| 摘要 |
Sheet metal plate has grooves formed in a side, by the electro chemical/photo resist method. Holes are formed in the same way, in the groove bottoms and pass through the metal thickness. In order to ensure that the holes have substantially parallel, dimensionally accurate walls, the sheet thickness to hole diameter ratio, is effectively reduced by first forming the holes to half depth in one side of the sheet, then forming grooves in the same side of the sheet in which the half holes are formed, so as to remove the half holes but leave depressions in the groove bottom at the positions where the half holes had been previously formed, then forming the hole proper for the holes by removing the metal from the opposite side of the sheet.
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