| 摘要 |
PROBLEM TO BE SOLVED: To control the etch rate of an etchant precisely by stably measuring the ion concentration of the etchant which changes continuously. SOLUTION: An etchant bath 2 is provided with a first sub liquid bath 4 which communicates with the etchant bath 2 at all times, and also with a second and a third sub liquid bath 6 and 8 which are connected to the etchant bath 2 via valves 15 and 20. Each of the sub liquid baths 4, 6, and 8 is provided with an ion concentration measuring device 26. The ion concentration obtained by the first sub liquid bath 4 is compared with that obtained by the second sub liquid bath 6. When the two ion concentrations do not match, the ion concentration is compared with that obtained by the third sub liquid bath 8. A correct ion concentration is obtained by these comparing operations, to correctly control the ion concentration of the etchant in the etchant bath 2. Consequently, the etch rate of a material to be etched can be precisely controlled, stabilizing the displaying performance of a liquid crystal display manufactured by this etching equipment.
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