以直角型Au/Sn-3.0Ag-0.5Cu/Au微焊点为对象,通过去除表面污染物和易挥发物以及观察焊盘Au层内部的微观缺陷,分析了无钎剂激光喷射锡球键合过程中溅射缺陷产生的原因及机理。结果表明:遍布Au层内的微空洞中的空气受热后体积急剧膨胀是导致溅射的关键因素。微空洞位置不同,形成的缺陷形态也不同,微空洞在焊盘边缘附近时容易引起锡溅,在焊盘中间位置时容易引起气孔缺陷,严重时锡溅和气孔同时出现。受凝固时间和气泡上浮极限速度的影响,初始尺寸较大的气泡易于形成空洞或锡溅缺陷,而较小的气泡则易在微焊点内部形成气孔。

The cause and mechanism of tin spattering in the free flux laser jet solder ball bonding (LJSBB) process were analyzed using a right-angle Au/Sn-3.0Ag-0.5Cu/Au micro solder joint by removing the surface contamination and the volatiles on the Au bonding pads and observing their inner microdefects of Au layer. Results reveal that the prompt expansion of the gas in the microvoids distributed randomly in the Au layer is the key factor leading to spattering. Moreover, if the positions of the microvoids are different, the shape of defects are different. When the microvoids are near the edge of the Au bonding pad, tin spattering occurs easily, whereas the microvoids far away from the edge lead to a gas hole, evenly bring to the tin spattering and the gas hole simultaneously. Because of the solidification time and the limited floating speed of the gas bubble, the larger initial gas bubble easily results in the gas hole or tin spattering, and the smaller one leads to the inner gas hole.