Analysis of the cause of circuit board failure
In the PCB processing process, it is inevitable that there will be defective products, which may be caused by machine errors, or may be caused by human factors. For example, there may be an abnormal situation called a hole breaking state, and the cause should be analyzed in detail.
If the hole breaking state is a point-like distribution rather than a complete circle breaking phenomenon, it is called a point-shaped hole breaking, and some people call it a "wedge hole breaking", which is often caused by poor processing of the desmear process. In the PCB processing, the desmear process is first treated with a leavening agent, followed by a strong oxidizing agent "permanganate", which removes the dross and creates a microporous structure. The oxidant remaining after the removal process is removed by a reducing agent, and the typical formulation is treated with an acidic liquid.
Since the residue is not seen again after the treatment of the slag, the monitoring of the reducing acid is often neglected, which may leave the oxidant on the wall of the hole. After the board enters the chemical copper process, the board will be micro-etched after the pore treatment, and the residual oxidant is again soaked by acid to peel off the resin in the residual oxidant zone, which is also equivalent to destroying the pore former.
The damaged pore walls will not react in the subsequent palladium colloid and chemical copper treatment, and these regions show no copper precipitation. The foundation is not established, and the electroplated copper will of course not be completely covered and the dot-shaped holes will be broken. This type of problem has occurred in many circuit board factories during the processing of the board. It is important to note that the syrup monitoring step of the slag removal process should be improved.(Mobile Phone PCB supplier china )
Every part of the PCB processing process needs to be strictly controlled, because the chemical reaction sometimes happens slowly in the inadvertent corner, thus destroying the entire circuit. This hole must be vigilant.