Low-Temperature Soldering (LTS) in the Electronics Industry: a Brief Review

Soldering is still the main joining technology of the electronics industry; thus, the quality and reliability of the solder joints determine the whole circuit’s quality and reliability. The lowtemperature soldering (LTS) is a new and emerging trend in the electronics industry, and it means that the melting temperature of the solder alloy is typically below the melting point of the classical eutectic Sn63Pb37 alloy ($183^{\circ} \mathrm{C}$). The LTS solder alloys are usually composed of tin (Sn), bismuth (Bi), or Indium (In), but not exclusively. The exact composition, additives, and, finally, the characteristics of the LTS solder alloy depend more on the manufacturer than in the case of classical SnAgCu lead-free alloys. They are usually applied to thermally sensitive components and circuit boards to mitigate warpage defects and reduce energy costs. In our review article, we would like to give an overview of the history and the current status of LTS technology in the electronics industry.