The Etching Process of The Outer Circuit of PCB (2)

There is a research result from the PCM industrial system, which has not yet been officially published, but the result will be refreshing. Because of the relatively strong project fund support, researchers have the ability to change the design ideas of the etching device in the long-term sense, and to study the effects of these changes at the same time. For example, compared with the conical nozzle, the best nozzle design uses a fan shape, and the spray manifold (that is, the pipe into which the nozzle is screwed) also has an installation angle, which can spray the workpiece in the etching chamber at 30 degrees. If such a change is not made, the installation method of the nozzles on the manifold will cause the spray angle of each adjacent nozzle to be not completely the same. The spray surfaces of the second group of nozzles are slightly different from those of the first group. In this way, the shapes of the sprayed solutions become superimposed or intersected. Theoretically, if the shapes of the solutions cross each other, the jetting force of this part will be reduced, and the old solution on the etched surface cannot be effectively washed away while keeping the new solution in contact with it. This situation is especially prominent at the edge of the spray surface. Its ejection force is much smaller than the vertical direction.

This study found that the latest design parameter is 65 pounds per square inch (ie 4+Bar). Every etching process and every practical solution has a problem of the best spray pressure, and at present, the spray pressure in the etching chamber reaches 30 pounds per square inch (2Bar) or more. There is a principle, that is, the higher the density (ie, specific gravity or glass degree) of an etching solution, the higher the optimal injection pressure should be. Of course this is not a single parameter. Another important parameter is the relative mobility (or mobility) that controls the reaction rate in the solution.

2. Maintenance of etching equipment

The most critical factor in the maintenance of etching equipment is to ensure that the nozzle is clean and free of obstructions to make the jet unobstructed. 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, which 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.