We all know that the key to the adhesion of the coating during the electroplating process of plastic workpieces lies in the pre-treatment process of the workpiece. So what are the improper operations when using roughening additives in our workpieces?
Based on on-site experience and the characteristics of plastic electroplating roughening additives, Bigley Technology analyzed that improper operation of the workpiece during the roughening process can directly affect the adhesion of the coating. Therefore, when plastic workpieces have poor adhesion effects, the following four points should be noted:
1. The proportion of chromic acid to sulfuric acid in the plastic roughening solution is out of balance or the concentration is low. When the plastic workpiece corrodes excessively in the roughening solution, the surface of the plastic collapses and cannot form regular shaped pits; Insufficient coarsening of the workpiece can lead to poor adhesion of the workpiece coating. Therefore, the concentration ratio of chromic acid to sulfuric acid in the roughening solution should be controlled at 1:1 during production.
2. The workpiece coarsening time is too long or too short, and the coarsening temperature is too high or too low. Generally, if the roughening time is too long, it will cause excessive corrosion; However, if the coarsening time is too short, it will not have the effect of etching and forming pores. When the temperature of the roughening solution is low, the roughening speed is slower, and the plastic surface cannot achieve the desired roughening effect; When the temperature is too high, the plastic surface will expand and contract during cleaning, resulting in a network of cracks on the plastic surface that we cannot see with the naked eye. During production, the temperature of the roughening solution should be controlled at 60-75 ℃ and the roughening time should be 6-15 minutes.
3. The trivalent chromium content in the plastic roughening solution is relatively high. After a period of production of plastic roughening solution, the hexavalent chromium in the solution will gradually be reduced to form trivalent chromium. The increase of trivalent chromium will significantly reduce the roughening time and effect of the workpiece, resulting in poor adhesion of the coating. Therefore, we should control the trivalent chromium content in the roughening solution within 15g/L during production.
4. The plastic roughening solution is contaminated. When the roughening solution is used for a long time, it will dissolve too much butadiene adhesive, which will hinder the roughening effect after being adsorbed on the surface of the workpiece, resulting in poor adhesion of the coating. Therefore, when the roughening solution is contaminated, 1/3 of the roughening solution should be updated and new plastic roughening additives should be added.
So, in order to improve the adhesion of plastic workpiece coatings, we should avoid these improper operations when using plastic roughening additives. If you are interested in roughening additives for plastic electroplating, please contact Bigley customer service for free samples and detailed technical information!
If you want to learn more about roughening additives, you can check the "Industry News".