Analysis of the reasons for PCB open circuit

We first summarize the main reasons for the PCB open circuit as the following aspects:

The causes analysis and improvement methods that cause the above phenomena are listed below:

First, the exposed substrate causes the PCB to open:

1. There is scratch on the CCL before entering the warehouse;

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

3. The copper clad plate is scratched by the drill nozzle during drilling;

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

5. When the board is stacked after sinking copper, the surface copper foil is bumped due to improper operation;

6. When the production board is over the horizontal machine, the surface copper foil is scratched.

 Improve methods:

1. The copper-clad board must be inspected before the storage into the warehouse. Check whether the board surface has scratched base. If it is necessary, contact the supplier in time and make appropriate treatment according to the actual situation.

2. The copper clad plate is scratched during the cutting process. The main reason is that there is a hard object in the machine surface. When the copper plate and the sharp object are rubbed during the material opening, the copper foil is scratched to form the exposed substrate. The table top must be carefully cleaned before the material to ensure that the table surface is smooth and free of hard objects.

3. The copper clad plate is scratched by the drill bit during drilling. The main reason is that the spindle clamp is worn, or the debris in the clamp is not cleaned. The PCB is not caught when the drill is grasped. The drill is not up to the top. It is slightly longer than the length of the drilled hole, and the height raised during drilling is not enough. When the machine moves, the tip of the drill bit scratches the copper foil to form a base material.

a. The clip can be replaced by the number of times the knife is recorded or according to the degree of wear of the clip;

b. Clean the clamps regularly according to the operating procedures to ensure that there are no debris in the nozzles.

4. The board is scratched during the transfer process:

a. The amount of PCB circuit board lifted by the carrying personnel at one time during transportation is too large and the weight is too large. The board is not lifted during transportation, but is dragged up by the situation, causing the board angle and the board surface to rub and scratch the board surface;

b. When the board is lowered, it is not properly placed. In order to reorganize it, the board is forced to push the board, causing friction between the board and the board to scratch the board surface.

5, after sinking copper, the whole board is plated after plating, due to improper operation is scratched:

After the copper is deposited and the plate is plated after plating, since the plates are stacked together, when there is a certain amount, the weight is not small. When the plate is lowered, the plate angle is downward and a gravity acceleration is added to form a strong impact force. Impact on the surface of the board, causing the board surface to scratch the exposed substrate.

6. The production board is scratched when it passes the horizontal machine:

a. The baffle of the grinding machine sometimes touches the surface of the PCB board. The edge of the baffle is generally uneven and the object is convex, and the board surface is scratched when passing the board;

b. The stainless steel drive shaft is made into a pointed object due to damage. When the plate is passed, the copper surface is scratched to expose the substrate.