2023-06-02 14:11:45
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Negative film of PCB circuit board Usually, the solution used in the negative film process is an acid-base corrosion process. After the film is made, the required path or copper surface is completely transparent, while the unnecessary part is black. After route process exposure, because the dry film inhibitor is exposed to ultraviolet light, the completely transparent part will be chemically hardened, but the following development process will not make the film hard, and the dry film will be washed away. Therefore, in the etching process, only the copper deposition of the dry film is washed away (the black part of the negative film), but the preserved dry film is not washed away. This is the PCB circuit board (the transparent part of the negative film) we want.
Positive film of circuit board Usually the positive process is based on alkaline etching process. On the film, the required path or copper surface is black, while the unnecessary part is completely transparent. Similarly, after the route process exposure, the completely transparent part is hardened by the chemical action of the dry film blocker exposed to ultraviolet rays, and the subsequent development process will wash away the dry film of the non-hard substrate in the next process. We use alkaline solution to cut off the copper surface (transparent part of the negative film) without tin and lead maintenance, leaving the PCB (black film) part. Difference between positive film and negative film of PCB circuit board ① screen printing screen (negative film), working film, positive film and negative film and film surface are distinguished: screen printing screen has mother film and working film (sub-film), black and yellow film, positive film and negative film; ② Negative film is also called black film and carbon negative film. However, the working film is not only yellow film, but also black film to make the workpiece. It is mainly used to manufacture high-precision HDI board or save cost, and it is used to produce and manufacture PCB circuit board in large quantities at one time in small batch production. ③ When the surface of the film is different, the bright side of the black film is the film, but the yellow film is the opposite. Generally speaking, it can be seen that the side is based on the film surface of the graffiti pen or cutter head on screen printing. ④ Precautions for yellow film application: There are smooth and matte surfaces, and the second application is prone to oil surface indentation. ⑤ The negative film (containing copper) that transmits light on the film circuit is the positive film; The positive film is used in graphic electroplating process, with the path of developer dripping, the remaining effect is corrosion-resistant electroplating process, and the key inlays are lead and tin. Film is usually used in the instant etching process, and the corrosion resistance after developer is the way, while acid-base etching solution is used for the instant etching process. Shenzhen Qinji Electronics Co., Ltd. is a large, medium and small batch PCB manufacturer. It has been focusing on the production of FR4 single-sided circuit board, double-sided circuit board, multi-layered PCB, metal substrate, HDI board, soft board, soft and hard combination board, special process board and semiconductor test interface board for many years, and is committed to building an excellent team with "leading technology, quick response and continuous innovation" to serve the sustainable development of electronic technology.
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