Development of Stacked Packaging Using Compression Type Flip Chip Technology

Abstract

A stacked device called SEP (System Embedded Package) was developed to drastically increase LSI density relative to its area on the circuit board. This was achieved by fabricating an LSI package in a stacked structure. This device has been applied to mobile communication equipment. The bottom-side chip was made into a flip-chip structure and attached to the substrate by the NSD method, which involves the use of stud-bumps and adhesive encapsulation film. On the top of this flip-chip LSI, another LSI was stacked and interconnected by using low-profile wire-bonding technology. The use of flip-chip bonding for the bottom-side LSI permitted easy wire bonding on the topside LSI. Furthermore, this packaging technology was able to provide a super multi-pin system LSI with more than 600 pins. By adopting this package in a mobile communication product, the required package area on the circuit board could be reduced by 35%.