More than Just Lines on a Map: Best Practices for U.S Bike Routes
HALT to HASS to HASA
1. How to Move from HALT
to HASS to HASA
for
QualMark Open House
by
Mike Silverman, CRE
Managing Partner, Ops A La Carte LLC
mikes@opsalacarte.com // www.opsalacarte.com // (408) 472-3889
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2. Presenter Biography
• Mike is founder and managing partner at Ops A La Carte, a Professional Consulting Company
that has in intense focus on helping customers with end-to-end reliability. Through Ops A
La Carte, Mike has had extensive experience as a consultant to high-tech companies, and
has consulted for over 125 companies including Cisco, Ciena, Siemens, Abbott Labs, and
Applied Materials. He has consulted in a variety of different industries including power
electronics, telecommunications, networking, medical, semiconductor, semiconductor
equipment, consumer electronics, and defense.
• Mike has 20 years of reliability and quality experience. He is also an expert in accelerated
reliability techniques, including HALT&HASS, testing over 500 products for 100 companies
in 40 different industries. Mike has authored and published 7 papers on reliability techniques
and has presented these around the world including China, Germany, and Canada. He has
also developed and currently teaches 10 courses on reliability techniques.
• Mike has a BS degree in Electrical and Computer Engineering from the University of Colorado
at Boulder, and is both a Certified Reliability Engineer and a course instructor through the
American Society for Quality (ASQ), IEEE, and Effective Training Associates. Mike is a
member of ASQ, IEEE, SME, ASME, PATCA, and IEEE Consulting Society and is an officer
in the IEEE Reliability Society for Silicon Valley.
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3. RELIABILITY INTEGRATION
“the process of seamlessly
cohesively integrating reliability
tools together to maximize
reliability and at the lowest
possible cost”
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4. Reliability vs. Cost
♦ Intuitively, one recognizes that there is some
minimum total cost that will be achieved when an
emphasis in reliability increases development and
manufacturing costs while reducing warranty and
in-service costs. Use of the proper tools during the
proper life cycle phase will help to minimize total
Life Cycle Cost (LCC).
9
CRE Primer by QCI, 1998
5. Reliability vs. Cost, continued
TOTAL
COST
OPTIMUM CURVE
COST
POINT RELIABILITY
PROGRAM
COSTS
COST
WARRANTY
COSTS
RELIABILITY
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6. Reliability vs. Cost, continued
In order to minimize total Life Cycle Costs (LCC),
a Reliability Engineer must do two things:
♦ choose the best tools from all of the tools
available and must apply these tools at the proper
phases of a product life cycle.
♦ properly integrate these tools together to assure
that the proper information is fed forward and
backwards at the proper times.
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7. Reliability vs. Cost, continued
As part of the integration process, we must
choose a set of tools at the heart of our program
in which all other tools feed to and are fed from.
The tools we have chosen for this are:
HALT and HASS
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8. HALT and HASS Summary
♦ Highly Accelerated Life Testing (HALT) and Highly
Accelerated Stress Screening (HASS) are two of the
best reliability tools developed to date, and every
year engineers are turning to HALT and HASS to
help them achieve high reliability.
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9. HALT and HASS Summary, continued
♦ In HALT, a product is introduced to progressively
higher stress levels in order to quickly uncover
design weaknesses, thereby increasing the
operating margins of the product, translating to
higher reliability.
♦ In HASS, a product is “screened” at stress levels
above specification levels in order to quickly
uncover process weaknesses, thereby reducing the
infant mortalities, translating to higher quality.
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10. HALT and HASS Summary, continued
This presentation shall review the best reliability
tools to use in conjunction with HALT and HASS
and how to integrate them together.
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12. HALT - Highly Accelerated Life Test
• Quickly discover design issues.
• Evaluate & improve design margins.
• Release mature product at market introduction.
• Reduce development time & cost.
• Eliminate design problems before release.
• Evaluate cost reductions made to product.
Developmental HALT is not really a test you pass or fail,
it is a process tool for the design engineers.
There are no pre-established limits.
13. HALT, How It Works
ss
re
St
Start low and step up the
stress, testing the product
during the stressing
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14. HALT, How It Works
Fa
ilu
ss re
re
St
Gradually increase
stress level until a
failure occurs
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15. HALT, How It Works
Fa
ilu
ss re
re
St
si s
aly Analyze
An
the failure
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16. HALT, How It Works
Fa
ilu
ss re
re
St
Im
si s
pr
Make o ve aly
An
temporary
improvements
29
17. HALT, How It Works
Increase
stress and Fa
start
ilu
ss
process
re
e)
(in re
s
ea
over cr
St
si s
Im
aly
pr
o
An
ve
30
18. HALT, How It Works
Fa
ilu
ss
re
e)
(in re
s
ea
cr
St
Fundamental
Technological
Im Limit
si s
aly
pr
o
An
ve
31
19. HALT, Why It Works
Classic S-N Diagram
(stress vs. number of cycles)
Point at which failures become non-relevant
S0= Normal Stress conditions
S2
N0= Projected Normal Life
Stress S1
S0
N2 N1 N0
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24. Summary of Products by Customer
Field Environment
Environment Number of Thermal Vibration
Type Products Environment Environment
Little or no
Office 18 0 to 40°C
vibration
Office with Vibration only from
9 0 to 40°C
User user of equipment
1-2 Grms vibration,
Vehicle 8 -40 to +75°C
0-200 Hz frequency
Little or no
Field 7 -40 to +60°C
vibration
Field with Vibration only from
4 -40 to +60°C
User user of equipment
1-2 Grms vibration,
Airplane 1 -40 to +75°C
0-500 Hz frequency
TOTAL 47
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25. Summary of Results
- by attribute -
Thermal Data,oC Vibration Data, Grms
Attribute LOL LDL UOL UDL VOL VDL
Average -55 -73 93 107 61 65
Most
-100 -100 200 200 215 215
Robust
Least
15 -20 40 40 5 20
Robust
Median -55 -80 90 110 50 52
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26. Summary of Results
- by field environment -
Thermal Data,oC Vibration Data, Grms
Environment LOL LDL UOL UDL VOL VDL
Office -62 -80 92 118 46 52
Office with
-21 -50 67 76 32 36
User
Vehicle -69 -78 116 123 121 124
Field -66 -81 106 124 66 69
Field with
-49 -68 81 106 62 62
User
Airplane -60 -90 110 110 18 29
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28. Summary of Results
- by stress -
Cold Step Stress: 14%
Hot Step Stress: 17%
Rapid Thermal Transitions: 4%
Vibration Step Stress: 45%
Combined Environment: 20%
Significance:
Without Combined Environment, 20% of all
failures would have been missed 41
29. Failure Details by Stress
- Cold Step Stress -
Failure Mode Qty
Failed component 9
Circuit design issue 3
Two samples had much different
3
limits
Intermittent component 1
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31. Failure Details by Stress
- Rapid Temperature Transitions -
Failure Mode Qty
Cracked component 1
Intermittent component 1
Failed component 1
Connector separated from board 1
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32. Failure Details by Stress
- Vibration Step Stress -
Failure Mode Qty Failure Mode Qty
Broken lead 43 RTV applied incorrectly 1
Screws backed out 9 Potentiometer turned 1
Socket interplay 5 Plastic cracked at stress point 1
Connector backed out 5 Lifted pin 1
Component fell out of socket 5 Intermittent component 1
Tolerance issue 4 Failed component 1
Card backed out 4 Connectors wearing 1
Shorted component 2 Connector intermit. contact 1
Broken component 2 Connector broke from board 1
Sheared screws 1 Broken trace 1
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33. Failure Details by Stress
- Combined Environment –
(combination of vibration with rapid temp transitions)
Failure Mode Qty
Broken lead 10
Component fell off (non-soldered) 4
Failed component 3
Broken component 1
Component shorted out 1
Cracked potting material 1
Detached wire 1
Circuit design issue 1
Socket interplay 1
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34. HALT Flow Chart
Reliability - Highly Accelerated Life Testing (HALT) Flow
Use Reliability
Modeling/
Derating Data as
Input
Perform a Failure Research
Perform HALT, Taking Evaluate Failures/
Modes and Effects Environmental
Product Outside Weaknesses and
Analysis (FMEA) to Limitations on All
Environmental and Fix Those That Are
Determine "Exotic"
Performance Specs to Relevant and Cost-
Weakpoints in a Technologies Being
Find Weakpoints Effective
Design Used
Reliability
Send failure
information to
FRACAS
Publish Results
Are Margins Yes
Retest Product to
Acceptable for
No Determine New
Reliability
Limits
Reqts?
Use Results to
Use Results to Develop a
Develop a HASS Reliability
Profile Demonstration
Test
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36. HASS - What Is It?
• Detect & correct PROCESS changes.
• Reduce production time & cost.
• Increase out-of-box quality & field reliability.
• Decrease field service & warranty costs.
• Reduce infant mortality rate at product introduction.
• Finds failures that are not found with burn-in
• Accelerates ones ability to discover process and
component problems.
HASS is not a test, it’s a process. Each product has its
own process.
But...before HASS can begin, we must first HALT !!
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37. Before HASS, We Must Characterize
Product with HALT
♦ Before HASS, we must HALT
• Even for mature products in which HASS is the
goal, HALT must be done first to characterize the
product margins.
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38. Steps Towards HASS
♦ Begin process during HALT stage (involve mfg)
♦ HASS development
♦ Production HASS
39. HASS Process Is Begun Early
♦ Even before HALT is complete, we should
• determine production needs and throughput
• start designing and building fixture
• determine which stresses to apply
• obtain functional and environmental equipment
• understand manpower needs
• determine what level HASS will be performed
(assembly or system)
• determine location of HASS (in-house or at an
outside lab or contract manufacturer)
• for high volume products, determine when to switch
to an audit and what goals should be put in place to
trigger this
40. HASS Process
♦ After HALT is complete, we must
• assure Root Cause Analysis (RCA) completed on all
failures uncovered
• develop initial screen based on HALT results
• map production fixture (thermal/vibration)
• run proof-of-screen
41. HASS Process, continued
♦ Proof-of-Screen Criteria
• Assure that screen leaves sufficient life in product
• Assure that screen is effective
42. Assuring the Screen Leaves Sufficient Life
Make dwells long enough to execute diagnostic
suite. Execute diagnostics during entire profile.
UDL
UOL
S
. . . .
P
E
t
C
It is highly
recommended to
LOL combine six-axis
vibration, tickle
vibration, power cycling,
other stresses with
thermal. Powered on
monitoring is essential.
LDL Minimum
20 passes
45. The “Ideal” HASS Profile for wide
operating limits
UDL
Fast Rate Thermal
UOL Make dwells long
enough to execute
diagnostic suite.
Execute diagnostics
during entire profile.
S It is highly
P recommended to
E
t
combine six-axis
C
vibration, tickle
vibration, power
cycling, other
stresses with
thermal. Powered
on monitoring is
essential.
LOL
LDL
47. The “Ideal” HASS Profile for narrow
operating limits
UDL Make dwells long enough to execute
diagnostic suite. Execute
diagnostics during entire profile.
UOL
Fast Rate Thermal
S
P
E
t
C
Slow Rate Thermal
LOL
It is highly recommended to combine six-
axis vibration, tickle vibration, power
cycling, other stresses with thermal.
LDL Powered on monitoring is essential.
48. HASS Process Is Begun Early
♦ Production HASS
• Start screening process with 4x the number of
screen cycles intended for long-term HASS
• During production screening (after each production
run), adjust screen limits up and cycles down until
90% of the defects are discovered in the first 1-2
cycles.
• Monitor field results to determine effectiveness of
screen. Again, adjust screen limits as necessary
to decrease “escapes” to the field.
• Add other stresses, as necessary, if it is impractical
to adjust screen limits any further.
It is essential that the product being tested be fully exercised and monitored
for problem detection.
49. Typical HASS Failures
♦ Poor solder quality
♦ Socket failures
♦ Component failures
♦ Bent IC leads
♦ Incorrect components
♦ Improper component placement
♦ Test fixture/program errors
50. HASS Advantages over “Burn-In”
♦ Finds flaws typically found by customers
♦ Reduces production time and costs
♦ Lowers warranty costs
51. HASS Defects by Environment
Extreme Temperature
Combined Temperature and Transitions
6 Degree-of-Freedom Vibration 12% High Temp
46% Extreme
13%
29% Low Temp
Data from Array Technology (1993). Extreme
52. HASS – Implementation Requirements
♦ HALT for margin discovery
♦ Screen development
♦ Powered product with monitored tests
♦ Fixturing to allow required throughput
QuaMark, 1998
53. HASS Cost Benefits
♦ Greatly reduced test time
♦ Reduction in test equipment
♦ Lower warranty costs
♦ Minimized chance of product recalls
QualMark, 1998
54. HASS: How to Use the Results of FMECA
and a Reliability Predictions in Planning a
HASS
♦ How to use the results of FMECA and a Reliability
Prediction in planning a HASS
• FMECA results can identify possible wearout
mechanisms that need to be taken into account for
HASS.
• Reliability Prediction results can help determine how
much screening is necessary.
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55. HASS: How to Use the Results of
FMECA and a Reliability Predictions in
Planning a HASS, continued
♦ Using FMECA results to identify possible wearout
mechanisms that need to be taken into account for
HASS
• As we discussed in the FMECA section, certain
wearout failure modes are not easily detectable in
HALT or even in HASS Development. Therefore,
when wearout failure modes are present, we must rely
on the results of a FMECA to help determine
appropriate screen parameters.
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56. HASS: How to Use the Results of
FMECA and a Reliability Predictions in
Planning a HASS, continued
♦ Using Reliability Prediction results to determine how
much screening is necessary
• One of the parameters of a reliability prediction is the
First Year Multiplier factor. This is a factor applied to
a product based on how much manufacturing
screening is being performed (or is planned for) to
take into account infant mortality failures.
• The factor is on a scale between 1 and 4. No
screening yields a factor of 4, and 10,000 hours of
“effective” screening yields a factor of 1 (the scale is
logarithmic).
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57. HASS: How to Use the Results of
FMECA and a Reliability Predictions in
Planning a HASS, continued
♦ Using Reliability Prediction results to determine how
much screening is necessary, continued
• Effective screening allows for accelerants such as
temperature and temperature cycling.
• HASS offers the best acceleration of any known
screen. Therefore, HASS is the perfect vehicle for
helping to keep this factor low in a reliability
prediction.
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58. HASS: Using the Results of HALT to
Develop a HASS Profile
♦ Using the HALT Results, we then run a HASS
Development process
• The process must prove there is significant life left
in the product
• The process must prove that it is effective at finding
defects.
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59. HASS: Linking the Repair Depot with
HASS by Sending “NTF” hardware back
through HASS
♦ During the repair process, we may identify a large
number of “No Trouble Founds” or NTFs. HASS is the
perfect vehicle for identifying if these NTFs are truly
intermittent hardware problems or due to something
else. Using HASS to assist with the “No Trouble
Found (NTF)” issue at the Repair Depot.
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60. HASS Dilemma
Difficult to implement without impacting production
Expensive to implement across many CM’s.
Difficult to cost-justify
HASA Solves All These Issues
62. What is HASA
♦ HASA is a Highly Accelerated Stress Audit
♦ HASA is an effective audit process for
manufacturing.
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63. HASA Advantages
♦ HASA combines the best screening tools with the
best auditing tools.
♦ Better than ORT because it leverages off of HALT
and HASS to apply a screen tailored to the product
♦ Better than HASS because it is much cheaper and
easier to implement and “almost” as effective.
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64. Steps to HASA
♦ HALT
♦ HASS Development
♦ Pilot HASS
♦ HASA
100
65. What is HASA
♦ HASA is an audit or sampling procedure
♦ HASA is intended for high volume applications in
which the emphasis is not on catching every defect but
rather detecting process shifts
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66. Advantage of switching from HASS to HASA?
♦ To achieve cost efficiency for High Volume
production, reducing manpower, equipment,
utilities, and space costs.
Risks in switching from HASS to HASA?
♦ Some defective units will be shipped to the field.
♦ Corrective actions must be fast and accurate.
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67. Review of HASA
♦ When can HASA be used?
• Design and processes are control
• HASS failure rate has become acceptable
♦ What is the advantage of a HASA program?
• Cost
♦ What is the risk of a HASA
• Statistical confidence
103
68. When should HASA be considered as an
option?
Only if:
HALT is completed
HASS Development is completed
HASS is successful
104
69. Is HALT Completed?
If so:
Design defects have been eliminated
Margins are known
Margins are large
Design is robust
105
70. Is HASS Development completed?
If so:
Screen is effective
Screen is safe
106
71. Is HASS implementation complete?
If so:
Failure rates are acceptable
Manufacturing processes are under control
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72. HASA Plan
Goal is to catch shifts in processes
1. Detect degradations in process quality control
2. Compare with pre-established thresholds
3. Empower Corrective Action Team
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73. HASA Example
Example from HP Vancouver
# units shipped per day = 1000
# units tested per day = 64
90% probability of detecting a rate shift from 1%
to 3% by sampling 112 units in just under 2 days
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74. HASA Choices
Acceptable risk of allowing a “bad lot” to ship
Probability of detecting a process shift of some amount
SAMPLING PLAN
♦ Sample Size
♦ Decision Limits
♦ Commitment to Action
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75. HASA Summary
♦ For high volume production, HASA is the best
process monitoring tool
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76. HASS/HASA Flow Chart
Reliability - Highly Accelerated Stress Screening (HASS) Flow
Analyze Repair Perform HASS
Data to Determine on Material
Data from HALT if HASS Profile from Repair
Needs to Be Center Has Product
Strengthened Do Results/
Undergone a
Volumes Warrant
Change that No
Moving to
Could Affect
Sample?
Performance
Prove Profile Using
Develop a HASS Iterative Process of
Profile that Matches Increasing Stress
Product to Maximum
Performance Possible without
Reliability
Capabilities Weakening Product Yes Perform HASS and
Collect Data Send Failures
No
to Failure
No Analysis
Process
Yes
Yes
Has Product
Undergone a Change
Develop HASS Do Results Yes
Perform Sample that Could Affect
Sampling Plan and Warrant Staying
HASS and Collect Performance?
Implement with Sample
Data
HASS?
No
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77. Presentation Summary
In Summary we have learned:
• the power of developing realistic reliability goals
early, planning an implementation strategy, and
then executing the strategy, and...
the power of integration !!
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79. Further Education
• For a more In-depth view of this topic and more, Mike
will be teaching at:
• May 18th-20th: Applied Reliability Symposium,
San Diego
• Ops A La Carte is a proud sponsor of the 2005 ARS at the
Catamaran Resort on Mission Bay in San Diego, CA.
• In addition to sponsoring, we shall be giving a presentation
on “Reliability Integration Across the Product Life Cycle”
• October 20th and 21st: “Essential Reliability Tools:
A look at the best reliability tools being used”
• Go to www.opsalacarte.com/pages/news/news_events.htm for more details
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80. For more information...
♦ Contact Ops A La Carte (www.opsalacarte.com)
• Mike Silverman
• (408) 472-3889
• mikes@opsalacarte.com
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