2019 Volume 19 Issue 1 Pages 38-43
In this paper, we describe the effect of controlling reacted NiAl and solder bond interface on bending strength of Al/Ni-reactively-soldered single-crystal Si specimens. The exothermic reaction in Al/Ni multilayer film was used to melt SnAg-solder film for producing Si solder joint. After the instantaneous bonding, Si rod-shaped specimens with the bonded section was prepared by mechanical dicing. Four-point bending test was then conducted to investigate the bending strength and the weakest layer or interface in the bonded section. The specimens with Al/Ni multilayer film deposited in the Al→Ni→…→Al→Ni order fractured at the base-side solder-NiAl interface. By changing the deposition order to Ni→Al→…→Al→Ni, the bending strength of the specimens increased and the fracture origin changed. With the usage of the free-standing film, bending strength increased more. The improvement of mechanical reliability would be caused by a reduction of the number of voids at the solder-NiAl interface.
