Thermal characterization of an epoxy-based underfill encapsulant for flip-chip packaging

摘要

Epoxy-based underfill encapsulant materials are used in advanced microelectronic packaging to reduce thermal stresses on solder joints and IC interconnections. Therefore, their thermal properties directly affect package performance and reliability. In this study, the thermal properties of an epoxy-based underfill material developed for Intel's flip-chip packaging were characterized using DSC, TGA, TMA, and DMTA techniques. Experimental results showed that this epoxy can be cured rapidly. Near room temperature, the cured epoxy has a low coefficient of thermal expansion (CTE) and a moderate storage modulus, resulting in a low stress index. The glass transition temperature and thermomechanical properties as a function of epoxy curing conditions will be discussed. These measurements were successfully used to screen incoming materials as well as to help establish a better manufacturing process.