Shear Strength and Interfacial Compound of Sn-Ag-Bi-In Alloy

抄録

Sn–3Ag–8Bi–5In solder (melting point, 461–477 K) was investigated as a lead(Pb)-free solder. In order to evaluate the solderability of the Sn–Ag–Bi–In alloy, the shear strength of soldered joint and inter-metallic compound (IMC) were investigated. As an experimental procedure, a 0.5 mm diameter solder was set on the Ni/Cu/Cr-pad of a Si-substrate. The solder ball on the pad was reflowed with Rosin Mildly Activated (RMA)-flux in air, and the reflow temperature was controlled between 483 K and 533 K. The shear strength and microstructure of the solder ball were evaluated with and without aging. The results show that the shear strength of the Sn–3Ag–8Bi–5In solder ball had the highest value of 1.69N by reflowing at 513 K for 10 s. The shear strength decreased from 1.69N to 0.95N as the IMC thickness was increased from 1.75 \\micron to 1.9 \\micron. Needle-shaped Ni₃Sn₄ and plate-like (Ni, Cu)₃Sn₄ formed on the interface between the solder and the Under Bump Metallization (UBM) that was bonded for 10 s at 513 K.