1. Curing treatment: deposit a layer of dense metal copper in the nodular particle gap of the roughening layer, increase the contact surface between the roughening layer and the wool foil substrate, and reduce the roughness of the roughening layer surface. Microscopically, after roughening the rough surface of the copper foil, the surface of the foil is uneven and undulating greatly, while the surface of the copper foil after curing treatment is relatively flat. After curing treatment, although the roughness is reduced, the bonding strength between the treatment layer and the insulating substrate material is improved due to the increased contact area between the roughened layer and the wool foil, which fundamentally eliminates the delamination between the treatment layer and the wool foil.

2. Galvanizing barrier layer: After the rough surface of the copper foil is galvanized, a barrier layer is formed to improve the oxidation resistance of the copper foil in the natural air. The appearance of the copper foil after galvanizing will look gray. After a period of storage, the gray color will turn into copper yellow. The more zinc is plated, the more yellow the copper foil will be.

3. Surface passivation: After the barrier layer is plated, the copper foil is passivated with chromate (or chromate and zinc salt) solution (i.e., anti oxidation treatment) to form a complex film with chromium (or chromium zinc) as the main body on the surface of the copper foil, so that the copper foil will not be oxidized and discolored due to direct contact with the air, and at the same time, the heat resistance of the copper foil is improved (higher zinc content, better heat resistance), The storage period of copper foil can reach 3 months.

4. Silane coupling agent treatment: after anti oxidation treatment, the surface is sprayed with silane, which can improve the oxidation resistance of copper foil at room temperature on the one hand; On the other hand, in high temperature pressing plate, silane can better combine copper foil and resin substrate through coupling, and improve peel strength. Post treatment process - drying. In order to prevent residual moisture from harming the copper foil, it must be dried at a temperature not lower than 100 ℃, and the drying temperature cannot be too high.