| 摘要 |
PROBLEM TO BE SOLVED: To provide a method, machining an oblong hole in a printed circuit board without inclination of an axis and with good accuracy using a drill. SOLUTION: In this oblong hole-machining method for the printed circuit board, a plurality of circular holes are bored taking a plurality of circle center points on the right and left and in the middle thereof on the same axis by the drill as a fulcrum to form oblong holes, whose longitudinal size is under twice as long as the transverse size. With the circle center points outside the circle center points of the right and left circular holes in the axis taken as a fulcrum, a prepared hole having a small diameter within a range not intersecting the circular holes is bored, and subsequently, with the plurality of circular center points on the right and left and in the middle thereof taken as a fulcrum, a circular hole is bored. The right and left prepared holes 17a, 17b are bored to have the same diameter, substantially come into contact with the inner peripheries of the right and left circular holes 17a, 17b, and substantially bring the outer peripheries thereof into contact with each other. COPYRIGHT: (C)2007,JPO&INPIT
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