After wave soldering, lead-free wave soldering or solvent cleaning, a white residue was found on the substrate, usually a residue of rosin, which did not affect the surface resistivity but was unacceptable to the customer and must be addressed .

1, wave soldering The main reason for this problem is usually flux, and sometimes change to another flux can be improved, rosin flux often produce white spots during cleaning, the best way is to seek the flux of the supplier Assistance, they are more professional.

2, residual impurities in the substrate manufacturing process, will also produce white spots in the long-term storage, this situation can be cleaned with flux or solvent.

3, Incorrect CURING can also cause white spots, usually generated in a batch. The substrate suppliers should be promptly returned and cleaned with flux or solvent.

4, the factory use of flux and substrate oxidation protection layer is not compatible, usually occurs in the new substrate supplier, or change the flux brand, should be asked to help solve the supplier.

5, due to the substrate used in the process of solvent changes in the substrate material, especially in nickel plating solution often cause this problem, it is recommended that the storage time is as short as possible.

6, Flux used too long has been aging, exposed to the air to absorb moisture deterioration, the flux should be updated, the usual foam flux should be updated weekly, immersion flux updated every two weeks, spray monthly update that is can.

7, the use of rosin-based flux, after the completion of the solder pot parked too long time to clean, causing white spots, solder and cleaning should be shortened as possible, you can improve.

8, cleaning the substrate solvent moisture content is too high, reducing the cleaning capacity and the white spot, the solvent should be updated promptly.