Transient liquid phase bonding of Sn-Pb solder with added Ni particles

The signal needed to be led out to the substrate through the multi-level interconnection packaging structure. The zero-level packaging solder joint was remelted and caused reliability problems during the repeated welding process. In this paper, the composite solder was prepared by adding Ni particles with an average particle size of 28.9μm and a mass fraction of 22% into the 63Sn37Pb solder. The high temperature phase was formed by the reaction between the solder matrix and Ni particles. The melting point of composite solder was improved after reflow. By simulating the application fields of the composite solder and Cu substrate welding structure, the melting point of the composite solder increased with the increasing of welding time and the welding temperature, which was 190.66 ℃ under the condition of 280℃ reflowed for 60minutes. The voids in the solder joint were caused by volume shrinking and flux including. The main reason was that the existence of Ni particles reduced the fluidity and plasticity of the solder. During the welding process, the thickness of the solder joint could not adapt to the volume shrinkage caused by the formation of intermetallic compound, and then the tensile stress generated during the volume shrinkage process could be released through the voids. The shear strength of the solder joint decreased by 11% with the increase in reflow time and temperature, and the fracture mode changed from mixed fracture to brittle fracture.