Reinforcing cross-tension strength of adhesively bonded joints using metallic solder balls

Abstract With the broader utilization of adhesive bonding in the automotive industry for structural lightweight applications, hybrid joining methods such as weld or rivet-bonding are being employed to complement the strength of adhesive-only joints. In this paper, a novel method to significantly improve the energy absorption of adhesive bonds by the addition of solder balls was developed and experimentally verified. Numerical analysis predicted a maximum increase of cross-tension strength and energy absorption by 25% and 80%, respectively. Our experimental study exhibited the same trend and achieved a maximum increase of strength and energy absorption of 17.5% and 40%, respectively. Microscopy indicated the presence of a thin adhesive layer between the solder balls and substrate after bonding which is believed to limit the full theoretical potential of the solder-adhesive bond strength. Effects of volume fraction of solder balls, and pre-tightening of the solder-adhesive joint prior to curing on the mechanical performance of solder-adhesive bonds were investigated. Additional work is ongoing to explore avenues to achieve the full potential of solder adhesives.