KR102195144B1 - Conductive paste and substrate with conductive film - Google Patents

Abstract

The present invention provides a substrate provided with a conductive paste capable of forming a conductive film having good conductivity and excellent durability, and a conductive film formed using such a conductive paste. In the present invention, (A) metal particles having a volume resistivity of 10 μΩ·cm or less and an average particle diameter of 1 to 15 μm, and (B) an average particle diameter of 0.1 to 3 μm and a redox potential of -440 mV to 320 mV It is a conductive paste containing (SHE) non-metallic particles and (C) a binder resin, and contains 0.01 to 3 parts by mass of the non-metallic particles of the (B) component based on 100 parts by mass of the metal particles of the component (A). It is a conductive paste characterized in that.

Description

Substrate with conductive paste and conductive film {CONDUCTIVE PASTE AND SUBSTRATE WITH CONDUCTIVE FILM}

The present invention relates to a substrate provided with a conductive paste and a conductive film using the same.

Conventionally, a method of using a conductive paste containing metal particles having high conductivity has been known to form wiring conductors such as electronic components and printed wiring boards. Among them, the production of a printed wiring board is performed by applying a conductive paste on an insulating substrate in a desired pattern shape and curing to form a conductive film forming a wiring pattern.

The conductive paste used for the above purpose must have (1) good conductivity, (2) easy screen printing, intaglio printing, and (3) good adhesion of the coating film on the insulating substrate. , (4) thin wire circuits, etc.

In order to satisfy these, the conductive paste contains a required amount of metal particles having a low specific resistance value such as copper or silver, a binder resin, a saturated fatty acid or an unsaturated fatty acid as a dispersant, or a metal salt thereof (refer to Patent Document 1).

By forming a conductive film from the conductive paste having the above-described configuration, good conductivity and adhesion can be ensured. However, although the initial conductivity is good, since the oxidation resistance is weak, the conductivity durability is insufficient. Therefore, there is a problem that the conductivity is impaired over time as the specific resistance increases by as much as 50% just by leaving it in the air at 25°C for 30 days.

For the purpose of improving oxidation resistance, it has been proposed to coat metal particles with low specific resistance values such as copper or silver with nickel (see Patent Document 2) or to add nickel powder to the paste as an additive (Patent Document 3). Reference).

However, the conductive paste described in Patent Literature 2 has a problem of being expensive because there is a complicated process of thinly coating nickel on the surface of metal particles by electroless plating. Further, compared to copper and silver, since nickel is a non-metal, oxidation proceeds selectively in the nickel portion. As a result of this, there is a problem that oxidized nickel is present on the surface of the metal particles, and the conductivity is impaired. In addition, the conductive paste described in Patent Literature 3 inhibits conductivity because nickel particles having a large particle diameter are added to silver particles having a low resistivity value, and the conductivity is about 20 to 65% compared to the case of only silver particles. It has a problem of getting worse.

Japanese Patent Publication No. 2007-184143 Japanese Patent Publication No. 2004-162164 Japanese Patent Laid-Open No. Hei 9-35530

Accordingly, an object of the present invention is to provide a conductive paste capable of forming a cured film having high conductivity and excellent durability when an electronic circuit is formed by screen printing.

In order to achieve the above object, the present invention provides, (A) metal particles having a volume resistivity of 10 μΩ·cm or less and an average particle diameter of 1 to 15 μm, and (B) an average particle diameter of 0.1 to 3 μm and oxidation-reduction Non-metallic particles having a potential of -440 mV to 320 mV (SHE), and (C) a conductive paste containing a binder resin, based on 100 parts by mass of the metal particles of the component (A), the non-metal particles of the component (B) It provides a conductive paste characterized in that it contains 0.01 to 3 parts by mass.

In the conductive paste of the present invention, the value of (average particle diameter of non-metallic particles of component (B))/(average particle diameter of metal particles of (A) component) is preferably 0.01 to 1.0.

In the conductive paste of the present invention, the metal particles of the component (A) are preferably copper particles or silver particles having an average particle diameter of 1 to 15 µm.

In the conductive paste of the present invention, the binder resin of the component (C) is preferably a resin containing a thermosetting resin containing formaldehyde as one component, and is selected from the group consisting of a phenol resin, a melamine resin, a xylene resin, and a urea resin. It is more preferable that it is more than one type.

In the conductive paste of the present invention, it is preferable that the non-metallic particles of the component (B) be at least one selected from the group consisting of nickel, tin, bismuth, and iron.

Further, the present invention provides a substrate with a conductive film, characterized in that the conductive film formed by coating and curing the conductive paste of the present invention described above is provided on the substrate.

According to the conductive paste of the present invention, a cured film having high conductivity and excellent conductive durability can be obtained. Specifically, the initial specific resistance is 30 µΩcm or less, and the durability measured according to the procedure described in Examples to be described later is 15% or less in the amount of change (increase) of the resistance value after the high temperature and high humidity test.

In addition, by using such a conductive paste, it is possible to obtain a substrate having a highly reliable conductive film having excellent conductivity and suppressing deterioration of conductivity due to the environment during use. Such a highly reliable conductive film is suitable for use in automobile parts requiring high durability.

Hereinafter, an embodiment of the present invention will be described. In addition, this invention is limited to the following description and is not interpreted.

<Conductive paste>

The conductive paste of the present invention comprises (A) metal particles having a volume resistivity of 10 μΩ·cm or less and an average particle diameter of 1 to 15 μm, and (B) an average particle diameter of 0.1 to 3 μm and an oxidation-reduction potential of -440 mV. It is a conductive paste containing non-metallic particles of to 320 mV (SHE) and (C) a binder resin, and contains 0.01 to 3 parts by mass of the non-metallic particles of the component (B) with respect to 100 parts by mass of the metal particles of the component (A). Characterized in that.

Hereinafter, each component constituting the conductive paste will be described in detail.

(A) metal particles

The metal particles of the component (A) are a conductive component of the conductive paste.

The metal particles of the component (A) are required to have good conductivity. In the present invention, metal particles having a volume resistivity value of 10 Ω·cm or less are used.

Metals that satisfy this may include gold, silver, and copper. Among these, silver and copper are preferable for reasons such as low resistance value and easy availability, and copper is particularly preferable because migration is difficult to occur.

The metal particles of the component (A) have an average value of particle diameters defined below, that is, an average particle diameter of 1 to 15 µm.

The particle diameter of the metal particles in the present specification is measured by measuring the Feret diameter of 100 metal particles randomly selected from a scanning electron microscope (hereinafter referred to as ``SEM'') image, and in each metal particle When the radial direction at which the maximum Feret diameter of is the major axis and the axis orthogonal to the major axis is the minor axis, the average value of the Feret diameter in the major axis direction and the Feret diameter in the minor axis direction ((Feret diameter in the major axis + short axis It is calculated as the Feret diameter in the direction)/2).

In addition, the particle diameter of the said metal particle is the primary particle diameter of a metal particle.

The average value (average particle diameter) of the particle diameter of the metal particles in the present specification is the average (number average) of the particle diameters of the metal particles calculated as described above.

When the average value (average particle diameter) of the particle diameter of the metal particles of the component (A) satisfies the above range, the flow characteristics of the conductive paste containing the metal particles are improved, and fine wiring is produced from the conductive paste. easy to do. When the average value (average particle diameter) of the particle diameters of the metal particles is less than 1 µm, sufficient flow characteristics cannot be obtained when using a conductive paste. On the other hand, when the average value (average particle diameter) of the particle diameters of the metal particles exceeds 15 µm, there is a concern that it may become difficult to manufacture fine wiring using the obtained conductive paste.

It is preferable that it is 1-15 micrometers, and, as for the average value (average particle diameter) of the particle diameter of the metal particle of (A) component, it is more preferable that it is 2-8 micrometers.

Further, as the metal particles of the component (A), "surface-modified metal particles" obtained by reducing the surface of the metal particles may be used. In the surface-modified metal particles, since the oxygen concentration on the surface of the particles is lowered by the reduction treatment, the contact resistance between the metal particles becomes smaller, and the conductivity of the resulting conductive film is improved.

In the conductive paste of the present invention, the compounding amount of the metal particles of the component (A) is preferably 75 to 95 parts by mass, and more preferably 80 to 90 parts by mass, based on 100 parts by mass of the total of all components of the conductive paste. If it is 75 parts by mass or more, the conductivity of the conductive film formed using the conductive paste becomes good. If it is 95 parts by mass or less, the portion where the metal particles and the binder resin are bonded increases, the hardness of the cured film is improved, and the flow characteristics of the conductive paste are improved.

(B) non-metallic particles

The nonmetallic particles of the component (B) are components that contribute to the improvement of durability. The non-metal used for the non-metallic particles of the component (B) is a metal that is more susceptible to oxidation than the metal of the component (A), and is a metal that is less likely to undergo spontaneous oxidation by oxygen in the air. The redox potential of this non-metal is in the range of -440 mV to 320 mV (SHE (standard hydrogen electrode)) based on the standard electrode potential (oxidation-reduction potential) at 25°C at which stable metal ions are reduced to metal in aqueous solution. Is in.

Specific metals include nickel (oxidation-reduction potential -257 mV (SHE)), tin (oxidation-reduction potential -140 mV (SHE)), bismuth (oxidation-reduction potential 317 mV (SHE)), iron (oxidation-reduction potential -440 mV ( SHE)) etc. are mentioned. Among these, nickel and tin are preferable for reasons such as low resistance value and easy availability, and nickel is particularly preferable from the viewpoint of stability of the surface oxide film.

The non-metallic particles of the component (B) exist between the metal particles of the component (A) that mainly exhibit electrical conductivity, and in the interaction with the metal particles of the component (A), the nonmetal of the component (B) is (A) Since it is a non-metal compared to the metal of the component, it is considered that it acts as a sacrificial anode when the metal particles of the component (A) are in an oxidized environment, and the oxidation of the metal particles of the component (A) can be suppressed. On the other hand, the non-metallic particles of the component (B) having a relatively high resistivity value hardly exist at the interface between the metal particles (particles of the component (A)) having a low resistivity during heat curing. The conduction of Esau is not hindered.

The nonmetallic particles of the component (B) have an average value of the particle diameters defined above, that is, an average particle diameter of 0.1 to 3 µm.

When the average value (average particle diameter) of the particle diameter of the non-metallic particles of the component (B) satisfies the above range, the flow characteristics of the conductive paste containing the non-metallic particles are improved, and fine wiring is produced from the conductive paste. easy to do. If the average value (average particle diameter) of the particle diameter of the non-metallic particles is less than 0.1 µm, when a conductive paste is formed, flow characteristics become difficult to obtain, and spontaneous oxidation proceeds, making it difficult to contribute to the improvement of durability. On the other hand, when the average value (average particle diameter) of the particle diameter of the non-metallic particles exceeds 3 μm, there is a fear that it becomes difficult to contribute to the improvement of the conductive durability.

The average value (average particle diameter) of the nonmetallic particles of the component (B) is preferably 0.1 to 3 µm, more preferably 0.1 to 2 µm, and still more preferably 0.1 to 1 µm.

In addition, when paying attention to the ratio of the average particle diameter of the nonmetallic particles of the component (B) and the average particle diameter of the metal particles of the component (A), the average particle diameter of the nonmetallic particles of the component (B) / the average of the metal particles of the component (A) It is preferable that the value of the particle diameter is 0.01 to 1.0.

Since the value of the average particle diameter of the non-metallic particles of the component (B) / the average particle diameter of the metallic particles of the component (A) satisfies the above range, the non-metallic particles are effective as a sacrificial anode in relation to the metal particles in the conductive paste. As a result, a conductive film formed using a conductive paste has good conductivity and excellent durability. If the value of the average particle diameter of the non-metallic particles of the component (B)/the average particle diameter of the metal particles of the component (A) is less than 0.01, when a conductive paste is used, flow characteristics become difficult to obtain and spontaneous oxidation proceeds, resulting in durability. It becomes difficult to contribute to improvement. On the other hand, when the average particle diameter of the nonmetallic particles of the component (B)/the average particle diameter of the metal particles of the component (A) exceeds 1.0, there is a fear that it becomes difficult to contribute to the improvement of the conductive durability.

It is more preferable that the value of the average particle diameter of the nonmetallic particles of the component (B)/the average particle diameter of the metal particles of the component (A) is 0.03 to 0.5.

In the conductive paste of the present invention, the blending amount of the non-metallic particles of the component (B) is 0.01 to 3 parts by mass per 100 parts by mass of the metal particles of the component (A). The blending amount is preferably 0.02 to 2.5 parts by mass, more preferably 0.02 to 1.5 parts by mass, particularly preferably 0.02 to 1.0, and very preferably 0.02 to 0.3.

When the blending amount of the nonmetallic particles of the component (B) satisfies the above range, the nonmetallic particles effectively act as sacrificial anodes in relation to the metal particles in the conductive paste, and a conductive film formed using the conductive paste is , Has good conductivity and excellent durability.

If the blending amount of the non-metallic particles of the component (B) is less than 0.01 parts by mass per 100 parts by mass of the metal particles of the component (A), since the blending amount of the non-metallic particles is insufficient, the non-metallic particles in relation to the metal particles in the conductive paste Does not function sufficiently as a sacrificial anode. For this reason, it becomes difficult to contribute to the improvement of durability.

On the other hand, if the blending amount of the non-metallic particles of the component (B) is more than 3 parts by mass based on 100 parts by mass of the metal particles of the component (A), the metal particles having a low specific resistance value (particles of the component (A)) during heat curing ) Non-metallic particles with relatively high resistivity (particles of component (B)) exist at the interface between them, and as a result, conduction between metal particles with low resistivity is inhibited, resulting in lowering the conductivity of the formed conductive film. I think.

(C) binder resin

In the conductive paste containing metal particles, a binder resin is used in order to maintain the structure of the conductor including the metal particles formed after curing.

In the conductive paste of the present invention, it is preferable to use, as the binder resin of the component (C), a thermosetting resin containing formaldehyde as one component. The reason for this is that the thermosetting resin containing formaldehyde as a single component has a large shrinkage during heat curing, and the force to press the metal particles becomes strong, so that high conductivity is easily obtained. In addition, especially when copper fine particles are used as metal particles, oxidation on the surface of the copper particles can be suppressed by the reduction of methylol groups generated from formaldehyde, and curing shrinkage proceeds appropriately to ensure contact between copper particles. Because it becomes.

As a thermosetting resin containing formaldehyde as one component, a phenol resin, a melamine resin, a xylene resin, and a urea resin are illustrated. Among them, phenolic resins are preferable from the extent of reduction of methylol groups and curing shrinkage. If the cure shrinkage is too large, unnecessary stress is accumulated in the conductive film, which causes mechanical breakdown. If the curing shrinkage is too small, sufficient contact between metal particles cannot be ensured.

In the conductive paste of the present invention, the blending amount of the binder resin of the component (C) can be appropriately selected according to the ratio of the volume of the component (A) (for example, copper particles) and the volume of the voids present between the metal particles. It is preferably 5 to 25 parts by mass, and more preferably 10 to 20 parts by mass, based on 100 parts by mass of all components of the conductive paste. If it is 5 parts by mass or more, the portion where the binder resin and the surface of the metal particles are bonded increases, the hardness of the cured film is improved, and the flow characteristics of the conductive paste are improved. If it is 25 parts by mass or less, the conductivity of the conductive film formed using the conductive paste becomes good.

(D) other ingredients

The conductive paste of the present invention contains, as necessary, a solvent or various additives (leveling agent, viscosity modifier, etc.) in addition to each component of the above (A) to (C) within a range that does not impair the effects of the present invention. You may have it. In particular, in order to obtain a paste having an appropriate fluidity, it is preferable to contain a solvent capable of dissolving the thermosetting resin.

As a solvent, for example, 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, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate can be used. As the printing paste, it is preferable that the amount of the solvent to be contained in the conductive paste is in a ratio of 5 to 40 parts by mass with respect to 100 parts by mass in total of all components of the conductive paste from the viewpoint of setting a suitable viscosity range.

The conductive paste can be obtained by mixing each component of the above (A) to (C) and other components such as the above solvent as necessary. When mixing each component of the above (A) to (C), it can be carried out while heating under a temperature such that curing of the thermosetting resin or volatilization of the solvent does not occur.

The temperature at the time of mixing and stirring is preferably 10 to 40°C. More preferably, it is good to set it as 20-30 degreeC. By heating at a temperature of 10° C. or higher when producing the conductive paste, the viscosity of the paste can be sufficiently reduced, and the stirring can be smoothly and sufficiently performed. On the other hand, when the temperature at the time of manufacturing the conductive paste exceeds 40°C, there is a fear that curing of the resin may occur in the paste or fusion of particles may occur. Further, in order to prevent the metal particles from being oxidized during mixing, it is preferable to mix in a container substituted with an inert gas.

In the conductive paste of the present invention described above, the volume resistivity of the component (A) is 10 μΩ·cm or less and the average particle diameter is 1 to 15 μm, together with metal particles, (B) the average particle diameter is 0.1 to 3 μm. Since the non-metal particles having an oxidation-reduction potential of -440 mV to 320 mV (SHE) and the binder resin of the component (C) are contained, the conductive film formed from this conductive paste is excellent in conductivity and durability.

<Substrate with conductive film>

A substrate with a conductive film of the present invention has a substrate and a conductive film formed by coating and curing the conductive paste of the present invention described above on the substrate.

Examples of the substrate main body include a glass substrate, a plastic substrate (eg, a polyimide substrate, a polyester substrate, etc.), and a substrate made of a fiber-reinforced composite material (eg, a glass fiber reinforced resin substrate, etc.).

As a method of applying the conductive paste, known methods such as a screen printing method, a roll coating method, an air knife coating method, a blade coating method, a bar coating method, a gravure coating method, a die coating method, and a slide coating method may be mentioned. Among these, the screen printing method is preferable.

The curing of the coating layer is performed by heating by a method such as warm air heating or thermal radiation heating to cure the resin (thermosetting resin) in the conductive paste.

The heating temperature and heating time may be appropriately determined according to the characteristics required for the conductive film. The heating temperature is preferably 80 to 200°C. When the heating temperature is 80° C. or higher, curing of the binder resin proceeds smoothly, the contact between the metal particles is improved, and conductivity and durability are improved. When the heating temperature is 200° C. or lower, a plastic substrate can be used as the base body, so that the degree of freedom in selecting the base material increases.

The thickness of the conductive film formed on the substrate is preferably 1 to 200 µm, and more preferably 5 to 100 µm, from the viewpoint of ensuring stable conductivity and maintenance of the wiring shape.

The specific resistance (also referred to as volume resistivity) of the conductive film is preferably 30 μΩcm or less. When the specific resistance of the conductive film exceeds 30 µΩcm, it may be difficult to use it as a conductor for electronic devices.

In addition, it is preferable that the amount of change (increase) of the specific resistance after the durability test is 20% or less in the conductive durability measured according to the procedure described in Examples to be described later. It is more preferable that it is 10% or less, and it is especially preferable that it is 5% or less.

[Example]

Hereinafter, the present invention will be described in more detail by examples, but the present invention is not limited to these examples. Examples 1 to 8 are Examples, and Examples 9 to 13 are Comparative Examples. In addition, the average particle diameter of the metal particle (copper particle) and the non-metal particle (nickel particle), the thickness of a conductive film, and the specific resistance were respectively measured using the apparatus shown below.

(Average particle diameter)

Copper particles were used as metal particles. The particle diameter of the copper particle is measured by measuring the Feret diameter of 100 particles randomly selected from the SEM image obtained by SEM (manufactured by Hitachi High Technologies, S-4300), and the Feret diameter in each copper particle becomes the maximum value. When the radial direction is the major axis and the axis perpendicular to the major axis is the minor axis, the average value of the feret diameter in the major axis direction and the feret diameter in the minor axis direction ((Feret diameter in the major axis direction + Feret diameter in the minor axis direction)/2) It was calculated as. And the average value (average particle diameter) of the particle diameter was calculated|required by average (number average) the particle diameter of the calculated copper particle.

(The thickness of the conductive film)

The thickness of the conductive film was measured using DEKTAK3 (manufactured by Veeco metrology Group).

(Resistivity of conductive film)

The specific resistance of the conductive film was measured using a 4-probe volume resistivity meter (manufactured by Mitsubishi Yuka Corporation, type: lorestaIPMCP-T250).

Example 1

After putting 3.0 g of formic acid and 9.0 g of a 50% by mass hypophosphorous acid aqueous solution into a glass beaker, this beaker was placed in a water bath and maintained at 40°C. In this beaker, 5.0 g of copper particles (manufactured by Mitsui Kinjoku Kogyo Co., Ltd., brand name: 1400YP) having an average particle diameter of 6 µm were gradually added and stirred for 30 minutes to obtain a copper dispersion.

From the obtained copper dispersion liquid, centrifugal separation was performed for 10 minutes at a rotation speed of 3000 rpm using a centrifugal separator to recover a precipitate. The precipitate was dispersed in 30 g of distilled water, and the precipitate was again precipitated by centrifugation to separate the precipitate. Thereafter, the obtained precipitate was heated at 80° C. for 60 minutes under a reduced pressure of -35 kPa to volatilize residual moisture and gradually removed, thereby obtaining copper particles (A) having surface-modified particles.

The copper particles after surface modification do not change the average value of the particle diameter and are 6 µm. In addition, that the average value of the particle diameter of the copper particles after surface modification does not change is the same for other examples shown below.

Subsequently, 12 g of the obtained surface-modified copper particles (A) were added to 3.7 g of a phenolic resin (manufactured by Gunei Chemical Co., Ltd., brand name: Rezitop PL6220, all the same in the following examples) as component (C). It was added to the resin solution dissolved in 4.3 g of butyl ether acetate. Further, with this mixture, 0.02 g of nickel powder (average particle diameter 0.3 µm, redox potential -257 mV (SHE)) as component (B) was put in a mortar, and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) was 0.17 parts by mass with respect to 100 parts by mass of the copper particles of the component (A). The blending amount of the component (C) was 11 parts by mass with respect to 100 parts by mass in total of all components of the copper paste. In addition, the value of the average particle diameter of the nickel powder (particle) of component (B)/the average particle diameter of the copper particle of (A) component is 0.05.

Example 2

Copper paste in the same manner as in Example 1 except that copper particles having an average particle diameter of 7 μm (manufactured by Nippon Atomize Chemical Co., Ltd., brand name: AFS-Cu) and nickel powder were changed to an average particle diameter of 0.5 μm. Got it. The average particle diameter of the nickel powder (particle) of the component (B)/the average particle diameter of the copper particles of the component (A) is 0.07.

Example 3

A copper paste was obtained in the same manner as in Example 1 except that the copper particles were changed to copper particles having an average particle diameter of 3 µm (manufactured by Nippon Atomize Chemical Co., Ltd., brand name: AFS-Cu). The value of the average particle diameter of the nickel powder (particle) of the component (B)/the average particle diameter of the copper particles of the component (A) is 0.1.

Example 4

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 were added to a resin solution in which 3.7 g of a phenol resin as a component (C) was dissolved in 4.3 g of ethylene glycol monobutyl ether acetate, and with this mixture, ( B) 0.004 g of nickel powder (average particle diameter: 0.2 µm) as a component was put into a mortar and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) was 0.03 parts by mass with respect to 100 parts by mass of the copper particles of the component (A). In addition, the value of the average particle diameter of the nickel powder (particle) of component (B)/the average particle diameter of the copper particle of (A) component is 0.03.

Example 5

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 were added to a resin solution in which 3.7 g of a phenol resin as a component (C) was dissolved in 4.3 g of ethylene glycol monobutyl ether acetate, and with this mixture, ( B) 0.02 g of nickel powder (average particle diameter of 2.5 µm) as a component was put in a mortar and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) was 0.17 parts by mass with respect to 100 parts by mass of the copper particles of the component (A). In addition, the value of the average particle diameter of the nickel powder (particle) of the component (B)/the average particle diameter of the copper particles of the component (A) is 0.42.

Example 6

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 were added to a resin solution in which 3.7 g of a phenol resin as a component (C) was dissolved in 4.3 g of ethylene glycol monobutyl ether acetate, and with this mixture, ( B) 0.1 g of nickel powder (average particle diameter: 0.3 µm) as a component was put in a mortar and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) was 0.8 parts by mass based on 100 parts by mass of the copper particles of the component (A). In addition, the value of the average particle diameter of the nickel powder (particle) of component (B)/the average particle diameter of the copper particle of (A) component is 0.05.

Yes 7

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 3 were added to a resin solution in which 3.7 g of a phenol resin as a component (C) was dissolved in 4.3 g of ethylene glycol monobutyl ether acetate, and together with this mixture, ( B) 0.02 g of nickel powder (average particle diameter of 2.5 µm) as a component was put in a mortar and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) was 0.17 parts by mass with respect to 100 parts by mass of the copper particles of the component (A). In addition, the value of the average particle diameter of the nickel powder (particle) of the component (B)/the average particle diameter of the copper particles of the component (A) is 0.83.

Yes 8

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 were added to a resin solution in which 3.7 g of a phenol resin as a component (C) was dissolved in 4.3 g of ethylene glycol monobutyl ether acetate, and with this mixture, ( B) 0.2 g of nickel powder (average particle diameter of 2.5 µm) as a component was put in a mortar and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) was 1.7 parts by mass with respect to 100 parts by mass of the copper particles of the component (A). In addition, the value of the average particle diameter of the nickel powder (particle) of the component (B)/the average particle diameter of the copper particles of the component (A) is 0.42.

Yes 9

With respect to 12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1, it was carried out in the same manner as in Example 1 except that the nickel powder of the component (B) was not added, and mixed at room temperature to obtain a copper paste.

Yes 10

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 were added to a resin solution in which 3.7 g of a phenol resin as a component (C) was dissolved in 4.3 g of ethylene glycol monobutyl ether acetate, and with this mixture, ( B) 0.001 g of nickel powder (average particle diameter: 0.3 µm) as a component was put in a mortar and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) was 0.008 parts by mass with respect to 100 parts by mass of the copper particles of the component (A). In addition, the value of the average particle diameter of the nickel powder (particle) of component (B)/the average particle diameter of the copper particle of (A) component is 0.05.

Yes 11

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 were added to a resin solution in which 3.7 g of a phenol resin as a component (C) was dissolved in 4.3 g of ethylene glycol monobutyl ether acetate, and with this mixture, ( B) 0.4 g of nickel powder (average particle diameter: 0.3 µm) as a component was put into a mortar and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) was 3.3 parts by mass with respect to 100 parts by mass of the copper particles of the component (A). In addition, the value of the average particle diameter of the nickel powder (particle) of component (B)/the average particle diameter of the copper particle of (A) component is 0.05.

Yes 12

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 were added to a resin solution in which 3.7 g of a phenol resin as a component (C) was dissolved in 4.3 g of ethylene glycol monobutyl ether acetate, and with this mixture, ( B) 0.02 g of nickel powder (average particle diameter of 0.05 µm) as a component was put in a mortar and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) was 0.17 parts by mass with respect to 100 parts by mass of the copper particles of the component (A). In addition, the value of the average particle diameter of the nickel powder (particle) of component (B)/the average particle diameter of the copper particle of (A) component is 0.008.

Yes 13

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 were added to a resin solution in which 3.7 g of a phenol resin as a component (C) was dissolved in 4.3 g of ethylene glycol monobutyl ether acetate, and with this mixture, ( B) 0.02 g of nickel powder (average particle diameter of 10 µm) as a component was put in a mortar and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) was 0.17 parts by mass with respect to 100 parts by mass of the copper particles of the component (A). In addition, the value of the average particle diameter of the nickel powder (particle) of the component (B)/the average particle diameter of the copper particles of the component (A) is 1.7.

Next, the copper pastes obtained in Examples 1 to 13 were each applied on a glass having a thickness of 3 mm, heated at 150° C. for 30 minutes, and the phenol resin as component (C) was cured to form a conductive film having a thickness of 15 μm. Formed. Then, the electrical resistance value of the obtained conductive film was measured using a resistance value meter (manufactured by Keithley, brand name: Milliohm High Tester), and the specific resistance (volume resistivity; unit μΩcm) was measured. Further, the same conductive film was stored in a high-temperature, high-humidity bath at 85°C and 85% RH for 250 hours, and then the electrical resistance value was measured, and the amount of change in the electrical resistance value was measured.

The results are summarized in Table 1.

As can be seen from Table 1, 0.01 to 3 parts by mass of nickel powder having an average particle diameter of 0.1 to 3 µm per 100 parts by mass of copper particles, together with copper particles having an average particle diameter of 1.0 to 15 µm. By using the conductive pastes of Examples 1 to 8 to be contained, the conductive film obtained by applying the conductive paste to a substrate and curing had a low specific resistance and was 25 µΩcm or less. Further, the change (deterioration) in conductivity after storage at high temperature and high humidity was also suppressed. This is considered to be due to the fact that an appropriate amount of nickel particles can exist between the copper particles, and the contact area between the copper particles and the nickel particles is increased, so that the function as a sacrificial anode has been effective.

On the other hand, Example 9 in which the nickel powder of component (B) was not blended, Example 10, 3 mass of which the blending amount of nickel powder of component (B) was less than 0.01 parts by mass based on 100 parts by mass of metal particles of component (A) Part 11, Example 12 in which nickel powder having an average particle diameter of 0.05 μm instead of 0.1 to 3 μm as the nickel powder of component (B) was blended, and the nickel powder of component (B) having an average particle diameter of 0.1 to In Example 13, in which nickel powder having an average particle diameter of 10 µm was mixed instead of 3 µm, the conductive film produced by using a conductive paste had a large change (deterioration) in conductivity after storage at high temperature and high humidity.

In addition, the conductive film formed from the metal paste using the copper powder of Patent Literature 1 has a large change in conductivity (deterioration) so that the specific resistance increases by 50% just by leaving it in the atmosphere at 25°C for 30 days. It is difficult to form the conductor wiring of an electronic component.

Although this application has been described in detail and with reference to specific embodiments, it is clear to those skilled in the art that various changes and modifications can be added without departing from the spirit and scope of the present invention.

This application is based on the Japanese patent application (Japanese Patent Application No. 2013-182783) for which it applied on September 4, 2013, The content is taken in here as a reference.

The conductive paste of the present invention can be used for various purposes, and can be used, for example, for forming and repairing a wiring pattern on a printed wiring board, interlayer wiring in a semiconductor package, and bonding a printed wiring board to an electronic component.

Claims (7)

(A) Surface-modified copper particles having a volume resistivity of 10 μΩ·cm or less and an average particle diameter of 1 to 15 μm, and (B) an average particle diameter of 0.1 to 3 μm and an oxidation-reduction potential of -440 mV to 320 mV (SHE ) Nonmetallic particles and (C) a conductive paste containing a binder resin, and 0.01 to 3 nonmetallic particles of the component (B) per 100 parts by mass of the surface-modified copper particles of the component (A). A conductive paste containing a mass part. The conductive paste according to claim 1, wherein the average particle diameter of the nonmetallic particles of the component (B)/the average particle diameter of the surface-modified copper particles of the component (A) is 0.01 to 1.0. The conductive paste according to claim 1 or 2, wherein the binder resin of the component (C) is a resin containing a thermosetting resin containing formaldehyde as one component. The conductive paste according to claim 1 or 2, wherein the non-metallic particles of the component (B) are at least one selected from the group consisting of nickel, tin, bismuth, and iron. The conductive paste according to claim 1 or 2, wherein the non-metallic particles of the component (B) are nickel. The conductive paste according to claim 1 or 2, wherein the binder resin of the component (C) is at least one selected from the group consisting of phenol resins, melamine resins, xylene resins, and urea resins. A substrate with a conductive film, comprising a conductive film formed by applying and curing the conductive paste according to claim 1 or 2 on the substrate.