| 摘要 |
PURPOSE:To reduce variation per hr of etching and washing property by a method wherein solution is added to the same component as vapored and vanished component at equal addition rate in accorance with reduction volume of solution in an etching device or a wet processing e.g. a washing and previous processing device. CONSTITUTION:An air operation valve 8 is opened to add fresh water since the surface of liquid is lowered at the time when heat phosphoric acid heated up to constant temperature at a heater 7. The flow rate of fresh water is adjsuted by a needle valve 9 and is subjected to be equal equivalently to vaporization volume of water. Fresh water is supplied to a tank 11 from a supply source 10 and the flow rate is adjusted by a needle valve 12. An overflow-drain 13 is provided in the tank 11 and if fresh water is filled above constant level, fresh water comes to be flown from the base. The level 14 of heat phosphoric acid rises up gradually by addition of fresh water and ths air operation valve 8 is closed at the time of getting to the position of the least upper bound level sensor 6, and the said valve 8 is opened at the time of falling to the position of the greatest lowerbound level sensor 15. |
