The usual reasons for yellowing are:
　　 1. The temperature of the tin furnace is too high and the fluidity is large, which leads to too large pinholes in the plating layer and fast penetration of copper and tin
　　2, the tin layer is too thin, the copper and tin penetrate fast
　　3. There are too many halogen residues in the flux, and the copper surface is not thoroughly pickled
　　4, the packaging time is too fast, the heat has not been dissipated, and the tin furnace has too much impurities
5. The quality of the copper material is not good enough. There are too many impurities because the temperature affects the speed of atomic activity, so hot weather is faster than cold weather. This problem is dealt with as follows: 1. Die diameter> wire diameter + 0.02mm (the purpose is very simple and the coating should not be too thin ); 2. After production, leave it for about 2 hours before packaging (purpose: internal heat dissipation) 3. Purchase a good flux and match the concentration of the flux. The main reason is that the flux affects the quality of tinning; 4. Choose a better one. Oxygen copper wire;