| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for forming a through hole, capable of suppressing collapse in the shape of the through hole.SOLUTION: The method for forming a through hole includes the step of forming the through hole penetrating an insulating substrate in the thickness direction of the substrate by condensing and applying a laser beam through a condenser lens on the insulating substrate. A medium between the condenser lens and the insulating substrate is air, and a condensing half width θ calculated using the following formula (1) from the focal length f of the condenser lens and the diameter d of the incident beam of the laser beam to the condenser lens satisfies the following formula (2). (d/2)/f=tanθ... (1), 0.16≤sinθ≤0.22... (2)SELECTED DRAWING: Figure 1 |
