What is the wave soldering and its process?

1. The wave soldering refers to the melting of the soft solder ( Pb-Sn alloy ), sprayed by electric or electromagnetic pump to the position required by the design

the solder wave crests can also be formed by injecting solder into the solder pool, so that the PCB printed boards of the pre-inserted components are placed on the conveyor chain, through a certain angle and a certain depth of immersion, through the solder wave crests to achieve the process of solder joint welding.

2. Wave soldering process

( 1 ) The surface of the wave soldering

The surface of the wave soldering is covered by a layer of oxide film, which is almost static on the whole length direction of the surface of the solder wave, during the wave soldering process, the PCB contacts the surface of the tin wave, the oxide film ruptures, and the tin waves in front of the PCB are pushed forward, this shows that the whole oxide film moves at the same speed as the PCB.

( 2 ) When the PCB enters the front end of the peak, the substrate and the pin are heated, and the whole PCB is immersed in the solder before leaving the peak surface, that is, the solder is bridged, but at the moment of leaving the peak, a small amount of solder is attached to the pad due to the effect of wetting force, and because of the surface tension, the lead will shrink to the minimum state, and the wetting force between the solder and the pad is greater than the solder between the two pads cohesion. Therefore, a full and round solder joint will be formed, leaving the excess solder at the tail end of the wave crest, which will fall back to the tin furnace due to the effect of gravity.

( 3 ) Peak height

Peak height refers to the height of the PCB in the wave soldering. The numerical control is 1 / 2 ~ 2 / 3 of the thickness of the PCB, which will cause the molten solder to flow to the surface of the PCB and form a " bridge connection ".If the solder is too low, it is easy to cause air welding leakage welding.

( 5 ) Preheating pre-heater definition : it is a heating box made of a high temperature resistant material, and the heating pipe is placed in the heating box. The PCB is heated by radiating heat from the reflecting disk.

( 6 ) The main component of flux soldering flux is turpentine or rosin, the principle of which is that turpentine or rosin is vaporized at high temperature, vaporized turpentine or rosin is chemically reacted with the oxide layer of the metal, and the metal removed from the oxide layer is more favorable for welding. The flux density is ( 0.812 + 0.02 ) g / cm.

This article is from Allicdata Electronics Limited