Anisotropic conductive adhesive, and connection structure

Abstract

Provided is an anisotropic conductive adhesive containing a resin having a heterocycle in the main chain, and a conductive material.

Description

Anisotropic conductive adhesive and connection structure

[0001] The present invention relates to an anisotropic conductive adhesive and a connection structure.

[0002] As electronic devices become more powerful, faster, and smaller, semiconductor circuits are becoming increasingly miniaturized, down to the nanometer order. In semiconductor packaging processes, a die, which is made of a semiconductor such as silicon and has transistors and wiring capable of input and output, is electrically connected to and sealed with a substrate that performs input and output. When connecting using conventional soldering techniques, the wiring pitch on the die side and the substrate side is a few tens of micrometers due to the limitations of solder bump characteristics.

[0003] To overcome the limitations of the wiring pitch on the die side, FOWLP (fan-out wafer-level packaging) has been developed. A typical example is known in which redistribution wiring (RDL) is performed on the electrode surface of the die by wafer processing, forming electrodes on the surface of the die with a wiring pitch that can be connected to a substrate. This makes it possible to finer the wiring inside the die, resulting in smaller die sizes and higher performance.

[0004] However, not only for electrodes extracted by FOWLP, but also for through-silicon vias (TSVs), when the connection between the die and the substrate is made by solder, the pitch of several tens of μm, which is the characteristic limit of the solder bump, is the industrial limit.

[0005] On the other hand, many alternative technologies to solder have been investigated, and one such alternative technology is a film-like connecting material (for example, anisotropic conductive film (ACF)) in which a thermosetting resin with a dispersed conductive material is applied to a release film.

[0006] This anisotropic conductive film is used as a connecting material that can be applied in low-temperature processes, for applications such as electrical connections in display peripheral devices. For example, a multilayer substrate has been reported in which semiconductor substrates are stacked using an anisotropic conductive film, making it possible to provide a multilayer substrate with excellent conductivity at low cost using a simple manufacturing process.The multilayer substrate has semiconductor substrates stacked on top of each other, each having a through electrode, and in which, when viewed from above, conductive particles are selectively present at positions where the through electrodes face each other, the facing through electrodes are connected by the conductive particles, and the semiconductor substrates on which the through electrodes are formed are bonded together with an insulating adhesive (see, for example, Patent Document 1).

[0007] Japanese Patent Application Laid-Open No. 2020-202409

[0008] However, compared to connecting materials used in display peripherals, connecting materials for semiconductor devices require high electrical connection reliability, such as resistance to temperature cycles under high-temperature operation and reflow, etc. The anisotropic conductive films of the prior art have a problem in that they have no track record as connecting materials for semiconductor devices such as FOWLP.

[0009] Furthermore, as mentioned above, conventional solder connections have limitations on how narrow the pitch can be, and as the wiring becomes finer, it becomes more difficult to apply underfill to prevent short circuits. In addition, the solder melting temperature is high, at 200°C or higher, which causes the board to warp when it returns to room temperature, resulting in problems in subsequent processes.

[0010] The present invention aims to solve the above-mentioned problems in the prior art and to achieve the following object: That is, the present invention aims to provide an anisotropic conductive adhesive that has high electrical connection reliability and excellent adhesion even after undergoing temperature cycles.

[0011] The means for solving the above problems are as follows: <1> An anisotropic conductive adhesive comprising a resin having a heterocyclic ring in its main chain and a conductive material. <2> The anisotropic conductive adhesive according to claim 1, wherein the resin having a heterocyclic ring in its main chain is represented by the following general formula (1) or the following general formula (2). In the general formula (1), X represents a group selected from the group consisting of the following: Ar １ , and Ar ２ represents an aryl group having one or more benzene rings, and n represents an integer. In the general formula (2), Y represents a group represented by the following formula: １ , and Ar ２ represents an aryl group having one or more benzene rings, and n represents an integer. <3> The anisotropic conductive adhesive according to <1>, wherein the resin having a heterocyclic ring in its main chain is represented by the following general formula (1) or the following general formula (2): In the general formula (1), X and Ar １ , and Ar ２ represents a group selected from the group consisting of the following, and n represents an integer: In the general formula (2), Y and Ar １ , and Ar ２ represents a group selected from the group consisting of the following, and n represents an integer: <4> The anisotropic conductive adhesive according to any one of <1> to <3>, wherein the content of the resin having a heterocyclic ring in its main chain is 20% by mass or more and 80% by mass or less with respect to the resin component. <5> The resistivity of the conductive material is 120×10 －８The anisotropic conductive adhesive according to any one of <1> to <4>, wherein the electrical resistance is [Ω·m] or less. <6> The anisotropic conductive adhesive according to any one of <1> to <5>, wherein the conductive material contains at least one selected from Au, Ag, Sn, Pb, Cu, Al, Ni, and Fe. <7> The anisotropic conductive adhesive according to any one of <1> to <6>, wherein the conductive material contains at least one selected from metal particles, alloy particles, and core-shell particles. <8> The anisotropic conductive adhesive according to any one of <1> to <7>, further containing a curing agent. <9> The anisotropic conductive adhesive according to any one of <1> to <8>, further containing another resin. <10> The anisotropic conductive adhesive according to any one of <1> to <9>, which is an anisotropic conductive adhesive film. <11> The anisotropic conductive adhesive according to any one of <1> to <10>, which is an anisotropic conductive adhesive film in which the conductive material is arranged in a single layer in the film-like resin component. <12> A connection structure comprising: a first circuit member; a second circuit member; and the anisotropic conductive adhesive according to any one of <1> to <11>, which anisotropically conductively connects the first circuit member and the second circuit member.

[0012] According to the present invention, it is possible to solve the above-mentioned problems in the prior art, achieve the above-mentioned objectives, and provide an anisotropic conductive adhesive that has high electrical connection reliability even after temperature cycling and excellent adhesion.

[0013] Fig. 1 is a schematic cross-sectional view of one example of an anisotropic conductive film according to the present embodiment. Fig. 2 is a schematic cross-sectional view of another example of an anisotropic conductive film according to the present embodiment. Fig. 3 is a cross-sectional view taken along the line B-B' in Fig. 2. Fig. 4 is a schematic cross-sectional view of another example of an anisotropic conductive film according to the present embodiment.

[0014] (Anisotropic conductive adhesive) The anisotropic conductive adhesive of the present invention comprises a resin component containing a resin having a heterocyclic ring in its main chain, a conductive material, and, if necessary, further comprises other components such as a curing agent. The anisotropic conductive adhesive can be suitably used as a paste-like anisotropic conductive adhesive or a film-like anisotropic conductive film that anisotropically conductively connects terminals of a first circuit member and terminals of a second circuit member.

[0015] <Conductive Material> The conductive material is not particularly limited as long as it has conductivity and can be appropriately selected depending on the purpose. Examples thereof include metal particles, alloy particles, and core-shell particles. These may be used alone or in combination of two or more. The resistivity of the conductive material is 120×10 －８ The conductive material preferably contains at least one selected from the group consisting of Au, Ag, Sn, Pb, Cu, Al, Ni, and Fe.

[0016] The metal particles are particles made of a single metal, and the metal is not particularly limited and can be appropriately selected depending on the purpose, for example, Au, Ag, Sn, Pb, Cu, Al, Ni, Fe, etc. The alloy particles are particles made of an alloy of multiple metals, and preferably contain two or more metals selected from Au, Ag, Sn, Pb, Cu, Al, Ni, and Fe. Among these, it is preferable to contain at least one of Ni, Ag, and Cu. These conductive materials may have Au or Pd (palladium) applied to their surfaces to prevent surface oxidation. Furthermore, particles with an insulating coating of an organic material applied to the surface may be used.

[0017] The core-shell particles are not particularly limited as long as they are particles in which a metal particle, alloy particle, or resin particle as a core is coated with a shell made of a metal or alloy different from the core, and can be appropriately selected depending on the purpose. For example, metal particles, alloy particles, or resin particles whose surfaces are coated with at least one metal or alloy selected from Au, Ag, Sn, Pb, Cu, Al, Ni, and Fe can be used. The shell can cover the entire surface of the core, or can cover only a portion of the surface of the core. Furthermore, particles with metal protrusions or an insulating coating made of an organic material can also be used. For connections requiring low resistance, resin particles whose surfaces are coated with Au or Ag are preferred. The method for coating the resin particles with a metal or alloy is not particularly limited and can be appropriately selected depending on the purpose, and examples include electroless plating and sputtering. The material of the resin particles is not particularly limited and can be appropriately selected depending on the purpose, and examples include styrene-divinylbenzene copolymer, benzoguanamine resin, cross-linked polystyrene resin, acrylic resin, and styrene-silica composite resin.

[0018] The conductive material may be any material as long as it is conductive during anisotropic conductive connection. For example, even metal particles having an insulating coating on their surfaces are considered to be conductive materials as long as they are deformed during anisotropic conductive connection, exposing the metal particles.

[0019] The average particle size of the conductive material is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 μm to 50 μm, more preferably 2 μm to 25 μm, and particularly preferably 2 μm to 10 μm. The average particle size is the average value of particle sizes measured for 10 randomly selected conductive materials. The particle size can be measured, for example, by observation using a scanning electron microscope.

[0020] The content of the conductive material is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 2 parts by mass to 200 parts by mass, more preferably 5 parts by mass to 100 parts by mass, per 100 parts by mass of the resin component.

[0021] <Resin Component> The resin component preferably contains a resin having a heterocyclic ring in its main chain, and further contains other resins such as a film-forming resin, a thermosetting resin, etc., as necessary. By containing a resin having the heterocyclic ring in its main chain, which has excellent heat resistance, the resin has the properties of being resistant to deformation and deterioration due to heat, and can maintain a state with little deformation or deterioration even after temperature cycling. This makes it possible to provide an anisotropic conductive adhesive with high electrical connection reliability that meets semiconductor connection specifications and excellent adhesion.

[0022] <<Resin Having a Heterocyclic Molecule in the Main Chain>> The resin having a heterocyclic molecule in the main chain is a resin having a heterocyclic molecule in the main chain that contains a heteroatom other than carbon and hydrogen in the ring. Examples of the heteroatom include nitrogen (N) and oxygen (O), and it is preferable that the resin contains N and O.

[0023] The resin having a heterocyclic ring in the main chain is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include polyimide, polybenzoxazole, polymaleimide, etc. These may be used alone or in combination of two or more.

[0024] The polyimide or polybenzoxazole is preferably a resin represented by the following general formula (1): In the general formula (1), X represents a group selected from the group consisting of the following: Ar １ , and Ar ２ represents an aryl group having one or more benzene rings, and n represents an integer.

[0025] The "aryl group having one or more benzene rings" is not particularly limited and can be appropriately selected depending on the purpose as long as it has one or more benzene rings, and may have a substituent, preferably having one, two or three benzene rings. When it has two or more benzene rings, it is preferable that the respective benzene rings are linked via a bond such as a covalent bond, an ether group (-O-), or a carbonyl group (-C(=O)-). Examples of the substituent include an alkyl group (monovalent group) such as a methyl group, a methylene group, an isopropylidene group (=C(CH３ ) ２ Among these, alkylene groups (divalent groups) such as Ar １ , and Ar ２ Preferably, each of represents a group selected from the group consisting of:

[0026] Among the resins represented by the general formula (1), resins represented by the following general formula (1-1), resins represented by the following general formula (1-2), and mixtures thereof are preferred.

[0027] The polymaleimide is preferably a resin represented by the following general formula (2): In the general formula (2), Y represents a group represented by the following formula: １ , and Ar ２ represents an aryl group having one or more benzene rings, and n represents an integer.

[0028] The "aryl group having one or more benzene rings" is not particularly limited and can be appropriately selected depending on the purpose as long as it has one or more benzene rings, and may have a substituent, preferably having one, two or three benzene rings. When it has two or more benzene rings, it is preferable that the respective benzene rings are linked via a bond such as a covalent bond, an ether group (-O-), or a carbonyl group (-C(=O)-). Examples of the substituent include an alkyl group (monovalent group) such as a methyl group, a methylene group, an isopropylidene group (=C(CH ３ ) ２ Among these, alkylene groups (divalent groups) such as Ar １ , and Ar ２ Preferably, each of represents a group selected from the group consisting of:

[0029] Among the resins represented by the general formula (2), the resin represented by the following general formula (2-1) is preferred.

[0030] The resin having a heterocyclic ring in its main chain may be suitably synthesized or may be a commercially available product. Examples thereof include soluble polyimide resin KPI-MX300F (manufactured by Kawamura Sangyo Co., Ltd.), polyimides described in JP-A-2005-272655 (e.g., polyimide in Example 1, etc.); polybenzoxazoles such as Sumiresin Excel CRC-8300 (manufactured by Sumitomo Bakelite Co., Ltd.); and polymaleimides such as polymaleimides obtained by polymerizing bismaleimide MIR-3000-70MT (manufactured by Nippon Kayaku Co., Ltd.).

[0031] The content of the resin having the heterocyclic ring in the main chain is not particularly limited and can be appropriately selected depending on the purpose. However, the content is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 80% by mass or less, relative to the total amount of the resin components.

[0032] <<Other Resins>> The resin component preferably includes, in addition to a resin having a heterocyclic ring in its main chain, other resins such as a film-forming resin and a thermosetting resin. The other resins and the curing agent may be bonded to the resin having a heterocyclic ring in its main chain, or may be mixed as additives. Here, when the resin having a heterocyclic ring in its main chain has a reactive functional group such as a cyclic ether group or a double bond group, it is advantageous in that a resin component and a cured product thereof that exhibit higher electrical connection reliability can be obtained through a bonding reaction or crosslinking reaction with the other resin.

[0033] -Film-forming resin- The film-forming resin is not particularly limited and can be appropriately selected depending on the purpose. Examples include phenoxy resin, acrylic resin, unsaturated polyester resin, saturated polyester resin, urethane resin, butadiene resin, polyamide resin, and polyolefin resin. The film-forming resin may be used alone or in combination of two or more. Among these, phenoxy resin is preferred from the viewpoints of thermal stability, film-forming ability, processability, and connection reliability, and acrylic resin is preferred from the viewpoints of flexibility and adhesiveness. Examples of the phenoxy resin include resins synthesized from bisphenol A and epichlorohydrin. The phenoxy resin may be an appropriately synthesized product or a commercially available product.

[0034] The content of the film-forming resin is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0% by mass or more and 80% by mass or less, more preferably 20% by mass or more and 70% by mass or less, and even more preferably 30% by mass or more and 70% by mass or less, relative to the resin component.

[0035] -Thermosetting Resin- The thermosetting resin (thermosetting component) is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include epoxy resins and radical polymerizable compounds.

[0036] --Epoxy Resin-- The epoxy resin is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include thermosetting epoxy resins such as bisphenol A epoxy resins, bisphenol F epoxy resins, novolac epoxy resins, and modified epoxy resins thereof. These may be used alone or in combination of two or more.

[0037] --Radically Polymerizable Compound-- The radically polymerizable compound is not particularly limited and can be appropriately selected depending on the purpose. Examples include methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, phosphate group-containing acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane triacrylate, dimethyloltricyclodecane diacrylate, tetramethylene glycol tetraacrylate, 2-hydroxy-1,3-diacryloxypropane, 2,2-bis[4-(acryloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloxyethoxy)phenyl]propane, dicyclopentenyl acrylate, tricyclodecanyl acrylate, tris(acryloxyethyl)isocyanurate, urethane acrylate, and epoxy acrylate. The acrylates can also be used as methacrylates. These compounds can be used alone or in combination of two or more.

[0038] The content of the thermosetting resin is not particularly limited and can be appropriately selected depending on the purpose. However, the content of the thermosetting resin is preferably 0% by mass or more and 80% by mass or less, more preferably 20% by mass or more and 70% by mass or less, and even more preferably 30% by mass or more and 70% by mass or less, relative to the resin component.

[0039] <Other Components> The other components are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a curing agent and a silane coupling agent.

[0040] <<Curing Agent>> The curing agent is not particularly limited as long as it has the effect of curing the thermosetting resin by heat, and can be appropriately selected depending on the purpose. Examples of the curing agent include cationic curing agents and radical curing agents.

[0041] -Cationic Curing Agent- The cationic curing agent is not particularly limited and can be appropriately selected depending on the purpose. Examples include sulfonium salts and onium salts. Among these, aromatic sulfonium salts are preferred. The cationic curing agent is preferably used in combination with an epoxy resin as the thermosetting resin.

[0042] -Radical Curing Agent- The radical curing agent is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include organic peroxides, etc. The radical curing agent is preferably used in combination with a radically polymerizable compound as the thermosetting resin.

[0043] The content of the curing agent is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 part by mass or more and 10 parts by mass or less, and more preferably 3 parts by mass or more and 7 parts by mass or less, relative to 100 parts by mass of the resin component.

[0044] <<Silane Coupling Agent>> The silane coupling agent is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include epoxy-based silane coupling agents, acrylic-based silane coupling agents, thiol-based silane coupling agents, amine-based silane coupling agents, etc. The content of the silane coupling agent is not particularly limited and can be appropriately selected depending on the purpose.

[0045] [Anisotropic conductive adhesive film] The anisotropic conductive adhesive can be suitably used as an embodiment of an anisotropic conductive adhesive film. The anisotropic conductive adhesive film may be a conductive material dispersion type film in which the conductive material is dispersed in the film-like resin component, or a conductive material arrangement type film in which the conductive material is arranged in a single layer in the film-like resin component. Either type can be suitably used to anisotropically conductively connect terminals of a first circuit member and terminals of a second circuit member. The anisotropic conductive adhesive film preferably further has a peelable substrate.

[0046] The average thickness of the anisotropic conductive adhesive film is not particularly limited and can be appropriately selected depending on the purpose, but the average thickness of the anisotropic conductive adhesive is preferably 2 μm to 50 μm, more preferably 3 μm to 40 μm, and particularly preferably 3 μm to 25 μm. Here, the average thickness is the arithmetic mean value when measurements are taken at 10 arbitrary locations.

[0047] In the conductive material array type anisotropic conductive adhesive film, the method for arranging the conductive materials is not particularly limited and can be appropriately selected depending on the purpose, and examples include the method of utilizing a biaxial stretching operation on an unstretched polypropylene film described in Example 1 of Japanese Patent No. 4789738; the method of using a mold described in JP-A-2010-33793; etc. The degree of arrangement is preferably such that the conductive materials are arranged two-dimensionally in a single layer at a distance of about 1 μm to 100 μm from each other, taking into consideration the size of the connection target, conduction reliability, insulation properties, particle capture efficiency, etc.

[0048] <Releasable Substrate> The releasable substrate can be any film that can be peeled off from the anisotropic conductive film when temporarily attached. Examples of the releasable substrate include silicone-based films, fluorine-based films, PET (polyethylene terephthalate) treated with a release agent, PEN (polyethylene naphthalate) treated with a release agent, and glassine paper treated with a release agent. Examples of the release agent include silicone-based release agents and fluorine-based release agents. Among these, substrates that have been treated with a silicone-based release agent are preferred.

[0049] The release substrate is disposed in contact with the anisotropic conductive film, and the surface of the release substrate that comes into contact with the anisotropic conductive film is preferably release-treated, but the surface opposite to the side that comes into contact with the anisotropic conductive film does not have to be release-treated.

[0050] The average thickness of the release substrate is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 12 μm to 75 μm.

[0051] An example of an anisotropic conductive film according to the present embodiment will now be described with reference to the drawings. Fig. 1 is a schematic cross-sectional view of an example of an anisotropic conductive film according to the present embodiment. The anisotropic conductive film 10 in Fig. 1 has a film-like anisotropic conductive adhesive 2 on a release substrate 1. The anisotropic conductive adhesive 2 is a conductive material-dispersed film having a resin component 3 and a conductive material 4 dispersed in the resin component 3.

[0052] Fig. 2 is a schematic cross-sectional view of another example of the anisotropic conductive film of this embodiment, and is a cross-sectional view taken along line A-A' in Fig. 3. Fig. 3 is a cross-sectional view taken along line B-B' in Fig. 2. The anisotropic conductive film 20 in Figs. 2 and 3 has a film-like anisotropic conductive adhesive 2 on a peelable substrate 1. The anisotropic conductive adhesive 2 is a conductive material arrangement type film having a resin component 3 and a conductive material 4 arranged in a single layer within the resin component 3. The size of the conductive material 4 is approximately equal to the average thickness of the anisotropic conductive adhesive 2.

[0053] Fig. 4 is a schematic cross-sectional view of another example of the anisotropic conductive film of this embodiment. The anisotropic conductive film 30 of Fig. 4 is a modified example of the anisotropic conductive film 20 of Figs. 2 and 3, and is a conductive material arrangement type film in which, instead of the spherical conductive materials 4, conductive materials 4 having a substantially square prism shape are arranged in a single layer in the resin component 3. The arrangement pattern of the conductive materials 4 is, for example, a 60° staggered pattern.

[0054] The shape of the conductive material 4 is not particularly limited and can be selected appropriately depending on the purpose, but is preferably a sphere, an oval sphere, a cylinder, an elliptical cylinder, a substantially square prism, a substantially equilateral triangle, a substantially hexagon, or other columnar shape. The arrangement pattern of the conductive material 4 is not particularly limited and can be selected appropriately depending on the purpose, but is preferably a regular arrangement in a single layer without contact with each other. Examples include 60° staggered, 45° staggered, square parallelepiped, regular hexagonal 60° staggered, equilateral triangle arrangement, and alternating square patterns. Here, "60° staggered" refers to an arrangement pattern in which the centers of the conductive materials are arranged so that, when viewed in a plan view, they are each vertex of a plurality of equilateral triangles that share their sides. "45° staggered" refers to an arrangement pattern in which the centers of the conductive materials are arranged so that, when viewed in a plan view, they are each vertex of a plurality of right-angled isosceles triangles that share their sides.

[0055] There are no particular restrictions on the size of the conductive material 4 and it can be selected appropriately depending on the purpose, but it is preferable that the size be between 1 / 5 and 1 / 2 of the average thickness of the anisotropic conductive adhesive 2, since when the anisotropic conductive film 20 or 30 is placed between the terminal of the first circuit member and the terminal of the second circuit member, each conductive material 4 is exposed on each surface of the anisotropic conductive adhesive 2, allowing for efficient anisotropic conductive connection.

[0056] In Figures 2 and 4, the size of the conductive material 4 is approximately the same as the average thickness of the anisotropic conductive adhesive 2, but if the size of the conductive material 4 is smaller than the average thickness of the anisotropic conductive adhesive 2, it may be arranged facing the side of the anisotropic conductive adhesive 2 opposite to the peelable substrate 1 side, or it may be arranged inside the anisotropic conductive adhesive 2, either of which can be selected appropriately depending on the desired form.

[0057] (Connection structure) The connection structure of the present invention comprises a first circuit member, a second circuit member, and the anisotropic conductive adhesive or anisotropic conductive film of the present embodiment described above, which anisotropically conductively connects the first circuit member and the second circuit member, and may further comprise other members as necessary.

[0058] <First Circuit Member, Second Circuit Member> The first circuit member and the second circuit member are not particularly limited and can be appropriately selected depending on the purpose, as long as they are circuit members that have terminals and are the target of anisotropic conductive connection using the anisotropic conductive adhesive or anisotropic conductive film. Examples include a glass substrate having terminals, a plastic substrate having terminals, an IC (Integrated Circuit), a TAB (Tape Automated Bonding) tape, Flex-on-Glass (FOG), Chip-on-Glass (COG), Chip-on-Flex (COF), Flex-on-Board (FOB), Flex-on-Flex (FOF), and a liquid crystal panel.

[0059] Examples of the glass substrate having terminals include an ITO (indium tin oxide) glass substrate, an IZO (indium zinc oxide) glass substrate, and other glass pattern substrates. Among these, an ITO glass substrate and an IZO glass substrate are preferred. The material and structure of the plastic substrate having terminals are not particularly limited and can be appropriately selected depending on the purpose. Examples include a rigid substrate having terminals and a flexible substrate having terminals. Examples of the IC include an IC chip for controlling a liquid crystal screen in a flat panel display (FPD).

[0060] The shapes and sizes of the first circuit member and the second circuit member are not particularly limited and can be appropriately selected depending on the purpose. The first circuit member and the second circuit member may be the same circuit member or different circuit members.

[0061] [Method for manufacturing connection structure, connection method] The method for manufacturing the connection structure of this embodiment and the connection method for connecting using the anisotropic conductive adhesive or anisotropic conductive film of this embodiment are not particularly limited and can be selected appropriately depending on the purpose, and can be suitably implemented, for example, by a method that includes at least a first arrangement step, a second arrangement step, and a heat and pressure step, and further includes other steps such as a temporary attachment step as necessary. The connection method is a method for anisotropically conductively connecting terminals of a first circuit member and terminals of a second circuit member.

[0062] The first circuit member and the second circuit member are not particularly limited and can be selected appropriately depending on the purpose, and examples thereof include the first circuit member and the second circuit member exemplified in the description of the anisotropic conductive film of this embodiment.

[0063] <First Placement Step> The first placement step is not particularly limited as long as it is a step of placing the anisotropic conductive film of the present embodiment on the terminals of the first circuit member so that it contacts the terminals of the first circuit member, and can be selected appropriately depending on the purpose.

[0064] <Second Placement Process> The second placement process is not particularly limited as long as it is a process of placing the second circuit member on the anisotropic conductive film so that the terminals of the second circuit member contact the anisotropic conductive film, and can be selected appropriately depending on the purpose.

[0065] <Heat Pressing Step> The heat pressing step is not particularly limited as long as it is a step of heating and pressing the second circuit member with a heat pressing member, and can be appropriately selected depending on the purpose.

[0066] The heating and pressing member may, for example, be a pressing member having a heating mechanism. The pressing member having a heating mechanism may, for example, be a heat tool. The heating temperature is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 150°C to 200°C. The pressing pressure is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.1 MPa to 50 MPa. The heating and pressing time is not particularly limited and can be appropriately selected depending on the purpose, but is, for example, 0.5 seconds to 120 seconds.

[0067] <Temporary attachment process> The temporary attachment process is not particularly limited as long as it is a process of heating and pressing the anisotropic conductive film at a temperature lower than the heating temperature in the heating and pressing process after the first placement process, and attaching the anisotropic conductive film to the first circuit member, and can be selected appropriately depending on the purpose.

[0068] The heating and pressing can be performed using, for example, a heating and pressing member. Examples of the heating and pressing member include a pressing member having a heating mechanism. Examples of the pressing member having a heating mechanism include a heat tool.

[0069] When the anisotropic conductive film has the releasable substrate on the conductive material side, it is preferable that the temporary attachment step is performed in a state where the anisotropic conductive film has the releasable substrate, and that the releasable substrate is peeled off from the anisotropic conductive film after the temporary attachment step.

[0070] The heating temperature in the temporary attachment step is not particularly limited as long as it is lower than the heating temperature in the heating and pressing step, and can be appropriately selected depending on the purpose, but is preferably 50°C to 110°C. The heating temperature is preferably a temperature at which the anisotropic conductive film does not harden. The pressing pressure in the temporary attachment step is not particularly limited, and can be appropriately selected depending on the purpose, but is preferably 0.1 MPa to 10 MPa. The heating and pressing time in the temporary attachment step is not particularly limited, and can be appropriately selected depending on the purpose, and can be, for example, 0.5 seconds to 10 seconds.

[0071] Examples of the present invention will be described below, but the present invention is not limited to these examples in any way.

[0072] Example 1 Preparation of Anisotropic Conductive Adhesive A polyimide solution was prepared by dissolving a polyimide (the soluble polyimide described in Example 1 of JP-A No. 2005-272655, a proprietary product) which is a mixture of a resin represented by the following general formula (1-1) and a resin represented by the following general formula (1-2) in N-methylpyrrolidone (NMP) to a concentration of 15% by mass. The polyimide solution and an epoxy resin (EXA-850CRP, manufactured by DIC Corporation) were mixed at a solids ratio of 50:50 to prepare a resin component of 100 parts by mass. Five parts by mass of Curesol (2E4MZ, manufactured by Shikoku Chemicals Corporation) were added as a curing agent and further mixed. A planetary mixer (Thinky Mixer ARE-312) was used for mixing. To the resulting mixture, Ni particles (diameter 3 μm, NIEJB-003-S, manufactured by Sekisui Chemical Co., Ltd.) as a conductive material were added in an amount of 50 parts by mass per 100 parts by mass of the resin component, and the mixture was further mixed to disperse the conductive material, thereby obtaining the anisotropic conductive adhesive of Example 1.

[0073]

[0074] <Preparation of Anisotropic Conductive Film> The obtained anisotropic conductive adhesive was applied to a PET (polyethylene terephthalate) film (UH-4, average film thickness 50 μm, manufactured by Teijin Limited) using a bar coater, and then heated in a drying oven at 80°C for 10 minutes to remove the solvent, thereby obtaining an anisotropic conductive film of Example 1 having an average thickness of 15 μm.

[0075] (Example 2) The anisotropic conductive adhesive and anisotropic conductive film of Example 2 were obtained in the same manner as Example 1, except that the solid content ratio (mass ratio) of polyimide to epoxy resin in Example 1 was changed from 50:50 to 20:80.

[0076] (Example 3) The anisotropic conductive adhesive and anisotropic conductive film of Example 2 were obtained in the same manner as Example 1, except that the solid content ratio (mass ratio) of polyimide to epoxy resin in Example 1 was changed from 50:50 to 80:20.

[0077] (Example 4) An anisotropic conductive adhesive and anisotropic conductive film of Example 4 were obtained in the same manner as in Example 1, except that the epoxy resin in Example 1 was changed to an acrylic resin (product name: ACMO, manufactured by KJ Chemicals Co., Ltd.).

[0078] (Example 5) An anisotropic conductive adhesive and an anisotropic conductive film of Example 5 were obtained in the same manner as in Example 1, except that the polyimide in Example 1 was changed to polybenzoxazole (Sumiresin Excel CRC-8300, manufactured by Sumitomo Bakelite Co., Ltd.).

[0079] Example 6 The anisotropic conductive adhesive and anisotropic conductive film of Example 5 were obtained in the same manner as in Example 1, except that the polyimide in Example 1 was changed to bismaleimide (MIR-3000-70MT, manufactured by Nippon Kayaku Co., Ltd.).

[0080] Example 7 An anisotropic conductive film intermediate having an average thickness of 4 μm was obtained in the same manner as in Example 1, except that no conductive material was added in Example 1. Next, Ni particles (diameter 3 μm, NIEJB-003-S, manufactured by Sekisui Chemical Co., Ltd.) were arranged on the obtained anisotropic conductive film intermediate in accordance with the procedure described in JP 2010-33793 A, thereby producing the anisotropic conductive film of Example 7.

[0081] (Comparative Example 1) An anisotropic conductive adhesive and anisotropic conductive film of Comparative Example 1 were obtained in the same manner as in Example 1, except that the solid content ratio (mass ratio) of polyimide to epoxy resin in Example 1 was changed from 50:50 to 0:100.

[0082] <Evaluation> Using each of the obtained anisotropic conductive films, "initial conduction characteristics," "electrical connection reliability after temperature cycling," and "adhesion" were evaluated according to the following procedures. The results are shown in Table 1.

[0083] <Initial Conduction Characteristics> <<Preparation of Pressure-Bonded Laminate>> A flexible printed circuit board (FPC) having Cu / Ni / Au plated wiring (wiring width: 25 μm, and wiring distance: 25 μm, 50 μm pitch) was used as the evaluation substrate. An anisotropic conductive film was sandwiched between two evaluation substrates, and thermocompression bonding was performed at 2 MPa and 180°C for 20 seconds using a constant heating head pressure bonding bonder (BD-01 tabletop thermocompression bonding device, manufactured by Ohashi Manufacturing Co., Ltd.) to prepare a pressure-bonded laminate for evaluation.

[0084] <<Evaluation of Initial Conduction Characteristics>> A current was passed through the obtained pressure-bonded laminate to measure the initial conduction resistance. Specifically, the resistance was measured by measuring the voltage when a current of 1 mA was passed using a four-terminal method using a digital multimeter (product number: Digital Multimeter 7555, manufactured by Yokogawa Electric Corporation). The resistance was measured for 30 channels, and the maximum resistance value was taken as the measured value and evaluated according to the following evaluation criteria.

[0085] [Evaluation criteria] ○: Conduction resistance is 1Ω or less. △: Conduction resistance is more than 1Ω and 2Ω or less. ×: Conduction resistance is more than 2Ω. The rating "○" indicates that the conduction resistance is sufficiently low, the rating "△" indicates that it is at a level that is practically usable, and the rating "×" indicates that it is not practically usable.

[0086] <Electrical connection reliability after temperature cycles> <<Thermal cycle test>> The obtained pressure-bonded laminate was placed in a highly accelerated life tester (EHS-212MD, manufactured by Espec Corporation) and subjected to a thermal cycle test (1 cycle: −55° C., 30 minutes and 125° C., 30 minutes, 500 cycles), to obtain a pressure-bonded laminate subjected to temperature cycles.

[0087] <<Electrical Connection Reliability>> Conduction resistance was measured and evaluated in accordance with the above-mentioned <<Evaluation of Initial Conduction Characteristics>> and the evaluation criteria, except that a pressure-bonded laminate subjected to a temperature cycle was used.

[0088] <Adhesion> The pressure-bonded laminate subjected to temperature cycling was observed using an ultrasonic imaging device (SAT, FS300IIIHR, manufactured by Hitachi Power Solutions Co., Ltd.) to inspect the adhesion to the substrate and the presence or absence of voids. A 50 MHz, 7 mm probe was used on the copper plate side, and a 25 MHz probe was used on the silicon plate side. [Evaluation criteria] ◯: Lifting, peeling, or voids from the substrate were less than 0.1% of the observed field of view, within the practical range. ×: Lifting, peeling, or voids from the substrate were 0.1% or more of the observed field of view, outside the practical range.

[0089]

[0090] This international application claims priority based on Japanese Patent Application No. 2024-008455 filed on January 24, 2024, and Japanese Patent Application No. 2025-003316 filed on January 9, 2025. The entire contents of Japanese Patent Application No. 2024-008455 and Japanese Patent Application No. 2025-003316 are incorporated by reference into this international application.

[0091] REFERENCE SIGNS LIST 1 Peelable substrate 2 Anisotropic conductive adhesive 3 Resin component 4 Conductive material 10 Anisotropic conductive film (dispersion type) 20, 30 Anisotropic conductive film (arrangement type)

Claims

1. An anisotropic conductive adhesive, comprising: a resin component containing a resin having a heterocyclic ring in the main chain; and a conductive material.

2. The anisotropic conductive adhesive according to claim 1, wherein the resin having the heterocyclic ring structure in the main chain is represented by the following general formula (1) or the following general formula (2). In the general formula (1), X represents a group selected from the group consisting of the following, and Ar １ , and Ar ２ each represent an aryl group having one or more benzene rings, and n represents an integer. In the general formula (2), Y represents a group consisting of the following, and Ar １ , and Ar ２ each represent an aryl group having one or more benzene rings, and n represents an integer.

3. The anisotropic conductive adhesive according to claim 1, wherein the resin having the heterocyclic ring structure in the main chain is represented by the following general formula (1) or the following general formula (2). In the general formula (1), X, Ar １ , and Ar ２ each represent a group selected from the group consisting of the following, and n represents an integer. In the general formula (2), Y, Ar １ , and Ar ２ each represent a group selected from the group consisting of the following, and n represents an integer.

4. The anisotropic conductive adhesive according to any one of claims 1 to 3, wherein the content of the resin having a heterocyclic ring in the main chain is 20% by mass or more and 80% by mass or less based on the total amount of the resin component.

5. The resistivity of the conductive material is 120 × 10 －８ [Ω·m] or less, and the anisotropic conductive adhesive according to any one of claims 1 to 4.

6. The anisotropic conductive adhesive according to any one of claims 1 to 5, wherein the conductive material contains at least one selected from Au, Ag, Sn, Pb, Cu, Al, Ni, and Fe.

7. The anisotropic conductive adhesive according to any one of claims 1 to 6, wherein the conductive material contains at least one selected from metal particles, alloy particles, and core-shell particles.

8. The anisotropic conductive adhesive according to any one of claims 1 to 7, further comprising a curing agent.

9. The anisotropic conductive adhesive according to any one of claims 1 to 8, further comprising another resin.

10. The anisotropic conductive adhesive according to any one of claims 1 to 9, which is an anisotropic conductive adhesive film.

11. The anisotropic conductive adhesive according to any one of claims 1 to 10, which is an anisotropic conductive adhesive film in which the conductive material is arranged in a single layer in the film-shaped resin component.

12. A connection structure, comprising: a first circuit member; a second circuit member; and the anisotropic conductive adhesive according to any one of claims 1 to 11, which anisotropically conducts and connects the first circuit member and the second circuit member.

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