| 摘要 |
PROBLEM TO BE SOLVED: To realize high quality boring without sacrifice of high speed energy beam machining by providing a diffusion preventive means on the inner wall of a through hole or a via hole where a connecting means, or at least the conductive substance therein, is not diffused to the outside. SOLUTION: When a through hole 15 is made by irradiating a board material 11 with a laser beam 14, thermosetting resin 12 and aramid fibers 13 in the board material 11 are thermally sublimated and scattered to the surroundings. When correct machining conditions are set, the aramid fibers 13 are integrated through fusion, for example, in the vicinity of the inner wall of a hole to form a diffusion preventive means, i.e., a quality change layer 16. Bonding reliability can be enhanced by conducting hot press while leaving only conductive particles on a conductive paste 17 selectively in the through hole 15 thereby increasing the density of the conductive particles sufficiently in the through hole 15 after hot press. |
