1. Issues related to substrate processing:

　　Especially for some thinner substrates (usually below 0.8mm), due to poor substrate rigidity, it is not suitable to use a brush machine to brush the board.

　　This may not effectively remove the protective layer specially treated to prevent oxidation of the copper foil on the surface of the substrate during production and processing. Although this layer is thin and easy to remove by brushing, chemical treatment poses significant difficulties. Therefore, it is important to pay attention to control during production and processing to avoid poor bonding between the substrate copper foil and chemical copper, which may cause foaming on the surface of the substrate; When blackening is carried out on thin inner layers, there may also be problems such as poor blackening and browning, uneven color, and poor local blackening and browning.

　　2. The phenomenon of poor surface treatment caused by oil stains or other liquids contaminated with dust during machining (drilling, lamination, milling, etc.) of the board surface.

　　3. Defective copper brush plate:

　　Excessive pressure on the grinding plate before copper sinking causes deformation of the hole opening, resulting in rounded copper foil corners or even substrate leakage at the hole opening. This can cause bubbling at the hole opening during processes such as copper sinking, electroplating, tin spraying, and welding; Even if the brush plate does not cause substrate leakage, an excessively heavy brush plate will increase the roughness of the copper at the hole opening. Therefore, during the micro etching and coarsening process, the copper foil at this area is prone to excessive coarsening, which also poses certain quality risks; Therefore, attention should be paid to strengthening the control of the brushing process, and the brushing process parameters can be adjusted to the best through abrasion tests and water film tests;

　　Washing problem:

　　Due to the need for a large amount of chemical solution treatment in the electroplating process of copper plating, there are many types of acid, alkali, and organic solvents, and the surface of the board cannot be washed clean with water. Especially when adjusting the oil removal agent for copper plating, it not only causes cross contamination, but also results in poor local treatment or uneven treatment effect of the board surface, causing some bonding problems; Therefore, attention should be paid to strengthening the control of water washing, mainly including controlling the flow rate, water quality, washing time, and dripping time of the cleaning water; Especially in winter when the temperature is low, the washing effect will be greatly reduced, and it is even more important to pay attention to controlling the washing process;