JP5089557B2 - Method for forming electromagnetic wave shielding wiring circuit and electromagnetic wave shielding sheet - Google Patents

Description

  The present invention relates to a method for forming an electromagnetic shielding wiring circuit using a copper fine particle dispersion and an electromagnetic shielding sheet.

A plasma display panel (hereinafter referred to as PDP) has a larger amount of electromagnetic waves radiated from the front of the panel when emitting light than a cathode ray tube or a liquid crystal display, and it is necessary to mount an electromagnetic shielding filter on the panel surface.
As a conventional electromagnetic wave shielding filter, a filter in which a metal thin film is formed in a mesh-like wiring pattern on the surface of a plastic substrate is known. From the viewpoints of preventing reflection from outside light and not affecting the color tone of the display, the wiring of such an electromagnetic wave shielding filter is a metal wire colored black, or a metal whose surface is blackened Alternatively, a metal wire having a black layer on the surface is desirable.

  As a method for forming a mesh-like wiring pattern, a photolithography technique is used in which a series of processes such as attaching a copper foil on a substrate, forming a metal film by silver sputtering, applying a resist, exposing, developing, and etching are performed. ing. However, this method has a problem that the number of steps is extremely large and the manufacturing cost is high.

  Therefore, in Patent Document 1, a metal fine particle dispersion containing metal fine particles having an average particle diameter of 100 nm or less and black inorganic fine particles having an average particle diameter of 300 nm or less is printed on a substrate by an inkjet method or the like. After that, a method of forming a wiring by heat treatment or baking by laser irradiation has been proposed. Such a wiring forming method is applied to a wiring of an address electrode or a bus electrode of a PDP or a liquid crystal display panel. It is described that it is used for the formation of.

  However, the above-mentioned metal fine particle dispersion has a problem that the metal fine particles in the dispersion medium are likely to aggregate, and the dispersibility of the fine particles is inferior, so that the storage stability and ejection stability when used as an inkjet ink are inferior. . Then, although the method of protecting the surface with a dispersing agent is considered, since it is dispersed together with inorganic fine particles that are pigments, depending on the inorganic particles to be blended, the dispersing agent of the metal fine particles is preferentially coordinated with the inorganic particles, It does not act as a dispersant, and the discharge stability is significantly lowered by the coarsened composite particles of metal fine particles and inorganic fine particles.

For such problems, various dispersions in which metal fine particles whose surfaces are coated with a polymer compound are dispersed in a dispersion medium have been proposed as metal fine particle dispersions with improved dispersibility and ejection stability. Yes. For example, Patent Document 2 proposes forming a circuit pattern using a metal fine particle dispersion in which the surface of metal nanoparticles is coated with an organic compound and stably dispersed in an organic solvent.
JP 2006-169592 A JP 2002-299833 A

  As metal fine particles used as an electromagnetic shielding wiring circuit for PDP, the metal material itself is much cheaper than gold, silver, nickel, etc., and is caused by electromigration like when using silver. From the viewpoint of avoiding a short circuit between wirings, it is desirable to use copper.

  However, when using a dispersion of fine particles of copper, copper alloy, or copper compound (hereinafter simply referred to as copper fine particles), the copper is oxidized and reduced in conductivity when heated in an oxidizing atmosphere, so that the inert gas atmosphere Or it is necessary to heat in reducing gas atmosphere, such as hydrogen gas. For this reason, when the surface of the copper fine particles is covered with a thick polymer compound layer, the high heat-resistant polymer is difficult to be decomposed in an inert gas or reducing gas atmosphere in which oxygen is not present. Sintering between the copper fine particles is hindered, and the finally obtained sintered wiring has insufficient conductivity.

In order to improve the electrical conductivity, it is conceivable that the polymer compound is baked at a high temperature that sublimates the polymer compound. When baking at such a high temperature, a plastic substrate having a low heat resistance temperature is used as a substrate on which the dispersion is applied. Cannot be used, and it is difficult to apply to the electromagnetic wave shielding wiring circuit for PDP.
In Patent Document 2, it is described that a circuit pattern can be formed at a firing temperature of 250 ° C. or lower when silver is used as the metal nanoparticle. However, there is no problem with using copper as the metal nanoparticle. Not considered. That is, when using copper fine particles, it is necessary to heat in an inert gas atmosphere or a reducing gas atmosphere such as hydrogen gas unlike when using silver that is not easily oxidized, thereby covering the copper fine particles. It is difficult for the polymer to be decomposed by low-temperature sintering, and it is not considered that the conductivity of the sintered wiring becomes insufficient, and it cannot be applied to a plastic substrate having a low heat-resistant temperature.

  Accordingly, an object of the present invention is to provide an electromagnetic wave shielding wiring circuit forming method and an electromagnetic wave shielding sheet capable of realizing an electromagnetic wave shielding wiring circuit using copper that is inexpensive and does not cause electromigration. .

In the first aspect of the present invention, copper fine particles are
(I) 5 to 90% by volume of an organic solvent (A) having an amide compound, 5 to 45% by volume of an organic solvent (B) having a boiling point of 20 ° C. or higher at normal pressure and 17 or more donors, A dispersion medium having an organic solvent (C) of 5 to 90% by volume having a boiling point at normal pressure exceeding 100 ° C. and comprising alcohol and / or polyhydric alcohol, from the organic solvents (A) to (C) A dispersion medium (S1) containing 90% by volume or more of
(Ii) 20 to 95% by volume of an organic solvent (A) having an amide-based compound, 5 to 80% by volume of an organic solvent (C) having a boiling point exceeding 100 ° C. at normal pressure and comprising alcohol and / or a polyhydric alcohol A dispersion medium containing 90% by volume or more of the component consisting of the organic solvents (A) and (C) (S2) ,
( Iv) 24 to 64% by volume of an organic solvent (A) having an amide compound, 5 to 39% by volume of a low-boiling organic solvent (B) having a boiling point of 20 to 100 ° C. at normal pressure, and a boiling point at normal pressure There exceed 100 ° C., and met dispersion medium containing an alcohol and / or a polyhydric organic solvent (C) 30 to 70% by volume composed of an alcohol and an organic solvent (E) 1 to 40 vol% with an amine compound A dispersion medium (S4) containing 90% by volume or more of the component consisting of the organic solvents (A) to (C) and (E ),
(V) 30 to 94% by volume of an organic solvent (A) having an amide-based compound, and 30 to 94% by volume of an organic solvent (C) having a boiling point exceeding 100 ° C. at normal pressure and comprising an alcohol and / or a polyhydric alcohol. , A dispersion medium containing 1 to 40% by volume of an organic solvent (E) having an amine compound , wherein the component comprising the organic solvents (A), (C) and (E) is contained by 90% by volume or more. dispersion media are (S5), and (vi) a boiling point of greater than 100 ° C. at normal pressure, and alcohol and / or organic solvent (C) and 80 to 90 volume percent composed of polyhydric alcohols, organic solvents having an amine compound (E) Dispersion medium containing 10 to 20% by volume , wherein the dispersion medium (S6) contains 90% by volume or more of the organic solvent (C) and (E ).
A step of adjusting the copper fine particle dispersion by dispersing in a dispersion medium (S) selected from:
Applying or printing the copper fine particle dispersion on a substrate or a black layer formed on the substrate to form a wiring pattern comprising a liquid film of the copper fine particle dispersion; and
And forming a sintered wiring layer by baking a liquid film of the copper fine particle dispersion.
The number of donors is defined by the formation enthalpy of the 1: 1 complex formation equilibrium of SbC15 and (electron-donating) solvent molecules in 1,2-dichloroethane measured by calorimetry -ΔH (kcal / mol).

  According to a second aspect of the present invention, in the method for forming an electromagnetic wave shielding wiring circuit according to the first aspect, the method further includes a step of forming a black layer on the sintered wiring layer.

  According to a third aspect of the present invention, in the method for forming an electromagnetic wave shielding wiring circuit according to the second aspect, the black layer is formed by overlaying a pigment dispersion containing a black inorganic pigment on the sintered wiring layer. It is formed by coating or printing.

  According to a fourth aspect of the present invention, in the method for forming an electromagnetic shielding wiring circuit according to any one of the first to third aspects, the coating or printing is performed by an ink jet method or a screen printing method. To do.

In a fifth aspect of the present invention, copper fine particles are
(I) 5 to 90% by volume of an organic solvent (A) having an amide compound, 5 to 45% by volume of an organic solvent (B) having a boiling point of 20 ° C. or higher at normal pressure and 17 or more donors, A dispersion medium having an organic solvent (C) of 5 to 90% by volume having a boiling point at normal pressure exceeding 100 ° C. and comprising alcohol and / or polyhydric alcohol, from the organic solvents (A) to (C) A dispersion medium (S1) containing 90% by volume or more of
(Ii) 20 to 95% by volume of an organic solvent (A) having an amide-based compound, 5 to 80% by volume of an organic solvent (C) having a boiling point exceeding 100 ° C. at normal pressure and comprising alcohol and / or a polyhydric alcohol A dispersion medium containing 90% by volume or more of the component consisting of the organic solvents (A) and (C) (S2) ,
( Iv) 24 to 64% by volume of an organic solvent (A) having an amide compound, 5 to 39% by volume of a low-boiling organic solvent (B) having a boiling point of 20 to 100 ° C. at normal pressure, and a boiling point at normal pressure There exceed 100 ° C., and met dispersion medium containing an alcohol and / or a polyhydric organic solvent (C) 30 to 70% by volume composed of an alcohol and an organic solvent (E) 1 to 40 vol% with an amine compound A dispersion medium (S4) containing 90% by volume or more of the component consisting of the organic solvents (A) to (C) and (E ),
(V) 30 to 94% by volume of an organic solvent (A) having an amide-based compound, and 30 to 94% by volume of an organic solvent (C) having a boiling point exceeding 100 ° C. at normal pressure and comprising an alcohol and / or a polyhydric alcohol. , A dispersion medium containing 1 to 40% by volume of an organic solvent (E) having an amine compound , wherein the component comprising the organic solvents (A), (C) and (E) is contained by 90% by volume or more. dispersion media are (S5), and (vi) a boiling point of greater than 100 ° C. at normal pressure, and alcohol and / or organic solvent (C) and 80 to 90 volume percent composed of polyhydric alcohols, organic solvents having an amine compound (E) Dispersion medium containing 10 to 20% by volume , wherein the dispersion medium (S6) contains 90% by volume or more of the organic solvent (C) and (E ).
A step of adjusting the copper fine particle dispersion by dispersing in a dispersion medium (S) selected from:
Applying or printing the copper fine particle dispersion on a substrate to form a wiring pattern comprising a liquid film of the copper fine particle dispersion; and
A step (b) of applying or printing a pigment dispersion containing a black inorganic pigment on the liquid film of the copper fine particle dispersion;
A wiring circuit for shielding electromagnetic waves, comprising: baking a liquid film of the copper fine particle dispersion and a pigment dispersion to form a sintered wiring having a two-layer structure including a copper sintered layer and a black layer. It is the formation method.

  According to a sixth aspect of the present invention, in the method for forming an electromagnetic wave shielding wiring circuit according to the fifth aspect, the step (b) is performed after the step (a). Of forming a wiring circuit for shielding electromagnetic waves.

  According to a seventh aspect of the present invention, in the method for forming an electromagnetic wave shielding wiring circuit according to the fifth or sixth aspect, the coating or printing is performed by an ink jet method or a screen printing method.

  According to an eighth aspect of the present invention, there is provided a protection provided on both the wiring circuit formed by the electromagnetic shielding wiring circuit forming method according to any one of the first to seventh aspects and the upper and lower surfaces of the wiring circuit. An electromagnetic wave shielding sheet comprising a film.

  In the method for forming an electromagnetic wave shielding wiring circuit of the present invention, copper fine particles are mixed with an organic solvent (A) having an amide compound and an organic solvent having a boiling point of 20 ° C. or higher at normal pressure and a donor number of 17 or higher. A dispersion medium containing B), an organic solvent (C) having a boiling point of more than 100 ° C. at normal pressure, and an alcohol and / or a polyhydric alcohol, and an organic solvent (E) having an amine compound in a specific ratio. Using the copper fine particle dispersion liquid dispersed in (S), an electromagnetic wave shielding wiring circuit is formed. By dispersing copper fine particles in a dispersion medium containing such a specific organic solvent, the fine particles can be obtained without coating the surface of the copper fine particles with a polymer compound or only with a relatively small amount of the polymer compound. The dispersibility of the resin can be improved, and coating or printing on the substrate can be performed stably. Then, by using a dispersion of copper fine particles that are not coated with a high molecular compound or coated with a relatively small amount of the high molecular compound, the inhibition factor of sintering between the copper fine particles is eliminated or reduced. And low temperature firing is possible. As a result, it can be applied to a plastic substrate having a low heat-resistant temperature, and an electromagnetic shielding wiring circuit using copper that is inexpensive and does not cause electromigration can be realized. The electromagnetic wave shielding wiring circuit formed by the method for forming an electromagnetic wave shielding wiring circuit of the present invention is excellent in conductivity even when fired at a low temperature, and can exhibit good shielding performance. In addition, by applying the method for forming an electromagnetic wave shielding wiring circuit according to the present invention, the manufacturing cost of the electromagnetic wave shielding sheet can be reduced, which contributes to lowering the cost of electronic equipment such as a plasma display panel on which the sheet is mounted. It becomes possible to do.

(First embodiment)
An electromagnetic shielding wiring circuit forming method according to the first embodiment of the present invention includes:
Copper fine particles
(I) an organic solvent (A) having an amide compound, an organic solvent (B) having a boiling point of 20 ° C. or higher at normal pressure and a donor number of 17 or higher, and a boiling point of 100 ° C. or higher at normal pressure; And a dispersion medium (S1) containing an organic solvent (C) composed of an alcohol having 1 or 2 or more hydroxyl groups in the molecule and / or a polyhydric alcohol,
(Ii) an organic solvent (C) having an amide compound and an organic solvent (C) having an alcohol and / or a polyhydric alcohol having a boiling point exceeding 100 ° C. and having one or more hydroxyl groups in the molecule. A dispersion medium (S2) containing
(Iii) Dispersion medium (S3) containing an organic solvent (C) consisting of an alcohol and / or a polyhydric alcohol having a boiling point at normal pressure exceeding 100 ° C. and having one or more hydroxyl groups in the molecule,
(Iv) 24 to 64% by volume of an organic solvent (A) having an amide compound, 5 to 39% by volume of a low boiling point organic solvent (B) having a boiling point of 20 to 100 ° C. at normal pressure, and a boiling point at normal pressure Is a dispersion medium (S4) containing 30 to 70% by volume of an organic solvent (C) composed of alcohol and / or polyhydric alcohol and 1 to 40% by volume of an organic solvent (E) having an amine compound. ),
(V) 30 to 94% by volume of an organic solvent (A) having an amide-based compound, and 30 to 94% by volume of an organic solvent (C) having a boiling point exceeding 100 ° C. at normal pressure and comprising an alcohol and / or a polyhydric alcohol. , A dispersion medium (S5) containing 1 to 40% by volume of an organic solvent (E) having an amine compound, and (vi) an organic solvent composed of an alcohol and / or a polyhydric alcohol having a boiling point exceeding 100 ° C. at normal pressure Dispersion medium (S6) containing 60 to 99% by volume of solvent (C) and 1 to 40% by volume of organic solvent (E) having an amine compound
A step of adjusting the copper fine particle dispersion by dispersing in a dispersion medium (S) selected from:
Applying or printing the copper fine particle dispersion on a substrate or a black layer formed on the substrate to form a wiring pattern comprising a liquid film of the copper fine particle dispersion; and
Including a step of firing the copper fine particle dispersion liquid film to form a sintered wiring layer as an essential step,
Furthermore, it includes a step of forming a black layer on the substrate or the sintered wiring layer as necessary.
Below, the formation method of the wiring circuit for electromagnetic wave shielding which concerns on the 1st Embodiment of this invention is demonstrated.

(Copper fine particle dispersion)
First, each component of the copper fine particle dispersion of the present invention will be described.
-Copper fine particles-
The copper fine particles of the present invention include fine particles of copper, a copper alloy, and a copper compound, and the copper compound contains an oxide of copper and a copper alloy. Copper particles that are transition metal particles do not contain any oxides at all, and the oxidation level in this case varies depending on the atmosphere, temperature, and holding time during particle generation and storage, but only the outermost surface of the particles. If it is thinly oxidized and the inside remains metal, the fine particles may be mostly oxidized. The copper compound referred to in the present invention contains all such particles in various oxidation states.

-Organic solvent (A)-
The organic solvent (A) is an amide compound having an amide group (—CONH—) or an organic solvent containing an amide compound, which improves dispersibility and storage stability in a dispersion medium, and further provides copper fine particles. It has the effect | action which improves board | substrate adhesiveness, when it bakes on a board | substrate in the state containing this.

  As the amide compound, one having a particularly high relative dielectric constant is preferable. As amide compounds, N-methylacetamide (191.3 at 32 ° C), N-methylformamide (182.4 at 20 ° C), N-methylpropanamide (172.2 at 25 ° C), formamide (111.0 at 20 ° C), N, N -Dimethylacetamide (37.78 at 25 ° C), 1,3-dimethyl-2-imidazolidinone (37.6 at 25 ° C), N, N-dimethylformamide (36.7 at 25 ° C), 1-methyl-2-pyrrolidone (32.58) at 25 ° C.), hexamethylphosphoric triamide (29.0 at 0 ° C.), 2-pyrrolidinone, ε-caprolactam, acetamide, and the like. The number in parentheses after the amide compound name indicates the relative dielectric constant at the measurement temperature of each solvent. Among these, N-methylacetamide, N-methylformamide, formamide, acetamide and the like having a relative dielectric constant of 100 or more can be preferably used. In addition, when it is solid at normal temperature like N-methylacetamide (melting point: 26-28 degreeC), it can mix with another solvent and can be used as a liquid state at working temperature.

-Organic solvent (B)-
The organic solvent (B) is an organic compound having a boiling point of 20 ° C. or higher at normal pressure and a donor number of 17 or higher. When the fine particle dispersion containing the organic solvent (B) is stored at room temperature when the boiling point at normal pressure is less than 20 ° C., the components of the organic solvent (B) easily volatilize and the solvent composition in the dispersion changes. There is a risk of it. In addition, when the boiling point at normal pressure is low, it can be expected that the effect of further reducing the dispersibility of the fine particles by reducing the mutual attractive force between solvent molecules due to the addition of the solvent can be expected. When the number of donors is less than 17, the electron pair donating property is lower than that of water, and when water is mixed as an impurity, the influence of the interaction between the copper particles and water becomes strong, and particle oxidation is liable to occur.

  In addition, when the boiling point in a normal pressure is 200 degrees C or less, it can be anticipated that the effect of reducing the mutual attractive force between solvent molecules by adding the solvent and further improving the dispersibility of the fine particles can be expected.

  In addition, when the electron donating property is high, the electrons are donated to the copper particles and molecules coordinated around the copper particles, and the negative chargeability of the copper particles is expanded, and the electrostatic repulsive force between the particles is increased. Have. Among the organic solvents (B), the ether compound (B1) is particularly preferable because it has a good balance between the boiling point and the number of donors, reduces the interaction between the solvent molecules, and has a large effect of donating electrons.

  Further, when the organic solvent (B) is used, it is possible to remarkably shorten the stirring time when preparing the fine particle dispersion by irradiation with ultrasonic waves, for example, to about 1/2. Further, when the organic solvent (B) is present in the mixed organic solvent, it can be easily redispersed even if the fine particles once become an aggregated state.

  As the organic solvent (B), an ether compound (B1) represented by the general formula R1-O-R2 (R1 and R2 each independently represents an alkyl group and has 1 to 4 carbon atoms), Alcohol (B2) represented by formula R3-OH (R3 is an alkyl group and has 1 to 4 carbon atoms), general formula R4-C (= O) -R5 (R4 and R5 are respectively And a ketone compound (B3) represented by an alkyl group independently having 1 to 2 carbon atoms) and a general formula R6- (N-R7) -R8 (R6, R7, R8 are each independently And an amine group compound (B4) represented by an alkyl group or a hydrogen atom and having 0 to 2 carbon atoms. Examples of the organic solvent (B) are shown below, but the number in parentheses after the compound name indicates the boiling point at normal pressure.

  Examples of the ether compound (B1) include diethyl ether (35 ° C.), methyl propyl ether (31 ° C.), dipropyl ether (89 ° C.), diisopropyl ether (68 ° C.), methyl t-butyl ether (55.3 ° C.). ), T-amyl methyl ether (85 ° C.), divinyl ether (28.5 ° C.), ethyl vinyl ether (36 ° C.), allyl ether (94 ° C.) and the like.

  As said alcohol (B2), methanol (64.7 degreeC), ethanol (78.0 degreeC), 1-propanol (97.15 degreeC), 2-propanol (82.4 degreeC), 2-butanol (100 degreeC) ), 2-methyl 2-propanol (83 ° C.) and the like.

Examples of the ketone compound (B3) include acetone (56.5 ° C.), methyl ethyl ketone (79.5 ° C.), diethyl ketone (100 ° C.) and the like.
Examples of the amine compound (B4) include triethylamine (89.7 ° C.) and diethylamine (55.5 ° C.).

-Organic solvent (C)-
The organic solvent (C) is an organic compound composed of an alcohol and / or a polyhydric alcohol having a boiling point exceeding 100 ° C. and having one or two or more hydroxyl groups in the molecule. Both alcohols have boiling points exceeding 100 ° C. at normal pressure. Further, alcohols having 5 or more carbon atoms and polyhydric alcohols having 2 or more carbon atoms are preferable, and those having a high relative dielectric constant, such as those having 10 or more, are liquid at room temperature.

  The mixed organic solvent containing the organic solvent (A) and the organic solvent (B) has excellent dispersibility by stirring, but generally the fine particles tend to adhere to each other over time in the organic solvent. When the organic solvent (C) is present in the mixed organic solvent, it is possible to suppress such bonding more effectively, thereby improving the dispersibility of the copper fine particles and improving the long-term stability of the dispersion. In addition, the uniformity of the finally obtained sintered wiring can be improved. In addition, the organic solvent (C) has an advantage that a reducing gas atmosphere is not required in the firing step described later because a reducing substance can be generated at the time of thermal decomposition and the oxide film of the copper fine particles can be reduced. .

  Specific examples of the organic solvent (C) include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol. -L, 1,4-butanediol, 2-butene-1,4-diol, 2,3-butanediol, pentanediol, hexanediol, octanediol, glycerol, 1,1,1-tris Examples include hydroxymethylethane, 2-ethyl-2-hydroxymethyl-1,3-propanediol, 1,2,6-hexanetriol, 1,2,3-hexanetriol, 1,2,4-butanetriol and the like. .

  Sugar alcohols such as D-Threitol, Erythritol, Pentaerythritol, Pentitol and Hexitol can also be used. Yes, pentitol includes xylitol, ribitol, and arabitol. Examples of hexitol include mannitol, sorbitol, dulcitol and the like. Furthermore, glyceraldehyde (Glyceric aldehyde), dioxyacetone (Dioxy-acetone), threose (threose), erythrulose (Erythrulose), erythrose (Erythrose), arabinose (Arabinose), ribose (Ribose), ribulose (Ribulose), xylose ( Xylose, Xylulose, Lyxose, Glucose, Fructose, Mannose, Idose, Sorbose, Gulose, Talose ), Tagatose, Galactose, Allose, Altrose, Lactose, Xylose, Arabinose, Isomaltose Sugars such as Gluco-heptose, Heptose, Maltotriose, Lactulose, and Trehalose can also be used.

  Among the alcohols, polyhydric alcohols having two or more hydroxyl groups in the molecule are more preferable, and ethylene glycol (Ethylene glycol) and glycerin (Glycerin) are particularly preferable.

-Organic solvent (E)-
The organic solvent (E) is an aliphatic primary amine, aliphatic secondary amine, aliphatic tertiary amine, aliphatic unsaturated amine, alicyclic amine, aromatic amine having a boiling point of 20 ° C. or higher at normal pressure. And one or more amine compounds selected from alkanolamines, or an organic solvent containing these amine compounds.

As amine compounds, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, n-butylamine, t-propylamine, t-butylamine, ethylenediamine, propylenediamine, tetramethylenediamine, tetramethylpropylene Diamine, pentamethyldiethylenetriamine, mono-n octylamine, mono-2ethylhexylamine, di-noctylamine, di-2ethylhexylamine, tri-noctylamine, tri-2ethylhexylamine, triisobutylamine, trihexylamine, Triisooctylamine, triisononylamine, triphenylamine, dimethyl coconutamine, dimethyloctylamine, dimethyldecylamine, dimethyllaur Ruamine, dimethylmyristylamine, dimethylpalmitylamine, dimethylstearylamine, dimethylbehenylamine, dilaurylmonomethylamine, diisopropylethylamine, methanolamine, dimethanolamine, trimethanolamine, ethanolamine, diethanolamine, triethanolamine, propanolamine, Isopropanolamine, diisopropanolamine, triisopropanolamine, butanolamine, N-methylethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, N-ethylethanolamine, N-ethyldiethanolamine, N, N-diethylethanol Amines, Nn-butylethanolamine, Nn-butyldiethanolamine, and 2- (2-a Examples include minoethoxy) ethanol and the like.
When the amine compound is a gas or a solid at room temperature, it can be dissolved in another solvent and used as a liquid at the working temperature.

-Dispersion medium (S)-
The dispersion medium (S) is selected from any of the following dispersion media (S1) to (S2).

-Dispersion medium (S1)-
The dispersion medium (S1) is a mixed organic solvent containing the organic solvent (A), the organic solvent (B), and the organic solvent (C). The amount of each organic solvent in the dispersion medium (S1) is 5 to 90% by volume for the organic solvent (A), 5 to 45% by volume for the organic solvent (B), and 5 to 90% by volume for the organic solvent (C). It is preferable that

  The organic solvent (A), the organic solvent (B), and the organic solvent (C) may be blended so that the blending ratio is 100% by volume, and further within the range of the blending ratio, Other organic solvent components may be blended within a range that does not impair the effect. In this case, 90% by volume or more of the component consisting of the organic solvent (A), the organic solvent (B), and the organic solvent (C) is included. It is preferable that it is 95 volume% or more.

  When other organic solvent components other than the above are blended, it is preferable to use polar organic solvents such as tetrahydrofuran, diglyme, ethylene carbonate, propylene carbonate, sulfolane, dimethyl sulfoxide and the like.

  By dispersing the copper fine particles in the dispersion medium (S1) containing such a specific organic solvent (A), organic solvent (B), and organic solvent (C), a polymer compound is substantially present on the surface. Or the weight ratio (D / P) of the polymer dispersant (D) to the copper fine particles (P) is in the range of 0 <D / P <0.01, and the polymer dispersant (D) on the surface Even if the copper fine particles are attached, the dispersibility of the fine particles can be improved. By using a dispersion of copper fine particles that are substantially free of polymer compounds on the surface or that have a very small amount of high-molecular compound attached thereto, the factors that inhibit sintering of copper fine particles are eliminated. Alternatively, since it can be reduced, low-temperature firing is possible in the firing step described later. And, by applying and baking the copper fine particle dispersion using the dispersion medium (S1) on the object to be coated, the electroconductivity is high even in low-temperature firing and excellent adhesion to the object to be coated. A sintered body can be obtained.

  In order to effectively exhibit such characteristics, the amount of the organic solvent (A) in the dispersion medium (S1) is more preferably 50 to 90% by volume, and further preferably 60 to 80% by volume. The blending amount of (B) is more preferably 5 to 40% by volume, still more preferably 10 to 30% by volume, and the blending amount of the organic solvent (C) is more preferably 5 to 45% by volume, and 10 to 30%. Volume% is more preferable.

-Dispersion medium (S2)-
The dispersion medium (S2) is a mixed organic solvent containing the organic solvent (A) and the organic solvent (C). The blending amount of each organic solvent in the dispersion medium (S2) is preferably 5 to 95% by volume for the organic solvent (A) and 5 to 95% by volume for the organic solvent (C).

  In the dispersion medium (S2), the organic solvent (A) and the organic solvent (C) may be blended so that the blending ratio is 100% by volume, and further within the range of the blending ratio, the present invention. You may mix | blend another organic solvent component in the range which does not impair the effect of this. In this case, it is preferable that the component which consists of an organic solvent (A) and an organic solvent (C) is 90 volume% or more, and 95 volume% or more is more preferable.

  When other organic solvent components other than the above are blended, polar organic solvents such as tetrahydrofuran, diglyme, ethylene carbonate, propylene carbonate, sulfolane and dimethyl sulfoxide can be used.

  By dispersing the copper fine particles in the dispersion medium (S2) containing such a specific organic solvent (A) and organic solvent (C), the dispersibility of the fine particles can be improved in the same manner as the dispersion medium (S1). In the firing step described later, low temperature firing is possible. Furthermore, even if it is low-temperature baking, the electroconductivity and the sintered compact which was excellent in the adhesiveness with respect to a to-be-coated body can be obtained.

  In order to effectively exhibit such characteristics, the blending amount of the organic solvent (A) in the dispersion medium (S2) is more preferably 50 to 90% by volume, and further preferably 60 to 80% by volume. 10-50 volume% is more preferable, and, as for the compounding quantity of an organic solvent (C), 20-40 volume% is still more preferable.

-Dispersion medium (S3)-
The dispersion medium (S3) is an organic solvent containing the organic solvent (C). Although the dispersion medium (S3) is somewhat inferior in dispersibility as compared with the organic solvent (S1) and the organic solvent (S2), the dispersion medium (S3) can be fired at a low temperature in the firing step described later. A highly conductive sintered body can be obtained.

-Dispersion medium (S4)-
The dispersion medium (S4) comprises 24 to 64% by volume of the organic solvent (A), 5 to 39% by volume of the organic solvent (B), 30 to 70% by volume of the organic solvent (C), and the organic solvent (E ) A mixed organic solvent containing 1 to 40% by volume.

The organic solvent (A), the organic solvent (B), the organic solvent (C), and the organic solvent (E) may be blended so that the blending ratio is 100% by volume, and within the blending ratio range. Furthermore, you may mix | blend another organic solvent component in the range which does not impair the effect of this invention. In this case, it is preferable that the component which consists of an organic solvent (A), an organic solvent (B), an organic solvent (C), and an organic solvent (E) is contained 90 volume% or more, and 95 volume% or more is more preferable.
When other organic solvent components other than the above are blended, it is preferable to use polar organic solvents such as tetrahydrofuran, diglyme, ethylene carbonate, propylene carbonate, sulfolane, dimethyl sulfoxide and the like.

-Dispersion medium (S5)-
The dispersion medium (S5) is a mixed organic solvent containing 30 to 94% by volume of the organic solvent (A), 30 to 94% by volume of the organic solvent (C), and 1 to 40% by volume of the organic solvent (E). It is. If the organic solvent (A) is less than 30% by volume, the dispersibility and storage stability of the fine particles (P) such as metals in the polar organic solvent may be insufficient.

  The organic solvent (C) needs to be contained in the dispersion medium (S5) in an amount of 30% by volume or more. By setting the organic solvent (C) to such a blending ratio, the dispersion medium (S5) suppresses aggregation of the copper fine particles (P) even when stored for a long period of time, and the dispersion stability is further improved. Further, the denseness and conductivity of the fired film obtained when the fine particle dispersion is sintered are further improved.

  The organic solvent (E) needs to be contained in 1 to 40% by volume in the dispersion medium (S5). By setting the organic solvent (E) to such a blending ratio, the affinity of the dispersed particles for the solvent is improved in the dispersion medium (S5), so that the copper fine particles (P) aggregate even if stored for a long period of time. And the dispersion stability is further improved.

  In the dispersion medium (S5), since the organic solvents (C) and (E) coexist, a part of each of the organic solvents (C) and (E) is made of copper fine particles (P ) It is considered to exist so as to cover the surface. Therefore, in order for the organic solvent (C) to exhibit the effect of further improving the denseness and conductivity of the fired film obtained when the fine particle dispersion is sintered in the dispersion medium (S5), the organic solvent (C ) In an amount of 30% by volume or more. Therefore, in order to produce the above-described effects, the organic solvent (A) needs to be 30 to 94% by volume.

The organic solvent (A), the organic solvent (C), and the organic solvent (E) may be blended so that the blending ratio is 100% by volume, and further within the range of the blending ratio, the effect of the present invention is further achieved. You may mix | blend another organic solvent component in the range which does not impair. In this case, it is preferable that the component which consists of an organic solvent (A), an organic solvent (C), and an organic solvent (E) is contained 90 volume% or more, and 95 volume% or more is more preferable.
When other organic solvent components other than the above are blended, it is preferable to use polar organic solvents such as tetrahydrofuran, diglyme, ethylene carbonate, propylene carbonate, sulfolane, dimethyl sulfoxide and the like.

-Dispersion medium (S6)-
The dispersion medium (S6) is a mixed organic solvent containing 60 to 99% by volume of the organic solvent (C) and 1 to 40% by volume of the organic solvent (E).

  It may be blended from the organic solvent (C) and the organic solvent (E) (D) so that the blending ratio is 100% by volume, and the effect of the present invention is not further impaired within the blending ratio. You may mix | blend another organic-solvent component in the range. In this case, it is preferable that the component which consists of an organic solvent (C) and an organic solvent (E) is 90 volume% or more, and 95 volume% or more is more preferable.

  The organic solvent (C) needs to be contained in the dispersion medium (S6) in an amount of 60% by volume or more. By setting the organic solvent (C) to such a blending ratio, in the dispersion medium (S6), the dispersion of the copper fine particles (P) is suppressed even when stored for a long period of time, and the dispersion stability is further improved. Further, the denseness and conductivity of the fired film obtained when the fine particle dispersion is sintered are further improved.

  The organic solvent (E) needs to be contained in 1 to 40% by volume in the dispersion medium (S6). By setting the organic solvent (D) to such a mixing ratio, the affinity of the dispersed particles for the solvent is improved in the dispersion medium (S6), so that the copper fine particles (P) are aggregated even if stored for a long period of time. And the dispersion stability is further improved.

Since the dispersion media (S1) to (S6) contain the organic solvent (C), a reducing substance can be generated at the time of thermal decomposition and the oxide film of the copper fine particles can be reduced. There is an effect that a gas atmosphere is not required. And, when the copper fine particle dispersion containing the organic solvent (C) is applied to the object to be coated and fired, the uniformity of the sintered body and the high dispersibility and reduction promoting ability of the organic solvent (C) The conductivity can be improved.
Moreover, the mixed organic solvent containing the organic solvent (A) and the organic solvent (B) has excellent dispersibility by stirring, but generally the fine particles tend to be joined to each other over time in the organic solvent. When the organic solvent (C) is present in the dispersion medium, it is possible to more effectively suppress such bonding, thereby improving the dispersibility of the copper fine particles and improving the long-term stability of the dispersion. .

  In the dispersion media (S1) and (S2) used in the present invention, it is more preferable that the concentration of the organic solvent (C) is practically about 20 to 90% by volume. In the dispersion media (S4) and (S5), the organic solvent (A) and the organic solvent (E) coexist, and in order to exhibit the effect of further improving the denseness and conductivity of the obtained fired film, It is necessary to blend 30 to 60% by volume or more of the organic solvent (C). Further, in the dispersion medium (S6), it is more preferable that the concentration of the organic solvent (C) is practically about 70 to 90% by volume due to the coexistence with the organic solvent (E).

(Copper dispersion adjustment process)
Next, the adjustment process of the copper fine particle dispersion will be described.
The copper fine particle dispersion is adjusted by being dispersed in a dispersion medium selected from the above dispersion media (S1) to (S6).

Specifically, for example, polymer dispersion from copper fine particles (Pc) obtained by a liquid phase reduction reaction of copper ions or a known reduction reaction in the presence of a polymer dispersant (D) in an aqueous solution. The copper fine particles (P) whose surface is not covered with the polymer dispersant (D) or whose surface is coated with the polymer dispersant (D) are removed by removing impurities including the agent (D). It can be adjusted by redispersing in the dispersion medium (S).
For the formation of the copper ions, copper chloride, copper nitrate, copper nitrite, copper sulfate, copper acetate, or the like can be used.

As a method for removing the polymer dispersant (D), an aggregation accelerator is added to the aqueous solution after completion of the reduction reaction to aggregate or precipitate the copper fine particles, and then the aggregated or precipitated fine particles are filtered from the aqueous solution. A method of separating by operation can be employed.
As a method for redispersing the copper fine particles (P) in the dispersion medium (S), a known stirring method can be employed, but an ultrasonic irradiation method is preferably employed.

  The average particle diameter of the primary particles of the fine particles (Pc) produced by the reduction is 1 to 150 nm, and practically 1 to 100 nm is preferable. Here, the primary particle diameter means the diameter of primary particles of fine particles such as individual metals constituting the secondary particles. The primary particle size can be measured using a transmission electron microscope. The average particle size means the number average particle size of fine particles such as metals. The secondary particles refer to those formed by aggregating primary particles in a dispersion medium.

  Copper fine particles (P) form secondary agglomerates which are soft agglomerates in which fine particles having a primary particle diameter of 1 to 150 nm are attracted with a weak force capable of redispersion in an organic solvent. Can be measured by a dynamic light scattering type particle size distribution measuring apparatus. By dispersing the copper fine particles (P) in the dispersion medium (S) containing the organic solvent (S), the organic solvent (S), and the organic solvent (C), the particle dispersibility is high (the secondary aggregation size is small). ) Since a fine particle dispersion can be obtained, it is possible to easily make the average secondary aggregate size of the secondary aggregate particles composed of the copper fine particles (P) 500 nm or less, preferably 300 nm or less.

  In addition, the control of the average particle diameter of the primary particles of the copper fine particles (P) is performed by adjusting the types and mixing concentrations of the copper ions, the polymer dispersant (D), the reducing agent, and the reduction reaction of the copper ions. It can be carried out by adjusting the speed, temperature, time, pH and the like. Specifically, for example, in the case of electroless liquid phase reduction, copper ions (cupric acetate, etc.) are borohydride in the presence of polyvinylpyrrolidone (PVP, number average molecular weight of about 3500) in an aqueous solution. When reducing with sodium, if the reduction temperature is about 80 ° C., it is possible to obtain copper fine particles having an average primary particle diameter of 100 nm.

-Polymer dispersant (D)-
The polymer dispersant (D) has solubility in water and is present in the solvent so as to cover the surface of the fine particles made of metal or the like, and suppresses the aggregation of the copper fine particles and is dispersible. Has the effect of maintaining good.

  The polymer dispersant (D) of the present invention is produced, for example, when the copper fine particles (P) are produced by liquid phase reduction such as electroless reduction of copper ions or electroless reduction using a reducing agent in an aqueous solution. It is possible to efficiently form the copper fine particles (P) by dissolving the water-soluble polymer dispersant (D) in the aqueous solution and suppressing aggregation of the copper fine particles (P) precipitated by the reduction reaction. it can.

  When the polymer dispersant (D) of the present invention is water-soluble and is present so as to cover the surface of the copper fine particles (P) deposited in the reaction system, the copper fine particles (P) are aggregated. Has the effect of suppressing dispersibility and maintaining good dispersibility.

  When the copper fine particles (P) are formed in an aqueous solution by liquid phase reduction in the presence of the polymer dispersant (D), these polymer dispersants (D) have solubility in water. It exists so as to cover the surface of the deposited copper fine particles (P), and functions to suppress the aggregation of fine particles (P) such as metals and maintain dispersion.

  The polymer dispersant (D) is a metal having a molecular weight of about 100 to 100,000, which is soluble in water, depending on its chemical structure, and deposited from a metal ion in a reduction reaction in an aqueous solution. Any material can be used as long as the fine particles can be dispersed well.

  Preferred as the polymer dispersant (D) are amine polymers such as polyvinylpyrrolidone and polyethyleneimine; hydrocarbon polymers having a carboxylic acid group such as polyacrylic acid and carboxymethylcellulose; acrylamides such as polyacrylamide; One or more selected from polyvinyl alcohol, polyethylene oxide, starch, and gelatin.

  Specific examples of the molecular weight of the exemplified polymer dispersant (D) compound include polyvinylpyrrolidone (molecular weight: 1000 to 500,000), polyethyleneimine (molecular weight: 100 to 100,000), carboxymethylcellulose (hydroxyl group of alkali cellulose). Degree of substitution of carboxymethyl group of Na salt: 0.4 or more, molecular weight: 1000 to 100,000, polyacrylamide (molecular weight: 100 to 6,000,000), polyvinyl alcohol (molecular weight: 1000 to 100,000) Polyethylene glycol (molecular weight: 100 to 50,000), polyethylene oxide (molecular weight: 50,000 to 900,000), gelatin (average molecular weight: 61,000 to 67,000), water-soluble starch, and the like.

The number average molecular weights of the respective polymer dispersants (D) are shown in the parentheses, and those having such a molecular weight range are water-soluble and can be used preferably in the present invention. In addition, these 2 or more types can also be mixed and used.
Other examples include thiols, carboxylic acids, amides, carbonitriles, and esters. Moreover, polymethyl vinyl ether etc. can be illustrated as a polymer which has a polar group.

  The flocculant is liquid or gas at normal temperature or operating temperature, and is added to the aqueous solution after the reduction reaction to aggregate or precipitate the fine particles and not to precipitate the polymer dispersant (D). Although not particularly limited, a preferred example is a halogen-based hydrocarbon. The halogen-based hydrocarbon is preferably a halogen compound such as a chlorine compound or bromine compound having 1 to 4 carbon atoms, or a chlorine-based or bromine-based halogen-based aromatic compound.

  As described above, the dispersibility is excellent and the surface is not coated with the polymer dispersant (D), or the weight ratio (D / P) between the polymer dispersant (D) and the copper fine particles (P). The copper fine particles coated with a very small amount of the polymer agent (D) having a ratio of less than 0.001, or the weight ratio (D / P) of the polymer dispersant (D) and the copper fine particles (P) is 0.001. A dispersion of copper fine particles coated with a relatively small amount of the polymer dispersant (D) in the range of -0.01 can be obtained.

  The confirmation of the weight ratio (D / P) of the polymer dispersant (D) and the copper fine particles (P) covering the surface of the copper fine particles (P) in the fine particle dispersion is, for example, the following (i) or ( It can be carried out by the method ii).

(I) Collecting the fine particle dispersion, separating the copper fine particles (P) from the fine particle dispersion by an operation such as centrifugation, and the condition that the polymer dispersant (D) does not react in the oxidizing solution. Then, a solution in which copper particles are dissolved is prepared, and the solution is quantitatively analyzed by liquid chromatography or the like to measure the weight ratio (D / P). The detection limit of the polymer dispersant (D) by the analysis method can be about 0.02% by weight.

(Ii) Collecting the fine particle dispersion, separating the fine particles (P) from the fine particle dispersion by an operation such as centrifugal separation, and removing the polymer dispersant (D) from the fine particles (P) by an operation such as solvent extraction. After extraction into a solvent, if necessary, concentration operation such as evaporation is performed, and liquid chromatography or specific elements (nitrogen, sulfur, etc.) in the polymer dispersant (D) are subjected to X-ray photoelectron spectroscopy ( It can be performed by analysis such as XPS (X-ray Photoelectron Spectroscopy) and Auger Electron Spectroscopy (AES).

(Wiring pattern formation process)
Next, the copper fine particle dispersion obtained by the above process is applied or printed on a substrate to form a wiring pattern made of a liquid film of the copper fine particle dispersion.
As a coating or printing method, various conventionally known methods can be adopted, but an inkjet method or a screen printing method is preferable.

  As the substrate, a transparent plastic material such as polyethylene terephthalate (PET), triacetyl cellulose (TAC), polycarbonate (PC), polymethyl methacrylate (PMMA) can be used.

(Baking process)
Next, the liquid film of the copper fine particle dispersion is dried and fired to form a sintered wiring layer of copper fine particles.
At this time, since the surface of the copper fine particles is not coated with the polymer dispersant (D) or is coated with a relatively small amount of the polymer dispersant (D), the conventional polymer compound layer Sintering between the copper fine particles is not hindered as in the case of the copper fine particles coated thickly, and firing at a relatively low temperature of about 190 ° C. is possible.

Specifically, although drying conditions depend on the solvent to be used, it is, for example, about 100 to 200 ° C. for about 15 to 30 minutes, and the firing conditions depend on the coating thickness, for example, for example, 190 to 250 ° C. for 20 to 40 minutes. Degree, preferably at 190 to 220 ° C. for about 20 to 40 minutes.
Drying and firing can be performed in an inert gas atmosphere such as argon without using a reducing gas such as hydrogen gas.

(Black layer formation process)
Next, a black layer is formed on the sintered wiring of copper fine particles. The black layer can be formed by applying or printing a pigment dispersion containing a black inorganic pigment on the sintered wiring. The coating or printing method is preferably an ink jet method or a screen printing method.

  In addition to the above-described forming method, a black layer is directly formed on a substrate, and a copper fine particle dispersion is applied or printed thereon to form a wiring pattern composed of a liquid film of the copper fine particle dispersion. The liquid film may be fired to form a sintered wiring layer. Further, a second black layer may be further formed on the sintered wiring layer.

  As the black inorganic pigment, fine particles made of various inorganic materials exhibiting black can be used. For example, at least one metal selected from the group consisting of copper, cobalt, chromium, manganese, iron, ruthenium, and titanium. And oxide fine particles or carbide fine particles. Moreover, various carbon blacks generally used as a black colorant can be used.

  The dispersion medium for dispersing the black inorganic pigment is not particularly limited, but water, alcohols, hydrocarbons, and ethers are preferable from the viewpoint of dispersion stability of fine particles and ease of application to the ink jet method. Water or hydrocarbons are preferred. These may be used alone or in combination of two or more.

Examples of alcohols include methanol, ethanol, propanol, butanol and the like.
Examples of hydrocarbons include n-heptane, n-octane, decane, toluene, xylene, cymene, durene, indene, dipentene, tetrahydronaphthalene, cyclohexylbenzene, and the like.

  Examples of ethers include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, p- A dioxane etc. can be illustrated.

The pigment dispersion applied or printed on the substrate is then dried and heat-treated, whereby a two-layered sintered wiring composed of a sintered wiring layer and a black layer is formed.
In this way, by forming a sintered wiring having a two-layer structure composed of a sintered wiring layer and a black layer, for example, a dispersion containing copper fine particles and a black inorganic pigment is applied onto a substrate and fired. Compared with the case of forming a single-layer sintered wiring colored in black, a wiring excellent in conductivity can be obtained. As a result, the wiring width can be made smaller, so that it can be applied to a finer wiring pattern.

By the above process, the metal material itself is much cheaper than gold, silver, nickel, etc., and copper is not short-circuited due to electromigration as in the case of using silver. An electromagnetic wave shielding wiring circuit using is formed.
The obtained electromagnetic shielding wiring circuit is excellent in electrical conductivity even when fired at a low temperature, and its electrical resistance value can achieve 1 × 10 ⁻⁴ Ωcm or less, and exhibits good shielding performance. be able to. Moreover, since the sintered wiring layer in this invention is excellent also in board | substrate adhesiveness, it is preferable that a sintered wiring layer is especially formed on a board | substrate among the formation methods mentioned above.

  Furthermore, by applying the method for forming an electromagnetic wave shielding wiring circuit of the present invention, it is possible to reduce the manufacturing cost of the electromagnetic wave shielding sheet and contribute to lowering the price of electronic equipment such as a plasma display panel on which the electromagnetic wave shielding sheet is mounted. can do.

(Second Embodiment)
Next, a method for forming an electromagnetic wave shielding wiring circuit according to the second embodiment of the present invention will be described.

(Process for adjusting copper fine particle dispersion)
First, the adjustment process of a copper fine particle dispersion liquid is implemented. Each component and adjustment method of the copper fine particle dispersion are the same as those in the first embodiment.

(Wiring pattern formation process)
Next, similarly to the first embodiment, the copper fine particle dispersion is applied or printed on the substrate to form a wiring pattern made of a liquid film of the copper fine particle dispersion.

(Pigment dispersion application or printing process)
Next, a pigment dispersion containing a black inorganic pigment is applied or printed on the liquid film of the copper fine particle dispersion. As the coating or printing method, an inkjet method or a screen printing method can be used.

  For example, when the inkjet method is used, the pigment dispersion liquid is applied by the first inkjet nozzle using two inkjet nozzles, and then the copper fine particle dispersion is continuously discharged by the second inkjet nozzle. . At this time, after applying the pigment dispersion, a drying process may be performed, and then the copper fine particle dispersion may be discharged.

  On the contrary, after the copper fine particle dispersion is discharged from the first inkjet nozzle, the pigment dispersion may be continuously discharged from the second inkjet nozzle. The copper fine particle dispersion discharged first is dried to some extent immediately after discharge to form a liquid film of copper fine particles, so that the pigment dispersion can be applied over the liquid film of the copper fine particles, After the copper fine particle dispersion is discharged, the pigment dispersion may be applied after a drying process.

(Baking process)
Next, the liquid film of the copper fine particle dispersion and the pigment dispersion are dried and fired to form a sintered wiring having a two-layer structure including a copper sintered layer and a black layer. The firing temperature is preferably 190 ° C to 300 ° C.

  At this time, as in the first embodiment, firing at a relatively low temperature of about 190 ° C. is possible, and drying and firing can be performed without using a reducing gas such as hydrogen gas and without using argon or the like. It can be performed under an active gas atmosphere.

  As in the wiring forming method according to the first embodiment, the sintered wiring layer in the present invention is also excellent in substrate adhesion. Preferably a layer is formed.

  Thus, a manufacturing process rather than the wiring forming method according to the first embodiment in which the sintered wiring of copper fine particles and the black layer are separately formed by simultaneously forming the copper sintered layer and the black layer. Can be simplified.

  According to the second embodiment, similarly to the first embodiment, it is possible to realize a PDP wiring using copper which is inexpensive and does not cause electromigration. In addition, the obtained PDP wiring is excellent in conductivity even when fired at a low temperature, and when used as an electromagnetic wave shielding wiring, it can exhibit good shielding performance. The sintered wiring layer is also excellent in substrate adhesion. Furthermore, the manufacturing cost of the plasma display panel can be reduced, which can contribute to the price reduction of the plasma display panel.

  FIG. 1 shows an example of an electromagnetic wave shielding sheet including the electromagnetic wave shielding wiring circuit obtained by the first and second embodiments. As shown in FIG. 1A, the electromagnetic wave shielding sheet 1 is a laminate in which a transparent base film 14, a mesh-like black layer 12 formed thereon, and a sintered wiring layer 11 are laminated. It has a body 10 and further has a protective film 20 and a protective film 30 provided on both surfaces of the laminate 10. The protective film 20 has a base material 21 and a pressure-sensitive adhesive layer 22 formed thereon, and the protective film 30 has a base material 31 and a pressure-sensitive adhesive layer 32 formed thereon. In this example, although the black layer 12 is laminated | stacked on the transparent base film 14 side in the sintered wiring layer 11, the sintered wiring layer 11 may be distribute | arranged on the transparent base film 14 side.

  Moreover, as shown in FIG.1 (b), in the electromagnetic wave shielding sheet 1, the sintered wiring layer 11 is made into a mesh shape with the apertures 11a arranged closely. As shown in FIG. 1 (c), the opening 11 a has a narrow line width w of 5 μm to 20 μm, and the pitches a and b in the vertical and horizontal directions may be the same or different. It is about 50 μm to 500 μm. However, the open area ratio per unit area is preferably about 90% to 95%. Further, the line may have an appropriate angle θ with respect to the horizontal direction (the horizontal direction during observation). The mesh shape is not limited to a lattice shape as shown in FIG. 1B, and the opening 11a has a shape other than a quadrangle, for example, a hexagonal honeycomb shape, a circular shape, or an elliptical shape. These may be included in the mesh range.

  Furthermore, the electromagnetic wave shielding sheet 1 is provided on the front and back of the laminate 10 laminated on the substrate, for example, through an infrared cut filter layer, etc. with respect to the laminate 10, further strengthening the outermost surface and imparting antireflection properties. In addition, sheets having effects such as imparting antifouling property are laminated and used. Therefore, it is necessary to peel off the protective film 20 in the case of such further lamination. For this reason, it is desirable that the lamination of the protective film 20 on the sintered wiring layer 11 side is performed in a so-called peelable manner. .

  Further, the peel strength when the protective film 20 is laminated on the sintered wiring layer 11 is preferably 5 mN / 25 mm width to 5 N / 25 mm width, more preferably 10 mN / 25 mm width to 100 mN / 25 mm width. If it is less than the lower limit, peeling is too easy, and the protective film 20 may be peeled off during handling or inadvertent contact, which is not preferable. On the other hand, if the upper limit is exceeded, a large force is required for peeling, and the mesh-like sintered wiring layer 11 may be peeled off from the transparent substrate film 14 at the time of peeling.

  FIG. 2 is a diagram showing an outline of an electromagnetic wave shielding panel using the electromagnetic wave shielding sheet of the present invention. The upper side in FIG. 2 is the observation side, and the lower side is the back side. The electromagnetic wave shielding panel 40 is disposed on the observation side of a display such as a PDP (not shown). The electromagnetic wave shielding panel 40 includes a transparent base film 14, a black layer 12 formed on the film 14 (that is, an observation side), and a mesh-like sintered wiring layer 11 formed on the black layer 12. Furthermore, the adhesive layer 53, the film 52, the hard coat layer, the antireflection layer, the antifouling layer, and the like were sequentially laminated on the sintered wiring layer 11 side from the laminated body 10 side. It has an observation-side (= front-side) film 50 on which multiple layers 51 are laminated. In FIG. 2, the intervals between the stacked bodies 50, 10, 60, 70, and 50 ′ are actually stacked without being opened.

  On the transparent substrate film 14 side of the laminate 10, a near-infrared absorbing film 60, a glass substrate 70, and a back surface (= back surface) film 50 'are sequentially stacked. The near-infrared absorbing film 60 is obtained by sequentially laminating a pressure-sensitive adhesive layer 61, a near-infrared absorbing layer 62, a film 63, and a pressure-sensitive adhesive layer 64 from the laminate 10 side. The glass substrate 70 is for maintaining the mechanical strength, self-supporting property, or flatness of the entire electromagnetic wave shielding panel 40. The back surface (= back surface) film 50 ′ is a multi-layer 51 ′ in which an adhesive layer 53 ′, a film 52 ′, a hard coat layer, an antireflection layer, an antifouling layer and the like are sequentially laminated from the glass substrate 70 side. In this case, the back film 50 ′ is the same as the observation-side film 50.

  In addition, the electromagnetic wave shielding panel 40 described with reference to FIG. 2 is an example, and it is preferable that each of the laminated bodies as described above is laminated. However, if necessary, any of them may be omitted. Modifications such as preparing and using a laminate having the functions of the respective layers are possible.

  Next, examples of the present invention will be described, but the present invention is not limited to the following examples.

First, evaluation methods in the following examples and comparative examples are described below.
(1) Electrical Resistance of Wiring The electrical resistance value of the wiring was measured using a DC four-terminal method (use measuring machine: Digital Multimeter DMM2000 type (four-terminal electric resistance measurement mode)) manufactured by Keithley. The electrical resistance value was evaluated by the following method.
○: Less than 1 × 10 −4 [Ω · cm] Δ: Less than 1 × 10 −2 [Ω · cm], 10 × 10 −4 [Ω · cm] or more ×: 1 × 10 −2 [Ω · cm] that's all

(2) Substrate adhesion of the fired film A tape peel test of the fired film was performed in accordance with JIS D0202-1988. The fired film of the evaluation sample was separated by 10 mm in total, divided into a total of 10 cells, and adhered using a cellophane tape (“CT24”, manufactured by Nichiban Co., Ltd.), and then peeled off. Judgment was expressed according to the following criteria from the number of squares not peeled out of 10 squares.
○: The peeled square is 1 square or less Δ: The peeled square is 4 to 2 squares x: 5 squares or more are peeled

The electromagnetic shielding wiring circuit was formed by the following procedure.
1. Preparation of Copper Fine Particle Dispersion Liquid copper fine particles covered with a polymer dispersant were prepared by the following method.
10 ml of an aqueous copper acetate solution in which 0.2 g of copper acetate ((CH ₃ COO) ₂ Cu · 1H ₂ O) was dissolved in 10 ml of distilled water as a raw material for copper fine particles, and 5.0 mol of sodium borohydride as a metal ion reducing agent 100 ml of an aqueous sodium borohydride solution was prepared by dissolving in distilled water to a concentration of 1 liter / liter. Thereafter, 0.5 g of polyvinyl pyrrolidone (PVP, number average molecular weight of about 3500) as a polymer dispersant was further added to the aqueous sodium borohydride solution, and dissolved by stirring.

  In a nitrogen gas atmosphere, 10 ml of the aqueous copper acetate solution was dropped into an aqueous solution in which the reducing agent and the polymer dispersant were dissolved. As a result of reacting this reduction reaction liquid with sufficient stirring for about 60 minutes, a fine particle dispersion in which copper fine particles having an average primary particle diameter of 5 to 10 nm were dispersed in an aqueous solution was obtained.

  Next, 5 ml of chloroform as an aggregation accelerator was added to 100 ml of the dispersion liquid in which the copper fine particles obtained by the above method were dispersed, and stirred well. After stirring for several minutes, the mixture was allowed to stand, and the aqueous phase as a reaction solution was supplied to a centrifuge to separate and collect copper fine particles. After that, the obtained copper fine particles and 30 ml of distilled water are put in a test tube, stirred well using an ultrasonic homogenizer, and then washed three times with a centrifuge to recover the particle components, followed by the same test. In the tube, the obtained copper fine particles and 30 ml of 1-butanol were put and stirred well, and then alcohol washing for recovering the copper fine particles with a centrifuge was performed three times. Through the above steps, copper fine particles to be dispersed in the final dispersion solvent were obtained.

  Separately, as an example of the mixed organic solvent of the present invention, N-methylacetamide as the organic medium (A), diethyl ether as the organic solvent (B), ethylene glycol as the organic solvent (C), and organic solvent (E) as the organic solvent (E) Using triethylamine, these were mixed at the solvent mixing ratio shown in Table 1 and Table 2, and the mixed organic solvents of Examples 1-1 to 1-25 were respectively adjusted.

  By dispersing the copper fine particles obtained by the above method in 10 ml of the organic mixed solvent of Examples 1-1 to 1-25 and applying ultrasonic vibration to the dispersion for 1 hour using an ultrasonic homogenizer, The copper fine particle dispersions of Examples 1-1 to 1-25 were prepared.

Next, the polymer dispersant covering the surface of the copper fine particles was analyzed. First, an eluent prepared by mixing a 0.2 M nitric acid aqueous solution, a 0.2 M hydrochloric acid aqueous solution, and methanol in a 1: 1: 2 ratio was added to the copper fine particles obtained in the above step to dissolve the copper particle components. . The resulting solution was neutralized with an appropriate amount of aqueous sodium hydroxide solution, and then polymerized using a gel filtration chromatogram (GPC, detector: Shodex RI SE-61, column: Tosoh TSKgel G3000PWXL) manufactured by Showa Denko K.K. The content of the dispersant component was examined. As a result, the used polymer dispersant component (polyvinylpyrrolidone) was not detected at all. The detection limit of the measuring device is 0.02% by weight.
From this experimental result and the detection sensitivity of the measuring device, the amount (D) of the polymer dispersant adhering to the copper fine particles obtained by this production method is at least 0 as the weight ratio (D / P) to the fine particle amount (P). It was confirmed to be less than 0.001.

2. Step of forming a wiring pattern Ink (black inorganic pigment ink) in which conductive carbon black of black inorganic pigment (Ketjen Black (registered trademark)) is dispersed in 3 wt% in THF (tetrahydrofuran); Copper fine particle dispersions (Examples 1-1 to 1-25) prepared by the method shown in FIG. 1 and Comparative Example 1 were manufactured by ULVAC, Inc., copper nanoparticle dispersions (trade names: Cu nanometal ink "Cu1T"), as Comparative Example 2, a copper particle dispersion obtained by dispersing the copper fine particles obtained by the above method in distilled water, and as shown in Table 3 as Comparative Examples 3-1 to 3-7 The copper particle dispersions obtained by dispersing the copper fine particles obtained by the above-described method in the solvent of the above ratio were respectively applied to the first and second ink jet heads (Mect: MICROJET (registered trademark) Model MJ-040). After forming a pattern with a black inorganic pigment ink on a transparent polyethylene terephthalate resin (= PET) film (Toyobo Co., Ltd., product number: A4300) having a width of 700 mm and a thickness of 100 μm In an argon gas atmosphere, drying the pattern formed by holding at about 0.99 ° C. 30 minutes to form a pattern with more copper particulate dispersion thereon (A). As shown in FIG. 1C, the pattern at this time was formed such that the line width w of the aperture 11a was 10 μm, and the vertical and horizontal pitches a and b were 250 μm.

3. 1. Step of forming a sintered wiring layer The wiring pattern formed in (1) was held in an argon gas atmosphere at about 150 ° C. for 30 minutes to dry the coating film, and further in a nitrogen atmosphere at 180 ° C., 190 ° C., 210 ° C., 250 ° C., 300 ° C. Each was heat-treated for 1 hour. Thereafter, the furnace was slowly cooled to room temperature in a heat treatment furnace.
Thus, the electromagnetic wave shielding wiring circuit in this example and the comparative example was formed.

(Conductivity evaluation)
The result of having measured the electrical resistance of the wiring after sintering obtained in the Example and the comparative example is shown to Tables 1-3.

As is apparent from Tables 1 and 2, the copper fine particle dispersions of Examples 1-1 to 1-25 were able to form wiring with good conductivity by heat treatment at a temperature of 210 ° C. or higher in a nitrogen atmosphere. . In particular, when the organic solvent (C) is 95% by volume or more (Examples 1-7, 1-13, 1-23), the electrical resistance is good even at a low sintering temperature of 180 ° C., and the organic solvent When (C) was less than 20% by volume, it was found that the electrical resistance was not so good on the low temperature side of sintering temperatures of 180 ° C. and 190 ° C.
On the other hand, as is apparent from Table 3, the fired film obtained in the comparative example remained high in resistance even when heat-treated at a temperature of 250 ° C. or higher.

(Adhesion evaluation)
A fired film was formed by the following procedure.
The copper fine particle dispersion was adjusted in the same manner as when the electromagnetic wave shielding wiring circuit was formed, and Examples 1-1 to 1-25 and Comparative Examples 1, 2, and 3-1 to 3 shown in Tables 1 to 3 were prepared. The copper fine particle dispersion of −7 was applied onto a transparent polyethylene terephthalate resin (= PET) film (product number: A4300, manufactured by Toyobo Co., Ltd.) having a thickness of 2 cm × 2 cm and a thickness of 100 μm. Thereafter, the coating film was dried at about 150 ° C. for 30 minutes in an argon gas atmosphere, and then further heat-treated at 210 ° C. for 1 hour in a nitrogen atmosphere. Thereafter, the furnace was slowly cooled to room temperature in a heat treatment furnace.
The tape peeling test was done about the obtained fired film by said method.

The test results are shown in Tables 1 to 3. As is clear from Table 1 and Table 2, the fired films obtained from the copper fine particle dispersions of Examples 1-1 to 1-25 were excellent in adhesion. However, in the electrical conductivity evaluation, the electrical resistance was good even at a low sintering temperature of 180 ° C., and the organic solvent (C) was 95% by volume or more (Examples 1-7, 1-13, 1-23) Then, it turned out that it cannot be said that adhesiveness is very excellent.
On the other hand, as is apparent from Table 3, the fired film obtained from the copper fine particle dispersion of the comparative example had poor adhesion.

  As is clear from the above, by using a dispersion medium in which the organic solvents (A) to (E) are blended within a predetermined ratio range, a conductive material having both conductivity and adhesion can be formed. did it.

(Ink stability evaluation)
Next, the results of evaluating the storage stability of the copper fine particle dispersion used in the examples will be described.
Storage stability was evaluated by storing the copper fine particle dispersion in a sealed state at 35 ° C. for one month. As a result, no precipitate was observed in the copper fine particle dispersion.

  In addition, with respect to the copper fine particle dispersion added with conductive carbon black (Ketjen Black (registered trademark)) as a black inorganic pigment, storage stability was evaluated by storing it at 35 ° C. for one month in a sealed state. . As a result, a precipitate was formed in the case where the black inorganic pigment (conductive carbon black) ink was added to the copper fine particle dispersion (A). Further, a precipitate was similarly generated in the copper fine particle dispersion (B).

  When the precipitate was analyzed using energy-dispersive X-ray spectroscopy (EDS), strong C and Cu peaks were confirmed. It is considered that the conductive carbon black and the copper particles of the black inorganic pigment ink are aggregated and precipitated.

  In addition, when the copper fine particle dispersion in which the precipitate is generated in this manner is put in the ink jet head, nozzle clogging occurs and wiring formation cannot be performed, and further, the head needs to be replaced. Cannot be used.

  Therefore, in order to form an electromagnetic wave shielding sheet having good conductivity without clogging the nozzles of the inkjet head, the wiring is formed by putting the black inorganic pigment ink and the copper fine particle dispersion into different inkjet heads as in this embodiment. It turns out that it is effective.

(Electromagnetic wave shielding sheet)
Using the copper fine particle dispersion of the example and the black inorganic pigment ink, as shown in FIG. 1, a black layer 12 and a sintered wiring layer 11 are formed on a transparent substrate film (PET film) 14 to shield the electromagnetic wave. A wiring circuit 10 was obtained. The layer thickness of the obtained sintered wiring layer 11 is not particularly limited, but is generally in the range of 0.5 to 100 μm. If the thickness of the conductive layer is too thin, the electromagnetic shielding property is deteriorated, which is not preferable. If the thickness is too thick, the thickness of the obtained electromagnetic shielding light transmitting window material itself is affected and the viewing angle is narrowed. For this reason, it is preferable that the thickness is in the range of 0.5 to 100 μm. Moreover, it is preferable that the line | wire width of a conductive layer is 5-20 micrometers, and it is especially preferable that it is 5-15 micrometers. By reducing the line width, it is possible to suppress the occurrence of moiré with respect to the pixels of the display and to increase the aperture ratio for improving transparency.

  Next, an acrylic pressure-sensitive adhesive layer 32 is laminated on the PET film 31 on the side where the black layer 12 and the sintered wiring layer 11 of the PET film 14 of the electromagnetic wave shielding wiring circuit 10 are not formed. A protective film 30 (manufactured by Panac Industry Co., Ltd., product number: HT-25) having a total thickness of 28 μm, which had been subjected to corona discharge treatment on the side where the layers were not laminated, was bonded using a laminator roller. Thereby, it was set as the laminated body of the structure of the protective film 30 / PET film 14 / black layer 12 / sintered wiring layer (copper mesh) 11. FIG. Protective film 20 having a total thickness of 65 μm obtained by laminating an acrylic pressure-sensitive adhesive layer 22 on polyethylene film 21 on the sintered wiring layer 11 side of the obtained laminate (product name: Sanitect Y-26F, manufactured by Sanei Kaken Co., Ltd.) ) Was laminated using a laminator roller. Thus, an electromagnetic wave shielding sheet 1 having a configuration of protective film 30 / PET film 14 / black layer 12 / sintered wiring layer (copper mesh) 11 / protective film 20 as shown in FIG. 1 was obtained.

  As described above, the electromagnetic wave shielding sheet of the present invention is excellent in electromagnetic wave shielding properties, hardly causes moiré, and has a high aperture ratio, and thus is excellent in transparency. For this reason, the electromagnetic wave shielding sheet of the present invention is suitable as a front film for PDP, and in an application to an environment where electromagnetic shielding properties such as a research institution of a hospital or a university are required (such as a sticking film), It can be used advantageously.

It is sectional drawing which shows the example of the sheet | seat for electromagnetic wave shielding which has the wiring circuit for electromagnetic wave shielding of this invention. It is sectional drawing which shows the example of the electromagnetic wave shielding panel which has the wiring circuit for electromagnetic wave shielding of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electromagnetic wave shielding sheet 10 Laminate body 11 Sintered wiring layer 11a Opening part 12 Black layer 14 Transparent base film 20 Protective film 30 Protective film 40 Electromagnetic wave shielding panel 50 Observation side film 50 ′ Rear film 60 Near infrared Absorption film 70 Glass substrate

Claims (8)

Copper fine particles (P)
(I) 5 to 90% by volume of an organic solvent (A) having an amide compound, 5 to 45% by volume of an organic solvent (B) having a boiling point of 20 ° C. or higher at normal pressure and 17 or more donors, A dispersion medium having an organic solvent (C) of 5 to 90% by volume having a boiling point at normal pressure exceeding 100 ° C. and comprising alcohol and / or polyhydric alcohol, from the organic solvents (A) to (C) A dispersion medium (S1) containing 90% by volume or more of
(Ii) 20 to 95% by volume of an organic solvent (A) having an amide-based compound, 5 to 80% by volume of an organic solvent (C) having a boiling point exceeding 100 ° C. at normal pressure and comprising alcohol and / or a polyhydric alcohol A dispersion medium containing 90% by volume or more of the component consisting of the organic solvents (A) and (C) (S2) ,
( Iv) 24 to 64% by volume of an organic solvent (A) having an amide compound, 5 to 39% by volume of a low-boiling organic solvent (B) having a boiling point of 20 to 100 ° C. at normal pressure, and a boiling point at normal pressure There exceed 100 ° C., and met dispersion medium containing an alcohol and / or a polyhydric organic solvent (C) 30 to 70% by volume composed of an alcohol and an organic solvent (E) 1 to 40 vol% with an amine compound A dispersion medium (S4) containing 90% by volume or more of the component consisting of the organic solvents (A) to (C) and (E ),
(V) 30 to 94% by volume of an organic solvent (A) having an amide-based compound, and 30 to 94% by volume of an organic solvent (C) having a boiling point exceeding 100 ° C. at normal pressure and comprising an alcohol and / or a polyhydric alcohol. , A dispersion medium containing 1 to 40% by volume of an organic solvent (E) having an amine compound , wherein the component comprising the organic solvents (A), (C) and (E) is contained by 90% by volume or more. dispersion media are (S5), and (vi) a boiling point of greater than 100 ° C. at normal pressure, and alcohol and / or organic solvent (C) and 80 to 90 volume percent composed of polyhydric alcohols, organic solvents having an amine compound (E) Dispersion medium containing 10 to 20% by volume , wherein the dispersion medium (S6) contains 90% by volume or more of the organic solvent (C) and (E ).
A step of adjusting the copper fine particle dispersion by dispersing in a dispersion medium (S) selected from:
Applying or printing the copper fine particle dispersion on a substrate or a black layer formed on the substrate to form a wiring pattern comprising a liquid film of the copper fine particle dispersion; and
Forming a sintered wiring layer by firing a liquid film of the copper fine particle dispersion, and forming a wiring circuit for shielding electromagnetic waves.   The method for forming an electromagnetic shielding wiring circuit according to claim 1, further comprising a step of forming a black layer on the sintered wiring layer.   The electromagnetic wave shielding device according to claim 2, wherein the black layer is formed by applying or printing a pigment dispersion containing a black inorganic pigment on the substrate or the sintered wiring layer. A method of forming a wiring circuit.   The method for forming an electromagnetic shielding wiring circuit according to claim 1, wherein the coating or printing is performed by an inkjet method or a screen printing method. Copper fine particles (P)
(I) 5 to 90% by volume of an organic solvent (A) having an amide compound, 5 to 45% by volume of an organic solvent (B) having a boiling point of 20 ° C. or higher at normal pressure and 17 or more donors, A dispersion medium having an organic solvent (C) of 5 to 90% by volume having a boiling point at normal pressure exceeding 100 ° C. and comprising alcohol and / or polyhydric alcohol, from the organic solvents (A) to (C) A dispersion medium (S1) containing 90% by volume or more of
(Ii) 20 to 95% by volume of an organic solvent (A) having an amide-based compound, 5 to 80% by volume of an organic solvent (C) having a boiling point exceeding 100 ° C. at normal pressure and comprising alcohol and / or a polyhydric alcohol A dispersion medium containing 90% by volume or more of the component consisting of the organic solvents (A) and (C) (S2) ,
( Iv) 24 to 64% by volume of an organic solvent (A) having an amide compound, 5 to 39% by volume of a low-boiling organic solvent (B) having a boiling point of 20 to 100 ° C. at normal pressure, and a boiling point at normal pressure There exceed 100 ° C., and met dispersion medium containing an alcohol and / or a polyhydric organic solvent (C) 30 to 70% by volume composed of an alcohol and an organic solvent (E) 1 to 40 vol% with an amine compound A dispersion medium (S4) containing 90% by volume or more of the component consisting of the organic solvents (A) to (C) and (E ),
(V) 30 to 94% by volume of an organic solvent (A) having an amide-based compound, and 30 to 94% by volume of an organic solvent (C) having a boiling point exceeding 100 ° C. at normal pressure and comprising an alcohol and / or a polyhydric alcohol. , A dispersion medium containing 1 to 40% by volume of an organic solvent (E) having an amine compound , wherein the component comprising the organic solvents (A), (C) and (E) is contained by 90% by volume or more. dispersion media are (S5), and (vi) a boiling point of greater than 100 ° C. at normal pressure, and alcohol and / or organic solvent (C) and 80 to 90 volume percent composed of polyhydric alcohols, organic solvents having an amine compound (E) Dispersion medium containing 10 to 20% by volume , wherein the dispersion medium (S6) contains 90% by volume or more of the organic solvent (C) and (E ).
A step of adjusting the copper fine particle dispersion by dispersing in a dispersion medium (S) selected from:
Applying or printing the copper fine particle dispersion on a substrate to form a wiring pattern comprising a liquid film of the copper fine particle dispersion; and
A step (b) of applying or printing a pigment dispersion containing a black inorganic pigment on the liquid film of the copper fine particle dispersion;
A wiring circuit for shielding electromagnetic waves, comprising: baking a liquid film of the copper fine particle dispersion and a pigment dispersion to form a sintered wiring having a two-layer structure including a copper sintered layer and a black layer. Forming method.   6. The method for forming an electromagnetic shielding wiring circuit according to claim 5, wherein the step (b) is performed after the step (a).   The method for forming an electromagnetic shielding wiring circuit according to claim 5 or 6, wherein the coating or printing is performed by an ink jet method or a screen printing method. A wiring circuit formed by the method for forming an electromagnetic shielding wiring circuit according to any one of claims 1 to 7,
An electromagnetic wave shielding sheet comprising protective films provided on both upper and lower surfaces of the wiring circuit.

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