Influence of POSS nano-particles on Sn-3.0Ag-0.5Cu-xPOSS/Cu composite solder joints during isothermal aging

Polyhedral oligomeric silsesquioxanes (POSS) nano-particles reinforced Sn-3.0Ag-0.5Cu-xPOSS (x = 1, 3, 5) composite solders were prepared and were reflowed on Cu substrates at 543 K. Then, the solder joints were isothermal aged at 393 K for 24 and 48 h, respectively. Microstructural evolution of the solder joints were observed by scanning electron microscopy and the influence of POSS nano-particles on the solder joint were investigated. The results showed that beta-Sn primary phase was refined and the number of grain boundary increased with the addition of POSS nano-particles. The growth rates of intermetallic compounds (IMCs) layer were suppressed by the adsorption affection of POSS nano-particles to the IMCs layer during isothermal aging. Moreover, the dissolution process of the IMCs layer, which was accompanied by with the growth of the IMCs layer, changed the morphology of the IMCs layer. The growth rate and the dissolution rate of the IMCs layer in Sn-3.0Ag-0.5Cu-3POSS/Cu composite solder joint were the lowest.