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What are the classifications of dry film photoresists in pcba circuit boards?

date:2022-04-20 17:32:45

In the PCBA board manufactured by the pcba manufacturer, the dry film is divided into 3 types according to the development and film removal methods after exposure:

Solvent-based dry film with organic solvent as developer and film remover in pcba manufacturing board. It has good acid and alkali resistance and stable process, but requires special equipment and toxic organic solvents for development, which pollutes the environment and is gradually eliminated.

The water-soluble dry film in the pcba board includes two varieties: semi-water-soluble and fully water-soluble. The developer and remover of semi-water-soluble dry film are mainly water, and then add 2% to 15% of organic solvent. The cost is lower than that of solvent-based dry film, but a small amount of organic solvent is also required, which also pollutes the environment. Waste liquid Difficult to handle and not much used. The fully water-soluble dry film developer and film remover use alkaline aqueous solution, which has little pollution, easy disposal of waste liquid, and the lowest cost. It is currently the most used dry film.

Dry developable or peelable dry film. It does not require a developer. After exposure, the polyester film is peeled off together with the non-photosensitive part by using the difference in the adhesion between the photosensitive part and the non-photosensitive part on the polyester film and the copper surface of the printed board, leaving the required surface on the copper foil. resist image. This kind of dry film has strict requirements on the degree of sensitivity. When the sensitivity is insufficient, the difference in adhesion between the photosensitive and non-photosensitive parts is small, it is not easy to ensure the quality of the image, and the image resolution is not as good as that of the water-soluble dry film, so it is not used much.

The pcba factory is classified according to the purpose of use of the dry film. The dry film can also be divided into three types: anti-corrosion dry film, hole masking dry film and solder mask dry film. Dry resist film and hole mask dry film are used to make the pattern of the printed board, and the conductive pattern should be removed after completion. Solder mask dry film is used on the finished printed board to protect other parts except the pad, so as to prevent the solder from being soldered to the wires other than the pad or other places of the copper foil when soldering the components, and avoid the solder making the pad and the pad. Wire bridging and short-circuiting are permanent protective films on the printed board, which do not need to be removed after soldering. They can play a role in dustproof, mildew proof and certain moisture proof, and can improve the withstand voltage performance of the printed board surface. Due to the high cost of solder mask dry film and the need for special filming equipment, it is gradually replaced by liquid photosensitive solder resist that is simpler to use.



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