Conductive compositions and their uses

Abstract

The present invention provides a conductive composition that can form a conductive metal film with excellent adhesion, conductivity, and plating resistance, even when fired at relatively low temperatures. [Solution] A conductive composition is prepared containing silver-containing metal nanoparticles (A), silver particles (B), and glass particles (C). The particle size of the silver-containing metal nanoparticles (A) is less than 200 nm. The particle size of the silver particles (B) is 200 nm or more. The mass ratio of the silver-containing metal nanoparticles (A) to the silver particles (B) is 40 / 60 to 99 / 1. The softening point of the glass particles (C) is less than 500°C. A laminate may be prepared containing a substrate and a conductive metal film laminated on at least one surface of the substrate and formed from a sintered body of the conductive composition.

Description

[Technical Field]

[0001] This invention relates to a conductive composition used in the field of electronics for forming circuits on various substrates, and to its applications. [Background technology]

[0002] Conductive compositions (conductive pastes) are widely used in the electronics field because they allow for the easy formation of various patterns, such as electrodes, through printing and other methods. In particular, silver paste, which contains silver in conductive metal powder, is widely used to form electrodes and circuits in electronic components and is broadly classified into resin-curing type and sintering type.

[0003] In resin-curing type conductive compositions, conductivity is ensured when the metal comes into contact with the resin during curing. On the other hand, in sintering type conductive compositions, conductivity is ensured when the metal particles bond together during sintering.

[0004] Sintered conductive compositions contain conductive metal powders such as silver, copper, nickel, palladium, and gold, glass particles as an inorganic binder, a vehicle, a solvent, etc. In general, sintered conductive compositions are fired at a temperature higher than the softening point of the glass particles, causing the conductive metal powder to sinter and form a conductive metal film (sintered film). At the same time, the molten and sintered glass components act as adhesive components that bond the conductive metal film to the substrate. For this reason, sintered conductive compositions are fired at a higher temperature than resin-cured conductive compositions and have superior adhesion to the substrate, resistance to plating (the ability to maintain adhesion to the substrate even after plating), and reliability.

[0005] The firing temperature of a sintered conductive composition is determined by taking into account the heat resistance temperature of the substrate and its surrounding components. That is, when using a highly heat-resistant material such as alumina as the substrate, the firing temperature of the conductive composition can be set to a sufficiently high temperature, while when using a less heat-resistant material such as glass or glass ceramics as the substrate, it is necessary to fire it at a correspondingly lower temperature.

[0006] Recently, due to the excellent formability compared to alumina and the like, and the low dielectric constant, which is suitable for high-frequency device applications, the demand for electronic components based on glass or glass ceramics as substrates has been increasing. Since the heat-resistant temperature of these substrates is about 500 to 600 °C, when using these substrates, the firing temperature needs to be below the heat-resistant temperature of the substrate (about 500 to 600 °C). On the other hand, as glass particles used in a conductive composition capable of corresponding to firing at about 500 to 600 °C, it is necessary to select glass particles with a softening point of 500 °C or less. However, glass particles with a softening point of 500 °C or less often have inferior performance such as plating resistance and water resistance.

[0007] Plating treatment is performed to prevent solder erosion of electrodes, prevent sulfidation, and protect against corrosion. However, when using glass particles with low plating resistance in a conductive composition, the adhesion to the substrate decreases. This is because the glass particles, which are the adhesion components, are eroded by the plating solution during the plating treatment of the metal film after sintering.

[0008] As described above, when firing at a relatively low temperature (about 500 to 600 °C) using a substrate with a low heat-resistant temperature, there is a limit to the options of glass components (glass particles) that can ensure adhesion (plating resistance).

[0009] In response to such problems, Japanese Patent Application Laid-Open No. 2013-182714 (Patent Document 1) proposes a conductive laminate in which an adhesive layer containing metal particles and bismuth-based glass frit with a softening point of 500 °C or less is formed on a substrate (especially a glass substrate), and then a coating layer containing metal nanoparticles and substantially not containing bismuth-based glass frit with a softening point of 50 less than 00 °C is formed on this adhesive layer, so that an Ni plating layer (especially an Ni / Au plating layer) can be formed on the conductive layer while ensuring the adhesion between the substrate (base material) and the conductive layer.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

[0011] However, the method described in Patent Document 1 is inefficient because it requires multiple printing steps to laminate multiple layers, and each conductive paste used to form the layer must be prepared separately.

[0012] Therefore, the object of the present invention is to provide a conductive composition (conductive paste) that can form a conductive metal film (sintered film) with excellent adhesion, conductivity, and plating resistance even when fired at a relatively low temperature (around 500°C).

[0013] Another object of the present invention is to provide a conductive composition (conductive paste) that can form a conductive metal film (sintered film) with excellent adhesion, conductivity, and plating resistance even at relatively low temperatures, and that also has excellent dispersion stability. [Means for solving the problem]

[0014] As a result of diligent research to achieve the above objectives, the inventors have discovered that by combining silver-containing metal nanoparticles (A) and silver particles (B) such that the proportion of silver-containing metal nanoparticles (A) is relatively large compared to the silver particles (B), and further incorporating glass particles (C) with a softening point of less than 500°C, a conductive metal film with excellent adhesion, conductivity, and plating resistance can be formed even with relatively low-temperature firing, thus completing the present invention.

[0015] In other words, the present invention includes the following embodiments.

[0016] Embodiment [1]: A conductive composition comprising silver-containing metal nanoparticles (A), silver particles (B), and glass particles (C), The particle size of the silver-containing metal nanoparticles (A) is less than 200 nm. The particle size of the silver particles (B) is 200 nm or larger. The mass ratio of the silver-containing metal nanoparticles (A) to the silver particles (B) is such that the former / latter = 40 / 60 to 99 / 1. A conductive composition in which the softening point of the glass particles (C) is less than 500°C.

[0017] Embodiment [2]: The conductive composition according to Embodiment [1], wherein the mass ratio of the total amount of the silver-containing metal nanoparticles (A) and the silver particles (B) to the glass particles (C) is the former / latter = 10 / 1 to 200 / 1.

[0018] Embodiment [3]: The conductive composition according to Embodiment [1] or [2], wherein the shape of the silver particles (B) is flake-like, and the mass ratio of the silver-containing metal nanoparticles (A) to the silver particles (B) is former / latter = 60 / 40 to 80 / 20.

[0019] Embodiment [4]: ​​The central particle diameter (D) of the silver-containing metal nanoparticle (A). 50 The diameter of the silver particle (B) is 25-150 nm, and the central particle diameter (D 50 A conductive composition according to any one of the embodiments [1] to [3], wherein the ) is 0.5 to 2 μm.

[0020] Embodiment [5]: The conductive composition according to any one of Embodiments [1] to [4], wherein the silver-containing metal nanoparticles (A) exist as composite nanoparticles compounded with a protective colloid, and the proportion of the protective colloid is 1 to 6 parts by mass per 100 parts by mass of the silver-containing metal nanoparticles (A).

[0021] Embodiment [6]: A laminate comprising a substrate and a conductive metal film laminated on at least one surface of the substrate and formed of a sintered body of the conductive composition described in any of Embodiments [1] to [5].

[0022] Embodiment [7]: The laminate according to Embodiment [6], wherein a plating layer is laminated on the surface of the conductive metal film.

[0023] Embodiment [8]: The laminate according to Embodiment [7], wherein the plating layer is a nickel-plated layer, a nickel-gold-plated layer, or a nickel-palladium-gold-plated layer.

[0024] Embodiment [9]: The laminate according to any of Embodiments [6] to [8], wherein the heat resistance temperature of the substrate is 500 to 600°C.

[0025] Embodiment

[10] : A method for manufacturing a laminate, comprising an adhesion step of adhering a conductive composition according to any of Embodiments [1] to [5] to at least one surface of a substrate, and a firing step of firing the conductive composition adhering to the substrate to form a conductive metal film.

[0026] Embodiment

[11] : The manufacturing method according to Embodiment

[10] , wherein the firing temperature in the firing step is 500 to 600°C.

[0027] In this application, the numerical range represented by "A~B" means "A or greater and B or less," and is used to include the values ​​A and B at both ends of that range. [Effects of the Invention]

[0028] In this invention, silver-containing metal nanoparticles (A) and silver particles (B) are combined such that the proportion of silver-containing metal nanoparticles (A) is relatively large compared to the silver particles (B), and glass particles (C) with a softening point of less than 500°C are also incorporated. As a result, a conductive metal film with excellent adhesion, conductivity, and plating resistance can be formed even with relatively low-temperature firing. Furthermore, by adjusting the particle size of the silver-containing metal nanoparticles (A), the dispersion stability (especially refrigeration stability) of the conductive paste, which is the raw material for the conductive metal film, can be improved. [Modes for carrying out the invention]

[0029] [Conductive composition] The conductive composition of the present invention comprises silver-containing metal nanoparticles (A), silver particles (B), and glass particles (C). The proportion of silver-containing metal nanoparticles (A) is relatively large compared to the silver particles (B), and the softening point of the glass particles (C) is less than 500°C. It is presumed that the above-mentioned effect is achieved through the following mechanism.

[0030] (Action of conductive composition) The conductive composition of the present invention is used to form a metal film (conductive metal film) by sintering on a substrate. Because the glass particles (C) have a low softening point, the glass particles (C) melt and sinter sufficiently even at relatively low temperatures (500°C). As a result, the glass particles (C) become a glass sintered body at the position between the substrate and the metal film, acting as an adhesion component between the metal film and the substrate, ensuring strong adhesion.

[0031] On the other hand, in a metal film, when large-particle-sized silver particles (B) are sintered, voids are created between the particles. However, because silver-containing metal nanoparticles (A) are present, these nanoparticles fill these voids, forming a sintered body that fills the gaps. When a silver sintered body with fewer voids is formed, the density of the metal film (sintered film) increases, resulting in improved conductivity and adhesion to the substrate (or the glass sintered body).

[0032] In particular, in this invention, by including a relatively large amount of silver-containing metal nanoparticles (A), even at low temperatures (500°C) during firing, the silver-containing metal nanoparticles (A) melt and sinter sufficiently, filling the voids between the silver particles (B) at high density and forming a dense metal film (sintered film). Therefore, as demonstrated in the examples described later, the conductivity and adhesion of the metal film can be improved compared to the case where a relatively small amount of silver-containing metal nanoparticles (A) is used.

[0033] Furthermore, when a dense metal film (sintered film) is formed, it functions as a barrier layer when plating is performed on the metal film. In other words, the dense metal film (sintered film) prevents the plating solution from penetrating to the glass sintered body (adhesion component) located at the interface with the substrate, so the glass sintered body is not eroded by the plating solution, and thus adhesion is maintained even after plating. Thus, in this invention, the dense metal film (sintered film) formed by containing a relatively large amount of silver-containing metal nanoparticles (A) has excellent plating resistance.

[0034] On the other hand, when the metal component consists only of silver-containing metal nanoparticles (without large-particle-sized silver particles), as is clear from the results of Comparative Example 3 described later, the proportion of organic protective colloid components of the silver-containing metal nanoparticles increases. If these organic protective colloid components cannot be released during firing and remain in the sintered film, the density becomes insufficient, reducing adhesion and plating resistance. Therefore, in order to form a dense metal film (sintered film) that ensures conductivity and adhesion while also having excellent plating resistance, it has been found that, as in the present invention, it is necessary to increase the proportion of silver-containing metal nanoparticles (A) as the metal component while also allowing silver particles (B) to coexist.

[0035] (Differences from conventional conductive compositions) The conductive composition of the present invention has the following characteristics compared to conventional conductive compositions (conductive pastes), which are broadly classified into resin-cured type and sintered type.

[0036] (1) Characteristics of conventional resin curing type In resin-curing type pastes, an organic resin component is included in the paste, and adhesion to the substrate is ensured by sintering the metal component and curing the organic resin component through a heat treatment of about 100 to 300°C. For example, in Japanese Patent Publication No. 2014-080559 and Japanese Patent Publication No. 2015-162392, an embodiment is disclosed in which the metal component includes metal nanoparticles and large-particle-sized silver particles (silver powder) in order to promote the sintering of silver particles.

[0037] However, when a resin-curing type conductive paste contains both metal nanoparticles and silver powder, the metal nanoparticles are often added as a sintering aid to avoid a decrease in density and conductivity due to the remaining organic protective colloidal components of the metal nanoparticles in the metal film after curing. In such cases, the proportion of silver powder is generally higher than that of metal nanoparticles. For example, in the aforementioned Japanese Patent Publication No. 2014-080559 and Japanese Patent Publication No. 2015-162392, it can be seen that a relatively large amount of silver powder is used. Furthermore, as the curing temperature increases, the difference in sinterability between metal nanoparticles and silver powder decreases, and the benefit of increasing the proportion of silver nanoparticles to improve sinterability is no longer obtained compared to the disadvantage of organic protective colloids remaining in the metal film. Therefore, it is considered common technical knowledge that the proportion of silver powder increases as the curing temperature increases for applications.

[0038] (2) Characteristics of the conventional sintered type In conventional sintered conductive pastes, conductive pastes used to form electrodes on substrates such as alumina can be fired at high temperatures (e.g., 900°C). At high temperatures, sintering is sufficient even if the metal component does not contain nanoparticles (even if it contains only silver powder), and the effect of improving density and conductivity by adding metal nanoparticles is hardly obtained. Therefore, there is little point in adding expensive and unstable metal nanoparticle components. For this reason, sintered conductive pastes generally do not contain metal nanoparticles.

[0039] (3) Features of the present invention Considering the characteristics of conventional conductive pastes, the firing temperature in the present invention is intermediate between the curing temperature of conventional resin-curing types and the firing temperature of conventional sintering types. Therefore, for those skilled in the art, even when incorporating metal nanoparticles, the usual approach and common technical practice is to either increase the amount of silver powder to match the resin-curing type, or further decrease the proportion of metal nanoparticles to match the sintering type. Indeed, Patent Document 1 describes a "conductive paste for forming an adhesive layer" as a composition containing silver nanoparticles, silver powder, and glass particles, stating that it is preferable for the amount of silver powder to be greater than the amount of silver nanoparticles. The examples also state that plating resistance cannot be obtained with a single adhesive layer.

[0040] In contrast, the present invention features a conductive composition (conductive paste) specifically designed for firing at relatively low temperatures (500°C). Contrary to conventional technical standards, it incorporates a large amount of metal nanoparticles, thereby achieving properties of adhesion, conductivity, and plating resistance. In particular, a remarkable effect is observed in terms of plating resistance.

[0041] (Composition of conductive composition) The conductive composition of the present invention comprises silver-containing metal nanoparticles (A), silver particles (B), and glass particles (C).

[0042] (A) Silver-containing metal nanoparticles Silver-containing metal nanoparticles (A) are nanoparticles formed from a silver-containing metal (a metal containing silver). The silver-containing metal may be pure silver or an alloy of silver with another metal. The other metal is not particularly limited as long as it can be alloyed with silver, but examples include Cr, Mo, W, Ni, Pd, Pt, Cu, Au, Zn, In, Sn, and Pb. These other metals can be used individually or in combination of two or more. Of these other metals, Cu is preferred.

[0043] The proportion of silver may be 50% by mass or more in the silver-containing metal, for example, 90% by mass or more, preferably 95% by mass or more, more preferably 97% by mass or more, more preferably 99% by mass or more, and most preferably 100% by mass (pure silver). If the proportion of silver is too low, there is a risk that the conductivity will decrease.

[0044] When the silver-containing metal is a combination of silver and another metal (especially Cu), the proportion of the other metal is, for example, 0.01 to 10 parts by mass, preferably 0.03 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, per 100 parts by mass of silver.

[0045] Silver-containing metal nanoparticles are solidified with adjacent particles in the sintered body, but in the raw material stage before sintering, they are nanometer-sized particles.

[0046] Silver-containing metal nanoparticles (A) are particles with a smaller particle size than silver particles (B), specifically small particles with a particle size of less than 200 nm (i.e., a group of particles in the conductive composition having a particle size distribution in the range of less than 200 nm).

[0047] In other words, the maximum particle diameter (maximum primary particle diameter) of the silver-containing metal nanoparticles (A) is less than 200 nm, preferably 190 nm or less, and more preferably 180 nm or less. If the maximum particle diameter is too large, it may be difficult for the nanoparticles to penetrate the gaps between the silver particles (B).

[0048] In this application, the maximum particle size of the silver-containing metal nanoparticles (A) can be confirmed based on the particle size distribution (volume distribution) measured using a laser diffraction scattering particle size distribution analyzer.

[0049] Center particle diameter of silver-containing metal nanoparticles (A) (50 volume% particle diameter) (D 50The particle size can be selected from a range of approximately 5 to 190 nm, for example, 10 to 180 nm. However, from the viewpoint of improving the dispersion stability (especially refrigeration storage stability) and plating resistance of the conductive paste, which is the raw material for the conductive metal film, 20 to 170 nm (especially 25 to 150 nm) is preferred, for example, 30 to 190 nm, preferably 40 to 150 nm, more preferably 50 to 130 nm, more preferably 70 to 120 nm, and most preferably 80 to 100 nm. If the central particle size is too small, handling may decrease and storage stability may decrease, and if it is too large, conductivity may decrease.

[0050] In this application, the central particle diameter (D) of the silver-containing metal nanoparticle (A) 50 ) can be measured using a transmission electron microscope, and the central particle diameter (D) when any 200 particle diameters are represented by their volume distribution is the central particle diameter. 50 ) will be shown as such.

[0051] The shape of the silver-containing metal nanoparticles (A) is not particularly limited as long as it is granular (or in lump form), and includes spherical (perfectly spherical or nearly spherical), ellipsoidal (ellipsoidal), rod-shaped, cylindrical or conical, polyhedral [for example, polygonal prisms such as cubes and rectangular prisms; polygonal pyramidal shapes such as triangular pyramidal or square pyramidal (pyramidal) shapes], flake-shaped, rod-shaped or rod-shaped, fibrous, dendritic, and irregular shapes. Of these, granular shapes such as spherical and irregular shapes are commonly used.

[0052] A sintered body obtained by firing silver-containing metal nanoparticles (A) only needs to be in a state where the silver-containing metal nanoparticles (A) are solidified together by firing. It may be a sintered body of silver-containing metal nanoparticles (A) obtained using silver-containing metal nanoparticles (A) alone, or a sintered body of silver-containing metal nanoparticles (A) obtained using composite nanoparticles of silver-containing metal nanoparticles (A) and an organic component as raw materials. In the case of a sintered body of silver-containing metal nanoparticles (A) obtained using the composite nanoparticles, a sintered body containing an organic component in addition to the solidified silver-containing metal nanoparticles (A) can be obtained by using the composite nanoparticles. Of these, a sintered body of silver-containing metal nanoparticles (A) obtained using composite nanoparticles with a protective colloid as the organic component is preferred. Using composite nanoparticles containing a protective colloid improves handling and increases the productivity of conductive metal films.

[0053] In composite nanoparticles of silver-containing metal nanoparticles (A) and protective colloid, the composite form of silver-containing metal nanoparticles (A) and protective colloid is not particularly limited, and may be a composite in which the silver-containing metal nanoparticles (A) are attached to or coordinated to the surface of the silver-containing metal nanoparticles (A), or a composite in which the surface of the silver-containing metal nanoparticles (A) is coated. Since silver-containing metal nanoparticles (A) have high coordination ability to protective colloid (or dispersant), the protective colloid may coordinate to the surface of the silver-containing metal nanoparticles (A), thereby coating the silver-containing metal nanoparticles (A) in a composite. When silver-containing metal nanoparticles (A) are composited with protective colloid, the dispersion stability of the silver-containing metal nanoparticles (A) can be improved.

[0054] The protective colloid may be a dispersant, and is often a non-volatile dispersant. In particular, it is preferable that the protective colloid contains a polymeric dispersant having a carboxyl group or a derivative group thereof. In this application, the carboxyl group also includes carboxyl groups in the form of acid anhydride groups.

[0055] The polymer dispersant (or polymer-type dispersant) may have at least carboxyl groups and be capable of dispersing silver-containing metal nanoparticles, and may be an amphiphilic polymer dispersant (or oligomeric dispersant).

[0056] Examples of the aforementioned polymer dispersants include polymer dispersants commonly used for dispersing colorants in the fields of paints and inks. Typical polymer dispersants (amphiphilic polymer dispersants) include water-soluble or water-dispersible resins containing hydrophilic units (or hydrophilic blocks) formed from hydrophilic monomers.

[0057] Examples of the hydrophilic monomers include addition polymerizable monomers such as carboxyl group-containing monomers (unsaturated polycarboxylic acids such as (meth)acrylic acid, maleic acid, and maleic anhydride or their acid anhydrides), sulfo group-containing monomers (such as styrene sulfonic acid), and hydroxyl group-containing monomers (such as hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and vinylphenol); and condensation polymerizable monomers such as ethylene oxide. The condensation polymerizable monomer may form a hydrophilic unit (or block) by reaction with active hydrogen such as a hydroxyl group (for example, the hydroxyl group). The hydrophilic monomers may form a hydrophilic unit (or block) alone or in combination of two or more. Preferred hydrophilic monomers are (meth)acrylic acid, maleic acid, maleic anhydride, and ethylene oxide.

[0058] The polymer dispersant only needs to have at least a carboxyl group, and may also have the functional groups of the hydrophilic monomer, such as an acid group (sulfo group) or a hydroxyl group. These functional groups may be introduced into the polymer dispersant individually or in combination of two or more.

[0059] The polymeric dispersant may contain at least a hydrophilic unit (or hydrophilic block), and may be a single hydrophilic monomer or a copolymer thereof (e.g., polyacrylic acid or a salt thereof), or a copolymer of a hydrophilic monomer and a hydrophobic monomer. Examples of hydrophobic monomers (nonionic monomers) include (meth)acrylic acid esters [(meth)acrylic acid C, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate]. 1-20 (Meth)acrylic monomers such as alkyl, cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, aryl (meth)acrylates such as phenyl (meth)acrylate, benzyl (meth)acrylate, aralkyl (meth)acrylates such as 2-phenylethyl (meth)acrylate; styrene monomers such as styrene, α-methylstyrene, vinyltoluene; α-C 2-20 Olefin monomers such as olefins (ethylene, propylene, 1-butene, isobutylene, 1-hexene, 1-octene, 1-dodecene, etc.); addition polymerizable monomers such as vinyl carboxylate monomers such as vinyl acetate and vinyl butyrate; and C120 3-6 Examples include condensation polymerizable monomers such as alkylene oxides. Hydrophobic monomers may be used alone or in combination of two or more to form hydrophobic units.

[0060] The polymer dispersant for copolymers (e.g., copolymers of hydrophilic monomers and hydrophobic monomers) may be a random copolymer, an alternating copolymer, a block copolymer (e.g., a copolymer composed of a hydrophilic block composed of hydrophilic monomers and a hydrophobic block composed of hydrophobic monomers), a comb copolymer (or comb graft copolymer), etc. The structure of the block copolymer is not particularly limited and may be a diblock structure, a triblock structure (ABA type, BAB type), etc. Furthermore, in the comb copolymer, the main chain may be formed of the hydrophilic block or the hydrophobic block, or it may be formed of a hydrophilic block and a hydrophobic block. Block copolymers of hydrophilic blocks and hydrophobic blocks can also improve silver luster.

[0061] As mentioned above, the hydrophilic unit can also be formed from a hydrophilic block (such as a polyalkylene oxide like polyethylene oxide). The hydrophilic block (such as a polyalkylene oxide) and the hydrophobic block (such as a polyolefin block) may be linked via linking groups such as ester bonds, amide bonds, ether bonds, or urethane bonds. These bonds may be formed, for example, by modifying the hydrophobic block (such as a polyolefin) with a modifying agent [such as an unsaturated carboxylic acid or its anhydride (such as maleic anhydride), lactam or aminocarboxylic acid, hydroxylamine, or diamine], and then introducing the hydrophilic block. Alternatively, a comb copolymer (a comb copolymer whose main chain is composed of hydrophobic blocks) may be formed by reacting (or bonding) a polymer obtained from a monomer having hydrophilic groups such as hydroxyl groups or carboxyl groups (such as the aforementioned hydroxyalkyl (meth)acrylate) with the hydrophilic monomer of the condensation system (such as ethylene oxide).

[0062] Furthermore, the balance between hydrophilicity and hydrophobicity may be adjusted by using hydrophilic nonionic monomers as copolymerization components. Examples of such components include monomers or oligomers having ethylene oxy units, such as 2-(2-methoxyethoxy)ethyl (meth)acrylate and polyethylene glycol mono(meth)acrylate (e.g., number average molecular weight 200-1,000). Alternatively, the balance between hydrophilicity and hydrophobicity may be adjusted by modifying (e.g., esterifying) hydrophilic groups (such as carboxyl groups).

[0063] In polymer dispersants having carboxyl groups, the carboxyl groups may be salts or acid anhydride groups. For example, at least some of the carboxyl groups may form salts (salts with amines, metal salts, etc.). However, polymer dispersants in which acid groups such as carboxyl groups do not form salts [i.e., polymer dispersants having free carboxyl groups] can be suitably used.

[0064] The acid value of a polymeric dispersant having a carboxyl group may be, for example, 1 mg KOH / g or more (e.g., 2 to 100 mg KOH / g), preferably 3 mg KOH / g or more (e.g., 4 to 90 mg KOH / g), more preferably 5 mg KOH / g or more (e.g., 6 to 80 mg KOH / g), and more preferably 7 mg KOH / g or more (e.g., 8 to 50 mg KOH / g), and is usually 3 to 30 mg KOH / g (particularly 5 to 20 mg KOH / g). In addition, the amine value of such a polymeric dispersant may be 0 (or nearly 0).

[0065] In the polymer dispersant, the position of the functional group is not particularly limited and may be located in the main chain, in the side chain, or in both the main chain and the side chain. Such a functional group may be, for example, a functional group derived from a hydrophilic monomer or hydrophilic unit (e.g., a functional group introduced by copolymerization of (meth)acrylic acid, maleic anhydride, ethylene oxide, etc.).

[0066] Polymeric dispersants containing carboxyl groups may be used alone or in combination of two or more types.

[0067] Furthermore, as a polymer dispersant, polymer dispersants (high molecular weight pigment dispersants) described in Japanese Patent Publication No. 2004-207558, etc., may be used. Also, the polymer dispersant may be synthesized or a commercially available product may be used. Specific examples of commercially available polymer dispersants (or dispersants composed of at least an amphiphilic dispersant) include the Solspers series [manufactured by Abyssia Co., Ltd.] such as Solspers 13240, Solspers 13940, Solspers 32550, Solspers 31845, Solspers 24000, Solspers 26000, Solspers 27000, Solspers 28000, Solspers 41090; Dispervic 160, Dispervic-161, Dispervic 162, etc. The Disperbyk series includes models such as Disperbyk 163, Disperbyk 164, Disperbyk 166, Disperbyk 170, Disperbyk 180, Disperbyk 182, Disperbyk 184, Disperbyk 190, Disperbyk 191, Disperbyk 192, Disperbyk 193, Disperbyk 194, Disperbyk 2001, Disperbyk 2015, and Disperbyk 2050 [BIG CHEMMIE Japan] [Manufactured by EFKA Chemical Co., Ltd.]; EFKA-46, EFKA-47, EFKA-48, EFKA-49, EFKA-1501, EFKA-1502, EFKA-4540, EFKA-4550, Polymer 100, Polymer 120, Polymer 150, Polymer 400, Polymer 401, Polymer 402, Polymer 403, Polymer 450, Polymer 451, Polymer 452, Polymer 453 [Manufactured by EFKA Chemical Co., Ltd.]; Azisper PB711, Azisper PA111, Azisper PB811, Azisper PB8 Examples include the Azisper series, such as Azisper PW911 [manufactured by Ajinomoto Co., Inc.]; the Floren series, such as Floren DOPA-158, Floren DOPA-22, Floren DOPA-17, Floren TG-700, Floren TG-720W, Floren-730W, Floren-740W, Floren-745W [manufactured by Kyoeisha Chemical Co., Ltd.]; and the Johncryl series, such as Johncryl 678, Johncryl 679, Johncryl 62 [manufactured by Johnson Polymer Co., Ltd.].Typical polymeric dispersants include Disperbyk 190, Disperbyk 194, Disperbyk 2015, etc.

[0068] When measured by gel permeation chromatography (GPC), the number average molecular weight of the polymeric dispersant is, in terms of polystyrene conversion, for example, 1,500 to 100,000, preferably 2,000 to 80,000 (e.g., 2,000 to 60,000), more preferably 3,000 to 50,000 (e.g., 5,000 to 30,000), and even more preferably 7,000 to 20,000.

[0069] The polymeric dispersant having a carboxyl group may be a polymeric dispersant having no hydroxyl group.

[0070] If necessary, the protective colloid may contain other dispersants. The other dispersants may be inorganic compounds, but usually they are organic compounds. Examples of the other dispersants include alkanols (C alkanemonools such as hexanol, octanol, decanol, dodecanol, octadecanol, etc.), aldehydes (C aliphatic aldehydes such as caprylaldehyde, laurylaldehyde, palmitoaldehyde, etc.), aliphatic hydroxycarboxylic acids, higher fatty acids or their salts, sulfonic acids (such as arenesulfonic acids like alkanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, etc.). These other dispersants may be used alone or in combination of two or more. 6-20 alkane monool), aldehydes (C 6-20 aliphatic aldehyde), aliphatic hydroxycarboxylic acid, higher fatty acid or its salt, sulfonic acids (alkanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, etc. of arenesulfonic acid, etc.). These other dispersants may be used alone or in combination of two or more.

[0071] The proportion of the other dispersant is, for example, 0.1 to 100 parts by mass, preferably 0.5 to 50 parts by mass, and more preferably 1 to 30 parts by mass with respect to 100 parts by mass of the polymeric dispersant.

[0072] The proportion of protective colloid (especially polymer dispersants having carboxyl groups) can be selected from a range of, for example, 0.1 to 10 parts by mass per 100 parts by mass of silver-containing metal nanoparticles (A), preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and more preferably 0.7 to 2 parts by mass. From the viewpoint of improving dispersion stability and plating resistance, for example, 0.5 to 7 parts by mass, preferably 1 to 6 parts by mass, more preferably 1.1 to 3 parts by mass, more preferably 1.2 to 2 parts by mass, and most preferably 1.3 to 1.8 parts by mass. If the proportion of protective colloid is too low, the dispersion stability in the composition may decrease, and if it is too high, the conductivity of the metal film may decrease.

[0073] In this application, the proportion of protective colloids in the composite nanoparticles can be measured by conventional methods, such as thermal analysis (e.g., simultaneous thermogravimetric / differential thermal analysis).

[0074] The proportion of silver-containing metal nanoparticles (A) may be 10% by mass or more in the conductive composition, for example, 10 to 90% by mass, preferably 30 to 80% by mass, more preferably 40 to 75% by mass, more preferably 50 to 70% by mass, and most preferably 55 to 65% by mass. If the proportion of silver-containing metal nanoparticles (A) is too low, the plating resistance and conductivity of the metal film fired at low temperature may decrease.

[0075] The method for producing the composite nanoparticles is not particularly limited, and conventional methods can be used. For example, if the silver-containing metal is elemental silver, the silver compound corresponding to the silver nanoparticles can be prepared by reducing it in a solvent in the presence of a protective colloid and a reducing agent. Specific production methods include, for example, the methods described in Japanese Patent Publication No. 2010-80442 and Japanese Patent Publication No. 2010-229544.

[0076] (B) Silver particles Silver particles (B) are particles with a larger particle size than silver-containing metal nanoparticles (A), specifically large particles with a particle size of 200 nm or more (i.e., a group of particles in the conductive composition having a particle size distribution in the range of 200 nm or more).

[0077] In other words, the minimum particle diameter (minimum primary particle diameter) of the silver particles (B) is 200 nm or larger, preferably 210 nm or larger, more preferably 230 nm or larger, more preferably 250 nm or larger, and most preferably 300 nm or larger. If the minimum particle diameter is too small, there is a risk that the conductivity of the metal film will decrease.

[0078] In this application, the minimum particle size of the silver particles (B) can be confirmed based on the particle size distribution (volume distribution) measured using a laser diffraction scattering particle size distribution analyzer.

[0079] Silver particle (B) central particle diameter (50 volume% particle diameter) (D 50 The particle size can be selected from a range of approximately 0.2 to 5 μm, for example, 0.25 to 4 μm, preferably 0.3 to 3 μm, and from the viewpoint of improving adhesion and plating resistance, for example, 0.4 to 2.3 μm, preferably 0.5 to 2.2 μm, more preferably 0.5 to 2 μm, more preferably 0.6 to 1.5 μm, and most preferably 0.7 to 1 μm. If the central particle size is too small, the conductivity of the metal film may decrease, and if it is too large, the uniformity of the metal film may decrease.

[0080] Silver particles (B) 10 volume% particle size (D 10 The particle size may be, for example, 0.25 μm or larger (e.g., 0.25 to 0.8 μm), for example, 0.3 μm or larger (e.g., 0.3 to 0.75 μm), preferably 0.35 μm or larger (e.g., 0.35 to 0.7 μm), and more preferably 0.4 μm or larger (e.g., 0.4 to 0.6 μm). If the 10% volume particle size is too small, the conductivity of the metal film may decrease.

[0081] Silver particles (B) 90% by volume particle size (D 90 The particle size may be, for example, 3 μm or less (e.g., 0.8 to 3 μm), for example, 2 μm or less (e.g., 0.9 to 2 μm), preferably 1.7 μm or less (e.g., 1 to 1.7 μm), and more preferably 1.5 μm or less (e.g., 1.2 to 1.5 μm). If the 90% volume particle size is too large, the uniformity of the metal film may decrease.

[0082] The central particle diameter (D) of the silver particle (B) 50 ) is the central particle diameter (D) of the silver-containing metal nanoparticle (A). 50 It may be more than twice the original value, for example, 2 to 100 times, preferably 3 to 40 times, more preferably 5 to 20 times, more preferably 6 to 15 times, and most preferably 8 to 12 times.

[0083] Furthermore, in this application, the central particle diameter (D) of the silver particle (B) 50 ), 10% by volume, particle size (D 10 ) and 90% volume particle size (D 90 ) refers to the particle size based on the particle size distribution (volume distribution) measured using a laser diffraction scattering particle size distribution analyzer.

[0084] Examples of the shapes of the silver particles (B) include spherical (perfectly spherical or nearly spherical), ellipsoidal or rod-shaped, cylindrical or conical, polyhedral (e.g., polygonal prisms such as cubes and rectangular prisms; polygonal pyramidal shapes such as triangular pyramidal or square pyramidal), flake-shaped, rod-shaped or rod-shaped, fibrous, dendritic, and irregular shapes. Of these, spherical and flake-shaped are preferred, and flake-shaped are particularly preferred. When the shape of the silver particles (B) is flake-shaped, the density of the conductive metal film can be improved, thereby further improving adhesion, conductivity, and plating resistance.

[0085] In this invention, "flake-like" includes forms (shapes) such as flattened, plate-like, flaky, and scale-like, and also includes forms (shapes) obtained by rolling or crushing three-dimensional silver powder, such as spherical or lumpy, in one direction. When such flake-like silver particles are used, the contact efficiency with adjacent silver particles is high, and conductive paths are easily formed.

[0086] The mass ratio of silver-containing metal nanoparticles (A) to silver particles (B) may be 35 / 65 to 99.5 / 0.5 (particularly 40 / 60 to 99 / 1), preferably 50 / 50 to 90 / 10, and more preferably 55 / 45 to 90 / 10, even more preferably 55 / 45 to 85 / 15 (particularly 57 / 43 to 83 / 17), more preferably 60 / 40 to 80 / 20, and most preferably 65 / 35 to 75 / 25, in order to greatly improve adhesion, conductivity, and plating resistance. If the ratio of silver particles (B) is too low, the conductivity of the metal film may decrease, and if it is too high, the plating resistance and conductivity of the metal film fired at low temperatures may decrease.

[0087] (C) Glass particles In this invention, the glass particles (C) have a softening point of less than 500°C so that they can be sufficiently melted and sintered even at relatively low temperatures. Specifically, the softening point of the glass particles (C) should be less than 500°C, preferably 300 to 495°C, more preferably 400 to 490°C, more preferably 420 to 480°C, and most preferably 430 to 450°C. If the softening point of the glass particles (C) is too low, the shape retention of the sintered film may decrease, and if it is too high, the melting fluidity may decrease, which may reduce the adhesion of the sintered film.

[0088] In this application, the softening point of the glass particles (C) can be determined by using a macro-type differential thermal analyzer (DTA) to determine the temperature of the fourth inflection point.

[0089] As the glass particles (C), conventional glass particles used in conductors can be used, and the composition of the glass constituting the glass particles (C) is not particularly limited, but for example, borosilicate glass represented by the composition formula SiO2-B2O3-MO (wherein M represents an element other than Si and B), aluminosilicate glass represented by the composition formula Al2O3-SiO2-MO (wherein M represents an element other than Al and B), aluminoborosilicate glass represented by the composition formula Al2O3-SiO2-B2O3-MO (wherein M represents an element other than Al, Si and B), composition formula Examples include zinc borosilicate glass represented by the formula ZnO-SiO2-B2O3-MO (wherein M represents an element other than Zn, Si, or B), bismuth-based glass represented by the formula Bi2O3-B2O3-MO (wherein M represents an element other than Bi or B), vanadium-based glass represented by the formula V2O5-MO (wherein M represents an element other than V), phosphoric acid-based glass represented by the formula P2O5-MO (wherein M represents an element other than P), and lead glass represented by the formula PbO2-B2O3-MO (wherein M represents an element other than Pb or B). Of these, bismuth-based glass and phosphoric acid-based glass are preferred because they can improve the adhesion of metal films and the resistance to plating even when fired at low temperatures.

[0090] Glass particle (C) Central particle diameter (D 50 The particle size can be selected from a range of approximately 0.1 to 100 μm, preferably 0.3 to 50 μm, more preferably 0.5 to 30 μm, more preferably 1 to 20 μm, and most preferably 3 to 15 μm. If the central particle size is too small, handling may be reduced, and if it is too large, the adhesion between the metal film and the substrate may be reduced.

[0091] In this application, the central particle diameter (D) of the glass particle (C) 50 ) refers to the particle size based on the particle size distribution (volume distribution) measured using a laser diffraction scattering particle size distribution analyzer.

[0092] Examples of glass particle shapes (C) include spherical (perfectly spherical or nearly spherical), ellipsoidal or rod-shaped, cylindrical or conical, polyhedral (e.g., polygonal prisms such as cubes and rectangular prisms; polygonal pyramidal shapes such as triangular and square pyramidal shapes), flake-shaped, rod-shaped or rod-shaped, fibrous, arboreal, and irregular shapes. Of these, ellipsoidal, polyhedral, and irregular shapes are commonly used.

[0093] In this invention, by blending glass particles (C) with the metal components of silver-containing metal nanoparticles (A) and silver particles (B) in a specific mass ratio, it is possible to achieve both density and adhesion of the conductive metal film, thereby further improving adhesion, conductivity, and plating resistance. In particular, by reducing the voids in the conductive metal film and preventing erosion by the plating solution, plating resistance can be improved.

[0094] Specifically, the mass ratio of the total amount of silver-containing metal nanoparticles (A) and silver particles (B) [(A) + (B)] to the glass particles (C) may be between 10 / 1 and 200 / 1 (particularly 12 / 1 to 190 / 1), for example, 15 / 1 to 180 / 1, preferably 20 / 1 to 170 / 1, more preferably 30 / 1 to 160 / 1, more preferably 50 / 1 to 150 / 1, and most preferably 80 / 1 to 120 / 1. If the ratio of glass particles (C) to the metal component is too small, the adhesion of the metal film may decrease, and if it is too large, the conductivity of the metal film may decrease.

[0095] (D) Resin component The conductive composition of the present invention may further contain a resin component (D) as an organic binder. The resin component (D) is not particularly limited and includes, for example, thermoplastic resins (olefin resins, vinyl resins, acrylic resins, styrene resins, polyether resins, polyester resins, polyamide resins, cellulose derivatives, etc.) and thermosetting resins (thermosetting acrylic resins, epoxy resins, phenolic resins, unsaturated polyester resins, polyurethane resins, etc.). These resin components can be used alone or in combination of two or more. Among these resin components, resins that burn off easily during the firing process and have low ash content are commonly used, such as acrylic resins (polymethyl methacrylate, polybutyl methacrylate, etc.), cellulose derivatives (nitrocellulose, ethylcellulose, butylcellulose, cellulose acetate, etc.), polyethers (polyoxymethylene, etc.), and rubbers (polybutadiene, polyisoprene, etc.), with cellulose derivatives such as ethylcellulose being preferred.

[0096] The proportion of resin component (D) is, for example, 0.1 to 5 parts by mass, preferably 0.3 to 3 parts by mass, more preferably 0.5 to 2 parts by mass, and most preferably 0.8 to 1.5 parts by mass, based on 100 parts by mass of the total amount of silver-containing metal nanoparticles (A) and silver particles (B). If the proportion of resin component (D) is too low, the handling properties of the conductive composition may decrease, and if it is too high, the density of the metal film may decrease.

[0097] (E) Organic solvents The conductive composition of the present invention may further contain an organic solvent (E). The organic solvent (E) is not particularly limited and may be any organic compound that imparts appropriate viscosity to the conductive composition (especially a paste-like composition) and can be easily volatilized by drying after the conductive composition is applied to a substrate, and may be an organic solvent with a high boiling point.

[0098] Examples of such organic solvents include aromatic hydrocarbons (paraxylene, ethylbenzene, trimethylbenzene, naphthalene, cumene, indene, etc.), aliphatic hydrocarbons (hexane, heptane, octane, nonane, etc.), esters (ethyl lactate, texanol, etc.), ketones (isophorone, etc.), amides (dimethylformamide, etc.), aliphatic alcohols (ethanol, isopropanol, butanol, octanol, 2-ethylhexanol, decanol, diacetone alcohol, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates (ethyl cellosolve acetate, butyl cellosolve acetate, etc.), and carbitols (carbitol, methyl carbitol, ethyl carbitol). Examples of organic solvents include ethyl carbitol acetate (ethyl carbitol acetate, butyl carbitol acetate), aliphatic polyhydric alcohols (ethylene glycol, diethylene glycol, dipropylene glycol, butanediol, triethylene glycol, glycerin, etc.), alicyclic alcohols [e.g., cycloalkanols such as cyclohexanol; terpene alcohols such as α-terpineol and dihydroterpineol (monoterpene alcohols, etc.)], aromatic alcohols (metacresol, etc.), aromatic carboxylic acid esters (dibutyl phthalate, dioctyl phthalate, etc.), and nitrogen-containing heterocyclic compounds (dimethylimidazole, dimethylimidazolidinone, etc.). These organic solvents can be used individually or in combination of two or more.

[0099] Among these organic solvents, aliphatic diol monocarboxylates such as texanol (2,2,4-trimethylpentane-1,3-diol monoisobutyrate), aliphatic alcohols such as octanol, alicyclic alcohols such as terpineol, carbitols such as butyl carbitol, and carbitol acetates such as butyl carbitol acetate are preferred from the viewpoint of the fluidity of the conductive composition, with carbitols being particularly preferred.

[0100] The proportion of the organic solvent (E) can be selected from a range of about 0.01 to 50 parts by mass per 100 parts by mass of the total amount of silver-containing metal nanoparticles (A) and silver particles (B), for example, 1 to 30 parts by mass, preferably 3 to 20 parts by mass, more preferably 5 to 15 parts by mass, and most preferably 8 to 13 parts by mass. If the proportion of the organic solvent (E) is too low, the viscosity of the conductive composition may increase and its handling properties may decrease, and if it is too high, the density of the metal film may decrease.

[0101] (F) Other metallic components The conductive composition of the present invention may further contain metal components other than silver-containing metal nanoparticles (A) and silver particles (B) (hereinafter referred to as "other metal components") (F).

[0102] Other metallic components (F) include, for example, metallic components (elemental metals, metallic compounds) of metallic elements selected from the group consisting of Mn, Fe, Cu, Pd, Al, Ni, Mo, W, Pt, Au, Co, Ti, Zr, Sn, etc., and Ag compounds. The elemental metal may be an alloy. The metallic compound (or Ag compound) may be a compound of a metal (or Ag) and a nonmetal (for example, a metal oxide, metal hydroxide, metal sulfide, metal carbide, metal nitride, metal boride, etc.).

[0103] Other metallic components (F) can take various shapes, such as spherical, ellipsoidal or rod-shaped, cylindrical or conical, polyhedral, flake-shaped, rod-shaped or rod-shaped, fibrous, arboreal, or irregular shapes. Of these, ellipsoidal, polyhedral, and irregular shapes are commonly used.

[0104] The central particle diameter (D) of the particles formed by other metal components (F) 50 The particle size is, for example, 0.5 to 30 μm, preferably 1 to 10 μm, and more preferably 1 to 5 μm. If the central particle size is too small, the adhesion to the ceramic substrate may decrease, and if it is too large, the adhesion may similarly decrease.

[0105] The proportion of other metal components (F) is 5 parts by mass or less (for example, about 0.01 to 5 parts by mass) per 100 parts by mass of the total amount of silver-containing metal nanoparticles (A) and silver particles (B).

[0106] (G) Conventional additives The conductive composition of the present invention may further contain conventional additives (G) to the extent that they do not impair the effects of the present invention. Examples of conventional additives (G) include curing agents (such as curing agents for acrylic resins), colorants (such as dyes and pigments), hue modifiers, dye fixatives, gloss enhancers, metal corrosion inhibitors, stabilizers (such as antioxidants and UV absorbers), surfactants or dispersants (such as anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants), dispersion stabilizers, viscosity modifiers or rheology modifiers, humectants, thixotropy enhancers, leveling agents, defoamers, bactericides, and fillers. These other components can be used individually or in combination of two or more. The total proportion of conventional additives (G) is 10 parts by mass or less (for example, about 0.01 to 10 parts by mass) per 100 parts by mass of the total amount of silver-containing metal nanoparticles (A) and silver particles (B).

[0107] [Method for preparing conductive compositions] As a method for preparing the conductive composition (or conductive paste) of the present invention, a conventional mixing method can be used to uniformly disperse each component, and a device with a grinding function (e.g., a three-roll mortar and pestle, a mill, etc.) may also be used. Each component may be added all at once and mixed, or added in stages and mixed.

[0108] [Laminated structure] The laminate of the present invention comprises a substrate and a conductive metal film laminated on at least one surface (particularly one side) of the substrate and formed from a sintered body of the conductive composition.

[0109] The base material is not particularly limited as long as it can withstand the firing temperature; for example, various inorganic materials can be used.

[0110] Inorganic materials include, for example, glass (soda-lime glass, borosilicate glass, crown glass, barium-containing glass, strontium-containing glass, boron-containing glass, low-alkali glass, alkali-free glass, crystallized clear glass, silica glass, quartz glass, heat-resistant glass, etc.), ceramics {metal oxides (alumina or aluminum oxide, zirconia, sapphire, ferrite, titania or titanium oxide, zinc oxide, niobium oxide, mullite, beryllia, etc.), silicon dioxide (quartz, silicon dioxide, etc.), and metal nitrides (aluminum nitride). Examples include titanium nitride, metal carbides (titanium carbide, tungsten carbide, etc.), metal borides (titanium boride, zirconium boride, etc.), silicon nitride, boron nitride, carbon nitride, silicon carbide, boron carbide, metal complex oxides [metal titanates (barium titanate, strontium titanate, lead titanate, niobium titanate, calcium titanate, magnesium titanate, etc.), metal zirconates (barium zirconate, calcium zirconate, lead zirconate, etc.)], metals (aluminum, copper, gold, silver, etc.), and semiconductors.

[0111] Of these, glass and ceramics are preferred, with glass being particularly preferred. Furthermore, the glass may be glass ceramics obtained by crystallizing glass. Furthermore, the ceramics may be low-temperature co-fired ceramics (LTCC). In addition, the substrate formed from ceramics may be a ceramic green sheet.

[0112] The conductive composition of the present invention exhibits excellent conductivity, adhesion, and plating resistance even when fired at 500°C, and therefore the heat resistance temperature of the substrate may be 500 to 600°C (particularly 510 to 600°C). The heat resistance temperature of the substrate can be selected according to the type of material; for glass, it may be the strain point temperature, and for ceramics, it may be the melting point temperature.

[0113] Furthermore, if the substrate is glass, the glass transition temperature of the glass may be 500-600°C (especially 510-600°C).

[0114] The substrate may have undergone surface treatment such as oxidation treatment [surface oxidation treatment, for example, electrical discharge treatment (corona discharge treatment, glow discharge treatment, etc.), acid treatment (chromic acid treatment, etc.), ultraviolet irradiation treatment, flame treatment, etc.], or surface roughening treatment (solvent treatment, sandblasting treatment, etc.).

[0115] The thickness (average thickness) of the base material can be appropriately selected depending on the application, for example, 0.001 to 10 mm, preferably 0.01 to 8 mm, more preferably 0.1 to 5 mm, and more preferably 0.5 to 4 mm.

[0116] The thickness (average thickness) of the conductive metal film can be appropriately selected according to the application. For example, it can be selected from a range of about 0.01 to 10000 μm, preferably 0.01 to 100 μm, more preferably 0.1 to 50 μm, and even more preferably 0.3 to 30 μm.

[0117] A plating layer may be laminated on the surface of the conductive metal film. The plating layer may be a nickel plating (Ni plating) layer, a nickel gold plating (Ni / Au plating) layer, a nickel nickel palladium gold plating (Ni / Pd / Au plating) layer, a tin plating (Sn plating) layer, or a solder plating layer, with the nickel plating layer, nickel gold plating layer, or nickel palladium gold plating layer being preferred.

[0118] The thickness (average thickness) of the plating layer is, for example, 0.01 to 100 μm, preferably 0.05 to 10 μm, and more preferably 0.1 to 5 μm.

[0119] [Method for manufacturing laminates] The laminate of the present invention (a metal film-coated ceramic in which a conductive metal film such as an electrode is formed on a substrate) is obtained by an adhesion step of adhering a conductive composition to at least one surface of the substrate, and a firing step of firing the conductive composition adhering to the substrate to form a conductive metal film (sintered film).

[0120] In the aforementioned adhesion step, the method of adhering the conductive composition can be selected according to the type of substrate. If the substrate is a surface metallized substrate or a through-hole wall metallized substrate, the conductive composition may be applied to the surface of the substrate or the inner walls of the through-holes. In the case of a via-filled substrate, the conductive composition may be filled into the through-holes on both the front and back surfaces (via filling).

[0121] In the adhesion step, a conductive composition may be adhered to the substrate to form a coating film. Conventional coating methods can be used to form the coating film, such as flow coating, dispenser coating, spin coating, spray coating, screen printing, flexographic printing, casting, bar coating, curtain coating, roll coating, gravure coating, dipping, slitting, photolithography, and inkjet. In the coating method, a pattern may be formed (drawn) in the coating film, and a conductive metal film (sintered film) can be formed by firing the formed pattern (drawn pattern) in a firing step. The drawing method (or printing method) for drawing the pattern (coated layer) is not particularly limited as long as it is a printing method capable of forming a pattern, and examples include screen printing, inkjet printing, intaglio printing (e.g., gravure printing), offset printing, intaglio offset printing, and flexographic printing. Of these, screen printing is preferred. In addition, prior to the firing step, a drying treatment may be performed as needed to dry the coating film and remove the organic solvent.

[0122] In the firing process, the conductive composition attached to the substrate is sintered as the metal components are subjected to firing, forming a dense conductive metal film (sintered film). In this invention, the composition ratio (mass ratio) of silver-containing metal nanoparticles (A) and silver particles (B) is 40 / 60 to 99 / 1, so a dense conductive metal film can be formed even at relatively low temperatures (500°C), ensuring high conductivity. Furthermore, the glass particles (C) of the conductive composition melted in the firing process act as adhesion components between the conductive metal film and the substrate, ensuring high adhesion even at relatively low temperatures (500°C). Moreover, when plating, the dense conductive metal film prevents erosion of the glass sintered body (adhesion component) by the plating solution, thus ensuring high plating resistance.

[0123] In the firing process, the firing temperature can be arbitrarily selected depending on the heat resistance temperature of the substrate and its surrounding components, and can be selected from a range of approximately 500 to 1000°C. For example, when using a glass substrate with a strain point temperature of 510 to 600°C as the substrate, if the heat resistance temperature of the substrate is approximately 500 to 600°C, the firing temperature may be approximately 500°C.

[0124] In other words, the conductive composition of the present invention is applicable to a wide range of firing temperatures from low to high temperatures, but even at low firing temperatures of 600°C or lower, it is possible to form a metal film with excellent adhesion, conductivity, and plating resistance. Therefore, it is particularly preferable to use a relatively low firing temperature. Specifically, a preferred firing temperature is 500°C or higher and below the heat resistance temperature of the substrate, for example, 500 to 600°C. If the firing temperature is too high, there is a risk that the substrate will deform or the conductive composition will over-sinter. If the firing temperature is too low, there is a risk that the adhesion and conductivity will be impaired.

[0125] In the firing process, such low firing temperatures are required not only when the heat resistance temperature of the base material is 600°C or lower, but also when the heat resistance temperature of the base material itself is greater than 600°C (such as an alumina base material), and when firing is performed with peripheral parts (electrodes, resistors, etc.) attached to the base material. Of these, it is preferable to use this method when the heat resistance temperature of the base material is between 500 and 600°C.

[0126] The firing time is, for example, 1 minute to 3 hours, preferably 10 minutes to 2 hours, and more preferably 30 minutes to 1.5 hours. The firing atmosphere is not particularly limited, but air is preferred. The firing may be carried out using a batch furnace or a belt-conveying tunnel furnace.

[0127] The laminate of the present invention may be subjected to a plating process in which the conductive metal film obtained in the firing process is plated. In the present invention, even after the conductive metal film is plated, adhesion can be maintained and the laminate has excellent resistance to plating.

[0128] Conventional plating methods can be used, and electroless plating treatments such as nickel plating, nickel-gold plating, and nickel-palladium-gold plating are preferably utilized.

[0129] The laminate of the present invention has excellent conductivity, and the resistivity of the conductive portion may be 3 μΩ·cm or less (for example, 1 to 3 μΩ·cm). [Examples]

[0130] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0131] [Materials used] Carboxyl group-containing polymer dispersant: Disperbic 190, manufactured by Bic Chemie; solution of high molecular weight block copolymer containing carboxyl groups; solvent: water; non-volatile components 40%; acid value 10 mg KOH / g; amine value 0 Silver particles B1: Flake-shaped, particle size distribution (D10 ~D 90 ) 0.42~1.25μm, 10 volume% particle size (D 10 ) 0.42 μm, 50 volume % particle size (D 50 ) 0.79 μm, 90 volume % particle size (D 90 ) 1.25 μm Silver particle B2: spherical, particle size distribution (D 10 ~D 90 ) 0.53~1.46μm, 10 volume% particle size (D 10 ) 0.53 μm, 50 volume % particle size (D 50 ) 0.81 μm, 90 volume % particle size (D 90 ) 1.46 μm Silver particles B3: Flake-shaped, particle size distribution (D 10 ~D 90 ) 1.0~3.5μm, 10 volume% particle size (D 10 ) 1.0 μm, 50 volume% particle size (D 50 ) 2.0 μm, 90 volume % particle size (D 90 ) 3.5 μm Silver particles B4: flake-like, particle size distribution (D 10 ~D 90 ) 1.2~6.3μm, 10 volume% particle size (D 10 ) 1.2 μm, 50 volume % particle size (D 50 ) 2.6 μm, 90 volume % particle size (D 90 ) 6.3 μm Glass particle C1: Bismuth-based glass particle, composition Bi2O3-ZnO-B2O3, softening point 439℃ Glass particles C2: Phosphate-based glass particles, composition P2O5-B2O3-Al2O3-R2O (where R represents an alkali metal), softening point 427°C Glass particles C3: Bismuth-based glass particles, composition Bi2O3-SiO2-B2O3, softening point 550℃ Ethyl cellulose resin: "STD20" manufactured by Dow Chemical Co., Ltd. Butylcarbitol: Manufactured by Fujifilm Wako Pure Chemical Corporation, boiling point 230°C Substrate (glass plate): SCHOTT "TEMPAX Float", strain point temperature 518°C, glass transition temperature (Tg) 525°C, 3.3 mm thick Base material (alumina plate): Heat resistance temperature 1800℃, 0.635mm thick

[0132] [Preparation of composite nanoparticle dispersion] Composite nanoparticle 1 (silver nanoparticle A1 coated with a polymeric dispersant having carboxyl groups) was prepared using the following procedure.

[0133] [Composite nanoparticle 1 (Silver nanoparticle A1 coated with a polymeric dispersant having carboxyl groups)] First, 66.8 g of silver nitrate and 1.6 g of a polymeric dispersant containing carboxyl groups were added to 100 g of deionized water and vigorously stirred to obtain a suspension. To this suspension, 100 g of dimethylaminoethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was gradually added so as not to exceed 50°C, and then heated and stirred in a water bath at 50°C for 4 hours to obtain a composite nanoparticle dispersion.

[0134] Next, an excess amount of methanol was added to the obtained composite nanoparticle dispersion and stirred. The composite nanoparticles were then settled by centrifugation, and the supernatant was removed. Methanol was added again and stirred, and the composite nanoparticles were then settled by centrifugation, and the supernatant was removed. Butyl carbitol was added to the methanol solution containing the precipitate, and the contaminating methanol was removed using an evaporator to obtain a composite nanoparticle dispersion with a silver content of 90% by mass.

[0135] When the particle size of the silver nanoparticle A1 constituting the composite nanoparticles was confirmed in this dispersion using a transmission electron microscope (manufactured by JEOL Ltd.), the particle size at 50% volume (D 50 ) is 90 nm, 10 volume % particle size (D 10 ) is 60 nm, 90 volume% particle size (D 90 The wavelength was 130 nm. Furthermore, when the composite nanoparticle 1 dispersion was vacuum-dried and the resulting composite nanoparticle dry was subjected to thermal analysis using a thermogravimetric differential thermal analysis (TG-DTA) instrument, the content of the organic protective colloid component was investigated. The content of the organic protective colloid component per 100 parts by mass of the metal component (silver nanoparticle A1) in composite nanoparticle 1 was found to be 1.5 parts by mass.

[0136] [Composite nanoparticles 2 (Silver nanoparticles A2 coated with a polymeric dispersant containing carboxyl groups)] In the synthesis of composite nanoparticle 1 dispersion, composite nanoparticle 2 dispersion was prepared in the same manner as composite nanoparticle 1, except that the amount of polymer dispersant used was changed to 8.5 g. When the particle size of silver nanoparticles A2 constituting composite nanoparticle 2 was confirmed by transmission electron microscopy, the 50 volume% particle size (D 50 ) is 10 nm, 10 volume % particle size (D 10 ) is 7nm, 90 volume% particle size (D 90 The n-n

[0137] [Composite nanoparticle 3 (Silver nanoparticle A3 coated with a polymeric dispersant containing carboxyl groups)] In the synthesis of composite nanoparticle 1 dispersion, composite nanoparticle 3 dispersion was prepared in the same manner as for composite nanoparticle 1, except that the amount of polymer dispersant used was changed to 6.4 g. When the particle size of silver nanoparticle A3 constituting composite nanoparticle 3 was confirmed by transmission electron microscopy, the 50 volume% particle size (D 50 ) is 25 nm, 10 volume % particle size (D 10 ) is 19nm, 90 volume% particle size (D 90 The n-n

[0138] [Composite nanoparticle 4 (Silver nanoparticle A4 coated with a polymeric dispersant having carboxyl groups)] In the synthesis of the composite nanoparticle 1 dispersion, the composite nanoparticle 4 dispersion was prepared in the same manner as for composite nanoparticle 1, except that the amount of polymer dispersant used was changed to 1.1 g. When the particle size of the silver nanoparticles A4 constituting composite nanoparticle 4 was confirmed by transmission electron microscopy, the 50 volume% particle size (D 50 ) is 150 nm, 10 volume % particle size (D 10 ) is 102 nm, 90 volume% particle size (D 90 The wavelength was 185 nm. Furthermore, when the content of the organic protective colloid component was examined, the content of the organic protective colloid component in composite nanoparticle 4 was 1.0 part by mass per 100 parts by mass of the metal component (silver nanoparticle A4).

[0139] [Preparation of conductive composition (conductive paste)] Conductive pastes for Examples 1-24 and Comparative Examples 1-5 were prepared to have the compositions shown in Tables 6-11. Specifically, first, the composite nanoparticle dispersion, each powder material, resin material, and organic solvent (butyl carbitol) were weighed into containers in predetermined amounts using an electronic balance. Subsequently, each material was uniformly mixed using a planetary (rotating / revolving) defoaming agitator, and then passed through three rolls to obtain the respective conductive pastes (conductive compositions).

[0140] Furthermore, the particle size distribution (volume distribution) of the composite nanoparticle dispersion and silver particles B1-B4 used in the examples and comparative examples was measured using a laser diffraction scattering particle size distribution analyzer (Microtrac-Bel "MT3000II"). As a result, no particles larger than 200 nm were detected from the silver nanoparticles A1-A4 contained in the composite dispersion. On the other hand, no particles smaller than 200 nm were detected from any of the silver particles B1-B4. In other words, the silver nanoparticles A1-A4 contained in the composite particle nanodispersion as a raw material correspond to silver-containing metal nanoparticles (A) with a particle size of less than 200 nm, and the silver particles B1-B4 correspond to silver particles (B) with a particle size of 200 nm or more. Therefore, in Examples 1-24 and Comparative Examples 4-5, the mass ratio of silver nanoparticles to silver particles B1-B4 in the raw material directly corresponds to the mass ratio of silver-containing metal nanoparticles (A) to silver particles (B) in the composition (mixture).

[0141] [Preparation of evaluation samples] A conductive paste was screen-printed onto a substrate (glass plate) using a screen plate configured to form both a resistance measurement pattern and an adhesion strength measurement pattern. The conductive paste was then applied to the substrate, and the resulting coating was fired at 500°C in an atmospheric environment to obtain a metal-film-coated glass substrate (evaluation sample) with a conductive metal film (sintered film) formed on it. In addition, a metal-film-coated alumina substrate was obtained using the same method, except that an alumina plate was used as the substrate and the firing temperature of the coating was changed to 600°C.

[0142] [Evaluation and Judgment] For each evaluation sample (examples and comparative examples), dispersion stability (viscosity change before and after refrigeration), adhesion (adhesion strength), plating resistance (adhesion strength after plating), and conductivity (resistivity) were verified to determine whether or not the problem of the present invention could be solved.

[0143] [Dispersion stability (viscosity change before and after refrigeration)] The viscosity of each conductive paste (Examples, Comparative Examples) immediately after preparation was measured using a Type B rotational viscometer (Blookfield "DV-2+PRO") at a sample temperature of 25°C and a rotation speed of 10 rpm, and this was defined as the viscosity η before storage. Then, each conductive paste was left to stand in a refrigerator (set temperature 5°C) for 96 hours, and the viscosity after standing (after refrigerated storage) was measured under the same conditions, and this was defined as the viscosity η' after storage. From the obtained viscosities η and η', the viscosity change rate [(η'-η) / η absolute value] before and after refrigerated storage was calculated and evaluated according to the judgment criteria shown in Table 1. From the viewpoint of dispersion stability, a rating of c or higher was considered acceptable.

[0144] [Table 1]

[0145] [Adhesion] A tinned soft copper wire (peel wire) was soldered to the surface of a conductive metal film (sintered film) on which a pattern for measuring adhesion strength (2 mm square pad pattern) was formed. The soft copper wire was bent vertically upward at the end of the pad and fixed to a tensile testing machine, and pulled up until the pad peeled off the substrate. The highest load at which the pad peeled off the substrate was recorded as the peel strength (peel strength of the 2 mm square pattern) and used as the adhesion strength. A peel strength (adhesion strength) of 2.0 kgf or higher means that the peel strength (adhesion strength) per 1 mm square of pattern is 0.5 kgf or higher. If the electrode peeled off simply by lifting the peel wire, it was recorded as 0 kgf. The adhesion strength in each example and comparative example was measured on 10 samples for each evaluation sample, the average value was calculated, and it was evaluated according to the judgment criteria shown in Table 2. From the viewpoint of adhesion, a rating of C or higher was considered acceptable.

[0146] [Table 2]

[0147] [Plating resistance] For evaluation samples in which a conductive metal film (sintered film) with an adhesion strength measurement pattern (2 mm square pad pattern) was formed and subjected to electroless plating (nickel-palladium-gold plating), the peel strength (adhesion strength) was measured using the same method as for adhesion evaluation, and the adhesion strength after plating was evaluated according to the judgment criteria shown in Table 3. From the viewpoint of plating resistance, a rating of C or higher was considered acceptable.

[0148] [Table 3]

[0149] [Conductive] The resistance of conductive metal films with a resistance measurement pattern (a rectangular pattern with a width of 1 mm, a length of 5 mm, and a film thickness of 10 μm) formed on them was measured at 25°C. The surface resistance and film thickness were then converted to resistivity using the four-terminal method, and these values ​​were evaluated accordingly. For each example and comparative example, resistivity was measured for 10 samples, and the average value was calculated and evaluated according to the criteria shown in Table 4. From a conductivity standpoint, a rating of C or higher was considered acceptable.

[0150] [Table 4]

[0151] [Overall assessment] Based on the evaluation of each evaluation item, an overall evaluation was performed according to the criteria shown in Table 5.

[0152] [Table 5]

[0153] [Verification Results and Discussion] The verification results are shown in Tables 6-11.

[0154] [Table 6]

[0155] Referring to Table 6, we will explain in detail the results, primarily for firing at 500°C (substrate: glass plate).

[0156] (Comparative Examples 1-2) Comparative Examples 1 and 2 are examples in which the metal component of the conductive composition consists only of silver particles [silver powder (silver flake powder or silver sphere powder)] and does not use silver nanoparticles. In Comparative Examples 1 and 2, the sintering of the conductive metal film was insufficient at 500°C, resulting in insufficient adhesion and plating resistance, leading to a D rating (failure), and an overall rank of D. In particular, the density of the sintered film was insufficient, creating voids in the metal film, and the plating solution that penetrated through these voids eroded the glass component (the component that adheres the metal film to the substrate), which has poor plating resistance. As a result, the adhesion strength after plating was extremely low, and the use of the conductive compositions of Comparative Examples 1 and 2 at 500°C firing was completely impossible for applications requiring plating.

[0157] (Comparative Example 3) Comparative Example 3 is an example in which the metal component of the conductive composition consists only of silver nanoparticles and no silver particles are used. In Comparative Example 3, by using silver nanoparticles as the metal component, the density of the conductive metal film increased even after firing at 500°C, and a slight improvement in adhesion and conductivity was observed. However, in Comparative Example 3, because only silver nanoparticles were used as the metal component, the protective colloid component also increased and remained in the sintered film, resulting in insufficient density of the sintered film. Consequently, the adhesion strength after plating was only 1.3 kgf, which is not sufficient, and the plating resistance was insufficient, resulting in a D rating (failure), and an overall rank of D. From these results, the conductive composition of Comparative Example 3 did not reach a level sufficient for practical use in applications requiring plating after firing at 500°C.

[0158] (Comparative Example 4) Comparative Example 4 is based on Comparative Example 1, and is designed to incorporate silver nanoparticles as a sintering aid to promote the sinterability of silver particles in the conductive composition. Specifically, it includes both silver nanoparticles and silver powder (silver flake powder) in the metal component, with a composition ratio (mass ratio) of silver nanoparticles to silver powder of 30 / 70. In Comparative Example 4, where the ratio of silver nanoparticles to silver powder in the metal component was 30 / 70, a slight improvement in conductivity was observed, but the adhesion still did not reach a practical level. Furthermore, the adhesion strength after plating did not improve at all, resulting in a d rating (failure) for both, and thus an overall rank of D. From the results of Comparative Example 4, it can be concluded that even when the metal component of the conductive composition includes both silver nanoparticles and silver powder (silver flake powder), and the composition ratio (mass ratio) is silver nanoparticles / silver powder = 30 / 70, no improvement in adhesion or plating resistance was observed.

[0159] (Examples 1-7) Examples 1 to 7 are based on the conductive composition of Comparative Example 4, which has a composition ratio (mass ratio) of silver nanoparticles / silver particles (silver flake powder) of 30 / 70, but with an increased proportion of silver nanoparticles as the metallic component. In Example 1, where the ratio of silver nanoparticles / silver powder as the metallic component was 40 / 60, a dense sintered film was formed during firing at 500°C, resulting in improved adhesion and plating resistance (pass), and an overall rank of C. This is thought to be because the formation of a dense sintered film reduced voids, suppressing the penetration of the plating solution, which corrodes the glass component, into the voids.

[0160] Furthermore, by increasing the proportion of silver nanoparticles in the metallic component, Example 2 (silver nanoparticles / silver powder = 50 / 50) showed improvement in all evaluation items of conductivity, adhesion, and plating resistance, resulting in an overall rank of B. In Examples 3 (silver nanoparticles / silver powder = 60 / 40), 4 (silver nanoparticles / silver powder = 70 / 30), and 5 (silver nanoparticles / silver powder = 80 / 20), where the proportion of silver nanoparticles in the metallic component was further increased, all evaluation items of conductivity, adhesion, and plating resistance improved to an A rating, resulting in an overall rank of A.

[0161] However, in Example 6 (silver nanoparticles / silver powder = 90 / 10), in which the proportion of silver nanoparticles in the metallic component was further increased, the levels of conductivity and plating resistance at 500°C firing decreased to a B rating, resulting in an overall rank of B. In Example 7 (silver nanoparticles / silver powder = 99 / 1), the levels decreased even further, resulting in an overall rank of C.

[0162] As a result of the above experiments, Examples 1 to 7 showed that by including both silver nanoparticles and silver powder in the metal component of the conductive composition, and setting the silver nanoparticle / silver powder composition ratio (mass ratio) in the range of approximately 40 / 60 to 99 / 1, a dense conductive metal film could be formed even after firing at 500°C. Therefore, it was found that a conductive composition capable of forming a conductive metal film with excellent conductivity, adhesion, and plating resistance can be obtained. Furthermore, it was found that by using flake powder instead of silver powder, and setting the silver nanoparticle / silver powder composition ratio (mass ratio) in the range of approximately 60 / 40 to 80 / 20, the density of the conductive metal film is further increased, and a conductive composition capable of forming a conductive metal film with the best conductivity, adhesion, and plating resistance can be obtained.

[0163] Table 6 also includes examples where the substrate was changed to an alumina plate and the firing temperature was changed to 600°C, and the adhesion and plating resistance were evaluated in the same way. The trend was the same at 600°C as at 500°C, and in Comparative Examples 1 to 4, the adhesion strength after plating did not reach a practical level. However, in Examples 1 to 7, in which the metal component of the conductive composition contained both silver nanoparticles and silver powder, and the composition ratio (mass ratio) of silver nanoparticles / silver powder was in the range of approximately 40 / 60 to 99 / 1, the adhesion strength after plating was improved, and a conductive metal film that achieved both adhesion and plating resistance was formed.

[0164] [Table 7]

[0165] (Examples 8-10) This example is based on Example 4, but with the silver nanoparticles changed from A1 to A2-A4, and the particle size of the silver nanoparticles was investigated.

[0166] Silver nanoparticle central particle diameter D 50 Example 8, which had a particle size of 10 nm (8.0 parts by mass of protective colloid per 100 parts by mass of silver nanoparticles), was ranked C, a slightly lower rank, from the viewpoint of plating resistance and dispersion stability. It is thought that the silver nanoparticles with a small particle size were relatively active, and increased viscosity due to aggregation during refrigerated storage, resulting in a change in viscosity (lower dispersion stability). In addition, it is thought that the silver nanoparticles with a small particle size contained a large amount of organic protective colloid, and the density (continuity of the film) of the sintered film decreased due to the increased number of particle interfaces, thus reducing plating resistance.

[0167] On the other hand, the central particle size D of the silver nanoparticles 50 Example 9, where the central particle diameter of the silver nanoparticles is 25 nm (6.0 parts by mass of protective colloid per 100 parts by mass of silver nanoparticles), D 50 In Example 10, where the particle size was 150 nm (1.0 part by mass of protective colloid per 100 parts by mass of silver nanoparticles), the sintered film became dense, resulting in a relatively good level of plating resistance (rating b) and a level of no problems at all in terms of dispersion stability (rating a). Furthermore, in Examples 9 and 10, the adhesion and conductivity were also at a level of no problems at all (rating a).

[0168] Therefore, focusing on the particle size of silver nanoparticles, from the viewpoint of a good balance of dispersion stability, adhesion, plating resistance, and conductivity (rank B or higher), the central particle size of silver nanoparticles D 50 It was found that a wavelength of approximately 25 to 150 nm is preferable. Furthermore, focusing on the amount of protective colloid relative to the silver nanoparticles, it was found that a protective colloid amount of approximately 1 to 6 parts by mass per 100 parts by mass of silver nanoparticles is preferable from the viewpoint of achieving a good balance of dispersion stability, adhesion, plating resistance, and conductivity (rank B or higher).

[0169] [Table 8]

[0170] (Examples 11-14) This is an example of a study that investigated the relationship between the particle size of silver nanoparticles and the ratio of silver nanoparticles to the metal component.

[0171] Examples 11 and 12 show the central particle size D of silver nanoparticles. 50 In Example G, which used 25nm silver nanoparticles A3 and had a silver nanoparticle / silver particle composition ratio (mass ratio) of 70 / 30, the examples also included silver nanoparticle / silver particle ratios of 50 / 50 and 90 / 10. In all cases, the results met practical passing standards in all evaluation items, including plating resistance, and were ranked C or higher (pass) in the overall assessment.

[0172] Furthermore, in Examples 13 and 14, the central particle size D of the silver nanoparticles was 50 In Example 10, 150 nm silver nanoparticles A4 were used, with a composition ratio (mass ratio) of silver nanoparticles to silver particles of 70 / 30. In contrast, examples were given with silver nanoparticle / silver particle ratios of 50 / 50 and 90 / 10. In all cases, practical passing standards were met for all evaluation items, including plating resistance, and the overall judgment was rank C (pass).

[0173] Therefore, in these Examples 11 to 14, the effects of the present invention were obtained, and it was confirmed that a conductive composition (conductive paste) is provided that can form a conductive metal film with excellent adhesion, conductivity, and plating resistance even when fired at a relatively low temperature (500°C).

[0174] [Table 9]

[0175] (Example 15) This example shows a change in the silver particles of Example 4, from B1 to B2, and from flake-shaped silver particles to spherical silver particles. Changing the shape of the silver particles from flake-shaped to spherical resulted in a slight decrease in plating resistance. Therefore, from the viewpoint of plating resistance, it was found that the flake-shaped silver particles are preferable.

[0176] (Examples 16-17) This example is based on Example 4, but with the silver particles changed from B1 to B3-B4, and the particle size of the silver particles was investigated.

[0177] Examples 16-17 show that as the particle size of the silver particles increases, the plating resistance tends to decrease, and the central particle size D of the silver particles 50 Examples 4 and 16, where the central particle size D was within the range of 0.5 to 2.0 μm, showed good results. In detail, the central particle size D 50 In Example 2, which used silver particles B1 of 0.79 μm, the adhesion strength after plating was 2.6 kgf (grade A), whereas D 50 Example 16, which used 2.0 μm silver particles B3, yielded 2.1 kgf (rating b), D 50 In Example 17, which used 2.6 μm silver particles B4, the result was 1.7 kgf (C rating). Also, the central particle diameter D 50 Examples 4 and 16, where the particle size was within the range of 0.5 to 2.0 μm, also showed excellent results (grade A) in other evaluation items.

[0178] Therefore, from the perspective of having a good balance of dispersion stability, adhesion, plating resistance, and conductivity (rank B or higher), the central particle diameter of the silver particles D 50 It was found that a particle size of approximately 0.5 to 2.0 μm is preferable.

[0179] [Table 10]

[0180] (Examples 18-19) This is an example of a study that investigated the relationship between the particle size of silver particles and the ratio of silver nanoparticles to the metallic component.

[0181] Examples 18-19 show the central particle diameter D of the silver particles. 50 In Example 16, 2.0 μm silver particles B3 were used, with a composition ratio (mass ratio) of silver nanoparticles / silver particles of 70 / 30. In contrast, examples were given with silver nanoparticle / silver particle ratios of 50 / 50 and 90 / 10. In all cases, practical passing standards were met for all evaluation items, including plating resistance, and the overall judgment was rank C (pass).

[0182] Therefore, in these Examples 18-19, the effects of the present invention were obtained, and it was confirmed that a conductive composition (conductive paste) is provided that can form a conductive metal film with excellent adhesion, conductivity, and plating resistance even when fired at a relatively low temperature (500°C).

[0183] [Table 11]

[0184] (Examples 20-23) This example is based on Example 4, but with a modified amount of glass particles relative to the total amount of silver components (total amount of silver nanoparticles and silver particles).

[0185] Compared to Example 4, both Examples 20-21, which increased the amount of glass particles, and Examples 22-23, which decreased the amount, showed a decrease in plating resistance. Considering these results, it is thought that in Examples 20-21, where the amount of glass particles was increased, the adhesion between the metal film and the substrate became stronger due to the increased amount of glass components that act as adhesion components to the substrate. However, the relative decrease in the proportion of metal components inhibited the sintering of the metal film, resulting in a decrease in the density of the metal film, and consequently, the adhesion strength did not improve. Furthermore, it is thought that the inclusion of a large amount of glass components, which have poor plating resistance, led to a significant decrease in strength after plating, resulting in reduced plating resistance. On the other hand, in Examples 22-23, where the amount of glass particles was reduced, the adhesion between the metal film and the substrate weakened due to the reduction in glass components that act as adhesion components to the substrate. This is thought to have resulted in a decrease in adhesion strength before plating, and consequently, a decrease in adhesion strength after plating. Specifically, in Examples 21, 4, and 22, where the amount of glass particles relative to the total amount of silver was set to 100 / 10 to 100 / 0.5, and the glass component acting as an adhesion component to the substrate was intentionally kept relatively small to increase the density of the metal film, the adhesion strength after plating was 2.0 kgf or higher (rating of B or higher), and it was found to be suitable from the viewpoint of plating resistance.

[0186] Therefore, from the viewpoint of good plating resistance (rank B or higher), it was found that the amount of glass particles relative to the total amount of silver is preferably 100 / 10 to 100 / 0.5.

[0187] (Example 24) This example is based on Example 4, but with the glass particles changed to glass particles C2, which have a different composition. There were no differences from Example 4 in each evaluation item, confirming that the effects of the present invention can be obtained regardless of the glass composition.

[0188] (Comparative Example 5) This is an example in which the glass particles were changed from Example 4 to glass particles C3 with a softening point of 550°C. In Comparative Example 5, glass particles containing SiO2, which has relatively good plating resistance, were used to attempt to improve plating resistance. However, because the softening point of the glass particles was increased, the glass particles did not soften (melt) at 500°C during firing and did not adhere to the substrate, so it was not a practical solution.

[0189] (Effects obtained) From the results of all the verifications above, it was found that a conductive composition containing silver-containing metal nanoparticles (A), silver particles (B), and glass particles (C), wherein the composition ratio (mass ratio) of silver-containing metal nanoparticles (A) to silver particles (B) is 40 / 60 to 99 / 1, and further adjusting the softening point of the glass particles (C) to less than 500°C, can solve the problem of the present invention. It is possible to form a conductive metal film (sintered film) that is excellent in conductivity and adhesion even when fired at a relatively low temperature (500°C), and also has excellent resistance to plating (adhesion to the substrate can be ensured even after plating), and a conductive composition (conductive paste) with excellent dispersion stability can be provided.

[0190] Furthermore, if the amount of glass particles (C) relative to the total amount of silver components (total amount of silver-containing metal nanoparticles (A) and silver particles (B)) is 100 / 10 to 100 / 0.5, and the shape of the silver particles (B) is flake-like, and the mass ratio of silver-containing metal nanoparticles (A) to silver particles (B) is former / latter = 60 / 40 to 80 / 20, then the central particle diameter (D) of the metal nanoparticles (A) 50The diameter is 25-150 nm, and the central particle diameter (D) of the silver particles (B) is 25-150 nm. 50 When the particle size is 0.5 to 2 μm, and the proportion of the protective colloid is 1 to 6 parts by mass per 100 parts by mass of silver-containing metal nanoparticles (A), it was found that in both cases, a conductive composition (conductive paste) with a superior balance in terms of dispersion stability, adhesion, plating resistance, and conductivity can be provided. [Industrial applicability]

[0191] The conductive composition of the present invention is useful for forming conductive parts (or conductive patterns) on a substrate (or base material) to form a conductive laminate, and can be used particularly effectively as a composition for forming conductive parts such as electrodes in a wiring circuit board.

[0192] The conductive laminate of the present invention can be used for circuit boards, electronic components, thermal substrates, substrates for LED packages, semiconductor substrates, thin-film circuit boards, resistor substrates, and the like.

Claims

1. A conductive composition comprising silver-containing metal nanoparticles (A), silver particles (B), and glass particles (C), The particle size of the silver-containing metal nanoparticles (A) is less than 200 nm. The particle size of the silver particles (B) is 200 nm or more. The mass ratio of the silver-containing metal nanoparticles (A) to the silver particles (B) is such that the former / latter = 40 / 60 to 99 / 1. A conductive composition in which the softening point of the glass particles (C) is less than 500°C.

2. The conductive composition according to claim 1, wherein the mass ratio of the total amount of the silver-containing metal nanoparticles (A) and the silver particles (B) to the glass particles (C) is the former / latter = 10 / 1 to 200 / 1.

3. The conductive composition according to claim 1 or 2, wherein the shape of the silver particles (B) is flake-like, and the mass ratio of the silver-containing metal nanoparticles (A) to the silver particles (B) is former / latter = 60 / 40 to 80 / 20.

4. The central particle diameter (D) of the silver-containing metal nanoparticle (A) ５０ The diameter of the silver particles (B) is 25 to 150 nm, and the central particle diameter (D ５０ The conductive composition according to claim 1 or 2, wherein the thickness is 0.5 to 2 μm.

5. The conductive composition according to claim 1 or 2, wherein the silver-containing metal nanoparticles (A) exist as composite nanoparticles compounded with a protective colloid, and the proportion of the protective colloid is 1 to 6 parts by mass per 100 parts by mass of the silver-containing metal nanoparticles (A).

6. A laminate comprising a substrate and a conductive metal film laminated on at least one surface of the substrate and formed of a sintered body of the conductive composition according to claim 1 or 2.

7. The laminate according to claim 6, wherein a plating layer is laminated on the surface of the conductive metal film.

8. The laminate according to claim 7, wherein the plating layer is a nickel plating layer, a nickel-gold plating layer, or a nickel-palladium-gold plating layer.

9. The laminate according to claim 6, wherein the heat resistance temperature of the substrate is 500 to 600°C.

10. A method for manufacturing a laminate, comprising an adhesion step of adhering the conductive composition according to claim 1 or 2 to at least one surface of a substrate, and a firing step of firing the conductive composition adhering to the substrate to form a conductive metal film.

11. The manufacturing method according to claim 10, wherein the firing temperature in the firing step is 500 to 600°C.

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