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There are many processes involved in the production process of PCB circuit boards, and quality defects may occur in each process. These quality always involve many aspects, which is more troublesome to solve. Because the causes of problems are many, some are chemical, Machinery, sheet metal, optics, etc. After decades of production practice, combined with the practical experience in solving quality and the corresponding information about solving PCB technical problems, the summary is as follows:
Defects, causes and solutions in the circuit board production process
Process Defects Causes Solutions
Film There are bubbles on the surface of the board. The surface is not clean. Check the wettability of the board, that is, the clean surface can keep the water even, and the continuous water film can last up to 1 minute.
The temperature and pressure of the film are too low. Increase the temperature and pressure
The edge of the film layer is raised. The film layer has too much tension, resulting in poor film adhesion. Adjust the pressure screw
The film creases Poor contact between the film and the board. Tighten the pressure screw
Exposure, poor resolution ability, due to scattered light and reflected light reaching the area covered by the film, reducing the exposure time
Overexposure Reduce exposure time
Image Yin-yang difference; sensitivity is too low so that the minimum Yin-yang difference ratio is 3:1
Poor contact between the film and the board surface Check the vacuum system
The light intensity is insufficient after adjustment, then adjust
Overheating Check the cooling system
Intermittent exposure Continuous exposure
Dry film storage conditions are not good, working under yellow light
Development There is scum on the developing area. Insufficient development, resulting in the colorless film remaining on the board. Decelerate and increase development time
The developer composition is too low Adjust the content to reach 1.5-2% sodium carbonate
The developer contains too much film. Replace
Development and cleaning interval is too long, not more than 10 minutes
Insufficient developer spray pressure. Clean the filter and check the nozzle
Overexposure Correct the exposure time
Improper sensitivity The ratio of maximum to minimum sensitivity should not be less than 3
The film layer is discolored, and the surface is not bright. Insufficient exposure, resulting in insufficient film polymerization. Increase the exposure and drying time
Over development Reduce the development time, correct the temperature and cooling system, and check the developer content
The film layer falls off the board surface. The film layer is not firmly attached due to insufficient exposure or overdevelopment. Increase the exposure time, reduce the development time and correct the content
PCB surface is not clean Check surface wettability
After the film is exposed, go to the development immediately. After the film is exposed, stay for at least 15-30 minutes
There is excess glue on the circuit pattern. The dry film is out of date. Replace
Underexposure Increase exposure time
The surface of the film is not clean Check the quality of the film
Improper developer composition, adjust
Development speed is too fast, adjust
