Pressure-assisted soldering of copper using porous metal-reinforced Sn58Bi solder

摘要

In this study, porous metals (Ni, Cu) with the porosity of 110 and 500 ppi were, respectively, added into the SnBi solder joint to obtain the SnBi@P-Cu and SnBi@P-Ni composite solder joints. To ensure the bonding quality between the solder layers and the Cu substrates, a low pressure of 0.1 MPa was conducted during the soldering process. The microstructure and shear behavior of the composite solder joints were investigated. With the addition of 110 ppi porous metals, the microstructures of the solder joints are mainly composed of porous metals and SnBi solder matrix. As the porosity of P-Cu and P-Ni metals increases to 500 ppi, the concentration of the SnBi matrix decreases sharply in the solder joints. The cross-sectional microstructures of the solder joints present a uniform morphology of P-metals and intermetallic compound (IMC). Here the IMC is Cu_6Sn_5 in the SnBi@P-Cu joint, but (Ni, Cu)_3Sn_4 and (Cu, Ni)_6Sn_5 in the SnBi@P-Ni joint. The shear strength of the SnBi solder joint increases significantly with the addition of porous metals. The average shear strength of SnBi@110P-Cu reaches 85.28 MPa, which is the highest among the investigated solder joints.