Influences of Exothermic Reactive Layer and Metal Interlayer on Fracture Behavior of Reactively Bonded Solder Joints

Abstract

Reactively bonded solder joints with Al/Ni exothermic films attract much attention in semiconductor and microelectromechanical systems (MEMS) industries. Higher bond strength of the joints is required for longterm mechanical reliability. We have investigated the strength of rectangularsolid single crystal silicon (SCS) specimens with reactively bonded Sn3.5Ag solder joint by using specially developed fourpoint bending test equipment. In this paper, the influences of Al/Ni exothermic film thickness and metallic interlayer on the strength are discussed. The strength increases with increasing Al/Ni film thickness and pressure load during bonding. Metallic interlayer between the solder and SCS also affects the strength because fracture origin is dependent on the types of metals. The obtained results suggest that reacted NiAl is durable against external forces compared with the solder and interlayer.