TW201516126A - Conductive paste and substrate with conductive film - Google Patents

Abstract

The present invention provides a conductive paste that can form conductive films with good conductivity and excellent bending property, and a substrate with conductive film thereon using the conductive paste. The conductive paste of this invention is characterized in that it contains (A) metallic particles with volume resistivity below 10[mu][Omega]-cm and average particle size of 0.5-15 [mu]m, (B) silane compound represented by Rx-Si-OR'4-x (where, x is an integer of 1-3, R is a mutually independent alkyl group having 1-25 carbon atoms under condition that the total number of carbon atoms in 1-3 alkyl group is below 30, and OR' is a mutually independent alkoxy group having 1-4 carbon atoms), and (C) thermosetting adhesive resin containing formaldehyde as one component. With respect to the total composition of the aforementioned conductive paste as 100 mass%, the adhesive resin of component (C) accounts to 5-25 mass%, and the silane compound of component (B) accounts to 0.01-2.5 mass%.

Description

Conductive paste and substrate with conductive film

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

A method of forming a wiring conductor such as an electronic component or a printed wiring board by using a conductive paste containing metal particles having high conductivity has been known. Among them, the printed wiring board is produced by applying a conductive paste to a desired pattern shape on an insulating substrate and curing it to form a conductive film having a wiring pattern.

The conductive paste used for the above purpose should have the following characteristics: (1) good conductivity; (2) screen printing and gravure printing; (3) good adhesion of the coating film to the insulating substrate; 4) A thin wire circuit can be formed; (5) excellent weldability and weld strength to the coating film; and (6) electrical conductivity of the solder coating circuit can be maintained for a long period of time.

In order to satisfy these characteristics, the conductive paste contains a metal oxide particle having a low resistance value such as copper or silver, a thermosetting resin such as a phenol resin as a binder resin, or a saturated fatty acid or an unsaturated fatty acid as a dispersing agent. The metal salt and the metal chelate forming agent (see Patent Document 1).

The conductive film is formed by the conductive paste having the above configuration, whereby good conductivity can be ensured. However, in the case where the conductive film is formed of a flexible film, there is a problem in that the formed conductive film and the flexible film are inferior in adhesion, and thus the electronic circuit is broken due to the bending, thereby impairing the conductivity.

When a flexible film is formed into an electronic circuit, it is proposed to contain a conductive powder such as metal or carbon as a conductive paste having a high bending resistance, and an acid value of 0.3 to 2.2. A conductive paste composition of a polyester resin of mgKOH/g (refer to Patent Document 2).

However, since the conductive paste described in Patent Document 2 uses a thermoplastic polyester resin having a soft property as a binder resin, it has a problem that it is easily damaged and easily broken.

Further, Patent Document 3 discloses an electrically conductive adhesive comprising an epoxy resin, a curing agent, a curing accelerator, a decane coupling agent, and a conductive filler. In the conductive adhesive, the decane coupling agent has an effect of improving the wettability of the conductive filler and the resin and the adhesion to the adherend, and is effective for obtaining the moisture resistance of the cured product.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 5-212579

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2005-197226

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2009-1604

Accordingly, it is an object of the present invention to provide a conductive paste which can be formed into a cured film having a certain bending resistance when a flexible film is formed into an electronic circuit.

In order to achieve the above object, the present invention provides a conductive paste comprising (A) a metal particle having a volume resistance value of 10 μΩ··cm or less and an average particle diameter of 0.5 to 15 μm, and (B) by R _{x .} -Si-OR' _4-x represents a decane compound (wherein x is an integer of 1 to 3, and R is independently a carbon number of 1 or more, and the carbon number is 1 or less. ~25 alkyl group, OR' is an alkoxy group independently of each other and having a carbon number of 1 to 4), and (C) a binder resin containing a thermosetting resin containing formaldehyde as a component, and is electrically conductive with respect to the above 100 parts by mass of the total of all the components of the paste, and 5 to 25 parts by mass of the binder resin containing the component (C), and 0.01 to 2.5 parts by mass of the decane compound containing the component (B).

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 0.5 to 15 μm.

In the conductive paste of the present invention, preferably, the decane compound of the above component (B) is selected from the group consisting of methyltrimethoxydecane, ethyltrimethoxydecane, propyltrimethoxydecane, and butyltrimethoxy. Decane, hexyltrimethoxydecane, heptyltrimethoxydecane, octyltrimethoxydecane, decyltrimethoxydecane,decyltrimethoxydecane,undecyltrimethoxydecane,dodecyltrimethyl Oxydecane, tridecyltrimethoxynonane, tetradecyltrimethoxynonane, pentadecyltrimethoxydecane,hexadecyltrimethoxynonane,heptadecyltrimethoxydecane, ten One or more of the group consisting of octadecyltrimethoxydecane.

In the conductive paste of the present invention, the binder resin of the component (C) is preferably one or more selected from the group consisting of a phenol resin, a melamine resin, a xylene resin, and a urea resin.

Moreover, the present invention provides a substrate with a conductive film, comprising a conductive film obtained by applying the above-described conductive paste of the present invention and hardening the substrate.

In the substrate with a conductive film of the present invention, it is preferred that the substrate be a flexible film.

According to the conductive paste of the present invention, a cured film having high conductivity and having a certain bending resistance can be obtained. Specifically, the initial specific resistance is 50 μΩcm or less, and the amount of change (increase) in the specific resistance before and after bending (the number of bending times is 5 times) measured in the order described in the following examples is 400% or less. .

In addition, by using such a conductive paste, it is possible to obtain a substrate with a conductive film which is highly reliable as a flexible film wiring board and which is excellent in deterioration of conductivity due to bending during use.

Hereinafter, embodiments of the present invention will be described. Furthermore, the present invention is not limited to the following description.

<Electrically conductive paste>

The conductive paste of the present invention is characterized in that it contains (A) metal particles having a volume resistance value of 10 μΩ··cm or less and an average particle diameter of 0.5 to 15 μm, and (B) R _x -Si-OR' _{4- x} is a decane compound (wherein x is an integer of 1 to 3, and R is an alkyl group having a carbon number of 1 to 25 as a condition of a total carbon number of 1 to 3 alkyl groups of 30 or less, OR 'Alkoxy group which is independent of each other and having a carbon number of 1 to 4, and (C) a binder resin containing a thermosetting resin containing formaldehyde as a component, and total of all components of the conductive paste 100 parts by mass of the binder resin containing the component (C) is 5 to 25 parts by mass, and the decane compound containing the component (B) is 0.01 to 2.5 parts by mass.

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

(A) metal particles

The metal particle of the component (A) is 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 resistance value of 10 μΩ··cm or less are used.

Examples of the metal satisfying the above requirements include gold, silver, copper, nickel, and aluminum. Among these, in terms of a low resistance value and ease of acquisition, it is preferable that silver or copper is not easily caused to migrate, and copper is particularly preferable.

The metal particles of the component (A) are based on the average value of the particle diameters defined below, that is, the average particle diameter is 0.5 to 15 μm.

The particle diameter of the metal particles in the present specification is measured by the Feret diameter of 100 metal particles randomly selected from a scanning electron microscope (hereinafter referred to as "SEM") image, and the Feret diameter in each metal particle is The radial value of the maximum value is set to the long axis, and the long axis will be positive When the axis of intersection is a short axis, the average value of the Feret diameter in the long axis direction and the Feret diameter in the short axis direction ((Feret diameter in the short axis direction of the Feret diameter in the long axis direction)/2) is calculated.

Further, the particle diameter of the above-mentioned metal particles is the primary particle diameter of the metal particles.

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

When the average value (average particle diameter) of the particle diameters 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 the conductive paste is easily used. Make fine wiring. When the average value (average particle diameter) of the particle diameter of the metal particles is less than 0.5 μm, sufficient flow characteristics cannot be obtained when the conductive paste is formed. On the other hand, when the average value (average particle diameter) of the particle diameter of the metal particles exceeds 15 μm, it is difficult to produce fine wiring by using the obtained conductive paste.

The average value (average particle diameter) of the particle diameter of the metal particles of the component (A) is preferably from 0.5 to 10 μm, more preferably from 1 to 5 μm.

Further, as the metal particles of the component (A), "surface-modified metal particles" having a surface treated with a metal particle may be used. Since the surface-modified metal particles have a low oxygen concentration on the surface of the particles by the reduction treatment, the contact resistance between the metal particles becomes smaller, and the conductivity of the obtained conductive film is improved.

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

(B) decane compound

The decane compound of the component (B) is represented by the following formula (1).

R _x -Si-OR' _4-x (1)

In the formula, x is an integer of from 1 to 3, and R is an alkyl group having a carbon number of from 1 to 25 as a condition of a total of from 1 to 3 alkyl groups, and the OR' is independent of each other and carbon. The number is 1 to 4 alkoxy groups.

That is, in the decane compound of the component (B), one or three functional groups bonded to the four functional groups of the ruthenium atom are alkyl groups having 1 to 25 carbon atoms, and the remaining 3 to 1 functional groups are carbon number 1 ~4 alkoxy group. Here, when two or more alkyl groups are bonded to a ruthenium atom, the alkyl groups may be the same or different. When two or more alkoxy groups are bonded to a ruthenium atom, the alkoxy groups may be the same or different.

Further, the alkyl group having 1 to 25 carbon atoms may be either a linear structure or a branched structure. Further, in the case where the carbon number of the alkoxy group is 3 or 4, it may be either a linear structure or a branched structure.

When it is desired to obtain a high bending resistance, a thermoplastic resin such as a polyester resin can be used as the binder resin as in the conductive paste described in Patent Document 2.

However, when a thermoplastic resin is used as the binder resin as in the conductive paste described in Patent Document 2, there is a problem that it is easily damaged and easily broken.

Therefore, in the case of obtaining a conductive film which is not easily damaged, a thermosetting resin such as a phenol resin can be used as the binder resin. However, when a thermosetting resin is used as the binder resin, it tends to be difficult to obtain bending resistance. The inventors of the present invention have estimated that the reason is that if the cured film of the thermosetting resin is bent, the stress generated between the metal particles and the binder resin becomes large, and the interface between the metal particles and the binder resin is broken. So that peeling occurs.

On the other hand, in the conductive paste of the present invention, the decane compound represented by the above formula (1) is blended as the component (B), and the metal particles in the conductive paste and the binder resin are appropriately formed. The interaction moderates the stress generated between the metal particles and the binder resin, thereby improving the bending resistance of the conductive film. Regarding the reason, the inventors of the present invention and the like presume as follows.

With respect to the decane compound of the component (B), the stanol portion obtained by hydrolysis of the alkoxy group is bonded to the metal particles, and on the other hand, the alkyl group forms an interaction with the binder resin of the component (C). By this interaction, the metal particles can form a strong bond with the binder resin. In the following examples, the Young's modulus of the cured films of Examples 1 to 5 in which the decane compound of the component (B) was added was higher than that of Example 6 in which the decane compound of the component (B) was not added. The inventors of the present invention speculated that the reason was to utilize the binding force of the interaction.

However, the inventors of the present invention have estimated that the binding force by the interaction is weaker than the addition of the glycidyl decane which is usually used to improve the adhesion by the conductive paste (conductive adhesive) described in Patent Document 3. The binding force obtained by a decane coupling agent such as amino decane, mercapto decane, acryl decyl decane or methacryl decyl decane is destroyed at the interface between the metal particles and the binder resin when a certain stress is generated. Relieve stress before.

In order to exhibit the above-described effects, in the decane compound of the component (B), the number of carbon atoms bonded to the alkyl group of the ruthenium atom must be 1 to 25, and the number of carbon atoms of the alkoxy group must be 1 to 4.

It is difficult to obtain a decane compound having a carbon number of 26 or more bonded to an alkyl group of a ruthenium atom, and it is difficult to ensure sufficient fluidity as a conductive paste even when it is available.

Further, when two or more alkyl groups are bonded to a ruthenium atom, the total carbon number of the alkyl group is 30 or less. When the total carbon number of the alkyl group is 31 or more, it becomes difficult to ensure sufficient fluidity as the conductive paste.

In the decane compound of the component (B), the carbon number of the alkyl group bonded to the ruthenium atom is preferably from 1 to 23, more preferably from 1 to 20.

The total carbon number of the alkyl group is preferably 27 or less, more preferably 25 or less.

On the other hand, the number of carbon atoms bonded to the alkoxy group of the ruthenium atom is preferably from 1 to 3, more preferably from 1 to 2.

The decane compound represented by the above formula (1) which constitutes the component (B) is exemplified by Trimethoxy decane, methyl triethoxy decane, dimethyl dimethoxy decane, dimethyl diethoxy decane, ethyl trimethoxy decane, ethyl triethoxy decane, diethyl Dimethoxydecane, diethyldiethoxydecane, propyltrimethoxydecane, propyltriethoxydecane, diisopropyldimethoxydecane, dibutyldiethoxydecane, butyl Trimethoxy decane, butyl triethoxy decane, dibutyl dimethoxy decane, heptyl trimethoxy decane, heptyl triethoxy decane, diheptyl dimethoxy decane, diheptyl Diethoxydecane, hexyltrimethoxydecane, hexyltriethoxydecane, dihexyldimethoxydecane, dihexyldiethoxydecane,octyltrimethoxydecane,octyltriethoxydecane, Dioctyldimethoxydecane, dioctyldiethoxydecane, mercaptotrimethoxydecane, mercaptotriethoxydecane, dimercaptodimethoxydecane, dimercaptodiethoxydecane , mercaptotrimethoxydecane, mercaptotriethoxydecane, dimercaptodimethoxydecane, dimercaptodiethoxydecane, ten Alkyltrimethoxydecane, undecyltriethoxydecane, di-undecyldimethoxydecane, di-undecyldiethoxydecane, dodecyltrimethoxydecane, Dodecyltriethoxydecane, di-dodecyldimethoxydecane, di-dodecyldiethoxydecane,tridecyltrimethoxydecane,tridecyltriethoxy Baseline, di-tridecyldimethoxydecane, ditridecyldiethoxydecane, tetradecyltrimethoxydecane, tetradecyltriethoxydecane,di-tetradecyl Alkyl dimethoxy decane, di-tetradecyl diethoxy decane, pentadecyl trimethoxy decane, cetyl trimethoxy decane, cetyl triethoxy decane, seventeen Alkyltrimethoxydecane, heptadecyltriethoxydecane,octadecyltrimethoxydecane,octadecyltriethoxydecane,nonadecyltrimethoxydecane,dodecyltrimethyl Ethoxy decane and the like.

In the above decane compound, only one type may be used as the component (B), or two or more types may be used in combination as the component (B).

Among the above decane compounds, methyltrimethoxydecane, ethyltrimethoxydecane, propyltrimethoxydecane, and butyltrimethoxy are preferred for the reason of the polarity of the alkyl moiety or the reactivity of the alkoxy moiety. Baseline, hexyltrimethoxydecane, heptyltrimethoxyanthracene Alkane, octyltrimethoxydecane, decyltrimethoxydecane, decyltrimethoxydecane, undecyltrimethoxydecane,dodecyltrimethoxydecane,tridecyltrimethoxydecane, Tetradecyltrimethoxydecane, pentadecyltrimethoxynonane, cetyltrimethoxydecane, heptadecyltrimethoxydecane,octadecyltrimethoxydecane.

In the conductive paste of the present invention, the blending amount of the decane compound of the component (B) is 0.01 to 2.5 parts by mass, more preferably 0.02 to 2.0 parts by mass, per 100 parts by mass of the total of all the components of the conductive paste. .

When the compounding amount of the decane compound of the component (B) satisfies the above range, the metal particles in the conductive paste can form a moderate interaction with the binder resin, and the conductive film formed using the conductive paste has a good effect. Electrical conductivity and excellent bending resistance.

When the amount of the decane compound of the component (B) is less than 0.01 parts by mass based on 100 parts by mass of the total of all the components of the conductive paste, the amount of the decane compound is insufficient, so that the conductive paste cannot be used. The metal particles form a modest interaction with the binder resin. Therefore, the conductivity of the formed conductive film is lowered, and the change (decrease) in conductivity before and after the bending becomes large.

On the other hand, when the blending amount of the decane compound of the component (B) exceeds 2.5 parts by mass based on 100 parts by mass of the total of all the components of the conductive paste, the decane compound is present at the interface between the metal particles at the time of heat curing. The conduction between the metal particles is hindered, and as a result, the conductivity of the formed conductive film is lowered.

(C) Adhesive resin

As described above, in the conductive paste which requires a high hardness of the cured film, a thermosetting resin can be used as the binder resin.

In the conductive paste of the present invention, a binder resin containing a thermosetting resin containing formaldehyde as a component is used as the component (C). The reason for this is that the thermosetting resin having formaldehyde as a component has a large shrinkage upon heat curing, and the force for pressing the metal particles becomes strong, so that it is easy to obtain high conductivity and high film hardness. Again, the reason is: In particular, when copper fine particles are used as the metal particles, the reduction of the surface of the copper particles can be suppressed by the reduction of the methylol group produced by formaldehyde, and the hardening shrinkage can be appropriately performed to ensure the contact of the copper particles with each other.

The thermosetting resin containing formaldehyde as a component may, for example, be a phenol resin, a melamine resin, a xylene resin or a urea resin. Among them, a phenol resin is preferred in terms of the degree of reduction and hardening shrinkage of the methylol group. If the hardening shrinkage is too large, the stress that is not required to accumulate in the conductive film is a cause of mechanical damage. If the hardening shrinkage is too small, the metal particles cannot be sufficiently ensured to contact each other.

In the conductive paste of the present invention, the amount of the binder resin of the component (C) may be appropriately adjusted according to the ratio of the volume of the component (A) (for example, copper particles) to the volume of the void portion between the metal particles. The total amount is preferably 5 to 25 parts by mass, more preferably 10 to 20 parts by mass, based on 100 parts by mass of the total of all the components of the conductive paste. When the amount is 5 parts by mass or more, the portion where the binder resin is bonded to the surface of the metal particles is increased, the bending resistance is improved, and the flow characteristics of the conductive paste are improved. When the amount is 25 parts by mass or less, the amount of the metal portion in the conductor is increased, and the contact between the metal particles can be sufficiently ensured. Therefore, the conductivity and the bending resistance of the conductive film formed using the conductive paste are improved.

(D) Other ingredients

In addition to the components (A) to (C), the conductive paste of the present invention may contain a solvent or various additives (a leveling agent, a viscosity modifier, etc.) as needed within the scope of the effects of the present invention. In particular, in order to obtain a paste having moderate fluidity, it is preferred to contain a solvent which can dissolve the thermosetting resin.

As the solvent, for example, cyclohexanone, cyclohexanol, rosinol, ethylene glycol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether B can be used. Acid ester, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate. The amount of the solvent contained in the conductive paste is preferably relative to the viewpoint of the moderate viscosity range of the paste for printing. The total amount of all the components of the electric paste is 100 to 40 parts by mass.

The conductive paste can be obtained by mixing the components of the above (A) to (C) and other components such as the above-mentioned solvent as necessary. When the components (A) to (C) described above are mixed, the mixture can be mixed while being heated without causing curing of the thermosetting resin or volatilization of the solvent.

The temperature during mixing and stirring is preferably set to 10 to 50 °C. More preferably, it is set to 20 to 30 °C. When the conductive paste is prepared, the viscosity of the paste can be sufficiently lowered by heating to a temperature of 10 ° C or higher, whereby the stirring can be smoothly and sufficiently performed. On the other hand, when the temperature at the time of mixing and stirring exceeds 50 ° C, there is a possibility that the resin is hardened in the paste or the particles are fused to each other. Further, in order to prevent oxidation of the metal particles during mixing, it is preferred to carry out the mixing in a vessel substituted with an inert gas.

In the conductive paste of the present invention described above, the metal particles containing the (A) component having a volume resistivity of 10 μΩ···cm or less and having an average particle diameter of 0.5 to 15 μm and the component (B) have the above formula ( 1) The decane compound and the component (C) include a binder resin of a thermosetting resin containing formaldehyde as a component. Therefore, the conductive film formed of the conductive paste has a high film hardness and is electrically conductive. Excellent in properties and resistance to bending.

<Substrate with conductive film>

The substrate with a conductive film of the present invention comprises a substrate, and a conductive film formed by applying the above-described conductive paste of the present invention to the substrate and curing the conductive paste.

As described above, the conductive film formed by using the conductive paste of the present invention has excellent conductivity and excellent bending resistance. Therefore, a flexible film is preferable as the substrate body. Examples of the flexible film include a plastic substrate (for example, a polyimide substrate or a polyester substrate), and a substrate including a fiber-reinforced composite material (for example, a glass fiber-reinforced resin substrate).

Examples of the coating method of the conductive paste include a screen printing method, a roll coating method, an air knife coating method, a knife coating method, a bar coating method, a gravure coating method, a die coating method, and a swash plate type. A known method such as a coating method. Among these, a screen printing method is preferred.

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

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

The thickness of the conductive film formed on the substrate is preferably from 1 to 200 μm, more preferably from 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 50 μΩcm or less. When the specific resistance of the conductive film exceeds 50 μΩcm, it may become difficult to use it as an electric conductor for an electronic device.

Further, the amount of change (increased) of the specific resistance before and after bending (the number of times of bending is 5 times) measured in the order described in the following examples is preferably 400% or less, more preferably 200% or less, and further It is preferably 150% or less.

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited to the examples. Examples 1 to 5 are examples, and example 6 is a comparative example. Further, the average particle diameter of the metal particles (copper particles), the thickness of the conductive film, and the specific resistance were measured using the apparatus shown below.

(The average particle size)

Copper particles are used as the metal particles. The particle size of the copper particles is measured by the Feret diameter of 100 particles randomly selected from the SEM images obtained by SEM (manufactured by Hitachi High-Technologies Corporation, S-4300), and the Feret diameter in each copper particle becomes When the radial value of the maximum value is the long axis and the axis orthogonal to the long axis is the short axis, the average value of the Feret diameter in the long axis direction and the Feret path in the short axis direction is calculated ((long axis direction) Feret diameter + short axis direction Feret Trail)/2). Then, the average value (average particle diameter) of the particle diameters was determined by averaging (quantitatively averaging) the particle diameters of the calculated copper particles.

(thickness of conductive film)

The thickness of the conductive film was measured using DEKTAK3 (manufactured by Veeco Metrology Group Co., Ltd.).

(specific resistance of conductive film)

The specific resistance of the conductive film was measured using a four-probe volume resistivity meter (manufactured by Mitsubishi Petrochemical Co., Ltd., model: loresta IP MCP-T250).

example 1

After adding 3.0 g of formic acid and 9.0 g of a 50% by mass aqueous solution of hypophosphite to a glass beaker, the beaker was placed in a water bath and kept at 40 °C. To the beaker, 5.0 g of copper particles (manufactured by Mitsui Mining Co., Ltd., trade name: 1400YP) having an average particle diameter of 3 μm was slowly added to the beaker, and the mixture was stirred for 30 minutes to obtain a copper dispersion.

The precipitate was collected from the obtained copper dispersion using a centrifugal separator at a number of revolutions of 3000 rpm for 10 minutes. The precipitate was dispersed in 30 g of distilled water, and the aggregate was again precipitated by centrifugation, and the precipitate was separated. Thereafter, the obtained precipitate was heated at 80 ° C for 60 minutes under a reduced pressure of -35 kPa, and the residual water was volatilized and slowly removed to obtain copper particles (A) whose surface was surface-modified.

The average value of the particle diameter of the copper particles after surface modification did not change and was 3 μm. Further, in the other examples shown below, the average value of the particle diameters of the surface-modified copper particles did not change.

Then, 12 g of the obtained surface-modified copper particles (A) was added to dissolve 3.7 g of a phenol resin (manufactured by QunRong Chemical Co., Ltd., trade name: Resitop PL6220, all the same in the following examples) as the component (C). A resin solution obtained from 4.3 g of ethylene glycol monobutyl ether acetate, and 0.030 g of methyltrimethoxydecane as a component (B) was placed in a mortar together with the mixture, and allowed to stand at room temperature. Mix to obtain a copper paste. Furthermore, the adjustment of component (B) The blending amount is 0.25 parts by mass based on 100 parts by mass of the total components of the copper paste, and the blending amount of the component (C) is 16 parts by mass based on 100 parts by mass of the total of all the components of the copper paste.

Example 2

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 was added to a resin obtained by dissolving 3.7 g of the phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. Solution. Further, 0.030 g of propyltrimethoxydecane as the component (B) was placed in a mortar together with the mixture, and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) is 0.25 parts by mass based on 100 parts by mass of the total components of the copper paste, and the blending amount of the component (C) is 16 parts by mass based on 100 parts by mass of the total components of the copper paste. Parts by mass.

Example 3

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 was added to a resin obtained by dissolving 3.7 g of the phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. Further, 0.030 g of dodecyltrimethoxydecane as the component (B) was placed in a mortar together with the mixture, and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) is 0.25 parts by mass based on 100 parts by mass of the total components of the copper paste, and the blending amount of the component (C) is 16 parts by mass based on 100 parts by mass of the total components of the copper paste. Parts by mass.

Example 4

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 was added to a resin obtained by dissolving 3.7 g of the phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. Further, 0.060 g of dodecyltrimethoxydecane as the component (B) was placed in a mortar together with the mixture, and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) is 0.50 parts by mass based on 100 parts by mass of the total components of the copper paste, and the blending amount of the component (C) is 16 parts by mass based on 100 parts by mass of the total components of the copper paste. Parts by mass.

Example 5

12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 was added to a resin obtained by dissolving 3.7 g of the phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. Further, 0.030 g of octadecyltrimethoxydecane as the component (B) was placed in a mortar together with the mixture, and mixed at room temperature to obtain a copper paste. In addition, the blending amount of the component (B) is 0.25 parts by mass based on 100 parts by mass of the total components of the copper paste, and the blending amount of the component (C) is 16 parts by mass based on 100 parts by mass of the total components of the copper paste. Parts by mass.

Example 6

In the same manner as in Example 1, except that 12 g of the surface-modified copper particles (A) obtained in the same manner as in Example 1 was added without adding the decane compound of the component (B), copper was obtained at room temperature in the same manner as in Example 1. Paste.

Then, the copper pastes obtained in Examples 1 to 6 were respectively coated on a 75 μm thick PET (polyethylene terephthalate), and heated at 150 ° C for 30 minutes to make (C) The phenol resin of the component was hardened to form a conductive film having a thickness of 15 μm. Then, the Young's modulus (unit GPa) of the obtained conductive film was measured by a micro hardness tester (manufactured by Fischer Co., Ltd., trade name: PICODENTOR HM500).

Further, the resistance value of the obtained conductive film was measured using a resistance meter (manufactured by Keithley Co., Ltd., trade name: Milliohm HiTester), and the specific resistance (volume resistivity; unit μΩcm) was measured. Further, the conductive film was repeatedly subjected to the following bending operation five times to measure the amount of change in the specific resistance, that is, the conductor was wound inward in a cylinder having a radius of 1 mm, and then wound outward, and then spread.

As is clear from Table 1, it is known that the copper particles having an average particle diameter of 0.5 to 15 μm and the total amount of 100 parts by mass of all the components of the conductive paste are 0.01 to 2.5 parts by mass as the component (B). In the conductive pastes of Examples 1 to 5 of the decane compound represented by the above formula (1), the conductive paste obtained by applying the conductive paste to the substrate and having a specific resistance is low, and is 50 μΩcm. the following. Moreover, the change (increase) in the specific resistance before and after the bending is also suppressed.

On the other hand, in Example 6 in which the decane compound of the component (B) was not blended, the change (increase) in the specific resistance due to the bending of the conductive film produced using the conductive paste was large.

In addition, the total amount of 100 parts by mass of all the components of the conductive paste is 0.01 to 2.5 parts by mass, which is represented by the above formula (1), in comparison with the example 6 of the decane compound in which the component (B) is not blended. In Examples 1 to 5 of the decane compound, the Young's modulus of the cured conductive film became high. It can be considered that the increase in the Young's modulus contributes to the suppression of the change (increase) in the specific resistance before and after the bending.

The present invention has been described in detail with reference to the specific embodiments thereof, and it is understood that various changes and modifications may be made without departing from the spirit and scope of the invention.

The present application is based on Japanese Patent Application No. 2013-186951, filed on Sep. 2010, the content of

[Industrial availability]

The conductive paste of the present invention can be applied to various uses, for example, it can be applied to printing The formation and repair of wiring patterns in wiring boards, etc., interlayer wiring in semiconductor packages, and bonding of printed wiring boards and electronic components.

Claims (6)

A conductive paste comprising (A) metal particles having a volume resistance value of 10 μΩ··cm or less and an average particle diameter of 0.5 to 15 μm, and (B) by R _x —Si—OR′ _4-x The decane compound (wherein x is an integer of 1 to 3, and R is an alkyl group having a carbon number of 1 to 25 as a condition of a total carbon number of 1 to 3 alkyl groups of 30 or less, OR' And a (C) alkoxy group having a carbon number of 1 to 4, and (C) a binder resin containing a thermosetting resin containing formaldehyde as a component, and a total of all the components of the conductive paste 100 parts by mass of the binder resin containing the component (C), 5 to 25 parts by mass, and 0.01 to 2.5 parts by mass of the decane compound containing the component (B). The conductive paste of claim 1, wherein the metal particles of the component (A) are copper particles or silver particles having an average particle diameter of 0.5 to 15 μm. The conductive paste according to claim 1 or 2, wherein the decane having the alkyl group having 1 to 25 carbon atoms of the component (B) is selected from the group consisting of methyltrimethoxydecane, ethyltrimethoxydecane, and propyl. Trimethoxy decane, butyl trimethoxy decane, hexyl trimethoxy decane, heptyl trimethoxy decane, octyl trimethoxy decane, decyl trimethoxy decane, decyl trimethoxy decane, undecyl Trimethoxydecane, dodecyltrimethoxydecane, tridecyltrimethoxydecane, tetradecyltrimethoxydecane, pentadecyltrimethoxynonane, cetyltrimethoxydecane, One or more of the group consisting of heptadecyltrimethoxydecane and octadecyltrimethoxydecane. The conductive paste according to any one of claims 1 to 3, wherein the binder resin of the component (C) is selected from the group consisting of a phenol resin, a melamine resin, a xylene resin, and a urea resin. the above. A substrate with a conductive film, characterized in that it has a coating on a substrate as requested The conductive paste of any one of items 1 to 4 which is hardened and formed. The substrate of the conductive film of claim 5, wherein the substrate is a flexible film.