Emerging Applications for Low Melting Point Solders

Electronic assembly requires the use of proper solders to establish electrical circuits and connections. Low melting point solders are fairly new and have the potential to be a low-cost way to establish reliable and strong joints. Low melting point solders are suitable for surface mount technology processes and they deliver high-quality joints while reducing operational costs, as they reduce the need for additional materials, labor, and energy. Using the material in through-hole steps can replace two critical SMT steps and the wave soldering process, resulting in more value for electronics manufacturers.

A lead-free alloy in a good solder material provides a lower melting point while exhibiting temperature resistance in advanced thermal cycling tests. Using low melting point solders can create value to your company and assembly process once it is established in your electronic assembly procedure. SAC alloys used to be the main alloys used in large-scale electronic manufacturing when lead-free standards were initially implemented. However, some manufacturers have begun looking into innovative alloy alternatives for their SMT processes, as lead-free soldering continues to thrive in the industry.

A low melting point of 138°C enables peak reflow temperatures between 170 to 180°C. The SnBiAg alloy system in the solder paste meets those parameters for reflow and melting point. Some lead-free alloys in certain products may have a lower melting point, but the resistance is good against accelerated thermal cycling tests in consumer electronics. This way, low temperature SMT processes help eliminate the wave soldering step, which is often a part of mixed technology assemblies.

Low melting point solders can be practical as you implement an SMT-only assembly process to ensure higher and streamlined throughput. It lets you switch to a low-temperature processing that can enhance secondary soldering, a process that will enable you to rework certain components, like RF shields that must be soldered separately. Low temperature alloys may also be used as an alternative to mercury in certain applications, so you can ensure the safety of your workers.