US4601916A — Process for bonding metals to electrophoretically…

Claim 1

Independent Claim 346 words

In a process for producing a printed circuit on an insulated metal substrate, which process includes providing one or more insulating layers on surfaces of a metal sheet to form the insulated metal substrate; providing one or more holes through the insulated substrate for through connections; etching the hole walls defined by the metal sheet to enlarge by a predetermined amount only the portion of the holes extending through the metal sheet, electrophoretically depositing a resinous coating comprising a cathodic or anodic electrophoretic thermosetting resin from a solution thereof on the etched portion of the hole walls; curing the resinous coating; and forming the printed circuit on the surface of the insulating layers and on the walls of the holes; the improvement comprising: incorporating in the resin solution a solid filler in finely divided form and having an average particle size of about 1 micron or less, the filler being non-resinous, inorganic, non-reactive with the solution and uniformly dispersed therethrough, the filler being capable of improving the adhesion of a metal layer to the electrophoretically deposited resinous coating after the coating is adhesion promoted, the resinous coating containing the filler having a volume resistivity greater than 10 4 megohm-cm between the printed circuit conductor and the metal sheet; electrophoretically depositing the resinous coating and the filler from the solution onto the metal wall portions of the holes, the deposited coating having fillers dispersed therethrough; curing the resinous coating, the thickness of the cured resinous coating being between about 0.025 mm and about 0.055 mm, the cured resinous coating being comprised of (a) 1% to 25% by weight of said filler, and (b) the balance being said thermosetting resin; adhesion promoting the surface of the resinous coating containing the filler to create a hydrophilic, microetched surface on the coating; depositing a metal layer on the surface of the resinous coating on the hole walls, and on the insulating layers, the metal layer deposited on the microetched surface of the resinous coating being continuous and free of blisters, and forming said printed circuit on the insulated metal substrate.

Claim 2

Dependent Claim 346 words

In a process for producing a printed circuit on an insulated metal substrate, which process includes providing one or more insulating layers on surfaces of a metal sheet to form the insulated metal substrate; providing one or more holes through the insulated substrate for through connections; etching the hole walls defined by the metal sheet to enlarge by a predetermined amount only the portion of the holes extending through the metal sheet, electrophoretically depositing a resinous coating comprising a cathodic or anodic electrophoretic thermosetting resin from a solution thereof on the etched portion of the hole walls; curing the resinous coating; and forming the printed circuit on the surface of the insulating layers and on the walls of the holes; the improvement comprising: incorporating in the resin solution a solid filler in finely divided form and having an average particle size of about 1 micron or less, the filler being non-resinous, inorganic, non-reactive with the solution and uniformly dispersed therethrough, the filler being capable of improving the adhesion of a metal layer to the electrophoretically deposited resinous coating after the coating is adhesion promoted, the resinous coating containing the filler having a volume resistivity greater than 10 4 megohm-cm between the printed circuit conductor and the metal sheet; electrophoretically depositing the resinous coating and the filler from the solution onto the metal wall portions of the holes, the deposited coating having fillers dispersed therethrough; curing the resinous coating, the thickness of the cured resinous coating being between about 0.025 mm and about 0.055 mm, the cured resinous coating being comprised of (a) 1% to 25% by weight of said filler, and (b) the balance being said thermosetting resin; adhesion promoting the surface of the resinous coating containing the filler to create a hydrophilic, microetched surface on the coating; depositing a metal layer on the surface of the resinous coating on the hole walls, and on the insulating layers, the metal layer deposited on the microetched surface of the resinous coating being continuous and free of blisters, and forming said printed circuit on the insulated metal substrate.

Claim 3

Dependent Claim 30 words

A process as defined in claim 1, wherein the solid filler is selected from the group consisting of clays, silicas, aluminas, silicates, earths, barium sulfide, zinc oxide and titanium dioxide.

Claim 4

Dependent Claim 15 words

A process as defined in claim 1, wherein the adhesion promotion is accomplished by oxidation.

Claim 5

Dependent Claim 17 words

A process as defined in claim 3, wherein the oxidation is accomplished by an aqueous oxidizing solution.

Claim 6

Dependent Claim 18 words

A process as defined in claim 1, wherein the adhesion promotion is accomplished with a hexavalent chromium solution.

Claim 7

Dependent Claim 30 words

A process as defined in claim 1, wherein the adhesion promotion is accomplished with a first acid solution and a second oxidizing solution, said second oxidizing solution comprising hexavalent chromium.

Claim 8

Dependent Claim 24 words

A process as defined in claim 1 wherein the metal layer deposited on the microetched surface of the resinous coating passes a tape test.

Claim 9

Dependent Claim 34 words

A process as defined in claim 1, wherein the metal layer deposited on the microetched surface of the resinous coating adheres to the coating with a peel strength of at least about 0.1 N/mm.

Claim 10

Dependent Claim 325 words

In a process for producing a printed circuit on an insulated metal substrate comprised of a metal sheet with insulating surface layers in which the substrate is provided with holes for through connections, the portions of hole walls extending through the metal sheet are enlarged by a predetermined amount and metal wall portions of the holes are insulated with a resinous coating electrophoretically deposited from a solution thereof, the solution comprising an anodic or cathodic electrophoretic epoxy resin, the improvement comprising: incorporating in the resin solution a solid filler in particulate form, the average particle size of which is finer than about 1 micron in diameter, said filler being non-resinous, inorganic, non-reactive with the solution and uniformly dispersed therethrough, the filler being capable of improving the adhesion of a metal layer to the electrophoretically deposited resinous coating after the coating is adhesion promoted, the filler being selected from the group consisting of clays, aluminas, silicates, earths, barium sulfate, zinc oxide and titanium dioxide, the resinous coating containing the filler having a volume restivity greater than 10 4 megohm-cm between the printed circuit conductor and the metal sheet; electrophoretically depositing the resinous coating and filler from the solution onto the metal wall portions of the holes, the deposited coating having filler uniformly dispersed therethrough; curing the resinous coating, the thickness of the coating after curing being between about 0.025 mm and about 0.055 mm, the cured resinous coating being comprised of 1 to 25% by weight of said filler, the balance being said epoxy resin; adhesion promoting the surface of the resinous coating with an aqueous oxidizing solution to create a hydrophilic, microetched surface on the coating; depositing a metal layer on the surface of the resinous coating on the hole walls, and on the insulating surface layers, the metal layer deposited on the microetched surface of the resinous coating being continuous and free of blisters, and forming said printed circuit on the insulated metal substrate.

Claim 11

Dependent Claim 325 words

In a process for producing a printed circuit on an insulated metal substrate comprised of a metal sheet with insulating surface layers in which the substrate is provided with holes for through connections, the portions of hole walls extending through the metal sheet are enlarged by a predetermined amount and metal wall portions of the holes are insulated with a resinous coating electrophoretically deposited from a solution thereof, the solution comprising an anodic or cathodic electrophoretic epoxy resin, the improvement comprising: incorporating in the resin solution a solid filler in particulate form, the average particle size of which is finer than about 1 micron in diameter, said filler being non-resinous, inorganic, non-reactive with the solution and uniformly dispersed therethrough, the filler being capable of improving the adhesion of a metal layer to the electrophoretically deposited resinous coating after the coating is adhesion promoted, the filler being selected from the group consisting of clays, aluminas, silicates, earths, barium sulfate, zinc oxide and titanium dioxide, the resinous coating containing the filler having a volume restivity greater than 10 4 megohm-cm between the printed circuit conductor and the metal sheet; electrophoretically depositing the resinous coating and filler from the solution onto the metal wall portions of the holes, the deposited coating having filler uniformly dispersed therethrough; curing the resinous coating, the thickness of the coating after curing being between about 0.025 mm and about 0.055 mm, the cured resinous coating being comprised of 1 to 25% by weight of said filler, the balance being said epoxy resin; adhesion promoting the surface of the resinous coating with an aqueous oxidizing solution to create a hydrophilic, microetched surface on the coating; depositing a metal layer on the surface of the resinous coating on the hole walls, and on the insulating surface layers, the metal layer deposited on the microetched surface of the resinous coating being continuous and free of blisters, and forming said printed circuit on the insulated metal substrate.

Claim 12

Dependent Claim 202 words

A process for depositing an adherent metallic film on at least part of a surface of a metal substrate coated with an electrophoretically deposited resinous coating, the resinous coating including a anodic or cathodic electrophoretic thermosetting resin, the process comprising: (a) incorporating in the resinous coating a filler in finely divided form selected from the group consisting of clays, alumina, silica, silicates, earths, barium sulfate, zinc oxide and titanium dioxide; (b) electrophoretically depositing the resinous coating onto the surface of a metal substrate; (c) curing said resinous coating, the cured resinous coating being comprised of 1% to 25% by weight of said filler, the balance being said thermosetting resin; (d) adhesion promoting the surface of said resinous coating to expose some of the filler and to create a microporous, hydrophilic surface on at least part of the coating, wherein the adhesion promotion is accomplished with a first acid solution followed by a second oxidizing solution, said second oxidizing solution comprising hexavalent chromium; and (e) electrolessly depositing an adherent metallic film on the part of the surface which has been adhesion promoted, the metal film deposited being continuous, free of blisters and adhering to the resinous coating when tested with a pressure-sensitive tape.

Claim 13

Dependent Claim 202 words

A process for depositing an adherent metallic film on at least part of a surface of a metal substrate coated with an electrophoretically deposited resinous coating, the resinous coating including a anodic or cathodic electrophoretic thermosetting resin, the process comprising: (a) incorporating in the resinous coating a filler in finely divided form selected from the group consisting of clays, alumina, silica, silicates, earths, barium sulfate, zinc oxide and titanium dioxide; (b) electrophoretically depositing the resinous coating onto the surface of a metal substrate; (c) curing said resinous coating, the cured resinous coating being comprised of 1% to 25% by weight of said filler, the balance being said thermosetting resin; (d) adhesion promoting the surface of said resinous coating to expose some of the filler and to create a microporous, hydrophilic surface on at least part of the coating, wherein the adhesion promotion is accomplished with a first acid solution followed by a second oxidizing solution, said second oxidizing solution comprising hexavalent chromium; and (e) electrolessly depositing an adherent metallic film on the part of the surface which has been adhesion promoted, the metal film deposited being continuous, free of blisters and adhering to the resinous coating when tested with a pressure-sensitive tape.

Claim 14

Dependent Claim 15 words

A process as defined in claim 10, wherein the hexavalent chromium compound is chromium trioxide.

Claim 15

Dependent Claim 17 words

A process as defined in claim 11, wherein the aqueous solution of chromium trioxide comprises 400-900 g/l.

Claim 16

Dependent Claim 13 words

A process as defined in claim 2 wherein said filler is a clay.

Claim 17

Dependent Claim 24 words

A process as defined in claim 13 wherein said clay is a hydrous aluminum silicate clay with an average particle size of 0.5 micrometers.

Claim 18

Dependent Claim 13 words

A process as defined in claim 10, wherein said filler is a clay.

Claim 19

Dependent Claim 24 words

A process as defined in claim 15, wherein said clay is a hydrous aluminum silicate clay with an average particle size of 0.5 micrometers.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1989-07-21	1990-01-20	1990-07-22	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1993-07-21	1994-01-20	1994-07-22	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1997-07-21	1998-01-20	1998-07-22	$7700.00	Window Closed / Lapsed

Process for bonding metals to electrophoretically deposited resin coatings

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