Effect of silver content and vacuum reflow soldering on thermal fatigue life of Sn-Ag-Cu solder

Sn-Ag-Cu solder which reduced silver content may be increasing of the market share in the future. Applicability to products, sufficient examination is required for low silver solder used in harsh environments. It is because change of the solder joint reliability by silver contents. Moreover, silver content influences solder wettability and the amounts of voids in the solder joints. In order to decrease the void, the vacuum reflow process was developed. Experimental evaluation of the thermal fatigue which discovered the influence of silver contents of solder and the amount of voids was performed. The thermal fatigue lifetime was prolonged with the increase in silver. By vacuum reflow, the void decreased and the thermal fatigue life-time was prolonged. However, this tendency was not seen with parts with big solder joint area. This result show that crack progress may not have regularity.