# US 9,439,293 B2 · Galvanic process for making printed conductive metal markings for chipless RFID applications > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,439,293 B2 - Document ID: US9439293B2 - Status: Granted - Kind: B2 - Application number: 11/943,774 - Filed: 2007-11-21 - Published: 2009-05-21 - Granted: 2016-09-06 - Earliest claimed: 2007-11-21 - Assignees: Xerox Corporation - Applicants: Naveen Chopra; Peter M. Kazmaier; Dominique J. Lalisse; Paul F. Smith - Inventors: Naveen Chopra; Peter M. Kazmaier; Dominique J. Lalisse; Paul F. Smith - Web page: https://patentgrep.com/patent/US9439293B2 ## CPC - H05K 3/125: {by ink-jet printing} - B41J 2/01: Ink jet - H05K 3/182: {characterised by the patterning method} - B05C 5/02: {the liquid or other fluent material being discharged through an outlet orifice by pressure, e.g.} from an outlet device in contact or almost in contact, with the work - H05K 3/12: using {thick film techniques, e.g.} printing techniques to apply the conductive material {or similar techniques for applying conductive paste or ink patterns} - H05K 2203/013: Inkjet printing, e.g. for printing insulating material or resist - H05K 2203/1157: Using means for chemical reduction - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS - B05C: APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (spraying apparatus, atomising apparatus, nozzles B05B; plant for applying liquids or other fluent materials to objects by electrostatic spraying B05B5/08) ## Abstract A process for printing a metal wire pattern on a substrate, including: printing a first salt solution including a metal ion that will undergo a reduction half-reaction; printing a second salt solution containing a reductant that will undergo an oxidation half-reaction in contact with the first salt solution, resulting in the reduction of the metal ions of the first salt solution; and allowing the first and second salt solutions to react by a galvanic reaction, causing reduced metal ions of the first salt solution to precipitate as a solid, on the substrate. ## Claims ### Claim 1 A method for printing a conductive metal wire pattern on a substrate, comprising: printing a homogenous first salt solution comprising a first solvent and a first metal ion, the first metal ion selected from the group consisting of copper, aluminum, magnesium, manganese, zinc, chromium, lead, cadmium, cobalt, nickel, gold, silver, platinum, tin, iron, and mixtures thereof; printing a homogeneous second salt solution comprising a second solvent and a second metal ion configured to reduce the homogeneous first salt solution, the second metal ion selected from the group consisting of iron (II), lead (II), chromium (II), mercury (II), platinum (IV), palladium (IV), nickel (III), and cobalt (III); and forming a metal wire pattern by the galvanic reaction on the substrate of the printed homogeneous first and the homogeneous second salt solutions to precipitate the first metal ion as solid metal nanoparticles having a size of about 5 nm to about 7 nm on the substrate; wherein: additional energy is not required to anneal the metal nanoparticles together and create the conductive metal wire pattern; the second metal ion has a lower reduction potential than the first metal ion; the first and/or second salt solutions are printed directly onto the substrate; the substrate is selected from the group consisting of paper, glass art paper, bond paper, paperboard, Kraft paper, cardboard, semi-synthetic paper, and plastic sheets; the printing of the first salt solution and the second salt solution is performed using a heated printer that deposits the first salt solution and the second salt solution onto the substrate in a flowable state; and after mixing and reacting, the first solvent of the first salt solution and the second solvent of the second salt solution evaporate to form the metal wire pattern by depositing the reduced first metal ion nanoparticle on the substrate. ### Claim 2 (depends on 1) The method according to claim 1, wherein the first metal ion in the homogenous first salt solution is copper (II). ### Claim 3 (depends on 1) The method according to claim 1, wherein the second metal ion is not an elemental metal. ### Claim 4 (depends on 1) The method according to claim 1, wherein the second metal ion is chromium (II). ### Claim 5 (depends on 1) The method according to claim 1, wherein the homogeneous first salt solution and the homogenous second salt solution are printed via a printing method selected from the group consisting of inkjet, screen printing, gravure, rotogravure, and flexography. ### Claim 6 (depends on 5) The method according to claim 5, wherein the homogeneous first salt solution and the homogeneous second salt solution are printed by an inkjet printer. ### Claim 7 (depends on 6) The method according to claim 6, wherein: the homogeneous first salt solution contains copper (II) as the first metal ion; and the second salt solution contains chromium (II) as the second metal ion. ### Claim 8 (depends on 5) The method according to claim 5, wherein the two homogenous salt solutions are printed in a manner such that one salt solution fully overlaps the other solution. ### Claim 9 (depends on 5) The method according to claim 5, wherein the two homogeneous salt solutions are printed in a manner such that the two salt solutions only partially overlap. ### Claim 10 (depends on 5) The method according to claim 5, wherein the two homogeneous salt solutions are printed via a two-pass process, whereby the inkjet printer prints one homogeneous salt solution during the first pass over the substrate, and then prints the other homogeneous salt solution during a subsequent second pass over the substrate. ### Claim 11 (depends on 5) The method according to claim 5, wherein the two homogeneous salt solutions are printed during a single pass of the inkjet printer over the substrate. ### Claim 12 (depends on 1) A method of printing resonant antennae in chipless RFID applications, comprising the method of claim 1. ### Claim 13 (depends on 1) The method according to claim 1, wherein the second metal ion is lead (II). ### Claim 14 (depends on 1) The method according to claim 1, wherein the second ionic metal species in the homogeneous second salt solution is provided in the form of a metal salt selected from the group consisting of metal sulfates, metal halides, metal acetates, metal oxides, metal carbonates, metal hydroxides, metal oxalates, metal pyrazolyl borates, metal azides, metal fluoroborates, metal carboxylates, metal halogencarboxylates, metal hydroxycarboxylates, metal aminocarboxylates, metal aromatics, which may optionally be nitro and/or fluoro substituted aromatic carboxylates, metal beta diketonates, and metal sulfonates. ### Claim 15 (depends on 1) The method of claim 1, wherein at least one of the first solvent and the second solvent has a melting point of at least 30° C. and less than or equal to 100° C. ### Claim 16 A method of printing a conductive metal wire on a substrate, comprising: depositing a first ionic metal solution comprising a first solvent and an oxidizing first metal ion directly onto a substrate, the first metal ion selected from the group consisting of copper, aluminum, magnesium, manganese, zinc, chromium, lead, cadmium, cobalt, nickel, gold, silver, platinum, tin, iron, and mixtures thereof; and depositing a second ionic metal solution comprising a second solvent and a reducing second metal ion directly onto the substrate, the second metal ion selected from the group consisting of iron (II), lead (II), chromium (II), mercury (II), platinum (IV), palladium (IV), nickel (III), and cobalt (III), the second ionic metal solution configured to reduce the first ionic metal solution; and forming a metal wire on the substrate by the galvanic reaction on the substrate of the deposited first and second ionic solutions to precipitate a reduced solid metal form of the first metal ion on the substrate, the solid metal form comprising metal nanoparticles having a size of about 5 nm to about 7 nm, wherein at least one of the first and second ionic solutions are deposited on the substrate in a flowable form using a heated printer head, wherein additional energy is not required to anneal the metal nanoparticles together and create the conductive metal wire, and wherein the reducing second metal ion has a lower reduction potential than the oxidizing first metal ion. ### Claim 17 (depends on 16) The method of printing a conductive metal wire on a substrate of claim 16, wherein a width of the metal wire is controlled by an overlap amount of the deposited first and second ionic solutions. ### Claim 18 (depends on 16) The method of printing a conductive metal wire on a substrate of claim 16, wherein the first and second solvent mix upon deposition on the substrate and react under a galvanic reaction to precipitate the reduced first metal ion nanoparticle. ### Claim 19 (depends on 18) The method of printing a conductive metal wire on a substrate of claim 18, further comprising: evaporating the first and second solvents from the substrate to deposit the metal wire comprising the reduced first metal ion nanoparticle. ### Claim 20 (depends on 16) The method of printing a conductive metal wire on a substrate of claim 16, wherein the conductive metal wire has a thickness of about 0.01 μm to about 5 μm and a print resistance of about 10 Ohms/square to about 10,000 Ohms/square.