Selective hole copper removing method for printed circuit board

Abstract

The invention provides a selective hole copper removing method for a printed circuit board. The selective hole copper removing method comprises a mechanical drilling step, to be specific, removing protective layers and / or weldable layers on hole copper surfaces of problem holes through mechanical drilling, and removing partial hole copper on the hole copper surfaces of the problem holes with partial hole copper left; a film bonding step, to be specific, bonding a dry film on the surface of a printed circuit board; a problem hole exposing step, to be specific, tearing off a PET (Polyethylene Glycol Terephthalate) protection film on the surface of the dry film, piercing the dry films at two ends on corresponding positions of the problem holes so as to expose the problem holes, wherein the problem holes are nonmetalized holes plated with the hole copper; an acid etching step, to be specific, completely removing the left partial hole copper of the problem holes through acid etching; a water washing and drying step, to be specific, carrying out water washing on a printed circuit board, and drying after water washing so as to remove chemical liquid left after the acid etching step; and a dry film removing step, to be specific, removing the dry film on the surface of the printed circuit board.

Description

technical field [0001] The invention relates to the field of printed circuit board manufacturing, and more specifically, the invention relates to a method for removing copper from selective holes of a printed circuit board. Background technique [0002] Plated Through Holes (Plated Through Holes, PTH) and Non-Plated Through Holes (No Plated Through Holes, NPTH) are two common types of through holes in printed circuit boards. Metallized holes. [0003] However, in the manufacture of printed circuit boards, due to errors in engineering data or process operations, etc., during the production process of printed circuit boards, some non-metallized holes may be mistakenly plated with copper on the holes. Moreover, for printed circuit boards that have undergone subsequent surface treatment, the misplated hole copper surface will be covered with other protective layers and / or solderable layers. [0004] In the prior art, in order to remove the hole copper in such problematic holes...

AI Technical Summary

Problems solved by technology

[0004] In the prior art, in order to remove the hole copper in such problematic holes, the hole copper and its surface protective layer and / or solderable layer can be removed at one time by mechanical hole expansion; however, for this method, only when Only by drilling a hole slightly larger than the original hole diameter at the problem hole can the copper layer on the hole wall be completely removed; that is, this method will increase the hole diameter of the non-metallized hole, affect the hole diameter accuracy, and even cause printing. Scrapping of printed circuit boards

[0005] Therefore, it is desirable to provide a method that can overcome the lack of aperture increase caused by the existing mechanical hole reaming method and realize the removal of the hole copper on the non-metallized hole of the printed circuit board.

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