Specific analysis of the factors that affect the penetration of tin through PCBA foundry materials

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1. Material
Tin melted at high temperature has strong permeability, but not all metals to be welded (PCB boards, components) can penetrate in, 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. Flux
Flux is also an important factor affecting PCB tin penetration. Flux mainly plays a role in removing surface oxides of PCB and components and preventing re-oxidation during soldering process. Flux selection is not good, coating unevenly, and the amount is too small. 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. Damaged nozzles need to be replaced in time to ensure that the PCB surface is coated with a proper amount of flux. Play the flux effect of flux.

3. Manual welding
In the actual plug-in welding quality inspection, a considerable part of the weldment only has the surface solder formed into a taper, and there is no tin penetration in the via hole. In the function test, it is confirmed that many of these parts are soldered. This situation is mostly caused by manual plug-ins During soldering, the reason is that the soldering iron temperature is not appropriate and the soldering time is too short. Poor solder penetration of pcba can easily lead to false soldering and increase the cost of repair. If the requirements for pcba tin penetration are relatively high and the welding quality requirements are stricter, selective wave soldering can be used, which can effectively reduce the problem of poor pcba tin penetration.