PCBA processing tin penetration is mainly affected by factors such as material, wave soldering process, flux, manual soldering, etc., which can be adjusted and solved in the following ways:
1. Material factor solution
Tin melted at high temperature has strong permeability, but not all metals to be welded (PCB boards, components) can penetrate into it, such as aluminum metal, whose surface generally automatically forms a dense protective layer, and the internal molecules The difference in structure also makes it difficult for other molecules to penetrate. Second, if there is an oxide layer on the surface of the metal to be welded, it will also prevent the penetration of molecules. We generally use flux to treat it or brush it with gauze.
2. Solutions to flux factors
The flux is also an important factor affecting the poor tin penetration of PCBA processing. The flux mainly plays a role in removing the surface oxides of PCB and components and preventing re-oxidation during the soldering process. The selection of the flux is not good, the coating is uneven, and the amount is too much. A small amount will lead to poor tin penetration. A well-known brand of flux can be selected, which will have higher activation and wetting effects, and can effectively remove difficult-to-remove oxides; check the flux nozzles, and the damaged nozzles need to be replaced in time to ensure that the PCB surface is coated with a proper amount of flux. Give full play to the flux effect of the flux.
3. Solution to wave soldering factors
The poor solder penetration of PCBA processing is directly related to the wave soldering process. Re-optimize the soldering parameters with poor solder penetration, such as wave height, temperature, soldering time or moving speed. First, reduce the orbital angle appropriately and increase the height of the wave crest to increase the contact amount of liquid tin with the soldering end; then, increase the temperature of wave soldering. Generally speaking, the higher the temperature, the stronger the permeability of tin, but this should be considered. The components can withstand the temperature; finally, the speed of the conveyor belt can be reduced, and the preheating and soldering time can be increased, so that the flux can fully remove oxides, soak the solder ends, and increase the amount of tin consumed.
4. Solutions to manual welding factors
In the actual plug-in welding quality inspection, a considerable part of the weldment only has a taper on the surface of the solder, and there is no tin penetration in the via. The function test confirms that many of these parts are soldered. This situation is more common in manual plug-ins. During soldering, the reason is that the soldering iron temperature is not appropriate and the soldering time is too short. Poor tin penetration in PCBA processing can easily lead to false soldering problems and increase the cost of rework. If the requirements for PCBA processing tin penetration are relatively high, and the welding quality requirements are relatively strict, selective wave soldering can be used, which can effectively reduce the problem of poor tin penetration in PCBA processing.