Why is there an open circuit on the PCB? How to improve?
PCB open circuit and short circuit is a problem that every PCB manufacturer encounters almost every day, which has been plagued by production and quality management personnel. It is difficult for people in the industry to solve the problems caused by replenishment due to insufficient shipments, delays in delivery, and customer complaints. I have worked in the PCB manufacturing industry for more than 10 years, mainly engaged in production management, quality management, process management and cost control. I have accumulated some experience in the improvement of PCB open and short circuit problems, and now I have formed a text for summary for the discussion of PCB manufacturing of the colleagues, and look forward to the management of production and quality of the colleagues can be used as a reference.
We first summarize the main causes of PCB open circuit into the following aspects.
The reasons for the above phenomena and the improvement methods are listed as follows:
Open circuit caused by exposed substrate:
1. The copper clad laminate is scratched before it enters the warehouse.
2. The copper clad laminate is scratched during the cutting process.
3. The copper clad laminate is scratched by the drill tip when drilling.
4. The copper clad laminate is scratched during the transfer process.
5. The copper foil on the surface was scratched due to improper operation when stacking the boards after copper sinking.
6. The copper foil on the surface of the production board was scratched when it passed the leveling machine.
1. IQC must conduct random inspections of the copper clad laminates before entering the warehouse to check whether the surface of the board is scratched and exposed to the base material. If so, contact the supplier in time, and make appropriate treatments based on the actual situation.
2. The copper clad laminate is scratched during the cutting process, mainly because there are hard sharp objects on the cutting machine table. The friction between the copper clad laminate and the sharp objects causes the copper foil to scratch and expose the substrate during the opening. The countertop must be carefully cleaned before feeding to ensure that the countertop is smooth and free of hard and sharp objects.
3. The copper-clad laminate was scratched by the drill tip during drilling.
The main reason was that the spindle clamp nozzle was worn out, or there was debris in the clamp nozzle that was not cleaned, the PCB prototyping could not grasp the drill nozzle firmly, and the drill nozzle did not reach the top, but slightly longer than the length of the drill tip set, the height of the lifting is not enough when drilling, and the tip of the drill tip scratches the copper foil when the machine is moving, causing the phenomenon of exposing the base material.
A. The chuck can be replaced by the number of times recorded by the knife or according to the degree of wear of the chuck.
B. Clean the chuck regularly according to the operating regulations to ensure that there is no debris in the chuck.
4. The sheet was scratched during the transfer process.
A. The amount of the board lifted by the carrier at one time is too large and the weight is too large during the transportation; the board is not lifted during the transportation, but dragged along with the trend, causing the board corners and the board surface to rub against the board surface.
B. Since the board was not placed neatly when the board was put down, the board was pushed hard to rearrange it, causing friction between the board and the board and scratching the board surface.
5. Scratched due to improper operation when stacking the boards after copper sinking and full board plating.
After copper sinking and full-plate electroplating, when storing the board, because the boards are stacked together, when there is a certain amount, the weight is not small, and then when the board is put down, the angle of the board is downward and a gravitational acceleration is added, forming a strong impact force Impact on the board surface, causing the board surface to scratch the exposed substrate.
6. The production board is scratched when passing through the leveling machine.
A. The baffle of the plate grinder sometimes touches the surface of the plate, and the edge of the baffle is generally uneven and protruding from the utensils. The surface of the plate is scratched when passing the plate.
B, the stainless steel drive shaft is damaged into a sharp object, and the copper surface is scratched when the board is passed, and the base material is exposed.
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