| 摘要 |
<p>PROBLEM TO BE SOLVED: To form high-precision through holes capable of coping with increase in input/output pads of silicon chips and preventing deformation or deterioration in a sheet material, or deformation in the through holes caused by heat radiation failure of working heat when the through holes arranged in a nearly lattice state with narrow intervals are formed by irradiating a laser beam. SOLUTION: In a piercing method which forms the through holes arranged in a nearly lattice state by irradiating the laser beam on a preset sheet, a piercing point which positions nearly center part of the nearly lattice arrangement is used as a starting point and the laser beam is irradiated while the boring point is shifted from this starting point toward the outer side nearly concentrically. Especially, it is desirable to form the through holes at every boring point by repeating a process which irradiates the laser beam on every boring point arranged in a nearly lattice state at lest at every one pulse several times.</p> |
