Adhesive Composition, Adhesive Film, and Connected Structure

Abstract

The present invention provides an adhesive composition which can suppress a decrease in adhesiveness even after storage in a normal temperature / refrigerated environment and achieve excellent adhesiveness under the same adhesion conditions as before. That is, the present invention provides an adhesive composition which is an adhesive composition containing an adhesive composition and a cationic polymerization initiator, the adhesive composition contains a cationically polymerizable component and a film-forming component, the cationic polymerization initiator is a quaternary ammonium salt-based thermoacid generator, and the cationically polymerizable component contains a bifunctional alicyclic epoxy compound and a tetrafunctional alicyclic epoxy compound.

Description

Technical Field

[0001] The present invention relates to an adhesive composition, an adhesive film, and a connection structure body. Background Art

[0002] As a means for bonding an electronic component to a circuit board or the like, adhesive compositions such as anisotropic conductive paste (ACP: Anisotropic Conductive Paste) or anisotropic conductive film (ACF: Anisotropic Conductive Film) or their film-like materials (adhesive films) are widely used. For example, an anisotropic conductive film is used in cases where various terminals are bonded to each other and electrically connected, typified by a case where a terminal of a flexible printed circuit board (FPC) is connected to a terminal of a glass substrate of an FPD panel (so-called FOG).

[0003] In such an adhesive composition, in order to achieve low-temperature rapid curability, it has been proposed to use an alicyclic epoxy compound having a higher cationic polymerization reactivity than a general glycidyl ether compound as a polymerizable compound, and at the same time, to use a sulfonium salt-based thermal acid generator that generates protons by heat as a polymerization initiator that is not inhibited by oxygen and exhibits dark reactivity (Patent Documents 1 to 3).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Laid-Open No. 9-176112;

[0007] Patent Document 2: Japanese Patent Laid-Open No. 2008-308596;

[0008] Patent Document 3: International Publication No. 2012 / 018123. Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] Regarding the adhesive composition, due to globalization of trade and the like, the period from manufacturing to actual use, including storage and transportation, tends to be prolonged. Although an adhesive composition in which an alicyclic epoxy compound and a sulfonium salt-based thermal acid generator are used in combination exhibits excellent adhesiveness when used immediately after manufacturing, it is sometimes difficult to manage the product life as the storage conditions change.

[0011] As a polymerization initiator of an alicyclic epoxy compound, in addition to sulfonium salt-based thermal acid generators, quaternary ammonium salt-based thermal acid generators are also known. The present inventors have found that: when a quaternary ammonium salt-based thermal acid generator is used instead of a sulfonium salt-based thermal acid generator, under the same bonding conditions as when using a sulfonium salt-based thermal acid generator, even when used immediately after manufacture, there are cases where the expected adhesiveness cannot be ensured. Although the adhesiveness can be improved by shifting the bonding conditions to the high temperature / long time side, from the viewpoints of reducing the thermal stress on electronic components or production efficiency, it runs counter to the recent trend of shifting to the low temperature / short time side.

[0012] An object of the present invention is to provide an adhesive composition that can suppress a decrease in adhesiveness even after storage in a normal temperature / refrigerated environment and achieve excellent adhesiveness under the same bonding conditions as before.

[0013] Means for Solving the Problem

[0014] The present inventors conducted in-depth research on the above problems and found that: the above problems can be solved by an adhesive composition having the following constitution, and thus completed the present invention.

[0015] That is, the present invention includes the following contents.

[0016] [1] An adhesive composition that is an adhesive composition containing an adhesive composition and a cationic polymerization initiator, the adhesive composition containing a cationic polymerizable component and a film-forming component,

[0017] The cationic polymerization initiator is a quaternary ammonium salt-based thermal acid generator,

[0018] The cationic polymerizable component contains a bifunctional alicyclic epoxy compound and a tetrafunctional alicyclic epoxy compound.

[0019] [2] The adhesive composition according to [1], wherein the mass ratio of the tetrafunctional alicyclic epoxy compound to the bifunctional alicyclic epoxy compound [tetrafunctional alicyclic epoxy compound / bifunctional alicyclic epoxy compound] (hereinafter referred to as "tetrafunctional / bifunctional mass ratio") is less than 1.0.

[0020] [3] The adhesive composition according to [1] or [2], wherein the tetrafunctional / bifunctional mass ratio is 0.1 or more and 0.85 or less.

[0021] [4] The adhesive composition according to any one of [1] to [3], wherein the bifunctional alicyclic epoxy compound has an epoxy C 3 ~C 10 cycloalkyl group.

[0022] [5] The adhesive composition according to any one of [1] to [4], wherein the tetrafunctional alicyclic epoxy compound has epoxy C 3 ~C 10 cycloalkyl group.

[0023] [6] The adhesive composition according to any one of [1] to [5], wherein the tetrafunctional alicyclic epoxy compound contains a structural unit represented by formula (1),

[0024] [Chemical formula 1]

[0025]

[0026] In the formula, R 1 represents a monovalent organic group having an epoxy C 3 ~C 10 cycloalkyl group, and R 2 represents a hydrogen atom, a hydrocarbon group or an alkoxy group.

[0027] [7] The adhesive composition according to [6], wherein the tetrafunctional alicyclic epoxy compound has 4 structural units represented by formula (1) in one molecule.

[0028] [8] The adhesive composition according to any one of [1] to [7], which further comprises a thiol compound.

[0029] [9] The adhesive composition according to [8], wherein the thiol compound contains the same number of carbonyloxy groups as the mercapto groups in one molecule.

[0030]

[10] The adhesive composition according to [8] or [9], wherein the functional number of the thiol compound is 2 or more.

[0031]

[11] The adhesive composition according to any one of [8] to

[10] , wherein the thiol compound contains a structural unit represented by formula (2),

[0032] [Chemical formula 2]

[0033] .

[0034]

[12] The adhesive composition according to any one of [8] to

[11] , wherein the mass ratio of the thiol compound to the quaternary ammonium salt-based thermal acid generator [thiol compound / quaternary ammonium salt-based thermal acid generator] is 0.1 or more.

[0035]

[13] The adhesive composition according to any one of [1] to

[12] , wherein the film-forming component contains a phenoxy resin.

[0036]

[14] The adhesive composition according to any one of [1] to

[13] , which further comprises conductive particles.

[0037]

[15] An adhesive film, which is composed of the adhesive composition described in any one of [1] to

[14] .

[0038]

[16] A connection structure, which is formed by connecting a first electronic component and a second electronic component through the adhesive composition described in any one of [1] to

[14] or the adhesive film described in

[15] .

[0039]

[17] A method for manufacturing a connection structure, which includes the following steps: pressing a first electronic component and a second electronic component via the adhesive composition described in any one of [1] to

[14] or the adhesive film described in

[15] .

[0040] Advantages of the Invention

[0041] According to the present invention, an adhesive composition can be provided, which can suppress the decrease in adhesiveness even after storage in a normal temperature / refrigerated environment and achieve excellent adhesiveness under the same adhesion conditions as before. Detailed Embodiments

[0042] <Explanation of Terms>

[0043] In this specification, the so-called "C n ~C m " (n and m are positive integers and satisfy n < m) means that the number of carbon atoms in the organic group described after this term is n to m. For example, "C 1 ~C 12 alkyl" means an alkyl group having 1 to 12 carbon atoms.

[0044] In this specification, "alicyclic epoxy compound" refers to an epoxy compound having an alicyclic ring in the molecule. In the alicyclic epoxy compound, the ethylene oxide ring may be formed by two carbon atoms and one oxygen atom constituting the alicyclic ring, or may be separated from the alicyclic ring to form a glycidyl group.

[0045] Hereinafter, the present invention will be described in detail according to its suitable embodiments. The present invention is not limited to the following description, and each component can be appropriately changed without departing from the gist of the present invention.

[0046] [Adhesive Composition]

[0047] The adhesive composition of the present invention is characterized by containing an adhesive composition and a cationic polymerization initiator, and the adhesive composition contains a cationic polymerizable component and a film-forming component.

[0048] The cationic polymerization initiator is a quaternary ammonium salt-based thermoacid generator.

[0049] The cationic polymerizable component contains a bifunctional alicyclic epoxy compound and a tetrafunctional alicyclic epoxy compound.

[0050] <Cationic polymerization initiator>

[0051] The adhesive composition of the present invention is characterized by containing a quaternary ammonium salt-based thermal acid generator as a cationic polymerization initiator.

[0052] As described above, although the sulfonium salt-based thermal acid generator contributes to low-temperature rapid curability in combination with the alicyclic epoxy compound and provides excellent adhesiveness immediately after the production of the adhesive composition, there is a case where the adhesiveness significantly decreases when the adhesive composition is stored for a certain period at normal temperature / refrigerated environment. In contrast, the adhesive composition of the present invention using a quaternary ammonium salt-based thermal acid generator can suppress the decrease in adhesiveness even when stored for a certain period at normal temperature / refrigerated environment. Moreover, by using a quaternary ammonium salt-based thermal acid generator in combination with a specific cationic polymerizable component described later, excellent adhesiveness is achieved under the same adhesion conditions as when using a sulfonium salt-based thermal acid generator.

[0053] As the quaternary ammonium salt-based thermal acid generator, a salt of a quaternary ammonium cation and an acid root anion or a borate anion is preferably used.

[0054] As the quaternary ammonium cation, the following can be mentioned: the cation represented by the formula: NR a R b R c R d+ In the formula, R a 、R b 、R c and R d are linear, branched or cyclic C 1 ~C 12 alkyl or aryl groups, and may each have a hydroxyl group, a halogen atom, an alkoxy group, an amino group, an ester group, etc.

[0055] As the acid root anion, either an inorganic acid root anion or an organic acid root anion can be used. For example, the following can be mentioned: hexafluoroantimonate anion, hexafluorophosphate anion, trifluoromethanesulfonate anion, perfluorobutanesulfonate anion, dinonylnaphthalenesulfonate anion, dinonylnaphthalenesulfonate anion, p-toluenesulfonate anion, dodecylbenzenesulfonate anion.

[0056] As the borate anion, alkyl borate anions and aryl borate anions can be mentioned, and may further have a halogen atom. Among them, an aryl borate anion having a fluorine atom (F-; fluoro group) is preferred, and a tetra(pentafluorophenyl)borate anion is particularly preferred.

[0057] The quaternary ammonium salt-based thermal acid generator can be used alone or in combination of two or more kinds.

[0058] Specific examples of the quaternary ammonium salt-based thermal acid generator include: CXC-1612, CXC-1733, CXC-1738, TAG-2678, CXC-1614, TAG-2689, TAG-2690, TAG-2700, CXC-1802-60, CXC-1821, etc. manufactured by King Industries, Inc. These can be obtained from Kusumoto Chemical Co., Ltd.

[0059] When the total non-volatile content of the cationic polymerizable component is set to 100% by mass, the content of the quaternary ammonium salt-based thermal acid generator in the adhesive composition is preferably 1% by mass or more, more preferably 3% by mass or more, further preferably 5% by mass or more, and still more preferably 7% by mass or more. There is no particular limitation on the upper limit of this content, and it is preferably 30% by mass or less, more preferably 20% by mass or less, and further preferably 15% by mass or less.

[0060] <Adhesive Composition>

[0061] The adhesive composition of the present invention comprises: an adhesive composition containing a cationic polymerizable component and a film-forming component.

[0062] (Cationic Polymerizable Component)

[0063] The adhesive composition of the present invention is characterized in that a bifunctional alicyclic epoxide and a tetrafunctional alicyclic epoxide are used in combination as the cationic polymerizable component. In combination with the quaternary ammonium salt-based thermal acid generator, by using the above-mentioned specific cationic polymerizable component, the adhesive composition of the present invention can suppress the decrease in adhesiveness even when stored in a normal temperature / refrigerated environment for a certain period, and moreover, excellent adhesiveness can be achieved under the same adhesion conditions as when using a sulfonium salt-based thermal acid generator.

[0064] -Bifunctional Alicyclic Epoxide-

[0065] The bifunctional alicyclic epoxide is not particularly limited as long as it is an alicyclic epoxide having two epoxy groups in one molecule, and can be appropriately selected from bifunctional epoxycycloolefin-type epoxides and diglycidyl ether compounds of alicyclic diols, for example.

[0066] The bifunctional epoxycycloolefin-type epoxide is a compound having two epoxycycloalkyl groups in one molecule. The number of carbon atoms of the epoxycycloalkyl group is preferably 3 to 10. Therefore, in a suitable embodiment, the bifunctional alicyclic epoxide has epoxy C 3 ~C 10Naphthenyl. The number of carbon atoms in the epoxy naphthenyl group is more preferably 4 to 10, further preferably 6 to 10, still further preferably 6 to 8, and particularly preferably 6. The two epoxy naphthenyl groups in the bifunctional alicyclic epoxy compound may be the same or different from each other. Among them, the bifunctional alicyclic epoxy compound preferably has two epoxycyclohexyl groups.

[0067] The bifunctional epoxycycloolefin type epoxy compound can be produced, for example, by directly epoxidizing a compound having two cycloolefin skeletons, or by polymerizing a monofunctional epoxycycloolefin type epoxy compound having a polymerizable functional group (for example, (meth)acryloyl group, allyl group, silanol group, etc.) to make it bifunctional.

[0068] In the bifunctional epoxycycloolefin type epoxy compound, the structure other than the epoxy naphthenyl group is not particularly limited, and any structure can be used as long as it does not inhibit the reactivity. From the viewpoint of realizing an adhesive composition having excellent adhesiveness, it preferably has a structure such that the epoxy equivalent is preferably 500 or less, more preferably 400 or less, further preferably 350 or less, still further preferably 300 or less, particularly preferably 250 or less, and more particularly preferably 200 or less. There is no particular limitation on the lower limit of the epoxy equivalent of the bifunctional epoxycycloolefin type epoxy compound, and it is preferably 70 or more, more preferably 80 or more, further preferably 90 or more, and still further preferably 95 or more.

[0069] Specific examples of the bifunctional epoxycycloolefin type epoxy compound include: 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexene carboxylate, diepoxy dicyclohexyl, etc.

[0070] The diglycidyl ether compound of alicyclic diol is a compound having an alicyclic ring and two glycidyl groups in one molecule. The alicyclic ring can be any structure as long as it does not inhibit the reactivity, and it can be a monocyclic ring or a fused ring, and one molecule can contain one or more than two alicyclic rings. From the viewpoint of realizing an adhesive composition having excellent adhesiveness, it preferably has a structure such that the epoxy equivalent is in the same range as the epoxy equivalent described for the above-mentioned epoxycycloolefin type epoxy compound.

[0071] The diglycidyl ether compound of alicyclic diol can be produced, for example, by subjecting the aromatic ring of an aromatic diol diglycidyl ether (for example, a bisphenol type diglycidyl ether such as bisphenol A diglycidyl ether) to a hydrogenation treatment to make it alicyclic, or by subjecting an aliphatic diol (for example, a hydrogenated bisphenol such as hydrogenated bisphenol A) to a glycidyl etherification reaction. Specific examples of the diglycidyl ether compound of alicyclic diol include: hexahydrobisphenol A diglycidyl ether, etc.

[0072] The bifunctional alicyclic epoxy compound can be used alone or in combination of two or more kinds.

[0073] - Tetrafunctional alicyclic epoxy compound -

[0074] The tetrafunctional alicyclic epoxy compound is not particularly limited as long as it is an alicyclic epoxy compound having four epoxy groups in one molecule. For example, it can be appropriately selected from tetrafunctional epoxycycloolefin type epoxy compounds and tetraglycidyl ethers of alicyclic tetrols.

[0075] In combination with the bifunctional alicyclic epoxy compound, from the viewpoint of achieving an adhesive composition with particularly excellent adhesiveness, the tetrafunctional alicyclic epoxy compound preferably contains a tetrafunctional epoxycycloolefin type epoxy compound.

[0076] The tetrafunctional epoxycycloolefin type epoxy compound is a compound having four epoxycycloalkyl groups in one molecule. The number of carbon atoms of the epoxycycloalkyl group is preferably 3 - 10. Therefore, in a suitable embodiment, the tetrafunctional alicyclic epoxy compound has epoxy C 3 ~ C 10 cycloalkyl group. The number of carbon atoms of the epoxycycloalkyl group is more preferably 4 - 10, further preferably 6 - 10, still further preferably 6 - 8, and particularly preferably 6. The four epoxycycloalkyl groups possessed by the tetrafunctional alicyclic epoxy compound may be the same or different from each other. Among them, the tetrafunctional alicyclic epoxy compound preferably has four epoxycyclohexyl groups.

[0077] The tetrafunctional epoxycycloolefin type epoxy compound can be produced, for example, by directly epoxidizing a compound having four cycloolefin skeletons or polymerizing a monofunctional epoxycycloolefin type epoxy compound having a polymerizable functional group (such as (meth)acryloyl group, allyl group, silanol group, etc.) to make it tetrafunctional.

[0078] In the tetrafunctional epoxycycloolefin type epoxy compound, the structure other than the epoxycycloalkyl group is not particularly limited and can be any structure as long as it does not inhibit the reactivity. From the viewpoint of achieving an adhesive composition with excellent adhesiveness, it preferably has a structure with an epoxy equivalent of preferably 500 or less, more preferably 400 or less, further preferably 350 or less, still further preferably 300 or less, and particularly preferably 250 or less. There is no particular limitation on the lower limit of the epoxy equivalent of the tetrafunctional epoxycycloolefin type epoxy compound, and it is preferably 70 or more, more preferably 80 or more, further preferably 90 or more, and still further preferably 95 or more.

[0079] In a suitable embodiment, the tetrafunctional alicyclic epoxy compound contains a structural unit represented by the formula (1).

[0080] [Chemical Formula 3]

[0081]

[0082] In the formula, R 1 represents a monovalent organic group having an epoxy C 3 -C 10 cycloalkyl group, and R 2 represents a hydrogen atom, a hydrocarbon group, or an alkoxy group.

[0083] As the organic group having the epoxy C 1 represented by R 3 -C 10 cycloalkyl group, as long as it has an epoxy C 3 -C 10 cycloalkyl group, there is no particular limitation. The number of epoxy C 3 -C 10 cycloalkyl groups contained in the organic group is not particularly limited, and is preferably 1 to 4, more preferably 1 or 2, and further preferably 1.

[0084] In one embodiment, R 1 is a monovalent group represented by the formula: E-(L) m -. In the formula, E represents an epoxy C 3 -C 10 cycloalkyl group, L represents an alkylene group, a cycloalkylene group, an oxyalkylene group, or an oxycycloalkylene group, and m represents 0 or 1.

[0085] The epoxy C 3 -C 10 cycloalkyl group represented by E is more preferably an epoxy C 4 -C 10 cycloalkyl group, an epoxy C 6 -C 10 cycloalkyl group, an epoxy C 6 -C 8 cycloalkyl group, and further preferably an epoxy C 6 cycloalkyl group, that is, epoxycyclohexyl group.

[0086] In combination with a bifunctional alicyclic epoxy compound, from the viewpoint of achieving an adhesive composition having particularly excellent adhesiveness, L is preferably an alkylene group, more preferably a C

[0087] The number of carbon atoms of the cycloalkylene group and oxycycloalkylene group represented by L is preferably 3 to 10, more preferably 3 to 6.

[0088] -C 1 -C 6 alkylene group.

[0089] In combination with a bifunctional alicyclic epoxy compound, from the viewpoint of achieving an adhesive composition having particularly excellent adhesiveness, m is preferably 1.

[0090] In formula (1), as the hydrocarbon group represented by R 2 Examples thereof include: an alkyl group, a cycloalkyl group, and a monovalent group formed by bonding two or more thereof. The number of carbon atoms of the alkyl group is preferably 1 to 6, more preferably 1 to 4, and still more preferably 1 to 3. The number of carbon atoms of the cycloalkyl group is preferably 3 to 10, more preferably 3 to 6, and still more preferably 4 to 6.

[0091] In formula (1), the alkoxy group represented by R 2 The number of carbon atoms of the alkoxy group is preferably 1 to 6, more preferably 1 to 4, and still more preferably 1 to 3.

[0092] In combination with a bifunctional alicyclic epoxy compound, from the viewpoint of achieving an adhesive composition having particularly excellent adhesiveness, R 2 is preferably an alkyl group, more preferably an alkyl group having 1 to 6 carbon atoms, and still more preferably a methyl group, an ethyl group, a propyl group or a butyl group.

[0093] The tetrafunctional alicyclic epoxy compound preferably has 2 to 4, more preferably 3 or 4, and particularly preferably 4 structural units represented by the above formula (1) in one molecule.

[0094] When the tetrafunctional alicyclic epoxy compound has a structural unit represented by the above formula (1), it may have a linear siloxane structure or a cyclic siloxane structure. In combination with a bifunctional alicyclic epoxy compound, from the viewpoint of achieving an adhesive composition having particularly excellent adhesiveness, it preferably has a cyclic siloxane structure.

[0095] In a particularly suitable embodiment, the tetrafunctional alicyclic epoxy compound contains a compound represented by formula (1-1).

[0096] [Chemical formula 4]

[0097]

[0098] The tetrafunctional alicyclic epoxy compound can be used alone or in combination of two or more.

[0099] In the adhesive composition of the present invention, when the non-volatile components in the adhesive composition are set to 100% by mass, the total content of the bifunctional alicyclic epoxy compound and the tetrafunctional alicyclic epoxy compound is preferably 10% by mass or more, more preferably 15% by mass or more, further preferably 18% by mass or more, and still more preferably 20% by mass or more. There is no particular limitation on the upper limit of this content, and it is preferably 60% by mass or less, more preferably 55% by mass or less, or 50% by mass or less.

[0100] In the combination with the quaternary ammonium salt-based thermal acid generator, from the viewpoint of achieving good adhesiveness under the same adhesion conditions as before, the mass ratio of the tetrafunctional alicyclic epoxy compound to the bifunctional alicyclic epoxy compound (i.e., tetrafunctional / bifunctional mass ratio) is preferably less than 1.0, more preferably 0.9 or less. In particular, when the tetrafunctional / bifunctional mass ratio is 0.85 or less, even after the reliability test in a high-temperature and high-humidity environment, the generation of bulges at the connection part of the connection structure can be significantly suppressed, so it is suitable. The tetrafunctional / bifunctional mass ratio is more preferably 0.7 or less, further preferably 0.6 or less, still more preferably 0.5 or less, and particularly preferably 0.4 or less. The present inventors have found that when the tetrafunctional / bifunctional mass ratio is 0.4 or less, an adhesive composition with extremely excellent adhesiveness can be achieved. In the combination with the quaternary ammonium salt-based thermal acid generator, from the viewpoint of achieving good adhesiveness under the same adhesion conditions as before, the lower limit of the tetrafunctional / bifunctional mass ratio is preferably 0.05 or more, more preferably 0.1 or more. The present inventors have found that in particular, when the tetrafunctional / bifunctional mass ratio is 0.1 or more, even after the reliability test in a high-temperature and high-humidity environment, the generation of bulges at the connection part of the connection structure can be significantly suppressed, so it is suitable, and an adhesive composition with extremely excellent adhesiveness can be achieved. The tetrafunctional / bifunctional mass ratio is more preferably 0.11 or more, further preferably 0.12 or more.

[0101] - Other cationic polymerizable components -

[0102] As long as the adhesive composition of the present invention contains a bifunctional alicyclic epoxy compound and a tetrafunctional alicyclic epoxy compound, it may also contain other cationically polymerizable components. Examples of other cationically polymerizable components include: trifunctional alicyclic epoxy compounds, pentafunctional or higher alicyclic epoxy compounds, and oxetane compounds. When other cationically polymerizable components are contained, their content is not particularly limited. When an oxetane compound is contained, when the total of the bifunctional alicyclic epoxy compound and the tetrafunctional alicyclic epoxy compound is set to 100% by mass, the content of the oxetane compound is preferably 20% by mass or less, more preferably 15% by mass or less, further preferably 10% by mass or less, still further preferably 5% by mass or less, particularly preferably 1% by mass or less, and it may also be not contained.

[0103] (Component for film formation)

[0104] The component for film formation only needs to have film-forming ability and is not particularly limited. The component for film formation can be appropriately selected according to the purpose. Examples include: phenoxy resin, epoxy resin (excluding alicyclic epoxy resin), polyvinyl acetal resin, unsaturated polyester resin, saturated polyester resin, urethane resin, butadiene resin, polyimide resin, polyamide resin, and polyolefin resin. The component for film formation can be used alone or in combination of two or more.

[0105] Among them, from the viewpoints of film-forming property, processability, and connection reliability, phenoxy resin can be suitably used. In addition, from the viewpoint of achieving good adhesiveness, polyvinyl acetal resin is also suitable. Therefore, in one embodiment, the component for film formation contains phenoxy resin. In another embodiment, the component for film formation contains polyvinyl acetal resin. In another suitable embodiment, the component for film formation contains phenoxy resin and polyvinyl acetal resin.

[0106] From the viewpoint of film-forming property, the polystyrene-reduced weight-average molecular weight (Mw) of the component for film formation is preferably 10,000 or more, more preferably 15,000 or more, further preferably 20,000 or more. There is no particular limitation on the upper limit of this Mw, and it is preferably 80,000 or less, more preferably 70,000 or less, and may be 60,000 or less. It can be appropriately selected according to other blends or use purposes. If the component for film formation contains a phenoxy resin with Mw of 50,000 or less, even after a reliability test in a high-temperature and high-humidity environment, the generation of bulges at the connection part of the connection structure can be significantly suppressed, so it is suitable. The polystyrene-reduced Mw of the component for film formation can be measured by gel permeation chromatography (GPC) method and calculated using the calibration curve of standard polystyrene.

[0107] The content of the film-forming component in the adhesive composition is not particularly limited and can be appropriately determined according to the purpose. When the non-volatile component in the adhesive composition is set to 100% by mass, it is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, and still more preferably 40% by mass or more. There is no particular limitation on the upper limit of this content, and it is preferably 70% by mass or less, more preferably 60% by mass or less.

[0108] <Thiol compound>

[0109] The adhesive composition of the present invention may further contain a thiol compound.

[0110] The present inventors have found that: in the adhesive composition of the present invention in which a quaternary ammonium salt-based thermal acid generator and a specific cationic polymerizable component are used in combination, by further containing a thiol compound, the adhesiveness can be specifically and remarkably improved. In this regard, the present inventors have confirmed that: in the conventional adhesive composition using a sulfonium salt-based thermal acid generator, even when a thiol compound is added, no improvement in adhesiveness is observed. Moreover, there is a case where the adhesiveness decreases (Comparative Example 3).

[0111] As the thiol compound, it is sufficient that it has a mercapto group (-SH) in one molecule and is not particularly limited. In the adhesive composition of the present invention in which a quaternary ammonium salt-based thermal acid generator and a specific cationic polymerizable component are used in combination, from the viewpoint of achieving particularly excellent adhesiveness, a compound having the same number of carbonyloxy groups (-C(=O)-O-) as the mercapto group in the molecule is suitable.

[0112] Among them, in the combination of the quaternary ammonium salt-based thermal acid generator and the specific cationic polymerizable component, from the viewpoint of achieving particularly excellent adhesiveness, the thiol compound preferably contains the structural unit represented by the formula (2). The structural unit of the formula (2) may be contained in the main chain of the thiol compound or may be present at the end. Among them, if the structure of the formula (2) exists at the end in the form of 3-mercapto-butyryloxy, there is a tendency to produce an adhesive composition with particularly excellent adhesiveness.

[0113] [Chemical formula 5]

[0114]

[0115] From the viewpoint of achieving excellent adhesiveness, the functional number of the thiol compound is preferably 2 or more, more preferably 3 or more, and further preferably 4 or more. In particular, from the viewpoint of achieving particularly excellent adhesiveness, a compound having preferably 2, more preferably 3, and further preferably 4 of the above-mentioned structural units represented by the formula (2) in the molecule is suitable.

[0116] In the combination of a quaternary ammonium salt-based thermal acid generator and a specific cationic polymerizable component, from the viewpoint of achieving particularly excellent adhesiveness, the molecular weight of the thiol compound is preferably 200 or more, more preferably 250 or more, and further preferably 300 or more. The upper limit of the molecular weight is preferably 1000 or less, more preferably 800 or less, further preferably 700 or less, and still more preferably 600 or less.

[0117] Suitable specific examples of the thiol compound include: 1,4-bis(3-mercaptobutyryloxy)butane [2-functional, molecular weight 294], 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione [3-functional, molecular weight 568], trimethylolpropane tris(3-mercaptobutyrate) [3-functional, molecular weight 440], pentaerythritol tetrakis(3-mercaptobutyrate) [4-functional, molecular weight 545], and the like.

[0118] The thiol compound can be used alone or in combination of two or more.

[0119] When using the thiol compound, from the viewpoint of achieving particularly excellent adhesiveness, the mass ratio of the thiol compound to the quaternary ammonium salt-based thermal acid generator [thiol compound / quaternary ammonium salt-based thermal acid generator] is preferably 0.1 or more, more preferably 0.12 or more, further preferably 0.14 or more, still more preferably 0.15 or more, particularly preferably 0.16 or more, and even more particularly preferably 0.18 or more. There is no particular limitation on the upper limit of this mass ratio, and it is preferably 2 or less, more preferably 1.5 or less, and further preferably 1 or less.

[0120] <Conductive particles>

[0121] The adhesive composition of the present invention may further contain conductive particles. By containing conductive particles, the adhesive composition and its film can be used as conductive paste and conductive film, anisotropic conductive paste and anisotropic conductive film.

[0122] As the conductive particles, known conductive particles used in anisotropic conductive films can be used. Examples of the conductive particles include: metal particles such as nickel, iron, copper, aluminum, tin, lead, chromium, cobalt, silver, and gold; alloy particles of these metals; coated particles obtained by coating the surfaces of particles such as metal oxides, carbon, graphite, glass, ceramics, and resins with a metal. In the case of using metal-coated resin particles obtained by coating the surface of resin particles with a metal, examples of the material of the resin particles include: epoxy resin, phenolic resin, acrylic resin, acrylonitrile / styrene (AS) resin, benzoguanamine resin, divinylbenzene-based resin, styrene-based resin, and the like. It should be noted that the conductive particles may also be conductive particles subjected to an insulation treatment as long as they do not affect the conduction performance after connection. In order to avoid the risk of short circuit between terminals, the insulation treatment is to further coat an insulating film on the surface of the above particles or attach insulating particles on the surface, etc. These conductive particles can be used alone or in combination of two or more.

[0123] There is no particular limitation on the average particle size of the conductive particles, which can be appropriately determined according to the purpose. It is preferably 40 μm or less, more preferably 30 μm or less, further preferably 25 μm or less, and still more preferably 20 μm or less. There is no particular limitation on the lower limit of the average particle size, and it is preferably 1 μm or more, more preferably 2 μm or more, and further preferably 3 μm or more. The average particle size of the conductive particles can be observed, for example, by scanning electron microscopy (SEM). The particle sizes of a plurality of (n≥10) conductive particles are measured, and their average value is calculated. Alternatively, it can be a measured value (N = 1000 or more) obtained by using an image-type particle size distribution measuring device (for example, FPIA-3000 (Malvern)).

[0124] When using conductive particles, there is no particular limitation on the content of the conductive particles in the adhesive composition, which can be appropriately determined according to the purpose. It is preferably 1% by mass or more, more preferably 2% by mass or more, and further preferably 3% by mass or more. From the viewpoint of obtaining the desired anisotropic conductivity, the upper limit of this content is preferably 30% by mass or less, more preferably 30% by mass or less, further preferably 25% by mass or less, and still more preferably 20% by mass or less.

[0125] The adhesive composition of the present invention may further contain other components as needed. Examples of the above components include: fillers that do not inhibit conduction, such as organic filler materials (for example, butadiene-based rubber particles, acrylic-based rubber particles, silicone-based rubber particles), insulating inorganic fillers (for example, silica fillers); known additives used in the manufacture of adhesive compositions, such as surface modifiers, flame retardants, coupling agents, and colorants.

[0126] Even when the adhesive composition of the present invention is stored for a certain period at normal temperature / refrigerated environment, it can suppress the decrease in adhesiveness, and at the same time, excellent adhesiveness can be achieved under the same bonding conditions as in the case of using a sulfonium salt-based thermal acid generator. Therefore, the adhesive composition of the present invention is suitable as a means for bonding electronic components and the like. In addition, when containing conductive particles, it can be used as a conductive paste or an anisotropic conductive paste.

[0127] [Adhesive film]

[0128] The adhesive composition of the present invention has good film-forming properties and can be suitably formed into a film-like material (adhesive film). The present invention also provides the above-mentioned adhesive film, which is characterized by being composed of the adhesive composition of the present invention.

[0129] The adhesive film of the present invention can be composed of a single layer or multiple layers. In the case of being composed of multiple layers, the adhesive film of the present invention at least includes: a first adhesive layer composed of the adhesive composition of the present invention and a second adhesive layer composed of the adhesive composition of the present invention provided on the first adhesive layer. Preferably, one of the first adhesive layer and the second adhesive layer contains conductive particles. Therefore, in one embodiment, the adhesive film of the present invention at least includes: a first adhesive layer composed of the adhesive composition of the present invention and a second adhesive layer composed of the adhesive composition of the present invention provided on the first adhesive layer, and one of the first adhesive layer and the second adhesive layer contains conductive particles. In addition, a layer different from the present invention can be provided on the adhesive layer of the present invention. The front and back of this layer can also be clamped by the adhesive layers of the present invention. At this time, the conductive particles can be contained in at least any one layer of the adhesive layers of the present invention, or can be contained in different layers. This different layer can be a layer composed of an adhesive composition different from the present invention, or a resin layer that is a non-adhesive layer (not contributing to adhesion). Preferably, it is insulating. As long as it can be bonded, there is no particular limitation even if it contains different layers.

[0130] The adhesive film can be manufactured in the following manner: for example, after mixing the adhesive composition of the present invention with an organic solvent as needed, it is coated on a release substrate and further dried to form an adhesive layer, thereby manufacturing it. The coating of the adhesive composition can be carried out using a coating device such as a bar coater. Known coating methods for adhesive films such as the doctor blade method can be used. In the case of manufacturing an adhesive film composed of multiple layers, the above-mentioned coating and drying processes can be repeatedly carried out multiple times. Or, they can be separately manufactured and laminated using lamination or the like.

[0131] The release substrate may be any film-like material that can support the adhesive film and can be peeled from the adhesive film at the desired timing, and is not particularly limited. As the material of the release substrate, for example, plastics materials such as polyesters such as polyethylene terephthalate (PET), polyolefins such as polypropylene (PP), poly-4-methylpentene-1 (PMP), and polytetrafluoroethylene (PTFE) can be used. The release substrate may also be a substrate having a release layer on the surface on the side joined to the adhesive film, and the release layer may contain a release agent such as a silicone resin or a polyolefin resin, for example.

[0132] There is no particular limitation on the thickness of the release substrate, and it is preferably 100 μm or less, more preferably 80 μm or less, further preferably 60 μm or less, and even more preferably 50 μm or less. There is no particular limitation on the lower limit of the thickness of the release substrate, and from the viewpoint of workability during slit processing when manufacturing the adhesive film, it is preferably 8 μm or more.

[0133] There is no particular limitation on the thickness of the adhesive film of the present invention, and it can be appropriately determined according to the purpose. It is preferably 1 μm or more, more preferably 3 μm or more, and further preferably 5 μm or more. There is no particular limitation on the upper limit of the thickness of the adhesive layer, and it is preferably 100 μm or less, more preferably 80 μm or less, further preferably 60 μm or less, even more preferably 50 μm or less, and particularly preferably 40 μm or less. In the case of laminating multiple layers, the thickness of the adhesive layer is the total thickness.

[0134] The adhesive film can be slit processed to have a desired width. When performing slit processing, in order to prevent contamination of the adhesive layer by cutting debris or the like, a cover film can be provided on its exposed surface. The thickness in this case can be appropriately selected according to the purpose. As the cover film, a known film used in the slit processing of the adhesive film can be used. As a product that is also used for connection purposes in addition to manufacturing processes such as slits, in order to prevent contamination during use, the cover film can also be provided separately from the release substrate. In this case, the cover film is preferably peelable, and the thickness is preferably the same as or thinner than the release substrate.

[0135] Even when the adhesive film of the present invention is stored in a normal temperature / refrigerated environment for a certain period, a decrease in adhesiveness can be suppressed, and excellent adhesiveness can be achieved under the same adhesion conditions as in the case of using a sulfonium salt-based thermal acid generator. Therefore, the adhesive film of the present invention can be suitably used as a means for bonding electronic components and the like. In addition, when containing conductive particles, it can be used as an anisotropic conductive film.

[0136] [Connection structure]

[0137] Using the adhesive composition or adhesive film of the present invention, a connection structure for bonding electronic components to each other can be manufactured. The present invention also provides the above-mentioned connection structure, which is characterized in that the first electronic component and the second electronic component are connected by the adhesive composition or the adhesive film of the present invention.

[0138] As the first electronic component, for example, it can be a general PWB, and examples include: rigid substrates, glass substrates, ceramic substrates, plastic substrates, FPCs, etc. In addition, as the second electronic component, examples include: FPCs, IC chips, semiconductor components other than IC chips, etc. There is no particular limitation on the electronic components, nor is there any particular limitation on the use of the connection structure. For example, it can be used in mobile information terminals and can also be used in in-vehicle electrical installations. In the present invention, as an example, a multi-purpose connection structure such as FOB, FOG, FOP, FOF, COG, COP, etc. can be manufactured. In particular, it is preferably applied to FOG and FOP.

[0139] [Manufacturing method of the connection structure]

[0140] The manufacturing method of the connection structure of the present invention is not particularly limited as long as it can manufacture a connection structure in which the first electronic component and the second electronic component are connected by the adhesive composition or the adhesive film of the present invention. Hereinafter, an example of the method for manufacturing the connection structure of the present invention is given.

[0141] In one embodiment, the manufacturing method of the connection structure of the present invention includes the following steps: crimping the first electronic component and the second electronic component via the adhesive composition or the adhesive film of the present invention.

[0142] First, place the first electronic component on a platform, set the adhesive composition or the adhesive film of the present invention thereon, and then place the second electronic component. Here, after setting the adhesive composition or the adhesive film of the present invention on the first electronic component placed on the platform, alignment is performed in such a manner that the electrodes of the first electronic component face the electrodes of the second electronic component, and temporary crimping is performed from the side of the second electronic component using a crimping tool. The temperature, pressure, and time during temporary crimping can be appropriately determined according to the specific design. For example, it can be set to 60 to 80 °C, 0.5 to 2 MPa, and 0.5 to 2 seconds. Before performing the subsequent formal crimping, by performing the above-mentioned temporary crimping, the electronic components can be more precisely aligned and connected to each other (the conduction parts of their respective components), which is more suitable. By performing temporary crimping, it is possible to expect to suppress the position shift during the formal crimping where extrusion is performed at a higher pressure.

[0143] After temporary crimping, a formal crimping is performed from the side of the second electronic component using a crimping tool. The temperature, pressure, and time during the formal crimping can be set to any known conditions used when bonding electronic components using an adhesive film, and can be appropriately determined according to the specific design. As described above, by using the adhesive film of the present invention that combines a quaternary ammonium salt-based thermal acid generator and a specific cationic polymerizable component, good adhesiveness can be achieved under the previous bonding conditions using a sulfonium salt-based thermal acid generator. For example, even for crimping at a low temperature (e.g., 200 °C or lower, 180 °C or lower, 160 °C or lower) and for a short time (e.g., 10 seconds or shorter, 8 seconds or shorter, 6 seconds or shorter), the first electronic component and the second electronic component can be bonded well.

[0144] It should be noted that a buffer material (such as a buffer sheet) can be provided between the second electronic component and the crimping tool, whether it is temporary crimping or formal crimping. Regarding the buffer material and whether to use it, it can be appropriately adjusted and determined according to the combination of electronic components.

[0145] The adhesive composition or adhesive film of the present invention that combines a quaternary ammonium salt-based thermal acid generator and a specific cationic polymerizable component can suppress the decrease in adhesiveness even when stored in a normal temperature / refrigerated environment for a certain period. For example, in the case of bonding under the bonding conditions of 160 °C, 3 MPa, and 5 seconds, for the connection structure of an FPC and a glass substrate manufactured using the adhesive composition or adhesive film of the present invention, whether using the adhesive composition (adhesive film) just after manufacturing or the adhesive composition (adhesive film) stored in a normal temperature / refrigerated environment for a certain period, a bonding strength of 7 N / cm or more can be exhibited in a 90-degree peel test. Examples

[0146] Hereinafter, examples of the present invention will be specifically described. However, the present invention is not limited to the examples shown below. In the following description, "parts" and "%" representing amounts refer to "parts by mass" and "mass %", respectively, unless otherwise specified.

[0147] [Example 1]

[0148] - Preparation of Adhesive Composition -

[0149] 17.4 parts of bisphenol F type epoxy resin (trade name: jER4007P, manufactured by Mitsubishi Chemical Corporation), 26.1 parts of phenoxy resin (trade name: YP-50, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., Mw = 60,000), 8.7 parts of polyvinyl acetal resin (trade name: KS-10, manufactured by Sekisui Chemical Co., Ltd.), 13.0 parts of a bifunctional alicyclic epoxy compound (trade name: Celloxide 2021P, manufactured by Daicel Corporation, a compound represented by the following formula (i)), 10.9 parts of a tetrafunctional alicyclic epoxy compound (trade name: KR-470, manufactured by Shin-Etsu Chemical Co., Ltd., a compound represented by the following formula (ii)), 2.6 parts of a quaternary ammonium salt-based thermal acid generator (trade name: CXC-1612, manufactured by Kusumoto Chemicals, Ltd.), 5.7 parts of conductive particles (trade name: Micropearl, manufactured by Sekisui Chemical Co., Ltd., Ni resin particles with an average particle diameter of 4 μm), 13.0 parts of a butadiene-based rubber (trade name: RKB-5515, manufactured by Resinous Kasei Co., Ltd.), 2.6 parts of a silane coupling agent (trade name: A187, manufactured by Toray Dow Corning Co., Ltd.), and PMA as a solvent were added so that the solid content of the whole became 43.38%, and they were uniformly mixed to obtain an adhesive composition.

[0150] [Chemical formula 6]

[0151]

[0152] [Chemical formula 7]

[0153]

[0154] -Fabrication of Adhesive Film-

[0155] As a release substrate, a PET film (thickness: 50 μm) was prepared. The adhesive composition was uniformly coated on the release substrate so that the thickness of the dried adhesive film (adhesive layer) became 18 μm. Then, it was dried in an oven at 70°C for 5 minutes to form an adhesive layer on the release substrate. Then, at 45°C, a cover film was laminated to the exposed surface of the adhesive layer.

[0156] [Reference Example 1] (Conventional System of Bifunctional Alicyclic Epoxy Compound + Sulfonium Salt-Based Thermal Acid Generator)

[0157] Use 2.6 parts of a sulfonium salt-based thermal acid generator (trade name: SI-60L, manufactured by Sanshin Chemical Industry Co., Ltd.) to replace 2.6 parts of a quaternary ammonium salt-based thermal acid generator (trade name: CXC-1612, manufactured by Kusumoto Chemicals, Ltd.), and use only a difunctional alicyclic epoxy compound (trade name: Celloxide 2021P, manufactured by Daicel Corporation) in the amounts shown in Table 1 as the cationic polymerizable component. Otherwise, operate in the same manner as in Example 1 to prepare an adhesive composition and produce an adhesive film.

[0158] [Comparative Example 1] (System of difunctional alicyclic epoxy compound + quaternary ammonium salt-based thermal acid generator)

[0159] Use only 23.9 parts of a difunctional alicyclic epoxy compound (trade name: Celloxide 2021P, manufactured by Daicel Corporation) as the cationic polymerizable component. Otherwise, operate in the same manner as in Example 1 to prepare an adhesive composition and produce an adhesive film.

[0160] [Comparative Example 2] (Conventional system of difunctional alicyclic epoxy compound + sulfonium salt-based thermal acid generator)

[0161] Use 2.5 parts of a sulfonium salt-based thermal acid generator (trade name: SI-60L, manufactured by Sanshin Chemical Industry Co., Ltd.) to replace 2.6 parts of a quaternary ammonium salt-based thermal acid generator (trade name: CXC-1612, manufactured by Kusumoto Chemicals, Ltd.), and use only a difunctional alicyclic epoxy compound (trade name: Celloxide 2021P, manufactured by Daicel Corporation) as the cationic polymerizable component, and the blending amounts of each component are as shown in Table 1. Otherwise, operate in the same manner as in Example 1 to prepare an adhesive composition and produce an adhesive film.

[0162] [Examples 2 - 6] (Effect of 4-functional / 2-functional mass ratio)

[0163] Change the amount ratio of the difunctional alicyclic epoxy compound to the tetrafunctional alicyclic epoxy compound as shown in Table 2. Otherwise, operate in the same manner as in Example 1 to prepare an adhesive composition and produce an adhesive film.

[0164] [Examples 7 - 11] (Effect of thiol compound)

[0165] The 4-functional thiol compound (trade name: Karenz MT PE1, manufactured by Showa Denko K.K., the compound represented by the following formula (iii)), 3-functional thiol compound (trade name: Karenz MT NR1, manufactured by Showa Denko K.K., the compound represented by the following formula (iv)), or 2-functional thiol compound (trade name: Karenz MT BD1, manufactured by Showa Denko K.K., the compound represented by the following formula (v)) was further added in the amounts shown in Table 3. Other than that, the operation was carried out in the same manner as in Example 1 to prepare an adhesive composition, and an adhesive film was produced.

[0166] [Chemical formula 8]

[0167]

[0168] [Chemical formula 9]

[0169]

[0170] [Chemical formula 10]

[0171]

[0172] [Comparative Example 3] (Effect of thiol compound on conventional system)

[0173] 0.4 part of a 4-functional thiol compound (trade name: Karenz MT PE1, manufactured by Showa Denko K.K.) was further added. Other than that, the operation was carried out in the same manner as in Reference Example 1 to prepare an adhesive composition, and an adhesive film was produced.

[0174] [Examples 12 to 15] (Effect of composition of film-forming components - phenoxy resin Mw -)

[0175] Except for using a phenoxy resin (trade name: YP-50, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., Mw = 60,000) and using a phenoxy resin (trade name: jER4210, manufactured by Mitsubishi Chemical Corporation, Mw = 30,000) in the amounts shown in Table 3, or using a phenoxy resin (trade name: jER4210, manufactured by Mitsubishi Chemical Corporation, Mw = 30,000) to replace the phenoxy resin (trade name: YP-50, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., Mw = 60,000), other than that, the operation was carried out in the same manner as in Example 1 to prepare an adhesive composition, and an adhesive film was produced.

[0176] [Example 16] (Effect of composition of film-forming components - without polyvinyl acetal resin -)

[0177] The polyvinyl acetal resin (trade name: KS-10, manufactured by Sekisui Chemical Co., Ltd.) was not used, and otherwise, the operation was carried out in the same manner as in Example 1 to prepare an adhesive composition and produce an adhesive film.

[0178] [Example 17] (System without conductive particles)

[0179] The conductive particles (trade name: Micropearl, manufactured by Sekisui Chemical Co., Ltd., Ni resin particles with an average particle diameter of 4 μm) were not used, and otherwise, the operation was carried out in the same manner as in Example 1 to prepare an adhesive composition and produce an adhesive film.

[0180] Hereinafter, the test / evaluation method will be described.

[0181] <Evaluation of adhesive strength>

[0182] -Fabrication of connection structure-

[0183] After the adhesive films produced in the examples and comparative examples were slit-processed to a width of 1.0 mm, the cover film was peeled off. Then, the adhesive film was attached to the edge of a glass substrate (thickness 0.7 mm) in such a way that the exposed surface of the adhesive layer was joined, and a force was uniformly applied on a hot plate at 45°C. After that, the release substrate was peeled off, and the gold wiring portion of a flexible printed circuit board (FPC; thickness 50 μm) was connected and attached in such a way that the exposed surface of the adhesive layer was completely covered. The FPC and the glass substrate were thermocompression-bonded via the adhesive layer, and all the conduction portions facing each other between the FPC and the glass substrate were bonded by the cured product of the adhesive layer, thereby obtaining the connected connection structure. The conditions for thermocompression bonding were 160°C, 3 MPa, and 5 seconds.

[0184] The connection structure was fabricated using the following respective adhesive films: (1) the adhesive film just after fabrication (initial stage), (2) the adhesive film after being stored for 14 days in a normal temperature environment of 25°C and 65% RH after fabrication, and (3) the adhesive film after being stored for 1 month in a refrigerated environment of 5°C after fabrication.

[0185] -Measurement / evaluation of adhesive strength-

[0186] For the obtained connection structure, the adhesive strength was measured by a 90-degree peel test. Specifically, the FPC and the cured product were cut to a length of 10 mm, the 10-mm-long FPC was clamped by a jig, and the FPC was peeled off the glass substrate in the vertical direction at a speed of 50 mm / minute at room temperature (25°C), and the load (N / cm) applied until peeling was measured. It should be noted that a Tensilon testing machine (manufactured by Orientec Co., Ltd.: STA-1150) was used in the measurement.

[0187] <Evaluation of On-Resistance>

[0188] -Fabrication of Connection Structure-

[0189] After the adhesive films in the examples and comparative examples were just fabricated, slit processing was performed to make the width 1.0 mm, and then the cover film was peeled off. Then, the adhesive film was attached to the edge of the ITO glass substrate (thickness 0.7 mm) in such a way that the exposed surface of the adhesive layer was joined to the ITO glass substrate, and force was uniformly applied on a hot plate at 45°C. After that, the release substrate was peeled off, and the gold wiring portion of the FPC (thickness 50 μm) was connected and attached in such a way that the exposed surface of the adhesive layer was completely covered. The FPC and the ITO glass substrate were thermocompression bonded via the adhesive layer to obtain a connection structure. The conditions for thermocompression bonding were 160°C, 3 MPa, and 5 seconds.

[0190] -Measurement / Evaluation of On-Resistance-

[0191] For the obtained connection structure, the on-resistance was measured just after bonding and after being kept under high-temperature and high-humidity conditions of 110°C and 85% RH for 32 hours, and evaluation was performed according to the following criteria. It should be noted that for Example 17 which does not contain conductive particles, this evaluation was not performed.

[0192] Regarding the initial on-resistance, it was set as an index for performance comparison rather than an evaluation criterion for practical applications. It should be noted that in the reliability test, if the evaluation is B or above, there is no problem in practical applications, and an A evaluation is preferred.

[0193] Initial (Evaluation Criterion)

[0194] A: Less than 0.5 Ω;

[0195] B: 0.5 Ω or more and less than 1.0 Ω;

[0196] C: 1.0 Ω or more.

[0197] After Reliability Test (Evaluation Criterion)

[0198] A: Less than 1.0 Ω;

[0199] B: 1.0 Ω or more and less than 5.0 Ω;

[0200] C: 5.0 Ω or more.

[0201] The evaluation results of the examples and comparative examples are shown in Tables 1 to 3.

[0202] [Table 1]

[0203]

[0204] [Table 2]

[0205]

[0206] [Table 3]

[0207]

[0208] The results in Table 1 (comparison between Comparative Example 1 and Reference Example 1) show that when a quaternary ammonium salt thermal acid generator is used instead of a sulfonium salt thermal acid generator, the original bonding strength decreases under the same bonding conditions as when a sulfonium salt thermal acid generator is used.

[0209] In addition, from the results of Table 1 (comparison of Example 1 and Comparative Example 1), it can be seen that in the combination with the quaternary ammonium salt thermal acid generator, if a bifunctional alicyclic epoxy compound and a tetrafunctional alicyclic epoxy compound are used as free radical polymerizable components, not only the decrease in adhesion caused by storage under normal temperature / refrigerated environment is suppressed, but also the bonding strength is significantly improved even under the same bonding conditions as the case of using a sulfonium salt thermal acid generator. It should be noted that in Comparative Example 1, it was confirmed that if the entire amount of the bifunctional alicyclic epoxy compound as a cationic polymerizable component was replaced with a tetrafunctional alicyclic epoxy compound (that is, if a tetrafunctional alicyclic epoxy compound was used alone as a cationic polymerizable component), the original adhesive layer would not be attached to the glass substrate.

[0210] From the results of Table 2, it can be seen that if the 4-functional / 2-functional mass ratio is in the range of 0.1 to 0.85, excellent bonding strength is exhibited. In addition, it is confirmed that if the 4-functional / 2-functional mass ratio is in the range of 0.1 to 0.85, even after the reliability test under a high temperature and high humidity environment, the generation of bulges at the connection part of the connection structure can be significantly suppressed. Moreover, it can be seen that if the 4-functional / 2-functional mass ratio is in the range of 0.1 to 0.4, significantly excellent bonding strength is achieved.

[0211] From the results in Table 3 (comparison of Examples 7 to 11 with Comparative Example 3), it can be seen that in the case of an adhesive composition using a sulfonium salt-based thermal acid generator, even though a thiol compound was added, not only was the bonding strength not improved, but the bonding strength was reduced. In contrast, it can be seen that in the adhesive composition of the present invention using a quaternary ammonium salt-based thermal acid generator in combination with a specific cationic polymerizable component (a combination system of a bifunctional alicyclic epoxy compound and a tetrafunctional alicyclic epoxy compound), the bonding strength is dramatically improved by further including a thiol compound.

[0212] In addition, from the results in Table 3 (Examples 12 to 16 (compared with Example 1)), it can be seen that even when the composition of the film-forming component is changed, good adhesive strength is exhibited under the same bonding conditions as in the case of using a sulfonium salt-based thermal acid generator. In addition, it was confirmed that when a phenoxy resin with Mw of 30,000 is included as the film-forming component, even after a reliability test in a high-temperature and high-humidity environment, the generation of bulges at the connection part of the connection structure can be significantly suppressed.

[0213] Moreover, from the results in Table 3 (Example 17), it can be seen that even when conductive particles are not added, good adhesive strength is exhibited under the same bonding conditions as in the case of using a sulfonium salt-based thermal acid generator.

[0214] It should be noted that for the initial conduction and the conduction after the reliability test, all examples showed values that are not problematic in practical applications.

Claims

1. A pressure-sensitive adhesive film composed of a pressure-sensitive adhesive composition, which is a film-like material peelable from a release substrate, and the pressure-sensitive adhesive composition contains an adhesive composition and a cationic polymerization initiator. The adhesive composition contains a cationically polymerizable component and a film-forming component. The film-forming component does not include alicyclic epoxy resins, and the weight-average molecular weight Mw of the film-forming component in terms of polystyrene is 10,000 or more and 80,000 or less. The cationic polymerization initiator is a quaternary ammonium salt-based thermoacid generator. The cationically polymerizable component contains a bifunctional alicyclic epoxy compound and a tetrafunctional alicyclic epoxy compound. Among them, The tetrafunctional alicyclic epoxy compound contains a tetrafunctional alicyclic epoxy compound containing a structural unit represented by formula (1). [Chemical formula 1] In the formula, R 1 represents a monovalent organic group having an epoxy C 3 ~C 10 cycloalkyl group, R 2 represents a hydrogen atom, a hydrocarbon group or an alkoxy group, The mass ratio of the tetrafunctional alicyclic epoxy compound to the bifunctional alicyclic epoxy compound [tetrafunctional alicyclic epoxy compound / bifunctional alicyclic epoxy compound] is 0.1 or more and 0.85 or less.

2. The pressure-sensitive adhesive film according to claim 1. Among them, The 2-functional alicyclic epoxy compound has epoxy C 3 ~C 10 cycloalkyl group.

3. The pressure-sensitive adhesive film according to claim 1. Among them, The tetrafunctional alicyclic epoxy compound containing the structural unit represented by formula (1) has 4 structural units represented by formula (1) in one molecule.

4. The pressure-sensitive adhesive film according to claim 1. Among them, The pressure-sensitive adhesive composition further contains a thiol compound.

5. The pressure-sensitive adhesive film according to claim 4. Among them, The thiol compound contains the same number of carbonyloxy groups as the mercapto groups in one molecule.

6. The pressure-sensitive adhesive film according to claim 4. Among them, The functional number of the thiol compound is 2 or more.

7. The pressure-sensitive adhesive film according to claim 4. Among them, The thiol compound contains a structural unit represented by formula (2). [Chemical formula 2] 8. The pressure-sensitive adhesive film according to claim 4. Among them, The mass ratio of the thiol compound to the quaternary ammonium salt-based thermoacid generator [thiol compound / quaternary ammonium salt-based thermoacid generator] is 0.1 or more.

9. The pressure-sensitive adhesive film according to claim 1. Among them, When the non-volatile components in the pressure-sensitive adhesive composition are set to 100% by mass, the total content of the bifunctional alicyclic epoxy compound and the tetrafunctional alicyclic epoxy compound is 10% by mass or more and 60% by mass or less.

10. The pressure-sensitive adhesive film according to claim 1. Among them, When the non-volatile components in the pressure-sensitive adhesive composition are set to 100% by mass, the content of the film-forming component is 10% by mass or more and 70% by mass or less.

11. The pressure-sensitive adhesive film according to claim 1. Among them, The film-forming component is one or more selected from phenoxy resins, epoxy resins other than alicyclic epoxy resins, polyvinyl acetal resins, unsaturated polyester resins, saturated polyester resins, urethane resins, butadiene resins, polyimide resins, polyamide resins, and polyolefin resins.

12. The pressure-sensitive adhesive film according to any one of claims 1 to 11. Among them, The pressure-sensitive adhesive composition further contains conductive particles.

13. A pressure-sensitive adhesive composition, which is a pressure-sensitive adhesive composition containing an adhesive composition and a cationic polymerization initiator. The adhesive composition contains a cationically polymerizable component and a film-forming component. The film-forming component does not include an alicyclic epoxy resin, and the weight-average molecular weight Mw in terms of polystyrene of the film-forming component is 10,000 or more and 80,000 or less. The cationic polymerization initiator is a quaternary ammonium salt-based thermal acid generator. The cationic polymerizable component contains a bifunctional alicyclic epoxy compound and a tetrafunctional alicyclic epoxy compound. Among them, The tetrafunctional alicyclic epoxy compound contains a tetrafunctional alicyclic epoxy compound including the structural unit represented by formula (1). [Chemical formula 1] In the formula, R 1 represents a monovalent organic group having an epoxy C 3 to C 10 cycloalkyl group, R 2 represents a hydrogen atom, a hydrocarbon group or an alkoxy group, Among them, the mass ratio of the tetrafunctional alicyclic epoxy compound to the bifunctional alicyclic epoxy compound [tetrafunctional alicyclic epoxy compound / bifunctional alicyclic epoxy compound] is 0.1 or more and 0.85 or less.

14. The adhesive composition according to claim 13, Among them, The 2-functional alicyclic epoxy compound has an epoxy C 3 ~C 10 cycloalkyl group.

15. The adhesive composition according to claim 13, Among them, The tetrafunctional alicyclic epoxy compound containing the structural unit represented by formula (1) has 4 structural units represented by formula (1) in 1 molecule.

16. The adhesive composition according to claim 13, which further contains a thiol compound.

17. The adhesive composition according to claim 16, Among them, The thiol compound contains the same number of carbonyloxy groups as the number of mercapto groups in 1 molecule.

18. The adhesive composition according to claim 16, Among them, The functional number of the thiol compound is 2 or more.

19. The adhesive composition according to claim 16, Among them, The thiol compound contains the structural unit represented by formula (2). [Chemical formula 2] 20. The adhesive composition according to claim 16, Among them, The mass ratio of the thiol compound to the quaternary ammonium salt-based thermal acid generator [thiol compound / quaternary ammonium salt-based thermal acid generator] is 0.1 or more.

21. The adhesive composition according to claim 13, Among them, When the non-volatile components in the adhesive composition are set to 100% by mass, the total content of the bifunctional alicyclic epoxy compound and the tetrafunctional alicyclic epoxy compound is 10% by mass or more and 60% by mass or less.

22. The adhesive composition according to claim 13, Among them, When the non-volatile components in the adhesive composition are set to 100% by mass, the content of the film-forming component is 10% by mass or more and 70% by mass or less.

23. The adhesive composition according to claim 13, Among them, The film-forming component is one or more selected from phenoxy resin, epoxy resin other than alicyclic epoxy resin, polyvinyl acetal resin, unsaturated polyester resin, saturated polyester resin, urethane resin, butadiene resin, polyimide resin, polyamide resin, and polyolefin resin.

24. The adhesive composition according to any one of claims 13 to 23, which further contains conductive particles.

25. An adhesive film, which is composed of the adhesive composition according to any one of claims 13 to 24.

26. A connection structure, which is formed by connecting a first electronic component and a second electronic component through the adhesive composition according to any one of claims 13 to 24 or the adhesive film according to any one of claims 1 to 12 and 25.

27. A method for manufacturing a connection structure, comprising the following steps: pressing a first electronic component and a second electronic component via the adhesive composition according to any one of claims 13 to 24 or the adhesive film according to any one of claims 1 to 12, 25.

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