Method of fabricating mask-over-copper printed circuit boards

Claim 1

A method of fabricating a mask-over-copper printed circuit board having circuit connections on both sides thereof and a solder mask covering portions of at least one side thereof, from a laminate of insulating board material having an electrically conductive coating of copper extending across and laminated to each of the opposed first and second sides thereof, comprising the steps of (a) piercing a desired pattern of holes completely through all three layers of said laminate; (b) forming a desired circuit connection pattern of said laminate copper coating extending between selected said holes on said laminate first side by selective removal of undesired portions of said laminate first side copper coating; (c) electrically connecting said laminate first side connection pattern by conductive metallic material deposited extending through said holes to said laminate second side copper coating extending across said laminate second side, whereby electrical continuity may be maintained among the various holes and connections by said second side copper coating; (d) applying a solder mask to the areas of said first side copper connection pattern which are to be protected from solder during any subsequent fabrication soldering steps and then electroplating a protective metallic material to portions of the first side connection pattern copper material not covered by said solder mask and to desired portions of a circuit connection pattern on said second side copper coating while said laminate second side copper coating remains extending across said laminate second side; and (e) removing the portions of said laminate second side copper coating outside said second side connection pattern, whereby may be produced a printed circuit board having connection patterns on both sides thereof and a solder mask over selected portions of at least the first side copper connection pattern.

Claim 2

A method of fabricating a mask-over-copper printed circuit board having circuit connections on both sides thereof and a solder mask covering portions of at least one side thereof, from a laminate of insulating board material having an electrically conductive coating of copper extending across and laminated to each of the opposed first and second sides thereof, comprising the steps of (a) piercing a desired pattern of holes completely through all three layers of said laminate; (b) forming a desired circuit connection pattern of said laminate copper coating extending between selected said holes on said laminate first side by selective removal of undesired portions of said laminate first side copper coating; (c) electrically connecting said laminate first side connection pattern by conductive metallic material deposited extending through said holes to said laminate second side copper coating extending across said laminate second side, whereby electrical continuity may be maintained among the various holes and connections by said second side copper coating; (d) applying a solder mask to the areas of said first side copper connection pattern which are to be protected from solder during any subsequent fabrication soldering steps and then electroplating a protective metallic material to portions of the first side connection pattern copper material not covered by said solder mask and to desired portions of a circuit connection pattern on said second side copper coating while said laminate second side copper coating remains extending across said laminate second side; and (e) removing the portions of said laminate second side copper coating outside said second side connection pattern, whereby may be produced a printed circuit board having connection patterns on both sides thereof and a solder mask over selected portions of at least the first side copper connection pattern.

Claim 10

A method of fabricating a mask-over-copper printed circuit board having circuit connection patterns on both sides thereof from a laminate of insulating board material having a conductive coating of copper material laminated to each of the opposed first and second sides thereof, comprising the steps of (a) piercing a desired pattern of holes through said laminate; (b) applying a first protective material to the areas of said first side copper coating defining a desired first side circuit connection pattern extending between selected said holes; (c) removing said laminate first side copper coating from the areas of said first side not covered by said first protective material, whereby the first side circuit connection pattern is formed; (d) removing said first protective material from said laminate; (e) applying a solder mask to the portions of said laminate first side which are desired to be protected from solder in any subsequent fabrication soldering steps; (f) depositing a conductive metallic material onto said laminate extending through said holes between said first and second side copper coatings, whereby electrical continuity may be established through said holes between the laminate first and second side copper coatings; (g) applying a plating resist material to areas of said laminate second side copper coating which are to be removed in a subsequent etching operation such that the portions not covered by said coating define a desired second side circuit connection pattern extending between selected said holes; (h) electroplating a conductive metal to the areas of said laminate not covered by either said solder mask or said plating resist material; (i) removing said plating resist material from said laminate second side copper coating; and (j) etching said laminate second side to remove completely said second side copper coating from all areas where no metal was deposited by said electroplating, whereby may be produced a printed circuit board having conductive connection patterns on both sides thereof and a solder mask over copper on at least one side thereof.

Claim 11

A method of fabricating a mask-over-copper printed circuit board having circuit connection patterns on both sides thereof from a laminate of insulating board material having a conductive coating of copper material laminated to each of the opposed first and second sides thereof, comprising the steps of (a) piercing a desired pattern of holes through said laminate; (b) applying a first protective material to the areas of said first side copper coating defining a desired first side circuit connection pattern extending between selected said holes; (c) removing said laminate first side copper coating from the areas of said first side not covered by said first protective material, whereby the first side circuit connection pattern is formed; (d) removing said first protective material from said laminate; (e) applying a solder mask to the portions of said laminate first side which are desired to be protected from solder in any subsequent fabrication soldering steps; (f) depositing a conductive metallic material onto said laminate extending through said holes between said first and second side copper coatings, whereby electrical continuity may be established through said holes between the laminate first and second side copper coatings; (g) applying a plating resist material to areas of said laminate second side copper coating which are to be removed in a subsequent etching operation such that the portions not covered by said coating define a desired second side circuit connection pattern extending between selected said holes; (h) electroplating a conductive metal to the areas of said laminate not covered by either said solder mask or said plating resist material; (i) removing said plating resist material from said laminate second side copper coating; and (j) etching said laminate second side to remove completely said second side copper coating from all areas where no metal was deposited by said electroplating, whereby may be produced a printed circuit board having conductive connection patterns on both sides thereof and a solder mask over copper on at least one side thereof.

Claim 15

A method of fabricating a mask-over-copper printed circuit board from a laminate of insulating board material having an electrically conductive metallic coating laminated to the opposed first and second broad surfaces thereof, comprising the steps of (a) piercing a desired pattern of holes through the laminate; (b) depositing an electrically conductive metallic coating to said laminate extending through said holes between said laminate conductive metallic coatings; (c) applying a first plating resist material to the portions of said laminate first side conductive metallic coating which are to be removed by etching in a first subsequent etching operation, such that the areas not covered by said first plating resist material define a desired first side circuit connection pattern extending between selected said holes; (d) application of a second plating resist material to portions of said laminate second side conductive metallic coating, covering areas of said laminate where said metallic coating is to be removed in a second subsequent etching operation, such that the areas not covered by said second plating resist material define a desired second side circuit connection pattern extending between selected said holes; (e) a first electroplating step for electroplating copper to the areas of said laminate not covered by either said first or said second plating resist material; (f) removing said first plating resist material from said first side of said laminate; (g) removing said laminate conductive metallic coating only from said areas previously covered by said first plating resist material by etching in a first etching operation using a first etching material, whereby a conductive connection pattern is formed on the laminate first side; (h) applying a first side solder mask to the portions of said laminate first side which are desired to be protected from solder in subsequent fabrication operations of said printed circuit boards; (i) a second electroplating step for electroplating a protective conductive metallic material onto the areas of copper deposition on said laminate which are not covered by said solder mask; (j) removing said second plating resist material from said laminate second side; and (k) removing said laminate second side conductive metallic coating from said areas previously covered by said second plating resist material by etching in a second etching operation using a second etching material, whereby a conductive metallic connection pattern is formed on the laminate second side.

Claim 16

A method of fabricating a mask-over-copper printed circuit board from a laminate of insulating board material having an electrically conductive metallic coating laminated to the opposed first and second broad surfaces thereof, comprising the steps of (a) piercing a desired pattern of holes through the laminate; (b) depositing an electrically conductive metallic coating to said laminate extending through said holes between said laminate conductive metallic coatings; (c) applying a first plating resist material to the portions of said laminate first side conductive metallic coating which are to be removed by etching in a first subsequent etching operation, such that the areas not covered by said first plating resist material define a desired first side circuit connection pattern extending between selected said holes; (d) application of a second plating resist material to portions of said laminate second side conductive metallic coating, covering areas of said laminate where said metallic coating is to be removed in a second subsequent etching operation, such that the areas not covered by said second plating resist material define a desired second side circuit connection pattern extending between selected said holes; (e) a first electroplating step for electroplating copper to the areas of said laminate not covered by either said first or said second plating resist material; (f) removing said first plating resist material from said first side of said laminate; (g) removing said laminate conductive metallic coating only from said areas previously covered by said first plating resist material by etching in a first etching operation using a first etching material, whereby a conductive connection pattern is formed on the laminate first side; (h) applying a first side solder mask to the portions of said laminate first side which are desired to be protected from solder in subsequent fabrication operations of said printed circuit boards; (i) a second electroplating step for electroplating a protective conductive metallic material onto the areas of copper deposition on said laminate which are not covered by said solder mask; (j) removing said second plating resist material from said laminate second side; and (k) removing said laminate second side conductive metallic coating from said areas previously covered by said second plating resist material by etching in a second etching operation using a second etching material, whereby a conductive metallic connection pattern is formed on the laminate second side.