| 摘要 |
PURPOSE:To enable conformance/non-conformance of a clearance hole to be inspected with a simple method without being affected by the size of indentation generated due to etching or that of the clearance hole by providing a dummy land whose diameter is smaller than that of the clearance hole by a specified amount within the clearance hole and by measuring the gap width. CONSTITUTION:A clearance hole 10 with a diameter which is larger than that of a machining hole 2a for a through-hole is formed at a metal plate 1 which is applied to an insulating material 3 and a dummy land 20 is formed within the inside while maintaining a specified gap width d with the clearance hole 10 within the inside of the clearance hole 10. The specified gap width d can be maintained to the same value regardless of whether the clearance hole 10 is large or small. Thus, after the clearance hole 10 and the dummy land 20 are formed, it is checked to see if this metal plate 1 leaves copper, etc. |
