| 摘要 |
A drill in which no positional shift on a drilled hole and no irregularities on an internal wall are formed. A torsion angle of a shaving discharge groove of a drill is set in the range of 30 degrees to 50 degrees. In this manner, a positional shift of a through hole to be drilled can be reduced. In addition, shavings of the drill are properly discharged, and thus, drilling is not precluded by the shavings. Therefore, a printed wiring board having excellent electric connectivity and reliability can be obtained.
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