JP2012036313A - Method for producing inorganic oxide particle and anisotropic electrically conductive adhesive using inorganic oxide particle obtained by the production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing inorganic oxide particles 6 that can attain sufficient dispersibility when mixed with an anisotropic electrically conductive adhesive etc., and an anisotropic electrically conductive adhesive 10 using the inorganic oxide particles 6 obtained by the production method.SOLUTION: The method for producing the inorganic oxide particles 6 includes a step for chemically adsorbing a three-dimensionally crosslinked silicone oligomer having a weight-average molecular weight of 500-10,000 on the surfaces of the inorganic oxide particles in a vapor phase.

Description

  The present invention relates to a method for producing inorganic oxide particles, and an anisotropic conductive adhesive using inorganic oxide particles obtained by the production method.

  Conventionally, as a method for producing surface hydrophobic inorganic oxide particles, a method in which the surface of inorganic oxide particles is dry-treated with silicone oil such as polydimethylsiloxane is known (see Patent Document 1 and Patent Document 2). Patent Document 3 describes an adhesive resin composition obtained by blending an adhesive resin with silica fine powder having an organic group (reactive organic group) that reacts with the adhesive resin component on the surface. Here, an example is shown in which silica is treated with a silicone oil or a silane coupling agent having a functional group that reacts with the adhesive resin component. Furthermore, in this patent, the treatment with silicone oil alone is insufficient in hydrophobicity, so after treatment with silicone oil, hexamethylsilazane, dimethylpolysiloxane, methylchlorosilane, alkyltrialkoxysilane, diallyldialkoxysilane, etc. Processing is performed twice.

  In addition, Patent Document 4 has a description that insulation and heat resistance are improved by blending a varnish with an inorganic material obtained by surface-treating a three-dimensionally crosslinked silicone oligomer in a solvent.

  On the other hand, when electrically connecting circuit boards to each other or connecting an IC chip or electronic component to a circuit board, an adhesive or an anisotropic conductive adhesive in which conductive particles are dispersed is used. Such a connection form is remarkable in the liquid crystal field. The method of mounting a liquid crystal driving IC on a liquid crystal display glass panel can be broadly classified into two types, COG (Chip-on-Glass) mounting and COF (Chip-on-Flex). In COG mounting, an IC for liquid crystal is directly bonded onto a glass panel using an anisotropic conductive adhesive containing conductive particles. On the other hand, in COF mounting, a liquid crystal driving IC is bonded to a flexible tape having metal wiring, and these are bonded to a glass panel using an anisotropic conductive adhesive containing conductive particles. Anisotropy here means conducting in the pressurizing direction and maintaining insulation in the non-pressurizing direction. As the conductive particles, particles obtained by performing nickel plating or nickel / gold plating on the outside of the plastic particles are used. Particles subjected to nickel / gold plating are considered to have better insulation.

With the recent high definition of liquid crystal displays, the gold bumps, which are circuit electrodes for liquid crystal driving ICs, have narrowed pitch and area, so that the conductive particles of anisotropic conductive adhesive are between adjacent circuit electrodes. There is a problem that a short circuit occurs due to outflow. This tendency is particularly remarkable in COG mounting. When conductive particles flow out between adjacent circuit electrodes, the number of conductive particles in the anisotropic conductive adhesive trapped between the gold bump and the glass panel decreases, and the connection resistance between the opposing circuit electrodes increases. There was a problem of poor connection. Particularly in recent years, since 20,000 particles / mm ² or more of conductive particles are introduced per unit area by narrowing the pitch and area of gold bumps, the tendency is remarkable.

  Therefore, as a method for solving these problems, as shown in Patent Document 5, by forming an insulating adhesive on at least one surface of the anisotropic conductive adhesive, COG mounting or deterioration in bonding quality in COG mounting. And a method of covering the entire surface of the conductive particles with an insulating coating as exemplified in Patent Document 6.

  On the other hand, adhesives containing inorganic oxide particles are generally used because they are easy to produce due to the thickening effect. As the inorganic oxide particles, those that have been subjected to a hydrophobic treatment by coating the inorganic oxide particles with hydrophobic molecules are often used.

  Furthermore, although it is an inorganic oxide particle used in the field of powder coating, Patent Document 7 and Patent Document 8 describe those in which the inorganic oxide particle is coated with a hydrophobic molecule. Examples of commercially available inorganic oxide particles subjected to hydrophobic treatment include R202 (manufactured by Nippon Aerosil Co., Ltd.) coated with dimethylsiloxane and silica having an average diameter of φ14 nm, and R805 (Nihon Aerosil Co., Ltd.) coated with silica having an average diameter of φ12 nm with octylsilane. Etc.).

U.S. Pat. No. 4,477,607 U.S. Pat. No. 4,713,405 Japanese Patent Laid-Open No. 10-287854 Japanese Patent No. 2904311 Japanese Patent Laid-Open No. 08-279371 Japanese Patent No. 2779409 JP 2004-210875 A JP 2004-168559 A

  However, according to the study by the present inventors, when inorganic oxide particles coated with hydrophobic molecules as described in Patent Documents 7 and 8 are added to the anisotropic conductive adhesive, the inorganic oxide Since the dispersibility of the particles is insufficient, sufficient insulation in the non-pressurizing direction cannot be obtained. Such a problem is noticeable when the amount of inorganic oxide particles is increased. In addition, in order to improve the dispersibility of the inorganic oxide particles in the anisotropic conductive adhesive, a method of previously crushing the inorganic oxide particles can be considered, but in this case, the inorganic oxide particles reaggregate. It is not a fundamental solution for dispersibility.

  The present invention has been made in view of such circumstances, and an inorganic oxide for producing inorganic oxide particles capable of achieving sufficient dispersibility when blended in an anisotropic conductive adhesive or the like. It aims at providing the manufacturing method of a thing. Another object of the present invention is to provide an anisotropic conductive adhesive using inorganic oxide particles obtained by the production method.

  In order to solve the above-described problems, the method for producing inorganic oxide particles of the present invention includes a three-dimensionally crosslinked silicone oligomer having a weight average molecular weight in the range of 500 to 10000 in the gas phase on the surface of the inorganic oxide particles. The process of chemical adsorption is provided.

According to the production method of the present invention, since it has the above-described configuration, inorganic oxide particles having good dispersibility in the anisotropic conductive adhesive can be produced. The adoption of the above configuration in the production method of the present invention is based on the knowledge of the present inventors described below.
That is, according to the study by the present inventors, sufficient dispersibility cannot be obtained when the inorganic oxide particles are blended with the anisotropic conductive adhesive because of the hydroxyl groups remaining on the surface of the inorganic oxide particles. That is, it was found that the hydrophobic treatment on the surface of the inorganic oxide particles was insufficient. Therefore, it was confirmed that the effect of residual hydroxyl groups on the surface of the inorganic oxide particles can be effectively suppressed by three-dimensionally covering the surface of the inorganic oxide particles with a three-dimensionally crosslinked silicone oligomer. Based on these findings The present invention has been completed.

  In addition, the present inventors speculate as follows for other reasons why the above-described effects are exhibited by the present invention.

That is, in the method for producing inorganic oxide particles of the present invention, a silicone oligomer that has been three-dimensionally crosslinked in advance is adsorbed onto the inorganic oxide particles. For this reason, compared with the case where the surface of the inorganic oxide is treated with a three-dimensional crosslinked structure by a gas phase graft polymerization method using a trifunctional silane coupling agent, etc., the variation in the adsorption thickness on the surface of the inorganic oxide particles It can be suppressed. Therefore, unevenness of the hydrophobic treatment on the surface of the inorganic oxide particles is less likely to occur, and the effect of improving the dispersibility of the inorganic oxide particles can be achieved at a high level when blended with the anisotropic conductive adhesive.
Furthermore, by adsorbing the silicone oligomer in the gas phase, the unreacted silicone oligomer can be removed by a reduced pressure treatment. By chemically adsorbing the inorganic oxide particles to the silicone oligomer, the obtained inorganic oxide particles are anisotropic. The present inventors consider that the fact that the silicone oligomer is difficult to peel off when dispersed in the conductive adhesive is also one of the reasons for the improvement in dispersibility due to the hydrophobicity of the inorganic oxide particle surface. Yes.

  In the present invention, the weight average molecular weight of the silicone oligomer is preferably in the range of 500 to 10,000, and more preferably in the range of 500 to 6,000. In terms of the degree of polymerization, those of 3 to 90 (converted from the weight average molecular weight by GPC) are preferred, and those of 5 to 80 are more preferred. When a silicone oligomer having a weight average molecular weight or a polymerization degree of not more than the above upper limit value is used, uneven treatment is less likely to occur during hydrophobic treatment of inorganic oxide particles, and the reliability can be further improved. Further, when a silicone oligomer having a weight average molecular weight or a polymerization degree of not less than the above lower limit is used, an adsorption thickness of a certain value or more can be obtained, and the effect of improving the dispersibility by hydrophobizing the surface can be sufficiently obtained.

  When the inorganic oxide particles obtained by the production method of the present invention are blended in an anisotropic conductive adhesive to produce an anisotropic conductive adhesive film (ACF), the appearance of the anisotropic conductive adhesive film can be improved. For this reason, as a result of the suppression of the aggregation of the inorganic oxide particles with the improvement of the dispersibility of the inorganic oxide particles when blended in the anisotropic conductive adhesive, the anisotropic conductive adhesive is applied to the base material. Presumably because of improved sex.

In addition, the anisotropic conductive adhesive in which conventional conductive particles are dispersed has the following problems. For example, as shown in Patent Document 5, in a multilayer connection member (an anisotropic conductive adhesive) in which an insulating adhesive layer is formed on at least one surface of a conductive adhesive layer having conductivity in a pressing direction, When the bump area is less than 3000 μm ² and the conductive particles are increased in order to obtain a stable connection resistance, there is still room for improvement in the insulation between adjacent electrodes. In addition, the method of covering the entire surface of the conductive particles described in Patent Document 6 with an insulating coating has a problem that the conductivity tends to be low although the insulating property is high. On the other hand, the method of coating the surface of the conductive particles with the insulating child particles has a good balance between the initial insulating property and the conductive property, but there is a problem that insulation deterioration occurs due to migration during a long-term reliability test. In particular, migration under high temperature conditions was a problem. In addition, although the conductive particles in the anisotropic conductive adhesive are increased, there is a problem that the conductive particles are difficult to be captured on the bumps due to the flow of the adhesive component during pressure bonding. Therefore, it is important from the viewpoints of both conduction and insulation that the conductive particles do not move as much as possible during pressure bonding.

  On the other hand, when the inorganic oxide particles manufactured by the manufacturing method of the present invention are added to the anisotropic conductive adhesive, the conductive particles are difficult to move at the time of pressure bonding, so that the capture rate of the conductive particles on the connection electrode is increased. Is possible. As a result, it is possible to provide an anisotropic conductive adhesive film that can maintain the resistance between the electrodes to be connected to a small value for a sufficiently long time and at the same time realizes the improvement of the insulating characteristics between adjacent electrodes. Even if such an anisotropic conductive adhesive film is used in a field where heat resistance is required in long-term outdoor high-temperature use such as for solar cells, the characteristics can be sufficiently exhibited.

  The step in the method for producing inorganic oxide particles includes the step of mixing a mixed solution obtained by diluting a silicone oligomer with a solvent having a boiling point lower than the thermal decomposition temperature of the silicone oligomer on the surface of the inorganic oxide particles being stirred in the gas phase. The step of dropping and stirring the inorganic oxide particles after dropping at a temperature lower than the thermal decomposition temperature of the silicone oligomer and higher than the boiling point of the solvent, and then removing the unreacted silicone oligomer at a high temperature under reduced pressure is preferable.

  Stirring at a temperature lower than the thermal decomposition temperature of the silicone oligomer and higher than the boiling point of the solvent is preferable because the silicone oligomer and the inorganic oxide particles undergo dehydration condensation (or dealcoholization reaction) without thermal decomposition. Specifically, it is preferably 100 ° C. or higher (however, higher than the boiling point of the solvent) and 400 ° C. or lower (but lower than the decomposition temperature of the silicone oligomer), more preferably 150 ° C. or higher and 300 ° C. or lower. Moreover, by removing the unreacted silicone oligomer, it becomes difficult for the silicone oligomer to elute and the deterioration of the properties of the resulting inorganic oxide particles can be prevented.

  Moreover, it is preferable that the thermal decomposition temperature of a silicone oligomer is 500 degreeC or more.

  It is preferable to purge with nitrogen when stirring the inorganic oxide particles. As a result, the risk of the solvent exploding can be reduced, and the volatilized solvent can be removed smoothly.

  The graft ratio of the silicone oligomer is preferably in the range of 4% to 100%. When the graft ratio is 4% or more, the inorganic oxide particles are sufficiently covered with the silicone oligomer, and dispersibility in the anisotropic conductive adhesive is easily obtained. On the other hand, when the graft ratio is 100% or less, most of the characteristics of the obtained inorganic oxide particles do not become the characteristics of the silicone oligomer, so that it is possible to ensure insulation in the non-pressurizing direction in the anisotropic conductive adhesive. it can. The graft ratio is more preferably in the range of 7% to 50%.

  The three-dimensionally crosslinked silicone oligomer has at least one siloxane unit selected from bifunctional and trifunctional units, and at least one siloxane unit selected from trifunctional and tetrafunctional siloxane units. It is preferable to have types. For example, those consisting only of a trifunctional siloxane unit, those consisting of a bifunctional siloxane unit and a trifunctional siloxane unit, those consisting of a trifunctional siloxane unit and a tetrafunctional siloxane unit, and bifunctional Are preferably composed of a functional siloxane unit, a trifunctional siloxane unit and a tetrafunctional siloxane unit. Moreover, it is preferable to contain a tetrafunctional siloxane unit in 15 mol% or more, preferably 20 to 60 mol% in all siloxane units.

R is preferably a phenyl group. When R is a phenyl group, the anisotropic conductive adhesive obtained by blending the obtained inorganic oxide particles is particularly excellent in heat resistance and insulation, and has good characteristics as an adhesive for circuit connection. For this reason, it is preferable to use at least one silicone oligomer containing a phenyl group. Specifically, PhSi (OCH ₃ ) ₃ , PhSi (OC ₂ H ₅ ) ₃ , PhSi (OC ₃ H ₇ ) ₃ , PhSi (OC ₄ H ₉ ) ₃ , Ph ₂ Si (OCH ₃ ) ₂ , Ph ₂ Examples include silanol compounds such as Si (OC ₂ H ₅ ) ₂ , Ph ₂ Si (OC ₃ H ₇ ) ₂ , Ph ₂ Si (OC ₄ H ₉ ) ₂ (where Ph represents a phenyl group).

  The anisotropic conductive adhesive of the present invention contains 5 wt% or more of inorganic oxide particles produced by the method for producing inorganic oxide particles.

  ADVANTAGE OF THE INVENTION According to this invention, when mix | blended with an anisotropic conductive adhesive etc., the manufacturing method of the inorganic oxide particle which can achieve sufficient dispersibility can be provided. Moreover, it becomes possible to provide an anisotropic conductive adhesive using inorganic oxide particles obtained by the production method.

It is sectional drawing which shows one Embodiment of an anisotropic conductive adhesive. It is sectional drawing which shows one Embodiment of the COG mounting method by an anisotropic conductive adhesive. It is a figure which shows one Embodiment of a connection structure.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

  The method for producing inorganic oxide particles of the present embodiment includes a step of chemically adsorbing a three-dimensionally crosslinked silicone oligomer having a weight average molecular weight in the range of 500 to 10,000 on the surface of the inorganic oxide particles in the gas phase.

  In the above step, a mixed solution obtained by diluting a silicone oligomer with a solvent having a boiling point lower than the thermal decomposition temperature of the silicone oligomer is dropped on the surface of the inorganic oxide particles stirred in the gas phase, and after the dropping The inorganic oxide particles are stirred at a temperature lower than the thermal decomposition temperature of the silicone oligomer and higher than the boiling point of the solvent, and then the unreacted silicone oligomer is removed under a high temperature under reduced pressure. Hereinafter, the manufacturing method of the inorganic oxide particle of this embodiment is demonstrated in detail.

  The inorganic oxide particles have a surface covered with a hydroxyl group and are hydrophilic (a hydroxyl group bonded to silicon may be referred to as silanol). When such hydrophilic inorganic oxide particles are put in the anisotropic conductive adhesive, they aggregate and thus the conductive particles are difficult to move at the time of pressure bonding, and the trapping rate of the conductive particles on the connection electrode tends to decrease. In addition, since the coating property of the anisotropic conductive adhesive tends to deteriorate, the surface of the inorganic oxide particles needs to be subjected to a hydrophobic treatment. Specifically, it is desirable to adsorb a silicone oligomer having both a functional group that easily reacts with a hydroxyl group and a hydrophobic functional group to the inorganic oxide particles.

  Examples of inorganic oxide particles include silica, alumina, zirconium oxide, antimony trioxide, antimony pentoxide, magnesium oxide, titanium oxide, and zinc oxide. Uniform particle size and insulation, and easy surface treatment. From this viewpoint, silica is preferable. Silica having a particle diameter of 5 to 500 nm can be used. If a film having a thickness of 5 to 30 nm is used, the characteristics are further improved. Silica having a size of 5 nm or less cannot be stably surface-treated, and has no stable size. In addition, when a silica particle having a silica diameter of 30 nm or more is used, the thickening effect at the time of blending with the anisotropic conductive adhesive becomes insufficient, and the conductive particles are difficult to move at the time of pressure bonding. It is difficult to improve. The particle diameter here is the particle diameter (primary particle diameter) calculated by the BET specific surface area method. The reason why the inorganic oxide particles are used for the gas phase treatment is that they are preferable from the viewpoint of uniformity of particle diameter and insulating properties. Further, when hard inorganic oxide particles are used, there is a tendency that the thickening effect can be increased when blended with the anisotropic conductive adhesive.

  The silicone oligomer preferably has a degree of polymerization of 3 to 90 (converted from the weight average molecular weight by GPC), more preferably 5 to 80. When a silicone oligomer having a degree of polymerization of 80 or less is used, uneven treatment hardly occurs during the hydrophobic treatment of the inorganic oxide particles, and the reliability is improved. Further, when a silicone oligomer having a degree of polymerization of 5 or more is used, an adsorption thickness of a certain level or more can be obtained, and the effect of improving the dispersibility by hydrophobicizing the surface can be sufficiently obtained. The weight average molecular weight is preferably in the range of 500 to 10,000, and more preferably in the range of 500 to 6000.

The silicone oligomer adsorbed on these inorganic oxide particles is preferably one having a functional group that reacts in advance with a three-dimensional condensation reaction such as silica and a hydrophobic functional group. Specifically, a trifunctional siloxane unit (RSiO _3/2 ) (wherein R is a functional group, for example, an alkyl group having 1 or 2 carbon atoms such as a methyl group or an ethyl group, or a carbon number of 6 such as a phenyl group). -12 aryl groups, vinyl groups, glycidoxypropyl groups, etc., and R groups in the silicone oligomer may be the same or different from each other) and bifunctional siloxane units (R ₂ ). It is preferable to contain at least one siloxane unit selected from SiO _2/2 ) and tetrafunctional siloxane units (SiO _4/2 ).

Here, R ₂ SiO _2/2 , RSiO _3/2 , and SiO _4/2 each representing a bifunctional, trifunctional, or tetrafunctional siloxane unit have the following structures.

Here, at least one of R is preferably a silicone oligomer containing a phenyl group. When R is a phenyl group, heat resistance and insulation are particularly excellent, and the characteristics as an adhesive for circuit connection are improved. Specifically, PhSi (OCH ₃ ) ₃ , PhSi (OC ₂ H ₅ ) ₃ , PhSi (OC ₃ H ₇ ) ₃ , PhSi (OC ₄ H ₉ ) ₃ , Ph ₂ Si (OCH ₃ ) ₂ , Ph ₂ Examples include silanol compounds such as Si (OC ₂ H ₅ ) ₂ , Ph ₂ Si (OC ₃ H ₇ ) ₂ , Ph ₂ Si (OC ₄ H ₉ ) ₂ (where Ph represents a phenyl group). When R reacts with the adhesive component of the anisotropic conductive adhesive dispersed later, it is often favorable in terms of various properties such as insulation. For example, when the adhesive component is an acrylic resin, R may have a vinyl group.

  The silicone oligomer used for the treatment of the inorganic oxide particles is preferably three-dimensionally crosslinked in advance. Therefore, it is preferable to have at least one type of siloxane unit selected from trifunctional and tetrafunctional siloxane units, and at least one type of siloxane unit selected from bifunctional and trifunctional units. For example, those consisting only of trifunctional siloxane units, those consisting of bifunctional siloxane units and trifunctional siloxane units, those consisting of trifunctional siloxane units and tetrafunctional siloxane units, and bifunctional siloxane units and 3 What consists of a functional siloxane unit and a tetrafunctional siloxane unit is preferable. Moreover, it is preferable to contain a tetrafunctional siloxane unit 15 mol% or more, preferably 20 to 60 mol% in all siloxane units. In order to cover the surface of the inorganic oxide particles with a sufficient three-dimensional crosslinked structure, the degree of polymerization of the silicone oligomer containing a trifunctional siloxane unit and / or a tetrafunctional siloxane unit is preferably 3 to 90. More preferably, it is 5-80. Such a silicone oligomer can be synthesized by, for example, condensing chloro or alkoxysilane corresponding to a desired siloxane unit using an acid catalyst in the presence of water. The condensation reaction is performed to such an extent that it does not become a gel before the surface treatment. For this purpose, the reaction temperature, reaction time, oligomer composition ratio, and type and amount of catalyst are adjusted. As the catalyst, acetic acid, hydrochloric acid, maleic acid, phosphoric acid and the like are preferably used.

  Methods for hydrophobizing inorganic oxide particles include gas phase treatment and liquid phase treatment. The inorganic oxide particles cannot be dispersed in an aromatic hydrocarbon-based and oxygen-containing mixed solvent that is used when blended directly into the anisotropic conductive adhesive. In addition, since it is difficult to filter the inorganic oxide particles that are nanoparticles, it is desirable to subject the inorganic oxide particles to a gas phase treatment.

  As a method for the gas phase treatment, specifically, inorganic oxide particles are put in a flask and stirred. Next, a silicone oligomer is dropped or sprayed on the surface of the inorganic oxide particles. Next, the whole flask is heated under a nitrogen atmosphere to promote adhesion with the silicone oligomer. After that, it is crushed and powdered once.

  The treatment method for the inorganic oxide particles such as the treatment liquid and surface treatment conditions of the silicone oligomer is not particularly limited, but as an example, while stirring the inorganic oxide particles in a heated nitrogen atmosphere, the silicone oligomer 5-100 wt% A method of dropping a% solution is simple.

  In addition to the silicone oligomer, the treatment liquid for treating the inorganic oxide particles may contain additives including various solvents, silane coupling agents, coupling agents such as titanate coupling agents, and the like. good. As the silane coupling agent, generally, epoxy silane such as γ-glycidoxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane, hydrochloride, etc. Examples include aminosilane-based, cationic silane-based, vinylsilane-based, acrylicsilane-based, mercaptosilane-based, and composite systems thereof. Examples of titanate coupling agents include isopropyl tris (dioctylpyrophosphate) titanate. These coupling agents are used in an arbitrary amount. Further, the surface of the inorganic oxide particles before or after the treatment with the silicone oligomer may be further subjected to a surface treatment with a silane coupling agent or a titanate.

  Thus, the inorganic oxide particle which processed the three-dimensional crosslinked silicone oligomer in the gaseous phase shows the property which the conventional surface treatment inorganic oxide particle does not have. That is, since it is treated with a three-dimensionally crosslinked silicone oligomer, it exhibits higher hydrophobicity than conventional surface-treated inorganic oxide particles even if the graft ratio on the surface of the inorganic oxide particles is the same. When the treatment is performed with a silane coupling agent that is a monomer, high hydrophobicity is not exhibited due to uneven treatment. When silicone oil such as ordinary polydimethylsiloxane is used, the effect of the silicone oil is less than that of a three-dimensionally crosslinked silicone oligomer because the silicone is not crosslinked at high density. Moreover, since the total amount of hydroxyl groups and methoxy groups is less than that of dimethylsiloxane, silicone oil has few contacts with inorganic oxides.

  Hereinafter, a specific hydrophobic treatment method will be described. A three-necked or four-necked eggplant-shaped flask may be used for the gas phase treatment. For example, when a 3 L eggplant-shaped flask is used, 30 to 200 g of inorganic oxide particles can be subjected to hydrophobic treatment. The smaller the particle size, the larger the surface area of the inorganic oxide particles and the greater the bulk. Therefore, the processing weight is reduced for small particle sizes, and the processing weight is increased for large particle sizes.

  During the hydrophobic treatment, the reactivity is slightly different depending on the moisture contained in the inorganic oxide particles. It may be preferable to carry out the reaction under moisture absorption because the methoxy group replaces the hydroxyl group and promotes dehydration condensation. The water content of the inorganic oxide particles should be adjusted as appropriate. Specifically, the water content is preferably adjusted between 0% and 50%.

  Next, a silicone oligomer is dropped or sprayed on the surface of the inorganic oxide particles. When the silicone oligomer is dropped or sprayed, if it is too early, uneven coating on the inorganic oxide particles can occur, so it is performed as slowly as possible. When the silicone oligomer is dropped or sprayed, the inorganic oxide particles are stirred with a stirring blade or the like. The stirring speed is preferably in the range of 10 to 500 rpm.

  The silicone oligomer may be dropped at a concentration of 100%, but the coating variation increases. Therefore, it is good to use after diluting to 10 to 50%. The solvent used for dilution needs to be lower than the boiling point of the silicone oligomer. Specific examples include methanol, ethanol, propanol, acetone, dimethylformamide, acetonitrile, and the like. When the concentration of the silicone oligomer is less than 10%, the inorganic oxide particles before the reaction are easily gelled, which is not preferable. When the silicone oligomer concentration exceeds 50%, the coating unevenness increases. The reason why the coating unevenness becomes large is considered to be that when the concentration is 100%, the silicone oligomer is immediately adsorbed on the dropped portion. That is, the reaction rate can be controlled by diluting the solvent. In particular, when a three-dimensionally crosslinked silicone oligomer is used, since the reactivity is good, dripping at a concentration of 100% is not preferable because the particle unevenness is severe.

  Next, stirring is performed at a temperature lower than the boiling point of the silicone oligomer and higher than the boiling point of the solvent. The reaction may be performed while replacing with an inert gas during stirring. As a result, the risk of the organic solvent exploding can be reduced, and the volatilized solvent can be removed smoothly. Nitrogen gas may be inexpensive as the inert gas. Nitrogen gas is purged by providing an inlet and an outlet. The flow rate of nitrogen gas is appropriately adjusted in the range of 1 ml / min to 1000 ml / min when a 3 L eggplant type flask is used. If the flow rate is too small, the volatilized solvent cannot be removed smoothly. Moreover, when there is too much flow volume, the temperature in a flask will fall too much and reaction will not advance.

  The reaction proceeds by dehydration condensation (or dealcoholization reaction) between the silicone oligomer and the inorganic oxide particles. The temperature during the reaction is preferably higher than the temperature at which dehydration condensation occurs. Specifically, it is preferably 100 ° C. or higher (provided that the boiling point of the solvent is higher), 400 ° C. or lower (however, the decomposition temperature of the silicone oligomer is lower), and more preferably 150 ° C. or higher and 300 ° C. or lower. If the reaction temperature is high, the reaction time is short, but the processing unevenness increases. Heating should be done with an oil bath or mantle heater. The heat treatment time in a nitrogen atmosphere is preferably in the range of 10 minutes to 24 hours, more preferably in the range of 1 hour to 6 hours.

  The decomposition temperature of the silicone oligomer here is a temperature at which weight is reduced by heat, and is a temperature of an exothermic peak as measured by DTA (differential thermal analysis). Generally, the decomposition temperature of the silicone oligomer is in the range of 400 ° C to 600 ° C.

  After the heat treatment under a nitrogen atmosphere, the unreacted silicone oligomer is removed by reducing the pressure while maintaining the temperature. The conditions under which the silicone oligomer volatilizes under reduced pressure and high temperature are set. The decompression time is preferably about 10 minutes to 2 hours. If the decompression time, the degree of vacuum during decompression, and the temperature during decompression are insufficient, the unreacted silicone oligomer cannot be removed, making it easier for the silicone oligomer to elute and improving the dispersibility associated with hydrophobicity. There may not be.

The graft ratio of the silicone oligomer thus completed can be measured based on the weight loss. In this embodiment, the graft ratio is defined as follows.
Graft ratio (%) = weight of silicone oligomer / weight of inorganic oxide particles × 100

Although depending on the actual measurement method, the graft ratio can be defined as follows.
However, it is limited to the case where the inorganic oxide particles do not lose weight at 1000 ° C. This is the case with most inorganic oxide particles such as silica.
Graft ratio (%) = (sample mass at room temperature−sample mass at 1000 ° C.) / Sample mass at 1000 ° C. × 100

  The graft ratio of the inorganic oxide particles is preferably in the range of 4% to 100%. When the graft ratio is 4% or more, the inorganic oxide particles are sufficiently covered with the silicone oligomer, and dispersibility in the anisotropic conductive adhesive is easily obtained. On the other hand, if the graft ratio is 100% or less, most of the properties of the resulting inorganic oxide particles can be avoided to be those of a silicone oligomer, so that the anisotropic conductive adhesive has insulation in the non-pressurizing direction. Obtainable. The graft ratio is more preferably in the range of 7% to 50%.

  Among the grafted silicone oligomers, chemical adsorption and physical adsorption should exist, but it is difficult to set the chemical adsorption and physical adsorption strictly. Therefore, here, the inorganic oxide particles after the surface treatment are dispersed in a solvent in which the silicone oligomer can be melted, and what does not peel off is defined as a chemical adsorption component. More specifically, it is defined in the examples.

  It is desirable that the silicone oligomer for the chemical adsorption occupies 50% or more of the total adsorption. When the chemical adsorption is 50% or less, even if the apparent grafting rate is high, it peels when dispersed in the adhesive, and thus there is a possibility that the effect of improving the dispersibility by hydrophobization may not be obtained.

  The grafted silicone oligomer produced as described above is preferably used after making a slurry dispersed in a solvent. Examples of the dispersion method include a bead mill, ultrasonic waves, and liquid layer collision crushing.

  Although it does not specifically limit as a solvent used for a slurry, It is good to use the same solvent used at the time of subsequent varnish compounding. For example, if it is used for an anisotropic conductive adhesive film, an aromatic hydrocarbon-based and oxygen-containing mixed solvent is preferable because it improves the solubility of the material. Specific examples include a mixed solvent of toluene and ethyl acetate or methyl ethyl ketone.

  If the grafting onto the surface of the inorganic oxide particles is not uniform during dispersion, the inorganic oxide particles tend to aggregate when blended in the anisotropic conductive adhesive, and the viscosity tends to increase. When used as a thickener, it can be used with a higher viscosity, but it is better to coat uniformly when considering insulation and heat resistance.

  By observing the state of secondary aggregation in the solvent, it is possible to determine the uniformity of grafting on the surface of the inorganic oxide particles. Specifically, the slurry is diluted with the same solvent to a concentration of about 0.1 wt%, and the particle diameter (secondary particle diameter) is measured by dynamic light scattering. If the grafting is performed uniformly, the primary particle diameter and the secondary particle diameter are close to each other. If the grafting is not performed uniformly, the primary particle diameter and the secondary particle diameter are different due to aggregation. Become.

  In general, when primary particles of 30 nm or less are used, it can be said that the grafting is relatively uniform if the secondary particle diameter after grafting is 100 nm or less.

  Alternatively, it can be judged that the aggregation is small if the grafted inorganic oxide particles are dispersed in a solvent such as toluene or methyl ethyl ketone at a concentration of about 15 wt% and the viscosity measured by a vibration viscometer is 30 mPa · s or less. If it is 60 mPa · s or more, it can be judged that the hydrophilic functional groups on the surface are not crushed and are aggregated.

  If importance is attached to insulation and coating properties, a secondary particle diameter after grafting of 100 nm or less and a 15 wt% slurry viscosity of 30 mPa · s or less may be used.

  When adjusting the slurry, a silane coupling agent, silicone oligomer, or silazane may be added.

[Conductive particles]

  Next, the conductive particles of this embodiment will be described. In the present embodiment, the use of conductive particles whose surfaces are partially covered with insulation as the conductive particles further improves the insulation.

  Such conductive particles can be produced by coating the surface of normal conductive particles with insulating child particles.

  The particle diameter of the conductive particles used in the present embodiment needs to be smaller than the minimum interval between the electrodes of the substrate, and when there is a variation in the height of the electrodes, it is preferable that the particle size is larger than the variation in height. The range of 1-10 micrometers is preferable by the said concept, The range of 2.5-5.0 micrometers is more preferable, The range of 2.5-4.0 micrometers is still more preferable.

  The conductive particles may be either metal-only particles and organic or inorganic core particles that are metal-coated by a method such as plating. Among these, organic core particles that are metal-coated by plating are preferred.

  Although it does not specifically limit as a metal coat | covered by plating etc. Gold, silver, copper, platinum, zinc, iron, palladium, nickel, tin, chromium, titanium, aluminum, cobalt, germanium, cadmium etc. metals, ITO, solder, etc. A metal compound is mentioned. From the viewpoint of corrosion resistance, nickel, palladium, and gold are preferable.

  The metal layer may have a single layer structure or a laminated structure including a plurality of layers. In the case of a laminated structure, it is preferable to coat the outermost layer with gold or palladium from the viewpoint of corrosion resistance and conductivity.

  Examples of the metal coating method include electroless plating, displacement plating, electroplating, and sputtering.

  Although the thickness of a metal layer is not specifically limited, The range of 0.001-1.0 micrometer is preferable and the range of 0.005-0.3 micrometer is more preferable.

  If the thickness of the metal layer is less than 0.001 μm, poor conduction is likely to occur, and if it exceeds 1.0 μm, it is not preferable in terms of cost.

  The organic core particle is not particularly limited, and examples thereof include acrylic resins such as polymethyl methacrylate and polymethyl acrylate, and polyolefin resins such as polyethylene, polypropylene, polyisobutylene, and polybutadiene.

  As the insulator particles coated on the conductive particles, organic fine particles or inorganic oxide fine particles are preferable. The method for coating organic fine particles or inorganic oxide fine particles is not limited, but an example is shown below.

As the inorganic oxide fine particles, oxides containing each element of silicon, aluminum, zirconium, titanium, niobium, zinc, tin, cerium, and magnesium are preferable, and these may be used alone or in combination of two or more. it can. Among these, water-dispersed colloidal silica (SiO ₂ ) having excellent insulating properties and controlled particle diameter is most preferable. Examples of such commercially available inorganic oxide fine particles include Snowtex, Snowtex UP (manufactured by Nissan Chemical Industries, Ltd.), Quatron PL series (manufactured by Fuso Chemical Industries, Ltd.) and the like. In terms of insulation reliability, the concentration of alkali metal ions and alkaline earth metal ions in the dispersion solution is desirably 100 ppm or less, preferably an inorganic oxidation produced by a hydrolysis reaction of metal alkoxide, a so-called sol-gel method. Fine particles are suitable.

  As for the size of the inorganic oxide fine particles, the particle diameter measured by the specific surface area conversion method by the BET method or the X-ray small angle scattering method is preferably 20 nm to 500 nm. If it is smaller than that, the inorganic fine particles adsorbed on the conductive particles do not act as an insulating film and cause a short circuit in part. On the other hand, if it is larger than that, conductivity in the pressurizing direction of the connection cannot be obtained.

Among inorganic oxides, water-dispersed colloidal silica (SiO ₂ ) has a hydroxyl group on the surface, and is particularly suitable because of its excellent bondability with conductive particles, ease of uniform particle diameter, and low cost.

  The hydroxyl group on the surface of the inorganic oxide can be modified to an amino group, a carboxyl group or an epoxy group with a silane coupling agent or the like, but it is difficult when the particle size of the inorganic oxide is 500 nm or less. Therefore, it is desirable to coat the conductive particles without modifying the functional group.

  In general, hydroxyl groups are known to form strong bonds with hydroxyl groups, carboxyl groups, alkoxyl groups, and alkoxycarbonyl groups. Examples of the mode of bonding between the hydroxyl group and these functional groups include covalent bonding by dehydration condensation and hydrogen bonding. Therefore, these functional groups are preferably formed on the surface of the conductive particles.

  When the conductive particles have a gold surface, a compound having any of a mercapto group, sulfide group, or disulfide group that forms a coordinate bond to gold forms a hydroxyl group, carboxyl group, alkoxyl group, or alkoxycarbonyl group on the gold surface. Good. Specific examples include mercaptoacetic acid, 2-mercaptoethanol, methyl mercaptoacetate, mercaptosuccinic acid, thioglycerin, and cysteine.

  A method for treating the above compound on the gold surface is not particularly limited, but a compound such as mercaptoacetic acid is dispersed in an organic solvent such as methanol or ethanol in an amount of about 10 to 100 mmol / l, and conductive particles having a gold surface are dispersed therein. Disperse.

  Next, the surface of the conductive particles having a functional group is coated with an inorganic oxide. The surface potential (zeta potential) of the conductive particles having a hydroxyl group, a carboxyl group, an alkoxyl group, or an alkoxycarbonyl group is usually (pH is in a neutral region). If so) negative. On the other hand, the surface potential of an inorganic oxide having a hydroxyl group is usually negative. It is difficult to coat particles having a negative surface potential around particles having a negative surface potential.

Therefore, a method of alternately laminating a polymer electrolyte and an inorganic oxide is preferable. As a more specific production method, conductive particles having a functional group are (1) dispersed in a polymer electrolyte solution, the polymer electrolyte is adsorbed on the surface of the conductive particles, and then rinsed; (2) conductive particles Is dispersed in a dispersion solution of inorganic oxide fine particles, and after the inorganic fine particles are adsorbed on the surface of the conductive particles, a rinsing process is performed, so that the surface is insulated with a polymer electrolyte and inorganic oxide fine particles laminated. Fine particles coated with a coating can be produced.
Such a method is called an alternating lamination method (Layer-by-Layer assembly). The alternate lamination method is described in G.H. This is a method of forming an organic thin film published in 1992 by Decher et al. (Thin Solid Films, 210/211, p831 (1992)). In this method, a polycation adsorbed on a substrate by electrostatic attraction by alternately immersing the base material in an aqueous solution of a polymer electrolyte having a positive charge (polycation) and a polymer electrolyte having a negative charge (polyanion). A combination of polyanions is laminated to obtain a composite film (alternate laminated film).

  In the alternating layering method, the film is grown by attracting the charge of the material formed on the substrate and the material having the opposite charge in the solution by electrostatic attraction, so that the adsorption proceeds and the charge is neutralized. When this occurs, no further adsorption occurs. Therefore, when reaching a certain saturation point, the film thickness does not increase any more. Lvov et al. Applied the alternate lamination method to fine particles and reported a method of laminating a polymer electrolyte having a charge opposite to the surface charge of the fine particles by using the fine particle dispersions of silica, titania and ceria. (Langmuir, Vol. 13, (1997) p6195-6203). By using this method, silica fine particles having a negative surface charge and polydiallyldimethylammonium chloride (PDDA) or polyethyleneimine (PEI), which are polycations having the opposite charge, are alternately laminated to form silica. It is possible to form a fine particle laminated thin film in which fine particles and a polymer electrolyte are alternately laminated.

After immersing in the dispersion of the polymer electrolyte solution or inorganic oxide fine particles, before immersing in the fine particle dispersion or polymer electrolyte solution having the opposite charge, the excess polymer electrolyte solution or inorganic oxide fine particles are rinsed only with a solvent. It is preferred to wash away the dispersion. Examples of such rinsing include water, alcohol, acetone, and the specific resistance value is usually 18 MΩ · cm or more from the viewpoint of removing an excessive polymer electrolyte solution or a dispersion of inorganic oxide fine particles. Ion-exchanged water (so-called ultrapure water) is used. Since the polymer electrolyte and inorganic oxide fine particles adsorbed on the conductive particles are electrostatically adsorbed on the surface of the conductive particles, they are not peeled off in this rinsing step. In addition, it is preferable to perform rinsing in order to prevent the polymer electrolyte or inorganic oxide fine particles not adsorbed from being brought into the solution having the opposite charge. If this is not done, cations and anions may be mixed in the solution by bringing them in, which may cause aggregation and precipitation of the polymer electrolyte and the inorganic oxide fine particles.
The polymer electrolyte solution used in the present invention is dissolved in water or a mixed solvent of water and a water-soluble organic solvent. Examples of water-soluble organic solvents that can be used include methanol, ethanol, propanol, acetone, dimethylformamide, acetonitrile, and the like.

  As the polymer electrolyte, a polymer that is ionized in an aqueous solution and has a charged functional group in the main chain or side chain can be used. In this case, a polycation is preferably used. The polycation generally has a positively charged functional group such as polyamines, such as polyethyleneimine (PEI), polyallylamine hydrochloride (PAH), polydiallyldimethylammonium chloride ( PDDA), polyvinyl pyridine (PVP), polylysine, polyacrylamide, and a copolymer containing at least one of them can be used.

Among polyelectrolytes, polyethyleneimine has a high charge density and a strong binding force. Among these polymer electrolytes, alkali metal (Li, Na, K, Rb, Cs) ions, alkaline earth metal (Ca, Sr, Ba, Ra) ions, halides are used to avoid electromigration and corrosion. Those not containing ions (fluorine ions, chloride ions, bromine ions, iodine ions) are preferred.
These polymer electrolytes are all water-soluble or soluble in a mixture of water and an organic solvent, and the molecular weight of the polymer electrolyte cannot be generally determined depending on the type of polymer electrolyte used. However, generally about 500-200,000 is preferable. In general, the concentration of the polymer electrolyte in the solution is preferably about 0.01 to 10% (weight). Further, the pH of the polymer electrolyte solution is not particularly limited.
By using this polymer electrolyte thin film, the surface of the conductive particles can be uniformly coated without defects, insulation is ensured even when the circuit electrode interval is narrow, and the connection resistance is low and good between the electrically connected electrodes. It becomes.

  In addition, the coverage of the inorganic oxide can be controlled by adjusting the type, molecular weight, and concentration of the polymer electrolyte thin film.

  Specifically, when a polymer electrolyte thin film with a high charge density such as polyethyleneimine is used, the coverage of inorganic oxide tends to be high, and a polymer electrolyte thin film with a low charge density such as polydiallyldimethylammonium chloride is used. When used, the coverage of the inorganic oxide tends to be low. Further, when the molecular weight of the polymer electrolyte is large, the coverage of the inorganic oxide tends to be high, and when the molecular weight of the polymer electrolyte is small, the coverage of the inorganic oxide tends to be low. Further, when the polymer electrolyte is used at a high concentration, the coverage of the inorganic oxide tends to be high, and when the polymer electrolyte is used at a low concentration, the coverage of the inorganic oxide tends to be low.

  When the coverage of the inorganic oxide is high, the insulation tends to be high and the conductivity tends to be poor, and when the coverage of the inorganic oxide is low, the conductivity tends to be high and the insulation is poor.

  Only one layer of the inorganic oxide may be coated. Multi-layer stacking makes it difficult to control the stacking amount.

  The coverage of the inorganic oxide is preferably in the range of 10% to 50%, and more preferably in the range of 10 to 30%. The coverage here is expressed as (surface area of insulating coating portion / total surface area) × 100% by SEM image analysis.

The insulation and conduction can be balanced by the coverage of the inorganic oxide. That is, in the experience of the inventors, when there are 20,000 particles / mm ² or more of conductive particles per area, it is necessary to set the coverage of the inorganic oxide to 40% or more. A range of 30% is sufficient. Even when conductive particles having an insulation coverage of 10 to 30% are used, the insulation is sufficient, and the conductivity is improved accordingly.

  The bond between the insulating particles and the conductive particles can be strengthened by heating and drying the insulating coated conductive particles completed as described above. The reason why the bonding force increases is, for example, chemical bonding between a functional group such as a carboxyl group on the gold surface and a hydroxyl group on the surface of the insulator particles. The temperature for heating and drying is preferably 60 to 200 ° C., and the heating time is preferably in the range of 10 to 180 minutes. When the temperature is lower than 60 ° C. or when the heating time is shorter than 10 minutes, the insulator particles are easy to peel off, and when the temperature is higher than 200 ° C. or when the heating time is longer than 180 minutes, the conductive particles are easily deformed, which is preferable. Absent.

  The insulating coated conductive particles produced as described above may have insufficient reliability due to having hydroxyl groups on the surface.

Therefore, insulation reliability increases when the surface of the insulating coated conductive particles is treated with a silicone oligomer.
[Anisotropic conductive adhesive]

  The insulating coated conductive particles and inorganic oxide particles produced as described above are dispersed in an adhesive to obtain an anisotropic conductive adhesive.

  As the adhesive used for the anisotropic conductive adhesive, a mixture of a heat-reactive resin and a curing agent is used. The adhesive preferably used is a mixture of an epoxy resin and a latent curing agent. Examples of the latent curing agent include imidazole series, hydrazide series, boron trifluoride-amine complex, sulfonium salt, amine imide, polyamine salt, dicyandiamide, and the like. In addition, an energy ray curable resin such as a mixture of a radical reactive resin and an organic peroxide or ultraviolet rays is used for the adhesive.

Examples of the epoxy resin used in the present embodiment include a bisphenol type epoxy resin derived from epichlorohydrin and bisphenol A, F, AD, etc., a skeleton containing an epoxy novolac resin derived from epichlorohydrin and phenol novolac or cresol novolac, and a naphthalene ring. Naphthalene-based epoxy resin having glycidylamine, glycidylamine, glycidyl ether, biphenyl, various epoxy compounds having two or more glycidyl groups in one molecule, or a mixture of two or more types Is possible. In particular, in the present embodiment, it is desirable to include an alicyclic hydrocarbon typified by a phenyl group. For these epoxy resins, it is preferable to use a high-purity product in which impurity ions (Na ⁺ , Cl ^−, etc.), hydrolyzable chlorine and the like are reduced to 300 ppm or less, in order to prevent electromigration.

  In order to reduce the stress after bonding or to improve the adhesiveness, butadiene rubber, acrylic rubber, styrene-butadiene rubber, silicone rubber, or the like can be mixed in the adhesive. Further, as the adhesive, a paste or film is used. In order to form a film, it is effective to blend a thermoplastic resin such as a phenoxy resin, a polyester resin, or a polyamide resin. These film-forming polymers are also effective in stress relaxation when the reactive resin is cured. In particular, when the film-forming polymer has a functional group such as a hydroxyl group, the adhesiveness is improved, which is more preferable. Moreover, it is desirable to contain the alicyclic hydrocarbon represented by the phenyl group. For film formation, an adhesive composition comprising at least an epoxy resin, acrylic rubber, and a latent curing agent is liquefied by dissolving or dispersing in an organic solvent, applied onto a peelable substrate, and below the activation temperature of the curing agent. This is done by removing the solvent.

  The solvent used at this time is preferably an aromatic hydrocarbon-based and oxygen-containing mixed solvent because the solubility of the material is improved. Specific examples include a mixed solvent of toluene and ethyl acetate or methyl ethyl ketone. In particular, in this embodiment, since the inorganic oxide particles grafted later are dispersed in the resin, the dispersion effect is large when the ratio of the aromatic hydrocarbon solvent to the whole solvent is 30% or more.

  The thickness of the anisotropic conductive adhesive is relatively determined in consideration of the particle diameter of the conductive element and the characteristics of the anisotropic conductive adhesive. The anisotropic conductive adhesive includes a conductive particle-containing layer containing conductive particles and a conductive particle-containing layer. A two-layer structure of a conductive particle-free layer that does not include conductive particles is preferable. For example, when an IC chip having a metal bump and a glass panel are connected via an anisotropic conductive adhesive, the conductive particle-free layer is disposed on the metal bump side, and the conductive particle-containing layer is disposed on the glass panel side. By doing so, the conductive particles are captured on the metal bump side with high efficiency. Accordingly, the conductive particle-containing layer is preferably as thin as possible, and the conductive particle non-containing layer is preferably thicker and more fluid than the conductive particle-containing layer. Specifically, the conductive particle-containing layer has a thickness of 3 to 15 μm, the conductive particle-free layer has a thickness of 7 to 20 μm, and the conductive particle-containing layer is 50 wt% or less of the entire anisotropic conductive adhesive film. Preferably there is.

  Moreover, it is more preferable to have a three-layer structure in which a conductive particle-free layer having a thickness of 4 μm or less is further arranged on the glass electrode side in order to enhance the adhesiveness with a glass panel or ITO. This conductive particle-free layer preferably has good fluidity.

  Here, the conductive particle non-containing layer disposed on the metal bump side preferably has good fluidity, and the conductive particle-containing layer disposed on the glass side desirably has low fluidity. Moreover, it is desirable that the conductive particles in the conductive particle-free layer are monodispersed without aggregating. The inventors have found that the following structures are preferable for achieving these problems.

  Generally, when fine particles are put in a film, the thickening effect is larger as the particle diameter is smaller. This is because the surface area per unit weight increases as the particle size decreases. For this reason, when an inorganic oxide particle is put in an anisotropic conductive adhesive film, it will become difficult for a conductive particle to move by taking out a thickening effect, and the capture rate of the conductive particle on a connection electrode will improve. In addition, the addition of fine particles also has an effect as a spacer. That is, the monodispersity of the conductive particles in the anisotropic conductive adhesive film is dramatically improved by the inclusion of the inorganic oxide particles.

  Then, when 10-50 wt% of inorganic oxide particle slurry is put into the conductive particle-containing layer, the monodispersity of the conductive particles is improved. As the inorganic oxide particle slurry, inorganic oxide particles obtained by the production method of the present embodiment may be used, and in particular, three-dimensionally crosslinked silica may be used.

  The inorganic oxide particle slurry as described above is dispersed in a large amount in the adhesive resin. As a method of dispersing, there are means such as rotating agitation, ultrasonic waves, bead mill, and wet collision after the slurry is mixed in the adhesive resin.

  In the conductive particle-containing layer, it is preferable that inorganic oxide particles having a hydrophobic surface are present in an amount of 10 wt% or more, more preferably 15 wt% or more, more preferably 20 wt% or more. It is preferable that it is present, more preferably 30 wt% or more. In this case, weight% of inorganic oxide particles = (weight of inorganic oxide particles / weight of adhesive) × 100%.

  As the inorganic oxide particles are added, the capturing rate of the conductive particles on the connection electrode and the monodispersity of the conductive particles in the anisotropic conductive adhesive film are improved. However, if the amount is excessively added, the adhesive strength tends to be lowered. Therefore, the amount of inorganic oxide particles added is preferably 40 wt% or less, and more preferably 30 wt% or less.

  That is, from the viewpoint of the capture rate of the conductive particles on the connection electrode and the monodispersity of the conductive particles, it is better that there are more inorganic oxide particles, and from the viewpoint of adhesive strength, it is better that there are fewer inorganic oxide particles. From the above viewpoint, the ideal addition amount of the inorganic oxide particles is preferably 10 wt% or more and 40 wt% or less.

  On the other hand, it is better that the conductive particle non-containing layer has higher fluidity. Therefore, it is better that there are fewer inorganic oxide particles. Specifically, it is preferably 10 wt% or less, more preferably 5 wt% or less.

The amount of the conductive particles to be put in the conductive particle-containing layer is preferably 20,000 / mm ² or more per unit area. Originally, if such conductive particles are added, it causes migration, but in this embodiment, since a large amount of fine particles are present in the conductive particle-containing layer, the insulation is improved. It is preferable that a large amount of conductive particles can be added because conductivity is increased and the number of captured conductive particles for each bump is stabilized.

  The anisotropic conductive adhesive film with a multi-layer structure that requires a conductive particle-containing layer and a conductive particle-free layer prepared as described above is bonded because a large amount of fine particles are mixed on the conductive particle-free layer side. May be insufficient. In this case, a configuration in which the conductive particle containing layer is sandwiched between the conductive particle non-containing layers is preferable. Also in this case, the conductive particle-containing layer is 50 vol% or less of the entire anisotropic conductive adhesive film, and the conductive particle non-conductive layer having an average thickness of 4 μm or less outside the conductive particle-containing layer (the side different from the conductive particle-free layer). It is preferable that a containing layer is present, and it is more preferable that a conductive particle-free layer having an average thickness of 4 μm or less exists.

  Specifically, the conductive particle-containing layer has a thickness of 3 to 15 μm, the conductive particle-free layer (1) has a thickness of 7 to 20 μm, and the conductive particle-free layer (2) has a thickness of 1 to 4 μm. Preferably, the conductive particle non-containing layer (1) is on the bump side and the conductive particle non-containing layer (2) is on the glass panel side at the time of pressure bonding. Each of these layers can be bonded together by applying to the separator and laminating.

The conductive particle non-containing layer (1) and the conductive particle non-containing layer (2) preferably have high fluidity and adhesiveness, so that the inorganic oxide particles are preferably less than 10 wt%, and preferably less than 5 wt%. Further preferred.
[Connection structure]

  An example of a method for producing a connection structure using the anisotropic conductive adhesive thus produced will be described with reference to FIG.

  FIG. 1 is a cross-sectional view of an anisotropic conductive adhesive 10 composed of three layers in which a conductive particle-containing layer 1 is sandwiched between conductive particle-free layers 2. In the conductive particle-containing layer 1, insulating coated conductive particles 5 and inorganic oxide particles 6 composed of the conductive particles 3 and the insulating coating layer 4 are dispersed. FIG. 2 is a cross-sectional view showing an embodiment of a COG mounting method using the anisotropic conductive adhesive 10. As shown in FIG. 2, the IC chip 7 and the glass substrate 9 are arranged to face each other so that the metal bumps 8 on the IC chip 7 and the electrodes 11 (ITO electrodes or IZO electrodes) on the glass substrate 9 face each other. An anisotropic conductive adhesive 10 is disposed between the IC chip 7 and the glass substrate 9. By heating and pressurizing the whole in this state, a connection structure 100 in which the IC chip 7 and the glass substrate 9 are electrically connected as shown in the sectional view of FIG. 3 is obtained. At the time of heating and pressurization, the conductive particles 3 are restrained from flowing by the inorganic oxide particles 6, and the conductive particles 3 are easily captured between the metal bumps 8 and the electrodes 11, so that high conductivity is obtained in the pressurizing direction. On the other hand, the metal bump 8 and the electrode 11 are in contact with a layer having a low content of the inorganic oxide particles 6, so that the embedding property and adhesiveness of the conductive particles 3 can be maintained. The insulation property in the non-pressurizing direction is improved as a result of an increase in the capture rate between the metal bumps 8 and the electrodes 11 and a reduction in the proportion of the conductive particles 3 flowing between the adjacent metal bumps 8. Even if the coverage of the insulating coating layer 4 existing on the surface of the conductive particles 3 is lowered, the insulation is easily secured. By reducing the coverage of the insulating coating layer 4, the conductivity is further improved.

  Hereinafter, although this embodiment is described concretely based on an example and a comparative example, this embodiment is not limited to the following examples at all.

(Conductive particles 1)
Conductive particles 1 are formed by forming a nickel layer having a thickness of 0.2 μm on the surface of crosslinked polystyrene particles having an average particle diameter of 2.8 μm by electroless plating, and further providing a palladium layer having a thickness of 0.04 μm outside the nickel. Produced.

(Insulation coated conductive particles 1)
Next, 8 mmol of mercaptoacetic acid was dissolved in 200 ml of methanol to prepare a reaction solution. Next, 10 g of the conductive particles 1 was added to the reaction solution, and the mixture was stirred at room temperature for 2 hours with a three-one motor and a stirring blade having a diameter of 45 mm. After washing with methanol, conductive particles having a carboxyl group on the surface were obtained by filtering the conductive particles with a φ3 μm membrane filter (manufactured by Nihon Millipore).

Next, a 30% polyethyleneimine aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) having a molecular weight of 70,000 was diluted with ultrapure water to obtain a 0.3 wt% polyethyleneimine aqueous solution. 10 g of the conductive particles having a carboxyl group were added to a 0.3% by weight polyethyleneimine aqueous solution and stirred at room temperature for 15 minutes. Next, the conductive particles were filtered through a φ3 μm membrane filter (manufactured by Nihon Millipore), put in 200 g of ultrapure water, and stirred at room temperature for 5 minutes. Further, the conductive particles were filtered through a membrane filter of φ3 μm (manufactured by Nihon Millipore), and washed with 200 g of ultrapure water on the membrane filter to remove unimsorbed polyethyleneimine.
Next, the conductive particles treated with polyethyleneimine are immersed in pure water, and a colloidal silica dispersion (mass concentration 20%, manufactured by Fuso Chemical Industries, product name Quatron PL-13, average particle size 130 nm) is diluted with ultrapure water. By dripping the obtained liquid, insulating coated conductive particles having a silica coverage of 30% were produced. The coverage was adjusted by the dropping amount.

  Next, the conductive particles were filtered through a φ3 μm membrane filter (manufactured by Nihon Millipore), put in 200 g of ultrapure water, and stirred at room temperature for 5 minutes. Further, the conductive particles were filtered through a membrane filter of φ3 μm (manufactured by Nihon Millipore) and washed twice with 200 g of ultrapure water on the membrane filter to remove unadsorbed silica. Thereafter, the silica surface was hydrophobized by dipping in a silicone solution. Thereafter, drying was performed at 80 ° C. for 30 minutes, and the insulating coated conductive particles 1 were produced by heating and drying at 120 ° C. for 1 hour.

(Silicone oligomer 1)
A solution was prepared by blending 50 g of triethoxyphenylsilane with 10 g of methanol. While stirring this, a solution of 6 g of distilled water and 0.5 g of acetic acid was added, and the mixture was heated at 80 ° C. for a certain time to perform hydrolysis and polycondensation reaction. Once cooled to 0 ° C., 6 g of tetraethoxysilane was added dropwise and stirred at room temperature for 2 hours to obtain a silicone polymer containing a phenyl group in the siloxane skeleton and having a trifunctional terminal. The molecular weight of the obtained polymer was 1100 (weight average molecular weight measurement by GPC). Methanol was added to the obtained silicone oligomer solution to prepare a treatment liquid having a solid content of 20% by weight. It was 620 degreeC when the thermal decomposition temperature of the obtained silicone oligomer was measured with the differential calorimeter.

(Silicone oligomer 2)
A solution was prepared by blending 30 g of triethoxyphenylsilane and 5 g of diethoxydiphenylsilane with 10 g of methanol. While stirring this, a solution of 8 g of distilled water and 0.5 g of acetic acid was added, and the mixture was heated at 50 ° C. for a certain time to perform hydrolysis and polycondensation reaction. Once cooled to 0 ° C., 6 g of tetraethoxysilane was added dropwise and stirred at room temperature for 2 hours to obtain a silicone polymer containing a phenyl group in the siloxane skeleton and having a trifunctional terminal. The molecular weight of the obtained polymer was 1000 (weight average molecular weight measurement by GPC). Methanol was added to the obtained silicone oligomer solution to prepare a treatment liquid having a solid content of 20% by weight. It was 600 degreeC when the thermal decomposition temperature of the obtained silicone oligomer was measured with the differential calorimeter.

(Silicone oligomer 3)
A solution was prepared by blending 40 g of diphenyldimethoxysilane and 20 g of dimethyldimethoxysilane with 10 g of methanol. While stirring this, a solution of 6 g of distilled water and 0.5 g of acetic acid was added, and the mixture was heated at 50 ° C. for a certain time to perform hydrolysis and polycondensation reaction. Once cooled to 0 ° C., 8 g of trimethoxymethylsilane was added dropwise and stirred at room temperature for a certain period of time to obtain a silicone polymer containing a phenyl group in the siloxane skeleton and having a bifunctional end. The molecular weight of the obtained silicone polymer was 800 (weight average molecular weight measurement by GPC). Methanol was added to the obtained silicone oligomer solution to prepare a treatment liquid having a solid content of 20% by weight. It was 550 degreeC when the thermal decomposition temperature of the obtained silicone oligomer was measured with the differential calorimeter.

(Silicone oligomer 4)
To a glass flask equipped with a stirrer, a condenser and a thermometer, 0.60 g of acetic acid and 17.8 g of distilled water were added to a solution prepared by mixing 20 g of dimethoxydimethylsilane, 25 g of tetramethoxysilane, and 105 g of methanol. The mixture was stirred for a time to synthesize a silicone oligomer having a molecular weight of 2500 (measurement of weight average molecular weight by GPC, the same definition hereinafter). The obtained silicone oligomer has a methoxy group or a silanol group as a terminal functional group that reacts with a hydroxyl group. Methanol was added to the obtained silicone oligomer solution to prepare a treatment liquid having a solid content of 20% by weight. It was 410 degreeC when the thermal decomposition temperature of the obtained silicone oligomer was measured with the differential calorimeter.

(Silicone oligomer 5)
To a glass flask equipped with a stirrer, a condenser and a thermometer, 0.60 g of acetic acid and 17.8 g of distilled water are added to a solution prepared by mixing 20 g of dimethoxydimethylsilane, 25 g of tetramethoxysilane, and 105 g of methanol, and constant at 70 ° C. The mixture was stirred for a time to synthesize a silicone oligomer having a molecular weight of 5800 (weight average molecular weight measurement by GPC, hereinafter the same definition). The obtained silicone oligomer has a methoxy group or a silanol group as a terminal functional group that reacts with a hydroxyl group. Methanol was added to the obtained silicone oligomer solution to prepare a treatment liquid having a solid content of 20% by weight. It was 420 degreeC when the thermal decomposition temperature of the obtained silicone oligomer was measured with the differential calorimeter.

(Silicone oligomer 6)
To a glass flask equipped with a stirrer, a condenser and a thermometer, 5 g of activated clay and 4.8 g of distilled water were added to a solution containing 118 g of 3-glycidoxypropyltrimethoxysilane and 5.9 g of methanol, and 75 ° C. And a silicone oligomer having a molecular weight of 1300 (weight average molecular weight measurement by GPC) was synthesized. The obtained silicone oligomer has a methoxy group or a silanol group as a terminal functional group that reacts with a hydroxyl group. Methanol was added to the obtained silicone oligomer solution to prepare a treatment liquid having a solid content of 20% by weight. It was 380 degreeC when the thermal decomposition temperature of the obtained silicone oligomer was measured with the differential calorimeter.

(Silicone oligomer 7)
To a glass flask equipped with a stirrer, a condenser and a thermometer, 3 g of activated clay and 6.3 g of distilled water were added to a solution containing 110 g of 3-glycidoxypropylmethyldimethoxysilane and 2.0 g of methanol, and 75 ° C. And a silicone oligomer having a molecular weight of 700 (weight average molecular weight measurement by GPC) was synthesized. The obtained silicone oligomer has a methoxy group or a silanol group as a terminal functional group that reacts with a hydroxyl group. Methanol was added to the obtained silicone oligomer solution to prepare a treatment liquid having a solid content of 20% by weight. It was 370 degreeC when the thermal decomposition temperature of the obtained silicone oligomer was measured with the differential calorimeter.

(Silica nanoparticles 1)
10 g of untreated 12 nm silica nanoparticles AEROSIL200 (manufactured by Nippon Aerosil Co., Ltd.) were placed in a glass flask equipped with a stirrer, a condenser and a thermometer, and stirred under a nitrogen atmosphere. While stirring, 10 g of silicone oligomer 1 was gradually added dropwise, followed by stirring at 200 ° C. for 24 hours to prepare silica nanoparticles having a particle diameter of 12 nm whose silica surface was covered with silicone. Thereafter, the taken-out particles were heated to 1000 ° C. with a micro thermogravimetric measuring apparatus, and the resin content was measured by weight change. As a result, a weight loss of 8.8 wt% was confirmed.

(Silica nanoparticles 2)
10 g of untreated 12 nm silica nanoparticles AEROSIL200 (manufactured by Nippon Aerosil Co., Ltd.) were placed in a glass flask equipped with a stirrer, a condenser and a thermometer, and stirred under a nitrogen atmosphere. While stirring, 10 g of silicone oligomer 2 was gradually added dropwise, followed by stirring at 200 ° C. for 24 hours to prepare silica nanoparticles having a particle diameter of 12 nm with the silica surface covered with silicone. Thereafter, the taken-out particles were heated to 1000 ° C. with a micro thermogravimetric measuring device, and the resin content was measured by weight change. As a result, a weight loss of 7.6 wt% was confirmed.

(Silica nanoparticles 3)
10 g of untreated 12 nm silica nanoparticles AEROSIL200 (manufactured by Nippon Aerosil Co., Ltd.) were placed in a glass flask equipped with a stirrer, a condenser and a thermometer, and stirred under a nitrogen atmosphere. While stirring, 10 g of the silicone oligomer 3 was gradually added dropwise, followed by stirring at 200 ° C. for 24 hours to prepare silica nanoparticles having a particle diameter of 12 nm whose silica surface was covered with silicone. Thereafter, the taken-out particles were heated to 1000 ° C. with a micro thermogravimetric measuring device, and the resin content was measured by weight change. As a result, a weight loss of 7.8 wt% was confirmed.

(Silica nanoparticles 4)
10 g of untreated 12 nm silica nanoparticles AEROSIL200 (manufactured by Nippon Aerosil Co., Ltd.) were placed in a glass flask equipped with a stirrer, a condenser and a thermometer, and stirred under a nitrogen atmosphere. While stirring, 10 g of silicone oligomer 4 was gradually added dropwise, followed by stirring at 200 ° C. for 24 hours to prepare silica nanoparticles having a particle diameter of 12 nm whose silica surface was covered with silicone. Thereafter, the taken-out particles were heated to 1000 ° C. with a micro thermogravimetric measuring device, and the resin content was measured by weight change. As a result, a weight loss of 7.6 wt% was confirmed.

(Silica nanoparticles 5)
10 g of untreated 12 nm silica nanoparticles AEROSIL200 (manufactured by Nippon Aerosil Co., Ltd.) were placed in a glass flask equipped with a stirrer, a condenser and a thermometer, and stirred under a nitrogen atmosphere. While stirring, 10 g of the silicone oligomer 5 was gradually added dropwise, followed by stirring at 200 ° C. for 24 hours to prepare silica nanoparticles having a particle diameter of 12 nm and having a silica surface covered with silicone. Thereafter, the taken-out particles were heated to 1000 ° C. with a micro thermogravimetric measuring apparatus, and the resin content was measured by weight change. As a result, a weight reduction of 4.5 wt% was confirmed.

(Silica nanoparticles 6)
10 g of treated 12 nm nanoparticles AEROSIL200 (manufactured by Nippon Aerosil Co., Ltd.) was placed in a glass flask equipped with a stirrer, a condenser and a thermometer, and stirred in a nitrogen atmosphere. While stirring, 10 g of silicone oligomer 6 was gradually added dropwise, and after the addition, the mixture was stirred at 200 ° C. for 24 hours to produce silica nanoparticles having a particle diameter of 12 nm whose silica surface was covered with silicone. Thereafter, the taken-out particles were heated to 1000 ° C. with a micro thermogravimetric measuring device, and the resin content was measured by weight change. As a result, a weight loss of 9.9 wt% was confirmed.

(Silica nanoparticles 7)
10 g of untreated 12 nm silica nanoparticles AEROSIL200 (manufactured by Nippon Aerosil Co., Ltd.) were placed in a glass flask equipped with a stirrer, a condenser and a thermometer, and stirred under a nitrogen atmosphere. While stirring, 10 g of silicone oligomer 7 was gradually added dropwise, and after the addition, the mixture was stirred at 200 ° C. for 24 hours to produce silica nanoparticles having a particle diameter of 12 nm whose silica surface was covered with silicone. Thereafter, the taken-out particles were heated to 1000 ° C. with a micro thermogravimetric measuring device, and the resin content was measured by weight change. As a result, a weight loss of 9.7 wt% was confirmed.

(Silica nanoparticles 8)
10 g of untreated 12 nm silica nanoparticles AEROSIL200 (manufactured by Nippon Aerosil Co., Ltd.) were placed in a glass flask equipped with a stirrer, a condenser and a thermometer, and stirred under a nitrogen atmosphere. While stirring, 10 g of phenyltrimethoxysilane was gradually added dropwise, followed by stirring at 200 ° C. for 24 hours to prepare silica nanoparticles having a particle diameter of 12 nm with the silica surface covered with a silane coupling agent. Thereafter, the taken-out particles were heated to 1000 ° C. with a micro thermogravimetric measuring device, and the resin content was measured by weight change. As a result, a weight loss of 6.7 wt% was confirmed.

(Silica slurry 1)
The silica nanoparticles 1 were dispersed in a solvent in which ethyl acetate and toluene were mixed at a weight ratio of 1: 1 so that the silica nanoparticles 1 would be 20 wt%, and the silica nanoparticles 1 were added to prepare a highly viscous slurry. Next, after lowering the viscosity with a self-revolving mixer, using a wet crusher Nanomizer NM2000-AR (trade name, manufactured by Yoshida Kikai Kogyo Co., Ltd.), crushing is performed three times under the condition of a supply pressure of 150 MPa, and the low viscosity Turned into.

(Silica slurry 2)
A silica slurry 2 was produced under the same conditions as the silica slurry 1 except that the silica nanoparticles 2 were used instead of the silica nanoparticles 1.

(Silica slurry 3)
A silica slurry 3 was produced under the same conditions as the silica slurry 1 except that the silica nanoparticles 3 were used instead of the silica nanoparticles 1.

(Silica slurry 4)
A silica slurry 4 was produced under the same conditions as the silica slurry 1 except that the silica nanoparticles 4 were used instead of the silica nanoparticles 1.

(Silica slurry 5)
A silica slurry 5 was produced under the same conditions as the silica slurry 1 except that the silica nanoparticles 5 were used instead of the silica nanoparticles 1.

(Silica slurry 6)
A silica slurry 6 was produced under the same conditions as the silica slurry 1 except that the silica nanoparticles 6 were used instead of the silica nanoparticles 1.

(Silica slurry 7)
A silica slurry 7 was produced under the same conditions as the silica slurry 1 except that the silica nanoparticles 7 were used instead of the silica nanoparticles 1.

(Silica slurry 8)
A silica slurry 8 was produced under the same conditions as the silica slurry 1 except that the silica nanoparticles 8 were used instead of the silica nanoparticles 1.

(Silica slurry 9)
Silica slurry 9 was produced under the same conditions as silica slurry 1 except that commercially available octylsilane-coated silica nanoparticles R202 (trade name, manufactured by Nippon Aerosil Co., Ltd.) were used instead of silica nanoparticles 1.

(Silica slurry 10)
Silica slurry 10 was produced under the same conditions as silica slurry 1 except that commercially available octyl-coated silica nanoparticles R805 (trade name, manufactured by Nippon Aerosil Co., Ltd.) were used instead of silica nanoparticles 1.

[Example 1 (Evaluation Example 1)]
Preparation of adhesive solution: copolymer of 100 g of phenoxy resin (trade name, PKHC, manufactured by Union Carbide) and acrylic rubber (40 parts of butyl acrylate, 30 parts of ethyl acrylate, 30 parts of acrylonitrile, 3 parts of glycidyl methacrylate, molecular weight: 85 Ten thousand) was dissolved in 300 g of a solvent in which ethyl acetate and toluene were mixed at a weight ratio of 1: 1 to obtain a 30 wt% solution. Next, 300 g of a liquid epoxy (Eboxy equivalent 185, manufactured by Asahi Kasei Epoxy Co., Ltd., NovaCure HX-3941) containing a microcapsule-type latent curing agent was added to this solution and stirred to prepare an adhesive solution 1. Next, the silica slurry 1 immediately after production was added to the adhesive solution 1 so that the silica solid content was 30 wt% with respect to the adhesive solid content.

  On the other hand, 4 g of the insulating coated conductive particles produced by the above-described method was ultrasonically dispersed in 10 g of a solvent in which ethyl acetate and toluene were mixed at a weight ratio of 1: 1 to obtain a particle dispersion. The condition of ultrasonic dispersion was that a sample immersed in a beaker was placed in an ultrasonic bath of 38 kHZ400W20L (test apparatus: US 107 Fujimoto Kagaku brand name) and stirred for 1 minute.

The particle dispersion is dispersed in the adhesive solution 1, and this solution is applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) with a roll coater, dried at 90 ° C. for 10 minutes, and an anisotropic conductive adhesive having a thickness of 10 μm. Film A was produced. This anisotropic conductive adhesive film A contained 30,000 particles / mm ² of insulating coated conductive particles per unit area.

  Next, the adhesive solution 1 was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) with a roll coater and dried at 90 ° C. for 10 minutes to prepare an anisotropic conductive adhesive film B having a thickness of 3 μm.

  Next, the adhesive solution 1 was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) with a roll coater and dried at 90 ° C. for 10 minutes to prepare an anisotropic conductive adhesive film C having a thickness of 10 μm.

Next, each layer was laminated in the order of the anisotropic conductive adhesive film B → the anisotropic conductive adhesive film A → the anisotropic conductive adhesive film C to prepare an anisotropic conductive adhesive film D consisting of three layers.
Next, using the produced anisotropic conductive adhesive film D, a chip (1.7 × 1.7 mm, thickness: 0) with gold bumps (area: 30 × 90 μm, space 8 μm, height: 15 μm, bump number 362) is used. 0.5 μm) and a glass substrate with a circuit (thickness: 0.7 mm) were connected as shown below.

After the anisotropic conductive adhesive film D was attached to a glass substrate with a circuit at 80 ° C. and 0.98 MPa (10 kgf / cm ² ), the separator was peeled off, and the bumps of the chip and the glass substrate with a circuit were aligned.

  Next, the main connection was performed by heating and pressing from above the chip under the conditions of 190 ° C., 40 g / bump, and 10 seconds.

[Example 2 (Evaluation Example 2)]
A connection sample was prepared in the same manner as in Evaluation Example 1 except that silica slurry 2 was used instead of silica slurry 1.

[Example 3 (Evaluation Example 3)]
A connection sample was prepared in the same manner as in Evaluation Example 1 except that silica slurry 3 was used instead of silica slurry 1.

[Example 4 (Evaluation Example 4)]
A connection sample was prepared in the same manner as in Evaluation Example 1 except that silica slurry 4 was used instead of silica slurry 1.

[Example 5 (Evaluation Example 5)]
A connection sample was prepared in the same manner as in Evaluation Example 1 except that the silica slurry 5 was used instead of the silica slurry 1.

[Example 6 (Evaluation Example 6)]
A connection sample was prepared in the same manner as in Evaluation Example 1 except that silica slurry 6 was used instead of silica slurry 1.

[Comparative Example 1 (Evaluation Example 7)]
A connection sample was prepared in the same manner as in Evaluation Example 1 except that silica slurry 7 was used instead of silica slurry 1.

[Comparative Example 2 (Evaluation Example 8)]
A connection sample was prepared in the same manner as in Evaluation Example 1, except that silica slurry 8 was used instead of silica slurry 1.

[Comparative Example 3 (Evaluation Example 9)]
A connection sample was prepared in the same manner as in Evaluation Example 1 except that silica slurry 9 was used instead of silica slurry 1.

[Comparative Example 4 (Evaluation Example 10)]
A connection sample was prepared in the same manner as in Evaluation Example 1 except that silica slurry 10 was used instead of silica slurry 1.

[Example 7 (Evaluation Example 11)]
A connection sample was prepared in the same manner as in Evaluation Example 1 except that a film was prepared after leaving the silica slurry 1 for 24 hours.

[Example 8 (Evaluation Example 12)]
A connection sample was prepared in the same manner as in Evaluation Example 2 except that a film was prepared after leaving the silica slurry 2 for 24 hours.

[Example 9 (Evaluation Example 13)]
A connection sample was prepared in the same manner as in Evaluation Example 3 except that a film was prepared after leaving the silica slurry 3 for 24 hours.

[Example 10 (Evaluation Example 14)]
A connection sample was prepared in the same manner as in Evaluation Example 4 except that a film was prepared after leaving the silica slurry 4 for 24 hours.

[Example 11 (Evaluation Example 15)]
A connection sample was prepared in the same manner as in Evaluation Example 5 except that a film was prepared after leaving the silica slurry 5 for 24 hours.

[Example 12 (Evaluation Example 16)]
A connection sample was prepared in the same manner as in Evaluation Example 6 except that a film was prepared after leaving the silica slurry 6 for 24 hours.

[Comparative Example 5 (Evaluation Example 17)]
A connection sample was prepared in the same manner as in Evaluation Example 7 except that a film was prepared after leaving the silica slurry 7 for 24 hours.

[Comparative Example 6 (Evaluation Example 18)]
A connection sample was prepared in the same manner as in Evaluation Example 8 except that a film was prepared after leaving the silica slurry 8 for 24 hours.

[Comparative Example 7 (Evaluation Example 19)]
A connection sample was prepared in the same manner as in Evaluation Example 9 except that a film was prepared after leaving the silica slurry 9 for 24 hours.

[Comparative Example 8 (Evaluation Example 20)]
A connection sample was prepared in the same manner as in Evaluation Example 10 except that a film was prepared after leaving the silica slurry 10 for 24 hours.

[Comparative Example 9 (Evaluation Example 21)]
A connection sample was prepared in the same manner as in Evaluation Example 1 except that a film was prepared without adding silica slurry.

(Insulation resistance test and conduction resistance test)
The insulation resistance test and conduction resistance test of the samples prepared in Examples 1 to 12 and Comparative Examples 1 to 9 were performed. It is important that the anisotropic conductive adhesive film has high insulation resistance between the chip electrodes and low conduction resistance between the chip electrode / glass electrode. 20 samples of the insulation resistance between the chip electrodes were measured. The insulation resistance was subjected to an initial value and a migration test (left for 500 hours under the conditions of an air temperature of 60 ° C., a humidity of 90%, and 20 V applied), and the yield was calculated when the insulation resistance was greater than 10 ⁹ (Ω). Moreover, the average value of 14 samples was measured regarding the conduction | electrical_connection resistance between a chip electrode / glass electrode. The conduction resistance was measured by an initial value and a value after a moisture absorption heat test (standing for 500 hours under conditions of an air temperature of 85 ° C. and a humidity of 85%).

(Capture rate)
The capture rate was determined from the ratio of the particle density in the anisotropic conductive adhesive to the particle density on the bump. Specifically, it calculated | required with the following formula | equation. The capture rate is a desired characteristic, and the higher the rate, the better.
Capture rate (%) = average number of particles on bump (n = 100) / bump area / number of particles in anisotropic conductive adhesive per unit area × 100 (%)

(Coating appearance)
When a large amount of nanoparticles that are difficult to disperse in the film are introduced into the film, the nanoparticles become aggregates of several micron level and streaks occur during coating. Since the conductive particles are scarcely present in the portion where the streaks are generated, it causes a conduction failure. Therefore, the coating appearance of the anisotropic conductive adhesive film was evaluated.

(Silica slurry viscosity)
The viscosity of the silica slurry was measured with a vibration viscometer.

(result)
The measurement results are shown in Table 1. A to D in Table 1 means evaluation based on the following criteria.
A: Particularly good B: Good C: Insufficient characteristics D: Unusable

In Examples 1 to 6, it was confirmed that excellent characteristics were imparted to the anisotropic conductive adhesive film due to the improvement in dispersibility of the inorganic oxide particles.
For example, in the anisotropic conductive adhesive films of Examples 1 to 6, since the dispersibility is good even if the content of the inorganic oxide particles is large, the viscosity of the anisotropic conductive adhesive film is increased and the connection electrode It was possible to effectively achieve improvement in the conductive reliability by increasing the capture rate of the conductive particles. In addition, since an aromatic hydrocarbon solvent is used, the varnish and the inorganic oxide particles are familiar with each other, and coating scratches are difficult to occur.
In addition, even when the chillers of Examples 1 to 6 were allowed to stand, there was a tendency for the viscosity increase to be small as shown in Examples 7 to 12.
Furthermore, in Examples 1-3, hydrophobicity and heat resistance were improved by introducing a phenyl group into silica, and insulation reliability and moisture absorption heat resistance could be greatly improved. By using a three-dimensionally crosslinked phenyl group-containing silicone oligomer, the viscosity when the inorganic oxide particles were added to an aromatic organic solvent to form a slurry was particularly low (ie, good dispersibility).

On the other hand, in Comparative Examples 1-4, the dispersibility of the inorganic oxide particles was insufficient, and desired characteristics could not be obtained. More specifically, in Comparative Examples 1-4, the viscosity of the slurry was higher than in Examples 1-6. Moreover, when the slurry of Comparative Examples 1-4 was left to stand, the viscosity rose compared with Examples 7-12 (Comparative Examples 5-8). In addition, the chip electrode / glass electrode conductivity and the insulation between the chip electrodes were insufficient. This is considered to be due to the fact that the surface of the inorganic oxide particles is not three-dimensionally covered and there is a residual hydroxyl group (silanol) on the surface of the inorganic oxide particles.
Moreover, in the comparative example 9 which did not use an inorganic oxide particle, the result that the capture | acquisition rate of the electroconductive particle on a connection electrode was low was shown.

  As described above, according to the present invention, inorganic oxide particles having good dispersibility in an adhesive can be produced by eliminating the influence of residual silanol. Especially when used for anisotropic conductive adhesive, it makes the conductive particles difficult to move during crimping, improves the capture rate of the conductive particles on the electrode, and at the same time improves the monodispersity of the conductive particles in the anisotropic conductive adhesive film Insulation characteristics and conduction characteristics can be improved at the same time. Furthermore, the input amount of conductive particles can be suppressed. Moreover, in order to suppress the inorganic oxide particle which is a nanoparticle, the applicability | paintability of an anisotropic conductive adhesive improves.

  6 ... Inorganic oxide particles, 10 ... Anisotropic conductive adhesive.

Claims (10)

  A method for producing inorganic oxide particles, comprising a step of chemically adsorbing a three-dimensionally crosslinked silicone oligomer having a weight average molecular weight in the range of 500 to 10,000 on the surface of the inorganic oxide particles in a gas phase.   In the step, a mixed solution obtained by diluting the silicone oligomer with a solvent having a boiling point lower than the thermal decomposition temperature of the silicone oligomer is dropped on the surface of the inorganic oxide particles stirred in the gas phase, and after the dropping The inorganic oxide particles are stirred at a temperature lower than the thermal decomposition temperature of the silicone oligomer and higher than the boiling point of the solvent, and then the unreacted silicone oligomer is removed under reduced pressure and high temperature. The manufacturing method of inorganic oxide particles.   The method for producing inorganic oxide particles according to claim 2, wherein the thermal decomposition temperature of the silicone oligomer is 500 ° C or higher.   The method for producing inorganic oxide particles according to claim 2 or 3, wherein nitrogen purge is performed when the inorganic oxide particles are stirred.   The method for producing inorganic oxide particles according to any one of claims 1 to 4, wherein a graft ratio of the silicone oligomer is in a range of 4% to 100%. The inorganic oxide according to any one of claims 1 to 5, wherein the silicone oligomer contains one or more types of trifunctional (RSiO _3/2 ) or tetrafunctional (RSiO _4/2 ) siloxane units in the molecule. Particle manufacturing method. The said silicone oligomer has both a bifunctional (RSiO2 _{/ 2} ) and a tetrafunctional (RSiO4 _{/ 2} ) siloxane unit in a molecule | numerator, The inorganic as described in any one of Claims 1-5 characterized by the above-mentioned. A method for producing oxide particles. According to any one of claims 1 to 5, characterized in that it has both bifunctional _{(R 2 SiO 2/2)} and trifunctional a _{(RSiO 3/2)} siloxane units in the silicone oligomer in the molecule The manufacturing method of inorganic oxide particles.   Said R is a phenyl group, The manufacturing method of the inorganic oxide particle as described in any one of Claims 6-8 characterized by the above-mentioned.   An anisotropic conductive adhesive comprising 5 wt% or more of inorganic oxide particles produced by the method for producing inorganic oxide particles according to claim 1.

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