Prototype pcb manufacturing solder joint formation process and influencing factors

The prototype pcb manufacturing electronic product is soldered by heating and flux applications to activate the flux, remove the oxide film on the surface to be soldered, liquefy the solder and complete the wetting and diffusion process to form solder joints. Specifically, the formation of solder joints involves two processes:

A. Melting and recrystallization of the solder.

B. Wetting of the base metal surface (such as Cu), dissolution and diffusion of the base metal, interfacial reaction and formation of intermetallic compounds (IMC)

The formation of solder joints involves four aspects: the metal to be soldered (and its solderability), the solder alloy, the flux, and the heating. It is often referred to as the four major factors affecting soldering.

Heating to activate the flux, solder wetting the surface of the metal to form a prototype pcb manufacturing solder joint, whether it is reflow soldering, wave soldering, or soldering iron soldering, heating is the most important process condition, it must meet two mutual contradictory requirements;

1. The soldering surface must have sufficient heat to wet the solder;

A.SMT process failure and assembly reliability

B. The welded components can not hot enough to the temperature at which they are damaged.

Flux has two important functions of removing oxides from the surface to be welded and preventing oxidation of the metal surface to be welded. It is the main reason why molten solder can wet the surface to be welded, and it is also an important factor affecting the shape of the prototype pcb manufacturing solder joint. In the actual welding project, there are phenomena such as non-wetting, weak wetting, and non-melting tin. In addition relate to the poor weldability of the surface to be welded, it is also related to the deoxidation of the flux and the ability to prevent reoxidation.