This presentation will cover test and management strategies that can be used to protect your company and products against obsolescence risk. Topics include relevant industry standards, use of Managed Supply Programs (MSP) and Contract Pooled Options, long term storage recommendations and practices, and descriptions of the appropriate tests to use in various situations. Component obsolescence management is a strategic practice that also mitigates the risk of counterfeit parts. Left unchecked, obsolescence issues increase support, development and production costs. So, planning ahead is critical. For companies that proactively manage component availability and obsolescence, the impact of long-term storage on manufacturability and reliability is an area of major concern. Effective test strategies are crucial in detecting and preventing problems.

1. Reliability Strategies for
Combating Obsolescence
Risks
Presented by:
Cheryl Tulkoff
DfR Solutions
ctulkoff@dfrsolutions.com

2. Abstract
Component obsolescence management is a strategic practice that also mitigates the risk of counterfeit parts.
Left unchecked, obsolescence issues increase support, development and production costs. So, planning
ahead is critical. For companies that proactively manage component availability and obsolescence, the
impact of long-term storage on manufacturability and reliability is an area of major concern. Effective test
strategies are crucial in detecting and preventing problems.
When component obsolescence isn’t planned for, the secondary market is often the supply chain of last
recourse. While it is possible to get high quality, genuine parts, it is also possible to get nonconforming,
reworked, or counterfeit components. And, it is increasingly difficult to differentiate genuine parts from their
counterfeit equivalents. This is an area where appropriate testing can help. Historically, the secondary market
provided a mechanism for finding parts in short supply or at reduced cost. Today, high-reliability system
manufacturers are less willing to risk contamination of their supply chain with potentially substandard parts
in order to save a few dollars on the cost of a part.
This presentation will cover test and management strategies that can be used to protect your company and
products against obsolescence risk. Topics include relevant industry standards, use of Managed Supply
Programs (MSP) and Contract Pooled Options, long term storage recommendations and practices, and
descriptions of the appropriate tests to use in various situations.
Testing and analysis always starts with non-destructive evaluation (NDE). This practice is designed to obtain
maximum information with minimal risk of damaging or destroying physical evidence with an
emphasize the use of simplest tools first. Testing strategies including visual inspection, mechanical
robustness, solderability assessment, X-Ray, XRF, C-SAM, electrical characterization, decapsulation, and
marking evaluations will be compared and contrasted. More intensive thermal cycling and degradation
testing will also be covered.

3. Obsolescence Management
• Strategic practice that also mitigates the risk
of counterfeit parts
• Anticipate & plan for:
– Supplier disruption
– End of life parts
– Aging technologies
– Long life programs

4. The Reliability Issues….
• Effect of long-term storage on
manufacturability and reliability is an area
of major concern
• Many issues can arise depending on the
technology and storage environment
– Components fail in storage
• Planning is key!

5. The Reliability Issues….
• Mechanisms of concern include:
– Solderability
– Moisture
– Tin whiskering
• Of these, solderability / wettability remains
the #1 challenge in long-term storage of
electronic components

6. So, What do You Need to Know?
• Industry Standards for Storage Reliability
• Use of Managed Supply Programs (MSP) and
Contract Pooled Options
• Long Term Storage Recommendations and
Practices
• Awareness of Long Term Storage Reliability
Issues
• Testing Recommendations

7. Industry Standards: JEDEC JEP160
• “Long-Term Storage for Electronic Solid-
State Wafers, Dice, and Devices”
– Age does not adversely affect most solid-state
electrical performance provided no
degradation in materials occurs
– Provides the industry with the best practices
and recommendations for packing and storing
solid-state electronics for long-term storage
– Addresses continuous storage where J-STD-033
does not apply

8. Industry Standards: ANSI-GEIA-STD-0003
• “PROCEDURES FOR LONG TERM STORAGE OF
ELECTRONICS”
• Provides an industry standard for Long Term
Storage (LTS) of electronic devices by drawing
from best long term storage practices
• LTS is > 12 months
– Typically much longer
• Addresses storage of unpackaged
semiconductors and packaged electronic
devices

9. MIL-HDBK-338B Viewpoint
• “ELECTRONIC RELIABILITY DESIGN HANDBOOK”
• Assumed failure rate is insignificantly small or
even 0 during the times when the equipment is
switched off
• Experiments indicate that failure rates of many
components are very significant even when no
electrical stresses are applied
– Other stressors are still present

10. MIL-HDBK-338B Viewpoint
• For some components, the storage failure
rate is even greater than the operating
failure rate at lower stress levels
– Some types of resistors (eg. carbon
composition) where, under storage conditions,
there is no internal heat generation to
eliminate humidity effects
– Certain types of electrolytic capacitors need a
reforming process after a long period of
storage

11. Critical Elements of a Long Term
Storage Program
• Asset Security
– Protect against loss, theft
• Component Inspection
– Authenticity & quality
• Product genealogy (origins) & condition
– Data records for manufacture, transportation,
and short term storage
• Environmental data, Lot codes, Date codes

12. Critical Elements of a Long Term
Storage Program
• Storage Environment
– GEIA Standards
• Active desiccant storage at less than 5% relative
humidity
• Dry nitrogen storage per MIL-PRF-27401
• Data Management
• Maintain and manage individual date and lot codes.
• Assured Supply

13. Product Genealogy – Example of
Supply Chain Complexity
Courtesy of Lloyd Condra, Boeing

14. Managed Supply Programs (MSPs)
• Companies offer MSPs as an industry service.
Some offerings include:
– Purchasing and holding of obsolete components
– Long term storage services
– Component contract financing
– Stock pooling and optional stock holdings
– Product quality inspection and management
– Contract terms up to 20 years

15. Contract / Stock Pooling Options
• Pay a percentage of part cost over some defined time
interval from mfg or MSP provider
• Less Purchase Investment
– Purchasing parts means an upfront cost for the value of the parts.
– The percentage will ensure that the part or parts that you need
are stocked and available when needed
• Less Inventory Cost
– Insurance
– Risk of losing or damaging stocked parts
– Storage space
• Warranty
– The warranty starts when a part is purchased from the pool
– With purchased parts, the 1st year warranty granted already starts
on the date of purchase

16. Proper IC Storage
• Die / Wafer
• Hermetic Packages
• Plastic Packages

17. Proper IC Storage
• For long-term programs, some form of storage
should be considered. But, it does present problems:
– Practical/physical space, mechanical, financial,
and counterfeit products
• What do we mean by long-term storage?
– Commercial: 2 years is very long-term
– Military: 20 years and beyond is common

18. Die/Wafer Storage :“Die Banking”
• Successful storage methodologies include special
bagging, environmental controls and periodic
monitoring.
– Requires care, cleanliness (particulates and
gases), and benign temperatures
– Controlled atmosphere “dry boxes” (dry nitrogen
purged storage)
– Dry bagged/vacuum storage
• Oxygen barrier bags designed specifically for long-
term storage

19. Die/Wafer Storage Advantages
• Compact
container, holds 9
wafers with gross
die count of
64,000
• Flexible form
factor, can build
parts in any
desired package
Courtesy John O’Boyle – QP Semiconductor

20. Hermetic Packages
• Minimize moisture intrusion
• 20 year storage is routine
– Metal TO-3 “can”
– Ceramic and side-brazed packages
• DIP, LCC, flat pack, and PGA
• Keep them dry and in environments
low in sulfur, chlorine, and
hydrocarbons to preserve solder
finish on lead frame

21. Hermetic Disadvantages/Advantages
• Cannot change package type
• Slightly more expensive to store than
die bank
• Large storage space required
• Easy storage infrastructure
• Long life time storage

22. Common Misconceptions about Plastic
• Come from the manufacturer in sealed
packaging and thus don’t need special
handling/storage
• Not rated as moisture sensitive
therefore okay
• Safe to store in a “normal room”
environment

23. Plastic Packages
• Plastic is hygroscopic
– Attracts water molecules
from the environment.
– Achieve equilibrium in 4 to
28 days depending on
molding compound.
– Normal room considered
“wet” for plastic ICs (LAX
annual average RH: +70%*)
– Store in “dry bags” or in a
<10% RH environment
Source: Plastic Package Moisture-Induced Cracking, April 2006,
National Semiconductor Application Note
* LAX weather station - indoor data over 31 years.

24. But, Water doesn’t hurt Plastic!
• It’s not the plastic we’re worried about!
– Water leaches and reacts
– Water corrodes and degrades the metal pads and wires
and results in device failure
• Isn’t plastic “rated” as non-moisture sensitive?
– Yes. But this rating is for IC/board assembly for reflow
solder heat induced delamination and popcorning
• Contrary to popular belief, it is not a rating for long-
term storage!

25. Storage Options: Summary

26. Long Term Storage Case Study
• In this case study, solderability was assessed for:
– Components from three different reels
– Stored for up to five years to determine how much
additional storage life was available
– Either an ASIC in a SOIC package or a MOSFET in a
TO-252 package
– In both package styles, the lead frame plating was
tin-based

27. Case Study (continued)
• Type of plating material drives the appropriate
solderability test
– In this case, tin can either oxidize and/or form intermetallics with the base
metal underneath
– Both reactions can detrimentally reduce the solderability of the component
• To assess these reactions, the components were subjected to
steam aging to accelerate storage related effects on solderability
– Elevated temperature accelerates tin-copper intermetallic growth
– Steam accelerates tin oxide formation
– Components were then tested for solder wettability using a wetting
balance test

28. Solderability Measurements
• Measurements of wettability of the
leads performed using a solder
meniscus measuring device
(Wetting Balance) for each
component
• Parts were tested with a standard
RMA flux
– Procedure detailed in IPC/EIA J-STD-
002C
• 3 components from each reel were
tested

29. Case Study Results
• TO252 (production year 2003). Solderability is already
impaired.
– Dashed line indicates a part which was tested with a more active
water soluble flux. Notice the significant improvement in
wettability
– Suggests the mechanism for poor wetting is thick oxide (as
opposed to intermetallic formation)
Wetting Force
DCC03994DC
-100
-50
0
50
100
150
200
250
300
350
400
-0.5 0.5 1.5 2.5 3.5 4.5 5.5
time (seconds)
Force(uN/mm)
0
0
0
12
12
12
24
24
24
48
48
48
72
72
72
Hours
Aged

30. Case Study Results
• TO252 (production year 2000). Even though this part is
older, initial solderability is superior to the 2003 part
• After 12 hours of steam aging (equivalent to six
months), solderability has deterioratedWetting Force
DK0060112G
-100
-50
0
50
100
150
200
250
300
350
400
-0.5 0.5 1.5 2.5 3.5 4.5 5.5
time (seconds)
Force(uN/mm)
0
0
0
12
12
12
24
24
24
48
48
48
72
72
72
Hours
Aged

31. Case Study Results
• SOIC (production year N/A). Solderability degrades slowly
• The part does not become completely unwettable, like the
TO252 parts, but fails IPC criteria after 24 hours of steam
aging (equivalent to 1 year of storage)Wetting Force
SOIC
-100
-50
0
50
100
150
200
250
300
350
400
-0.5 0.5 1.5 2.5 3.5 4.5 5.5
time (seconds)
Force(uN/mm)
0
0
0
12
12
12
24
24
24
48
48
48
72
72
72
Hours
Aged

32. Discussion and Conclusions
• The same components produced by the same
manufacturer can display very different behaviors
in regards to long-term solderability
– This was seen with the TO252 parts, where the parts
fabricated in 2000 had better wettability than the parts
fabricated in 2003
– Therefore, any component or obsolescence storage
strategy should involve an initial solderability
assessment of each part and date code combination

33. Some Long Term Storage
Reliability Issues
• Intermetallics
• Tin whiskering
• Moisture

34. Intermetallics & Oxidation
• Intermetallic compounds form when two
unlike metals diffuse into one another
creating species materials which are
combinations of the two materials
• There are a number of locations where
these dissimilar metals are joined including:
– Die level interconnects, wire bonds
– Plating finishes on lead frames
– Solder joints, flip chip interconnects, etc...

35. Tin Whiskers
• Single crystal growth that can
occur on tin plated lead
frames
• Mechanism for the growth is
not clearly understood
– Appears to be related to
compressive stresses in the
plating, moisture, and
contamination
• Can lead to shorting,
intermittent errors, and high
frequency issues

36. Moisture
• Depending on storage time & conditions,
parts may be subjected to moisture.
• May be from
– Overloading of the desiccant with moisture
– Failure of the storage bags
– Improper storage
• Presence of moisture can lead to corrosion
issues and other failures such as popcorning

37. Summary
• Managing obsolescence issues is critical!
• Anticipate and plan
• Implement a robust obsolescence & anti-counterfeiting
program which considers:
– Asset Security
– Component Inspection
– Product genealogy (origins) & condition
– Storage Environment
– Data Management
– Assured Supply
• Be aware of the potential reliability issues!
• Use available testing protocols

38. Presenter Biography
• Cheryl has over 22 years of experience in electronics manufacturing focusing on failure analysis
and reliability. She is passionate about applying her unique background to enable her clients to
maximize and accelerate product design and development while saving time, managing
resources, and improving customer satisfaction.
• Throughout her career, Cheryl has had extensive training experience and is a published author
and a senior member of both ASQ and IEEE. She views teaching as a two-way process that
enables her to impart her knowledge on to others as well as reinforce her own understanding
and ability to explain complex concepts through student interaction. A passionate advocate of
continued learning, Cheryl has taught electronics workshops that introduced her to numerous
fascinating companies, people, and cultures.
• Cheryl has served as chairman of the IEEE Central Texas Women in Engineering and IEEE
Accelerated Stress Testing and Reliability sections and is an ASQ Certified Reliability Engineer,
an SMTA Speaker of Distinction and serves on ASQ, IPC and iNEMI committees.
• Cheryl earned her Bachelor of Mechanical Engineering degree from Georgia Tech and is
currently a student in the UT Austin Masters of Science in Technology Commercialization
(MSTC) program. She was drawn to the MSTC program as an avenue that will allow her to
acquire relevant and current business skills which, combined with her technical background,
will serve as a springboard enabling her clients to succeed in introducing reliable, blockbuster
products tailored to the best market segment.
• In her free time, Cheryl loves to run! She’s had the good fortune to run everything from 5k’s to
100 milers including the Boston Marathon, the Tahoe Triple (three marathons in 3 days) and
the nonstop Rocky Raccoon 100 miler. She also enjoys travel and has visited 46 US states and
over 20 countries around the world. Cheryl combines these two passions in what she calls
“running tourism” which lets her quickly get her bearings and see the sights in new places.

39. Thank you!
Cheryl Tulkoff
DfR Solutions
ctulkoff@dfrsolutions.com