Manufacturing And Reliability Challenges With QFN - SMTA

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Manufacturability (cont.)• QFN solder joints are more susceptible to dimensional changes• Case Study: Military supplier experienced solder separation under QFN• QFN supplier admitted that the package was more susceptible tomoisture absorption that initially expectedResulted in transient swelling during reflow solderingInduced vertical lift, causing solder separation• Was not popcorningNo evidence of cracking or delamination in component package© 2004 - 200937
Manufacturability (Board Flexure)• Area array devices are known to have boardflexure limitations For SAC attachment, maximum microstrain canbe as low as 500 ue• QFN has an even lower level of compliance Limited quantifiable knowledge in this area Must be conservative during board build IPC is working on a specification similar to BGAs© 2004 - 200938
Page 4 and 5: Who Uses DfR?Military / Avionics /
Page 6 and 7: Knowledge and Education(Website)•
Page 8 and 9: Introduction (cont.)• Why is know
Page 10 and 11: Component Packaging• Most of us h
Page 12 and 13: 2 nd Level Interconnect Reliability
Page 14 and 15: Solder Wearout (cont.)• Eliminati
Page 17 and 18: Industry Response to SJ Wearout?•
Page 19 and 20: Quad Flat Pack No-Lead (QFN)© 2004
Page 21 and 22: QFN (cont.)• Availability 1 x 2 m
Page 24 and 25: Advantages: Thermal Performance•
Page 26 and 27: QFN: Why Not?• QFN is a ‘next g
Page 28 and 29: Bond Pads (cont.)• Extend bond pa
Page 30 and 31: Singulated operationTitle: Reliabil
Page 32 and 33: Title: Reliability study of surface
Page 34 and 35: Manufacturability (Rework)• Can b
Page 38 and 39: Reliability (Thermal Cycling)• Or
Page 40 and 41: Reliability (Bend Cycling)• Low d
Page 42 and 43: Dendritic Growth (cont.)• The ele
Page 44: QFN: Risk Mitigation• Assess manu

Manufacturing And Reliability Challenges With QFN - SMTA

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