1. Liquid preparation: the so-called liquid preparation is to conduct chemical reaction between sulfuric acid and copper in the liquid preparation tank under heating conditions (generally 70-90), and then finally generate copper sulfate solution, and then use a special pump to inject the electrolyte into the storage tank.

2. Electrolysis: The process of producing thick foil by electrolysis is carried out in the electrolysis machine. The electrolytic cell is composed of cathode roller, anode semicircle lead zinc plate and electrolytic cell. Under the action of DC voltage, the divalent copper ions in the electrolyte move towards the interface of the cathode roller, generate copper atoms through reduction reaction, and concentrate on the surface of the cathode roller. With the gradual progress of electrolysis, the core particles of copper grains formed on the roll will gradually grow into uniform and fine equiaxed crystals. When the electrodeposition reaches the basic thickness requirement of the thick foil and forms a solid metal copper layer, the thick foil will be continuously stripped from the cathode roll when the cathode roll rolls out of the electrolyte level in the electrolytic cell. Then, rough foil is generated by trimming and winding.

The smooth surface of wool foil is near the cathode roller. Its quality depends on the polishing quality of the cathode roll and the maintenance of the roll surface. The foil surface on the other side of the cathode roll is called the foil surface. The roughening process is carried out on rough surfaces. The roughness of matte surface is closely related to the filtration quality of solution, additives, current density and other conditions.

3. The smooth surface of the surface treated copper foil is the surface of the PCB circuit, and the rough surface is the junction surface with the PCB substrate. Laminates cannot be made of rough foil, but the rough foil surface shall be treated, and the rough surface and smooth surface shall be treated separately. The copper foil supplier said that the three-step method for rough surface treatment is as follows:

1. Several small bumps are formed on the rough surface through copper plating roughening treatment. Then through electroplating and curing, a layer of copper is plated on these small bumps to seal and improve the adhesion with rough surfaces.

2. Plating a thin layer of single metal or binary or ternary alloy, such as zinc, zinc nickel alloy and zinc cobalt alloy, on the rough layer to establish a heat-resistant passivation layer.

3. Spray organic matter on the passivation layer to form a coupling layer.

After the above process, the adhesive knife, heat resistance, drug resistance and other characteristics with the resin substrate can meet the standards. The principle of wool foil smooth surface treatment is to coat one or more metals or alloys on the smooth surface, so that the light surface has heat resistance, solder wettability, corrosion resistance and resin dust resistance.