CN103262173A - Conductive paste, conductive film-attached base material using the conductive paste, and method for manufacturing conductive film-attached base material - Google Patents

Abstract

Provided is a conductive paste, with which a conductive film that suppresses formation of an oxide film and can maintain a low volume resistivity for a long period of time can be formed. The conductive paste contains: copper particles (A) having a surface oxygen concentration ratio (O/Cu) of 0.5 or less, said surface oxygen concentration ratio being obtained by means of X-ray photoelectron spectroscopy; a chelating agent (B), which is composed of a compound having a stability constant (logKCu) of 5-15 with copper ions at 25 DEG C and an ion strength of 0.1 mol/L; and a thermosetting resin (C).

Description

Conductive paste and used the base material that has conducting film of this conductive paste and the manufacture method that has the base material of conducting film

Technical field

The present invention relates to conductive paste and used the base material that has conducting film of this conductive paste and the manufacture method that has the base material of conducting film, particularly relate to the repressed conductive paste of oxidation of metal ingredient and used the base material that has conducting film of this conductive paste and the manufacture method that has the base material of conducting film.

Background technology

In the past, the known method of in the formation of electronic component, printing distributing board distribution conductors such as (printing substrates), using conductive paste.Wherein, for example the manufacturing of printing substrate is to be coated with conductive paste with desired pattern form on the insulating properties substrate that is made of glass, pottery etc., calcines, and forms Wiring pattern and carries out.

As conductive paste, consider that from the viewpoint of guaranteeing high conductivity main application is the silver paste of principal component with silver (Ag).But, if silver paste is switched on, take place easily then that silver atoms carries out ionization and by electric field attracts and mobile ion migration (electrolysis of silver) under hot and humid environment.If the migration of Wiring pattern generation ion then may occur in wiring closet and produce unfavorable conditions such as short circuit, hinder the reliability of wiring substrate.

Consider from the viewpoint of the reliability that improves electronic equipment, wiring substrate, proposed to replace silver paste and use copper cream as the technology of conductive paste.Because copper cream is difficult to take place transport phenomena, so can improve the connection reliability of circuit.

But therefore the general easy oxidation of copper is placed in the atmosphere under the environment of high humility and since with atmosphere in the reaction of moisture, oxygen etc., generate cupric oxide easily.Therefore, there is the problem that specific insulation raises easily owing to the influence of oxide film thereon in the conducting film that the calcining of copper cream is formed.

In order to solve such problem, adopt the technology of utilizing the copper powders may that cooperates in the wet type reducing process manufactured copper cream.For example, in the patent documentation 1, the surface treatment method that the aqueous solution that uses the alkali metal salt that contains acid, reducing agent and the aliphatic acid of carbon number more than 8 is simultaneously handled the conducting powder of the conducting powder that is made of copper or copper alloy is disclosed.

In addition, disclose in the patent documentation 2 that to contain the copper that copper powders may and adhesive for paint resin and antioxidant form be the conductive coating paint composition.In addition, disclose use in salicylic acid and derivative or the BTA carboxylic acid hydrazides at least a kind as this antioxidant.

But, even actual conditions are to utilize the technology of above-mentioned citing document also can't substantially improve the problem that conductive paste that the distribution conductor uses rises because of the specific insulation that forms oxide film thereon and cause.

Patent documentation 1: TOHKEMY 2007-184143 communique

Patent documentation 2: Japanese kokai publication hei 1-158081 communique

Summary of the invention

The present invention carries out in order to solve above-mentioned problem.That is, the purpose of this invention is to provide the formation that can suppress oxide film thereon, can form the conductive paste of conducting film that can the low specific insulation of long term maintenance.In addition, the purpose of this invention is to provide the substrate that has conducting film with the conducting film that has used above-mentioned conductive paste.

Namely, conductive paste of the present invention is characterised in that, contain copper particle (A), chelating agent (B) and thermosetting resin (C), the surface oxygen concentration that utilizes the x-ray photoelectron optical spectroscopy to obtain of described copper particle (A) is below 0.5 than O/Cu, and described chelating agent (B) is by under 25 ℃, ionic strength 0.1mol/L condition and stability constant logK copper ion _CuBe that 5～15 compound constitutes.

Should illustrate, below also with under 25 ℃, ionic strength 0.1mol/L condition and stability constant logK copper ion _CuSimply be expressed as " with the stable number of degrees logK of copper ion _Cu".

In above-mentioned conductive paste, it is to handle the surface modification copper particle that obtains through reduction in the decentralized medium below 3 that above-mentioned copper particle (A) is preferably in the pH value.In addition, above-mentioned copper particle (A) can be will have metallic copper particle and hydrogenation copper particulate the heating of copper compound particle and described hydrogenation copper particulate become the metallic copper particulate and the composition metal copper particle that forms, the average primary particle of described metallic copper particle directly is 0.3～20 μ m, described hydrogenation copper particle coagulation and be attached to described metallic copper particle surface and average primary particle directly is 1～20nm.

As the pH value conditioning agent of above-mentioned decentralized medium, the preferred use is selected from least a in formic acid, citric acid, maleic acid, malonic acid, acetic acid, propionic acid, sulfuric acid, nitric acid, the hydrochloric acid.In addition, the pH conditioning agent of the water-soluble copper compound solution that uses in the formation as above-mentioned hydrogenation copper particulate, the preferred use is selected from least a in formic acid, citric acid, maleic acid, malonic acid, acetic acid, propionic acid, sulfuric acid, nitric acid, the hydrochloric acid.

The functional group (b) that above-mentioned chelating agent (B) preferably contains the functional group (a) of nitrogen-atoms and contains the atom with lone electron pair beyond the nitrogen-atoms is disposed at the aromatic compound at the ortho position of aromatic rings, and the atom with lone electron pair beyond above-mentioned nitrogen-atoms and the above-mentioned nitrogen-atoms passes through two or three atoms and bonding.In addition, the above-mentioned functional group (b) of containing the nitrogen-atoms atom with lone electron pair in addition is preferably hydroxyl or carboxyl.In addition, the atom with lone electron pair beyond preferred above-mentioned nitrogen-atoms and the above-mentioned nitrogen-atoms is by two or three carbon atoms and bonding.In addition, above-mentioned chelating agent (B) is preferably the compound that is selected from salicylhydroxamic acid, salicylaldoxime, o-aminophenol, the salicylic acid.

Above-mentioned thermosetting resin (C) is preferably and is selected from phenolic resins, diallyl phthalate resin, unsaturated alkyd resin, epoxy resin, polyurethane resin, span and comes according at least a resin in a cyanate resin, organic siliconresin, acrylic resin, melmac, the urea resin.

Preferably with respect to above-mentioned copper particle (A) 100 mass parts, the amount of above-mentioned chelating agent (B) is 0.01～1 mass parts to above-mentioned conductive paste.In addition, preferably with respect to above-mentioned copper particle (A) 100 mass parts, the amount of above-mentioned thermosetting resin (C) is 5～50 mass parts to above-mentioned conductive paste.

The base material that has conducting film of the present invention is characterised in that, has the conducting film that the conductive paste of the invention described above of making is solidified to form at base material and forms.In the above-mentioned base material that has a conducting film, the specific insulation of above-mentioned conducting film is preferably 1.0 * 10 ^-4Below the Ω cm.

The manufacture method that has the base material of conducting film of the present invention is characterised in that, behind the conductive paste of base material coating the invention described above, makes this conductive paste be solidified to form conducting film.

According to the present invention, though can make can form the formation that under the environment of high humility, also can suppress cupric oxide, can the low specific insulation of long term maintenance the conductive paste of conducting film.In addition, according to the present invention, by using such conductive paste, can be made as the reliability height of wiring substrate etc., in addition because forming the repressed substrate that has conducting film of rising of the volume change that oxide film thereon causes.

Description of drawings

Fig. 1 is the key diagram of the schematic construction example of the device that uses in the enforcement handled of the wet type reduction of expression copper particle.

Fig. 2 is the profile schema diagram of an example of the expression base material that has a conducting film of the present invention.

Embodiment

Below, the present invention is described in detail.

Conductive paste of the present invention is characterised in that and contains copper particle (A), chelating agent (B) and thermosetting resin (C), the surface oxygen concentration that utilizes the x-ray photoelectron optical spectroscopy to obtain of described copper particle (A) is below 0.5 than O/Cu, and described chelating agent (B) is by under 25 ℃, ionic strength 0.1mol/L condition and stability constant logK copper ion _CuBe that 5～15 compound constitutes.

According to the present invention, by cooperating under 25 ℃, ionic strength 0.1mol/L condition and stability constant logK copper ion _CuAt the compound of prescribed limit as chelating agent (B), thereby can reduce with atmosphere in the amount of copper ion of contained reactions such as oxygen.Therefore, can make the repressed conductive paste of formation of cupric oxide.For the conducting film that is formed by such conductive paste, being difficult to form with the cupric oxide is the oxide film thereon of principal component, so even can make in the rising of the environment lower volume resistivity of the high humility also repressed base material that has conducting film.

Copper particle (A) is the material that becomes the conductive compositions of conductive paste, and the surface oxygen concentration that utilizes the x-ray photoelectron optical spectroscopy to obtain is below 0.5 than O/Cu.The surface oxygen concentration that below will utilize the x-ray photoelectron optical spectroscopy to obtain is expressed as " surface oxygen concentration is than O/Cu " than O/Cu is simple.

" surface oxygen concentration is than O/Cu " represented with respect to the ratio of surperficial copper concentration (atom %) by the surface oxygen concentration (atom %) of the copper particle of utilizing the x-ray photoelectron spectrum analysis to measure.In this manual, " surperficial copper concentration (atom %) " and " surface oxygen concentration (atom %) " is respectively the measured value to carrying out x-ray photoelectron spectrum analysis to the center to the zone, particle top layer of the scope of the degree of depth of about 3nm from the copper particle surface and obtaining.Scope to the degree of depth of about 3nm is fully to grasp the scope of the surface state of copper particle by the concentration determination of each composition is carried out in the particle zone of this scope to the center from the copper particle surface.

If the surface oxygen concentration of copper particle (A) surpasses 0.5 than O/Cu, then the amount of the cupric oxide on copper particle (A) surface is too much, and when making conducting film, interparticle contact resistance is big, and specific insulation may uprise.Be copper particle (A) below 0.5 by using surface oxygen concentration than O/Cu, can reduce the contact resistance between copper particle, can improve the conductivity when making conducting film.The surface oxygen concentration of copper particle (A) is preferably below 0.3 than O/Cu.

In addition, contained oxygen concentration is below the 700ppm in copper particle (A) the preferred particle integral body.Contained oxygen concentration for example can utilize oxymeter to measure in the copper particle.

As copper particle (A), so long as surface oxygen concentration is that copper particle below 0.5 just can be used various copper particle than O/Cu.Copper particle (A) can be the metallic copper particle, also can be hydrogenation copper particulate or metallic copper particulate that hydrogenation copper particulate heating is obtained (below be also referred to as the copper particulate).In addition, as copper particle (A), can be the compound particle of the compound form of these metallic copper particles and copper particulate.As compound particle, for example can enumerate the compound particle of form that the copper particulate adheres to or be incorporated into the surface of metallic copper particle.For compound particle, detailed content is narrated in the back.

The average grain diameter of copper particle (A) is preferably 0.01～20 μ m.The average grain diameter of copper particle (A) can be according to the shape of copper particle (A) and is suitably adjusted in the scope of 0.01～20 μ m.If the average grain diameter of copper particle (A) is more than the 0.01 μ m, the flow behavior that then contains the conductive paste of this copper particle becomes good.In addition, if the average grain diameter of copper particle (A) is below the 20 μ m, then utilize the conductive paste that contains this copper particle to make fine distribution easily.

Copper particle (A) contains under the situation of metallic copper particle, and its average grain diameter (average primary particle diameter) is preferably 0.3～20 μ m.In addition, under the situation that copper particle (A) only is made of the copper particulate, the average grain diameter of its aggregated particle is preferably 0.01～1 μ m, more preferably 0.02～0.4 μ m.

It is 0.3 μ m when above that copper particle (A) contains under the situation of metallic copper particle its average grain diameter (average primary particle diameter), and the flow behavior that contains the conductive paste of this copper particle becomes good.In addition, the average grain diameter of its aggregated particle is 0.01 μ m when above under the situation that copper particle (A) only is made of the copper particulate, and the flow behavior that contains the conductive paste of this copper particle becomes good.

In addition, it is 20 μ m when following that copper particle (A) contains under the situation of metallic copper particle its average grain diameter (average primary particle diameter), utilizes the conductive paste that contains this copper particle to make fine distribution easily.In addition, the average grain diameter of its aggregated particle is 1 μ m when following under the situation that copper particle (A) only is made of the copper particulate, utilizes the conductive paste that contains this copper particle to make fine distribution easily.

Be copper particle (A) below 0.5 as surface oxygen concentration than O/Cu, for example can preferably use following copper particle (A1)～(A5).

(A1) be that metallic copper particle and its average primary particle diameter are the metallic copper particle of 0.3～20 μ m.

(A2) has the copper compound particle of metallic copper particle and hydrogenation copper particulate, described metallic copper particle is that metallic copper particle and its average primary particle diameter are 0.3～20 μ m, and described hydrogenation copper particulate is to be attached to the hydrogenation copper particulate of above-mentioned metallic copper particle surface and the average grain diameter of its aggregated particle is 20～400nm.

(A3) be that the average grain diameter of hydrogenation copper particulate and its aggregated particle is the hydrogenation copper particulate of 10nm～1 μ m.

(A4) has the composition metal copper particle of metallic copper particle and metallic copper particulate, described metallic copper particle is that metallic copper particle and its average primary particle diameter are 0.3～20 μ m, described metallic copper particulate be will be attached to the metallic copper particulate that forms of the hydrogenation copper particulate heating of above-mentioned metallic copper particle surface and the average grain diameter of its aggregated particle be 20～400nm.

(A5) be that the average grain diameter of metallic copper particulate and its aggregated particle is the metallic copper particulate of 10nm～1 μ m.

Should illustrate that composition metal copper particle (A4) is the composition metal copper particle that the hydrogenation copper particulate of copper compound particle (A2) is become the metallic copper particulate by heat treated.In addition, metallic copper particulate (A5) is the metallic copper particulate that hydrogenation copper particulate (A3) is become by heat treated.

In this manual, average grain diameter is following obtains.That is, be the Feret footpath of measuring 100 particles from scanning electron microscope (below be designated as " SEM ") image, selecting at random for the average primary particle diameter of metallic copper particle, these particle diameters are averaged calculate.

In addition, the average grain diameter of the aggregated particle that is made of the copper particulate is to measure the Feret footpath of 100 particles selecting at random from transmission electron microscope (below be designated as " TEM ") image, these particle diameters is averaged calculate.

In addition, for example as copper compound particle (A2), for containing as the copper particle of metallic copper particle and being attached under the situation of compound particle of hydrogenation copper particulate on this copper particle surface, utilize SEM that this compound particle integral body is observed, measure the Feret footpath of the particle integral body that also comprises the copper particulate, the particle diameter that obtains is averaged and calculates.

As such copper particle (A), for example can enumerate the copper particle surface reduced and handle " the composition metal copper particle " that at least a portion that " the surface modification copper particle " form or metallic copper particulate be attached to the metallic copper particle surface forms.

" surface modification copper particle " among the present invention reduced the copper particle surface to handle and obtained in the pH value is decentralized medium below 3." surface modification copper particle " for example can following by having (1)～(3) operation the wet type reducing process make, (1) copper particle is scattered in decentralized medium and forms the operation of " copper dispersion liquid ", (2) the pH value of copper dispersion liquid is adjusted to operation below the setting, (3) add the operation of reducing agent in the copper dispersion liquid.

The surface modification copper particle that obtains by above-mentioned (1)～(3) operation mainly is made of the metallic copper particle.The average primary particle diameter of surface modification copper particle is preferably 0.3～20 μ m(metallic copper particle (A1)).In the surface modification copper particle, if its average primary particle diameter is more than the 0.3 μ m, the flow behavior that then contains the conductive paste of this copper particle becomes good.In addition, if the average primary particle diameter of surface modification copper particle is below the 20 μ m, then utilize the conductive paste that contains this copper particle to make fine distribution easily.

Below, operation (1)～(3) of making the surface modification copper particle are described.

(1) making of copper dispersion liquid

The copper particle that is scattered in the copper dispersion liquid can be used as the normally used copper particle of conductive paste.The shape of particle that is scattered in the copper particle of copper dispersion liquid can be for spherical, also can be for tabular.

The average grain diameter that is scattered in the copper particle of copper dispersion liquid is preferably 0.3～20 μ m, more preferably 1～10 μ m.If the average grain diameter of copper particle is less than 0.3 μ m, then the flowability of conductive paste may reduce.On the other hand, if the average grain diameter of copper particle surpasses 20 μ m, then be difficult to make fine distribution with the conductive paste that obtains.Be 0.3～20 μ m by the average grain diameter that makes copper particle, can form good fluidity and be fit to make the conductive paste of fine distribution.

Should illustrate that the average grain diameter of copper particle is to measure the Feret footpath of 100 metallic copper particles selecting at random from the SEM image, calculates its mean value and obtains.

The copper dispersion liquid can be made above-mentioned copper particle Powdered back input decentralized medium and obtain.The concentration of the copper particle of copper dispersion liquid is preferably 0.1～50 quality %.If the concentration of copper particle is less than 0.1 quality %, then contained decentralized medium quantitative change gets too much in the copper dispersion liquid, possibly production efficiency can't be maintained sufficient level.On the other hand, if the concentration of copper particle surpasses 50 quality %, then the influence of particle cohesion each other becomes excessive, and the yield of surface modification copper particle may descend.The concentration of the copper particle by making the copper dispersion liquid can obtain the surface modification copper particle with high yield in the scope of 0.1～50 quality %.

As the decentralized medium of copper particle dispersion liquid, so long as can disperse the medium of copper particle, just be not particularly limited, can preferably use the decentralized medium with high polarity.As the decentralized medium of high polarity, for example can make alcohols such as water, methyl alcohol, ethanol, 2-propyl alcohol, glycols such as ethylene glycol, and the blending agent that they are mixed etc.As the decentralized medium of high polarity, particularly can preferably make water.

The copper particle that is scattered in decentralized medium can be with surface conditioning agent particle surface have been carried out the surface-treated copper particle for the oxidation that prevents particle surface.As surface conditioning agent, can use long-chain carboxylic acids such as stearic acid, palmitic acid, myristic acid.

When using the long-chain carboxylic acid as surface conditioning agent, be scattered in decentralized medium after preferably removing long-chain carboxylic acid's (surface conditioning agent) from the copper particle surface.After removing long-chain carboxylic acid's (surface conditioning agent) from the copper particle surface, be scattered in decentralized medium, can successfully carry out reduction reaction described later.

In addition, when using the long-chain carboxylic acid as surface conditioning agent, copper particle directly can also be supplied with reduction and be handled.Removing of long-chain carboxylic acid can be undertaken by for example using the methods such as cleaning of acid.

In addition, in order to improve the dispersiveness of copper particle in decentralized medium, preferably copper particle is carried out pre-treatment.By carrying out pre-treatment, the copper particle surface is by hydrophilyization.Therefore, can improve the dispersiveness of copper particle in the contour polarity decentralized medium of water.

As pretreating reagent, can preferably use aliphatic monocarboxylic acid class and aliphatic polycarboxylic acid classes such as aliphatic monocarboxylic acid below 6 of carbon number for example, aliphatic hydroxyl monocarboxylic acid, aliphatic amino acid.As the aliphatic polycarboxylic acid class, for example can enumerate aliphatic polycarboxylic acid, the aliphatic hydroxyl polycarboxylic acid of carbon number below 10.The more preferably aliphatic polycarboxylic acid class of carbon number below 8.As pretreating reagent, particularly, can preferably use glycine, alanine, citric acid, malic acid, maleic acid, malonic acid etc.

Preferably in the copper dispersion liquid that as above obtains, add dispersant.As dispersant, can use the water miscible all cpds that copper particle is had adsorptivity.

As dispersant, particularly, can use for example water-soluble high-molecular compounds such as polyvinyl alcohol, polyacrylic acid, PVP, hydroxypropyl cellulose, propyl cellulose, ethyl cellulose, ethylenediamine tetra-acetic acid, imido-acetic acid (イ ミ ノ ジ two jealous woman acid) isochela combination compound etc.

The amount of the surface conditioning agent that supporting after above-mentioned each processing of process exists in the copper particle surface, pretreating reagent, dispersant is 0.1～10 quality % with respect to copper particle preferably.

The processing that utilizes the copper particle that pretreating reagent, dispersant carry out is to add pretreating reagent etc. and add copper particle in the solution that obtains and stir in the water equal solvent.In addition, can in this solution, carry out in the mode that supports pretreating reagent etc. on the copper particle surface.

In order to improve processing speed, when carrying out pre-treatment, carry out while preferably heat the copper dispersion liquid.As heating-up temperature, preferably under the temperature more than 50 ℃, below the boiling point of decentralized medium such as water, carry out.Should illustrate that when having added surface conditioning agent, dispersants such as carboxylic acid in decentralized medium, heating-up temperature preferably is heated to below the boiling point of these compounds.

The time of carrying out heat treated is preferably 5 minutes～and 3 hours.If heating time is less than 5 minutes, the effect of the processing speed that then might fully be improved.On the other hand, 3 hours Di carry out heat treated even if surpass, also might excessively raise by cost, not preferred from economic aspect.

Should illustrate, when carrying out pre-treatment etc., in order to prevent the oxidation on copper particle surface, preferably will replace with inert gases such as nitrogen, argon gas in the container handling.After the pre-treatment, desolventizing, water etc. cleans as required, thereby can access the copper particle that is scattered in dispersion liquid.

(2) adjusting of the pH value of copper dispersion liquid

Regulate the pH value of the copper dispersion liquid that obtains in above-mentioned (1).The adjusting of pH value can be added the pH conditioning agent and carry out in the copper dispersion liquid.

PH conditioning agent as the copper dispersion liquid can use acid.As the pH conditioning agent of copper dispersion liquid, can preferably use for example carboxylic acids such as formic acid, citric acid, maleic acid, malonic acid, acetic acid, propionic acid, inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid.As carboxylic acid, can use the compound identical with the above-mentioned carboxylic acid that uses as pretreating reagent.

In the middle of these, as the pH conditioning agent, can preferably use carboxylic acid.By using carboxylic acid as the pH conditioning agent, carboxylic acid is adsorbed in the copper particle surface, remains in the surface of the surface modification copper particle after reduction is handled and protects particle surface, can suppress the oxidation reaction of copper.

Particularly formic acid possesses aldehyde radical with reproducibility and (CHO), therefore can remain in the copper particle surface through surface modification, can suppress the carrying out of the oxidation of particle surface.Cooperated the conductive paste of such copper particle by use, can form and be difficult to the conducting film that forms oxide film thereon, suppressed the rising of specific insulation.Should illustrate, as the pH conditioning agent, might not be limited to sour composition.When for example the pH value of dispersion liquid is low, also can use alkali as the pH conditioning agent.

The pH value of copper dispersion liquid is preferably below 3.Be below 3 by the pH value that makes the copper dispersion liquid, in the reduction treatment process of back, can successfully carry out the removing of oxide-film of particle surface, can reduce the surface oxygen concentration of resulting surface modification copper particle.If the pH value of dispersion liquid surpasses 3, the effect of the oxide-film that is formed at the copper particle surface of then can not fully being removed possibly can't fully reduce the oxygen concentration on copper particle surface.On the other hand, the pH value of dispersion liquid is preferably more than 0.5.If the pH value of dispersion liquid is less than 0.5, the then excessive stripping of copper ion may be difficult to successfully carry out the surface modification of copper particle.The pH value of dispersion liquid more preferably 0.5～2.Should illustrate that the pH value of dispersion liquid is 3 when following, can directly reduce processing to this dispersion liquid.

(3) reduction of copper dispersion liquid is handled

In the copper dispersion liquid of having regulated the pH value, add reducing agent and reduce processing.

As the reducing agent that in the copper dispersion liquid, adds, can use at least a kind in amine borines such as hypophosphites, dimethyamine borane such as being selected from metal hydride, hydro-reduction agent, hypophosphorous acid, sodium hypophosphite and the formic acid.As metal hydride, can enumerate lithium hydride, hydrofining and calcium hydride.As the hydro-reduction agent, can enumerate lithium aluminium hydride, lithium borohydride and sodium borohydride.Wherein, can preferably use hypophosphorous acid, sodium hypophosphite.

Should illustrate that as mentioned above, formic acid also uses as the pH conditioning agent.Therefore, in decentralized medium, added under the situation of formic acid, also played a role as the pH conditioning agent when playing a role as reducing agent.

The reducing agent that adds in the copper dispersion liquid preferably excessively adds with respect to the copper atom amount of particle surface.Particularly, the total mole number of the copper particle contained with respect to dispersion liquid with molar ratio computing, preferably adds the above reducing agent of 1 times of amount, and the molal quantity with respect to total copper atom of copper particle with molar ratio computing, preferably uses the reducing agent of 1.2～10 times of amounts.

If add the reducing agent of the amount more than 10 times with respect to the total mole number of copper, then unfavorable aspect cost, might become too high by production cost.In addition, get too much from the quantitative change of the decomposition product of reducing agent, removing of it also might become numerous and diverse.

Reduction reaction preferably is made as the temperature of decentralized medium 5～60 ℃ and carry out, and more preferably is made as 35～50 ℃ and carry out.Be made as below 60 ℃ by the temperature with dispersion liquid, can reduce the influence of the change in concentration of the dispersion liquid integral body that from the copper dispersion liquid, makes decentralized medium evaporation and removing when.

The reduction of copper particle can be as mentioned above added reducing agent and is carried out in the copper dispersion liquid, perhaps make copper particle disperse and carry out in being added with the decentralized medium of reducing agent.

Should illustrate that the pH value of the copper dispersion liquid behind the interpolation reducing agent is preferably from reacting the zero hour to reacting the state that keeps the finish time below 3.Thus, can successfully carry out the removing of oxide-film on copper particle surface.

The oxidation-reduction potential of copper dispersion liquid can be according to the addition of reducing agent, kind etc. and is suitably adjusted.The oxidation-reduction potential of copper dispersion liquid is preferably 100～300mV with respect to the current potential of standard hydrogen electrode (SHE), more preferably 100～220mV.Oxidation-reduction potential by making the copper dispersion liquid is 100～300mV with respect to the current potential of standard hydrogen electrode (SHE), can successfully carry out the reduction reaction of copper ion.

Should illustrate that oxidation-reduction potential can be used as with the potential difference of normal electrode and obtains.In this manual, oxidation-reduction potential indicates with using standard hydrogen electrode to measure the potential difference that obtains as normal electrode.

After the decomposition of reducing agent finishes substantially, from dispersion liquid, separate the copper particle through surface modification.Then, water etc. cleans as required, carries out drying, can access surface oxygen concentration than O/Cu be below 0.5 the surface modification copper particle, be copper particle (A) powder.The surface oxygen concentration of copper particle (A) can be adjusted to desired scope by the pH value of for example regulating the copper dispersion liquid, the oxidation-reduction potential of adjusting the copper dispersion liquid than O/Cu in the operation of above-mentioned (1)～(3).

By carrying out the surface treatment of above-mentioned operation (1)～(3), can be with the cupric oxide (Cu that is present in the copper particle surface as initiation material ₂O, CuO) be reduced to copper atom, can reduce the amount of the cupric oxide that becomes the factor that hinders conductivity.

Should illustrate that accessory substances such as reducing agent analyte normally dissolve in the composition of decentralized medium.Therefore, by filter, centrifugation, can be from these compositions the separating copper particle.

In addition, in the copper particle surface after the surface treatment of above-mentioned operation (1)～(3), the part of copper atom is reduced the agent reduction, generates hydrogenation copper sometimes.Therefore, the copper particle after the surface treatment can be separated the back from dispersion liquid and carried out heat treated and hydrogenation copper is become copper at 40～120 ℃.

" composition metal copper particle " among the present invention is the particle that is attached with the metallic copper particulate as described above at least a portion of metallic copper particle surface." composition metal copper particle " is attached to the metallic copper particle surface with hydrogenation copper particulate and forms " copper compound particle " heating, hydrogenation copper particulate become the metallic copper particulate and the particle that obtains.Should illustrate that the metallic copper particle surface has or not adhesion of particles to confirm by observing the SEM image.In addition, be attached to the metallic copper particle the surface hydrogenation copper particulate evaluation can (the Rigaku corporate system TTR-III) be carried out by using the X-ray diffraction device.

The metallic copper particle of copper compound particle can use normally used known copper particle in the conductive paste.The shape of particle of metallic copper particle can be spherical, also can be tabular.

The average grain diameter of the metallic copper particle of copper compound particle is preferably 0.3～20 μ m, more preferably 1～10 μ m.

If the average grain diameter of metallic copper particle less than 0.3 μ m, when then making conductive paste, can not get sufficient flow behavior.On the other hand, if the average grain diameter of metallic copper particle surpasses 20 μ m, then might utilize resulting conductive paste to be difficult to make fine distribution.The average grain diameter of metallic copper particle is 1～10 μ m more preferably.Should illustrate that the average grain diameter of metallic copper particle is to measure the Feret footpath of 100 metallic copper particles selecting at random from TEM image or SEM image, this measured value is averaged calculate.

The hydrogenation copper particulate of copper compound particle mainly exists with the form of the offspring of the primary particle about 1～20nm cohesion.The shape of particle of hydrogenation copper particulate can be spherical, also can be tabular.The average grain diameter of the aggregated particle of hydrogenation copper particulate is preferably 20～400nm, more preferably 30～300nm, more preferably 50～200nm.Be preferably 80～150nm especially.If the average grain diameter of the aggregated particle of hydrogenation copper particulate is less than 20nm, then welding-the growth of hydrogenation copper particulate takes place easily, when making conducting film, might follow the unfavorable conditions such as crackle of volume contraction.On the other hand, if the average grain diameter of the aggregated particle of hydrogenation copper particulate surpasses 400nm, then particle surface is long-pending insufficient, is difficult to take place the surface melting phenomenon, is difficult to form fine and close conducting film.The average grain diameter of hydrogenation copper particulate is to measure the Feret footpath of 100 hydrogenation copper particulates selecting at random from TEM image or SEM image, this measured value is averaged calculate.

As the copper compound particle, the compound particle (copper compound particle (A2)) that preferably has metallic copper particle and hydrogenation copper particulate, described metallic copper particle is that metallic copper particle and its average primary particle diameter are 0.3～20 μ m, and described hydrogenation copper particulate is to be attached to the hydrogenation copper particulate of this metallic copper particle surface and the average grain diameter of its aggregated particle is 20～400nm.

The amount that is attached to the hydrogenation copper particulate of metallic copper particle surface is preferably 5～50 quality % of the amount of metallic copper particle, more preferably 10～35 quality %.

With respect to the amount of metallic copper particle, the amount of hydrogenation copper particulate can not fully form conductive path, the effect of the specific insulation of the conducting film that might fully be reduced during less than 5 quality % between the metallic copper particle.On the other hand, with respect to the amount of metallic copper particle, when the amount of hydrogenation copper particulate surpasses 50 quality %, be difficult to guarantee sufficient flowability as conductive paste.

Should illustrate that the amount of hydrogenation copper particulate that is attached to the surface of metallic copper particle for example can be calculated by the difference that the copper ion concentration in the water-soluble copper compound solution that adds before the reducing agent and hydrogenation copper particulate generate copper ion concentration residual in the reactant liquor after the end.

The copper compound particle for example can following by having (i)～(iii) the wet type reducing process of operation make: the operation that (i) in reaction system (R), forms hydrogenation copper particulate, (ii) in reaction system (R), drop into the metallic copper particle, make hydrogenation copper particulate be attached to the metallic copper particle surface and form the operation of " copper compound particle ", the operation of (iii) from reaction system (R), separating " copper compound particle ".By heating this copper compound particle, hydrogenation copper particulate is become the metallic copper particulate, thereby can access " composition metal copper particle ".

Should illustrate that in this manual, " reaction system (R) " refers to generate the system of hydrogenation copper particulate.Reaction system (R) comprises that not only (α) adds the system of the unreacted state of reducing agent in water-soluble copper compound solution, the system of state that also comprises the generation well afoot of (β) reaction by water-soluble copper compound and reducing agent, hydrogenation copper particulate, the system of the state that the hydrogenation copper particle after (γ) reaction of formation of hydrogenation copper particulate finishes, generates is disperseed.

That is residue in the system of various ions in the solvent, other residues, reducing agent, its analyte etc. after, " reaction system (R) " refers in the water equal solvent together to exist hydrogenation copper particulate to generate with water-soluble copper compound, copper ion, various anion.Thereby the hydrogenation copper separation of particles after will generating from solution also is scattered in decentralized medium and the dispersion liquid that obtains does not belong to the reaction system (R) in this specification again.

Below, describe to the operation (i)～(iii) of manufactured copper compound particle and by the method that this copper compound particle is made the composition metal copper particle.

(i) formation of hydrogenation copper particulate

At least add reducing agent in the water-soluble copper compound solution that reaction system (R) can form in that water-soluble copper compound is made an addition to solvent and form.

As the water miscible copper compound that forms reaction system (R), preferred mantoquita.As mantoquita, more preferably use the salt of copper (II) ion and inorganic acid or carboxylic acid.As the carboxylic acid that forms mantoquita, the carbon number that preferably also comprises the carbon atom of carboxyl is 1～4 carboxylic acid, special preferable formic acid, acetic acid or propionic acid.As water miscible copper compound, especially preferably use copper sulphate, copper nitrate, copper formate, copper acetate, copper chloride, copper bromide, cupric iodide etc.

Should illustrate, as the solvent of above-mentioned water-soluble copper compound solution, so long as can dissolve the solvent of water-soluble copper compound, just can be not particularly limited to use.As the solvent of water-soluble copper compound solution, especially preferably make water.

With respect to solution 100 quality %, the concentration of contained water-soluble copper compound is preferably 0.1～30 quality % in the water-soluble copper compound solution.If the concentration of water-soluble copper compound is less than 0.1 quality %, then the amount of moisture in the solution becomes too much, and the production efficiency of hydrogenation copper particulate reduces.On the other hand, if the concentration of water-soluble copper compound surpasses 30 quality %, then the yield of hydrogenation copper particulate might reduce on the contrary.

The water-soluble copper compound solution that adds reducing agent preferably is adjusted to the pH value below the setting.As the pH conditioning agent of water-soluble copper compound solution, can use with in the explanation of the manufacturing process of surface modification copper particle as the pH conditioning agent of copper dispersion liquid and the identical pH conditioning agent of the sour composition of enumerating.Particularly, can use for example formic acid, citric acid, maleic acid, malonic acid, acetic acid, propionic acid, sulfuric acid, nitric acid, hydrochloric acid etc.

In the middle of these, as the pH conditioning agent of water-soluble copper compound solution, can especially preferably use formic acid.Formic acid (CHO), so can residue in particle surface, suppresses the oxidation of copper particulate owing to possess the aldehyde radical with reproducibility.

The pH value of water-soluble copper compound solution is preferably below 3.Be below 3 by the pH value that makes water-soluble copper compound solution, can improve the formation efficiency of hydrogenation copper particulate.Infer that this is to reduce processing under the state that exists in solution because can mix with hydrogen ion at copper ion.If the pH value of water-soluble copper compound solution surpasses 3, then generate the metallic copper particulate easily, the production rate of hydrogenation copper particulate descends sometimes.Consider the pH value of water-soluble copper compound solution more preferably 0.5～2 from the viewpoint of the production rate that improves hydrogenation copper particulate.

As reducing agent, can use at least a kind in amine borines such as hypophosphites, dimethyamine borane such as being selected from metal hydride, hydro-reduction agent, hypophosphorous acid, sodium hypophosphite and the formic acid.As metal hydride, can enumerate lithium hydride, hydrofining and calcium hydride.As the hydro-reduction agent, can enumerate lithium aluminium hydride, lithium borohydride and sodium borohydride.Wherein, can preferably use hypophosphorous acid, sodium hypophosphite.

Should illustrate that as mentioned above, formic acid also uses as the pH conditioning agent, so added under the situation of formic acid, also plays a role as the pH conditioning agent when playing a role as reducing agent in decentralized medium.

The reducing agent of water-soluble copper compound solution preferably adds 1.2～10 times equivalents with respect to the copper ion in the solution.If the amount of the reducing agent that adds in the water-soluble copper compound solution then is difficult to obtain sufficient reduction with respect to the amount of the copper ion equivalents less than 1.2 times.On the other hand, if the addition of reducing agent surpasses 10 times equivalents with respect to the amount of copper ion, the content of the impurity such as sodium, boron, phosphorus of hydrogenation copper particulate is increased.

Reaction system (R) for example can mix the reductant solution that mixes above-mentioned reducing agent and water equal solvent and obtain and form with water-soluble copper compound solution.In addition, reaction system (R) also can make an addition to water-soluble copper compound solution with the reducing agent of solid state and form.In the reaction system (R) that forms like this, under acid condition, copper ion is reduced the agent reduction and generates hydrogenation copper particulate, carries out grain and grow.

The (ii) formation of copper compound particle

Drop into the metallic copper particle in the reaction system (R) that in above-mentioned (i), forms, make this metallic copper particle surface adhere to hydrogenation copper particulate and form " copper compound particle ".

At first, the metallic copper particle is dropped into reaction system (R).Should illustrate, for shape, the particle diameter of metallic copper particle, as mentioned above.

The metallic copper particle preferably adds in the reaction system (R) in the stage that copper ion exists or water-soluble copper compound solution.

By adding the metallic copper particle in the reaction system (R) that exists at copper ion, under the environment of metallic copper particle and the coexistence of hydrogenation copper particulate, carry out the reduction reaction of copper ion.Therefore, between metallic copper particle and hydrogenation copper particulate, can form firm bonding state.Should illustrate, have or not in the reaction system (R) to exist the concentration determination of the copper ion that copper ion can be by having used cupric ion electrode, visible absorption spectrum to confirm.In addition, have or not and exist copper ion to confirm by the oxidation-reduction potential of measuring the aqueous solution.

That is, the metallic copper particle preferably adds in the reaction system (R) in the generation way of hydrogenation copper particulate.Or preferably add the metallic copper particle in the water-soluble copper compound solution before adding reducing agent, add reducing agent then and form reaction system (R).Preferably add the metallic copper particle in the reaction system (R) in the generation way of hydrogenation copper particulate.

Should illustrate that the reaction system (R) of adding the metallic copper particle is not limited to above-mentioned state.For example, also can be at the copper ion amount in the reaction system (R), the minimizing of reduction dosage owing to the carrying out of reduction reaction, interpolation metallic copper particle in the reaction system (R) of the state that the growth of the hydrogenation copper particulate after the generation of hydrogenation copper particulate, the generation stops.That is, the metallic copper particle can drop in the reaction system (R) before hydrogenation copper particulate generates, and also can drop in the reaction system (R) in hydrogenation copper particulate generates on the way, in addition, also can drop in the reaction system (R) after hydrogenation copper particulate generates.

By drop into the metallic copper particle in reaction system (R), hydrogen copper particulate is attached to this metallic copper particle surface, can form " copper compound particle " in reaction system (R).

The amount of the copper ion of the water-soluble copper compound solution preceding with respect to the reducing agent interpolation, the amount that adds copper ion contained in the reaction system (R) of metallic copper particle is preferably 1～100 quality %, more preferably 5～100 quality %.Should illustrate that the copper in the water-soluble copper compound solution is whole Ionized copper.

The temperature of reaction system (R) is preferably below 60 ℃.Be below 60 ℃ by the temperature that makes reaction system (R), the decomposition of the hydrogenation copper particulate in can inhibitory reaction system (R).

The metallic copper particle preferably is the scope of 100～300mVSHE, more preferably adds under the state of the scope of 100～220mVSHE in the oxidation-reduction potential of reaction system (R).

Should illustrate that " SHE " means standard hydrogen electrode.In addition, " mVSHE " expression is the oxidation-reduction potential that benchmark is measured with the standard hydrogen electrode.In this manual, the measured value of oxidation-reduction potential is to be the value that benchmark records with the standard hydrogen electrode.

The (iii) separation of copper compound particle

The copper compound particle that will form in reaction system (R) separates from this reaction system (R).

Method as the copper compound particle is separated from reaction system (R) is not particularly limited.As the method that the copper compound particle is separated from reaction system (R), for example can be by methods such as centrifugation, filtrations and from reaction system (R) the copper compound particle of separated powder shape.

Behind reaction system separating copper compound particle, carry out the cleaning that the cleaning fluids such as dissolubility impurity water that are attached to particle surface are removed etc.By like this copper compound particle after separating being carried out refinement treatment, can access pulverous copper compound particle that the metallic copper particle surface is attached with hydrogenation copper particulate.Should illustrate, carry out the separation of copper compound particle before, the solvent of reaction system (R) can also be replaced, together the impurity such as analyte of reducing agent are removed with solvent.

The copper compound particle that separates from reaction system (R) is carried out heat treated, hydrogenation copper particulate is become the metallic copper particulate.Thus, can access surface oxygen concentration is composition metal copper particle below 0.5 than O/Cu.

The composition metal copper particle can positively form conductive path by being present in the interparticle metallic copper particulate of metallic copper, can reduce the specific insulation when making conducting film.In addition, as mentioned above, by hydrogenation copper particulate is become the metallic copper particulate, can be difficult to produce metallic copper particulate peeling off from the metallic copper particle.Therefore, can form the conductive paste that the viscosity because of metallic copper particulate free conductive paste that causes in conductive paste rises and is inhibited.

The heat treated of copper compound particle is preferably carried out under 60～120 ℃ temperature.If heating-up temperature surpasses 120 ℃, the welding each other of metallic copper particulate then takes place easily, the specific insulation when making conducting film might uprise.On the other hand, if heating-up temperature less than 60 ℃, then the needed time of heat treated elongated, consider from the manufacturing cost aspect, not preferred.

The heat treated of copper compound particle is more preferably carried out at 60～100 ℃, further preferably carries out at 60～90 ℃.Should illustrate that the remnant of moisture content of the composition metal copper particle that obtains after the heat treated is preferably below the 3 quality %, more preferably below the 1.5 quality %.

The heat treated of copper compound particle preferably counting-101 with relative pressure～-carry out under the decompression of 50kPa.If under the pressure greater than-50kPa, carry out heat treated, then the dry needed time elongated, consider from the manufacturing cost aspect, not preferred.On the other hand, if the pressure during heat treated less than-101kPa, then for example the removing of balance solvent such as water, need use large-scale device when dry, manufacturing cost is risen.

The surface oxygen concentration of " composition metal copper particle " can be in the operation of above-mentioned (i)～(iii) than O/Cu partial pressure of oxygen during by the heat treated of pH value, the oxidation-reduction potential of reaction system (R) or the temperature of reaction system (R) etc. of adjusting water-soluble copper compound solution or adjustment copper compound particle wait to adjust to needed scope.

The average primary particle diameter of the metallic copper particle of the composition metal copper particle that obtains through above-mentioned each operation is preferably 0.3～20 μ m.In addition, the average grain diameter of aggregated particle that is attached to the metallic copper particulate of this metallic copper particle surface is preferably 20～400nm(composition metal copper particle (A4)).

If the average grain diameter of the metallic copper particle of " composition metal copper particle " less than 0.3 μ m, when then making conductive paste, can not get sufficient flow behavior.On the other hand, if the average grain diameter of metallic copper particle surpasses 20 μ m, then utilize the conductive paste that obtains to be difficult to make fine distribution.The average grain diameter of the metallic copper particle in " composition metal copper particle " is 1～10 μ m more preferably.

The copper particulate of " composition metal copper particle " and the hydrogenation copper particulate in the copper compound particle are same, and mainly the form with the offspring of the cohesion of the primary particle about 1～20nm exists.The shape of particle of copper particulate can be for spherical, also can be for tabular.If the average grain diameter of the aggregated particle of copper particulate is less than 20nm, then welding-the growth of copper particulate takes place easily, when making conducting film, might follow the unfavorable conditions such as crackle of volume contraction.On the other hand, if the average grain diameter of the aggregated particle of copper particulate surpasses 400nm, then particle surface is long-pending not enough, is difficult to produce the surface melting phenomenon, is difficult to form fine and close conducting film.The average grain diameter of the aggregated particle of copper particulate is 30～300nm more preferably, more preferably 50～200nm.Be preferably 80～150nm especially.

Should illustrate that the average grain diameter of metallic copper particle is to measure the Feret footpath of 100 metallic copper particles selecting at random from TEM image or SEM image, this measured value is averaged calculate.In addition, the average grain diameter of copper particulate is to measure the Feret footpath of 100 hydrogenation copper particulates selecting at random from TEM image or SEM image, this measured value is averaged calculate.

As other copper particle (A), can also preferably use the average grain diameter of aggregated particle to be the hydrogenation copper particulate (A3) of 10nm～1 μ m.Hydrogenation copper particulate (A3) for example can use the solution of the water-soluble copper compound that uses in the manufacturing process of " copper compound particle " to form.Particularly, for example, can be in the solution of this water-soluble copper compound be below 3 and oxidation-reduction potential is 100～300mVSHE, is preferably and adds reducing agent under the condition of 100～220mVSHE and obtain in the pH value.As reducing agent, can use the identical reducing agent of reducing agent that uses in the manufacturing process with " copper compound particle ".

Should illustrate, the average grain diameter of the aggregated particle of hydrogenation particulate can by control during reduction reaction reaction temperature, reaction time or add dispersant and adjust.

As copper particle (A), can also preferably use this hydrogenation copper particulate (A3) is carried out heat treated and the metallic copper particulate (A5) that obtains.That is, as copper particle (A), can also preferably use is that the average grain diameter of metallic copper particulate and its aggregated particle is the metallic copper particulate (A5) of 10nm～1 μ m.

In addition, be the method for the copper particle (A) below 0.5 as obtaining surface oxygen concentration than O/Cu, be not limited to the above-mentioned method of utilizing the wet type reduction.Be the method for the copper particle (A) below 0.5 as obtaining surface oxygen concentration than O/Cu, for example the oxide-film that is formed at the surface of copper powders may can also be used acid such as hydrochloric acid, sulfuric acid, nitric acid clean, the oxide-film dissolving is removed to carry out.

In addition, be the method for the copper particle (A) below 0.5 than O/Cu as being used for obtaining surface oxygen concentration, except said method, for example can also import the gas of reproducibility on copper particle surface, in this gas, copper particle etc. is carried out heat treated and wait to carry out.

Particularly, for example, at first, import reducibility gas such as hydrogen, carbon monoxide, natural gas, decomposed ammonia body or make inside become vacuum, be reducing atmosphere in the reduction furnace thereby make.Then, in this reduction furnace, put into copper particle, 120～400 ℃ temperature ranges copper particle is reduced processing, thereby can remove the oxide of particle surface.

In addition, as the additive method that uses reducibility gas, utilize in the mist of inert gas and reducibility gas, to make plasma generation and to carrying out the method for plasma treatment in the copper particle surface, also can reduce processing to the copper particle surface.

For example shown in Figure 1, from the gas introduction port 7 supply inert gases of reactive tank 1 and the mist of reducibility gas, make AC power 5 runnings that are connected with flat upper electrode 2.Then, between upper electrode 2 and lower electrode 3, make plasma generation by glow discharge, and the zone between upper electrode 2 and lower electrode 3, specifically be at the solid dielectric 6 configuration object being treateds 4 of mounting on lower electrode 3, be copper particle, thereby can reduce processing to this copper particle surface.

In addition, as the additive method of the surface oxygen concentration of adjusting copper particle, can also be with copper particle and following chelating agent (B), thermosetting resin mixing such as (C) time by using 3 roller mills, ball mills (cream) integral body that stirs the mixture to carry out.

Chelating agent (B) is the compound that can form complex with the copper ion coordination, by the reaction shown in the following formula (1) with copper ion.

[several 1]

...(1)

Wherein, the following meaning of the symbolic representation in the formula.

M: copper ion

Z: chelating agent (B)

MZ: complex salts

X: the number of the chelating agent (B) of being combined with 1 copper

When chelating agent (B) is the x=1 of the above-mentioned formula (1) under 25 ℃, ionic strength 0.1mol/L and stability constant logK copper ion _CuIt is 5～15 compound.Stability constant logK _CuIt is the index in conjunction with intensity of force of expression chelating agent and metal.Stability constant logK _CuCan be with the equilibrium constant K of the reaction equation shown in the above-mentioned formula (1) _CuThe form of logarithm value obtain.K _CuSpecifically can be tried to achieve by following formula (2).

[several 2]

$K_{\mathrm{Cu}}=\frac{\left[M{Z}_x\right]}{\left[M\right]\·[Z{]}^x}$

...(2)

(wherein, in above-mentioned formula (2), the concentration of each composition in ［ ］ expression bracket.）

About " the stability constant logK among the present invention _Cu"; as the concrete numerical value for all cpds, for example be recorded in chemistry just hurdle (ball kind), Stability Constants of Metal-Ion Complexes(PERGAMON PRESS), Journal of Chemical Engineering Data(ACS Publications) etc. document.

Think by the stability constant logK of cooperation with copper ion _CuBe compound more than 5 as chelating agent (B), at least one part of the copper ion that generates in the cream and chelating agent (B) form complex.Therefore, can reduce with atmosphere in moisture, for example O ₂, H ₂The amount of the copper ion of contained reactions such as oxygen among the O etc. can be suppressed at and form cupric oxide in the cream.In addition, chelating agent (B) is difficult to dissociate with copper ion, therefore even under the environment of high humility, place, and state that also can the long term maintenance complex.Therefore, be difficult to form oxide film thereon, can make the conductive paste of the repressed conducting film of rising that can form specific insulation.

If the stability constant logK of chelating agent (B) _CuLess than 5, then because insufficient to the adhesion of copper ion, so can not fully reduce with atmosphere in the amount of copper ion of reactions such as moisture, oxygen, be difficult to suppress the generation of cupric oxide.In addition, if the stability constant logK of chelating agent (B) _CuSurpass 15, then chelating agent (B) is strong excessively to the adhesion of copper ion, hinders copper particle contact each other, and conductivity is reduced.Infer that this is because chelating agent (B) not only acts on the copper ion that the copper particle surface exists, but also act on copper (metallic copper).Stability constant logK _CuMore preferably 7～14.

As chelating agent (B), " nitrogen-atoms " that the functional group (b) that can preferably use the functional group (a) of containing nitrogen-atoms and contain the atom with lone electron pair beyond the nitrogen-atoms is configured in the ortho position of aromatic rings and functional group (a) and " atom with lone electron pair " of functional group (b) are by two or three atoms and the aromatic compound of bonding.Cooperate as chelating agent (B) by the compound that will have above-mentioned molecular structure, can form stable complex with copper ion.

As the atom between " atom with lone electron pair " of " nitrogen-atoms " that be present in functional group (a) and functional group (b), can enumerate carbon atom.

In above-mentioned aromatic compound, as chelating agent (B), the atom with lone electron pair that can preferably use the nitrogen-atoms of functional group (a) and functional group (b) is by two or three carbon atoms and the chelating agent of bonding.

Have functional group lone electron pair, that contain the functional group (b) of nitrogen-atoms atom in addition as being suitable as, for example can enumerate hydroxyl or carboxyl.

As chelating agent (B), particularly, for example can use at least a compound that is selected from salicylhydroxamic acid, salicylaldoxime, o-aminophenol, the salicylic acid.

As chelating agent (B), when using salicylaldoxime, by the reaction shown in the following chemical formula (I), form the complex with copper ion.

With respect to copper particle (A) 100 mass parts, the content of the chelating agent in the conductive paste (B) is preferably 0.01～1 mass parts.If the content of chelating agent (B) is less than 0.01 mass parts, when then making conducting film, the effect that the specific insulation that might fully be inhibited rises.On the other hand, if the content of chelating agent (B) surpasses 1 mass parts, then hinder copper particle contact each other, conductivity is reduced.

As thermosetting resin (C), so long as under common curing temperature abundant cured thermosetting, the known thermosetting resin that just can use the resin binder as conductive paste to use.

As thermosetting resin (C), for example can preferably using, phenolic resins, diallyl phthalate resin, unsaturated alkyd resin, epoxy resin, polyurethane resin, span come according to a cyanate resin, organic siliconresin, acrylic resin, melmac, urea resin etc.Wherein, especially preferably use phenolic resins.

Thermosetting resin (C) can the resinous principle after curing hinder the scope of conductivity to be added.The content of the thermosetting resin in the conductive paste (C) can suitably be selected according to the volume of copper particle and the ratio that is present in the volume in the space between copper particle.

With respect to copper particle (A) powder 100 mass parts, the content of the thermosetting resin in the conductive paste (C) is preferably 5～50 mass parts usually, more preferably 5～20 mass parts.If the content of thermosetting resin less than 5 mass parts, then is difficult to obtain sufficient flow behavior as lotion.On the other hand, if the content of thermosetting resin surpasses 50 mass parts, then because the resinous principle after solidifying hinders the contact between copper particle, the specific insulation of electric conductor is risen.

Conductive paste of the present invention can also contain solvent in the scope of not damaging effect of the present invention, various additive (levelling agent, coupling agent, viscosity modifier, antioxidant etc.) waits other compositions as required except above-mentioned (A)～(C) composition.Particularly, for the lotion of the flowability that obtains having appropriateness, preferably contain can heat of solution thermosetting resin (C) solvent.

As the solvent that in conductive paste, contains, for example can preferably use cyclohexanone, cyclohexanol, terpineol, ethylene glycol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethylether acetate, ethylene glycol monomethyl ether acetate, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetic acid esters, butyl carbitol acetate.As the printing lotion, consider that from the viewpoint that forms appropriate range of viscosities the amount of the solvent that contains in the preferred conductive paste is 1～10 quality % with respect to copper particle.

Conductive paste can mix each composition of above-mentioned (A)～(C) and obtain with other compositions such as solvents.

When mixing each composition of above-mentioned (A)～(C), can carry out in the following heating edge of temperature of the degree of the volatilization of the curing that thermosetting resin does not take place, solvent.Mixing, the temperature when stirring are preferably 10～40 ℃.More preferably 20～30 ℃.When forming conductive paste, by being made as the temperature more than 10 ℃, can fully reduce the viscosity of cream, can stir smoothly and fully.In addition, can make the hydrogenation copper that generates on the copper particle surface form copper atom.On the other hand, if the temperature when forming conductive paste surpasses 120 ℃, the curing that then might produce thermosetting resin (C) in cream, or particle welding each other.

Should to illustrate that copper particle is oxidized in order preventing from mixing, preferably in the container that has carried out displacement with inert gas, to mix.

Even more than Shuo Ming conductive paste of the present invention also is difficult to oxidizedly in air, compare with conductive paste in the past, can form because generating the repressed conducting film of rising of the specific insulation that cupric oxide causes.

The base material 10 that has conducting film of the present invention for example can be made as follows.That is, as shown in Figure 2, above-mentioned conductive paste is coated the surface of base material 11 and formed conductive paste film.Then, behind the volatile ingredients such as desolventizing, thermosetting resin (C) is solidified, form conducting film 12 at base material 11 and make.

As base material 11, can use glass substrate, plastic basis material, fiber reinforced composite material, ceramic substrate etc.As fiber reinforced composite material, can enumerate glass fiber-reinforced resin substrate etc., as plastic basis material, for example can enumerate membranaceous substrate that is constituted by polyimide film, polyester film etc. etc.

Particularly can preferably use the glass reinforced epoxy substrate that in printing distributing board, uses etc.

As the coating process of conductive paste, can enumerate silk screen print method, rolling method, airblade coating method, scraper rubbing method, rod and be coated with method, intaglio plate rubbing method, mould and be coated with known methods such as method, slip rubbing method.

Wherein, from the viewpoint consideration of the repressed level and smooth distribution shape of the concavo-convex generation that on base material 11, forms surface and side effectively, can preferably use silk screen print method.

The curing of thermosetting resin (C) can keep under 100～300 ℃ temperature by the base material 11 that will form conductive paste film carrying out.If curing temperature less than 100 ℃, then is difficult to thermosetting resin is fully solidified.On the other hand, if curing temperature surpasses 300 ℃, when then having used the base material 11 that is formed by thermoplastic resins such as plastic films, base material 11 might be out of shape.As curing, can enumerate methods such as hot blast heating, thermal radiation.In addition, the formation of conducting film can be carried out in air, can also carry out in that the few blanket of nitrogen of oxygen amount is inferior.

The specific insulation of conducting film 12 is preferably 1.0 * 10 ^-4Below the Ω cm.If the specific insulation of conducting film 12 surpasses 1.0 * 10 ^-4Ω cm then as the electric conductor that is used for electronic equipment, might can not get sufficient conductivity.

Consider that from the viewpoint of guaranteeing stable conductivity and keeping the distribution shape easily the thickness of the conducting film 12 on the base material 11 is preferably 1～200 μ m, more preferably 5～100 μ m.

With regard to the base material that has conducting film that the present invention relates to, owing to utilize the conductive paste of the invention described above to form conducting film, so be difficult to generate the oxide film thereon that causes because of cupric oxide, compare with the base material that has conducting film in the past, even if can form specific insulation low and also under the environment of high humility long-term use also can suppress the base material that has conducting film of the rising of specific insulation.

More than, giving an example for the base material that has conducting film of the present invention is illustrated, but under the situation of not violating purport of the present invention, can also suitably change formation as required.In addition, in the manufacture method of the base material that has a conducting film of the present invention, for the formation sequential scheduling of each one, also can under the situation that can make the base material that has conducting film, suitably change.

Embodiment

Below, utilize embodiment to further describe the present invention.

At first, obtain copper particle has been implemented the copper particle (A) (surface modification copper particle) that reduction is handled.That is, in glass beaker processed, drop into formic acid 3.0g and 50wt% hypophosphorous acid aqueous solution 9.0g, this beaker is put into water-bath and remain on 40 ℃.Slow interpolation copper particle in this beaker (Mitsu Mining ﹠ Smelting Co., Ltd's system, trade name: " 1400YP ", and average primary particle diameter: 5.0g 7 μ m), stirred 30 minutes, obtain " copper dispersion liquid ".Use whizzer, with rotating speed 3000rpm centrifugation 10 minutes, from " the copper dispersion liquid " that obtain, reclaim sediment.Make this sediment be scattered in steaming and stay water 30g, by centrifugation condensation product is precipitated again, sediment separate out.The sediment that obtains under the decompression of-35kPa, 80 ℃ of heating 60 minutes, is made the residual moisture volatilization and it is slowly removed, obtain particle surface by the copper particle of surface modification (A-1).

For the copper particle that obtains (A-1), utilize x-ray photoelectron spectroscopy apparatus (ULVAC-PHI corporate system, trade name: " ESCA5500 "), under following condition, carry out the mensuration of surface oxygen concentration " atom % " and surperficial copper concentration " atom % ".

Analyze area: 800mm ²φ

·Pass?Energy：93.9eV

·Energy?Step：0.8eV/step

The surface oxygen concentration that obtains is calculated surface oxygen concentration than O/Cu divided by surperficial copper concentration, and the surface oxygen concentration of copper particle (A-1) is 0.16 than O/Cu as a result.

Should illustrate that sharp oxygen consuming amount meter (LECO corporate system, trade name: " ROH-600 ") is measured the oxygen amount in the copper particle (A-1), the oxygen amount is 460ppm as a result.

(embodiment 1)

Cooperate salicylhydroxamic acid 0.005g and make its dissolving in the resin solution that obtains at mixed phenol urea formaldehyde (group flourish KCC system, trade name: " RESITOPPL6220 ") 0.74g and ethylene glycol monomethyl ether acetate 0.43g.In this resin solution, cooperate copper particle (A-1) 5.0g, in mortar, mix, obtain conductive paste 1.

On glass substrate, be coated with this conductive paste 1 with the banded distribution shape of width 1mm, thickness 20 μ m by silk screen print method, make phenolic resin curing 150 ℃ of heating 30 minutes, form the substrate that has conducting film 1 with conducting film 1.

(embodiment 2)

The use level of salicylhydroxamic acid is changed to 0.0125g, in addition, carry out similarly to Example 1, obtain conductive paste 2.

(embodiment 3)

Replace salicylhydroxamic acid 0.005g, in resin solution, add salicylaldoxime 0.025g, in addition, carry out similarly to Example 1, obtain conductive paste 3.

(embodiment 4)

The use level of salicylaldoxime is changed to 0.0125g, in addition, carry out similarly to Example 3, obtain conductive paste 4.

(embodiment 5)

Replace salicylhydroxamic acid 0.005g, in resin solution, add o-aminophenol 0.0125g, in addition, carry out similarly to Example 1, obtain conductive paste 5.

(embodiment 6)

Replace salicylhydroxamic acid 0.005g, in resin solution, add salicylic acid 0.0125g, in addition, carry out similarly to Example 1, obtain conductive paste 6.

(comparative example 1)

In resin solution, do not add salicylhydroxamic acid 0.005g, in addition, carry out similarly to Example 1, obtain conductive paste 7.

(comparative example 2)

Replace salicylhydroxamic acid 0.005g, in resin solution, add salicylyl hydrazine 0.0125g, in addition, carry out similarly to Example 1, obtain conductive paste 8.

(comparative example 3)

Replace salicylhydroxamic acid 0.005g, in resin solution, add rosin acid 0.0125g, in addition, carry out similarly to Example 1, obtain conductive paste 9.

Replace conductive paste 1, at glass substrate coating conductive paste 2～6, form conducting film 2～6, in addition, carry out similarly to Example 1, obtain having base material 2～6(embodiment 2～6 of conducting film).In addition, replace conductive paste 1, at glass substrate coating conductive paste 7～9, form conducting film 7～9, in addition, carry out similarly to Example 1, obtain having base material 7～9(comparative example 1～3 of conducting film).

(resistance of electric conductor distribution)

Utilize resistance value meter (Keithley corporate system, trade name: " Milliohm Hi-Tester ") to measure the resistance value of resulting conducting film 1～9.

(endurance test)

Then, the endurance test that the base material 1～9 that has conducting film is carried out under the hot and humid environment.That is, the base material 1～9 that will have a conducting film keeps 60 hours in 70 ℃, the hot and humid groove of 85%RH after, measure the resistance value of conducting film 1～9.

In table 1, with under 25 ℃ of the compound that uses in the kind of the compound that uses in the rate of change of the specific insulation after the endurance test under the specific insulation at initial stage and the hot and humid environment and the chelating agent (B), the chelating agent (B), ionic strength 0.1mol/L condition and stability constant logK copper ion _Cu, and the addition of chelating agent (B) illustrate in the lump.Should illustrate that in table 1, the addition of chelating agent (B) is with addition (mass parts) expression with respect to copper particle 100 mass parts.

As shown in Table 1, use the stability constant logK that has cooperated with copper ion _CuThe conductive paste 1～6 that is 5～15 chelating agent (B) has formed in the base material that has conducting film 1～6 of conducting film 1～6, and specific insulation is low, and the rate of change of transferring the specific insulation of postpone at hot and humid environment also is suppressed lowlyer.

On the other hand, use the conductive paste 7 do not cooperate chelating agent (B) and to form and formed the base material 7(comparative example 1 that has conducting film of conducting film 7) in, the rate of change height to 9% of the specific insulation of postpone, poor durability transferred at hot and humid environment.In addition, use as chelating agent (B) and cooperated stability constant logK with copper ion _CuThe conductive paste 8 of the compound (salicylyl hydrazine) above 15 and use have cooperated the stability constant logK with copper ion _CuThe conductive paste 9 of the compound less than 5 (rosin acid) and having formed in the base material that has conducting film 8～9 of conducting film 8～9, the specific insulation height at initial stage, to transfer the rate of change of specific insulation of postpone also high to 10～12% for hot and humid environment in addition, poor durability.

Symbol description

1 ... reactive tank, 2 ... upper electrode, 3 ... lower electrode, 4 ... object being treated, 5 ... AC power, 6 ... solid dielectric, 7 ... gas introduction port, 8 ... gas discharge outlet, 9 ... insulant, 10 ... the base material that has conducting film, 11 ... base material, 12 ... conducting film

Claims (15)

1. conductive paste, it is characterized in that, contain copper particle (A), chelating agent (B) and thermosetting resin (C), the surface oxygen concentration that utilizes the x-ray photoelectron optical spectroscopy to obtain of described copper particle (A) is below 0.5 than O/Cu, and described chelating agent (B) is by under 25 ℃, ionic strength 0.1mol/L condition and stability constant logK copper ion _CuBe that 5～15 compound constitutes.

2. conductive paste according to claim 1 is characterized in that, described copper particle (A) is to be to handle the surface modification copper particle that obtains through reduction in the decentralized medium below 3 in the pH value.

3. conductive paste according to claim 1, it is characterized in that, described copper particle (A) be will have metallic copper particle and hydrogenation copper particulate the heating of copper compound particle and described hydrogenation copper particulate become the metallic copper particulate and the composition metal copper particle that forms, the average primary particle of described metallic copper particle directly is 0.3～20 μ m, described hydrogenation copper particle coagulation and be attached to described metallic copper particle surface and average primary particle directly is 1～20nm.

4. conductive paste according to claim 2 is characterized in that, as the pH value conditioning agent of described decentralized medium, uses to be selected from least a in formic acid, citric acid, maleic acid, malonic acid, acetic acid, propionic acid, sulfuric acid, nitric acid, the hydrochloric acid.

5. conductive paste according to claim 3, it is characterized in that, as the pH conditioning agent of the water-soluble copper compound solution that is used to form described hydrogenation copper particulate, use to be selected from least a in formic acid, citric acid, maleic acid, malonic acid, acetic acid, propionic acid, sulfuric acid, nitric acid, the hydrochloric acid.

6. according to each described conductive paste in the claim 1～5, it is characterized in that, described chelating agent (B) is the aromatic compound that the functional group (a) of containing nitrogen-atoms and the functional group (b) of containing the atom with lone electron pair beyond the nitrogen-atoms are coordinated in the ortho position of aromatic rings, and the atom with lone electron pair beyond described nitrogen-atoms and the described nitrogen-atoms passes through two or three atoms and bonding.

7. conductive paste according to claim 6 is characterized in that, the described functional group (b) of containing the nitrogen-atoms atom with lone electron pair in addition is hydroxyl or carboxyl.

8. according to claim 6 or 7 described conductive pastes, it is characterized in that the atom with lone electron pair beyond described nitrogen-atoms and the described nitrogen-atoms is by two or three carbon atoms and bonding.

9. according to each described conductive paste in the claim 1～8, it is characterized in that described chelating agent (B) is the compound that is selected from salicylhydroxamic acid, salicylaldoxime, o-aminophenol, the salicylic acid.

10. according to each described conductive paste in the claim 1～9, it is characterized in that described thermosetting resin (C) is to be selected from phenolic resins, diallyl phthalate resin, unsaturated alkyd resin, epoxy resin, polyurethane resin, span to come according at least a resin in a cyanate resin, organic siliconresin, acrylic resin, melmac, the urea resin.

11., it is characterized in that with respect to described copper particle (A) 100 mass parts, the amount of described chelating agent (B) is 0.01～1 mass parts according to each described conductive paste in the claim 1～10.

12., it is characterized in that with respect to described copper particle (A) 100 mass parts, the amount of described thermosetting resin (C) is 5～50 mass parts according to each described conductive paste in the claim 1～11.

13. a base material that has conducting film is characterized in that, has at base material the conducting film that each described conductive paste is solidified to form in the claim 1～12 is formed.

14. the base material that has conducting film according to claim 13 is characterized in that, the specific insulation of described conducting film is 1.0 * 10 ^-4Below the Ω cm.

15. a manufacture method that has the base material of conducting film is characterized in that, behind each described conductive paste, makes this conductive paste be solidified to form conducting film in base material coating claim 1～12.

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