There are some PCB boards with processing defects in the PCBA processing in the PCBA factory These boards with processing defects cannot be shipped directly. They need to enter the repair process. They can only be shipped after being confirmed to be correct after being processed by the maintenance engineer, but not every board can be repaired successfully. Generally, PCBA factories have certain restrictions on some PCBA that need to be repaired. 
APS is a professional GUANGDONG PCBA factory, will give you a brief introduction of the repair criteria.
1. Rework and repair do not have design documents and regulations, have not been approved according to relevant regulations, and have no specific rework and repair process procedures.
2. The number of rework of PCBA
solder joints is limited, and it is impossible to repair unlimited times. Generally speaking, the number of rework of each solder joint should not exceed three times, otherwise the welding part will be damaged.
3. In principle, the components removed from the damaged PCBA should not be used again. If they need to be used, they must be screened and tested according to the original electrical performance and technological performance of the components, and can only be installed if they meet the requirements.
4. During the repair process of PCBA factory, the desoldering operation of each pad is also limited. Each printed pad should only be desoldered once. The thickness of the intermetallic compound (IMC) of a qualified solder joint is 1.5~3.5 µ m, and the thickness will increase after remelting, even to 50 µ m, the solder joint becomes brittle, the welding strength decreases, and there are serious reliability risks under vibration conditions; Moreover, remelting IMC requires higher temperature, otherwise IMC cannot be removed.
5. The camber and twist of surface mounted and mixed mounted PCBA after processing, assembly and welding are also required, less than 0.75%
6. Total number of PCBA assembly parts repaired: the total number of PCBA assembly
parts repaired is limited to six, and excessive repair and modification affect the reliability.
Post time: Feb-08-2023