Accelerative reliability tests for Sn3.0Ag0.5Cu solder joints under thermal cycling coupling with current stressing

摘要

The lead-tin solder has already been replaced by the lead-free solder gradually in most industrial applications according to the RoHS restriction. However, the reliability test duration and the failure mechanism of lead-free solders are always a concerned problem that must be addressed when designing a new electronic product. In this paper, a thermo-electric accelerated test (TEC) method, as well as its corresponding failure mechanism, was discussed to consider the feasibility of reducing the reliability test duration. Compared with the traditional thermal cycling (TC) test, the lifetime of the component boards decreased apparently in the thermo-electric accelerated test, including both the time-to-failure and the cycles-to-failure based on the Weibull distribution. The main failure mode in TEC test is the cracks propagating along the boundaries of the recrystallized grains at the corner of a solder joint, similar as the TC test. The higher acceleration rate of TEC test might be related to the intermetallic evolution both at the interface and in the solder bulk. Thus, it could be concluded that the thermoelectric test would be a valuable option to achieve highly accelerated reliability test for electronic products.