JP2000044905A - Anisotropic, electrically conductive adhesive and electronic equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic, electrically conductive adhesive that effects a good electrical connection of microcircuits to each other at a low temperature within a short time by incorporating a radical polymerizable resin (A), an organic peroxide (B), a thermoplastic elastomer (C) and a phosphate (D) into a resin composition. SOLUTION: The phosphate (D) incorporated into the resin composition is represented by the formula, wherein R is CH2=CR1CO(OR2)n; (l) and (m) are each 1 or 2; and provided that R1 is -H or -CH3; R2 is -C2H4-, -C3H6- or the like; and n is an integer of 1-10. The content of the phosphate (D) is preferably blended in a weight ratio of (D)/ (A)+(B)+(C)}=(0.1-50)/100. For example, on connecting TCP and PCB for use in LCD with use of the adhesive, the phosphate (D) acts so as to effect a coupling of the radical polymerizable resin (A) with metal parts of an adherend (TCP, PCB or the like), whereby good adhesion and connection reliability can be accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrical connection between fine circuits such as a connection between an LCD (liquid crystal display) and a TCP (tape carrier package) and a connection between a TCP and a PCB (printed circuit board). The present invention relates to an anisotropic conductive adhesive to be used, and an electronic device using the same.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays LCD and TCP
The necessity of various fine circuit connections, such as connection between a TCP and a PCB, has been dramatically increased, and an anisotropic conductive adhesive in which conductive particles are dispersed in an adhesive resin has been used as a connection method. ing. In this method, an anisotropic conductive adhesive is sandwiched between members to be connected and heated and pressed, so that electrical insulation is maintained between adjacent terminals in the surface direction, and electrical conduction is provided 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, 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, the connection reliability was low and it was not able to withstand a long-term environmental test.

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
F3 amine complexes, dicyandiamide, organic acid hydrazide, a compound containing a latent curing agent such as an imidazole compound and the like have been proposed, but those having excellent storage stability require a long time or high temperature for curing, and a low temperature. -Those which can be cured in a short time have a problem that storage stability is inferior, and all have advantages and disadvantages.

In addition to the problems described above, in connection workability between fine circuits using a thermosetting type anisotropic conductive adhesive, a member once connected due to a displacement or the like is damaged or damaged. There has been a growing demand for peeling without damage and joining (so-called repair) again.
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.

[0008] In particular, recently, the LCD module has rapidly increased 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, a connection pattern shift occurs due to the extension of TCP at the time of connection, and a member inside the LCD is thermally affected by the temperature at the time of connection because the connection portion is narrow. The problem 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.

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, when trying to connect at low temperature with an epoxy resin-based anisotropic conductive adhesive, which is the mainstream of thermosetting type, it is necessary to lengthen the connection time to cure the resin,
It was not practically applicable.

As an anisotropic conductive adhesive which enables low-temperature connection, an adhesive resin in which a cationically polymerizable substance and a sulfonium salt are blended and conductive particles are dispersed (JP-A-7-90237). Also, there has been proposed an epoxy resin or the like and a dispersion of conductive particles 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: and an aminosilane coupling agent further added for the purpose of improving adhesiveness and connection reliability have 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. , And adhesion, connection reliability,
There is an increasing demand for an anisotropic conductive adhesive having excellent storage stability and repairability.

[0012]

SUMMARY OF THE INVENTION The present invention relates to an LCD and a TFT.
In electrical connection between microcircuits such as connection with CP and connection between TCP and PCB, especially connection at low temperature and short time is possible, and adhesion, connection reliability, storage stability and repairability are improved. Another object of the present invention is to provide an excellent heat-curable anisotropic conductive adhesive.

[0013]

The present invention provides an anisotropic conductive adhesive comprising conductive particles dispersed in a resin composition,
The resin composition comprises a radical polymerizable resin (A), an organic peroxide (B), a thermoplastic elastomer (C), and a phosphate ester (D) represented by the formula (1). Adhesive.

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In a more preferred embodiment, the mixing ratio of each component in the resin composition is (D) / {(A) + (B) + (C)} = (0.1 to 5)
0) / 100, and the resin composition is an anisotropic conductive adhesive further containing an epoxysilane coupling agent (E) represented by the formula (2) and / or (3). .

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The mixing ratio of each component in the resin composition is expressed as {(D) + (E)} / {(A) + (B) + (C)} =
(0.1-20) / 100, and the phosphate ester (D) represented by the formula (1) and the epoxysilane coupling agent represented by the formula (2) and / or (3) ( This is an anisotropic conductive adhesive in which the total compounding ratio of E) is (D) / (E) = 90/10 to 10/90 by weight.

Further, using the anisotropic conductive adhesive described above,
This is an electronic device in which electronic and electrical components are electrically connected. As a further preferred form, the electronic and electric parts are:
A semiconductor element, a semiconductor device, a printed circuit board, a liquid crystal display (LCD) panel, a plasma display panel (PDP), an electroluminescence (EL) panel, a field emission display (FED) panel, a tape carrier package, and the electronic device is an image. Display module (LCD, PDP, EL, FE)
D), electronic devices that are computers, televisions, measuring devices, and communication devices.

[0017]

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 a phosphate ester represented by the formula (1). When TCP and PCB are connected, phosphate ester acts to couple the radical polymerizable resin with the metal part of the adherend (TCP, PCB, etc.), so that the conventional radical-curable anisotropic conductive adhesive is used. Adhesiveness and connection reliability that could not be obtained with the agent can be obtained. Furthermore, (2),
By combining the epoxy silane coupling agent represented by the formula (3), it is possible to further obtain the coupling effect between the radical polymerizable resin and the metal part of the adherend.

In the case of phosphate esters other than the formula (1), the effect of coupling 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. Also,
With a silane coupling agent other than the epoxy silane coupling agent represented by the formulas (2) and (3), the coupling effect between the resin composition and the adherend is low, and the silane coupling agent is represented by the formulas (2) and (3). Only the epoxy silane coupling agent can obtain a coupling effect at a relatively low temperature in a short time.

Examples of the radical polymerizable resin used in the present invention include acrylates such as (meth) acryloylated phenol novolak resin having phenolic hydroxyl group, vinyl ester resin, urethane acrylate resin, unsaturated polyester resin, diallyl phthalate resin, And maleimide resins. Among them, curability and storage,
A (meth) acryloylated phenol novolak resin having a phenolic hydroxyl group, which has both heat resistance, moisture resistance and chemical resistance of the cured product, a vinyl ester resin, a urethane acrylate resin, and a maleimide resin can be suitably used.

Further, in order to ensure the preservability, it is possible to add a polymerization inhibitor such as quinones, polyhydric phenols and phenols in advance (see, for example, JP-A No.
No. 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 can be used after being diluted with various monomers or a common reactive diluent.

The organic peroxide used in the present invention is not particularly limited. For example, 1,1,3,3-
Tetramethylbutyl peroxy-2-ethyl hexanate, t-butyl peroxy-2-ethyl hexanate,
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. Considering properties such as adhesion and connection reliability when anisotropically conductive adhesive is used among them, acrylonitrile-butadiene-methacrylic acid copolymer, polyester,
Polyamide resin, nylon, polyvinyl butyral resin, styrene-ethylene-butylene-styrene block copolymer, and the like can be more preferably used.

The phosphate in the present invention is (1)
It is not particularly limited as long as it is represented by the formula,
They may be used alone or in combination of two or more. Specific examples of the phosphoric acid ester include (meth) acryloyloxyethyl acid phosphate, (meth) acryloyloxypropyl acid phosphate, (meth) acryloyloxyisopropyl acid phosphate, and (meth) acrylolyloxy polyoxyethylene glycol acid phosphate. , (Meth) acryloyloxy polyoxypropylene glycol acid phosphate,
Examples include caprolactone-modified (meth) acryloyloxyethyl acid phosphate, di (meth) acryloyloxypropyl acid phosphate, and di [caprolactone-modified (meth) acryloyloxyethyl] acid phosphate.

The epoxy silane coupling agent used in the present invention is not limited as long as it is represented by the formulas (2) and (3), and may be used alone or as a mixture of two or more. Specifically, as the epoxy silane coupling agent, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4 epoxycyclohexyl) ethyltriethoxysilane, β- (3,4 epoxycyclohexyl) ethyl Dimethoxymethylsilane, 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.

Phosphate ester (D) represented by the formula (1)
The compounding amount of {(D)} / {(A) + (B) + (C)} = (0.1 to
50) / 100. If the amount is less than 0.1% by weight, a sufficient bonding force cannot be obtained because the coupling effect cannot be obtained, and if the amount exceeds 50 parts by weight, the curability and storage stability decrease. Such a problem arises.

The compounding amounts of the phosphoric acid ester (D) represented by the formula (1) and the epoxysilane coupling agent (E) represented by the formulas (2) and (3) are expressed by the following weight ratio: ) + (E)｝ / {(A) + (B) + (C)} =
(0.1-20) / 100 is more preferable. If the amount is less than 0.1% by weight, a sufficient bonding force cannot be obtained because a coupling effect cannot be obtained, and if the amount exceeds 20 parts by weight, curability and storage stability decrease. Such a problem arises.

Phosphate ester (D) represented by the formula (1)
The mixing ratio of the epoxysilane coupling agent (E) represented by the formulas (2) and (3) is preferably (D) / (E) = 90/10 to 10/90 by weight. Phosphate ester (D) ratio of 9
If it exceeds 0/10, the pH of the resin composition will be low, which causes a problem such as a decrease in storage stability. Also, 10
If it is less than / 90, a problem arises in that a sufficient coupling effect cannot be obtained and the adhesive strength is deteriorated.

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.
Appropriate particles, materials, and amounts of these conductive particles can be selected according to the pitch and pattern of the circuit to be connected, the thickness and material of the circuit terminals, and the like.

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. Since the agent contains the phosphate ester represented by the formula (1) and the epoxysilane coupling agent represented by the formulas (2) and (3), excellent adhesiveness and connection reliability can be obtained. Connection at an extremely low temperature and in a short time is also possible, and an anisotropic conductive adhesive excellent in adhesiveness, connection reliability, storage stability and repairability can be obtained.

Further, the anisotropic conductive adhesive of the present invention can be used for electronic devices such as semiconductor elements, semiconductor devices, printed circuit boards, flexible printed circuit boards, liquid crystal display panels, PDP panels, EL panels, FED panels, and tape carrier packages. -Can be used for electrical joining of electrical components. Their electrical connections are made with various image display modules (LCD, PDP, EL, FED, etc.), computers,
It can be used for televisions, measuring instruments, communication equipment, and other electronic equipment, and by using these, it is possible to achieve the miniaturization, weight reduction, and ease of manufacture of electronic equipment, as well as ease of repair. I have.

[0031]

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

[0032]

[Table 1]

[0033]

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[0034]

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[0035]

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Example 1 200 parts by weight of a 50% solution of a methacryloylated phenol novolak resin having the structure of formula (4) dissolved in methyl ethyl ketone, (7)
350 parts by weight of a 20% solution of a diaminodiphenylmethane type bismaleimide resin having the structure of the formula in tetrahydrofuran, 5 parts by weight of 1,1,3,3-tetramethylbutylperoxyhexanoate, the formula (9) A 20% solution of an acrylonitrile-butadiene-methacrylic acid copolymer having the structure of
Parts by weight, 5 parts by weight of caprolactan-modified (meth) acryloyloxyethyl acid phosphate, Ni / Au
After mixing and uniformly dispersing 7 parts by weight of the plated polystyrene particles, they are cast and dried on a release-treated polyethylene terephthalate film so that the thickness after drying becomes 45 μm, and then cut into 2 mm width. Thus, an anisotropic conductive adhesive was obtained.

<Examples 2 to 18> Anisotropically conductive electroadhesives were obtained in the same proportions as in Example 1 at the mixing ratios shown in Tables 2 and 3.

[0038]

[Table 2]

[0039]

[Table 3]

1. Preparation of evaluation sample The adherend was copper foil / polyimide = 25/75 μm and 0.5 μm
m tin-plated TCP (pitch 0.3 mm, number of terminals 60) and 0.8 mm thick four-layer board (FR-4) inner and outer copper foil 18 μm flash gold-plated PCB (pitch 0.
3 mm, 60 terminals). 2. Adhesive strength measurement method The adhesive strength was measured at 130 ° C., 30 kg / cm ² , and 15 sec, 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 adhesive in a 25 ° C. atmosphere for 2 weeks,
Crimping was performed under the conditions of 30 ° C., 30 kg / cm ² , and 15 s, and the connection resistance was measured. When the resistance was 1.5 Ω or less, the result was indicated by “○”. 5. Repairability evaluation method Anisotropic conductive adhesive was applied at 130 ° C, 30 kg / cm ² , 15 s
After crimping under the condition of ec and peeling off TCP at room temperature,
The resin remaining on the PCB was wiped off with acetone, and then a new TCP was pressed on the PCB using a new anisotropic conductive adhesive, and the connection resistance and adhesive strength were measured. The connection resistance is 1.5Ω or less (good repairability),
X (poor repairability) when the resistance was 1.5 Ω or more, ○ when the adhesive strength was 80% or more of the value before repair, and x when the adhesive strength was less than 80%.

<Comparative Examples 1 to 4> Anisotropic conductive adhesives were obtained in the same proportions as in Example 1 at the mixing ratios shown in Table 4.

[Table 4]

[0042]

According to the present invention, an anisotropic conductive adhesive excellent in workability and long-term reliability can be obtained. By using this anisotropic conductive adhesive, fine circuit electrodes can be connected at a low temperature of about 130 ° C. Further, an electronic device using the anisotropic conductive adhesive can easily repair the anisotropic conductive adhesive, and is useful for improving the productivity of expensive electronic devices.

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[Procedure amendment]

[Submission date] June 3, 1999 (1999.6.3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction contents]

[0038]

[Table 2]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction contents]

[0039]

[Table 3]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0041

[Correction method] Change

[Correction contents]

[0041]

[Table 4]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01R 11/01 H01R 11/01 H

Claims (8)

[Claims] 1. An anisotropic conductive adhesive comprising conductive resin dispersed in a resin composition, wherein the resin composition comprises a radical polymerizable resin (A), an organic peroxide (B), and a thermoplastic elastomer. An anisotropic conductive adhesive comprising (C) and a phosphate (D) represented by the formula (1). Embedded image 2. The mixing ratio of each component in the resin composition is (D) / {(A) + (B) + (C)} = (0.1 to 5) by weight ratio.
The anisotropic conductive adhesive according to claim 1, wherein 0) / 100. 3. The resin composition according to claim 1, wherein the resin composition further comprises an epoxysilane coupling agent (E) represented by the formula (2) and / or (3). One side conductive adhesive. Embedded image Embedded image 4. The composition ratio of each component in the resin composition is {(D) + (E)} / {(A) + (B) + (C)} =
The anisotropic conductive adhesive according to claim 3, wherein (0.1 to 20) / 100. 5. The composition according to claim 3, wherein the mixing ratio of the phosphate ester (D) and the epoxysilane coupling agent (E) is (D) / (E) = 90/10 to 10/90 by weight. Anisotropic conductive adhesive. 6. An electronic device wherein electronic and electric parts are electrically connected using the anisotropic conductive adhesive according to claim 1. 7. The electronic / electric component is a semiconductor element, a semiconductor device, a printed circuit board, a liquid crystal display (LCD).
The electronic device according to claim 6, which is a panel, a plasma display panel (PDP), an electroluminescence (EL) panel, a field emission display (FED) panel, or a tape carrier package. 8. The electronic device according to claim 1, wherein the electronic device is an image display module (LC).
D, PDP, EL, FED), computer, television,
The electronic device according to claim 6, which is a measuring device or a communication device.