Soldering

Soldering is performed by a Vitronics Soltec XPM 820 using the reflow soldering method, which is the method of choice when connecting surface mount devices (SMDs) to printed circuit boards.

Reflow soldering is a relatively simple process. Solder in the form of paste is heated in contact with components and the PCB. Depending on the alloy, the solder paste particles become liquid at around 180ºC. In the case of lead-free paste the temperature will be higher depending on the alloy selected, but typically about 235ºC. When the solder is liquid, a joint will form between the two surfaces.

Nitrogen is used in reflow soldering to drive out the oxygen from the soldering chamber. This prevents the solder pads and component terminals to oxidise during reflow of the solder paste. The visual appearance of the solder joint surface will be smoother and in some cases shinier.