(TI)对半导体器件的长期存储评估.pdf - 第12页
1 1.4 QFP (Quad Flat Pack) Sample batch #S8: 18 years storage, MSL3, TQFP 100 pin, lead finish : post assembly plated Sn Figure 1 1-22. Package T op View Figure 1 1-23. Solder Past Print Corner Figure 1 1-24. Bottom View…
Figure 11-14. Lead Side View After
Bake
Figure 11-15. Lead Side View After
Soldering
11.3 SOIC (Small Outline Integrated Circuit)
Sample batch #46: 21 years storage, MSL1, SOIC D, lead finish: pre-plated NiPdAu
Figure 11-16. Unit After Bake 4Hr/
150°C
Figure 11-17. Solder Paste Print
Pattern
Figure 11-18. Bottom View After
Test
Figure 11-19. Lead Side View After
Bake
Figure 11-20. Lead Side View After
Soldering
Figure 11-21. Lead Side View
Soldered PCB
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11.4 QFP (Quad Flat Pack)
Sample batch #S8: 18 years storage, MSL3, TQFP 100 pin, lead finish: post assembly plated Sn
Figure 11-22. Package Top View
Figure 11-23. Solder Past Print
Corner
Figure 11-24. Bottom View After
Test
Figure 11-25. Lead Side View
Original
Figure 11-26. Lead Side View After
Soldering
Figure 11-27. Lead Soldered on
PCB
11.5 BGA (Ball Grid Array)/WCSP (Wafer Level Chip Scale Package)
Sample Batch #38: 12 years storage, MSL1, wafer chip scale package (WCSP) 24 SnAgCu solder balls
Figure 11-28. Unit After Bake 4 hr/
150°C
Figure 11-29. Bottom View After
Test
Figure 11-30. Solder Paste Print
Pattern
Figure 11-31. Side View After Bake
Figure 11-32. Side View After
Soldering
Figure 11-33. Side View Soldered
on PCB
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12 Summary of Results
• Reliability of the semiconductor devices stored in an environmentally controlled warehouse for an extended
period of time up to 21 years was assessed. No failure mechanisms were identified.
• ESD performance of tape and reel samples was comparable to new tape and pocket samples.
• The HIC were confirmed to be functional after LTS.
• The desiccant used for moisture sensitive product is active for >15 years.
• No degradation in ESD performance or moisture ingress was observed on the MBB when stored in a
controlled environment.
• Solderability of the package pins met all expectations and is comparable with the solderability performance of
current devices.
13 Conclusion
Advancements in lead-frame technology, packing materials, work methods, and inventory logistics have made it
possible to further extend the time between manufacturing semiconductor products and delivering to customers.
This extended storage time does not impact product performance or the customers product shelf life. In multiple
studies performed since 1998, no evidence of diminishing reliability has been found that would adversely affect
the product or the ability for it to be soldered to a PCB. No failure mechanisms have been identified that would
compromise the circuit reliability of LTS devices. Based on these studies, TI will eliminate limitations on the
storage durations. TI will continue to collect data on more samples and as the data directs, TI will continue to
adjust the storage conditions and duration for various products.
14 Acknowledgments
The author wishes to recognize the following individuals and groups for their professional assistance:
• Andreas Pfeiffer and Markus Filbry, TI Germany, solderability testing and documentation of the 2020 long
term storage study results.
• TI technical staff members who collaborated and contributed to the evaluation efforts.
• The TI Reliability Laboratory in Freising, Germany and Dallas, Texas.
• Dallas Device Analysis Operation (DDAO) and Freising Device Analysis Operation (FDAO).
• Todd Wyant, TI Dallas, packaging support.
• Ron Eller, TI Dallas, technical assistance.
• Ron Madsen, TI Tucson, retired.
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