All About Low-Temperature Solders

Low-temperature soldering is applied to the SMT (surface mount technology) process for electronic devices and products that should not be exposed to extreme temperatures. A low temp solder is crucial to the process, and certain types of alloys will be used depending on the process or the product being manufactured. Several benefits are identified from low-temperature soldering and some of these include the use of lead-free solders, the ability to conduct step soldering, and reduction of thermal shock, a risk that tends to be higher as peak temperatures rise. Hence, damages that are caused by high temperatures can effectively be minimized with a low-temperature solder. This may help reduce peak flow reflow temperature that can damage components, too.

Low temp solder has enabled step soldering, which allows multiple reflow processes to be conducted on one board. For instance, if normal components can handle high reflow temperature, they can be soldered to the board with a standard surface, while components that can only handle lower temperatures can be added in a separate reflow process. Step soldering will reduce the time it takes to solder components compared to when you hand solder the parts. Moreover, it does not require special training or investing in new or different equipment.

A lot of low-temperature solders do not contain any lead, making them ideal for lead-free manufacturing. A solder alloy that melts in low temperatures should be able to start melting at below 183°C or above 50°C. Tin, lead, indium, and bismuth are the most common alloys that meet this range. Cadmium alloys are extremely toxic, so they are not used. When determining which alloy to use for soldering, you need to consider its wettability, long-term stability, reliability, and practicality.

Low-temp solder alloys can be used for a variety of applications soldering MID (molded interconnect device) plastics, step soldering of temperature-sensitive components, and processes where fuse and fusible alloys are involved, like in lens blocking, tube bending, potting molds, and wax pattern dies. With low-temperature soldering, MID plastics can be transformed into 3D shapes to boost the functionality and reduce the weight of the product. Low-temperature solders can be suitable replacements to mercury as they offer excellent electrical and thermal conductivity.

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Alpha Assembly Solutions Inc. is the global leader in the development, manufacturing and sales of innovative specialty materials used in a wide range of industry segments, including electronics assembly, power electronics, die attach, LED lighting.