Method for electroplating non-metallic surfaces

Claim 3

The method of claim 1 characterized in that said component (C) preferentially attaches itself to a surface of the species of metal (B) compared to the surface of the species of metal (A), substantially inhibiting or reducing the plating reaction on surfaces formed by metal (B) without substantially interfering with the plating reaction on surfaces formed by the species of the site metal (A).

Claim 4

The method of claim 2, characterized in that said component (C) increases the overpotential on surfaces formed by metal (B).

Claim 5

The method of claim 1, characterized in that said component (C) preferentially attaches itself to the species of site metal (A), compared to the surface of the species of metal (B), said attached component (C) substantially increasing the plating reaction on surfaces formed by site metal (A) compared to the plating reaction on surfaces of the species of metal (B).

Claim 6

The method of claim 4 characterized in that said attached component (C) reduces the overpotential thus increasing the plating reaction compared to the plating reaction on surfaces of the species of metal (B).

Claim 7

The method of claim 1 characterized in that component (C) is selected from dyes, surfactants, chelating agents, brighteners and leveling agents.

Claim 8

The method of claim 6 characterized in that component (C) is a dye selected from methylene blue and methyl violet.

Claim 9

The method of claim 6 characterized in that component (C) is a surfactant selected from alkylphenoxy-polyethoxyethanols, nonionic fluorocarbon surfactants, polyoxyethylene compounds, block copolymers of polyoxyethylene and polyoxypropylene.

Claim 10

The method of claim 8 characterized in that component (C) is selected from compounds containing 4 to 1,000,000 oxyethylene groups.

Claim 11

The method of claim 9 characterized in the component (C) is selected from the compounds containing twenty to one hundred fifty oxyethylene groups.

Claim 12

The method of claim 8 characterized in that component (C) is selected from ethylene oxide-propylene oxide copolymers containing 10 to 400 oxyethylene groups.

Claim 13

The method of claim 6 characterized in that component (C) is 2,4,6-(2-pyridyl)-s-triazine.

Claim 14

The method of claim 6 characterized in that component (C) comprises a brightener and/or leveling agent selected from N-heterocyclic compounds, triphenyl methane dyes, thiourea, allyl thiourea, tetrathiuram disulfide, thiourea derivatives, saccharin and O-benzaldehyde sulfonic acid derivatives.

Claim 15

The method of claim 1 characterized in that the conductivity of the electroplating bath solution and the potential applied to the connector area and the counter-electrode are selected sufficiently high to achieve a rate of deposition on the surface of the species of the site metal (A) which is at least one order of magnitude higher than the deposition rate on the surface of the species of metal (B).

Claim 16

The method of claim 14 characterized in that the potential is adjusted to compensate for the potential drop on the resistive path formed by the plating bath solution between the connector area and the metallic sites consisting of, or comprising metal (A), and between such neighboring sites.

Claim 17

The method of claim 1 characterized in that metal (A) and metal (B) are selected from Groups Ib and VIII of the Periodic Table of Elements.

Claim 18

The method of claim 16 characterized in that component (C) is selected from dyes, surfactants, chelating agents, brighteners and leveling agents.

Claim 19

The method of claim 16 characterized in that metal (A) is selected from palladium, platinum, silver or gold.

Claim 20

The method of claim 16 characterized in that metal (B) is selected from copper and nickel.

Claim 21

The method of claim 1 characterized in that metals (A) and (B) are selected so that potential for the deposition of metal (B) on metal (A) is less negative than the potential for the deposition of metal (B) on itself under the conditions provided by the plating operation.

Claim 22

The method of claim 20 characterized in that component (C) is selected from dyes, surfactants, chelating agents, brighteners and leveling agents.

Claim 23

The method of claim 1 characterized in that the site formation step comprises employing metal (A) in solution as a compound or complex.

Claim 24

The method of claim 22 characterized in that the compound is a metal halide or double metal halide.

Claim 25

The method of claim 23 characterized in that the double metal halide is a palladium-tin-chloride.

Claim 26

The method of claim 23 characterized in that the plurality of metal sites of metal (A) is formed by treating the non-metallic surface with a solution comprising metal (A) and subsequently exposing said surface to heat or to a reducing agent.

Claim 27

The method of claim 25 characterized in that said heat-treatment is effected at a temperature in the range of 65° to 120° C. and for at least 10 minutes.

Claim 28

The method of claim 25 characterized in that said reducing agent is selected from sodium borohydride, formaldehyde, dimethylamine borane and hydroxylamine.

Claim 29

The method of claim 22 characterized in that the solution comprises metal (A) and a tin-halide; and that the treated surface is subsequently exposed to a solvent for tin-compounds.

Claim 30

The method of claim 1 characterized in that it further comprises the steps of terminating the deposition of metal (B) after establishing a continuous film of metal (B) of desired thickness over the non-metallic surface; and by electrolytically depositing one or more metal layers on said film or part thereof.

Claim 31

The method of claim 29 characterized in that at least two electroplating bath solutions of different composition are employed; and that the first used solution comprises components which maximize the rate of deposition on metal (A) and that the electroplating bath solutions employed subsequently are formulated for optimizing the properties of the respective metal deposit formed.

Claim 32

In a method for the manufacture of printed circuit board which includes forming holes in a copper clad insulating sheet, or in a laminate formed by a plurality of such sheets, and providing the non-metallic walls of said holes with a metal layer, without prior electroless metal plating, the improvement which comprises: (a) providing a vessel containing a counter-electrode and an electroplating bath of predetermined conductivity comprising in dissolved form a metal (B) to be electroplated, said copper cladding being located outside of and abutting the non-metallic surface of said walls to be electroplated, said abutting copper cladding being employed as an electrode during electroplating; (b) forming a plurality of discrete metallic sites on the walls of said holes, each of said sites comprising or consisting of a metal (A), said metal (A) being different from metal (B); (c) at a subsequent step exposing said sheet or laminate including said copper cladding thereon to the electroplating bath solution which further comprises at least one component (C) which allows preferential deposition of said metal (B) on said metallic sites comprising or consisting of metal (A), at a rate which is faster compared to the electrodeposition rate of metal (B) on surfaces consisting of or formed by the species of the electrodeposited metal (B), with the proviso that component (C) does not comprise pyrophosphate anion; (d) applying a potential between the copper cladding and the counter-electrode which is sufficient to: (1) initiate electroplating of metal (B) on the exposed portion of the copper cladding and (2) allow electroplating of metal (B) on neighboring metallic sites, the application of said potential initiating electroplating of metal (B) on the copper cladding and on said neighboring metallic sites, the electroplating of metal (B) on the copper cladding covering the copper cladding with metal (B); (e) continuing the application of said potential until all said neighboring metallic sites are covered with metal (B), the rate of forming metal (B) deposits on said neighboring metallic sites being greater than the electrodeposition rate of metal (B) on surfaces consisting of or formed by the species of metal (B), the greater rate of electrodeposition of metal (B) on said neighboring metallic sites continuing until all of said sites are covered with metal (B); and (f) continuously electroplating metal (B) on said sheet or laminate to produce an electrically conductive continuous film of metal (B) having a thickness of at least 0.5 microns.

Claim 33

In a method for the manufacture of printed circuit board which includes forming holes in a copper clad insulating sheet, or in a laminate formed by a plurality of such sheets, and providing the non-metallic walls of said holes with a metal layer, without prior electroless metal plating, the improvement which comprises: (a) providing a vessel containing a counter-electrode and an electroplating bath of predetermined conductivity comprising in dissolved form a metal (B) to be electroplated, said copper cladding being located outside of and abutting the non-metallic surface of said walls to be electroplated, said abutting copper cladding being employed as an electrode during electroplating; (b) forming a plurality of discrete metallic sites on the walls of said holes, each of said sites comprising or consisting of a metal (A), said metal (A) being different from metal (B); (c) at a subsequent step exposing said sheet or laminate including said copper cladding thereon to the electroplating bath solution which further comprises at least one component (C) which allows preferential deposition of said metal (B) on said metallic sites comprising or consisting of metal (A), at a rate which is faster compared to the electrodeposition rate of metal (B) on surfaces consisting of or formed by the species of the electrodeposited metal (B), with the proviso that component (C) does not comprise pyrophosphate anion; (d) applying a potential between the copper cladding and the counter-electrode which is sufficient to: (1) initiate electroplating of metal (B) on the exposed portion of the copper cladding and (2) allow electroplating of metal (B) on neighboring metallic sites, the application of said potential initiating electroplating of metal (B) on the copper cladding and on said neighboring metallic sites, the electroplating of metal (B) on the copper cladding covering the copper cladding with metal (B); (e) continuing the application of said potential until all said neighboring metallic sites are covered with metal (B), the rate of forming metal (B) deposits on said neighboring metallic sites being greater than the electrodeposition rate of metal (B) on surfaces consisting of or formed by the species of metal (B), the greater rate of electrodeposition of metal (B) on said neighboring metallic sites continuing until all of said sites are covered with metal (B); and (f) continuously electroplating metal (B) on said sheet or laminate to produce an electrically conductive continuous film of metal (B) having a thickness of at least 0.5 microns.

Claim 34

The method of claim 31 characterized in that it further comprises the steps of providing a negative image resist layer on the surface of said copper clad sheet or laminate, said layer leaving exposed the areas corresponding to a desired conductor pattern which includes said holes, the walls defining said holes provided with said sites of metal (A); and, after establishing a continuous film of metal (B) electrolytically depositing one or more metal layers on said film, removing said resist layer and etching away the metal in the areas which have been covered by said resist layer.

Claim 35

The method of claim 31 characterized in that it further comprises the steps of electrolytically depositing one or more layers of metal over the metal (B) film; providing a positive image resist layer on the surface of said copper clad sheet or laminate subsequent to the electroplating step, said resist layer covering the areas corresponding to the desired circuit pattern including the holes; and etching away the metal not covered by the positive image resist layer thus forming the printed circuit board pattern.

Claim 36

In a method for the manufacture of printed circuit boards comprising forming holes in a non-metallic sheet and metallizing, without prior electroless metal plating, non-metallic areas of said sheet corresponding to a desired printed circuit conductor pattern with a metal layer having a desired thickness, the improvement which comprises: (a) providing a vessel containing a counter-electrode and containing an electroplating bath solution of defined conductivity comprising in ionic form a metal (B) to be electroplated, said non-metallic areas being provided with a conductive connector area, said connector area being located outside of and abutting the non-metallic surface area to be electroplated said abutting connector area being employed as an electrode during electroplating; (b) forming a plurality of discrete metallic sites on the walls of said holes, each of said sites comprising or consisting of a metal (A), said metal (A) being different from a metal (B) to be electroplated; (c) at a subsequent step exposing said sheet including said connector area to the electroplating bath solution which further comprises one or more component(s) (C) which allow deposition of said metal (B) on said metallic sites comprising or consisting of metal (A), at a rate which is faster compared to the electrodeposition rate of metal (B) on surfaces formed by the species of the electro-deposited metal (B), with the proviso that component (C) does not comprise pyrophosphate anion; (d) applying a potential between the connector area and the counter-electrode which is sufficient to: (1) initiate electroplating of metal (B) on the exposed portion of the connector area and (2) allow electroplating of metal (B) on neighboring metallic sites, the application of said potential initiating electroplating of metal (B) on the connector area and on said neighboring metallic sites, the electroplating of metal (B) on the connector area covering the connector area with metal (B); (e) continuing the application of said potential until all said neighboring metallic sites are covered with metal (B), the rate of forming metal (B) deposits on said neighboring metallic sites being greater than the electrodeposition rate of metal (B) on surfaces consisting of or formed by the species of metal (B), the greater rate of electrodeposition of metal (B) on said neighboring metallic sites continuing until all of said sites are covered with metal (B); and (f) continuously electroplating metal (B) onto the exposed portion of the connector area and onto said electroplated sites to produce an electrically conductive continuous film of metal (B) having a thickness of at least 0.5 microns.

Claim 37

In a method for the manufacture of printed circuit boards comprising forming holes in a non-metallic sheet and metallizing, without prior electroless metal plating, non-metallic areas of said sheet corresponding to a desired printed circuit conductor pattern with a metal layer having a desired thickness, the improvement which comprises: (a) providing a vessel containing a counter-electrode and containing an electroplating bath solution of defined conductivity comprising in ionic form a metal (B) to be electroplated, said non-metallic areas being provided with a conductive connector area, said connector area being located outside of and abutting the non-metallic surface area to be electroplated said abutting connector area being employed as an electrode during electroplating; (b) forming a plurality of discrete metallic sites on the walls of said holes, each of said sites comprising or consisting of a metal (A), said metal (A) being different from a metal (B) to be electroplated; (c) at a subsequent step exposing said sheet including said connector area to the electroplating bath solution which further comprises one or more component(s) (C) which allow deposition of said metal (B) on said metallic sites comprising or consisting of metal (A), at a rate which is faster compared to the electrodeposition rate of metal (B) on surfaces formed by the species of the electro-deposited metal (B), with the proviso that component (C) does not comprise pyrophosphate anion; (d) applying a potential between the connector area and the counter-electrode which is sufficient to: (1) initiate electroplating of metal (B) on the exposed portion of the connector area and (2) allow electroplating of metal (B) on neighboring metallic sites, the application of said potential initiating electroplating of metal (B) on the connector area and on said neighboring metallic sites, the electroplating of metal (B) on the connector area covering the connector area with metal (B); (e) continuing the application of said potential until all said neighboring metallic sites are covered with metal (B), the rate of forming metal (B) deposits on said neighboring metallic sites being greater than the electrodeposition rate of metal (B) on surfaces consisting of or formed by the species of metal (B), the greater rate of electrodeposition of metal (B) on said neighboring metallic sites continuing until all of said sites are covered with metal (B); and (f) continuously electroplating metal (B) onto the exposed portion of the connector area and onto said electroplated sites to produce an electrically conductive continuous film of metal (B) having a thickness of at least 0.5 microns.

Claim 38

The method of claim 34 characterized in that said connector area covers the surface of said insulating sheet in small areas along its edges, and shaped like a window frame.

Claim 39

In a method for the manufacture of printed circuit boards which include forming holes in a copper clad insulating sheet, or in a laminate formed from a plurality of such sheets, and providing the walls of said holes with metal layers, the improvement which comprises: (a) forming a plurality of metal sites on the walls of said holes, the metal of said sites being selected from the group consisting of palladium, platinum, silver and gold; and (b) at a subsequent step, without prior electroless metal plating, electrodepositing copper on the hole walls from an acidic electroplating bath comprising copper ions, and an organic compound containing 4 to 1,000,000 oxyethylene groups, the electrodeposited copper on the hole walls forming a continuous conductive film; and (c) further electroplating copper to reinforce the continuous conductive film and form plated through holes in the insulating sheet.

Claim 40

In a method for the manufacture of printed circuit boards which include forming holes in a copper clad insulating sheet, or in a laminate formed from a plurality of such sheets, and providing the walls of said holes with metal layers, the improvement which comprises: (a) forming a plurality of metal sites on the walls of said holes, the metal of said sites being selected from the group consisting of palladium, platinum, silver and gold; and (b) at a subsequent step, without prior electroless metal plating, electrodepositing copper on the hole walls from an acidic electroplating bath comprising copper ions, and an organic compound containing 4 to 1,000,000 oxyethylene groups, the electrodeposited copper on the hole walls forming a continuous conductive film; and (c) further electroplating copper to reinforce the continuous conductive film and form plated through holes in the insulating sheet.

Claim 41

The method of claim 36 wherein the acidic electroplating bath also comprises sulfuric acid.