ENTRY BOARD FOR SMALL-BORE DIAMETER DRILLING, AND SMALL-BORE DIAMETER DRILLING METHOD

摘要

PROBLEM TO BE SOLVED: To provide an entry board for small-bore diameter drilling and a small-bore diameter drilling method that further improve hole positional precision in forming a small-bore diameter hole in a workpiece, such as a printed wiring board, using a drill.;SOLUTION: An entry board for small-bore diameter drilling is constituted of an aluminium foil composite material in which plural pieces of aluminium foil are laminated. Hardness of aluminium foil on a drill inlet side is smaller than hardness of aluminium foil on a drill outlet side. An average interval (Rsm) between irregularities on a surface of the aluminium foil on the drill inlet side is 15-23 μm in a rolling direction of the same aluminium foil, and 20-48 μm in a direction perpendicular to the rolling direction of the same aluminium foil.;SELECTED DRAWING: Figure 1;COPYRIGHT: (C)2018,JPO&INPIT