Definition and avoidance methods of punctiform hole breakage in PCB circuit boards

Definition

Dot-shaped hole breakage is a defect that may occur during the PCB (Printed Circuit Board) processing. Its characteristic is that the state of the hole breakage shows a dot-shaped distribution rather than a phenomenon of a complete circular open circuit. This phenomenon is also known as wedge-shaped hole breakage. Dot-shaped hole breakage is usually caused by poor treatment in the desmear process. Especially after using strong oxidants such as permanganate for the etching operation, if the residual oxidant is not properly removed, it may lead to the peeling of the resin on the hole wall, which in turn affects the integrity of the electroplated copper and causes dot-shaped hole breakage.

Avoidance methods

To avoid the occurrence of punctiform hole breakage, the following aspects need to be noted:

1. Appropriate hole wall treatment: Ensure that the hole wall is properly treated, sufficiently activated, and the conductive film is uniformly and completely covered. This can improve the coverage rate of subsequent copper plating and reduce the occurrence of point-like hole breaks.

2. Monitor the reducing acid solution: In the desmear process, although no residual smears can be seen after the smear treatment, manufacturers should not neglect the monitoring of the reducing acid solution. The reducing acid solution is used to remove the residual oxidant. Insufficient monitoring may result in the oxidant remaining on the hole walls, thus causing punctiform hole breakage.

3. Strict process control: Every step in the PCB circuit board processing needs to be strictly controlled because chemical reactions may occur gradually in unnoticed corners, thus damaging the entire circuit. In particular, attention should be paid to the details in the desmear process and the electroless copper plating process to prevent oxidant residues and damage to the hole walls.

Through the above measures, the occurrence of dot-shaped hole breakage in PCB circuit boards can be effectively reduced or even avoided, ensuring the quality and reliability of the products.