Moisture effect on adhesive bonding strength characterized by crack opening method

Adhesive wafer bonding has been explored as a candidate technology for micro-electro-mechanical-system (MEMS) and 3D packaging because of its low bonding temperature, low-cost and flexible applicability. Although the bonding strength is critical to the system success, very few results have been reported on quantitative analysis of adhesive bonding strength. In this paper, by using the crack opening method, we present semi-quantitative measurement of bonding strength for two adhesives, i.e., SPR220 and BCB4024, and the bonding strength degradation under various ambient conditions. Two adhesives are compared in terms of bonding strength, and the correlation between the bonding strength variation and the microstructural evolution is also established. The time delay phenomenon in crack length stabilization is also discussed.