| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve producibility of a conduction hole processing and realize high reliability by improvement of conductivity, by forming a metallic layer of low heat conduction and low boiling point in a conductor layer surface in the middle, at a side wherein a conduction hole for interlayer conduction is processed. SOLUTION: In a printed board 102, zinc platings 101a, 101b are applied to both sides of a copper foil 1b which is a conductor layer held between insulation layers 2a, 2b and a metallic layer is formed. Zinc used for the zinc platings 101a, 101b is a metal of low heat conductivity and low boiling point. Therefore, when laser beam is cast on zinc to fuse zinc, a surface thereof vaporizes and an irradiation part alone can be removed. That is, zinc is vaporized during hole making processing by laser irradiation and a trouble of insulation layer residue can be eliminated by forming a metallic layer (zinc) of low heat conductivity and low boiling point in a surface of an intermediate conductor layer (copper foil 1b), by plating at a side of the printed board 102 wherein a through- hole is provided.</p> |
