Pcba defect Solution

Many processes are involved in the pcba process, and each process may have quality defects. These quality problems always involve many aspects and are difficult to solve. Due to the causes of the problems, some belong to chemistry, machinery, plates, Optics and so on. After decades of production practice, combined with the practical experience in solving quality and relevant materials on solving technical problems, the following is a summary:

Pcba Process Defects, causes and solutions

Solution to Process Defects
Board Film Board mask layer floating bubble PCB Board surface is not clean check board surface is runability that is clean surface energy to keep water uniform, continuous water film for up to 1 minute
Film Temperature and Pressure are too low to increase the temperature and pressure
When the edge of the film is tilted, the tension of the film is too high, resulting in poor adhesion of the film to adjust pressure screws.
Poor contact between the film layer and PCB Board, locking Pressure Screw
Poor photo exposure ability due to scattered light and reflected light shooting to film mask reduce exposure time
Over-exposure reduces exposure time
Image yin and yang difference; low sensitivity makes the minimum yin and yang difference ratio 3:1
Negative contact with PCB Board inspection Vacuum System
Adjust the light intensity after adjustment.
Overheated inspection Cooling System
Intermittent continuous exposure
Dry Film storage conditions are not good in yellow light
The development area has insufficient scum, which causes the colorless film to slow down on the PCB Surface and increase the development time.
The content of the photo display liquid is too low to reach 1.5 ~ 2% sodium carbonate
There are too many replicas in the photo liquid.
The interval between development and cleaning must not exceed 10 minutes.
Insufficient injection pressure on the display liquid to clean the filter and check the nozzle
Over-correction of exposure time
The maximum to minimum sensitivity ratio should not be less than 3.
The film layer is discolored, and the surface is not bright and exposed. As a result, the film polymerization function does not fully increase the exposure and drying time.
Excessive development reduces development time, compares positive temperature and cooling system, and checks the display liquid content
Film layer from the PCB Surface due to lack of exposure or excessive development, so that the film is not attached to increase the exposure time, reduce the development time and content
Non-clean surface check surface softening
After the film is exposed, it stays at least 15 ~ 30 minutes
Circuit diagram is replaced with a dry rubber film
Exposure insufficiency increases exposure time
Negative surface not clean check negative quality
Improper adjustment of the display Liquid Composition
The development speed is adjusted too fast