PTH plating method of printed circuit boards

A plating through hole (PTH) plating method of a printed circuit board is provided to minimize the thickness of plating by removing a copper layer formed on both surfaces of a substrate through an etching process after processing the size of a hole with 10 um-20 um. A hole is processed on one side of a printed circuit board in which a copper layer, a polyimide (PI) layer, and a copper layer are successively laminated by radiating ultraviolet ray (UV) laser (S10). The copper layer is removed by performing an etching process on the printed circuit board (S20). A plating preprocessing process is performed in the inner side of a hole and on the upper and lower sides of the PI layer (S30). A copper plating processing is performed in the inner side of the hole and on the upper and lower sides of the printed circuit board (S40). Therefore, fine patterns can be favorably formed.