In Pcba processing, welding is a major connection and is a basic skill in pcba processing.
It is also one of the main methods of metal processing. In every stage of the pcba process, we must consider welding pick up the relevant questions.

1. The meaning of welding

Welding is the process of joining two or more separate work pieces into a single unit in a certain form and position. Heat, pressure or other methods can be used, with or without fillers, relying on inter atomic diffusion and bonding to achieve a permanent bond between the two metals.

2. Classification of welding

Welding can generally be divided into three categories: fusion welding, pressure welding and brazing.
(1) Fusion welding: During the welding process, the weldment joint is heated to a molten state, and the welding method can be completed without pressure. Such as arc welding, gas welding and plasma welding.
(2) Pressure welding: During the welding process, pressure must be applied to the weldment to complete the welding method. Pressure welding can be done with or without heating. Such as ultrasonic welding, pulse welding and forging.
(3) Brazing: a metal material with a low melting point is used as a brazing material, and the brazing material and the weldment are heated to a temperature higher than the melting point of the brazing material but lower than the melting point of the base material, and the base material is wetted by the liquid brazing material to fill the joint. The gap and the mutual diffusion of the base material realize a method of joining the weldments. Such as flame brazing, resistance brazing and vacuum brazing. According to the melting point of the solder, it is also divided into solder (melting point below 450 ° C) and brazing (melting point above 450 ° C).