Adhesive composition for circuit connection, adhesive film for circuit connection, method for manufacturing a circuit connection structure, and circuit connection structure

Abstract

To provide an adhesive composition and adhesive film for circuit connections that can suppress the decrease in adhesive strength associated with narrowing the width, as well as a method for manufacturing a circuit connection structure using the same, and a circuit connection structure. [Solution] The adhesive composition for circuit connection contains (A) a thermoplastic resin, (B) a radical polymerizable compound, (C) a radical polymerization initiator, (D) a thiol compound having two or more thiol groups in its molecule, and (E) a nitroxide compound having an aminoxyl group in its molecule.

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition for circuit connections, an adhesive film for circuit connections, a method for manufacturing a circuit connection structure, and a circuit connection structure. [Background technology]

[0002] Conventionally, in the fields of semiconductor devices and image display devices, circuit connection materials are used to connect various circuit components. Examples of circuit connection materials include adhesive compositions and anisotropic conductive adhesives containing conductive particles (see, for example, Patent Document 1).

[0003] The connection of circuit components using anisotropic conductive adhesive is performed by pressing the circuit components together (thermocompression) while heating them with the adhesive in between. This results in a connection structure in which the circuit components are joined together and the electrodes of the circuit components are electrically connected to each other.

[0004] In recent years, displays for televisions, smartphones, and other devices have been getting narrower bezels, creating a demand for image display devices that can achieve this narrow bezel design. For the manufacture of such image display devices, a method known as FOG (Film On Glass) mounting is sometimes applied, in which a flexible circuit board containing driver ICs and other components is mounted onto the glass substrate that makes up the display panel. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 1-251787 [Overview of the project] [Problems that the invention aims to solve]

[0006] Further reducing the bezel size of displays requires even narrower connections between circuit components. In this case, the circuit connection materials used for the connections must also be narrower, making it difficult to ensure sufficient adhesive strength between circuit components.

[0007] Therefore, the present invention aims to provide an adhesive composition and adhesive film for circuit connections that can suppress the decrease in adhesive strength associated with narrowing the width, as well as a method for manufacturing a circuit connection structure using the same, and a circuit connection structure. [Means for solving the problem]

[0008] In several aspects, the present invention provides the following [1] to

[12] . [1] A circuit connection adhesive composition comprising a thermoplastic resin, a radical polymerizable compound, a radical polymerization initiator, a thiol compound having two or more thiol groups in its molecule, and a nitroxide compound having an aminoxyl group in its molecule. [2] The circuit connection adhesive composition according to [1], wherein the ratio T / N of the content T of the thiol compound to the content N of the nitroxide compound is 1 to 100. [3] The circuit connection adhesive composition according to [1] or [2], further containing conductive particles. [4] A circuit connection adhesive film comprising a thermoplastic resin, a radical polymerizable compound, a radical polymerization initiator, a thiol compound having two or more thiol groups in its molecule, and a nitroxide compound having an aminoxyl group in its molecule. [5] The circuit connection adhesive film according to [4], wherein the ratio T / N of the content T of the thiol compound to the content N of the nitroxide compound is 1 to 100. [6] The circuit connection adhesive film according to [4] or [5], further containing conductive particles. [7] A method for manufacturing a circuit connection structure, comprising the steps of: heat-pressing a first circuit member having a first circuit electrode formed on the main surface of a first circuit board and a second circuit member having a second circuit electrode formed on the main surface of a second circuit board with a circuit connection adhesive film described in any of [4] to [6] interposed between the first circuit member and the second circuit member, thereby electrically connecting the first circuit electrode and the second circuit electrode. [8] A first circuit member having first circuit electrodes formed on the main surface of a first circuit board, A second circuit electrode is formed on the main surface of a second circuit board, and a second circuit member is arranged such that the second circuit electrode and the first circuit electrode face each other. The device comprises a connecting member provided between the first circuit member and the second circuit member, which electrically connects the first circuit member and the second circuit member, A circuit connection structure wherein the connecting member is a cured product of the circuit connection adhesive composition described in any of [1] to [3]. [9] The circuit connection structure according to [8], wherein the first circuit board is a glass substrate and the second circuit board is a flexible substrate.

[10] A circuit connection structure comprising: a first circuit member having a first circuit electrode formed on the main surface of a first circuit board; a second circuit member having a second circuit electrode formed on the main surface of a second circuit board, arranged such that the second circuit electrode and the first circuit electrode face each other; and a connecting member provided between the first circuit member and the second circuit member for electrically connecting the first circuit member and the second circuit member, wherein the first circuit electrode is located near one side surface of the first circuit board, the second circuit board extends outward beyond the one side surface of the first circuit board, and the connecting member has an overhang that contacts a part of the one side surface of the first circuit board and a part of the main surface of the second circuit board.

[11] The circuit connection structure according to

[10] , wherein the first circuit board is a glass substrate and the second circuit board is a flexible substrate.

[12] The circuit connection structure according to

[10] , wherein the connection member is a cured product of the adhesive composition according to any one of [1] to [3].

Advantages of the Invention

[0009] According to the present invention, it is possible to provide an adhesive composition for circuit connection and an adhesive film for circuit connection that can suppress a decrease in adhesive strength accompanying narrowing, and a method for manufacturing a circuit connection structure and a circuit connection structure using them.

[0010] The inventors of the present invention speculate as follows about the reason why the adhesive composition for circuit connection and the adhesive film for circuit connection according to the present invention can suppress a decrease in adhesive strength accompanying narrowing. A nitroxide compound having an aminoxyl group in the molecule functions as a polymerization inhibitor, so that the polymerization initiation temperature can be increased during circuit connection, and the flow time of the adhesive at the initial stage of connection can be extended. At this time, by using in combination a thiol compound having two or more thiol groups in the molecule that functions as a crosslinking agent, a decrease in the heat generation end temperature and the total heat generation amount of the polymerization reaction due to the polymerization inhibitor can be suppressed, sufficient curability can be imparted during the connection process, and it is considered that a higher adhesive force can be exhibited.

[0011] By the way, in FOG mounting, interfacial peeling between the connection member formed of the circuit connection material and the flexible substrate tends to occur easily. According to the study by the inventors of the present invention, when observing the circuit member after performing a peeling test on the circuit connection structure, it has been found that there may be no residue of the connection member remaining on the flexible substrate side. The reason for this is considered that since the area of the metal electrode of the flexible substrate is smaller than that of the glass substrate, it is difficult to obtain adhesion with the connection member, and when this adhesion is lower than the breaking strength of the connection member, the connection member is likely to peel from the interface between the flexible substrate and its surface electrode. On the other hand, according to the adhesive composition for circuit connection and the adhesive film for circuit connection according to the present invention, by having the above-described fluidity and curability, even when connecting a circuit member having a flexible substrate, it is possible to form a connection member that is less likely to cause interfacial peeling with the flexible substrate.

Brief Description of the Drawings

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an embodiment of a laminated film including an adhesive film for circuit connection according to the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view for explaining an embodiment of a method for manufacturing a circuit connection structure according to the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional view showing an embodiment of a circuit connection structure according to the present invention.

Embodiments for Carrying Out the Invention

[0013] In this specification, a numerical range indicated by using "~" means a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value of a certain stepwise numerical range may be replaced with the upper limit value or the lower limit value of another stepwise numerical range. Also, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. Further, the individually described upper limit value and the lower limit value can be arbitrarily combined. Also, in this specification, "(meth)acrylate" means at least one of acrylate and the corresponding methacrylate. The same applies to other similar expressions such as "(meth)acryloyl". Also, "(poly)" means both cases with and without the prefix "poly". Also, "A or B" means that either A or B may be included, or both may be included. Also, the materials exemplified below may be used alone or in combination of two or more, unless otherwise specified. The content of each component in the composition means the total amount of the plurality of substances corresponding to each component in the composition, unless otherwise specified when there are a plurality of substances corresponding to each component in the composition.

[0014] The following describes in detail embodiments for carrying out the present invention (hereinafter referred to as "this embodiment"), with reference to the drawings as appropriate. The present invention is not limited to the following embodiments.

[0015] <Adhesive composition for circuit connections> The circuit connection adhesive composition of this embodiment contains (A) a thermoplastic resin (hereinafter also referred to as "component (A)"), (B) a radical polymerizable compound (hereinafter also referred to as "component (B)"), (C) a radical polymerization initiator (hereinafter also referred to as "component (C)"), (D) a thiol compound having two or more thiol groups in its molecule (hereinafter also referred to as "component (D)"), and (E) a nitroxide compound having an aminooxyl group in its molecule (hereinafter also referred to as "component (E)").

[0016] The circuit connection adhesive composition of this embodiment may further contain (F) conductive particles (hereinafter also referred to as "component (F)").

[0017] [(A) Component: Thermoplastic resin] (A) The following can be used as components: polyvinyl butyral resin, polyvinyl formal resin, polyamide resin, polyester resin, phenolic resin, epoxy resin, phenoxy resin, polystyrene resin, xylene resin, polyurethane resin, polyester urethane resin, etc. These can be used individually or in combination of two or more.

[0018] The weight-average molecular weight of the above thermoplastic resin is 1.0 × 10⁻⁶, from the perspective of film-forming properties and other factors. 4 The above is also acceptable, and from the viewpoint of mixability, 1.0 × 10 4 The above 1.0 × 10 6 It is acceptable to be less than [a certain value].

[0019] The weight-average molecular weight of a thermoplastic resin is determined by gel permeation chromatography (GPC) using a calibration curve based on standard polystyrene, according to the following conditions. [GPC Conditions] Equipment used: Hitachi L-6000 (Hitachi, Ltd.), Column: Gelpack GL-R420 + Gelpack GL-R430 + Gelpack GL-R440 (3 columns in total) (Resonac Corporation), Eluent: Tetrahydrofuran, Measurement temperature: 40℃, Flow rate: 1.75 ml / min, Detector: L-3300RI (Hitachi, Ltd.)

[0020] Furthermore, component (A) has a Tg (glass transition temperature) of 40°C or higher and a weight-average molecular weight of 1.0 × 10⁻⁶. 4 A hydroxyl group-containing resin (e.g., phenoxy resin) meeting the above criteria can be used. The hydroxyl group-containing resin may be modified with an epoxy group-containing elastomer.

[0021] In this specification, thermoplastic resins having radically polymerizable functional groups are to be formulated as (B) radically polymerizable compounds.

[0022] Phenoxy resins can be obtained by reacting difunctional phenols with epihalohydrins to a high molecular weight, or by polyaddition reaction between difunctional epoxy resins and difunctional phenols.

[0023] Alternatively, polyester urethane resin may be used as component (A).

[0024] The content of component (A) in the adhesive composition may be 20-80% by mass, 25-70% by mass, or 30-65% by mass, based on the resin components of the adhesive composition (for example, components other than conductive particles and non-conductive fillers), from the viewpoint of improving adhesive strength, film-forming properties, and fluidity.

[0025] [(B) Component: Radical polymerizable compound] (B) Component can be a compound having a radically polymerizable functional group. Examples of radically polymerizable functional groups include vinyl groups, acryloyl groups, and methacryloyl groups. Of these, compounds having an acryloyl group and / or a methacryloyl group are more preferred. Component (B) can be used alone or in combination of two or more.

[0026] The adhesive composition of this embodiment may also use polymers such as polyurethane, polystyrene, polyethylene, polyvinyl butyral, polyvinyl formal, polyimide, polyamide, polyester, polyvinyl chloride, polyphenylene oxide, urea resin, melamine resin, phenol resin, xylene resin, epoxy resin, polyisocyanate resin, and phenoxy resin as component (B). The polymer used as component (B) has at least one radically polymerizable functional group in its molecule.

[0027] (B) It is preferable to include a polymer as component (B) because it is easy to handle and has excellent stress relaxation during curing, and it is even more preferable if the polymer has functional groups such as hydroxyl groups because it improves adhesion.

[0028] The weight-average molecular weight of the above polymer is 1.0 × 10⁻⁶. 4 It may be greater than or equal to 1.0 × 10 in terms of mixability. 4 The above 1.0 × 10 6 The following may also apply. The weight-average molecular weight here is measured using a calibration curve with standard polystyrene by gel permeation chromatography (GPC) according to the conditions described in the examples.

[0029] (B) Component can be a (poly)urethane (meth)acrylate compound from the viewpoint of improving high temperature and high humidity connection reliability.

[0030] The content of the (poly)urethane (meth)acrylate compound may be 40-95% by mass, 50-90% by mass, or 55-85% by mass, based on the total mass of component (B), in terms of the balance between crosslinking density and curing shrinkage.

[0031] Component (B) can be ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, 2-hydroxy-1,3-di(meth)acryloxypropane, 2,2-bis[4-((meth)acryloxymethoxy)phenyl]propane, 2,2-bis[4-((meth)acryloxypolyethoxy)phenyl]propane, dicyclopentenyl(meth)acrylate, tricyclodecanyl(meth)acrylate, tris((meth)acryloyloxyethyl) isocyanurate, urethane(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, isocyanurate EO (ethylene oxide) modified diacrylate, 2-methacryloyloxyethyl acid phosphate, etc.

[0032] Furthermore, as component (B), a substructure having at least one selected from the group consisting of a dicyclopentane skeleton, a tricyclodecane skeleton, and a triazine ring can be used.

[0033] Component (B) may contain a (meth)acrylate compound having a tricyclodecane skeleton in order to balance the crosslinking density and curing shrinkage and to further reduce connection resistance. The content of the (meth)acrylate compound having a tricyclodecane skeleton may be, for example, 0 to 90% by mass, 5 to 60% by mass, or 10 to 30% by mass, based on the total mass of component (B), in order to balance the crosslinking density and curing shrinkage.

[0034] Component (B) may contain a (meth)acrylate compound represented by the following formula (B-1) (a (meth)acrylate compound having a phosphate ester structure). In this case, the adhesive strength to the surface of inorganic materials (metals, etc.) is improved, making it suitable for bonding electrodes together (for example, circuit electrodes together). [ka] In formula (B-1), n ​​represents an integer from 1 to 3, and R represents a hydrogen atom or a methyl group.

[0035] The (meth)acrylate compound represented by formula (B-1) can be obtained, for example, by reacting phosphoric anhydride with 2-hydroxyethyl (meth)acrylate. Specific examples of the (meth)acrylate compound represented by formula (B-1) include mono(2-(meth)acryloyloxyethyl) acid phosphate and di(2-(meth)acryloyloxyethyl) acid phosphate.

[0036] The content of the (meth)acrylate compound represented by formula (B-1) may be, for example, 1 to 10% by mass, 2 to 5% by mass, or 2 to 4% by mass, based on the total mass of component (B), in order to easily obtain the crosslink density necessary to reduce connection resistance and improve connection reliability.

[0037] The content of component (B) in the adhesive composition may be 20-80% by mass, 30-70% by mass, or 35-65% by mass, based on the total mass of the resin components of the adhesive composition (e.g., components other than conductive particles and non-conductive fillers), in order to easily obtain adhesive strength even when the width of the connection is small.

[0038] [(C) Component: Radical polymerization initiator] (C) Component can be a compound that generates free radicals, for example, peroxide compounds, azo compounds, and other compounds that decompose upon heating to generate free radicals. The radical polymerization initiator is selected as appropriate depending on the desired connection temperature, connection time, etc. Component (C) can be used alone or in combination of two or more.

[0039] Examples of radical polymerization initiators include diacyl peroxides, peroxydicarbonates, peroxyesters, peroxyketals, dialkyl peroxides, and hydroperoxides.

[0040] Examples of diacyl peroxides include 2,4-dichlorobenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, succinic peroxide, benzoyl peroxytoluene, and benzoyl peroxide.

[0041] Examples of peroxydicarbonates include di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, di-2-ethoxymethoxyperoxydicarbonate, di(2-ethylhexylperoxy)dicarbonate, dimethoxybutyl peroxydicarbonate, and di(3-methyl-3-methoxybutylperoxy)dicarbonate.

[0042] Peroxyesters include 1,1,3,3-tetramethylbutyl peroxyneodecanoate, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, t-butyl peroxypivalate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, 1-cyclohexyl-1-methylethyl peroxy-2-ethylhexanoate, t-hexyl peroxy-2-ethylhexanoate, and t-butyl peroxy Examples include c-2-ethylhexanoate, t-butyl peroxyisobutyrate, 1,1-bis(t-butylperoxy)cyclohexane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di(m-toluylperoxy)hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, and t-butylperoxyacetate.

[0043] Examples of peroxyketals include 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-(t-butylperoxy)cyclododecane, and 2,2-bis(t-butylperoxy)decane.

[0044] Examples of dialkylperoxides include α,α'-bis(t-butylperoxy)diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and t-butylcumyl peroxide.

[0045] Examples of hydroperoxides include diisopropylbenzene hydroperoxide and cumene hydroperoxide.

[0046] These radical polymerization initiators may be used in combination with decomposition accelerators, inhibitors, etc. Furthermore, those radical polymerization initiators coated with polyurethane-based or polyester-based polymers and microencapsulated are preferred because they extend their shelf life.

[0047] The content of component (C) in the adhesive composition may be 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, 20% by mass or less, 10% by mass or less, or 5% by mass or less, or 0.1 to 20% by mass, 0.5 to 10% by mass, or 1 to 5% by mass, based on the total mass of the resin components of the adhesive composition (e.g., components other than conductive particles and non-conductive fillers), from the viewpoint of pot life.

[0048] [(D) Component: Thiol compound having two or more thiol groups in the molecule] Component (D) may be a compound having three or more thiol groups in its molecule, or a compound having six or more thiol groups in its molecule. In the cured product of the adhesive composition, component (D) functions as a crosslinking agent during the polymerization of component (A), forming a crosslinked structure (-CSC-) derived from component (D). Therefore, when the above-mentioned polyfunctional thiol compound is used as component (D), it is easier to obtain a cured product that has flexibility that does not hinder transferability, while having a high crosslink density that further suppresses the flow of conductive particles. Since component (D) can form a crosslinked structure when used in combination with component (A), it may be a compound that does not have (meth)acryloyl groups in its molecule.

[0049] Compounds having three or more thiol groups in the molecule and not having a (meth)acryloyl group in the molecule include 1,3,5-tris(2-(3-sulfanylbutanoyloxy)ethyl)-1,3,5-triazinan-2,4,6-trione, pentaerythritol tetrakis(3-mercaptobutyrate), trimethylolpropane tris(3-mercaptopropionate), and tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate.

[0050] Examples of compounds having six or more thiol groups in the molecule and not having a (meth)acryloyl group in the molecule include, for example, compounds in which multiple pentaerythritol skeletons are formed via ether bonds. Here, "pentaerythritol skeleton" refers to the substructure shown in the following formula (D-1).

[0051] [ka]

[0052] In particular, it is preferable that at least one of the thiol groups is a primary thiol group, and more preferably that all of the thiol groups are primary thiol groups. By using thiol compounds having these primary thiol groups, it tends to be easier to obtain adhesive compositions that can provide good connection reliability during low-temperature, short-time connection.

[0053] Examples of thiol compounds include dipentaerythritol hexakis(3-mercaptopropionate) and dipentaerythritol hexakis(3-mercaptobutyrate) (see formulas (D-2) and (D-3) below).

[0054] [ka] In equation (D-2), the asterisk * indicates a bonding site of substituent R.

[0055] [ka] In formula (D-3), the asterisk * indicates the bonding site of substituent R.

[0056] The molecular weight of the thiol compound is preferably from 400 to 5000, more preferably from 600 to 2500. When the thiol compound having such a molecular weight is incorporated into the film adhesive, it tends to be less volatile in the drying process and to be easily compatible with other components.

[0057] From the viewpoint of easy compatibility with other components and improvement of the fluidity of the adhesive, the number of thiol groups in the thiol compound is preferably 20 or less, more preferably 15 or less, and particularly preferably 10 or less.

[0058] From the viewpoint of easily maintaining sufficient connection reliability even under low-temperature and short-time connection conditions, the content of component (D) in the adhesive composition is preferably 1.5 to 16 parts by mass, more preferably 2 to 12.5 parts by mass, and particularly preferably 2.5 to 10 parts by mass with respect to 100 parts by mass of component (B).

[0059] [Component (E): Nitroxide compound having an aminoxyl group in the molecule] As the nitroxide compound having an aminoxyl group (>N - O·) used in the present invention, there are no particular restrictions and known ones can be used. Specific examples thereof include, for example, compounds represented by the following general formula (E).

[0060] [Chemical formula] Here, in formula (E), R 1 represents a hydrogen atom, a hydroxyl group, an amino group, a carboxyl group, a cyano group, a thioisocyanate group, an alkyl group having 1 to 10 carbon atoms, an aryl group, an alkoxy group having 1 to 20 carbon atoms, an ester group, or an amide group, and X 1 , X 2 , X 3 and X 4 each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.

[0061] More specifically, examples of nitroxide compounds include those represented by the following formulas (1) to (16). Furthermore, the side chains of polyamines, polyesters, polyacrylates, etc., can be modified from the compound represented by the above general formula (E) to R. 1 or X 4 Examples include polymers in which a monovalent group, obtained by eliminating a certain component, is introduced as a substituent.

[0062] [ka]

[0063] The content of component (E) in the adhesive composition may be 0.01 to 10 parts by mass, or 0.02 to 0.5 parts by mass, per 100 parts by mass of component (B). Since the nitroxide compound can almost completely trap the radicals generated from the radical polymerization initiator, the initiation and progress of radical polymerization are completely suppressed while the nitroxide compound remains, and radical polymerization proceeds after the nitroxide compound is completely consumed. Therefore, when the content of component (E) is within the above range, it becomes easier to ensure sufficient flow time for the adhesive composition during bonding, and the process margin of the adhesive composition can be expanded.

[0064] Furthermore, the ratio T / N of the content T of the (D) thiol compound to the content N of the (E) nitroxide compound may be 1 to 100, 3 to 50, or 5 to 30. In this case, it becomes easier to obtain a cured product with a high crosslinking density that further suppresses the flow of conductive particles while expanding the above process margin.

[0065] [(F) Component: Conductive particles] The conductive particles may be metal particles such as Au, Ag, Ni, Cu, or solder, or conductive carbon particles composed of conductive carbon. The conductive particles may also be those in which the surface of a transition metal such as Ni is coated with a noble metal such as Au. From the viewpoint of obtaining sufficient pot life, the surface layer can be made of Au, Ag, or platinum group noble metals, and may even be Au. Furthermore, the conductive particles may be coated conductive particles in which a conductive layer is formed on the surface of non-conductive particles such as glass, ceramic, or plastic by coating the surface of the non-conductive particle with the aforementioned conductive material, and the outermost layer is composed of a noble metal. When such particles, or molten metal particles, are used, their deformability under heating and pressurization increases the contact area with the electrode during connection, thereby improving reliability.

[0066] The conductive particles may be insulating coated conductive particles comprising the above-mentioned metal particles, conductive carbon particles, or coated conductive particles, and an insulating layer comprising an insulating material such as resin that covers the surface of the particles. When the conductive particles are insulating coated conductive particles, even if the conductive particle content is high, the surface of the particles is covered with resin, which suppresses the occurrence of short circuits due to contact between conductive particles and also improves the insulation between adjacent electrode circuits.

[0067] The conductive particles can be used either individually or in combination of two or more of the various conductive particles described above.

[0068] The maximum particle size of conductive particles must be smaller than the minimum electrode spacing (the shortest distance between adjacent electrodes). From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of conductive particles may be 1.0 μm or larger, 2.0 μm or larger, or 2.5 μm or larger. From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of conductive particles may be 50 μm or smaller, 30 μm or smaller, or 20 μm or smaller. From these viewpoints, the maximum particle size of conductive particles may be between 1.0 and 50 μm, 2.0 and 30 μm, or 2.5 and 20 μm. In this specification, the particle size of any 300 conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the largest value obtained is taken as the maximum particle size of the conductive particles. If the conductive particles are not spherical, such as having protrusions, the particle size of the conductive particles is taken as the diameter of the circle circumscribing the conductive particles in the SEM image.

[0069] The average particle size of conductive particles may be 1.0 μm or larger, 2.0 μm or larger, or 2.5 μm or larger, from the viewpoint of excellent dispersibility and conductivity. The average particle size of conductive particles may be 50 μm or smaller, 30 μm or smaller, or 20 μm or smaller, from the viewpoint of excellent dispersibility and conductivity. From these viewpoints, the average particle size of conductive particles may be between 1.0 and 50 μm, between 2.0 and 30 μm, or between 2.5 and 20 μm. In this specification, the particle size of any 300 conductive particles (pcs) is measured by observation using a scanning electron microscope (SEM), and the average value of the obtained particle sizes is defined as the average particle size.

[0070] The content of conductive particles in the adhesive composition may be in the range of 0.1 to 30 parts by volume per 100 parts by volume of the resin component of the adhesive composition (e.g., components other than conductive particles and non-conductive fillers), in order to easily obtain a stable connection resistance. The content of conductive particles may be 0.1 to 10 parts by volume, from the viewpoint of preventing short circuits of adjacent circuits due to excessive conductive particles.

[0071] Furthermore, the content of conductive particles may be 0.5 to 60% by mass, 3 to 45% by mass, or 6 to 30% by mass, based on the total mass of the resin components of the adhesive composition (for example, components other than conductive particles and non-conductive fillers), in order to easily obtain a stable connection resistance.

[0072] [Other ingredients] The adhesive composition of this embodiment may further contain other components in addition to those described above. Examples of other components include coupling agents (hereinafter also referred to as component (G)) and fillers (hereinafter also referred to as component (H)). These components can be used individually or in combination of two or more.

[0073] (G) As the coupling agent, a compound having at least one of the following can be used: a vinyl group, an acrylic group (acryloyl group), an amino group, an epoxy group, or an isocyanate group, from the viewpoint of improving adhesion. The coupling agent may be a silane coupling agent, and examples include vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatetopropyltriethoxysilane, and condensates thereof. These may be used individually or in combination of two or more.

[0074] The content of component (G) may be 0.1 to 10% by mass or 0.25 to 7% by mass, based on the total mass of the resin components of the adhesive composition (for example, components other than conductive particles and fillers).

[0075] Examples of the filler component (H) include non-conductive fillers (e.g., non-conductive particles). The filler may be either an inorganic filler or an organic filler. Examples of inorganic fillers include metal oxide nanoparticles such as silica nanoparticles, alumina nanoparticles, silica-alumina nanoparticles, titania nanoparticles, and zirconia nanoparticles; and inorganic nanoparticles such as nitride nanoparticles. Examples of organic fillers include organic nanoparticles such as silicone nanoparticles, methacrylate-butadiene-styrene nanoparticles, acrylic-silicone nanoparticles, polyamide nanoparticles, and polyimide nanoparticles. These nanoparticles may have a uniform structure or a core-shell structure. The maximum diameter of the filler may be less than the minimum particle size of the conductive particles.

[0076] The content of component (F) may be 4 to 60% by volume, 5 to 50% by volume, or 6 to 30% by volume, based on the total volume of the adhesive composition. Furthermore, the content of the filler may be 3 to 60% by mass, 4 to 40% by mass, or 5 to 20% by mass, based on the total mass of the resin components of the adhesive composition (e.g., components other than conductive particles and fillers), from the viewpoint of improving connection reliability.

[0077] Furthermore, the adhesive composition of this embodiment may contain other additives such as softeners, accelerators, antioxidants, colorants, flame retardants, thixotropic agents, and polymerization inhibitors (e.g., hydroquinone, methyl ether hydroquinones).

[0078] <Adhesive film for circuit connections> The circuit connection adhesive film of this embodiment contains (A) a thermoplastic resin, (B) a radical polymerizable compound, (C) a radical polymerization initiator, (D) a thiol compound having two or more thiol groups in its molecule, and (E) a nitroxide compound having an aminoxyl group in its molecule. The circuit connection adhesive composition of this embodiment may further contain (F) conductive particles and can have the same configuration as the adhesive composition of this embodiment described above.

[0079] Furthermore, regarding the content of each component, "based on the total amount of the adhesive composition" shall be read as "based on the total amount of the adhesive film," and "based on the total mass of the resin components of the adhesive composition (e.g., components other than conductive particles and fillers)" shall be read as "based on the total mass of the resin components of the adhesive film (e.g., components other than conductive particles and fillers)."

[0080] When the adhesive film of this embodiment contains conductive particles, the particle density of the conductive particles in the adhesive film for circuit connection is 100 particles / mm² from the viewpoint of obtaining stable connection resistance. 2 More than 1000 pieces / mm 2 or more, or 3000 pieces / mm 2 The above is acceptable. The particle density of conductive particles in the adhesive film for circuit connections should be 100,000 particles / mm² from the viewpoint of ensuring insulation between adjacent electrodes. 2 Below, 50000 pieces / mm 2 The following, or 30,000 pieces / mm 2 The following may apply. From these perspectives, the particle density of conductive particles in the adhesive film for circuit connections is 100 to 100,000 particles / mm². 2 , 1000~50000 pieces / mm 2 , or 3000-30000 pieces / mm 2 That's fine.

[0081] The thickness of the adhesive film for circuit connection may be, for example, 3 μm or more, 10 μm or more, 40 μm or less, 30 μm or less, or 20 μm or less.

[0082] The adhesive film for circuit connections may have a multilayer structure of two or more layers, as this makes it easier to obtain stable connection resistance.

[0083] The adhesive film for circuit connections may also be an adhesive film for circuit connections that does not contain conductive particles.

[0084] The adhesive film for circuit connection according to this embodiment can be manufactured by the following method. Specifically, first, components (A), (B), (C), (D), and (E), as well as other components added as needed, are added to a solvent (organic solvent) and dissolved or dispersed by stirring, mixing, kneading, etc. to prepare a varnish composition (varnish-like adhesive composition). Then, the varnish composition is applied to a substrate that has been treated with a release agent using a knife coater, roll coater, applicator, comma coater, die coater, etc., and the solvent is evaporated by heating to form an adhesive film for circuit connection on the substrate.

[0085] The solvent used in preparing the varnish composition may be one that has the property of uniformly dissolving or dispersing each component. Examples of such solvents include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, and butyl acetate. These solvents can be used individually or in combination of two or more. The stirring, mixing, and kneading during the preparation of the varnish composition can be carried out using, for example, a stirrer, a 3-roll mill, a ball mill, a bead mill, or a homodisper.

[0086] As for the base material, there are no particular restrictions as long as it has heat resistance that can withstand the heating conditions when the solvent is evaporated. For example, base materials (e.g., films) made of stretched polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, synthetic rubber, liquid crystal polymer, etc. can be used.

[0087] The heating conditions for volatilizing the solvent from the varnish composition applied to the substrate may be such that the solvent volatilizes sufficiently. For example, the heating conditions may be 40°C to 120°C for 0.1 minutes to 10 minutes.

[0088] The adhesive film for circuit connections in this embodiment may have some solvent remaining without being removed. The solvent content in the adhesive film for circuit connections in this embodiment may be, for example, 10% by mass or less, or 5% by mass or less, based on the total mass of the adhesive film.

[0089] <Laminated film> Figure 1 is a schematic cross-sectional view showing one embodiment of a laminated film comprising a circuit connection adhesive film according to the present invention. The laminated film 100 shown in Figure 1 comprises a support 8 and a circuit connection adhesive film 40 that is peelably laminated on the support 8. The circuit connection adhesive film 40 is composed of an insulating adhesive layer 5 and conductive particles 7 dispersed in the insulating adhesive layer 5. The insulating adhesive layer 5 is composed of components of the adhesive composition other than the conductive particles. This circuit connection adhesive film is easy to handle, can be easily installed on an adherend, and connection work can be easily performed. The circuit connection adhesive film may have a multilayer structure consisting of two or more layers. When the circuit connection adhesive film contains conductive particles, the circuit connection adhesive film can be suitably used as an anisotropic conductive film.

[0090] According to the circuit connection adhesive film of this embodiment, adherends can usually be bonded together by using a combination of heating and pressurizing. The heating temperature is preferably 100 to 250°C. The pressure is not particularly limited as long as it does not damage the adherends, but is generally preferably 0.1 to 10 MPa. These heating and pressurizing steps are preferably performed for a period of 0.5 to 120 seconds. According to the circuit connection adhesive film of this embodiment, adherends can be sufficiently bonded together even with short heating and pressurizing periods of 5 seconds at conditions of approximately 130 to 200°C and 1 MPa. Furthermore, since the decrease in adhesive strength due to narrowing of the width can be suppressed, circuit members with a narrow connection width (e.g., 1.0 mm or less) can be connected with sufficient adhesive strength.

[0091] Specific examples of circuit components to be connected include glass or plastic substrates with electrodes such as ITO (indium tin oxide) films formed on them, printed circuit boards, ceramic circuit boards, flexible circuit boards, and semiconductor silicon chips used in liquid crystal displays. These are used in combination as needed. According to the circuit connection adhesive film of this embodiment, in addition to printed circuit boards and components having surfaces formed from organic materials such as polyimide films, metals such as copper and aluminum, ITO, silicon nitride (SiN) x It can be used to bond circuit components having a wide variety of surface conditions, such as components having surfaces formed from inorganic materials like silicon dioxide (SiO2).

[0092] The adhesive film for circuit connection according to this embodiment can be used for FOG (Film On Glass) mounting.

[0093] <Manufacturing method for circuit connection structure and circuit connection structure> The manufacturing method of the circuit connection structure of this embodiment comprises the steps of: heat-pressing together a first circuit member having a first circuit electrode formed on the main surface of a first circuit board and a second circuit member having a second circuit electrode formed on the main surface of a second circuit board, with the circuit connection adhesive film of this embodiment described above interposed between the first circuit member and the second circuit member, thereby electrically connecting the first circuit electrode and the second circuit electrode.

[0094] The following describes an example of manufacturing a circuit connection structure by using the circuit connection adhesive film according to this embodiment as an anisotropic conductive film to connect circuit boards and circuit members having circuit electrodes formed on the main surface of the circuit boards as adherends.

[0095] Figure 2 is a schematic cross-sectional view showing one embodiment of manufacturing a connection structure using the circuit connection adhesive film according to this embodiment. As shown in Figure 2(a), the circuit connection adhesive film 40 is placed on the main surface of the first circuit member 20 on the side of the first circuit electrode 22. When the circuit connection adhesive film 40 is provided on the support described above, the laminated film of the circuit connection adhesive film and the support is placed on the circuit member in an orientation where the circuit connection adhesive film 40 is positioned on the side of the first circuit member 20.

[0096] The first circuit member 20 comprises a first circuit board 21 and a first circuit electrode 22 formed on the main surface 21a of the first circuit board 21. An insulating layer may be formed on the main surface 21a of the first circuit board 21. In this embodiment, the first circuit electrode 22 is located near one side surface 21b of the first circuit board.

[0097] The first circuit member 20 is not particularly limited as long as it has circuit electrodes that require electrical connection. The first circuit board 21 can be, for example, an inorganic material substrate such as semiconductor, glass, or ceramic; an organic material substrate such as polyimide or polycarbonate; or a substrate containing both inorganic and organic materials such as glass / epoxy. In this embodiment, the first circuit board 21 may be a glass substrate.

[0098] The width W1 of the adhesive film 40 for circuit connection can be set appropriately to match the width of the connection part. When the first circuit member 20 is a display panel for an image display device, the width W1 may be 3 mm or less, or 0.4 to 1.0 mm, from the viewpoint of accommodating a narrow bezel.

[0099] By applying pressures A and B in the thickness direction of the circuit connection adhesive film 40, as shown in Figure 2(a), the circuit connection adhesive film 40 is temporarily connected to the first circuit member 20 (see Figure 2(b)). At this time, heating may be applied while applying pressure. However, the heating temperature is set to a temperature that is sufficiently lower than the temperature at which the adhesive composition in the circuit connection adhesive film 40 does not harden, i.e., the temperature at which the radical polymerization initiator rapidly generates radicals.

[0100] Next, as shown in Figure 2(c), the second circuit member 30 is placed on the circuit connection adhesive film 40 with the second circuit electrode facing the first circuit member 20. If the circuit connection adhesive film 40 is provided on a support, the support is peeled off before placing the second circuit member 30 on the circuit connection adhesive film 40.

[0101] The second circuit member 30 comprises a second circuit board 31 and a second circuit electrode 32 formed on the main surface 31a of the second circuit board 31. An insulating layer may also be formed on the main surface 31a of the second circuit board 31. In this embodiment, the second circuit board 31 extends outward beyond one side surface 21b of the first circuit board 21.

[0102] The second circuit member 30 is not particularly limited as long as it has circuit electrodes that require electrical connection. The second circuit board 31 can be, for example, an inorganic material substrate such as semiconductor, glass, or ceramic; an organic material substrate such as polyimide or polycarbonate; or a substrate containing both inorganic and organic materials such as glass / epoxy. In this embodiment, the second circuit board 31 may be a flexible substrate (preferably a resin film such as a polyimide film). With the circuit connection adhesive film of this embodiment, even when connecting circuit members having a flexible substrate, it is possible to form a connecting member that is less prone to interfacial delamination with the flexible substrate.

[0103] Subsequently, the circuit connection adhesive film 40 is heated while applying pressures A and B in its thickness direction to perform the final connection. The heating temperature at this time is set to a temperature at which the radical polymerization initiator generates sufficient radicals. As a result, radicals are generated from the radical polymerization initiator, and polymerization of the radical polymerizable compound begins.

[0104] This connection can be performed, for example, under conditions of a heating temperature of 100 to 250°C, a pressure of 0.1 to 10 MPa, and a pressurization time of 0.5 to 120 seconds. After this connection, post-curing may be performed as needed.

[0105] This connection yields the circuit connection structure 1 shown in Figure 3. By heating the circuit connection adhesive film 40, the insulating adhesive hardens while the distance between the first circuit electrode 22 and the second circuit electrode 32 is sufficiently reduced, forming an insulating layer 11. As a result, the first circuit member 20 and the second circuit member 30 are firmly connected via the connecting member 10 which includes the insulating layer 11. That is, the connecting member 10 is made of the cured product of the circuit connection adhesive film according to this embodiment and contains the insulating layer 11 and conductive particles 7 dispersed in the insulating layer 11.

[0106] In the circuit connection structure 1 shown in Figure 3, the connecting member 10 is formed from a cured product of the circuit connection adhesive film according to this embodiment, and can have an overhang 12 that contacts a part of one side surface 21b of the first circuit board 21 and a part of the main surface 31a of the second circuit board 31, thereby making the adhesive strength of the connecting member 10 to the first circuit member 20 and the second circuit member 30 sufficiently high.

[0107] The length W2 of the protruding portion 12 of the connecting member 10 that contacts the main surface 31a of the second circuit board 31 may be 1 to 100, 3 to 50, 5 to 40, or 25 to 35 when W1 is set to 100. The length W3 of the protruding portion 12 of the connecting member 10 that contacts one side surface 21b of the first circuit board 21 may be 1 to 100, 3 to 50, or 5 to 40 when W1 is set to 100.

[0108] If the connecting member 10 has an overhang 12 that satisfies at least the above condition W2, the adhesive strength tends to increase because the overhang acts as a support when peeling. Also, since the second circuit electrode can be covered by more connecting members, moisture resistance is more easily obtained when the adhesive film for circuit connection according to this embodiment contains an ion trapping agent or the like.

[0109] Furthermore, the connecting member 10 formed by the cured product of the circuit connection adhesive film according to this embodiment may be less prone to interfacial delamination with the second circuit board 32 (for example, a flexible substrate). In this case, the adhesive strength between the first circuit member and the second circuit member is primarily influenced by the tensile strength of the cured product of the circuit connection adhesive film, and the adhesive strength can be further increased by improving the physical properties of the cured product. [Examples]

[0110] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples.

[0111] (Synthesis of polyester urethane resin (A1)) In a stainless steel autoclave equipped with a heater, a stirrer, thermometer, condenser, vacuum generator, and nitrogen gas inlet tube, 48 parts by mass of isophthalic acid and 37 parts by mass of neopentyl glycol were added, followed by 0.02 parts by mass of tetrabutoxytitanate as a catalyst. The mixture was then heated to 220°C under a nitrogen stream and stirred for 8 hours. After that, the pressure was reduced to atmospheric pressure (760 mmHg) and cooled to room temperature. This caused a white precipitate to form. The white precipitate was then removed, washed with water, and vacuum-dried to obtain a polyester polyol. After thoroughly drying the obtained polyester polyol, it was dissolved in MEK (methyl ethyl ketone) and placed in a four-necked flask equipped with a stirrer, dropping funnel, reflux condenser, and nitrogen gas inlet tube. Furthermore, dibutyltin dilaurate was added as a catalyst in an amount of 0.05 parts by mass per 100 parts by mass of polyester polyol, and 4,4'-diphenylmethane diisocyanate in an amount of 50 parts by mass per 100 parts by mass of polyester polyol was dissolved in MEK and added using a dropping funnel. The mixture was stirred at 80°C for 4 hours to obtain the target polyester urethane resin. The weight-average molecular weight of the polyester urethane resin was 15,000. The weight-average molecular weight was measured using a calibration curve with standard polystyrene by gel permeation chromatography (GPC) according to the following conditions. (Measurement conditions) Equipment: GPC-8020 manufactured by Tosoh Corporation Detector: RI-8020 manufactured by Tosoh Corporation Column: Gelpack GLA160S+GLA150SG2000Hhr manufactured by Resona Corporation Solvent: tetrahydrofuran Injection volume: 60μL Pressure: 2.94 × 10 6 Pa Flow rate: 1.00mL / min

[0112] <Synthesis of Polyurethane Acrylate B1> A reaction solution was prepared by charging a 2 L (liter) four-necked flask equipped with a thermometer, stirrer, inert gas inlet, and reflux condenser with 4000 parts by mass of polycarbonate diol (Aldrich, number average molecular weight 2000), 238 parts by mass of 2-hydroxyethyl acrylate, 0.49 parts by mass of hydroquinone monomethyl ether, and 4.9 parts by mass of tin-based catalyst. To the reaction solution heated to 70°C, 666 parts by mass of isophorone diisocyanate (IPDI) was uniformly added dropwise over 3 hours and the reaction was allowed to proceed. After the addition was complete, the reaction was continued for 15 hours, and the reaction was considered complete when the NCO% (NCO content) fell to 0.2% by mass or less, yielding urethane acrylate. The NCO% was confirmed by a potentiometric automatic titrator (product name: AT-510, Kyoto Electronics Manufacturing Co., Ltd.). Analysis by GPC revealed that the weight-average molecular weight of urethane acrylate was 8500 (equivalent to standard polystyrene). The weight-average molecular weight was measured using a calibration curve based on standard polystyrene via gel permeation chromatography (GPC) under the following conditions. (Measurement conditions) Equipment: GPC-8020 manufactured by Tosoh Corporation Detector: RI-8020 manufactured by Tosoh Corporation Column: Gelpack GLA160S+GLA150S manufactured by Resona Corporation Sample concentration: 120mg / 3mL Solvent: tetrahydrofuran Injection volume: 60μL Pressure: 2.94 × 10 6 Pa(30kgf / cm 2 ) Flow rate: 1.00mL / min

[0113] <Fabrication of conductive particles (F1)> A layer of nickel with a thickness of 0.2 μm was formed on the surface of polystyrene particles to obtain conductive particles with an average particle size of 3 μm, a maximum particle size of 3.5 μm, and a specific gravity of 2.5.

[0114] <Preparation of adhesive films (Examples and comparative examples)> The following components were mixed in the amounts (parts by mass) shown in Table 1 to prepare varnish compositions (varnish-like adhesive compositions).

[0115] [Thermoplastic resin] A1: Polyester urethane resin synthesized as described above (A1)

[0116] [Radical polymerizable compounds] B1: Polyurethane acrylate synthesized as described above (B1) B2: Isocyanuric acid EO-modified diacrylate (Product name: M-215, manufactured by Toagosei Co., Ltd.) B3: 2-Methacryloyloxyethyl acid phosphate (Product name: Light Ester P-2M, manufactured by Kyoeisha Chemical Co., Ltd.)

[0117] [Radical polymerization initiator] C1: Benzoyl peroxide (Product name: Niper BMT-K40, manufactured by NOF Corporation)

[0118] [Thiol compounds] D1: Dipentaerythritol hexakis(3-mercaptopropionate) (Trade name: DPMP, manufactured by SC Organic Chemicals Co., Ltd.) D2: 1,3,5-Tris(2-(3-sulfanylbutanoyloxy)ethyl)-1,3,5-triazinan-2,4,6-trione (Trade name: Karenz MT NR1, manufactured by Resonaq Corporation, Number of functional groups: 3)

[0119] [Nitroxide compounds] E1: 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl (Product name: Adeka Stab LA-7RD, manufactured by ADEKA)

[0120] [Conductive particles] F1: Conductive particles (F1) prepared as described above.

[0121] [Coupling agent] G1: 3-Methacryloxypropyltrimethoxysilane (Trade name: KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0122] [Filling material] H1: Silica microparticles (product name: R104, manufactured by Nippon Aerosil Co., Ltd., average particle size (primary particle size): 12 nm)

[0123] [Table 1]

[0124] The above varnish composition was applied to a substrate (PET film) with a thickness of 50 μm using a coating apparatus. Next, hot air drying was performed at 70°C for 3 minutes to form an adhesive film (adhesive layer) on the substrate, and a laminated film was prepared. The thickness of the adhesive film (thickness after drying) was 14 μm.

[0125] <Fabrication of connecting structures> Using the adhesive film (width 0.6 mm) prepared as described above, a COF (Fiber Oxide Frame) (manufactured by FLEXSEED) with Cu electrodes of line width 18 μm, pitch 40 μm, and height 8 μm on a 38 μm thick polyimide film was connected to a glass substrate (4 cm × 1.2 cm × thickness 0.7 mm) with thin film electrodes (height: 500 nm) made of silicon nitride (SiNx) on it (manufactured by Technoprint). The connection was made using a thermocompression bonding device (heating method: constant heat type, manufactured by Taiyo Kikai Seisakusho Co., Ltd.) by heating and pressurizing at 150°C and 4 MPa for 6 seconds. As a result, a circuit connection structure was fabricated in which the COF and the glass substrate with thin film electrodes were connected by the cured adhesive film over a width of 0.6 mm.

[0126] The circuit connection structure has a similar structure to that shown in Figure 3, and the length W2 of the protruding portion 12 of the connection member 10 that contacts the main surface of the COF and the length W3 that contacts the side surface of the glass substrate were measured.

[0127] <Measuring adhesive strength> The adhesive strength of the resulting connection structures was measured using the 90-degree peel method in accordance with JIS-Z0237. A Tensilon UTM-4 (manufactured by Toyo Baldwin Co., Ltd., product name, peel strength 50 mm / min, 25°C) was used as the adhesive strength measuring device. The adhesive strength was measured immediately after connection of the connection structures.

[0128] <Evaluation of the fracture surface> The amount of cured adhesive film residue remaining on the glass substrate and COF after measuring the adhesive strength was compared relative to each other and evaluated according to the following criteria.

[0129] [Table 2] [Explanation of symbols]

[0130] 1...Circuit connection structure, 5...Insulating adhesive layer, 7...Conductive particles, 8...Support, 10...Connecting member, 11...Insulating layer, 20...First circuit member, 21...First circuit board, 21a...Main surface, 22...First circuit electrode, 30...Second circuit member, 31...Second circuit board, 31a...Main surface, 32...Second circuit electrode, 40...Adhesive film for circuit connection, 100...Laminated film.

Claims

1. A circuit connection adhesive composition comprising a thermoplastic resin, a radical polymerizable compound, a radical polymerization initiator, a thiol compound having two or more thiol groups in its molecule, and a nitroxide compound having an aminoxyl group in its molecule.

2. The circuit connection adhesive composition according to claim 1, wherein the ratio T / N of the content T of the thiol compound to the content N of the nitroxide compound is 1 to 100.

3. The circuit connection adhesive composition according to claim 1, further containing conductive particles.

4. A circuit connection adhesive film containing a thermoplastic resin, a radical polymerizable compound, a radical polymerization initiator, a radical polymerization initiator, a thiol compound having two or more thiol groups in its molecule, and a nitroxide compound having an aminoxyl group in its molecule.

5. The circuit connection adhesive film according to claim 4, wherein the ratio T / N of the content T of the thiol compound to the content N of the nitroxide compound is 1 to 100.

6. The circuit connection adhesive film according to claim 4, further containing conductive particles.

7. A method for manufacturing a circuit connection structure, comprising the steps of: heat-pressing a first circuit member having a first circuit electrode formed on the main surface of a first circuit board and a second circuit member having a second circuit electrode formed on the main surface of a second circuit board with a circuit connection adhesive film according to any one of claims 4 to 6 interposed between the first circuit member and the second circuit member, thereby electrically connecting the first circuit electrode and the second circuit electrode.

8. A first circuit member having a first circuit electrode formed on the main surface of a first circuit board, A second circuit electrode is formed on the main surface of a second circuit board, and a second circuit member is arranged such that the second circuit electrode and the first circuit electrode face each other. The device comprises a connecting member provided between the first circuit member and the second circuit member, which electrically connects the first circuit member and the second circuit member, A circuit connection structure wherein the connecting member is a cured product of the circuit connection adhesive composition described in any one of claims 1 to 3.

9. The circuit connection structure according to claim 8, wherein the first circuit board is a glass substrate and the second circuit board is a flexible substrate.

10. A first circuit member having a first circuit electrode formed on the main surface of a first circuit board, A second circuit electrode is formed on the main surface of a second circuit board, and a second circuit member is arranged such that the second circuit electrode and the first circuit electrode face each other. The device comprises a connecting member provided between the first circuit member and the second circuit member, which electrically connects the first circuit member and the second circuit member, The first circuit electrode is located near one side surface of the first circuit board. The second circuit board extends outward beyond the one side surface of the first circuit board, A circuit connection structure wherein the connecting member has an overhang that contacts a part of one side surface of the first circuit board and a part of the main surface of the second circuit board.

11. The circuit connection structure according to claim 10, wherein the first circuit board is a glass substrate and the second circuit board is a flexible substrate.

12. The circuit connection structure according to claim 10, wherein the connecting member is a cured product of the adhesive composition according to any one of claims 1 to 3.

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