Adhesion and failure of polymer-metal interfaces in microelectronic packaging

This chapter focuses on polymer/metal interfaces. Attention is given to two common aspects of tremendous practical interest, namely, surface roughness and moisture. Debonding of polymer/metal interfaces often involves both interfacial and cohesive failure. Since the cohesive strength of polymers is usually much greater than the polymer/metal interfacial strength, cohesive failure near the interface is usually desired to enhance the interfacial adhesion. Roughened surfaces generally produce more cohesive failure and, therefore, are used commonly in practice to obtain better adhesion. In this chapter, a fracture mechanics model is developed that can be used to quantitatively predict the amount of cohesive failure once the surface roughness data are given. Moisture, on the other hand, tends to degrade the interfacial strength. To quantify such degradation, a systematic and multidisciplinary study is conducted to better understand the fundamental science of moisture-induced degradation of interfacial adhesion. The approach is comprised of both experimental and modeling components of analysis and addresse some of the key issues needed to advance the understanding of the effect of moisture on interfacial adhesion.