ANALYSIS OF INTERFACIAL THERMAL-STRESSES AND ADHESIVE STRENGTH OF BIANNULAR CYLINDERS

An engineering theory for predicting interfacial stresses in finite bi-annular cylinders subjected to thermally induced or external loading is developed for the evaluation of epoxy molding compounds for plastic packaging of microelectronic devices. Bi-material co-axial cylindrical specimens are being used to characterize the adhesive strength of several molding compound candidates. With this theory, it is possible to calculate both shearing and normal (radial) stresses arising at the interface between an inner (adherend) and outer (adhesive) cylinder. Predictions for a pyrex(inner)epoxy (outer) bi-annular cylinder agree well with the results from finite element analyses. It is concluded that bi-annular cylindrical specimens can be successfully applied to evaluate the adhesive strength of materials. Although our theory has been developed for a specific materials science problem, it has a broad scope of applications. Examples include insulated tubes, electrical wires, coated optical fibers, highpressure vessels, various shaft-hub joints, and even barrels of artillery guns. © 1990.