PCB News - The etching problem and repair of the front/rear edge of PCB board

Regarding the upper and lower PCB board surfaces, The problem and maintenance of the different etching states of the leading edge and the trailing edge

A large number of problems related to etching quality are concentrated on the etched part of the upper plate surface. It is very important to understand this. These problems come from the influence of the glue-like clumps produced by the etchant on the upper surface of the printed circuit board. The accumulation of colloidal slabstock on the copper surface affects the spraying force on the one hand, and on the other hand prevents the replenishment of fresh etching solution, resulting in a decrease in the etching speed. It is precisely because of the formation and accumulation of colloidal slabs that the degree of etching of the upper and lower patterns of the board is different. This also makes the first part of the board in the etching machine easy to be etched completely or to cause over-corrosion, because the accumulation has not yet formed at that time, and the etching speed is faster. On the contrary, the part that enters behind the board has already formed when it enters, and slows down its etching speed.

Maintenance of etching equipment

The key factor in the maintenance of etching equipment is to ensure that the nozzle is clean and free of obstructions to make the spray smooth. Blockages or slagging will impact the layout under the action of jet pressure. If the nozzle is not clean, it will cause uneven etching and scrap the entire PCB. Obviously, equipment maintenance is the replacement of damaged and worn parts, including replacement of nozzles. The nozzles also have the problem of wear. In addition, the more critical issue is to keep the etching machine free of slagging. In many cases, slagging will accumulate. Excessive slagging will even affect the chemical balance of the etching solution. Similarly, if there is excessive chemical imbalance in the etching solution, slagging will become more serious. The problem of slag accumulation cannot be overemphasized. Once a large amount of slagging occurs suddenly in the etching solution, it is usually a signal that there is a problem with the balance of the solution. This should be done with strong hydrochloric acid for proper cleaning or supplementation of the solution.

residual film can also produce slagging, a very small amount of residual film dissolves in the etching solution, and then forms copper salt precipitation. The slagging formed by the residual film indicates that the previous film removal process is not complete. Poor film removal is often the result of edge film and over-plating.

The above is an introduction to the problems and maintenance of the upper and lower board surfaces, the leading edge and the trailing edge etching state are different, Ipcb also provides PCB manufacturers and PCB manufacturing technology