Effect of adding porous Cu on the microstructure and mechanical properties of Pb-free solder joint

In this paper, the effect of adding porous Cu to Sn-based solder on the joint strength of the solder alloy was investigated. The porous Cu was arranged in a sandwich-liked layer with Sn-based solder alloys. The soldering process involved different soldering temperature and time. Shear test was also performed to evaluate the joint strength of the solder alloy for both with and without addition of porous Cu. Preliminary results showed that the shear strength increased proportionately with increasing soldering temperature and time. In addition, the shear tests on soldered sample with porous Cu showed an increase in joint strength compared to soldered sample without porous Cu. This result showed that porous Cu has influence on the shear strength of the soldered sample. The follow up investigation was conducted to analyse interfacial reaction that occurred at the solder joints. Details on deformation of intermetallic compound was observed by using optical microscopy (OM). Photo images showed that porous Cu reacted with molten solder paste and were diffused at the boundary of the solder alloys.