| 摘要 |
PROBLEM TO BE SOLVED: To keep the uniformity of a pit formation of a supporting body grain by a method wherein the supporting body has a double structure of large and small pits, and the large pit has a uniformity, and also, the average opening diameter of the small pit and a ratio of the depth and the opening diameter of the small pit are specified. SOLUTION: As a first surface roughening, a roughening is performed in such a manner that the cycle of an unevenness may become 3-6μm. Then, as an alkaline surface melting treatment (1), by melting the surface by 3.0-10.0 g/m<2> , the sharp shape formed by the first roughening is molten, and a structure wherein large pits are thickly placed is obtained. Then, by performing an electrolytic surface roughening by using A/C in an electrolytic solution containing hydrochloric acid and acetic acid, small pits are formed under a thickly placed state by overlapping the large pits. The surface melting amount by an alkaline surface melting treatment liquid (2) which is applied next, is 0.6-3.0 g/m<2> . By this method, the small pit shape is controlled in such a manner that the average opening diameter may be 0.2μm or higher and 0.8μm or lower, and also, a ratio of the depth and the opening diameter may be 0.2 or lower. |
