Ni3Sn4-composed die bonded interface rapidly formed by ultrasonic-assisted soldering of Sn/Ni solder paste for high-temperature power device packaging

The time-consuming of transient-liquid-phase is a big challenge for the die bonding. In this paper, a novel rapid bonding method plus alloying design was proposed to cheaply fabricate Sn-Ni intermetallic joint for high temperature electronic packaging. The ultrasonic effect and the evolution of the joint microstructures, shear strength as a function of Ni content were systemically investigated. The amount of Ni3Sn4 in the joint increased with the addition of Ni, and when the Ni content reached 24 wt.%, the joint consisted of nearly sole Ni3Sn4 with a high shear strength of 43.4 MPa was achieved. After aging at 300 degrees C for 72 h in air, the shear strength of the joint obtained with smaller Ni content solder showed great improvement because of the phase transformation of residual Sn to Ni3Sn4, but for the Sn-24 wt.%Ni and Sn-30 wt.%Ni, it showed a little decrease due to the grains coarsening of Ni3Sn4. The acoustic cavitation and streaming effects dramatically accelerates the reaction of Ni and Sn during the ultrasonic-assisted soldering. The joint obtained by the Sn-24 wt.%Ni solder has the best potential to be applied in the power electronic packaging. (C) 2016 Elsevier Ltd. All rights reserved.