1. Process half of the hole with a double V-shaped cutting tool.

2. Second drill adds support holes at the edge of the hole, removes copper skin in advance, reduces burrs, and uses slot cutters to produce the drill, optimizing the speed and falling speed.

3. Copper plating is applied to the substrate by depositing a layer of copper on the hole wall of the circular holes on the edge of the board.

4. After laminating, exposing, and developing the outer circuit, the substrate is subjected to secondary copper plating and tin plating to thicken the copper layer on the hole wall of the circular hole at the edge of the board and cover it with a tin layer with anti-corrosion properties;

5. Half hole forming involves cutting the circular holes on the edge of the board in half to form a half hole;

6. Remove the anti electroplating film pressed during the process of film removal and pressing;

7. Etching is performed on the substrate to remove the exposed copper on the outer layer of the substrate after film removal;

8. Tin stripping is performed on the substrate to remove the tin on the half hole wall and expose the copper layer on the half hole wall.

9. After molding, use red tape to stick the unit boards together and remove burrs through alkaline etching lines

10. After secondary copper plating and tin plating on the substrate, the circular holes on the edge of the board are cut in half to form half holes. Due to the tin layer covering the copper layer on the hole wall and the good connection between the copper layer on the hole wall and the copper layer on the outer layer of the substrate, the bonding force is strong, which can effectively prevent the copper layer on the hole wall from being pulled off or lifted during cutting;