JP2014086243A - Paste for forming an electroconductive film, electroconductive film, method for manufacturing an electroconductive film, and article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paste for forming an electroconductive film capable of reducing the volume resistivity of the electroconductive film, an electroconductive film having an improved electroconductivity, a method for manufacturing the electroconductive film, and an article possessing the electroconductive film.SOLUTION: The paste used is a paste including 15-40 parts.mass of a resin binder with respect to 100 parts.mass of a copper powder wherein, on an occasion where the paste is heated and cured at 100 to 300°C, the density of the copper powder and the shrinkage rate of paste components excluding the solvent volume content are respectively 4.0-6.5 g/cmand 10-30 vol.%.

Description

  The present invention relates to a conductive film-forming paste, a conductive film produced using the paste, a method for producing the conductive film, and an article having the conductive film.

As a method for manufacturing an article having a conductive film such as an electric wiring film or an electrode film having a desired pattern, there is a conventional method in which a metal paste containing metal particles is applied on a substrate in a desired wiring pattern and fired. Are known. For example, silver paste is widely used for manufacturing printed circuit boards. However, a conductive film formed by baking a silver paste has a problem that ion migration is likely to occur. Since ion migration causes problems such as a short circuit, in consideration of the reliability of electronic equipment, it has been studied to use a copper paste that is less susceptible to ion migration than silver paste.
For example, a conductive paste (Patent Document 1) containing copper powder and a resol type phenol resin as main components and further containing an alicyclic secondary amine or the like, or a conductive copper paste containing copper powder, a thermosetting resin and sepiolite A composition (Patent Document 2) has been proposed.
Furthermore, conductive paste (Patent Document 3) using conductive powder made of copper or copper alloy treated with an aqueous solution of a predetermined acid, reducing agent and fatty acid, dendritic copper powder having a predetermined particle size distribution, thermosetting A conductive copper paste (Patent Document 4) containing a resin, an organic carboxylic acid and a chelating agent has been proposed.

JP-A-5-128911 Japanese Patent Laid-Open No. 10-283842 JP 2007-184143 A JP 2008-130301 A

As described above, various studies have been made to improve the conductivity of the paste, but no study has been made in terms of copper powder filling properties and paste shrinkage when processed into a conductive film. The conductivity of the obtained conductive film was insufficient.
Therefore, in the present invention, from the viewpoint of copper powder filling properties and paste shrinkage, the physical properties of the copper powder used in the raw material, the composition of the paste, the processing conditions of the conductive film, etc. are studied, and the copper powder filling properties are improved. An object of the present invention is to provide a conductive film forming paste capable of reducing the volume resistivity of the conductive film and a conductive film with improved conductivity.

The present invention for solving the above problems has the following aspects.
(1) A paste containing 15 to 40 parts by mass of a resin binder with respect to 100 parts by mass of copper powder, and the density of the copper powder after heat treatment of the paste at 100 to 300 ° C. is 4.0 to 6. A conductive film forming paste having a shrinkage rate of 10 to 30% by volume at 5 g / cm ³ and excluding the solvent volume of the paste.
(2) The conductive film forming paste according to (1), wherein the resin component contained in the paste is 6 to 28 parts by mass with respect to 100 parts by mass of the copper powder.
(3) The conductive film forming paste according to (1) or (2), wherein the copper powder has an average aspect ratio of 2.5 to 6.
(4) The copper powder having a 10% particle size of 2.0 to 4.0 μm, a 50% particle size of 4.0 to 8.0 μm, and a 90% particle size of 7.0 to 14.0 μm (1) The paste for electrically conductive film formation as described in any one of-(3).
(5) A conductive film containing copper powder and a resin binder, wherein the density of the copper powder contained in the conductive film is 4.0 to 6.5 g / cm ³ and the paste containing the copper powder and the resin binder is heat treated. Then, in the step of forming the conductive film, the conductive film has a shrinkage rate of 10 to 30% by volume of the component excluding the solvent volume of the paste.
(6) The electrically conductive film as described in said (5) whose thickness of an electrically conductive film is 10-50 micrometers.
(7) The conductive film according to (5) or (6), wherein the volume resistivity is 50 μΩ · cm or less.
(8) An article in which the conductive film according to any one of (5) to (7) is formed on a substrate.
(9) A method for producing a conductive film obtained by heat-treating a paste obtained by mixing 15 to 40 parts by mass of a resin binder with respect to 100 parts by mass of copper powder, the density of the copper powder of the conductive film Of 4.0 to 6.5 g / cm ³ , and the shrinkage ratio of components excluding the solvent volume of the paste before and after the heat treatment is 10 to 30% by volume.

ADVANTAGE OF THE INVENTION According to this invention, the filling property of the copper powder in a conductive film is high, the conductive film formation paste which can reduce the volume resistivity of a conductive film, the conductive film which improved electroconductivity, and the electroconductivity which improved electroconductivity Articles having membranes can be provided.
Whether the conductive film-forming paste of the present invention and the conductive film have the effects described above is not necessarily clear, but is estimated as follows. The volume resistivity of the conductive film is affected by numerous factors such as the particle size distribution and shape of the copper powder used, the type of resin binder contained in the paste, the composition of the paste, and the conductive film formation conditions. Therefore, it is estimated that a conductive film having a very low volume resistivity and an extremely high conductivity can be produced by optimizing these factors based on the viewpoint of the shrinkage rate of the paste. In other words, by using the shrinkage rate of the paste as an index, many of these factors are controlled, adjusted to the optimum conditions, and the hardening shrinkage force of the binder is further promoted, so that the particles of copper powder in the paste are highly advanced. The contact area between the copper powder particles in the conductive film can be increased, and the density of the copper powder can be sufficiently increased. As a result, a conductive film having a low volume resistivity and a very high conductivity can be obtained. Presumed.

<Paste for conductive film formation>
The conductive film forming paste of the present invention is a composition containing 15 to 40 parts by mass of a resin binder with respect to 100 parts by mass of copper powder. Especially, 18-30 mass parts is preferable with respect to 100 mass parts of copper powder, and, as for the resin binder contained in this paste, 20-25 mass parts is more preferable. If the amount of the resin binder is 15 parts by mass or more, the fluidity of the paste will be good. If the amount of the resin binder is 40 parts by mass or less, when processed into a conductive film, contact between the copper powder particles is not hindered by the thermal decomposition product of the resin binder generated by heating during processing, The contact area between the copper powder particles increases, and a conductive film having high conductivity is obtained.

The copper powder contained in the conductive film forming paste of the present invention is a copper powder having a density of 4.0 to 6.5 g / cm ³ when the paste is heat-treated. the density of the copper powder contained, inter alia preferably 4.5~6.5g / cm ^3, more preferably 5.0~6.5g / cm ^3.
The density of this copper powder is measured as follows. First, a conductive film forming paste is applied on a glass substrate so as to form a line pattern, and then heat-treated at 150 ° C. for 30 minutes to produce a conductive film. Specifically, as shown in the following formula 1, the mass of the prepared copper powder is divided into the value “W / (B + W)” obtained by dividing the mass B of the prepared resin binder by the total of the mass B of the resin binder and W. It is obtained by dividing the value obtained by multiplying the mass P by the volume V of the conductive film.
Copper powder density = P × (W / (B + W)) / V (Formula 1)
W: Mass of prepared copper powder, B: Mass of prepared resin binder, P: Mass of coated paste, V: Volume of conductive film

In the heat-treated conductive film-forming paste of the present invention, the shrinkage ratio of the components excluding the solvent volume is 10 to 30% by volume, preferably 12 to 30% by volume, more preferably 15 to 30% by volume. .
The shrinkage rate defined in the present invention is the shrinkage rate of components excluding the solvent volume of the paste before and after heat treatment (in this specification, sometimes referred to as volume shrinkage rate or shrinkage rate), and the shrinkage rate is It is measured as follows. Specifically, as expressed by Equation 2 below, a value “V / (Vp) obtained by dividing the volume V of the conductive film by“ Vp−Vs ”obtained by subtracting the solvent volume Vs contained in the paste from the volume Vp of the paste. -Vs) ". Next, it is obtained by subtracting “V / (Vp−Vs)” from 1 and then multiplying by 100.
Shrinkage rate = (1− (V / (Vp−Vs))) × 100 (Formula 2)
V: Volume of conductive film, Vp: Volume of paste, Vs: Solvent volume contained in paste

In the copper powder contained in the paste of the present invention, the 10% particle size is preferably 2.0 to 4.0 μm, more preferably 2.0 to 3.5 μm, and particularly preferably 2.0 to 3.0 μm. The 50% particle size of the copper powder is preferably 4.0 to 8.0 μm, more preferably 4.0 to 7.0 μm, and particularly preferably 4.0 to 6.0 μm. Further, the 90% particle size of the copper powder is preferably 7.0 to 14.0 μm, more preferably 7.0 to 12.0 μm, and particularly preferably 7.0 to 10.0 μm. When the particle size of the copper powder is small, the filling property of the copper powder in the conductive film after being processed into a conductive film is improved, the contact area between the copper powder particles is increased, and an improvement in conductivity can be expected.
In the present invention, the 10% particle size, 50% particle size, and 90% particle size of the copper powder are prepared by dispersing 0.2 g of copper powder in a solvent to prepare a measurement sample, and laser diffraction diffraction scattering particle size distribution. It measured using LA920 by HORIBA as a measuring apparatus. Ethanol was used as a solvent, and measurement was performed without applying ultrasonic waves to the measurement sample. The refractive index at the time of measurement was 0.48 to 2.6i according to the measurement conditions of copper. In the present invention, the 10% particle size, 50% particle size, and 90% particle size are particle size distributions obtained on a volume basis, and the cumulative curve with an overall volume of 100% is 10%. The volume-based cumulative 10% diameter is 50%, the volume-based cumulative 50% diameter is 50%, and the volume-based cumulative 90% diameter is 90%.

  Moreover, in the copper powder contained in the paste of the present invention, the average aspect ratio is preferably 2.5 to 6, more preferably 2.5 to 5, further preferably 2.5 to 4, and 2.5 to 3 .5 is particularly preferred. When the average aspect ratio of the copper powder is large, the contact area between the copper powder particles when processed into a conductive film is increased, and the conductivity tends to be improved. The shape of the copper powder particles is preferably flat. In the present invention, the average aspect ratio is measured as follows. First, copper powder particles are observed using a scanning electron microscope (hereinafter referred to as SEM), and 10 copper powder particles are randomly extracted from an SEM image at a magnification of 2000 times. The major axis / minor axis ratio (value obtained by dividing the major axis by the minor axis) is determined with the longest diameter in the SEM image of each copper powder particle as the major axis and the perpendicular diameter as the minor axis. Subsequently, the average value of the major axis / minor axis ratio of the ten copper powder particles is calculated, and the average value is taken as the average aspect ratio.

  Although it does not specifically limit as a resin binder contained in the paste for electrically conductive film formation of this invention, A thermosetting resin is preferable especially. Specific examples of the thermosetting resin include phenol resin, diallyl phthalate resin, unsaturated alkyd resin, epoxy resin, urea resin, melamine resin, urethane resin, bismaleide triazine resin, silicone resin and thermosetting acrylic resin. Preferably, at least one selected from the group consisting of: at least one selected from the group consisting of urea resin, melamine resin, epoxy resin and phenol resin is more preferable, and phenol resin is particularly preferable.

The resin binder can further contain a solvent in addition to the resin component. When the resin binder contains a component other than the resin component, the resin component contained in the resin binder is preferably 6 to 28 parts by mass, and more preferably 7 to 23 parts by mass with respect to 100 parts by mass of the copper powder contained in the paste. More preferably, 8-20 mass parts is especially preferable. The amount of the solvent contained in the resin binder may be in a range that provides a viscosity suitable for forming the conductive film. The specific amount of the solvent is preferably 5 to 20 parts by mass, more preferably 5 to 18 parts by mass, and particularly preferably 6 to 15 parts by mass with respect to 100 parts by mass of the copper powder contained in the paste. When the resin binder contains a solvent, part of the resin component is dissolved, and the fluidity of the conductive film forming paste is improved, which is preferable.
The amounts of the resin component and the solvent contained in the resin binder were determined as follows. First, a predetermined amount of a liquid resin binder was applied to a glass plate and heat treated at 150 ° C. for 30 minutes to obtain a cured resin binder. Next, the resin component of the resin binder was determined by dividing the mass of the obtained resin binder by the mass of the liquid resin binder. Moreover, the changed amount which decreased before and after heat processing was made into the amount of solvent.

  Solvents contained in the resin binder include cyclohexanone, cyclohexanol, terpineol, ethylene glycol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol, diethylene glycol monoethyl ether, At least one selected from the group consisting of diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate and propylene glycol monoethyl ether is preferred, and among them, ethylene glycol, ethylene glycol monoethyl ether, diethylene glycol And professional Renguriko - monoethyl - more preferably at least one selected from the group consisting of ether, diethylene glycol monoethyl ether is especially preferred.

  The conductive film forming paste of the present invention may further contain various additives as required. Examples of the additive include a leveling agent, a coupling agent, a viscosity modifier, and an antioxidant.

  In preparing the conductive film forming paste, the copper powder and the resin binder can be mixed by a known method used for producing a metal paste. Moreover, you may heat in the case of mixing, and also may mix in the atmosphere of inert gas, such as nitrogen gas or argon, as needed. Mixing in the presence of an inert gas is preferable because oxidation of copper powder can be suppressed, and a conductive film having low volume resistivity and high conductivity tends to be obtained.

<Conductive film>
The electrically conductive film of this invention is obtained by heat-processing the paste obtained by mixing copper powder and a resin binder. Specifically, a conductive film is produced by applying a paste on a glass substrate using a handrail squeegee to a rectangular parallelepiped mold.
The temperature and time of the heat treatment can be appropriately selected according to the characteristics required for the conductive film. Specifically, the temperature of the heat treatment is preferably 100 to 300 ° C, more preferably 120 to 200 ° C, and particularly preferably 130 to 170 ° C. When the temperature of the heat treatment is 100 ° C. or higher, the resin is easily cured. When the temperature of heat processing is 300 degrees C or less, since a plastic film can be used as a base material which forms an electrically conductive film, it is preferable. The heat treatment time is preferably 5 minutes to 12 hours, more preferably 10 minutes to 10 hours, and particularly preferably 15 minutes to 6 hours. Examples of the heat treatment include hot air heating and heat radiation.
When the conductive film-forming paste of the present invention is heat-treated, the resin component of the resin binder contained in the paste is decomposed to form a polymer in which resin molecules are crosslinked. Further, since the solvent contained in the paste is evaporated and removed by the heat treatment, almost no solvent remains in the obtained conductive film.
The atmosphere in which the conductive film is formed is not particularly limited, and examples thereof include air and nitrogen with little oxygen. However, air is preferable because the manufacturing equipment is simple.

The length, width and depth of the mold can be adjusted as appropriate, but a conductive film was produced under the conditions of a length of 100 mm and a width of 10 mm. Among these, since the depth of the mold is related to the thickness of the conductive film to be produced, a mold having a depth of 10 to 100 μm is preferably used, and more preferably 15 to 80 μm. When the depth of the mold is in the above range, it is preferable because the conductive film can be formed thin, and a film with high conductivity and low volume resistivity can be efficiently mass-produced with a small amount of paste. In conventional pastes, the volume resistivity tends to increase when the amount used is reduced and a thin conductive film is produced.
The substrate is preferably at least one selected from the group consisting of a glass substrate, a polyimide substrate, a plastic substrate such as a polyester film, a glass fiber reinforced composite material substrate and a ceramic substrate, and in particular, a glass substrate and a glass fiber reinforced material. Epoxy resin substrates are more preferable, and glass fiber reinforced epoxy resin substrates used for printed wiring boards are particularly preferable.
As a paste application method, any of screen printing, roll coating method, air knife coating method, blade coating method, bar coating method, gravure coating method, die coating method and slide coating method can be preferably used.

The density of the copper powder contained in the obtained conductive film is 4.0 to 6.5 g / cm ³ , and the shrinkage ratio of the components excluding the solvent volume of the paste before and after the heat treatment is 10 to 30% by volume. The composition of the paste is preferably a composition in which 15 to 40 parts by mass of a resin binder is mixed with 100 parts by mass of copper powder.
The density of the copper powder contained in the conductive film is 4.0~6.5g / cm ^3, preferably among them ^{4.5~6.5g / cm 3, 5.0~6.5g / cm} 3 Gayori preferable.
The density of the copper powder contained in the conductive film is the same as the above-described formula 1, that is, the value obtained by dividing the mass B of the prepared copper powder by the total of the mass B of the resin binder and the W. B + W) "multiplied by the mass P of the coated paste and divided by the volume V of the conductive film. In the present invention, the density of the copper powder contained in the paste and the density of the copper powder contained in the conductive film have the same value because the calculation formula is the same.

The conductive film of the present invention has a volume resistivity of preferably 50 μΩ · cm or less, more preferably 25 μΩ · cm or less, and particularly preferably 20 μΩ · cm or less. On the other hand, the volume resistivity of the conductive film is preferably as low as possible. However, in reality, considering that the volume resistivity of copper is 1 to 2 μΩ · cm, 2 μΩ · cm or more is preferable, and 3 μΩ · cm or more is more preferable. Preferably, 5 μΩ · cm or more is more preferable.
In addition, 10-50 micrometers is preferable, as for the thickness of the electrically conductive film of this invention, 10-40 micrometers is more preferable, and 10-30 micrometers is especially preferable. The conductive film of the present invention is preferable because the conductive film of the present invention can be made thinner so that a conductive film having a high electrical conductivity and a low volume resistivity can be formed with a smaller amount of paste and excellent in productivity.
The volume resistivity and thickness of the conductive film are measured as follows. First, a conductive film forming paste was applied on a glass substrate, and then heat treated at 150 ° C. for 30 minutes to produce a conductive film in which a line-shaped pattern was formed. About this electrically conductive film, the width | variety, thickness, and length of an electrically conductive film were measured using Surfcom (Surfcom FLEX by Tokyo Seimitsu), and also the resistance value of an electrically conductive film was made into HIROKI's Milliome High Tester 3540 It measured using. Next, the volume resistivity of the conductive film was determined by determining the volume of the conductive film from the measured thickness, length and width of the conductive film and dividing the measured resistance value by the volume of the conductive film.

  Examples of the article formed with the conductive film of the present invention include wiring on a thin film device of a glass substrate used for a liquid crystal display (LCD) and a thin film sensor, wiring of an element on a ceramic substrate of a solar cell, and the like. The In these fields, when manufacturing a thin film device or element, it can be used to form a conductive film such as an electric wiring film or an electrode film. At present, in these fields, particularly in the LCD field, larger size and higher definition are progressing, and conductive films such as electric wiring films and electrode films have a very low volume resistance in order to prevent signal delay. Rate is required. According to the present invention, a conductive film having a low volume resistivity that satisfies such requirements is formed.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.
Example 1 1.00 g of copper powder having a 10% particle size of 3.5 μm, a 50% particle size of 7.4 μm, a 90% particle size of 14.0 μm and an average aspect ratio of 2.8 And a resin binder containing 12.8 parts by mass of phenol resin and 9.2 parts by mass of diethylene glycol monoethyl ether with respect to 100 parts by mass of copper powder at a ratio of 22 parts by mass of resin binder to 100 parts by mass of copper powder. A paste was obtained by kneading in a mortar for 3 minutes. The used resin binder is 0.22 g. The obtained paste was applied to a rectangular parallelepiped mold having a length of 100 mm, a width of 10 mm, and a depth of 50 μm on a glass substrate using a handrail squeegee. The amount of paste used for painting was 0.1568 g and the paste volume was 0.0433 cm ³ . The volume of the solvent contained in the paste was 0.0128 g / cm ³ . Next, the glass substrate and the coated material thereon were heat-treated at 150 ° C. for 30 minutes to obtain an article in which a conductive film was formed on the glass substrate. The volume of the obtained conductive film was 0.0244 g / cm ³ . The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured. From the formula 1, the density of the copper powder in the conductive film was 0.1568 × (1.00 / (1.00 + 0.22) /0.0244) = 5.27 g / cm ³ . Further, the shrinkage rate was 1− (0.0244 / (0.0433−0.0128)) × 100 = 20% by volume from the formula 2.

Example 2 Example Copper powder having 10% particle size 2.3 μm, 50% particle size 4.4 μm, 90% particle size 7.7 μm and an average aspect ratio of 4.0 as copper powder. The composition of the paste is used with respect to 100 parts by mass of copper powder using a resin binder containing 8.7 parts by mass of phenol resin and 6.3 parts by mass of diethylene glycol monoethyl ether with respect to 100 parts by mass of copper powder. A paste was prepared in the same manner as in Example 1 except that the resin binder was changed to 15 parts by mass. The obtained paste was applied to a glass substrate in the same manner as in Example 1 to obtain an article having a conductive film formed on the glass substrate. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

Example 3 Example Copper powder having a 10% particle size of 2.3 μm, a 50% particle size of 4.4 μm, a 90% particle size of 7.7 μm and an average aspect ratio of 4.0. A paste was prepared in the same manner as in Example 1 except that was used. The obtained paste was applied to a glass substrate in the same manner as in Example 1 to obtain an article having a conductive film formed on the glass substrate. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 4] Example The composition of the paste was determined using a resin binder containing 17.4 parts by mass of phenol resin and 12.6 parts by mass of diethylene glycol monoethyl ether based on 100 parts by mass of copper powder. A paste was prepared in the same manner as in Example 1 except that the resin binder was changed to 30 parts by mass with respect to 100 parts by mass of the copper powder. The obtained paste was used in the same manner as in Example 1 to obtain an article having a conductive film formed on a glass substrate. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 5] Example A paste composed of copper powder and a resin binder was applied on a glass substrate to a rectangular parallelepiped mold having a length of 100 mm, a width of 10 mm, and a depth of 20 μm using a handrail squeegee, In the same manner as in Example 3, an article having a conductive film formed on a glass substrate was obtained. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 6] Example Except that a paste composed of copper powder and a resin binder was applied on a glass substrate to a rectangular parallelepiped mold having a length of 100 mm, a width of 10 mm, and a depth of 35 μm using a handrail squeegee, In the same manner as in Example 3, an article having a conductive film formed on a glass substrate was obtained. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 7] Example A paste composed of copper powder and a resin binder was applied on a glass substrate to a rectangular parallelepiped mold having a length of 100 mm, a width of 10 mm, and a depth of 20 μm using a handrail squeegee, In the same manner as in Example 1, an article having a conductive film formed on a glass substrate was obtained. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 8] Example A paste composed of copper powder and a resin binder was applied on a glass substrate to a rectangular parallelepiped mold having a length of 100 mm, a width of 10 mm, and a depth of 35 μm using a handrail squeegee, In the same manner as in Example 1, an article having a conductive film formed on a glass substrate was obtained. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 9] Example A paste composed of copper powder and a resin binder was applied to a rectangular parallelepiped mold having a length of 100 mm, a width of 10 mm, and a depth of 80 μm on a glass substrate using a handrail squeegee, In the same manner as in Example 1, an article having a conductive film formed on a glass substrate was obtained. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 10] Example Example 1 except that a resin binder containing 10.1 parts by mass of phenol resin and 11.9 parts by mass of diethylene glycol monoethyl ether per 100 parts by mass of copper powder was used as the resin binder. Similarly, an article having a conductive film formed on a glass substrate was obtained. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

Example 11 Example 1 is used except that a resin binder containing 7.3 parts by mass of phenol resin and 14.7 parts by mass of diethylene glycol monoethyl ether is used as a resin binder with respect to 100 parts by mass of copper powder. Similarly, an article having a conductive film formed on a glass substrate was obtained. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 12] Example The composition of the paste was determined using a resin binder containing 8.7 parts by mass of phenol resin and 6.3 parts by mass of diethylene glycol monoethyl ether based on 100 parts by mass of copper powder. A paste was prepared in the same manner as in Example 1 except that the resin binder was changed to 15 parts by mass with respect to 100 parts by mass of the copper powder. The obtained paste was used in the same manner as in Example 1 to obtain an article having a conductive film formed on a glass substrate. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 13] Example The composition of the paste was determined using a resin binder containing 23.2 parts by mass of phenol resin and 16.8 parts by mass of diethylene glycol monoethyl ether based on 100 parts by mass of copper powder. A paste was prepared in the same manner as in Example 1 except that the resin binder was 40 parts by mass with respect to 100 parts by mass of the copper powder. The obtained paste was used in the same manner as in Example 1 to obtain an article having a conductive film formed on a glass substrate. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 14] Example A paste was prepared in the same manner as in Example 1 except that the heat treatment temperature was 200 ° C. The obtained paste was used in the same manner as in Example 1 to obtain an article having a conductive film formed on a glass substrate. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 15] Example A paste was prepared in the same manner as in Example 1 except that the heat treatment temperature was 120 ° C. The obtained paste was used in the same manner as in Example 1 to obtain an article having a conductive film formed on a glass substrate. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 16] Comparative Example Example 1 except that a resin binder containing 5.7 parts by mass of phenol resin and 16.3 parts by mass of diethylene glycol monoethyl ether with respect to 100 parts by mass of copper powder was used as the resin binder. Similarly, an article having a conductive film formed on a glass substrate was obtained. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 17] Comparative Example The composition of the paste was determined using a resin binder containing 29.0 parts by mass of a phenol resin and 21.0 parts by mass of diethylene glycol monoethyl ether based on 100 parts by mass of the copper powder. A paste was prepared in the same manner as in Example 2 except that the resin binder was changed to 50 parts by mass with respect to 100 parts by mass of the copper powder. The obtained paste was used in the same manner as in Example 1 to obtain an article having a conductive film formed on a glass substrate. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

[Example 18] Comparative Example The composition of the paste was changed using a resin binder containing 29.0 parts by mass of a phenol resin and 21.0 parts by mass of diethylene glycol monoethyl ether based on 100 parts by mass of the copper powder. A paste was prepared in the same manner as in Example 1 except that the resin binder was changed to 50 parts by mass with respect to 100 parts by mass of the copper powder. The obtained paste was used in the same manner as in Example 1 to obtain an article having a conductive film formed on a glass substrate. The density, shrinkage rate, thickness, and volume resistivity of the copper powder in the conductive film were measured.

The results of Examples 1 to 15 as examples and Examples 16 to 18 as comparative examples are summarized in Table 1.
When Examples 1-15 and Examples 16-18 are compared, as shown in Table 1, the density of the copper powder contained in the conductive film is 4.4 g / cm ³ or more from the description in Example 13, and from the description in Example 12. When the volume shrinkage is 11% by volume or more, the performance is improved to a critical value of 50 μΩ · cm or less which is preferably used as a conductive film for electronic parts. Further, as described in Example 4, when the volume shrinkage is 30% by volume, the volume resistivity is 22 μΩ · cm. From these facts, it is understood that the conductivity of the conductive film is remarkably improved when the density and volumetric shrinkage of the copper powder in the conductive film are in a specific range.

  The conductive film-forming paste and the conductive film of the present invention can be used for various applications, specifically, formation and repair of wiring patterns in printed wiring boards, interlayer wiring in semiconductor packages, and printed wiring boards and electronics. It can be used for a wide range of applications such as joining parts.

Claims (9)

It is a paste containing 15 to 40 parts by mass of a resin binder with respect to 100 parts by mass of copper powder, and the density of the copper powder when the paste is cured by heat treatment at 100 to 300 ° C. is 4.0 to 6. A conductive film forming paste having a shrinkage rate of 10 to 30% by volume at 5 g / cm ³ and excluding the solvent volume of the paste.   The conductive film-forming paste according to claim 1, wherein the resin component contained in the paste is 6 to 28 parts by mass with respect to 100 parts by mass of the copper powder.   The conductive film forming paste according to claim 1 or 2, wherein the copper powder has an average aspect ratio of 2.5 to 6.   The copper powder has a 10% particle size of 2.0 to 4.0 µm, a 50% particle size of 4.0 to 8.0 µm, and a 90% particle size of 7.0 to 14.0 µm. The conductive film forming paste according to claim 1. A conductive film containing copper powder and a resin binder, wherein the density of the copper powder contained in the conductive film is 4.0 to 6.5 g / cm ³ , and the paste containing the copper powder and the resin binder is heat treated The electrically conductive film whose shrinkage | contraction rate of the component except the solvent volume of the paste in the process of shape | molding a film | membrane is 10-30 volume%.   The conductive film according to claim 5, wherein the conductive film has a thickness of 10 to 50 μm.   The conductive film according to claim 5 or 6, wherein the volume resistivity is 50 µΩ · cm or less.   The article | item in which the electrically conductive film as described in any one of Claims 5-7 was formed on the base material. It is a manufacturing method of the electrically conductive film obtained by heat-processing the paste obtained by mixing 15-40 mass parts resin binder with respect to 100 mass parts of copper powder, Comprising: The density of the copper powder of this electrically conductive film is 4. The manufacturing method of the electrically conductive film whose shrinkage | contraction rate of the component except 0-6.5 g / cm < ³ > and the solvent volume fraction of the paste before and behind heat processing is 10-30 volume%.