The Difference between PCB Dry Film and Wet Film

Both the dry film and the wet film of the PCB refer to the raw materials used for the Circuit. The dry film is a kind of high-molecular compound. It generates a polymerization reaction after being irradiated with ultraviolet rays to form a stable substance attached to the surface of the plate, thereby achieving the functions of impedance plating and etching. The wet film is a blue viscous liquid synthesized from a photosensitive resin and is added with a sensitizer, a pigment, a filler, and a solvent.

The functions of the dry film and the wet film are basically similar. However, if the surface of the PCB is not flat and a very thin film thickness is required, the PCB manufacturers can consider using a wet film. Moreover, the cost of the wet film is much lower than that of the dry film, so that a large amount of cost can be saved. The wet film has a good filling ability, but does not protective film,  so high exposure energy is required.

If it is a perforated PCB, the dry film is more suitable and is easier to control the operation. The dry film is easy to handle, but its unit price is higher than the wet film. The dry film is advantageous in use because it is easy to keep clean and does not have to be baked and has good processability. However, for thinner films, especially dry films of thickness less than 15 μm are not easy to do.

In general, the PCB dry film is better than the wet film, convenient and stable. The downside is that it is only expensive. In addition to general considerations, the manufacturer's own operating environment needs should also be considered. Each customer has a different perspective on strengths and weaknesses. This must be based on the needs of the customer to arrive at a conclusion that is more suitable for them.