Employing computer-aided design tools reliable die attachment

摘要

The Computer-Aided Design for Microelectronic Packages-II (CADMP-II) software program, developed by the University of Maryland, was used to analyze die attach fatigue problems in an Army missile system. CADMP-II is a set of integrated software program that can be used to design and assess the reliability of integrated circuits, hybrid, and muitichip module packages. CADMP-II consists of the various tools including: geometry design, material selection, die placement, thermal analysis andcalculation of thermal resistance, thermomechanical stress analysis, and life prediction based on potential failure mechanisms and associated failure sites.The analysis was performed for an Army microwave module that used GaAs semiconductors attached to an aluminum substrate. Die attach fatigue failure models used in the analysis included: brittle fracture, brittle fatigue, tensile fatigue, and shearfatigue. The initial analysis was performed using epoxy adhesive for the GaAs semiconductors. Various other attach materials and assembly techniques were analyzed including platings and shims. An analysis to determine the optimal attach materialproperties was conducted to determine if any currently-produced attach materials would be acceptable. The analyses showed that metal shims attached to the GaAs semiconductors were required to prevent the attach fatigue failures.