JP4415905B2 - Adhesive, wiring terminal connection method and wiring structure - Google Patents

Description

  The present invention relates to an adhesive for wiring connection, a method of connecting a wiring terminal using the same, and a wiring structure.

  In recent years, the density of wiring has been increased in the field of precision electronic equipment, and the electrode width and the electrode interval have become extremely narrow. In order to solve this problem, an adhesive composition for electric and electronic use having excellent low-temperature fast curing properties and having a pot life has been developed (for example, JP-A-11-97825).

  However, these conventional wiring connecting members have a problem that the adhesive strength differs depending on the type of material constituting the wiring to be connected. In particular, when the substrate supporting the wiring terminals is an insulating organic material such as polyimide resin or glass, or when silicon nitride, silicone resin, or polyimide resin is coated or adhered to the surface of the wiring member, the adhesive strength is significantly reduced. There was a problem to do.

  INDUSTRIAL APPLICABILITY The present invention is suitable for electric and electronic use, and in particular, a wiring member in which a substrate supporting a wiring terminal is made of an insulating organic material or glass, or a wiring member having silicon nitride, silicone resin and / or polyimide resin on at least a part of its surface It is an object of the present invention to provide an adhesive capable of obtaining a high adhesive strength even when adhering, a wiring terminal connection method using the same, and a wiring structure.

  The present invention provides an adhesive for connecting a wiring terminal, which includes (1) a curing agent that generates free radicals upon heating, (2) a radical polymerizable substance, and (3) silicone particles. The adhesive of the present invention is interposed between wiring boards arranged so that wiring terminals provided on the surface face each other, and the wiring boards are heated while being pressed to electrically connect the terminals. Can be used. In the present specification, the terminal may be an electrode.

  The adhesive of the present invention may further contain (4) a film forming material. A phenoxy resin is suitable as the film forming material.

  The adhesive of the present invention may further contain (5) conductive particles. It is preferable that at least the surface of the conductive particles includes at least one of gold, silver, and a platinum group metal, and the surface is preferably covered with any of these metals.

  The content of the silicone particles in the adhesive of the present invention is 5 parts by weight based on 100 parts by weight of the radical polymerizable substance (when including the film forming material, the total of 100 parts by weight of the radical polymerizable substance and the film forming material). It is preferable that it is -200 weight part.

  The silicone particles used in the adhesive of the present invention desirably have an elastic modulus of 0.1 to 100 MPa at 25 ° C. (room temperature).

  In the present invention, (1) a curing agent that generates free radicals upon heating, (2) a first layer comprising a composition containing a radical polymerizable substance and (3) silicone particles, and (5) conductivity. Provided is an adhesive film for connecting a wiring terminal, in which particles, (2) a radical polymerizable substance, and (3) a second layer made of a composition containing silicone particles are laminated.

  Furthermore, in this invention, the connection method of the wiring terminal which electrically connects between the connection terminals each provided in two or more wiring members using the adhesive agent of this invention is provided.

  The connection method of the present invention includes a first wiring member having a first connection terminal and a second connection terminal arranged so that the terminals face each other with the adhesive of the present invention interposed therebetween. The second wiring member is heated while being pressed in the bonding direction to electrically connect the first connection terminal and the second connection terminal.

  The connection method of the present invention is particularly suitable when at least one of the connection terminals has a surface made of gold, silver, tin, a platinum group metal, and / or indium-tin oxide (ITO). In addition, the connection method of the present invention is suitable when at least one of the wiring members includes a substrate containing an insulating organic material and / or glass. Furthermore, the connection method of the present invention can provide excellent adhesive strength even when at least one of the wiring members includes at least one of silicon nitride, silicone compound, and polyimide resin on the surface. .

  Furthermore, the present invention provides a wiring structure that includes two or more wiring members each having a connection terminal, and the connection terminals of the wiring members are electrically connected using the adhesive of the present invention.

  The wiring structure of the present invention includes, for example, a first wiring member having a first connection terminal and a second connection terminal having a second connection terminal with a cured product of the adhesive of the present invention interposed therebetween. The wiring member has a structure in which the first connection terminal and the second connection terminal are arranged to face each other, and the first connection terminal and the second connection terminal are electrically connected.

  BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 are explanatory views showing a connection process of wiring terminals.

(1) Curing agent that generates free radicals upon heating The curing agent that generates free radicals upon heating contained in the adhesive of the present invention decomposes upon heating of peroxides, azo compounds, and the like to generate free radicals. It is a substance. This curing agent can be appropriately selected depending on the intended connection temperature, connection time, pot life, etc., but the temperature of the half-life of 10 hours is 40 ° C. in terms of the high reactivity and the length of the pot life. Organic peroxides having a half-life temperature of 180 ° C. or less are preferred, organic peroxides having a half-life of 10 hours of 60 ° C. or more and a half-life of 1 minute of 170 ° C. or less Is more preferable.

  When the connection time is 10 seconds or less, the curing agent is blended in a radical polymerizable substance (in the case where a film forming material is blended, the radical polymerizable substance and the film forming material in order to obtain a sufficient reaction rate). Is preferably 0.1 to 30 parts by weight, more preferably 1 to 20 parts by weight with respect to 100 parts by weight. When the blending amount of the curing agent is less than 0.1 parts by weight, a sufficient reaction rate cannot be obtained, and good adhesive strength and small connection resistance tend to be difficult to obtain. When the blending amount exceeds 30 parts by weight, the fluidity of the adhesive is lowered, the connection resistance is increased, or the pot life of the adhesive tends to be shortened.

  Suitable curing agents for the present invention include diacyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, dialkyl peroxide, hydroperoxide, silyl peroxide and the like.

  In order to suppress corrosion of the connection terminals of the wiring member, the chlorine ions and organic acids contained in the curing agent are preferably 5000 ppm or less, and more preferably those that generate less organic acid after thermal decomposition. Specifically, peroxyesters, dialkyl peroxides, hydroperoxides, silyl peroxides and the like are suitable. In particular, it is desirable to select a curing agent from peroxyesters that can provide high reactivity. As the curing agent, one type of compound may be used, or two or more types of compounds may be appropriately used in combination.

  Peroxyesters suitable for the present invention include cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate. Ate, t-hexylperoxyneodecanoate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5 -Di (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy- 2-ethylhexanonate, t-butylperoxyisobutyrate, 1,1-bis (t-butylperoxy) silane Rhohexane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanonate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di (m- Toluoyl peroxy) hexane, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy-2-ethylhexyl monocarbonate, t-hexyl peroxybenzoate, t-butyl peroxyacetate and the like.

  Dialkyl peroxides suitable for the present invention include α, α′-bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy). Hexane, t-butyl cumyl peroxide, etc. are mentioned.

  Suitable hydroperoxides for the present invention include diisopropylbenzene hydroperoxide, cumene hydroperoxide, and the like.

  Diacyl peroxides suitable for the present invention include isobutyl peroxide, 2,4-dichlorobenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, sucrose. Sinic peroxide, benzoyl peroxytoluene, benzoyl peroxide and the like can be mentioned.

  Peroxydicarbonates suitable for the present invention include di (n-propyl) peroxydicarbonate, di (isopropyl) peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di (2- And ethoxyethyl) peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, di (methoxybutyl) peroxydicarbonate, and di (3-methyl-3-methoxybutyl) peroxydicarbonate.

  Peroxyketals include 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t- Butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclododecane, 2,2-bis (t-butylperoxy) decane and the like.

  Examples of silyl peroxides include t-butyltrimethylsilyl peroxide, bis (t-butyl) dimethylsilyl peroxide, t-butyltrivinylsilyl peroxide, bis (t-butyl) divinylsilyl peroxide, and tris (t-butyl). Examples thereof include vinylsilyl peroxide, t-butyltriallylsilyl peroxide, bis (t-butyl) diallylsilyl peroxide, and tris (t-butyl) allylsilyl peroxide.

  Of these curing agents that generate free radicals upon heating, one type of compound may be used alone, or two or more types of compounds may be used in combination. Moreover, you may use a decomposition accelerator, an inhibitor, etc. together with these hardening | curing agents.

  A material obtained by coating these curing agents with a polymer compound such as polyurethane or polyester and microencapsulating them is suitable for the present invention because the pot life is extended.

(2) Radical polymerizable substance The radical polymerizable substance contained in the adhesive of the present invention is a substance having a functional group that can be polymerized by radicals. Examples of the radical polymerizable substance include acrylates, methacrylates, maleimide compounds, and the like, and any state of monomers and oligomers may be used. Monomers and oligomers can be used in combination.

  Specific examples of acrylates and methacrylates suitable for the adhesive of the present invention include methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, 2-hydroxy-1,3-diaacryloxypropane, 2,2-bis [4- (acryloxymethoxy) phenyl] propane, 2,2-bis [4- (acryloxypolyethoxy) phenyl] propane, dicyclo Examples include pentenyl acrylate, tricyclodecanyl acrylate, tris (acryloyloxyethyl) isocyanurate, urethane acrylate, and the like and corresponding methacrylates. It is.

  The maleimide compound suitable for the adhesive of the present invention contains at least two maleimide groups in the molecule. Examples of such maleimide compounds include 1-methyl-2,4-bismaleimide benzene, N, N′-m-phenylene bismaleimide, N, N′-p-phenylene bismaleimide, N, N′-m. -Toluylene bismaleimide, N, N'-4,4-biphenylene bismaleimide, N, N'-4,4- (3,3'-dimethyl-biphenylene) bismaleimide, N, N'-4,4- (3,3′-dimethyldiphenylmethane) bismaleimide, N, N′-4,4- (3,3′-diethyldiphenylmethane) bismaleimide, N, N′-4,4-diphenylmethane bismaleimide, N, N ′ -4,4-diphenylpropane bismaleimide, N, N'-3,3'-diphenylsulfone bismaleimide, N, N'-4,4-diphenyl ether bisma Imido, 2,2-bis {4- (4-maleimidophenoxy) phenyl} propane, 2,2-bis {3-s-butyl-4,8- (4-maleimidophenoxy) phenyl} propane, 1,1- Bis {4- (4-maleimidophenoxy) phenyl} decane, 4,4′-cyclohexylidene-bis {1- (4-maleimidophenoxy) phenyl} -2-cyclohexylbenzene, 2,2-bis {4- ( 4-maleimidophenoxy) phenyl} hexafluoropropane and the like.

  Of these radically polymerizable substances, a compound having at least one of a dicyclopentenyl group, a tricyclodecanyl group and a triazine ring is preferable because the heat resistance of the cured adhesive is improved.

  In addition, these radically polymerizable substances may be used individually by 1 type, and may use 2 or more types together. If necessary, a polymerization inhibitor such as hydroquinone or methyl ether hydroquinone may be used as appropriate.

  In addition, it is preferable to use a radical polymerizable substance having a phosphate ester structure represented by the following chemical formula (I) in combination with the above-mentioned radical polymerizable substance because the adhesive strength on the surface of an inorganic substance such as a metal is improved.

（ただし、ｎは１，２又は３である）

(Where n is 1, 2 or 3)

  Such a radically polymerizable substance having a phosphoric ester structure is obtained by reacting anhydrous phosphoric acid with 2-hydroxyethyl (meth) acrylate, specifically, mono (2-methacryloyloxyethyl) acid. Examples thereof include phosphate and di (2-methacryloyloxyethyl) acid phosphate. These may use one type of compound independently, and may use 2 or more types together.

  The blending amount of the radical polymerizable substance having a phosphate ester structure is 0.1 part by weight based on 100 parts by weight of the total amount of the radical polymerizable substance (in the case where the film forming material is included, the total of the film forming material and the radical polymerizable substance). It is preferable to use 01 to 50 parts by weight, and more preferably 0.5 to 5 parts by weight. If it is less than 0.01 part by weight, it is difficult to improve the adhesive strength with the surface of an inorganic material such as metal, and if it exceeds 50 parts by weight, the expected curing characteristics may not be obtained.

(3) Silicone particles Silicone particles are prepared by, for example, adding a silane compound (methyltrialkoxysilane, partially hydrolyzed condensate thereof, etc.) to an alcohol aqueous solution whose pH is adjusted to be greater than 9 with a basic substance such as sodium hydroxide or ammonia. It can be obtained by adding, hydrolyzing and polycondensing this, or by copolymerization of organosiloxane.

  The adhesive of the present invention has a functional group such as a hydroxyl group, an epoxy group, a ketimine, a carboxyl group, or a mercapto group at the molecular terminal or inner molecular chain in order to improve dispersibility in a film-forming material or a radical polymerizable substance. Silicone particles are preferred.

  In this invention, even if the board | substrate which supports a connection terminal is a wiring member which consists of an insulating organic substance or glass by containing a silicone particle in an adhesive agent, the surface contains a silicon nitride, a silicone compound, or a polyimide resin. Even if it is a wiring member, very high adhesive strength is obtained. In addition, when the film forming material is used to form a film, the peelability from the support material is improved, so that the transferability to the electronic material to be connected using this film adhesive is improved.

  In the present invention, spherical or amorphous fine particles can be used as the silicone particles, and it is preferable to use fine particles having an average particle diameter of 0.1 μm to 20 μm. Further, silicone particles in which particles having an average particle size or less occupy 80% by weight or more of the particle size distribution of the fine particles are preferable, and those obtained by treating the particle surface with a silane coupling agent are particularly preferable because dispersibility in the resin is improved.

  The elastic modulus at room temperature (25 ° C.) of the silicone particles in the adhesive of the present invention is preferably from 0.1 to 100 MPa, and in order to reduce the dispersibility of the particles and the interfacial stress at the time of connection, the elastic modulus is set to 1 to 30 MPa. More preferred. The elastic modulus specified here is the elastic modulus of silicone rubber obtained by polymerizing a silane compound (alkoxysilane compound, partially hydrolyzed condensate thereof, etc.) that is a raw material of silicone particles, and is measured by dynamic viscoelasticity measurement. Measured.

  Silicone particles can be directly mixed with radically polymerizable substances, curing agents that generate free radicals upon heating, and film-forming materials, but they can be easily dispersed in film-forming materials and radically polymerizable substances, so they are dispersed in organic solvents. It is preferable to mix with these after having been made.

  The blending amount of the silicone particles is preferably 5 to 200 parts by weight with respect to 100 parts by weight of the total amount of the radical polymerizable substance (when the film forming material is included, the total of the radical polymerizable substance and the film forming material), 10-50 weight part is more preferable. When the amount is less than 5 parts by weight, good adhesion strength to the substrate supporting the connection terminals and the surface of the wiring member and releasability from the support material become inferior. On the other hand, when the amount exceeds 200 parts by weight, the cohesive force of the adhesive is lowered, and there is a possibility that good adhesion cannot be obtained.

(4) Film forming material Examples of the film forming material suitable for the present invention include polyvinyl formal resin, polystyrene resin, polyvinyl butyral resin, polyester resin, polyamide resin, xylene resin, phenoxy resin, polyurethane resin and the like.

  A film-forming material is a material that, when a liquid composition is solidified into a film shape, can be handled as a film in a normal state, that is, good mechanical properties as a film (film to be formed Is easy to handle, and the film is imparted with characteristics such as that the film is not easily torn, broken, or sticky. In view of ease of handling as a film, a film capable of forming a self-supporting film is particularly preferable.

  Among the compounds capable of imparting such characteristics, it is preferable to use a phenoxy resin because it is excellent in adhesiveness, compatibility, heat resistance, and mechanical strength. The phenoxy resin can be obtained by reacting a bifunctional phenol and epihalohydrin to a high molecular weight, or by polyadding a bifunctional epoxy resin and a bifunctional phenol.

  Specifically, for example, by reacting 1 mol of a bifunctional phenol and 0.985 to 1.015 mol of epihalohydrin in a non-reactive solvent at 40 to 120 ° C. in the presence of an alkali metal hydroxide. Obtainable.

  From the viewpoint of the mechanical properties and thermal properties of the resin, in particular, the mixing equivalent ratio of the bifunctional epoxy resin and the difunctional phenols is epoxy group / phenol hydroxyl group = 1 / 0.9 to 1/1. 1 in an organic solvent such as an amide, ether, ketone, lactone, or alcohol having a boiling point of 120 ° C. or higher in the presence of a catalyst such as an alkali metal compound, an organic phosphorus compound, or a cyclic amine compound. The reaction solid content is preferably 50 parts by weight or less, and is obtained by heating to 50 to 200 ° C. to cause a polyaddition reaction.

  Examples of the bifunctional epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, and bisphenol S type epoxy resin. Bifunctional phenols are compounds having two phenolic hydroxyl groups, and examples thereof include hydroquinones, bisphenols such as bisphenol A, bisphenol F, bisphenol AD, and bisphenol S. The phenoxy resin may be modified with a radical polymerizable functional group.

(5) Conductive Particles The adhesive of the present invention can be electrically connected by direct contact of the wiring terminals to be connected, and therefore does not need to contain conductive particles in particular. However, when the conductive particles are contained, the adhesive is more stable. This is preferable because a connection can be obtained.

  Examples of the conductive particles suitable for the present invention include metal particles such as Au, Ag, Ni, Cu, and solder, and carbon particles. In order to obtain a sufficient pot life, it is preferable that noble metals such as Au, Ag and white metals are the surface layer, not transition metals such as Ni and Cu, and the surface is particularly preferably Au. Further, particles in which the surface of a transition metal such as Ni is coated with a noble metal such as Au are also suitable for the present invention.

  In addition, by forming a conductive layer made of the above-mentioned metal on the particle surface of non-conductive glass, ceramic, plastic, etc., composite particles with the outermost layer as noble metals and hot-melt metal particles are heated and pressurized. Therefore, it is suitable for the present invention because the contact area with the electrode increases at the time of connection and the reliability is improved.

  When using composite particles having a noble metal coating layer on the surface, the thickness of the coating layer is preferably 100 angstroms or more in order to obtain good resistance. In particular, when a noble metal layer is formed on a transition metal such as Ni, free radicals are generated due to the redox effect caused by the loss of the noble metal layer generated when the conductive particles are mixed and dispersed, resulting in a decrease in storage stability. In order to avoid this, the thickness of the coating layer made of noble metals is preferably 300 angstroms or more. However, since the effect is not improved in proportion to the thickness even if it is thicker than 1 μm, it is usually desirable that the thickness of the coating layer be 1 μm or less, but the present invention is limited to this. It is not a thing.

  The conductive particles are properly used in the range of 0.1 to 30 parts by volume with respect to 100 parts by volume of the adhesive resin component. In order to prevent the adjacent wiring from being short-circuited by excessive conductive particles, the amount is more preferably 0.1 to 10 parts by volume.

  In addition, when it is set as the structure where electroconductive particle does not contact with a hardening | curing agent, a pot life can be improved further. That is, a multilayer of two or more layers in which a first layer made of the adhesive of the present invention containing no conductive particles and a second layer made of an adhesive containing conductive particles instead of a curing agent are laminated. A film-like adhesive having a structure is preferable because of its long pot life.

(6) Other additives In the adhesive of the present invention, allyl acrylate and / or allyl methacrylate may be blended as necessary for improving the adhesive strength. The blending amount may be 0.1 to 10 parts by weight with respect to 100 parts by weight of the total amount of the radical polymerizable substance (when the film forming material is contained, the total of the film forming material and the radical polymerizable substance). Preferably, the amount is 0.5 to 5 parts by weight. If the amount is less than 0.1 parts by weight, the effect of improving the adhesive strength is not sufficiently exhibited. If the amount exceeds 10 parts by weight, the radical polymerization reactivity is low, resulting in insufficient reaction, making it difficult to obtain good adhesive strength.

  The adhesive of the present invention can be blended with a polymer or copolymer containing at least one of acrylic acid, acrylic acid ester, methacrylic acid ester and acrylonitrile as a monomer component. In particular, a copolymer-based acrylic rubber containing a glycidyl acrylate and / or glycidyl methacrylate monomer containing a glycidyl ether group is preferable because it is excellent in stress relaxation. The weight average molecular weight of these acrylic rubbers is preferably 200,000 or more from the viewpoint of increasing the cohesive strength of the adhesive.

  The adhesive of the present invention further includes fillers, softeners, accelerators, anti-aging agents, colorants, flame retardants, thixotropic agents, coupling agents, resins (such as phenolic resins and melamine resins), And isocyanates etc. may be blended.

  The blending of the filler is preferable because the connection reliability and the like are improved. When using a filler, the maximum diameter of the particles is less than the particle diameter of the conductive particles. Moreover, it is preferable that the compounding quantity shall be 5-60 volume parts with respect to 100 volume parts of resin components in an adhesive agent. If it exceeds 60 parts by volume, the effect of improving the reliability may be saturated, and if it is less than 5 parts by volume, the effect of addition is small.

  As the coupling agent, ketimine, vinyl group, acrylic group, amino group, epoxy group, and isocyanate group-containing material are suitable for the present invention from the viewpoint of improving adhesiveness.

  Examples of the silane coupling agent having an amino group include N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, and γ-amino. Examples thereof include propyltriethoxysilane and N-phenyl-γ-aminopropyltrimethoxysilane.

  Examples of the silane coupling agent having ketimine include those obtained by reacting the above-mentioned silane coupling agent having an amino group with a ketone compound such as acetone, methyl ethyl ketone, and methyl isobutyl ketone.

(7) Applications The adhesive of the present invention can also be used as a film adhesive for bonding an IC (integrated circuit) chip and a chip mounting substrate, or for bonding electric wirings to each other. That is, a book formed into a film shape between a first wiring member having a first connection terminal and a second wiring member having a second connection terminal arranged so that the connection terminals face each other. The adhesive (film adhesive) of the invention is interposed, and the first connection terminal and the second connection terminal can be electrically connected by heating and pressing.

  Examples of wiring members suitable for connection according to the present invention include chip components such as semiconductor chips, resistor chips, and capacitor chips, and substrates such as printed boards. These wiring members are usually provided with a large number of connection terminals (or one in some cases). At least one set of the wiring members is disposed with the adhesive of the present invention interposed therebetween so that at least a part of the connection terminals provided on the wiring members are opposed to each other, and the connection terminals are opposed to each other by applying pressure while heating. A wiring structure (such as a wiring board) including two or more wiring members can be manufactured by electrically connecting the two. In addition, conduction | electrical_connection of the wiring terminal formed by this may be implement | achieved by the direct contact of a wiring terminal, and may be implement | achieved through the electroconductive particle in an adhesive agent.

  For the connection of the wiring terminals of the present invention, for example, an adhesive layer is formed on the surface of the first connection terminal (circuit electrode), and the connection terminal is opposed to the second connection terminal (circuit electrode) on this surface. Thus, it can be performed by aligning, heating and pressurizing. Formation of the adhesive layer may be performed by application of a liquid adhesive or the like, or may be performed by placing a film adhesive.

(8) Physical properties of the adhesive The adhesive of the present invention melts and flows at the time of connection and connects opposite wiring terminals, and then hardens to maintain the connection. For this reason, the fluidity of the adhesive is an important factor. The adhesive of the present invention sandwiches the adhesive of the present invention having a thickness of 35 μm, 5 mm × 5 mm between two pieces of glass having a thickness of 0.7 mm and 15 mm × 15 mm, under the conditions of 150 ° C., 2 MPa, and 10 seconds. When heating and pressurization are performed, the value of fluidity (B) / (A) expressed using the initial area (A) and the area after heat pressurization (B) is 1.3 to 3. 0 is preferable, and 1.5 to 2.5 is more preferable. If it is less than 1.3, fluidity may be poor and good connection may not be obtained. If it exceeds 3.0, bubbles are likely to be generated and reliability may be poor.

  Moreover, it is preferable that the elasticity modulus in 25 degreeC after hardening is 100-3000 MPa, and, as for the adhesive agent of this invention, it is more preferable that it is 300-2000 MPa. When the elastic modulus is in this range, the internal stress of the resin after connection is reduced, which is advantageous for improving the adhesive force and good conduction characteristics can be obtained.

  The adhesive of the present invention has a heating value rising temperature (Ta) of 70 ° C. to 110 ° C. and a peak temperature (Tp) in a measurement at a heating rate of 10 ° C./min with a differential scanning calorimeter (DSC). It is preferable that Ta + 5 to 30 ° C. and the end temperature (Te) is 160 ° C. or less.

A. Preparation of adhesive <Example 1>
(1) Synthesis of urethane acrylate 400 parts by weight of polycaprolactone diol having an average molecular weight of 800, 131 parts by weight of 2-hydroxypropyl acrylate, 0.5 parts by weight of dibutyltin dilaurate as a catalyst, and hydroquinone monomethyl ether as a polymerization inhibitor 0 part by weight was mixed by heating to 50 ° C. with stirring. Next, 222 parts by weight of isophorone diisocyanate was added dropwise, and the mixture was further heated to 80 ° C. with stirring to conduct a urethanization reaction. After confirming that the reaction rate of the isocyanate group reached 99% or more, the reaction temperature was lowered to obtain urethane acrylate A.

(2) Synthesis of Silicone Particles Silicone particles were obtained by adding methyltrimethoxysilane to an aqueous alcohol solution having a pH of 12 maintained at 20 ° C. while stirring at 300 rpm, followed by hydrolysis and condensation. The obtained silicone particles had an elastic modulus at 25 ° C. of 8 MPa and an average particle size of 2 μm.

(3) Preparation of conductive particles As for conductive particles, a nickel layer having a thickness of 0.2 μm is provided on the surface of particles having polystyrene as a core, and a gold layer having a thickness of 0.04 μm is provided outside the nickel layer. It was prepared by. The average particle diameter of the obtained conductive particles was 10 μm.

(4) Preparation of adhesive 100 parts by weight of the silicone particles obtained in the step (2) were dispersed in 100 parts by weight of a mixed solvent of toluene / ethyl acetate = 50/50 by weight.

  In solid weight ratio, 99 g of urethane acrylate A obtained in step (1), 1 g of phosphate ester acrylate (manufactured by Kyoei Chemical Co., Ltd., trade name: P2M), 30 g of silicone particles, t-hexylperoxy- The mixture was blended so that 2-ethylhexanonate (free radical generator) was 5 g, and further 3% by volume of the conductive particles obtained in the step (3) were mixed and dispersed to obtain a liquid adhesive.

<Example 2>
50 g of phenoxy resin (manufactured by Union Carbide Co., Ltd., trade name PKHC, average molecular weight 45000) in weight ratio with toluene (boiling point 110.6 ° C., SP value 8.90) / ethyl acetate (boiling point 77.1 ° C., SP value 9) .10) = dissolved in a 50/50 mixed solvent to obtain a solution having a solid content of 40% by weight.

  In a solid weight ratio, 50 g of phenoxy resin, 49 g of urethane acrylate A, 1 g of phosphate ester acrylate, 5 g of t-hexylperoxy-2-ethylhexanate, 5 g of silicone particles, Conductive particles are mixed and dispersed at 3% by volume, and the resulting liquid is applied to a PET (polyethylene terephthalate) film having a surface treated on one side with a thickness of 80 μm using a coating device and dried with hot air at 70 ° C. for 10 minutes. Thus, a film adhesive having a thickness of 20 μm was obtained.

<Examples 3 to 5>
The solid weight ratio of phenoxy resin / urethane acrylate A / phosphate ester acrylate / silicone particles / t-hexylperoxy-2-ethylhexanate was 50 g / 49 g / 1 g / 20 g / 5 g (Example 3), 30 g / A film adhesive was obtained in the same manner as in Example 2 except that 69 g / 1 g / 10 g / 5 g (Example 4) and 30 g / 40 g / 30 g / 10 g / 5 g (Example 5).

<Comparative Example 1>
The process of Example 1 except that the solid weight ratio of urethane acrylate A / phosphate ester acrylate / t-hexylperoxy-2-ethylhexanonate was 99 g / 1 g / 5 g and no silicone particles were added. A liquid adhesive was obtained in the same manner as in 4).

<Comparative example 2>
A film adhesive was obtained in the same manner as in Example 2 except that the silicone particles were not used.

B. Evaluation Method of Adhesive (1) Fabrication of Wiring Structure First, an ITO substrate (surface resistance <20Ω / □) formed by vapor deposition of indium-tin oxide (ITO) wiring 12 on the surface of a glass 11 having a thickness of 1.1 mm. ) An adhesive layer 15 made of an adhesive 13 containing conductive particles 14 (prepared in each of the examples and comparative examples) was formed on the surface on which the wiring 12 of FIG. 10 (FIG. 1A) was formed. (FIG. 1 (b)).

  The adhesive layer 15 is formed by applying an adhesive in Examples 1 and Comparative Example 1 where the adhesive is liquid, and Examples 2 to 5 and Comparative Example 2 in which the adhesive is a film. Then, it was performed by attaching an adhesive, heating and pressurizing at 70 ° C. and 0.5 MPa for 5 seconds for temporary connection, and then peeling the PET film.

  A flexible wiring board in which a polyimide layer 18 and a copper foil (thickness: 18 μm) are attached to the surface of the adhesive layer 15 with an adhesive 17, and the copper foil is patterned to form wiring 16 having a line width of 50 μm and a pitch of 100 μm. (Three-layer FPC) 19 is placed (FIG. 1 (c)), heated and pressurized at 160 ° C. and 3 MPa for 10 seconds, and connected over a width of 2 mm to obtain a wiring structure 21 shown in FIG. 1 (d). It was.

  In place of the three-layer FPC, a flexible wiring board (two-layer FPC) 24 in which 500 copper circuits 23 having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm are formed on the surface of a polyimide film (thickness 100 μm) 22 is used. (FIG. 2 (a)) was connected to the ITO substrate in the same manner to obtain a wiring structure 25 (FIG. 2 (b)).

(2) Measurement of connection resistance After manufacturing the wiring structure as described above, the resistance value between adjacent circuits of the FPC including the wiring connection portion is measured with a multimeter immediately after the manufacturing. After holding for 500 hours in a high temperature and high humidity bath at 85 ° C. and 85% RH, the resistance value was measured in the same manner. The resistance value is shown as an average of 150 resistances between adjacent circuits.

(3) Measurement of adhesive strength The wiring structure produced as described above was subjected to a 90-degree peeling test at a peeling speed of 50 mm / min to measure the adhesive strength.

(4) Evaluation of insulation First, on the surface on which the circuit of the printed circuit board having the comb-shaped circuit in which 250 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm are alternately arranged is formed in the same manner as in (1). Then, an adhesive layer was formed. Next, a flexible wiring board (FPC) having 500 copper circuits having a line width of 50 μm, a pitch of 100 μm, and a thickness of 18 μm is placed on the surface of the adhesive layer, and heated and pressed at 160 ° C. and 3 MPa for 10 seconds. And connected over a width of 2 mm to obtain a wiring structure. The insulation resistance value was measured by applying a voltage of 100 V to the comb circuit of this wiring structure, and the insulation resistance value after conducting a high temperature and high humidity test at 85 ° C. and 85% RH for 500 hours was measured.

(5) Evaluation of fluidity An adhesive to be evaluated having a size of 5 mm × 5 mm and a thickness of 35 μm is sandwiched between two sheets of 15 mm × 15 mm and a thickness of 0.7 mm, and heated and pressed at 150 ° C. and 2 MPa for 10 seconds. The value of fluidity (B) / (A) was determined using the initial area (A) and the area (B) after heating and pressing.

(6) Elastic modulus after curing The liquid adhesive (Example 1, Comparative Example 1) was poured into a mold, heated at 160 ° C. for 1 minute, and cured to obtain a rod-shaped cured product. Film-like adhesives (Examples 2 to 5 and Comparative Example 2) were immersed in 160 ° C. oil for 1 minute and cured to obtain a film-like cured product. The storage elastic modulus of these cured products was measured using a dynamic viscoelasticity measuring device (temperature increase rate 5 ° C./min, 10 Hz), and the elastic modulus at 25 ° C. was determined.

(7) Measurement of DSC Using the adhesive obtained in each Example and Comparative Example, the rising temperature (Ta) of the exothermic reaction with a differential scanning calorimeter (DSC, manufactured by TA Instruments, product name 910 type), Peak temperature (Tp) and end temperature (Te) were determined. The temperature increase rate in the measurement was 10 ° C./min.

C. Results Table 1 shows the results of the above evaluation methods.

  Silicone particles are not blended in the adhesives of Comparative Examples 1 and 2. On the other hand, Examples 1-5 which mix | blended silicone particle | grains are comparative examples even if it is 2 layer FPC which the polyimide resin exposed to the board | substrate surface which supports a connection terminal, and 3 layer FPC which the adhesive agent exposed. Compared to this, the adhesive strength was greatly improved. Moreover, the adhesive force after moisture absorption was also large.

  As described above, according to the present invention, even if the substrate supporting the connection terminal is a wiring member made of an insulating organic material such as polyimide resin or glass, the wiring member having a silicone resin or polyimide resin on the surface is also used. Even if it exists, favorable adhesive strength can be obtained and a wiring structure with high connection reliability can be manufactured.

It is explanatory drawing which shows the connection process of a wiring terminal. It is explanatory drawing which shows the connection process of a wiring terminal.

Claims (14)

A curing agent that generates free radicals upon heating;
A radical polymerizable substance;
An adhesive for connecting a wiring terminal, comprising silicone particles having an elastic modulus at 25 ° C. of 0.1 to 100 MPa and an average particle diameter of 0.1 to 20 μm. The content of the silicone particles is
The adhesive for connecting a wiring terminal according to claim 1, wherein the amount is 5 to 200 parts by weight with respect to 100 parts by weight of the radical polymerizable substance.   The adhesive for connecting a wiring terminal according to claim 1, further comprising a film forming material.   The wiring terminal connecting adhesive according to claim 3, wherein the film forming material is a phenoxy resin. The content of the silicone particles is
The adhesive for connecting a wiring terminal according to claim 3 or 4, wherein the adhesive is 5 to 200 parts by weight with respect to 100 parts by weight in total of the radical polymerizable substance and the film forming material.   The adhesive for connecting a wiring terminal according to any one of claims 1 to 5, further comprising conductive particles. The adhesive for wiring terminal connection in any one of Claims 1-6 whose average particle diameter of the said silicone particle is 2-20 micrometers. A composition comprising a curing agent that generates free radicals upon heating, a radical polymerizable substance, and silicone particles having an elastic modulus at 25 ° C. of 0.1 to 100 MPa and an average particle size of 0.1 to 20 μm. A first layer comprising:
A second layer comprising a conductive particle, a radical polymerizable substance, and a composition containing silicone particles having an elastic modulus at 25 ° C. of 0.1 to 100 MPa and an average particle size of 0.1 to 20 μm. A film-like adhesive for connecting a wiring terminal.   The film adhesive for wiring terminal connection according to claim 8, wherein the silicone particles have an average particle diameter of 2 to 20 μm. Between the connection terminals provided respectively in two or more wiring members are electrically connected with wiring terminals for connecting adhesive according to any one of claims 1 to 9 method of connecting wiring terminals. At least one of the connection terminals is
The method for connecting wiring terminals according to claim 10 , wherein the surface is made of at least one selected from gold, silver, tin, a platinum group metal, and indium-tin oxide. At least one of the wiring members is
The connection method of the wiring terminal of Claim 10 or 11 provided with the board | substrate containing at least any one of an insulating organic substance and glass. At least one of the wiring members is
On the surface, silicon nitride, comprises at least one selected from silicone compounds and polyimide resins, a method of connecting wiring terminals according to any one of claims 10-12. Two or more wiring members each having a connection terminal are provided, and the connection terminals of the wiring members are electrically connected using the wiring terminal connection adhesive according to any one of claims 1 to 9 . Wiring structure.

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