Dry film production process technology of PCB circuit board factory

Dry film production process technology of PCB circuit board factory

Circuit board factory dry film is to peel off the polyethylene protective film from the dry film, and then paste the dry film resist on the copper-clad copper foil of the PCB under the condition of heat and pressure. The resist layer in the dry film becomes soft after being heated, and the fluidity increases. The circuit board filming work is completed by the pressure of the hot pressing roller and the role of the adhesive in the resist. PCB board lamination is usually completed on a laminating machine. There are many types of circuit board laminating machines, but the basic structure is roughly the same. Generally, the film can be continuously pasted, or it can be a single piece of PCB board.

 In general, when making continuous film on a circuit board, pay attention to the alignment of the dry film on the upper and lower dry film feed rollers. The size of the general film should be slightly smaller than the surface of the PCB to prevent the resist from sticking to the heat roller. Continuous film production has high efficiency and is suitable for large-scale circuit board production and processing. The three factors to master when applying the film are pressure, temperature, and transfer speed. Pressure: For newly installed film laminating machines, firstly, the upper and lower hot-pressing rollers should be adjusted to be parallel to the axial direction, and then the pressure should be adjusted by gradually increasing the pressure. According to the thickness of the printed circuit board, adjust to make the dry film easy to stick and fasten. No wrinkles. Generally, the pressure can be fixed after being adjusted. If the thickness of the printed circuit board is too large, it needs to be adjusted. The general line pressure is 0.5-0.6 kg / cm. Temperature: It is slightly different according to the type, performance, ambient temperature and humidity of the dry film. If the film is dry and the ambient temperature is low and the humidity is low, the temperature of the film should be higher, otherwise it can be lower, and the dark room is good and stable. The good environment and equipment are a good guarantee for the film.

 Generally, if the temperature of the film is too high, the dry film image will become brittle, resulting in poor plating resistance, the temperature of the film is too low, and the dry film and the copper surface of the circuit board will not adhere firmly. During the development or plating process, the film is easily warped. Even fall off. Usually control the temperature of the film at about 100 ° C. Transmission speed: It is related to the temperature of the film. The temperature is high, and the transmission speed of the PCB board can be faster. If the temperature is low, the transmission speed is slowed down. Usually the transmission speed is 0.9 to 1.8 m / min.

 Generally, when mass-producing circuit boards, at the required transfer speed, it is difficult for the hot-pressing roller to provide enough heat. The PCB board to be laminated can be preheated, that is, the film can be pasted after being cooled in the oven after a little cooling. Or by slowing down the speed of the film.

 In order to adapt to the production of printed circuit boards with fine wires, a wet film lamination process has been developed. This process uses a special film laminator to form a layer of water film on the surface of the copper foil of the PCB before the film is dried. The function of the water film is to improve Dry film fluidity; removes air bubbles trapped on scratches, trachoma, pits, and fabric dents; in the process of heating and pressurizing film, water plays a role in thickening the photoresist, which can greatly improve the dry film Adhesion to the substrate improves the qualification rate of fine wires for circuit boards. It is reported that the fine wire qualification rate for processing circuit boards using this process can be increased by 1-9%.

 A good printed circuit board film should have a flat surface of the PCB, no wrinkles, no bubbles, and no dust particles. Note In order to maintain the stability of the process, the circuit board should be exposed for more than 15 minutes after the film is cooled and recovered.