Dry film hole masking method for PTH long slotted hole

Abstract

The invention belongs to the technical field of manufacturing of printed circuit boards. The invention provides a dry film hole masking method for a PTH long slotted hole. The dry film hole masking method comprises the following steps of pressing of a conventional multilayer board, outer layer drilling, CNC groove milling, board electroplating and grinding, copper deposition, VCP primary copper plating, line board grinding, dry film pasting, LDI exposure, development, line inspection, acid etching and inspection. In the CNC groove milling process, cold punching plates are additionally arrangedon the upper face and the lower face of the PCB, and the burr height is controlled. According to the method, the dry film mask hole quality of the 4.0*50.0 mm PTH long groove can be stably and efficiently ensured, so that the processing requirement of acid etching is met.

Description

technical field [0001] The invention belongs to the technical field of manufacturing printed circuit boards, and in particular relates to a dry film masking method for PTH long slots. Background technique [0002] PCB circuit molding usually needs to go through an etching process. At present, the etching process is mainly alkaline etching and acid etching. Compared with the two processes, there are mainly the following quality differences: [0003] 1. Alkaline etching requires a resist layer before etching. Affected by the pattern distribution, it is easy to have uneven plating, and there is a pattern of thin film in the fine pitch, and the quality is unstable. In addition, the alkaline etching process has a large amount of side erosion, which is not conducive to fine lines Production, so it is generally used for relatively simple PCB processing. [0004] 2. Acid etching, copper plating on the whole board before etching + dry film masking protection, because it is not aff...

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Problems solved by technology

[0006] The acid etching process is simple, the etching precision is high, and the product yield is high. However, the acid etching process is greatly affected by the masking ability of the dry film. Usually, it can only meet the masking etching of 5.0mm PTH round holes. For PTH circles ≥ 5.0mm For holes or slots with a size ≥ 3.0X10.0mm, the masking ability is relatively weak, and the defect of film rupture is prone to occur, resulting in scrapped etching. Therefore, the dry film masking ability of the slots needs to be further improved