In the process of PCB board making, it is inevitable to encounter several defective products, which may be caused by machine errors or human factors. For example, sometimes there will be an abnormal situation called hole breakage. The causes should be analyzed in detail.
If the hole breaking state is the phenomenon of point distribution rather than whole circle breaking, it is called point hole breaking, and some people call it "wedge type hole breaking". The common cause is the poor treatment of the degumming residue process. In PCB board making, the process of removing glue residue will be treated with leavening agent first, and then eroded by strong oxidant "permanganate". This process will remove the glue residue and produce microporous structure. After the removal process, the residual oxidant is removed by reducing agent, and the typical formula is acid liquid treatment.
Due to the fact that there is no glue residue after the treatment of the glue residue, the monitoring of the reducing acid solution is often ignored, which may leave the oxidant on the pore wall. After that, the circuit board enters the chemical copper process. After being treated with the pore forming agent, the circuit board will be micro etched. At this time, the residual oxidant is soaked in acid again and the resin in the residual oxidant area will peel off, which is equivalent to destroying the pore forming agent.
The damaged pore wall will not react with the subsequent treatment of palladium colloid and chemical copper, and there will be no copper precipitation in these areas. If the foundation is not established, the electroplated copper will not be able to cover completely and produce point like holes. This kind of problem has occurred in many PCB factories duing making printed circuit boards. It should be improved by paying more attention to the reduction step in the process of removing glue residue.
Every link in the PCB manufacturing process needs to be strictly controlled, because sometimes chemical reactions will occur slowly in the corners we don't pay attention to, thus destroying the whole circuit. We should be on guard against this kind of broken state.