Flip-chip packaging using PES (Printing Encapsulation Systems) and PES underfill epoxy resin

Abstract

Flip-chip technology has been rapidly progressing in the laboratory. But industrial use of flip-chip has not progressed satisfactorily. Packaging materials are using low viscosity liquid type underfill epoxy resin, and packaging methods are using dispenser systems. These systems have many problems in mass production as follows. (1) This process needs to underfill epoxy resin many times. (2) This epoxy resin must use low viscosity epoxy resin to underfill under LSI, and it can't contain much filler. It is difficult to get low expansion epoxy resin system. Delamination between LSI and underfill epoxy resin sometimes occurs. We solved these problems using our PES process and PES epoxy resin. At the first step, we developed new type underfill epoxy resin. This epoxy resins has low expansion, high purity, high adhesive strength, high Tg, high humidity resistance and high electric resistance. This underfill epoxy resin didn't have mismatching between LSI and board. At the secondary step, we developed the special PES for underfill method of flip-chip. We can get no bubble process for underfill packaging of flip-chip. This process is formed of flip-chip bumping/spl rarr/PES printing/spl rarr/vacuum process/spl rarr/heat curing/spl rarr/test. This process is very simple and underfills many LSI chips at once.