Effect of Solution Components on Corrosion Rate of Etching Machine
(1) Effect of FeCl3 concentration on etching speed: With the increase of FeCl3 concentration in FeCl3 etching solution, the etching speed is accelerated. When the contained FeCl3 exceeds a certain concentration, the corrosion rate will decrease due to the increase of the viscosity of the etching machine solution. For copper parts using resist printing material or resist dry film, the concentration can be controlled at about 35° Baume; for copper parts using liquid photoresist (such as bone glue, polyvinyl alcohol, etc.). The concentration is controlled at around 42° Baume. Under normal circumstances, the concentration of the chemical solution in the chemical tank of the etching machine is preferably 350g/L-600g/L.
(2) The effect of the amount of hydrochloric acid added on the corrosion rate of Xinhengli etching machine: adding hydrochloric acid to the etching machine, one can inhibit the hydrolysis of FeCl3 and CuCl2; the other can increase the etching rate. Especially when the copper content in the etching solution reaches 37.4g/L, the effect of hydrochloric acid is more obvious. However, the appropriate acidity should be selected according to different resist materials. If the resist layer is selected from bone glue, gelatin, polyvinyl alcohol and other photoresist layers, the acidity should not be too high, otherwise, the resist layer will be easily damaged. . For photosensitive resin resists and screen printing resists, higher acidity can be selected.
(3) The influence of temperature on the etching rate: In the FeCl3 etching process, as the temperature increases, the corrosion rate of the workpiece in the etching machine is significantly accelerated. For example, at 50°C, the metal etching speed of copper in a new etching solution can reach 10 μm/min. However, in actual production, the normal temperature etching method is used. The etching of copper by FeCl3 is an exothermic reaction. As the etching progresses, the temperature of the liquid in the etching machine will gradually increase, and the etching speed will increase. With the consumption of FeCl3, the etching rate will also decrease. At the same time, this heating process is relatively slow, so the etching rate does not change much during the entire etching process.