| 摘要 |
PURPOSE:To assure shielding effect by facilitating water discharge upon heating by constructing a shielding layer with a thin primary conductor layer provided on the whole surface of an organic insulating layer excepting a through-hole part and with a thick mesh-shaped secondary conductor layer provided on the primary conductor layer. CONSTITUTION:A multilayer wiring board is constructed by alternately laminating an organic insulating material and a conductor layer on a base board 2. A shielding layer 3 provided on an intermediate layer or an uppermost layer is formed by preparing a 500-2000Angstrom thick primary conductor layer 5 over the entire surface of an insulating layer 4 of the organic insulating material and preparing a predetermined size mesh-shaped thick secondary conductor layer 6 on the primary conductor layer 5 by electroplating. Thereupon, the primary conductor 5 is left behind so as not to be etched excepting through-hole or via hole 9 parts. Thus, an absorbed water fraction in the lower layer of the shielding layer can easily be discharged upon heating and hence a shielding layer effective for crosstalk and the like can be assured. |
