Ultrasound-assisted soldering of alumina using Ni-foam reinforced Sn-based composite solders

Abstract

Abstract Ultrasound-assisted dipping was performed to fabricate a Sn coating layer on the Al 2 O 3 ceramic, then the as-coated Al 2 O 3 ceramics were ultrasonically soldered with Ni-foam reinforced Sn and Sn-9Zn composite solders, respectively. Effects of ultrasonic soldering time on the microstructure and mechanical properties of joints were investigated. A pure Sn metallization layer which exhibited excellent metallurgic bonding with Al 2 O 3 ceramic was fabricated by ultrasonic dipping for more than 40 s. For Al 2 O 3 joints soldered with composite solders for 4 s, Ni skeletons distributed irregularly in the soldering seam and some pores existed in the base solders. A thin Ni 3 Sn 4 intermetallic compound (IMC) layer was formed at the Sn/Ni interface while no reaction phase was found at the Sn-9Zn/Ni interface. Increasing the ultrasonic soldering time to 12 s the Ni skeletons were compressed into a strip type. In the Al 2 O 3 /Ni-Sn/Al 2 O 3 joint, the gaps among Ni skeletons were filled with Ni 3 Sn 4 layers with some reaction cavities trapped in them. However, in the Al 2 O 3 /Ni-Sn9Zn/Al 2 O 3 joint, the Ni skeletons gaps were mainly filled with (Ni,Zn) 3 Sn 4 bulks with some (Ni,Zn) 3 Sn 4 particles dispersed between them. The Al 2 O 3 /Ni-Sn9Zn/Al 2 O 3 joint soldered for 12 s exhibited the highest shear strength of 53.45 MPa with the joint shear failed at the interface of filler metal layer and Al 2 O 3 ceramic.