JPH03110711A - Anisotropic conductive adhesive composition - Google Patents

Abstract

PURPOSE:To obtain an anisotropic conductive abusive composition providing a wide range of joining conditions and high reliability by compositing the anisotropic conductive adhesive composite of an adhesive matrix resin and a conductive material, the resin consisting of a monoliquid type epoxy modified thermosetting resin and a thermoplastic resin. CONSTITUTION:An anisotropic conductive adhesive composite comprises an adhesive matrix resin and a conductive material, the matrix resin consisting of a one liquid-component type epoxy modified thermosetting resin and a thermoplastic resin, Preferably, the adhesive matrix resin is itself excellent in an electrical insulating property and has fluidity such that it can flow through a space between two opposite parts to be stuck to each other, and also the adhesive matrix resin can be hardened by heat, light and electron beams. As the one liquid-component type epoxy modified thermosetting resin, epoxy resin modified by one or two kinds of resins such as an alkide resin, phenor resin and melamine resin is preferable, and as the thermosetting resin urethane resin is preferable on account of conductance reliablity. An anisotropic conductive adhesive composite excellent in treatability and whose connecting parts are excellent in heat resistance and thermal durability is obtained in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an anisotropically conductive adhesive composition, which is used for assembling electrical parts, particularly for connecting electrical parts and circuit boards, or for connecting circuit boards to each other. The present invention relates to an anisotropically conductive adhesive composition suitably used for connections between.

[Prior art] Conventionally, liquid crystal displays and FPCs (FI ex 1b
The connection terminals have a fine pitch (le printed circuit), connection between circuit boards, etc.
For example, as a method for connecting electrical components lined up with a circuit count of 5 circuits/mm, a connection method using an anisotropic conductive adhesive proposed in Japanese Patent Application Laid-Open No. 61-74205 and the like is well known. Most conventional anisotropically conductive adhesives are preferably used in the form of a paste or film made by randomly dispersing conductive particles in an adhesive resin. The method of use is to place this anisotropically conductive adhesive between opposing circuits and apply pressure and heat, etc., to simultaneously connect the opposing circuits electrically and to provide insulation between adjacent circuits. This is to adhesively fix the circuit.

As one of the conventional anisotropic conductive adhesives, one in which metal powder is dispersed in a thermoplastic resin is known. In this anisotropic conductive adhesive, a plurality of metal powders are connected to opposing circuits by point contact, and the opposing circuits are fixed with a thermoplastic resin.

However, since these use thermoplastic resin, there is a problem with the heat resistance of the connected parts, and the thermoplastic resin tends to thermally swell during storage, resulting in poor contact between the metal powder and the circuit part, resulting in poor conductivity. This is not preferable in terms of continuity reliability because it is easily interrupted.

For the purpose of improving the above-mentioned conduction reliability, there has been an attempt to connect polystyrene particles coated with metal with an anisotropic conductive adhesive using conductive powder. In this method, metal-coated polystyrene particles are deformed by heat and pressure during connection, allowing surface connection to the circuit. As a result, conduction reliability is improved, but in practice, the range of conditions during connection is narrow, and strict control of temperature, pressure, time, etc. is required. For example, if the conditions are even slightly deviated from the preferred conditions during connection, the polystyrene particles will be abnormally deformed due to strong local stress, the metal coated on the surface will peel or break, and the electrical connection of the connected body will likely be interrupted. The current situation is that reliability is lacking. There is also an attempt to connect with an anisotropic conductive adhesive using a thermosetting resin instead of a thermoplastic resin. However, this method has the disadvantage that during storage under cold conditions such as heat shock, the thermosetting resin between opposing circuits tends to crack, and the electrical connection is likely to be interrupted.

The present inventors have arrived at the present invention as a result of intensive studies on anisotropically conductive adhesive compositions that are compatible with a wide range of connection conditions, have high reliability, and are capable of unprecedented ultra-high density circuit connections. It is something.

[Problems to be Solved by the Invention] Therefore, the first object of the present invention is to provide an anisotropically conductive adhesive that is easy to handle and can be connected with a wide range of connection conditions and can be connected with simple work. An object of the present invention is to provide a drug composition.

A second object of the present invention is to provide an anisotropic conductive adhesive composition whose connected product has excellent heat resistance and cold durability. Furthermore, the third object of the present invention is to provide an anisotropic conductive adhesive that enables ultra-high-density connections (10 or more connected circuits/mm), which has been in increasing demand with the recent increase in the density of electrical components. An object of the present invention is to provide a drug composition.

[Means for Solving the Problems] An object of the present invention is to provide a composition comprising an adhesive matrix resin and a conductive substance, the matrix resin comprising a one-component epoxy-modified thermosetting resin and a thermoplastic resin. This is achieved by an anisotropically conductive adhesive composition characterized by comprising:

The adhesive matrix resin used in the present invention is
It is preferable that the material itself has excellent electrical insulation properties. In addition, it has enough fluidity to flow through the gap between two opposing parts to be bonded during the connection process, and it can be hardened by heat, light, electron beams, etc., or solidified by cooling. It is preferable that the material has the property of forming an adhesive layer. Furthermore, matrix resin has repairability, which means that even if opposing circuits become misaligned due to malfunction during connection, they can be removed and the circuits can be reused. Those that retain their properties are preferably used.

A matrix resin suitable for this purpose can be obtained by blending a one-component epoxy-modified thermosetting resin that is effective in firmly adhering opposing circuits with a thermoplastic resin that is effective in pairing properties. can.

The one-component epoxy-modified thermosetting resin described below is more stable at room temperature than the commonly used two-component epoxy curable resin, which uses a curing catalyst such as an amine and an epoxy resin. The reaction occurs <<
, which reacts and hardens by applying a predetermined temperature, and has excellent storage stability at room temperature.

Therefore, during production, the adhesive of the present invention can be made to have stable performance with little change in the viscosity of the wave-shaped epoxy-modified thermosetting resin, as well as conductivity during heat storage in the connected state. It has the advantage of being excellent in maintaining sex.

As these wave-shaped epoxy-modified thermosetting resins, those obtained by modifying epoxy resins with one or more types of alkyd resins, phenol resins, melamine resins, guanamine resins, urea resins, non-drying oil fatty acids, etc. are preferably used. It will be done. Note that the modified product with the epoxy resin is not limited to those listed here.

Thermoplastic resins used in combination with single-wave epoxy-modified thermosetting resins include acrylic resins, polyurethane resins, polyester resins, butyral resins, copolymers of ethylene and vinyl acetate, and copolymers of styrene and butadiene. One type or a mixture of two or more of these can be used. Note that the thermoplastic resin is not limited to those listed here, but urethane resin is particularly preferably used in terms of continuity reliability.

The urethane resin is obtained by reacting one or more of hexamethylene diisocyanate, tolylene diisocyanate, isophorone diisocyanate, and diphenylmethane diisocyanate with at least one of polyester polyol, polyether polyol, and castor oil. Although resins such as
Can be used. do not have. As the urethane resin, one having a molecular weight of 50,000 or more and a thermosetting temperature of 110 to 160°C, more preferably 110 to 140°C is preferably used.

Even if the molecular weight is less than 50,000, the thermal softening temperature exceeds 160°C, which is not preferred because it is difficult to flow at normal connection temperatures.

The amount of matrix resin blended in the adhesive composition is not particularly limited, but from the viewpoint of adhesiveness and insulation reliability, it is 99%
The range is preferably 65% by weight, more preferably 95% by weight.
It is 75% by weight.

The amount of thermoplastic resin blended in the adhesive matrix resin is not particularly limited, but from the viewpoint of repairability and continuity reliability during heat storage, it is preferably in the range of 20 to 80% by weight, more preferably 40 to 70% by weight. Weight%. The urethane resin can be selected as appropriate within the range that satisfies the above-mentioned blending conditions of the thermoplastic resin, but from the viewpoint of significant improvement in continuity reliability and repairability during heat storage, it is recommended that the urethane resin contains 40% by weight or more in the thermoplastic resin. It is better to mix it.

The conductive substance used in the present invention is not particularly limited, but metal powder itself having excellent conductivity, organic polymer particles whose surface is coated with metal, or mixtures thereof are preferably used. .

As the metal powder, one or a mixture of two or more of platinum, gold, silver, nickel, cobalt, copper, tin, aluminum, palladium, etc. is preferably used. In addition to a single composition, alloys such as solder, and nickel, copper, etc. plated with gold or the like are also preferably used. Of course, the metal powder is not limited to those listed here.

The diameter of the metal powder is not particularly limited, but from the viewpoint of continuity reliability and insulation, it is preferably in the range of 0.3 μm or more and less than 40 μm, more preferably in the range of 0.5 to 16 μm.

The shape of the metal powder may be either flaky or spherical, but it is more preferably spherical and of uniform particle size.

Polymer components of the metal-coated organic polymer particles include thermosetting resins such as epoxy and phenol, thermoplastic resins such as polyamide, polyimide, polyamideimide, polyester and polystyrene, polybutadiene,
Although the rubber can be selected from a wide variety of rubbers such as nitrile rubber and butadiene styrene rubber, particles made of epoxy resin are preferably used because they provide excellent plating particles.

Metals coated include gold, platinum, silver, tin, nickel, copper,
Zinc, aluminum, palladium, cobalt, and the like are preferably used. Not only single composition coatings but also alloy coatings such as solder are used. It is preferable to use a composite coating with copper in the bottom layer, nickel next, and gold in the top layer from the viewpoint of the balance between cost and performance.

Composite coatings with solder as the top layer are also used.

The amount of metal coated is preferably such that its volume does not exceed the volume of the organic polymer particles, and more preferably 30% by weight or less.

The diameter of the organic polymer particles whose surfaces are coated with metal is not particularly limited, but from the viewpoint of continuity reliability and insulation reliability due to surface connection, it is preferably 1 μm or more and less than 40 μm, more preferably in the range of 1 to 20 μm. It is more preferable to use particles that are nearly spherical and have a uniform particle size.

From the viewpoint of conductivity reliability and ease of handling, it is best to use a mixture of metal powder and metal-coated organic polymer particles, and in that case, the diameter ratio of the metal powder and metal-coated organic polymer particles is Although not particularly limited, from the viewpoint of not causing peeling or damage of the metal coated on the surface and causing appropriate deformation of the metal-coated organic polymer particles to ensure continuity reliability, it is preferable to coat the metal with a metal. organic polymer particle size 1
It is preferable that the metal powder diameter is in the range of 0.1 to 1.0 with respect to 0°. More preferably it is 0.3 to 0.8.

The amount of conductive material, that is, the amount of metal powder and/or metal-coated organic polymer particles, is not particularly limited, but it is important that the individual particles are almost independent and the entire adhesive layer is insulated in the lateral direction. From the viewpoint of ensuring insulation reliability between adjacent circuits of the connection body and continuity reliability, the adhesive composition preferably contains 1 to 35% by weight, more preferably 5% by weight. ~25% by weight. In addition, when using a mixture of the two, the preferred ratio is that the metal powder is 0.
．． From the viewpoint of continuity reliability, it is preferable to use 5 to 30% by weight of the metal-coated organic polymer particles and 99.5 to 30% by weight of the metal-coated organic polymer particles.

The anisotropically conductive adhesive composition of the present invention is usually applied in the form of a paste containing a conductive substance dispersed therein to at least the terminal portion or the entire surface of one component, and is dried as necessary to remove the solvent. After removal, the two parts are hot-pressed facing each other to form an electrical connection, or an anisotropically conductive adhesive composition is sandwiched between the two parts as an adhesive film and hot-pressed to form an electrical connection. You can also.

The paste is usually diluted with a diluent, and examples of the diluent include ketones, alcohols, cellosolves, dioxane, aromatic hydrocarbons, and ethyl acetate. When used as an adhesive film, methods such as forming the paste and removing the solvent to form a film, or directly forming a film by melt forming using a diluent, etc., are used, but are not limited thereto.

When the anisotropically conductive adhesive composition is used as a film, the thickness of the film is preferably in the range of 1 to 100μ, and 1 to 100μ.
A range of 50μ is more preferred.

[Examples] The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto.

Example 1, Comparative Example 1 A paste was prepared by mixing and dispersing the following composition.

- Corrugated epoxy-modified thermosetting resin (manufactured by Toshi ■, TE1710) 8.8% by weight Acrylic resin (manufactured by Toshi ■, LU-651) 1.8% by weight Urethane resin (manufactured by Sanyo Kasei ■, "Sunbren") LO3
-A) 7.0% by weight nickel-plated epoxy particles (manufactured by Toshi ■, 6μ diameter) 2.6% by weight metal powder (
Manufactured by Inco, Ni287, 3μ) 0.9% by weight Methyl ethyl ketone 78.9% by weight Polyimide film clad with 18μ copper foil is used as raw material.
Two test circuits having terminals with a pitch of 0 wires/mm were made, and the above paste was screen printed on the terminal portion of one of the test circuits. The average coating thickness after drying was 20 microns. Then, place these terminals facing each other and heat them to 150℃.
, after hot pressing at 30kg/Cm2 for 20 seconds,
It was immediately cooled (Example 1).

The obtained connection body has a conduction resistance value of 1.0Ω or less,
The insulation resistance value between adjacent terminals was 1010Ω or more. Even after this connected body was stored at 80° C. for 1.0 OOhr, the conductivity and insulation properties described above were maintained.

On the other hand, a connection body was produced in the same manner as in Example 1 above, except that the -wave type epoxy-modified thermosetting resin was not used (Comparative Example 1).

Table 1 shows a comparison of the conduction resistance values when the connected body obtained in Example 1 and the connected body obtained in Comparative Example 1 were stored at 80° C. for 1,000 hours.

The conventional connection body according to Comparative Example 1 had poor conduction reliability and lacked reliability as an ultra-high-density electrical connection body, whereas the connection body using the anisotropic conductive adhesive of the present invention had poor conductivity reliability. This case has excellent continuity reliability, making it possible to make ultra-high-density electrical connections.

Table 1 Continuity resistance value (Ω) Adhesive Initial 80℃80℃ 80℃250hr
5[10br 1000hrExample 1 0.42 0
．． 56 0.74 0.95 Example 2 0.56
0.75 0.83 0.90 Comparative example 1 1.02
3.65 Continuity Poor continuity Defect Note Measurement was performed using a digital micrometer manufactured by Keithley.

Example 2 The following composition was charged into a non-solvent Brabender equipment, melted and mixed, and then formed into a film with a thickness of approximately 20 μm using a flat plate hot press.
obtained the film.

- Corrugated epoxy-modified thermosetting resin (manufactured by Toshi ■, TE1710) 52% by weight Maleic acid-modified ethylene/vinyl acetate copolymer (manufactured by Mitsui DuPont Chemical, IIPR-103) 35% by weight Conductive particles (Novamet) This film was sandwiched between the terminals of the test circuit used in Example 1, which had terminals with a pitch of 10 terminals/mm, and heated at 160°C, 1C13% by weight.
After hot pressing at Q/cm2 for about 20 seconds, it was immediately left to cool. The performance of the thus obtained connection body was as good as in Example 1, and the present invention enabled ultra-high density electrical connection.

Table 1 shows the connected bodies obtained in Example 2 at 80°C. 0
The conduction resistance value when stored for 00 hours is shown.

[Effects of the Invention] According to the present invention, an ultra-high density electrical connection body that cannot be obtained with conventional anisotropically conductive adhesives can be obtained. Furthermore, in electrical connection during heat storage, an electrical connection body with excellent continuity reliability can be obtained using conventional products. For this reason, it is possible to directly mount delicate components such as IC chips on a circuit board, which brings about remarkable practical effects.

Written amendment 1, Indication of the case 1999 Patent Application No. 247508 2, Name of the invention Anisotropic conductive adhesive composition 3, Person making the amendment Relationship to the case Patent applicant address 2, Nihonbashi Muromachi, Chuo-ku, Tokyo Chome 2-1 name (
315) Toshi Co., Ltd. 5, No number of inventions increased by amendment (1) Amended to "thermal softening temperature" on page 8, line 15 of the specification.

(2) Page 13, line 1 of the specification Correct it to "70 weight."

"Thermosetting temperature" "30 weight"

Claims (5)

[Claims] (1) An anisotropic conductive adhesive comprising a composition comprising an adhesive matrix resin and a conductive substance, the matrix resin comprising a one-component epoxy-modified thermosetting resin and a thermoplastic resin. Composition. (2) The anisotropic conductive adhesive composition according to claim (1), wherein the thermoplastic resin contains a urethane resin. (3) The anisotropically conductive adhesive composition according to claim (2), wherein the urethane resin has a heat softening temperature of 110 to 160°C and a molecular weight of 50,000 or more. (4) The conductive substance is composed of a metal powder and an organic polymer particle whose surface is coated with a metal, and the particle size ratio is 1.0 for the organic polymer particle coated with a metal to 0.0 for the metal powder. Claim (1) characterized in that it is 3 to 1.0.
The anisotropically conductive adhesive composition described above. (5) The anisotropically conductive adhesive composition according to claim (4), wherein the organic polymer particles are made of an epoxy polymer.