An improvement of conductive adhesives on high temperature endurance by using Ag-Sn alloy powder

Ag-epoxy isotropic conductive adhesives are expected to be one of the alternatives to solder. One of the fatal drawbacks is, however, the poor compatibility between Ag fillers and Sn plating on components at elevated temperature. In the present work, the Ag-Sn alloy fillers were examined for replacing Ag filler to prevent this degradation. Two types of joints of Cu/adhesive/Cu with or without Sn plating on Cu were exposed at 150/spl deg/C. The initial strength of both joints was about 40 MPa and those increased about 65 MPa after 100 h exposure. Beyond 100 h exposure, the strength of the Sn plated joint decreased gradually as increasing exposure time. However, even after 1000 h exposure, the joint maintained high strength of 45 MPa. Thus, the Ag-Sn alloy fillers can be good replacement fillers compared with Ag fillers. On the other hand, the joint without any plating decreased strength to 25 MPa after 1000 h exposure. The interface reaction has a key role for such degradation mechanisms.