Machining process of metal holes

The invention discloses a machining process of metal holes. The process includes: drilling a series of holes on a PCB (printed circuit board), sinking metal to drilled holes while adhering films to protect the outer layer of a non-pattern area without drilled holes, and thickening and electro-plating metal to holes and the PCB; tinning a pattern area, with drilled holes, of the PCB for protection, and machining appearance of the tin-protected metal holes to form wave holes while metal burr at orifices of the wave holes formed on a metal hole feeding path is not processed; removing films adhered to the non-pattern area of the PCB, using alkaline etching solution to etch metal electro-plated on the surface of the non-pattern area, and using another etching solution to etch tin plated on the surface of the wave holes; The burr formed during metal hole machining needs no grinding, so that production efficiency is improved, product scrapping caused by burr grinding can be avoided, and one-step yield of the product