Advanced TAB/BGA multi-chip stacked module for high density LSI packages

A newly advanced design for a TAB/BGA multi-chip stacked module has been developed for high density LSI packages. The configuration of this module is designed to reduce package body size and to lighten the weight. Electrical and thermal performance of this module was carefully considered and estimated by simulation or experiments. This module is called a COCB module which means the Chip On Chip Ball Grid Array module. Two chips are mounted on both top and bottom sides of a small substrate by TAB technology using a new Au-Sn (Au10-40%-Sn) eutectic micro-connection method. Two chips are electrically connected by routing wires and through holes of an interposed substrate respectively. This module is useful when packages are mounted on a board with solder paste, directly to its surface, with some discrete packages on the assembly line. The authors propose the concept of the micro bare chip module