Failure of chip sized packaging (CSP) under coupling fields of electrical current and thermal cycle

In this work, we investigated the failure behavior of a commercial chip size packaging (CSP) under coupling fields of electrical current and thermal cycles. The failure process was real-time monitored through the response resistance change. Under the coupling condition, the lifetime was much shorter than that in single thermal cycle condition. Instead of the void accumulation mechanism, the excessive Joule heat was considered to be failure mechanism in coupling condition. The high temperature induced rapid dissolution of Cu UBM and overheat led to the melt of the solder.