Laser welding of Cu wires bundle and dumet wire for interconnection of electronic components: Investigation of the practical welding method of the ends

Recently, the use of environment-friendly manufacturing technology has increased in the electronics industry worldwide. In particular, the replacement of lead-containing solder with lead-free solder has been widely investigated. In this paper, laser welding of Cu wires bundle and dumet wire for the production of thermistors has been investigated as an alternative to soldering. The results are summarized below. When laser irradiation was applied to the end of the Cu wires bundle, the molten portion shrank and solidified in the direction of the laser irradiation. Laser welding without failure was achievable when the laser irradiation was applied at right angles to the lap direction of the Cu wires bundle and the dumet wire, and the laser irradiation position was shifted towards the dumet wire from the axis of the Cu wires bundle. The ends of the wires could be incorporated in the weld. Both the electric resistance and the tensile breaking load of the weld were equivalent to those of the dumet wire. It was possible to achieve perfect laser welding by experimenting with clamping, movement, lapping of wires and laser irradiation with the welding apparatus.