CN119242209A

CN119242209A - Adhesive composition, connection structure and method for producing the same

Info

Publication number: CN119242209A
Application number: CN202411361143.5A
Authority: CN
Inventors: 筱原研吾; 川端泰典; 立泽贵; 坂野和惠
Original assignee: Resonac Corp
Current assignee: Resonac Corp
Priority date: 2018-01-17
Filing date: 2019-01-15
Publication date: 2025-01-03
Also published as: TW202430608A; JP7294145B2; CN111601867A; TWI842693B; KR102781086B1; WO2019142791A1; KR20200108439A; TW201934705A; TWI868003B; KR20250039505A; JPWO2019142791A1

Abstract

The present invention relates to an adhesive composition, a connection structure and a method for manufacturing the same. One aspect of the present invention provides an adhesive composition comprising conductive particles and an adhesive component, wherein the adhesive component comprises a compound having a nitrogen-containing aromatic heterocycle, wherein the adhesive component comprises a radical polymerizable substance, and wherein the radical polymerizable substance comprises urethane acrylate or urethane methacrylate.

Description

Adhesive composition, connection structure, and method for producing same

The present invention is a divisional application of the invention application having application number 201980007769.7 (international application number PCT/JP 2019/000954), application date 2019, 1-15, and the name "adhesive composition, connection structure, and method of manufacturing the same".

Technical Field

The invention relates to an adhesive composition, a connection structure and a method for manufacturing the same.

Background

In recent years, miniaturization, thinning, and higher performance of electronic components have been advanced, and at the same time, development of economical high-density mounting techniques has been actively advanced. It is difficult to connect an electronic component having a fine circuit electrode to a circuit member by a conventional solder and rubber connector. Accordingly, an adhesive composition and a method for connecting films (adhesive films) using an anisotropic conductive adhesive composition having excellent decomposability as disclosed in patent documents 1 to 6 are often used. For example, when a glass of a Liquid crystal display (Liquid CRYSTAL DISPLAY) is connected to a circuit member such as TAB (Tape Automated Bonding ) or FPC (Flexible Print Circuit, flexible printed circuit board), an anisotropic conductive adhesive film containing conductive particles is sandwiched between opposing electrodes and heated and pressed, whereby electrodes of both substrates are electrically connected to each other while maintaining the insulation between adjacent electrodes on the same substrate, and an electronic component having a fine circuit electrode is pressure-bonded to the circuit member and fixed.

In addition, a reduction in weight, a reduction in thickness, and a high sensitivity of a module are demanded, and in a display module such as a liquid crystal display device and an electronic paper, or a sensor substrate such as a touch panel, copper, gold, aluminum, or an alloy thereof having a low surface resistance is required to be used as an electrode instead of a conventional silver paste in order to reduce wiring resistance, thereby narrowing the width of the wiring and reducing wiring resistance. In the anisotropic conductive adhesive film, studies have also been made to optimize the raw materials and the like contained in the adhesive film for the purpose of reducing the connection resistance.

Prior art literature

Patent literature

Patent document 1 Japanese patent laid-open No. 08-148213

Patent document 2 Japanese patent laid-open No. 08-124613

Patent document 3 Japanese patent laid-open No. 11-50032

Patent document 4 Japanese patent application laid-open No. 2011-91044

Patent document 5 Japanese patent application laid-open No. 2011-100605

Patent document 6 Japanese patent application laid-open No. 2013-55058

Disclosure of Invention

Problems to be solved by the invention

Among the metals having low surface resistance, studies have been conducted for using easily available copper, copper alloys, copper oxides, and the like for electrodes. However, when a conventional adhesive film is applied to such an electrode, for example, the connection resistance may increase with time, and there is room for further improvement in connection reliability.

Accordingly, an object of the present invention is to provide an adhesive composition capable of suppressing an increase in connection resistance and improving connection reliability. The present invention also aims to provide a connection structure having excellent connection reliability and a method for manufacturing the same.

Means for solving the problems

One aspect of the present invention is an adhesive composition containing conductive particles and a compound having a nitrogen-containing aromatic heterocycle.

The nitrogen-containing aromatic heterocycle is preferably selected from the group consisting of pyrazole ring, imidazole ring, triazole ring, tetrazole ring, thiazole ring, thiadiazole ring,At least one of the group consisting of an azole ring and a pyrimidine ring. This can further improve the connection reliability.

The adhesive composition is preferably used to connect circuit members to each other.

Another aspect of the present invention is a connection structure including a first circuit member having a first substrate and a first electrode provided on the first substrate, a second circuit member having a second substrate and a second electrode provided on the second substrate, and a circuit connection member disposed between the first circuit member and the second circuit member and electrically connecting the first electrode and the second electrode to each other, wherein the circuit connection member is a cured product of the adhesive composition.

The first electrode and the second electrode are preferably copper, copper alloy, or copper oxide.

Another aspect of the present invention is a method for manufacturing a connection structure, including the steps of disposing the adhesive composition between a first circuit member having a first substrate and a first electrode provided on the first substrate and a second circuit member having a second substrate and a second electrode provided on the second substrate, and bonding the first circuit member and the second circuit member with the adhesive composition interposed therebetween to electrically connect the first circuit member and the second circuit member.

Effects of the invention

According to the present invention, an adhesive composition capable of suppressing an increase in connection resistance and improving connection reliability can be provided. The present invention can also provide a connection structure having excellent connection reliability and a method for manufacturing the same.

Drawings

Fig. 1 is a schematic cross-sectional view showing an adhesive film according to an embodiment.

Fig. 2 is a schematic cross-sectional view showing a method for manufacturing a connection structure according to an embodiment.

Fig. 3 is a schematic cross-sectional view showing a copper electrode film attached body used in the example.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

An adhesive composition according to one embodiment includes an adhesive component and conductive particles dispersed in the adhesive component. The binder component is defined as a nonvolatile component other than the conductive particles in the binder composition.

The conductive particles include, for example, polymer particles (plastic particles) such as polystyrene, and a metal layer covering the polymer particles. The polymer particles are preferably coated with a metal layer substantially throughout their surfaces, but a part of the polymer particle surfaces may be exposed without being coated with a metal layer within a range where the function as a circuit connecting material can be maintained. The polymer particles may be particles containing a polymer containing at least one monomer selected from styrene and divinylbenzene as a monomer unit.

The average particle diameter of the polymer particles may be preferably 1 μm or more, 40 μm or less, or 1 to 40 μm. From the viewpoint of high-density mounting, the average particle diameter of the polymer particles may be more preferably 30 μm or less, or may be 1 to 30 μm. The average particle diameter of the polymer particles may be more preferably 2 μm or more, or may be less than or equal to 20 μm, or may be 2 to 20 μm, from the viewpoint of more stably maintaining the connected state even when irregularities are formed on the surface of the electrode. The average particle diameter of the polymer particles can be obtained as an average value by observing the average particle diameter with a Scanning Electron Microscope (SEM) and measuring the particle diameters of 300 polymer particles.

The metal layer may be formed of various metals such as Ni, ni/Au, ni/Pd, cu, niB, ag, ru, and the like. The metal layer may be a thin film formed by plating, vapor deposition, sputtering, or the like.

The conductive particles may further have an insulating layer provided outside the metal layer and covering the metal layer from the viewpoint of improving the insulation property. The insulating layer may be a layer formed of an insulating material such as silicon dioxide or acrylic.

The conductive particles preferably have a surface on which a plurality of protrusions are formed. The conductive particles having the protrusions can be obtained by forming a metal layer on the surface of the polymer particles by metal plating, for example.

The content of the conductive particles is determined according to the fineness of the electrodes to be connected, and the like. For example, the content of the conductive particles may be 1 part by volume or more, 50 parts by volume or less, or 1 to 50 parts by volume relative to 100 parts by volume of the adhesive component. From the viewpoints of insulation and manufacturing cost, the content of the conductive particles may be more preferably 30 parts by volume or less, or 1 to 30 parts by volume, based on 100 parts by volume of the adhesive component.

In one embodiment, the adhesive component contains a radical polymerizable substance which has insulating properties and is cured by heat or light, a radical generator, and a compound having a nitrogen-containing aromatic heterocycle.

The radical polymerizable substance is a substance having a functional group that is polymerized by a radical, and examples thereof include an acrylate compound, a methacrylate compound, and a maleimide compound. The content of the radical polymerizable substance may be, for example, 50% by mass or more, 80% by mass or less, or 50 to 80% by mass based on the total amount of the binder component.

As the acrylate compound and the methacrylate compound, there may be mentioned, for example, urethane acrylate, urethane methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dimethylol tricyclodecane diacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, 2-hydroxy-1, 3-diacryloxypropane, 2-bis [4- (acryloyloxymethoxy) phenyl ] propane, 2-bis [4- (acryloyloxypolyethoxy) phenyl ] propane, dicyclopentenyl acrylate, tricyclodecyl acrylate, bis (acryloyloxyethyl) isocyanurate, epsilon-caprolactone-modified tris (acryloyloxyethyl) isocyanurate, and tris (acryloyloxyethyl) isocyanurate. The radical polymerizable substance may be used singly or in combination of two or more. From the viewpoint of adhesion, the radical polymerizable substance is preferably urethane acrylate or urethane methacrylate.

As the radical polymerizable material, it is particularly preferable to use a urethane acrylate or urethane methacrylate in combination with a radical polymerizable material which alone exhibits Tg of 100 ℃ or more when crosslinked with an organic peroxide, from the viewpoint of improving heat resistance. Such a radical polymerizable substance may be a compound having a dicyclopentenyl group and/or a tricyclodecyl group, and preferably a compound having a tricyclodecyl group.

The viscosity of the radical polymerizable substance at 25 ℃ may be 100000mpa·s or more, 1000000mpa·s or less, 100000 to 1000000mpa·s or less, preferably 500000mpa·s or less, 100000 to 500000mpa·s or less. The viscosity of the radically polymerizable material at 25℃can be measured using a commercially available E-type viscometer.

The radical generator is a compound that generates a radical by decomposition by heat or light, and is, for example, a peroxy compound or an azo compound. The free radical generator is appropriately selected according to the target ligation temperature, ligation time, pot life, and the like. The free radical generator may be, for example, one or more selected from benzoyl peroxide, diacyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, dialkyl peroxide and hydroperoxide. From the viewpoint of high reactivity and pot life, the free radical generator is preferably an organic peroxide compound having a half-life of 10 hours at a temperature of 40 ℃ or more and a half-life of 1 minute at a temperature of 180 ℃ or less. The content of the free radical generator may be, for example, 0.05 mass% or more, 15 mass% or less, or 0.05 to 15 mass% based on the total amount of the binder component. When the adhesive component contains a free radical generator, the free radical generator may be used in combination with a decomposition accelerator, an inhibitor, or the like.

The adhesive component of the present embodiment may further contain a polymerization inhibitor. The polymerization inhibitor may be hydroquinone compound, methyl ether hydroquinone compound, etc. The content of the polymerization inhibitor may be 0.05 mass% or more, 5 mass% or less, or 0.05 to 5 mass% based on the total amount of the binder components.

A compound having a nitrogen-containing aromatic heterocycle (hereinafter also simply referred to as "heterocyclic compound") is a compound having an aromatic heterocycle containing one or more nitrogen atoms in the ring. The nitrogen-containing aromatic heterocycle (hereinafter also simply referred to as "heterocycle") may be composed of at least two kinds of atoms, i.e., a carbon atom and a nitrogen atom, or may be composed of three or more kinds of atoms including other atoms such as a sulfur atom and an oxygen atom in addition to the carbon atom and the nitrogen atom. The heterocycle contains, for example, 1 to 4 nitrogen atoms, preferably 2 to 4 nitrogen atoms. In the case where the nitrogen atom contained in the heterocyclic ring is one, the heterocyclic ring preferably further contains the above-described other atoms in addition to the carbon atom and the nitrogen atom.

The heterocycle is preferably a compound having a 5-membered ring or a 6-membered ring, more preferably a compound having a 5-membered ring (azole). Examples of the 5-membered ring include a pyrazole ring, an imidazole ring, a triazole ring, a tetrazole ring, a thiazole ring, a thiadiazole ring,An azole ring, and the like. Examples of the 6-membered ring include pyrimidine ring and the like.

The heterocycle is preferably selected from the group consisting of pyrazole ring, imidazole ring, triazole ring, tetrazole ring, thiazole ring, thiadiazole ring, and the like, from the viewpoint of suppressing an increase in connection resistance and further improving connection reliability,At least one selected from the group consisting of an azole ring and a pyrimidine ring, more preferably a pyrazole ring, an imidazole ring, a triazole ring, a tetrazole ring, a thiazole ring, a thiadiazole ring, andAt least one selected from the group consisting of triazole rings, tetrazole rings, and thiadiazole rings is further preferable.

The heterocycle may be unsubstituted or substituted (the hydrogen atom bonded to the atom constituting the heterocycle is substituted). In the case where the heterocyclic ring has a substituent, the substituent may be a hydrocarbon group or an organic group containing a sulfur atom, an oxygen atom or the like. The hydrocarbon group may be an alkyl group or the like. The organic group containing a nitrogen atom may be an amino group or the like. The organic group containing a sulfur atom may be a mercapto group or the like.

The heterocyclic compound may have a nitrogen-containing aromatic heterocycle including a single ring, or may have a polycyclic ring in which an aromatic ring (for example, a substituted or unsubstituted benzene ring) composed of only a hydrocarbon is condensed with the nitrogen-containing aromatic heterocycle. Such polycyclic rings may be, for example, benzimidazole rings, benzotriazole rings, benzothiazole rings, and benzoAn azole ring, and the like.

Specifically, the heterocyclic compound may be 5-methyltetrazole, 5-amino-1H-tetrazole, 3-mercapto-1, 2, 4-triazole, benzotriazole, 2-aminopyrimidine, 5, 6-dimethylbenzimidazole, 2-amino-5-mercapto-1, 3, 4-thiadiazole, 2-mercaptopyrimidine, 2-mercaptobenzoOxazole, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole and the like.

From the viewpoint of suppressing an increase in connection resistance and further improving connection reliability, the content of the heterocyclic compound is preferably 0.01 part by volume or more, more preferably 0.1 part by volume or more, further preferably 0.2 part by volume or more, and further preferably 5 parts by volume or less, more preferably 2 parts by volume or less, further preferably 1 part by volume or less, relative to 100 parts by volume of the adhesive component.

In another embodiment, the adhesive component contains a thermosetting resin and the above-mentioned compound having a nitrogen-containing aromatic heterocycle.

Examples of the thermosetting resin include epoxy resin, cyanate resin, maleimide resin, allylnadimide resin, phenol resin, urea resin, alkyd resin, acrylic resin, unsaturated polyester resin, diallyl phthalate resin, silicone resin, resorcinol formaldehyde resin, xylene resin, furan resin, polyurethane resin, ketone resin, triallyl cyanurate resin, polyisocyanate resin, resin containing tris (2-hydroxyethyl) isocyanurate, resin containing triallyl trimellitate, thermosetting resin synthesized from cyclopentadiene, thermosetting resin obtained by trimerization of aromatic dicyandiamide, and the like. The thermosetting resin may be used singly or in combination of two or more. The content of the thermosetting resin may be, for example, 20 mass% or more, 50 mass% or less, or 20 to 50 mass% based on the total amount of the binder component.

In the case where the adhesive component contains a thermosetting resin, the adhesive component may further contain a curing agent. The curing agent may be, for example, a catalyst-type curing agent. The catalyst-type curing agent may be a hydrazide, boron trifluoride-amine complex, sulfonium salt, amine imide, diaminomaleonitrile, polyamine salt, dicyandiamide, or the like, or may be a modified product thereof. The curing agent may be a polyaddition type curing agent such as polyamine, polythiol, polyphenol, acid anhydride, etc. As the curing agent, a combination of an addition polymerization type curing agent and a catalyst type curing agent may be used. The curing agent may be used singly or in combination of two or more. The content of the curing agent may be 0.5 mass% or more, 15 mass% or less, or 0.5 to 15 mass% based on the total amount of the binder components.

The curing agent may be a polymer compound such as polyurethane or polyester, or a metal film such as Ni or Cu, or an inorganic compound such as calcium silicate, which is coated with the curing agent and microencapsulated. Such a curing agent is preferable because the usable time can be prolonged.

In another embodiment, the adhesive component contains the above-mentioned radical polymerizable substance, a radical generator, a thermosetting resin, and a compound having a nitrogen-containing aromatic heterocycle.

In this embodiment, the total of the content of the radical polymerizable substance and the content of the thermosetting resin may be 50% by mass or more, 80% by mass or less, or 50 to 80% by mass, based on the total amount of the binder component.

In each of the above embodiments, the adhesive component may further contain a filler such as silicone particles, a softener, an accelerator, an anti-aging agent, a colorant, a flame retardant, a thixotropic agent, a coupling agent, and the like.

The adhesive composition may be in the form of a paste, and from the viewpoint of handling, it is preferable that the adhesive composition be formed into a film. Fig. 1 is a schematic cross-sectional view showing a film-like adhesive composition (adhesive film) according to an embodiment. As shown in fig. 1, in one embodiment, the adhesive film 1 is composed of one layer including an adhesive component 2 and conductive particles 3 dispersed in the adhesive component 2. In one embodiment, the adhesive component 2 and the conductive particles 3 may be the adhesive component and the conductive particles. The thickness of the adhesive film 1 may be, for example, 10 μm or more, 50 μm or less, or 10 to 50 μm.

In the case where the adhesive composition is formed into a film shape, the adhesive component may contain an insulating resin other than the thermosetting resin in order to improve film formability. The insulating resin may be polystyrene, polyethylene, polyvinyl butyral, polyvinyl formal, polyimide, polyamide, polyvinyl chloride, polyphenylene ether, urea resin, phenoxy resin, polyimide resin, polyester urethane resin, or the like, or may be a high molecular weight phenoxy resin having a weight average molecular weight of 10000 or more as determined by High Performance Liquid Chromatography (HPLC) from the viewpoint of further improving connection reliability. The adhesive component may contain a substance obtained by modifying these resins with radical polymerizable functional groups, and may contain a mixture of these resins with a styrene resin or an acrylic resin in order to adjust melt viscosity or the like. In another embodiment, the adhesive component may contain rubber in order to improve film formability.

The adhesive film may have a multilayer structure. The adhesive film may have a two-layer structure including a layer containing conductive particles and a layer containing no conductive particles, or a three-layer structure including a layer containing conductive particles and layers containing no conductive particles provided on both sides thereof. A plurality of layers containing conductive particles may be provided in the adhesive film. The adhesive film having such a multilayer structure is suitable for connection at a narrow pitch because conductive particles can be efficiently arranged on the electrode. In view of the adhesiveness to the circuit members, the adhesive film may further have an adhesive layer exhibiting high adhesiveness to each circuit member to be connected.

The adhesive composition (adhesive film) described above can be suitably used as a material (circuit connecting material) for connecting circuit members to each other, and can be particularly suitably used as an anisotropic conductive adhesive composition (anisotropic conductive adhesive film) for connecting circuit members to each other.

Next, a method for manufacturing a connection structure using the adhesive film 1 will be described. Fig. 2 is a schematic cross-sectional view showing a method for manufacturing a connection structure according to an embodiment. First, as shown in fig. 2 (a), a first circuit member 6 having a first substrate 4 and a first electrode 5 provided on the first substrate 4, and a second circuit member 9 having a second substrate 7 and a second electrode 8 provided on the second substrate 7 are prepared.

Next, the first circuit member 6 and the second circuit member 9 are disposed so that the first electrode 5 and the second electrode 8 face each other, and the adhesive film 1 is disposed between the first circuit member 6 and the second circuit member 9.

Then, the adhesive film 1 is cured while pressing the whole in the directions of arrows a and B. The pressure during pressurization may be, for example, 1 to 10mpa with respect to the total connection area. The method of curing the adhesive film 1 may be a method using heat or a method using light irradiation in addition to heat. The heating may be performed at 100 to 170 ℃, for example. The pressurization and heating (light irradiation as needed) may be performed for, for example, 1 to 160 seconds. Thereby, the first circuit member 6 and the second circuit member 9 are pressure-bonded with the cured product of the adhesive composition constituting the adhesive film 1 interposed therebetween.

In the present embodiment, the adhesive film 1 is disposed between the first circuit member 6 and the second circuit member 9, and as another embodiment, a paste-like adhesive composition may be applied to the first circuit member 6 or the second circuit member 9, or both, instead of the adhesive film.

As shown in fig. 2 (b), the connection structure 11 according to one embodiment obtained in the above manner includes a first circuit member 6 having a first substrate 4 and a first electrode 5 provided on the first substrate 4, a second circuit member 9 having a second substrate 7 and a second electrode 8 provided on the second substrate 7, and a circuit connection member 10 disposed between the first circuit member 6 and the second circuit member 9 to electrically connect the first electrode 5 and the second electrode 8 to each other. The circuit connecting member 10 is composed of a cured product of an adhesive composition, and includes a cured product 12 of an adhesive component 2 and conductive particles 3 dispersed in the cured product 12. In the connection structure 11, the conductive particles 3 are interposed between the first electrode 5 and the second electrode 8, so that the first electrode 5 and the second electrode 8 are electrically connected to each other.

The first substrate 4 and the second substrate 7 may be the same or different from each other, and may be, for example, a flexible substrate including a thermoplastic resin, a glass substrate, or a composite substrate including a glass substrate and an insulating film provided on the glass substrate.

The flexible substrate may be, for example, an organic substrate formed of an organic material including at least one thermoplastic resin selected from Polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), and polyethylene naphthalate (PEN).

The flexible substrate may further have a modifying treatment film such as a hard coat layer and/or a protective film for improving optical and mechanical characteristics, which are formed on the surface of the organic substrate. In order to facilitate handling and transportation of the flexible substrate, a reinforcing material selected from glass materials, SUS, and the like may be bonded to the organic substrate.

The thickness of the flexible substrate may be preferably 10 μm or more, 200 μm or less, 10 to 200 μm or less, more preferably 125 μm or less, or 10 to 125 μm or less, from the viewpoint of securing strength as a film and bending easiness by the substrate alone.

If the conventional circuit connecting material is used, the electrodes on the flexible substrate may be broken or may be easily cracked due to heat and pressure for pressing the circuit members against each other. In addition, in order to suppress breakage of the electrodes, it is necessary to press-bond the circuit member under a lower temperature or lower stress condition with respect to connection of the electrodes, which makes it difficult to form a sufficient electrical connection. The adhesive film 1 of the present embodiment can have advantageous effects in these respects as compared with conventional materials.

The glass substrate may be formed of soda glass, quartz glass, or the like. From the viewpoint of preventing breakage due to stress from the outside, the substrate formed of these materials may be subjected to chemical strengthening treatment. The composite substrate may have a glass substrate, and an insulating film formed of polyimide or an organic or inorganic material colored for decoration provided on a surface of the glass substrate. In the composite substrate, the electrode may be formed on the insulating film.

As a combination of the first substrate 4 and the second substrate 7, more specifically, the first substrate 4 may be an IC chip or a flexible substrate including a thermoplastic resin, and the second substrate 7 may be a flexible substrate including a thermoplastic resin. Alternatively, the first substrate 4 may be an IC chip or a flexible substrate, and the second substrate 7 may be a glass substrate or a composite substrate. In other words, when the second substrate 7 is a flexible substrate, the first substrate 4 may be an IC chip or a flexible substrate. When the first substrate 4 is an IC chip and the second substrate 7 is a flexible substrate, the adhesive film 1 may be used for COP (Chip on Plastic substrate, flip-chip plastic board) connection. When the first substrate 4 and the second substrate 7 are flexible substrates, the adhesive film 1 may be used for FOP (Film on Plastic substrate, film-coated plastic plate) connection.

When the second substrate 7 is a flexible substrate, the first circuit member 6 may be an electronic component such as a semiconductor chip, an active element such as a transistor, a diode, or a thyristor, a passive element such as a capacitor, a resistor, or a coil, a printed board, or a glass substrate on which a circuit such as ITO is formed. When the first substrate 4 is a semiconductor chip or a glass substrate, the tip of a bump or gold wire formed by plating may be melted by a welding gun or the like to form a gold ball, which is pressed against an electrode sheet, and then a bump electrode such as a wire bump obtained by cutting a wire is provided to be used as the first circuit member 6.

Examples of the electrode material for forming the first electrode 5 and the second electrode 8 include metals such as Ag, ni, al, au, cu, ti, mo and transparent conductors such as ITO, IZO, silver nanowires, and carbon nanotubes. The first electrode 5 and the second electrode 8 may be formed of the same material, or may be formed of different materials, but are preferably formed of the same material. The first electrode 5 and the second electrode 8 are preferably formed of copper, a copper alloy, or a copper oxide from the viewpoints of reduction in connection resistance and easiness of acquisition. From the viewpoint of preventing disconnection, a surface layer such as an oxide or nitride film, an alloy film, or an organic film may be further provided on the first electrode 5 and the second electrode 8. The first and second electrodes 5 and 8 may be provided one by one on the first and second circuit members 6 and 9, respectively, but it is preferable to provide a plurality of first and second electrodes 5 and 8 at predetermined intervals, respectively.

Examples

The present invention will be further specifically described below with reference to examples. The present invention is not limited to these examples.

Example 1]

20 Parts by mass of urethane acrylate (product name: UA-5500T, product name: manufactured by Xinzhou chemical industry Co., ltd.), 15 parts by mass of bis (acryloyloxyethyl) isocyanurate (product name: M-215, product name: east Asia Synthesis Co., ltd.), 5 parts by mass of dimethylol tricyclodecane diacrylate (product name: DCP-A, product name: co-Rong chemical Co., ltd.), 1 part by mass of 2-methacryloyloxyethyl acid phosphate (product name: P-2M, product name: co-Rong chemical Co., ltd.), 8 parts by mass of benzoyl peroxide (product name: nyper BMT-K, product name: japanese fat/oil Co., ltd.), and 60 parts by mass of a solution containing 40% by mass of polyester polyurethane resin (product name: UR4800, product name: east ocean spinning Co., ltd.) as an insulating resin were mixed and stirred to obtain a resin solution. In this case, the polyester urethane resin solution is prepared by dissolving the polyester urethane resin in a mixed solvent of toluene/methyl ethyl ketone=50/50.

On the other hand, a nickel layer having a thickness of 0.2 μm was formed on the surface of the polystyrene particles. Further, a gold layer having a thickness of 0.04 μm was formed on the outer side of the nickel layer. Thus, conductive particles having an average particle diameter of 4 μm were produced. The conductive particles were dispersed in the prepared resin solution at a ratio of 10 parts by volume to 100 parts by volume of the resin solution. In which 5-methyltetrazole was dispersed in a proportion of 1 part by volume relative to 100 parts by volume of the resin solution. Further, silicone fine particles (product name: KMP-605, manufactured by Xinyue chemical Co., ltd.) having an average particle diameter of 2 μm as a filler were dispersed at a ratio of 20 parts by mass relative to 100 parts by mass of the resin solution, to obtain a coating liquid comprising a radical polymerizable substance, a radical generator, an insulating resin, conductive particles, a compound having a nitrogen-containing aromatic heterocycle, and an adhesive composition for a filler. The coating liquid was applied to a polyethylene terephthalate (PET) film (thickness 50 μm) having one side subjected to a mold release treatment using an application apparatus. The coating film was dried by hot air drying at 70 ℃ to form an anisotropic conductive adhesive film (18 μm thick) containing the adhesive composition according to example 1.

< Examples 2 to 5, comparative example 1>

Adhesive films according to examples 2 to 5 were produced in the same manner as in example 1, except that the compound having a nitrogen-containing aromatic heterocycle shown in table 1 was used instead of 5-methyltetrazole in example 1. An adhesive film according to comparative example 1 was produced in the same manner as in example 1 except that 5-methyltetrazole was not added in example 1.

< Preparation of copper electrode film attached body >

As an adherend imitating a circuit member, a copper electrode film member having a PET film and a copper film formed on the PET film was prepared. The copper electrode film of the copper electrode film member was heated to a temperature of 70 ℃ for the adhesive film, and the entire copper electrode film was pressurized at a pressure of 2MPa with respect to the total connection area for 10 seconds, thereby obtaining a copper electrode film adherend having a cured product of the adhesive composition derived from the adhesive film. Fig. 3 is a schematic cross-sectional view showing a copper electrode film attached body. As shown in fig. 3, in the copper electrode film attached body 13, a copper film 15 is formed on the PET film 14, and a cured product 20 of an adhesive composition (a cured product 22 containing an adhesive component and conductive particles 23) is further provided on a surface 15a of the copper film 15 opposite to the PET film 14.

< Evaluation of connection reliability >

The obtained adherends of examples 1 to 5 and comparative example 1 were allowed to stand in an environment of 85 ℃ and 85% rh for 100 hours and then subjected to a reliability test. The appearance of the portion (attached portion) of the copper film 15 on the surface 15a opposite to the PET film 14, which portion is in contact with the cured product 20, was visually observed with respect to the copper electrode film attached body 13 before and after the test. The connection reliability was evaluated by assuming that a was almost not discolored before and after the test, B was slightly discolored, and C was severely discolored. The evaluation results are shown in table 1. If the evaluation result is A or B, it can be said that the connection reliability is excellent.

< Evaluation of connection resistance >

After the obtained anisotropic conductive adhesive films of examples 1 to 5 and comparative example 1 were attached to the copper electrode film, a flexible circuit board (FPC) was mounted on the adhesive film on the opposite side of the copper electrode film, and the entire was pressurized for 10 seconds under a pressure of 2MPa with respect to the total connection area while heating the adhesive film to a temperature of 170 ℃. As the flexible circuit board, a substrate having an electrode width of 150 μm, an inter-electrode gap (spacer) of 150 μm, an inter-electrode gap (pitch) of 300 μm, a copper foil thickness of 18 μm, and Ni (film thickness of 3 μm) and Au (film thickness of 0.01 μm) formed on the surface was used. The adhesive film-attached body a was left to stand for 100 hours at 85 ℃ under 85% rh, and then subjected to a reliability test. The connection resistance of the adhesive film attached body a after the reliability test was measured, and the case where it was less than or equal to 1Ω was evaluated as a, and the case where it was more than 1Ω was evaluated as B. As shown in table 1, the connection resistance of the adhesive film attachment bodies a of examples 1 to 5 was equal to or less than 1Ω, and was good.

< Evaluation of adhesion >

After the obtained anisotropic conductive adhesive films of examples 1 to 5 and comparative example 1 were attached to a PET film having a SiO ₂ film, a flexible circuit board (FPC) was mounted on the adhesive film on the opposite side of the PET film, and the whole was pressurized for 10 seconds under a pressure of 2MPa with respect to the total connection area while heating the adhesive film to a temperature of 170 ℃. As the flexible circuit board, a substrate having an electrode width of 150 μm, an inter-electrode spacing of 300 μm, a copper foil thickness of 18 μm, and Ni (film thickness of 3 μm) and Au (film thickness of 0.01 μm) formed on the surface was used. The adhesive film-attached body b was left to stand for 100 hours at 85 ℃ under 85% rh, and then subjected to a reliability test. The adhesiveness (adhesive force) of the adhesive film-mounted body B after the reliability test was measured, and the case where it was 4N/cm or more was evaluated as A, and the case where it was less than 4N/cm was evaluated as B. As shown in Table 1, the adhesion was not less than 4N/cm.

TABLE 1

Symbol description

1 Adhesive film (adhesive composition), 2 adhesive component, 3 conductive particles, 4 first substrate, 5 first electrode, 6 first circuit member, 7 second substrate, 8 second electrode, 9 second circuit member, 10 circuit connection member (cured product of adhesive composition), and 11 connection structure.

Claims

1. An adhesive composition comprising conductive particles and an adhesive component comprising a compound having a nitrogen-containing aromatic heterocycle,

The adhesive component contains a radical polymerizable substance,

The radically polymerizable substance contains a urethane acrylate or a urethane methacrylate.

2. The adhesive composition according to claim 1, wherein the adhesive component further comprises a radically polymerizable substance that alone exhibits a Tg of 100 ℃ or more when crosslinked with an organic peroxide.

3. The adhesive composition of claim 1, the nitrogen-containing aromatic heterocycle comprising a single ring.

4. The adhesive composition according to claim 1, wherein the nitrogen-containing aromatic heterocycle is selected from the group consisting of pyrazole ring, imidazole ring, triazole ring, tetrazole ring, thiazole ring, thiadiazole ring,At least one of the group consisting of an azole ring and a pyrimidine ring.

5. The adhesive composition according to claim 1 or 2, which is used for connecting circuit members to each other.

6. A connection structure is provided with:

A first circuit member having a first substrate and a first electrode provided on the first substrate;

a second circuit member having a second substrate and a second electrode provided on the second substrate, and

A circuit connection member disposed between the first circuit member and the second circuit member and electrically connecting the first electrode and the second electrode to each other,

The circuit connecting member is a cured product of the adhesive composition according to any one of claims 1 to 5.

7. The connection structure according to claim 6, wherein the first electrode and the second electrode are formed of copper, a copper alloy, or copper oxide.

8. A method for manufacturing a connection structure, comprising the steps of:

Disposing the adhesive composition according to any one of claims 1 to 5 between a first circuit member having a first substrate and a first electrode provided on the first substrate and a second circuit member having a second substrate and a second electrode provided on the second substrate;

the first circuit member and the second circuit member are pressure-bonded via the adhesive composition, thereby electrically connecting the first circuit member and the second circuit member to each other.