Resin composition and production method therefor, conductive adhesive, connection structure, and electronic component

Abstract

Provided are: a resin composition with which it is possible to suppress thermal expansion and impart excellent connection reliability when used as an adhesive for connecting; and a production method therefor. The present invention relates to a resin composition including an epoxy resin, a curing agent, conductive particles, and negative thermal expansion particles, wherein the content of the conductive particles is 0.2-40 mass%, the content of the negative thermal expansion particles is 0.5-30 vol%, and the ratio of the average particle size of the negative thermal expansion particles with respect to the average particle size of the conductive particles (average particle size of the negative thermal expansion particles / average particle size of the conductive particles) is 0.001-10.

Description

Resin compositions and methods for producing the same, conductive adhesives, connecting structures, and electronic components

[0001] This invention relates to resin compositions and methods for producing the same, conductive adhesives, connecting structures, and electronic components.

[0002] Conventionally, resin compositions mainly composed of compounds having epoxy groups have been used as connecting adhesives to connect circuit components and circuit boards.

[0003] In recent years, with the expansion of the RFID (Radio Frequency Identification) market, the demand for adhesives used to connect circuit components contained in RFID media such as RFID tags to circuit boards has also increased. Furthermore, as electronic devices and RFID media become smaller, thinner, and more high-performance, there is a growing need for adhesives that can suppress malfunctions such as poor conductivity and short circuits between circuit components and circuit boards, enabling highly reliable electrode connections.

[0004] For example, Patent Document 1 discloses that an anisotropic conductive adhesive for connecting circuit members, containing an adhesive resin composition comprising an epoxy resin and a latent curing agent, an inorganic filler, and conductive particles, enables the manufacture of a circuit board with significantly improved connection reliability.

[0005] Japanese Patent Publication No. 2012-209558

[0006] The anisotropic conductive adhesive for connecting circuit components described in Patent Document 1 has a low coefficient of thermal expansion at high temperatures, and thermal expansion at the connection point at high temperatures is suppressed. As a result, there is no increase in connection resistance or peeling of the adhesive at the connection point, leading to a significant improvement in connection reliability.

[0007] However, with the recent improvements in various characteristics of electronic devices and RFID media, there has been a demand for further improvements in connection reliability.

[0008] Therefore, the object of the present invention is to provide a resin composition and a method for producing the same that can suppress thermal expansion and provide excellent connection reliability when used as a connecting adhesive.

[0009] In view of the above circumstances, the inventors conducted extensive research and, as a result, discovered that a resin composition containing epoxy resin, a latent curing agent, and conductive particles, when further containing negative thermal expansion particles, can suppress thermal expansion and provide excellent connection reliability when used as a connecting adhesive. This led to the completion of the present invention.

[0010] In other words, the present invention provides a resin composition comprising an epoxy resin, a curing agent, conductive particles, and negative thermal expansion particles, wherein the content of the conductive particles is 0.2 to 40% by mass, the content of the negative thermal expansion particles is 0.5 to 30% by volume, and the ratio of the average particle size of the negative thermal expansion particles to the average particle size of the conductive particles (average particle size of the negative thermal expansion particles / average particle size of the conductive particles) is 0.001 to 10.

[0011] Furthermore, the present invention provides a method for producing a resin composition by adding and mixing a curing agent solution to a mixture containing epoxy resin, negative thermal expansion particles, and conductive particles.

[0012] Furthermore, the present invention provides a conductive adhesive containing the aforementioned resin composition.

[0013] Furthermore, the present invention provides an adhesive structure in which members to be bonded are bonded together via the conductive adhesive, and an electronic component using the conductive adhesive.

[0014] According to the present invention, a resin composition that can suppress thermal expansion and provide excellent connection reliability when used as a connecting adhesive, a method for producing the same, a conductive adhesive that can suppress thermal expansion and provides excellent connection reliability using the same, a connecting structure, and an electronic component can be provided.

[0015] The present invention will be described below based on preferred embodiments. The resin composition of the present invention comprises an epoxy resin, a curing agent, conductive particles, and negative thermal expansion particles.

[0016] The epoxy resin used in the resin composition of the present invention may be any epoxy resin commonly used as an adhesive for connecting electronic devices and RFID media, and is usually a compound having one or more epoxy groups in one molecule. Specific examples of such compounds include novolac resins such as phenol novolac and cresol novolac; polyhydric phenols such as bisphenol A, bisphenol F, bisphenol AD, resorcinol, and bishydroxydiphenyl ether; polyhydric alcohols such as ethylene glycol, neopentyl glycol, glycerin, trimethylolpropane, and polypropylene glycol; polyamino compounds such as ethylenediamine, triethylenetetramine, and aniline; polyhydric carboxyl compounds such as adipic acid, phthalic acid, and isophthalic acid; glycidyl-type epoxy resins obtained by reacting these with epichlorohydrin or 2-methylepichlorohydrin; aliphatic epoxy resins such as dicyclopentadiene epoxy and butadiene dimer epoxy; and alicyclic epoxy resins such as 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate. Among these, alicyclic epoxy resins are preferred because they have high adhesive strength, excellent heat resistance and electrical insulation properties, low melt viscosity, and allow connection at low pressure. Furthermore, to prevent ion migration, it is preferable to use high-purity products with reduced impurity ions (such as Na and Cl) and hydrolyzable chlorine.

[0017] The curing agent used in the resin composition of the present invention is preferably a latent curing agent that exhibits its function as a curing agent upon heating or the like, and can be appropriately selected depending on the type of epoxy resin, but examples include onium salt-based curing agents, amine-based curing agents, acid anhydride curing agents, phenol-based curing agents, etc. Among these, onium salt-based curing agents and amine-based curing agents are preferred in terms of curing speed.

[0018] As the onium salt-based curing agent, any compound capable of generating cationic species or Lewis acid by heating may be used. Examples include aromatic sulfonium salts, thiophenium salts, thianium salts, benzylammonium, pyridinium salts, hydrazinium salts, carboxylic acid esters, sulfonic acid esters, amine imides, iodonium salts, and the like. Commercially available products of this kind include, for example, SI-L85, SI-L110, SI-L145, SI-L160, SI-H15, SI-H20, SI-H25, SI-H40, SI-H50, SI-60L, SI-80L, SI-100L, SI-60, SI-80, SI-100, SI-B7, SI-B2A, SI-3A of the Sun-Aid (registered trademark) series manufactured by Sanshin Chemical Industry Co., Ltd.; TA-60, TA-100, TA-110 manufactured by San-Apro Ltd.; Adeka Opton CP-66 (counter ion: SbF6), Adeka Opton CP-77 manufactured by ADEKA Corporation; TAG-2678, TAG-2713, TAG-2172 manufactured by KING INDUSTRIES INC.; FC-520 manufactured by 3M; CI-2921, CI-2920, CI-2946, CI-3128, CI-2624, CI-2639, CI-2064 manufactured by Nippon Soda Co., Ltd. These may be used alone or in combination of two or more.

[0019] Examples of amine-based curing agents include aromatic amines, aliphatic amines, cyclic amines, amine adducts, and dicyandiamides. Examples of aromatic amines include diaminodiphenylmethane, metaphenylenediamine, diaminodiphenylsulfone, and imidazole. Examples of commercially available products include MDA-100 from Mitsui Chemicals Fine Chemicals, Inc., WA and P200H50 from Mitsubishi Chemical Corporation, and SIZ, 2MZ-H, C11Z, 1.2DMZ, C17Z, 2E4MZ, 2PZ, 2P4MZ, 2MZ-CN, C11Z-CN, 2MZ-CN, C11Z-A, 2MZ-A, 2MA-OK, and 2PHZ-PW from Shikoku Chemicals, Inc. Examples of aliphatic amines include diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), m-xylenediamine (MXDA), trimethylhexamethylenediamine (TMD), 2-methylpentamethylenediamine (2-MPMDA), and diethylaminopropylamine (DEAPA). Examples of commercially available products include ethylenediamine from Tosoh Corporation, EH-6019, EH-6024, EH-6028, EH-479A, EH451N, EH-451K, and EH-6007 from the ADEKA Hardener® series from ADEKA Corporation, TO184 from Mitsubishi Chemical Corporation, and WN-405, WN-620, WH-614, F4, and WH-650 from the LUCKAMIDE® series from DIC Corporation. Examples of cyclic amines include isophoronediamine, 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, norbornenediamine, 1,2-diaminocyclohexane, and Laromine C-260. Examples of commercially available products of this type include 1,3-BAC manufactured by Mitsubishi Gas Chemical Company, Inc. Examples of amine adducts include reaction products of amine compounds and epoxy compounds. Examples of commercially available products of this type include PN-23, PN-23J, PN-H, PN-31, and PN-31J from the Amicure® series manufactured by Ajinomoto Fine Techno Co., Ltd.Other commercially available amine-based curing agents include 8114, 8116, 8119-D, 8149-D, FXD-821-F, FXK-8014-A, FXE-8104-D, 8106-A, FXP-8063-B, 8122-D, 8139-J, 8150-D, 8185-A, FXJ-838-B, FXJ-8091, 8, manufactured by T&KTOKA Corporation. Examples include 117, 8121, ST14, YN100, DICY7, DICY15, DICY50 from Mitsubishi Chemical Corporation, and PN-23, PN-N, PN-31, PN-40, PN-50, PN-F, PN-23J, PN-31J, PN-40J, MY-24, MY-25, AH-154, AH-162 from Ajinomoto Fine Techno Co., Ltd.

[0020] Examples of acid anhydride curing agents include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride, tetrabromophthalic anhydride, maleic anhydride, succinic anhydride, dodecinyl succinic anhydride, dichlorosuccinic anhydride, methylnadic anhydride, pyromelic anhydride, chlorendicic anhydride, and benzophenonetetracarboxylic anhydride. Examples of such commercially available products include YH306 and YH307 from Mitsubishi Chemical Corporation, HN-2200 and MHAC-P from Resonac Co., Ltd., and MH-700, MH-700G, MH, MH-T, MTA-15, HNA-100, OSA, DDSA, TH, HH, SA, and TMEG-S from Shin Nippon Rika Co., Ltd.

[0021] Examples of phenolic curing agents include phenol novolac resin, cresol novolac resin, tert-butylphenol novolac resin, nonylphenol novolac resin, phenol aralkyl resin, and naphthol aralkyl resin. Examples of commercially available products include 170 and 170N from Mitsubishi Chemical Corporation, and TD-2131, TD-2106, TD-2093Y, TD-2090, VH-4150, VH-4170, KH-6021, KA-1160, KA-1163, and KA-1165 from DIC Corporation.

[0022] The conductive particles used in the resin composition of the present invention include metal particles such as nickel, gold, silver, palladium, copper, and solder, and those having conductivity by themselves such as carbon particles. Further, those in which a metal film is formed on the surface of the core material particles to impart conductivity are also included. By including the conductive particles, the resin composition of the present invention becomes a one-component conductive adhesive and is useful as a connecting adhesive for connecting circuit components and a circuit board.

[0023] The average particle size of the conductive particles is preferably 0.1 μm to 1000 μm, and particularly preferably 0.5 to 200 μm. The average particle size of the conductive particles is appropriately selected according to the specific use of the resin composition of the present invention. However, when the resin composition of the present invention is used as a connecting adhesive, if the average particle size of the conductive particles is too small, conduction may be difficult, and if the average particle size of the conductive particles is too large, a short circuit may easily occur. The average particle size of the conductive particles can be measured using the electrical resistance method.

[0024] Further, the shape of the conductive particles is not particularly limited. Generally, the conductive particles can be in the form of powder grains, but other shapes, such as fibrous, hollow, plate-like, or needle-like, may also be used, and those having a large number of protrusions on the particle surface or those having an amorphous shape may also be used. Among these, spherical conductive particles are particularly preferable because of their excellent packing properties and ease of uniform mixing and dispersion.

[0025] When using conductive particles in which a metal film is formed on the surface of the core material particles, as a method for forming a metal film on the surface of the core material particles, for example, dry methods using vapor deposition, sputtering, mechanochemical, and hybridization methods, and wet methods using electrolytic plating and electroless plating methods can be mentioned. Further, these methods may be combined to form a metal film on the surface of the core material particles.

[0026] When conductive particles are used in which a metal film is formed on the surface of core material particles, the core material particles used may be inorganic or organic. Examples of inorganic core material particles include metal particles such as gold, silver, copper, nickel, palladium, and solder, alloys, glass, ceramics, silica, metal or nonmetal oxides (including hydrated ones), metal silicates including aluminosilicates, metal carbides, metal nitrides, metal carbonates, metal sulfates, metal phosphates, metal sulfides, metal salts, metal halides, and carbon. Examples of organic core material particles include natural fibers and natural resins, thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutene, polyamide, polyacrylic acid esters, polyacrylonitrile, polyacetal, ionomers, and polyesters, alkyd resins, phenolic resins, urea resins, benzoguanamine resins, melamine resins, xylene resins, silicone resins, epoxy resins, and diallyl phthalate resins. In the resin composition of the present invention, it is preferable to use metal particles such as gold, silver, copper, nickel, palladium, and solder as core material particles, in order to uniformly and densely coat the particle surface with a metal film, thereby providing oxidation resistance and low resistance during connection. It is also preferable to use nickel as the core material particle and to use a material in which the metal film is formed on the surface of the nickel by an electroless plating method. The metal film may also include alloys (for example, nickel-phosphorus alloys and nickel-boron alloys).

[0027] When conductive particles are used in which a metal film is formed on the surface of core material particles, the average particle size of the core material particles is preferably 0.1 μm to 1000 μm, and particularly preferably 0.5 μm to 200 μm. If the average particle size of the core material particles is too small, conductivity may be difficult even with conductive particles that have a metal film formed on them, and if the average particle size of the core material particles is too large, short circuits may occur easily. The average particle size of the core material particles is the value measured using the electrical resistance method.

[0028] Furthermore, the particle size distribution of core material particles measured by the method described above has a range. Generally, the range of particle size distribution of powder is expressed by the coefficient of variation shown in the following formula (1): Coefficient of variation (%) = (standard deviation / average particle size) × 100 ... (1) A large coefficient of variation indicates a wide range of distribution, while a small coefficient of variation indicates a sharp particle size distribution. It is preferable to use core material particles with a coefficient of variation of 50% or less, preferably 30% or less, and particularly preferably 20% or less, as this increases the effective contribution to the connection between circuit components and circuit boards.

[0029] Furthermore, there are no particular restrictions on the shape of the core material particles. Generally, the core material particles may be in the form of powder or granules, but they may also be in other shapes, such as fibrous, hollow, plate-like, or needle-like, and may have numerous protrusions on the particle surface or be irregular in shape. Among these, spherical core material particles are particularly preferred because they are easy to mix and disperse uniformly, and it is easier to obtain spherical conductive particles.

[0030] Furthermore, while there are no particular restrictions on other physical properties of the core material particles, in the case of core material particles made of resin material, the value of K, as defined by the calculation formula (2) below, must be 100 N / mm at 20°C. ２ ~100000N / mm ２ A material within the range of K (N / mm²) and with a recovery rate of 1% to 100% after 10% compression deformation at 20°C is preferred because it prevents damage to the electrodes when pressing them together and allows for sufficient contact between the electrodes. ２ ) = (3 / √2) × F × S －３／２ ×R －１／２ ... (2) [In formula (2), F and S are the load value (N) and compression displacement (mm) at 10% compression deformation of the core material particles, respectively, as measured by a micro-compression testing machine (MCTM-500 manufactured by Shimadzu Corporation), and R is the radius (mm) of the core material particles as measured by a micro-compression testing machine (MCTM-500 manufactured by Shimadzu Corporation)]

[0031] In addition, conductive particles obtained by treating the particle surface of the conductive particles with a hydrophobizing agent as necessary for the purpose of improving the moisture resistance and corrosion resistance of the conductive particles can be used. Examples of the hydrophobizing agent include benzotriazole-based compounds, titanate-based coupling agents, higher fatty acids and their derivatives, phosphate esters, phosphite esters, and the like. These can be used alone or in combination of two or more as necessary.

[0032] The content ratio of the conductive particles is preferably 0.2 to 60% by mass, more preferably 0.2 to 40% by mass, still more preferably 0.5 to 40% by mass, and particularly preferably 1 to 30% by mass. When the content ratio of the conductive particles is within the above range, problems such as poor conduction and short circuit can be suppressed, and an adhesive for connection excellent in connection reliability can be obtained. The content ratio of the conductive particles is calculated by the following formula. Content of conductive particles (parts by mass) / Total amount of resin composition (parts by mass) × 100

[0033] The negative thermal expansion particles used in the resin composition of the present invention are particles of a compound having a negative linear expansion coefficient, that is, having negative thermal expansibility, in a predetermined temperature range, and include β-eucryptite (LiAlSiO ４ ), zirconium tungstate (ZrW ２ O ８ ), zirconium phosphate, zirconium phosphate sulfate, zirconium phosphate tungstate (Zr ２ WO ４ (PO ４ ) ２ (hereinafter, also referred to as "ZWP").), Zn ｘ Cd １－ｘ (CN) ２ copper vanadium composite oxide (Cu ２ V ２ O ７Examples of particles include those made of (hereinafter also referred to as "CVO"), copper vanadium composite oxide containing a predetermined element in a solid solution, copper vanadium composite oxide in which part of Cu and / or V is substituted with a predetermined element, zinc phosphorus composite oxide, zinc phosphorus composite oxide in which part of Zn is substituted with a predetermined element, manganese nitride, bismuth nickel iron oxide, etc. Also, examples include particles in which the surface of particles having negative thermal expansion properties is surface-treated, such as coating the surface of zirconium tungstate particles with a silane coupling agent, fatty acid or its derivative, or an inorganic compound. Among these, particles of compounds selected from β-eucryptite, zirconium tungstate, zirconium tungstate phosphate, and copper vanadium composite oxide are preferred because they can expand and contract relatively uniformly in any temperature range. These can be used alone or in combination of two or more as needed. By including negative thermal expansion particles, the resin composition of the present invention can achieve a negative thermal expansion coefficient, zero thermal expansion coefficient, or low thermal expansion coefficient.

[0034] The linear expansion coefficient of negative thermal expansion particles at 50-200°C is -1.0 × 10⁻⁶. －７ ~-1.0 x 10 －３ Preferably, the range is (-0.1 to -1000 ppm), and -1.0 × 10 －６ ~-1.0 x 10 －４ It is more preferable that the coefficient of linear expansion of the negative thermal expansion particles is within the above range. This suppresses the thermal expansion of the resin composition, prevents increased resistance during connection even after reliability testing, and provides sufficient adhesive performance, resulting in a connecting adhesive with excellent connection reliability.

[0035] The average particle size of the negative thermal expansion particles is preferably 0.01 to 100 μm, and more preferably 0.05 to 50 μm. Having the average particle size of the negative thermal expansion material within this range facilitates handling. The average particle size of the negative thermal expansion particles can be determined by observing 100 arbitrary particles using a scanning electron microscope and calculating the arithmetic mean of the maximum particle lengths in the scanning electron microscope image. In this case, the maximum length refers to the length of the longest line segment crossing the particle image.

[0036] The shape of the negative thermal expansion material is not particularly limited. For example, it may be spherical, granular, plate-shaped, flaky, whisker-shaped, rod-shaped, filament-shaped, crushed, or a combination thereof. Among these, spherical negative thermal expansion particles are particularly preferred because they have excellent packing properties and are easy to mix and disperse uniformly.

[0037] The content of negative thermal expansion particles is preferably 0.5 to 30 volume%, and more preferably 1 to 25 volume%. By having a negative thermal expansion particle content within this range, the thermal expansion of the resin composition can be suppressed, preventing increased resistance during connection even after reliability testing, while maintaining sufficient adhesive performance and resulting in a connecting adhesive with excellent connection reliability. The content of negative thermal expansion particles is calculated using the following formula: (Content of negative thermal expansion particles (parts by mass) / Specific gravity of negative thermal expansion particles) / {(Content of negative thermal expansion particles (parts by mass) / Specific gravity of negative thermal expansion particles) + (Content of epoxy resin (parts by mass) + Content of curing agent (parts by mass)) / Specific gravity of epoxy resin)} × 100

[0038] The resin composition of the present invention may contain known additives as long as they do not affect connection reliability. Known additives include, for example, silane coupling agents, organic solvents, fillers, thixotropic agents, thickeners, devising agents, viscosity modifiers, leveling agents, antioxidants, tackifiers, waxes, heat stabilizers, stabilizers, anti-stabilizers, foaming agents, organic pigments, inorganic pigments, heat conductors, dyes, antistatic agents, moisture-permeable factory agents, water repellents, hollow foams, flame retardants, colorants, water absorbents, moisture absorbers, deodorants, foam stabilizers, defoamers, antifungal agents, preservatives, anti-algal agents, pigment dispersants, blocking inhibitors, hydrolysis inhibitors, etc. In addition, other resins such as organic water-soluble compounds, inorganic water-soluble compounds, thermoplastic resins, and thermosetting resins can be used in combination in liquid or solid form. Typical additives include stabilizers, heat conductors, and thixotropic agents.

[0039] The resin composition of the present invention can extend the pot life by further containing a quaternary phosphonium salt represented by the following formula (1) as the stabilizer.

[0040]

[0041] In equation (1), R １ , R ２ , R ３ and R ４ These may be the same group or different groups, and each may independently be an alkyl group or a phenyl group (-C ６ H ５ ) represents R in equation (1). １ ~R ４ If is an alkyl group, an alkyl group having 1 to 16 carbon atoms is preferred. Also, in formula (1), X － This represents an anion, for example, F － , Cl － , I － , Br － SO ４ ２－ BF ４ － , PF ４ － SbF ６ － , (OC ２ H ５ ) ２ P = O－ , (C ６ H ５ ) ４ B － These are some examples.

[0042] In the resin composition of the present invention, methyltributylphosphonium dimethyl phosphate and methyltrioctylphosphonium dimethyl phosphate are preferred as stabilizers because they can extend the pot life with only a small amount of addition.

[0043] The amount of quaternary phosphonium salt added as a stabilizer in the resin composition of the present invention is determined in relation to the amount of curing agent, and is preferably an amount such that the mass ratio of the quaternary phosphonium salt to the curing agent is 0.001 to 1, and more preferably an amount such that it is 0.005 to 0.8. If the mass ratio of the quaternary phosphonium salt to the curing agent is less than 0.001, it becomes difficult to obtain the effect of extending the pot life, on the other hand, if this mass ratio exceeds 1, although the pot life is extended, the curing of the resin composition tends to become difficult.

[0044] If the resin composition of the present invention further contains a quaternary phosphonium salt, the pot life at 25°C is preferably 7 days or more, more preferably 14 days or more, and particularly preferably 30 days or more, from the viewpoint of balancing storage stability and curability.

[0045] In the resin composition of the present invention, the aforementioned thermal conductive agent may further include boron nitride, aluminum oxide, titanium oxide, silica, etc. These may be included individually or, if necessary, as a mixture of two or more. Furthermore, the particle shape, size, amount added, etc., are not particularly limited.

[0046] The total content of conductive particles and negative thermal expansion particles in the resin composition of the present invention is preferably 0.05 to 50% by mass, and more preferably 0.2 to 30% by mass, relative to the total amount of the resin composition. By having the total content of conductive particles and negative thermal expansion particles within this range, it is possible to suppress defects such as poor conductivity and short circuits, and to suppress thermal expansion of the resin composition, while maintaining adhesive performance as an adhesive. The total content of conductive particles and negative thermal expansion particles can also be calculated using the following formula: (Content of conductive particles (parts by mass) + Content of negative thermal expansion particles (parts by mass)) / Total amount of resin composition (parts by mass) × 100

[0047] The total content of epoxy resin and curing agent in the resin composition of the present invention is not particularly limited, but is preferably 30% by mass or more, more preferably 35% by mass, and more preferably 40% by mass or more, based on the total amount of the resin composition. By having the total content of epoxy resin and curing agent within the above range, it is possible to suppress defects such as poor conductivity and short circuits, and to suppress thermal expansion of the resin composition, while maintaining adhesive performance as an adhesive. The total content of epoxy resin and curing agent is calculated by the following formula: (Epoxy resin content (parts by mass) + Curing agent content (parts by mass)) / Total amount of resin composition (parts by mass) × 100

[0048] In the resin composition of the present invention, the ratio of the average particle size of negatively thermally expanding particles to the average particle size of conductive particles (average particle size of negatively thermally expanding particles / average particle size of conductive particles) is preferably 0.001 to 10, more preferably 0.005 to 5, and particularly preferably 0.01 to 1. By having the ratio of the average particle size of negatively thermally expanding particles to the average particle size of conductive particles within the above range, the resin composition can suppress thermal expansion when used as a connecting adhesive, thereby providing excellent connection reliability.

[0049] The linear thermal expansion coefficient of the resin composition of the present invention is preferably 80 ppm / °C or less, and more preferably 75 ppm / °C or less, at 50 to 100°C. Having the linear thermal expansion coefficient of the resin composition within this range improves adhesion to the substrate and reduces the likelihood of gaps forming at the interface between the IC and the resin composition, thereby suppressing a decrease in communication strength. The linear thermal expansion coefficient of the resin composition of the present invention is measured using a thermomechanical measuring device under conditions such as a load of 5 g, a heating rate of 5°C / min, and a temperature range of 30 to 250°C, with the measured value between 50 and 100°C being defined as the linear thermal expansion coefficient. For example, a NETZSCH JAPAN TMA4000SE can be used as the thermomechanical measuring device.

[0050] The present invention provides a method for producing a resin composition by adding a curing agent solution to a mixture containing epoxy resin, conductive particles, and negative thermal expansion particles, and mixing them to obtain the resin composition as a one-component resin composition. In other words, the method for producing the resin composition of the present invention comprises the steps of: obtaining a mixture containing epoxy resin, conductive particles, and negative thermal expansion particles; preparing a curing agent solution; and adding the curing agent solution to the mixture and mixing it.

[0051] In the process of obtaining a mixture containing epoxy resin, conductive particles, and negative thermal expansion particles, the epoxy resin, conductive particles, and negative thermal expansion particles can be mixed using general-purpose equipment. Examples of such equipment include planetary mixers, two-roll mixers, three-roll mixers, bead mills, and ball mills. There are no particular restrictions as long as the equipment can mix uniformly, but a self-rotating vacuum degassing agitator is suitable because it can simultaneously knead and remove air bubbles from the paste in a short time.

[0052] The step of obtaining a mixture containing epoxy resin, conductive particles, and negative thermal expansion particles may be a step of mixing epoxy resin, conductive particles, and negative thermal expansion particles to obtain a mixture containing epoxy resin, conductive particles, and negative thermal expansion particles; a step of mixing epoxy resin and conductive particles to obtain a mixture containing epoxy resin and conductive particles, and then mixing the mixture containing epoxy resin and conductive particles with negative thermal expansion particles to obtain a mixture containing epoxy resin, conductive particles, and negative thermal expansion particles; or a step of mixing epoxy resin and negative thermal expansion particles to obtain a mixture containing epoxy resin and negative thermal expansion particles, and then mixing the mixture containing epoxy resin and negative thermal expansion particles with conductive particles to obtain a mixture containing epoxy resin, conductive particles, and negative thermal expansion particles.

[0053] In the process of preparing the curing agent solution, the curing agent and the solvent that dissolves the curing agent can be mixed using general equipment. Examples of such equipment include planetary mixers, two-roll mixers, three-roll mixers, bead mills, and ball mills. However, a self-rotating vacuum degassing agitator is suitable because it can simultaneously perform kneading and remove air bubbles from the paste in a short time.

[0054] In the step of adding the prepared curing agent solution to a mixture containing epoxy resin, conductive particles, and negative thermal expansion particles and mixing them, the mixture containing epoxy resin, conductive particles, and negative thermal expansion particles and the curing agent solution can be mixed using general-purpose equipment. Examples of such equipment include planetary mixers, two-roll mixers, three-roll mixers, bead mills, and ball mills. There are no particular restrictions as long as the equipment can mix uniformly, but a self-rotating vacuum degassing agitator is suitable because it can simultaneously knead and remove air bubbles from the paste in a short time.

[0055] In the method for producing the resin composition of the present invention, if necessary, a curing agent solution and known additives may be added to and mixed with a mixture containing epoxy resin, conductive particles, and negative thermal expansion particles. When mixing the curing agent solution and the main component, heat is generated if the mixing is done at high speed. If the temperature of the mixture containing epoxy resin, conductive particles, and negative thermal expansion particles and the curing agent solution exceeds a predetermined temperature due to this heat, the curing reaction may begin. Therefore, it is preferable to either add the additive to the mixture containing epoxy resin, conductive particles, and negative thermal expansion particles beforehand and mix them uniformly to form a mixed solution, or to prepare a uniform solution of the curing agent solution and additives beforehand and then add this solution to the mixture containing epoxy resin, conductive particles, and negative thermal expansion particles.

[0056] In the method for producing the resin composition of the present invention, a curing agent solution is added to a mixture containing epoxy resin, conductive particles, and negative thermal expansion particles and mixed to obtain a one-component conductive adhesive. This conductive adhesive suppresses malfunctions such as poor conductivity and short circuits, further suppresses thermal expansion, prevents increased resistance during connection even after reliability testing, and has sufficient adhesive performance, making it useful as a connection adhesive with excellent connection reliability.

[0057] Since the resin composition of the present invention contains the aforementioned conductive particles, it is also useful as a conductive adhesive.

[0058] The conductive adhesive of the present invention is preferably used as an anisotropic conductive adhesive that is placed between two substrates on which conductive substrates are formed, and adheres the conductive substrates to them by heating and pressing to establish electrical conductivity. The conductive adhesive can be used in various forms, such as paste or sheet.

[0059] The conductive adhesive of the present invention suppresses malfunctions such as poor conductivity and short circuits in miniaturized IC chips, circuit components such as light-emitting diodes, and circuit boards, and further suppresses thermal expansion. It also prevents increased resistance during connection even after reliability testing, maintains sufficient adhesive performance, and enables highly reliable electrode connections.

[0060] Examples of adhesive structures in which members to be bonded are bonded together via the conductive adhesive of the present invention include RFID-related products such as IC cards and IC tags, in which an IC chip is bonded to a circuit board having electrodes, and light-emitting electronic components in which a light-emitting diode is bonded to a circuit board having electrodes.

[0061] As a method for manufacturing electronic components using the conductive adhesive of the present invention, known methods can be used. For example, one method involves applying the conductive adhesive of the present invention to the surface of a circuit board having electrodes using a coating apparatus such as a slit coater, roll coater, spin coater, screen printing method, metal mask printing method, dispenser, or jet dispenser to a film thickness of 0.1 to 100 μm, and then placing the circuit components on the substrate so that a portion of the circuit components is positioned above the electrodes, and then heating and pressurizing the resulting laminate. By heating and pressurizing the laminate at a temperature of 120 to 230°C, preferably 150 to 200°C, and a pressure of 1 to 3 N, preferably 1.5 to 2.5 N, for 1 to 15 seconds, preferably 2 to 10 seconds, the members to be bonded are bonded to each other via the conductive adhesive of the present invention, and an electronic component of the present invention can be manufactured. The electronic component of the present invention has fewer defects such as poor conduction and short circuits, can suppress thermal expansion, prevents increased resistance during connection even after reliability testing, has sufficient adhesive performance, and has excellent connection reliability.

[0062] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0063] (Examples 1-13, 16, 17) The amounts of epoxy resin and negative thermal expansion particles shown in Table 1 were mixed in a rotary-type vacuum degassing stirrer to obtain a first compound. Next, the first compound and the amounts of conductive particles shown in Table 1 were mixed in a rotary-type vacuum degassing stirrer to obtain a second compound. Next, the amounts of curing agent shown in Table 1 were dissolved in γ-butyrolactone (manufactured by Tokyo Chemical Industry Co., Ltd.), which is the curing agent solvent, and mixed in a rotary-type vacuum degassing stirrer to obtain a curing agent solution. After that, the curing agent solution and the second compound were mixed in a rotary-type vacuum degassing stirrer to obtain a resin composition.

[0064] (Examples 14 and 15) The amounts of epoxy resin and negative thermal expansion particles shown in Table 1 were mixed in a rotary-type vacuum degassing stirrer to obtain a first compound. Next, the first compound, the amounts of conductive particles and additives shown in Table 1 were mixed in a rotary-type vacuum degassing stirrer to obtain a second compound. Next, the amounts of curing agent shown in Table 1 were dissolved in γ-butyrolactone (manufactured by Tokyo Chemical Industry Co., Ltd.), which is the curing agent solvent, and mixed in a rotary-type vacuum degassing stirrer to obtain a curing agent solution. After that, the curing agent solution and the second compound were mixed in a rotary-type vacuum degassing stirrer to obtain a resin composition.

[0065] (Comparative Examples 1 and 2) The amounts of epoxy resin and conductive particles shown in Table 1 were mixed in a rotary-type vacuum degassing agitator to obtain the first mixture. Next, the amount of curing agent shown in Table 1 was dissolved in γ-butyrolactone (manufactured by Tokyo Chemical Industry Co., Ltd.), which is the curing agent solvent, and mixed in a rotary-type vacuum degassing agitator to obtain the curing agent solution. Subsequently, the curing agent solution was mixed with the first mixture in a rotary-type vacuum degassing agitator to obtain the resin composition.

[0066] (Comparative Examples 3-6) The amounts of epoxy resin and negative thermal expansion particles shown in Table 1 were mixed in a rotary-type vacuum degassing stirrer to obtain a first compound. Next, the first compound and the amount of conductive particles shown in Table 1 were mixed in a rotary-type vacuum degassing stirrer to obtain a second compound. Next, the amount of curing agent shown in Table 1 was dissolved in γ-butyrolactone (manufactured by Tokyo Chemical Industry Co., Ltd.), which is the curing agent solvent, and mixed in a rotary-type vacuum degassing stirrer to obtain a curing agent solution. After that, the curing agent solution and the second compound were mixed in a rotary-type vacuum degassing stirrer to obtain a resin composition.

[0067] (Comparative Example 7) The epoxy resin, conductive particles, and additives in the amounts shown in Table 1 were mixed in a rotary-type vacuum degassing agitator to obtain a first mixture. Next, the curing agent in the amount shown in Table 1 was dissolved in γ-butyrolactone (manufactured by Tokyo Chemical Industry Co., Ltd.), which is the curing agent solvent, and mixed in a rotary-type vacuum degassing agitator to obtain a curing agent solution. Subsequently, the curing agent solution was mixed with the first mixture in a rotary-type vacuum degassing agitator to obtain a resin composition.

[0068] The components listed in Table 1 are as follows: <Epoxy Resin> - Bisphenol A type epoxy resin manufactured by Mitsubishi Chemical Corporation, product name: jER(registered trademark) 828 <Conductive Particles> - Conductive particle A: Manufactured by Nippon Chemical Industrial Co., Ltd., conductive particles in which a gold film is formed on the surface of nickel core particles by electroless plating, average particle size 5 μm - Conductive particle B: Manufactured by Nippon Chemical Industrial Co., Ltd., conductive particles in which a gold film is formed on the surface of nickel core particles by electroless plating, average particle size 7 μm - Conductive particle C: Manufactured by Nippon Chemical Industrial Co., Ltd., conductive particles in which a gold film is formed on the surface of nickel core particles by electroless plating, average particle size 50 μm <Negative Thermal Expansion Particles> - Negative thermal expansion particle A: Manufactured by Nippon Chemical Industrial Co., Ltd., zirconium tungstate phosphate (ZWP), linear expansion coefficient at 0 to 100°C -3 ppm / °C, average particle size 1.5 μm - Negative thermal expansion particle B: Manufactured by Nippon Chemical Industrial Co., Ltd., zirconium tungstate phosphate (ZWP), linear expansion coefficient at 0-100°C -3 ppm / °C, average particle size 0.10 μm - Negative thermal expansion particle C: Manufactured by Nippon Chemical Industrial Co., Ltd., zirconium tungstate phosphate (ZWP), linear expansion coefficient at 0-100°C -3 ppm / °C, average particle size 40 μm - Negative thermal expansion particle D: Manufactured by Nippon Chemical Industrial Co., Ltd., zirconium tungstate phosphate (ZWP), linear expansion coefficient at 0-100°C -3 ppm / °C, average particle size 28 μm - Negative thermal expansion particle E: Manufactured by Nippon Chemical Industrial Co., Ltd., zirconium tungstate phosphate (ZWP), linear expansion coefficient at 0-100°C -3 ppm / °C, average particle size 7 μm - Negative thermal expansion particle F: Manufactured by Nippon Chemical Industrial Co., Ltd., copper vanadium composite oxide (CVO), linear expansion coefficient at 0-100°C -15 ppm / °C, average particle size 20 μm - Negative thermal expansion particle G: Manufactured by Nemoto Special Chemicals Co., Ltd., zirconium tungstate (ZrW ２ O ８), linear expansion coefficient at 0 to 100°C -9 ppm / °C, average particle size 3 μm <Curing agent> ・Dicyandiamide (DICY) manufactured by Tokyo Chemical Industries, Ltd. ・Aromatic sulfonium salt manufactured by Sanshin Chemical Industries, Ltd., trade name: San-Aid (registered trademark) SI-60 ・2-phenyl-4-methyl-5-hydroxymethylimidazole (2P4MHZ) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. ・Amine adduct manufactured by Ajinomoto Fine Techno Co., Ltd., trade name: Amicure (registered trademark) PN-23J <Additives> ・2-ethyl-4-methylimidazole manufactured by Shikoku Chemicals, Ltd., trade name: 2E4MZ ・Quaternary phosphonium salt manufactured by Nippon Chemical Industrial Co., Ltd., trade name: Hishikorin (registered trademark) PX-4ET In addition, the ratio of average particle size listed in Table 1 indicates the ratio of the average particle size of negatively thermally expanding particles to the average particle size of conductive particles (average particle size of negatively thermally expanding particles / average particle size of conductive particles).

[0069] <Evaluation> <Coefficient of Linear Expansion> The coefficient of linear expansion of the resin compositions of Examples 1 to 17 and Comparative Examples 1 to 7 was measured using a thermomechanical measuring device (NETZSCH JAPAN TMA4000SE). The measurement conditions were a load of 5g, a heating rate of 5°C / min, and a temperature range of 30°C to 250°C. The coefficient of linear expansion between 50°C and 100°C was used as the coefficient of linear expansion of the resin composition. <Fabrication of IC Tags> On a substrate (size: 2.5 cm long, 8 cm wide) with aluminum wiring formed on a PET film, the resin compositions prepared in Examples 1 to 17 and Comparative Examples 1 to 7 were applied by dispensing to an area including the entire aluminum wiring, so that the thickness after curing was 100 μm, and an IC with a gold bump was placed on top. The resin composition was cured by heating at a temperature of 190°C and under a pressure of 3N for 10 seconds, connecting the substrate and the IC, and an IC tag was fabricated. The resin compositions used were prepared within 3 hours. <Adhesion> The die shear strength of the fabricated IC tags was measured. Die shear strength was measured using a digital force gauge, representing the strength (N) required to peel the IC chip from the substrate. The results are shown in Table 1. In the table, "Adhesion" indicates that the strength falls within the following ranges: ◎: 8N or more ○: 5-8N ×: 5N or less <Connection Reliability> The communication strength of the IC tags before and after the thermal shock test was measured, and the pass rate (%) was evaluated based on the difference between the former and the latter being within 2 dBm. Communication strength was measured using the Tagformance® Pro system manufactured by Voyantic. The thermal shock test consisted of maintaining the temperature at -40°C for 30 minutes and then at 85°C for 30 minutes, with 336 cycles performed. The results are shown in Table 1. In the table, "Connection Reliability" indicates that the pass rate falls within the following ranges. ◎: 80% or more ○: 50-80% ×: 50% or less

[0070]

[0071] As shown in Table 1, the resin composition of the present invention exhibits suppressed thermal expansion, excellent adhesion, and high connection reliability.

Claims

1. A resin composition comprising an epoxy resin, a curing agent, conductive particles, and negative thermal expansion particles, wherein the content of the conductive particles is 0.2 to 40% by mass, the content of the negative thermal expansion particles is 0.5 to 30% by volume, and the ratio of the average particle size of the negative thermal expansion particles to the average particle size of the conductive particles (average particle size of the negative thermal expansion particles / average particle size of the conductive particles) is 0.001 to 10.

2. The resin composition according to claim 1, wherein the total content of the conductive particles and the negative thermal expansion particles is 0.05 to 50% by mass of the total amount of the resin composition.

3. The resin composition according to claim 1, wherein the curing agent is a latent curing agent selected from onium salt-based curing agents, amine-based curing agents, acid anhydride-based curing agents, and phenol-based curing agents.

4. The resin composition according to claim 1, wherein the conductive particles are particles of a metal selected from the group consisting of nickel, gold, silver, palladium, copper, and solder.

5. The resin composition according to claim 1, wherein the conductive particles are particles on which a metal film has been formed on the surface of core material particles by an electroless plating method.

6. The resin composition according to claim 5, wherein the core material particles are particles of a metal selected from the group consisting of nickel, gold, silver, palladium, copper, and solder.

7. The resin composition according to claim 1, wherein the average particle size of the conductive particles is 0.1 to 1000 μm.

8. The resin composition according to claim 1, wherein the negative thermal expansion particles are particles of a compound selected from the group consisting of β-eucryptite, zirconium tungstate, zirconium tungstate phosphate, and copper vanadium composite oxide.

9. The resin composition according to claim 1, wherein the average particle size of the negative thermal expansion particles is 0.1 to 50 μm.

10. The resin composition according to claim 1, wherein the coefficient of linear expansion of the resin composition is 80 ppm / °C or less at 50 to 100°C.

11. A method for producing a resin composition according to any one of claims 1 to 10, comprising adding a curing agent solution to a mixture containing epoxy resin, negative thermal expansion particles, and conductive particles and mixing them.

12. A conductive adhesive comprising the resin composition according to any one of claims 1 to 10.

13. An adhesive structure in which members to be bonded are bonded together via the conductive adhesive described in claim 12.

14. An electronic component using the conductive adhesive described in claim 12.

15. The electronic component according to claim 14, wherein the electronic component is selected from the group consisting of IC cards, IC tags, and light-emitting electronic components.

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