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US 4,303,715 AGranted
Printed wiring board
AssigneeWestern Electric Company, Inc.
InventorJoseph J. Chang
Life of this patent
Estimating the term…
Abstract
A method of fabricating a printed circuit board is disclosed. The method comprises forming a metal substrate having a through-hole pattern. The metal substrate is coated with a dielectric powder having a suitable flow length value to form a dielectric coat on the substrate having a sufficient through-hole edge coverage. The dielectric coated substrate is then treated with a second powder to form a satisfactory topcoat thereon. Electrical circuitry is then formed on the topcoat in conjunction with the through hole pattern.
Claims5
A printed circuit board comprising:
- (a) a metal substrate having a thickness of from about 1 to about 7 mils and a through hole;
- and
- (b) a dielectric coat on said substrate fused from particles of a thermosetting material having a flow length value defined by the area extending between lines A and B in the graph of FIG. 2, said dielectric coat having a through hole edge coverage of at least about 40 percent in thickness of the principle thickness of the dielecric coat.
A printed circuit board comprising:
- (a) a metal substrate having a thickness of from about 1 to about 7 mils and a through hole;
- (b) a dielectric coat on said substrate fused from particles of a thermosetting material having a flow length value defined by the area extending between lines A and B in the graph of FIG. 2, said dielectric coat having a through hole edge coverage of at least about 40 percent in thickness of the principle thickness of the dielectric coat;
- and
- (c) a dielectric top coat on said dielectric coat wherein said topcoat is applied from a powder having a flow length value above curve A of FIG. 2.
1 more element
Dependencies are inferred from the claim text.