During the processing of PCB circuit boards, an abnormal situation of hole breakage sometimes occurs. It may be caused by machine errors or human reasons. The specific situation needs to be analyzed in detail.
If the holes are distributed in a point-like manner instead of being broken in the entire circle, it is called "point-like hole breakage". The cause is caused by poor processing of the slag removal process.
When processing PCB circuit boards, the slag removal process will first include a leavening agent treatment, and then the strong oxidant "permanganate" erosion operation. This process will remove the slag and create a microporous structure.
The remaining oxidant after removing the slag must be removed again with a reducing agent, such as using a reducing acid solution.
Since no residual slag will be seen after slag treatment, monitoring of the reducing acid solution is often neglected, resulting in the possibility of oxidants remaining on the hole walls. Afterwards, the circuit board manufacturing process enters the chemical copper manufacturing process. After being treated with the pore shaping agent, the circuit board will undergo micro-etching. At this time, the residual oxidant is soaked by acid again, causing the resin in the residual oxidant area to peel off, which is equivalent to removing the pore shaping agent. destroy.
The damaged hole walls will not react in the subsequent palladium colloid and chemical copper treatments, and these areas will show no copper precipitation, resulting in "point-like hole breaks" due to the inability of the electroplated copper to be completely covered. To solve this kind of problem, we must pay more attention to the slag removal process and strengthen the monitoring of the reducing acid solution.
In short, we need to strictly control every aspect of the PCB circuit board processing process, because chemical reactions often occur slowly in corners where we are not paying attention, thus destroying the entire circuit. Therefore, everyone should be alert to this kind of hole condition.