ETCHING LIQUID CONTROLLING APPARATUS

PURPOSE:To stabilize etching liquid by periodically measuring concentration of acid of a copper etching liquid to correct and control an output of chlorine ion electrode. CONSTITUTION:An ORP electrode 3 and chlorine ion electrode 4 are immersed in an etching liquid 2 and a hydrometer 6 and a thermometer 6 are provided to measure a specific gravity and temperature of the etching liquid 2. Outputs of these sensors are inputted to a comparator 8 and are compared with preset values. On the other hand, the sampling liquid from a sampler 10 is measured with a pH automatic titlator 11 for detecting concentration of acid. A compensating section 12 compares an output of the pH automatic titlator 11 with an output of the chlorine ion electrode to calculate a difference and outputs a compensated preset value to a comparator 8d. The pH automatic titlator 11 operates in the predetermined period and periodically repeats the calibrating operation of an output of the chlorine ion electrode. With an output of the comparator 8, a drive 13 operates a pump 15 to supply the supplemental liquid 14 to a tank la, in order to adjust temperature of the liquid 2 with a temperature controller 16.