wave soldering process is widely used two-wave, the first peak is the cylindrical wave (mainly used for welding secret plot of the SMD components, easy to exhaust air, reducing the weld), the width of the wave surface more narrow. The second peak for the flat wave, crest flat, stable, like a mirror, the flow rate to slow. There are always new waves on the surface of liquid tin and oxygen exposure, tin oxide in liquid slag is formed under rapid flow of material, it is very different from the static oxidation, the oxidation of dynamic slag formed when there are three forms.
(1) the surface oxide film. Tin tin furnace liquid material at high temperatures, exposure to oxygen in contact with each surface and oxidized. This is the main component of the surface oxide film SnO. As long as the liquid state is not destroyed, it can play a role in the absence of air to protect the inner solder result of the above oxide slag formation and composition, to reduce the oxidation residue from the following aspects:
not continue to oxidation.
(2) black powder. Produced in liquid junction with the mechanical shaft, causing rotation around the axis of the vortex surface, oxide-axis movement by the friction with the ball. While rubbing the surface of the particle temperature, and increased oxidation.
(3) oxidation residue. Tin stove generator improper design formed violent rolling surface, oxygen in the air is continuously inhaled tin material inside. Because a limited number of inhaled oxygen, oxidation is not sufficient to produce large amounts of silver within the sand-like (or rubbish-like) oxidation residue. The content of the slag in the oxidation accounts for the main ingredient, and some can reach more than 90%.
1. Tin surface level is not too low: level too low to increase the crest of the gap, increasing the area of contact with air and liquid tin tin bath down the impact of surface intensified roll
2. Slag too frequent: tin-tin oxide surface with the absence of air to do with tin oxide is inversely proportional to the speed and time, but frequently exacerbated slag tin oxide.
3. Crest play too: an increase of flow rate and the impact of tin, to increase the amount of oxygen combined with tin.
4. Tin stove vents designed to change: my company after long-term efforts and communication with customers, broke and now the equipment factory tin stove design ideas, the installation of diversion tank, oxidation sets and jet width adjusting mechanism, greatly reducing the a tin of liquidity, measured by the oxidation of slag at the customer's weight, every 8 hours not more than 1.2KG (200 width of the PCB). To save customers a lot of resources.