JP2002241722A - Anisotropic conductive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-curable anisotropic conductive adhesive which can especially connect microcircuits to each other at a low temperature in a short time on the electric connection of the microcircuits such as the connection of LCD to TCP or the connection of LCD to COF, and which has excellent adhesivity, adhesion reliability, storage stability and repairability. SOLUTION: This anisotropic conductive adhesive in which conductive particles are dispersed in a resin composition is characterized in that the resin composition consists essentially of (A) a radically polymerizable resin, (B) an organic peroxide, (C) a thermoplastic elastomer resin, (D) a resin containing one or more epoxy groups in the molecule, and (E) an aminosilane coupling agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a connection between an LCD (liquid crystal display) and a TCP (tape carrier package), a connection between an LCD and a COF (Chip On FPC), and a connection between a TCP and a PCB (printed circuit board). The present invention relates to an anisotropic conductive adhesive used for electrical connection between fine circuits, such as connection of the same.

[0002]

2. Description of the Related Art In recent years, anisotropic conductive adhesives in which conductive particles are dispersed in an adhesive resin have been developed for LCD and TCP, and for LCD and C.
The necessity of connecting various kinds of fine circuits such as OF and connection between TCP and PCB has been dramatically increased, and an anisotropic conductive adhesive has been used as a connection method thereof. In this method, an anisotropic conductive adhesive is sandwiched between members to be connected and heated and pressed to maintain electrical insulation between adjacent terminals in the surface direction and to electrically conduct between upper and lower terminals. . Anisotropic conductive adhesives have often been used for such applications because of the lack of heat resistance of the adherend and the short circuit between adjacent terminals in fine circuits, such as soldering. The reason is that the connection method cannot be applied.

[0003] The anisotropic conductive adhesive is classified into a thermoplastic type and a thermosetting type. Recently, however, an epoxy resin-based thermosetting type having higher reliability than the thermoplastic type has been used. Things are becoming widely used.

As for the thermoplastic type anisotropic conductive adhesive, SBS (styrene-butadiene-styrene), SI
Styrene-based copolymers such as S (styrene-isoprene-styrene) and SEBS (styrene-ethylene-butadiene-styrene) have been mainly used. In general, the workability can be applied at a relatively low temperature and in a short time compared to the thermosetting one if the conditions are selected.
The resin was not durable in long-term environmental tests due to low moisture resistance and chemical resistance, and low connection reliability.

On the other hand, as the thermosetting type anisotropic conductive adhesive which is currently mainstream, an epoxy resin type thermosetting type having a good balance between storage stability and curability is widely used. However, in practice, these thermosetting types are required to be heated and cured at a temperature of 150 to 200 ° C. for about 30 seconds in order to achieve both storage stability and curability of the resin, in view of their curing reactivity. For example, at a temperature of 150 ° C. or less, it is difficult to cure the resin in a practical connection time.

Further, regarding the storage stability, for example, B
F ₃ amine complex, dicyandiamide, organic acid hydrazide, a compound containing a latent curing agent such as an imidazole compound and the like have been proposed, but those with excellent storage stability require a long time or high temperature for curing, On the other hand, those which can be cured at a low temperature in a short time have a problem that storage stability is inferior, and all have advantages and disadvantages.

In addition to the above problems, in connection workability between fine circuits using a thermosetting type of anisotropic conductive adhesive, a member once connected due to a position shift or the like may be damaged or damaged. There has been a growing demand for peeling without damage and joining again (so-called repair). However, while most of them have advantages such as high adhesive strength and high reliability, it is extremely difficult to respond to such seemingly contradictory requirements, and no satisfactory products have been obtained.

In recent years, in particular, LCD screens have been rapidly increasing in size, definition, and frame width.
The miniaturization of the connection pitch and the narrowing of the connection have also progressed rapidly. For this reason, for example, LCD and TCP connection and LCD
In the connection between the device and the COF, there are problems such as the connection pattern being shifted due to the spread of TCP and COF at the time of connection, and the members inside the LCD being thermally affected by the temperature at the time of connection because the connection portion is narrow. Has arisen. Further, in the connection between the TCP and the PCB, since the PCB has become longer, there has been a problem that the PCB and the LCD are warped due to heating during the connection, and the wiring of the TCP is disconnected. Also, with the spread of display devices represented by mobile phones, there has been a problem that the current connection time of 15 to 20 seconds results in poor production efficiency.

In order to solve these problems, it has been conceived to solve these problems by connecting at a lower temperature and in a shorter time.
For example, if an attempt is made to connect with a conventional thermoplastic type anisotropic conductive adhesive, connection at a relatively low temperature is possible, but the connection reliability is poor due to the low moisture resistance and heat resistance of the resin. Was. In addition, when connecting an epoxy resin-based anisotropic conductive adhesive, which is the mainstream of the thermosetting type, at a low temperature, it is necessary to lengthen the connection time in order to cure the resin, which is not practically applicable. .

As an anisotropic conductive adhesive which enables low-temperature connection, conductive particles dispersed in an adhesive resin containing a cationically polymerizable substance and a sulfonium salt (JP-A-7-90237) Also, there has been proposed an epoxy resin or the like in which conductive particles are dispersed in a 4- (dialkylamino) pyridine derivative (Japanese Patent Application Laid-Open No. 4-189883). It has not been put to practical use due to problems such as corrosion of the steel.

[0011] Further, as a low temperature connection,
In a thermosetting anisotropic conductive adhesive in which conductive particles are dispersed in a resin composition containing a radical polymerizable resin, an organic peroxide, a thermoplastic elastomer, and a maleimide, the radical polymerizable resin has a phenolic hydroxyl group. Anisotropic conductive adhesive which is a (meth) acryloylated novolak resin having, and further, an aminosilane coupling agent added for the purpose of improving adhesion and connection reliability have been proposed. Workability, adhesion after high temperature and high humidity treatment,
A resin system that satisfies all requirements such as connection reliability and storage stability in a well-balanced manner has not been obtained.

[0012] Further, as a material which enables low-temperature connection, conductive particles are dispersed in a resin composition containing a radical polymerizable resin, an organic peroxide, an epoxy resin, a curing agent, and a thermoplastic elastomer. (JP-A-10-1
No. 68142) has been proposed, but the curing agent of the epoxy resin promotes the decomposition of the organic peroxide, resulting in poor preservability, and the curing of the resin is insufficient due to trapping of radicals during thermocompression bonding. However, there is a problem that the connection reliability is poor, and the resin system has not been satisfied.

[0013] In addition, a resin composition containing a radically polymerizable resin, an organic peroxide, a thermoplastic elastomer, a phosphate ester, and an epoxy silane coupling agent is used as a compound capable of connecting at a low temperature for a short time. A dispersion of particles (JP-A-2000-044905) has also been proposed. Although the balance between the curability and the preservability at a low temperature and in a short time is good, there is a problem in that the adhesion to silicon nitride, which is the bonding interface of LCD, and the polyimide, which is the bonding interface of COF, is insufficient. Therefore, low-temperature and short-time connection is possible, adhesiveness, connection reliability,
There is an increasing demand for an anisotropic conductive adhesive having excellent storage stability and repairability.

[0014]

SUMMARY OF THE INVENTION The present invention has been made as a result of various studies in view of the above-mentioned problems of the prior art, and aims at connection between an LCD and a TCP, and between an LCD and a TCP. Connection with COF, TCP and PCB
Thermosetting anisotropic conductivity that enables electrical connection between microcircuits, such as connection with a device, especially at low temperature and in a short time, and has excellent adhesiveness, connection reliability, storage stability, and repairability. It is intended to provide an adhesive.

[0015]

According to the present invention, there is provided a radical polymerizable resin (A), an organic peroxide (B), a thermoplastic elastomer (C), containing at least one epoxy group in at least one molecule. An anisotropic conductive adhesive comprising a resin (D), an aminosilane coupling agent (E), and conductive particles dispersed in these resin compositions. More preferred embodiments include a radical polymerizable resin (A), a thermoplastic elastomer resin (C) in a resin composition, a resin (D) containing at least one epoxy group in at least one molecule, and an aminosilane coupling agent. The mixing ratio of (E) is a weight ratio, and {(D) + (E)} / {(A) + (C)} = (0.1 to
20) / 100 (D) / (E) = 90/10 to 50/50.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The anisotropic conductive adhesive of the present invention comprises a resin (D) containing at least one epoxy group per molecule in a resin composition constituting the anisotropic conductive adhesive, and an aminosilane coupling agent (E). Is characterized by containing
LCD and TCP for use, LCD and COF, TCP and PC
When B is connected, sufficient connection reliability can be obtained due to the adhesiveness to silicon nitride and polyimide, which are the bonding interface of LCD, which was not obtained with the conventional radical polymerizable resin, and the heat and moisture resistance. I found something.

The radically polymerizable resin (A) used in the present invention is not particularly limited as long as it has at least one carbon-carbon double bond in the molecule and is capable of radical polymerization. Alternatively, they can be used alone or as a mixture of two or more. For example, unsaturated polyester resins, maleimide resins, various allyl resins, various acrylate resins, and the like can be used. In addition, an acrylate resin modified with an amine compound or a compound having a carbon-carbon double bond can also be used. Above all, adhesiveness, curability, preservability, and anisotropic conductive adhesive
A vinyl ester resin and a urethane acrylate resin having heat resistance, moisture resistance and chemical resistance of the cured product can be suitably used.

Further, in order to secure the curability of the anisotropic conductive adhesive and the flowability of the resin during thermocompression bonding, trimethylolpropane triacrylate (TMPTA)
Pentaerythritol diallylate monostearate,
Acrylates such as tetraethylene glycol diacrylate and pentaerythritol tetraacrylate and various radically polymerizable monomers such as styrene can be used in combination. Further, in order to ensure its preservability, it is also possible to add a polymerization inhibitor such as quinones, polyhydric phenols and phenols in advance (for example,
JP-A-4-146951).

The organic peroxide (B) used in the present invention is not particularly limited, and may be used alone or as a mixture of two or more organic peroxides for controlling the curability. It is. For example, ketone peroxides include methyl ethyl ketone peroxide, cyclohexanone peroxide, methylcyclohexanone peroxide, methyl acetoacetate peroxide, acetylacetone peroxide and the like. As peroxyketals, 1,1-
Bis (t-hexylperoxy) 3,3,5-trimethylcyclohexanone, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) 3,3,5-trimethyl Cyclohexanone,
1,1-bis (t-butylperoxy) 2-methylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy)
Cyclododecane, 2,2-bis (t-butylperoxy) butane, 2,2-bis (4,4-di-t-butylperoxy) propane and the like can be mentioned. Hydroperoxides include p-methane hydroperoxide, diisopropylbenzene hydroperoxide,
Examples thereof include 1,1,3,3 tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-hexyl hydroperoxide, and t-butyrr hydroperoxide. Examples of the dialkyl peroxide include α, α-bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5 dimethyl-2,5-bis (t-butylperoxy) hexane, and t-butylcumyl peroxide. Oxide, di-t-butyl peroxide, 2,5 dimethyl-2,5 bis (tt
-Butylperoxy) hexane-3 and the like. Examples of diacyl peroxides include isobutyl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, and the like. Examples of peroxydicarbonates include di-n-propylperoxydicarbonate, diisopropylperoxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, -2-ethoxyhexylperoxydicarbonate, di-3-methoxybutylperoxydicarbonate, di (3-methyl-3-
(Methoxymethyl) peroxydicarbonate. As peroxyesters, α, α-bis (neodecanylperoxy) diisopropylbenzene, cumylperoxyneodecanate, 1,1,3,3
3-tetramethylbutyl peroxy neodecanoate,
1-cyclohexyl-1-methylethyl peroxy neodecanoate, t-hexyl peroxy neodecanoate, t-butyl peroxy neodecanoate, t-hexyl peroxy neodecanoate, t-butyl peroxy Pivalate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy)
Hexane, 1-cyclohexyl-1-methylethylperoxy 2-ethylhexanoate, t-hexylperoxy 2-ethylhexanoate, t-butylperoxy 2-ethylhexanoate, t-butylperoxyisobutyrate Rate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-
Butylperoxy 3,5,5 trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-bis (m-toluoylperoxy) hexane, t-butylperoxy 2-ethylhexyl Monocarbonate, t-butylperoxyisopropyl monocarbonate, t-hexylperoxyzenzoate, 2,
5-dimethyl-2,5-bis (benzoylperoxy)
Hexane, t-butyl peroxy acetate, t-butyl peroxy-m-toluoyl benzoate, t-butyl peroxy benzoate, bis (t-butyl peroxy) isophthalate, and the like. Among them, peroxy ketals and peroxy esters having excellent curability and storage stability when used as an anisotropic conductive adhesive can be more preferably used. Various polymerization inhibitors can be added in advance to improve the storage stability. Further, in order to facilitate the work of dissolving the resin, it can be used after being diluted with a solvent or the like.

The thermoplastic elastomer resin (C) used in the present invention includes, for example, polyester resin, polyurethane resin, polyimide resin, polybutadiene, polypropylene, styrene-butadiene-styrene copolymer, polyacetal resin, polyvinyl butyral resin,
Phenoxy resin, butyl rubber, chloroprene rubber, polyamide resin, acrylonitrile-butadiene copolymer,
Acrylonitrile-butadiene-methacrylic acid copolymer, acrylonitrile-butadiene-styrene copolymer, polyvinyl acetate, nylon resin, styrene-isoprene copolymer, styrene-butylene-styrene block copolymer, styrene-ethylene-butylene-styrene A block copolymer, polymethyl methacrylate resin, or the like can be used. Considering properties such as adhesiveness and connection reliability when used as an anisotropic conductive adhesive among them, acrylonitrile-butadiene-methacrylic copolymer, polyester, nylon resin, polyvinyl butyral resin, phenoxy resin, styrene-ethylene -A butylene-styrene block copolymer can be more preferably used.
In addition, it has a methacryl group capable of radically polymerizing an isocyanate group and a polyester resin having a hydroxyl group in the molecule, a polyvinyl butyral resin or a phenoxy resin in the molecule in order to improve the adhesiveness when the anisotropic conductive adhesive is used. Those modified with isocyanate ethyl methacrylate or those modified with glycidyl methacrylate having an epoxy group and a methacryl group capable of radical polymerization can be used. Further, those modified with isocyanate silane or amino silane to improve the adhesiveness can be used.

The resin (D) having at least one epoxy group in at least one molecule used in the present invention is not particularly limited. For example, bisphenol A
1,6-bis- having a naphthalene skeleton in other molecules such as epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolak epoxy resin, cresol novolak epoxy resin, etc.
(2,3 epoxypropoxy) naphthalene or tris- (2,3 epoxypropyl) isocyanurate having isocyanuric acid skeleton, diallyl monoglycidyl isocyanuric acid or monoallyl diglycidyl isocyanuric acid, glycidyl methacrylate monomer, glycidyl methacrylate homopolymer, glycidyl Examples thereof include methacrylate-styrene copolymer and glycidyl methacrylate-methyl methacrylate copolymer, and may be used alone or in combination of two or more.

The aminosilane coupling agent (E) used in the present invention includes one or more primary and secondary amino
There is no particular limitation as long as it has a primary or tertiary amino group. For example, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenylaminopropyltrimethoxysilane,
γ- (2-aminoethyl) aminopropylmethoxysilane, γ-butylaminopropyltrimethoxysilane, bis (trimethoxysilylpropyl) amine, (aminoethylaminomethyl) phenethyltrimethoxysilane, bis [3- (trimethoxysilyl) ) Propyl] ethylenediamine and the like, and may be used alone or in combination of two or more.

The amounts of the radical polymerizable resin (A), the thermoplastic elastomer (C), the resin (D) containing at least one epoxy group in one molecule and the aminosilane coupling agent (E) are weight ratios. Where {(D) + (E)} / {(A) + (C)} = (0.1 to
20) / 100. If the compounding amount of {(D) + (E)} is less than 0.1 / 100, the coupling effect between the anisotropic conductive adhesive and the adherend cannot be obtained, and {(D) +
If the amount of (E) exceeds 20/100, problems such as a decrease in the flowability of the binder resin of the anisotropic conductive adhesive and a decrease in storage stability occur.

The compounding amount of the resin (D) containing at least one epoxy group in one molecule and the aminosilane coupling agent (E) is by weight ratio, and (D) / (E) = 90 / 10-50 / 50 is preferable. The proportion of the resin (D) containing at least one epoxy group in at least one molecule is 90/10
If it exceeds 3, the effect of adding the aminosilane coupling agent cannot be obtained, and sufficient adhesive strength cannot be obtained. A resin (D) containing at least one epoxy group in at least one molecule;
Is less than 50/50, the pH of the anisotropic conductive adhesive increases and the storage stability decreases, and the aminosilane coupling agent traps radicals during actual thermocompression bonding to lower the curability. Such a problem arises.

The conductive particles used in the present invention are not particularly limited as long as they have conductivity, and various kinds of metals such as nickel, iron, copper, aluminum, tin, lead, chromium, cobalt, silver, and gold can be used. And metal alloys, metal oxides, carbon, graphite, glass and ceramics, and plastic particles coated with a metal on the surface.
The circuit pitch of TCP and COF is becoming narrower, and considering the problem of short circuit between adjacent terminals, the particle size is 3 μm to 1 μm.
Those obtained by coating 0 μm plastic particles with nickel / gold plating are more preferably used.

According to the present invention, there is provided an anisotropic conductive adhesive obtained by dispersing conductive particles in an adhesive containing a radical polymerizable resin, an organic peroxide, and a thermoplastic elastomer. At least one in one molecule
Excellent adhesiveness and connection reliability can be obtained because it contains a resin containing two or more epoxy groups and aminosilane coupling agent, connection at extremely low temperature and short time is possible, and furthermore, storage stability Thus, an anisotropic conductive adhesive excellent in repairability can be obtained.

[0027]

The present invention will be described below with reference to examples and comparative examples. Table 1 summarizes the substances used in Examples and Comparative Examples.

[0028]

[Table 1]

[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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Example 1 A 50% solution of a bismaleimide resin having the structure of the formula (1) in tetrahydrofuran
200 parts by weight of the solution, 5 parts by weight of t-hexylperoxy 2-ethylhexanoate, 500 parts by weight of a 20% solution of polyvinyl butyral resin having the structure of the formula (4) in methyl ethyl ketone, bisphenol F type epoxy resin 10 parts by weight (epoxy equivalent: 175), γ-
5 parts by weight of aminopropyltriethoxysilane, Ni /
7.0 parts by weight of Au-plated polystyrene particles (average particle size 5
μm) was mixed and uniformly dispersed, and then cast and dried on a release-treated polyethylene terephthalate film so that the thickness after drying became 15 μm to obtain an anisotropic conductive adhesive. . The following evaluation was performed about the obtained anisotropic conductive adhesive.

<Examples 2 to 26> Anisotropic conductive adhesives were obtained in the proportions shown in Tables 2 and 3 in the same manner as in Example 1. The following evaluation was performed about the obtained anisotropic conductive adhesive.

[0036]

[Table 2]

[0037]

[Table 3]

<Comparative Examples 1 to 9> Anisotropic conductive adhesives were obtained in the same proportions as in Example 1 at the mixing ratios shown in Table 4.
The following evaluation was performed about the obtained anisotropic conductive adhesive.

[0039]

[Table 4]

<Evaluation Method> Preparation of evaluation sample The adherend was Ni / A on copper foil / polyimide = 12/25 μm.
u-plated COF (pitch 50 μm, number of terminals 30
0) and ITO (indium / tin oxide) solid glass (sheet resistance 30Ω / □). 2. Adhesive strength measuring method The adhesive strength was measured at 150 ° C., 3 MPa, and 10 s, and evaluated by a 90 ° peel test.

3. Connection reliability measurement method Immediately after sample preparation, temperature 85 ° C, humidity 85%, 10
The connection resistance after leaving for 0 hour was measured. Those that could not be measured were regarded as poor conduction (open). 4. Storage property measurement method After storing the anisotropic conductive film in a 25 ° C atmosphere for 2 weeks, 1
Crimping was performed under the conditions of 50 ° C., 3 MPa, and 10 s, and the connection resistance was measured. 5 Ω or less was rated as ○, and 5 Ω or greater was rated as x.

[0042]

By using the anisotropic conductive adhesive of the present invention, it is possible to connect fine circuit electrodes at a low temperature of about 150 ° C. and in a short time of 10 seconds or less.
An anisotropic conductive adhesive excellent in long-term reliability can be obtained.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01R 4/04 H01R 4/04 H05K 3/32 H05K 3/32 BF term (Reference) 4J040 CA031 CA032 DA141 DA142 DD071 DD072 DE021 DE022 DF001 DF002 DF051 DF052 DM001 DM002 EA001 EA002 EC062 EC072 EC232 EC282 EC332 ED001 ED002 ED111 ED112 EE061 EE062 EF001 EF002 EG001 EG002 EH031 EH032 HB41 HD36 JB02 KA03 KA16 KA16 LA05 5 DA02 DA03 DA04 DA05 DA06 DA07 DA10 DA13 DA18 DA19 DA23 DA29 DA42 DA57 DD03

Claims (3)

[Claims] 1. An adhesive comprising conductive particles dispersed in a resin composition, wherein the resin composition comprises a radical polymerizable resin (A), an organic peroxide (B), and a thermoplastic elastomer resin (C). ), An anisotropic conductive adhesive comprising, as essential components, a resin (D) containing at least one epoxy group in one molecule and an aminosilane coupling agent (E). 2. A radical polymerizable resin (A) in a resin composition, a thermoplastic elastomer resin (C), a resin (D) containing at least one epoxy group in at least one molecule, an aminosilane coupling agent ( The mixing ratio of E) is a weight ratio, and {(D) + (E)} / {(A) + (C)} = (0.1 to
20) / 100, The anisotropic conductive adhesive according to claim 1. 3. The method according to claim 1, wherein at least one molecule is present in one molecule of the resin composition.
The compounding ratio of the resin (D) containing at least two epoxy groups and the aminosilane coupling agent (E) is in the range of (D) / (E) = 90/10 to 50/50 by weight. The anisotropic conductive adhesive according to the above.