In the etching machine process, in addition to the overall etching method without any anti-corrosion treatment, it is necessary to pay attention to the “spread” problem of etching under the anti-corrosion layer, which is what we often call side corrosion. The size of the side corrosion is directly related to the accuracy of the graphics and the limit size of the etching lines. Generally, the horizontal etching width A under the anti-corrosion layer is called the side etching amount, and the ratio of the side etching amount A to the etching depth H is the side etching rate F:
Introduction to the accuracy of etching and side etching problems
F=A/H where: A is the side etching amount (mm), H is the etching depth (mm); F is the side etching rate or corrosion factor, used to express the relationship between the side etching amount and the etching depth under different conditions .
The size of the above-mentioned arc R is greatly affected by the etching depth, the ratio of the minimum width of the etched window to the etching depth, the composition of the etching solution, the etching method, and the type of material. The amount of side etching determines the accuracy of chemical etching. The smaller the amount of side etching, the higher the processing accuracy and the wider the applicable range. On the contrary, the processing accuracy is low and the applicable range is small.
The amount of side erosion is mainly affected by metal materials. Among several commonly used metal materials, copper has the smallest amount of side erosion, and aluminum has the largest amount of side erosion. Choosing a more superior etchant, although the increase in the etching speed is not obvious, it can indeed improve the amount of side etching in the metal etching process.