JP2017069012A - Conductive paste and method of manufacturing conductive film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive paste capable of forming a conductive film good in adhesiveness with a substrate and weather resistance by light burning, and a method of manufacturing the conductive film using the same.SOLUTION: A conductive paste contains a copper fine particle with average particle diameter of 10 to 100 nm and a silver crude particle with cumulative 50% particle diameter (D) measured with a laser diffraction type particle size distribution measuring device of 4 to 25 μm and has tap density of the copper crude particle of 3.9 g/cmor less, a ratio of cumulative 90% particle diameter (D) to cumulative 10% particle diameter (D) by volume basis measured with the laser diffraction type particle size distribution measuring device of 3.65 or more and percentage of mass of the copper fine particle to the total amount of the copper fine particle and the copper crude particle of 20% or more. The conductive paste is applied on a substrate by screen printing, preliminary burned by vacuum drying and then irradiated with light to form a conductive film on the substrate and pressure is applied to the conductive film with a roll or the like to conduct a compression treatment.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive paste, and more particularly to a conductive paste used for manufacturing a conductive film for forming an electrode or a circuit of an electronic component and a method for manufacturing a conductive film using the conductive paste.

  Conventionally, as a method for producing a conductive film using a conductive paste, a photosensitive paste containing inorganic fine particles such as glass fine particles, a photosensitive organic component, and a compound having an azole structure such as benzotriazole is applied to a substrate. Then, after exposure, development is performed, and then baking is performed to form a pattern (of a conductive film) (see, for example, Patent Document 1). Also, after printing a copper ink solution containing copper nanoparticles on the surface of the substrate and drying it, the copper nanoparticles are fused by photo-sintering by exposure to a pulse, and a photo-sintered copper nano-particle film (conductive film) Has been proposed (see, for example, Patent Document 2). Furthermore, a conductive ink using copper fine particles with benzotriazole deposited on the surface as a conductive filler has been proposed as an oxidation resistant treatment (see, for example, Patent Document 3).

JP-A-9-218508 (paragraph numbers 0010-0056) Japanese translation of PCT publication 2010-528428 (paragraph number 0009-0014) JP 2008-285761 A (paragraph number 0008-0010)

  However, in the method of Patent Document 1, it is necessary to apply a photosensitive paste to a substrate, expose it, develop using a developer, and then bak at a high temperature (520 to 610 ° C.). It is complicated and cannot be fired by light irradiation, and a pattern cannot be formed on a heat-sensitive substrate such as paper or PET (polyethylene terephthalate) film. In the method of Patent Document 2, a conductive film having sufficient adhesion to a substrate such as paper cannot be formed, and a conductive film having good weather resistance cannot be formed. In addition, when the conductive ink of Patent Document 3 is used as a conductive paste for light baking, the conductive film cracks when the conductive film is formed by applying it to a substrate and drying it, followed by baking by light irradiation. Sexuality gets worse.

Therefore, in view of such conventional problems, the present invention provides a conductive paste capable of forming a conductive film having good adhesion and weather resistance with a substrate by photo-baking and a conductive film using the conductive paste. An object is to provide a manufacturing method.
The purpose is to do.

As a result of intensive studies to solve the above problems, the present inventors have found that copper fine particles having an average particle diameter of 10 to 100 nm and a volume-based cumulative 50% particle diameter (D ₅₀₎ measured by a laser diffraction particle size distribution analyzer. ) Include 4 to 25 μm copper coarse particles, and the tap density of the copper coarse particles is 3.9 g / cm ³ or less, and the volume-based cumulative 10% particle diameter (D ₁₀ ) measured by a laser diffraction particle size distribution analyzer. If the ratio of the cumulative 90% particle diameter (D ₉₀ ) to is 3.65 or more and the ratio of the mass of the copper fine particles to the total amount of the copper fine particles and the copper coarse particles is 20% or more, It has been found that a conductive paste capable of forming a conductive film having good adhesion to the base material and weather resistance by light baking can be provided, and the present invention has been completed.

That is, the conductive paste according to the present invention includes copper fine particles having an average particle diameter of 10 to 100 nm and a copper coarse particle having a volume-based cumulative 50% particle diameter (D ₅₀ ) measured by a laser diffraction particle size distribution measuring device of 4 to 25 μm. 90% cumulative particle diameter (D ₁₀ ) with respect to a volume-based cumulative 10% particle diameter (D ₁₀ ) measured by a laser diffraction particle size distribution analyzer, wherein the tap density of copper coarse particles is 3.9 g / cm ³ or less. ₉₀ ) is 3.65 or more, and the ratio of the mass of the copper fine particles to the total amount of the copper fine particles and the copper coarse particles is 20% or more.

  In this conductive paste, the copper fine particles are preferably coated with an azole compound, and the azole compound is preferably benzotriazole. The conductive paste further contains a solvent and a resin, and the total amount of copper fine particles and copper coarse particles in the conductive paste is preferably 50 to 90% by mass. The solvent is preferably a glycol solvent, and the glycol solvent is preferably ethylene glycol. The resin is preferably a polyvinylpyrrolidone resin.

  Also, the method for producing a conductive film according to the present invention is characterized in that after the conductive paste is applied to a substrate and pre-baked, the conductive film is formed on the substrate by irradiation with light and baking. And

  In this method for producing a conductive film, the conductive paste is preferably applied by screen printing, and the preliminary baking is preferably performed by vacuum drying at 50 to 200 ° C. The light irradiation is preferably performed by irradiating light having a wavelength of 200 to 800 nm with a pulse period of 500 to 2000 μs and a pulse voltage of 1600 to 3800 V. Moreover, it is preferable to compress the electrically conductive film formed on the base material, and this compressing process is preferably performed by pressurizing the electrically conductive film formed on the base material with a roll. The average film thickness of the conductive film after the compression treatment is preferably 1 to 30 μm.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the electrically conductive paste which can form the electrically conductive paste with favorable adhesiveness with a base material and favorable weather resistance by light baking, and its, and a conductive film using the same can be provided.

It is a top view which shows the shape (RFID antenna circuit pattern) of the electrically conductive paste printed on the base material in an Example and a comparative example. 2 is a field emission electron microscope (FE-SEM) photograph (50,000 times) of the BTA-coated copper fine particles obtained in Example 1. FIG. 2 is an FE-SEM photograph (5,000 times) of flaky copper coarse particles obtained in Example 1. FIG. 2 is an FE-SEM photograph of a cross section of a conductive film after compression treatment obtained in Example 1.

Embodiments of the conductive paste according to the present invention include copper fine particles having an average particle diameter of 10 to 100 nm and a volume-based cumulative 50% particle diameter (D ₅₀ ) measured by a laser diffraction particle size distribution measuring device of 4 to 25 μm. 90% cumulative particle diameter with respect to a volume-based cumulative 10% particle diameter (D ₁₀ ) measured by a laser diffraction particle size distribution analyzer, wherein the copper coarse particles have a tap density of 3.9 g / cm ³ or less. The ratio of (D ₉₀ ) is 3.65 or more, and the ratio of the mass of copper fine particles to the total amount of copper fine particles and copper coarse particles is 20% or more.

  Since the copper fine particles having an average particle diameter of 10 to 100 nm are particles that are easily sintered, it is preferable that the surfaces of the copper fine particles are coated with an azole compound such as benzotriazole. If the surface of the copper fine particles is coated with an azole compound in this way, the storage stability of the copper fine particles can be improved, the light absorption can be improved, and it can be easily sintered by light irradiation. it can. In particular, since the azole compound has a conjugated double bond in the molecule, the copper fine particles can be easily sintered by absorbing light in the ultraviolet wavelength region (200 to 400 nm) and converting it into heat.

Copper coarse particles having a volume-based cumulative 50% particle diameter (D ₅₀ ) measured by a laser diffraction particle size distribution measuring device of 4 to 25 μm are baked by light irradiation to form a conductive film. Reducing the shrinkage of the conductive film due to bonding, preventing the conductive film from cracking and preventing the conductivity from deteriorating, and suppressing the conductivity from deteriorating even when the conductive film becomes thicker be able to. The tap density of the copper coarse particles are at 3.9 g / cm ³ or less, preferably at 3.8 g / cm ³ or less. The ratio of the cumulative 90% particle diameter (D ₉₀ ) to the volume-based cumulative 10% particle diameter (D ₁₀ ) measured by a laser diffraction particle size distribution measuring device of the copper coarse particles is 3.65 or more, It is preferably 3.7 or more. Further, BET specific surface area of the copper coarse particles is preferably from 0.3 to 1.5 m ² / g, and even more preferably 0.4~1.2m ² / g. The oxygen content in the copper coarse particles is preferably 2% by mass or less, and more preferably 0.1 to 1% by mass. The carbon content in the copper coarse particles is preferably 0.1 to 5% by mass, and more preferably 0.1 to 1% by mass.

Such copper coarse particles are obtained by using electrolytic copper powder having a volume-based cumulative 50% particle diameter (D ₅₀ ) measured by a laser diffraction particle size distribution measuring device of 5 to ₅₀ μm or wet copper powder having 1 to 10 μm as stearic acid or After coating with a fatty acid such as palmitic acid, it can be pulverized by a vibration mill or the like in a nitrogen atmosphere to obtain flaky copper coarse particles. This pulverization time is preferably about 10 to 150 minutes in the case of electrolytic copper powder, and preferably 150 minutes or more in the case of wet copper powder.

  The ratio of the mass of the copper fine particles to the total amount of the copper fine particles and the copper coarse particles in the conductive paste is 20% or more, and preferably 30% or more. The conductive paste preferably further contains a solvent and a resin. In this case, the total amount of copper fine particles and copper coarse particles in the conductive paste is preferably 50 to 90% by mass, and 60 to 80% by mass. More preferably.

  When this conductive paste is applied to a substrate such as paper to form a conductive film, the conductive paste solvent is preferably water-soluble in order to improve the wettability of the substrate, and copper is easily oxidized. It preferably has a functional hydroxyl group, and preferably has a boiling point of 180 ° C. or higher so that it can be continuously printed on the substrate. As the solvent having such properties, a glycol solvent is preferably used.

  As this glycol solvent, ethylene glycol, isopropylene glycol, 1,6-hexanediol, 1,3-propanediol, 1,4-butanediol, dipropylene glycol, 1,5-pentanediol, diethylene glycol, (molecular weight 200 Polyethylene glycol, methylpentanediol, triethylene glycol, etc. can be used, and ethylene glycol is preferably used.

  In addition, when a conductive film is formed by applying a conductive paste to a substrate such as paper, the resin contained in the conductive paste can improve adhesion to the substrate and dissolves in a glycol-based solvent at a high concentration. It is preferable that the resin be capable of imparting appropriate viscosity and sagging and capable of forming a flexible conductive film. Polyvinyl pyrrolidone (PVP) resin and polyvinyl butyral (PVB) resin can be used as the resin having such properties, and it is preferable to use polyvinyl pyrrolidone resin.

  When the conductive paste contains a polyvinylpyrrolidone resin, the amount of the polyvinylpyrrolidone resin in the conductive paste is preferably 3 to 9% by mass with respect to the total amount of the copper fine particles and the copper coarse particles. When polyvinyl butyral is included, the amount of polyvinyl butyral resin in the conductive paste is preferably 3 to 6% by mass with respect to the total amount of copper fine particles and copper coarse particles.

  Examples of the polyvinylpyrrolidone resin include Pitskor K-30 (weight average molecular weight 45,000), Pitzkor K-90 (weight average molecular weight 1,200,000) manufactured by DKS Corporation, Wako Pure Chemical Industries, Ltd. PVP K-25 (weight average molecular weight 20,000) etc. which can be used can be used, and as a polyvinyl butyral resin, for example, S-LEC B series, S-LEC K series, manufactured by Sekisui Chemical Co., Ltd. Kuraray's Mowital B series can be used.

  To the conductive paste, a dispersant may be added to the solvent in order to improve the dispersibility of the copper fine particles. The amount of the dispersant added is preferably 0.1 to 10% by mass, more preferably 0.1 to 2% by mass with respect to the conductive paste. Any dispersant may be used as long as it has an affinity for the surface of the copper fine particles and also has an affinity for the glycol solvent.

  Examples of the dispersant having such properties include nonionic polyoxyethylene (for example, TRITON X-100 manufactured by Sigma-Aldrich), polyoxyethylene (8) octylphenyl ether (for example, TRITON X manufactured by Sigma-Aldrich). -114), high molecular weight block copolymer (for example, DISPERBYK-190 manufactured by Big Chemie Japan Co., Ltd.), modified acrylic block copolymer (for example, DISPERBYK-2000, DISPERBYK-2001 manufactured by Big Chemie Japan Co., Ltd.), non- Ion fluorinated polyoxyethylene (for example, Zonyl FS300 manufactured by DuPont), fluorine-containing group / hydrophilic group-containing oligomer (for example, Megafac EXP TF-1540 manufactured by DIC Corporation, Megaf EXP EXP TF-1878, MegaFac F-480SF), lauryltrimethylammonium chloride (for example, Cotamin 24P manufactured by Kao Corporation), polyoxyethylene coconut alkylamine (for example, Amite 102 manufactured by Kao Corporation), polyoxy Ethylene distyrenated phenyl ether (for example, Emulgen A-60 manufactured by Kao Corporation), special polycarboxylic acid type surfactant (for example, Demol EP manufactured by Kao Corporation), naphthalenesulfonic acid formaldehyde condensate ammonium salt (for example, MX-2045L manufactured by Kao Corporation), polyoxyethylene-laurylamine (for example, Nimine L-202, Marialim HKM-150A manufactured by NOF Corporation), styrene-maleic acid half ester copolymer ammonium salt (example) For example, DKS Discoat N-14 manufactured by DKS Co., Ltd., polyoxyethylene styrenated phenyl ether (for example, Neugen EA-167 manufactured by DKS Co., Ltd.), polyoxyethylene (20) nonylphenyl ether (for example, Wako Pure) Yaku Kogyo Co., Ltd.), cationic surfactants (for example, Nop Cosperth 092 manufactured by San Nopco Co., Ltd.), and ethylene oxide adducts of acetylenic diol (for example, Dinol 604 manufactured by Nissin Chemical Industry Co., Ltd.). The dispersing agent which consists of these is mentioned.

  In addition, the conductive paste is added with a chlorine compound so that the mass ratio of Cl to the total amount of copper fine particles and copper coarse particles (Cl / Cu) is 0.1 to 0.5 mass%. preferable. Examples of the chlorine compounds include oxoacids such as hypochlorous acid, sodium chlorite, potassium chlorite, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, and other oxoacid salts such as hydrochloric acid. Inorganic salts such as hydrides, lithium salts, sodium salts, potassium salts, barium salts, strontium salts, ammonium salts, zirconium salts, aluminum salts, magnesium salts, calcium salts, and the like can be used. Among these, it is preferable to use one or more chlorine compounds selected from the group consisting of sodium chloride, ammonium chloride, potassium chloride, and calcium chloride.

  Further, the conductive paste may contain additives such as a rheology control agent, an adhesion imparting agent, and a defoaming agent.

  The conductive paste is preferably kneaded and defoamed with a stirring defoaming mixer, a three-roll mill, a planetary ball mill, a bead mill, a mortar, or the like.

  In the embodiment of the method for producing a conductive film according to the present invention, the conductive paste is applied to the substrate, pre-baked, and then irradiated with light to form the conductive film on the substrate.

  In this method for producing a conductive film, the conductive paste is preferably applied by screen printing. The pre-baking is preferably performed by heating with a vacuum dryer or an IR lamp heater. When pre-baking with a vacuum dryer, it is preferable to vacuum dry at 50 to 200 ° C. for 10 to 180 minutes, and when pre-baking with an IR lamp heater, a heat quantity of 140 to 600 J in the atmosphere is 5 to 5. Heating for 20 seconds is preferred. The light irradiation is preferably performed by irradiating light having a wavelength of 200 to 800 nm with a pulse period of 500 to 2000 μs and a pulse voltage of 1600 to 3800 V. This light irradiation can be performed by irradiating light with a xenon flash lamp or the like, can be performed in the air in a short time, and may be performed a plurality of times. A conductive film with favorable conductivity can be formed by this light irradiation.

  Moreover, it is preferable to compress the electrically conductive film formed on the base material by light irradiation. This compression treatment is preferably performed by pressing the conductive film formed on the substrate with a roll. By this compression treatment, a conductive film having an average film thickness of 1 to 30 μm and good conductivity and adhesion to the substrate can be formed.

  In the present specification, the “average particle diameter” of the copper fine particles refers to an average primary particle diameter calculated from a field emission scanning electron microscope (FE-SEM). About this "average primary particle diameter", for example, copper fine particles or copper coarse particles were observed with a field emission scanning electron microscope (FE-SEM) (S-4700 manufactured by Hitachi, Ltd.) and set at random. Within the observation field, all the particles that can grasp the outline representing the overall image of copper fine particles or copper coarse particles (that is, the particle contours because some of the particles are obstructed by other particles or are out of the field of view) All particles excluding particles that cannot be grasped) are selected, and for each of the total number N (of 200 or more) of the selected particles, the projected area S of the particles is determined from the particle outline in the FE-SEM image. The diameter D of a circle having an area equal to the projected area S is obtained, and a value obtained by dividing the sum of the diameters D by the total number N can be calculated as the average primary particle diameter.

  Hereinafter, the Example of the electrically conductive paste by this invention and the manufacturing method of the electrically conductive film using the same is described in detail.

[Example 1]
First, 280 g of copper sulfate pentahydrate (manufactured by JX Nippon Mining & Metals) as a copper source and 1 g of benzotriazole (BTA) (manufactured by Wako Pure Chemical Industries, Ltd.) as a dispersant were dissolved in 1330 g of pure water. Solution A, Solution B obtained by diluting 200 g of 50% by weight aqueous caustic soda solution (manufactured by Wako Pure Chemical Industries, Ltd.) as a neutralizing agent with 900 g of pure water, and 80% by weight hydrazine monohydrate (Otsuka Chemical) as a reducing agent A solution C prepared by diluting 150 g with a product of 1300 g of pure water was prepared.

Next, the solution A and the solution B are mixed with stirring, adjusted to a temperature of 60 ° C., and with the stirring maintained, the entire amount of the solution C is added to the mixed solution within 30 seconds. The reaction was complete. Dispersion in which ethylene glycol (EG) (manufactured by Wako Pure Chemical Industries, Ltd.) is passed through the solid content obtained by solid-liquid separation of the slurry produced by this reaction, and BTA-coated copper fine particles are dispersed in ethylene glycol. Got. When the copper fine particles in this dispersion were observed with a field emission scanning electron microscope (FE-SEM) (S-4700, manufactured by Hitachi, Ltd.), as shown in FIG. It was a spherical fine particle, and the average particle size was calculated to be 46.1 nm. Further, by a differential analysis in N ₂ in the dispersion was determined the content of copper in the dispersion was 85.3 wt%.

Moreover, electrolytic copper powder (FCC-115 (D ₅₀ = 20.4 μm) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.) was prepared, and 0.5% by mass of stearic acid was mixed with the copper powder to produce stearin. After obtaining copper powder coated with acid, 870 g of copper powder coated with stearic acid was pulverized in a nitrogen atmosphere with vibration mill MB-1 (manufactured by Chuo Kako Co., Ltd.) for 60 minutes, and sieved with an opening of 50 μm. Thus, flaky copper coarse particles as shown in FIG. 3 were obtained.

The BET specific surface area, tap density, oxygen content, carbon content and particle size distribution of the flaky copper coarse particles thus obtained were determined. The BET specific surface area was 0.57 m ² / g and the tap density was 3 0.6 g / cm ³ , the oxygen content was 0.27% by mass, and the carbon content was 0.36% by mass. The cumulative 10% particle diameter (D ₁₀ ) is 2.2 μm, the cumulative 50% particle diameter (D ₅₀ ) is 5.7 μm, the cumulative 90% particle diameter (D ₉₀ ) is 12.5 μm, and the standard deviation (SD) is It was 4.0 μm, D ₉₀ / D ₁₀ was 5.6, and SD / D ₉₀ was 0.70. In addition, the BET specific surface area of the copper coarse particle was calculated | required by the BET 1-point method using the BET specific surface area measuring apparatus (4 Sorb US made from a Yua sonics company). Further, the tap density of the coarse copper particles is formed by filling the coarse copper particles into a bottomed cylindrical container having an inner diameter of 6 mm to form a copper powder layer, as in the method described in JP-A-2007-263860. After applying a pressure of 0.16 N / m ² from the top to the copper powder layer, the height of the copper powder layer is measured, the measured value of the height of the copper powder layer, the weight of the filled copper powder, From this, the density of the copper coarse particles was determined and used as the tap density of the copper coarse particles. The oxygen content in the copper coarse particles was measured with an oxygen / nitrogen analyzer (TC-436 type manufactured by LECO), and the carbon content in the copper coarse particles was measured with a carbon / sulfur analyzer (EMIA manufactured by Horiba, Ltd.). -220V), the particle size distribution of the copper coarse particles was obtained by adding a sample of 0.3 g of copper coarse particles to 30 mL of isopropyl alcohol and ultrasonically dispersing for 5 minutes. MT3300EXII manufactured by Bell Co., Ltd.) was measured on a volume basis in the total reflection mode.

  Next, 29.2 g of the flaky copper coarse particles are added to 51.3 g of the BTA-coated copper fine particle dispersion (so that the mass ratio of the BTA-coated copper fine particles is 60:40). As a dispersant, 5.5 g of a surfactant made of ammonium salt of formaldehyde condensate of naphthalene sulfonate (Demol NL manufactured by Kao Chemical Co.) (the ratio of the active ingredient of the dispersant to Cu is 3.0% by mass), 60 5.5 g of ethylene glycol solution containing mass% polyvinyl pyrrolidone (PVP) resin (Pitzkol K-30 manufactured by Daiichi Kogyo Seiyaku Co., Ltd., weight average molecular weight 45,000) (the ratio of the resin to Cu is 4.5 mass) Chlorine in which 5% by mass of sodium chloride (NaCl) (manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in ethylene glycol as a chlorine compound 4.4 g of the compound solution (the ratio of the mass of Cl to Cu (Cl / Cu) is 0.35 mass%), and further (to make the Cu concentration 73.0 mass%) 4.12 g of ethylene glycol And then rotating for 60 seconds at 1400 rpm with a self-revolving vacuum stirring and defoaming mixer (V-mini300 manufactured by EME Co., Ltd.) so that the BTA-coated copper fine particles and the flaky copper coarse particles become uniform. After defoaming, the BTA-coated copper fine particles (conductive filler 1) and the flaky copper powder (conductive filler) are dispersed by passing three rolls and uniformly dispersing the BTA-coated copper fine particles and the flaky copper coarse particles. 100 g of conductive paste containing conductive filler 2) (Cu concentration 73.0 mass%) and 0.22 mass% NaCl was obtained.

  Next, using a screen plate (ST200-40-80 manufactured by Sonocom Co., Ltd., screen plate having a mesh number of 200 LPI, a wire diameter of 40 μm, a thickness of 80 μm, and an emulsion thickness of 10 μm), coated paper (Mitsubishi Paper) In the region of the size of about 70 mm × 15 mm on the DF color M70 made of the above, the above-mentioned conductive paste is formed into the shape shown in FIG. 1 having a conductive length of 146 mm (total length 69.8 mm, total width 14.6 mm, line width about 0) .7mm RFID antenna 10 shape (reference numeral 11 indicates an IC chip mounting portion) is screen-printed, and preliminarily baked in a vacuum dryer for 60 minutes at 100 ° C. Xenon flash run with a pulse period of 2000 μs and a pulse voltage of 2900 V in an air atmosphere. The conductive film (in the shape of the RFID antenna 10) was obtained by irradiating with a light having a wavelength of 200 to 800 nm and firing. The electric resistance (line resistance) of this conductive film was measured by a tester (model CDM-03D manufactured by CUSTOM) and found to be 2.7Ω.

  Next, in order to improve the adhesion between the obtained conductive film and the base material, the work roll of the roll press machine together with the base material (steel roll having a diameter of 400 mm whose surface temperature can be controlled by an external heater). In the meantime, the compression treatment was performed by passing and pressurizing as linear pressure (load per unit length in the axial direction of the roll) 1818 N / mm, peripheral speed 1 / min of roll, and surface temperature of roll 180 ° C. . When the average film thickness was determined as the average value of the five film thicknesses randomly selected in the FE-SEM photograph of the cross section of the conductive film thus subjected to the compression treatment, the average of the conductive films after the compression treatment was obtained. The film thickness was 10.5 μm. The electrical resistance (line resistance) of the conductive film after the compression treatment was measured by a tester (model CDM-03D manufactured by CUSTOM), which was 1.4Ω, and the rate of change in electrical resistance due to the compression treatment was 52%. (= 1.4 × 100 / 2.7).

  Next, as a weather resistance test, the conductive film after the compression treatment was held in a constant temperature and humidity apparatus set at a temperature of 85 ° C. and a humidity of 85% for 168 hours, and then the electric resistance of the conductive film was measured by a tester (model made by CUSTOM). When measured by CDM-03D), it was 2.2Ω, and the rate of change in electrical resistance by the weather resistance test was 157% (= 2.2 × 100 / 1.4).

[Example 2]
Except for using palmitic acid in place of stearic acid, by the same method as in Example 1, after obtaining copper powder coated with palmitic acid, flaky copper coarse particles were obtained.

The BET specific surface area, tap density, oxygen content, carbon content and particle size distribution of the flaky copper coarse particles thus obtained were determined in the same manner as in Example 1. The BET specific surface area was 0.90 m. ² / g, the tap density was 3.3 g / cm ³ , the oxygen content was 0.40 mass%, and the carbon content was 0.39 mass%. The cumulative 10% particle size (D ₁₀ ) is 2.5 μm, the cumulative 50% particle size (D ₅₀ ) is 6.6 μm, the cumulative 90% particle size (D ₉₀ ) is 15.2 μm, and the standard deviation (SD) is It was 4.8 μm, D ₉₀ / D ₁₀ was 6.2, and SD / D ₉₀ was 0.73.

  Moreover, after obtaining conductive paste by the method similar to Example 1 using said flaky copper coarse particle, after using this conductive paste, pulse voltage was set to 2850V, Example When the electrical resistance of the obtained conductive film was measured by the same method as in Example 1, it was 2.7Ω.

  The obtained conductive film was subjected to compression treatment in the same manner as in Example 1, and the electrical resistance of the conductive film was measured. As a result, it was 1.8Ω, and the rate of change in electrical resistance due to compression treatment was It was 67% (= 1.8 × 100 / 2.7).

  Further, the conductive film subjected to the compression treatment was subjected to a weather resistance test in the same manner as in Example 1, and then the electrical resistance of the conductive film was measured. The change rate of was 244% (= 4.4 × 100 / 1.8). In addition, if the change rate of the electrical resistance after this weather resistance test is 300% or less, it can be evaluated that the conductive film has practically excellent weather resistance as an RFID antenna using a paper substrate.

[Example 3]
Except for the pulverization time being 15 minutes, flaky copper coarse particles were obtained by the same method as in Example 1 after obtaining copper powder coated with stearic acid.

The BET specific surface area, tap density, oxygen content, carbon content and particle size distribution of the flaky copper coarse particles thus obtained were determined by the same method as in Example 1. The BET specific surface area was 0.45 m. ² / g, the tap density was 3.2 g / cm ³ , the oxygen content was 0.26 mass%, and the carbon content was 0.37 mass%. The cumulative 10% particle diameter (D ₁₀ ) is 3.0 μm, the cumulative 50% particle diameter (D ₅₀ ) is 7.4 μm, the cumulative 90% particle diameter (D ₉₀ ) is 14.4 μm, and the standard deviation (SD) is It was 4.6 μm, D ₉₀ / D ₁₀ was 4.8, and SD / D ₉₀ was 0.63.

  Moreover, after obtaining conductive paste by the method similar to Example 1 using said flaky copper coarse particle, this Example is used except that this conductive paste was used and the pulse voltage was set to 2930V. When the electric resistance of the obtained conductive film was measured by the same method as in Example 1, it was 2.9Ω.

  Further, the obtained conductive film was subjected to compression treatment by the same method as in Example 1, and then the electrical resistance of the conductive film was measured. It was 52% (= 1.5 × 100 / 2.9).

  Moreover, about the electrically conductive film which carried out the compression process, after performing a weather resistance test by the method similar to Example 1, when the electrical resistance of a conductive film was measured, it was 2.9 (ohm), and the electrical resistance by a weather resistance test is The rate of change was 193% (= 2.9 × 100 / 1.5).

[Example 4]
Except that the pulverization time was 30 minutes, by the same method as in Example 1, after obtaining copper powder coated with stearic acid, flaky copper coarse particles were obtained.

The BET specific surface area, tap density, oxygen content, carbon content and particle size distribution of the flaky copper coarse particles thus obtained were determined by the same method as in Example 1. The BET specific surface area was 0.53 m. ² / g, the tap density was 3.4 g / cm ³ , the oxygen content was 0.31% by mass, and the carbon content was 0.38% by mass. The cumulative 10% particle size (D ₁₀ ) is 2.5 μm, the cumulative 50% particle size (D ₅₀ ) is 6.3 μm, the cumulative 90% particle size (D ₉₀ ) is 13.2 μm, and the standard deviation (SD) is It was 4.2 μm, D ₉₀ / D ₁₀ was 5.2, and SD / D ₉₀ was 0.67.

  Moreover, after obtaining conductive paste by the method similar to Example 1 using said flaky copper coarse particle, this Example is used except that this conductive paste was used and the pulse voltage was changed to 2870V. When the electric resistance of the obtained conductive film was measured by the same method as in Example 1, it was 2.2Ω.

  Further, the obtained conductive film was subjected to compression treatment by the same method as in Example 1, and then the electrical resistance of the conductive film was measured. It was 68% (= 1.5 × 100 / 2.2).

  Further, the conductive film subjected to the compression treatment was subjected to a weather resistance test in the same manner as in Example 1, and then the electrical resistance of the conductive film was measured. The change rate of was 220% (= 3.3 × 100 / 1.5).

[Example 5]
Except that the pulverization time was 90 minutes, flaky copper coarse particles were obtained by the same method as in Example 1 after obtaining copper powder coated with stearic acid.

The BET specific surface area, tap density, oxygen content, carbon content and particle size distribution of the flaky copper coarse particles thus obtained were determined by the same method as in Example 1. The BET specific surface area was 1.17 m. ² / g, the tap density was 3.4 g / cm ³ , the oxygen content was 0.51% by mass, and the carbon content was 0.39% by mass. The cumulative 10% particle diameter (D ₁₀ ) is 3.0 μm, the cumulative 50% particle diameter (D ₅₀ ) is 8.0 μm, the cumulative 90% particle diameter (D ₉₀ ) is 19.9 μm, and the standard deviation (SD) is It was 6.5 μm, D ₉₀ / D ₁₀ was 6.6, and SD / D ₉₀ was 0.82.

  Moreover, after obtaining conductive paste by the method similar to Example 1 using said flaky copper coarse particle, this Example is used except that this conductive paste was used and the pulse voltage was set to 2930V. When the electrical resistance of the obtained conductive film was measured by the same method as in Example 1, it was 2.8Ω.

  Further, the obtained conductive film was subjected to compression treatment by the same method as in Example 1, and the electrical resistance of the conductive film was measured. As a result, it was 1.6Ω. It was 57% (1.6 × 100 / 2.8).

  The conductive film subjected to the compression treatment was subjected to a weather resistance test in the same manner as in Example 1, and then the electrical resistance of the conductive film was measured to be 2.9Ω. The change rate of was 181% (= 2.9 × 100 / 1.6).

[Example 6]
Except for the pulverization time being 120 minutes, flake-like copper coarse particles were obtained by the same method as in Example 1 after obtaining copper powder coated with stearic acid.

The BET specific surface area, tap density, oxygen content, carbon content and particle size distribution of the flaky copper coarse particles thus obtained were determined in the same manner as in Example 1. The BET specific surface area was 0.84 m. ² / g, the tap density was 3.3 g / cm ³ , the oxygen content was 0.54 mass%, and the carbon content was 0.39 mass%. The cumulative 10% particle diameter (D ₁₀ ) is 6.5 μm, the cumulative 50% particle diameter (D ₅₀ ) is 19.9 μm, the cumulative 90% particle diameter (D ₉₀ ) is 37.0 μm, and the standard deviation (SD) is It was 12.8 μm, D ₉₀ / D ₁₀ was 5.7, and SD / D ₉₀ was 0.64.

  Moreover, after obtaining conductive paste by the method similar to Example 1 using said flaky copper coarse particle, this Example is used except that this conductive paste was used and the pulse voltage was changed to 2810V. When the electrical resistance of the obtained conductive film was measured by the same method as in Example 1, it was 3.0Ω.

  Further, the obtained conductive film was subjected to compression treatment by the same method as in Example 1, and the electrical resistance of the conductive film was measured. As a result, it was 1.7Ω. It was 57% (= 1.7 × 100 / 3.0).

  Further, the conductive film subjected to the compression treatment was subjected to a weather resistance test by the same method as in Example 1, and then the electrical resistance of the conductive film was measured. The rate of change was 288% = 4.9 × 100 / 1.7).

[Example 7]
After obtaining a copper powder coated with stearic acid by the same method as in Example 1 except that electrolytic copper powder (# 6 (D ₅₀ = 20.7 μm) manufactured by JX Nippon Mining & Metals Co., Ltd.) was used. Thus, flaky copper coarse particles were obtained.

The BET specific surface area, tap density, oxygen content, carbon content and particle size distribution of the flaky copper coarse particles thus obtained were determined in the same manner as in Example 1. The BET specific surface area was 0.88 m. ² / g, the tap density was 3.0 g / cm ³ , the oxygen content was 0.41% by mass, and the carbon content was 0.39% by mass. The cumulative 10% particle diameter (D ₁₀ ) is 4.9 μm, the cumulative 50% particle diameter (D ₅₀ ) is 12.8 μm, the cumulative 90% particle diameter (D ₉₀ ) is 25.6 μm, and the standard deviation (SD) is It was 8.2 μm, D ₉₀ / D ₁₀ was 5.2, and SD / D ₉₀ was 0.64.

  Moreover, after obtaining conductive paste by the method similar to Example 1 using said flaky copper coarse particle, after using this conductive paste, pulse voltage was set to 2940V Example When the electrical resistance of the obtained conductive film was measured by the same method as in Example 1, it was 1.9Ω.

  The obtained conductive film was subjected to compression treatment by the same method as in Example 1, and the electrical resistance of the conductive film was measured. As a result, it was 1.4Ω, and the rate of change in electrical resistance due to compression treatment was It was 74% (= 1.4 × 100 / 1.9).

  Further, the conductive film subjected to the compression treatment was subjected to a weather resistance test in the same manner as in Example 1, and then the electrical resistance of the conductive film was measured. The change rate of was 243% (= 3.4 × 100 / 1.4).

[Example 8]
A copper powder coated with stearic acid was obtained in the same manner as in Example 1 except that electrolytic copper powder (CE-20 manufactured by Fukuda Metal Foil Powder Co., Ltd. (D ₅₀ = 44.0 μm)) was used. Thereafter, flaky copper coarse particles were obtained.

The BET specific surface area, tap density, oxygen content, carbon content and particle size distribution of the flaky copper coarse particles thus obtained were determined by the same method as in Example 1. The BET specific surface area was 0.74 m. ² / g, the tap density was 2.8 g / cm ³ , the oxygen content was 0.38% by mass, and the carbon content was 0.35% by mass. Further, the cumulative 10% particle size (D ₁₀ ) is 8.5 μm, the cumulative 50% particle size (D ₅₀ ) is 21.4 μm, the cumulative 90% particle size (D ₉₀ ) is 38.2 μm, and the standard deviation (SD) is 12.1 μm, D ₉₀ / D ₁₀ was 4.5, and SD / D ₉₀ was 0.57.

  Moreover, after obtaining conductive paste by the method similar to Example 1 using said flaky copper coarse particle, this Example is used except that this conductive paste was used and the pulse voltage was set to 2930V. When the electric resistance of the obtained conductive film was measured by the same method as in Example 1, it was 2.2Ω.

  The obtained conductive film was subjected to compression treatment by the same method as in Example 1, and the electrical resistance of the conductive film was measured. As a result, it was 1.4Ω, and the rate of change in electrical resistance due to compression treatment was It was 64% (= 1.4 × 100 / 2.2).

  Further, the conductive film subjected to the compression treatment was subjected to a weather resistance test in the same manner as in Example 1, and then the electrical resistance of the conductive film was measured. The change rate of was 257% (= 3.6 × 100 / 1.4).

[Example 9]
Wet copper powder (DOWA Electronics Co., _Ltd., D 50 = 3.0 [mu] m) in place of the electrolytic copper powder using, except that the addition amount of stearic acid and 1.0 wt%, and the milling time was between 200 minutes, After obtaining copper powder coated with stearic acid by the same method as in Example 1, flaky copper coarse particles were obtained.

The BET specific surface area, tap density, oxygen content, carbon content and particle size distribution of the flaky copper coarse particles thus obtained were determined in the same manner as in Example 1. The BET specific surface area was 0.98 m. ² / g, the tap density was 3.7 g / cm ³ , the oxygen content was 0.53% by mass, and the carbon content was 0.77% by mass. The cumulative 10% particle size (D ₁₀ ) is 2.2 μm, the cumulative 50% particle size (D ₅₀ ) is 4.3 μm, the cumulative 90% particle size (D ₉₀ ) is 8.0 μm, and the standard deviation (SD) is 2.2 μm, D ₉₀ / D ₁₀ was 3.7, and SD / D ₉₀ was 0.50.

  Moreover, after obtaining conductive paste by the method similar to Example 1 using said flaky copper coarse particle, after using this conductive paste and setting pulse voltage to 3000V, it is Example. When the electrical resistance of the obtained conductive film was measured by the same method as in Example 1, it was 2.6Ω.

  Further, the obtained conductive film was subjected to compression treatment by the same method as in Example 1, and the electrical resistance of the conductive film was measured. As a result, it was 1.3Ω. It was 50% (= 1.3 × 100 / 2.6).

  In addition, the conductive film subjected to the compression treatment was subjected to a weather resistance test in the same manner as in Example 1, and then the electrical resistance of the conductive film was measured. The change rate of was 269% (= 3.5 × 100 / 1.3).

[Example 10]
(The BTA-coated copper fine particles and the flaky copper coarse particles have a mass ratio of 30:70) The amount of the BTA-coated copper fine particle dispersion is 25.7 g, and the flaky copper coarse particles are the same as in Example 1. Except that 51.1 g was added, a conductive paste was obtained by the same method as in Example 1, and then the same method as in Example 1 except that this conductive paste was used and the pulse voltage was changed to 2700 V. As a result, the electric resistance of the obtained conductive film was measured and found to be 2.3Ω.

  Further, the obtained conductive film was subjected to compression treatment by the same method as in Example 1, and the electrical resistance of the conductive film was measured. As a result, it was 1.7Ω. It was 74% (= 1.7 × 100 / 2.3).

  Further, the conductive film subjected to the compression treatment was subjected to a weather resistance test in the same manner as in Example 1, and then the electrical resistance of the conductive film was measured. The change rate of was 282% (= 4.8 × 100 / 1.7).

[Example 11]
(The ratio of the mass of the BTA-coated copper fine particles and the flaky copper coarse particles is 50:50) The amount of the BTA-coated copper fine particle dispersion is 42.8 g, and the same flaky copper coarse particles as in Example 1 Except for adding 36.5 g, after obtaining a conductive paste by the same method as in Example 1, the same method as in Example 1 except that this conductive paste was used and the pulse voltage was changed to 2720V. Thus, the electric resistance of the obtained conductive film was measured and found to be 3.3Ω.

  Further, the obtained conductive film was subjected to compression treatment by the same method as in Example 1, and then the electrical resistance of the conductive film was measured. It was 45% (= 1.5 × 100 / 3.3).

  In addition, the conductive film subjected to the compression treatment was subjected to a weather resistance test in the same manner as in Example 1, and then the electrical resistance of the conductive film was measured. The rate of change was 233% (= 3.5 × 100 / 1.5).

[Comparative Example 1]
Except for using wet copper powder (D ₅₀ = 3.0 μm, manufactured by DOWA Electronics Co., Ltd.) instead of electrolytic copper powder, the addition amount of stearic acid was 1.0 mass%, and the grinding time was 30 minutes, After obtaining copper powder coated with stearic acid by the same method as in Example 1, flaky copper coarse particles were obtained.

The BET specific surface area, tap density, oxygen content, carbon content and particle size distribution of the flaky copper coarse particles thus obtained were determined by the same method as in Example 1. The BET specific surface area was 0.35 m. ² / g, the tap density was 4.5 g / cm ³ , the oxygen content was 0.53% by mass, and the carbon content was 0.75% by mass. The cumulative 10% particle size (D ₁₀ ) is 2.4 μm, the cumulative 50% particle size (D ₅₀ ) is 3.7 μm, the cumulative 90% particle size (D ₉₀ ) is 7.0 μm, and the standard deviation (SD) is 1.7 μm, D ₉₀ / D ₁₀ was 3.0, and SD / D ₉₀ was 0.46.

  Moreover, after obtaining conductive paste by the method similar to Example 1 using said flaky copper coarse particle, after using this conductive paste, pulse voltage was set to 2950V Example When the electrical resistance of the obtained conductive film was measured by the same method as in Example 1, it was 114.0Ω.

  Further, the obtained conductive film was subjected to compression treatment by the same method as in Example 1, and the electrical resistance of the conductive film was measured. As a result, it was 2.4Ω. It was 2% (= 2.4 × 100 / 114.0).

  In addition, the conductive film subjected to the compression treatment was subjected to a weather resistance test in the same manner as in Example 1, and then the electrical resistance of the conductive film was measured to be 19.6Ω. The change rate of was 817% (= 19.6 × 100 / 2.4).

[Comparative Example 2]
Coated with stearic acid in the same manner as in Example 1 except that wet copper powder (D ₅₀ = 6.0 μm, manufactured by DOWA Electronics Co., Ltd.) was used instead of electrolytic copper powder and the grinding time was 100 minutes. After obtaining the obtained copper powder, flaky copper coarse particles were obtained.

The BET specific surface area, tap density, oxygen content, carbon content and particle size distribution of the flaky copper coarse particles thus obtained were determined by the same method as in Example 1. As a result, the BET specific surface area was 0.46 m. ² / g, the tap density was 4.0 g / cm ³ , the oxygen content was 0.40 mass%, and the carbon content was 0.41 mass%. The cumulative 10% particle size (D ₁₀ ) is 4.4 μm, the cumulative 50% particle size (D ₅₀ ) is 9.7 μm, the cumulative 90% particle size (D ₉₀ ) is 16.1 μm, and the standard deviation (SD) is The thickness was 4.4 μm, D ₉₀ / D ₁₀ was 3.6, and SD / D ₉₀ was 0.46.

  Moreover, after obtaining conductive paste by the method similar to Example 1 using said flaky copper coarse particle, after using this conductive paste and setting pulse voltage to 2920V, Example When the electrical resistance of the obtained conductive film was measured by the same method as in Example 1, it was 2.7Ω.

  Further, the obtained conductive film was subjected to compression treatment by the same method as in Example 1, and the electrical resistance of the conductive film was measured. As a result, it was 1.6Ω. It was 59% (= 1.6 × 100 / 2.7).

  Further, the conductive film subjected to the compression treatment was subjected to a weather resistance test by the same method as in Example 1, and then the electrical resistance of the conductive film was measured. As a result, it was 6.8Ω. The change rate of was 425% (= 6.8 × 100 / 1.6).

[Comparative Example 3]
73.0 g of flaky copper coarse particles similar to Example 1 without using a dispersion of BTA-coated copper fine particles (so that the mass ratio of BTA-coated copper fine particles to flaky copper coarse particles is 0: 100) The conductive paste was obtained by the same method as in Example 1, except that the pulse voltage was changed to 2850 V using this conductive paste. The electric resistance of the obtained conductive film was measured and found to be 24.9Ω.

  The obtained conductive film was subjected to compression treatment in the same manner as in Example 1, and the electrical resistance of the conductive film was measured. As a result, it was 26.0Ω. It was 104% (= 26.0 × 100 / 24.9).

  Further, the conductive film subjected to the compression treatment was subjected to a weather resistance test in the same manner as in Example 1, and then the electrical resistance of the conductive film was measured to be 369.2 Ω. The change rate of was 1420% (= 369.2 × 100 / 26.0).

[Comparative Example 4]
(The BTA-coated copper fine particles and the flaky copper coarse particles have a mass ratio of 15:85) The amount of the BTA-coated copper fine particles is 12.8 g, and the flaky copper coarse particles are the same as in Example 1. Except for adding 62.1 g, after obtaining a conductive paste by the same method as in Example 1, the same method as in Example 1 except that this conductive paste was used and the pulse voltage was changed to 2450V. Thus, the electric resistance of the obtained conductive film was measured and found to be 10.0Ω.

  The obtained conductive film was subjected to compression treatment in the same manner as in Example 1, and the electrical resistance of the conductive film was measured. As a result, it was 3.2Ω, and the rate of change in electrical resistance due to compression treatment was It was 32% (= 3.2 × 100 / 10.0).

Further, the conductive film subjected to the compression treatment was subjected to a weather resistance test in the same manner as in Example 1, and then the electrical resistance of the conductive film was measured. The change rate of was 650% (= 20.8 × 100 / 3.2).
Tables 1 to 5 show the manufacturing conditions and characteristics of the conductive pastes of these Examples and Comparative Examples, and the manufacturing conditions and characteristics of the conductive films using the conductive paste.

  When an inlay (consisting of an IC chip and an antenna) is manufactured by incorporating an RFID tag antenna such as an IC tag antenna formed using a conductive film manufactured from the conductive paste according to the present invention, a practical communication distance RFID tags such as IC tags can be manufactured.

10 RFID antenna 11 IC chip mounting part

Claims (14)

A copper coarse particle tap comprising copper fine particles having an average particle diameter of 10 to 100 nm and copper coarse particles having a volume-based cumulative 50% particle diameter (D ₅₀ ) of 4 to 25 μm measured by a laser diffraction particle size distribution analyzer. The density is 3.9 g / cm ³ or less, and the ratio of the cumulative 90% particle diameter (D ₉₀ ) to the volume-based cumulative 10% particle diameter (D ₁₀ ) measured by a laser diffraction particle size distribution analyzer is 3.65 or more. A conductive paste characterized in that the ratio of the mass of copper fine particles to the total amount of copper fine particles and copper coarse particles is 20% or more. The conductive paste according to claim 1, wherein the copper fine particles are coated with an azole compound. The conductive paste according to claim 2, wherein the azole compound is benzotriazole. The conductive paste contains a solvent and a resin, and the total amount of the copper fine particles and the copper coarse particles in the conductive paste is 50 to 90% by mass. The conductive paste as described. The conductive paste according to claim 4, wherein the solvent is a glycol-based solvent. The conductive paste according to claim 5, wherein the glycol solvent is ethylene glycol. The conductive paste according to claim 4, wherein the resin is a polyvinyl pyrrolidone resin. A conductive film is formed on a substrate by applying the conductive paste according to any one of claims 1 to 7 to a substrate and pre-baking, and then irradiating and baking light. Manufacturing method of electrically conductive film. The method for producing a conductive film according to claim 8, wherein the conductive paste is applied by screen printing. The method for producing a conductive film according to claim 8 or 9, wherein the preliminary baking is performed by vacuum drying at 50 to 200 ° C. The conductive film according to claim 8, wherein the light irradiation is performed by irradiating light having a wavelength of 200 to 800 nm with a pulse period of 500 to 2000 μs and a pulse voltage of 1600 to 3800 V. Manufacturing method. The method for producing a conductive film according to claim 8, wherein the conductive film formed on the base material is compressed. The method for producing a conductive film according to claim 12, wherein the compression treatment is performed by pressurizing the conductive film formed on the substrate with a roll. The method for producing a conductive film according to claim 12 or 13, wherein an average film thickness of the conductive film after the compression treatment is 1 to 30 µm.

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