The open circuit and short circuit of PCB circuit boards are almost daily problems encountered by PCB printed circuit board manufacturers, which have been troubling production and quality management personnel. We have accumulated some experience in improving the open and short circuits of printed circuit boards. Now we have written a summary of the discussion on PCB manufacturing. I hope it can serve as a reference for colleagues engaged in production and quality management.
Firstly, we summarized the main reasons for open circuits in PCB circuit boards as follows:
The reasons and improvement methods for the above phenomenon are as follows:
Exposure substrate:
1. There are scratches on the copper clad laminate before it is stored.
2. The copper clad plate was scratched during the punching process.
During the drilling process, the copper composite plate was scratched by the drill bit.
4. The copper clad laminate was scratched during transportation.
5. When stacking copper foil after sinking, improper operation may cause surface damage.
6. The copper foil on the surface of the production board is scratched when passing through the horizontal machine.
Improvement method for open circuit of PCB circuit board:
Before entering the warehouse, IQC must conduct spot checks to check for scratches on the surface of the copper clad plate. If so, contact the supplier in a timely manner and handle it according to the actual situation.
2. The copper clad plate was scratched during the tapping process. The main reason is that there are hard and sharp objects on the surface of the tapping machine workbench. When struck, the copper clad plate and sharp objects are scratched to form an exposed substrate. Therefore, before tapping, it is necessary to carefully clean the surface of the workbench to ensure that it is not a hard or sharp object.
3. During drilling, the copper clad plate was scratched by the drill bit. The main reason is that the spindle clamp is worn, or some debris in the clamp is not clean, the PCB sample cannot firmly hold the drill bit, the drill bit cannot reach the top, is smaller than the length of the drill bit group, and the height added during the drilling process is not enough. When the machine tool moves, the drill tip wipes the copper foil to form an exposed substrate. Fixtures can be replaced by the number of times recorded by the fixture or the degree of wear of the fixture. Regularly clean the fixture according to the operating procedures to ensure that there are no impurities in the fixture.
4. The metal plate was scratched during transportation: When moving, the transmission lifted too many plates at once, and the weight was too large. When moving, the board is not lifted, but rather dragged along with the trend, causing friction between the corners and the surface of the board, and scraping the surface of the board. When the board is lowered, the surface of the board is scratched due to friction between the boards.
Scratches caused by improper sinking or stacking of copper plates after electroplating: When the plates are stacked together after sinking and electroplating, the weight is not small. When laying the plate, the angle of the plate is downward, and there is Gravitational acceleration, which forms a strong impact force on the surface of the plate and scratches on the surface of the plate, exposing the base material.
6. The production of soft and hard combination boards may scratch when passing through a horizontal machine. The baffle of the grinding machine sometimes touches the surface of the baffle. The edges of the baffle are usually uneven and sharp objects are lifted. The surface of the baffle was scratched when passing through the plate. Stainless steel transmission shaft. Due to damage from sharp objects, the surface of the copper plate generates scratches and exposure when passing through the plate.