Concealed dirt affects the bonding strength of nickel plated layer.
If the dirt in the hole and gap of the workpiece can not be cleaned up before pretreatment, it will be decomposed when electroplating. The adhesion of the coating in this range is very poor, and sometimes it may be immediately bubbling and falling off.
The influence of the thin copper plating layer on the bonding strength of nickel plating layer
In some copper-nickel-chromium plating processes, cyanide copper plating is adopted first and then acid bright copper plating is adopted. If cyanide copper plating is too thin, acidic copper plating is easy to occur "plating". Nickel plating on this coating, the nickel layer stress will pull the "plating" layer from the surface of cyanide copper plating together.
Bare hand contact with workpiece affects the bonding strength of nickel plated layer.
In the process of nickel plating, sometimes the workpiece is not hanging correctly enough, such as the tip, protruding parts toward the anode should be corrected in time, but do not use a bare hand wrench when correcting, otherwise it will inevitably leave a fingerprint and skin.
Solution: use clean plastic or metal rods to correct.
Influence of organic contamination on bonding strength of nickel plated layer
The main causes of organic impurities in bright nickel plating solution are the low purity of chemical raw materials used, the decomposition of brighteners and the introduction of polishing paste, the incomplete pretreatment of workpieces and the entrance of dirt hidden in hidden parts.
Solution: regular purification.
1. Add hydrogen peroxide 1~3ml/l to the solution under stirring.
2. Heat the solution to 50~60 C.
3、在搅拌下加入粉末状活性炭2~3 g/l (如果加的是颗粒状的应加倍加入）
3. Add the powdered activated carbon 2~3 g/l to the agitation (if the addition is granular, it should be doubled).
4, continue stirring for 2 hours.
5, filter for 2 hours after standing.
6. Add proper amount of additives and test.