Mechanical Behavior of Encapsulants in Microelectronic Packaging

Abstract

AbstractA modern electronic device is a complex 3-dimensional structure that consists of millions of components for each single IC chip. This complex and delicate device requires effective encapsulation and packaging to ensure its long-term reliability. The device encapsulant requires not only excellent electrical, physical properties, but also suitable mechanical properties for the hostile and extreme temperature cycling requirements. Hence, the mechanical behavior of the encapsulant plays a critical role in the device reliability.Low stress encapsulants are the preferred choice for microelectronic packaging. Silicone-base materials, with their low modulus and excellent electrical properties, are one of the best encapsulants. However, the intrinsic elastic (to soft gel-like) silicone properties provide weak mechanic protection of 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 its mechanical property, but it also increases its modulus. This modified high modulus silicone material tends to have microcracks during the high temperature cycling testing. In this paper, I will describe a modified version of the enhanced mechanical property silicone-base encapsulant, the materials formulation, the curing and the thermal mechanical protecting mechanism and its application to AT&T's No. 5 Electronic Switching System (ESS) Gated Diode Crosspoint (GDX) hybrid IC supplemental insulating layer (SIL) materials.