Application of thermal analysis

Abstract

The evaluation of molding compounds is generally based on the performance of encapsulated semiconductor devices under specific sets of environmental conditions. Testing under these conditions may require several months. To reduce the evaluation time to a few days, tools and techniques which enable some prediction of encapsulation material’s behavior on the basis of certain characteristics, have been developed by thermal analysts techniques. The instrumentation consists of a DuPont 990 Analyzer equipped with a Differential Scanning Calorimeter (DSC) and a Thermo-gravimetric Analyzer coupled to a Gas Chromatograph. Other commercial equipment is available for this testing. Thermo-gravimetric analysis was used to evaluate the thermal stability of four (4) types of epoxy molding compounds. The types and relative amounts of organic constituents are determined by gas chromatography analysis of the degradation products. Differential scanning calorimeter thermograms are used to characterize the behavior of molding compounds during polymerization. The first exotherm, which is characteristic of cross polymerization, is used for determining shelf life, pelietizing, preheating, and molding process conditions. The second major exotherm reaction, which is characteristic of the degradation mechanism, is used to evaluate the effect of post curing conditions and, in addition, is used to identify the type of resin used in the formation of the moldings compounds.