| 摘要 |
PROBLEM TO BE SOLVED: To form a hole for a small-diameter through hole accurately by etching and removing a metal foil at the same position of the opposite surface of the metal foil at the diameter, which is smaller in the range of the specified ratio than the circle on a laser irradiated surface. SOLUTION: A copper foil (a) at a hole forming position on the surface of a glass-cloth reinforced laminated plate is etched to the specified circular size for carbon-dioxide-gas laser erradiation and removed. Furthermore, the metal film (a) at the same position of the opposite surface is etched at the area, which is smaller than the diameter of the circle on the laser applied surface by 5-80%, and removed. Then, after a through hole (c) is formed by applying the output 30-100 mJ/pulse of the carbon-dioxide gas laser, both surfaces of the metal foil (a) are etched in the planar pattern at the speed of 0.02-1.0μm/sec. The thickness of 1/3-1/2 of the original metal foil is etched and removed. Thus, a land can be formed without shifting the copper-foil position of the upper and lower holes. Furthermore, the processing speed can be made quick. |
