JPH09169958A - Anisotropically electroconductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermosetting type anisotropically electroconductive film, connectable at low temperatures in a short time, excellent in storage stability at normal temperatures, having excellent adhesion within a wide temperature range (-40 to +100 deg.C) after hot-pressing and curing, having an extremely small strain (stress) remaining in a joining area and capable of peeling and recarrying out the contact bonding by heating the contacted bonded films once to a prescribed temperature or above. SOLUTION: This anisotropically electroconductive film is obtained by casting a pasty mixture consisting essentially of (A) a reactional elastomer, (B) an acrylate resin, (C) a silane coupling agent, (D) an organic peroxide, (E) a solvent capable of dissolving the components and (F) electroconductive particles at [100/(0.1-10)] weight blending ratio (B)/(D) of the acrylate resin (B) to the organic peroxide (D) onto a mold releasing film, volatilizing the solvent and forming the film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electrical connection between minute circuits, and more particularly to LCD (liquid crystal display).
And flexible circuit board or TAB film connection, T
Connection between AB film and printed circuit board and semiconductor I
The present invention relates to an anisotropic conductive film used for micro joining of C and an IC mounted circuit board.

With the recent miniaturization and thinning of electronic equipment,
The need for connecting minute circuits to each other, connecting minute parts to minute circuits, and the like has increased dramatically, and anisotropic conductive adhesives and films have begun to be used as the connecting method. (For example, JP-A-59-120436, 60-
191228, 61-274394, 61-28797
4, 62-244242, 63-153534, 63
-305591, 64-81878, JP-A-1-251
787 publications). Due to further miniaturization of components, in connection work of circuits with anisotropic conductive films accompanying it, peeling and re-crimping the connected members that have been once connected without damage or damage due to misalignment etc. (so-called The adherend is damaged (for example, L due to the requirement that "repair") is possible, the shrinkage of the anisotropic conductive film during the thermosetting reaction and the strain stress of the resin itself in various atmospheres.
(Glass substrate used for CD cracks and substrate warpage)
The problem of doing is emerging. In order to solve these problems, low temperature fast curing, long life, moisture resistance,
There is a strong demand for a highly reliable thermosetting anisotropic conductive film with low distortion.

[0003]

DISCLOSURE OF THE INVENTION The present invention enables connection at a low temperature for a short time, which was not possible with the conventional thermosetting type epoxy resin / amine compound, and has storage stability at room temperature. It has excellent adhesiveness in a wide temperature range (-40 ℃ to 100 ℃) after heating and pressurizing and curing, and the strain stress remaining in the joint is extremely small. The present invention provides a heat-radical-curable hetero-conductive film that can be peeled and re-bonded by heating.

[0004]

The present invention is directed to a reactive elastomer (A), an acrylate resin (B), a silane coupling agent (C), an organic peroxide (D), and a solvent (E) for dissolving them. And a paste-like mixture containing conductive particles (F) as an essential component and a polymerization compounding ratio of the acrylate resin (B) and the organic peroxide (D) being (B) / (D) = 100 / 0.1 to 10. Is cast on a release film to volatilize the solvent to form a film, which is an anisotropic conductive film.

The reactive elastomer used in the present invention is
Carboxyl group-containing styrene-butadiene copolymer, carboxyl group-containing styrene-isoprene copolymer, carboxyl group-containing styrene-butadiene saturated copolymer, carboxyl group-containing styrene-isoprene saturated copolymer,
Carboxyl group-containing styrene-ethylene-butene-styrene copolymer, carboxyl group-containing styrene-ethylene-butene-styrene saturated copolymer, carboxylic acid-terminated acrylonitrile-butadiene copolymer, hydrogenated carboxylic acid-modified acrylonitrile-butadiene copolymer , Methyl methacrylate polymer, methyl methacrylate-butyl methacrylate copolymer, hydroxyl group-containing methyl methacrylate polymer, carboxyl group-containing methyl methacrylate polymer, carboxylic acid modified acrylic rubber, polyvinyl butyral resin, urethane resin, amino group modified polyol Resins, amino group-modified phenoxy resins, hydroxy-terminated saturated copolyester resins, carboxyl-terminated saturated copolyester resins, etc., ketone-based, alcohol-based or aromatic Used in combination as a soluble one or two or more of the solvents.

The acrylate resin used in the present invention is an acrylate resin having at least two or more acryloyl groups in one molecule. As a specific example, bisphenol A ethylene glycol modified diacrylate,
Isocyanuric acid ethylene glycol modified diacrylate, tripropylene glycol diacrylate, pentaerythritol diacrylate monostearate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolpropane propylene glycol triacrylate Acrylate, trimethylolpropane ethylene glycol triacrylate, isocyanuric acid ethylene glycol modified triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, pentaerythritol tetraacrylate and the like can be mentioned, and one kind or a combination of two or more kinds can be used.

The silane coupling agent used in the present invention is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the reactive elastomer and the acrylate resin. If it is less than 0.1 part by weight, the effect of addition is not obtained, and if it exceeds 5 parts by weight, the tackiness and hardness of the film and the adhesion to the carrier film are affected. Specific examples include γ-methacryloxypropyritrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane,
N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, vinyltri Ethoxysilane,
γ-ureidopropyltriethoxysilane and the like can be mentioned, and one kind or a combination of two or more kinds is used.

The organic peroxide used in the present invention has a --O--O-- bond in its molecule and is active by generating a free radical by heating. When roughly classified, ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxydicarbonates,
Examples thereof include peroxyesters, etc., which may be used alone or in combination of two or more. Specifically, the ketone peroxides include cyclohexanone peroxide and methylcyclohexanone peroxide, and the peroxyketals include 1,1-bis (t-butylperoxycyclohexanone) and 1,1-bis (t -Butylperoxy 3,3,5 trimethylcyclohexanone) and the like, hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide, and dialkyl peroxides such as dicumyl peroxide and di- t-butyl peroxide, etc.
Examples of diacyl peroxides include lauroyl peroxide and benzoyl peroxide, and examples of peroxydicarbonates include diisopropyl peroxydicarbonate and bis- (4-t-butylcyclohexyl) peroxydicarbonate. Examples of the esters include t-butyl peroxybenzoate, t
-Butylperoxy (2-ethylhexanoate), t
-Butyl peroxyisopropyl carbonate and the like. In consideration of the balance between storage stability, curability, and adhesiveness, peroxyketals and peroxyesters are preferable. The weight ratio of the acrylate resin (B) and the organic peroxide (D) is (B) / (D) = 100 / 0.1.
If the organic peroxide is less than 0.1 parts by weight, the curability will be insufficient, and sufficient adhesive strength and connection reliability cannot be obtained, although it depends on the target workability and reliability.
On the other hand, if the amount exceeds 10 parts by weight, the preservability (life) is deteriorated and the fluidity at the time of melting is insufficient, so that the conductive particles may not come into contact with the terminal and the conductivity may not be obtained.

The conductive particles used in the present invention are nickel,
Iron, copper, aluminum, tin, lead, chromium, cobalt,
Metals such as silver and gold, metal oxides, alloys such as solder and carbon, graphite, or conductive particles obtained by coating a metal such as glass, ceramic, or plastic with a metal by a method such as plating. Alternatively, they may be used in combination of two or more. The amount of conductive particles is 0.5 to 5% by volume based on the total composition.
Is preferred. If it is less than 0.5% by volume, stable conduction reliability cannot be obtained after connection, and if it exceeds 5% by volume, there may be a problem in insulation between adjacent circuits, which is not preferable.

The solvent used in the present invention is preferably a ketone type, alcohol type or aromatic type from the viewpoint of resin stability after compounding. Specific examples thereof include acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl alcohol, ethyl alcohol, n-butyl alcohol, toluene, xylene and the like, and one kind or a combination of two or more kinds is used.

[0011]

EXAMPLES The present invention will be specifically described with reference to Examples. Example 1 As a reactive elastomer, a polymerization degree of 170
0, acetylation degree 3 mol% or less, butyralization degree 65
A 10 wt% solution 400 obtained by dissolving a polyvinyl butyral resin with a mol softening point of 225 ° C. or higher in a toluene / ethyl acetate = 5: 1 (weight ratio) mixed solution.
100 parts by weight of isocyanuric acid ethylene glycol-modified triacrylate, 1.4 parts by weight of γ-mercaptopropyltrimethoxysilane, 1.0 part by weight of t-butylperoxybenzoate [acrylate resin (D) /
Organic peroxide (D) = 100 / 1.0] was rapidly mixed and stirred, and then 7 g of conductive particles obtained by plating Ni / Au on polystyrene spherical core material was added and uniformly dispersed, and toluene was further added. Then, it was cast on the 4-fluoroethylene-perfluoroalkylvinylether copolymer film so that the thickness after drying was 25 μm and dried to obtain an anisotropic conductive film.

Example 2 As a reactive elastomer,
A hydroxyl group-containing polyester resin having a molecular weight of 20,000 and a hydroxyl value of 4 mgKOH / g is toluene / methanol = 1: 1.
(Weight ratio) An anisotropic conductive film was obtained in the same manner as in Example 1 except that 80 parts by weight of a 50% by weight solution obtained by dissolving in a mixed solution was used.
<Example 3> Except that 80 parts by weight of a 50% by weight solution obtained by dissolving a carboxyl group-containing methyl methacrylate polymer in a toluene / methylethylketone = 1: 1 (weight ratio) mixed solution was used as the reactive elastomer. An anisotropic conductive film was obtained in the same manner as in Example 1. Example 4 An anisotropic conductive film was obtained in the same manner as in Example 1 except that 1.4 parts by weight of γ-methacryloxytrimethoxysilane was used as the silane coupling agent.

Examples 5 and 6 In Example 5, 100 parts by weight of dipentaerythritol penta and hexaacrylate were used in place of ethylene glycol modified isocyanuric acid triacrylate, and in Example 6, 100 parts by weight of pentaerythritol tetraacrylate was used. An anisotropic conductive film was obtained in the same manner as in Example 1 except that it was used. << Examples 7 and 8 >> In Example 7, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane was used in place of t-butylperoxybenzoate.
An anisotropic conductive film was obtained in the same manner as in Example 1 except that 0 part by weight was used in Example 8 and 1.0 part by weight of benzoyl peroxide was used.

Comparative Example 1 As a reactive elastomer, a polyvinyl butyral resin having a polymerization degree of 1700, an acetylation degree of 3 mol% or more, a butyralization degree of 65 mol% or more and a flow softening point of 225 ° C. is toluene / ethyl acetate = 5: 1.
(Weight ratio) 10% by weight obtained by dissolving in a mixed solution 10
0 parts by weight of bisphenol A type epoxy resin (epoxy equivalent of 4000 g / eq) toluene / butyl acetate =
20 parts by weight of a 50% by weight mixed solution of 3: 1 (weight ratio) and 50 parts by weight of a microencapsulated imidazole derivative epoxy compound were rapidly stirred and mixed, and a polystyrene spherical core material was plated with Ni / Au to conduct electricity. 7 g of particles
And evenly disperse, and then add toluene and
An anisotropic conductive film was obtained by casting and drying on a -fluorinated ethylene-perfluoroalkyl vinyl ether copolymer film so that the thickness after drying was 25 µm.

Comparative Example 2 As a reactive elastomer,
A hydroxyl group-containing polyester resin having a molecular weight of 20,000 and a hydroxyl value of 4 mgKOH / g is toluene / methanol = 1: 1.
(Weight ratio) An anisotropic conductive film was obtained in the same manner as in Comparative Example 1 except that 80 parts by weight of a 50% by weight solution obtained by dissolving in a mixed solution was used. Comparative Example 3 Except that 80 parts by weight of a 50 wt% solution obtained by dissolving a carboxyl group-containing methyl methacrylate polymer in a toluene / methyl ethyl ketone = 1: 1 (weight ratio) mixed solution was used as the reactive elastomer. An anisotropic conductive film was obtained in the same manner as in Comparative Example 1. << Comparative Examples 4 and 5 >> In Comparative Example 4, 0.05 parts by weight of t-butylperoxybenzoate [(B) / (D) = 100]
/0.05] and in Comparative Example 5 15 parts by weight of t-butylperoxybenzoate [(B) / (D) = 100/1
5] was used in the same manner as in Example 1 to obtain an anisotropic conductive film.

<< Evaluation Method >> The anisotropic conductive films obtained in these Examples and Comparative Examples were evaluated for storage stability, adhesive strength, repairability and long-term reliability.
Shown in All anisotropic conductive films used as test pieces had a thickness of 25 μm, and the adherend was copper foil / polyimide =
35μm / 75μm 0.4μm tin plated T
AB (pitch 0.10 mm, number of terminals 200) and 1.1 mm thick glass (hereinafter referred to as ITO glass) having an indium / tin oxide conductive film having a sheet resistance value of 30 Ω formed on the entire surface were used. -Storage stability: After the anisotropic conductive film was left at room temperature (23 ° C) and 40 ° C, it was confirmed that it melted on a hot plate at 120 ° C. -Adhesive strength: Adhesion was performed under the conditions of 150 ° C, 30 kg / cm ² and 15 seconds, and the 90 ° peeling test was used for evaluation. Repairability: A test piece that was once joined by thermocompression bonding was heated to 150 ° C. on a hot plate and peeled off, and it was observed whether the connected member could be peeled off without damage. ○ means peeled without damage, × means peeled.・ Connection reliability: -40 ° C / 30 minutes, 25 ° C / 5 minutes, 80
250 ° C / 30 minutes, 25 ° C / 5 minutes temperature cycle test
After cycling, the connection resistance between adjacent terminals was measured. Those whose resistance could not be measured were regarded as poor conduction (OPEN). The following evaluation results are shown in Tables 1 and 2.

Table 1 Example 1 2 3 4 5 6 7 8 Storage stability Room temperature ○ ○ ○ ○ ○ ○ ○ ○ 40 ° C ○ ○ ○ ○ ○ ○ ○ ○ Adhesion room temperature 620 590 720 640 780 810 620 590 (g / cm) 60 ℃ 530 480 630 620 610 730 580 430 Repairability ○ ○ ○ ○ ○ ○ ○ ○ Connection reliability Initial 1.3 1.9 1.8 1.5 1.6 1.7 1.6 1.6 (Ω) After treatment 1.7 2.1 2.2 1.7 2.0 2.1 1.9 2.0

Table 2 Comparative Example 1 2 3 4 5 Storage stability Room temperature ○ ○ ○ ○ × 40 ° C ○ ○ ○ ○ × Adhesion room temperature 240 180 260 360 690 (g / cm) 60 ° C 270 160 240 150 580 Repairability ○ ○ ○ ○ ○ Connection reliability Initial OPEN OPEN OPEN OPEN 4.9 (Ω) After processing OPEN OPEN OPEN OPEN 8.5

[0019]

According to the present invention, it is possible to obtain an anisotropic conductive film having an excellent balance of adhesion and workability at low temperature / short time connection, high reliability, and low connection resistance.

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Claims (2)

[Claims] 1. A reactive elastomer (A), an acrylate resin (B), a silane coupling agent (C), an organic peroxide (D), a solvent (E) which dissolves these, and conductive particles (F) are essential. As a component, the weight mixing ratio of the acrylate resin (B) and the organic peroxide (D) is (B) / (D) =
An anisotropic conductive film, characterized in that a paste-like mixture of 100 / 0.1 to 10 is cast on a release film to volatilize a solvent to form a film. 2. The anisotropic conductive film according to claim 1, wherein the acrylate resin contains two or more acrylic groups or methacrylic groups in one molecule.