Microstructure and mechanical properties of resistor chip joints fabricated by laser soldering using Sn-58Bi solder on Ni(P)/Cu pads

With the miniaturization of electronic devices and the utilization of heat-sensitive electronic components, the couple of solder with low melting temperature and laser soldering technology would be applied in electronic packaging. In this study, the microstructure and mechanical properties of resistor chip joints fabricated by laser soldering were investigated. The energy input of the laser was 1 W and the soldering time was more than 0.3 s, resistor chip could be bonded with pads reliably. Precipitated Bi phase was not observed in the laser soldering joints due to the rapid cooling rate. Ni 3 Sn 4 IMCs layer formed between Sn-58Bi solder and Ni(P)/Cu pads. The thickness of IMCs layer was less than 1.0 µm even if the laser soldering time was more than 1.0 s. The maximum shearing force of laser soldered joints increased with increasing the soldering time which was slightly lower than that of reflow soldered joints.