PCB Tech - Causes and improvement methods of open circuits in PCB multilayer circuit boards

Causes and improvement methods of open circuits in PCB multilayer circuit boards

The reason for the open circuit of the PCB multilayer circuit board and the improvement method. Why is the circuit board open?

How to improve? PCB multi-layer board/multi-layer circuit board circuit open circuit and short circuit are almost daily problems encountered by PCB multi-layer circuit board manufacturers. These problems have been plagued by production and quality management personnel. Problems caused by insufficient quantity of goods (such as replenishment, delayed delivery and customer complaints) are relatively difficult to solve. I have more than 10 years of working experience in circuit board manufacturing, mainly engaged in production management, quality management, process management and cost control. We have accumulated some experience in improving the open circuit and short circuit of the printed circuit board. Now we have written a summary of the discussion about circuit board manufacturing. I hope it can be used as a reference for colleagues engaged in production and quality management.

First of all, the Electronics Co., Ltd. summarized the main reasons for the open circuit of some PCB multilayer circuit boards as follows:

The reasons for the above phenomenon and the improvement methods are as follows:

Exposure substrate:

1. There are scratches before the copper clad laminated wiring board is stored.

2. The copper clad board was scratched during the punching process.

3. The copper clad laminate was scratched during transportation.

4. During the drilling process, the copper composite board was scratched by the drill bit.

5. The copper foil on the surface of the PCB multilayer circuit board is scratched when it passes through the horizontal machine.

6. When the copper foil is piled up after sinking, the surface is damaged due to improper operation.

Improve methods:

1. IQC must conduct spot checks before entering the warehouse to check whether there are scratches on the surface of the copper clad board. If so, contact the supplier in time and deal with it according to the actual situation.

2. Scratches caused by copper plate sinking or improper stacking operation after plating: When the plates are stacked together after sinking and plating, the weight is not small. When laying the board, the angle of the board is downward and there is gravitational acceleration, which forms a strong impact on the surface of the board, causing scratches on the surface of the board, and exposing the substrate.

3. The metal plate was scratched during transportation: When moving, the transmission lifted too many plates at a time, and the weight was too large. When moving, the board is not lifted, but dragged along with the trend, causing friction between the corners and the board surface, and scratching the board surface. When the board is put down, the surface of the PCB board is scratched due to the friction between the circuit board boards.

4. The copper clad board was scratched during the tapping process. The main reason is that there are hard and sharp objects on the surface of the working table of the tapping machine. When struck, the copper clad plate and sharp objects are scratched to form an exposed substrate. Therefore, before tapping, the surface of the workbench must be carefully cleaned to ensure that the surface of the workbench is not hard and sharp objects.

5. When 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, PCB proofing cannot hold the drill firmly, the drill cannot reach the top, which is less than the length of the drill set, and the height increased during the drilling process is not enough. When the machine moves At this time, the drill tip wipes the copper foil to form an exposed substrate. Answer: The fixture can be replaced by the number of fixture records or the degree of wear of the fixture. Clean the fixtures regularly according to the operating procedures to ensure that there are no impurities in the fixtures.

6. The production of FPC soft and hard board will be scratched when passing through the horizontal machine. The baffle of the grinder sometimes hits 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 while passing through the plate. Stainless steel drive shaft. Due to the damage of sharp objects, the surface of the copper plate is scratched and exposed when passing through the plate.