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Home appliance circuit board uses exposure and developing technology to make PCB board

Shenzhen Inno Circuit Co.,Ltd | Updated: Jun 08, 2018

Home appliance circuit board uses exposure and developing technology to make PCB board

PCB pattern on the circuit board is the use of exposure imaging and developing etching process technology to complete the appliance circuit board factory, whether it is PCB multilayer flexible board or circuit board in the production of line graphics must use the exposure imaging and development process technology. To describe in detail the processing characteristics and processing principles of these two processes.

       Number of layers: 4 layers Thickness: 1.6mm Line width / spacing: 0.08mm/0.1mm Material: FR-4 Copper thickness: 1OZ Hole diameter: 0.1mm Process: Spray tin multilayer board production method generally from the inner layer graphics Doing and then printing or single-sided or double-sided substrate made by printing, and included in the specified layer, and then heated, pressurized and bonded, and the subsequent drilling is the same as double-sided plated through-hole method. These basic manufacturing methods did not change much with the methods dating back to the 1960s, but they have become more mature as materials and process technologies (such as press-bonding technology, the development of slag when drilling, improvement of film) have become more mature. The properties of the multilayer board are more diverse.

       1Exposure: Since the thickness of the dielectric layer on the substrate of coated PCB substrate is relatively thick, a relatively large exposure machine is required to expose the PCB. For example, a 7-kilowatt metal halide (such as a tungsten lamp) is used. The lamp is uplighted in an exposure machine with parallel (or reflected quasi-parallel light). The amount of light on the surface of the dried insulating dielectric layer should be between 200 and 250, and the exposure time can be adjusted and adjusted by the conditions such as the optical ladder scale test or the supplier's conditions. Generally, larger exposure and shorter time should be used. exposure. For the low power exposure machine, since the light energy is low and the exposure time is long, the light refraction, diffraction, and the like are exacerbated, which is disadvantageous for manufacturing fine pitch or high density interconnected vias.

       2 Development and cleaning: The conditions and conditions of the developing and cleaning conditions and the liquid photo-sensitive solder mask ink are similar. Pay attention to changes in sodium carbonate concentration and temperature in the developer, often adjust the development time (or transfer rate) or adjust the solution, which is related to the problem of pattern development on the PCB board.

       Curing (heat curing and UV curing). After being exposed and developed, the PCB circuit board of the home appliance circuit board factory is basically cured although it is cured by exposure to photochemistry (crosslinking). However, it is mostly incomplete. Add water absorbed by developing, cleaning, etc., so it is done by heating. On the one hand, water and solvent can be removed, and on the other hand, curing is mainly completed and deepened.

       However, thermal curing is mostly conducted using conductive heat. Therefore, the solidification progresses gradually from the surface to the inside, so that it is in a gradient-type curing state. However, since UV light has the property of penetrating substances, and also has the characteristic of strong absorption of UV light due to epoxy resin and the like, it has a strong photocross-linking reaction, so that the curing completely and thoroughly drives out organic solvent substances. Therefore, it is necessary to fully cure and completely remove the moisture and solvent as the insulation medium layer of the laminate board in order to achieve the expected Tg (glass fiber temperature) and dielectric constant requirements. Therefore, in the curing, most of the two steps of heat curing and then UV curing can be completely cured. The curing should be strictly controlled. The control time should be set according to the experiment and the test. If the PCB circuit board is over-cured or insufficiently cured, the performance of the product will be deteriorated and the roughness (pulling) will be changed. This will bring great quality risks to the electroplating process behind. After long-term practical experience is summarized, such as the circuit board manufacturers in the exposure and development process will have strict control of technical parameters.