Adhesive composition

Abstract

This invention relates to an adhesive composition. One aspect of the invention relates to an adhesive composition for connecting electronic components to each other, comprising a first conductive particle and a second conductive particle, wherein the first conductive particle is a conductive particle having protrusions capable of penetrating an oxide film formed on an electrode surface in the electronic component, and the second conductive particle is a conductive particle other than the first conductive particle, and is a conductive particle having a non-conductive core and a conductive layer disposed on the core.

Description

[0001] This invention is a divisional application of the invention application with application number 201780052955.3 (international application number PCT / JP2017 / 031010), application date August 29, 2017, and invention title "adhesive composition". Technical Field

[0002] This invention relates to adhesive compositions. Background Technology

[0003] In recent years, various adhesives have been used in fields such as semiconductors and liquid crystal displays for fixing electronic components and connecting circuits. As electronic components and circuits become increasingly dense and sophisticated in these applications, higher performance levels are required of adhesives.

[0004] For example, for connections between liquid crystal displays and TCP (Tape Carrier Package), FPC (Flexible Printed Circuit) and TCP, or FPC and printed wiring boards, adhesives containing conductive particles dispersed in the adhesive are used (conductive adhesives). For conductive adhesives, further improvements in conductivity and reliability are required.

[0005] For example, Patent Document 1 describes a conductive film formed by having a conductive film containing predetermined dendritic silver-coated copper powder particles on a substrate film, and discloses that sufficient conductive properties can be obtained even without the addition of silver powder using this conductive film.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2014 / 021037 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, when connecting electronic components to each other, it is sometimes desirable to apply the lowest possible pressure. In such cases, it is difficult to achieve the desired conductivity because it is challenging to electrically connect the electronic components to the conductive adhesive. For example, with a conductive film as described in Patent Document 1, there is room for improvement in conductivity when connecting electronic components to each other under low pressure (e.g., 0.1–0.5 MPa). On the other hand, to achieve the desired conductivity using such a conductive film, it is possible to increase the pressure when connecting the electronic components to each other, but in this case, the adhesive component (resin component) may be squeezed out and leak from between the electronic components.

[0011] In addition, the reliability of the conductive film described in Patent Document 1 cannot be said to be sufficient. That is, the conductive film described in Patent Document 1 may fail to maintain the desired conductivity in the face of changes in ambient temperature.

[0012] Therefore, the main objective of this invention is to provide an adhesive composition that exhibits excellent conductivity even under low-voltage bonding and can suppress the outflow of adhesive components during bonding. Another objective of this invention is to provide an adhesive composition with excellent reliability.

[0013] Methods for solving problems

[0014] One aspect of the present invention relates to an adhesive composition for connecting electronic components to each other, comprising a first conductive particle and a second conductive particle, wherein the first conductive particle is a conductive particle having a protrusion capable of penetrating an oxide film formed on an electrode surface in the electronic component, and the second conductive particle is a conductive particle other than the first conductive particle, and is a conductive particle having a non-conductive core and a conductive layer disposed on the core.

[0015] In addition, one aspect of the present invention relates to an adhesive composition comprising a first conductive particle and a second conductive particle, wherein the first conductive particle is a conductive particle having a pointed protrusion, and the second conductive particle is a conductive particle other than the first conductive particle, and is a conductive particle having a non-conductive core and a conductive layer disposed on the core.

[0016] The first conductive particle is preferably a conductive particle with an anisotropic shape.

[0017] The first conductive particle is preferably a dendritic conductive particle.

[0018] The first conductive particle is preferably a thin sheet-like conductive particle.

[0019] The second conductive particle is preferably a roughly spherical conductive particle.

[0020] The conductive layer preferably contains at least one selected from the group consisting of gold, nickel and palladium.

[0021] Invention Effects

[0022] This invention provides an adhesive composition that exhibits excellent conductivity even under low-voltage bonding and suppresses the outflow of adhesive components during bonding. Furthermore, according to this invention, an adhesive composition with excellent reliability can also be provided. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating one embodiment of the first conductive particle.

[0024] Figure 2 This is a schematic cross-sectional view illustrating one embodiment of a film-like adhesive composition.

[0025] Figure 3 This is a schematic cross-sectional view of a major part of an example showing how electronic components are connected to each other.

[0026] Figure 4 This is a schematic diagram illustrating the manufacturing method of the mounting body used for reliability testing.

[0027] Figure 5 This is a schematic diagram illustrating the method for measuring connection resistance in reliability testing. Detailed Implementation

[0028] Hereinafter, embodiments of the present invention will be described in detail with appropriate reference to the accompanying drawings.

[0029] One embodiment of the adhesive composition includes a first conductive particle and a second conductive particle. The first conductive particle is a conductive particle with protrusions, and the second conductive particle is a conductive particle having a non-conductive core and a conductive layer disposed on the core. The second conductive particle is a conductive particle other than the first conductive particle. The adhesive composition typically further includes an adhesive component in which the first and second conductive particles are dispersed.

[0030] Adhesive components can be composed of materials that exhibit curing properties through heat or light, such as epoxy adhesives, free-radical curing adhesives, thermoplastic adhesives such as polyurethane and polyethylene. From the viewpoint of excellent heat and moisture resistance after bonding, adhesive components can also be composed of cross-linking materials. Among these substances, epoxy adhesives containing epoxy resin as a thermosetting resin as the main component are preferred, considering their ability to cure quickly, good bonding workability, and excellent adhesion. Free-radical curing adhesives, compared to epoxy adhesives, have superior curing properties at low temperatures and in short time, and can therefore be used appropriately depending on the application.

[0031] Epoxy-based adhesives may contain thermosetting materials such as epoxy resin and curing agents, and may also contain thermoplastic resins, coupling agents, fillers, etc. as needed.

[0032] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenolic varnish type epoxy resin, cresol phenolic varnish type epoxy resin, bisphenol A phenolic varnish type epoxy resin, bisphenol F phenolic varnish type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, and aliphatic chain epoxy resin. These epoxy resins can be halogenated, hydrogenated, or have a structure with acryloyl or methacryloyl groups added to the side chains. These epoxy resins can be used alone or in combination of two or more.

[0033] There are no particular limitations on any curing agent that can cure epoxy resin, such as anionic polymeric catalyst-type curing agents, cationic polymeric catalyst-type curing agents, and addition polymeric curing agents. Among these substances, anionic or cationic polymeric catalyst-type curing agents are preferred from the perspective of excellent rapid curing performance and without needing to consider stoichiometry.

[0034] As a catalyst-type curing agent for anionic or cationic polymerization, examples include imidazole-based, hydrazide-based, boron trifluoride-amine complexes, etc. Salts (aromatic sulfonate, aromatic diazo salts) Salts, aliphatic sulfonate salts, etc.), aminoimides, diaminomaleonitrile, melamine and its derivatives, polyamine salts, dicyandiamide, etc., and their modified forms can also be used. Examples of addition polymerization curing agents include polyamines, polythiols, polyphenols, and acid anhydrides.

[0035] Potential curing agents that are microencapsulated by coating with polymers such as polyurethane and polyester, metal films such as nickel and copper, or inorganic materials such as calcium silicate are preferred because they can extend the usable time. One curing agent can be used alone, or two or more can be used in combination.

[0036] The content of the curing agent can be 0.05 to 20 parts by weight relative to the total mass of the thermosetting material and the thermoplastic resin to be formulated as needed, for a total of 100 parts by weight.

[0037] Free radical curing adhesives may contain free radical polymerizable materials and free radical polymerization initiators (also known as curing agents), and may further contain thermoplastic resins, coupling agents, fillers, etc. as needed.

[0038] As free radical polymerizable materials, any substance having functional groups that can polymerize via free radicals can be used without particular restrictions. Specifically, examples include acrylate (including corresponding methacrylates, hereinafter the same) compounds, acryloxy (including corresponding methacryloyloxy, hereinafter the same) compounds, maleimide compounds, citrileimide resins, nadimidimide resins, and other free radical polymerizable substances. These free radical polymerizable substances can be in the form of monomers or oligomers, or in the form of a mixture of monomers and oligomers.

[0039] Examples of acrylate compounds include methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, 2-hydroxy-1,3-diacryloyloxypropane, 2,2-bis[4-(acryloyloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloyloxypolyethoxy)phenyl]propane, dicyclopentenyl acrylate, tricyclodecyl acrylate, tri(acryloyloxyethyl)isocyanurate, carbamate acrylate, and phosphate diacrylate.

[0040] Free radical polymerizable substances such as acrylate compounds can also be used with polymerization inhibitors such as hydroquinone and methyl ether hydroquinone, as needed. From the viewpoint of improving heat resistance, free radical polymerizable substances such as acrylate compounds preferably have at least one substituent such as a dicyclopentenyl, tricyclodecyl, or triazine ring. As free radical polymerizable substances other than acrylate compounds, compounds described in International Publication No. 2009 / 063827 can be used, for example. Free radical polymerizable substances can be used alone or in combination of two or more.

[0041] As free radical polymerization initiators, any compound that generates free radicals through decomposition by heating or light irradiation can be used without particular restrictions. Specifically, examples include peroxide compounds and azo compounds. These compounds can be appropriately selected based on the target bonding temperature, bonding time, shelf life, etc.

[0042] More specifically, examples of free radical polymerization initiators include acyl peroxides, dicarbonates peroxides, ester peroxides, ketals peroxides, dialkyl peroxides, hydrogen peroxides, and silane peroxides. Among these substances, ester peroxides, dialkyl peroxides, hydrogen peroxides, and silane peroxides are preferred, and highly reactive ester peroxides are more preferred. Compounds described in International Publication No. 2009 / 063827 can be suitably used as these free radical polymerization initiators, for example. One free radical polymerization initiator can be used alone or in combination of two or more.

[0043] The content of the free radical polymerization initiator can be 0.1 to 10 parts by mass relative to the total mass of the free radical polymerizable material and the thermoplastic resin to be formulated as needed, per 100 parts by mass.

[0044] In epoxy adhesives and free radical curing adhesives, thermoplastic resins, when added as needed, readily impart film properties to the adhesive. Examples of thermoplastic resins include phenoxy resins, polyvinyl formal resins, polystyrene resins, polyvinyl butyral resins, polyester resins, polyamide resins, xylene resins, polyurethane resins, polyester urethane resins, phenolic resins, and terpene phenolic resins. Compounds described in International Publication No. 2009 / 063827 can be suitably used as thermoplastic resins. Among these substances, phenoxy resins are preferred from the viewpoint of excellent adhesion, compatibility, heat resistance, and mechanical strength. One thermoplastic resin may be used alone, or two or more may be used in combination.

[0045] When incorporated into epoxy adhesives, the content of thermoplastic resin may be 5 to 80 parts by weight relative to 100 parts by weight of the combined thermoplastic resin and thermosetting material. When incorporated into free radical curing adhesives, the content of thermoplastic resin may be 5 to 80 parts by weight relative to 100 parts by weight of the combined thermoplastic resin and free radical polymerizing substance.

[0046] Other examples of adhesive components include thermoplastic resins, free radical polymeric materials containing free radical polymeric substances that are liquid at 30°C, and thermoplastic polymerization initiators. Thermoplastic curable adhesives have lower viscosity compared to the adhesive components described above. The content of the free radical polymeric substance in the thermoplastic curable adhesive is preferably 20 to 80 parts by weight, more preferably 30 to 80 parts by weight, and even more preferably 40 to 80 parts by weight, relative to 100 parts by weight of the combined amount of thermoplastic resin and free radical polymeric substance.

[0047] The adhesive component may also be an epoxy-based adhesive containing a thermoplastic resin, a thermosetting material containing an epoxy resin that is liquid at 30°C, and a curing agent. In this case, the epoxy resin content in the epoxy-based adhesive is preferably 20 to 80 parts by weight, more preferably 40 to 80 parts by weight, and even more preferably 30 to 80 parts by weight, relative to 100 parts by weight of the combined amount of the thermoplastic resin and the thermosetting material.

[0048] When adhesive compositions are used to bond IC chips to glass substrates, flexible printed circuit boards (FPCs), etc., from the viewpoint of suppressing substrate warping caused by the difference in the coefficients of linear expansion between the IC chip and the substrate, the adhesive composition preferably further contains components that play a role in mitigating internal stress. Specifically, such components include acrylic rubber, elastomer components, etc. Alternatively, the adhesive composition may be a free radical curing adhesive as described in International Publication No. 98 / 44067.

[0049] In one embodiment, the first conductive particle has a protrusion that, when the adhesive composition is used for connecting electronic components to each other (details to be described later), can penetrate the oxide film formed on the electrode surface in the electronic component (hereinafter, for convenience, sometimes referred to as "the first conductive particle according to the first embodiment"). The first conductive particle may have one or more such protrusions.

[0050] In another embodiment, the first conductive particle is a conductive particle with a pointed protrusion (hereinafter, for convenience, it is sometimes referred to as "the first conductive particle according to the second embodiment"). That is, in the first conductive particle according to the second embodiment, the front end of the protrusion is pointed, or sharp. The front end of the protrusion can be, for example, conical. The first conductive particle may have one or more such protrusions.

[0051] The first conductive particle in the first embodiment and the first conductive particle in the second embodiment may also have anisotropic shapes. In this specification, "conductive particle having anisotropic shape" means conductive particle with shape anisotropy, and refers to conductive particle that is not a conductive particle with a substantially point-symmetric (substantially isotropic) shape (e.g., spherical).

[0052] The aspect ratio of the first conductive particle having an anisotropic shape may be less than or equal to 0.7, less than or equal to 0.6, or less than or equal to 0.5, and may be greater than or equal to 0.1, greater than or equal to 0.2, or greater than or equal to 0.3. The aspect ratio of the first conductive particle is defined as the ratio (B / A) of the maximum length A of the straight line connecting one end of the first conductive particle to the maximum length B of the diameter of the circumcircle of the first conductive particle that is perpendicular to the straight line.

[0053] The first conductive particle in the first embodiment and the first conductive particle in the second embodiment may also be dendritic (also called dendritic). Figure 1(a) is a schematic diagram showing dendritic conductive particles. As shown in the figure, the dendritic conductive particle 1A has a main axis 2 and multiple branches 3 branching from the main axis 2 in two or three dimensions. In the dendritic conductive particle 1A, each of the multiple branches 3 forms a pointed protrusion 4a. Because the protrusion 4a is pointed, it is possible to penetrate the oxide film formed on the electrode surface in the electronic component when the adhesive composition is used to connect electronic components to each other.

[0054] The first conductive particle in the first embodiment and the first conductive particle in the second embodiment may also be in the form of a thin sheet. Figure 1 (b) is a schematic diagram showing the sheet-like conductive particles. As shown in the figure, the sheet-like conductive particles 1B are plate-shaped (also called flat or scale-like) with a main surface 5 that is either planar or curved. The sheet-like conductive particles 1B may have pointed protrusions 4b on their outer edge 6, or they may have pointed protrusions (not shown) on their main surface 5. Because the protrusions 4b are pointed, they can penetrate the oxide film formed on the electrode surface in the electronic components when the adhesive composition is used to connect electronic components to each other.

[0055] The first conductive particle can be formed from metals such as copper and silver, or it can be silver-coated copper particles made by coating copper particles with silver.

[0056] The first conductive particle can be a known conductive particle. In the case of dendritic conductive particles, specifically, it can be obtained as ACBY-2 (Mitsui Metals & Minerals Co., Ltd.), CE-1110 (Fukuda Metal Foil & Powder Co., Ltd.), #FSP (JX Metals Co., Ltd.), or #51-R (JX Metals Co., Ltd.). Alternatively, the first conductive particle can also be manufactured by a known method (for example, if it is a dendritic conductive particle, the method described in Patent Document 1 above; if it is a sheet-like conductive particle, the method of crushing and processing spherical conductive particles using a ball mill or the like).

[0057] In addition to the above, the first conductive particle may also be a needle-shaped conductive particle (e.g., a needle-shaped conductive particle obtained by coating silver onto potassium titanate fiber (which can be obtained as YTA-1575 (Yokozawa Metal Industry Co., Ltd.))) or an amorphous conductive particle (e.g., an amorphous conductive particle obtained by coating copper onto graphite (which can be obtained as CC-13D (Yokozawa Metal Industry Co., Ltd.))).

[0058] The content of the first conductive particles, based on the total volume of the solid components in the adhesive composition, can be greater than or equal to 2% by volume, or greater than or equal to 8% by volume, or less than or equal to 25% by volume, or less than or equal to 15% by volume.

[0059] The second conductive particle has a non-conductive core and a conductive layer disposed on the core. The core is formed of a non-conductive material such as glass, ceramic, or resin, preferably resin. Examples of resins include acrylic resin, styrene resin, silicone resin, polybutadiene resin, or copolymers of monomers constituting these resins. The average particle size of the core can be, for example, 2 to 30 μm.

[0060] The conductive layer is formed, for example, of gold, silver, copper, nickel, palladium, or alloys thereof. From the viewpoint of excellent conductivity, the conductive layer preferably contains at least one selected from gold, nickel, and palladium, more preferably gold or palladium, and even more preferably gold. The conductive layer is formed, for example, by plating the aforementioned metal onto a core. The thickness of the conductive layer can be, for example, 10–400 nm.

[0061] The second conductive particles can be, for example, substantially spherical. Regarding the average particle size of the second conductive particles, from the viewpoint of enabling suitable thinning of the film when the adhesive composition is in film form, it is preferably less than or equal to 30 μm, more preferably less than or equal to 25 μm, and even more preferably less than or equal to 20 μm. The average particle size of the second conductive particles can, for example, be greater than or equal to 1 μm. The average particle size of the second conductive particles can be measured using a particle size distribution measuring device (Microtrac, Nikkiso Co., Ltd.) employing laser diffraction and scattering methods.

[0062] The content of the second conductive particles, based on the total volume of the solid components in the adhesive composition, can be greater than or equal to 2% by volume, or greater than or equal to 5% by volume, or less than or equal to 20% by volume, or less than or equal to 10% by volume.

[0063] The volume ratio of the first conductive particle to the second conductive particle in the adhesive composition (first conductive particle / second conductive particle) is preferably greater than or equal to 1 / 1, more preferably greater than or equal to 2 / 1, even more preferably greater than or equal to 3 / 1, preferably less than or equal to 20 / 1, more preferably less than or equal to 10 / 1, and even more preferably less than or equal to 6 / 1.

[0064] The adhesive composition may be, for example, in film form. Figure 2 This is a schematic cross-sectional view illustrating one embodiment of a film-like adhesive composition (adhesive film). For example... Figure 2 As shown, the adhesive film (film-like adhesive composition) 11 contains adhesive component 12, first conductive particles 1A and second conductive particles 13 dispersed in the adhesive component 12.

[0065] The thickness of the adhesive film 11 can be, for example, less than or equal to 30 μm, less than or equal to 25 μm, or less than or equal to 20 μm, or greater than or equal to 5 μm, greater than or equal to 7 μm, or greater than or equal to 10 μm.

[0066] Adhesive film 11 is obtained, for example, by coating a paste-like adhesive composition onto a resin film such as a PET (polyethylene terephthalate) film and then drying it.

[0067] The adhesive film can also be composed of multiple adhesive layers. In this case, the first conductive particle 1A and the second conductive particle 13 need only be contained in at least one of the multiple adhesive layers, and they can be contained in the same adhesive layer or in different adhesive layers.

[0068] The adhesive composition may be, for example, a paste. A paste-like adhesive composition is obtained, for example, by heating or dissolving a mixture comprising an adhesive component, a first conductive particle, and a second conductive particle in a solvent. As a solvent, for example, a solvent with a boiling point of 50–150°C at atmospheric pressure is used.

[0069] The adhesive composition can be cured, for example, by heat treatment. The heating temperature is, for example, 40°C to 250°C. The heating time is, for example, 0.1 seconds to 10 hours.

[0070] The adhesive composition can be bonded to the substrate by means of heating and pressurization. The heating temperature is, for example, 50 to 190°C. The pressure is, for example, 0.1 to 30 MPa. These heating and pressurization are carried out, for example, in the range of 0.5 seconds to 120 seconds.

[0071] The adhesive composition described in this embodiment can be used as an adhesive for bonding similar types of substrates together, and also as an adhesive for bonding different types of substrates (e.g., substrates with different coefficients of thermal expansion) together. The adhesive composition is suitable for connecting electronic components to each other.

[0072] Figure 3 This is a schematic cross-sectional view of a main part of an example illustrating how electronic components are interconnected. (e.g.) Figure 3 As shown, the first electronic component 14 and the second electronic component 15 are electrically connected to each other through the circuit connection material 16.

[0073] The first electronic component 14 includes a first substrate 17 and a first electrode 18 formed on the main surface of the first substrate 17. The second electronic component 15 includes a second substrate 19 and a second electrode 20 formed on the main surface of the second substrate 19.

[0074] The first substrate 17 and the second substrate 19 can be substrates formed of glass, ceramic, polyimide, polycarbonate, polyester, polyethersulfone, etc. The first electrode 18 and the second electrode 20 can be electrodes formed of gold, silver, copper, tin, aluminum, ruthenium, rhodium, palladium, osmium, iridium, platinum, indium tin oxide (ITO), etc.

[0075] The circuit connection material 16 comprises a cured product 21 containing first conductive particles 1A, second conductive particles 13, and adhesive components. That is, the circuit connection material 16 is a material formed by curing the aforementioned adhesive composition.

[0076] Even when the first electrode 18 and the second electrode 20 are formed of materials that readily form oxide films on their surfaces (e.g., copper, aluminum), the adhesive composition according to this embodiment is capable of suitably connecting the electronic components 14 and 15 to each other. This is believed to be because the first conductive particle 1A and the second conductive particle 13 are used together in the adhesive composition. That is, it is believed that, as Figure 3 As shown, the second conductive particle 13 forms the main conductive path that enables the first electrode 18 and the second electrode 20 to conduct to each other. On the other hand, the first conductive particle 1A assists in the electrical connection between the second conductive particle 13 and each electrode 18, 20, thereby achieving a suitable connection. More specifically, the inventors speculate that since the first conductive particle 1A is a dendritic conductive particle, even when an oxide film is formed on the surface of the electrodes 18, 20, the first conductive particle 1A can penetrate the oxide film through the pointed protrusion 4a in the first conductive particle 1A, thereby being able to contact the electrodes 18, 20. As a result, the second conductive particle 13 can be properly connected to each electrode 18, 20.

[0077] Therefore, according to the adhesive composition of this embodiment, even when connecting electronic components 14 and 15 to each other under low voltage, excellent conductivity can be obtained, for example, compared to adhesive compositions containing only first conductive particles 1A as conductive particles (without conductive particles forming the main conductive path that connects the first electrode 18 and the second electrode 20 to each other) and adhesive compositions containing only second conductive particles 13 as conductive particles (without conductive particles that assist in the electrical connection between the second conductive particles 13 and each electrode 18 and 20).

[0078] In addition, according to the adhesive composition of this embodiment, even when the pressure is increased when connecting electronic components 14 and 15 to each other in order to obtain the desired conductivity, since the second conductive particle 13 forming the main conductive path also acts to block the flow of adhesive component 12, for example, compared with an adhesive composition that only contains the first conductive particle 1A as a conductive particle (in the case where there is no conductive particle to block adhesive component 12), it is possible to suppress the flow of adhesive component 12 from between electronic components 14 and 15.

[0079] In the connection of electronic components, dendritic conductive particles 1A were used as the first conductive particles as described above. However, other first conductive particles, such as sheet-like conductive particles 1B, as described in the first embodiment or the second embodiment, can also be used as the first conductive particles. Even in this case, as described above, electronic components 14 and 15 can be properly connected to each other. Furthermore, excellent conductivity can be obtained when connecting under low voltage, and the outflow of adhesive components during connection can be suppressed.

[0080] Example

[0081] The present invention will be further described in detail below based on embodiments, but the present invention is not limited to the following embodiments.

[0082] (Preparation of solution A1)

[0083] 50g of phenoxy resin (manufactured by Union Carbide Corporation, product name: PKHC, weight average molecular weight: 45000) was dissolved in a mixed solvent of toluene (boiling point: 110.6℃) and ethyl acetate (boiling point: 77.1℃) (toluene:ethyl acetate = 1:1 by mass) to obtain a phenoxy resin solution with a solid content of 40% by mass. A solution A1 was prepared by mixing urethane acrylate (manufactured by Neage Kogyo Co., Ltd., product name: UN7700) and dimethacrylate phosphate (manufactured by Kyoeisha Chemical Co., Ltd., product name: LIGHT ESTER P-2M) as free radical polymerizable substances with 1,1-bis(tert-hexylperoxy)-3,3,5-trimethylcyclohexane (manufactured by Nippon Yushi Co., Ltd., product name: PERHEXATMH) as curing agent in a phenoxy resin solution at a solid mass ratio of phenoxy resin:urethane acrylate:dimethacrylate phosphate:curing agent = 10:10:3:2.

[0084] As the conductive particle B1 (first conductive particle), dendritic conductive particles (silver-coated copper particles, product name: ACBY-2, manufactured by Mitsui Metals Mining Co., Ltd.) are used.

[0085] (Preparation of the nucleus (resin particles))

[0086] Benzoyl peroxide, acting as a polymerization initiator, was added to a mixed solution of divinylbenzene, styrene monomer, and butyl methacrylate. The mixture was heated while being stirred at high speed and uniformly to induce a polymerization reaction, resulting in a particulate dispersion. This dispersion was then filtered and dried under reduced pressure to obtain a blocky aggregate of particles. Furthermore, this blocky aggregate was pulverized to produce cores (resin particles) with an average particle diameter of 20 μm, each exhibiting a different crosslinking density.

[0087] (The fabrication of conductive particles C1)

[0088] A palladium catalyst (manufactured by MUROMACHI TECHNOS, product name: MK-2605) was supported on the surface of the core. The core, activated with an accelerator (manufactured by MUROMACHI TECHNOS, product name: MK-370), was then immersed in a mixture of nickel sulfate aqueous solution, sodium hypophosphite aqueous solution, and sodium tartrate aqueous solution heated to 60°C for a pre-electrolytic plating process. The mixture was stirred for 20 minutes to confirm that hydrogen foaming had stopped. Next, a mixed solution of nickel sulfate, sodium hypophosphite, sodium citrate, and plating stabilizer was added, and the mixture was stirred until the pH stabilized. A post-electrolytic plating process was then performed until hydrogen foaming stopped. Finally, the plating solution was filtered, the filtrate was washed with water, and then dried in a vacuum dryer at 80°C to produce nickel-plated conductive particles C1 (second conductive particles).

[0089] (The fabrication of conductive particles C2)

[0090] Nickel-plated conductive particles C1 were added to a mixed solution of sodium chloroaurate and ion-exchanged water and mixed. Then, ammonium thiosulfate, ammonium sulfite, and ammonium hydrogen phosphate were added to prepare the plating solution. Hydroxylamine was added to the obtained plating solution, and the pH was adjusted to 10 using ammonia. The bath temperature was set to 65°C, and the reaction was allowed to proceed for about 20 minutes to produce conductive particles C2 (the second conductive particles) with a gold-plated outermost layer.

[0091] (The fabrication of conductive particles C3)

[0092] Nickel-plated conductive particles C1 were added to a mixed solution containing tetrachloropalladium, ethylenediamine, aminopyridine, sodium hypophosphite, polyethylene glycol, and deionized water. The pH was then adjusted to 7.5 using ammonia, and the bath temperature was set to 60°C. The mixture was allowed to react for about 20 minutes to produce conductive particles C3 (the second conductive particles) with a palladium-plated outermost layer.

[0093] [Example 1]

[0094] <Film Formation of Adhesive Compositions>

[0095] 45 parts by volume of conductive particles B1 and 15 parts by volume of conductive particles C1 were dispersed relative to 100 parts by volume of solution A1 to obtain a mixed solution. The obtained mixed solution was coated onto a fluoropolymer film with a thickness of 80 μm, and the solvent was removed by hot air drying at 70°C for 10 minutes to obtain a film-like adhesive composition with a thickness of 25 μm formed on the fluoropolymer film.

[0096] The reliability of using the obtained film adhesive composition as a circuit connection material is evaluated through the steps shown below.

[0097] <Evaluation of conductivity during low-voltage connections>

[0098] like Figure 4 As shown in (a) and (b), the obtained film-like adhesive composition was cut into 6mm × 6mm adhesive films 31, and placed approximately in the center of a 6mm × 50mm copper foil 32. It was then bonded using a BD-07 adhesive press manufactured by Ohashi Manufacturing Co., Ltd. (50°C, 0.1MPa, 2 seconds). Next, as... Figure 4 As shown in (c) and (d), a 50mm × 6mm aluminum foil 33 is prepared. For the laminate of copper foil 32 and adhesive film 31, the adhesive film 31 is overlapped in a covering manner. Heating and pressurizing (150°C, 0.1MPa, 10 seconds) is performed using a BD-07 heat exchanger manufactured by Ohashi Manufacturing Co., Ltd., to obtain a mounting body for evaluating conductivity under low-voltage connections. Regarding the obtained mounting body, as... Figure 5 The ammeter and voltmeter are connected as shown, and the connection resistance (initial) is measured using the four-terminal method. The results are shown in Table 1.

[0099] <Evaluation of the inhibition of efflux of adhesive components>

[0100] First, when the mounting body is manufactured using the same steps as described in the "Evaluation of Conductivity under Low Voltage Connection" above, the pressure required for the obtained mounting body to achieve a connection resistance (initial) of 0.20Ω (the pressure when the adhesive film 31 is overlapped on the laminate of the copper foil 32 and the adhesive film 31 and then heated and pressurized) P (MPa) is calculated.

[0101] Next, the outflow of the adhesive component was evaluated using the following steps. Specifically, the obtained film-like adhesive composition and the fluoropolymer film were cut together into 3mm × 3mm squares to obtain an adhesive film with a fluoropolymer film. The adhesive film with the fluoropolymer film was placed approximately in the center of a square coverslip (model C018181) made of Matsunami Glass, and then heated and pressurized using a BD-07 manufactured by Ohashi Corporation (60°C, 0.1 MPa, 2 seconds) before peeling off the fluoropolymer film. Next, another identical coverslip was placed on the adhesive film, and heated and pressurized using a BD-07 manufactured by Ohashi Corporation (130°C, the calculated pressure P (MPa), 10 seconds). Using a scanner and Photoshop (registered trademark), the area of ​​the peeled fluoropolymer film [A] and the area of ​​the heated and pressurized adhesive film [B] were measured in pixels, and the outflow was calculated according to the following formula. The results are shown in Table 1.

[0102] Outflow (%) = ([B] / [A]) × 100

[0103] <Reliability Evaluation>

[0104] like Figure 4 As shown in (a) and (b), the obtained film-like adhesive composition was cut into 6mm × 6mm adhesive films 31, and placed approximately in the center of a 6mm × 50mm copper foil 32. It was then bonded using a BD-07 adhesive press manufactured by Ohashi Manufacturing Co., Ltd. (50°C, 0.5MPa, 2 seconds). Next, as... Figure 4 As shown in (c) and (d), prepare an aluminum foil 33 of 50mm × 6mm. For the laminate of copper foil 32 and adhesive film 31, overlap the adhesive film 31 in a covering manner and heat and pressurize it (150°C, 0.5MPa, 10 seconds) using BD-07 manufactured by Ohashi Manufacturing Co., Ltd. to obtain the mounting body for reliability evaluation.

[0105] For the obtained mounting body, such as Figure 5 The connection resistance (initial) was measured using a 4-terminal method with a galvanometer and voltmeter connected as shown. Additionally, the connection resistance (after the thermal cycle test) was measured using a TSA-43EL (manufactured by ESPEC Corporation) after performing the following thermal cycling test on the mounting body. In the thermal cycle test, the temperature was maintained at -20°C for 30 minutes, then increased to 100°C over 10 minutes, maintained at 100°C for 30 minutes, and then decreased to -20°C over 10 minutes. This thermal cycle was repeated 500 times. If the connection resistance after the thermal cycle test is less than or equal to 0.5Ω, the reliability is considered good. The results are shown in Table 1.

[0106] [Examples 2-4, Comparative Examples 1-4]

[0107] The composition of the adhesive composition was modified as shown in Tables 1 and 2. Otherwise, the same procedure as in Example 1 was followed to prepare the adhesive composition and evaluate the conductivity, efflux suppression, and reliability of the adhesive components during low-pressure bonding. The results are shown in Tables 1 and 2.

[0108] [Table 1]

[0109]

[0110] [Table 2]

[0111]

[0112] Symbol Explanation

[0113] 1A: First conductive particle (dendritic conductive particle), 1B: First conductive particle (sheet-like conductive particle), 4a, 4b: protrusions, 11: adhesive film (film-like adhesive composition), 12: adhesive component, 13: second conductive particle.

Claims

1. An adhesive composition for connecting electronic components to each other, comprising: The first conductive particle is a conductive particle with protrusions, the protrusions being able to penetrate the oxide film formed on the electrode surface in the electronic component, and The second conductive particle is a conductive particle other than the first conductive particle, and it is a conductive particle having a non-conductive core and a conductive layer disposed on the core. The average particle size of the second conductive particles is greater than or equal to 1 μm and less than or equal to 30 μm. The content of the first conductive particles, based on the total volume of the solid components in the adhesive composition, is greater than or equal to 2% by volume and less than or equal to 25% by volume. The content of the second conductive particles, based on the total volume of the solid components in the adhesive composition, is greater than or equal to 2% by volume and less than or equal to 20% by volume. The volume ratio of the first conductive particle to the second conductive particle in the adhesive composition is greater than or equal to 1 / 1 and less than or equal to 20 / 1.

2. An adhesive composition comprising: The first conductive particle is a conductive particle with a pointed protrusion, and The second conductive particle is a conductive particle other than the first conductive particle, and it is a conductive particle having a non-conductive core and a conductive layer disposed on the core. The average particle size of the second conductive particles is greater than or equal to 1 μm and less than or equal to 30 μm. The content of the first conductive particles, based on the total volume of the solid components in the adhesive composition, is greater than or equal to 2% by volume and less than or equal to 25% by volume. The content of the second conductive particles, based on the total volume of the solid components in the adhesive composition, is greater than or equal to 2% by volume and less than or equal to 20% by volume. The volume ratio of the first conductive particle to the second conductive particle in the adhesive composition is greater than or equal to 1 / 1 and less than or equal to 20 / 1.

3. The adhesive composition according to claim 1 or 2, wherein the first conductive particle is a conductive particle having an anisotropic shape.

4. The adhesive composition according to claim 1 or 2, wherein the first conductive particle is a dendritic conductive particle.

5. The adhesive composition according to claim 1 or 2, wherein the first conductive particle is a sheet-like conductive particle.

6. The adhesive composition according to claim 1 or 2, wherein the second conductive particle is a generally spherical conductive particle.

7. The adhesive composition according to claim 1 or 2, wherein the conductive layer contains at least one selected from the group consisting of gold, nickel and palladium.

8. An electronic component, comprising a first electronic component and a second electronic component connected together, comprising: First electronic component, Second electronic component, and Circuit connection material that electrically connects the first electronic component and the second electronic component to each other. The circuit connection material is a cured product containing first conductive particles, second conductive particles, and adhesive components. The first conductive particle is a conductive particle with protrusions, the protrusions being able to penetrate the oxide film formed on the electrode surfaces of the first electronic component and the second electronic component. The second conductive particle is a conductive particle other than the first conductive particle, and it is a conductive particle having a non-conductive core and a conductive layer disposed on the core. The average particle size of the second conductive particles is greater than or equal to 1 μm and less than or equal to 30 μm. The content of the first conductive particles, based on the total volume of the circuit connection material, is greater than or equal to 2% by volume and less than or equal to 25% by volume. The content of the second conductive particles, based on the total volume of the circuit connection material, is greater than or equal to 2% by volume and less than or equal to 20% by volume. The volume ratio of the first conductive particle to the second conductive particle in the circuit connection material is greater than or equal to 1 / 1 and less than or equal to 20 / 1.

9. An electronic component, comprising a first electronic component and a second electronic component connected together, comprising: First electronic component, Second electronic component, and Circuit connection material that electrically connects the first electronic component and the second electronic component to each other. The circuit connection material is a cured product containing first conductive particles, second conductive particles, and adhesive components. The first conductive particle is a conductive particle with a pointed protrusion. The second conductive particle is a conductive particle other than the first conductive particle, and it is a conductive particle having a non-conductive core and a conductive layer disposed on the core. The average particle size of the second conductive particles is greater than or equal to 1 μm and less than or equal to 30 μm. The content of the first conductive particles, based on the total volume of the circuit connection material, is greater than or equal to 2% by volume and less than or equal to 25% by volume. The content of the second conductive particles, based on the total volume of the circuit connection material, is greater than or equal to 2% by volume and less than or equal to 20% by volume. The volume ratio of the first conductive particle to the second conductive particle in the circuit connection material is greater than or equal to 1 / 1 and less than or equal to 20 / 1.

10. The electronic component according to claim 8 or 9, wherein the first conductive particle is a conductive particle having an anisotropic shape.

11. The electronic component according to claim 8 or 9, wherein the first conductive particle is a dendritic conductive particle.

12. The electronic component according to claim 8 or 9, wherein the first conductive particle is a sheet-like conductive particle.

13. The electronic component according to claim 8 or 9, wherein the second conductive particle is a generally spherical conductive particle.

14. The electronic component according to claim 8 or 9, wherein the conductive layer contains at least one selected from the group consisting of gold, nickel and palladium.

15. The electronic component according to claim 8 or 9, wherein an oxide film is formed on the electrode surface of at least one of the first electronic component and the second electronic component.

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