Method for depositing a metal on a surface

Claim 1

A method for selectively depositing a metal on a surface of a substrate, which comprises: (a) coating the surface with a sensitizing solution comprising at least a reducible salt of a non-noble metal and a radiation-sensitive reducing agent for said reducible salt to form a sensitized surface; (b) exposing said sensitized surface to a source of light radiant energy to reduce said metal salt to a reduced metal salt species, wherein at least one of said above steps (a) or (b) is restricted to a selected pattern on the surface to form a catalytic real image capable of catalyzing the deposition of a metal thereon from an electroless metal deposition solution; and (c) treating said catalytic real image, prior to exposing said real image to an electroless metal deposition solution, with a stabilizer comprising at least (a) a reducing agent for the non-noble metal ions of said reducible salt, (b) a complexing agent and (c) an accelerator comprising a compound containing a cyanide radical (CN - ) complexed with a metal selected from Group VIII of the Periodic Table of the Elements, to at least stabilize said catalytic real image.

Claim 2

A method for selectively depositing a metal on a surface of a substrate, which comprises: (a) coating the surface with a sensitizing solution comprising at least a reducible salt of a non-noble metal and a radiation-sensitive reducing agent for said reducible salt to form a sensitized surface; (b) exposing said sensitized surface to a source of light radiant energy to reduce said metal salt to a reduced metal salt species, wherein at least one of said above steps (a) or (b) is restricted to a selected pattern on the surface to form a catalytic real image capable of catalyzing the deposition of a metal thereon from an electroless metal deposition solution; and (c) treating said catalytic real image, prior to exposing said real image to an electroless metal deposition solution, with a stabilizer comprising at least (a) a reducing agent for the non-noble metal ions of said reducible salt, (b) a complexing agent and (c) an accelerator comprising a compound containing a cyanide radical (CN - ) complexed with a metal selected from Group VIII of the Periodic Table of the Elements, to at least stabilize said catalytic real image.

Claim 9

A method for selectively metallizing a surface of a substrate comprising the steps of: (a) depositing on the surface a layer of a sensitizing composition by treating the surface with a solution comprising at least a reducible salt of a non-noble metal and a radiation-sensitive reducing agent for said salt; (b) selectively exposing said layer-deposited surface to a source of light radiant energy to form a catalytic pattern on the surface which is capable of directly catalyzing the deposition thereon of a metal from an electroless metal deposition solution; and (c) treating said catalytic pattern, prior to removing radiation unexposed portions of said deposited layer, with a stabilizing solution comprising a reducing agent selective for the non-noble metal ions of the salt contained within said catalytic pattern, a complexing agent and an accelerator comprising a compound containing a cyanide radical (CN - ) complexed with a metal selected from Group VIII of the Periodic Table of the Elements, to stabilize the pattern.

Claim 10

A method for selectively metallizing a surface of a substrate comprising the steps of: (a) depositing on the surface a layer of a sensitizing composition by treating the surface with a solution comprising at least a reducible salt of a non-noble metal and a radiation-sensitive reducing agent for said salt; (b) selectively exposing said layer-deposited surface to a source of light radiant energy to form a catalytic pattern on the surface which is capable of directly catalyzing the deposition thereon of a metal from an electroless metal deposition solution; and (c) treating said catalytic pattern, prior to removing radiation unexposed portions of said deposited layer, with a stabilizing solution comprising a reducing agent selective for the non-noble metal ions of the salt contained within said catalytic pattern, a complexing agent and an accelerator comprising a compound containing a cyanide radical (CN - ) complexed with a metal selected from Group VIII of the Periodic Table of the Elements, to stabilize the pattern.

Claim 17

A method for making printed circuit boards, which comprises: (a) treating an electrically non-conductive base with a solution comprising a reducible salt of copper, a radiation-sensitive reducing compound and a secondary reducer; (b) exposing the treated base to light radiant energy in selected areas to reduce the metal salt to produce a reduced metal salt species in the form of a real image corresponding to the desired circuit pattern; (c) treating the exposed base, prior to removing radiation unexposed copper ions therefrom, with a stabilizing solution comprising (a') a reducing agent selected from the group consisting of formaldehyde, paraformaldehyde and a mixture thereof, (b') a complexing agent comprising ethylenediaminetetraacetic acid or a salt thereof, (c') an accelerator comprising a ferrocyanide salt and (d') a basic compound, to at least stabilize the real image; and (d) treating the stabilizing solution treated base with a solution comprising an organic acid selected from the group consisting of (a") a monocarboxylic acid having the structural formula ##STR2## where R is a member selected from the hydrogen atom, H, or an alkyl radical having 1 to 5 carbon atoms, (b") citric acid and (c") a mixture of (a") and (b") to remove essentially all remaining radiation-unexposed portions of said treated base; and (e) exposing the real image to an electroless metal deposition solution to deposit an electroless metal thereon.

Claim 18

A method for making printed circuit boards, which comprises: (a) treating an electrically non-conductive base with a solution comprising a reducible salt of copper, a radiation-sensitive reducing compound and a secondary reducer; (b) exposing the treated base to light radiant energy in selected areas to reduce the metal salt to produce a reduced metal salt species in the form of a real image corresponding to the desired circuit pattern; (c) treating the exposed base, prior to removing radiation unexposed copper ions therefrom, with a stabilizing solution comprising (a') a reducing agent selected from the group consisting of formaldehyde, paraformaldehyde and a mixture thereof, (b') a complexing agent comprising ethylenediaminetetraacetic acid or a salt thereof, (c') an accelerator comprising a ferrocyanide salt and (d') a basic compound, to at least stabilize the real image; and (d) treating the stabilizing solution treated base with a solution comprising an organic acid selected from the group consisting of (a") a monocarboxylic acid having the structural formula ##STR2## where R is a member selected from the hydrogen atom, H, or an alkyl radical having 1 to 5 carbon atoms, (b") citric acid and (c") a mixture of (a") and (b") to remove essentially all remaining radiation-unexposed portions of said treated base; and (e) exposing the real image to an electroless metal deposition solution to deposit an electroless metal thereon.

Claim 19

A method of depositing a metal pattern on a dielectric surface, which comprises: (a) treating the surface with a sensitizing solution comprising at least a reducible salt of copper and a radiation-sensitive reducing agent selected from the group consisting of anthraquinone, a derivative of anthraquinone, and a mixture of the foregoing, to sensitize the surface; (b) exposing said sensitized surface to a source of ultraviolet radiation to reduce the copper salt to a reduced copper species wherein at least step (a) or (b) is restricted to a selected pattern on the surface to produce a real image of the reduced copper species in the selected pattern which is capable of directly catalyzing the deposition thereon of a metal from an electroless metal deposition, and, following said exposing; (c) maintaining said real image containing surface in a stabilizing solution comprising formaldehyde, ethylenediaminetetraacetic acid or a salt thereof, potassium ferrocyanide and an alkali metal hydroxide to preserve said real image.

Claim 20

A method of depositing a metal pattern on a dielectric surface, which comprises: (a) treating the surface with a sensitizing solution comprising at least a reducible salt of copper and a radiation-sensitive reducing agent selected from the group consisting of anthraquinone, a derivative of anthraquinone, and a mixture of the foregoing, to sensitize the surface; (b) exposing said sensitized surface to a source of ultraviolet radiation to reduce the copper salt to a reduced copper species wherein at least step (a) or (b) is restricted to a selected pattern on the surface to produce a real image of the reduced copper species in the selected pattern which is capable of directly catalyzing the deposition thereon of a metal from an electroless metal deposition, and, following said exposing; (c) maintaining said real image containing surface in a stabilizing solution comprising formaldehyde, ethylenediaminetetraacetic acid or a salt thereof, potassium ferrocyanide and an alkali metal hydroxide to preserve said real image.