Anisotropic conductive adhesive, and connection structure

Abstract

To provide an anisotropic conductive adhesive exhibiting superior adhesion while maintaining high reliability in electrical connection after temperature cycling.SOLUTION: Provided is an anisotropic conductive adhesive containing a resin having a heterocycle in the main chain, and a conductive material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] As electronic devices become more powerful, faster, and smaller, semiconductor circuits are becoming increasingly miniaturized down to the nanometer level. In the semiconductor packaging process, 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 technology, the wiring pitch on the die side and the substrate side is a few tens of micrometers due to the limitations of the 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 the formation of electrodes on the surface of the die with a wiring pitch that can be connected to the substrate by performing redistribution wiring (RDL) on the electrode surface of the die during wafer processing. This makes it possible to fine-tune 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 industrial limit is a pitch of several tens of microns, which is the characteristic limit of the solder bumps.

[0005] On the other hand, many alternative technologies to solder are being investigated, and one such alternative is a film-like connecting material (for example, anisotropic conductive film (ACF)), which is made by applying a thermosetting resin with conductive material dispersed in it 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 is a multilayer substrate in which semiconductor substrates having through electrodes are stacked, and in which, when viewed in plan, 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). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-202409 Summary of the Invention [Problem to be solved by the invention]

[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. Conventional anisotropic conductive films 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 over 200°C, 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. [Means for solving the problem]

[0011] The means for solving the above problems are as follows: <1> The anisotropic conductive adhesive is characterized by comprising a resin having a heterocyclic ring in its main chain and a conductive material. <2> 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). [ka] In the general formula (1), X represents a group selected from the group consisting of the following: Ar1 and Ar2 each represent an aryl group having one or more benzene rings; and n represents an integer. [ka] [ka] In the general formula (2), Y represents a group shown below, Ar1 and Ar2 each represent an aryl group having one or more benzene rings, and n represents an integer. [ka] <3> The resin having a heterocyclic ring in its main chain is represented by the following general formula (1) or the following general formula (2): <1> The anisotropic conductive adhesive is described in [ka] In the general formula (1), X, Ar1, and Ar2 each represent a group selected from the group consisting of the following, and n represents an integer. [ka] [ka] In the general formula (2), Y, Ar1, and Ar2 each represent a group selected from the group consisting of the following, and n represents an integer. [ka] <4> The content of the resin having the heterocyclic ring in the main chain is 20% by mass or more and 80% by mass or less with respect to the resin component. <1> from <3> The anisotropic conductive adhesive according to any one of the above items. <5> The resistivity of the conductive material is 120×10 -8 [Ω·m] or less <1> from <4> The anisotropic conductive adhesive according to any one of the above items. <6> The conductive material includes at least one selected from the group consisting of Au, Ag, Sn, Pb, Cu, Al, Ni, and Fe. <1> from <5> The anisotropic conductive adhesive according to any one of the above items. <7> The conductive material includes at least one selected from metal particles, alloy particles, and core-shell particles. <1> from <6> The anisotropic conductive adhesive according to any one of the above items. <8> The composition further comprising a curing agent. <1> from <7> The anisotropic conductive adhesive according to any one of the above items. <9> The above-mentioned resin further containing other resins <1> from <8> The anisotropic conductive adhesive according to any one of the above items. <10> The anisotropic conductive adhesive film <1> from <9> The anisotropic conductive adhesive according to any one of the above items. <11> The anisotropic conductive adhesive film is an anisotropic conductive adhesive film in which the conductive material is arranged in a single layer in the film-like resin component. <1> from <10> The anisotropic conductive adhesive according to any one of the above items. <12> a first circuit member; a second circuit member; The first circuit member and the second circuit member are anisotropically conductively connected. <1> from <11> and the anisotropic conductive adhesive according to any one of the above. [Effects of the Invention]

[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. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic cross-sectional view of an example of an anisotropic conductive film according to the present embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of another example of the anisotropic conductive film of the present embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along line BB' of FIG. [Figure 4] FIG. 4 is a schematic cross-sectional view of another example of the anisotropic conductive film of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] (anisotropic conductive adhesive) The anisotropic conductive adhesive of the present invention contains a resin component containing a resin having a heterocyclic ring in the main chain, a conductive material, and, if necessary, 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 provides an anisotropic conductive connection between the terminals of a first circuit member and the terminals of a second circuit member.

[0015] <Conductive materials> The conductive material is not particularly limited as long as it has conductivity and can be appropriately selected depending on the purpose, and examples thereof include metal particles, alloy particles, core-shell particles, etc. These may be used alone or in combination of two or more. The resistivity of the conductive material is 120×10 -8 It is preferable that the resistance be [Ω·m] or less. 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, and examples thereof include Au, Ag, Sn, Pb, Cu, Al, Ni, and Fe. The alloy particles are particles made of an alloy of a plurality of 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 use at least one of Ni, Ag, and Cu. These conductive materials may have their surfaces coated with Au or Pd (palladium) to prevent surface oxidation. Furthermore, the surface may be coated with an insulating film made of an organic material.

[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, there are particles in which the surface of a metal particle, alloy particle, or resin particle is coated with at least one metal or alloy selected from Au, Ag, Sn, Pb, Cu, Al, Ni, and Fe. The shell may cover the entire surface of the core, or may cover only a portion of the surface of the core. Furthermore, the core may have a surface coated with metal protrusions or an insulating coating made of an organic material. For low-resistance connections, 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. Examples thereof include electroless plating and sputtering. The material of the resin particles is not particularly limited and can be appropriately selected depending on the purpose. 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 selected appropriately depending on the purpose, but is preferably 2 to 200 parts by mass, more preferably 5 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 the main chain, and further contains other resins such as a film-forming resin and a thermosetting resin, as required. Because the resin component contains a resin having the heterocyclic ring, which has excellent heat resistance, in its main chain, 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 the specifications for semiconductor connection and excellent adhesion.

[0022] <<Resin with heterocyclic rings in the main chain>> The resin having a heterocyclic ring in its main chain is a resin having a heterocyclic ring containing a heteroatom other than carbon and hydrogen in the ring in its main chain, and 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. Examples thereof include polyimide, polybenzoxazole, and polymaleimide. 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). [ka] In the general formula (1), X represents a group selected from the group consisting of the following: Ar1 and Ar2 each represent an aryl group having one or more benzene rings; and n represents an integer. [ka]

[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, and preferably has one, two, or three benzene rings. When the compound has two or more benzene rings, the benzene rings are preferably linked via a bond such as a covalent bond, an ether group (—O—), or a carbonyl group (—C(═O)—). Examples of the substituent include alkyl groups (monovalent groups) such as a methyl group, and alkylene groups (divalent groups) such as a methylene group and an isopropylidene group (=C(CH3)2). Among these, it is preferable that Ar1 and Ar2 each represent a group selected from the group consisting of the following: [ka]

[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. [ka]

[0027] The polymaleimide preferably includes a resin represented by the following general formula (2). [ka] In the general formula (2), Y represents a group shown below, Ar1 and Ar2 each represent an aryl group having one or more benzene rings, and n represents an integer. [ka]

[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, and preferably has one, two, or three benzene rings. When the compound has two or more benzene rings, the benzene rings are preferably linked via a bond such as a covalent bond, an ether group (—O—), or a carbonyl group (—C(═O)—). Examples of the substituent include alkyl groups (monovalent groups) such as a methyl group, and alkylene groups (divalent groups) such as a methylene group and an isopropylidene group (=C(CH3)2). Among these, it is preferable that Ar1 and Ar2 each represent a group selected from the group consisting of the following: [ka]

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

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

[0031] The content of the resin having the heterocyclic ring in its main chain is not particularly limited and can be appropriately selected depending on the purpose, but 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 contains, in addition to a resin having a heterocyclic ring in the main chain, other resins such as a film-forming resin and a thermosetting resin. The other resin and the curing agent may be bonded to the resin having the heterocyclic ring in the main chain, or may be mixed as additives. Here, when the resin having the 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 other resins.

[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, polyolefin resin, etc. 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. The phenoxy resin may be, for example, a resin synthesized from bisphenol A and epichlorohydrin. The phenoxy resin may be a suitably 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 resin, bisphenol F epoxy resin, novolac epoxy resin, and modified epoxy resins thereof, etc. These may be used alone or in combination of two or more.

[0037] --Radical polymerizable compound-- The radical 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 converted to methacrylates. These compounds can be used alone or in combination.

[0038] The content of the thermosetting 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.

[0039] <Other ingredients> 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, and examples thereof include sulfonium salts, onium salts, etc. 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. The radical curing agent is preferably used in combination with a radical polymerizable compound as the thermosetting resin.

[0043] The content of the curing agent is not particularly limited and can be selected appropriately 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, per 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. Examples thereof include epoxy-based silane coupling agents, acrylic-based silane coupling agents, thiol-based silane coupling agents, and amine-based silane coupling agents. 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, and either type can be suitably used to establish an anisotropic conductive connection between a terminal of a first circuit member and a terminal of a second circuit member. The anisotropic conductive adhesive film preferably further comprises a releasable substrate.

[0046] The average thickness of the anisotropic conductive adhesive film is not particularly limited and can be selected appropriately 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 random locations.

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

[0048] <Releasable substrate> The releasable substrate can be any film that can be peeled off from the anisotropic conductive film when temporarily attached without any particular limitation. Examples of the release substrate include a silicone-based film, a fluorine-based film, PET (polyethylene terephthalate) that has been treated with a release agent for release, PEN (polyethylene naphthalate) that has been treated with a release agent for release, and glassine paper that has been treated with a release agent for release. Examples of the release agent include silicone-based release agents and fluorine-based release agents. Among these, a substrate that has been subjected to release treatment with a silicone-based release agent is preferred.

[0049] The releasable substrate is disposed in contact with the anisotropic conductive film. The surface of the peelable 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 the anisotropic conductive film of this 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 peelable 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 AA' in Fig. 3. Fig. 3 is a cross-sectional view taken along line BB' in Fig. 2. The anisotropic conductive film 20 of 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 in 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 the present 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 quadrangular prism shape are arranged in a single layer in the resin component 3. The arrangement pattern of the conductive materials 4 is, for example, 60° staggered.

[0054] The shape of the conductive material 4 is not particularly limited and can be appropriately selected depending on the purpose, but is preferably a sphere, an oval sphere, a cylinder, an oval cylinder, an approximately square prism, an approximately equilateral triangle, an approximately 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 it is preferable that the conductive materials are arranged regularly in a single layer without contacting each other, and examples of such patterns include 60° staggered, 45° staggered, parallel squares, 60° staggered regular hexagons, equilateral triangle arrangement, and alternating squares. Here, "60° staggered" refers to an arrangement pattern in which the centers of the conductive materials in plan view are aligned with the vertices of multiple equilateral triangles that share a common side, and "45° staggered" refers to an arrangement pattern in which the centers of the conductive materials in plan view are aligned with the vertices of multiple isosceles right triangles that share a common side.

[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 embodiment.

[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 an anisotropic conductive connection using the anisotropic conductive adhesive or anisotropic conductive film. Examples include glass substrates with terminals, plastic substrates with terminals, ICs (Integrated Circuits), TAB (Tape Automated Bonding) tapes, Flex-on-Glass (FOG), Chip-on-Glass (COG), Chip-on-Flex (COF), Flex-on-Board (FOB), Flex-on-Flex (FOF), and liquid crystal panels.

[0059] Examples of the glass substrate having the 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 IC chips for controlling liquid crystal screens in flat panel displays (FPDs).

[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 may be different circuit members.

[0061] [Manufacturing method of 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. For example, they can be suitably carried out by a method that includes at least a first placement step, a second placement step, and a heat pressing step, and further includes other steps such as a temporary attachment step as necessary. The connection method is a method of anisotropically conductively connecting the terminals of a first circuit member and the terminals of a second circuit member.

[0062] The first circuit member and the second circuit member are not particularly limited and can be appropriately selected 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 process> The first placement process is not particularly limited as long as it is a process of placing the anisotropic conductive film of this embodiment on the terminal of the first circuit component so that it contacts the terminal of the first circuit component, 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 component on the anisotropic conductive film so that the terminals of the second circuit component contact the anisotropic conductive film, and can be selected appropriately depending on the purpose.

[0065] <Heat pressing process> 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 be, for example, a pressing member having a heating mechanism, or 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 pressure of the pressing 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, and may be, for example, 0.5 seconds to 120 seconds.

[0067] <Temporary pasting process> The temporary attachment process is not particularly limited as long as it is a process in which, after the first placement process, the anisotropic conductive film is heated and pressed at a temperature lower than the heating temperature in the heating and pressing process, and the anisotropic conductive film is attached to the first circuit component, 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 heat 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 pressure to be applied in the temporary bonding 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 may be, for example, 0.5 seconds to 10 seconds. [Example]

[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 (a soluble polyimide described in Example 1 of JP-A No. 2005-272655, a product synthesized in-house) 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. A polyimide solution and an epoxy resin (EXA-850CRP, manufactured by DIC Corporation) were mixed at a solids ratio of 50:50 to 100 parts by mass of a resin component. Five parts by mass of a curing agent, Curesol (2E4MZ, manufactured by Shikoku Chemical Industry Co., Ltd.), was added and further mixed. A planetary mixer (Awatori Rentaro ARE-312, manufactured by Thinky Corporation) was used for mixing. To the resulting mixture, 50 parts by mass of Ni particles (diameter 3 μm, manufactured by Sekisui Chemical Co., Ltd.) serving as a conductive material were added as a conductive material. Further mixing was performed to disperse the conductive material, yielding an anisotropic conductive adhesive of Example 1.

[0073] [ka]

[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, resulting in an anisotropic conductive film of Example 1 with an average thickness of 15 μm.

[0075] Example 2 An 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 An 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 The anisotropic conductive adhesive and anisotropic conductive film of Example 5 were obtained in the same manner as 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 An 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. 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 of JP-A-2010-33793, 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 was changed from 50:50 to 0:100.

[0082] <Evaluation> Using each of the obtained anisotropic conductive films, the "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> <<Making a pressure-bonded laminate>> The substrate for evaluation was a flexible printed circuit board (FPC) with Cu / Ni / Au plated wiring (wiring width: 25 μm, wiring spacing: 25 μm, 50 μm pitch). An anisotropic conductive film was sandwiched between two substrates for evaluation, and thermocompression bonding was performed using a constant-heating head compression bonder (BD-01 tabletop thermocompression bonder, manufactured by Ohashi Manufacturing Co., Ltd.) at 2 MPa and 180°C for 20 seconds to produce a compression-bonded laminate for evaluation.

[0084] <<Evaluation of initial conduction characteristics>> A current was passed through the resulting 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 applied 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 criteria.

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

[0086] <Electrical connection reliability after temperature cycling> <<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>> Except for using a pressure-bonded laminate subjected to a temperature cycle, the conduction resistance was measured and evaluated in accordance with the above-mentioned <<Evaluation of initial conduction characteristics>> and the evaluation criteria.

[0088] <Adhesion> The bonded laminate subjected to the temperature cycle 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 are less than 0.1% of the observed field of view, which is within the practical range. ×: Lifting, peeling, or voids from the substrate are present in 0.1% or more of the observed field of view, and are outside the practical range.

[0089] [Table 1] [Explanation of symbols]

[0090] 1. Peelable substrate 2 Anisotropic conductive adhesive 3 Resin component 4. Conductive materials 10 Anisotropic conductive film (dispersion type) 20,30 Anisotropic conductive film (array type)

Claims

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

2. 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): 【Chemical 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. 【Chemistry 2】 【Chemistry 3】 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. 【Chemistry 4】

3. 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): 【Chemistry 5】 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: 【Chemistry 6】 【Chemistry 7】 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: 【Chemistry 8】

4. 4. The anisotropic conductive adhesive according to claim 1, wherein the content of the resin having the heterocyclic ring in its main chain is 20% by mass or more and 80% by mass or less with respect to the total amount of the resin components.

5. The resistivity of the conductive material is 120×10 －８ 4. The anisotropic conductive adhesive according to claim 1, wherein the anisotropic conductive adhesive has a resistance of Ω·m or less.

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

7. 4. The anisotropic conductive adhesive according to claim 1, wherein the conductive material comprises at least one selected from the group consisting of metal particles, alloy particles, and core-shell particles.

8. The anisotropic conductive adhesive according to claim 1 , further comprising a curing agent.

9. The anisotropic conductive adhesive according to claim 1 , further comprising another resin.

10. 4. The anisotropic conductive adhesive according to claim 1, which is an anisotropic conductive adhesive film.

11. 11. The anisotropic conductive adhesive according to claim 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 first circuit member; a second circuit member; A connection structure comprising: the anisotropic conductive adhesive according to claim 10 that anisotropically conductively connects the first circuit member and the second circuit member.

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