US 4,706,167 A · Circuit wiring disposed on solder mask coating

Abstract

In the manufacturing process for a printed wiring board a photopolymer insulation layer having a flat outer plateau surface is extended from the board substrate surface carrying the wiring pattern and provides access channels to a plurality of wiring pattern conductor pad areas. A patterned conductor layer disposed on the insulation layer surface including the sidewalls of the access channels thus electrically connects to the conductor pad areas. Circuit wiring pattern test current or plating currents are passed through the conductor layer pattern during the manufacturing process, and the conductor layer may thereafter be easily removed from the flat surface by sanding or the like. Permanently retained conductor layer portions, such as feasible by indenting the plateau surface, aid in expanding conductor surface areas at solder joint pads, or in increasing the density of circuit wires feasible in a given substrate board area. The conductor layer may provide indicia marking nomenclature patterns which are in dot matrix format to reduce capacitance coupling between wiring circuits on the board substrate.

Claims37

Dependent claims

In a printed wiring board assembly having an insulation photopolymer resist coating such as a solder mask layer disposed to extend upwardly from a conductive circuit wiring pattern on a printed wiring board substrate surface to cover a substantial portion of the substrate surface while leaving exposed through a resist coating conductor pads at predetermined circuit contact positions on the substrate surface, the improvement comprising in combination providing increased efficiency of circuit space usage with given board substrate dimensions thereby permitting additional circuit board patterns to be printed without increasing the substrate area, namely, a thin conductive circuit pattern on the substrate surface, said insulation resist coating consisting of a cured liquid photopolymer with a glossy flush surface formed by contact of a flat plate with the polymer in liquid form which is adhered to the substrate surface and presents a flush flat surface plateau with access channels downwardly extending thereinto to expose the conductor pads on the substrate surface and having a thin conductive coating on the channel sidewalls electrically contacting the exposed conductor pads, and a layer of conductive material disposed on the surface of said insulation coating in a pattern with controlled electronic coupling to the circuit board wiring pattern.

The method of producing a printed wiring board assembly having an insulation resist coating such as a solder mask layer disposed to extend upwardly from a conductive circuit wiring pattern on the printed wiring board substrate surface leaving exposed conductor pads at predetermined circuit contact positions on the substrate surface, comprising the steps of:

improving efficiency of circuit space usage with given board substrate dimensions thereby permitting additional circuit board patterns to be printed without increasing the substrate area by providing on the substrate surface a thin conductive circuit pattern, adhering to the substrate surface an insulation resist coating presenting a flush flat surface plateau with access channels downwardly extending thereinto exposing conductor pads in the conductive circuit pattern on the substrate surface, coating channel sidewalls with a thin conductive coating electrically contacting the exposed conductor pads, disposing on the surface of said insulation coating a layer of conductive material as indicia marking nomenclature in a pattern electronically coupled to the circuit board wiring pattern on the substrate surface, and photoprinting a layer of liquid photopolymer overlying the printed wiring on said board to produce a permanently adhered said resist coating.

improving efficiency of circuit space usage with given board substrate dimensions thereby permiting additional circuit board patterns to be printed without increasing the substrate area by providing on the substrate surface a thin conductive circuit pattern, adhering to the substrate surface an insulation resist coating presenting a flush flat surface plateau with access channels downwardly extending thereinto exposing conductor pads in the conductive circuit pattern on the subtrate surface, coating channel sidewalls with a thin conductive coating electrically contacting the exposed conductor pads, disposing on the surface of said insulation coating a layer of conductive material as indicia marking nomenclature in a pattern electronically coupled to the circuit board wiring pattern on the substrate surface, and providing at least one temporary conductive path on said insulation surface plateau with electrical connection to the circuit wiring pattern, conducting electrical current through said temporary conductive path to said circuit wiring pattern in a manufacturing step, and removing the temporary conductive path from the plateau following completion of said manufacturing step.

Dependencies are inferred from the claim text.

Circuit wiring disposed on solder mask coating

Life of this patent

Circuit wiring disposed on solder mask coating

Life of this patent

Abstract

Claims37