研究了Cu/Sn3.8Ag0.7Cu/Cu一维焊点在电流密度为5×103A/cm2、环境温度为100℃作用下晶须的生长机理。研究结果表明，通电300 h后，在Cu/Sn3.8Ag0.7Cu/Cu焊点的阳极界面出现了一些小丘，而在焊点的阴极出现了一些裂纹；通电500 h后，焊点阴极界面的裂纹进一步扩展，而且在裂纹处发现了大量纤维状Sn晶须，其长度超过10μm；继续通电达到700 h后，Sn晶须的数量没有增加，同时停止生长。由于电迁移的作用，金属原子在电子风力的作用下由焊点的阴极向阳极进行了扩散迁移，进而在阴极处形成裂纹。随着裂纹逐渐扩展，导致该区域处的电流密度急剧增大，焦耳热聚集效应明显，为了释放应力，形成了纤维状的晶须。%Cu/Sn3.8Ag0.7Cu/Cu solder joint with current density of 5×103A/cm2 at 100℃ was investigated. Results show that after current stressing for 300 h, some hillocks occur at the anode interface and some cracks appear at the cathode interface. As the electromigration test goes on for 500 h, the cracks propagate along the cathode interface. Furthermore, a large quantity of Sn whiskers appears at the crack region, whose lengths are beyond 10μm. As the current stressing reaches 700 h, the total whisker quantity dosen’t increase, and stop growing. Due to the electromigration, the metal atoms migrate from the cathode side to the anode side by the electron wind force, resulting in the crack formation at the cathode interface. Therefore, the current density at the crack region increases, leading to much more Joule heat accumulation, to release the stress, some whiskers are formed in this crack region.
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