An MCM-D memory module in an overmolded plastic package

Abstract

In this paper, a PQFP package design which holds a thin film MCM with four memory dice is described. The substrate design is briefly mentioned. We describe the strategy to integrate the MCM-D Al substrate into an existing standard package (i.e. 160 lead PQFP) with minimum cost to meet manufacturability and reliability requirements. This was achieved through minimal modifications to existing assembly processes, fixtures, and materials. Also discussed is material selection to meet the reliability stress tests goals with respect to thin film MCM corrosion and stress relief on high aspect ratio die sizes. Choice of molding compound, die attach and stress relief coatings and their impact on reliability are discussed. The proper selection of materials can eliminate a few assembly steps. The reliability qualification requirements and the qualification test results are also presented.