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Reasons for open circuit on PCB and improvement methods
PCB circuit open and short circuit is a problem that PCB manufacturers encounter on an almost daily basis, and has always plagued production and quality management personnel. It is caused by the lack of shipments and the lack of shipments, delivery delays, and customer complaints. Difficult to solve the problem. I have more than 20 years of working experience in the PCB manufacturing industry. I mainly work in production management, quality management, process management and cost control. We have accumulated some experience in the improvement of PCB opening and short circuit problems. Now we have formed a text to summarize and discuss with our peers on PCB manufacturing. We look forward to the management and production and quality of our colleagues as a reference.

We first categorize the main causes of PCB open circuit as follows:

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

First, open circuit caused by exposed substrate:

1. There is scratching before the CCL is placed in the warehouse;

2. The copper-clad laminate was scratched during the opening process;

3. CCL is scratched by drilling nozzle during drilling;

4. CCL is scratched during the transfer process;

5, after the sinking of copper piled on the board due to improper operation caused the surface copper foil was bruised;

6. The surface copper foil is scratched when the production board is over horizontal.

Improve methods: 

1. The IQC of the CCL must be sampled before entering the warehouse to check if there is any scratched substrate on the board surface. If there is any problem, contact the supplier in time and make appropriate treatment according to the actual situation.

2. The copper-clad laminate is scratched during the process of blanking. The main reason is that there are hard tools on the surface of the material-feeding machine. When the materials are opened, the copper-clad laminates and the frictional materials cause the copper foil to scratch and form the exposed substrate. Before the material, the countertop must be carefully cleaned to ensure that the countertop is smooth and free of hard objects.

3. CCL is scratched by a drill nozzle during drilling. The main reason is that the spindle clamp nozzle is worn out, or there are debris in the clamp nozzle is not clean, the PCB is not grasped when the PCB is drilled, and the drill nozzle is not on the top. The length of the drilling nozzle is slightly longer than that of the set drill hole. The raised height of the drill hole is not enough. When the machine tool moves, the tip of the drill bit scratches the copper foil to form the exposed substrate.

a, can be replaced by the number of times the knife record or according to the degree of wear of the clip, to change the clip Tsui;

b. Periodically clean the clamps according to the operating procedures to ensure that there are no debris in the clamps.

4, the sheet was scratched during the transfer process:

a. The amount of plates lifted by the handling personnel at one time is too much and the weight is too large. The plates are not lifted when they are carried, but they are dragged by the trend and cause the plate corners to rub against the plate surface to scratch the plate surface;

b. When the board is put down, it is not put neatly. In order to rearrange the board, it is hard to push the board, causing friction between the board and the board and scratching the board surface.

5, after sinking copper, plated plate after the whole plate is improperly handled due to scratch:

When the plate is stored after electroplating after plating, the plates are stacked together. When the plate is stacked, the weight is not small. When the plate is lowered, the plate angle is downward and a gravitational acceleration is added to form a strong impact force. Impact on the board surface, resulting in scratches on the board surface exposed substrate.

6, the production board was scratched when crossing the level machine:

a. The baffle of the plate mill may sometimes come into contact with the surface of the plate. The edges of the baffle are generally not even and the objects are convex. When the plate is over, the plate surface is scratched.

b. Stainless steel drive shaft, due to damage to sharp objects, scratches the copper surface and exposes the substrate when the board is over.