JP4770139B2 - Conductive particles and anisotropic conductive material composition - Google Patents

Description

  The present invention relates to an anisotropic conductive material used for connection between an electrical component and a circuit board or between circuit boards. More specifically, the present invention relates to improvement of conductive particles for imparting good anisotropy to the conductivity of an anisotropic conductive material.

  In recent years, in the field of mounting electronic information materials, integration of mounting components has been rapidly progressing, and it is desired to electrically connect connection terminals (electrodes) with a fine pitch. As such an electrode connection method, a soldering method, a wire bonding method, or the like is generally known.

  However, the soldering method has a drawback that it is difficult to connect the connection terminals with a fine pitch. In addition, soldering wettability is required for the connection terminals used, and high heat resistance is required for the insulating substrate in order to make a high temperature connection.

  In addition, the wire bonding method performs connection using a gold wire, but this method has a limit in connecting a miniaturized electrode.

  In order to solve these problems, in recent years, an electric infrastructure circuit in which reliability is improved by interposing conductive particles between electrodes is known. Until now, metal particles such as gold, silver, and nickel have been used for such conductive particles, but these have non-uniform shapes or have a higher specific gravity than the binder resin in the conductive paste. Since it is difficult to settle or evenly disperse, there is a drawback that connection reliability is lacking.

  For this reason, conductive fine particles (for example, see Patent Document 1 or Patent Document 2) in which a metal plating layer is provided on silica fine particles or resin fine particles are disclosed. Moreover, the electroconductive powder which coat | covered fine metal microparticles | fine-particles with the organic or inorganic core material as electroconductive fine particles is also disclosed (for example, refer patent document 3).

  However, these conductive fine particles have a small contact area because the core material is too hard to damage or compressively deform, and it is difficult to reduce the contact resistance, or they are buried in the electrode during hot pressing. There was a case.

In addition, these conductive fine particles have a problem that the metal thin film is hard and cracks are likely to occur, and the connection reliability is also poor.
JP 59-28185 A Japanese Examined Patent Publication No. 7-95165 Japanese Patent Publication No. 6-96771

  In recent years, with the trend toward smaller and thinner electronic devices, the fine pitch of multi-contact electrodes has been increasing along with the trend toward higher density of various components. The appearance of highly reliable conductive particles is also desired for such connections.

  Therefore, as a result of intensive studies by the present inventors, in order to solve the above-mentioned problems, highly reliable conductive particles, anisotropic conductive adhesives, anisotropic conductive properties for the multi-contact electrodes of the fine pitch currently required. We have succeeded in providing a film and a highly reliable electric circuit board. That is, the present invention is as follows.

(1) A core particle and a conductive fiber layer on the core particle surface, and the core particle is a polyamide resin, a phenol resin, an amino resin, an ethylene-vinyl acetate resin, a polyester resin, a urea resin, a melamine resin, an alkyd resin, Conductive particles that are particles mainly composed of at least one resin selected from polyimide resin, urethane resin, and epoxy resin .

  (2) The conductive particle according to (1), wherein the conductive fiber is composed only of carbon.

( 3 ) The conductive particle according to (1) or (2), which has an adhesive layer between the core particle and the conductive fiber layer.

( 4 ) The core particles are mainly composed of at least one thermoplastic resin selected from polyamide resin, amino resin, ethylene-vinyl acetate resin, polyester resin, urea resin, melamine resin, alkyd resin, polyimide resin, and urethane resin. The electroconductive particle in any one of (1)-( 3 ) which is a particle | grain to do.

( 5 ) The conductive particles according to ( 4 ) , wherein the thermoplastic resin is a polyamide resin.

( 6 ) The electroconductive particle in any one of (1)-(3) whose core particle is a particle | grains which have a grill amide and an epoxy resin as a main component.

( 7 ) An anisotropic conductive material composition containing an adhesive binder and the conductive particles according to any one of (1) to ( 6 ).

( 8 ) An anisotropic conductive adhesive containing an insulating thermosetting resin and the conductive particles according to any one of (1) to ( 6 ).

( 9 ) An insulating thermosetting resin film containing the insulating thermosetting resin and the conductive particles according to any one of (1) to ( 6 ).

( 10 ) The insulating thermosetting resin film according to ( 9 ), having a fine particle layer formed from the conductive particles according to any one of (1) to (6) on the film surface.

  By using the present invention, it is possible to provide a reliable and stable connection method for a fine-pitch multi-contact electrode, which has been a problem until now, and is required to be miniaturized and miniaturized. Great improvements are made to the circuit board.

Hereinafter, the conductive particles according to the present invention, the anisotropic conductive adhesive using the particles, the film, the anisotropic conductive adhesive using the particles, the anisotropic conductive film, and the electric circuit board will be specifically described. To do.

[Configuration of conductive particles]
The electroconductive particle of this invention is comprised with the following. The block diagram is shown in FIG.
1. 1. core particle 2. Adhesive layer Conductive layer

  Hereinafter, each will be described in detail.

1. Core particles As the core particles used in the present invention, inorganic oxide particles, organic-inorganic composite particles, organic polymer particles, and the like can be used, but it is essential to use polymer particles . The organic polymer particles, polyamide resin, phenol resin, amino resin, et styrene - vinyl acetate resins, polyester resins, urea resins, melamine resins, alkyd resins, polyimide resins, urethane resins, thermosetting resins such as epoxy resins, heat Examples thereof include curable resins and organic-inorganic hybrid copolymers. Further, two or more kinds of the materials mentioned here may be used in combination.

  The average particle size of the core layer at this time is preferably 1 mm or less, more preferably 100 μm or less, and still more preferably 80 μm or less. Within this range, finer connection is facilitated.

2. Adhesive Layer The adhesive layer used in the present invention may or may not be present, but may be present when the core layer and the conductive layer are easily peeled off. The main components of the adhesive layer in this case are vinyl acetate resin, acrylic resin, vinyl acetate-acrylic resin, vinyl acetate-vinyl chloride resin, ethylene-vinyl acetate resin, ethylene-vinyl acetate resin, ethylene-acrylic resin, polyamide. , Polyvinyl acetal, polyvinyl alcohol, polyester, polyurethane, urea resin, melamine resin, phenol resin, resorcinol resin, epoxy resin, polyimide, natural rubber, chloroprene rubber, nitrile rubber, urethane rubber, SBR, recycled rubber, butyl rubber, aqueous vinyl urethane , Α-olefin, cyanoacrylate, modified acrylic resin, epoxy resin, epoxy-phenol, butyral-phenol, nitrile-phenol, etc. are preferred, among which vinyl acetate resin, acrylic resin, vinyl acetate Lil resin, vinyl acetate - vinyl chloride resins, ethylene - vinyl acetate resins, ethylene - vinyl acetate resins, ethylene - acrylic resin, an epoxy resin is preferred.

  The thickness of the adhesive layer at this time is 10 μm or less, preferably 5 μm or less, more preferably 1 μm or less.

  Moreover, it can also serve as an adhesive bond layer and a core layer. In this case, the core component and the adhesive component are mixed, and then particles are formed. In this case, the core layer and the adhesive component are preferably the materials described in the section of the core layer and the adhesive layer. The average particle diameter of the “core-adhesive layer” at this time is preferably 1 mm or less, more preferably 100 μm or less, and still more preferably 80 μm or less. Within this range, finer connection is facilitated.

3. Conductive layer The material of the conductive layer used in the present invention is preferably a microconductive fiber. More preferably, the micro conductive fibers are made of carbon, and more preferably hollow carbon fibers.

  The outer diameter of the minute conductive fiber is preferably 1 μm or less, and more preferably 100 μm or less.

  Although a hollow carbon fiber has been exemplified as a preferable form of the minute conductive fiber, the hollow carbon fiber may be one in which a graphite layer is formed. In this case, the total number of graphite layers is preferably 1 to 100 layers, more preferably 1 to 10 layers, still more preferably 1 to 5 layers, and particularly preferably 1 Two layers (single layer) to two layers.

  The hollow carbon fiber preferably has an aspect ratio expressed by a ratio of the total length of the layer to the outer diameter of the layer of 1 to 1,000,000, more preferably 1 to 100,000, and still more preferably 1 to 10,000.

  As this hollow carbon fiber, one containing a metal or a metal compound can be used as necessary. The content of the metal or metal compound is not particularly limited, but is practically preferably 1 wt% or less with respect to the total weight of the hollow carbon fiber containing the metal or metal compound.

[Method for producing conductive particles]
The conductive particles can be made by the following method.

  If an adhesive layer is present, the particulate core layer is first immersed in a uniform solution of the adhesive layer component. At this time, any solvent may be used as long as it does not completely dissolve the core layer, and a solvent that does not completely dissolve the core layer can also be used.

  Next, the particles on which the adhesive layer has been formed are separated from the solution. The separation method at this time is not particularly limited, and examples thereof include filtration and distillation.

  Next, the particles coated with the adhesive layer are put into a suspension in which a separately prepared conductive layer component is dispersed and mixed.

  Subsequently, the particles on which the conductive layer is formed are separated from the solution by a filtration method or the like, and the conductive particles are completed through a drying step in some cases.

  When the core component has adhesive ability, it is not always necessary to form an adhesive layer, and it is directly put into a suspension in which a separately prepared conductive layer component is dispersed, mixed, and separated by a filtration method or the like. To complete the conductive particles.

  Solvents used at this time are pentane, hexane, heptane, octane, nonane, n-decane, n-dodecane, n-tridecane, cyclohexane, cyclopentane, benzene, toluene, xylene and other hydrocarbon solvents, ethyl acetate, acetic acid. Ester solvents such as methyl, halogen solvents such as chloroform, bromoform, methylene chloride, 1,2-dichloroethane, 1,1,1-trichloroethane, chlorobenzene, 2,6-dichlorotoluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, Ketone solvents such as methyl butyl ketone, alcohol solvents such as methanol, ethanol, isopropanol, and n-propanol, polar solvents such as dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, and trimethyl phosphoric acid , Diethyl ether, tetrahydrofuran, diisopropyl ether, dioxane, diglyme, dimethoxyethane and the like.

  The conductive particles thus obtained have a conductivity equal to or higher than that of conventionally known conductive fine particles coated with metal particles or metal layers by using hollow carbon fibers.

  In addition, since hollow carbon fibers are used, the effect of entanglement between the fibers prevents stable cracking and peeling of the layers found in metal-coated conductive fine particles that have been known in the past. It becomes the material to give.

  In addition, hollow carbon fiber is a material that is extremely strong against deformation caused by stress, and thus is suitable as a material in the field to be used after being crimped.

[Utilization of conductive particles]
The conductive particles thus obtained can be used as an anisotropic conductive adhesive by being dispersed in an insulating thermosetting resin.

The insulating thermosetting resin at this time is an epoxy resin, a polyurethane resin, a phenol resin, a melamine resin, a polyester resin, or an oxazoline resin.
An epoxy resin and an oxazoline resin are preferable, and an epoxy resin is particularly preferable.

  Further, the conductive particles can be used as an anisotropic conductive film after being dispersed in an insulating resin and formed into a film.

  Insulating resin at this time includes polyamide resin, phenol resin, amino resin, acrylic resin, ethylene-vinyl acetate resin, polyester resin, urea resin, melamine resin, alkyd resin, polyimide resin, urethane resin, epoxy resin, etc. A plastic resin and a thermosetting resin are preferable, and a thermosetting resin such as a polyurethane resin, a phenol resin, a melamine resin, a polyester resin, and an epoxy resin is preferable, and an epoxy resin is particularly preferable.

  It is preferable to arrange the conductive particles so as to be exposed on the front and back of the film during film production. By doing in this way, it becomes possible to give conduction in the thickness direction of a film.

  The thickness of the insulating film at this time is preferably such that the lower limit is 10% and the upper limit is 95% with respect to the average particle diameter of the conductive particles. If it is less than 10%, it becomes difficult to support the conductive particles on the film portion, and if it exceeds 95%, the conductive particles do not reach the electrode at the time of continuity inspection, causing a connection failure. A preferable lower limit is 20% and an upper limit is 80%, and a more preferable lower limit is 30% and an upper limit is 70%.

  As described above, by using the conductive fine particles obtained by the present invention, or the anisotropic conductive adhesive and anisotropic conductive film using the conductive particles, it is conventionally possible to produce fine pitch multi-contact electrodes. There can be no reliable connection method.

  The present invention will be specifically described with reference to the following examples, but the present examples are not intended to limit the present invention.

Example 1
Preparation of core particles 90 parts by weight of transparent polyamide (trade name “Grillamide-TR55”, manufactured by Mzavelke), 7.5 parts by weight of epoxy resin (trade name “Epicoat 828”, manufactured by Yuka Shell Co., Ltd.) and curing agent (product) 2.5 parts by weight of “Tomide” # 296, manufactured by Fuji Chemical Industry Co., Ltd.) was added to a mixed solvent of 300 parts by weight of chloroform and 100 parts by weight of methanol to obtain a uniform solution. Next, the solution was atomized using a spray gun for coating, stirred well, and sprayed toward the liquid surface of 3000 parts by weight of n-hexane to precipitate a solute. The precipitated solid was separated by filtration, washed well with n-hexane, and then vacuum dried at 100 ° C. for 24 hours to obtain core particles.

Example 2
Preparation of conductive fine particles In 100 ml of ethanol, 5 g of hollow carbon fiber (manufactured by Toray Industries, Inc.) and 23 g of the core layer obtained in Example 1 were added and stirred for 1 hour. The resulting suspension was concentrated under reduced pressure. Subsequently, by heating to 200 ° C. under an argon atmosphere and curing, 25 g of conductive particles were obtained. When the cross section of the conductive particles was observed with an electron microscope (2000 magnification of FIG. 2), the conductive layer was coated with a thickness of 0.3 μm.

Example 3 Preparation of Anisotropic Conductive Film A mixed paste consisting of 30 parts by weight of conductive particles obtained in Example 2 and 100 parts by weight of polyarylate was heated and melted at 330 ° C., and a biaxial stretching machine was used. An anisotropic conductive film having a thickness of 20 μm was prepared.

Example 4 Evaluation of anisotropic conductive film
An anisotropic conductive film produced in Example 3 was attached to an ITO glass substrate by thermocompression bonding, and the separator was peeled off. Then, a bare chip with gold bumps was thermocompression bonded to form a circuit. When the connection resistance between the electrodes at this time and the connection resistance between adjacent electrodes were measured, the connection resistance was 1.2Ω, and the insulation resistance was 5E + 11Ω.

Anisotropic conductive adhesive and anisotropic conductive film using the conductive particles and conductive particles obtained in the present invention are required for electronic circuits, etc., and can be stably connected to a fine pitch multi-contact electrode. A method can be provided, which is useful for use in electrical circuit board applications where miniaturization and miniaturization are required.

It is an outline of composition of conductive particles. 2 is a photomicrograph of a cross section of conductive particles obtained in Example 2. FIG.

Explanation of symbols

1: Core layer 2: Adhesive layer 3: Conductive layer

Claims (10)

Core particles and a conductive fiber layer on the core particle surface, the core particles are polyamide resin, phenol resin, amino resin, ethylene-vinyl acetate resin, polyester resin, urea resin, melamine resin, alkyd resin, polyimide resin, Conductive particles , characterized in that the particles are mainly composed of at least one resin selected from urethane resins and epoxy resins . The electroconductive particle of Claim 1 in which the electroconductive fiber of an electroconductive fiber layer is comprised only with carbon. The electroconductive particle of Claim 1 or 2 which has an adhesive bond layer between a core particle and an electroconductive fiber layer. The core particle is a particle mainly composed of at least one thermoplastic resin selected from polyamide resin, amino resin, ethylene-vinyl acetate resin, polyester resin, urea resin, melamine resin, alkyd resin, polyimide resin, and urethane resin. conductive particles according to any of one claims 1-3. The conductive particles according to claim 4 , wherein the thermoplastic resin is a polyamide resin . The conductive particles according to any one of claims 1 to 3 , wherein the core particles are particles mainly composed of grill amide and an epoxy resin. Adhesive binder and claims 1 to anisotropic conductive material composition containing the conductive particles according to any one of 6. Anisotropic conductive adhesive containing conductive particles according to any one of the insulating thermosetting resins and claims 1-6. Insulating thermosetting resin film containing a conductive particle according to any one of the insulative thermosetting resin and claims 1-6. The insulating thermosetting resin film according to claim 9, wherein the film surface has a fine particle layer formed from the conductive particles according to claim 1.

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