A review of soldering by localized heating

In recent years, the rapid development of the new energy industry has driven continuous upgrading of high-density and high-power devices. In the packaging and assembly process, the problem of differentiation of the thermal needs of different modules has become increasingly prominent, especially for small-size solder joints with high heat dissipation in high-power devices. Localized soldering is considered a suitable choice to selectively heat the desired target while not affecting other heat-sensitive chips. This paper reviews several localized soldering processes, focusing on the size of solder joints, soldering materials, and current state of the technique. Each localized soldering process was discovered to have unique characteristics. The requirements for small-size solder joints are met by laser soldering, microresistance soldering, and self-propagating soldering; however, laser soldering has difficulty meeting the requirements for large heat dissipation, microresistance soldering requires the application of pressure to joints, and self-propagating soldering requires ignition materials. However, for small-size solder junctions, selective wave soldering, microwave soldering, and ultrasonic soldering are not appropriate. Because the magnetic field can be focused on a tiny area and the output energy of induction heating is large, induction soldering can be employed as a significant trend in future research.