KR100566102B1 - Conductive particles having insulating layer on the surface, method for preparing the same and anisotropic electroconductive material containing the same - Google Patents

Abstract

The present invention relates to an insulating conductive particle in which an inorganic magnetic particle treated with a coupling agent is bonded to the surface of the conductive mother particle to form an insulating layer, wherein the surface of the conductive mother particle is due to the affinity between the functional group and the metal on the surface of the inorganic magnetic particle. An inorganic magnetic particle insulating layer is formed on the magnetic particles, and the magnetic particles have more adhesion than the physically attached insulating coating particles, and they have less adhesion than covalent bonds, and maintain insulation and heat and pressure in the absence of heat and pressure. When given, the insulating layer is broken, and the balance between insulation and conductivity is appropriately achieved. In addition, the physical properties are stable and can be produced economically.

 Insulating conductive particles, inorganic magnetic particles, conductive mother particles, coupling agent, anisotropic conductive film

Description

Insulating conductive particle, manufacturing method thereof, and anisotropic conductive material comprising same {CONDUCTIVE PARTICLES HAVING INSULATING LAYER ON THE SURFACE, METHOD FOR PREPARING THE SAME AND ANISOTROPIC ELECTROCONDUCTIVE MATERIAL CONTAINING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to insulating conductive particles that can be used for anisotropic conductive films that can be used as a wide connection material, such as between modules or between IC chips and circuits, when mounting various display devices, including liquid crystal displays (LCDs), and semiconductor devices. The present invention relates to a new concept of insulating conductive particles exhibiting high insulation even at narrow pitch intervals and anisotropic conductive materials using the same.

Conventionally, a combination of a lead line of a semiconductor chip or a liquid crystal display device and a connection portion of a driving circuit thereof is used to form a bump or use a carrier tape. However, this method is inadequate to form more detailed connecting portions. Thus, anisotropic conductive films capable of improving this have become widely used as materials for electrically connecting electronic components such as semiconductor devices and circuit boards. The use of anisotropic conductive films is becoming more diversified in accordance with the trend toward thinner and shorter electronic components. In recent years, computer monitors as well as televisions have become thinner and thinner. A connection method using an anisotropic conductive film (ACF) is widely used. In addition, in particular, the use of ACF in LCD mounting technology is intensifying, and a method of directly mounting a semiconductor circuit on a film or a glass substrate by a COF (Chip On Film) or COG (Chip on Glass) method is also rapidly developing. Examples of patents related to such an anisotropic conductive film include Japanese Patent Laid-Open Nos. 5-21094, 5-5-020020, 7-302666, 7-302667, 7-211374, 8-311420, and 9-199206 and 9-115335.

The anisotropic conductive film is basically composed of conductive particles and insulating resin. Carbon particles were initially used as particles that exhibit electrical conductivity, and then solder balls were used. Currently, conductive particles in which nickel and gold are plated on nickel particles or plastic particles are mainly used. have. Nickel has a low price and relatively good electrical conductivity, but when exposed to high temperature and humidity conditions, it may cause problems such as corrosion or oxidation on the surface.

Currently, when ACF is used in a fine pattern of 100 μm or less in a COG application or the like, when general conductive particles are used, there is a problem that insulation between adjacent circuits is easily destroyed due to aggregation of conductive particles. As a method for solving this problem, various solutions have been proposed, which are mainly methods of preventing direct contact between conductive particles by forming an electrical insulation layer on the surface of the conductive particles. Japanese Patent Publication No. 2836337 or 3050384 and the like are patents for a new technology for forming an electrical insulation layer on the surface of conductive particles.

Up to now, three methods have been proposed as follows to form an electrical insulation layer on the surface of the conductive particles.

(1) Metal surface oxidation method: When the surface of electroconductive particle is Ni or Al, when it heats in presence of oxygen, the oxide film of Ni or Al will be formed on the surface of electroconductive particle, and this is a method which acts as an electrical insulation layer. This method has a problem that the type of applicable metal is limited and the thickness of the electrical insulation layer is not sufficient.

(2) Solution method: A method in which an electrically insulating resin is dissolved in a solvent, conductive particles are dispersed in this solution, and then dried to form an electrically insulating resin layer on the surface of the conductive particles. Although this method is easy and simple, it is only possible to dissolve the resin in a solvent, so that the resin is limited to the dissolvable resin, and it is difficult to prepare a uniform and uniform thickness of the electrical insulation layer.

(3) Dry method: It is a method of forming an electrically insulating resin layer on the surface of electroconductive particle using the method of making an electrically insulating resin into powder, mixing with electroconductive particle, and making it collide at high speed. In this case, a surface modification device such as a Mechano-fusion system may be used. However, this method has a limited amount of product that can be produced at one time, resulting in poor productivity, and since the electrical insulation layer is hardly in close contact with the conductive particles, the insulation layer is easily peeled off and the thickness of the insulation layer is not uniform. There is.

The present invention is to solve the problems of the prior art as described above, it is an object of the present invention to provide an insulating conductive particles of a new concept in which an insulating layer is formed by bonding the insulating magnetic particles on the surface of the conductive parent particles.

That is, one aspect of the present invention relates to insulating conductive particles in which inorganic magnetic particles treated with a coupling agent are bonded to the surface of the conductive mother particles to form an insulating layer.

Another aspect of the invention provides a method for treating an inorganic particle comprising treating the surface of an inorganic magnetic particle with a coupling agent; And

It relates to a method for producing insulating conductive particles comprising the step of bonding the treated inorganic magnetic particles to the surface of the conductive parent particles to form an insulating layer.

Another aspect of the invention relates to an anisotropic conductive material comprising the insulating conductive particles.

The present invention will be described in more detail below.

In the present invention, after the inorganic particles are reacted with or adsorbed with a coupling agent containing a functional group having a strong affinity with the metal to prepare a metal affinity magnetic particles, and then contact with the conductive mother particles, the conductive mother particles by the strong metal affinity of the functional group The phenomenon in which the electrical insulation layer which consists of inorganic magnetic particles is formed in the surface was used.

As the conductive mother particles used in the present invention, any of the generally known metal particles themselves or metal plating particles in which metals are plated on organic particles or inorganic particles may be used. That is, as long as the surface is a metal, the inside may be any of metal particles, organic particles, and inorganic particles. Examples of the metal include nickel, gold, silver, copper, palladium, ruthenium, rhodium, iridium, cobalt, aluminum, titanium, vanadium, chromium, manganese, zirconium, molybdenum, indium, antimony, tungsten, and the like. And styrene resin particles, silicone particles, polyester particles, polyurethane particles, polyamide particles, phenol particles, terpene particles, melamine particles, guanamine particles or composite resin particles thereof. . Examples of the inorganic particles include alumina, titanium dioxide, calcium titanate, magnesium titanate, zinc oxide, clay, calcium carbonate, silica, tungsten carbide, carbon black and the like. When the conductive particles are formed by metal plating on the surface of such organic particles or inorganic particles, it is possible to plate metals such as gold, silver, nickel, palladium, and copper alone or in the form of alloys. Plating may be performed in layers or multilayers. As a volume average particle diameter of such a mother particle, in order to use it as a material of an anisotropic conductive film, the range of 1-50 micrometers is preferable. When the average particle diameter of the mother particle is less than 1 µm, conduction between circuits is difficult to obtain when used as an anisotropic conductive material. On the other hand, when the average particle diameter is more than 50 µm, it is likely to cause short circuits between adjacent circuits.

Inorganic magnetic particles used to form an insulating layer on the surface of the mother particle in the present invention may be used alumina, titanium dioxide, calcium titanate, magnesium titanate, zinc oxide, clay, calcium carbonate, silica, tungsten carbide, and the like. Preferably, hydrophilic fumed silica (OH group) is used. However, if the size is larger than a certain ratio compared to the parent particles, it is difficult to adsorb on the surface of the parent particles, so it is important to select the appropriate size of the own particles. That is, the volume average particle diameter of the magnetic particles is 1/3 or less, preferably 1/5 or less, and more preferably 1/10 or less of the average particle diameter of the mother particles. When the average particle diameter of the magnetic particles is larger than 1/3 of the mother particles, the adhesion state is not stabilized, and the aggregates of the mother particles and the magnetic particles are formed.

As a coupling agent compound which has a functional group with strong affinity with the metal which can be used by this invention, the silane couple which has functional groups, such as thiol (-RSH), thioether (-RS-R '), and disulfide (-RSS-R'), etc. Ring agent is representative. Examples include commercially readily obtainable 3-mermethopropyl trimethoxy silane, 3-merceto propyl triethoxy silane, 4-merceto butyl methoxy silane, 4-merceto butyl ethoxy silane, and the like. In addition to such materials, any of the functional groups having 1 to 3 and capable of coupling can be used without limitation.

Referring to the method of treating the inorganic magnetic particles with the coupling agent in the present invention in detail. First, the inorganic magnetic particles are uniformly dispersed on the organic solvent, then the coupling agent is mixed and nitric acid is introduced as a catalyst. In this case, ethyl alcohol or methyl alcohol may be used as the organic solvent, and the coupling agent may be used in an amount of 1 to 5 parts by weight based on 100 parts by weight of the inorganic magnetic particles. Nitric acid used as a catalyst is a nitric acid solution of 62% by weight of purity, and is used in an amount of 1 to 10 parts by weight based on 100 parts by weight of inorganic particles. However, the method described above is not limited, and various methods predicted from the prior art can be used.

Meanwhile, the reaction between the coupling agent-treated inorganic magnetic particles and the conductive mother particles is performed by mixing in the presence of a dispersion medium. Examples of the dispersion medium include alcohols such as water, methyl alcohol, ethyl alcohol, isopropyl alcohol and butyl alcohol, hydrocarbons such as hexane, pentane and cyclohexane, esters such as ethyl acetate, and the like. It is also possible to use 1 type or 2 or more types together.

In the mixing process, the concentration of particles in the dispersion medium varies depending on the type and particle size of the magnetic particles and the mother particles, but is preferably in the range of 5 to 25% by weight. If the particle concentration in the mixing treatment is less than 5% by weight, the contact probability between the mother particles and the mother particles is lowered, so that the treatment requires a long time and is economically undesirable.

In addition, it is preferable that the mixing ratio of an inorganic magnetic particle and an electroconductive mother particle shall be 25: 1-15: 1. If the mixing ratio is out of the above range and the inorganic magnetic particles are excessively larger than the conductive mother particles, aggregation may occur between the inorganic magnetic particles and the conduction may be deteriorated. There is a problem that the gold plating layer is not sufficiently insulated and energized.

The reaction conditions may vary depending on the type, particle concentration, and specific gravity of the parent and child particles, but the reaction temperature is in the range of 20 to 200 ° C, preferably 30 to 150 ° C, more preferably 40 to 100 ° C. In addition, as for the stirring speed, the speed which distribute | disperses a mother particle and a magnetic particle uniformly is suitable.

Insulating conductive particles prepared by the above method have a larger adhesion than the insulating coated particles that are simply physically attached, and have less adhesion than covalent bonds, and maintain insulation and heat and pressure in the absence of heat and pressure. In this case, the insulating layer is easily broken and the balance between insulation and conductivity is properly achieved, thus showing stable physical properties.

The insulating conductive particles of the present invention can be used to form various anisotropic conductive materials. Specifically, it may be dispersed in a matrix material such as a resin, or may be used in the form of a film adhesive or a paste adhesive. In this case, the content of the insulating conductive particles contained in the anisotropic conductive material is not particularly limited because the surface of the particles is insulative, so even if a large amount is mixed, short circuits between adjacent circuits do not occur, but are usually in the range of 1 to 95% by weight.

Hereinafter, a representative anisotropic conductive material to which the insulating conductive particles of the present invention are applied will be described in more detail.

(1) Anisotropic Conductive Film

The film adhesive is formed into a film shape after disperse | distributing the said insulating conductive particle in an insulating adhesive agent. As the insulating adhesive, a thermoplastic material used for an insulating sheet or the like or a curable material exhibiting curability by heat or light can be widely applied. Among them, the epoxy adhesive can be cured in a short time, so that the connection workability is good. It is preferable because there are characteristics such as excellent adhesion on the molecular structure. As the epoxy adhesive, for example, a polymer epoxy, a solid epoxy and a liquid epoxy, an epoxy mixed with a phenoxy resin and a liquid epoxy, urethane, polyester, NBR and the like as a main component, various additives such as latent curing agents and coupling agents The system which added the catalyst, etc. is common. Preparation of the anisotropic conductive film may be by a known method.

(2) paste adhesive

An insulating adhesive similar to the above-mentioned adhesive film (ACF) can be applied as an anisotropic conductive adhesive by mixing with the insulating conductive particles in a suitable solvent to form a paste and applying it to the use surface. Preparation of the anisotropic conductive paste adhesive also follows a well-known method.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are provided for the purpose of explanation and are not intended to limit the present invention.

Example 1

60 g of silica (Degussa QS-10), 2 g of γ-merctopropyl trimethoxy silane, 5 g of nitric acid, and 200 g of ethanol were added to the reaction vessel, and the silica and the silane coupling agent were reacted while maintaining a temperature of 60 ° C. A magnetic particle having was prepared. After the above reaction, 3g of conductive particles (NCI 9.7GNR -10㎛ average particle diameter) were added thereto, and reacted at 50 ° C. for 20 hours, and then the insulating conductive particles were recovered by using a magnet.

Example 2

60 g of alumina, 2 g of γ-mercito propyl trimethoxy silane, 5 g of nitric acid and 200 g of ethanol were added to the reaction vessel, and the alumina and silane coupling agent were reacted while maintaining a temperature of 60 ° C. to prepare a magnetic particle having a mucto functional group. It was. After the above reaction, 3g of conductive particles (NCI 9.7GNR -10㎛ average particle diameter) were added thereto, and reacted at 50 ° C. for 20 hours, and then the insulating conductive particles were recovered by using a magnet.

[Property evaluation]

The physical properties of the insulating conductive particles made in Examples 1 and 2 were evaluated as follows.

(1) Insulation evaluation of the prepared insulating conductive particles

To test the insulation of the recovered insulating conductive particles (inorganic particles bonded with the surface metal layer of the conductive particles by the conductive particles and the mercury functional group) to test the insulating properties of the insulating conductive particles prepared in Examples 1 and 2 The microparticles were used for the conductive particles. The result is as follows.

Initial resistance After 20% compression (compression at 20mN force) Example 1 10 ⁹ Ω or more 100Ω or less Example 2 10 ⁹ Ω or more 100Ω or less NCI 9.7GNR (Before Treatment) 100Ω or less 100Ω or less

As can be seen from the above table, the original conductive particles that were not reacted showed connection resistance of 100 Ω (one resistance value) or less from the beginning when the connection resistance was measured with a microcompression hardness meter, but the insulating properties prepared in Examples 1 and 2 were used. In the case of conductive particles, it can be seen that the initial contact resistance is measured to be 10 ⁹ Ω or more, indicating insulation. Also, if the compressed conductive particles are compressed, the insulating layer is destroyed when compressed to about 20% of the original size. It turns out that connection resistance falls rapidly and shows the connection resistance of 100 ohms or less. In other words, it can be seen that the conductive layer is restored while the insulating layer is broken. In addition, when observed under an electron scanning microscope (SEM) it can be seen that the magnetic particles are attached to the surface of the parent particle.

(2) Evaluation of conductivity on the anisotropic conductive film

Next, the conductivity was evaluated by making it onto the anisotropic conductive film like the example used actually.

Evaluation 1: The insulating conductive particle obtained in Example 1 was mix | blended with the epoxy adhesive containing a hardening | curing agent so that it may become 20% by solid content weight ratio, and an anisotropic conductive film with a thickness of 25 micrometers was made, and this film adhesive is pitched with the ITO electrode on a glass substrate, and pitch (pitch) 50 micrometers thick 35 micrometers copper circuits were pinched | interposed with the tinned FPC, and it connected under the thermocompression bonding conditions of 170 degreeC-20 Kgf / cm <2> -20 sec. When voltage was applied to this circuit, the connection resistance was 9.6 ohms, so it was confirmed that conduction occurred.

Evaluation 2: The insulating conductive particles obtained in Example 2 were filmed in the same manner as in Evaluation 1 to form a circuit. It was confirmed that the connection resistance measured after applying a voltage to this circuit became 5.8 Ω.

The insulating conductive particles according to the present invention have a larger adhesion than the insulating coated particles which are simply physically attached, and have a smaller adhesion than adhesion by covalent bonds, thereby maintaining insulation in the absence of heat and pressure, and easily insulating layers when heat and pressure are applied. This breakage results in an appropriate balance between insulation and conductivity, and the physical properties are stable and economical to produce. Therefore, the present invention can be usefully applied as a wide range of connection materials, such as between modules and between IC chips and circuits.

Claims (7)

Inorganic magnetic particles treated with a coupling agent are bonded to the surface of the conductive mother particle to form an insulating layer, wherein the coupling agent is a silane coupling agent having a thiol, thioether or disulfide functional group, and the inorganic magnetic particles are alumina or titanium dioxide. , At least one material selected from the group consisting of calcium titanate, magnesium titanate, zinc oxide, clay, calcium carbonate, silica, and tungsten carbide, wherein the conductive mother particles are metal particles or metal plated organic or inorganic particles. Insulating conductive particles, characterized in that. delete delete delete Treating the surface of the inorganic magnetic particles with a coupling agent; And Bonding the treated inorganic magnetic particles to a surface of a conductive mother particle to form an insulating layer, The coupling agent is a silane coupling agent having a thiol, thioether or disulfide functional group, and the inorganic magnetic particles are made of alumina, titanium dioxide, calcium titanate, magnesium titanate, zinc oxide, clay, calcium carbonate, silica, and tungsten carbide It is made of one or more materials selected from, wherein the conductive parent particles are metal particles or metal plated organic or inorganic particles manufacturing method of the insulating conductive particles, characterized in that. Anisotropic conductive material comprising the insulating conductive particles according to claim 1. The anisotropic conductive material according to claim 6, wherein the anisotropic conductive material is a film or a paste adhesive.