PROTOCOL DEVELOPMENT FOR TESTING SOLDER RELIABILITY IN COMBINED ENVIRONMENTS

摘要

This paper describes a proposed method for investigating solder joint reliability in a combined environment of vibration and thermal cycle testing. Since combined environmental testing is an evolving concept, no default approach or standard test protocol currently exists. The need to develop such a protocol arises from the fact that materials may behave differently under combined stress conditions; exhibit different failure modes and impact the overall reliability. Combined environmental testing would therefore provide the closest approximation to actual field conditions and the best means of evaluating the performance capability of solder joints. In developing this protocol, consideration was given to obtain relevant information from both a reliability perspective (number of cycles to failure) as well as micro-structural stand point (at time of failure). Further, in combining the two conditions, time to failure had to be weighed against the overall expected time of the test; when performed alone, vibration testing is often completed within a single day, while thermal cycle testing can take up to six months to complete. Phase one of this project will include developing and refining the test protocol. Phase two will then use this protocol to evaluate, characterize and compare various low melt, Bi-containing alloys against currently used SAC305 and Sn-Pb solders.