The difference between selective wave soldering and ordinary wave soldering

Select the fundamental difference between wave soldering and ordinary wave soldering. Wave soldering is the contact of the entire circuit board with the spray surface relying on the natural climb of the surface tension of the solder to complete the welding. For large heat capacity and multilayer circuit boards, wave soldering is difficult to meet the requirements of tin penetration. The dynamic tin wave is flushed out of the welding nozzle, and its dynamic strength will directly affect the vertical tin penetration in the through hole. Especially for lead-free welding, because of its poor wettability, it needs a dynamic and strong tin wave. In addition, there is no residual oxide on the strong flow crest, which will also help to improve the quality of welding.

The welding efficiency of selective wave soldering is indeed not as high as that of ordinary wave soldering, because selective welding is mainly for high-precision PCB boards, which can not be welded by ordinary wave soldering. When the traditional wave welding cannot complete the through-hole group welding (defined in some special products, such as automotive electronics, aerospace, etc.), at this time, the selective welding of each solder joint can be precisely controlled by programming, which is more stable than manual welding and soldering robot, and the temperature, process, welding parameters and other controllable and repeatable control; It is suitable for today's through hole welding more and more microform, welds-intensive products. Selective wave welding is lower than ordinary wave welding production efficiency (even 24 hours), production and maintenance costs are high, the key point yield is to look at NOZZLE status.

Selective wave welding main attention: 1, nozzle state. The tin flow is stable, and the wave cannot be too high or too low. 2, the welded pin should not be too long, too long the pin will cause the nozzle offset, affecting the tin flow state.