In PCBA processing plants, we often encounter some defective products or boards that need to be repaired when there are problems. So why do we need to pay attention to repairing or repairing? Let’s take a look at the following Sanjing:

Solder joint defects such as open circuits, bridges, false soldering and poor wetting generated in reflow soldering and wave soldering processes need to be manually trimmed and removed with the help of necessary tools (such as BGA rework station, X-Ray, high-power microscope, etc.) Various solder joint defects, so as to obtain qualified PCBA solder joints.

However, the solder joints to be repaired should be judged before repairing: ①The electronic product should be positioned before judging what solder joints need to be repaired. Determine which level of product the electronic product belongs to. If the product belongs to the first level, it is sufficient to comply with the minimum standard requirements, but if the product belongs to the third level (the highest requirement), it needs to be tested according to the highest standard, because the third level product is based on reliability. As the main goal.

②Clarify the definition of good solder joints: Good SMT solder joints refer to solder joints that can maintain electrical performance and mechanical strength in the use environment, method and lifespan considered by the design. Therefore, as long as this condition is met, repairs are not necessary.

Rework is generally for repairing missing components, or replacing components that are damaged at the location of the patch, and it also includes repairing after leaving the factory.

Three, rework matters needing attention

①Do not damage the pad.

②The component surface and PCB surface must be flat.

③Component availability: If it is double-sided welding, one component needs to be heated twice, if it is reworked once before leaving the factory, it needs to be heated twice (disassembled and soldered once each); if it is repaired once after leaving the factory, it needs to be heated again twice. Based on this calculation, a component must withstand at least six times of high-temperature soldering to be considered a qualified product. Therefore, for high-reliability products, components that may have been repaired once cannot be used again, otherwise reliability problems are likely to occur.

④Pay attention to the number of potential electrostatic discharge (ESD) hazards. The most important thing for repair is to follow the correct welding curve.

The above is about the purpose and precautions of PCBA repair, I hope it can be helpful to everyone!