Conductive resin composition, electromagnetic wave shield layer, and electronic component

Abstract

The present invention relates to a conductive resin composition containing silver-containing particles as a component (A) and a thermosetting resin and / or a thermoplastic resin as a component (B). The indentation elastic modulus EIT found from a load-displacement curve obtained by means of a nanoindentation test of procedures described in the specification is 10-20 GPa.

Description

Conductive resin composition, electromagnetic wave shielding layer, and electronic component

[0001] The present invention relates to a conductive resin composition, an electromagnetic wave shielding layer, and an electronic component.

[0002] Electronic components such as power amplifiers, Wi-Fi / Bluetooth modules, and flash memory are mounted on circuit boards built into electronic devices such as mobile phones, smartphones, laptops, and tablet computers. These electronic components may malfunction due to external electromagnetic waves. Conversely, electronic components may become a source of electromagnetic noise, causing other electronic components to malfunction.

[0003] In the field of electronic devices, the development of high integration technologies that integrate multiple components into a single component, such as system-on-chip (SoC), system-in-package (SiP), and multi-chip module (MCM), has progressed, and electronic devices have become increasingly smaller and thinner. As electronic devices become smaller and thinner, there is an increasing need to protect against electromagnetic interference (EMI) between components, such as baseband components, radio frequency (RF) components, wireless components, analog devices, and power management components.

[0004] To protect electronic components mounted on a circuit board, methods for forming an electromagnetic wave shielding layer on the surface of the electronic components to block electromagnetic waves have been investigated, and various materials have been investigated. For example, conductive particles such as silver and copper have low electrical resistance and are incorporated into conductive inks used in the manufacture of electronic circuits and coating agents for forming shielding layers that block electromagnetic waves in electronic components. For example, Patent Document 1 discloses a conductive ink that does not contain a polymer or resin binder, but contains nanosilver particles and an adhesion promoter. Furthermore, Patent Document 2 discloses a technique for coating the surface of an electronic component by spraying a coating agent.

[0005] Japanese Patent Publication No. 2014-529674 Japanese Patent Publication No. 2020-143225

[0006] However, conventional spray coating agents used to form electromagnetic wave shielding layers deteriorate over time in high-temperature, high-humidity environments, which may result in reduced adhesion after reliability testing.

[0007] Therefore, an object of the present invention is to provide a conductive resin composition capable of forming an electromagnetic wave shielding layer that has a high electromagnetic wave shielding effect and excellent adhesion after reliability testing.

[0008] The means for solving the above problems are as follows, and the present invention includes the following aspects.

[0009] [1] A conductive resin composition comprising silver-containing particles as component (A), and at least one of a thermosetting resin and a thermoplastic resin as component (B), wherein the indentation modulus E is determined from a load-displacement curve obtained by a nanoindentation test according to the following procedure. ＩＴA conductive resin composition having a modulus of elastic modulus of 10 to 20 GPa. [Procedure] (1) The conductive resin composition is applied to a slide glass and heated at 200°C for 20 minutes to form a coating film having a thickness of 50 μm, thereby obtaining a test piece. (2) A nanoindentation test is performed on the coating surface of the test piece obtained in (1) using a Berkovich indenter under the following conditions: a load is applied to the coating surface of the test piece up to a maximum load of 200 mN over 10 seconds, the maximum load is maintained for 10 seconds, and then the load is released over 10 seconds, thereby obtaining a load-displacement curve. [2] The conductive resin composition according to [1], wherein the component (A) contains silver particles having an average particle size of 100 nm or more and 350 nm or less. [3] The conductive resin composition according to [1] or [2], wherein the component (B) contains an epoxy resin. [4] The conductive resin composition according to any one of [1] to [3], wherein the component (B) contains a flexible skeleton-containing epoxy resin. [5] The conductive resin composition according to [4], wherein the flexible-skeleton-containing epoxy resin contains, in a part of its molecule, at least one flexible skeleton selected from a polyoxyalkylene skeleton, a polyethylene glycol skeleton, a polypropylene glycol skeleton, a polyether skeleton, a polypropylene oxide skeleton, a urethane skeleton, a polybutadiene skeleton, and a nitrile rubber skeleton. [6] The conductive resin composition according to any one of [1] to [5], wherein the content of the component (B) is 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the component (A). [7] The conductive resin composition according to any one of [1] to [6], further comprising a solvent as the component (C). [8] The conductive resin composition according to any one of [1] to [7], further comprising a curing agent as the component (D). [9] The conductive resin composition according to [8], wherein the component (D) contains at least one selected from an acid anhydride-based curing agent, a phenol-based curing agent, and an amine-based curing agent.

[10] The conductive resin composition according to [8] or [9], further comprising a curing accelerator as component (E).

[11] The conductive resin composition according to any one of [1] to

[10] , further comprising carbon particles as component (G).

[12] The conductive resin composition according to

[11] , wherein the average particle size of component (G) is 0.1 to 10 μm.

[13] The conductive resin composition according to

[11] or

[12] , wherein the content of the component (G) is 1 to 50 parts by mass per 100 parts by mass of the component (A).

[14] The conductive resin composition according to

[10] , wherein the maximum value of the exothermic peak in a chart obtained by differential scanning calorimetry of a composition comprising the components (B), (D), and (E) is in the range of 175 to 250°C.

[15] The conductive resin composition according to any one of [1] to

[14] , wherein the viscosity at 25°C and 10 rpm is 10 to 10,000 mPa s.

[16] The conductive resin composition according to any one of [1] to

[15] , wherein the conductive resin composition is for spray application.

[17] The conductive resin composition according to any one of [1] to

[15] , wherein the conductive resin composition is a spray coating agent for electromagnetic wave shielding.

[18] An electromagnetic wave shielding layer formed from the conductive resin composition according to any one of [1] to

[17] .

[19] An electronic component comprising the electromagnetic wave shielding layer according to

[18] .

[0010] According to the present invention, it is possible to provide a conductive resin composition capable of forming an electromagnetic wave shielding layer that has a high electromagnetic wave shielding effect and excellent adhesion after reliability testing.

[0011] FIG. 1 is a view showing a DSC chart of a composition containing components (B), (D), and (E) in Examples 1 and 2 of the conductive resin composition according to an embodiment of the present invention.

[0012] Hereinafter, a description will be given based on embodiments of the conductive resin composition according to the present disclosure. However, the embodiments shown below are merely examples for embodying the technical concept of the present invention, and the present invention is not limited to the following conductive resin composition.

[0013] <Conductive Resin Composition> The conductive resin composition according to an embodiment of the present invention is a conductive resin composition comprising silver-containing particles as component (A), and at least one of a thermosetting resin and a thermoplastic resin as component (B), and has an indentation modulus E obtained from a load-displacement curve obtained by a nanoindentation test according to the following procedure. ＩＴis 10 to 20 GPa. [Procedure] (1) A conductive resin composition is applied to a glass slide and heated at 200°C for 20 minutes to form a coating film with a thickness of 50 μm, thereby obtaining a test piece. (2) A nanoindentation test is performed on the coating surface of the test piece obtained in (1) using a Berkovich-type indenter under the following conditions: a load is applied to the coating surface of the test piece obtained in (1) up to a maximum load of 200 mN over 10 seconds, the maximum load is maintained for 10 seconds, and then the load is released over 10 seconds, and a load-displacement curve is obtained.

[0014] In the embodiment of the present invention, the indentation elastic modulus E ＩＴ represents the ratio of stress to strain in the compressive direction when a Berkovich indenter is pressed.

[0015] The conductive resin composition according to the embodiment of the present invention has an indentation elastic modulus E measured by the above-mentioned specific procedure. ＩＴ When the modulus is 10 to 20 GPa, the cured product (electromagnetic wave shielding layer) absorbs the internal stress caused by the difference in the coefficient of linear thermal expansion between the adherend and the cured product (electromagnetic wave shielding layer), thereby maintaining adhesion even after a reliability test under a high-temperature, high-humidity environment, and making it possible to form an electromagnetic wave shielding layer with excellent durability.

[0016] Indentation elastic modulus E of the conductive resin composition according to an embodiment of the present invention ＩＴ The indentation modulus E must be 10 to 20 GPa, and from the viewpoint of the adhesiveness of the electromagnetic wave shielding layer obtained from the conductive resin composition, it is preferably 12 GPa or more, and more preferably 14 GPa or more. Also, from the viewpoint of the adhesiveness of the electromagnetic wave shielding layer obtained from the conductive resin composition, it is more preferably 18 GPa or less. ＩＴ From the viewpoint of adhesion, the pressure is more preferably 12 to 18 GPa, and particularly preferably 14 to 18 GPa.

[0017] The conductive resin composition according to the embodiment of the present invention may be for spray application. The conductive resin composition according to the embodiment of the present invention may be a spray coating agent for electromagnetic wave shielding. Furthermore, an electromagnetic wave shielding layer can be formed using the conductive resin composition according to the embodiment of the present invention.

[0018] Component (A) (Silver-Containing Particles) The conductive resin composition according to an embodiment of the present invention contains silver-containing particles as component (A). The silver-containing particles are blended to shield electromagnetic waves. The silver-containing particles (hereinafter sometimes referred to as "component (A)" or "silver-containing particles (A)") are not particularly limited, and include silver particles such as silver powder, silver-containing alloy particles, silver-coated particles in which non-silver particles such as carbon particles are coated with silver, and silver-coated particles in which single or alloy metal particles of a ferromagnetic material such as nickel or iron are coated with silver.

[0019] The (A) silver-containing particles may be used alone or in combination of two or more types.

[0020] In an embodiment of the present invention, the (A) silver-containing particles preferably contain metal particles such as silver particles or silver-containing alloy particles, and more preferably contain silver particles. This is because the electrical conductivity of silver is higher than that of other metals. By containing silver particles as the (A) silver-containing particles, a conductive resin composition that exhibits a higher electromagnetic wave shielding effect can be obtained.

[0021] From the viewpoints of sinterability and spray applicability, the silver-containing particles are preferably nano-order silver particles. The average particle size (D50) of the silver-containing particles is preferably 1000 nm or less, more preferably 500 nm or less, even more preferably 350 nm or less, and particularly preferably 150 nm or less. Also, it is preferably 50 nm or more, more preferably 80 nm or more, and even more preferably 100 nm or more. From the viewpoints of sinterability and spray applicability, the average particle size (D50) of the silver-containing particles is preferably 50 nm to 1000 nm, more preferably 80 nm to 500 nm, even more preferably 100 nm to 350 nm, and particularly preferably 100 nm to 150 nm.

[0022] When the average particle size of the silver-containing particles is within the above range, the shielding layer has a dense film structure, which improves conductivity, and the conductive resin composition can be made suitable for spray application. In the conductive resin composition according to the embodiment of the present invention, component (A) preferably contains silver particles having an average particle size of 100 nm or more and 350 nm or less.

[0023] The average particle size of the (A) silver-containing particles can be measured, for example, by observation using a scanning electron microscope (SEM). For example, an SEM photograph or image of the (A) silver-containing particles is obtained at a magnification of 10,000 to 20,000 times, the outlines of the (A) silver-containing particles in the SEM photograph or image are approximated to perfect circles, the diameters of the perfect circles are measured, and the arithmetic mean value of the diameters of 50 arbitrary (A) silver-containing particles can be used as the average particle size.

[0024] The shape of the (A) silver-containing particles is not particularly limited and may be any shape, such as spherical, granular, flake-like, needle-like, or scale-like. When the (A) silver-containing particles are scaly or needle-like, the average major axis length of the scaly or needle-like particles can be used as the average particle size. From the viewpoint of the viscosity and spray applicability of the conductive resin composition, the (A) silver-containing particles are preferably spherical.

[0025] (A) The method for producing silver-containing particles is not particularly limited, and they can be produced by, for example, a reduction method, a pulverization method, an electrolysis method, an atomization method, a heat treatment method, or a combination thereof. For example, silver-containing particles can also be produced by these production methods. Flake-shaped silver-containing particles can be produced, for example, by crushing spherical or granular silver-containing particles using a ball mill or the like.

[0026] Specific examples of the silver-containing particles that can be used include silver powders manufactured by Metalor Technologies USA (product names: P620-7 and P620-24) and silver powders manufactured by Dowa Electronics Co., Ltd. (product name: Ag nano powder-2).

[0027] The (A) silver-containing particles are contained in the conductive resin composition in an amount of preferably 35% by mass to 99% by mass, or alternatively 40% by mass to 98% by mass, or alternatively 45% by mass to 92% by mass, calculated as solids. Note that the amount calculated as solids refers to the resin composition excluding volatile components such as solvents.

[0028] The (A) silver-containing particles may be used as a masterbatch in which they are pre-dispersed in a (C) solvent, which will be described later. The masterbatch is prepared by pre-dispersing the (A) silver-containing particles in a (C) solvent to form a slurry. By using a masterbatch containing the (A) silver-containing particles in a conductive resin composition, the shielding layer has a dense film structure, and adhesion to the surface of electronic components and the like can be improved. When the conductive resin composition further contains a solvent as a (C) component, as will be described later, the (C) solvent may be added to the conductive resin composition in addition to the (C) solvent contained in the masterbatch. Specifically, the masterbatch may be a slurry containing silver particles (product name: nanoAg (SNM-007 (NET 92%)) manufactured by Dowa Electronics Co., Ltd.

[0029] Component (B) (Thermosetting Resin or Thermoplastic Resin) The conductive resin composition according to an embodiment of the present invention contains, as component (B), at least one selected from a thermosetting resin and a thermoplastic resin (hereinafter, sometimes referred to as “component (B)” or “resin (B)”).

[0030] The (B) resin imparts adhesiveness and curability to the conductive resin composition. The (B) resin may include both a thermosetting resin and a thermoplastic resin. The content of the (B) resin is preferably in the range of 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, even more preferably 1.5 to 8 parts by mass, and particularly preferably 2 to 7 parts by mass, per 100 parts by mass of the (A) silver-containing particles. When the content of the (B) resin is in the range of 0.1 to 20 parts by mass, per 100 parts by mass of the (A) silver-containing particles, the conductive resin composition covers and adheres to the entire target, making it easier to form a substantially uniform electromagnetic wave shielding layer.

[0031] The (B) resin can be at least one selected from thermosetting resins and thermoplastic resins. From the viewpoint of adhesiveness and curability, the (B) resin is preferably contained in the conductive resin composition in an amount of 0.5 mass % or more and 10 mass % or less, and may be contained in an amount of 0.8 mass % or more and 4.8 mass % or less.

[0032] The (B) resin contained in the conductive resin composition preferably contains a thermosetting resin. Examples of thermosetting resins include epoxy resins. That is, in the conductive resin composition according to the embodiment of the present invention, the (B) component preferably contains an epoxy resin. The thermosetting resin may be used alone or in combination of two or more.

[0033] The epoxy resin preferably has at least one epoxy group or glycidyl group in the molecule and is liquid at room temperature, and examples of the epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, naphthalene epoxy resin, hydrogenated bisphenol epoxy resin, alicyclic epoxy resin, alcohol ether epoxy resin, cycloaliphatic epoxy resin, fluorene epoxy resin, siloxane epoxy resin, aminophenol epoxy resin, and cresol novolac epoxy resin.

[0034] Furthermore, from the viewpoint of curability and the elastic modulus of the cured product, the epoxy equivalent is preferably 100 to 400 g / eq, more preferably 180 to 350 g / eq. By having the epoxy equivalent within this range, the curability of the resin can be controlled, improving adhesion to the adherend, and making it easier to achieve both electrical conductivity and shielding properties. If the epoxy equivalent of the epoxy resin is 100 g / eq or more, the amount of polar reactive groups is sufficient, improving adhesion to metals and accelerating the resin curing rate, preventing the resin curing from inhibiting sintering of the silver-containing particles or the formation of conductive paths through the silver-containing particles. On the other hand, if the epoxy equivalent is 400 g / eq or less, the reactivity of the epoxy resin is excellent, improving conductivity and shielding properties, and suppressing a decrease in adhesion and durability even if the resin is not cured sufficiently.

[0035] The component (B) preferably contains a flexible skeleton-containing epoxy resin. The epoxy resin may be an epoxy resin having a flexible skeleton (flexible skeleton-containing epoxy resin), and the conductive resin composition may contain an epoxy resin having a flexible skeleton as the resin (B).

[0036] By containing an epoxy resin having a flexible skeleton as the resin (B) in the conductive resin composition, when a coating film is formed from the conductive resin composition, the flexibility of the coating film is increased, and the indentation modulus of elasticity E ＩＴ The epoxy resin having a flexible skeleton may be contained as a main component in the resin (B).

[0037] More specifically, the epoxy resin having a flexible skeleton is preferably an epoxy resin having two or more epoxy groups in one molecule and including at least one flexible skeleton selected from a polyoxyalkylene skeleton, a polyethylene glycol skeleton, a polypropylene glycol skeleton, a polyether skeleton, a polypropylene oxide skeleton, a urethane skeleton, a polybutadiene skeleton, and a nitrile rubber skeleton in a part of the molecule. By using an epoxy resin having a flexible skeleton that has two or more epoxy groups in one molecule and including at least one flexible skeleton selected from a polyoxyalkylene skeleton, a polyethylene glycol skeleton, a polypropylene glycol skeleton, a polyether skeleton, a polypropylene oxide skeleton, a urethane skeleton, a polybutadiene skeleton, and a nitrile rubber skeleton in a part of the molecule, the flexibility of a coating film formed from the conductive resin composition is increased, and the indentation modulus E ＩＴ Among these, from the viewpoint of achieving superior water resistance (hydrolysis resistance), it is preferable to use an epoxy resin containing at least one flexible skeleton selected from a polypropylene oxide skeleton, a urethane skeleton, and a polybutadiene skeleton.

[0038] The entire main resin may contain components that do not have a flexible skeleton, such as bisphenol A epoxy resin or bisphenol F epoxy resin. However, from the viewpoint of setting the indentation modulus EIT within a specific range, these components should be 50% by mass or less of the entire main resin, and it is preferable that the proportion of epoxy resin components with a flexible skeleton is high within this range. The epoxy resin with a flexible skeleton preferably accounts for 50% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass, of the total amount of epoxy resin.

[0039] When the epoxy resin has a flexible skeleton, the indentation modulus of the conductive resin composition is easily adjusted to a specific range, which contributes to improving the adhesion of the electromagnetic wave shielding layer formed from the conductive resin composition.

[0040] Examples of commercially available epoxy resins include bisphenol F epoxy resin (product name: YDF8170) manufactured by Nippon Steel Sumitomo Chemical Co., Ltd., bisphenol A epoxy resin (product name: EXA-850CRP) manufactured by DIC Corporation, bisphenol A and bisphenol F mixed epoxy resin (product name: EXA-835LV) manufactured by DIC Corporation, aminophenol epoxy resin (grade: JER630) manufactured by Mitsubishi Chemical Corporation, cresol novolac epoxy resin (product name: Epiclon N665-EXP) manufactured by DIC Corporation, polypropylene oxide-modified epoxy resin (product name: EP4010S) manufactured by ADEKA Corporation, polybutadiene skeleton-containing epoxy resin (product name: PB3600) manufactured by Daicel Corporation, and urethane skeleton-containing epoxy resin (product name: EPU 7N) manufactured by ADEKA Corporation.

[0041] The resin (B) contained in the conductive resin composition may contain a thermoplastic resin. When the resin (B) contained in the conductive resin composition contains a thermoplastic resin, examples of the thermoplastic resin include at least one selected from the group consisting of polystyrene resin, acrylic resin, polycarbonate resin, polyamide resin, polyamideimide resin, and a thermoplastic elastomer having a glass transition temperature of 25° C. or lower and being liquid or soluble in an organic solvent.

[0042] The acrylic resin is not particularly limited, and examples thereof include polymers obtained by polymerizing one or more monomers selected from acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters. Preferred acrylic resins are polymers obtained by polymerizing acrylic acid or methacrylic acid.

[0043] The polycarbonate resin is not particularly limited, and a polymer obtained by the phosgene method in which a dihydroxydiaryl compound is reacted with phosgene, or the ester exchange method in which a dihydroxydiaryl compound is reacted with a carbonate ester such as diphenyl carbonate can be used.

[0044] The polyamide resin is not particularly limited, and is a polymer containing an amide bond (—NH—CO—) in the main chain of the polymer, and examples thereof include nylon 6, nylon 66, copolymer nylon, and modified nylon such as N-methoxymethylated nylon.

[0045] The polyamide-imide resin is not particularly limited, and examples thereof include those obtained by mixing a tricarboxylic acid anhydride with a diamine compound or a diisocyanate and polycondensing the mixture.

[0046] Examples of liquid thermoplastic elastomers that have a glass transition temperature of 25° C. or lower and are in a liquid state or that can be dissolved in an organic solvent include acrylic rubber, butadiene rubber, silicone rubber, nitrile rubber, etc. As the thermoplastic elastomer, commercially available products produced by known methods may be used, and an example of a commercially available product is carboxyl-terminated butadiene nitrile rubber (product name: HYPRO CTBN 1300×13) manufactured by HUNTSMAN Corporation.

[0047] Component (C) (Solvent) The conductive resin composition according to the embodiment of the present invention may further contain a solvent (hereinafter, sometimes referred to as "component (C)" or "solvent (C)") as component (C). By containing the solvent (C) in the conductive resin composition, the viscosity of the silver-containing particles can be appropriately adjusted, improving spray applicability, and the solvent volatilizes during curing, thereby achieving a thin cured film. The solvent (C) may also be used as a solvent for producing a masterbatch. The solvent (C) in the conductive resin composition according to the embodiment of the present invention may be one type of solvent (C), or may contain two or more types of solvent (C).

[0048] The (C) solvent may be, for example, at least one selected from the group consisting of terpinolene, alkoxysilane, limonene, ethylene glycol monophenyl ether (EPH), diethylene glycol monobutyl ether acetate (Butyl Carbitol Acetate: registered trademark), and diethylene glycol monobutyl ether (Butyl Carbitol: registered trademark). After preparing the masterbatch, a (C) solvent may be further blended to adjust the viscosity of the conductive resin composition. Specific examples of the (C) solvent include a silicone-based alkoxysilane (product name: KBM103) manufactured by Shin-Etsu Silicones Co., Ltd. and ethylene glycol monophenyl ether (product name: Hisolve EPH) manufactured by Toho Chemical Industry Co., Ltd. The amount of the (C) solvent contained in the masterbatch containing the (A) silver-containing particles may be any amount that is sufficient to suppress sedimentation of the (A) silver-containing particles and maintain a slurry state.

[0049] The (C) solvent is preferably contained in the conductive resin composition in an amount of 5 to 150 parts by mass relative to 100 parts by mass of the (A) silver-containing particles. By containing the (C) solvent in the conductive resin composition in an amount of 5 to 150 parts by mass relative to 100 parts by mass of the (A) silver-containing particles, a shielding layer can be formed by spray application, and the evaporation of the (C) solvent allows the formation of a shielding layer having an electromagnetic wave shielding effect. The amount of the (C) solvent contained in the conductive resin composition is preferably in the range of 6 to 100 parts by mass, more preferably in the range of 7 to 50 parts by mass, and particularly preferably in the range of 8 to 30 parts by mass, relative to 100 parts by mass of the (A) silver-containing particles. When the (C) solvent is contained in a masterbatch containing (A) silver-containing particles, the content of the (C) solvent in the conductive resin composition using the masterbatch may be within the range of 4 parts by mass to 100 parts by mass, 5 parts by mass to 80 parts by mass, 6 parts by mass to 70 parts by mass, or 7 parts by mass to 25 parts by mass, per 100 parts by mass of the (A) silver-containing particles in the conductive resin composition.

[0050] Component (D) (Curing Agent) The conductive resin composition according to the embodiment of the present invention may further include a curing agent (hereinafter sometimes referred to as "component (D)" or "(D) curing agent") as component (D). When the (B) resin includes a thermosetting resin, the conductive resin composition preferably further includes a (D) curing agent. That is, the conductive resin composition preferably includes a (B) resin that includes a thermosetting resin and further includes a (D) curing agent. The (D) curing agent preferably includes at least one selected from the group consisting of acid anhydride curing agents, phenolic curing agents, amine curing agents, and imidazole curing agents, more preferably at least one selected from acid anhydride curing agents, phenolic curing agents, and amine curing agents, and even more preferably includes a phenolic curing agent. One (D) curing agent may be used alone, or two or more types may be used in combination. At least one (D) curing agent may be used as the (D) curing agent, and another may be used as the (E) curing accelerator described below.

[0051] Examples of acid anhydride curing agents include phthalic anhydride, maleic anhydride, dodecenylsuccinic anhydride, trimellitic anhydride, benzophenonetetracarboxylic dianhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, etc. Commercially available products include tetrahydrophthalic anhydride (grade: HN2000) manufactured by Hitachi Chemical Co., Ltd., hexahydrophthalic anhydride (grade: HN5500) manufactured by Hitachi Chemical Co., Ltd., and acid anhydrides (grades: YH306, YH307) manufactured by Mitsubishi Chemical Corporation.

[0052] An example of a phenolic curing agent is a phenolic resin. As the phenolic resin, any monomer, oligomer, or polymer having two or more phenolic hydroxyl groups capable of reacting with an epoxy resin can be used. Furthermore, a liquid phenolic curing agent (liquid phenolic resin) is preferred as the phenolic curing agent. By using a liquid phenolic resin as the (D) curing agent, the curing initiation temperature shifts to a higher temperature, which facilitates the removal of solvent from the cured product obtained by curing the conductive resin composition, thereby reducing coating defects such as voids and improving adhesion.

[0053] Examples of phenolic resins include resol-type phenolic resins, phenol novolac resins, cresol novolac resins, bisphenol A-type novolac resins, triazine-modified phenol novolac resins, etc. Commercially available products include novolac-type phenolic resin (product name: RESITOP PSM4324) manufactured by Gun-ei Chemical Co., Ltd. and liquid phenolic resin (product name: XPL4437E) manufactured by Gun-ei Chemical Co., Ltd.

[0054] Examples of the amine curing agent include aliphatic polyamines such as diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, trimethylhexamethylenediamine, and 2-methylpentamethylenediamine; alicyclic polyamines such as isophoronediamine, 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, norbornenediamine, and 1,2-diaminocyclohexane; piperazine-type polyamines such as N-aminoethylpiperazine and 1,4-bis(2-amino-2-methylpropyl)piperazine; and aromatic polyamines such as diaminodiphenylmethane, m-phenylenediamine, m-xylenediamine, diaminodiphenylsulfone, diethyltoluenediamine, trimethylenebis(4-aminobenzoate), and polytetramethyleneoxide-di-p-aminobenzoate. Commercially available products include 3,3'-diethyl-4,4'-diaminodiphenylmethane (product name: KAYAHARD AA (HDAA)) manufactured by Nippon Kayaku Co., Ltd., and aromatic amine (product name: Ethacure 100) manufactured by Albemarle Japan Co., Ltd.

[0055] Examples of imidazole curing agents include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and 1-cyanoethyl-2-undecylimidazole. Modified imidazole curing agents can also be used. Specific examples include epoxy-imidazole adduct compounds and acrylate-imidazole adduct compounds. Commercially available products include an acrylate-imidazole adduct compound (product name: EH2021) manufactured by ADEKA Corporation.

[0056] When an epoxy resin is used as the resin (B), the amount of the curing agent (D) varies depending on the type of epoxy resin and the type of the curing agent (D). The following describes the amount of the curing agent (D) that is suitable for each type of curing agent.

[0057] When the (D) curing agent is an acid anhydride curing agent, it is preferably blended so that the ratio of the acid anhydride equivalent (g / eq) of the (D) curing agent to the epoxy equivalent (g / eq) of the epoxy resin (acid anhydride equivalent / epoxy equivalent) is preferably 0.05 to 10, more preferably 0.1 to 5, and even more preferably 0.5 to 3.

[0058] When the (D) curing agent is a phenolic curing agent, it is preferably blended so that the ratio of the hydroxyl equivalent (g / eq) of the phenolic curing agent to the epoxy equivalent (g / eq) of the epoxy resin (hydroxyl equivalent / epoxy equivalent) is preferably 0.01 to 5, more preferably 0.04 to 1.5, and even more preferably 0.06 to 1.2.

[0059] When the (D) curing agent is an amine-based curing agent, it is preferably blended so that the ratio of the amine value (mg KOH / g) of the amine-based curing agent to the epoxy equivalent (g / eq) of the epoxy resin (amine value / epoxy equivalent) is preferably 0.001 to 3, more preferably 0.01 to 2, and even more preferably 0.05 to 1.5. Here, the amine value refers to the number of mg of potassium hydroxide equivalent in moles to hydrochloric acid required to neutralize 1 g of the solid content of the amine-based curing agent.

[0060] When the (D) curing agent is an imidazole-based curing agent, it is preferable to mix the imidazole-based curing agent in an amount of preferably 0.1 parts by mass or more and 50 parts by mass or less, more preferably 0.25 parts by mass or more and 30 parts by mass or less, and even more preferably 0.5 parts by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the epoxy resin.

[0061] Component (E) (Curing Accelerator) The conductive resin composition according to an embodiment of the present invention may further include a curing accelerator (hereinafter sometimes referred to as "component (E)" or "(E) curing accelerator") as component (E). The curing accelerator is incorporated to accelerate the curing of the thermosetting resin. When an epoxy resin is used as the (B) resin, for example, imidazoles, salts of triphenylphosphine, or tetraphenylphosphine can be used. Specifically, 2-phenyl-4-methyl-5-hydroxymethylimidazole (product name: Curesol 2P4MHZ-PW) manufactured by Shikoku Chemicals Corporation, 2-ethyl-4-methylimidazole (product name: 2E4MZ) manufactured by Shikoku Chemicals Corporation, 2-phenyl-4-methylimidazole (product name: 2P4MZ) manufactured by Shikoku Chemicals Corporation, or the like can be used.

[0062] When the conductive resin composition according to an embodiment of the present invention contains the components (D) and (E), it is preferable that the maximum value of the exothermic peak in the chart (DSC chart) obtained by differential scanning calorimetry (DSC) of a composition consisting of the components (B), (D), and (E) is in the range of 175 to 250°C. Having the maximum value of the exothermic peak in the DSC chart in the range of 175 to 250°C provides the effect of reducing resistance. This is presumably because, as the curing initiation temperature of the thermosetting resin becomes higher, sintering of the silver-containing particles begins first, making the composition less susceptible to the reduced fluidity that accompanies the curing reaction of the thermosetting resin. This leads to the progress of sintering of the silver-containing particles, which in turn makes the composition more susceptible to the reduced resistance. Furthermore, as the curing initiation temperature of the thermosetting resin becomes higher, the solvent in the cured product obtained by curing the conductive resin composition is more easily removed, reducing coating defects such as voids and improving adhesion.

[0063] The conductive resin composition according to the embodiment of the present invention may further contain various additives as the component (F) (hereinafter, these may be referred to as "component (F)" or "additive (F)"). Examples of the additive (F) that may be blended include a silane coupling agent, an antifoaming agent, and a dispersant.

[0064] The silane coupling agent is blended to enhance the heat resistance and adhesive strength of the conductive resin composition, and various silane coupling agents can be used, such as epoxy-based, amino-based, vinyl-based, methacrylic-based, acrylic-based, mercapto-based, etc. Among these, epoxy-based silane coupling agents having an epoxy group and methacrylic-based silane coupling agents having a methacrylic group are preferred.

[0065] Specifically, an epoxy-based silane coupling agent (3-glycidoxypropyltrimethoxysilane) (product name: KBM403) manufactured by Shin-Etsu Chemical Co., Ltd., a methacrylic-based silane coupling agent (3-methacryloxypropyltrimethoxysilane) (product name: KBM503) manufactured by Shin-Etsu Chemical Co., Ltd., or the like can be used.

[0066] When a silane coupling agent is added, it is preferably added in an amount of 0.01 parts by mass or more and 5 parts by mass or less, and more preferably 0.05 parts by mass or more and 3 parts by mass or less, per 100 parts by mass of the (A) silver-containing particles.

[0067] The antifoaming agent is blended to prevent the generation of bubbles in the conductive resin composition, and examples of such antifoaming agents include acrylic, silicone, and fluorosilicone antifoaming agents. Specifically, a silicone antifoaming agent (product name: WACKER AF98 / 1000) manufactured by Wacker Asahi Kasei Silicone Co., Ltd. can be used. When an antifoaming agent is added, it can be added in an amount of 0.001 to 5 parts by mass per 100 parts by mass of the (A) silver-containing particles.

[0068] From the viewpoint of compatibility with other components, the dispersant is preferably at least one selected from the group consisting of acrylic acid-based dispersants, phosphate ester salt-based dispersants, and multifunctional ionic dispersants. When the conductive resin composition contains a dispersant as component (F), the dispersibility of the (A) silver-containing particles and other components in the conductive resin composition can be improved. Examples of acrylic dispersants include polyisobutyl methacrylate. Commercially available phosphate ester salt-based dispersants include BYK-145 manufactured by BYK-Chemie. Examples of multifunctional ionic dispersants include SC1015F from the Marialim (registered trademark) series or Marialim (registered trademark) SC series manufactured by NOF Corporation. The Marialim (registered trademark) series dispersants manufactured by NOF Corporation are multifunctional comb-type dispersants having ionic groups in the main chain and polyoxyalkylene chains in the graft chain. When a dispersant is added, it can be added in an amount of 0.001 to 5 parts by mass per 100 parts by mass of the (A) silver-containing particles.

[0069] By including a dispersant in the conductive resin composition in an amount of 0.5 to 10 parts by mass per 100 parts by mass of the (A) silver-containing particles, sedimentation of the (A) silver-containing particles can be suppressed, and a shielding layer can be formed in a state in which the (A) silver-containing particles are substantially uniformly dispersed. The amount of dispersant included in the conductive resin composition is preferably in the range of 1 to 8 parts by mass, and more preferably in the range of 1.5 to 7 parts by mass, per 100 parts by mass of the (A) silver-containing particles.

[0070] The dispersant as component (F) may be contained in a masterbatch in which the (A) silver-containing particles have been dispersed in advance in a slurry form. When the masterbatch contains a dispersant as component (F), the sedimentation of the (A) silver-containing particles is suppressed, and a shielding layer can be formed in which the (A) silver-containing particles are dispersed substantially uniformly. Even when the dispersant is contained in the masterbatch, it is sufficient that the dispersant is contained in a range of 0.5 parts by mass to 10 parts by mass per 100 parts by mass of the (A) silver-containing particles contained in the conductive resin composition.

[0071] The amount of the additive in the conductive resin composition is preferably in the range of 0.01 to 5 parts by mass, and more preferably in the range of 0.05 to 3 parts by mass, relative to 100 parts by mass of the conductive resin composition. Even when the additive is added to a masterbatch, the amount of the additive in the conductive resin composition to which the masterbatch has been added may be in the range of 0.01 to 5 parts by mass, relative to 100 parts by mass of the conductive resin composition.

[0072] Component (G) (Carbon Particles) The conductive resin composition according to the embodiment of the present invention may further contain carbon particles as component (G). Examples of types of carbon particles include carbon black, ketjen black, acetylene black, carbon nanotubes, graphene, graphite, and fullerene. Graphene is preferred from the viewpoints of improving the toughness of the shielding layer after curing and improving adhesion after reliability testing. Graphene is a substance made of pure carbon in which atoms are arranged in a hexagonal pattern in a densely packed sheet one atom thick.

[0073] In the conductive resin composition according to an embodiment of the present invention, the carbon particles preferably have an average particle size (D50) of 0.1 to 10 μm, more preferably 0.5 to 5 μm, and even more preferably 1 to 3 μm. Having the average particle size of component (G) within this range imparts toughness to the cured shielding layer and also improves spray applicability. When the conductive resin composition contains carbon particles, when the conductive resin composition is applied to an object to form an electromagnetic wave shielding layer, the toughness of the electromagnetic wave shielding layer can be improved, and adhesion after reliability testing can be improved. Examples of commercially available carbon particles include graphite (flake graphite) (product name: CX3000) manufactured by Chuetsu Graphite Industries Co., Ltd., graphene powder (grade: XGnP-R10) manufactured by XG Science, and graphene (product name: GNH-XA) manufactured by Graphene Platform Co., Ltd.

[0074] The content of component (G) in the conductive resin composition is preferably 1 to 50 parts by mass, more preferably 3 to 30 parts by mass, and even more preferably 5 to 25 parts by mass per 100 parts by mass of component (A). When the conductive resin composition contains carbon particles within the above range, the toughness of the electromagnetic wave shielding layer can be improved without reducing the adhesion of the conductive resin composition to the target object, and an electromagnetic wave shielding layer with high electromagnetic wave shielding effect and excellent durability can be formed.

[0075] (Viscosity) The viscosity of the conductive resin composition is preferably 10 mPa·s or more, more preferably 15 mPa·s or more, even more preferably 20 mPa·s or more, even more preferably 25 mPa·s or more, and particularly preferably 30 mPa·s or more, measured at 25 ° C. and 10 rpm using a rotational viscometer (product number: TVE-22H) manufactured by Toki Sangyo Co., Ltd. The upper limit of the viscosity is preferably 10,000 mPa·s or less, more preferably 5000 mPa·s or less, even more preferably 1000 mPa·s or less, even more preferably 900 mPa·s or less, and particularly preferably 850 mPa·s or less. If the viscosity of the conductive resin composition measured at 25 ° C. and 10 rpm is in the range of 10 mPa·s or more and 10,000 mPa·s or less, it is possible to obtain a conductive resin composition that is easy to apply by spraying (atomization). The viscosity of the conductive resin composition can be adjusted by changing the type and blending ratio of the solvent (C). Note that the viscosity in the present invention is measured at 25°C.

[0076] <Method for producing conductive resin composition> The conductive resin composition can be produced, for example, by blending (A) silver-containing particles, (B) resin, optionally (C) solvent, optionally (D) curing agent, optionally (E) curing accelerator, optionally (F) additive, and optionally (G) carbon particles, and stirring and mixing them using a known device. Examples of known devices that can be used include a Henschel mixer, a roll mill, and a three-roll mill. The components constituting the conductive resin composition may be simultaneously added to the device and mixed, or some of the components may be first added to the device and mixed, and the rest may be added to the device and mixed later.

[0077] <Method for Producing a Masterbatch> In an embodiment of the present invention, (A) silver-containing particles and (C) solvent may be mixed and stirred in advance to produce a slurry masterbatch, which may then be used to produce a conductive resin composition. The masterbatch may contain a dispersant as component (F) and may contain other additives as needed. The (A) silver-containing particles and (C) solvent contained in the masterbatch can be mixed and stirred using the known apparatus described above.

[0078] <Application Method> The conductive resin composition according to the embodiment of the present invention can form an electromagnetic wave shielding layer by application or the like. For example, the conductive resin composition can be spray-applied to an electronic component or the like to form an electromagnetic wave shielding layer on the outer surface of the electronic component or the like. The conductive resin composition can also be applied to the electronic component using, for example, a conventionally known spray coating machine. The conductive resin composition can also be filled in an aerosol can or the like and applied. The thickness of the electromagnetic wave shielding layer formed by spray-applying the conductive resin composition to an electronic component may be in the range of 0.5 μm to 30 μm, or in the range of 0.5 μm to 20 μm, or in the range of 0.5 μm to 10 μm.

[0079] <Electromagnetic Shielding Layer> The electromagnetic shielding layer according to the embodiment of the present invention is an electromagnetic shielding layer formed from the conductive resin composition described above. The electromagnetic shielding layer according to the embodiment of the present invention can be formed from the conductive resin composition described above, and is preferably formed by spray coating using the conductive resin composition. The electromagnetic shielding layer formed from the conductive resin composition according to the embodiment of the present invention has an excellent electromagnetic shielding effect and can effectively shield electromagnetic waves. The electromagnetic shielding layer according to the embodiment of the present invention has an electromagnetic shielding effect of 37 dB or more, preferably 50 dB or more, and particularly preferably 60 dB or more. This electromagnetic shielding effect can be measured in accordance with ASTM D4935.

[0080] From the viewpoint of heat dissipation of components, the electromagnetic wave shielding layer according to an embodiment of the present invention preferably has a thermal conductivity of 7 W / mK or more, more preferably 14 W / mK or more, and even more preferably 16 W / mK or more. While methods such as increasing the content of silver-containing particles or treating at high temperatures to promote sintering of the silver-containing particles are conceivable to improve thermal conductivity, both methods may result in embrittlement of the coating film and reduced adhesion. Therefore, from the viewpoint of adhesion and coating film strength, the thermal conductivity is preferably 400 W / mK or less, more preferably 100 W / mK or less, and even more preferably 40 W / mK or less. This thermal conductivity is the value measured at 25°C using a NETZSCH LFA447 flash analyzer. The specific heat used in the calculation can be measured by DSC using a NETZSCH DSC204F1 differential scanning calorimeter on a cured product, and the specific gravity of the cured product can be measured by the Archimedes method.

[0081] The electromagnetic wave shielding layer formed from the conductive resin composition according to the embodiment of the present invention has a tape adhesion of 4B or more in both the tape adhesion and reliability tests shown in the following examples. By having such tape adhesion, the electromagnetic wave shielding layer formed on the outer surface of an electronic component is less likely to peel off.

[0082] <Electronic Component> An electronic component according to an embodiment of the present invention includes an electromagnetic wave shielding layer according to an embodiment of the present invention. The conductive resin composition according to an embodiment of the present invention can be applied to an electronic component by spray coating or the like. The present invention also relates to an electronic component using the above-described conductive resin composition. Examples of electronic components using the conductive resin composition according to an embodiment of the present invention include power amplifiers, Wi-Fi / Bluetooth modules, flash memories, and the like used in electronic devices such as mobile phones, smartphones, laptops, and tablet devices. When using the conductive resin composition for an electronic component, the conductive resin composition may be applied to individual electronic components and then mounted on a substrate, or the conductive resin composition may be applied after mounting each electronic component on a substrate.

[0083] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0084] The following raw materials were used to produce the conductive resin compositions of the Examples and Comparative Examples.

[0085] (A) Silver-containing particles A1: nanoAg (SNM-007 (NET 92%)), spherical, average particle size 100 nm, BC (butyl carbitol) slurry, manufactured by Dowa Electronics Co., Ltd. (In Tables 1 and 2, the amount used was calculated by removing 8% by mass of diethylene glycol monobutyl ether (butyl carbitol: registered trademark) as a solvent from the nano-Ag slurry.) The average particle size of the (A) silver-containing particles was measured using a scanning electron microscope (SEM). 50 particles were randomly selected from SEM photographs or SEM images magnified at 10,000 to 20,000 times, the outline of each particle was approximated to a perfect circle, and the diameter of the perfect circle was measured. The arithmetic average value was used as the average particle size. When the (A) conductive filler was shaped like a flake (scale), the average major axis length of 50 randomly selected particles was used as the average particle size.

[0086] (B) Resin B1: AER9000 (polypropylene oxide-modified epoxy resin), manufactured by Asahi Kasei Corporation, epoxy equivalent: 380 g / eq B2: EP4010S (polypropylene oxide-modified epoxy resin), manufactured by ADEKA Corporation, epoxy equivalent: 350 g / eq

[0087] B3: PB3600 (polybutadiene skeleton-containing epoxy resin), manufactured by Daicel Corporation, epoxy equivalent: 199 g / eq. B4: EPU 7N (urethane skeleton-containing epoxy resin), manufactured by ADEKA Corporation, epoxy equivalent: 230 g / eq. B5: CTBN 1300x13 (CTBN (carboxyl-terminated butadiene nitrile rubber)), manufactured by HUNTSMAN Corporation. B6: AK601 (bisphenol A-type epoxy resin), manufactured by Nippon Kayaku Co., Ltd.

[0088] (C) Solvent C1: KBM 103, manufactured by Shin-Etsu Silicone Co., Ltd. C2: Terpinolene, manufactured by Nippon Terpene Chemical Co., Ltd. C3: Butyl carbitol

[0089] (D) Curing agent D1: Hexahydrophthalic anhydride (HN5500), an acid anhydride curing agent, manufactured by Hitachi Chemical Co., Ltd. D2: XPL4437E, a phenolic curing agent, manufactured by Gun-ei Chemical Co., Ltd.

[0090] (E) Curing accelerator E1: 2E4MZ, 2-ethyl-4-methylimidazole, manufactured by Shikoku Chemicals Corporation E2: 2P4MZ, manufactured by Shikoku Chemicals Corporation

[0091] (F) Additive F1: Marialim SC1015F, polymeric polycarboxylic acid dispersant, manufactured by NOF Corporation (G) Carbon particles Graphene (GNH-XA), particle size 2.5 μm, manufactured by Graphene Platform Co., Ltd.

[0092] Examples 1 to 9 and Comparative Examples 1 to 3 Conductive resin compositions were produced by mixing and dispersing the raw materials using a three-roll mill so as to obtain the blending ratios shown in the tables below. The numerical values ​​of each component (A) to (G) and the total numerical value shown in the tables are in parts by mass. Numerical values ​​without units in the tables represent parts by mass.

[0093] <Viscosity> The viscosity of each conductive resin composition in the Examples and Comparative Examples was measured using a TVE-22H viscometer (1°34' cone, R24) manufactured by Toki Sangyo Co., Ltd., by measuring 1 ml of the sample and rotating it at 10 rpm at 25°C for 1 minute, and the value was read as the measured value.

[0094] <Specific Resistivity Value> A 50 μm thick stencil capable of obtaining a linear printing pattern of 50 mm × 2 mm on a flat alumina substrate was prepared, and each conductive resin composition of the Examples and Comparative Examples was printed as a sample. The alumina substrate on which the sample had been printed was cured at 200° C. for 20 minutes, and the line resistance of the cured product was measured with a digital multimeter. The sample film thickness was measured using a Surfcom 1500 surface roughness meter manufactured by Tokyo Seimitsu, and the specific resistance value was calculated.

[0095] <Tape Adhesion> Each conductive resin composition from the Examples and Comparative Examples was applied to a cured epoxy resin to a film thickness of approximately 150 μm. The resulting test specimens were cured at 200°C for 20 minutes, and a cross-cut test was performed on the specimens to evaluate tape adhesion according to ASTM D3359-97. Specifically, the sample was applied to a 10 mm x 10 mm flat plate, cured at 200°C for 20 minutes, and six notches were cut with a cutter at 1 mm intervals in both the vertical and horizontal directions to form 25 1 mm x 1 mm grids (5 mm x 5 mm). Tape was applied to the resulting test specimens, and the specimens were peeled using the method described in ASTM D3359-97. The peeling condition was evaluated by calculating the percentage of peeled area from the number of peeled pieces within the total area of ​​the 5 mm x 5 mm grid. Tape adhesion was evaluated using a five-point scale (1B to 5B) for the peeled surface after tape peeling. A rating of 5B or higher is evaluated as "excellent", 4B is "good", and 3B to 0B is "unacceptable". 5B: No peeling 4B: Peeling area is 5% or less of the total area of ​​the 5mm x 5mm grid 3B: Peeling area is more than 5% but not more than 15% of the total area of ​​the 5mm x 5mm grid 2B: Peeling area is more than 15% but not more than 35% of the total area of ​​the 5mm x 5mm grid 1B: Peeling area is more than 35% but not more than 65% of the total area of ​​the 5mm x 5mm grid 0B: Peeling area is more than 65% of the total area of ​​the 5mm x 5mm grid

[0096] <Reliability Test> Each of the conductive resin compositions of the Examples and Comparative Examples was applied as a sample onto a cured epoxy resin material so that the film thickness was approximately 150 μm, and the sample was cured at 200° C. for 20 minutes to obtain a test piece. The test piece was then subjected to a HAST (High Accelerated Stress Test) test condition of 130° C. / 85% RH for 24 hours, and the adhesion after the test was evaluated in the same manner as in the cross-cut test in <Tape Adhesion>.

[0097] <Thermal Conductivity> Each conductive resin composition of the Examples and Comparative Examples was applied as a sample to a copper plate with a thickness of 1 mm so that the film thickness after curing was 100 to 150 μm, and the sample was cured at 200°C for 20 minutes. A carbon spray was applied to the surface of the cured product to prepare a test piece. The thermal conductivity of the prepared test piece at 25°C was measured using a NETZSCH LFA447 flash analyzer. The specific heat used in the calculation was measured by DSC method using a NETZSCH DSC204F1 differential scanning calorimeter on the cured product, and the specific gravity of the cured product was measured by Archimedes' method.

[0098] <Indentation Elastic Modulus> Each conductive resin composition of the Examples and Comparative Examples was applied as a sample onto a glass slide so that the thickness of the cured film was 50 μm, and the sample was cured at 200°C for 20 minutes to prepare a test piece (cured product). Measurements were performed using a nanoindentation tester, ENT-NEXUS, manufactured by Elionix. A load of 200 mN was applied to the test piece cured at 200°C for 20 minutes using a Berkovich indenter over 10 seconds, the load was held for 10 seconds, and the load was released over 10 seconds. The indentation depth was approximately 5 μm, which is approximately 1 / 10 of the sample film thickness of 50 μm, and measurements were taken in an area not affected by the glass slide. A nanoindentation test was performed under these conditions to obtain a load-displacement curve. The indentation elastic modulus E defined in ISO 14577 was calculated from the obtained load-displacement curve. ＩＴ was calculated.

[0099] <Electromagnetic Shielding Effect> The electromagnetic shielding effect was measured in accordance with ASTM D4935. A dispenser valve (Nordson Asymtek DJ-2200) was attached to a precision dispensing device (Nordson Asymtek S2-920P). A sample was applied to a polyimide substrate (1 mm thick) so that the cured film would have a thickness of 15 μm, and the applied sample was heated at 200°C for 20 minutes to prepare a test specimen. The prepared test specimen was measured using a Keycom "Coaxial Tube Type Shielding Effect Measurement System (500 MHz to 18 GHz)." An electromagnetic shielding effect of 50 dB or more was evaluated as "Excellent," a value of 30 dB or more but less than 50 dB was evaluated as "Good," and a value of less than 30 dB was evaluated as "Fair."

[0100] <Spray Coatability> A dispenser valve (product name: Dispense Jet, model number: DJ-2200, manufactured by Nordson Asymtek) was attached to a precision dispensing device (product name: Spectrum II Dispenser, model number: S2-920P, manufactured by Nordson Asymtek), and each of the conductive resin compositions of the Examples and Comparative Examples was sprayed onto a flat surface. A needle with a nozzle diameter of 24G was used, and evaluations were made for clogging of the needle nozzle, lack of discharge, smearing, etc. A state in which the composition was atomized by spraying and applied in a straight line was evaluated as "◯ (good)," and a state in which the composition was not discharged or the straight line was interrupted midway by the spray was evaluated as "× (insufficient)."

[0101] The conductive resin compositions of the Examples and Comparative Examples and the evaluation results are shown in Tables 1 and 2. The compositions containing the components (B), (D), and (E) in Examples 1 and 2 were cured at 200°C for 20 minutes, and the cured products were measured using a differential scanning calorimeter DSC204F1 manufactured by NETZSCH. The DSC chart (resin-based DSC) is shown in Figure 1.

[0102]

[0103]

[0104] As shown in Tables 1 and 2, the conductive resin compositions according to Examples 1 to 9 were conductive resin compositions containing (A) silver-containing particles and (B) resin, and had an indentation modulus E ＩＴ Since the modulus of elasticity is in the range of 10 to 20 GPa, when the conductive resin composition is applied by spray coating, a coating film with high adhesion to objects such as electronic components can be formed, providing excellent electromagnetic wave shielding effects. Furthermore, compared to Example 1, Example 2 showed superior adhesion after reliability testing due to the use of a phenolic resin as the curing agent. This is thought to be because, as shown in the DSC chart (resin-based DSC) in Figure 1, the use of a liquid phenolic resin as the (D) curing agent shifts the curing initiation temperature to a higher temperature, facilitating the removal of solvents in the cured product of the conductive resin composition, reducing coating defects such as voids and improving adhesion. The conductive resin composition of Comparative Example 1 had an indentation modulus of elasticity E ＩＴSince the modulus of elasticity is less than 10 GPa, the reliability test revealed that the adhesion decreased and sufficient adhesion could not be obtained over time in a high-temperature, high-humidity environment. This is thought to be because the (B) resin used in Comparative Example 1 was poorly reactive and insufficiently cured, resulting in an increase in the initial resistance value. Furthermore, Comparative Example 1 exhibited large thermal shrinkage due to heat during the reliability test, which is thought to be why peeling occurred in the adhesion test after the reliability test. The conductive resin composition of Comparative Example 2, which does not contain the (B) component, had an indentation modulus of elasticity E ＩＴ The conductive resin composition according to Comparative Example 3 had an indentation modulus E ＩＴ was more than 20 GPa, and the reliability was insufficient.

[0105] The conductive resin composition according to an embodiment of the present invention can form an electromagnetic wave shielding layer by spraying onto electronic components, and can be suitably used in electronic components such as power amplifiers, Wi-Fi / Bluetooth modules, and flash memories used in electronic devices such as mobile phones, smartphones, laptop computers, and tablet terminals.

[0106] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2022-110666) filed on July 8, 2022, the contents of which are incorporated herein by reference.

Claims

1. (A) Component: Silver-containing particles, (B) Component is at least one of a thermosetting resin or a thermoplastic resin. A conductive resin composition comprising, The indentation modulus E is determined from the load-displacement curve obtained by the nanoindentation test following the procedure below. ＩＴ The pressure is 10-20 GPa. Conductive resin composition. [procedure] (1) A conductive resin composition is applied to a glass slide, heated at 200°C for 20 minutes to form a coating film with a thickness of 50 μm, and a test specimen is obtained. (2) A nanoindentation test is performed on the coated surface of the test piece obtained in (1) using a Berkovich indenter, applying a load up to a maximum load of 200 mN over 10 seconds, holding at that maximum load for 10 seconds, and then unloading over 10 seconds, to obtain a load-displacement curve.

2. The conductive resin composition according to claim 1, wherein component (A) contains silver particles with an average particle size of 100 nm or more and 350 nm or less.

3. The conductive resin composition according to claim 1 or 2, wherein component (B) contains an epoxy resin.

4. The conductive resin composition according to claim 1 or 2, wherein the component (B) comprises a flexible skeleton-containing epoxy resin.

5. The conductive resin composition according to claim 4, wherein the flexible skeleton-containing epoxy resin comprises, as a part of its molecule, at least one flexible skeleton selected from a polyoxyalkylene skeleton, polyethylene glycol skeleton, polypropylene glycol skeleton, polyether skeleton, polypropylene oxide skeleton, urethane skeleton, polybutadiene skeleton, and nitrile rubber skeleton.

6. The conductive resin composition according to claim 1 or 2, wherein the content of component (B) is 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of component (A).

7. Furthermore, the conductive resin composition according to claim 1 or 2, further comprising a solvent as component (C).

8. Furthermore, the conductive resin composition according to claim 1, comprising a curing agent as component (D).

9. The conductive resin composition according to claim 8, wherein component (D) comprises at least one selected from an acid anhydride-based curing agent, a phenol-based curing agent, and an amine-based curing agent.

10. Furthermore, the conductive resin composition according to claim 8 or 9, further comprising a curing accelerator as component (E).

11. The conductive resin composition according to claim 1, further comprising carbon particles as component (G).

12. The conductive resin composition according to claim 11, wherein the average particle size of component (G) is 0.1 to 10 μm.

13. The conductive resin composition according to claim 11 or 12, wherein the content of component (G) is 1 to 50 parts by mass per 100 parts by mass of component (A).

14. The conductive resin composition according to claim 10, wherein the maximum value of the exothermic peak in the chart when the composition comprising component (B), component (D), and component (E) is measured by differential scanning calorimetry is in the range of 175 to 250°C.

15. The conductive resin composition according to claim 1 or 2, wherein the viscosity at 25°C and 10 rpm is 10 to 10,000 mPa·s or less.

16. The conductive resin composition according to claim 1 or 2, wherein the conductive resin composition is for spray application.

17. The conductive resin composition according to claim 1 or 2, wherein the conductive resin composition is a spray coating agent for electromagnetic wave shielding.

18. An electromagnetic wave shielding layer formed from the conductive resin composition according to claim 1 or 2.

19. An electronic component comprising an electromagnetic shielding layer as described in claim 18.