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研究了Cu/Sn/Ni-P线性焊点在150和200℃,电流密度1.0×10~4 A/cm~2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Ni_2SnP和Ni_3P;从Ni-P层中扩散到钎料中的Ni原子在钎料中以(Cu,Ni)_6Sn_5或(Ni,Cu)_3Sn_4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/Ni_2SnP界面形成,Ni_3P逐渐转变为Ni_2SnP,空洞进一步扩展形成裂缝,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 effects of electroless Ni-P layer consumption on the solder joint failure mechanism of Cu / Sn / Ni-P solder joints at 150 and 200 ℃ and current density of 1.0 × 10 ~ 4 A / cm ~ 2 were studied. The results show that before the Ni-P layer is completely consumed, the change of the cathode interface is as follows: Ni 2 SnP and Ni 3 P are formed on the Sn / Ni-P interface with the depletion of the Ni-P layer; The Ni atom in the material precipitates in the brazing filler metal with (Cu, Ni) 6Sn_5 or (Ni, Cu) _3Sn_4 type IMC, and only a very small amount of Ni atoms can diffuse to the opposite Cu / Sn anode interface. When the layer is completely consumed, the changes of the cathode interface are mainly as follows: the voids are formed at the Sn / Ni_2SnP interface, Ni_3P gradually changes to Ni_2SnP, and the voids further expand to form cracks, resulting in the increase of Joule heat generated by the increase of the actual current density through the solder joint , Eventually leading to the occurrence of high temperature melting point solder melting fuse failure.