SUBJECT: Ph.D. Dissertation Defense
   
BY: David Samet
   
TIME: Wednesday, July 18, 2018, 1:00 p.m.
   
PLACE: MARC Building, 201
   
TITLE: Development of a Fatigue-Compatible Cohesive Zone Method for a Copper-Epoxy Molding Compound Bimaterial Interface
   
COMMITTEE: Dr. Suresh Sitaraman, Chair (ME)
Dr. Samuel Graham (ME)
Dr. Olivier Pierron (ME)
Dr. C. P. Wong (MSE)
Dr. Jianmin Qu (Tufts University)
 

SUMMARY

Interfacial delamination is a prevalent failure mechanism in microelectronic packages. While much work has been performed towards understanding fracture of bimaterial interfaces under monotonic loading, investigation focused on the impact of fatigue loading on such structures is still evolving. Microelectronic packaging interfaces experience cyclic loads, and thus may eventually debond during operation. In addition to such fatigue characterization of packaging interfaces, the development of a computationally affordable modeling methodology with predictive capability towards fatigue crack propagation and failure is needed. This work focuses on copper/epoxy mold compound (EMC) interfacial delamination under fatigue loading through experiments as well as computational modeling. The performed characterization relies primarily on double cantilever beam tests but also other test configurations such as four-point bend. Finite-element models for both traditional fracture mechanics and cohesive-zone modeling (CZM) have been used for interfacial fracture parameter extraction and analysis. Using fatigue interfacial fracture experiments, an innovative fatigue-compatible CZM modeling framework has been developed. The developed fatigue CZM model has been validated against other experimental data. Also, interfacial fracture failure locus is examined under the context of multiple interfacial fracture tests. Additionally, the dependency of fatigue crack propagation trends on mode-mixity is examined.