Crystallographic characterization and growth behavior of (Cu,Ni,Pd)6Sn5 intermetallic compound in Ni(P)/Pd/Au/SnAgCu/Cu assembled solder joint

The interfacial reaction and crystallographic orientation of Ni(P)/Au/SnAgCu/Cu and Ni(P)/Pd/Au/SnAgCu/Cu assembled solder joints were investigated. With the aid of crystallographic analysis, the Pd influence on the grain structure and preferred growth orientation of intermetallic compound (IMC) on both Cu and Ni(P) substrates were revealed. On the Ni(P) substrate, the enhanced nucleation of (Cu,Ni,Pd)(6)Sn-5 resulted in the random grain texture and needle-like morphology in the Pd-doping assembled joints. This random texture of (Cu,Ni,Pd)(6)Sn-5 could hinder the crack propagation directly through (0001) plane of adjacent grains. As for the Cu substrate, the granular (Cu,Ni,Pd)(6)Sn-5 formed near the substrate and subsequently grew into a layer-like morphology after thermal aging. The granular grains of (Cu,Ni,Pd)(6)Sn-5 exhibited the concentrated texture after aging, whereas (Cu,Ni)(6)Sn-5 stilled revealed the random texture. Most important, the absence of high angle grain boundary among (Cu,Ni,Pd)(6)Sn-5 grains on the Cu substrate could further guarantee the lifetime of solder joint during the reliability test. Finally, the detailed correlation between microstructure variation and grain orientation will be investigated and discussed as well as the possible mechanism. (C) 2014 Elsevier B. V. All rights reserved.