Angled high strain rate shear testing for SnAgCu solder balls

Abstract

A high speed shear test of solder ball at different shear angles has been developed and investigated for SnAgCu solder balls. The objective of the test is to introduce vertical loading component in the high speed shear test and to study intermetallic response of different solder balls. The shear test is performed at three angles of attack e. g. 3, 5 and 10 degree. The basic shear tester allow high speed shear tool movement of up to 4000 mm per second, and capture the load-displacement curve experienced by the shear tool. Using this setup, high-speed shear characterization has been carried out on microBGA sample with Sn3Ag0.5Cu and Sn1Ag0.5Cu solder on Ni/Au pad finish. In this paper, the effect of angle shear at high speed on these SnAgCu BGA balls is presented, with the details of load-displacement response and failure mode for these solder balls. Generally all the samples show changes in ductile-to-brittle failure as shear speed increases. The angled shear test lead to down shift of ductile-brittle transition to occur at lower shear speed with larger shear angle. It is found to improve sensitivity in revealing brittle failure for solder ball characterization.