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IMC morphology, interfacial reaction and joint reliability of Pb-free Sn–Ag–Cu solder on electrolytic Ni BGA substrate

2004; Elsevier BV; Volume: 392; Issue: 1-2 Linguagem: Inglês

10.1016/j.jallcom.2004.09.045

1873-4669

Jeong‐Won Yoon, Sang-Won Kim, Seung‐Boo Jung,

Advanced Welding Techniques Analysis

The interfacial reaction, morphology of intermetallic compound (IMC) and shear strength between the Sn–3.5Ag–0.7Cu (in wt.%) solder and Ni ball grid array (BGA) substrates during reflow at 255 °C for up to 20 min were investigated. The reaction between the molten solder and Ni layer resulted in the formation of two IMCs such as (Cu, Ni)6Sn5 and (Ni, Cu)3Sn4 at the interface. The (Ni, Cu)3Sn4 IMCs were needle-like type, while the (Cu, Ni)6Sn5 IMCs were cylinders with a hexagonal cross-section and pointed tips. Compared to the quenched sample, the (Cu, Ni)6Sn5 IMCs nucleated heterogeneously on the (Ni, Cu)3Sn4 layer during the solidification of the solder. In the ball shear test, the shear strength value did not change much as a function of reflow time. In all samples, the fracture occurred in the bulk solder. The results of interfacial reaction and shear test in this study show that the Sn–Ag–Cu/Ni BGA solder joint has a desirable joint reliability.