JP2013125598A - Film-like anisotropic conductive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film-like anisotropic conductive adhesive having improved adhesive strength and connection reliability in a polymerizable (meth) acrylic curable film-like anisotropic conductive adhesive.
SOLUTION: A film-form conductive material comprising (A) a film-forming resin, (B) a polymerizable (meth) acrylic compound, (C) a thermoplastic elastomer, (D) a polymerization initiator, and (E) conductive particles. Adhesive. (C) The thermoplastic elastomer is preferably a polyamide-based thermoplastic elastomer, and the content relative to the total amount of the resin is preferably 2 to 40% by mass.
[Selection figure] None

Description

  The present invention relates to a film-like anisotropic conductive adhesive used for bonding circuit boards such as LCD glass panels and flexible printed wiring boards (FPCs), and particularly using a polymerizable (meth) acrylic compound. The present invention relates to a low-temperature fast-curing film-like anisotropic conductive adhesive.

  A film in which conductive particles are dispersed in an insulating resin composition as an adhesive to be bonded while maintaining electrical connection between circuit boards such as a glass panel of an LCD and a flexible printed circuit board (FPC). An anisotropic conductive adhesive is used. For example, as shown in FIG. 1, an LCD glass panel 1 in which electrodes 1a, 1a,... Are juxtaposed at a predetermined interval, and a flexible printed wiring board (FPC) 2 in which electrodes 2a, 2a are juxtaposed at a predetermined interval. When the film-like anisotropic conductive adhesive 3 is placed and heated and pressed with a pressing tool 5 (cushion material 4 may be interposed), the resin in the adhesive flows, Between the electrodes (between 1a and 2a), which are embedded in the gaps between the electrodes formed between the circuit boards 1 and 2 (between 1a and 1a, between 2a and 2a), and at the same time a part of the conductive particles are opposed ) To achieve electrical connection. Therefore, the film-like anisotropic conductive adhesive is capable of flowing into the gap between the electrodes on each circuit board (between 1a and 2a) by heating and pressing, and between the connected electrodes facing each other in the joined body ( Connection reliability and adhesive strength are required to maintain an electrical connection between 1a and 2a.

  As such an anisotropic conductive film, conventionally, a resin composition in which an epoxy resin and a latent curing agent are combined is used from the viewpoint of heat resistance, moisture resistance, and insulation.

  In recent years, from the viewpoint of cost reduction and high productivity, a low-temperature fast-curing adhesive composition has been demanded. As an adhesive resin composition that meets such a demand, an acrylate derivative having radical polymerizability and ( Attention has been focused on radical polymerization curable adhesives comprising a combination of a (meth) acrylate derivative and a radical polymerization initiator. Such radical curable adhesives can be cured at a low temperature and in a short time as compared with a combination of an epoxy resin and a latent curing agent, because radicals that are reactive species are highly reactive.

  However, a polymerization and curing type adhesive composition using a (meth) acrylate derivative generally has a larger curing shrinkage than an adhesive composition using an epoxy resin. For this reason, voids are likely to occur in the cured adhesive portion, and as a result, the adhesive strength is low and the connection resistance is high and the connection reliability is inferior compared to a bonded body using an epoxy resin type adhesive. Are known.

  For these reasons, studies are underway to improve the adhesive strength of radical curable adhesives using (meth) acrylate derivatives.

  For example, Japanese Unexamined Patent Application Publication No. 2010-111847 (Patent Document 1) proposes the inclusion of a vinyl compound having a phosphate group, and Japanese Unexamined Patent Application Publication No. 2011-37953 (Patent Document 2) further discloses radicals. It has been proposed to use an acrylate derivative having a special structure as the polymerizable compound.

  Japanese Patent Application Laid-Open No. 2011-32491 (Patent Document 3) relates to an anisotropic conductive film having a two-layer structure in which a conductive particle-containing layer is laminated on an insulating adhesive layer. It has been proposed to contain a thiol compound in each of the particle-containing layers.

  Japanese Patent Application Laid-Open No. 2010-106261 (Patent Document 4) includes polybutadiene particles as a stress relieving agent, and dicyclopentanyl (meth) acrylic monomer and urethane (meth) acrylate as radical polymerizable compounds. It has been proposed to include any of the oligomers.

  Furthermore, in JP-A-2006-190644 (Patent Document 5), two types of polymerizable acrylate compounds are used, a silane group-containing resin is used as a resin for film formation, and a carboxyl group or an epoxy group is contained. A conductive adhesive for film in which a rubber (paragraph numbers 0021-0022) obtained by reacting rubber with an organic reactive silane has been proposed.

  Furthermore, Japanese Patent Application Laid-Open No. 2006-8978 (Patent Document 6) proposes adding a crosslinkable rubber-like resin (EPDM and butyl rubber are used in Examples).

JP 2010-111847 A JP 2011-37953 A JP 2011-32491 A JP 2010-106261 A JP 2006-190644 A JP 2006-8978 A

  As described above, although various proposals have been made for the polymerizable (meth) acrylic compound, the film-forming resin, and other compounding components, there are still no satisfactory ones.

  The present invention has been made in view of such circumstances, and in a polymerizable (meth) acrylic curable film-like anisotropic conductive adhesive, a film-like anisotropic conductive material having improved adhesive strength and connection reliability. It is in providing an adhesive.

  In order to improve the adhesive strength when a polymerizable (meth) acrylic curable film-like anisotropic conductive adhesive is used, the present inventors have prepared a component other than a film-forming resin and a polymerizable (meth) acrylic compound. We focused on and examined. In order to suppress a decrease in adhesive strength due to cure shrinkage, it was considered effective to add a polymer component serving as a stress relaxation agent, and further studies were made, and the present invention was completed.

  The film-like anisotropic conductive adhesive of the present invention comprises (A) a film-forming resin, (B) a polymerizable (meth) acrylic compound, (C) a thermoplastic elastomer, (D) a polymerization initiator, and (E ) Contains conductive particles.

  The (C) thermoplastic elastomer is preferably a polyamide-based thermoplastic elastomer. Moreover, it is preferable that the content rate with respect to the resin whole quantity of the said (C) thermoplastic elastomer is 2-40 mass%.

  The (B) polymerizable acrylic compound preferably contains epoxy acrylate and urethane acrylate. The (A) film-forming resin is preferably a phenoxy resin.

  In the present specification, when acryl and methacryl are not particularly distinguished, they are referred to as “(meth) acryl”. Similarly, when acrylate and methacrylate are not particularly distinguished, “(meth) acrylate” is particularly distinguished from acryloyl and methacryloyl. If not, it is referred to as “(meth) acryloyl”.

  Since the film-like anisotropic conductive adhesive of the present invention uses a thermoplastic elastomer as a relaxation of curing shrinkage due to polymerization, it impairs the low-temperature rapid curing property by using a polymerizable (meth) acrylic compound. Therefore, it is possible to improve the adhesive strength and the connection reliability.

It is a figure for demonstrating joining of the circuit boards using a film-like anisotropic conductive adhesive.

  Although embodiments of the present invention will be described below, it should be considered that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[Film-like anisotropic conductive adhesive]
The film-like anisotropic conductive adhesive of the present invention comprises (A) a film-forming resin, (B) a polymerizable (meth) acrylate compound, (C) a thermoplastic elastomer, (D) a polymerization initiator, and (E ) An adhesive composition containing conductive particles is formed into a film.

[Adhesive composition]
First, an adhesive composition that is a raw material for the film-like anisotropic conductive adhesive of the present invention will be described.
(A) Film-forming resin The film-forming resin used in the present invention is softened so that the film state is maintained at room temperature and the polymerizable (meth) acrylate compound can be dispersed at the polymerization reaction temperature. A phenoxy resin corresponding to a high molecular weight epoxy resin is preferably used from the viewpoint of heat resistance and insulation, which is a thermoplastic resin having fluidity.

  A phenoxy resin corresponds to a high molecular weight epoxy resin and has a degree of polymerization (n) of about 100 or more. The phenoxy resin used in the present invention has a weight average molecular weight measured by GPC of 30,000 or more, preferably 40,000 or more, more preferably 45000 or more. The phenoxy resin corresponding to such a high molecular weight epoxy resin usually has a softening point of about 80 to 150 ° C. and is solid at room temperature. Since it behaves as a thermoplastic resin, it has good film formability.

  The kind of phenoxy resin used in the present invention is not particularly limited. For example, bisphenol A type, bisphenol F type, bisphenol S type phenoxy resin, copolymer type phenoxy resin of bisphenol A type and bisphenol F type, distilled product thereof, naphthalene type phenoxy resin, novolac type phenoxy resin, biphenyl type phenoxy resin, cyclo A pentadiene type phenoxy resin or the like can be used. Of these, bisphenol A-type phenoxy resins are preferably used from the viewpoint of film formability and heat resistance.

  The phenoxy resin is preferably contained in an amount of 20 to 60% by mass, more preferably 25 to 50% by mass, based on the total amount of the resin. If it is less than 20% by mass, it becomes difficult to maintain the solidity of the entire composition, and it tends to be difficult to produce a film-like anisotropic conductive adhesive. Here, the total amount of resin refers to the total amount of components present as a resin in the resulting cured product, (A) film-forming resin, (B) polymerizable (meth) acrylic compound, (C) heat When a plastic elastomer, (D) a polymerization initiator, and other resin (F) to be described later are included, it means the total amount of other resins added (the same applies hereinafter).

(B) Polymerizable (meth) acrylic compound The polymerizable (meth) acrylic compound is a (meth) acrylic compound that initiates radical polymerization and cures with a polymerization initiator described later. Monomers or oligomers having one or more acryloyl groups, preferably two or more, (meth) acrylate monomers, and compounds in which molecular chain ends such as epoxy resins, urethanes and polyols are modified with (meth) acryloyl groups Can be mentioned.

  Specific examples of the (meth) acrylic monomer include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylic acid-n-butyl, acrylic acid-n-butyl, acrylic acid isobutyl, methacrylic acid. Isobutyl acid, isopentyl acrylate, isopentyl methacrylate, acrylic acid-n-hexyl, methacrylic acid-n-hexyl, isooctyl acrylate, isooctyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, acrylic acid Carbon of (meth) acrylic acid such as n-octyl, n-octyl methacrylate, isononyl acrylate, isononyl methacrylate, acrylic acid-n-decyl, methacrylic acid-n-decyl, isodecyl acrylate, isodecyl methacrylate 1-10, preferably 1-6 alkyl esters; epoxy-containing (meth) acrylates such as glycidyl acrylate, glycidyl methacrylate, acryl glycidyl ether; acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, etc. α, β-unsaturated carboxylic acids; hydroxyl group-substituted (meth) acrylates such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; amide-containing acrylic monomers such as acrylamide and methacrylamide, and cyano groups such as acrylonitrile Examples include acrylic monomers. These may be used alone or in admixture of two or more.

  In addition, oligomers having two or more (meth) acryloyl groups include oligomers such as epoxy (meth) acrylate oligomers, urethane (meth) acrylate oligomers, polyether (meth) acrylate oligomers, polyester (meth) acrylate oligomers, and trimethylol. Propane tri (meth) acrylate, polyethylene glycol di (meth) acrylate, polyalkylene glycol di (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, neopentyl glycol di (meth) Acrylate, dipentaerythritol hexa (meth) acrylate, isocyanuric acid modified bifunctional (meth) acrylate, isocyanuric acid modified trifunctional (meth) acrylate, Add (meth) acrylic acid to the glycidyl group of epoxy (meth) acrylate, bisphenoxyethanol fluorene acrylate, or bisphenol fluorenediglycidyl ether with (meth) acrylic acid added to the glycidyl group of sphenoxyethanol fluorene acrylate or bisphenol fluorenediglycidyl ether. Examples thereof include compounds obtained by introducing a (meth) acryloyloxy group into a compound obtained by adding ethylene glycol or propylene glycol to the glycidyl group of epoxy (meth) acrylate or bisphenol fluorenediglycidyl ether. These may be used alone or in admixture of two or more. Furthermore, each of these oligomers may be used by mixing with the above (meth) acrylic monomer.

  The polymerizable (meth) acrylic compound as described above starts radical polymerization and cures by the action of radicals generated from the (D) polymerization initiator by heating. Moreover, since the polymer obtained is generally dissolved in a general-purpose solvent such as acetone, ketone, and alcohol, it is excellent in solvent wiping ease (repairability) when reusing defective products such as poor bonding.

  The polymerizable (meth) acrylic compound in the adhesive composition is preferably 20 to 50% by mass, more preferably 30 to 50% by mass, based on the total amount of the resin.

(C) Thermoplastic elastomer A thermoplastic elastomer is softened by heating and exhibits fluidity, and can behave as a rubber-like elastic body at room temperature. Thermoplastic elastomers tend to have a lower melt viscosity at higher temperatures, so the fluidity of the adhesive composition decreases as the polymerization reaction of the polymerizable (meth) acrylic compound initiated by heat and pressure progresses. It can melt and flow to contribute to the reduction of the gap between the counter electrodes (between 1a and 2a in FIG. 1). In addition, the residual stress generated in the adhesive interface and inside the adhesive due to the curing shrinkage of the polymerizable (meth) acrylic compound is relieved, and after hardening, the stress is relieved due to deformation at the joint based on the rubbery elasticity. Since it can act as a material, it can contribute to an increase in adhesive strength. Moreover, since it is soluble in a solvent, it does not impair the ease of wiping off the acrylic resin.

Examples of the thermoplastic elastomer used in the present invention include a styrene thermoplastic elastomer, a polyamide thermoplastic elastomer, a polyolefin thermoplastic elastomer, a polyester thermoplastic elastomer, a polyvinyl chloride thermoplastic elastomer, and a polyurethane thermoplastic elastomer. Etc. can be used. These may be used alone or in combination of two or more.
The molecular structure of the thermoplastic elastomer used in the present invention is not particularly limited, and may be any of a triblock copolymer type, a tetrablock copolymer type, a multiblock copolymer type, a star block copolymer type, and the like.

  Of these, polyamides are compatible with phenoxy resins and acrylate resins, have excellent adhesion to polyimides used for flexible printed wiring boards as adherends, and are soluble in alcohols and ketone solvents. An elastomer is preferably used.

  The polyamide-based elastomer is a block copolymer having nylon as a hard segment and polyester and / or polyol as a soft segment, and the type thereof is not particularly limited. Polyamide based on polymerized fatty acid is used as a hard segment, and polyether ester and polyester are used. A polyamide-based elastomer for the soft segment is preferably used. Since such a polyamide-based elastomer is thermoplastic, it can be melted and flowed quickly in the heating of the film-like anisotropic conductive adhesive. Therefore, even if the heating temperature is less than 200 ° C., the gap between the electrodes on the same substrate can be reduced. The fluidity that can flow in, and the flexibility that can narrow the distance between the opposing electrodes by pressurization. In addition, the specific gravity is about 1.0 to 1.2 and is about the same as the specific gravity of the phenoxy resin preferably used as the film-forming resin, so that it is difficult to separate and is uniformly dispersed in the resin composition. Cheap.

  The thermoplastic elastomer is preferably contained in an amount of 2 to 40% by mass, more preferably 5 to 30% by mass, based on the total amount of the resin in the adhesive composition. If the content of the thermoplastic elastomer is too high, the heat resistance of the joint and thus the connection reliability will be reduced. If the content is too low, the effect of increasing the adhesive strength is difficult to obtain.

(D) Polymerization initiator (B) A compound that initiates radical polymerization of a polymerizable (meth) acrylic compound, usually a compound that generates radicals upon application of activation energy, such as a peroxide or an azo compound. Although it can be used, an organic peroxide that decomposes at 70 to 110 ° C. (preferably 80 to 100 ° C.) and generates radicals is preferably used from the viewpoints of low-temperature fast curability and storage stability.

  The organic peroxide used as the polymerization initiator may be a compound having a —O—O— bond in the molecule and capable of cleaving by heating to generate a free radical. Specific examples include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters, and peroxycarbonates. For example, specifically, diisobutyryl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, dilauroyl peroxide, di (3,5,5-trimethylhexanoyl) peroxide, t-butyl peroxypivalate, t-hexyl peroxypivalate, t-butyl peroxyneoheptanoate, t-butyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, di (2- Ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, di-sec-butyl peroxydicarbonate, di -N-propyl peroxydicarbonate, cumyl par Carboxymethyl neodecanoate, di (4-methylbenzoyl) peroxide, di (3-methylbenzoyl) peroxide, dibenzoyl peroxide, t-hexyl peroxybenzoate, may be mentioned t-butyl peroxy benzoate. Two or more of these can be used in combination. Of these, peroxyester is particularly preferably used.

  The organic peroxide curing agent varies depending on the type and blending amount of the thermosetting acrylic resin, phenoxy resin, and thermoplastic elastomer to be used, but is 1 to 20 with respect to 100 parts by mass of the polymerizable (meth) acrylic compound. It is preferable to contain a mass part.

(E) Conductive particles The conductive particles may be any conductive particles, such as solder particles, nickel particles, gold-plated nickel powder, copper powder, silver powder, nano-sized metal crystals, and metal surfaces. Metal particles such as particles coated with other metals; resin particles such as styrene resin, urethane resin, melamine resin, epoxy resin, acrylic resin, phenol resin, styrene-butadiene resin, gold, nickel, silver, copper, solder, etc. Particles coated with a conductive thin film can be used. The particle size of such conductive particles is not particularly limited, but is usually an average particle size of 0.1 to 5 μm.

  Among these, particles having magnetism are preferably used from the viewpoint that the conductive particles are easily oriented in a predetermined direction (in the present invention, the film thickness direction). Further, from the viewpoint of easily orienting the conductive particles in the thickness direction, conductive particles having an aspect ratio of 5 or more are preferably used. Specifically, a shape in which fine metal particles are connected in a straight chain or a needle-like particle is preferable, and a linear or needle-like particle having a particle size (short axis) of 0.05 to 0.3 μm is more preferable. Is used. Such conductive particles can be oriented in the thickness direction by the action of a magnetic field during film formation.

  The content of conductive particles varies depending on the application, but the anisotropic conductive adhesive used for joining circuit boards is not sufficient for conducting gaps between adjacent electrodes juxtaposed on the same surface. In addition, it is an amount capable of conducting between the opposing electrodes. Specifically, it is preferably 0.01 to 10% by volume with respect to the total volume of the conductive adhesive, and more preferably 0. It is 01-1 volume%, More preferably, it is 0.01-0.5 volume%.

(F) Other additives For the film-like anisotropic conductive adhesive of the present invention, in addition to the above components, a reinforcing material, a filler, a coupling agent, a curing accelerator, a flame retardant, as necessary. Etc. may be contained.

  Moreover, as long as it does not impair the low-temperature rapid curability of the adhesive composition of the present invention, for example, other thermosetting such as epoxy resin, polyimide resin, polyamideimide resin, polyesterimide resin, phenol resin, polyurethane resin, etc. A thermoplastic resin, an acrylic resin, a fluororesin, a polyester resin, a silicone resin, or the like may be appropriately contained as necessary.

[Manufacture of film-like anisotropic conductive adhesive]
The film-like anisotropic conductive adhesive of the present invention is obtained by forming a composition for an adhesive containing the above components into a film. Although the manufacturing method of a film-form anisotropic conductive adhesive is not specifically limited, Usually, it manufactures with the following methods.

(A), (B), (C), (D), and (E), and if necessary, a predetermined amount of the component (F) is blended and dissolved in a solvent to prepare an adhesive solution. Examples of the solvent include toluene, xylene, benzene, ethyl acetate, butyl acetate, aromatic hydrocarbons and the like. Further, when the film-like anisotropic conductive adhesive uses acicular particles (for example, conductive particles having an aspect ratio of 5 or more) as the conductive particles, the conductive particles can be oriented in the thickness direction during drying. A solvent having a high volatilization rate is preferably used. Specifically, ester systems such as propylene glycol monomethyl ether acetate (PGMEA) and cellosolve acetate are preferably used.
Although it does not specifically limit as solid content rate of the said adhesive agent solution, It is preferable that it is 40-70 mass%.

The prepared adhesive solution is coated on a base film, cast, and dried by heating to form a film.
Although the drying temperature for producing the film-like anisotropic conductive adhesive varies depending on the organic solvent to be used, it is preferable to select a temperature lower than the decomposition initiation temperature of the radical polymerization initiator, usually about 60 to 80 ° C. It is. The decomposition start temperature of the radical polymerization initiator is defined as the heat generation start temperature when DSC measurement is performed at a temperature increase rate of 10 ° C./min.

When the film-like anisotropic conductive adhesive contains magnetic particles or conductive particles having an aspect ratio of 5 or more as the component (D), the conductive particles are passed through a magnetic field before or simultaneously with heating and drying. It is preferable to align in the thickness direction.
Although the thickness of a film-form anisotropic conductive adhesive is not specifically limited, Usually, it is 10-50 micrometers, Preferably it is 15-40 micrometers.

[Method for producing circuit board assembly]
Next, connecting the circuit boards using the film-like anisotropic conductive adhesive of the present invention will be described.

  Specifically, as shown in FIG. 1, two circuit boards in which a plurality of electrodes are juxtaposed face each other so that the electrodes face each other, and the film-like anisotropic of the present invention is interposed between the circuit boards. A conductive adhesive is interposed and heated and pressurized under the following conditions.

  The heating and pressing method is not particularly limited, but is usually performed using a pressing tool such as a press machine or a pressing member heated to a predetermined temperature. A cushion material may be appropriately interposed between the circuit board serving as the adherend and the pressing tool.

  The heating temperature is a temperature at which the polymerizable (meth) acrylic compound can be polymerized, and more preferably a temperature at which the film-forming resin and the thermoplastic elastomer can sufficiently soften and flow. Accordingly, the type of polymerizable (meth) acrylic compound to be used, the type of initiator, the type of film-forming resin, the type of thermoplastic elastomer, the content and the like vary depending on the composition of the composition, but usually 130 to 180 ° C. , Preferably it is 140-170 degreeC.

  Here, the heating temperature is a temperature that the film-like anisotropic conductive adhesive should reach. For example, a thin thermocouple is embedded in the film-like anisotropic conductive adhesive, and the glass panel 1 and the flexible print. It is measured by sandwiching between the wiring boards 2 and actually measuring.

  The pressurizing pressure is 1 to 7 MPa, preferably 1 to 5 MPa. The pressing time is appropriately determined depending on the heating temperature and the composition of the adhesive resin composition, but is preferably as short as possible from the viewpoint of productivity. Usually, it is 15 seconds or less, preferably 10 seconds or less. According to the film-like anisotropic conductive adhesive of the present invention, it becomes easy to satisfy the requirement of low-temperature rapid curing as compared with a film-like anisotropic conductive adhesive using an epoxy resin as a thermosetting resin.

  The film-like anisotropic conductive adhesive of the present invention is softened and melted by heating and pressing and flows into a gap between electrodes on the same plane, and the distance between electrodes to be bonded is reduced to 1 μm or less and cured. To do. In particular, thermoplastic elastomers have a low melting point, so they soften and melt from the beginning of heating, contribute to narrowing the distance between electrodes by pressurization, and become liquid at high temperatures, resulting in an increase in viscosity due to the progress of the curing reaction. Even in this case, it can contribute to the flow of the resin and the reduction of the distance between the electrodes, which in turn helps to improve the adhesive strength.

The obtained bonded body can maintain connection reliability even after adhesion strength, connectivity, and storage at high temperature and high humidity. In particular, since the bonded body can act to relieve stress due to elastomeric properties, the connection reliability is high.
Furthermore, when bonding failure occurs, the adhesive remaining on the adherend after heating and peeling off the cured product can be easily wiped off with a general-purpose solvent such as a ketone or alcohol.

  The best mode for carrying out the present invention will be described with reference to examples. The examples are not intended to limit the scope of the invention.

[Evaluation measurement method]
(1) Adhesive strength (N / cm)
About the joined body produced in the Example mentioned later, it is flexible from a 90 degree direction with respect to the surface of a glass epoxy board | substrate using the tensile testing machine (The Shimadzu Corporation make, brand name Autograph AGS-500G). The printed wiring board was peeled off, and the adhesive strength was measured by measuring the peel strength (N / cm) at the interface between the flexible printed wiring board and the adhesive.

(2) Repairability (easy wiping)
While the manufactured joined body is heated to 170 ° C., the flexible printed wiring board is peeled off from the glass epoxy board, and the adhesive remaining on the copper electrode of the glass epoxy board is wiped off with a cotton swab dipped in acetone. The adhesive remaining on the copper electrode of the glass epoxy substrate was removed.
“○” indicates that the adhesive remaining on the copper electrode of the glass epoxy substrate can be completely removed, and “○” indicates that the adhesive remains even after rubbing with a cotton swab for 10 minutes. “×”.

(3) Initial connection resistance (Ω)
In the fabricated joined body, the resistance value of the daisy pattern of the connected 40 electrodes was obtained by the four-terminal method, and the value was divided by 40 to calculate the connection resistance value per place.

(4) Heat and humidity resistance The prepared joined body is put into a high temperature and high humidity tank set at 85 ° C. and 85% Rh, taken out after 500 hours, and the connection resistance value is obtained by the method of (3). It was.

[Production and evaluation of film-like anisotropic conductive adhesive]
No. 1-3:
As film-forming resin, bisphenol A type phenoxy resin (Epicoat 1256 manufactured by Japan Epoxy Resin Co., Ltd., weight average molecular weight 50,000), as thermosetting acrylic resin, NK Oligo EA-1020 manufactured by Shin-Nakamura Chemical Co., Ltd. Bisphenol A type epoxy acrylate oligomer) and NK Oligo U-2PPA (a mixture of urethane acrylate oligomer and 2-hydroxypropyl acrylate) manufactured by Shin-Nakamura Chemical Co., Ltd. Table 1 shows polyamide elastomer (TPAE826 manufactured by Fuji Kasei) as a thermoplastic elastomer using “Perocta O” and 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate). Blended in the proportions (parts by weight) Was dissolved in a mixed solvent of glycol monomethyl ether acetate and isophorone, to obtain an adhesive solution is a solid content of 50 mass%.

  In this adhesive solution, linear nickel particles were uniformly dispersed so as to be 0.05% by volume with respect to the components excluding the solvent, thereby preparing a conductive adhesive composition.

  The adhesive composition prepared above is applied onto a release-treated PET film, and dried and solidified in a magnetic field with a magnetic flux density of 100 mT at 70 ° C. for 40 minutes, whereby linear Ni in the film thickness direction. A film-like conductive adhesive having a particle orientation and a thickness of 35 μm was prepared.

100 flexible printed wiring boards in which 100 gold electrodes (width 100 μm, height 18 μm) are arranged at intervals of 100 μm and gold plated copper electrodes (width 100 μm, height 35 μm) are 100 at intervals of 100 μm. Individually arranged glass epoxy substrates were prepared.
The prepared adhesive film is sandwiched between the flexible printed wiring board and the glass epoxy substrate, and heated and bonded to 150 ° C. with a pressure of 3 MPa for 10 seconds to bond the flexible printed wiring board and the glass epoxy substrate. A zygote was obtained.

  Using this joined body, adhesive strength, repairability, connection reliability, heat resistance and moisture resistance were evaluated based on the above-described measurement evaluation method. The results are shown in Table 1.

No. 4:
No. except that no thermoplastic elastomer was blended. In the same manner as in Example 1, a film-like anisotropic conductive adhesive was produced, and a joined body was obtained using the film-like anisotropic conductive adhesive.

No. 5
No. 1 was used except that acrylic rubber (“Taisan Resin WS023” manufactured by Nagase ChemteX Corporation) was used in place of the thermoplastic elastomer. In the same manner as in Example 1, a film-like anisotropic conductive adhesive was produced, and a joined body was obtained using the film-like anisotropic conductive adhesive.

No. 1-3 and No.1. From the comparison with No. 4, No. 4 containing no thermoplastic elastomer. 4 shows that the adhesive strength is low, and the initial connectivity and heat and humidity resistance are also poor.
No. 4 and no. From the comparison with No. 5, although the initial connectivity can be improved by containing acrylic rubber, the heat and humidity resistance is not blended No.5. It turns out that it was inferior to 4. Furthermore, regarding the adhesive strength, No. in which the elastomer component is not blended is more blended with acrylic rubber. It was inferior to 4.

  No. From 1-3, it can be seen that, when the thermoplastic elastomer is contained in an amount of 5 to 30% by mass with respect to the total amount of the resin, all of high adhesive strength, initial connectivity, and heat and humidity resistance can be satisfied. In addition, No. From the comparison of 1-3, the adhesive strength tends to increase as the thermoplastic elastomer content increases, but the connection reliability tends to decrease when the thermoplastic elastomer content increases too much. It appears to be.

  The film-like anisotropic conductive adhesive of the present invention uses a polymerizable (meth) acrylic compound capable of rapid curing at low temperature, and the obtained joined body has an adhesive strength and a connection without impairing repairability. Since the reliability is improved, it is useful for realizing energy saving at the joining work site.

Claims (5)

(A) Film-forming resin, (B) polymerizable (meth) acrylic compound, (C) thermoplastic elastomer, (D) polymerization initiator, and (E) conductive anisotropic particles in film form Agent. The film-like anisotropic conductive adhesive according to claim 1, wherein the (C) thermoplastic elastomer is a polyamide-based thermoplastic elastomer. The film-like anisotropic conductive adhesive according to claim 1 or 2, wherein the content of the (C) thermoplastic elastomer with respect to the total amount of the resin is 2 to 40% by mass. The film-like anisotropic conductive adhesive according to claim 1, wherein the (B) polymerizable acrylic compound contains an epoxy acrylate and a urethane acrylate. The film-shaped anisotropic conductive adhesive according to any one of claims 1 to 4, wherein the (A) film-forming resin is a phenoxy resin.

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