Adhesive film and connection structure

Abstract

An adhesive film containing: an adhesive component; a first conductive particle that is a dendritic conductive particle; and second conductive particles that are conductive particles other than the first conductive particles and that have a non-conductive core and a conductive layer provided on the core, the flow rate of the adhesive film being 10-50%.

Description

TECHNICAL FIELD

[0001] The present application relates to an adhesive film and a connected structure. BACKGROUND

[0002] In recent years, various adhesives are used for the fixation of electronic parts, the connection of circuits, and the like in the fields of semiconductors, liquid crystal displays, and the like. In these uses, the high density and high fineness of electronic parts, circuits, and the like are being developed, and higher performance is required for the adhesives.

[0003] For example, in the connection of a liquid crystal display and a TCP (Tape Carrier Package), the connection of an FPC (Flexible Printed Circuit) and a TCP, or the connection of an FPC and a printed circuit board, an adhesive in which conductive particles are dispersed (a conductive adhesive) is used. The conductive adhesive is sometimes required to have excellent connection reliability when electronic parts connected at low pressure (for example, 0.1 to 0.5 MPa) are connected to each other.

[0004] For example, Patent Literature 1 describes that it has been found that an isotropic conductive pressure-sensitive adhesive sheet formed of a pressure-sensitive adhesive containing a specific acrylic resin, a specific amount of an isocyanate-based curing agent, and a specific amount of dendritic conductive particles, and having a ratio of the thickness of the pressure-sensitive adhesive sheet to the median diameter D50 of the dendritic conductive particles within a specific range is easily adhered to an adherend with high bonding force, has excellent electrical connection stability, and has a small change in resistance value after a thermal cycle test.

[0005] Prior Art Documents

[0006] Patent Literature

[0007] Patent Literature 1: International Publication No. 2020-241818 SUMMARY

[0008] Technical Problem to be Solved by the Invention

[0009] An object of one aspect of the present application is to provide an adhesive film that can suppress the increase rate of resistance before and after a thermal cycle test to be low.

[0010] Means for Solving the Technical Problem

[0011] One aspect of the present application relates to an adhesive film containing: an adhesive component; first conductive particles which are dendritic conductive particles; and second conductive particles which are conductive particles other than the first conductive particles and which are conductive particles having a non-conductive core and a conductive layer provided on the core, the adhesive film having a flow rate of 10% to 50%.

[0012] In one aspect of the present application, the volume ratio of the content of the first conductive particles to the content of the second conductive particles can be 5 / 1 or more.

[0013] In one aspect of the present application, the total content of the first conductive particles and the second conductive particles can be 20 parts by volume or more per 100 parts by volume of the content of the adhesive component.

[0014] In one aspect of the present application, the total content of the first conductive particles and the second conductive particles can be 55 parts by volume or less per 100 parts by volume of the content of the adhesive component.

[0015] Another aspect of the present application relates to a connection structure body including: a first electronic component having a first substrate and a first electrode formed on the first substrate; a second electronic component having a second substrate and a second electrode formed on the second substrate; and a connection component electrically connecting the first electrode and the second electrode to each other, the connection component including a cured product of the above-described adhesive film.

[0016] Effects of the Invention

[0017] According to one aspect of the present application, it is possible to provide an adhesive film which can suppress an increase in resistance before and after a thermal cycle test to be low. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a schematic cross-sectional view showing one embodiment of the adhesive film.

[0019] Figure 2 is a schematic cross-sectional view showing one embodiment of the connection structure body.

[0020] Figure 3 is a schematic view showing a method for producing a mounting body for reliability test.

[0021] Figure 4 is a schematic view showing a method for measuring connection resistance in reliability test.

[0022] Figure 5 is a schematic plan view showing a laminate in peel strength measurement. DETAILED DESCRIPTION

[0023] Hereinafter, one embodiment of the present application will be described in detail with appropriate reference to the drawings.

[0024] Figure 1 is a schematic cross-sectional view showing an embodiment of the adhesive film. As shown in Figure 1 the adhesive film 10 contains an adhesive component 11, first conductive particles 12 which are dendritic conductive particles, and second conductive particles 13 which are conductive particles having a non-conductive core and a conductive layer provided on the core. However, the second conductive particles 13 are conductive particles other than the first conductive particles 12. The first conductive particles 12 and the second conductive particles 13 are dispersed in the adhesive component 11.

[0025] The adhesive component 11 is composed of, for example, a material exhibiting curability by heat or light, and can be a radical-curable adhesive, an epoxy-based adhesive, a thermoplastic adhesive such as a polyurethane, a polyvinyl ester, or the like. Among these, the radical-curable adhesive is preferable because it has excellent curability at low temperature and in a short time, and the like. Also, the epoxy-based adhesive is preferable in terms of short-time curability, good workability, excellent adhesiveness, and the like.

[0026] The radical-curable adhesive contains, for example, a radical-polymerizable substance and a radical polymerization initiator, and, as needed, can further contain a thermoplastic resin, a filler material, other additives, and the like.

[0027] As the radical-polymerizable substance, for example, any substance having a functional group that is polymerized by radicals can be used without particular limitation. Specifically, for example, radical-polymerizable substances such as (meth)acrylate compounds, maleimide compounds, citraconimide resins, nadimide resins, and the like can be given. These radical-polymerizable substances can be in the state of a monomer or an oligomer, or in the state of a mixture of a monomer and an oligomer.

[0028] As the (meth)acrylate compound, for example, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, 2-hydroxy-1,3-bis(meth)acryloyloxypropane, 2,2-bis[4-((meth)acryloyloxymethoxy)phenyl]propane, 2,2-bis[4-((meth)acryloyloxy polyethoxy)phenyl]propane, dicyclopentenyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, isocyanuric acid ethylene oxide (EO)-modified di(meth)acrylate, isocyanuric acid EO-modified tri(meth)acrylate, urethane (meth)acrylate, EO-modified phosphoric acid di(meth)acrylate, and the like can be given.

[0029] As the radical polymerizable substance other than the (meth)acrylate compound, for example, the compound described in International Publication No. 2009-063827 can be preferably used. The radical polymerizable substance can be used alone in one kind or in combination of two or more kinds.

[0030] The content of the radical polymerizable substance can be 10 parts by volume or more, 20 parts by volume or more, 30 parts by volume or more, or 40 parts by volume or more, and can be 80 parts by volume or less, 70 parts by volume or less, or 60 parts by volume or less, with respect to 100 parts by volume of the total amount of the adhesive ingredient 11.

[0031] The content of the radical polymerizable substance can be 30 parts by volume or more, 40 parts by volume or more, or 50 parts by volume or more, and can be 90 parts by volume or less, 80 parts by volume or less, or 70 parts by volume or less, with respect to 100 parts by volume of the total of the radical polymerizable substance and the thermoplastic resin, which is optionally formulated.

[0032] As the radical polymerization initiator, for example, a compound that generates a free radical by decomposition through heating or irradiation of light can be used without particular limitation. Specifically, for example, peroxide compounds, azo compounds, and the like can be mentioned. These compounds can be appropriately selected depending on the target bonding temperature, bonding time, pot life, and the like.

[0033] More specifically, as the radical polymerization initiator, diacyl peroxide, peroxydicarbonate, peroxyester (for example, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane), peroxyketal, dialkyl peroxide, hydroperoxide, silicon-based peroxide, and the like can be mentioned. Among these, peroxyester, dialkyl peroxide, hydroperoxide, silicon-based peroxide, and the like are preferred, and peroxyester, which can obtain high reactivity, is more preferred. As these radical polymerization initiators, for example, the compound described in International Publication No. 2009-063827 can be preferably used. The radical polymerization initiator can be used alone in one kind or in combination of two or more kinds.

[0034] The content of the radical polymerization initiator can be 1 part by volume or more, and can be 10 parts by volume or less, with respect to 100 parts by volume of the total of the radical polymerizable substance and the thermoplastic resin, which is optionally formulated.

[0035] The epoxy-based adhesive contains, for example, an epoxy resin and a curing agent, and, as needed, can further contain a thermoplastic resin, a filler material, other additives, and the like.

[0036] As the epoxy resin, for example, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, a bisphenol A novolac type epoxy resin, a bisphenol F novolac type epoxy resin, an alicyclic epoxy resin, a glycidyl ester type epoxy resin, a glycidyl amine type epoxy resin, a hydantoin type epoxy resin, an isocyanurate type epoxy resin, an aliphatic chain type epoxy resin, and the like can be given. These epoxy resins can be halogenated, can be hydrogenated, or can have a structure in which an acryl group or a methacryl group is added to a side chain. These epoxy resins can be used alone or in combination of two or more.

[0037] The content of the epoxy resin can be 10 parts by volume or more, 20 parts by volume or more, or 30 parts by volume or more, and can be 70 parts by volume or less, 60 parts by volume or less, or 50 parts by volume or less, with respect to 100 parts by volume of the total amount of the adhesive component 11.

[0038] The content of the epoxy resin can be 20 parts by volume or more, 30 parts by volume or more, or 40 parts by volume or more, and can be 80 parts by volume or less, 70 parts by volume or less, or 60 parts by volume or less, with respect to 100 parts by volume of the total amount of the epoxy resin and the thermoplastic resin, which is blended as necessary.

[0039] As the curing agent, there is no particular limitation as long as it is a curing agent capable of curing the epoxy resin, and, for example, an anionically polymerizable catalyst type curing agent, a cationically polymerizable catalyst type curing agent, an addition polymerization type curing agent, and the like can be given. Among these, from the viewpoint that the curing speed is excellent and the chemical equivalent does not need to be considered, an anionically or cationically polymerizable catalyst type curing agent is preferred.

[0040] As the anionically or cationically polymerizable catalyst type curing agent, for example, an imidazole type, a hydrazide type, a boron trifluoride-amine complex, an onium salt (an aromatic sulfonium salt, an aromatic diazonium salt, an aliphatic sulfonium salt, and the like), an amine imide, a diaminomaleonitrile, a melamine and a derivative thereof, a salt of a polyamine, a dicyanediamine, and the like can be given, and a modified product and the like of these can also be used. As the addition polymerization type curing agent, for example, a polyamine, a polythiol, a polyphenol, an acid anhydride, and the like can be given.

[0041] A latent curing agent obtained by coating these curing agents with a high molecular substance such as a polyurethane type or a polyester type, a metal thin film such as nickel or copper, an inorganic substance such as calcium silicate, and the like, and microencapsulating them is preferred because the usable time can be extended. The curing agent can be used alone or in combination of two or more.

[0042] The content of the curing agent can be 0.05 parts by volume or more, and can be 20 parts by volume or less, with respect to 100 parts by volume of the total amount of the epoxy resin and the thermoplastic resin, which is blended as necessary.

[0043] The adhesive component 11 can include a thermoplastic resin. In the case where the radical-curable adhesive or the epoxy-based adhesive includes a thermoplastic resin, it is possible to easily impart film properties to the adhesive. As the thermoplastic resin, for example, phenoxy resin, polyethylene glycol formal resin, polystyrene resin, polyethylene glycol butylal resin, polyester resin, polyamide resin, xylene resin, polyurethane resin, polyester urethane resin, phenol resin, terpene phenol resin, or the like can be given. As the thermoplastic resin, for example, the compound described in International Publication No. 2009 / 063827 can be preferably used. The thermoplastic resin can be used alone or in combination with two or more kinds.

[0044] The content of the thermoplastic resin can be 10 parts by volume or more, 15 parts by volume or more, or 20 parts by volume or more, and can be 50 parts by volume or less, 40 parts by volume or less, or 30 parts by volume or less, with respect to 100 parts by volume of the total amount of the adhesive component 11.

[0045] As an example of the radical-curable adhesive, a thermal radical-curable adhesive containing a radical-polymerizable material including a radical-polymerizable substance that is liquid at 30°C, a radical polymerization initiator, and a thermoplastic resin can be given. The thermal radical-curable adhesive has a tendency to reduce the viscosity. Also, as an example of the epoxy-based adhesive, an epoxy-based adhesive containing a thermosetting material including an epoxy resin that is liquid at 30°C, a curing agent, and a thermoplastic resin can be given.

[0046] A filler material can be mixed in the adhesive component 11. As an example of the filler material, a non-conductive particle can be given. The non-conductive particle can be an inorganic non-conductive particle, or an organic non-conductive particle. As an example of the inorganic non-conductive particle, a silica particle can be given.

[0047] The content of the filler material can be 1% by volume or more, or 3% by volume or more, and can be 25% by volume or less, or 20% by volume or less, with respect to the total volume of the adhesive film 10.

[0048] The adhesive component 11 can include other additives as needed. As an example of the other additives, a coupling agent, a component that exerts a relaxing effect of internal stress, or the like can be given. If the adhesive component 11 further includes a component that exerts a relaxing effect of internal stress, it is possible to suppress warping of a substrate caused by a difference in linear expansion coefficient of an IC chip and the substrate when the adhesive can be used to connect the IC chip, a glass substrate, a flexible printed substrate (FPC), or the like. Specifically, as the component that exerts a relaxing effect of internal stress, an acrylate rubber, an elastomer component, or the like can be given.

[0049] The first conductive particles 12 are dendritic and have one main axis and a plurality of branches branching two-dimensionally or three-dimensionally from the main axis. The first conductive particles 12 can be formed of a metal such as copper, silver, or the like, and can be, for example, silver-coated copper particles in which copper particles are coated with silver.

[0050] The first conductive particles 12 can be publicly known conductive particles, and specifically, for example, can be obtained as ACRYLITE® ACFBY-2 (Mitsui Mining & Smelting Co., Ltd.), CE-1110 (FUKUDA METAL FOIL & POWDER Co., Ltd.), #FSP (JX Metals Corporation), or #51-R (JX Metals Corporation). Alternatively, the first conductive particles 12 can be produced by a publicly known method (for example, the method described in International Publication No. 2014 / 021037).

[0051] The content of the first conductive particles 12 can be 5 vol% or more, 10 vol% or more, 20 vol% or more, 25 vol% or more, or 30 vol% or more, and can be 60 vol% or less, 50 vol% or less, or 45 vol% or less, based on the total volume of the binder film 10.

[0052] The content of the first conductive particles 12 can be 5 vol% or more, 10 vol% or more, 20 vol% or more, 30 vol% or more, 40 vol% or more, or 50 vol% or more, and can be 90 vol% or less, 85 vol% or less, 80 vol% or less, or 70 vol% or less, relative to 100 vol parts of the content of the binder component 11.

[0053] The second conductive particles 13 have a non-conductive core and a conductive layer provided on the core. The core is formed of a non-conductive material such as glass, ceramic, resin, or the like, and is preferably formed of resin. As the resin, for example, an acrylic resin, a styrene resin, a silicone resin, a polybutadiene resin, or a copolymer of monomers constituting these resins can be mentioned. The average particle diameter of the core can be, for example, 2 μm or more, and can be 30 μm or less.

[0054] The conductive layer is formed of, for example, gold, silver, copper, nickel, palladium, or an alloy of these. From the viewpoint of excellent conductivity, the conductive layer preferably contains at least one selected from the group consisting of gold, nickel, and palladium, more preferably contains gold or palladium, and further preferably contains gold. The conductive layer is formed, for example, by plating the above metal on the core. The thickness of the conductive layer can be, for example, 10 nm or more, and can be 400 nm or less.

[0055] The second conductive particles 13 can be substantially spherical, for example. From the viewpoint of being able to thin the adhesive film appropriately, the average particle diameter of the second conductive particles 13 is preferably 30 μm or less, more preferably 25 μm or less, and further preferably 22 μm or less. The average particle diameter of the second conductive particles 13 can be 1 μm or more, for example. The average particle diameter of the second conductive particles 13 is measured by using a particle size distribution measuring device (Microtrac (product name, Nikkiso Co., Ltd.)) using a laser diffraction / scattering method.

[0056] The content of the second conductive particles 13 can be 1 vol% or more, 2 vol% or more, 3 vol% or more, 4 vol% or more, or 5 vol% or more, and can be 30 vol% or less, 20 vol% or less, 15 vol% or less, or 10 vol% or less, based on the total volume of the adhesive film 10.

[0057] The content of the second conductive particles 13 can be 1 vol% or more, 2 vol% or more, 5 vol% or more, 7 vol% or more, or 10 vol% or more, and can be 20 vol% or less, 17 vol% or less, or 15 vol% or less, with respect to 100 parts by volume of the content of the adhesive component 11.

[0058] The volume ratio of the first conductive particles 12 to the second conductive particles 13 (first conductive particles 12 / second conductive particles 13) in the adhesive film can be 0.5 / 1 or more, 1 / 1 or more, 3 / 1 or more, 5 / 1 or more, 6.1 / 1 or more, or 6.5 / 1 or more, and can be 40 / 1 or less, 30 / 1 or less, 25 / 1 or less, 20 / 1 or less, or 15 / 1 or less.

[0059] The total content of the first conductive particles 12 and the second conductive particles 13 can be 10 parts by volume or more, 20 parts by volume or more, 30 parts by volume or more, 35 parts by volume or more, 40 parts by volume or more, or 45 parts by volume or more, and can be 100 parts by volume or less, 90 parts by volume or less, 80 parts by volume or less, 70 parts by volume or less, 60 parts by volume or less, 57 parts by volume or less, or 55 parts by volume or less, with respect to 100 parts by volume of the content of the adhesive component 11.

[0060] In the case where the adhesive component 11 contains a filler material, the total content of the first conductive particles 12 and the second conductive particles 13 can be 10 parts by volume or more, 20 parts by volume or more, 30 parts by volume or more, 35 parts by volume or more, 40 parts by volume or more, or 45 parts by volume or more, and can be 110 parts by volume or less, 100 parts by volume or less, 90 parts by volume or less, 80 parts by volume or less, 70 parts by volume or less, 60 parts by volume or less, 57 parts by volume or less, or 55 parts by volume or less, with respect to 100 parts by volume of the total of the components other than the filler material among the components contained in the adhesive component 11.

[0061] The flowability of the adhesive film 10 is 10% to 50%. This flowability can be 12% or higher, or 20% or higher, and can be 45% or lower, or 40% or lower. When the flowability of the adhesive film 10 is at least the lower limit, reliability is further improved. Furthermore, when the flowability is 50% or lower, the shape stability of the adhesive film is likely to be excellent.

[0062] The flow rate of the adhesive film 10 is an index indicating the fluidity of the adhesive film 10, and refers to the ratio of change in area when the adhesive film 10 is heated and pressurized. Specifically, the flow rate can be calculated by the following method.

[0063] First, prepare a disc-shaped adhesive film with a diameter of 1.0 mm and a fluororesin film (thickness: 80 μm) attached to one side. Place the adhesive film with the fluororesin film attached on the first cover glass (thickness: 0.15 mm) with the adhesive film side in contact with the first cover glass to produce a first laminate (first cover glass / adhesive film / fluororesin film). The first laminate is then thermocompressed from the fluororesin film side under the conditions of a pressing temperature of 60°C, a pressing pressure of 1 MPa, and a pressing time of 0.1 seconds. The pressing temperature is the maximum temperature achieved after pressing for 1 second, and the pressing pressure is the pressure converted to the area of ​​the adhesive film used for evaluation. The maximum temperature achieved is adjusted as follows: Prepare a separate first laminate identical to the above, thermocompress the adhesive film of this laminate and the first cover glass with a thin temperature sensor sandwiched between them, and measure the maximum temperature achieved by the adhesive film in advance.

[0064] Next, the fluororesin film was peeled off, and a second cover glass (thickness: 0.15 mm) was placed on the exposed adhesive film to produce a second laminate (first cover glass / adhesive film / second cover glass). This laminate was then hot-pressed from the second cover glass side under the conditions of a pressing temperature of 170°C, a pressing pressure of 80 MPa, and a pressing time of 5 seconds to obtain a pressed body. The pressing temperature refers to the maximum temperature achieved by the adhesive film, and the pressing pressure refers to the pressure converted to the area of ​​the adhesive film used for evaluation. The maximum temperature achieved was adjusted as follows: a second laminate identical to the above was prepared separately, and hot-pressed with a thin temperature sensor sandwiched between the adhesive film of the second laminate and the first cover glass. The maximum temperature achieved by the adhesive film was measured in advance.

[0065] The obtained press-bonded structure was observed with an optical microscope, and the area (bonding area) S1 (unit: mm) of the bonded portion between the adhesive film and the first cover glass in the press-bonded structure was determined. 2 The bonding area S1 and the area of ​​the adhesive film before thermal compression bonding (0.25π[mm 2 ]), and the flow rate is calculated by the following formula.

[0066] Flow rate [%] = {(adhesion area S1 - 0.25π) / (0.25π)} x 100

[0067] The thickness of the adhesive film 10 can be, for example, 50 μm or less, 45 μm or less, or 40 μm or less, and can be 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more.

[0068] The adhesive film 10 is obtained, for example, by applying a paste-like adhesive composition to a resin film such as a PET (polyethylene terephthalate) film, a fluororesin film, or the like, and drying. The paste-like adhesive composition is obtained, for example, by heating or dissolving a mixture containing the adhesive component 11, the first conductive particles 12, and the second conductive particles 13 in a solvent. As the solvent, a solvent having a boiling point of 50°C or higher and 150°C or lower at atmospheric pressure (for example, toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, butyl acetate, or the like) can be used.

[0069] The adhesive film 10 can be formed of a plurality of adhesive layers. In this case, the first conductive particles 12 and the second conductive particles 13 can be contained in at least one of the plurality of adhesive layers, can be contained in the same adhesive layers as each other, or can be contained in different adhesive layers.

[0070] The adhesive film 10 can be cured, for example, by being subjected to a heat treatment. The heating temperature can be, for example, 40°C or higher, and can be 250°C or lower. The heating time can be, for example, 0.1 seconds or more, and can be 10 hours or less.

[0071] The adhesive film 10 can be adhered to an adherend by being subjected to heating and pressurization. The heating temperature can be, for example, 50°C or higher, and can be 190°C or lower. The pressure can be, for example, 0.1 MPa or more, and can be 30 MPa or less, 10 MPa or less, 1 MPa or less, or 0.8 MPa or less. The heating and pressurization can be performed, for example, for 0.5 seconds or more, and can be performed for 120 seconds or less.

[0072] The adhesive film 10 according to the present embodiment can be used as an adhesive for adhering the same kind of adherends to each other, and can also be used as an adhesive for adhering different kinds of adherends (for example, adherends having different coefficients of thermal expansion) to each other. The adhesive film 10 is suitable for connecting electronic components to each other. By connecting electronic components to each other using the adhesive film 10, a connection structure can be manufactured.

[0073] Figure 2 is a schematic cross-sectional view illustrating one embodiment of a connection structure. As Figure 2As shown, the connection structure 20 includes: a first electronic component 23 having a first substrate 21 and a first electrode 22 formed on a main surface of the first substrate 21; a second electronic component 26 having a second substrate 24 and a second electrode 25 formed on a main surface of the second substrate 24; and a connection component 27 electrically connecting the first electrode 22 and the second electrode 25 to each other.

[0074] The first substrate 21 and the second substrate 24 can each be a substrate formed of glass, ceramic, polyimide, polycarbonate, polyester, polyethersulfone, or the like. The first electrode 22 and the second electrode 25 can each be an electrode formed of gold, silver, copper, tin, aluminum, ruthenium, rhodium, palladium, osmium, iridium, platinum, indium tin oxide (ITO), or the like.

[0075] The connection component 27 includes a cured product 28 of an adhesive component, first conductive particles 12 dispersed in the cured product 28, and second conductive particles 13 dispersed in the cured product 28. That is, the connection component 27 can also be referred to as a cured product of the above-described adhesive film.

[0076] In the connection structure according to the present embodiment, since the first conductive particles 12 and the second conductive particles 13 are used in combination, the electronic components 23 and 26 can be appropriately connected to each other. As shown in FIG. 1, it is considered that the second conductive particles 13 form a main conduction path for electrically connecting the first electrode 22 and the second electrode 25 to each other, and on the other hand, the first conductive particles 12 assist in electrically connecting the second conductive particles 13 and the respective electrodes 22 and 25, thereby achieving appropriate connection. Figure 2

[0077] Example

[0078] Hereinafter, the present application will be specifically described according to examples, but the present application is not limited to these examples at all.

[0079] < Synthesis of polyurethane acrylate (UA1) >

[0080] ​Poly(1,6-hexanediol carbonate) (product name: DURANOL T5652, manufactured by ASAHI KASEI CORPORATION, number average molecular weight 1000) 2500 parts by mass (2.50 mol) and isophorone diisocyanate (manufactured by Sigma Aldrich) 666 parts by mass (3.00 mol) were uniformly added dropwise over 3 hours into a reaction vessel equipped with a stirrer, a thermometer, a reflux cooling tube with a calcium chloride drying tube, and a nitrogen gas introduction tube. Subsequently, after sufficiently introducing nitrogen gas into the reaction vessel, the inside of the reaction vessel was heated to 70 to 75°C and allowed to react. Subsequently, after adding hydroquinone monomethyl ether (manufactured by Sigma Aldrich) 0.53 parts by mass (4.3 mmol) and dibutyltin dilaurate (manufactured by Sigma Aldrich) 5.53 parts by mass (8.8 mmol) to the reaction vessel, 2-hydroxyethyl acrylate (manufactured by Sigma Aldrich) 238 parts by mass (2.05 mol) was added, and allowed to react under an air atmosphere and at 70°C for 6 hours. Thus, a urethane acrylate (UA1) was obtained. The weight average molecular weight of the urethane acrylate (UA1) was 15000. Note that the weight average molecular weight was measured by a gel permeation chromatograph (GPC) using a calibration curve based on standard polystyrene under the following conditions.

[0081] (Measurement conditions)

[0082] Apparatus: GPC-8020 manufactured by TOSOH CORPORATION

[0083] Detector: RI-8020 manufactured by TOSOH CORPORATION

[0084] Column: Gelpack GLA160S + GLA150S manufactured by Resonac Techno Service Corporation

[0085] Sample concentration: 120 mg / 3 mL

[0086] Solvent: Tetrahydrofuran

[0087] Injection amount: 60 μL

[0088] Pressure: 2.94 x 106Pa (30 kgf / cm2)

[0089] Flow rate: 1.00 mL / min

[0090] <Production method of polyester urethane resin>

[0091] Into a stainless steel autoclave equipped with a stirrer, a thermometer, a capacitor, a vacuum generating device, a nitrogen introducing tube, and a heater, 48 parts by mass of isophthalic acid and 37 parts by mass of neopentyl glycol were charged, and further, 0.02 parts by mass of tetrabutoxy titanate as a catalyst was charged. Subsequently, the temperature was raised to 220°C under a stream of nitrogen, and direct stirring was performed for 8 hours. Thereafter, the pressure was reduced to the atmospheric pressure (760 mmHg), and the temperature was lowered to room temperature. Thus, white precipitates were deposited. The white precipitates were taken out, washed with water, and vacuum-dried, whereby a polyester polyol was obtained. The obtained polyester polyol was sufficiently dried, dissolved in MEK (methyl ethyl ketone), and charged into a four-necked flask equipped with a stirrer, a dropping funnel, a reflux cooler, and a nitrogen introducing tube. Further, 0.05 parts by mass of dibutyl tin dilaurate was charged as a catalyst, in an amount of 0.05 parts by mass per 100 parts by mass of the polyester polyol. Furthermore, 4,4'-diphenyl methane diisocyanate was dissolved in MEK in an amount of 50 parts by mass per 100 parts by mass of the polyester polyol, and charged using a dropping funnel, and stirring was performed at 80°C for 4 hours, whereby a polyester urethane resin was obtained.

[0092] (Preparation of Solution Al)

[0093] In the methyl ethyl ketone solution of the polyester urethane resin (content of polyester urethane resin: 47.2 parts by volume) synthesized as described above, 53.3 parts by volume of the urethane acrylate (UA1) synthesized as described above, 13.5 parts by volume of dimethylol tricyclodecane diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., product name: DCP-A), 6.0 parts by volume of EO-modified triallyl isocyanurate and EO-modified triallyl isocyanurate (manufactured by TOAGOSEI CO., LTD., product name: M-315), and 6.0 parts by volume of EO-modified dimethylaminoethyl acrylate phosphate (manufactured by Nippon Kayaku Co., Ltd., product name: PM-21) as radical polymerizable substances, 9.0 parts by volume of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (manufactured by NOF CORPORATION, product name: Perhexa (registered trademark) 250) as a radical polymerization initiator, and two kinds of silica particles (manufactured by Evonik Industries AG, product name: "R202" 20.0 parts by volume and manufactured by Evonik Industries AG, product name: "R805" 15.0 parts by volume) as a filler were mixed, whereby Solution Al was obtained. The total content of the binder components (hereinafter, also referred to as "binder components al") contained in Solution Al was 170 parts by volume.

[0094] (First conductive particles)

[0095] As the first conductive particles (Bl), dendritic silver-coated copper particles (manufactured by Mitsui Mining & Smelting Co., Ltd., product name: ACBY-2) were used.

[0096] (Second conductive particles)

[0097] On the surface of polystyrene particles as the core, a conductive layer containing gold was formed (thickness of the layer: 20 nm). The obtained particles were used as the second conductive particles (B2) (average particle diameter: 20 μm, specific gravity: 1.65).

[0098] Preparation of adhesive film

[0099] [Example 1]

[0100] The conductive particles Bl and the conductive particles B2 were dispersed in the solution Al in such a manner that the adhesive component al : the conductive particles Bl : the conductive particles B2 (volume parts) became 170 : 92.0 : 3.9, and thereby a mixed solution was obtained. The obtained mixed solution was applied to a fluororesin film having a thickness of 80 μm, and hot air drying was performed at 70°C for 10 minutes to remove the solvent, and thereby an adhesive film having a thickness of 25 μm formed on the fluororesin film (adhesive film attached with a fluororesin film) was obtained.

[0101] [Examples 2 to 17 and Comparative Examples 1 and 2]

[0102] The adhesive films relating to Comparative Examples 1 and 2 and Examples 2 to 17 were obtained in the same manner as in Example 1, except that the amounts (volume parts) of the conductive particles Bl and the conductive particles B2 with respect to the adhesive component al (170 volume parts) were changed in the manner described in Table 1.

[0103] Evaluation of flow rate

[0104] The flow rates of the adhesive films relating to Examples 1 to 17 and Comparative Examples 1 and 2 were measured by the following method.

[0105] First, a living tissue biopsy trepan (Trepan) BP-10F 1.0 mm (manufactured by KAI INDUSTRIES CO., LTD.) was used to punch out the adhesive film with the fluororesin film attached thereto relating to each of the examples and comparative examples produced as described above in the thickness direction, thereby obtaining a circular plate-shaped adhesive film with the fluororesin film attached thereto having a diameter of 1 mm. The adhesive film with the fluororesin film attached thereto was placed on a first cover glass (manufactured by Matsunami Glass Ind., Ltd., thickness 0.15 mm, length 18 mm, width 18 mm) in such a manner that the adhesive film side was in contact with the first cover glass, thereby obtaining a first laminate (first cover glass / adhesive film / fluororesin film). The first laminate was subjected to heat press bonding from the fluororesin film side using a heat press bonding device (manufactured by Ohashi Engineering Co., Ltd., LD-06) under conditions of a press bonding temperature of 60°C, a press bonding pressure of 1 MPa, and a press bonding time of 0.1 seconds. In addition, the press bonding temperature was the maximum temperature reached when press bonding was performed for 1 second, and the press bonding pressure was the pressure converted to the area of the adhesive film. The maximum temperature reached was adjusted by separately preparing the same first laminate as described above, sandwiching a thin temperature sensor (manufactured by RKC INSTRUMENT INC., ST-50) between the adhesive film and the first cover glass of the laminate, and previously measuring the maximum temperature reached of the adhesive film.

[0106] Next, the fluororesin film was peeled off from the first laminate after heat press bonding, and a second cover glass (manufactured by Matsunami Glass Ind., Ltd., thickness 0.15 mm, length 18 mm, width 18 mm) was placed on the exposed adhesive film, thereby obtaining a second laminate (first cover glass / adhesive film / second cover glass). Next, heat press bonding was performed from the second cover glass side using a heat press bonding device (manufactured by Ohashi Engineering Co., Ltd., BD-06) under conditions of a press bonding temperature of 170°C, a press bonding pressure of 80 MPa, and a press bonding time of 5 seconds, thereby obtaining a press-bonded body. In addition, the press bonding temperature was the maximum temperature reached of the adhesive film, and the press bonding pressure was the pressure converted to the area of the adhesive film. The maximum temperature reached was adjusted by separately preparing the same second laminate as described above, sandwiching a thin temperature sensor (manufactured by RKC INSTRUMENT INC., ST-50) between the adhesive film and the first cover glass of the second laminate, and previously measuring the maximum temperature reached of the adhesive film.

[0107] The crimped body was observed using an optical microscope (manufactured by Nikon Corporation, L300ND), and the area of the bonded portion of the adhesive film in the crimped body to the first cover glass (bonded area) S1 (unit: mm2) was found using a length measuring tool. 2 ). Using this bonded area S1, the flow rate was calculated based on the following equation. The results are shown in Table 1.

[0108] Flow rate [%] = {(bonded area S1 - 0.25π) / (0.25π)} x 100

[0109] <Reliability (resistance increase rate) evaluation>

[0110] As shown in Figure 3 (a) and (b), the adhesive film 31 with the fluororesin film attached was cut into 6 mm x 6 mm, the cut adhesive film 31 was arranged so as to contact the copper foil 32 in the substantially center of the 6 mm x 50 mm copper foil 32, and heat press bonding was performed from the fluororesin film side using a heat press bonding device (manufactured by Ohashi Engineering Co., Ltd., BD-07) under conditions of a press bonding temperature of 50°C, a press bonding pressure of 0.5 MPa, and a press bonding time of 2 seconds. Next, the fluororesin film on the adhesive film 31 was peeled off, as shown in Figure 3 (c) and (d), an aluminum foil 33 of 50 mm x 6 mm was prepared, and was overlapped on the laminate of the copper foil 32 and the adhesive film 31 in a manner so as to cover the adhesive film 31, and heat press bonding was performed from the aluminum foil 33 side using a heat press bonding device (manufactured by Ohashi Engineering Co., Ltd., BD-07) under conditions of a press bonding temperature of 150°C, a press bonding pressure of 0.5 MPa, and a press bonding time of 10 seconds, thereby obtaining a mounting body for evaluation.

[0111] As shown in Figure 4 , a current meter and a voltage meter were connected to the obtained mounting body, and the connection resistance (initial connection resistance) was measured by the 4-terminal method. Further, after a thermal cycle test in which the mounting body was repeatedly subjected to a thermal cycle of being held at -40°C for 30 minutes, being warmed up to 100°C over 10 minutes, being held at 100°C for 30 minutes, and being cooled down to -40°C over 10 minutes, 20 times, the connection resistance (post-test connection resistance) was measured in the same manner as described above using a TSA-43EL manufactured by ESPEC Corp. The resistance increase rate was calculated by the following equation. The results are shown in Table 1.

[0112] Reliability (resistance increase rate) [%] = {(post-test connection resistance - initial connection resistance) / initial connection resistance} x 100

[0113] <Peeling strength evaluation>

[0114] First, a glass substrate with ITO wiring was prepared (glass substrate size: 2.5 mm × 28 mm, glass substrate thickness: 300 μm, ITO wiring size: 2500 μm (2.5 mm) × 300 μm, ITO wiring thickness: 0.2 μm, number of ITO wirings: 28, spacing between ITO wirings: 300 μm). The adhesive films with fluororesin films prepared as described above for each of the Examples and Comparative Examples were cut into 2 mm × 23 mm pieces and placed on the glass substrate with the adhesive film side facing down. The long sides of the adhesive films were positioned perpendicular to the ITO wiring. The laminate was then thermally pressed using a thermocompression bonding apparatus (heating method: constant temperature type, manufactured by TAIYO KOKI CO., LTD.) at a temperature of 60°C, a pressure of 1 MPa, and a time of 1 second to produce a laminate. Figure 5 This is a schematic plan view showing a laminate during peel strength measurement in Examples. Figure 5 The laminate 40 shown comprises: a glass substrate 43 having ITO wiring (including a glass substrate 41 and a substrate having ITO wiring 42 provided on the glass substrate 41); and an adhesive film 10A arranged on the glass substrate 43 having ITO wiring. Next, the fluororesin film is peeled off from the adhesive film, and a polyimide tape cut into 1.8 mm × 35 mm is attached to the adhesive film to obtain a measurement sample. The glass substrate side of the measurement sample is placed on a hot plate set at 40°C, and the front end of the polyimide tape is placed on a tensile strength measuring device (Tensilon). The peel strength is measured by fixing the glass substrate horizontally and stretching the polyimide tape in the vertical direction at a peeling speed of 50 mm / min. The results are shown in Table 1.

[0115] [Table 1]

[0116]

[0117] Explanation of symbols

[0118] 10, 10A-adhesive film, 11-adhesive component, 12-first conductive particle, 13-second conductive particle, 20-connection structure, 21-first substrate, 22-first electrode, 23-first electronic component, 24-second substrate, 25-second electrode, 26-second electronic component, 27-connection component, 28-cured product of adhesive component, 31-adhesive film, 32-copper foil, 33-aluminum foil, 40-laminated body, 41-glass substrate, 42-ITO wiring, 43-glass substrate with ITO wiring.

Claims

1. An adhesive film comprising: an adhesive component; first conductive particles which are dendritic conductive particles; and second conductive particles which are conductive particles other than the first conductive particles and which are conductive particles having a non-conductive core and a conductive layer provided on the core, a flow rate of the adhesive film is 10 to 50%.

2. The adhesive film according to claim 1, wherein a volume ratio of a content of the first conductive particles to a content of the second conductive particles is 5 / 1 or more.

3. The adhesive film according to claim 1 or 2, wherein a total content of the first conductive particles and the second conductive particles is 20 parts by volume or more per 100 parts by volume of a content of the adhesive component.

4. The adhesive film according to claim 1 or 2, wherein a total content of the first conductive particles and the second conductive particles is 55 parts by volume or less per 100 parts by volume of a content of the adhesive component.

5. A connection structure comprising: a first electronic component having a first substrate and a first electrode formed on the first substrate; a second electronic component having a second substrate and a second electrode formed on the second substrate; and a connection component electrically connecting the first electrode and the second electrode to each other, the connection component includes a cured product of the adhesive film according to claim 1 or 2.

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