JP7143685B2 - METHOD FOR MANUFACTURING CONDUCTIVE LAMINATED BODY, CONDUCTIVE LAMINATED BODY, AND 2-PART CONDUCTIVE FILM FORMING AGENT - Google Patents

Description

TECHNICAL FIELD The present invention relates to a conductive laminate, a method for producing the same, and a two-component conductive film-forming agent.

A conductive laminate in which a film having conductivity (hereinafter sometimes referred to as a conductive film) is provided on a base material is an electronic material for producing electronic devices such as peripheral parts for automobiles, semiconductor packages, and smartphone antennas. is used as Electromagnetic wave shields, smartphone antennas, automotive wiring, laminates, solar panels, displays, transistors, semiconductor packages, multilayer ceramic capacitors, and other electronic components have a conductive film on the surface of the substrate to ensure conduction. is being established.

As a method of forming a conductive film on a base material, a conductor-forming agent such as ink or paste containing metal particles is applied to the base material, and the coating is heated to sinter the metal particles to form a conductor. There is known a method for doing so (see, for example, Patent Documents 1 and 2 below). According to such a method, conductive films such as wirings and internal electrodes can be efficiently formed in desired shapes on base materials such as glass substrates and dielectric green sheets.

JP 2012-072418 A JP 2012-226865 A

However, a conductive film formed by sintering metal particles may not have sufficient adhesiveness depending on the material of the base material, and may not be able to ensure conduction. Recently, substrates used for electronic parts or electronic materials are diversified, and improvement of adhesiveness between substrates and conductive films has become an issue.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a conductive laminate having a conductive film with excellent adhesion to a substrate, and a method for producing the same. Another object of the present invention is to provide a two-component conductive film-forming agent capable of forming a conductive film having excellent adhesiveness to a substrate.

In order to solve the above problems, the present invention provides a method for producing a conductive laminate comprising a base material and a conductive film provided on the base material, wherein a thermosetting resin is coated on the base material A step of providing a resin composition layer containing the and forming a conductive film adhered to a base material with a cured product of (1).

According to the method for producing a conductive laminate of the present invention, it is possible to obtain a conductive laminate having a conductive film with excellent adhesiveness to a substrate.

The present inventors consider the reason why the conductive film having excellent adhesiveness to the substrate is formed by the above process as follows. By providing a metal particle-containing layer on the resin composition layer before curing, a structure is formed in which the sintered body of the copper-containing particles is slightly embedded in the cured resin after heating, and the sintered body of the copper-containing particles is strong. is considered to be a factor in obtaining a conductive film having excellent adhesiveness to the substrate.

The thermosetting resin is an epoxy resin having a bisphenol skeleton and a linear hydrocarbon group having 4 or more carbon atoms, and/or an epoxy resin having a bisphenol skeleton and a polyoxyalkylene group containing 3 or more ether bonds. is preferably included. In this case, both the conductivity of the conductive film and the adhesiveness to the substrate can be achieved at a high level.

Further, when the copper-containing particles are coated copper particles having a core particle containing copper and an organic coating layer covering at least a part of the surface of the core particle, a conductive film can be formed at a lower temperature. .

From the viewpoint of facilitating the formation of the metal particle-containing layer and the control of the thickness of the conductive film, the metal particle-containing layer is formed by applying a conductor-forming composition containing copper-containing particles onto the resin composition layer, The content of the copper-containing particles in the conductor-forming composition is preferably 20 to 80 parts by mass with respect to 100 parts by mass of the total conductor-forming composition.

The heating temperature may range from 100°C to 250°C.

The present invention also provides a conductive laminate comprising a substrate and a conductive film provided on the substrate, wherein the conductive film contains a sintered body of copper-containing particles, and the substrate and the conductive film A conductive laminate having a cured thermosetting resin composition between them is provided.

In the conductive laminate of the present invention, the conductive film having the structure described above has excellent adhesiveness to the base material, so that the conductive laminate can easily ensure conductivity.

In the conductive laminate of the present invention, the thermosetting resin composition is an epoxy resin having a bisphenol skeleton and a linear hydrocarbon group having 4 or more carbon atoms, and/or a bisphenol skeleton and 3 or more ether bonds. It may contain an epoxy resin having a polyoxyalkylene group containing. In this case, the conductive laminate can have a conductive film that is excellent in both conductivity and adhesiveness to the substrate.

The present invention also provides a two-component conductive film-forming agent comprising a component containing a thermosetting resin and a component b containing copper-containing particles.

According to the two-component conductive film-forming agent of the present invention, the resin composition layer and the metal particle-containing layer in the method for producing a conductive laminate according to the present invention can be formed. It is possible to form a conductive film having excellent adhesion to the film.

The thermosetting resin is an epoxy resin having a bisphenol skeleton and a linear hydrocarbon group having 4 or more carbon atoms, and/or an epoxy resin having a bisphenol skeleton and a polyoxyalkylene group containing 3 or more ether bonds. can include In this case, a conductive film excellent in both conductivity and adhesiveness to the substrate can be formed on the substrate.

The copper-containing particles may be coated copper particles having a core particle containing copper and an organic coating layer coating at least part of the surface of the core particle. In this case, the conductive film can be formed on the substrate at a lower temperature.

ADVANTAGE OF THE INVENTION According to this invention, the electrically conductive laminated body which has an electrically conductive film which is excellent in adhesiveness with a base material, and its manufacturing method can be provided. Moreover, according to the present invention, it is possible to provide a two-component conductive film-forming agent capable of forming a conductive film having excellent adhesiveness to a substrate.

DETAILED DESCRIPTION OF THE INVENTION Embodiments for carrying out the present invention will be described in detail below. However, the present invention is not limited to the following embodiments.

In this specification, the numerical range indicated using "to" indicates the range including the numerical values before and after "to" as the minimum and maximum values, respectively. Furthermore, in the present specification, the content of each component in the composition refers to the total amount of the multiple substances present in the composition when there are multiple substances corresponding to each component in the composition, unless otherwise specified. means

As used herein, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.

In the present specification, the term "layer" or "film" includes not only a shape configuration formed over the entire surface but also a shape configuration formed partially when observed as a plan view.

As used herein, the term "laminate" indicates stacking layers, and two or more layers may be combined.

<Method for manufacturing conductive laminate>
The method for producing a conductive laminate of the present embodiment is a method for producing a conductive laminate comprising a base material and a conductive film provided on the base material. Step S1 of providing a resin composition layer containing a curable resin, Step S2 of providing a metal particle-containing layer containing copper-containing particles on the resin composition layer, and heating the resin composition layer and the metal particle-containing layer, and a step S3 of forming a conductive film adhered to the substrate by a cured product of the resin composition layer.

(Step S1)
The base material is not particularly limited, and may or may not have conductivity. Examples of materials for the substrate include metals such as gold, silver, copper, platinum, palladium, zinc, nickel, tin, cobalt, iron, and aluminum, alloys of these metals, indium tin oxide, zinc oxide, indium zinc oxide, Semiconductors such as indium gallium zinc oxide, silicon, silicon carbide, and gallium nitride; glasses such as quartz glass, borosilicate glass, and soda lime glass; carbon materials such as graphite and graphite; resins; and paper.

As the resin, thermoplastic resins and thermosetting resins can be used. Specifically, polyolefin resins such as polyethylene, polypropylene, and polymethylpentene, polycarbonate resins, liquid crystal polymer resins, polyamides, polyaramids, and polyether ether ketones can be used. , polyphenylsulfone, polyethersulfone, polyamideimide, and polyimide.

The substrate may be a liquid crystal resin (LCP) substrate. A liquid crystal resin refers to a polymer that exhibits a state in which molecular chains are almost regularly aligned (liquid crystallinity) when the resin is melted at high temperatures or dissolved in a solvent to become a fluid state. For example, some resins among wholly aromatic polyesters, aromatic polyazomethines, aromatic-aliphatic polyesters, aromatic polyester carbonates, wholly aromatic or non-wholly aromatic polyesteramides, etc. are known to exhibit liquid crystallinity. ing. Examples of these polyesters include polyesters obtained by linear polycondensation of parahydroxybenzoic acid and other components. Specifically, polyesters obtained by polycondensation of ethylene terephthalate and parahydroxybenzoic acid, polyesters obtained by polycondensation of phenol, phthalic acid and parahydroxybenzoic acid, and polycondensation of 2,6-hydroxynaphthoic acid and parahydroxybenzoic acid. Examples include condensed polyesters. A commercially available LCP base material can be used, and examples thereof include "Sumikasuper E6007" (manufactured by Sumitomo Chemical Co., Ltd., trade name) and "UENO LCP 2030G" (manufactured by Ueno Pharmaceutical Co., Ltd., trade name).

The substrate may contain fillers. Fillers include glass fibers, inorganic fillers, and combinations thereof.

The shape of the substrate is not particularly limited, and may be plate-like, rod-like, roll-like, film-like, spherical, cubic, rectangular parallelepiped, or the like. Also, it may be a combination of two or more of these, or a complicated three-dimensional shape that does not belong to any of them.

The resin composition layer can be formed using a thermosetting resin composition containing a thermosetting resin. Thermosetting resins include epoxy resins, urethane resins, imide resins, and phenol resins. Epoxy resins, from the viewpoint of flexibility and adhesion between the cured resin and the substrate, include epoxy resins having a bisphenol skeleton and a straight-chain hydrocarbon group with 4 or more carbon atoms, and bisphenol skeletons and 3 or more ether bonds. One or two or more of epoxy resins having a polyoxyalkylene group can be used.

As the epoxy resin having a bisphenol skeleton and a linear hydrocarbon group having 4 or more carbon atoms, for example, "EPICLON EXA4816" (which is an epoxy resin having a bisphenol A skeleton and a linear hydrocarbon group having 6 carbon atoms) ( DIC Corporation, trade name) can be used. Examples of epoxy resins having a bisphenol skeleton and a polyoxyalkylene group containing three or more ether bonds include polyalkyleneoxylated bisphenol A type epoxy resin "EPICLON EXA4850-150" (manufactured by DIC Corporation, trade name). can be used.

The content of the thermosetting resin in the thermosetting resin composition may be 10 to 70% by mass, 20 to 60% by mass, or 30 to 50% by mass based on the total amount of the composition.

The thermosetting resin composition can contain a curing agent. Curing agents for curing the above epoxy resins include amine compounds, acid anhydrides, phenol compounds, imidazole compounds, latent curing agents, and the like. Curing agents may be used singly or in combination of two or more.

The content of the curing agent in the thermosetting resin composition may be 1 to 20 parts by weight, 3 to 15 parts by weight, or 5 to 10 parts by weight with respect to 100 parts by weight of the thermosetting resin.

The thermosetting resin composition may contain other components such as a dispersion medium, an inorganic filler, and a coupling agent, if necessary. Dispersion media include alcohols such as methanol, ethanol, propanol and butanol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; aromatic compounds such as toluene and xylene; chains such as butane, pentane, hexane, heptane and octane. hydrocarbons, esters such as ethyl acetate, propyl acetate and butyl acetate, and cyclic compounds such as cyclohexane, methylcyclohexane and cyclohexanone. As the inorganic filler, one having a high insulating property is preferable, and examples thereof include silica, alumina, silicon nitride, aluminum nitride, and boron nitride. Examples of coupling agents include compounds containing Si, Ti, Zr, Al, Sn, or Ce as main component elements.

A resin composition layer containing a thermosetting resin can be formed by applying the thermosetting resin composition described above onto a substrate by a known method. Application methods include inkjet, super inkjet, screen printing, transfer printing, offset printing, jet printing, dispensing, jet dispensing, needle dispensing, comma coating, bar coating, and slit coating. , die coating method, gravure coating method, relief printing method, intaglio printing method, gravure printing method, soft lithography method, dip pen lithography method, particle deposition method, spray coating method, spin coating method, dip coating method, electrodeposition coating method, etc. can be mentioned.

In the present embodiment, it is preferable to clean the substrate surface by washing it before providing the resin composition layer on the substrate. Methods for cleaning the substrate surface include a method of cleaning with a cleaning solution containing solvent or water, a method of cleaning by irradiating the surface of the substrate with ultraviolet rays, a method of cleaning by irradiating the surface of the substrate with a plasma beam, and a method of cleaning the surface of the substrate. A method of washing by spraying dry ice particles on the surface, and the like can be mentioned.

The shape of the resin composition layer provided on the substrate is not particularly limited, and can be appropriately selected according to the purpose. In addition, the thickness of the resin composition layer can be appropriately set according to the purpose. .

After providing the resin composition layer on the base material, the base material can be heated to remove excess dispersion medium. The temperature range for heating the substrate is preferably room temperature to 90°C, more preferably 40°C to 80°C. When the heating temperature of the base material is 90° C. or less, it is possible to suppress excessive curing of the resin composition layer, and it becomes easy to embed the copper sintered body formed in step S3 in the resin cured product. It becomes easier to form a conductive film having excellent adhesiveness to the substrate.

(Step S2)
The metal particle-containing layer can be formed using a conductor-forming composition containing copper-containing particles. In addition to the copper-containing particles, the conductor-forming composition may optionally contain other components such as a dispersion medium and a resin component.

The copper-containing particles may be copper particles mainly made of metallic copper, or a core particle that is a copper particle mainly made of metallic copper and an organic coating layer covering part or all of the surface of the core particle. It may be a coated copper particle having A combination of copper particles and coated copper particles may also be used. The organic coating layer of the coated copper particles is usually thermally decomposed and lost by heating when the metal particle-containing layer formed from the conductor-forming composition is sintered.

The coated copper particles are easily fused by heating at a low temperature (for example, 150° C. or lower) to form a conductor. The organic coating layer functions as a protective material for the copper particles, which are the core particles, and suppresses oxidation of the core particles. For this reason, even after long-term storage in the atmosphere, good fusion-bondability at low temperatures is likely to be maintained.

The element ratio of copper in the copper particles or core particles may be 80 atomic % or more, 90 atomic % or more, or 95 atomic % or more based on all elements excluding hydrogen, carbon and oxygen. When the element ratio of copper is 80 atomic % or more, the thermal conductivity and sinterability derived from copper tend to be easily exhibited.

The copper particles or core particles can contain at least one selected from the group consisting of copper and alloys containing copper. Also, the copper particles or core particles can contain minor amounts of other components other than metallic copper. Examples of components other than metallic copper include metals such as gold, silver, platinum, tin and nickel, metal compounds containing these metal elements, copper oxide, copper chloride, and organic substances. The organic substance may be a substance derived from fatty acid copper, a reducing compound, or an aliphatic amine, which will be described later. From the viewpoint of forming a conductor with excellent conductivity, the content of metallic copper in the copper particles is 50 to 100% by mass, 60 to 100% by mass, or 70 to 100% by mass based on the mass of the copper particles. may

In the coated copper particles, the ratio of the organic coating layer covering the surface of the core particles may be 0.1 to 20% by mass based on the total mass of the core particles and the organic coating layer. When the proportion of the organic coating layer is 0.1% by mass or more, there is a tendency that sufficient oxidation resistance is likely to be obtained. When the proportion of the organic coating layer is 20% by mass or less, the low-temperature fusion bondability of the coated copper particles tends to be better. From the same point of view, the proportion of the organic coating layer based on the total mass of the core particles and the organic coating layer may be 0.3-10% by mass, or 0.5-5% by mass.

Coated copper particles are produced, for example, by a method that includes heating a mixture containing fatty acid copper, a reducing compound, and an aliphatic amine. This method may optionally include steps such as centrifugation and washing after the heating step.

In the above method, fatty acid copper is used as a copper precursor. This allows lower boiling point (ie, lower molecular weight) aliphatic amines to be used as the reaction medium. When an aliphatic amine with a low boiling point is used, the resulting organic coating layer of the coated copper particles becomes more susceptible to thermal decomposition or volatilization, so that conductors with good electrical conductivity can be formed by sintering at lower temperatures. it is conceivable that.

A fatty acid constituting fatty acid copper is a monovalent carboxylic acid represented by RCOOH (R represents a linear or branched hydrocarbon group). Fatty acids may be either saturated or unsaturated fatty acids. From the viewpoint of efficiently covering the core particles to suppress oxidation, the fatty acid may be a linear saturated fatty acid. Only one kind of fatty acid may be used, or two or more kinds thereof may be used.

The number of carbon atoms in the fatty acid may be 9 or less. Examples of saturated fatty acids having 9 or less carbon atoms include acetic acid (2 carbon atoms), propionic acid (3 carbon atoms), butyric acid and isobutyric acid (4 carbon atoms), valeric acid and isovaleric acid (5 carbon atoms). , caproic acid (6 carbon atoms), enanthic acid and isoenanthic acid (7 carbon atoms), caprylic acid, isocaproic acid and isocaproic acid (8 carbon atoms), and nonanoic acid and isononanoic acid (9 carbon atoms). Examples of unsaturated fatty acids having 9 or less carbon atoms include those having one or more double bonds in the hydrocarbon group of the above saturated fatty acids.

The type of fatty acid can affect properties such as the dispersibility of the coated copper particles in the dispersion medium and the fusion bondability. From the viewpoint of making the particle shape uniform, a fatty acid having 5 to 9 carbon atoms and a fatty acid having 4 or less carbon atoms may be used in combination. For example, nonanoic acid having 9 carbon atoms and acetic acid having 2 carbon atoms may be used in combination. When a fatty acid having 5 to 9 carbon atoms and a fatty acid having 4 or less carbon atoms are used in combination, their ratio is not particularly limited.

The method of obtaining fatty acid copper is not particularly limited, and for example, it may be obtained by a method of reacting copper hydroxide and fatty acid in a solvent. Commercially available fatty acid copper may be used. Alternatively, copper hydroxide, a fatty acid and a reducing compound are mixed in a solvent to form a fatty acid copper and a complex formed between the fatty acid copper and the reducing compound in the same step. good too.

It is believed that the reducing compound reacts with the fatty acid copper to form a complex compound such as a complex. It is believed that the reducing compound functions as an electron donor to the copper ions in the fatty acid copper, thereby facilitating the reduction of the copper ions. Therefore, fatty acid copper that forms a complex compound is more likely to liberate copper atoms due to spontaneous thermal decomposition than fatty acid copper that does not form a complex compound.

One reducing compound may be used alone, or two or more thereof may be used in combination. Examples of reducing compounds include hydrazine compounds such as hydrazine, hydrazine derivatives, hydrazine hydrochloride, hydrazine sulfate, and hydrazine hydrate; hydroxylamine compounds such as hydroxylamine and hydroxylamine derivatives; and sodium borohydride, sodium sulfite. , sodium bisulfite, sodium thiosulfate, and sodium hypophosphite.

A reducing compound having an amino group may be used from the viewpoint of facilitating the formation of a complex while maintaining the structure of the fatty acid copper. A reducing compound having an amino group may be, for example, a compound selected from hydrazine and its derivatives, and hydroxylamine and its derivatives. These reducing compounds can form a complex by forming a coordinate bond between a nitrogen atom and a copper atom. Since these reducing compounds generally have stronger reducing power than aliphatic amines, the resulting complex tends to spontaneously decompose under relatively mild conditions, resulting in reduction and liberation of copper atoms. Therefore, the heating temperature in the step of heating the mixture containing the fatty acid copper, the reducing compound and the aliphatic amine can be, for example, a low temperature (e.g. 150°C or less) that does not cause evaporation or decomposition of the aliphatic amine.

By using a hydrazine derivative and a hydroxylamine derivative, it is possible to adjust the reactivity with fatty acid copper to form a complex that undergoes spontaneous decomposition under desired conditions. Examples of hydrazine derivatives include methylhydrazine, ethylhydrazine, n-propylhydrazine, isopropylhydrazine, n-butylhydrazine, isobutylhydrazine, sec-butylhydrazine, t-butylhydrazine, n-pentylhydrazine, isopentylhydrazine, neo- Pentylhydrazine, t-pentylhydrazine, n-hexylhydrazine, isohexylhydrazine, n-heptylhydrazine, n-octylhydrazine, n-nonylhydrazine, n-decylhydrazine, n-undecylhydrazine, n-dodecylhydrazine, cyclohexylhydrazine , phenylhydrazine, 4-methylphenylhydrazine, benzylhydrazine, 2-phenylethylhydrazine, 2-hydrazinoethanol, and acetohydrazine. Examples of derivatives of hydroxylamine are N,N-di(sulfoethyl)hydroxylamine, monomethylhydroxylamine, dimethylhydroxylamine, monoethylhydroxylamine, diethylhydroxylamine and N,N-di(carboxyethyl)hydroxylamine. mentioned.

The ratio of the copper contained in the fatty acid copper and the reducing compound is not particularly limited as long as the desired complex is formed. For example, the copper:reducing compound molar ratio may be from 1:1 to 1:4, from 1:1 to 1:3, or from 1:1 to 1:2.

The aliphatic amine is believed to function as a reaction medium for the decomposition reaction of the complex formed from the fatty acid copper and the reducing compound. Further, the aliphatic amine is thought to capture protons generated by the reducing action of the reducing compound, thereby suppressing oxidation of the copper atoms due to acidification of the reaction solution.

Aliphatic amines are primary amines represented by RNH ₂ (R represents an optionally substituted linear, branched or cyclic aliphatic group), R ¹ R ² NH (R ¹ and R ² each independently represent an optionally substituted linear, branched or cyclic aliphatic group. alkylenediamine having one amino group, or a combination thereof. Aliphatic amines may have aliphatic groups containing one or more double bonds and may have substituents containing atoms such as oxygen, silicon, nitrogen, sulfur, phosphorus, and the like. Aliphatic amines may be used alone or in combination of two or more.

Examples of primary amines include ethylamine, 2-ethoxyethylamine, propylamine, butylamine, isobutylamine, pentylamine, isopentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, dodecylamine, hexa Decylamine, oleylamine, 3-methoxypropylamine, 4-methoxybutylamine, and 3-ethoxypropylamine.

Examples of secondary amines include diethylamine, dipropylamine, dibutylamine, ethylpropylamine, ethylpentylamine, dibutylamine, dipentylamine, and dihexylamine.

Examples of alkylenediamines include ethylenediamine, N,N-dimethylethylenediamine, N,N'-dimethylethylenediamine, N,N-diethylethylenediamine, N,N'-diethylethylenediamine, 1,3-propanediamine, 2,2- dimethyl-1,3-propanediamine, N,N-dimethyl-1,3-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, N,N-diethyl-1,3-diaminopropane, 1 ,4-diaminobutane, 1,5-diamino-2-methylpentane, 1,6-diaminohexane, N,N'-dimethyl-1,6-diaminohexane, 1,7-diaminoheptane, 1,8 -diaminooctane, 1,9-diaminononane, and 1,12-diaminododecane.

The number of carbon atoms in the aliphatic group of the aliphatic amine may be 7 or less. When the number of carbon atoms in the aliphatic group of the aliphatic amine is 7 or less, the aliphatic amine is likely to be thermally decomposed, so that sintering at a low temperature tends to easily form a conductor having good electrical conductivity. The number of carbon atoms in the aliphatic group of the aliphatic amine may be 6 or less, or 3 or more. An aliphatic amine having an aliphatic group with 7 or less carbon atoms and an aliphatic amine having an aliphatic group with 8 or more carbon atoms may be used in combination. In that case, the ratio of the aliphatic amine having an aliphatic group having 7 or less carbon atoms to the whole aliphatic amine may be 50% by mass or more, 60% by mass or more, or 70% by mass or more.

The ratio of copper and aliphatic amine contained in fatty acid copper is not particularly limited. For example, the copper:aliphatic amine molar ratio may be from 1:1 to 1:8, from 1:1 to 1:6, or from 1:1 to 1:4.

The mixture for forming coated metal particles comprising fatty acid copper, reducing compound and fatty amine may further comprise a solvent. The mixture may contain a polar solvent from the viewpoint of promoting the formation of a complex between the fatty acid copper and the reducing compound. Here, a polar solvent means a solvent that dissolves in water at 25°C. The polar solvent may be alcohol. The use of alcohol tends to promote formation of the complex. Although the reason for this is not clear, it is believed that contact with the water-soluble reducing compound is promoted while dissolving the solid fatty acid copper. A solvent may be used individually by 1 type, or may use 2 or more types together.

The alcohol that dissolves in water at 25° C. may be, for example, an alcohol having 1 to 8 carbon atoms and one hydroxyl group. Examples of such alcohols include straight-chain alkyl alcohols, phenols, compounds having two or more hydrocarbon groups, an ether bond connecting them, and a hydroxyl group. From the viewpoint of expressing stronger polarity, an alcohol having two or more hydroxyl groups may be used. Alternatively, an alcohol containing a sulfur atom, a phosphorus atom, a silicon atom, or the like may be used.

Examples of alcohols include methanol, ethanol, 1-propanol, 2-propanol, butanol, pentanol, hexanol, heptanol, octanol, allyl alcohol, benzyl alcohol, pinacol, propylene glycol, menthol, catechol, hydroquinone, salicyl alcohol, glycerin. , pentaerythritol, sucrose, glucose, xylitol, methoxyethanol, triethylene glycol monomethyl ether, ethylene glycol, triethylene glycol, tetraethylene glycol, and pentaethylene glycol. The alcohol may be selected from methanol, ethanol, 1-propanol and 2-propanol, or 1-propanol and 2-propanol, optionally 1-propanol.

The method for carrying out the step of heating the mixture containing the fatty acid copper, the reducing compound and the fatty amine is not particularly limited. Examples include a method of mixing a fatty acid copper and a reducing compound with a solvent, further adding an aliphatic amine to the resulting mixture, and heating the mixture; mixing fatty acid copper and an aliphatic amine with a solvent; A method of further adding a reducing compound to the obtained mixture and heating the mixture, and a method of mixing copper hydroxide, fatty acid, reducing compound and aliphatic amine with a solvent and heating the resulting mixture.

The heating temperature may be, for example, 150° C. or lower, 130° C. or lower, or 100° C. or lower. By using fatty acid copper having 9 or less carbon atoms, coated metal particles can be formed at a relatively low temperature.

The shape of the copper-containing particles is not particularly limited, and examples thereof include spherical, approximately spherical, polyhedral, needle-like, flake-like, and rod-like.

The copper-containing particles may contain two or more kinds of copper-containing particles having different shapes. Inclusion of two or more types of copper-containing particles having different shapes tends to suppress cracking of the formed conductive film and facilitate formation of a conductive film having a sufficient thickness. The reason for this is not necessarily clear, but it is believed that two or more different types of copper-containing particles complement each other to suppress the omnidirectional occurrence of volume reduction due to fusion between the copper-containing particles. be done. It is presumed that this suppresses cracking even in a conductive film having a sufficient thickness.

As a combination of copper-containing particles having different shapes, for example, a combination of spherical copper-containing particles (A) and flat copper-containing particles (B) is preferable.

The spherical copper-containing particles (A) may be spherical or substantially spherical, and may have an aspect ratio (major axis/minor axis) of 1 to 1.2. In this specification, "flat shape" means a shape with a relatively large aspect ratio, and in addition to long grains such as ellipsoids or shapes similar thereto, flat plates such as flakes and scales It is used as a term that also includes shape. The flattened copper-containing particles may have an aspect ratio of 3-10. The spherical copper-containing particles and the flat copper-containing particles may be spherical or flat as a whole, and may have fine irregularities on their surfaces.

The median diameter or mode diameter of the spherical copper-containing particles (A) is 0.1 to 2.0 μm, 0.1 to 1.2 μm, 0.3 to 0.9 μm, or 0.1 to 0.6 μm. may The flat copper-containing particles (B) have a median diameter or mode diameter of 0.03 to 9.0 μm, 0.03 to 7.0 μm, 0.03 to 4.0 μm, or 0.03 to 2.5 μm. There may be. By combining the spherical copper-containing particles (A) and the flat copper-containing particles (B) having such a median diameter or mode diameter, there is a tendency for excellent low-temperature fusion bondability.

In the present specification, the median diameter of the copper-containing particles is the D50 value (cumulative median volume distribution) measured with a laser diffraction particle size distribution meter (e.g., Submicron Particle Analyzer N5 PLUS (Beckman Coulter)). means The mode diameter means the particle diameter at which the maximum maximum value is observed in the cumulative distribution of particle diameters (particle size distribution) obtained by a similar method. When the copper-containing particles are the coated copper particles described above, the median diameter or mode diameter of the copper-containing particles means the median diameter or mode diameter in the cumulative distribution of the particle diameters of the entire particles including the organic coating layer.

As the copper-containing particles, commercially available copper particles having a predetermined median diameter or mode diameter can be used. The median diameter and mode diameter of the coated copper particles can be adjusted, for example, by adjusting conditions such as the type of raw materials in the above-described production method, the temperature when mixing the raw materials, the reaction time, the reaction temperature, the washing process, and the washing solvent. can be adjusted.

Ratio of the content of the spherical copper-containing particles (A) to the content of the flat copper-containing particles (B) in the conductor-forming composition [content of the spherical copper-containing particles (A)] / [flat content of copper-containing particles (B)] may be 0.25 to 4.0, 0.3 to 3.0, or 0.4 to 2.5. When the ratio of the content of the spherical copper-containing particles (A) to the content of the flat copper-containing particles (B) is within this range, cracking of the conductive film tends to be more suppressed.

The conductor-forming composition may contain metal particles other than the copper-containing particles. Examples of metal components constituting metal particles include silver, nickel, beryllium, platinum, cobalt, antimony, germanium, thallium, iridium, zinc, niobium, gold, palladium, cadmium, ruthenium, titanium, indium, tungsten, molybdenum, Conductive metal components such as aluminum, lead, bismuth, rhodium, chromium, tin, iron, vanadium and manganese, or alloys containing these metal components can be mentioned. The metal component can be at least one selected from the group consisting of gold and silver and alloys containing these metals from the viewpoint of conductivity, and gold and silver and these metals from the viewpoint of oxidation resistance At least one selected from the group consisting of alloys containing can be used.

The content of the copper-containing particles in the conductor-forming composition may be 20 to 80% by mass based on the total amount of the composition. When the content of the copper-containing particles is 20% by mass or more based on the total amount of the composition, it tends to be possible to form a conductive film having a sufficient thickness. It tends to facilitate the formation of the particle-containing layer. The content of the copper-containing particles may be 30% by mass or more, 40% by mass or more, or 50% by mass or more, based on the total amount of the composition, and is 75% by mass or less, 70% by mass or less, or 65% by mass. It may be below.

The dispersion medium contained in the conductor-forming composition is not particularly limited, and one or more organic solvents can be selected according to the application of the conductor-forming composition. From the viewpoint of viscosity control of the conductor-forming composition, the dispersion medium may contain at least one selected from the group consisting of terpineol, isobornylcyclohexanol, dihydroterpineol and dihydroterpineol acetate. A conductor-forming composition containing these tends to have a viscosity suitable for a printing method.

The viscosity of the conductor-forming composition is not particularly limited, and can be selected according to the method of forming the metal particle-containing layer. For example, when the conductor-forming composition is applied to the bar coating method, the viscosity of the conductor-forming composition may be 0.1 to 30 Pa·s, or 1 to 10 Pa·s. The viscosity of the conductor-forming composition can be measured at 25° C. using an E-type viscometer (eg, manufactured by Toki Sangyo Co., Ltd., product name: VISCOMETER-TV33, applicable cone-plate rotor: SPP).

The conductor-forming composition may optionally contain components other than the copper-containing particles and the dispersion medium. Examples of such components include silane coupling agents, polymeric compounds, radical initiators, and reducing agents.

The conductor-forming composition can be obtained by a method of dispersing copper-containing particles in a dispersion medium.

Examples of methods for forming a metal particle-containing layer on a resin composition layer using a conductor-forming composition include an inkjet method, a super inkjet method, a screen printing method, a transfer printing method, an offset printing method, a jet printing method, and a dispensing method. , jet dispensing method, needle dispensing method, comma coating method, bar coating method, slit coating method, die coating method, gravure coating method, relief printing method, intaglio printing method, gravure printing method, soft lithography method, dip pen lithography method, particles A deposition method, a spray coating method, a spin coating method, a dip coating method, an electrodeposition coating method, and the like can be mentioned.

The shape of the metal particle-containing layer is not particularly limited, and can be appropriately selected depending on the purpose. The thickness of the metal particle-containing layer can be appropriately set depending on the purpose, and may be, for example, 0.2 μm to 50 μm. From the viewpoint of the conductivity and connection reliability of the conductive film to be formed, the thickness of the metal particle-containing layer is more preferably 0.8 μm to 20 μm.

The ratio of the thickness of the resin composition layer to the thickness of the metal particle-containing layer can be appropriately set according to the purpose. 0.1 to 0.7, preferably 0.15 to 0.6 from the viewpoint of adhesion.

(Step S3)
In step S3, by heating the resin composition layer and the metal particle-containing layer, a cured product of the resin composition layer (cured resin product) is formed on the substrate, and the copper-containing particles are sintered to form a conductor. to form a conductive film containing a sintered body of copper-containing particles on the cured resin. As a result, a conductive film is obtained that is adhered to the base material by the cured product of the resin composition layer. When the metal particle-containing layer contains coated copper particles, heating removes the organic substance covering the surfaces of the copper-containing core particles, and the core particles come into contact with each other to achieve conductivity.

The heating temperature may be 120° C. or higher, 250° C. or lower, or 230° C. or lower. When the heating temperature is 120° C. or higher, a cured resin product having sufficient adhesiveness to the substrate can be easily formed, and a conductive film having sufficient conductivity can be easily obtained.

The heating temperature may be constant or may vary regularly or irregularly. The heating time is not particularly limited, and can be selected in consideration of the heating temperature, the heating atmosphere, the amount of copper-containing particles, and the like. From the viewpoint of achieving both sufficient conductivity and mass productivity, the heating time is preferably 5 minutes to 120 minutes. The heating method is not particularly limited, but may be, for example, heating with a hot plate, infrared heater, light irradiation, or pulse laser.

The atmosphere in which the resin composition layer and the metal particle-containing layer are heated is not particularly limited, but may be an inert atmosphere containing an inert gas such as nitrogen and argon, and a reducing substance such as hydrogen and formic acid. It may be a reducing atmosphere or an atmosphere in which both are mixed. Although the pressure is not particularly limited, there is a tendency that heating the metal particle-containing layer in a reduced pressure atmosphere promotes conductivity at a low temperature. The inert gas can suppress the formation of copper oxide on the surface of the copper-containing core particles, and the reducing substance facilitates the detachment of organic substances on the surface of the copper-containing core particles. Sintering (fusion) between core particles can be promoted.

Although the pressure of the atmosphere in which the resin composition layer and the metal particle-containing layer are heated is not particularly limited, it may be under atmospheric pressure or under reduced pressure. Heating the metal particle-containing layer under reduced pressure tends to further promote conductivity at low temperatures.

The volume resistivity of the conductive film to be formed may be 100 μΩ-cm or less, 50 μΩ-cm or less, 20 μΩ-cm or less, or 10 μΩ-cm or less. .

The method for manufacturing the conductive laminate of the present embodiment may include other steps as necessary. Other steps include, for example, a step of reducing oxides generated by heating in a reducing atmosphere after step S3, a step of removing residual components by photobaking after step S3, and a step of applying a load to the conductive film after step S3. and a step of increasing the film thickness by electroplating or electroless plating after step S3.

<Conductive laminate>
The conductive laminate of the present embodiment can be obtained by the above-described method for producing a conductive laminate, and the conductive laminate includes a base material and a conductive film provided on the base material. contains a sintered body of copper-containing particles, and has a cured product of a thermosetting resin composition between the substrate and the conductive film that adheres them. The conductive laminate of the present embodiment can have sufficient adhesiveness between the substrate and the cured product and between the cured product and the conductive film, and the conductive film can easily ensure conductivity.

In the conductive laminate of the present embodiment, the thermosetting resin composition is an epoxy resin having a bisphenol skeleton and a linear hydrocarbon group having 4 or more carbon atoms, and/or a bisphenol skeleton and 3 or more ether bonds. It may contain an epoxy resin having a polyoxyalkylene group containing. In this case, the conductive laminate can have a conductive film that is excellent in both conductivity and adhesiveness to the substrate. In addition, since the cured resin product is rich in flexibility, even if the base material is a film or the like, a highly adhesive conductive laminate can be obtained.

The volume resistivity of the conductive film can be appropriately set according to its application, and may be 500 μΩ·cm or less, 200 μΩ·cm or less, or 100 μΩ·cm or less.

The shape of the conductive film (sintered body) is not particularly limited, and may be thin film, bump, pattern, or the like. The conductive laminate of this embodiment can be used for wiring of various electronic components. In particular, since the conductive laminate can be produced at a low temperature, it is suitably used for forming metal foils, connection terminals, wiring patterns, etc. on base materials with low heat resistance.

<Two-component conductive film forming agent>
The two-component conductive film-forming agent of the present embodiment comprises a component containing a thermosetting resin and a component b containing copper-containing particles. Examples of agent a include the thermosetting resin composition described above. Examples of the b-agent include the conductor-forming composition described above.

The two-component conductive film-forming agent of the present embodiment can be used for forming the resin composition layer and the metal particle-containing layer in the above-described method for producing a conductive laminate of the present embodiment. In the instructions for use of the two-pack type conductive film-forming agent of the present embodiment, each condition in the above-described method for producing a conductive laminate of the present embodiment can be appropriately selected and described. For example, the ratio of the thickness of the resin composition layer to the thickness of the metal particle-containing layer [thickness of the resin composition layer]/[thickness of the metal particle-containing layer] is set to 0.1 to 0.7. can be described.

The two-component conductive film-forming agent of the present embodiment is suitably used for forming metal foils, connection terminals, wiring patterns, etc. on substrates with low heat resistance.

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to these.

(Example 1)
[Preparation of thermosetting resin composition]
40 parts by mass of "EPICLON EXA4816" (manufactured by DIC Corporation, trade name), which is an epoxy resin having a bisphenol A skeleton and a linear hydrocarbon having 6 carbon atoms, is mixed with 60 parts by mass of terpineol (manufactured by Wako Pure Chemical Industries, Ltd.). dissolved in parts. To this solution, "FXR-1081" (manufactured by T&K TOKA Co., Ltd., trade name) was added as a curing agent at a rate of 5 parts by mass with respect to 100 parts by mass of the epoxy resin, and a rotation and revolution stirrer "Awatori Rentaro" was added. (manufactured by THINKY Co., Ltd., trade name) and stirred to obtain a thermosetting resin composition.

[Conductor-forming composition]
<Preparation of copper-containing particles>
As the copper-containing particles, a mixture of spherical copper-containing particles (A) described below and flat copper-containing particles (B) described below at a mass ratio of 70:30 was prepared. In addition, [content of (A)]/[content of (B)] is 70/30.
Spherical copper-containing particles (A): “CH-0200” (manufactured by Mitsui Mining & Smelting Co., Ltd., product name, median diameter (D50): 0.15 μm)
Flat copper-containing particles (B): “1050YF” (manufactured by Mitsui Mining & Smelting Co., Ltd., product name, median diameter (D50): 1.4 μm, aspect ratio (average): 7)

The median diameter (D50) of the particles was measured using a submicron particle analyzer N5 PLUS (manufactured by Beckman Coulter, Inc.).

<Preparation of dispersion medium>
As a dispersion medium, a mixture of terpineol (manufactured by Nippon Terpene Chemical Co., Ltd.) and isobornylcyclohexanol (Nippon Terpene Chemical Co., Ltd.) at a mass ratio of 70:30 was prepared.

Add 24 parts by mass of the dispersion medium prepared above to 76 parts by mass of the copper-containing particles prepared above, and stir using a rotation-revolution stirrer "Awatori Rentaro" (manufactured by Thinky Co., Ltd., trade name). , to obtain a conductor-forming composition.

[Manufacture of conductive laminate]
<Formation of Resin Composition Layer>
The above-mentioned thermosetting resin composition is coated on an LCP substrate "Sumika Super E6007" (manufactured by Sumitomo Chemical Co., Ltd., trade name) using a spin coater "1H-DX1" (manufactured by Mikasa Co., Ltd., trade name). Then, spin coating was performed at a rotation speed of 500 rpm to form a resin composition layer. Thereafter, the resin composition layer was dried by heating in an oven (atmosphere) at 80° C. for 30 minutes. The thickness of the resin composition layer after drying was 15 μm.

<Formation of metal particle-containing layer>
On the resin composition layer after drying, the above-described conductor-forming composition was applied using a bar coater (coating gap: 55 μm) to form a metal particle-containing layer.

<Formation of conductive film>
The substrate comprising the resin composition layer and the metal particle-containing layer formed above is placed in a hydrogen sintering and bonding apparatus (manufactured by Shinko Seiki Co., Ltd.), and heat-treated at 225 ° C. for 90 minutes in a 100% hydrogen atmosphere. rice field. In this way, a conductive laminate was obtained in which a conductive film made of a thin film of metallic copper (sintered copper) was provided on the LCP base material and adhered by the cured resin.

[Evaluation of conductive laminate]
<Measurement of volumetric efficiency>
The volume resistivity of the conductive film is measured with a 4-point stylus surface resistance measuring device “Loresta GP MCP-T610” (manufactured by Mitsubishi Chemical Analytech Co., Ltd., trade name) and the surface resistance value and the contact type step meter “ET200”. (manufactured by Kosaka Seisakusho Co., Ltd., trade name). Table 1 shows the results.

<Measurement of peel strength>
The 90-degree peel strength between the conductive film and the substrate in the conductive laminate was measured by the following method to evaluate the adhesiveness of the conductive film.

Electrolytic copper plating was performed at 2 A/dm ² for 1 hour in an aqueous solution containing copper sulfate, sulfuric acid and hydrochloric acid, using the conductive film of the conductive laminate as a cathode and the phosphorous copper plate as an anode. Next, the metal copper film thickened by electrolytic copper plating was subjected to a metal copper film peel width of 10 mm and a peel angle of 90 using a desktop peel tester (trade name: small desktop tester EZ-S, Shimadzu Corporation). ° and a peel speed of 50 mm/min, and the adhesive strength (N/m) between the substrate and the copper film was measured. Table 1 shows the results.

(Example 2)
A conductive laminate was produced in the same manner as in Example 1, except that a resin composition layer (having a thickness of 10 μm after drying) was formed at a spin coater rotation speed of 1000 rpm, and the same evaluation was performed. Table 1 shows the results.

(Example 3)
A conductive laminate was produced in the same manner as in Example 1 except that a resin composition layer (having a thickness of 5 μm after drying) was formed at a spin coater rotation speed of 2000 rpm, and the same evaluation was performed. Table 1 shows the results.

(Example 4)
A conductive laminate was produced in the same manner as in Example 2 except that a resin composition layer (thickness after drying: 20 μm) was formed by heating in an oven (atmosphere) at 60 ° C. for 30 minutes, and the same evaluation was performed. gone. Table 1 shows the results.

(Example 5)
A conductive laminate was produced in the same manner as in Example 2 except that "JER828" (trade name of Mitsubishi Chemical Corporation) having a bisphenol A skeleton was used as the epoxy resin, and the same evaluation was performed. Table 1 shows the results.

(Comparative example 1)
A conductive laminate was produced in the same manner as in Example 1, except that the resin composition layer was not formed, and the same evaluation was performed. Table 1 shows the results.

As shown in Table 1, the conductive laminates of Examples 1 to 5 are formed with a conductive film having a low volume resistivity, and the conductive laminate of Comparative Example 1, which did not form a resin composition layer, In comparison, it was confirmed that the adhesion between the conductive film and the substrate is excellent. Further, it was confirmed that the conductive laminates of Examples 1 to 4 using the epoxy resin having a straight-chain hydrocarbon group with 4 or more carbon atoms are even more excellent in adhesion between the conductive film and the substrate. rice field.

Claims (5)

A method for producing a conductive laminate comprising a base material and a conductive film provided on the base material, the method comprising:
A step of providing a resin composition layer containing a thermosetting resin on the substrate;
A step of providing a metal particle-containing layer containing copper-containing particles on the resin composition layer;
A conductive film adhered to the substrate by a cured product of the resin composition layer by heating the resin composition layer and the metal particle-containing layer in an inert atmosphere or a reducing atmosphere under atmospheric pressure or under reduced pressure . forming a
with
The thermosetting resin is an epoxy resin having a bisphenol skeleton and a linear hydrocarbon group having 4 or more carbon atoms, and/or an epoxy resin having a bisphenol skeleton and a polyoxyalkylene group containing 3 or more ether bonds. A method for manufacturing a conductive laminate, comprising: The metal particle-containing layer is formed by applying a conductor-forming composition containing the copper-containing particles onto the resin composition layer,
The copper-containing particles include spherical copper-containing particles (A) and flat copper-containing particles (B),
Ratio of the content of the spherical copper-containing particles (A) to the content of the flat copper-containing particles (B) in the conductor-forming composition [content of the spherical copper-containing particles (A)]/[ The method for producing a conductive laminate according to claim 1, wherein the content of flat copper-containing particles (B)] is 0.25 to 4.0 . The conductive laminate according to claim 1 or 2, wherein the copper-containing particles are coated copper particles having a core particle containing copper and an organic coating layer covering at least a part of the surface of the core particle. Production method. The metal particle-containing layer is formed by applying a conductor-forming composition containing the copper-containing particles onto the resin composition layer,
4. The content of the copper-containing particles in the conductor-forming composition is 20 to 80 parts by mass with respect to 100 parts by mass of the conductor-forming composition. The method for producing the conductive laminate according to 1. The method for producing a conductive laminate according to any one of claims 1 to 4, wherein the heating temperature is 100°C to 250°C.