JP2019083182A - Conductive paste - Google Patents

Abstract

To provide a conductive paste capable of preventing deterioration of conversion efficiency of a solar cell even if a bus bar electrode of the solar cell manufactured with a resin-type conductive paste using silver-coated copper powder is connected to a tab line by soldering.SOLUTION: A conductive paste includes a resin and silver-coated copper powder in which a silver layer is coating a surface of copper powder with a cumulative 50% particle diameter (Ddiameter) of 0.1 to 15 μm measured in a volume basis by a laser diffraction type grain size distribution apparatus. The conductive paste employs, as the resin, an epoxy resin having a naphthalene skeleton, and preferably adds, at least one of imidazole and a boron trifluoride amine-based curative, as a curative.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a conductive paste, and in particular to a conductive paste using silver-coated copper powder as a conductive metal powder.

  Conventionally, in order to form an electrode or wiring of an electronic component by a printing method or the like, a conductive paste prepared by mixing a solvent, a resin, a dispersant, etc. with a conductive metal powder such as silver powder or copper powder is used. .

  However, although silver powder has a very low volume resistivity and is a good conductive material, it is a powder of a noble metal, which increases the cost. Copper powder, on the other hand, has a low volume resistivity and is a good conductive substance, but is easily oxidized and therefore inferior in storage stability (reliability) to silver powder.

  In order to solve these problems, silver-coated copper powder in which the surface of copper powder is coated with silver is proposed as a metal powder used for a conductive paste (for example, refer to patent documents 1-2).

  In recent years, as a conductive paste for forming bus bar electrodes of solar cells, it has been attempted to use a conductive paste using silver-coated copper powder, which is cheaper than silver powder, in place of the conductive paste using silver powder. .

  In a general crystalline silicon solar cell, an electrode is formed by firing a firing-type conductive paste using silver powder at a high temperature of about 800 ° C. in the atmosphere, but copper powder or silver-coated copper powder is used. When using a conductive paste made of copper, the copper powder and the silver-coated copper powder are oxidized when firing at such high temperatures in the atmosphere, so special techniques such as firing in an inert atmosphere Will be required, which will increase the cost

  On the other hand, in HIT (single crystal hybrid type) solar cells, etc., an electrode is generally formed by heating and curing a resin-curable conductive paste using silver powder at about 200 ° C. in the atmosphere, Since copper powder and silver-coated copper powder can resist oxidation even when heated at such a low temperature in the air atmosphere, it is possible to use a resin-curable conductive paste using silver-coated copper powder Become.

  In addition, in the case of manufacturing a HIT solar cell by connecting an electrode formed of a conventional resin-hardened conductive paste to a tab wire, if the electrode and the tab wire are soldered and connected, the soldering temperature (380 ° C.) Since the resin of the conductive paste is decomposed by the degree), the conductive adhesive that is more expensive than the solder is used to connect the electrode and the tab wire.

JP, 2010-174311, A (paragraph number 0003) JP, 2010-077495, A (paragraph number 0006)

  A busbar electrode formed of a conductive paste of resin type using a silver-coated copper powder as a conductive filler and a bisphenol A epoxy resin as a resin is connected to a tab wire by a conductive adhesive to produce a HIT solar cell As a result, it was found that the solar cell had a conversion efficiency as high as when silver powder was used.

  However, when the bus bar electrode formed with the conductive paste of resin type obtained by kneading the silver-coated copper powder as described above and bisphenol A epoxy resin etc. is connected to the tab wire by soldering, the resistance of the bus bar electrode is It turned out that it may become high and the conversion efficiency of a solar cell may fall. Such a problem does not occur when silver powder is used instead of the silver-coated copper powder of the above-mentioned resin type conductive paste.

  Therefore, in view of such problems, the present invention is directed to a solar cell of the present invention, even if the bus bar electrodes of a solar cell produced by using a conductive paste of resin type using silver-coated copper powder are connected to tab wires by soldering. An object of the present invention is to provide a conductive paste capable of preventing a reduction in conversion efficiency.

  As a result of intensive studies to solve the above problems, the present inventors have found that a conductive paste of resin type includes silver-coated copper powder in which the surface of copper powder is coated with a silver layer, and an epoxy resin having a naphthalene skeleton. As a result, it has been found that if the bus bar electrode of the solar cell is manufactured, reduction in the conversion efficiency of the solar cell can be prevented even if the bus bar electrode is connected to the tab wire by soldering, and the present invention has been completed.

That is, the conductive paste according to the present invention is characterized in that it contains a silver-coated copper powder in which the surface of the copper powder is coated with a silver layer, and an epoxy resin having a naphthalene skeleton. The conductive paste preferably contains a solvent. The conductive paste preferably contains a curing agent, and the curing agent is preferably at least one of imidazole and a boron trifluoride amine-based curing agent. The amount of silver relative to the silver-coated copper powder is preferably 5% by mass or more, and the cumulative 50% particle diameter (D ₅₀ diameter) of volume based on copper powder measured by a laser diffraction type particle size distribution device is 0.1 to 15 μm Is preferred. The amount of silver-coated copper powder in the conductive paste is preferably 50 to 90% by mass.

  The method for producing a solar cell electrode according to the present invention is characterized in that the above-mentioned conductive paste is applied to a substrate and then cured to form the electrode on the surface of the substrate.

  According to the present invention, even if the bus bar electrode of the solar cell manufactured by the conductive paste of the resin type using the silver-coated copper powder is connected to the tab wire by soldering, the reduction of the conversion efficiency of the solar cell is prevented. Conductive paste can be provided.

It is a figure which shows the scanning electron microscope (SEM) image of the cross section of the bus-bar electrode formed in the surface side (cover glass side) of the cell with an interconnector of the solar cell module produced by Comparative Example 8. It is a figure which shows the SEM image of the cross section of the bus-bar electrode formed in the surface side (cover glass side) of the cell with an interconnector of the solar cell module produced in Example 5. FIG. It is a figure which shows Ag map image by mapping analysis of the cross section of the bus-bar electrode formed in the surface side (cover glass side) of the cell with an interconnector of the solar cell module produced in Example 5. FIG. It is a figure which shows Cu map image by mapping analysis of the cross section of the bus-bar electrode formed in the surface side (cover glass side) of the cell with an interconnector of the solar cell module produced in Example 5. FIG.

  The embodiment of the conductive paste according to the present invention includes a silver-coated copper powder in which the surface of the copper powder is coated with a silver layer, and an epoxy resin having a naphthalene skeleton.

  As a resin having a naphthalene skeleton contained in this conductive paste, an epoxy resin having a naphthalene skeleton as shown in Chemical Formula 1 (for example, HP 4710 manufactured by Dainippon Ink & Chemicals, Inc.) can be used. The content of the epoxy resin having a naphthalene skeleton is preferably 1 to 20% by mass, and more preferably 3 to 10% by mass with respect to the conductive paste. If the content of the epoxy resin having a naphthalene skeleton is too low, the function of protecting the surface of the silver-coated copper powder from thermal oxidation becomes insufficient. On the other hand, if the amount is too large, the printability when printing on the bus bar electrode shape of the solar cell with the conductive paste and the adhesive strength of the solder when soldering the bus bar electrode to the tab wire deteriorate, The resistance of the bus bar electrode of the solar cell increases. In addition, it can be identified by gas chromatograph mass spectrometer (GC-MS) or C13-NMR whether it is an epoxy resin which has naphthalene frame.

  The conductive paste preferably contains a curing agent, and it is preferred to use at least one of imidazole and a boron trifluoride amine curing agent as the curing agent. The content of the curing agent is preferably 1 to 10% by mass, and more preferably 2 to 6% by mass with respect to the epoxy resin.

  The conductive paste preferably contains a solvent, and the solvent can be appropriately selected according to the purpose of use of the conductive paste. For example, butyl carbitol acetate (BCA), butyl carbitol (BC), ethyl carbitol acetate (ECA), ethyl carbitol (EC), toluene, methyl ethyl ketone, methyl isobutyl ketone, tetradecane, tetralin, propyl alcohol, isopropyl alcohol, One or more solvents can be selected and used from dihydroterpineol, dihydroterpineol acetate, ethyl carbitol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Texanol) and the like. The content of the solvent is preferably 0 to 20% by mass, and more preferably 0 to 10% by mass with respect to the conductive paste.

  The conductive paste may also contain other components such as surfactants, dispersants, rheology modifiers, silane coupling agents, and ion collectors.

  In the conductive paste, a silver-coated copper powder in which the surface of the copper powder is coated with a silver layer is used as a conductor. The shape of the copper powder (silver-coated copper powder) coated with the silver layer may be substantially spherical or flake-like.

  The silver layer is preferably a layer made of silver or a silver compound, and more preferably a layer made of 90% by mass or more of silver. The amount of silver relative to the silver-coated copper powder is preferably 5% by mass or more, more preferably 7 to 50% by mass, still more preferably 8 to 40% by mass, and 9 to 20% by mass Most preferred. An amount of silver less than 5% by mass is not preferable because it adversely affects the conductivity of the silver-coated copper powder. On the other hand, if it exceeds 50% by mass, the cost increases due to the increase in the amount of silver used, which is not preferable.

The particle diameter of the copper powder is preferably such that the cumulative 50% particle diameter (D ₅₀ diameter) on a volume basis measured by a laser diffraction type particle size distribution device is 0.1 to 15 μm, and 0.3 to 10 μm. More preferably, it is most preferably 1 to 5 μm. If the cumulative 50% particle diameter (D ₅₀ diameter) is less than 0.1 μm, it is not preferable because it adversely affects the conductivity of the silver-coated copper powder. On the other hand, if it exceeds 15 μm, formation of fine wiring becomes difficult, which is not preferable.

  The copper powder may be produced by a wet reduction method, an electrolytic method, a gas phase method or the like, but copper is melted at a temperature higher than the melting temperature, and it is caused to collide with high pressure gas or high pressure water while dropping from the lower part of the tundish It is preferable to manufacture by a so-called atomization method (such as a gas atomization method or a water atomization method) to obtain a fine powder by In particular, copper powder having a small particle diameter can be obtained when manufactured by so-called water atomization method in which high pressure water is sprayed, and therefore, when copper powder is used for conductive paste, the conductivity is improved by the increase of contact points between particles. Can be

  Using a method of depositing silver or a silver compound on the surface of copper powder by a substitution method using a substitution reaction of copper and silver or a reduction method using a reducing agent as a method of coating copper powder with a silver layer For example, a method of depositing silver or a silver compound on the surface of copper powder while stirring a solution containing copper powder and silver or a silver compound in the solvent, or a solution containing copper powder and an organic substance in the solvent It is possible to use a method of precipitating silver or a silver compound on the surface of copper powder while mixing and stirring a solution containing silver or a silver compound and an organic matter.

  As the solvent, water, an organic solvent or a mixture thereof can be used. When using a solvent in which water and an organic solvent are mixed, it is necessary to use an organic solvent that becomes liquid at room temperature (20 to 30 ° C.), but the mixing ratio of water to the organic solvent depends on the organic solvent used It can be adjusted appropriately. As water used as a solvent, distilled water, ion-exchanged water, industrial water, etc. can be used unless there is a possibility that impurities will be mixed.

  It is preferable to use silver nitrate having high solubility in water and many organic solvents because silver ions need to be present in the solution as a raw material of the silver layer. In addition, a silver nitrate solution in which silver nitrate is dissolved in a solvent (water, an organic solvent, or a mixed solvent thereof) rather than solid silver nitrate in order to carry out a reaction (silver coating reaction) of coating copper powder with a silver layer as uniformly as possible. It is preferred to use The amount of the silver nitrate solution to be used, the concentration of silver nitrate in the silver nitrate solution and the amount of the organic solvent can be determined according to the amount of the desired silver layer.

  A chelating agent may be added to the solution in order to form a silver layer more uniformly. As a chelating agent, it is preferable to use a chelating agent having a high complex stability constant with respect to copper ions and the like so that copper ions and the like by-produced by substitution reaction of silver ions and metallic copper are not reprecipitated. . In particular, since the copper powder to be the core of the silver-coated copper powder contains copper as a main component, it is preferable to select a chelating agent in consideration of the complex stability constant with copper. Specifically, as a chelating agent, a chelating agent selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), iminodiacetic acid, diethylenetriamine, triethylenediamine and salts thereof can be used.

  A pH buffer may be added to the solution to stably and safely perform the silver coating reaction. Ammonium carbonate, ammonium hydrogencarbonate, ammonia water, sodium hydrogencarbonate etc. can be used as this pH buffer.

  During the silver coating reaction, add copper powder into the solution and stir it before adding the silver salt, and add the silver salt-containing solution while the copper powder is well dispersed in the solution. Is preferred. The reaction temperature during the silver coating reaction may be a temperature at which the reaction solution solidifies or evaporates, but is preferably set in the range of 10 to 40 ° C., more preferably 15 to 35 ° C. The reaction time may vary depending on the amount of silver or silver compound and the reaction temperature, but can be set in the range of 1 minute to 5 hours.

  In addition, the above conductive paste (a conductive paste containing a silver-coated copper powder in which the surface of the copper powder is coated with a silver layer and an epoxy resin having a naphthalene skeleton) is applied to a substrate and then cured to form a substrate surface. Form an electrode, solder an interconnector to this electrode, and cover glass via a protective sheet on the surface side (side where sunlight is incident) of the cell with interconnector having an interconnector soldered to this electrode By stacking, a solar cell module can be manufactured. As the protective sheet, it is preferable to use a polyolefin-based film such as a cycloolefin copolymer (COC) film. A polyolefin-based film is known to pass oxygen, but the above-mentioned conductive paste (a conductive paste containing silver-coated copper powder in which the surface of the copper powder is coated with a silver layer and an epoxy resin having a naphthalene skeleton) It has been found that when a polyolefin-based film is used as a protective sheet in a solar cell module using an electrode formed from the above, oxidation of the electrode is suppressed and the performance as a solar cell can be maintained.

  Hereinafter, examples of the conductive paste according to the present invention will be described in detail.

Example 1
A commercially available copper powder (Atomized copper powder SF-Cu 5 μm manufactured by Nippon Atomize Processing Co., Ltd.) manufactured by the atomization method was prepared, and the particle size distribution of this copper powder (before silver coating) was determined. The volume based cumulative 10% particle diameter (D ₁₀ ) was 2.26 μm, the cumulative 50% particle diameter (D ₅₀ ) was 5.20 μm, and the cumulative 90% particle diameter (D ₉₀ ) was 9.32 μm. In addition, the particle size distribution of copper powder is measured by a laser diffraction type particle size distribution apparatus (Microtrac particle size distribution measuring apparatus MT-3300 manufactured by Nikkiso Co., Ltd.), and a cumulative 10% particle size (D ₁₀ ) based on volume, cumulative The 50% particle size (D ₅₀ ) and the 90% cumulative particle size (D ₉₀ ) were determined.

  In addition, a silver nitrate solution containing 16.904 kg of silver in a solution of 2.6 kg of ammonium carbonate dissolved in 450 kg of pure water (solution 1), a solution of 319 kg of EDTA-4Na (43%) and 76 kg of ammonium carbonate in 284 kg of pure water A solution (solution 2) obtained by adding 92 kg of an aqueous solution was prepared.

  Next, 100 kg of the above copper powder was added to the solution 1 under a nitrogen atmosphere, and the temperature was raised to 35 ° C. while stirring. The solution 2 was added to the solution in which the copper powder was dispersed and stirred for 30 minutes, then filtered, washed with water and dried to obtain a silver-coated copper powder (silver-coated copper powder). Washing with water was performed by applying pure water to the solid content obtained by filtration until the potential of the solution after washing became 0.5 mS / m or less.

  Dissolve 5.0 g of the silver-coated copper powder thus obtained in 40 mL of a nitric acid aqueous solution diluted with pure water so that a nitric acid aqueous solution with a specific gravity of 1.38 has a volume ratio of 1: 1, and boil with a heater to After the coated copper powder is completely dissolved, to this aqueous solution, a hydrochloric acid aqueous solution with a specific gravity of 1.18 is added little by little to a hydrochloric acid aqueous solution diluted with pure water so as to have a volume ratio of 1: 1 to precipitate silver chloride, The addition of aqueous hydrochloric acid was continued until precipitation did not occur, and the Ag content was determined from the obtained silver chloride by a gravimetric method. The Ag content in the silver-coated copper powder was 10.14% by mass.

In addition, 0.1 g of this silver-coated copper powder is added to 40 mL of isopropyl alcohol and dispersed by an ultrasonic homogenizer (tip tip diameter 20 mm) for 2 minutes, and then the particle size distribution of the silver-coated copper powder is measured using a laser diffraction particle size distribution apparatus ( It measured by Nikkiso Co., Ltd. Microtrac particle size distribution measuring apparatus MT-3300). As a result, the volume-based 10% particle diameter (D ₁₀ ) of silver-coated copper powder is 2.5 μm, the 50% particle diameter (D ₅₀ ) is 5.2 μm, and the 90% particle diameter (D ₉₀ ) is 10 .1 μm.

Further, the BET specific surface area of this silver-coated copper powder was measured by the BET one-point method using a BET specific surface area measuring device (4 sorb US manufactured by Yuasa Ionics Co., Ltd.). As a result, the BET specific surface area of the silver-coated copper powder was 0.31 m ² / g.

  Further, 87.64 parts by weight of the obtained silver-coated copper powder, 6.49 parts by weight of an epoxy resin having a naphthalene skeleton shown in Chemical formula 1 (HP 4710 manufactured by Dainippon Ink and Chemicals, Inc.), and butyl carbitol as a solvent 5.52 parts by weight of acetate (manufactured by Wako Pure Chemical Industries, Ltd.), 0.25 parts by weight of imidazole (2E4MZ manufactured by Shikoku Kasei Kogyo Co., Ltd.) as a curing agent, and oleic acid (Wako Pure Chemical Industries, Ltd.) as a dispersant Made (0.10 parts by weight) and mixed (pre-kneaded) with a self-revolution type vacuum stirring defoaming apparatus (Awatori Neritaro manufactured by Shinky Co., Ltd.), and then a 3-roll (EXAKT 80S manufactured by Otto Harman) The conductive paste 1 was obtained (as a paste for a bus bar electrode) by kneading according to the above. The F value (the ratio of the silver-coated copper powder to the total amount of the silver-coated copper powder as the conductive filler, the resin, and the curing agent) of the conductive paste 1 is 92.9%. It was 40 Pa.s when the viscosity of this electroconductive paste 1 was measured at 1 rpm at 25 degreeC with the viscometer (DV-III Ultra by Brookfield, Inc., CP52 is used as a cone | corn).

  Further, 45 L of industrial ammonia water was added to 502.7 L of a silver nitrate solution of 21.4 g / L as silver ions to form an ammine complex solution of silver. The pH was adjusted by adding 8.8 L of sodium hydroxide solution with a concentration of 100 g / L to the formed silver ammine complex solution, diluted with 462 L of water, and diluted with 48 L of industrial formalin as a reducing agent. Immediately thereafter, 121 g of a 16% by weight stearic acid emulsion as stearic acid was added. The silver slurry thus obtained was filtered, washed with water and then dried to obtain 21.6 kg of silver powder. The silver powder was subjected to surface smoothing treatment with a Henschel mixer (high speed stirrer), and then classified to remove silver aggregates larger than 11 μm. Washing with water was performed by applying pure water to the solid content obtained by filtration until the potential of the solution after washing became 0.5 mS / m or less.

  88 parts by weight of silver powder thus obtained, 0.2 parts by weight of indium powder, 1.5 parts by weight of silver tellurium-coated glass powder, and ethyl cellulose (manufactured by Wako Pure Chemical Industries, Ltd.) 0.12 as a binder resin Parts by weight and 1.1 parts by weight of acrylic resin (Nisset EU-5638 from Nippon Carbide Industries Co., Ltd.), 0.5 parts by weight of oleic acid (Wako Pure Chemical Industries, Ltd.) as an additive, stearin as a thixotropic agent 0.3 parts by weight of magnesium acid (made by Wako Pure Chemical Industries, Ltd.), 3.4 parts by weight of methyl isobutyl ether (MIBE) (made by JNC) as a solvent, and butyl carbitol acetate (made by Wako Pure Chemical Industries, Ltd.) ) 3.4 parts by weight were mixed (pre-kneading with a revolution-type vacuum stirring degassing apparatus (Awatori Neritaro manufactured by Shinky Co., Ltd.)) After, by kneading by a three-roll (EXAKT80S manufactured by Otto Herman, Inc.), was obtained (as a baking type Ag paste) conductive paste 2.

  The silver telluride-coated glass powder was produced as follows. First, 3.47 g of a 32 mass% silver nitrate aqueous solution was mixed with 787 g of pure water in a 1 L beaker state, and 28 mass% ammonia water as a complexing agent was added to the silver nitrate aqueous solution containing 1.11 g of this silver. 2.5 g was added to obtain a silver ammine complex salt aqueous solution. After the solution temperature of this silver ammine complex aqueous solution is brought to 30 ° C., 10 g of tellurium-based glass powder (BLT-77 manufactured by Asahi Glass Co., Ltd.) is added, and immediately thereafter, 0.3 g of hydrazine as a reducing agent and silver colloid 10 A mixture of 3 g of pure water and 20 g of pure water is added, aged for 5 minutes, coated with a tellurium-based glass powder with a layer mainly composed of silver and tellurium, and then this silver-tellurium-coated glass powder-containing slurry is suction-filtered And wash with pure water until the potential is 0.5 mS / m or less, and the obtained cake is dried in a vacuum drier at 75 ° C. for 10 minutes, and silver tellurium-coated glass powder (silver and tellurium as main components Glass powder coated with the layer to be obtained.

  Next, two silicon wafers (100 Ω / sq, 6 inch single crystal manufactured by E & M Corporation) are prepared, and the back side of each silicon wafer is aluminum by a screen printing machine (MT-320T manufactured by Microtech Co., Ltd.) After printing the paste (Alsolar 14-7021 manufactured by Toyo Aluminum Co., Ltd.), the paste is dried at 200 ° C. for 10 minutes with a hot air dryer, and a screen printing machine (MT-C manufactured by Microtech Co., Ltd.) After printing the above-mentioned conductive paste 2 in the shape of 100 finger electrodes with a width of 40 μm according to 320T), the conductive paste 2 is dried at 200 ° C. for 10 minutes with a hot-air drier and a high-speed firing IR furnace (high speed manufactured by NGK Insulators Ltd. Firing test with a peak temperature of 820 ° C. as in-out 21 seconds of firing test 4 chamber furnace) Formed. After that, each conductive paste 1 (conductive paste 1 obtained from silver-coated copper powder) is 1.3 mm wide on the surface of each silicon wafer by a screen printing machine (MT-320T manufactured by Microtech Co., Ltd.) After printing in the shape of three bus bar electrodes of the above, it was heated at 150 ° C. for 10 minutes with a hot air dryer, then dried by heating at 200 ° C. for 30 minutes for drying and curing to form bus bar electrodes. It was 3.15 ohm when resistance (initial stage resistance value) of a bus bar electrode formed in this way was measured. Also, apply a soldering iron at 380 ° C to the bus bar electrodes and move them at a speed of 10 mm / sec so that the same level of heat as soldering heat is applied on the bus bar electrodes of one silicon wafer, and after this heating The resistance of the bus bar electrode was measured to be 3.42 Ω, and the resistance change rate to the initial resistance value was 109%.

Next, the bus bar electrode and the tab wire of the other silicon wafer were soldered at 380 ° C. by SnPb eutectic solder (melting point 183 ° C.) to produce a solar cell. A battery characteristic test was conducted by irradiating this solar cell with pseudo-sunlight of 100 mW / cm ² of light irradiation energy with a xenon lamp of a solar simulator (WACOM, Inc.). As a result, when the output terminal of the solar cell is shorted, the current (short circuit current) Isc flowing between the two terminals is 9.23 A, and the voltage (open circuit voltage) Voc between the two terminals when the output terminal of the solar cell is opened. Is the current density Jsc (short circuit current Isc per 1 cm ² ) is 0.038 A / cm ² , and the maximum output Pmax (= Imax · Vmax) divided by the product of the open circuit voltage Voc and the current density Jsc (curve Factor) FF (= Pmax / Voc · Isc) is 73.64, power generation efficiency Eff (maximum output Pmax divided by the amount of irradiation light (W per 1 cm ² ) multiplied by 100) is 17.65 %, Series resistance Rs was 0.0089 Ω / □.

Example 2
A solar cell was prepared in the same manner as in Example 1, except that imidazole (2PHZ-PW manufactured by Shikoku Kasei Kogyo Co., Ltd.) was used in place of imidazole (2E4MZ manufactured by Shikoku Kasei Kogyo Co., Ltd.) as a curing agent. Made. The viscosity of the conductive paste 1 obtained in this example was measured by the same method as in Example 1. As a result, it was in the range of 40 ± 5 Pa · s.

  When the resistance of the bus bar electrode before and after soldering the bus bar electrode of this solar cell and the tab wire was measured, the resistance value (initial resistance value) before soldering of the bus bar electrode is 7.56 Ω, the resistance value after soldering The resistance change rate with respect to the initial resistance value was 87%.

Moreover, when the cell characteristic test of the solar cell was conducted by the same method as in Example 1, the short circuit current Isc is 9.23 A, the open circuit voltage Voc is 0.630 V, the current density Jsc is 0.038 A / cm ² , and the curve The factor FF was 72.98, the power generation efficiency Eff was 17.45%, and the series resistance Rs was 0.0091 Ω / □.

[Example 3]
Silver-coated copper is used as a curing agent in conductive paste 1 instead of imidazole (2E4MZ manufactured by Shikoku Kasei Kogyo Co., Ltd.) and using a boron trifluoride amine hardener (BF 3 NH 2 Et manufactured by Wako Pure Chemical Industries, Ltd.) The same as Example 1, except that the amounts of powder, epoxy resin having naphthalene skeleton, solvent and curing agent were 85.52 parts by weight, 8.44 parts by weight, 5.62 parts by weight and 0.32 parts by weight, respectively. A solar cell was produced by the method of The F value of the conductive paste 1 obtained in this example was 90.7%. The viscosity of the conductive paste 1 obtained in this example was measured by the same method as in Example 1 and found to be in the range of 40 ± 5 Pa · s.

  When the resistance of the bus bar electrode before and after soldering the bus bar electrode of this solar cell and the tab wire was measured, the resistance value (initial resistance value) before soldering of the bus bar electrode is 6.58 Ω, the resistance value after soldering Is 7.71 Ω, and the rate of change in resistance with respect to the initial resistance value is 117%.

Moreover, when the cell characteristic test of the solar cell was conducted by the same method as in Example 1, the short circuit current Isc is 9.20 A, the open circuit voltage Voc is 0.628 V, the current density Jsc is 0.038 A / cm ² , a curve The factor FF was 71.63, the power generation efficiency Eff was 17.02%, and the series resistance Rs was 0.0102 Ω / □.

Example 4
An epoxy resin having a naphthalene skeleton shown in Chemical formula 1 (HP 9500 manufactured by Dainippon Ink Chemical Industry Co., Ltd.) in place of the epoxy resin having a naphthalene skeleton in the conductive paste 1 (HP 4710 manufactured by Dainippon Ink Chemical Industry Co., Ltd.) A solar cell was produced in the same manner as in Example 1 except that the above was used. The F value of the conductive paste 1 obtained in this example was 90.9%. The viscosity of the conductive paste 1 obtained in this example was measured by the same method as in Example 1 and found to be in the range of 40 ± 5 Pa · s.

  When the resistance of the bus bar electrode before and after soldering the bus bar electrode of this solar cell and the tab wire was measured, the resistance value (initial resistance value) before soldering of the bus bar electrode is 3.56 Ω, the resistance value after soldering Is 5.83 Ω, and the rate of change in resistance with respect to the initial resistance value is 164%.

Moreover, when the cell characteristic test of the solar cell was conducted by the same method as in Example 1, the short circuit current Isc is 8.85 A, the open circuit voltage Voc is 0.627 V, the current density Jsc is 0.036 A / cm ² , a curve The factor FF was 70.47, the power generation efficiency Eff was 16.10%, and the series resistance Rs was 0.0114 Ω / □.

Comparative Example 1
A bisphenol F-type epoxy resin (EP 4901E manufactured by ADEKA Co., Ltd.) shown in Chemical formula 2 is used instead of the epoxy resin having a naphthalene skeleton in the conductive paste 1 and imidazole (2E4MZ manufactured by Shikoku Kasei Kogyo Co., Ltd.) as a curing agent A solar cell was manufactured in the same manner as in Example 3, except that the amount of the solvent was changed to 1.94 parts by weight so that the viscosity of the conductive paste 1 was in the range of 40 ± 5 Pa · s. did. The F value of this conductive paste 1 is 90.7%.

  When the resistance of the bus bar electrode before and after soldering the bus bar electrode of this solar cell and the tab wire was measured, the resistance value (initial resistance value) before soldering of the bus bar electrode is 4.05 Ω, the resistance value after soldering Is 18.70Ω, and the resistance change rate to the initial resistance value is 462%.

Moreover, when the cell characteristic test of the solar cell was conducted by the same method as in Example 1, the short circuit current Isc was 6.71 A, the open circuit voltage Voc was 0.634 V, the current density Jsc was 0.028 A / cm ² , and the curve The factor FF was 49.96, the power generation efficiency Eff was 8.74%, and the series resistance Rs was 0.0162 Ω / □.

Comparative Example 2
In place of the epoxy resin having a naphthalene skeleton, a bisphenol F-type epoxy resin (EP 4901E manufactured by ADEKA Co., Ltd.) shown in Chemical formula 2 is used so that the viscosity of the conductive paste 1 is in the range of 40 ± 5 Pa · s. A solar cell was produced in the same manner as in Example 1 except that the amount of the solvent was changed to 1.99 parts by weight.

  When the resistance of the bus bar electrode before and after soldering the bus bar electrode of this solar cell and the tab wire was measured, the resistance value (initial resistance value) before soldering of the bus bar electrode is 2.37 Ω, the resistance value after soldering Is 7.73 Ω, and the rate of change in resistance with respect to the initial resistance value is 326%.

Moreover, when the cell characteristic test of the solar cell was conducted by the same method as in Example 1, the short circuit current Isc is 7.93 A, the open circuit voltage Voc is 0.632 V, the current density Jsc is 0.033 A / cm ² , a curve The factor FF was 45.47, the power generation efficiency Eff was 9.39%, and the series resistance Rs was 0.0228 Ω / □.

Comparative Example 3
In place of the epoxy resin having a naphthalene skeleton, a bisphenol F-type epoxy resin (EP 4901E manufactured by ADEKA Co., Ltd.) shown in Chemical formula 2 is used so that the viscosity of the conductive paste 1 is in the range of 40 ± 5 Pa · s. A solar cell was produced in the same manner as in Example 3 except that the amount of the solvent was changed to 1.94 parts by weight.

  When the resistance of the bus bar electrode before and after soldering the bus bar electrode of this solar cell and the tab wire was measured, the resistance value (initial resistance value) before soldering of the bus bar electrode is 5.95 Ω, the resistance value after soldering Is 12.63 Ω, and the resistance change rate to the initial resistance value is 212%.

Moreover, when the cell characteristic test of the solar cell was conducted by the same method as in Example 1, the short circuit current Isc is 8.65 A, the open circuit voltage Voc is 0.630 V, the current density Jsc is 0.036 A / cm ² , and the curve The factor FF was 64.69, the power generation efficiency Eff was 14.51%, and the series resistance Rs was 0.0165 Ω / □.

Comparative Example 4
In place of the epoxy resin having a naphthalene skeleton, bisphenol A type epoxy resin (JER 828 manufactured by Mitsubishi Chemical Corporation) shown in Chemical formula 3 is used, and the viscosity of the conductive paste 1 is in the range of 40 ± 5 Pa · s A solar cell was produced in the same manner as in Example 1 except that the amount of the solvent was changed to 1.99 parts by weight.

When the resistance of the bus bar electrode before and after soldering the bus bar electrode of this solar cell and the tab wire was measured, the resistance value (initial resistance value) before soldering of the bus bar electrode is 3.50 Ω, the resistance value after soldering Is 34.93 Ω, and the rate of change in resistance with respect to the initial resistance value is 998%.
Moreover, when the cell characteristic test of the solar cell was conducted by the same method as in Example 1, the short circuit current Isc is 7.78 A, the open circuit voltage Voc is 0.635 V, the current density Jsc is 0.032 A / cm ² , a curve The factor FF was 54.49, the power generation efficiency Eff was 11.07%, and the series resistance Rs was 0.0181 Ω / □.

Comparative Example 5
Using a biphenyl skeleton epoxy resin (NC-3000-H manufactured by Nippon Kayaku Co., Ltd.) shown in Chemical formula 4 instead of the epoxy resin having a naphthalene skeleton, the viscosity of the conductive paste 1 is 40 ± 5 Pa · s A solar cell was produced in the same manner as in Example 1 except that the amount of the solvent was changed to 5.32 parts by weight so as to be within the range.

  When the resistance of the bus bar electrode before and after soldering the bus bar electrode of this solar cell and the tab wire was measured, the resistance value (initial resistance value) before soldering of the bus bar electrode is 6.08 Ω, the resistance value after soldering Is 23.53 Ω, and the rate of change in resistance relative to the initial resistance value is 387%.

Moreover, when the cell characteristic test of the solar cell was conducted by the same method as in Example 1, the short circuit current Isc is 5.67 A, the open circuit voltage Voc is 0.635 V, the current density Jsc is 0.023 A / cm ² , a curve The factor FF was 54.52, the power generation efficiency Eff was 8.07%, and the series resistance Rs was 0.0127 Ω / □.

Comparative Example 6
Instead of the epoxy resin having a naphthalene skeleton, a cyclopentadiene skeleton epoxy resin (XD-1000 manufactured by Nippon Kayaku Co., Ltd.) shown in Chemical formula 5 is used, and the viscosity of the conductive paste 1 is in the range of 40 ± 5 Pa · s. A solar cell was produced in the same manner as in Example 1 except that the amount of the solvent was changed to 5.32 parts by weight to be inside.

  When the resistance of the bus bar electrode before and after soldering the bus bar electrode of this solar cell and the tab wire was measured, the resistance value (initial resistance value) before soldering of the bus bar electrode is 4.73 Ω, the resistance value after soldering Is 21.67 Ω, and the rate of change in resistance with respect to the initial resistance value is 458%.

Moreover, when the cell characteristic test of the solar cell was conducted by the same method as in Example 1, the short circuit current Isc is 4.66 A, the open circuit voltage Voc is 0.632 V, the current density Jsc is 0.019 A / cm ² , and the curve The factor FF was 55.01, the power generation efficiency Eff was 6.67%, and the series resistance Rs was 0.0182 Ω / □.

  The results of these examples and comparative examples are shown in Tables 1 to 3.

  As can be seen from Tables 1 to 3, when the conductive pastes of Examples 1 to 3 are used to form bus bar electrodes of a solar cell, the bus bar electrodes are compared with the case where the conductive pastes of Comparative Examples 1 to 6 are used. Even if it connects with a tab wire by soldering, it can prevent that resistance of a bus-bar electrode becomes high and can prevent the fall of the conversion efficiency of a solar cell.

[Example 5]
79.0 parts by weight of the silver-coated copper powder of Example 1, 8.8 parts by weight of silver powder with an average primary particle diameter of 1 μm (Ag-2-IC manufactured by DOWA Electronics Co., Ltd.), and a naphthalene skeleton shown in Chemical Formula 1 6.6 parts by weight of an epoxy resin (HP 4710 manufactured by Dainippon Ink and Chemicals, Inc.), 5.3 parts by weight of butyl carbitol acetate (manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent, and imidazole (Shikoku Kasei) as a curing agent 0.3 parts by weight of 2E4MZ manufactured by Kogyo Co., Ltd. and 0.1 parts by weight of oleic acid (manufactured by Wako Pure Chemical Industries, Ltd.) as a dispersant After mixing (pre-kneading) with Awatori Neritaro, by kneading with a 3-roll (EXAKT 80S manufactured by Otto Harman), the surface of the silicon wafer (described later) Was obtained busbar as electrode paste) The conductive paste A. The conductive paste A contains 87.8% by mass in total of silver-coated copper powder and silver powder as a conductive filler.

  In addition, 88 parts by weight of silver powder (AG-4-8F manufactured by Dowa Electronics Co., Ltd.) having an average primary particle diameter of 1.9 μm, 2.4 parts by weight of ethyl cellulose resin (manufactured by Wako Pure Chemical Industries, Ltd.), and Texanol (JMC) 9.5 parts by weight of a mixed solvent of 1:11 and Butyl Carbitol Estate (manufactured by Wako Pure Chemical Industries, Ltd.) 1: 1 and 1 part by weight of glass frit (GA-12 manufactured by Nippon Electric Glass Co., Ltd.) And 0.5 parts by weight of oleic acid (manufactured by Wako Pure Chemical Industries, Ltd.) as a dispersant using a self-revolution type vacuum stirring and degassing apparatus (Awatori Neritaro manufactured by Shinky Co., Ltd.) (pre-kneading) Then, by kneading with a three-roll (EXAKT 80S manufactured by Otto Harman), the conductive paste (as a paste for the bus bar electrode on the back surface of the silicon wafer described later) It was obtained B.

  Furthermore, 87.9 parts by weight of silver powder (AG-2.5-8F manufactured by Dowa Electronics Co., Ltd.) having an average primary particle diameter of 1.3 μm and 0.1 parts by weight of ethyl cellulose resin (manufactured by Wako Pure Chemical Industries, Ltd.) 1 part by weight of acrylic resin (EU-5638 manufactured by Nippon Carbide Industries Co., Ltd.), methyl isobutyl ether (MIBE) (manufactured by JNC Co., Ltd.) and butyl carbitol estate (manufactured by Wako Pure Chemical Industries, Ltd.) : 6.1 parts by weight of solvent mixed in 1, 1.5 parts by weight of glass frit (Te-Bi-Li system), 0.3 parts by weight of magnesium stearate, oleic acid as a dispersant (Wako Pure Chemical Industries, Ltd. After mixing (pre-kneading) 0.5 parts by weight of the product with a revolution-revolution-type vacuum stirring degassing apparatus (Awatori Neritaro manufactured by Shinky Co., Ltd.) By kneading by EXAKT80S) manufactured by Herman Inc., was obtained (as a finger electrode paste) conductive paste C.

  Next, a silicon wafer (100 Ω / sq, 6 inch single crystal manufactured by E & M Co., Ltd.) is prepared, and the above conductive paste is applied to the back surface of this silicon wafer by a screen printing machine (MT-320T manufactured by Microtec Inc.) B was printed in a shape of three bus bar electrodes 1.3 mm wide, and then dried by heating at 200 ° C. for 10 minutes using a hot air dryer. Thereafter, an aluminum paste (Alsolar 14-7021 manufactured by Toyo Aluminum Co., Ltd.) is printed on the back side of the silicon wafer other than the printed part of conductive paste B, and then heated at 200 ° C. for 10 minutes with a hot air dryer. It was dried. Thereafter, the conductive paste C is printed in the shape of 100 finger electrodes of 50 μm in width by a screen printer (MT-320T manufactured by Microtech Co., Ltd.) on the surface of a silicon wafer, and then 200 by a hot air dryer. Heated at 10 ° C for 10 minutes, dried, fired at a peak temperature of 820 ° C for 21 seconds in-out of a high-speed firing IR furnace (High-speed firing test 4 chamber furnace made by NGK Insulators Ltd.) Electrodes and surface finger electrodes were formed. Thereafter, the conductive paste A is printed on the surface of a silicon wafer with a screen printing machine (MT-320T manufactured by Microtech Co., Ltd.) in the shape of three bus bar electrodes of 1.3 mm in width, and then a hot air dryer C. for 10 minutes, and then dried by heating at 200.degree. C. for 40 minutes to form bus bar electrodes on the surface of the silicon wafer.

  After flux is applied to the bus bar electrodes on the front and back of the solar cell thus produced, the solar cell is placed on a hot plate at 50 ° C., and 0.2 mm × 1.5 mm × 176 mm on it Place the interconnect material (SSA-SPS manufactured by Hitachi Metals, Ltd.), and while touching the soldering iron heated to 380 ° C, trace it from above at a speed of about 10 mm / s and solder on both sides of the solar cell To obtain a cell with an interconnector. Then, from the surface side, cover glass, EVA sheet (ever film), cycloolefin copolymer (COC) film (TOPAS (registered trademark) manufactured by Topas Advanced Polymers GmbH, 75 μm thick), EVA sheet, cell with interconnector as described above , EVA sheet and back sheet were laminated in this order, and this laminated body was pressed by a vacuum laminator to obtain a solar cell module. The solar cell module is irradiated with pseudo-sunlight by a solar simulator, and the maximum output Pmax, the open circuit voltage Voc, the short circuit current Isc, and the curve factor FF are determined. The maximum output Pmax is 4.7 W, and the open circuit voltage Voc is 0. 0. The short circuit current Isc was 10.0 A, and the fill factor FF was 71%.

  Moreover, as a PID test of this solar cell module, using a PID test apparatus (manufactured by ESPEC Corp.), the solar cell module is placed in a chamber at a temperature of 85 ° C. and a humidity of 85%, and a voltage of −000 V is applied for 1000 hours Then, an accelerated deterioration test was conducted. Thereafter, the solar cell module taken out of the PID test apparatus is irradiated with pseudo-sunlight by a solar simulator, and the maximum output Pmax, the open circuit voltage Voc, the short circuit current Isc, and the curve factor FF are determined. The open circuit voltage Voc was 0.6 V, the short circuit current Isc was 10.0 A, and the curve factor FF was 71%. It was confirmed that the solar cell characteristics were not degraded at all compared with those before the PID test.

Comparative Example 7
Conductivity (as a bus bar electrode paste) in the same manner as in Example 5 except that a bisphenol F-type epoxy resin (EP4901E manufactured by ADEKA Co., Ltd.) shown in Chemical formula 2 is used instead of the epoxy resin having a naphthalene skeleton. Sex paste A was obtained. An attempt was made to manufacture a solar cell module by the same method as in Example 5 except that this conductive paste A was used, but the interconnector and the bus bar did not adhere, and a solar cell module could not be manufactured. .

[Example 6]
Cover glass, EVA sheet, COC film (TOPAS (registered trademark) made by Topas Advanced Polymers GmbH, 75 μm thick), EPDM rubber, cell with interconnector, EPDM rubber (transparent, 300 μm thick) when producing a laminate A solar cell module was obtained by the same method as Example 5, except that the back sheets were laminated in order. The solar cell module is irradiated with pseudo-sunlight by a solar simulator, and the maximum output Pmax, the open circuit voltage Voc, the short circuit current Isc, and the curve factor FF are determined. The maximum output Pmax is 4.7 W, and the open circuit voltage Voc is 0. 0. The short circuit current Isc was 11.0 A, and the fill factor FF was 71%. Moreover, after performing a PID test similar to Example 5 to this solar cell module, simulated solar light is irradiated to a solar cell module by a solar simulator, and maximum output Pmax, open circuit voltage Voc, short circuit current Isc, curve factor FF The maximum output Pmax is 4.9 W, the open circuit voltage Voc is 0.6 V, the short circuit current Isc is 10.0 A, the curve factor FF is 70%, and the maximum output is rising. It was confirmed that the solar cell characteristics did not deteriorate at all compared to before.

Comparative Example 8
A solar cell module was obtained by the same method as in Example 5 except that, in producing the laminate, from the surface side, a cover glass, an EVA sheet, a cell with an interconnector, an EVA sheet, and a back sheet were laminated in this order. . The solar cell module is irradiated with pseudo-sunlight by a solar simulator, and the maximum output Pmax, the open circuit voltage Voc, the short circuit current Isc, and the curve factor FF are determined. The maximum output Pmax is 4.7 W, and the open circuit voltage Voc is 0. 0. The short circuit current Isc was 11.0 A, and the fill factor FF was 71%. In addition, when the same PID test as in Example 5 was carried out on this solar cell module, delamination occurred (delamination) between the cell with the interconnector and the EVA sheet after 265 hours, and the maximum output after 1000 hours Etc could not be measured. When this comparative example and Examples 5 and 6 are compared, when producing a solar cell module using the conductive paste containing silver coated copper powder of Example 1, and the epoxy resin which has naphthalene frame, It is understood that it is better to laminate a COC film between the EVA sheet on the cover glass side and the cell with interconnector.

  In addition, a conductive paste containing a bus bar electrode (silver coated copper powder of Example 1 and an epoxy resin having a naphthalene skeleton formed on the surface side (cover glass side) of the cell with interconnector of the solar cell module after the PID test For the cross section of the bus bar electrode formed by A), using a Auger electron spectrometer (FE-AES) (JAMP-9500F manufactured by JEOL Ltd.), the diameter of the analysis area is 1 Qualitative analysis of the central part of the cross section of the copper particle was carried out, and oxygen was detected. In addition, the solar cell module produced in Example 5 (the same solar cell as Comparative Example 8 except that the EVA sheet between the cover glass and the cell with the interconnector was replaced with an EVA sheet, a cycloolefin copolymer (COC) film, and an EVA sheet) The same qualitative analysis was conducted for the battery module as well, and no oxygen was detected. From these results, it can be seen that the solar cell module produced in Example 5 has no oxygen detected even after the PID test, and that the oxidation resistance is enhanced by combining the epoxy resin having a naphthalene skeleton with the COC film. . The SEM image of the cross section of the bus-bar electrode formed in the surface side (cover glass side) of the cell with an interconnector of the solar cell module produced in this comparative example and Example 5 is each shown in FIG. 1 and FIG.

  In addition, mapping analysis of the cross section of the bus bar electrode formed on the surface side (cover glass side) of the interconnector-equipped cell of the solar cell module after the PID test using the above-mentioned Auger electron spectroscopy analyzer (FE-AES) As a result, oxygen was observed almost all over the copper particles, and the presence of silver coated with copper was hardly confirmed. Moreover, when the same mapping analysis was performed also about the solar cell module produced in Example 5, silver was detected on the surface of the copper particles, and it was present in the state of silver-coated copper powder even after the PID test. Was confirmed. From these results, it is understood that the solar cell module produced in Example 5 can maintain the state of the silver-coated copper powder even after the PID test by combining the epoxy resin having a naphthalene skeleton and the COC film. In addition, Ag map image and Cu map image by the mapping analysis of the cross section of the bus-bar electrode formed in the surface side (cover glass side) of the cell with an interconnector of the solar cell module produced in Example 5 are each shown in FIG. Shown in.

[Example 7]
89 parts by weight of silver powder having an average primary particle diameter of 0.8 μm (AG-2-1C manufactured by Dowa Electronics Corporation), 4 parts by weight of an epoxy resin, 0.2 parts by weight of a curing agent, and 2 parts by weight of a urethane resin 0.4 parts by weight of butyl carbitol acetate (manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent and 0.1 parts by weight of oleic acid as a dispersing agent using a revolution / revolution type vacuum stirring deaerator (manufactured by Shinky Co., Ltd.) After mixing (pre-kneading) with Awatori Neritaro), conductive paste D was obtained by kneading with a 3-roll (EXAKT 80S manufactured by Otto Harman).

  Next, a heterojunction silicon wafer is prepared, and the conductive paste D is printed on the entire back surface of the silicon wafer by a screen printing machine (MT-320T manufactured by Microtech Co., Ltd.), and then a hot air drier And dried at 150 ° C. for 10 minutes, and then cured by heating at 200 ° C. for 30 minutes. Thereafter, the conductive paste D is printed on the surface of a silicon wafer with a screen printer (MT-320T manufactured by Microtech Co., Ltd.) in the shape of 100 finger electrodes of 50 μm width, and then 150 by a hot air dryer. After drying by heating at 10 ° C. for 10 minutes, it was cured by heating at 200 ° C. for 30 minutes. Thereafter, a conductive paste A similar to that of Example 5 is formed on the surface of a silicon wafer by a screen printing machine (MT-320T manufactured by Microtech Co., Ltd.) in the shape of 100 finger electrodes and 3 bus bars of 1.3 mm in width. After printing the electrode shape into a combined shape, it was dried by heating at 150 ° C. for 10 minutes with a hot air dryer and then dried by heating at 200 ° C. for 30 minutes.

  A solar cell module was obtained by the same method as in Example 5 using the solar cell manufactured in this manner. The solar cell module is irradiated with pseudo sunlight by a solar simulator, and the maximum output Pmax, the open circuit voltage Voc, the short circuit current Isc, and the curvilinear factor FF are determined. The maximum output Pmax is 5.3 W, and the open circuit voltage Voc is 0. 0. The short circuit current Isc was 11.0 A, and the fill factor FF was 71%. Moreover, after performing a PID test similar to Example 5 to this solar cell module, simulated solar light is irradiated to a solar cell module by a solar simulator, and maximum output Pmax, open circuit voltage Voc, short circuit current Isc, curve factor FF The maximum output Pmax is 4.7 W, the open circuit voltage Voc is 0.7 V, the short circuit current Isc is 10.0 A, the curve factor FF is 67%, the output deterioration rate is only 11%, and the long-term use is Were confirmed to be able to withstand

  The conductive paste according to the present invention can be used for producing a conductor pattern of a circuit board, an electrode of a substrate such as a solar cell or an electronic component such as a circuit.

Claims (10)

A conductive paste comprising a silver-coated copper powder in which the surface of a copper powder is coated with a silver layer, and an epoxy resin having a naphthalene skeleton. The conductive paste according to claim 1, wherein the conductive paste contains a solvent. The conductive paste according to claim 1, wherein the conductive paste contains a curing agent. The conductive paste according to claim 3, wherein the curing agent is at least one of imidazole and a boron trifluoride amine-based curing agent. The conductive paste according to any one of claims 1 to 4, wherein an amount of silver to the silver-coated copper powder is 5% by mass or more. The volume-based cumulative 50% particle diameter (D ₅₀ diameter) measured by the laser diffraction type particle size distribution device of the copper powder is 0.1 to 15 μm, The method according to any one of claims 1 to 5, Conductive paste. The conductive paste according to any one of claims 1 to 6, wherein the amount of the silver-coated copper powder in the conductive paste is 50 to 90% by mass. A method of manufacturing a solar cell electrode, comprising forming the electrode on the surface of the substrate by applying the conductive paste according to any one of claims 1 to 7 to the substrate and then curing the conductive paste. The conductive paste according to any one of claims 1 to 7 is applied to a substrate and then cured to form an electrode on the surface of the substrate, to solder the interconnector to the electrode, and to have the interconnector soldered to the electrode A method of manufacturing a solar cell module, comprising: laminating a cover glass on a cell with a connector via a polyolefin-based film. An inter-connector-equipped cell having an interconnector soldered to an electrode containing a silver-coated copper powder coated with a silver layer and a naphthalene skeleton on the surface of a copper powder, and a polyolefin-based film between a cover glass The solar cell module characterized by being laminated.

Images