There are several reasons for copper wire yellow:
1. The furnace temperature of tin is high and the liquid is large, resulting in too large needle hole and fast penetration of copper tin.
2. The tin layer is too thin and the copper tin permeates quickly.
3. Excessive residue of the flux halogen, the surface acid washing is not thorough;
4. The packaging time is too fast, the heat is not scattered, the tin furnace is too impurities;
5. Copper quality not pass, impurity too much;
6. The temperature and height affect the activity of copper atoms, and the hot days are more yellow than the cold ones.
But how to solve this problem? There also have some tips:
1. The die aperture > line is +0.02mm (the purpose is simple and cannot be plated too thin);
2. After production, it can be packed in 2 hours or so before packaging (the purpose: internal heat dissipation);
3. Buy good flux and match the flux concentration, mainly for the flux influence on the quality of tin plating;
4. Choose a better anaerobic copper wire.