JP2002180012A - Anisotropic electroconductive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hot-curing type anisotropic electroconductive adhesive capable of carrying out connection especially at a low temperature in a short time and having excellent adhesion, connection reliability, preservation stability and repair properties in electrical connection of mutual microcircuits such as connection of a liquid crystal display(LCD) to a tape carrier package(TCP) or connection of the TCP to a printed circuit board(PCB). SOLUTION: This anisotropic electroconductive adhesive comprises a radical- polymerizable resin, an allyl-modified cyanurate compound, an organic peroxide, a thermoplastic elastomer, a phosphoric ester, an epoxy silane coupling agent and electroconductive particles dispersed in a resin composition consisting essentially of the radical-polymerizable resin, the allyl-modified cyanurate compound, the organic peroxide, the thermoplastic elastomer, the phosphoric ester and the epoxy silane coupling agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an LCD (Liquid Crystal Display), a PDP (Plasma Display) and a TCP.
(Tape carrier package), TCP and P
The present invention relates to an anisotropic conductive adhesive having low-temperature connectivity and heat resistance used for electrical connection between fine circuits such as connection to a CB (printed circuit board).

[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 required to connect various fine circuits such as connection between LCD or PDP and TCP, connection between TCP and PCB. The use of an anisotropic conductive adhesive has been increasing as a connection method. 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 been frequently used in 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. This is because the conventional connection method cannot be applied.

[0003] This 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 is used. Is being 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, but these thermoplastic types are basically used in a melt-fusion method. The workability is generally considered to be good because it can be applied at a relatively low temperature and in a short time compared to the thermosetting one if the conditions are selected, but the moisture resistance and chemical resistance of the resin Therefore, it was not able to withstand a long-term environmental test because of its low reliability 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 lower than 150 ° C., 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 an anisotropic conductive adhesive of a thermosetting type, one which is once connected due to a position shift or the like,
There have been many demands for peeling and rejoining (so-called repair) the connected member without breaking or damaging it.
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, in the connection between the LCD and the TCP, the connection pattern is shifted due to the extension of the TCP at the time of connection, and the members inside the LCD are thermally affected by the temperature at the time of connection because the connection portion is narrow. Such problems have 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.

In order to solve these problems by connecting at a lower temperature, for example,
When trying to connect with a conventional thermoplastic type anisotropic conductive adhesive, connection at a relatively low temperature is possible, but there is a problem that the connection reliability is poor because the moisture resistance and heat resistance of the resin are low. Also, if you try to connect at low temperature with epoxy resin type anisotropic conductive adhesive which is the mainstream of thermosetting type,
In order to cure the resin, it was necessary to lengthen the connection time, which was 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. An anisotropic conductive adhesive characterized by being a (meth) acryloylated novolak resin having the formula (1), and a resin to which an aminosilane coupling agent is added for the purpose of improving adhesion and connection reliability have also been proposed. However, a resin system that satisfies all of the curability, workability, adhesiveness after high-temperature and high-humidity treatment, connection reliability, and storage stability in a well-balanced manner has not been obtained. In addition, there is an increasing demand for anisotropic conductive adhesives having excellent heat resistance, adhesiveness, connection reliability, storage stability, repairability, and the like.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned problems of the prior art, and has been made as a result of various studies. The purpose of the present invention is to provide a connection between an LCD and a TCP or a TCP. In the electrical connection between microcircuits such as the connection between the PCB and the PCB, it is possible to connect especially in a low temperature and short time, and also, heat resistance, adhesiveness, connection reliability, storage stability,
An object of the present invention is to provide a heat-curable anisotropic conductive adhesive having excellent repairability.

[0013]

According to the present invention, there is provided a resin composition comprising a radical polymerizable resin, an organic peroxide, a thermoplastic elastomer and a phosphate ester represented by the formula (1) as an essential component. An anisotropic conductive adhesive in which particles are dispersed, wherein all or a part of the radically polymerizable resin is an allyl-modified cyanurate compound represented by the formula (2). As a more preferred embodiment, in the radical polymerizable resin, the ratio of the allyl-modified cyanurate compound represented by the formula (2) to the other radical polymerizable resin is in the range of 10: 1 to 1:10, and the resin composition Is an anisotropic conductive adhesive further containing an epoxysilane coupling agent represented by the formulas (3) and / or (4).

[0014]

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[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The anisotropic conductive adhesive of the present invention is characterized in that the resin composition constituting the anisotropic conductive adhesive contains an allyl-modified cyanurate compound represented by formula (2) as a radical polymerizable resin, LCD and TCP for LCD applications
When it is used for the connection between the substrate and the TCP and the PCB, heat resistance and moisture resistance which cannot be obtained by the conventional radically polymerizable resin can be obtained, and unprecedented good connection reliability can be obtained. Further, by combining epoxysilane coupling agents represented by the following formulas (3) and (4), the coupling effect between the radical polymerizable resin and the metal portion of the adherend can be further improved. It is possible to obtain further adhesiveness and connection reliability.

The phosphate in the present invention is
There is no particular limitation as long as it is represented by the formula (1), and it may be used alone or in combination of two or more. Specific examples of the phosphoric ester include (meth) acryloyloxyethyl acid phosphate, (meth) acryloyloxypropyl acid phosphate, (meth) acryloyloxyisopropyl acid phosphate, and (meth) acrylyloxypolyoxyethylene glycol acid. Phosphate, (meth) acryloyloxy polyoxypropylene glycol acid phosphate, caprolactone-modified (meth) acryloyloxyethyl acid phosphate, di (meth) acryloyloxypropyl acid phosphate, di [caprolactone-modified (meth) acryloyloxyethyl] acid phosphate, and the like No.

In the case of a phosphate ester other than the formula (1), the coupling effect between the radical polymerizable resin and the metal part of the adherend is low, and only the phosphate ester of the formula (1) is used at a relatively low temperature for a short time. A ring effect can be obtained.

The allyl-modified cyanurate compound used in the present invention is represented by the formula (2). If it has at least one allyl group, the allyl group chain length and other types of functional groups are not limited. It is not particularly limited, and may be determined in consideration of compatibility, fluidity at the time of heating, the type of the target adherend, and the like, depending on the type of other radical polymerizable resin or thermoplastic elastomer contained. is there. Specific examples include, for example, diallyl monoglycidyl isocyanurate, monoallyl diglycidyl isocyanurate, and triallyl isocyanurate, and these may be used alone or in combination of two or more. It is also preferable to use the resin in combination with another radical polymerizable resin. More preferably, the ratio of the allyl-modified cyanurate compound to the other radically polymerizable resin is in the range of 10: 1 to 1:10.
If the ratio is lower than the range, sufficient heat resistance cannot be obtained, and if the ratio is higher than the range, the adhesive strength is insufficient.

Other radically polymerizable resins used in the present invention include (meth) -containing phenolic hydroxyl groups.
Acryloylated phenol novolak resins, vinyl ester resins, acrylates such as urethane acrylate resins, unsaturated polyester resins, diallyl phthalate resins, maleimide resins, and the like can be used. Among them, a (meth) acryloylated phenol novolak resin, a vinyl ester resin, a urethane acrylate resin, and a maleimide resin having a phenolic hydroxyl group having both curability and storage properties, heat resistance, moisture resistance, and chemical resistance of a cured product are preferably used. Can be Further, in order to ensure the storage stability, it is possible to add a polymerization inhibitor such as quinones, polyhydric phenols, and phenols in advance (see, for example,
146951). In order to further improve curability, fluidity during heating, and workability, acrylates such as trimethylolpropane triacrylate (TMPTA), pentaerythritol diallylate monostearate, tetraethylene glycol diacrylate, pentaerythritol tetraacrylate, and styrene. It is also possible to use it after diluting with various monomers or a common reactive diluent.

The organic peroxide used in the present invention is not particularly limited, and for example, 1,1,3,3
-Tetramethylbutylperoxy-2-ethylhexanate, t-butylperoxy-2-ethylhexanate, t-hexylperoxy-2-ethylhexanate, 1,1-bis (t-butylperoxy)- 3,3
5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, bis (4-t-butylcyclohexyl) peroxydicarbonate and the like can be mentioned. These peroxides can be used alone or as a mixture of two or more kinds of organic peroxides for controlling curability.
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 diluted with a solvent or the like. Naturally, the type and amount of the organic peroxide used in the present invention are determined depending on the balance between the curability and the preservability of the adhesive when each peroxide is compounded.

The thermoplastic elastomer used in the present invention is not particularly limited. Examples thereof include polyester resins, polyurethane resins, polyimide resins, polybutadiene, polypropylene, styrene-butadiene-styrene copolymer, polyacetal resin, and polyvinyl butyral. Resin, butyl rubber, chloroprene rubber, polyamide resin, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, acrylonitrile-butadiene-styrene copolymer, polyvinyl acetate resin, nylon, styrene-isoprene copolymer, Styrene-butylene-styrene block copolymer,
Styrene-ethylene-butylene-styrene block copolymer, polymethyl methacrylate resin and the like can be used. Among them, acrylonitrile-butadiene-methacrylic acid copolymer, polyester, polyester, when considering properties such as adhesiveness and connection reliability when used as an anisotropic conductive adhesive.
Polyamide resin, nylon, polyvinyl butyral resin, styrene-ethylene-butylene-styrene block copolymer, and the like can be more preferably used.

The epoxysilane coupling agent used in the present invention is not limited as long as it is represented by the formulas (3) and (4), and may be used alone or as a mixture of two or more. good. Specifically, for example, as an epoxysilane coupling agent, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4 epoxycyclohexyl) ethyltriethoxysilane, β
-(3,4 epoxycyclohexyl) ethyldimethoxymethylsilane, β- (3,4 epoxycyclohexyl)
Ethylmethoxydimethylsilane, β- (3,4 epoxycyclohexyl) ethyldiethoxyethylsilane, β-
(3,4 epoxycyclohexyl) ethylethoxydiethylsilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane,
γ-glycidoxypropylmethyldimethoxysilane, γ
-Glycidoxypropylmethoxydimethylsilane, γ-
Glycidoxypropylethyldiethoxysilane, γ-glycidoxypropylethoxydiethylsilane and the like can be mentioned.

In the silane coupling agents other than the epoxy silane coupling agents represented by the formulas (3) and (4),
The coupling effect between the resin composition and the adherend is low, and (3)
Only the epoxysilane coupling agent represented by the formula (4) can provide a coupling effect at a relatively low temperature and in a short time.

The conductive particles used in the present invention are not particularly limited as long as they have conductivity. Various kinds of conductive particles such as nickel, iron, copper, aluminum, tin, lead, chromium, cobalt, silver, and gold can be used. Metals, metal alloys, metal oxides, carbon, graphite, glass and ceramics, and plastic particles coated with metal can be used. Appropriate particles, materials, and amounts of these conductive particles can be selected depending on the pitch and pattern of the circuit to be connected, the thickness and material of the circuit terminals, and the like.

[0025]

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

Example 1 As shown in Table 2, 250 parts by weight of an acryloylated phenol novolak resin having the structure of the formula (5), 250 parts by weight of an allyl-modified cyanurate compound having the structure of the formula (8), 1,1,3,3
2 parts by weight of tetramethylbutyl peroxyhexanoate, 500 parts by weight of a 20% solution of a polyvinyl butyral resin (polymerization degree: 1700, butyralization degree: 68 mol%, flow softening point: 170 ° C.) in methyl ethyl ketone, caprolactan-modified (meta 2) acryloyloxyethyl acid phosphate in an amount of 2 parts by weight and β- (3,4 epoxycyclohexyl) ethyltrimethoxylan in 0.1 part by weight.
6 parts by weight and 2.8 parts by weight of Ni / Au plated polystyrene particles are mixed and uniformly dispersed, and then cast on a release-treated polyethylene terephthalate film so that the thickness after drying becomes 45 μm. Drying to obtain an anisotropic conductive adhesive.

[0027]

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[0028]

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<Examples 2 to 16> Anisotropically conductive electroadhesives were obtained in the same manner as in Example 1 by using the formulations shown in Table 2.

<Comparative Example 1> An anisotropic conductive adhesive was obtained according to the formulation shown in Table 3 in the same manner as in Example 1.

The anisotropic conductive adhesives obtained in the above Examples and Comparative Examples were evaluated by the following methods. <Evaluation method of anisotropic conductive adhesive> Preparation of evaluation sample The adherend was copper foil / polyimide = 25/75 μm and 0.5 μm
m tin-plated TCP (pitch: 0.30 mm, number of terminals: 60) and 0.8 mm thick 4-layer plate (FR-4) inner layer
The outer copper foil 18 μm flash gold plated PCB (pitch 0.30 mm, number of terminals 60) was used.

2. Adhesion strength measurement method Crimping was performed under the conditions of 150 ° C., 30 kg / cm ² , and 15 seconds.
The evaluation was performed by a 0 ° peel test. 3. Connection Reliability Measurement Method The connection resistance was measured immediately after sample preparation and at a temperature of −40 ° C. to 150 ° C., and after 100 times of treatment. 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., 30 kg / cm ² and 15 seconds, and the connection resistance was measured. A value of 1.5Ω or less was evaluated as ○, and a value exceeding 1.5Ω was evaluated as ×.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

By using the anisotropic conductive adhesive of the present invention, fine circuit electrodes can be connected at a low temperature of about 150 ° C., and excellent heat resistance, adhesiveness and connection reliability can be obtained. It is also possible to connect at an extremely low temperature in a short time, and an anisotropic conductive adhesive excellent in adhesiveness, connection reliability, storage stability and repairability can be obtained.

Claims (3)

[Claims] Anisotropically obtained by dispersing conductive particles in a resin composition comprising a radical polymerizable resin, an organic peroxide, a thermoplastic elastomer and a phosphate represented by the formula (1) as essential components. An anisotropic conductive adhesive, wherein all or a part of the radically polymerizable resin is an allyl-modified cyanurate compound represented by the formula (2). Embedded image Embedded image 2. The radical polymerizable resin according to claim 1, wherein the ratio of the allyl-modified cyanurate compound represented by the formula (2) to the other radical polymerizable resin is in the range of 10: 1 to 1:10. Anisotropic conductive adhesive. 3. The resin composition further comprises the formula (3) and / or
Or the anisotropic conductive adhesive according to claim 1, further comprising an epoxysilane coupling agent represented by the formula (4). Embedded image Embedded image