The difference between wave soldering and selective wave soldering when doing PCBA processing

When we do PCBA processing for customers, most boards will have plug-in soldering materials. If the sample is small, manual soldering can be chosen to complete it, but once the order quantity is relatively large, wave soldering will be used. So what is the difference between fully automatic wave soldering and selective wave soldering?

The difference between wave soldering and selective wave soldering:

Wave soldering is to contact the entire circuit board with the tin-spraying surface and rely on the surface tension of the solder to naturally climb to complete the soldering. For large heat capacity and multi-layer circuit boards, wave soldering is difficult to meet the tin penetration requirements. Selective wave soldering is different. The dynamic tin wave that comes out of the welding nozzle directly affects the vertical tin penetration in the through hole; especially when performing lead-free soldering, because of its poor wettability, a more dynamic and strong tin wave is needed. In addition, it is not easy to leave oxides on the wave with strong flow, which will also help improve the welding quality.

The welding efficiency of selective wave soldering is indeed not as high as that of ordinary wave soldering, because selective soldering is mainly for high-precision PCB boards, which cannot be soldered by ordinary wave soldering. When traditional wave soldering cannot complete through-hole group soldering (defined in some special products, such as automotive electronics, aerospace, etc.), selective soldering with the help of programming to precisely control each solder joint is used. It is more stable than manual soldering and soldering robots, and the temperature, process, welding parameters, etc. are controllable and repeatable. It is suitable for products with increasingly miniaturized through-hole soldering and dense welds. Selective wave soldering has lower production efficiency than ordinary wave soldering (even 24 hours), and the production maintenance cost is high. The key to the solder joint yield depends on the NOZZLE state.

The main points to note for selective wave soldering are: 1. The nozzle state, the tin flow is stable, and the wave should not be too high or too low. 2. The welding pin should not be too long. Too long pins will cause the nozzle to deviate and affect the tin flow state.

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