Stud-bump bonding technique onto an advanced organic substrate for MCM-Ls

This paper describes the result of our study that bare LSI chips are mounted directly onto the "ALIVH/sup TM/" (any layer inner via hole) substrate by using Stud-Bump-Bonding (SBB/sup TM/) technique, which has been developed by us. The SBB/sup TM/ technique is an advanced flip-chip bonding technique, for high density Multi-Chip-Modules (MCMs), which can mount bare LSI chips directly onto substrates. The structure of the bonding portion is composed of Au bumps having two-stepped construction and conductive adhesives. The conductive adhesive is very flexible in bond, thus relaxing thermal and mechanical stresses. The ALIVH/sup TM/ substrate has been developed in our laboratory. It is a high density and high performance multi-layered printed wiring board with any layer inner via hole structure, via hole processing technology using a CO/sub 2/ laser and interconnection technology that employs conductive paste. We had good results for several reliability tests in the test vehicles of MCM-ALIVH/sup TM/. Especially, in the thermal shock test, the increase of connecting resistance in MCM-ALIVH/sup TM/ was smaller than that of MCM-Ls which used ordinary organic substrates in stead of the ALIVH/sup TM/ substrate. The combination of SBB/sup TM/ technique and the ALIVH/sup TM/ substrate is promising for miniaturized, light-weighted, high speed (high frequency), and high quality in MCMs.