シリカ粒子高充てんエポキシ樹脂の強度特性

Abstract

In plastic packaged integrated circuit (IC) devices, silicon chips are molded with epoxide resins containing about 60% by volume of silica particles. Recently, the size of chips mounted in a package has increased rapidly with advances in large-scale integration technology. This trend creates a problem of increased mechanical stress in the package, which sometimes causes cracking in the encapsulation resin under temperature cycling and other conditions. Hence thorough understanding of the fracture properties of these materials has become an important issue in package design.In this study, static fracture, fatigue and creep properties of silica particulate filled epoxide resins for IC encapsulation were studied at various temperatures between -55°C and 150°C by using smooth plate specimens. The fatigue tests were carried out with different mean stresses and frequencies. Comparison was made between the properties, and their failure mechanism was discussed.The gradients of both S-N and creep rupture curves were very small. The test results suggest that the fracture of these materials is mainly controlled by stress rather than strain. Scanning electron microscopy of the fracture surfaces indicates that a crack propagates by debonding of filler particle/matrix interfaces at high temperatures around the glass transition temperature, whereas it propagates through filler particles at lower temperatures. Most features of the test results can be attributed to the brittle fracture of the particles.