Z. Wang, International Rectifier, Temecula, CA

Summary: The present paper studies several failure mechanisms at both UBM and Cu substrate side for flip-chip die open contact failures in multiple-chip-module plastic BGA-LGA packages. A unique failure analysis process flow, starting from non-disturbance die level C-SAM, bump x-section followed by a two-stage bump interface integrity test including under-fill etching and bump pull test has been developed. Four different types of failure mechanism in multiple chip module that are associated with open/intermittent contact, ranging from device layout design, UBM forming process defect, to assembly related bump-substrate interface de-lamination have been identified. The established FA process has been proved to be efficient and accurate with repeatable result. It has facilitated and accelarated new product qualification processes for a line of high power MCM modules.