JPWO2008065997A1 - Adhesive and connection structure using the same - Google Patents

Abstract

(A) a thermoplastic resin, (b) a radical polymerizable compound, (c) a urea compound represented by the following general formula (10), (d) a radical polymerization initiator, (e) an acidic compound, Containing adhesive. [Chemical 1]

Description

  The present invention relates to an adhesive and a connection structure using the adhesive.

In the semiconductor element and the liquid crystal display element, an adhesive is used for the purpose of bonding various members constituting the element. This adhesive is required to satisfy various properties such as adhesiveness, heat resistance and reliability in a high temperature and high humidity state. In addition, the adherend to which the adhesive is applied is a surface composed of various materials such as printed wiring boards and organic base materials such as polyimide, metals such as copper and aluminum, and ITO, SiN, and SiO ₂ A substrate having the following is used. In the adhesive, it is necessary to design a molecule according to such various adherends.

  Conventionally, as an adhesive for a semiconductor element or a liquid crystal display element, a thermosetting resin using an epoxy resin having high adhesion and high reliability has been widely used (for example, see Patent Document 1). As a component of an adhesive using an epoxy resin, a curing agent such as an epoxy resin, a phenol resin having reactivity with the epoxy resin, or a thermal latent catalyst that promotes the reaction between the epoxy resin and the curing agent is generally used. . The heat latent catalyst is an important factor for determining the curing temperature and the curing rate, and various compounds have been used from the viewpoint of storage stability at room temperature and curing rate during heating. As for the curing conditions in the actual process, heating at a temperature of 170 to 250 ° C. for about 1 to 3 hours is common.

  However, with recent high integration of semiconductor elements and high definition of liquid crystal elements, the pitch between elements and wirings is narrowed, and there is a high possibility that peripheral members will be adversely affected by heating during curing. Furthermore, there is a need to improve throughput in order to reduce costs. For this reason, curing at a lower temperature and in a shorter time, in other words, adhesion at a low temperature rapid curing is required. In order to achieve this low temperature rapid curing, it is necessary to use a thermal latent catalyst with low activation energy, so it is very difficult to combine low temperature rapid curing and storage stability near room temperature. It has been known.

Therefore, recently, radical curing type adhesives using radically polymerizable compounds such as acrylate derivatives and methacrylate derivatives and peroxides as radical polymerization initiators are attracting attention. Radical curing can be cured in a short time because radicals that are reactive species are rich in reactivity (see, for example, Patent Document 2). However, since the radical curable adhesive has a large curing shrinkage at the time of curing, the adhesive strength tends to be lower than that when an epoxy resin is used. Therefore, in order to improve the adhesive strength of the radical curable adhesive, a method using a urethane acrylate compound imparted with flexibility and flexibility by an ether bond as a radical polymerizable compound (see Patent Documents 3 and 4) , A method using a radically polymerizable compound, phosphate methacrylate and melamine resin in combination (see Patent Documents 5 and 6) has been proposed.
Japanese Patent Laid-Open No. 1-113480 JP 2002-203427 A Japanese Patent No. 3522634 JP 2002-285128 A JP 2003-89775 A JP 2003-20464 A

  However, although radical curable adhesives using urethane acrylate have good initial adhesive strength, there is a problem that characteristics such as adhesive strength and connection resistance deteriorate when exposed to a high temperature and high humidity environment. there were. Further, according to the study by the present inventors, an adhesive using a methacrylate methacrylate and a melamine resin has insufficient storage stability, and sufficient adhesive strength and connection resistance can be obtained when used after long-term storage. It became clear that it disappeared.

  Therefore, the present invention is a radical curable adhesive that expresses high adhesive strength, has high resistance to a reliability test under high temperature and high humidity, and also has excellent storage stability, and a connection using the same An object is to provide a structure.

The adhesive according to the present invention includes (a) a thermoplastic resin, (b) a radical polymerizable compound, (c) a urea compound represented by the following general formula (10), and (d) a radical polymerization initiator. And (e) an acidic compound. In formula (10), R ¹ and R ² each independently represent an alkyl group or a hydrogen atom which may have a substituent, and R ¹ and R ² may be bonded to each other to form a ring. , R ³ and R ⁴ each independently represent a hydrogen atom, a linear alkyl group having 1 to 8 carbon atoms, or a branched alkyl group having 3 to 10 carbon atoms.

  The adhesive according to the present invention employs a combination of the above-mentioned specific components, so that it exhibits high adhesive strength, has high resistance to a reliability test under high temperature and high humidity, and storage stability. It became even better.

  The connection structure according to the present invention includes a first circuit member having a first connection terminal, a second connection terminal, and the second connection terminal facing the first connection terminal. A second circuit member disposed opposite to the one circuit member; and an adhesive layer that is interposed between the first circuit member and the second circuit member to bond them together. The adhesive layer is formed by the adhesive according to the present invention.

  The connection structure according to the present invention has high resistance to a reliability test under high temperature and high humidity while the circuit members are bonded to each other with high adhesive strength.

  ADVANTAGE OF THE INVENTION According to this invention, while exhibiting high adhesive strength, it has the high tolerance with respect to the reliability test under high temperature, high humidity, Furthermore, the radical curing type adhesive which is excellent also in storage stability is provided.

  Moreover, according to this invention, while the circuit members are adhere | attached by high adhesive strength, the connection structure which has the high tolerance with respect to the reliability test under high temperature, high humidity is provided.

It is a schematic cross section showing one embodiment of a connection structure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Connection structure, 7 ... Electroconductive particle, 10 ... Adhesive layer, 11 ... Insulating layer, 20 ... First circuit member, 21 ... First circuit board, 22 ... First connection terminal, 30 ... Second Circuit member, 31 ... second circuit board, 32 ... second connection terminal.

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

  The adhesive according to this embodiment contains (a) a thermoplastic resin, (b) a radical polymerizable compound, (c) a urea compound, (d) a radical polymerization initiator, and (e) an acidic compound. To do. The adhesive according to the present invention is suitably used as, for example, an anisotropic conductive adhesive for bonding circuit members having connection terminals to form a connection structure.

  As the thermoplastic resin of the component (a), known resins can be used without any particular limitation. For example, phenoxy resin, polyester resin, polyurethane resin, polyester urethane resin, butyral resin, acrylic resin, polyimide resin, polyamide resin, poly (meth) acrylates, polyvinyl butyral, or ethylene-vinyl acetic acid copolymer is a thermoplastic resin. Can be used as In particular, the thermoplastic resin in the adhesive preferably contains at least one selected from the group consisting of phenoxy resin, polyester resin, polyurethane resin, polyester urethane resin, butyral resin, acrylic resin and polyimide resin. These can be used alone or in combination of two or more.

  The thermoplastic resin may have a siloxane bond or a substituent containing a fluorine atom. These can be used particularly preferably if they are completely compatible with each other, or if they become cloudy due to microphase separation.

  The larger the molecular weight of the thermoplastic resin, the easier it is to obtain film formability, and the melt viscosity that affects the fluidity as an adhesive can be set over a wide range. Specifically, the weight average molecular weight of the thermoplastic resin is preferably 5,000 to 500,000, and more preferably 10,000 to 100,000. If the weight average molecular weight is less than 5,000, the film formability tends to decrease, and if it exceeds 500,000, the compatibility with other components tends to decrease.

  As the radically polymerizable compound of component (b), any known compound can be used without particular limitation as long as it is a compound having a radically polymerizable functional group. For example, a styrene derivative, a maleimide polymer, and a compound having an acryloyl group or a methacryloyl group (hereinafter referred to as “(meth) acryloyl group”) are used. Especially, it is preferable that a radically polymerizable compound contains the polyfunctional (meth) acrylate compound which has a 2 or more (meth) acryloyl group.

  Preferred specific examples of the polyfunctional (meth) acrylate include epoxy (meth) acrylate oligomers, urethane (meth) acrylate oligomers, oligomers such as polyether (meth) acrylate oligomers and polyester (meth) acrylate oligomers, and trimethylolpropane. Tri (meth) acrylate, polyethylene glycol di (meth) acrylate, polyalkylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, dipentaerythritol hexa (meth) acrylate, isocyanuric acid modified bifunctional (meth) acrylate Epoxy with (meth) acrylic acid added to the glycidyl group of isocyanuric acid-modified trifunctional (meth) acrylate and bisphenol fluorenediglycidyl ether (Meth) acrylate, a compound in which ethylene glycol or propylene glycol is added to a glycidyl group of bisphenol fluorenediglycidyl ether, a compound represented by the following general formula (A) or (B): These are polyfunctional (meth) acrylate compounds. These polyfunctional (meth) acrylate compounds are used alone or in combination of two or more as required.

In formula (A), R ²¹ and R ²² each independently represent a hydrogen atom or a methyl group, and k and m each independently represent an integer of 1 to 8. In formula (B), R ²³ and R ²⁴ represent a hydrogen atom or a methyl group, n represents an integer of 1 to 8, and p represents an integer of 0 to 8.

  As the component (b), for the purpose of improving fluidity, a polyfunctional (meth) acrylate compound and a monofunctional (meth) acrylate compound may be used in combination. By using a monofunctional (meth) acrylate compound, the fluidity of the adhesive is improved. Specific examples of monofunctional (meth) acrylate compounds include pentaerythritol (meth) acrylate, 2-cyanoethyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) ) Acrylate, 2- (2-ethoxyethoxy) ethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-hexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate , Hydroxypropyl (meth) acrylate, isobornyl (meth) acrylate, isodecyl (meth) acrylate, isooctyl (meth) acrylate, n-lauryl (meth) acrylate, 2-methoxyethyl (meth) Acrylate, 2-phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylamino Examples include propyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, (meth) acryloylmorpholine, and bisphenoxyethanol fluorene acrylate. These compounds may be used alone or in combination of two or more as required.

  The radically polymerizable compound may contain a compound having a radically polymerizable functional group other than the (meth) acryl group, such as an allyl group, a maleimide group, and a vinyl group. Specific examples thereof include N-vinylimidazole, N-vinylpyridine, N-vinylpyrrolidone, N-vinylformamide, N-vinylcaprolactam, 4,4′-vinylidenebis (N, N-dimethylaniline), N-vinyl. Examples include acetamide, N, N-dimethylacrylamide, N-isopropylacrylamide, and N, N-diethylacrylamideacrylamide.

  The amount of the radical polymerizable compound in the adhesive is preferably 30 to 250 parts by weight with respect to 100 parts by weight of the thermoplastic resin. When the amount of the radical polymerizable compound is less than 30 parts by weight, the heat resistance after curing tends to decrease, and when it exceeds 250 parts by weight, the film formability tends to decrease when the adhesive is used as a film. There is. From the same viewpoint, the amount of the radical polymerizable compound is more preferably 50 to 150 parts by weight.

  As will be described later, when the acidic compound of component (e) has a radical polymerizable functional group such as a vinyl group, a radical polymerizable compound different from component (e) is used as component (b).

  The urea compound as component (c) is a compound represented by the general formula (10). By using such a urea compound in combination with an acidic compound, an increase in connection resistance and a decrease in adhesive strength under high temperature and high humidity are suppressed, and furthermore, storage stability is specifically improved. On the other hand, according to the knowledge of the present inventors, when an acidic compound is combined with a melamine resin, the initial adhesive strength is relatively good, but the adhesive strength is remarkably lowered after long-term storage. The reason is not necessarily clear, but it is considered that the reaction of the melamine resin itself tends to proceed gradually in the presence of an acidic compound during long-term storage.

In Formula (10), R ¹ and R ² each independently represent an alkyl group or a hydrogen atom which may have a substituent, and R ¹ and R ² may be bonded to each other to form a ring. . R ³ and R ⁴ each independently represent a hydrogen atom, a linear alkyl group having 1 to 8 carbon atoms, or a branched alkyl group having 3 to 10 carbon atoms. The alkyl group as R ¹ and R ² may be substituted with, for example, a urea group.

  More specifically, the urea compound is one selected from compounds represented by the following general formula (11), (12), (13), (14), (15), (16) or (17). The above is preferable. By using these compounds, the effect of improving resistance to high-temperature and high-humidity environments and storage stability is particularly prominent.

In the formula (11) ~ (17), ^{R 3} and ^{R 4} are the same as ^{R 3} and ^{R 4} of formula (10). In formula (13), R ⁵ and R ⁶ each independently represent a hydrogen atom, a linear alkyl group having 1 to 8 carbon atoms, or a branched alkyl group having 3 to 10 carbon atoms. In formula (14), R ⁷ and R ⁸ each independently represent a hydrogen atom, a linear alkyl group having 1 to 8 carbon atoms, or a branched alkyl group having 3 to 10 carbon atoms. In Formula (16), R ⁹ represents a hydrogen atom, a linear alkyl group having 1 to 8 carbon atoms, or a branched alkyl group having 3 to 10 carbon atoms. In formula (17), R ¹⁰ and R ¹¹ each independently represent a hydrogen atom, a linear alkyl group having 1 to 8 carbon atoms, or a branched alkyl group having 3 to 10 carbon atoms.

More specifically, the urea compound is represented by the formula (11), and R ³ and R ⁴ are hydrogen atoms, N, N′-dimethylolurea, represented by the formula (12), and R ³ and R ⁴ 1,3-dimethoxymethylethyleneurea in which is a methyl group, and 1,3,4,6-tetrakis (which is represented by the formula (17) and in which R ³ , R ⁴ , R ¹⁰ and R ¹¹ are methyl groups There is methoxymethyl) glycoluril.

  The amount of the urea compound in the adhesive is preferably 1 to 50 parts by weight with respect to 100 parts by weight of the thermoplastic resin. When the amount of the urea compound is less than 1 part by weight, the effect of improving the resistance to the reliability test tends to be reduced, and when it exceeds 50 parts by weight, the film formability tends to be lowered when the adhesive is used as a film. There is. From the same viewpoint, the amount of the urea compound is more preferably 5 to 30 parts by weight.

  As the radical polymerization initiator of component (d), known compounds such as conventionally known peroxides and azo compounds can be used. From the viewpoints of stability, reactivity, and compatibility, a peroxide having a 1 minute half-life temperature of 90 to 175 ° C. and a molecular weight of 180 to 1000 is preferred.

  Specific examples of suitable radical polymerization initiators include 1,1,3,3-tetramethylbutylperoxyneodecanoate, di (4-t-butylcyclohexyl) peroxydicarbonate, di (2-ethylhexyl) perper Oxydicarbonate, cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, dilauroyl peroxide, 1-cyclohexyl-1-methylethylperoxynoedecanoate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2 , 5-Dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, t-hex Peroxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyneoheptanoate, t-amylperoxy-2-ethylhexanoate, di-t-butyl Peroxyhexahydroterephthalate, t-amylperoxy-3,5,5-trimethylhexanoate, 3-hydroxy-1,1-dimethylbutylperoxyneodecanoate, 1,1,3,3-tetramethyl Butyl peroxy-2-ethylhexanoate, t-amylperoxyneodecanoate, t-amylperoxy-2-ethylhexanoate, di (3-methylbenzoyl) peroxide, dibenzoyl peroxide, di (4-Methylbenzoyl) peroxide, 2,2′-azobis-2,4-dimethylvalero Tolyl, 1,1′-azobis (1-acetoxy-1-phenylethane), 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), dimethyl-2, 2'-azobisisobutyronitrile, 4,4'-azobis (4-cyanovaleric acid), 1,1'-azobis (1-cyclohexanecarbonitrile), t-hexylperoxyisopropyl monocarbonate, t-butylper Oxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di (3-methylbenzoylperoxy) hexane, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5 -Di (benzoylperoxy) hexane, t-butylperoxybenzoate, dibutylperoxytrimethyladipate, t-amylperoxynormal octoate, t-amylperoxyisononanoate, and t-amylperoxybenzoate . These compounds may be used alone or in combination of two or more.

  As the radical polymerization initiator, a photo radical polymerization initiator that generates radicals by light irradiation (typically 150 to 750 nm) is also preferable. Examples of photo radical polymerization initiators include Photoinitiation, Photopolymerization, and Photocuring, J. Mol. -P. The α-acetaminophenone derivatives and phosphine oxide derivatives described in Fouassier, Hanser Publishers (1995), p17 to p35 are more preferable because of their high sensitivity to light irradiation. These radical photopolymerization initiators may be used alone or in combination with a peroxide or an azo compound.

  The amount of the radical polymerization initiator in the adhesive is preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the thermoplastic resin. If the amount of the radical polymerization initiator is less than 0.1 parts by weight, the possibility of insufficient curing tends to increase, and if it exceeds 30 parts by weight, the effect of improving storage stability tends to be small. From the same viewpoint, the amount of the radical polymerization initiator is more preferably 2 to 20 parts by weight.

  (E) The acidic compound of a component is a compound which has 1 or 2 or more acidic groups, such as a phosphate group. In particular, an acidic compound having a phosphate group and a vinyl group is preferable. By using an acidic compound having a phosphoric acid group and a vinyl group, higher adhesive force can be maintained. As an acidic compound which has a phosphoric acid group and a vinyl group ((meth) acryl group), the compound represented by the following general formula (21), (22) or (23) is mentioned, for example.

In formula (21), R ³⁰ and R ³¹ each independently represent a hydrogen atom or a methyl group, and w and x each independently represent an integer of 1 to 8. In formula (22), R ³⁰ represents a hydrogen atom or a methyl group, and x, y and z each independently represents an integer of 1 to 8. In formula (23), R ³⁰ and R ³¹ each independently represent a hydrogen atom or a methyl group, and a and b each independently represent an integer of 1 to 8.

  More specifically, the acidic compound includes acid phosphooxyethyl methacrylate, acid phosphooxyethyl acrylate, acid phosphooxypropyl methacrylate, acid phosphooxypolyoxyethylene glycol monomethacrylate, acid phosphooxypolyoxypropylene glycol monomethacrylate, 2- From (meth) acryloyloxyethyl phosphate, 2,2'-di (meth) acryloyloxydiethyl phosphate, EO (ethylene oxide) modified phosphate dimethacrylate, phosphate modified epoxy acrylate, vinyl phosphate and lactone modified phosphate methacrylate It is preferably at least one selected from the group consisting of

  The amount of the acidic compound in the adhesive is preferably 0.05 to 30 parts by weight with respect to 100 parts by weight of the thermoplastic resin. If the amount of the acidic compound is less than 0.05 parts by weight, high adhesive strength tends to be difficult to obtain, and if it exceeds 30 parts by weight, the physical properties of the adhesive after curing are lowered, and the reliability is improved. Tends to be smaller. From the same viewpoint, the amount of the acidic compound is more preferably 0.1 to 20 parts by weight.

  The adhesive according to the present embodiment may further contain conductive particles as the component (f). Adhesives containing conductive particles are particularly useful as anisotropic conductive adhesives. Examples of the conductive particles include metal particles such as Au, Ag, Ni, Cu, and solder, and carbon. Coated particles having a nonconductive core made of glass, ceramic, plastic or the like and a coating layer made of metal or carbon covering the core may be used as the conductive particles. Since the conductive particles are coated particles having a core made of plastic and a coating layer made of a metal or carbon that coats the core, or heat-melted metal particles, the conductive particles have deformability due to heat and pressure, The contact area with the electrode increases at the time of connection, which improves the reliability. In addition, fine particles with the surface of these conductive particles coated with a polymer resin or the like suppress short circuit due to contact between the particles when the amount of the conductive particles is increased, and the insulation between the electrode circuits is reduced. Since it can improve, you may use this individually or in mixture with electroconductive particle suitably.

  The average particle size of the conductive particles is preferably 1 to 18 μm from the viewpoint of dispersibility and conductivity. It is preferable that the quantity of the electroconductive particle in an adhesive agent is 0.1-30 volume% with respect to the volume of the whole adhesive agent containing electroconductive particle. When the amount of the conductive particles is less than 0.1% by volume, sufficient conductivity tends to be hardly obtained, and when it exceeds 30% by volume, a short circuit tends to occur. From the same viewpoint, the amount of the conductive particles is more preferably 0.1 to 10% by volume. In addition, the volume% of electroconductive particle is determined based on the volume in 23 degreeC of each component before hardening. The volume of each component can be converted from weight to volume using specific gravity. Alternatively, do not dissolve or swell each component, put an appropriate solvent (water, alcohol, etc.) that wets each component well into a graduated cylinder, and add each component to it and obtain the increased volume as the volume. You can also.

  The adhesive according to this embodiment may contain a stabilizer. By using the stabilizer, the effect of improving the storage stability becomes more remarkable while appropriately controlling the curing rate. Stabilizers include quinone derivatives such as benzoquinone and hydroquinone, phenol derivatives such as 4-methoxyphenol and 4-t-butylcatechol, 2,2,6,6-tetramethylpiperidine-1-oxyl and 4-hydroxy-2 It is preferably selected from aminoxyl derivatives such as 1,2,6,6-tetramethylpiperidine-1-oxyl, and hindered amine derivatives such as tetramethylpiperidyl methacrylate.

  The amount of the stabilizer in the adhesive is preferably 0.01 to 30 parts by weight with respect to 100 parts by weight of the thermoplastic resin. If the amount of the stabilizer is less than 0.01 parts by weight, the effect tends to be reduced, and if it exceeds 30 parts by weight, the compatibility with other components tends to be reduced. From the same viewpoint, the amount of the stabilizer is more preferably 0.05 to 10 parts by weight.

  The adhesive according to this embodiment may contain an adhesion aid such as a coupling agent represented by an alkoxysilane derivative and a silazane derivative, an adhesion improver, and a leveling agent. Specifically, the adhesive may contain a silane compound represented by the following general formula (30). Such silane compounds may be used alone or in combination of two or more.

In the formula (30), R ³² represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkoxycarbonyl group having 1 to 5 carbon atoms, or an aryl group. A plurality of R ³² may be the same or different, and R ³³ is a (meth) acryloyloxy group, vinyl group, isocyanate group, imidazole group, mercapto group, amino group, methylamino group, dimethylamino group, benzylamino group , Phenylamino group, cyclohexylamino group, morpholino group, piperazino group, ureido group or glycidyl group, and c represents an integer of 1 to 10. When R ³³ is a (meth) acryloyloxy group, the silane compound is used as the component (b). In other words, the radically polymerizable compound of the component (b) may include a silane compound represented by the formula (30), and R ³³ is a (meth) acryloyloxy group.

  The adhesive according to this embodiment may contain rubber. By using rubber, effects of stress relaxation and adhesion improvement can be obtained. Specific examples of rubber include polyisoprene, polybutadiene, carboxyl-terminated polybutadiene, hydroxyl-terminated polybutadiene, 1,2-polybutadiene, carboxyl-terminated 1,2-polybutadiene, hydroxyl-terminated 1,2-polybutadiene, acrylic rubber, and styrene-butadiene. Rubber, hydroxyl-terminated styrene-butadiene rubber, acrylonitrile-butadiene rubber, carboxyl group, hydroxyl group, (meth) acryloyl group or morpholine group-containing acrylonitrile-butadiene rubber, carboxylated nitrile rubber, hydroxyl-terminated poly (oxypropylene) , Alkoxysilyl-terminated poly (oxypropylene), poly (oxytetramethylene) glycol, polyolefin glycol, and poly-ε-caprolactone.

  From the viewpoint of improving adhesiveness, a rubber having a cyano group or a carboxyl group, which is a highly polar group, in the side chain or terminal is preferable. From the viewpoint of improving fluidity, liquid rubber is more preferable. Specific examples include liquid acrylonitrile-butadiene rubber, liquid acrylonitrile-butadiene rubber containing a carboxyl group, a hydroxyl group, a (meth) acryloyl group or a morpholine group at the polymer end, and a liquid carboxylated nitrile rubber. These rubbers preferably contain 10 to 60% by weight of acrylonitrile. These rubbers may be used alone or in combination of two or more.

  The adhesive according to this embodiment may be liquid (preferably pasty) at normal temperature (0 to 30 ° C.) or may be solid. The solid adhesive may be used by heating, or may be pasted using a solvent. The solvent that can be used is not particularly limited as long as it has no reactivity with each component of the adhesive and exhibits sufficient solubility, but has a boiling point of 50 to 150 ° C. at normal pressure. preferable. If the boiling point is less than 50 ° C., it may volatilize if left at room temperature (0 to 30 ° C.), which limits the use in an open system. On the other hand, if the boiling point exceeds 150 ° C., it is difficult to volatilize the solvent, which may adversely affect the reliability after bonding.

  The adhesive according to this embodiment may be in the form of a film. Use in the form of a film is more convenient from the viewpoint of handleability. For example, a film-like adhesive is obtained by applying a solution obtained by dissolving an adhesive in a solvent onto a peelable substrate such as a fluororesin film, a polyethylene terephthalate film, or a release paper, or impregnating a substrate such as a nonwoven fabric. It can obtain by the method of mounting on a peelable base material and removing a solvent after that.

  The adhesive according to the present embodiment can be used as an adhesive for bonding different kinds of adherends having different thermal expansion coefficients. Specifically, it is suitably used as a circuit connecting material typified by anisotropic conductive adhesive, silver paste, silver film and the like. Or you may use the adhesive agent which concerns on this embodiment as a semiconductor element adhesive material represented by the elastomer for CSP, the underfill material for CSP, a LOC tape, a die attach film, etc.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of a connection structure. A connection structure 1 shown in FIG. 1 includes a first circuit board 21 and a first circuit member 20 having a first connection terminal 22 formed on a main surface 21a thereof, a second circuit board 31 and The second circuit member 30 having the second circuit electrode 32 formed on the main surface 31a thereof, and the first circuit member 20 and the second circuit member 30 are interposed and bonded together. The adhesive layer 10 is provided. The second circuit member 30 is disposed to face the first circuit member 20 so that the second connection terminal 32 faces the first connection terminal 22.

  The adhesive layer 10 is formed of the above-described adhesive containing conductive particles, and includes an insulating layer 11 and conductive particles 7 dispersed in the insulating layer 11. The insulating layer 11 is a cured body that is derived from components other than the conductive particles in the adhesive and is formed by radical polymerization of a radical polymerizable compound. The first connection terminal 22 and the second connection terminal 32 facing each other are electrically connected via the conductive particles 7. On the other hand, the first connection terminals 22 and the second connection terminals 32 formed on the same circuit board are insulated.

  As the first circuit board 31 and the second circuit board 21, for example, a substrate made of an inorganic material such as a semiconductor, glass and ceramic, a plastic substrate, or a glass / epoxy substrate is used. Examples of the plastic substrate include a polyimide film, a polycarbonate film, and a polyester film. The first connection terminal and the second connection terminal are formed from a metal such as copper.

  More specifically, one of the first circuit member 20 and the second circuit member 30 is a liquid crystal display panel having a glass substrate or a plastic substrate as a circuit substrate and having connection terminals formed from ITO or the like. There may be. Further, one of the first circuit member 20 and the second circuit member 30 is a flexible printed wiring board (FPC), a tape carrier package (TCP) or a chip-on-film (COF) having a polyimide film as a circuit board, or It may be a semiconductor silicon chip having a semiconductor substrate as a circuit board. These various circuit members are appropriately combined as necessary to constitute a connection structure.

  In the connection structure 1, for example, the first connection member 22 and the second connection terminal 32 face each other in the order of the first circuit member 20, the film adhesive, and the second circuit member 30. In this state, the adhesive is cured by heating and pressing in this state. The heating temperature is not particularly limited, but is preferably 100 to 250 ° C. The pressure is not particularly limited as long as it does not damage the adherend, but is generally preferably 0.1 to 10 MPa. These heating and pressurization are preferably performed in the range of 0.5 seconds to 120 seconds, and can be bonded even by heating at 140 to 200 ° C., 3 MPa, and 10 seconds.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

Material (a) Thermoplastic resin / phenoxy resin: PKHM-30 (trade name), manufactured by InChem, butyral resin: Denkabutyral 3000-1 (trade name), manufactured by Denki Kagaku Kogyo Co., Ltd., polyester urethane resin: UR-3500 ( Product name), Toyobo Co., Ltd. urethane resin: 450 parts by weight of polybutylene adipate diol having an average molecular weight of 2000, 450 parts by weight of polyoxytetramethylene glycol having an average molecular weight of 2000 and 100 parts by weight of 1,4-butylene glycol are 4000 parts by weight of methyl ethyl ketone. The mixture was uniformly mixed, and 390 parts by weight of diphenylmethane diisocyanate was added and reacted at 50 ° C. (weight average molecular weight 100,000).
(B) Radical polymerizable compound, isocyanuric acid EO-modified triacrylate: M-315 (trade name), manufactured by Toa Gosei Co., Ltd., urethane acrylate: AT-600 (trade name), Kyoeisha Chemical Co., Ltd. (c) urea compound N, N'-dimethylolurea (urea compound 1): manufactured by Tokyo Chemical Industry 1,3,4,6-tetrakis (methoxymethyl) glycoluril (urea compound 2): manufactured by Tokyo Chemical Industry 1,3-dimethoxymethylethylene Urea (urea compound 3): After reacting 43 parts by weight of 2-imidazolidone (manufactured by Aldrich) and 122 parts by weight of 37% formaldehyde (manufactured by Kanto Chemical) under basic conditions at 100 ° C. for 1 hour, room temperature (25 ° C. ), 32 parts by weight of methanol (manufactured by Kanto Chemical Co., Inc.) was added, and the mixture was stirred for 30 minutes under acidic conditions, and water was distilled off (yield 72%).
(D) Radical polymerization initiator t-hexylperoxy-2-ethylhexanoate: Perhexyl O (trade name), manufactured by Nippon Oil & Fats Co., Ltd. (e) Acidic compound 2- (meth) acryloyloxyethyl phosphate: Light ester P-2M (trade name), manufactured by Kyoeisha Co., Ltd., lactone-modified phosphate methacrylate: Kayamar PM-21 (trade name), manufactured by Nippon Kayaku Co., Ltd.

Production of Film Adhesive 40 g of phenoxy resin and butyral resin were dissolved in 60 g of methyl ethyl ketone to prepare a solution having a solid content of 40% by weight. The polyester urethane resin was dissolved in a mixed solvent of methyl ethyl ketone and toluene. These solutions were used for the preparation of the adhesive.

  Further, conductive particles (average particle diameter of 4 μm, specific gravity of 2. μm) provided with a nickel layer having a thickness of 0.2 μm on the surface of a core made of polystyrene and a gold layer having a thickness of 0.02 μm provided on the outside of the nickel layer. 5) was produced.

  A thermoplastic resin, a radical polymerizable compound, a urea compound, a radical polymerization initiator and an acidic compound are mixed in the composition (solid weight ratio) shown in Table 1, and the conductive particles are added at a ratio of 1.5% by volume. This was dispersed to prepare adhesive solutions for the examples and comparative examples.

  The obtained adhesive solution was applied to a fluororesin film having a thickness of 80 μm using a coating apparatus, and a film adhesive having a thickness of 18 μm was obtained by drying with hot air at 70 ° C. for 10 minutes.

Evaluation of film adhesive (1) Adhesive strength, connection resistance Using the obtained film adhesive, a flexible circuit board (FPC) having 500 copper circuits having a line width of 25 μm, a pitch of 50 μm, and a thickness of 12 μm, and 0 A glass substrate (thickness 1.1 mm, surface resistance 20 Ω / □) on which a thin layer of 2 μm indium oxide (ITO) was formed was used with a thermocompression bonding apparatus (heating method: constant heat type, manufactured by Toray Engineering Co., Ltd.) Then, heating and pressurizing at 3 MPa at a temperature of 160 ° C. for 10 seconds were performed to connect over a width of 2 mm to produce a connection structure. The resistance value between adjacent circuits of the obtained connection structure was measured with a multimeter immediately after bonding and after being held in a high-temperature and high-humidity tank at 85 ° C. and 85% RH for 168 hours. The resistance value was shown as an average of 37 resistances between adjacent circuits.

  Moreover, the adhesive strength of the connection structure was measured by a 90-degree peeling method according to JIS-Z0237. As a measuring device for adhesive strength, Tensilon UTM-4 (peeling speed 50 mm / min, 25 ° C.) manufactured by Toyo Baldwin Co., Ltd. was used.

  The connection resistance and the adhesive strength were measured immediately after bonding and after being subjected to a reliability test in which the connection structure was held in a high-temperature and high-humidity tank at 85 ° C. and 85% RH for 168 hours. The measurement results are shown in Table 2.

  The film-like adhesives of Examples 1 to 7 showed good connection resistance and adhesive strength immediately after bonding and after high-temperature and high-humidity treatment, and were found to have sufficient resistance to the reliability test. On the other hand, in Comparative Examples 1 to 3 in which no urea compound was used, a significant decrease in adhesive strength was observed after the high temperature and high humidity treatment. In Comparative Example 4 in which no acidic compound was used, connection resistance and adhesive strength were not sufficient immediately after bonding, and peeling occurred after high-temperature and high-humidity treatment. In Table 2, “Open” means that the connection resistance was 500Ω or more, and “Peel” means that the FPC was peeled off when the peel strength (adhesion strength) was measured.

(2) Storage stability The film adhesives obtained in Examples 3 and 6 were vacuum packaged and allowed to stand at 40 ° C. for 3 days. Thereafter, a connection structure was prepared in the same manner as in “(1) Adhesive strength and connection resistance”, and the adhesive strength and connection resistance were measured. The measurement results are shown in Table 3 together with the values before standing (immediately after bonding).

  It was found that the film adhesives of Examples 3 and 6 exhibited good connection resistance and adhesive strength before and after standing at 40 ° C./3 days, and were excellent in storage stability.

  As is clear from the experimental results as described above, according to the present invention, high adhesive strength is exhibited, high resistance to a reliability test under high temperature and high humidity, and storage stability are also achieved. It was confirmed that an excellent radical curable adhesive was provided.

Claims (5)

(A) a thermoplastic resin;
(B) a radically polymerizable compound;
(C) a urea compound represented by the following general formula (10);
(D) a radical polymerization initiator;
(E) an acidic compound;
Containing adhesive.

[In Formula (10), R ¹ and R ² each independently represent an alkyl group or a hydrogen atom which may have a substituent, and R ¹ and R ² may be bonded to each other to form a ring. Well, R ³ and R ⁴ each independently represent a hydrogen atom, a linear alkyl group having 1 to 8 carbon atoms, or a branched alkyl group having 3 to 10 carbon atoms. ]   The adhesive according to claim 1, wherein the acidic compound has a phosphate group and a vinyl group.   The adhesive according to claim 1, wherein the thermoplastic resin includes at least one selected from the group consisting of a phenoxy resin, a polyester resin, a polyurethane resin, a polyester urethane resin, a butyral resin, an acrylic resin, and a polyimide resin.   The adhesive according to claim 1, further comprising (f) conductive particles. A first circuit member having a first connection terminal;
A second circuit member having a second connection terminal, the second circuit member being disposed opposite to the first circuit member such that the second connection terminal faces the first connection terminal;
An adhesive layer that is interposed between the first circuit member and the second circuit member to bond them;
With
The connection structure in which the said contact bonding layer is formed with the adhesive agent as described in any one of Claims 1-4.

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