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US 5,956,843 AGranted
Multilayer printed wiring board and method of making same
AssigneeInternational Business Machines Corporation
InventorsShogo Mizumoto, Yutaka Tsukada
Life of this patent
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Abstract
A multilayered printed wiring board includes two or more layers each having a via hole therein, these holes aligned vertically above one another to minimize board real estate while assuring an effective circuit path between respective points on the two layers. One or both via holes can be filled with either an electrically conductive material (e.g., copper paste) or a nonconductive material (e.g., resin).
Claims4
A method for fabricating a multilayered printed wiring board comprising the steps of:
- providing a first insulating layer;
- forming a first via hole at a predetermined position within said insulating layer;
- forming a first metal plated layer on said first via hole, said first metal layer having an outer surface external of said first via hole;
- filling said first via hole with filler material;
- smoothing said outer surface of said first metal plated layer after said step of filling said first via hole with said filler material;
- forming a second insulating layer on said first insulating layer and over said first via hole;
- forming a second via hole in said second insulating layer at a location directly above said first via hole in said first insulating layer and in direct contact therewith;
- forming a second metal plated layer on said second via hole such that said second metal plated layer is in direct physical contact with said filler material within said first via hole;
- and
- forming an electrical circuit pattern from said second metal plated layer.
7 more elements
Dependencies are inferred from the claim text.