PCB Circuit Board Copper Protection Layer Introduction
The copper layer is electroplated with a copper-plating Protective agent. It is not easily oxidized in the air. It is extremely easy to oxidize when not used. The reason is that it is easily oxidized and loses its luster. The copper is soft and easy to activate, and it can form a good metal with other metal plating. Intermetallic bonding to achieve good adhesion between the coatings. Therefore, copper can be used as the bottom layer of many metal electrolytic depositions, and copper plating plays an important role in the production process of printed boards. Copper plating of printed circuit boards includes electroless copper plating and electroplating copper, among which electroplating copper is an important process in PCB fabrication.
Measures to eliminate such failures include: controlling the proportion of brightener in the bath by the Hall test or by looking at the condition of the workpiece; do not think that the more brightener, the better the brightness. When the brightener is excessive, the low current density region will show a clear boundary between bright and non-bright, and the complex parts will be coated with flowers. When the brightener is less bright, consider whether it is too much. At this time, if a small amount of hydrogen peroxide is added and the brightness is increased, part of the brightener should be disposed of. For any electroplating additive, we must adhere to the principle of less addition and diligence.
Accumulation of the decomposition products of the brightener in the plating solution may result in poor brightness and flatness of the plating layer, and no bright current density region. When it is found that the same proportion of brightener is used at a similar bath temperature, the consumption is much higher than the normal value, and excessive organic impurities should be suspected. There are too many organic solvents, and there is no copper powder in the plating solution; however, copper powdery precipitates having poor adhesion are deposited on the plating layer. The organic impurities in the plating solution should be treated at this time. In addition, do not neglect the adverse effects of organic impurities on the brightness of the low current density zone. The sensitivity of the current to organic impurities is particularly strong. It has been proved that the long-untreated bright copper plating solution uses 39/L high-quality activated carbon to adsorb organic impurities, and the full-light range of the low current density region of the Hall slot test piece may extend by several millimeters.