Laser soldering of nickel plated steel sheets

Abstract

The growing prominence of the electric vehicle industry, fueled by environmental concerns, has demanded innovation in various aspects of battery technologies with special emphasis on increasing the efficiency of both electric storage and its retrieval. An unexplored area of this is to identify the possibilities and limits of laser soldering. Here, we reveal the effects of surface pretreatment conditions and the amount of filler, along with the laser power and irradiation time on the characteristics of laser-soldered joints, by simultaneously evaluating the electrical and mechanical behavior of laser-soldered nickel-plated steel sheets (Hilumin®). By describing the morphological characteristics of the resolidified solder and the electrical and mechanical properties of the joints, we identify three, characteristically different morphological appearances and highlight the optimal one, where uniform and mostly void-free solder can be produced. Furthermore, we report a correlation between the threshold of upper sheet melting (either expressed as laser power or irradiation time) and joint deterioration in terms of the electrical and mechanical properties of the joint. We conclude that laser soldering can create joints with outstanding electrical conductance and adequate mechanical stability that meets the critical specifications of battery joining technologies when the surface pretreatment condition and processing parameters are properly optimized.