Characterization of soldering alloy type Zn-In-Mg and the study of direct soldering of silicon and copper

The aim of study was to characterize the Zn-In-Mg soldering alloy type and investigate the direct soldering of silicon and copper. The Zn-In-Mg solder type has a broad interval of melting, which depends on the indium content in the solder. Solder microstructure is formed of a matrix with pure Zn. The MgZn2 phases and solid solution (In) β-In are precipitated along the grain boundaries. Tensile strength attains values from 46 to 124 MPa and is dependent on indium content. The bond with silicon is formed due to the reactions of active metals - In and Mg with the substrate surface. Diffraction analysis has also revealed the In13Mg7 phase. In spite of that, the bond formation with a copper substrate in not affected by In and Mg content. The bond is formed owing to interaction between the zinc from the solder and copper substrates. Two phases, namely CuZn4 and Cu5Zn8 were observed. The shear strength of Cu/Zn-In-Mg/Cu joints attains values from 56 to 62 MPa and the shear strength of Si/Zn-In-Mg/Cu joint is within 34-42 MPa.