JPH0462714A - Anisotropic conductive adhesive - Google Patents

Abstract

PURPOSE:To improve the reliability of anisotropic conductiye adhesive owing to excellent heat-resistant and humidity-resistant chracteristics and strength of adhesive bonding, by containing thermoplastic elastomers, tackifiers, silane- base coupling agents having ethylenic double bond, crosslinking promoting catalysts, and conductive particles in the anisotropic conductive adhesive. CONSTITUTION:An anisotropic conductive adhesive can be used by adding such compositions which comprises 50 to 100 weight-parts of tackifers such as terpene base resins etc., 0.5 to 5 weight-parts of silane base coupling sgents having ethylenic double bond in molecules, such as vinyl trichlorosilan etc., 0.1 to 10%, in volumetric ratio, of conductive particles, such as carbon, solders, and the like with their average particle diameter being one-fifth to two-thirds of the adhesive layer thickness, 0.1 to 3 weight-parts of crosslinking promoting catalysts, such as organic/peroxide hydroperoxide etc, to 100 weight-parts of thermoplastic elastomers, such as SBS etc., as essential compositions, and by dissolving in or dispersing through an adequate solvent to be collected as a pasty mass, and by applying the mass on top of a workpiece and heating and drying it thereafter.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to anisotropic conductive adhesives, particularly for the assembly of electronic components or the electrical connection of terminals of circuit boards by heating and pressurizing. This invention relates to an anisotropically conductive adhesive suitable for simultaneous use.

(Prior art) Anisotropic conductive adhesives have already been put into practical use on the market as adhesive materials for connecting circuit board terminals of electronic components, but synthetic rubber-based, polyester-based, etc. carbon or graphite particles in thermoplastic or thermosetting insulating resins such as epoxy, phenoxy or
Plastic particles containing nickel, gold, copper, and solder alone
Seeds or those coated with two or more types, as well as nickel,
In practical use, metal particles such as gold, copper, solder, and alloy particles are dispersed and processed into a film or printing paste.

(Problem to be solved by the invention) However, with conventional thermoplastic adhesives, under high temperature and high humidity conditions, the adhesive's holding power decreases, weakening the contact between the conductive particles and the terminals of the circuit board, and causing an increase in connection resistance. There are some drawbacks. In addition, thermosetting adhesives are less affected by high temperature and high humidity than thermoplastic adhesives, but they do have problems such as the long heating and pressing time during the work process, and the fact that the adherend is There is a drawback that the sushi cannot be removed and the parts may be damaged.

An object of the present invention is to improve the drawbacks of these conventionally known anisotropically conductive adhesives.

(Means for Solving the Problems) The anisotropic conductive adhesive of the present invention includes a thermoplastic elastomer, a tackifier, a silane coupling agent having an ethylenic double bond in the molecule, a crosslinking promoting catalyst, and conductive particles. It is characterized by containing.

To explain each component of the anisotropic conductive adhesive of the present invention, examples of the thermoplastic elastomer include polyhinyl chloride-vinyl acetate copolymer, ethylene-vinyl chloride copolymer, ethylene-acrylic acid copolymer, and ethylene-vinyl chloride copolymer. Vinyl acetate copolymers or their saponified products, styrene-butadiene-styrene copolymers (SBS), styrene-isoprene-styrene copolymers (SIS), acrylic rubber/chloroprene rubber, ethylene-propylene copolymers There are polymer rubbers, etc. Particularly preferred are styrene copolymer elastomers such as SBS and SIS.

As the tackifier, modified wood rosin, alkylphenol resin, terpene resin, polyketone resin, or hydrogenated products thereof can be used, and terpene resin is particularly preferred.

For example, when SBS is used as a thermoplastic elastomer and a terpene resin is used as a tackifier, the terpene resin is compatible with the polybutadiene block phase of SBS, significantly improving adhesive strength or surface tack. effect. The amount of the tackifier added varies depending on the type of thermoplastic elastomer to be bonded, but is usually 30 to 120 parts by weight per 100 parts by weight of the thermoplastic elastomer such as SBS.
Particularly preferred is 50 to 100 parts by weight. If it is too small, the adhesive strength or surface tackiness tends to decrease, and if it is too large, the cohesive force when heated is reduced, resulting in a decrease in adhesive strength.

As the silane-based strength/twisting agent having an ethylenic double bond in the molecule, tonysilane (meth)acryloxysilane, etc. can be used, and specifically, vinyltrichlorosilane, vinyltris(2-methoxyethoxy)silane, α
-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, tris-(2-methoxyethoxy)vinylsilane, 3-(trimethoxysilyl)propyl methacrylate, and the like.

These silane coupling agents having an ethylenic double bond in their molecules have the function of improving adhesion and reliability, particularly to glass materials such as glass substrates. The amount of these silane coupling agents added is preferably about 0.5 to 1 part of 5i per 100 parts by weight of the thermoplastic elastomer, and their addition improves the adhesive strength and reliability to the glass substrate at high temperatures. Significant improvement. If the amount added is too small, there will be no effect, and if the amount added is too large, the adhesive strength will decrease.

Conductive particles include carbon, graphite particles, nickel, solder, gold, copper, alone or a combination of two or more coated on plastic particles, or metal particles such as nickel, solder, gold, copper, or alloys. Any one that has particles dispersed and that is currently in practical use may be used.

Further, the average particle size of the conductive particles varies depending on the thickness of the adhesive layer, but is preferably in the range of 5 to 40 μm, and the average particle size of the conductive particles is preferably 175 to 2/3 of the thickness of the adhesive layer. If the diameter of the conductive particles is less than 115 times the thickness of the adhesive layer, poor connection will occur, and if the diameter is 2/3 or more, the gap in the circuit cannot be filled, and air bubbles will be interposed due to floating.

Further, the content of the conductive particles is 0.0% by volume with respect to the adhesive.
A range of 1 to 10% is preferred. At 0.1% by volume or less,
Sufficient connection resistance cannot be obtained and there are large variations, and 10
If the amount exceeds the volume %, the adhesive strength decreases or the insulating property of the adhesive layer in the plane direction decreases.

As the crosslinking promoting catalyst, conventionally well-known organic peroxides, platinum chloride catalysts, and the like are used. Specific examples of organic peroxides include hydroperoxide, dialkyl peroxide, peroxyketal, peroxyester,
Examples include diacyl peroxide.

These crosslinking promoting catalysts have the function of promoting crosslinking between the thermoplastic elastomer and the silane coupling agent having an ethylenic double bond in the molecule. The amount of these crosslinking promoting catalysts to be added is determined according to the conventionally known general amounts of these catalysts to be added, but it is usually desirable that the amount of organic peroxide be 0.1 to 3 parts by weight per 100 parts by weight of the thermoplastic elastomer. Further, the platinum chloride catalyst is preferably used in an amount of 1.times.10@-6 to 1.times.10@-4 parts by weight.

The anisotropically conductive connecting agent of the present invention essentially contains these components, and the manufacturing method thereof is not particularly limited, but usually includes a thermoplastic elastomer, a tackifier, and a silane cup having an ethylenic double bond in the molecule. A liquid or paste-like product is obtained by dissolving or dispersing the ring agent, crosslinking promoting catalyst, and conductive particles in an appropriate solvent in an appropriate order. Then, this solution or paste is formed into a sheet with appropriate dimensions, or it is directly applied to areas that require electrical connection such as electronic circuits by means such as coating, and anisotropically conductive adhesive is attached. Electronic boards, etc. Note that a sheet-like anisotropically conductive adhesive can also be obtained by transferring the above-mentioned solution or paste onto a release film by screen printing or the like. In these processes, the solvent is volatilized after being attached to the adherend by coating, transfer, etc., and this solvent volatilization is preferably carried out by heating and drying at about 100° C., and this heating accelerates the crosslinking reaction. The anisotropically conductive adhesive material of the present invention thus obtained has excellent adhesive strength and reliability, and also has excellent heat resistance and moisture resistance.

(Example) The present invention will be explained below with reference to Examples and Comparative Examples.

Examples 1 to 3, Comparative Examples 1 to 3 100 parts by weight of SBS type block copolymer TR-1186 [trade name of Shell Chemical Co., Ltd.], tenpene-based resin YS Polyster T-145 [Yasuhara Chemical Co., Ltd.] with a softening temperature of 150°C 50 to 90 parts by weight of Co., Ltd.'s product name, 1 part by weight of organic peroxide diacyl peroxide as a crosslinking promoting catalyst, or 10-5 parts by weight of platinum chloride hexahydrate, and vinyl trimethoxy as a silane coupling agent. 2 parts by weight of silane and 5% by volume of solder powder with an average particle size of 10μ as conductive particles are dissolved or dispersed in 400 parts by weight of toluene to form a film thickness of 30μ on the fluorine film. A film was formed using a bar coater as described above, and heated at 100℃×
Toluene was volatilized after 10 minutes. Then, the obtained anisotropically conductive adhesive was transferred onto a glass substrate on which indium oxide was vapor-deposited, and bonded to a flexible printed circuit board. This adhesion is carried out at 150℃ x 3 from the flexible printed circuit board side.
The test was carried out by heating and pressurizing 0 kg for 10 seconds. Further, when this product was left in a 60° C. x 95% atmosphere for 200 hours and the change in connection resistance value was examined, the results shown in Table 1 were obtained. (Example 1.2.3.4) A test was also conducted by forming a coating film similar to the above without adding the organic oxide or silane coupling agent. (Comparative example 1
,2.3)

Claims (5)

[Claims] (1) An anisotropic conductive adhesive characterized by containing a thermoplastic elastomer, a tackifier, a silane coupling agent having an ethylenic double bond in the molecule, a crosslinking promoting catalyst, and conductive particles. (2) The anisotropically conductive adhesive according to claim 1, which is in the form of a sheet. (3) The anisotropically conductive adhesive according to claim 1 or 2, wherein the silane coupling agent is vinylsilane or (meth)acryloxysilane. (4) The anisotropic conductive adhesive according to any one of claims 1 to 3, wherein the thermoplastic elastomer is a styrene copolymer elastomer. (5) Claims 1 to 4 wherein the tackifier is a terpene resin.
The anisotropically conductive adhesive according to any one of Item 1 above.