New adhesion promoters for copper leadframes and epoxy resin

Abstract

New primer mols. have been synthesized to increase the adhesion strength between a copper leadframe and an epoxy molding compd. in microelectronical devices. The coupling agents were preliminarily chemisorbed at the surface of copper plates via special binding groups like thiol, disulfide, ethylene diamine and phthalocyanine. Binding to the epoxy resin was performed via an hydroxyl group. Linear hydrocarbon spacers with various chain lengths connected the copper- and epoxy-binding groups. The self-assembled layers of the org. coupling agents at the metal surface were characterized by XPS. Thermogravimetric anal. was used to study the coating with respect to its corrosion oxidn. inhibition. Shear tests clearly indicated that the coupling agents increase adhesion strength and are stable even in extreme humidity and thermal conditions in analogy to IPC-Level-1 pretreatment. Thus, delamination of the microelectronical packages was prevented.