Large Die Flip Chip Packaging on Organic Substrates: The Role of Finite Element Analysis (FEA), Materials Characterization, Failure Analysis (FA) and Test Vehicles in Development Spins

摘要

This work describes a case study where a process was developed focusing on four key factors that can be used to define a methodology for packaging large die on high performance organic substrates: failure analysis (FA), finite element analysis (FEA), test vehicle development and materials testing. The process consisted of in depth FA in the prototype phase to identify failure modes within typical thermomechanical stress tests such as air - to -air thermal cycling. Armed with a known failure mode, we describe the efforts to characterize a variety of assembly materials and utilize 3-D FEA of stress and warpage to determine optimal package construction. The use of low cost, quick turn test vehicles allowed us to verify the predicted optimal package and materials combinations through simple opens / shorts electrical tests during JEDEC reliability testing. Processability evaluations and optical coplanarity measurements allowed us to quickly select materials based on minimized warpage and optimum underfill characteristics. The result of this effort is a systematic approach to identify reliable large die flip chip packaging options for organic substrates in a cost effective, timely manner.