There are usually several reasons for yellowing:
1, the tin stove temperature is too high, the fluidity is big, causes the coating pinhole to be too big, the copper tin penetration fast
2, tin layer is too thin, copper tin infiltration fast
3, Flux halogen residue too much, copper surface pickling is not thorough enough
4, packaging time is too fast, heat is not dispersed, tin furnace impurities too much
5. Copper quality does not pass, the miscellaneous son too many
Because the temperature affects the speed of the atoms, hot weather turns yellow faster than cold.
This issue is handled as follows:
1. The mold aperture and the line through +0.02mm (the objective is very simple cannot the coating too thin);
2. After the production of 2 hours after the packaging can be (purpose: internal cooling)
3. The purchase of good flux, with a good flux concentration, mainly the flux impact on the quality of tin plating; 4. Choose better oxygen-free copper wire;