Thermal-mechanical enhanced high-performance silicone gels and elastomeric encapsulants in microelectronic packaging

Abstract

A modern electronic device is a complex 3-D structure that consists of millions of components for each single integrated circuit (IC) chip. This complex and delicate device requires effective encapsulation and packaging to ensure its long-term reliability. This device encapsulant requires not only excellent electrical and physical properties, but also suitable mechanical properties for hostile and extreme temperature cycling requirements (from -65/spl deg/ to 150/spl deg/C). Hence, the mechanical and thermal behavior of the encapsulant plays a critical role in device reliability. Low stress encapsulants are the preferred choice for microelectronic packaging. Silicone-based materials, either the elastomers or gels, with their low modulus and excellent electrical properties, are the best encapsulants. However, the intrinsic low modulus silicone provides weak mechanic protection for the IC device. We have, however, modified the silicone material with a high loading of silica to improve its mechanical and physical properties. This high-silica filler loading material improves not only its mechanical property, but also its modulus. Furthermore, this modified high modulus silicone material tends to have microcracks during the high temperature thermal cycling testing that generates the device reliability problem. In this paper, we will describe a modified version of the thermal-mechanical enhanced silicone-based encapsulant, its material formulation, curing process, thermal mechanical failure and its protecting mechanisms, and its application. >