Shear and tensile impact strength of lead-free solder ball grid arrays placed on Ni (P)/Au surface-finished substrates

Abstract

This study aims to investigate the shear and tensile impact behavior of ball grid arrays (BGAs) placed on Ni (P)/Au surface-finished substrates considering the microstructure and compositions of intermetallic compounds (IMCs) formed at the solder/substrate interfaces. Tests were conducted on as-reflowed and aged samples with four different compositions of solders such as Ni-doped and non-Ni-doped Sn-0.7 wt.%Cu, Sn-37 wt.%Pb and Sn-3.0 wt.%Ag-0.5 wt.%Cu, over a wide range of displacement rates from 10 to 4000 mm/s in shear and from 1 to 400 mm/s in tensile tests. In shear tests, there was almost no difference between as-reflowed and aged samples at low displacement rates in all the samples, while at high displacement rates the aged samples showed better properties than as-reflowed ones, in particular, in Ni-doped Sn-0.7wt%Cu samples. In tensile tests, the aging treatments had little effect on the strength for any compositions of solders at low and high displacement rates. Sn-3.0 wt.%Ag-0.5 wt.%Cu samples with any heat treatments showed the least resistance to both shear and tensile loadings at any displacement rates.