Novel technique for the evaluation of adhesive strength of molding compounds used in plastic packaging

A novel technique, based on the application of both experimental and theoretical approaches, has been developed for the evaluation of the adhesive strength in shear for epoxy molding compounds used in plastic packaging of integrated circuit devices. This technique uses bi-material coaxial cylindrical specimens and a cylindrical version of the double lap shear joint, and has been devised based on a desire to minimize the influence of bending stresses, as well as to employ a simple and inexpensive process for preparation of test specimens. The technique was applied to four commercially available epoxy compounds molded to three metal surfaces. Adhesion of all the compounds to etched copper is much better than adhesion to nickel plated nickel or gold plated nickel. Ranking the four epoxies for adhesion to etched copper, Sumitomo-115>Nitto>Shin-Etsu>Sumitomo-89, with all being within 20%. Adhesive strength is shown to decrease with an increase in temperature for all the epoxies