One hundred percent pattern plating of plated through-hole circuit boards

Claim 2

A process for manufacturing an electrical printed circuit board having plated through-holes for electrically interconnecting circuits on opposite surfaces of the board, said process comprising the steps of: (a) laminating a thin copper foil on opposite surfaces of an epoxy glass substrate; (b) forming apertures through the laminated assembly at the locations of the desired plated through-holes; (c) electroless copper plating the exposed surfaces of the apertures and the opposite surfaces of the substrate; (d) applying a layer of photoresist to both opposite surfaces of the apertured laminated assembly to define resist layer portions susceptible to a chemical developer over the apertures and a desired circuit image on opposite surfaces, and resist portions resistant to chemical etchant over the remainder thereof; (e) chemically removing those portions of the photoresist layer susceptible to the developer to expose the apertures and the desired circuit image on opposite surfaces of the substrate; (f) removing the electroless copper plating; (g) plating again by electroless copper plating the surfaces of the apertures and the desired circuit image to establish an initial copper thickness; (h) electroplating with copper the surfaces of the apertures and the desired circuit image to the approximate thickness of the photoresist; (i) electroplating the copper plating with solder; (j) removing the remaining portions of the photoresist from the board; and (k) chemically removing the exposed laminated copper foil from the substrate.

Claim 3

The process defined in claim 1 wherein the thin copper foil has a thickness of about 0.00014 inch, and the epoxy glass substrate has a thickness of about 0.062 inch.

Claim 4

The process defined in claim 1 wherein the layer of photoresist has a thickness of about 0.0018 inch.

Claim 5

The process defined in claim 3 wherein the plated copper circuit image has a thickness of about 0.0015 inch.

Claim 6

The process defined in claim 1 wherein the thickness of the solder plating is about 0.0003 inch.

Claim 7

A process for manufacturing an electrical printed circuit board having plated through-holes for connecting circuits on opposite surfaces of the board comprising the steps of: (a) laminating a copper foil having a thickness of about 0.00014 inch on opposite surfaces of an epoxy glass substrate board, the substrate board being substantially flat and having a thickness of about 0.062 inch; (b) drilling a plurality of apertures through the laminated substrate board at the desired locations of the plated through-holes; (c) sensitizing the exposed surfaces of the substrate board in the apertures by a catalyst; (d) electroless copper plating the surfaces of the apertures and the opposite surfaces of the substrate board to establish an initial copper thickness; (e) laminating at an elevated temperature, a dry film photoresist having a thickness of approximately 0.0018 inch to opposite surfaces of the drilled assembly; (f) photographically exposing and developing the photoresist to define non-polymerized portions over the apertures and the desired circuit images and polymerized portions over the remainder of the photoresist; (g) chemically removing the non-polymerized portions of the photoresist to expose the apertures and the desired circuit images; (h) removing the electroless copper plating; (i) reapplying electroless copper plating over the surfaces of the apertures and the desired circuit images to establish an initial copper thickness; (j) electroplating with copper the surfaces of the apertures to a thickness of approximately one mil and the circuit image to a thickness of approximately 1.5 mil; (k) electroplating with solder the copper plating to a thickness of 0.0003 inch; (l) removing the polymerized photoresist from the board; and (m) chemically etching the now exposed copper foil from the substrate.

Claim 8

A process for manufacturing an electrical printed circuit board having plated through-holes for connecting circuits on opposite surfaces of the board comprising the steps of: (a) laminating a copper foil having a thickness of about 0.00014 inch on opposite surfaces of an epoxy glass substrate board, the substrate board being substantially flat and having a thickness of about 0.062 inch; (b) drilling a plurality of apertures through the laminated substrate board at the desired locations of the plated through-holes; (c) sensitizing the exposed surfaces of the substrate board in the apertures by a catalyst; (d) electroless copper plating the surfaces of the apertures and the opposite surfaces of the substrate board to establish an initial copper thickness; (e) laminating at an elevated temperature, a dry film photoresist having a thickness of approximately 0.0018 inch to opposite surfaces of the drilled assembly; (f) photographically exposing and developing the photoresist to define non-polymerized portions over the apertures and the desired circuit images and polymerized portions over the remainder of the photoresist; (g) chemically removing the non-polymerized portions of the photoresist to expose the apertures and the desired circuit images; (h) removing the electroless copper plating; (i) reapplying electroless copper plating over the surfaces of the apertures and the desired circuit images to establish an initial copper thickness; (j) electroplating with copper the surfaces of the apertures to a thickness of approximately one mil and the circuit image to a thickness of approximately 1.5 mil; (k) electroplating with solder the copper plating to a thickness of 0.0003 inch; (l) removing the polymerized photoresist from the board; and (m) chemically etching the now exposed copper foil from the substrate.

Claim 9

A process for manufacturing a printed circuit board having plated through-holes for interconnecting circuits on opposite sides of the board, said process comprising the steps of: (a) laminating a 0.00014 inch copper foil on opposite surfaces of an epoxy glass substrate board, the board being substantially flat and having a thickness of 0.062 inch; (b) drilling apertures through the laminated assembly at the desired locations of the plated through-holes; (c) sensitizing the exposed epoxy glass surfaces of the drilled apertures by applying a catalyst; (d) electroless copper plating the copper film over the entire substrate board; (e) laminating at an elevated temperature a dry film photoresist having a thickness of about 0.0018 inch to opposite surfaces of the drilled substrate board; (f) photographically exposing and developing the photoresist to define portions which are not polymerized over the apertures and the desired circuit images and polymerized portions over the remainder of the photoresist; (g) chemically removing the non-polymerized portions of the photoresist to expose the surfaces of the apertures and the desired circuit images; (h) stripping the electroless copper film from the surfaces exposed by the removal of the non-polymerized portions of the photoresist; (i) electroless copper plating again the surfaces of the apertures and the desired circuit images to establish an initial copper thickness; (j) electroplating copper with the surfaces of the apertures to a thickness of one mil and the circuit images to a thickness of 1.5 mil; (k) electroplating with solder the copper plating to a thickness of 0.0003 inch; (l) removing the polymerized photoresist from the board; and (m) chemically etching the now exposed copper film and copper foil from the substrate board.

Claim 10

A process for manufacturing a printed circuit board having plated through-holes for interconnecting circuits on opposite sides of the board, said process comprising the steps of: (a) laminating a 0.00014 inch copper foil on opposite surfaces of an epoxy glass substrate board, the board being substantially flat and having a thickness of 0.062 inch; (b) drilling apertures through the laminated assembly at the desired locations of the plated through-holes; (c) sensitizing the exposed epoxy glass surfaces of the drilled apertures by applying a catalyst; (d) electroless copper plating the copper film over the entire substrate board; (e) laminating at an elevated temperature a dry film photoresist having a thickness of about 0.0018 inch to opposite surfaces of the drilled substrate board; (f) photographically exposing and developing the photoresist to define portions which are not polymerized over the apertures and the desired circuit images and polymerized portions over the remainder of the photoresist; (g) chemically removing the non-polymerized portions of the photoresist to expose the surfaces of the apertures and the desired circuit images; (h) stripping the electroless copper film from the surfaces exposed by the removal of the non-polymerized portions of the photoresist; (i) electroless copper plating again the surfaces of the apertures and the desired circuit images to establish an initial copper thickness; (j) electroplating copper with the surfaces of the apertures to a thickness of one mil and the circuit images to a thickness of 1.5 mil; (k) electroplating with solder the copper plating to a thickness of 0.0003 inch; (l) removing the polymerized photoresist from the board; and (m) chemically etching the now exposed copper film and copper foil from the substrate board.

Claim 11

The process defined in claim 7 wherein the substrate board is backed by a sheet of backing material before drilling apertures through the board.