Constantly Changing 60
4th MY
o Rapidly Outdated 50
DPTV
5th MY
o Lack of Understanding & Confusion 40 6th MY
o Design Issues That Effect QRD 30
o Manufacturing Issues Effect QRD
20
o Outdated Paradigms 10
o MIL HDBK 217 for Reliability Assessment
0
and tracking 0 6 12 18 24 30 36 42 48 54 60
o “Test & Fix” Dev./Val. Growth
Months After Sale
o Lack of Reliability by Design
o Annual Reappearance of Problems
o Fire Fighting
o Hardy Perennials
o Uneven Supply Chain Learning Curve
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 12

14. The Traditional Product Development Process (PDP) Approach is
A Series of Design - Build - Test - Fix Growth Events
Emphasis Emphasis Emphasis
Sketchy/ Design QRD+P Costly Watch &
Loosely then Growth by Redesign Start Study
Defined Build Rounds of /Retool Production Warranty
Req’mts Product Test Dev/Val Fixes
Process
Part 1: Part 2:
Formal Lab & Track Dev/Val Trial Customers Become the Unwitting
& Error Approach to Test Subjects in Continued Trial
Finding & Fixing Problems. & Error Tests in the Real World
Essentially Formalized Trial & Error
That Starts With Product Test – To Be Good Enough To Start Production
Then Evolves Into Continuous Improvement Activates
In Responses to Warranty Claims
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 13

15. Reliability/Capability Growth with Traditional D-B-T-F Product
Development Processes Takes Years to Achieve Maturity
1.00
D Initial Prod. 94% R / 6% Fr.
E Dev. Emphasis
S on Performance
I .90 & Functional w/
G Non-Production
N Intend HW
.80
C Duane Model
A Simplification of
P Reliability Growth
A .70
B Capability / Reliability
I Growth Actually Occurs in
L Incremental Steps
I .60
Mid Prod. Dev.
T
Emphasis on
Y
/ .50 Packaging & Final Prod. Dev.
R HW Durability Emphasis on
E w/Prod. intent Manufacturing
Process & Continuous Production
L HW & Non-
I .40 Prod. Intent Quality
A Manuf. w/Prod. Intend
B HW & Manuf.
I .30
L
Design Alpha HW Beta HW Proto Production Production Production Production
I Proj. Team (Funct. Dev.) (DV)
Pilot Prod.
(PV) & Ramp up 1st Yr. 2nd Yr. 3rdt Yr. 4th Yr.
T Concept Start B-T-F1 B-T-F2 B-T-F3 B-T-F4 P-W-F1 P-W-F2 P-W-F3 P-W-F4
Y 14
© 2011 - 2010
© 2012 DfR2007
2004 & ASQ 14

16. If Parts Past Qualification Testing , Why Do Field failures Still Occur
Statistically Confident - Probability of Detection X Sized Issues out of # of Y Parts
Not Very Effective for Issues Below 5% of Population
D-B-T-F is
Probability of Detecting a Problems of Size “X” with “N” Parts on Test Effective For
Finding a Few
Big-Medium
Sized
Problems
10%
5%
2%
1%
0.5%
0.2%
0.1%
0.05%
But D-B-T-F is
Ineffective For
Finding Many
Small
Problems
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 15

17. Is the Solution Better Faster Reliability Growth Tests like HALT:
Better Tests Do Find/Fix Field Some Problems Faster, But is this Enough?
1.00
D
But Best in Class 98-99R @SOP
E
S
I
G .90
N More Capable .97R => 3% Failures
Accelerated Tests by 2nd Model Year
C
A .80 Enables Faster
P Reliability Growth BETTER QRD
A (Evolutionary ACHIEVED FASTER
B Improvement)
I .70
L Implement Over Traditional Reliability
I
T 6 Years Growth
Y .60
/
R
E
L .50
I
A 10-15% FASTER PRODUCT
B DEVELOPMENT
I .40
L
I
T
Y
.30
Production Production Production Production
Proj. . Alpha HW Beta Proto 1st Yr. 2nd Yr. 3rdt Yr. 4th Yr.
Launch
Concept (Funct. Dev.) (DV) (PV) Pilot & P-W-F1 P-W-F2 P-W-F3 P-W-F4
Dsgn B-T-F1 B-T-F3 Ramp up
Team B-T-F2
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ B-T-F4 16

18. Key PoF Terms and Definitions
o Failure Mode:
o The EFFECT by which a failure is OBSERVED, PERCEIVED or SENSED.
o Failure Mechanism :
o The PROCESS (elect., mech., phy., chem. ... etc.) that causes failures.
o FAILURE MODE & MECHANISM are NOT Interchangeable Terms in PoF.
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 17

19. Key PoF Terms and Definitions
o Failure Site :
o The location of potential failures, typically the site of a designed in:
o stress concentrator ,
o design weakness or
o material variation or defect.
o Knowledge Used to Identify and Prioritized Potential Failure Sites and Risks in New
Designs During PoF Design Reviews.
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 18

20. 3 Generic PoF Failure Categories and
Their Evaluation/Detection Methods
GENERIC FAILURE CATEGORY TYP. FAILURE DETECTION
o Errors - Incorrect Operations & Quality
Variation Defects/Weaknesses.
o Missing parts, incorrect assembly or process. Assurance
o Process control errors (Torque, Heat treat). Immediate or
o Design errors Latent defects
o Missing functions,
o Inadequate performance.
o Inadequate strength.
o Overstress. Performance
Overheating.
o
o Voltage/Current
Capability
o Electro static discharge. Assessments
o Immediate yield, buckling, crack.
o Wearout/Changes,
via Damage Accumulation. Stress-Life
o Friction wear. Durability
o Fatigue.
o Corrosion. Assessments
o Performance changes/parameter drift
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 19

21. Generic Failure Categories
Errors and Variation Issues are Everywhere
 Errors Broadest Category  Variation
 Errors in Design, Manufacturing, Usage & Service.
 Fine line between excessive variation & out
 Missing knowledge right errors.
 Human factor Issues.  Both related to various quality issues.
 Manufacturing equipment wear out & failure could
be related to maintenance errors.
 Weak material could be raw material variation or
insufficient heat treat processing errors.
Interface Equipment  Equipment process capabilities limitation or
operator set up error.
Design & Process
People
Performance
Usage
Material Environment
Noise Factors
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 20

22. Generic Failure Categories
Overstress - When Loading Stress Exceed Material Strength
STRESS/
STRENGTH
Variation of Design’s Material Strengths
Typical
- Related to Process Capabilities
Deterministic
(Nominal) Analysis
DESIGN MARGIN
4
How well  3
2
SAFETY FACTOR

do you | 
Understand 9
| UNRELIABILITY = Probability
9 |
& Design 9 3 6 that Load Exceed Strength
For % 9
%
Strengths t t %
t Stress Variation of Usage &
& Stresses? i i
l i Environments Loads &
l l
e e
Their Interactions
e FREQUENCY OF OCCURRENCE
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 21

23. Overview of How Things Age & Wear Out
- Stress Driven Damage Accumulation in Materials
3. Strain :
Instantaneous changes
(materialsstructural) due
2. Stress to loading, different loads
The distribution/ interact to contribute to a
transmission of single type of strain.
loading forces
Knowledge of how/ which
throughout
“Key Loads” act & interact
the device.
is essential for “efficiently”
developing good products,
6. Time to Mean Failure: processes & evaluations.
(Damage Accumulation verses Yield Strength
1. Loads
A Function of: Stress Intensity, Material
Elect. Chem. Properties, & Stress Exposure Cycles/Duration].
Thermal, Mech...
4. Damage
7. Project the Distribution About the Mean Accumulation
Individual or
combined, from
i.e. Rate of Failure (Fall out) (or Stress Aging):
A function of variation in; Usage, Device Strength Permanent change
environment &
& Process Quality Control (i.e. latent defects). degradation retained
usage act on
materials & 5. Failure Site & Type: after loads are removed.
structure. Typically due to a designed in: stress concentrator , From small incremental
design weakness, material/process variation or defect. damage, accumulated
during periods/cycles
of stress exposure.
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 22

24. Generic Failure Categories - Wearout (Damage Accumulation)
- Over Time of Stress Exposure
STRESS INDUCED
STRESS/ DAMAGE
STRENGTH
ACCUMULATION
Design’s Strength
Decay/Spreads Over
Time / Usage
Material Decay
Increases
UNRELIABILITY
OVER TIME
4
How well 3 STRESS
  2 EXPOSURE TIME
do you | |  or USAGE CYC’S
Understand 9 9 |
& Design 9 3 6 INITIAL
For % 9 UNRELIABILITY
Strengths %
t t %
& Stresses? i i
t
l i
l l
e e e FREQUENCY OF OCCURRENCE
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 23

25. Generic Failure Categories
Examples of Wear Out Failure Mechanism
o Mechanical  Chemical / Contaminate
o Fatigue  Moisture Penetration
o Creep  Electro-Chemical-Migration Driven
o Wear Dendritic Growth.
o Electrical  Conductive Filament Format (CFF)
o Electro-Migration Driven  Corrosion
Molecular Diffusion & Inter Diffusion  Radiation Damage
o Thermal Degradation
o When Over Stress Issue are Detected.
o Verify supplier’s are meeting material strength specs & purity expectation.
o Re-evaluate field loading / stress expectation used to design the part.
o Sort out stresses,
o Combined stress issues are often involved.
o Re-evaluate effectiveness of product durability testing
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 24

26. Two Types of Circuit Board Related
Vibration Durability Issues
o Board in Resonance o Components In Resonance.
o Components. Shaken Off/Fatigued o Components Shake/Fatigue themselves apart or
by Board Motion. off the Board.
o By Flexing Attachment Features o Especially Large, Tall Cantilever Devices
3 Med. Sized Alum CAPS
Lead Motion 1 Small Long Leaded Snsr
Bending Lead Wires - Flexed Down 1 Hall Effect Sensor.
Stressed - Normal
Solder
1 Large Coil Assembly
Gull Wing I.C. - Flexed up
Joint
Displacement PC Board
 Time to Failure Determine by
Intensity/Frequency of Stress Verses Solder Fatigue Life
Strength of Material Log (Peak Strain)
Steinberg’s Criterion:
For a 10 million cycle life, Z < 0.0008995·B/(C·h·r (L1/2)).
Ref: Vibration Analysis for Electronic Equipment, by David S. Steinberg
Log (Number of Cycles to Failure)
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 25

27. PCB Vibration - 1st, 2nd & 3rd Harmonic Modals
1st Harmonic 2nd Harmonic
3rd Harmonic
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 26

28. PoF Example
– E/E Module Vibration Analysis
Connector Provides Primary PCB Support CAE Modal Simulation of Circuit Board Flexure
Original CAE Guided Redesign
Transformer
A Large Mass,
Adds Back Edge Support
will drive a Large Board Displacement (mils) 13.95 1.15
Vibration Modal Natural Frequency (Hz) 89 489
Response
Vib. Durability Calculation 25 Days > 50 Years
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 27

29. Module Vibration Durability Simulation Results
- For Alternative Board Support & Transformer Locations
DAYS TO
FAILURE ORIGINAL TRANSFORMER LOCATION TRANSFORMER RELOCATED
@ 2 Hrs
Vib / Day || R101
+ R102
1000M || R825
+ R824
100 M
10 M
1M
100,000
3650 Days
10,000 (10 Years)
1000
100
10
1
Edge1 Edge1 & Edge1 & Edge1, Edge1 & All Edges Edge1 Edge1 & Edge1 & Edge1, Edge1 & All Edges
(Connector) Corners Middle Corners Edge2 (Connector) Corners Middle Corners Edge2
& Middle, & Middle,
|| + || + || + || + || + || + || + || + || + || + || + || +
|| + || + || + || + || + || + || + || + || + || + || + || +
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 28

30. Generic Failure Categories
- Shock
o Animated Simulation Visualizes Transition of the
Shock Wave Through the Structure of the Module.
o Peak Stresses, Material Strain, Motions &
Displacements Can be Identified.
o Potential Failure Sites Where Local Stresses
Exceed Material Strength Can Be Identified &
Prioritized.
o Zoom In On Surface Such as Potential for Snap
Lock Fastener Release
o Wire Frame View Allows Xray Vision of Internal
Features.
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 29

31. Solder Thermo-Mechanical Shearing Fatigue Driven by:
Coefficient of Thermal Expansion/Contraction (CTE) Mismatch During Thermal Cycling
o As a circuit board and its components expand and contract at different
rates the differential strain between them is absorbed by the
attachment system leads and solder joints which drives metal fatigue.
Coef. Of Thermal Exp. (PPM/°C)
• Chip Resistor Body: 4-5 ppm/°C
• PCB - FR4 x-y axis: 14-17 ppm/°C
FR4 z axis: 120-160 ppm/°C
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 30

32. Correlation Between: Stress Driven Damage Accumulation in Materials
and Life Consumption Rates
o Material N-S Curve (Number of Life Cycle at a Stress Level) (Transposed S-N) .
High Useful Acceleration Range
(log)
Number
of Foolish Failure Region
Cycles INVALID TEST REGION
Low Stress
~ Near “Infinite” Low
Life Region
Low Stress (log) High
o Stress - Strain Yield Curve. Plastic Region
Excessive Plastic
High
Deformation
STRESS
(psi) Instantaneous or
Near Instantaneous
Low Ultimate Strength or
Elastic Region Fracture Point
Low STRAIN in/in High
o Lowering the Stress in Material & Members Increases Life &Reliability
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 31

33. Solder Fatigue Life is Directly Related to Component Packaging & Solder Attachment Scheme
Generally the IC Package Influences QRD more than the IC itself.
Single Sided Then Thru-hole 1st Generation Quad Surface Mount 2nd Generation Quad Surface Mount
DIP Integrated Circuits J Lead PLCC, 1982 - Today Fine Pitch Gull Wing I.C, 1993 - Today
1970 ‘s- Today ~6 Up to 160 I/O, 1.5 in sq., ~54 Up to 450 I/O, 1.75 in sq
~4 up to 68 I/O, 1” x 3.5” Up to 100 Meg Hz Speeds Up to 250 Meg Hz Speeds
Up to 10 Meg Hz Speeds. Source of Many Reliability Problems. >10 Time the Life of J Lead in Auto ECMs.
Bump & Ball Grid Arrays No Lead Chip Scale Packaging (NLCSP)
Leadless Attachments (LCCC, QFN, DFN, SON, LGA)
1996 - Today 2002 - Today
~24 - 1000 I/O 1.2 in. sq ~8 - 480 I/O, .75 in SQ
500+ 1000 Meg Hz Speeds. Gigi Hz Speeds
Life Varies Greatly w/Size & Conf. Can have significantly reduces life
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 32

34. Comparison of Through Hole Component Attachment Schemes
- Impact of Structural Configuration & Size on Fatigue Durability
Package I.C. Die & Die Attachment
Wire Bond
Lead Frame
Lead @ Cold Lead @ Cold
Single Sided Solder Joint Lead @ Hot Double Sided (PTH) Joints
Allow Leads to Wiggle are 35- 55 TIMES Stronger
Under Vib., Shock & Lead is constrained
Thermal Exp/Contraction So the Rate of Fatigue
the Joint Fatigues Faster DIP - Thru-hole Stress Aging is Much Slower
Automotive Fatigue Life Automotive Fatigue Life
Single Sided 2-5 Yrs Single Sided >10 Yrs
o Since Electrical Engineers Design Most Circuit Boards,
o The motivation to accepted the added costs of Plated Through Hole (PTHs) was when increasing component
required placing component and traces on both sides of the circuits board.
o THE RELIABILITY OF EE MODULES SKY ROCKETED with the use of more complex Double Sides PCB.
o Thus More Complexity DOES NOT ALWAYS HAVE TO RESULT IN LESS RELIABILITY.
A More Capable or Smarter Design Approach
Can Overcome the Inherent QRD Risks of Increased Complexity
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 33

35. Comparison of Leaded Surface Mount Attachment Schemes
- Impact of Structural Configuration & Size on Fatigue Durability
S. M. Pad & Solder Joint
Surface Mount Devices with Gull Wing Fine Pitch Leads
J lead - Surface Mount Devices Are Designed as an Articulated Spring,
- Thermal Exp/Contraction Their Leads Flex at Two Bend Points
Cause Rapid Fatigue Due To Lead Rocking Instead of Transmitting Stress to the Weaker Solder
Similar Sized GWFP Devices
Avg. 10x the Durability Life of
J Leaded Parts in the Same Thermal Cycling Tests.
The Cost – GLFP Devices Take Up More Board Areas
So Larger Boards May Be Require to
Hold the Same Number of Components
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 34

36. PoF Thermal Cycling Solder Fatigue Model
(Modified Engelmaier – Leadless Device)
o Modified Engelmaier LD
o Semi-empirical analytical approach Dg  C DaDT
o Energy based fatigue hs
o Determine the strain range (Dg)
o Where: C is a function of activation energy, temperature and dwell time,
LD is diagonal distance, a is CTE, DT of temperature cycle & h is solder joint height
Determine the shear  LD LD hc  2   
a 2  a1  DT  LD  F        hs
o
 
force applied at the  9G a 

solder joint  E1 A1 E2 A2 AsGs AcGc  b  
o Where: F is shear force, LD is length, E is elastic modulus, A is the area, h is thickness,
G is shear modulus, and a is edge length of bond pad.
o Subscripts: 1 is component, 2 is board, s is solder joint, c is bond pad, and b is board
o Takes into consideration foundation stiffness and both shear and axial loads
(Models of Leaded Components factor in lead stiffness / compliancy)
Determine the strain energy F
o
DW  0.5  Dg 
dissipated in the solder joint As
Calculate N50 cycles-to-failure using: N f  0.0019  DW 
o 1
o An Energy Based model for SnPb
N f  0.0006061  DW 
1
o The Syed-Amkor model for SAC
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 35

37. Originally Stress Analysis and PoF Modeling was a Time Consuming Process
Requiring an Expert to Create a Custom Finite Element Analysis of Individual Issues
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 36

38. PoF CAE Thermal Cycling Simulation - Reveals Issues That Could
Never Be Seen or Measured in a Physical Test
BGA IC CTE = 10 PPM/°C
Sheering Simulated
Strain in Thermal
Solder Balls Cycle of
0 to +100°C
Circuit Board CTE = 15 PPM/°C
View of the outer edge balls with
motion originating from the neutral center of the Quad BGA IC.
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 37

39. PoF Durability/Reliability Risk Assessments
PCB Plated Through Hole (PTH) Via Fatigue Analysis
o When a PCB experiences thermal cycling the expansion/
contraction in the z-direction is much higher than that in the
x-y plane.
o The glass fibers constrain the board in the x-y plane but not
through the thickness.
o As a result, a great deal of stress can be built up in the
copper via barrels resulting in eventual cracking near the
center of the barrel as shown in the cross section photos.
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 38

40. Plated Through Hole Via Barrel Cracking
Fatigue Life Based On IPC TR-579
o Determine applied stress applied (σ)
o Determine strain range (∆ε)
o Apply calibration constants
o Strain distribution factor, Kd(2.5 –5.0)
o PTH & Cu quality factor KQ(0 –10)
o Iteratively calculate cycles-to-failure (Nf50)
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 39

41. Through PoF Research Durability/Reliability Simulations for
Virtual Reliability Growth of Electronics are Now Possible
Start Build & Program Model(s) Integrated
with PoF/PoS Validate into Standalone Simple for Into a
Mechanism PoF / PoS Complex FEA Sophisticated
Knowledge Math Models Math Data Tools CAE Tool.
Add in Statistical Account for Operational
Tools for Variation Loading Drift
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 40

42. PoF Knowledge Enables A New Product Development Process
Math to Hardware
MATH TO
HARDWARE
A) Durability / Reliability Simulations – “A” Analysis
o Evaluate Durability Capability and
o Identify Specific Reliability Risks
o While Still on the CAD Screen
B) First Article Evaluation via Direct Quality Assessments – “D” Development
o Verify PCB Fabrication and Assembly Quality Meets Design Requirement
o Before Starting Stress Life Testing
C) Refocused Physical Durability Testing – “V” Validation
w/Simulation Aided Accelerated Testing
o Refocused from a Discover Process to a Final Conformation Procedure
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 41

43. The Auto Industry Has Reaped Significant PDP & QRD Benefits
Through Math Based, Virtual, Computer Aided Engineering Tools
Safety
Vehicle Structure Energy
A Result of
Initiatives to:
Migrate
Evaluations Performance Integration
from Road Thermal Vehicle Dynamics
to Lab
to Computer,
at the
Vehicle, Aerodynamics Noise & Vibration
Subsystem &
Component Durability
Level
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 42

44. A CAE Software Programs are now Commercially Available to
Automate CAE PoF Model Creation and Analysis
1) Design Capture – Utilize standard CAD/CAM
Circuit Board design files to create a virtual model
2) Life-Cycle Characterization - define the reliability/durability
objectives and expected environmental & usage conditions
(Field or Test) under which the device is required to operate
3) Load Transformation – automated FEA creation and
calculations that translates and distributes the
environmental and operational loads into the stresses
across a circuit board to each individual parts
4) PoF Durability Simulation/Reliability Analysis
& Risk Assessment – Performs a design and application
specific durability simulation to calculates detail life
expectations, reliability distributions over a life tine line
& prioritizes risks by applying PoF algorithms.
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 43

45. 1) Semi Automated Design Capture From CAD/CAM files
to create a CAE Virtual Model of a Product Design.
o Creates CAE virtual model from standard circuit board
CAD/CAM design files (Gerber or ODB Format)
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 44

46. 2) Define Test or Field Environment and Usage Profiles
o Define simple or complex environmental or test stress profiles
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 45

47. 3) Load Transformation in to Stresses - Automated FEA Mesh Creation and
Calculation of Stress/Strain Distribution Across the Device and at Each Component
o Days of FEA modeling and
calculations, executed in minutes
o Without a FEA modeling expert.
Finite Element Mesh
1st Natural Frequency 3rd Natural Frequency
2nd Natural Frequency
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 46

48. 4) Stress/Strain Results Become Inputs to PoF Durability/ Reliability Damage Models To
Calculate and Tally Durability Life Curve for Each Component & Each Failure Mechanism
Parts With Low Fatigue Endurance
Found In Initial Design
~84% Failure Projection
Within Service Life,
Starting at ~3.8 years.
o N50 fatigue life calculated for each of 705 components (68 part types), of a Safety Critical
Avionics Module with risk color coding, prioritized risk listing and life distribution plots based on
known part type failure distributions (analysis performed in <30 secs after model created).
o Red - Significant portion of failure distribution within service life or test duration.
o Yellow - lesser portion of failure distribution within service life or test duration.
o Green - Failure distribution well beyond service life or test duration.
(Note: N50 (i.e. Mean) life - # of thermal cycles where fatigue of 50% of the parts are expected to fail)
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 47

49. 5) PoF Durability Simulations/Reliability Risk Assessment
Enables Virtual Reliability Growth
o Identification of specific reliability/durability limits or deficiencies,
of specific parts in, specific applications, enables the module
design to be revised with more suitable/more robust parts capable
of meeting reliability/durability objectives.
o Reliability plot of the
same project after
fatigue susceptible
parts replaced with
electrically equivalent
parts in component
packages suitable for
the application.
o Life time failure risks reduced from ~84% to ~1.5%
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 48

50. 5) PoF Durability Simulations/Reliability Risk Life Curves for Each Failure
Mechanism Tallied to Produce a Combined Life Curve for the Entire Module.
Over All
Module
Combined
Failure Rate
Thermal
Vibration
Cycling
Fatigue
Solder
Wear Out
Fatigue
Wear Out
PTH Thermal
Cycling Fatigue
Wear Out
Constant Failure Rate
Generic Actuarial MTBF Database
o Detailed Design and Application Specific PoF Life Curves are Far More
Useful that a simple single point MTBF (Mean Time Between Failure) estimate.
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 49

51. The Efficiency Improvements of a PoF Knowledge & Analysis Based Product
Development Process
D .99R => 1% Failures
E 1.00 Simulation Based PDP
S Enables Dramatic
I “Revolutionary” Improvement
G in Growth Rate
N .90
BETTER QRD
C ACHIEVED FASTER
A
P .80
A Traditional Reliability
B Growth
I
L .70
I More Capable Accelerated Tests
T Enables Faster Reliability Growth
Y (Evolutionary Improvement)
/ .60
R
E
L
I .50
A FASTER PRODUCT
B DEVELOPMENT
I
L = LOWER COSTS
.40
I
T
Y
.30
Alpha HW Production Production Production Production
Proj. . Proto Launch
(Funct. Dev.) 1st Yr. 2nd Yr. 3rdt Yr. 4th Yr.
Concept (PV)
Dsgn B-T-F1 Beta B-T-F3 Pilot & P-W-F1 P-W-F2 P-W-F3 P-W-F4
Team (DV) Ramp
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ
Start B-T-F2 up 50
50

52. Summary - Physics of Failure/Reliability Physics is
Reliability Science for the Next Generation
o PoF Science based Virtual Validation Durability Simulation/
Reliability Assessments Tools Enable Virtual Reliability
Growth that is:
o Faster and Cheaper than Traditional Physical
Design, Build, Test and Fix Testing.
o Determines if a Specific Design is Theoretically Capable of
Enduring Intended Environmental and Usage Conditions.
o “Stress Analysis” Followed by “Material Degradation/Damage Modeling”
o Compatible with the way modern products are designed and engineered
(i.e CAD/CAE/CAM).
o Semi Automated PoF CAE Tools Enables Rapid, Low Cost Analysis
Without a Highly Trained CAE/PoF expert.
o Produces Significant Improvement In Accelerated Fielding of High QRD Products
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 51

53. Want to Know More – Suggested Reading
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 52

54. Questions & Discussion
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 53

55. Follow Up
o To Learn More about Physics of Failure
Durability Simulation / Reliability Assessment Tools,
o To Request a PDF Copy of the Presentation Slides
o Contact: jmcleish@dfrsolutions.com , or
askdfr@dfrsolutions.com 301-474-0607
o Thank You for Attending.
© 2012 DfR2007
© 2011 - 2010
2004 & ASQ 54