高电流密度作用下共晶SnBi钎料基体内部金属间化合物生长机制

研究Cu/SnBi/Cu焊点在电流密度分别为8×103，1×104和1.2×104 A/cm2的作用下通电80 h后钎料基体内部金属间化合物 (IMC)的形貌演变。结果表明：电流密度为8×10３ A/cm2时，在焊点的阳极界面出现了大量的形状不规则的IMC，而在阴极界面并未有明显的IMC形成；当电流密度为1×104 A/cm2时，阴极界面的IMC层呈扇贝状，有些IMC已经在界面处脱落，而阳极界面的IMC呈层状，而且厚度要比阴极的薄；当电流密度为1.2×104 A/cm2时，阳极界面的IMC厚度有所增加，但是阴极界面的IMC已经向钎料基体中进行了扩散迁移，使得界面变得凹凸不平。值得注意的是, 随着电流密度的增加，在阳极形成的Bi层的厚度明显增加

Mechanism of Intermetallic Compound Growth in Eutectic SnBi Solder Matrix with High Current Density

The morphology evolution of intermetallic compounds (IMC) in Cu/SnBi/Cu solder joint after current stressing at the current density of 8×103, 1×104 and 1.2×104 A/cm2 for 80 h was investigated. Results indicate that when the current density was 8×103 A/cm2, a lot of irregular-shaped IMCs were observed at the anode interface; however, there was no obvious IMC formation at the cathode interface. When the current density was 1×104 A/cm2, scallop-shaped IMC layer was formed at the cathode interface, and some of them had spalled from the interface; while at the anode interface, the lamellar IMC was formed, and it was thinner than that at the cathode interface. When the current density was 1.2×104 A/cm2, the thickness of the IMC layer at the anode interface increased. Nevertheless, the IMC at the cathode interface had diffused and migrated towards the solder matrix, which made the cathode interface uneven. It should be noted that, with the current density increasing, the thickness of Bi layer forming at the anode side increased greatly