Experimental analysis of Sn-3.0Ag-0.5Cu solder joint board-level drop/vibration impact failure models after thermal/isothermal cycling

摘要

Sn-3.0Ag-0.5Cu board-level lead-free solder joint drop (1000g, 1 ms)/vibration (15g, 25-35 Hz) reliability after thermal (-40-125 degrees C, 1000 cycle)/isothermal (150 degrees C, 500 h) cycling was reported in this study. The failure performance of solder joint and testing life were analyzed under design six testing conditions (1. Single drop impact, 2. Order thermal cycling and drop impact, 3. Order isothermal cycling and drop impact, 4. Single vibration 5. Order thermal cycling and vibration 6. Order isothermal cycling and vibration). The results revealed that the pre-cracks initiation during thermal cycling do not affect the solder joint drop impact reliability, but decrease the vibration reliability. The formation of voids weaken both drop and vibration reliability of solder joint. After thermal cycling, the crack initiated from beta-Sn near IMC layer, and continued propagation through the same path when under second in order vibration impact. But propagation path turn to IMC layer when under second in order drop impact. The drop life increases from 41 times to 49 times, and vibration life decrease from 77 min to 45 min. After isothermal cycling, the formation of voids let the cracks occurred at IMC layer under second in order no matter drop impact or vibration. The drop and vibration life is 19 times and 62 min respectively.