PCB Tech - The reason and improvement method of pcb circuit board open circuit

We first summarize the main reasons for the open circuit of the PCB circuit board into the following aspects:

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

Exposure of the base material causes an open circuit of the PCB circuit board:

1. There are scratches before the copper clad laminate is put into the warehouse;

2. The copper clad laminate is scratched during the cutting process;

3. The copper clad laminate is scratched by the drill tip during drilling;

4. The copper clad laminate is scratched during the transfer process;

5. The copper foil on the surface was bumped due to improper operation when stacking the boards after copper sinking;

6. The copper foil on the surface of the production board is scratched when it passes through the leveling machine.

Improve methods:

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 there is, contact the supplier in time, and make appropriate treatment according to the actual situation.

2.The copper clad laminate is scratched during the opening 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 be scratched and the substrate is exposed. It is necessary to carefully clean the countertop 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 nozzle 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, and the PCB circuit board was not firmly grasped when the drill nozzle was grasped, and the drill nozzle was not up. To the top, it is slightly longer than the set length of the drill tip, and the lifting height is not enough when drilling. When the machine tool moves, the tip of the drill tip scratches the copper foil and exposes 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 PCB circuit boards lifted by the carrier at one time are too heavy and too heavy. 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. Because the board was not placed neatly when the board was put down, the board was pushed hard in order to rearrange it, which caused friction between the board and the board and scratched the board surface.

5. Scratched due to improper operation when stacking the board 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. When the board is put down, the angle of the board is downward and a gravity 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 stainless steel drive shaft is damaged into a sharp object, and the copper surface is scratched when passing the board, and the base material is exposed.

b. The baffle of the plate grinder sometimes touches the surface of the PCB circuit board, and the edge of the baffle is generally uneven and has beneficial objects raised, and the board surface is scratched when passing the board;