Leak plating is a frequent problem in the production of electroless nickel plating on ABS plastics. Because the missing parts of ABS plastic workpieces are not conductive, in the subsequent electroplating production, there is no metal deposition in the missing parts, resulting in unqualified product quality. Generally, leakage plating can be divided into two types: sheet leakage plating and pinhole leakage plating.
1. Sheet-like leakage plating
The roughening solution for the electroplating process of plastic parts uses high-concentration chromic acid and concentrated sulfuric acid solution, which is prone to be caused by the incomplete washing and neutralization process after the roughening process, or because the shape of the workpiece is complex, the roughening solution is easy to store inside. , Resulting in the partial surface of the workpiece being unable to "grab" the palladium during the sensitization process, and even during electroless nickel plating, the residual roughening solution inside the workpiece gradually seeps out to dissolve the deposited electroless nickel layer, which will eventually lead to the partial position of the workpiece There is no electroless nickel layer, this kind of missing plating caused by the remaining roughening solution on the workpiece is sheet-like missing plating.
2. Pinhole leakage plating
Pinhole leakage refers to the small dot-like leakage on the surface of the workpiece after electroless nickel plating. This defect is easily confused with pitting after electroplating. The difference between the two lies in whether there is metal deposition or no metal at this point. What is deposited is pinhole leakage plating, which not only affects the appearance of the product, but more importantly, reduces the corrosion resistance of the product coating, resulting in unqualified product quality. According to our Lejiang team’s long-term observations at the customer’s production site, the main factors leading to pinhole leakage plating are: solid impurities suspended in the plating solution: dust in the air and acidic substances volatilized from the roughening tank. These substances are adsorbed on the surface of the work piece, blocking the electroless nickel plating reaction, resulting in no plating deposition at this adsorption point. Therefore, the key to solving this problem is to strengthen the continuous filtration of the tank liquid, keep the production site environment clean, and block the air circulation between the roughening tank and the electroless nickel plating tank.
