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Fatigue Crack Growth Analysis of Interface between Lead Frame and Molding Compound

: Bektas, E.; Broermann, K.; Brumm, S.P.; Pecanac, G.; Rzepka, S.; Silber, C.; Wunderle, B.


TU Dresden, Institut für Aufbau- und Verbindungstechnik der Elektronik -IAVT-; Institute of Electrical and Electronics Engineers -IEEE-; International Microelectronics and Packaging Society -IMAPS-:
7th Electronic System-Integration Technology Conference, ESTC 2018. Proceedings : 18th to 21st Sept. 2018, Dresden, Germany
Piscataway, NJ: IEEE, 2018
ISBN: 978-1-5386-6814-6
ISBN: 978-1-5386-6813-9
ISBN: 978-1-5386-6815-3
Electronic System-Integration Technology Conference (ESTC) <7, 2018, Dresden>
Fraunhofer ENAS ()

Cyclic thermo-mechanical loading together with mismatch of elastic properties between the components can lead to fatigue crack growth at interfaces and finally to interfacial delamination, potentially resulting in malfunction of an integrated circuit (IC) at the end. This work aims for a methodology to characterize one of such interfaces. The overall intention is to integrate methods into virtually conducted DoEs (design-of-experiments) for the determination of most robust design of packages with respect to fatigue crack growth at lead frame molding compound interface. In this manner, a miniaturized sub-critical bending test (MSCB), first demonstrated by [1], was optimized and used to characterize the interface between lead frame (LF) and molding compound (MC). Interfacial fatigue crack growth was quantitatively determined on samples taken from production line. Experimental crack length is determined by compliance method and by help of finite element method. Finally, sub-critical strain energy release rate is determined by using numerical methods and then Paris-Erdogan curves at different temperatures are formed for the related interface. Later these sub-critical strain energy release rate values are used to forecast crack growth in IC Packages under temperature cycle tests in which initial crack is created by a separator.