DEVICE FOR PLATING MAGNETIC DISK SUBSTRATE

PURPOSE:To improve the characteristic of a magnetic disk by segmenting a plating bath into at least three baths, causing an Ni-P alloy plating liquid to overflow from the pre-stage bath to the post-stage bath and suctioning the liquid from the last-stage bath to a circulating pipe. CONSTITUTION:Two kinds of filters for a plating for filtering liquid are inserted in series on the way of the circulating pipe 8, the pre-stage desc filter 9 removes particles of 1mum or over in the plating liquid and the membrane filter 10 removes the particles of 0.2mum or over succeedingly. The plating liquid is circulated at the high speed of 15 times/hr or over. A heater 5 for heating plating liquid is provided to the pre-stage tank. The plating liquid circulated to the pre-stage bath through circulation flows along with the heater while being heated and overflows from the upper part of the bath to the middle stage bath. Since the N2 gas flowing externally is bubbled from the lower side of the heater 5, the plating liquid does not stay in the vicinity of the heater 5, the deterioration of liquid is prevented and the quality of product is improved.