研究了Cu/Sn/Ni--P线性焊点在150和200 ℃, 电流密度1.0×10⁴ A/cm²的条件下化学镀Ni--P层消耗及其对焊点失效机理的影响. 结果表明, 在Ni-P层完全消耗之前, 阴极界面的变化表现为: 伴随着Ni--P层的消耗, 在Sn/Ni-P界面上生成Ni₂SnP和Ni₃P; 从Ni-P层中扩散到钎料中的Ni原子在钎料中以(Cu, Ni)₆Sn₅或(Ni, Cu)₃Sn₄类型的IMC析出, 仅有很少量的Ni原子能扩散到对面的Cu/Sn阳极界面. 当Ni--P层完全消耗后, 阴极界面的变化主要表现为: 空洞在Sn/Ni₂SnP界面形成, Ni₃P逐渐转变为Ni₂SnP, 空洞进一步展形成裂缝, 从而导致通过焊点的实际电流密度升高、产生的Joule热增加, 最终导致焊点发生高温电迁移熔断失效.

The consumption of electroless Ni-P and its effect on the failure mechanism of solder joints duringelectromigration under a current density of 1.0×10⁴ A/cm² at both 150 and 200℃ wereinvestigated using line-type Cu/Sn/Ni-P solder joints. Before the electroless Ni-P was completely consumed,the microstructural evolution of the Sn/Ni-P interface (cathode) was the formation of Ni₂SnP and Ni₃P accompanied by the consumption of the electroless Ni-P. Ni atoms diffused from the electroless Ni--P into the Sn solder under electron current stressing. Most Ni atoms precipitated as (Cu, Ni)₆Sn₅ or (Ni, Cu)₃Sn₄ in the Sn solder, and few Ni atoms could arrive at the opposite Cu/Sn interface (anode). After the electroless Ni-P was completely consumed, the microstructural evolutions of the Sn/Ni-P interface (cathode) were the formation of voids and the transformation from Ni₃P to Ni₂SnP. Furthermore, cracks that resulted from the propagation of voids significantly increased the current density through solder joints, and thus greatly enhanced the Joule heating of solder joints, resulting in the failure of solder joints by the fusing of Sn solder.