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In the production process of the printed circuit board, after the outer circuit is completed, the circuit must be protected against soldering to prevent the outer circuit from oxidizing or soldering short-circuit. Some friends are not very clear about the meaning of the circuit board soldering and its process The process and function, the following editor will talk about it in detail.
Introduction to PCB solder mask
The solder mask is to print paint on the large layout surface of the PCB. After simple baking, press the corresponding plug-in position to expose and wash away the unnecessary parts. The printed text is convenient for plug-ins and subsequent maintenance. It is one of the processes in the printed circuit board, which protects the etched circuit of the circuit board, and the front process is the layout.
Chinese name: Anti-welding
English name: SolderMask
Other names: green paint, green oil
Process flow of anti-welding:
1. Pretreatment removes oxidation and oil stains to prevent pollution
2, electrostatic spraying (SprayCoating) or semi-automatic printing machine printing
3. Precure is the initial curing of the paint in the previous process
4, Exposure (Exposure) Use the photosensitive characteristics of the ink. Perform image transfer through the negative film, and irradiate the area where the ink needs to be retained with strong light, so that it can be hardened and firmly adhered to the board surface
5. Develop (Develop) Use sodium carbonate to wash off the ink that has not been hardened during exposure.
6. Post Cure needs to be further cured after the liquid ink is developed to enhance its solder resistance
7, Printing of Legend (Printing of Legend) facilitates loading and maintenance
8, UV curing (UV Cure) uses high temperature to dry the moisture of the text and ink to make it firmly adhere to the board surface
The role of solder mask:
1. Prevent chemicals from harming the circuit.
2. Maintain good insulation on the board.
3. Prevent oxidation and the harm of various electrolytes, which is conducive to post-process operations.
4. The text is used to mark the location of parts; it is convenient for customers to plug-in; it is convenient for maintenance.
5. Cover the substrate between the lines to prevent short circuits between the lines.
6. Cover all the conductive lines that do not need to be soldered to prevent the copper layer from being oxidized, and short-circuit the conductive lines during the surface treatment process.
7. When performing reflow soldering, wave soldering, and manual soldering on the client side, prevent short circuits between conductive circuits and solder pads.
