Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
  • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D11/00—Inks
  • C09D11/52—Electrically conductive inks
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/20—Conductive material dispersed in non-conductive organic material
  • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
  • H01B5/14—Non-insulated conductors or conductive bodies characterised by their form comprising conductive layers or films on insulating-supports
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K1/00—Printed circuits
  • H05K1/02—Details
  • H05K1/09—Use of materials for the conductive, e.g. metallic pattern
  • H05K1/092—Dispersed materials, e.g. conductive pastes or inks
  • H05K1/095—Dispersed materials, e.g. conductive pastes or inks for polymer thick films, i.e. having a permanent organic polymeric binder
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K1/00—Printed circuits
  • H05K1/02—Details
  • H05K1/09—Use of materials for the conductive, e.g. metallic pattern
  • H05K1/092—Dispersed materials, e.g. conductive pastes or inks
  • H05K1/097—Inks comprising nanoparticles and specially adapted for being sintered at low temperature
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
  • H05K3/12—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns
  • H05K3/1241—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns by ink-jet printing or drawing by dispensing

Definitions

• the present invention relates to low sintering temperatures conductive nano-inks and to a method for producing the same.
• Metal nano-powder materials are single phase or multi-phase polycrystals, with particle size in the order of a few nanometers (typically 1-100) in at least one dimension. It is well acknowledged that wherein conventional polycrystalline materials grain boundaries account for less than 1% of the volume, in nano structured materials can occupy as much as 50%. Nano particles, specially metal nano particles have hence very special properties which are directly related to their dimensions and to the fact that a large ratio of the atoms in the particle are in the surface of the particle or at particle and grain boundaries. These properties include optical properties, diffusion properties, electrical properties like capacitance, impedance and resistance, catalytic activity and many others.
• Nano-inks and nano-powders for coatings characterized by a significant electrical conductivity are useful, but not exclusively, for printing of electrical connections in circuits such as, antennas, smart tags, display panels, printed circuit boards, chips and others.
• U.S. Pat. No. 6,395,214 to Kear et al. discloses another approach and presents a method for fabricating a nano-crystalline ceramic article at respectively low temperature yet by applying very high pressures.
• their method comprises the steps of (i) synthesizing loosely-agglomerated ceramic nano-powder having a metastable structure; (if) forming the ceramic nano-powder into a compact; and than (Hi) sintering the ceramic nano-powder compact under a pressure of 3 GPa to 5.5 GPa and at a temperature no greater than about 0.6 times the melting temperature of the ceramic nano-powder to form the nano-crystalline article.
• a useful and cost effective method for sintering nano-particles, and especially electrically conductive nano-ink powders at respectively low temperatures and at ambient pressure is thus a significant industrial need.
• Fig.l The change of relative resistance for silver nano powders coated with surfactant (1) and washed from surfactant (2);
• Fig. 2 Relative resistance dependence on temperature for the different particle size silver powders - and measured bulk silver in our measuring system
• Fig. 3 Relative resistance dependence on temperature for the different particle size copper powders - and measured bulk copper in our measuring system.
• Said method comprising inter alia the following four steps: (i) admixing metal nano powder in a solvent with at least one ingredient of the group selected from: binder, surfactant, additive, polymer, buffer, dispersant and/or coupling agent in the manner a homogenized solution is obtained; (if) applying the homogenized mixture obtained above on a surface to be coated; ( ) evaporating the solvent from said homogenized mixture; and lastly and most importantly, (iv) sintering the coated layer at temperature range of 50°C to 350°C, providing a conductive ink on top of said surface characterized by resistances between 0.005 ⁇ /square to 5 ⁇ /square.
• Said sintering is preferably provided at ambient pressure (e.g., about atmospheric pressure).
• the sintering step is provided at temperature of about 50°C. Alternatively or additionally, it is in the scope of the present invention wherein the sintering step is provided for 0.5 to 2 hours.
• the present invention also relates to the aforementioned method, wherein the metal nano powder is selected from at least one of the group: metal nano powder; metal nano powder with metal colloids; metal nano powder with a metal reducible salt and/or organic metal complexes and/or organo-metal compounds which decompose to form conductive materials.
• the concentration of the metal nano-powder in the admixed solution may be between 1% (wt) to 70% (wt). More specifically, the concentration of the metal nano powder in the admixed solution may be between 2% (wt) to 50% (wt).
• the admixed solution comprising organic solvent or a mixture of organic solvents including UV and thermally curable monomers.
• concentration of the organic solvent or the mixture of organic solvents in the admixed solution is between 20%) (wt) to 85%> (wt). Most specifically, said range is between 40% (wt) to 80% (wt).
• the aforementioned solvent is preferably selected from at least one of the group of petroleum ether, hexane, heptanes, toluene, benzene, acrylates, dichloroethane, trichloroethylene, chloroform, dichloromethane, nitromethane, dibromomethane, cyclopentanone, cyclohexanone or any mixture thereof.
• concentration of the aforementioned binder in the admixed solution is preferably between 0% (wt) to 5% (wt).
• Said binder may be selected from ethyl cellulose and/or modified urea.
• the surface to be coated is selected from ceramics, glass, either flexible or relatively non-flexible polymeric films or sheets, polyimides, kepton, polyethylene products, polypropylene, acrylate containing products, polymethyl metaacryalte, e.g., PMMA or Perspex, their co-polymers or any combination thereof, or any printable substrate.
• the polymeric film comprising at least one of the group of polyesters, polyamides, polycarbonates, polyethylene, polypropylene, their copolymers or any combination thereof.
• the method is additionally comprises of a step of treating the surface to be coated by a means of corona treatment and/or coating by primer.
• a primer may be selected from at least one of the group of 3-aminopropyl triethoxy silane, phenyl trimethoxysilane, glycidyl trimethoxysilane, commercially available Tween products, Tween-80, neoalkoxy tri(dioctylpropylphosphato) titanate or any combination thereof.
• the nano-powder comprising metal or a mixture of metals selected from silver, gold, platinum, palladium, nickel, cobalt, copper or any combination thereof or any other conductive metal.
• said metal is admixed with metal colloids; metal nano powder with a metal reducible salt and/or organic metal complexes and/or organo-metal compounds which decompose to form conductive materials.
• the aforementioned method may comprise the step of polymerizing a monomer in the presence of catalyst and/or oxidizing agent and/or reducing agent, in the manner a water miscible polymer is obtained in the homogenized solution.
• the spreading of the homogenized mixture on a surface to be coated may be provided by a means selected from simple spreading; bar spreading, immersing; spin coating; doping and/or dipping.
• the coating layer or layers provided by the spreading of the homogenized mixture on a surface to be coated may be characterized by a wet thickness of 1 to 200 microns.
• the conductive nano-ink as defined above, printed or coated in a predetermined pattern, and to provide a self assembled conductive nano-ink.
• the conductive nano-ink especially adapted for post treatment of surface; wherein said treatment is selected from scratch resistance, increasing adhesion or a combination thereof.
• any conductive ink e.g., nano-powders characterized by resistances between 0.005 ⁇ /square to 5 ⁇ /square
• metal nano-powders obtained by the method defined in any of the above.
• a novel method of low temperature sintering useful for the production of conductive coatings and inks comprising metal nano-powders is hereby presented. It is according to the present invention that by coating a substrate with an ink, solution or paste that was previously dispersed, cost-effective nano conductive materials and/or conductive transparent coating are produced.
• the term 'coating' is referring according to the present invention to any conductive layer produced in the manner of admixing metal nano powder in a solvent with at least one ingredient of the group: binder, surfactant, additive, polymer, buffer, dispersant and/or coupling agent in the manner a homogenized solution is obtained; and then sintering at respectively low temperatures of 50 to 300°C.
• 'ink' is referring according to the present invention to any ink containing nano-powders of metal or metals, especially emulsion based compositions provided for coloring materials, or alternatively, to legend ink (marking ink) suitable for printing on printed circuit boards (PCB's).
• the term 'ink' is referring according to the present invention to any conductive topical pattern produced in the manner of admixing metal nano powder in a solvent with at least one ingredient of the group: binder, additive, polymer, buffer, dispersant and/or coupling agent in the manner a homogenized solution is obtained; the solution can be admixed, but not essential, with water or water miscible solvent or mixture of water miscible solvents in the manner a W/O type emulsion is obtained; spreading or printing the homogenized mixture obtained above on said surface to be coated; evaporating the solvent from said homogenized mixture in the manner that a self-assembled network-like pattern is developed in situ or a printed pattern or a complete coverage is formed; and than sintering the network-like pattern at respectively low temperatures of 50 to 300°C so a conductive and nano-ink is obtained.
• the inks can also especially be adapted for use in or on top of transparent substrates.
• the aforementioned ink is adapted for coating, covering, immersing, dipping, and/or entrapping on top or into either solid or semi-solid matrix, or by means of any other suitable technique on such as glass or any polymer matrix, including flexible, semi-flexible or rigid materials.
• the present invention discloses the novel properties of the nano metal powders and inks (i.e., conductive-polymers, as well as conductive metals, oxides characterized by D 50 ⁇ 60nm and D 0 ⁇ 100nm). Those properties enable the hereto-defined nano-powders to provide an industrial scale production of flexible electrical circuits on substrates such as polymer films and plastics.
• nano sized particles and grains that have much larger surface area than bulk materials, characterized by special diffusion properties and can be processed so continuous conductive phase is produced at relative low temperatures and lower energy input.
• nano metal powder or ink it is according to another embodiment of the present invention to coat a substrate with a nano metal powder or ink.
• a solution or paste in which the nano metal powder were dispersed and sintered at low temperatures of about 50°C and preferably around 100°C to 220°C, in the manner conductive layers characterized by resistances between 0.005 ⁇ /square to 5 ⁇ /square are obtained
• any type of substrates can be coated. More particularly, those substrates are selected, yet no limited to glass, poly-carbonate, polymer films or any combination thereof.
• Silver powders of different sizes were produced through the procedure described in U.S. Pat. No. 5,476,535, which is hereto provided as a reference.
• the powders are coated with organic materials and de-agglomerated.
• the volume particle size distribution of these powders, measured in a Coulter Particle Size Analyzer LS 230, are presented in Table 1.
• figure 1 presenting the change of relative resistance for silver nano powders coated with surfactant (1) and washed from surfactant (2).
• figure 2 presenting the relative resistance dependence on temperature for the different particle size silver powders - and measured bulk silver in our measuring system.
• Samples 1, 2 and 3 are nano silver powders; samples 4 and 5 are coarse silver powders with a particle size of over 2.5 ⁇ m (D 0 ). As can be seen nano silver powders achieve better conductivities at lower temperatures. A nano silver powder washed from its coating will give the same performance at even lower temperatures of about 100°C in comparison to around 220°C for the coated powder and over 700°C for coarse silver powders. Table 2: Electrical properties of silver powders
• Table 3 Electrical properties of different particle size silver powders at different sintering temperatures.
• Copper powders of different sizes were produced through the procedure described in U.S. Pat. No. 5,476,535, which is hereto provided as a reference.
• the powders were coated with organic materials and de-agglomerated.
• Nano metal powders in formulations are nano metal powders in formulations.
• the formulations are inks or pastes, which facilitate the printing and/or coating process, were prepared according to the general procedures described bellow. Care has to be taken to achieve a good dispersion of the conductive additives (metal nano powders, salts and/or colloids).
• ink/paste systems were tested. All three have been found to produce a conductive coating at low sintering temperatures.
• the systems differ in the formulation concept, and main ingredients leading to the conductivity.
• the main ingredients of the systems are: 1) metal nano powder, 2) metal nano powder with metal colloids, 3) metal nano powder with a metal reducible salt.
• Admixing a binder e.g., ethyl cellulose), 13% (wt/wt) in a solvent (e.g., terpinol). Then, admixing a conductive nano powder metal (e.g., silver nano powder) (D90 ⁇ 0.1 ⁇ m); 50 parts by weight; terpinol 20 parts by weight, and a coupling agent such as isopropyl dioleic(dioctylphosphato)titanate, also know a the commercially available NDZ-101 KRTTS, 1 parts by weight, to some 25 parts by weight of the solution obtained above, by a means of a high rpm homogenizer.
• a binder e.g., ethyl cellulose
• a solvent e.g., terpinol
• colloidal silver 12 parts by weight; a binder e.g., a binder which is an adhesion promoter, such as Polyvinyl Pyrrolidone (PVP), 2.5 parts by weight; water, 32 parts by weight by a means of an ultrasonic energy and or high rpm dispersing equipment.
• a binder e.g., a binder which is an adhesion promoter, such as Polyvinyl Pyrrolidone (PVP), 2.5 parts by weight
• water 32 parts by weight by a means of an ultrasonic energy and or high rpm dispersing equipment.
• a conductive nano powder metal e.g., silver nano powder
• solvent e.g., ethanol
• a conductive nano powder metal e.g., silver nano powder
• Table 5 Resistance data for nano metal powders ink formulations.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Composite Materials (AREA)
• Dispersion Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Physics & Mathematics (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Conductive Materials (AREA)
• Inks, Pencil-Leads, Or Crayons (AREA)
• Powder Metallurgy (AREA)

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• 2003
  • 2003-07-03 JP JP2004519139A patent/JP2005531679A/ja active Pending
  • 2003-07-03 WO PCT/IL2003/000554 patent/WO2004005413A1/en not_active Ceased
  • 2003-07-03 AU AU2003237578A patent/AU2003237578A1/en not_active Abandoned
  • 2003-07-03 CN CN03815904XA patent/CN1671805B/zh not_active Expired - Fee Related
  • 2003-07-03 KR KR1020047021518A patent/KR20060012545A/ko not_active Ceased

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