JP5471504B2 - Anisotropic conductive film - Google Patents

Description

  The present invention relates to an anisotropic conductive film (ACF) composed of a plurality of layers.

  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. The anisotropy here means that the anisotropic conductive adhesive is conductive in the pressurizing direction at the time of pressure bonding, and the insulating property is maintained 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. Nickel / gold plated particles have better insulation.

With the recent high definition of liquid crystal displays, gold bumps, which are circuit electrodes of liquid crystal driving ICs, are becoming narrower in pitch and area. Therefore, there is a problem that the conductive particles of the anisotropic conductive adhesive flow out between adjacent circuit electrodes and cause a short circuit. This tendency is particularly remarkable in COG mounting. If 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 exemplified in Patent Document 1 below, by forming an insulating adhesive on at least one surface of the anisotropic conductive adhesive, the bonding in COG mounting or COG mounting There are ways to prevent quality degradation. Further, as exemplified in Patent Document 2 below, there is a method of covering the entire surface of the conductive particles with an insulating film.

JP-A-8-279371 Japanese Patent No. 2779409

However, in the method of forming an insulating adhesive on one side of the circuit connection member, when the bump area is less than 3000 μm ² and the conductive particles are increased in order to obtain a stable connection resistance, the insulation between adjacent electrodes There is still room for improvement in sex. Furthermore, the method of covering the entire surface of the conductive particles with an insulating coating has a problem that the conductivity tends to be low although the insulating property is high.

In addition, despite the increase in conductive particles, there is a problem that it is difficult for the conductive particles to ride on the bumps due to the resin flow during pressure bonding. Therefore, it is important to prevent the conductive particles from moving as much as possible at the time of crimping from the viewpoints of both conductivity and insulation. In other words, in order to improve both the electrical conductivity between the circuits facing each other in the pressurizing direction and the insulation between the adjacent electrodes in the non-pressurizing direction, trapping of the conductive particles defined by the following formula (B) It is important to increase the rate.
Capture rate (%) = (Average number of conductive particles on bump / Bump area / Number of conductive particles contained per unit area of anisotropic conductive film) × 100 (B)

  In the method of covering the surface of the conductive particles with the insulating child particles, the balance between the initial insulating property and the conductivity is good. However, this measure alone cannot sufficiently prevent insulation deterioration during a long-term reliability test due to migration of conductive particles.

  The present invention has been made in view of the above-described problems of the prior art, and improves the trapping rate of conductive particles and simultaneously improves the insulation in the non-pressurization direction and the conductivity in the pressurization direction. It aims at providing an adhesive film.

In order to achieve the above object, an anisotropic conductive film according to the present invention includes an anisotropic conductive film comprising a conductive particle layer containing conductive particles and an adhesive, and an adhesive layer laminated on the conductive particle layer. The conductive particle layer further contains inorganic oxide particles, the conductive particles are contained only in the conductive particle layer, and a part of the surface of the conductive particles is covered with an insulator, so that the insulating in the conductive particles The coverage of the body is greater than 5%, the number of conductive particles per unit area of the conductive particle layer is 20,000 / mm ² or more, and the surface of the inorganic oxide particles is coated with a hydrophobic substance. The grafting rate represented by Formula A is 2.0% by mass or more, and the content of the inorganic oxide particles in the conductive particle layer is 10% by mass or more with respect to the total amount of the adhesive contained in the conductive particle layer. Yes, the content of inorganic oxide particles in the adhesive layer However, it is 0 mass% or more and less than 30 mass% with respect to the whole quantity of the adhesive agent which an adhesive layer contains.
Grafting rate = 100 × (weight of hydrophobic substance) / (weight of inorganic oxide particles) (A)

  According to the present invention, it is possible to improve the trapping rate of conductive particles and simultaneously improve the insulation in the non-pressurization direction and the conductivity in the pressurization direction. Furthermore, according to the present invention, since the capture rate is improved, the amount of conductive particles introduced into the anisotropic conductive film can be suppressed.

  In the present invention, the hydrophobic substance is preferably silicone. Thereby, the effect of this invention becomes remarkable.

  In the said invention, it is preferable that the polymerization degree of silicone is 3 or more. As a result, the surface of the inorganic oxide particles is easily coated with a desired thickness with silicone.

  In the said invention, it is preferable that an inorganic oxide particle is a silica which has a particle size of 5-30 nm. The surface treatment of the silica with a hydrophobic substance is easy to perform stably. The size of the silica after the surface treatment is easy to stabilize. As a result, the viscosity of the conductive particle layer to which the silica is added increases, and the capture rate is likely to increase.

  In the said invention, it is preferable that the coverage of the insulator in a conductive particle is 10 to 40%. Thereby, it becomes easy to achieve both insulation and conductivity.

  In the said invention, it is preferable that an adhesive layer is laminated | stacked on both surfaces of an electroconductive particle layer, and the average value of the thickness of the adhesive layer laminated | stacked on the single side | surface of the electroconductive particle layer is 4 micrometers or less. Thereby, the effect of the present invention becomes remarkable. Moreover, in the said invention, the contact bonding layer may be laminated | stacked only on the single side | surface of the electrically-conductive particle layer. Also in this case, the effect of the present invention can be achieved.

  In the said invention, it is preferable that the content rate of the inorganic oxide particle in a conductive particle layer is 40 mass% or less with respect to the whole quantity of the adhesive agent which a conductive particle layer contains. Thereby, it becomes easy to prevent poor appearance (for example, streaks) in the conductive particle layer.

  In the said invention, it is preferable that the volume of an electroconductive particle layer is 50 volume% or less with respect to the whole anisotropically conductive film. Thereby, the effect of this invention becomes remarkable.

  ADVANTAGE OF THE INVENTION According to this invention, while improving the capture | acquisition rate of electroconductive particle, the anisotropic conductive film which improves the insulation in a non-pressurization direction and the electroconductivity in a pressurization direction simultaneously can be provided.

FIG. 1 is a schematic cross-sectional view of an anisotropic conductive film, IC chip, and glass substrate according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of the conductive particle layer shown in FIG. FIG. 3 is a schematic cross-sectional view of inorganic oxide particles provided in the anisotropic conductive film according to an embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of a connection structure formed using an anisotropic conductive film according to an embodiment of the present invention.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratio in each drawing does not necessarily match the actual dimensional ratio.

(Anisotropic conductive film)
An anisotropic conductive film 12 according to this embodiment shown in FIGS. 1 and 2 includes a conductive particle layer 5 and an adhesive layer 3. The adhesive layer 3 is laminated on one surface of the conductive particle layer 5. Further, the anisotropic conductive film 12 may include an adhesive layer 6 laminated on the other surface of the conductive particle layer 5.

  The conductive particle layer 5 contains conductive particles 10, inorganic oxide particles 9, and an adhesive 22. A part of the surface of the conductive particles 10 is covered with an insulator 11. The inorganic oxide particles 9 have a hydrophobic surface. The conductive particles 10 and the inorganic oxide particles 9 are each uniformly dispersed in the adhesive 22 of the conductive particle layer 5. The adhesive layer 3 and the adhesive layer 6 each contain an adhesive and do not contain the conductive particles 10.

  By connecting the IC chip 1 and the glass substrate 8 through the anisotropic conductive film 12 by the following procedure, the connection structure 42 shown in FIG. 4 is formed.

  As shown in FIG. 1, the anisotropic conductive film 12 is disposed between the IC chip 1 and the glass substrate 8. Of the surface of the IC chip 1, the surface on which the metal bumps 2 are formed is opposed to the adhesive layer 3. The surface of the glass substrate 8 on which the electrode 7 is formed is opposed to the adhesive layer 6. The electrode 7 is made of ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide). The metal bump 2 included in the IC chip is opposed to the electrode 7 included in the glass substrate 8.

  With the anisotropic conductive film 12, the IC chip 1 and the glass substrate 8 arranged as described above, the IC chip 1 and the glass substrate 8 are pressed and laminated while being heated. Thereby, the connection structure 42 of FIG. 4 is completed. The metal bumps 2 of the IC chip 1 and the electrodes 7 of the glass substrate 8 are electrically connected through the conductive particles 10.

  In order to improve the adhesiveness between the IC chip 1 and the glass substrate 8, it is desirable that the fluidity at the time of pressure bonding of the adhesive layer 3 disposed on the metal bump 2 side is desirable. Moreover, in order to improve the adhesiveness between the IC chip 1 and the glass substrate 8, it is desirable that the fluidity at the time of pressure bonding of the adhesive layer 6 disposed on the glass substrate 8 side is good. Furthermore, in order to improve the capture rate of the conductive particles 10 and simultaneously improve the insulation in the non-pressurization direction and the conductivity in the pressurization direction, it is desirable that the viscosity of the conductive particle layer 5 at the time of pressure bonding is high. Moreover, it is desirable that the conductive particles 10 in the conductive particle layer 5 at the time of pressure bonding are not dispersed but monodispersed. The present embodiment has been found by the present inventors to achieve these requirements.

  In this embodiment, since the conductive particle layer 5 contains the inorganic compound particles 9, the viscosity of the conductive particle layer 5 at the time of heating is increased as compared with the adhesive layer 3 and the adhesive layer 6. This thickening effect makes it difficult for the conductive particles 10 to move when the IC chip 1 and the glass substrate 8 are pressure-bonded, thereby improving the capture rate. Moreover, the inorganic compound particle 9 exhibits the effect as a spacer by making the conductive particle layer 5 contain the inorganic compound particle 9. That is, in this embodiment, the monodispersity of the conductive particles 10 in the conductive particle layer 5 is dramatically improved as compared with the conventional anisotropic conductive film in which the inorganic compound particles are not added to the conductive particle layer.

  In the present embodiment, the flow of the conductive particles 10 in the heated conductive particle layer 5 is suppressed by the inorganic oxide particles 9 when the IC chip 1 and the glass substrate 8 are pressed. As a result, the conductive particles 10 are easily captured on the metal bumps 2, and the conductivity in the vertical direction (pressure direction) is increased. Since the ratio of the conductive particles 10 flowing out between the metal bumps 2 is reduced by improving the capture rate, the insulation in the lateral direction (non-pressurizing direction) is improved. Therefore, even when the coverage of the insulator 11 on the surface of the conductive particles 10 is low, it is easy to ensure the insulation in the lateral direction. Lowering the coverage further improves the longitudinal conductivity. The adhesive layer 3 or 6 having a lower content of inorganic oxide particles 9 than the conductive particle layer 5 is in contact with the metal bumps 2 and the electrodes 7. Therefore, embedding property and adhesiveness can be maintained.

The number of conductive particles 10 present per unit area of the conductive particle layer 5 is 20,000 / mm ² or more. The unit area is a unit area on the surface of the conductive particle layer 5 facing the IC chip 1 or the glass substrate 8. When the conductive particle layer 5 contains a large amount of the conductive particles 10, the conductivity in the pressurizing direction is increased, and the number of conductive particles captured between the metal bumps 2 and the electrodes 7 is also stabilized. When the number of conductive particles per unit area of the conductive particle layer not containing inorganic compound particles is 20,000 / mm ² or more, migration tends to occur. However, in this embodiment, since a large amount of inorganic compound particles 9 are present in the conductive particle layer 5, migration is prevented, and insulation in the non-pressurizing direction is improved.

  When the anisotropic conductive film 12 does not include the adhesive layer 6 and is composed of two layers of the conductive particle layer 5 and the adhesive layer 3, the adhesive layer 3 is disposed on the IC chip 1 side, and the conductive particle layer 5 is disposed on the glass substrate. It is preferable to arrange on the 8 side. Thereby, the conductive particles 10 are captured on the metal bump 2 side with high efficiency. For this purpose, the conductive particle layer 5 is preferably as thin as possible. The adhesive layer 3 is preferably thicker than the conductive particle layer 5 and has higher fluidity.

  Since a large amount of inorganic oxide particles 9 are mixed in the conductive particle layer 5, the fluidity of the conductive particle layer 5 is lower than that of the adhesive layer 3, and the adhesiveness may be insufficient. Therefore, in order to reinforce the adhesiveness between the glass substrate 8 or the electrode 7 (ITO) and the anisotropic conductive film, as described above, the adhesive layer is formed on one surface of the conductive particle layer 5 opposite to the adhesive layer 3. 6 are preferably laminated. That is, it is preferable that the anisotropic conductive film 12 is composed of the conductive particle layer 5 and the three layers of the adhesive layer 3 and the adhesive layer 6 laminated on both surfaces thereof. The adhesive layer 6 is preferably disposed on the glass substrate 8 side in order to adhere to the glass substrate 8 and the electrode 7 (ITO). The fluidity of the adhesive layer 6 is preferably higher than that of the conductive particle layer 5.

  The total thickness of the anisotropic conductive film 12 is relatively determined in consideration of the particle size of the conductive particles 10 and the characteristics of the anisotropic conductive adhesive. The average thickness of the conductive particle layer 5 may be 3 μm or more and 15 μm or less. The average thickness of the adhesive layer 3 facing the IC chip 1 may be 7 μm or more and 20 μm or less. The average thickness of the adhesive layer 6 facing the glass substrate 8 may be 1 μm or more and 4 μm or less.

  The volume of the conductive particle layer 5 is preferably larger than (100/3) volume% with respect to the entire anisotropic conductive film 12. This significantly improves the capture rate. The volume of the conductive particle layer 5 is preferably 50% by volume or less with respect to the entire anisotropic conductive film 12. Thereby, a capture rate, insulation, and electrical conductivity improve remarkably.

The content (% by mass) of the inorganic oxide particles 9 in the conductive particle layer 5 is defined by the following formula (C).
Content ratio of the inorganic oxide particles 9 in the conductive particle layer 5 = {(total mass of the inorganic oxide particles 9 included in the conductive particle layer 5) / (total mass of the adhesive 22 included in the conductive particle layer 5)} × 100 ·・ ・ (C)

  The content of the inorganic oxide particles 9 in the conductive particle layer 5 is 10% by mass or more. The content of the inorganic oxide particles 9 in the conductive particle layer 5 is preferably 15% by mass or more, more preferably 20% by mass or more, and most preferably 30% by mass or more. The content of the inorganic oxide particles 9 in the conductive particle layer 5 is preferably 40% by mass or less, and more preferably 30% by mass or less.

  The more the inorganic oxide particles 9 are added to the conductive particle layer 5, the better the capture rate of the conductive particles 10 and the monodispersity of the conductive particles 10 in the film. However, if the inorganic oxide particles 9 are added too much, the adhesive strength tends to decrease. That is, in order to improve the capture rate and monodispersity of the conductive particles 10, the more inorganic oxide particles 9 are better, and in order to improve the adhesive strength, the fewer inorganic oxide particles 9 are better. From the above viewpoint, the addition amount of the inorganic oxide particles 9 in the conductive particle layer 5 is preferably within the above numerical range.

The content (% by mass) of the inorganic oxide particles 9 in the adhesive layer 3 is defined by the following formula (D).
Content of inorganic oxide particles 9 in adhesive layer 3 = {(total mass of inorganic oxide particles 9 included in adhesive layer 3) / (total mass of adhesive included in adhesive layer 3)} × 100 (D )

The content of the inorganic oxide particles 9 in the adhesive layer 3 is 0% by mass or more and less than 30% by mass. The content of the inorganic oxide particles 9 in the adhesive layer 3 is preferably less than 10% by mass, and more preferably less than 5% by mass. When the content rate of the inorganic oxide particles 9 in the adhesive layer 3 is too high, the fluidity of the adhesive layer 3 tends to decrease, and the capture rate of the conductive particles 10 tends to decrease. The fluidity of the adhesive layer 3 is high, and the higher the adhesiveness, the better. Therefore, the smaller the number of inorganic oxide particles 9 contained in the adhesive layer 3, the better. The adhesive layer 3 may not contain the inorganic oxide particles 9. The content of the inorganic oxide particles 9 in the adhesive layer 6 is the same as that of the adhesive layer 3.

(Inorganic oxide particles)
As shown in FIG. 3, the surface of the inorganic oxide particles 9 is covered with a hydrophobic substance 32. The surface of the inorganic oxide particles not covered with the hydrophobic substance is covered with a hydroxyl group and is hydrophilic. When such hydrophilic inorganic oxide particles are put into a varnish which is a raw material of the conductive particle layer, they are aggregated, so it is difficult to add a certain amount or more of the inorganic oxide particles to the conductive particle layer. . Therefore, it is necessary to make the surface of the inorganic oxide particles hydrophobic. In addition, the use of hydrophilic inorganic oxide particles becomes a factor in forming scratches on the conductive particle layer when the conductive particle layer is formed by coating.

  In order to impart hydrophobicity to the surface of the inorganic oxide particle, it is desirable to treat the inorganic oxide particle with a compound having both a functional group that easily reacts with a hydroxyl group on the surface of the inorganic oxide particle and a hydrophobic functional group. As such a compound, a silane coupling agent and silicone are preferable. That is, as the hydrophobic substance that covers the surface of the inorganic oxide particles, a silane compound or a silicone compound is preferable. However, since the molecular weight of the silane compound is low, it is difficult to uniformly form a film made of a hydrophobic silane compound on the inorganic oxide particles. Therefore, when a coating agent having a molecular weight larger than that of the silane compound is used, it becomes easy to form a uniform hydrophobic film on the inorganic oxide particles. As the treatment agent having a molecular weight larger than that of the silane compound, a silicone compound is preferable. Of the silicone compounds, silicone oligomers are particularly preferred. Although it is difficult to three-dimensionally attach the silane coupling agent to the inorganic oxide particles, it is easy to three-dimensionally bond the silicone oligomer to the surface of the inorganic oxide particles. When the coating amount is the same, the effect of the present invention is more remarkable when the silicone oligomer is used as the coating agent than the silane coupling agent.

As the silicone oligomer, those having a three-dimensional condensation reaction in advance and having both a functional group that reacts with an inorganic material such as silica and a hydrophobic functional group are preferable. The silicone oligomer preferably contains at least one kind selected from a bifunctional siloxane unit (R ₂ SiO _2/2 ), a trifunctional siloxane unit (RSiO _3/2 ), and a tetrafunctional siloxane unit (SiO _4/2 ). . In the above chemical formula, 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, an aryl group having 6 to 12 carbon atoms such as a phenyl group, or a vinyl group. . The plurality of R groups contained in the silicone oligomer may be the same as or different from each other.

The bifunctional siloxane unit (R ₂ SiO _2/2 ) is represented by the following chemical structural formula (1). The trifunctional siloxane unit (RSiO _3/2 ) is represented by the following chemical structural formula (2). The tetrafunctional siloxane unit (SiO _4/2 ) is represented by the following chemical structural formula (3).

  The silicone oligomer preferably has at least one of a trifunctional siloxane unit and a tetrafunctional siloxane unit. Such a silicone oligomer is previously three-dimensionally crosslinked. Specific examples of the silicone oligomer include those composed only of trifunctional siloxane units, those composed only of tetrafunctional siloxane units, those composed of bifunctional siloxane units and trifunctional siloxane units, and bifunctional siloxane units and 4 Examples thereof include those composed of functional siloxane units, those composed of trifunctional siloxane units and tetrafunctional siloxane units, and those composed of bifunctional siloxane units, trifunctional siloxane units and tetrafunctional siloxane units. Moreover, it is preferable that the ratio of a tetrafunctional siloxane unit is 15 mol% or more in all the siloxane units which a silicone oligomer has, and it is more preferable that it is 20-60 mol%.

  The degree of polymerization of the silicone oligomer is preferably 3 to 90, and more preferably 5 to 80. The degree of polymerization is a converted value from the weight average molecular weight measured by gel permeation chromatography (GPC). When the degree of polymerization exceeds 80, when the inorganic oxide particles are surface-treated with a silicone oligomer, uneven treatment may occur and reliability may be lowered. Moreover, when the degree of polymerization is less than 5, the thickness of the coating layer made of the silicone oligomer cannot be obtained, and the effect relating to the silicone oligomer tends to be insufficient.

  In order to cover the surface of the inorganic oxide particles with a silicone oligomer having 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 6 to 70. Is preferable, and it is more preferable that it is 10-50. Such a silicone oligomer can be synthesized, for example, by condensing chlorosilane 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 the catalyst are adjusted. As the catalyst, acetic acid, hydrochloric acid, maleic acid, phosphoric acid and the like are preferably used.

  The silicone oligomer solution (treatment liquid) used for the surface treatment of the inorganic oxide particles and the treatment conditions are not particularly limited. As an example of a simple surface treatment method, there is a method in which a treatment liquid having a silicone oligomer content of 5 to 100% by mass is dropped onto the inorganic oxide particles while stirring the inorganic oxide particles in a heated nitrogen atmosphere. is there.

  Various solvents, silane coupling agents, coupling agents such as titanate coupling agents, and other additives may be blended in the treatment liquid. Examples of the silane coupling agent include epoxy silane coupling agents such as γ-glycidoxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane, hydrochloride, and the like. And aminosilane coupling agents, cationic silane coupling agents, vinyl silane coupling agents, acrylic silane coupling agents, mercaptosilane coupling agents, and composite coupling agents 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 treated with a silane coupling agent or a titanate coupling agent.

The grafting rate represented by the following formula A is 2.0% by mass or more.
Grafting rate = 100 × (total weight of hydrophobic substance 32 covering inorganic oxide particles 9) / (weight of inorganic oxide particles 9) (A)
When the grafting rate is less than 2% by mass, hydroxyl groups on the surface of the inorganic oxide particles tend to remain. As a result, it is easy to generate | occur | produce the deterioration of insulation, the fall of the capture rate of electroconductive particle, and the monodispersity of the electroconductive particle in a film.

  For example, when the hydrophobic substance 32 is a silicone oligomer, the method for measuring the grafting ratio is to heat the inorganic oxide particles coated with the silicone oligomer at 1000 ° C. to thermally decompose the silicone oligomer. The amount of decrease in the weight of the inorganic oxide particles accompanying the thermal decomposition corresponds to the weight of the thermally decomposed silicone oligomer.

  Inorganic oxide particles are superior to other particles in terms of fineness of particle diameter, uniformity of particle diameter, and insulation. Examples of the inorganic oxide constituting the inorganic oxide particles include silica, alumina, zirconium oxide, antimony trioxide, antimony pentoxide, magnesium oxide, titanium oxide, and zinc oxide. Among these, silica is preferable from the viewpoints of particle diameter, uniformity of particle diameter, insulation, and ease of surface treatment. The average particle size of the inorganic oxide particles is preferably 5 to 30 nm. The smaller the particle size of the inorganic oxide particles, the greater the thickening effect of the conductive particle layer. This is because the surface area per unit weight of the inorganic oxide particles increases as the particle size of the inorganic oxide particles decreases. When the particle size is less than 5 nm, it is difficult to stably surface-treat the inorganic oxide particles with a hydrophobic substance, and the size of the inorganic oxide particles after the surface treatment tends to be unstable. Moreover, when a particle size is larger than 30 nm, the thickening effect of a conductive particle layer is small, and there exists a tendency for a capture rate to be hard to improve. The average particle size of the inorganic oxide particles is calculated by the BET specific surface area method.

(Conductive particles)
As shown in FIG. 2, a part of the surface of the conductive particle 10 is covered with an insulator 11 (insulating child particles). The coverage of the insulator 11 in the conductive particles 10 is greater than 5%. Thereby, the insulation in the non-pressurizing direction of the anisotropic conductive film is improved.

The coverage of the insulator 11 is preferably 10 to 40%, and more preferably 10 to 30%. The coverage of the insulator 11 in the conductive particles 10 is defined by the following formula (E). Each area in the formula (E) may be obtained by analyzing the SEM image of the conductive particles 10.
Coverage of insulator 11 in conductive particle 10 = (surface area covered with insulator 11 / surface area of the entire conductive particle 10) × 100 (E)

The insulation and conductivity can be balanced by the coverage of the insulator 11. That is, according to the experience of the present inventors, when the number of conductive particles per unit area of the metal bump is 20,000 / mm ² or more in the conventional connection structure, It is necessary to set the coverage to 40% or more. However, in this embodiment, sufficient insulation is achieved even if the coverage of the insulator 11 is 10 to 30%. Thus, since the insulation coverage of the insulator 11 can be set lower than before, the continuity is improved accordingly.

  The particle diameter of the conductive particles 10 is preferably smaller than the minimum value of the distance between the metal bumps 2 and the distance between the electrodes 7. When the heights of the metal bumps 2 and the electrodes 7 vary, the particle diameter of the conductive particles 10 is preferably larger than the height variations. For these reasons, the particle size of the conductive particles 10 is preferably 1 to 10 μm, more preferably 2.5 to 5 μm, and most preferably 2.5 to 4 μm.

  As the conductive particles 10, particles made of only metal may be used. Further, as the conductive particles 10, those obtained by coating core particles such as organic compound particles or inorganic compound particles with metal plating may be used. In the present embodiment, as shown in FIG. 2, the conductive particles 10 are preferably those in which the core particles 24 made of an organic compound are coated with the metal plating 22.

  Although it does not specifically limit as a metal which comprises the metal plating 22, Gold, silver, copper, platinum, zinc, iron, palladium, nickel, tin, chromium, titanium, aluminum, cobalt, germanium, cadmium etc. are mentioned. From the viewpoint of corrosion resistance, nickel, palladium, and gold are preferable. Further, the core particles 24 may be covered with a conductive metal compound such as ITO or solder.

  The structure of the metal plating 22 may be a single layer structure or a laminated structure composed of a plurality of layers. In the case of a laminated structure, the outermost layer of the metal plating 22 is preferably composed of gold or palladium from the viewpoint of corrosion resistance and conductivity.

  Methods for forming the metal plating 22 include methods such as electroless plating, displacement plating, electroplating, and sputtering.

  The thickness of the metal plating 22 is not particularly limited, but is preferably 0.001 to 1.0 μm, and more preferably 0.005 to 0.3 μm. If the thickness of the metal plating 22 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 compound constituting the core particle 22 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.

  The insulating child particles 11 covering the conductive particles 10 are preferably fine particles made of an organic compound or fine particles made of an inorganic compound. The method for coating the conductive particles 10 with the child particles 11 is not limited.

  Below, the case where the electrically-conductive particle 10 is coat | covered with the insulating child particle 11 which consists of an inorganic compound as an example is demonstrated. Hereinafter, the insulating child particles made of an inorganic compound are referred to as “inorganic child particles”.

The inorganic compound constituting the inorganic particles is preferably an oxide containing each element of silicon, aluminum, zirconium, titanium, niobium, zinc, tin, cerium, and magnesium. These can be used alone or in admixture of two or more. Among these, the inorganic particles are most preferably water-dispersed colloidal silica (SiO ₂ ) having excellent insulating properties and controlled particle diameter. Since water-dispersed colloidal silica (SiO ₂ ) has a hydroxyl group on the surface, it has excellent bonding properties with conductive particles. Moreover, the water-dispersed colloidal silica is easy to make the particle diameter uniform. Furthermore, water-dispersed colloidal silica is inexpensive. Examples of such commercially available inorganic particles include Snowtex, Snowtex UP (manufactured by Nissan Chemical Industries), Quatron PL series (manufactured by Fuso Chemical Industries), and the like. As the inorganic particles, inorganic particles produced by metal alkoxide hydrolysis reaction, so-called sol-gel method, are suitable.

  The particle size of the inorganic particles is preferably 20 to 500 nm. When the particle diameter is smaller than 20 nm, the inorganic particles adsorbed on the conductive particles do not act as an insulating film and tend to cause a short circuit in a part of the connection structure. On the other hand, when the particle diameter is larger than 500 nm, it tends to be difficult to obtain conductivity in the pressurizing direction. The particle diameter of the inorganic particles is measured by the specific surface area conversion method by the BET method or the X-ray small angle scattering method.

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

  In general, a hydroxyl group is known to form a strong bond with a hydroxyl group, a carboxyl group, an alkoxyl group, or an alkoxycarbonyl group. 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 may be formed on the surface of the conductive particles. The inorganic particles having a hydroxyl group on the surface can be strongly adsorbed to the conductive particles having a functional group formed on the surface.

  When the outermost surface of the conductive particles (the surface of the metal plating 22) is a gold layer or a palladium layer, it is a compound having any of a mercapto group, a sulfide group, and a disulfide group that forms a coordinate bond with gold or palladium. A hydroxyl group, a carboxyl group, an alkoxyl group, or an alkoxycarbonyl group is preferably formed on the outermost surface of the conductive particle. Specifically, the outermost surface of the conductive particles may be treated with mercaptoacetic acid, 2-mercaptoethanol, methyl mercaptoacetate, mercaptosuccinic acid, thioglycerin, cysteine, or the like.

  A method for treating the outermost surface of the conductive particles with the above compound is not particularly limited, and a compound such as mercaptoacetic acid is dispersed in an organic solvent such as methanol or ethanol at a concentration of about 10 to 100 mmol / l. And a method of dispersing conductive particles having a surface made of gold or palladium.

  Below, the case where the outermost surface (surface of the metal plating 22) of the electrically-conductive particle 10 is a palladium layer is demonstrated. After the surface of the palladium layer on which the functional group is formed is treated with a polymer electrolyte, inorganic particles are chemically adsorbed on the surface of the palladium layer.

  The surface potential (zeta potential) of a palladium layer having a functional group such as a hydroxyl group, a carboxyl group, an alkoxyl group, or an alkoxycarbonyl group is usually negative if the pH is in a neutral region. On the other hand, since the surface of the inorganic particle to be adsorbed on the surface of the palladium layer in the subsequent step is composed of an inorganic oxide having a hydroxyl group, the surface potential of the inorganic particle is usually negative. As described above, inorganic particles having a negative surface potential tend not to be adsorbed around the palladium layer having a negative surface potential. Therefore, by treating the surface of the palladium layer with a polymer electrolyte, the surface of the palladium layer can be easily coated with inorganic particles.

As a method of adsorbing the inorganic particles on the surface of the palladium layer after the treatment with the polymer electrolyte, a method of alternately laminating the polymer electrolyte and the inorganic particles on the surface of the palladium layer is preferable. More specifically, the conductive particles in which a part of the surface is coated with an insulating coating film in which a polymer electrolyte and inorganic particles are laminated by sequentially performing the following steps (1) and (2). Can be manufactured.
Step (1): A step of dispersing conductive particles having a functional group on the surface of the palladium layer in a polymer electrolyte solution, adsorbing the polymer electrolyte on the surface of the palladium layer, and then rinsing the conductive particles.
Step (2): A step of rinsing the conductive particles after dispersing the rinsed conductive particles in a dispersion solution of inorganic particles and adsorbing the inorganic particles on the surface (palladium layer) of the conductive particles.

  That is, in the step (1), a polymer electrolyte thin film is formed on the surface of the conductive particles, and in the step (2), the inorganic particles are immobilized on the surface of the conductive particles through the polymer electrolyte thin film by chemical adsorption. By using this polymer electrolyte thin film, the surface of the conductive particles can be uniformly coated with inorganic particles without defects. When circuit electrodes are connected using an anisotropic conductive film using conductive particles obtained through such steps (1) and (2), insulation is ensured even when the circuit electrode interval is narrow, and electrical The connection resistance is low and good between the electrodes connected to.

  The method having the above steps (1) and (2) is referred to as 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 by Decher et al. In 1992 (see Thin Solid Films, 210/211, p831 (1992)).

  In this alternate lamination method, a polymer adsorbed on a substrate by electrostatic attraction by alternately immersing the substrate 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 a cation and a polyanion 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. (See Langmuir, Vol. 13, (1997) p6195-6203).

  By using this method, by alternately laminating silica fine particles having a negative surface charge and polydiallyldimethylammonium chloride (PDDA) or polyethyleneimine (PEI) which are polycations having the opposite charge, It is possible to form a fine particle laminated thin film in which silica fine particles and polymer electrolyte are alternately laminated.

  In this embodiment, after immersing the conductive particles in the polymer electrolyte solution and before immersing in the dispersion of inorganic particles having opposite charges, the excess polymer electrolyte solution is washed away from the conductive particles by rinsing with only the solvent. Is preferred. Alternatively, in this embodiment, after immersing the conductive particles in the dispersion of inorganic particles, and before immersing the conductive particles in the polymer electrolyte solution having an opposite charge, the dispersion of excess inorganic particles by rinsing with a solvent alone Is preferably washed away from the conductive particles.

  Since the polymer electrolyte and inorganic particles adsorbed on the conductive particles are electrostatically adsorbed on the surface of the conductive particles, they are not separated from the surface of the conductive particles in this rinsing step. However, if excess polymer electrolyte or inorganic particles that are not adsorbed with conductive particles are brought into a solution having the opposite charge to them, cations and anions are mixed in the solution, causing aggregation of the polymer electrolyte and inorganic particles. And precipitation may occur. Such a malfunction can be prevented by rinsing.

  Solvents used for rinsing include water, alcohol, acetone and the like. Usually, an ion exchange having a specific resistance value of 18 MΩ · cm or more is easy in that excessive polymer electrolyte solution or inorganic particle dispersion can be easily removed. Water (so-called ultrapure water) is used.

  The polymer electrolyte solution is obtained by dissolving a polymer electrolyte 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, halide ions are used to avoid electromigration and corrosion. Those not containing (fluorine ion, chloride ion, bromine ion, iodine ion) are preferred.

  These polymer electrolytes are either water-soluble or soluble in a mixture of water and an organic solvent, and the molecular weight of the polymer electrolyte is generally determined depending on the type of polymer electrolyte used. Although it cannot be determined, generally about 500 to 200,000 is preferable. In general, the concentration of the polymer electrolyte in the solution is preferably about 0.01 to 10% by mass. The pH of the polymer electrolyte solution is not particularly limited.

  By adjusting the type, molecular weight, or concentration of the polymer electrolyte thin film that coats the conductive particles, the coverage of the inorganic particles can be controlled within the above range.

  Specifically, when a polymer electrolyte thin film with a high charge density such as polyethyleneimine is used, the coverage of inorganic particles tends to be high, and a polymer electrolyte thin film with a low charge density such as polydiallyldimethylammonium chloride. When is used, the coverage of inorganic particles tends to be low.

  Further, when the molecular weight of the polymer electrolyte is large, the coverage of the inorganic particles tends to be high, and the inorganic particles can be firmly adsorbed to the palladium layer. On the other hand, when the molecular weight of the polymer electrolyte is small, the coverage of the inorganic particles tends to be low.

  Furthermore, when the polymer electrolyte is used at a high concentration, the coverage of the inorganic particles tends to be high, and when the polymer electrolyte is used at a low concentration, the coverage of the inorganic particles tends to be low. When the coverage of the inorganic particles is high, the insulation tends to be high and the conductivity tends to be poor, and when the coverage of the inorganic particles is low, the conductivity tends to be high and the insulation is poor.

  Only one layer of the inorganic particles is preferably coated with the conductive particles. Multi-layer stacking makes it difficult to control the stacking amount.

  The concentration of alkali metal ions and alkaline earth metal ions in the dispersion of inorganic particles is preferably 100 ppm or less. Thereby, it becomes easy to improve the insulation reliability between adjacent electrodes.

  By heating and drying the conductive particles coated with the inorganic particles, the bond between the inorganic particles and the conductive particles can be further strengthened. The reason why the binding force is increased is, for example, a chemical bond between a functional group such as a carboxyl group on the surface of the palladium layer and a hydroxyl group on the surface of the inorganic particle. From the viewpoint of preventing metal rust, heating in a vacuum is preferred.

  The drying temperature is preferably 60 to 200 ° C., and the heating time is preferably 10 to 180 minutes. When the temperature is less than 60 ° C. or when the heating time is less than 10 minutes, the inorganic particles are easily peeled off from the conductive particles, and when the temperature exceeds 200 ° C. or the heating time exceeds 180 minutes, the conductive particles Since it is easy to deform, it is not preferred.

  Since the conductive particles coated with inorganic particles have a hydroxyl group on the surface, the insulation reliability may be insufficient. Therefore, the surface of the conductive particles coated with the inorganic particles may be further treated with a hydrophobic silicone oligomer. Thereby, insulation reliability increases.

(adhesive)
As an adhesive used for the conductive particle layer 5, the adhesive layer 3, and the adhesive layer 6, for example, a mixture of a heat-reactive resin and a curing agent may be used. A preferable adhesive includes, for example, a mixture of an epoxy resin and a latent curing agent. Examples of latent curing agents include imidazole curing agents, hydrazide curing agents, boron trifluoride-amine complexes, sulfonium salts, amine imides, polyamine salts, 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 an ultraviolet curable resin may be used as the adhesive.

Epoxy resins include bisphenol-type epoxy resins derived from epichlorohydrin and bisphenol A, F, AD, etc., epoxy novolac resins derived from epichlorohydrin and phenol novolac or cresol novolac, and naphthalene-based epoxy resins having a skeleton containing a naphthalene ring. , Various epoxy compounds having two or more glycidyl groups in one molecule such as glycidylamine, glycidyl ether, biphenyl, and alicyclic can be used alone or in admixture of two or more. As these epoxy resins, it is preferable to use high-purity products in which the content of impurity ions (Na ⁺ , Cl ^−, etc.), hydrolyzable chlorine, etc. is reduced to 300 ppm or less. Thereby, electromigration is prevented.

  The adhesive may be mixed with butadiene rubber, acrylic rubber, styrene-butadiene rubber, silicone rubber, or the like. Thereby, the adhesiveness of an anisotropic conductive film improves, or the stress in the anisotropic conductive film after adhesion | attachment reduces. 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, the film-forming polymer preferably has a functional group such as a hydroxyl group. In this case, the adhesiveness is improved.

  In the formation of the adhesive layers 3 and 6, the adhesive composition composed of at least the above-described epoxy resin, acrylic rubber, and latent curing agent is liquefied by dissolving or dispersing it in an organic solvent. Then, the liquefied adhesive composition is applied on the peelable substrate, and the solvent is removed at a temperature lower than the activation temperature of the curing agent. Thereby, an adhesive layer is formed on the peelable substrate. As the solvent used for liquefaction, an aromatic hydrocarbon-based and oxygen-containing mixed solvent is preferable. By using this mixed solvent, the solubility of the adhesive composition is improved.

  In the formation of the conductive particle layer 5, the conductive particles and inorganic oxide particles coated with the inorganic particles are dispersed in the liquefied adhesive composition, and then coated on the peelable substrate to activate the curing agent. Remove solvent below temperature. Thereby, a conductive particle layer is formed on the peelable substrate.

  An anisotropic conductive film 12 is obtained by laminating the adhesive layer 3, the conductive particle layer 5 and the adhesive layer 6 formed on the peelable substrate.

(Conductive particles 1)
A nickel layer having a thickness of 0.2 μm was formed by electroless plating on the surface of crosslinked polystyrene particles (core particles) having an average particle size of 2.8 μm. Furthermore, a palladium layer having a thickness of 0.04 μm was provided outside the nickel layer. Thereby, mother particle 1 provided with metal plating which consists of two layers of the nickel layer which coats a core particle, and the palladium layer which coats a nickel layer was produced.

  Next, 8 mmol of mercaptoacetic acid was dissolved in 200 ml of methanol to prepare a reaction solution. Next, 10 g of the mother particle 1 was added to the above 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, 10 g of mother particles 1 having a carboxyl group on the surface were obtained by filtering the mother particles 1 with a membrane filter (manufactured by Millipore) having a diameter of 3 μm.

  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 mass% polyethyleneimine aqueous solution. The mother particle 1 (10 g) having a carboxyl group was added to a 0.3% by mass polyethyleneimine aqueous solution and stirred at room temperature for 15 minutes. Next, the mother particle 1 was filtered with a φ3 μm membrane filter (manufactured by Millipore), put in 200 g of ultrapure water, and stirred at room temperature for 5 minutes. Further, the mother particle 1 is filtered through a φ3 μm membrane filter (manufactured by Millipore), and the polyethyleneimine not adsorbed on the mother particle 1 is removed by washing twice with 200 g of ultrapure water on the membrane filter. did.

  Next, the mother particles 1 treated with polyethyleneimine were immersed in pure water, and a liquid obtained by diluting a colloidal silica dispersion with ultrapure water was added dropwise. As a result, mother particles 1 coated with silica as an insulator were obtained. The silica coverage was adjusted to 30%. The coverage was adjusted by the amount of the diluted colloidal silica dispersion added dropwise. As the colloidal silica dispersion, Quatron PL-13 manufactured by Fuso Chemical Industry Co., Ltd. was used. The concentration of colloidal silica in the colloidal silica dispersion was 20% by mass. The average particle size of colloidal silica was 130 nm.

  Next, the mother particle 1 was filtered with a φ3 μm membrane filter (manufactured by Millipore), put in 200 g of ultrapure water, and stirred at room temperature for 5 minutes. Further, the base particle 1 was filtered with a membrane filter (manufactured by Millipore) having a diameter of 3 μm, and the silica not adsorbed on the base particle 1 was removed by washing twice with 200 g of ultrapure water on the membrane filter. . Thereafter, the mother particles 1 were immersed in a silicone solution, and the surface of the silica covering the mother particles 1 was hydrophobized. Thereafter, drying was performed at 80 ° C. for 30 minutes, and further, heat drying was performed at 120 ° C. for 1 hour to obtain conductive particles 1.

(Conductive particles 2)
The conductive particles 2 were produced in the same manner as the conductive particles 1 except that the amount of the diluted colloidal silica dispersion dropped was adjusted and the silica coverage was 40%.

(Conductive particles 3)
The conductive particles 3 were produced in the same manner as the conductive particles 1 except that the amount of the diluted colloidal silica dispersion dropped was adjusted and the silica coverage was 50%.

(Conductive particles 4)
The conductive particles 4 were produced in the same manner as the conductive particles 1 except that the amount of the diluted colloidal silica dispersion dropped was adjusted and the silica coverage was 10%.

(Conductive particles 5)
The conductive particles 5 were produced in the same manner as the conductive particles 1 except that the amount of the diluted colloidal silica dispersion dropped was adjusted and the silica coverage was 5%.

(Silicone oligomer 1)
In 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, and at 50 ° C. The mixture was stirred for 8 hours to synthesize a silicone oligomer 1 having a siloxane unit polymerization degree of 30. The degree of polymerization was converted from the weight average molecular weight by GPC. The silicone oligomer 1 has a methoxy group and a silanol group as terminal functional groups that react with a hydroxyl group. Methanol was added to the silicone oligomer 1 solution to prepare a treatment liquid (coating agent) having a solid content of 10% by mass.

(Silicone oligomer 2)
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 heated at 80 ° C. for 4 hours for hydrolysis and polycondensation reaction. The solution after the polycondensation reaction is once cooled to 0 ° C., then 6 g of tetraethoxysilane is added dropwise and stirred at room temperature for 2 hours to contain a phenyl group in the siloxane skeleton and a trifunctional silicone polymer at the terminal. (Silicone oligomer 2) was obtained. The degree of polymerization of the siloxane units of the silicone oligomer 2 was 10. Methanol was added to the silicone oligomer 2 solution to prepare a treatment liquid having a solid content of 10% by mass.

(Silicone oligomer 3)
In 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 prepared by mixing 110 g of 3-glycidoxypropyltoxisilane and 2 g of methanol. The mixture was stirred for a time to synthesize a silicone oligomer 3 having a degree of polymerization of siloxane units of 5. The silicone oligomer 3 has a glycidyl group and a silanol group as terminal functional groups that react with a hydroxyl group. Methanol was added to the obtained silicone oligomer 3 solution to prepare a treatment liquid having a solid content of 10% by mass.

(Silica nanoparticles 1)
10 g of untreated silica nanoparticles having an average particle diameter of 12 nm (Aerosil 200, manufactured by Aerosil Co., Ltd.) were 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 the treatment solution for silicone oligomer 1 was gradually added dropwise, and after the addition, the mixture was stirred at 120 ° C. for 24 hours to prepare silica nanoparticles 1 having a particle size of 12 nm and having a surface covered with silicone. Then, the silica nanoparticle 1 was heated to 1000 degreeC with the micro thermogravimetry apparatus, and the weight change amount was measured. The weight change amount is a weight reduction rate of the silica nanoparticles 1 accompanying heating at 1000 ° C. The amount of weight change corresponds to the total weight of the resin (silicone) removed from the silica nanoparticles 1 by thermal decomposition. As a result, it was confirmed that the weight reduction amount of the silica nanoparticles 1 was 2.5% by weight. This weight loss is equal to the grafting rate.

(Silica nanoparticles 2)
Silica nanoparticles 2 were produced in the same manner as silica nanoparticles 1 except that silicone oligomer 2 was used instead of silicone oligomer 1. The weight reduction amount of the silica nanoparticles 2 measured by the same method as that for the silica nanoparticles 1 was 4.5% by weight.

(Silica nanoparticles 3)
Silica nanoparticles 3 were produced in the same manner as silica nanoparticles 1 except that silicone oligomer 3 was used instead of silicone oligomer 1. The weight loss of the silica nanoparticles 3 measured by the same method as that for the silica nanoparticles 1 was 4.5% by weight.

(Silica nanoparticles 4)
Silica nanoparticles 4 were produced in the same manner as silica nanoparticles 1 except that untreated silica nanoparticles AEROSIL300 having an average particle diameter of 7 nm were used instead of silica nanoparticles AEROSIL200. The weight reduction amount of the silica nanoparticles 4 measured by the same method as that for the silica nanoparticles 1 was 2.2% by weight.

(Silica nanoparticles 5)
Instead of AEROSIL 200, silica nanoparticles 5 were produced in the same manner as silica nanoparticles 1 except that untreated silica nanoparticles AEROSIL 50 having an average particle diameter of 30 nm were used. The amount of weight reduction of the silica nanoparticles 5 measured by the same method as that for the silica nanoparticles 1 was 2.8% by weight.

(Silica nanoparticles 6)
In the production of the silica nanoparticles 6, the amount of the silicone oligomer 1 treatment solution dropped was adjusted to 5 g instead of 10 g. Except for this, silica nanoparticles 6 were prepared in the same manner as silica nanoparticles 1. The weight reduction amount of the silica nanoparticles 6 measured by the same method as that for the silica nanoparticles 1 was 1.4% by weight.

(Evaluation example 1)
100 g of phenoxy resin (trade name, Union Carbide, PKHC) and 75 g of acrylic rubber were dissolved in 300 g of ethyl acetate to obtain a resin solution having a solid content of 30% by mass. The acrylic rubber was a copolymer formed from 40 parts by weight of butyl acrylate, 30 parts by weight of ethyl acrylate, 30 parts by weight of acrylonitrile, and 3 parts by weight of glycidyl methacrylate. The molecular weight of the acrylic rubber was 850000.

  An adhesive solution 1a was prepared by adding 300 g of liquid epoxy (Eboxy equivalent 185, manufactured by Asahi Kasei Epoxy Co., Ltd., NovaCure HX-3941) containing the microcapsule-type latent curing agent to the above resin solution and stirring. . Next, 30 mass% of silica nanoparticles 1 with respect to the adhesive solid content contained in the adhesive solution 1a was dispersed in ethyl acetate to prepare a dispersion of silica nanoparticles 1. A dispersion of silica nanoparticles 1 was added to the adhesive solution 1a to prepare an adhesive solution 1b.

  4 g of conductive particles 1 were ultrasonically dispersed in 10 g of ethyl acetate to prepare a dispersion of conductive particles 1. In ultrasonic dispersion, a sample immersed in a beaker was placed in an ultrasonic device (trade name: US107, manufactured by Fujimoto Kagaku Co., Ltd.) and stirred for 1 minute. The frequency of the ultrasonic wave was 38 kHz, and the output was 400 W. The capacity of the ultrasonic device was 20L.

A dispersion of the conductive particles 1 was dispersed in the adhesive solution 1b to prepare an adhesive solution 1c. The total value of the volume of the conductive particles contained in the adhesive solution 1c was adjusted to be 21% by volume with respect to the total volume of the adhesive components contained in the adhesive solution 1c. The solution of the adhesive solution 1c was applied to the separator with a roll coater, and dried at 90 ° C. for 10 minutes to prepare a film-like conductive particle layer (A layer). The thickness of the A layer was adjusted to 10 μm. The number of conductive particles 1 per unit area of the A layer was adjusted to 30,000 / mm ² . Hereinafter, the number of conductive particles per unit area of the A layer will be referred to as “conductive particle density”. The density of the conductive particles was confirmed by SEM (scanning electron microscope). As the separator, a polyethylene terephthalate film whose surface was treated with silicone was used. The thickness of the separator was 40 μm.

  The adhesive solution 1a was applied to the separator with a roll coater and dried at 90 ° C. for 10 minutes to produce a film-like adhesive layer (B layer). The thickness of the B layer was adjusted to 3 μm.

  The adhesive solution 1a was applied to the above separator with a roll coater and dried at 90 ° C. for 10 minutes to produce a film-like adhesive layer (C layer). The thickness of the C layer was adjusted to 10 μm.

  After laminating the A layer on the B layer, the C layer was laminated on the A layer to prepare an anisotropic conductive film D consisting of three layers.

  Using the anisotropic conductive film D, the chip with gold bumps and the glass substrate with circuit were connected in the following procedure to obtain a connection structure of Evaluation Example 1. The area of the gold bump was 30 × 90 μm. The space of the gold bump was 10 μm. The height of the gold bump was 15 μm. The number of bumps included in the chip was 362. The area of the chip was 1.7 × 1.7 mm. The thickness of the chip was 0.5 μm. The thickness of the glass substrate with circuit was 0.7 mm.

The layer B included in the anisotropic conductive film D was attached to a glass substrate with a circuit at 0.98 MPa (10 kgf / cm ² ) while heating to 80 ° C. After separating the separator from the anisotropic conductive film D and aligning the gold bumps of the chip with the glass substrate with circuit, the chip was laminated on the C layer included in the anisotropic conductive film D. The chip was pressed at a pressure of 40 [g / bump area] for 10 seconds while being heated to 190 ° C., and the chip and the glass substrate were finally connected. Thereby, the connection structure of Evaluation Example 1 was obtained.

(Evaluation example 2)
A connection structure of Evaluation Example 2 was produced in the same manner as in Evaluation Example 1 except that the conductive particles 2 were used instead of the conductive particles 1.

(Evaluation example 3)
A connection structure of Evaluation Example 3 was produced in the same manner as in Evaluation Example 1 except that the conductive particles 3 were used instead of the conductive particles 1.

(Evaluation example 4)
A connection structure of Evaluation Example 4 was produced in the same manner as in Evaluation Example 1 except that the conductive particles 4 were used instead of the conductive particles 1.

(Evaluation example 5)
A connection structure of Evaluation Example 5 was produced in the same manner as in Evaluation Example 1 except that silica nanoparticles 2 were used instead of silica nanoparticles 1.

(Evaluation example 6)
A connection structure of Evaluation Example 6 was produced in the same manner as in Evaluation Example 1 except that silica nanoparticles 3 were used instead of silica nanoparticles 1.

(Evaluation example 7)
A connection structure of Evaluation Example 7 was produced in the same manner as in Evaluation Example 1 except that silica nanoparticles 4 were used instead of silica nanoparticles 1.

(Evaluation example 8)
A connection structure of Evaluation Example 8 was produced in the same manner as in Evaluation Example 1 except that silica nanoparticles 5 were used instead of silica nanoparticles 1.

(Evaluation example 9)
A connection structure of Evaluation Example 9 was produced in the same manner as in Evaluation Example 1 except that the thickness of the A layer was 12 μm and the thickness of the C layer was 9 μm.

(Evaluation example 10)
In Evaluation Example 10, an anisotropic conductive film composed of two layers of the A layer and the C layer was used without providing the B layer. Except for this, the connection structure of Evaluation Example 10 was produced in the same manner as in Evaluation Example 1.

(Evaluation example 11)
A connection structure of Evaluation Example 11 was produced in the same manner as in Evaluation Example 1 except that the thickness of the B layer was 4 μm.

(Evaluation example 12)
In Evaluation Example 12, 10 mass% of silica nanoparticles 1 with respect to the adhesive solid content contained in the adhesive solution 1a was dispersed in ethyl acetate to prepare a dispersion of silica nanoparticles 1. Except for this, the connection structure of Evaluation Example 12 was produced in the same manner as in Evaluation Example 1.

(Evaluation example 13)
In Evaluation Example 13, a dispersion of silica nanoparticles 1 was prepared by dispersing 40% by mass of silica nanoparticles 1 in ethyl acetate with respect to the adhesive solid content contained in the adhesive solution 1a. Except for this, the connection structure of Evaluation Example 13 was produced in the same manner as in Evaluation Example 1.

(Evaluation Example 14)
A connection structure of Evaluation Example 14 was produced in the same manner as in Evaluation Example 1 except that the mother particles 1 not coated with silica were used instead of the conductive particles 1.

(Evaluation Example 15)
A connection structure of Evaluation Example 15 was produced in the same manner as in Evaluation Example 1 except that the conductive particles 5 were used instead of the conductive particles 1.

(Evaluation Example 16)
A connection structure of Evaluation Example 16 was produced in the same manner as in Evaluation Example 1 except that silica nanoparticles 6 were used instead of silica nanoparticles 1.

(Evaluation Example 17)
In Evaluation Example 17, silica nanoparticles (AEROSIL 200) whose surface was not treated with a silicone oligomer were used instead of silica nanoparticles 1. Except for this, an attempt was made to produce a connection structure of Evaluation Example 17 in the same manner as in Evaluation Example 1. However, since AEROSIL200 was not dispersed in ethyl acetate, it was impossible to produce the anisotropic conductive film and connection structure of Evaluation Example 17.

(Evaluation Example 18)
A connection structure of Evaluation Example 18 was produced in the same manner as in Evaluation Example 1 except that R805 (manufactured by Aerosil) was used instead of silica nanoparticle 1. R805 is obtained by hydrophobizing the surface of silica having a particle size of 12 nm with a silane coupling agent. The weight loss amount of R805 measured by the same method as that of silica nanoparticle 1 was 5.2% by weight.

(Evaluation Example 19)
In Evaluation Example 19, 10 mass% of silica nanoparticles 1 with respect to the adhesive solid content contained in the adhesive solution 1a was dispersed in ethyl acetate to prepare a dispersion of silica nanoparticles 1. A dispersion of silica nanoparticles 1 was added to the adhesive solution 1a to prepare an adhesive solution 1-19. B layer and C layer were formed using the adhesive solution 1-19. A connection structure of Evaluation Example 19 was produced in the same manner as in Evaluation Example 1 except for the above items.

(Evaluation Example 20)
In Evaluation Example 20, a dispersion of silica nanoparticles 1 was prepared by dispersing 30% by mass of silica nanoparticles 1 in ethyl acetate with respect to the adhesive solid content contained in the adhesive solution 1a. A dispersion of silica nanoparticles 1 was added to the adhesive solution 1a to prepare an adhesive solution 1-20. B layer and C layer were formed using adhesive solution 1-20. Except for the above, a connection structure of Evaluation Example 20 was produced in the same manner as in Evaluation Example 1.

  In addition, the silica layer is not contained in the contact bonding layer with which connection structures other than the evaluation examples 19 and 20 are provided.

(Evaluation Example 21)
A connection structure of Evaluation Example 21 was produced in the same manner as in Evaluation Example 1 except that the thickness of the B layer was 10 μm.

(Evaluation example 22)
A connection structure of Evaluation Example 22 was produced in the same manner as in Evaluation Example 1 except that the thickness of the A layer was 15 μm.

(Evaluation Example 23)
In Evaluation Example 23, a silica nanoparticle 1 dispersion was prepared by dispersing 5 mass% of silica nanoparticles 1 in ethyl acetate with respect to the adhesive solid content contained in the adhesive solution 1a. Except for this, the connection structure of Evaluation Example 23 was produced in the same manner as in Evaluation Example 1.

(Evaluation Example 24)
In Evaluation Example 24, a silica nanoparticle 1 dispersion was prepared by dispersing 50% by mass of silica nanoparticles 1 in ethyl acetate with respect to the adhesive solid content contained in the adhesive solution 1a. Except for this, the connection structure of Evaluation Example 24 was produced in the same manner as in Evaluation Example 1.

(Evaluation Example 25)
In Evaluation Example 25, the density of the conductive particles in the A layer was controlled to 20000 particles / mm ² by adjusting the amount of the conductive particles contained in the adhesive solution 1c. Except for this, the connection structure of Evaluation Example 25 was produced in the same manner as in Evaluation Example 1.

(Evaluation Example 26)
In Evaluation Example 26, the density of the conductive particles in the A layer was controlled to 15000 particles / mm ² by adjusting the amount of the conductive particles contained in the adhesive solution 1c. Except for this, the connection structure of Evaluation Example 26 was produced in the same manner as in Evaluation Example 1.

[Appearance inspection of conductive particle layer]
When the conductive particle layers of Evaluation Examples 1 to 16 and 17 to 26 were formed by coating, the appearance of the conductive particle layers was inspected. The inspection results are shown in Table 2 below. When a large amount of nanoparticles that are difficult to disperse in the conductive particle layer are introduced into the conductive particle layer, the nanoparticles become an aggregate of several microns, and streaks are generated in the conductive particle layer during coating. Since there are almost no conductive particles in the portion where the streaks are generated, the streaks cause poor conduction.

[Peeling inspection]
The connection structures of Evaluation Examples 1 to 16 and 17 to 26 were left for 200 hours in an environment where the temperature was 85 ° C. and the humidity was 85%. The connection structure after being left was inspected for isolation between the glass substrate and the anisotropic conductive film. The inspection results are shown in Table 2 below.

[Insulation resistance test]
The insulation resistance test of the connection structures of Evaluation Examples 1 to 16 and 17 to 26 was performed. In the insulation resistance test, the resistance value (insulation resistance) between the gold bumps of the chip was measured. The distance between the gold bumps was 10 μm. The higher the insulation resistance, the better.

In the insulation resistance test, 20 connection structures of each evaluation example were prepared. In the insulation resistance test, the insulation resistance (initial value) before the migration test of each connection structure and the insulation resistance after the migration test were measured. Table 2 below shows the minimum value of the insulation resistance shown in each evaluation example. In the insulation resistance test, the ratio (yield) of the number of connection structures showing an insulation resistance greater than 10 ⁹ (Ω) among the 20 connection structures of each evaluation example was calculated. The yield (%) of the connection structure of each evaluation example is shown in Table 2 below. In the migration test, the connection structure was left in an environment of 60 ° C. temperature and 90% humidity for 1000 hours while applying a voltage of 20 V between the gold bumps.

[Conduction resistance test]
Conduction resistance tests were performed on the connection structures of Evaluation Examples 1 to 16 and 17 to 26. In the conduction resistance test, the resistance value (conduction resistance) between the gold bump of the chip and the circuit of the glass substrate was measured. The lower the conduction resistance, the better.

  In the conduction resistance test, the average value of the conduction resistance of the 14 connection structures was measured. In the conduction resistance test, the conduction resistance (initial value) before the moisture absorption heat test of the connection structure and the conduction resistance after the moisture absorption heat test were measured. The average value of the conduction resistance of each evaluation example is shown in Table 2 below. In the moisture absorption heat resistance test, each connection structure was left for 1000 hours in an environment where the temperature was 85 ° C. and the humidity was 85%.

[Measurement of capture rate]
The capture rates (%) of the connection structures of Evaluation Examples 1 to 16 and 17 to 26 were measured. The capture rate of each evaluation example is shown in Table 2 below. The capture rate is a ratio of the density of the conductive particles on the gold bump to the density of the conductive particles in the anisotropic conductive film, and is calculated by the following formula (B). The capture rate is a desired characteristic, the higher the better. The average value of the number of conductive particles on the gold bump was calculated from the number of conductive particles on 100 gold bumps. The number of conductive particles on each gold bump was confirmed by SEM.
Capture rate (%) = (average number of particles on gold bump / gold bump area / number of conductive particles contained per unit area of anisotropic conductive film) × 100 (B)

  The structure of the connection structure of each evaluation example is shown in Table 1. Table 2 shows the results of appearance inspection, peel inspection, insulation resistance test, conduction resistance test, and capture rate measurement of the conductive particle layer of each evaluation example.

  The functional groups shown in parentheses in Table 1 are functional groups possessed by the silicone oligomer that is a coating agent. The weight reduction amount of the silica nanoparticles shown in Table 1 corresponds to the grafting rate. Each area of A layer, B layer, and C layer is equal. Therefore, the ratio of the thickness of each layer corresponds to the ratio of the volume of each layer.

In Table 2, an insulation resistance of 10 ¹⁰ (Ω) or more is evaluated as A. An insulation resistance of 10 ⁹ (Ω) or more and less than 10 ¹⁰ (Ω) is evaluated as B. An insulation resistance of 10 ⁸ (Ω) or more and less than 10 ⁹ (Ω) is evaluated as C. An insulation resistance of less than 10 ⁵ (Ω) is evaluated as D.

  In the column of the conduction resistance after the test in Table 2, a conduction resistance of 10 (Ω) or less is evaluated as A. A conduction resistance greater than 10 (Ω) and less than or equal to 15 (Ω) is evaluated as B. An insulation resistance greater than 15 (Ω) and not greater than 20 (Ω) is evaluated as C. A conduction resistance greater than 20 (Ω) is evaluated as D.

  In Table 2, a capture rate of 50% or more is evaluated as A. A capture rate of 40% or more and less than 50% is evaluated as B. A capture rate of 30% or more and less than 40% is evaluated as C. A capture rate of less than 30% is rated as D.

  In Evaluation Examples 1 to 13, 19, 22, 24, and 25, the results of the appearance inspection and the mounting test are stable at a high level. In addition, since the conditions of the insulation resistance test are quite strict, the anisotropic conductive film cannot actually be used unless the yield is 100%. Evaluation Examples 1 to 13, 19, 22, 24, and 25 can be suitably used as general-purpose products.

  Evaluation Examples 1, 12, 13, 23, and 24 are data in which only the addition amount of silica nanoparticles was changed. It can be seen that as the amount of silica nanoparticles added increases, the trapping rate of the conductive particles improves. If the capture rate is improved, the effect can be obtained even if the input amount of the conductive particles is reduced. Therefore, the improvement of the capture rate can reduce the input amount of conductive particles and contribute to cost reduction and insulation improvement.

  In Evaluation Example 23, a conventional anisotropic conductive film with a small amount of silica nanoparticles added was used. In Evaluation Example 23, since the trapping is low, the conduction resistance is high and the insulation resistance is also low. In Evaluation Example 24, the content of silica nanoparticles in the conductive particle layer is high, which is 50% by mass. As in Evaluation Example 24, when too much silica nanoparticles are put in the conductive particle layer, streaks are generated during coating due to aggregation of the silica nanoparticles. Furthermore, in the evaluation example 24, since the aggregated silica nanoparticles enter between the gold bump and the conductive particles, the conduction resistance is slightly increased. From the above viewpoint, it can be seen that the optimum amount of the inorganic oxide particles having a hydrophobic surface is 10 to 40% by mass with respect to the varnish solid content (total amount of adhesive) of the conductive particle layer.

  Evaluation Examples 1-4, 14 and 15 are data in which the silica coverage on the surface of the conductive particles was changed. Essentially, when the silica coverage is increased, the insulation is improved and the conductivity is deteriorated. In the present invention, the insulating property is increased by increasing the amount of silica nanoparticles introduced into the conductive particle layer. Therefore, in the present invention, insulation can be maintained without increasing the silica coverage on the surface of the conductive particles. The silica coverage on the surface of the conductive particles is preferably 10 to 40%.

  Evaluation Examples 1, 5 to 8, 16, 17, and 18 are data in which the type of silica nanoparticles and the weight reduction amount (grafting rate) of silica nanoparticles were changed.

  In Evaluation Example 17, since the silica nanoparticles were not surface-treated, the silica nanoparticles were not dispersed in the solvent for forming the conductive particle layer, and the conductive particle layer and the anisotropic conductive film could not be prepared. .

  In Evaluation Example 18, silica nanoparticles surface-treated with a commonly used silane coupling agent were used. In Evaluation Example 18, it was found that when the conductive particle layer was applied, streaks due to the aggregation of silica nanoparticles occurred frequently. It was found that the silica nanoparticles surface-treated with the monomer aggregate in the varnish because the coating unevenness is large. Conventionally, when silica particles that have been completely hydrophobically treated are used, it has been difficult to obtain a thickening effect of the conductive particle layer during pressure bonding. For this reason, conventionally, silica particles treated with a silane coupling agent are often added to the conductive particle layer by several percent. On the other hand, in the present invention, as in Evaluation Example 1, by using silica nanoparticles coated with silicone, aggregation and movement of conductive particles can be suppressed, and the capture rate can be greatly improved. When the diameter of the silica nanoparticles is small as in Evaluation Example 7, the effect of capturing the conductive particles is particularly large. When the diameter of nano silica is large as in Evaluation Example 8, the conductive particle capturing effect is small.

  As shown in Evaluation Examples 1, 5, and 6, the effect of the present invention was obtained when any of the three types of silicone was used. In particular, in Evaluation Example 5 using silicone having a phenyl group, it was found that the insulation resistance was remarkably high.

  In Evaluation Example 16, since the silicone coverage (grafting rate) on the surface of the silica nanoparticles was less than 2% by mass, the conductive particle layer streaks due to the aggregation of the silica nanoparticles occurred frequently, and the insulation was also lowered.

  Evaluation Examples 1, 19 and 20 are data in which the concentration of silica nanoparticles in the adhesive layer was changed. If silica nanoparticles are added to the adhesive layer, the fluidity of the adhesive layer is lowered, and the conductive particles are relatively easy to move. Therefore, the trapping rate of the conductive particles decreases as silica nanoparticles are added to the adhesive layer. From the comparison of Evaluation Examples 1, 19 and 20, it can be seen that the content of silica nanoparticles in the adhesive layer is preferably less than 30% by mass.

  Evaluation Examples 1, 9 to 11, 21, and 22 are data in which the thicknesses of the A layer, the B layer, and the C layer are changed. Evaluation Examples 9 to 11 indicate that the capture rate is improved as the thickness of the B layer is thinner. If it is used for an application where peeling of the glass substrate and the adhesive is not a problem, the B layer may be omitted. However, if there is a B layer having a thickness of 4 μm or less, the balance is good. The trapping rate tends to be higher as the conductive particle layer (A layer) in the entire anisotropic conductive film is thinner. It can be seen that the volume of the conductive particle layer is preferably 50% by volume or less of the entire film.

From the comparison of Evaluation Examples 1, 25, and 26, the higher the density of the conductive particles, the better the conductivity. It can be seen that in order to achieve a conduction resistance of 20 (Ω) or less, a density of 20000 particles / mm ² or more of conductive particles is necessary. Conversely, in the present invention, sufficient conductivity can be obtained even if the density of the conductive particles is 20000 particles / mm ^{2 because} of the high capture rate.

  DESCRIPTION OF SYMBOLS 1 ... IC chip, 2 ... Metal bump, 3, 6 ... Adhesion layer, 5 ... Conductive particle layer, 7 ... Electrode, 8 ... Glass substrate, 9 ... Inorganic oxidation 10 ... conductive particles, 11 ... insulator, 12 ... anisotropic conductive film, 20 ... adhesive, 22 ... metal plating, 24 ... core particles, 32 ... ..Hydrophobic substances, 42... Connection structure

Claims (8)

A conductive particle layer containing conductive particles and an adhesive;
An anisotropic conductive film comprising an adhesive layer that is laminated to the conductive particle layer and contains an adhesive,
The conductive particle layer further contains inorganic oxide particles;
The conductive particles are contained only in the conductive particle layer,
A part of the surface of the conductive particles is covered with an insulator,
A coverage of the insulator in the conductive particles is greater than 5%;
The number of the conductive particles per unit area of the conductive particle layer is 20,000 / mm ² or more,
The surface of the inorganic oxide particles is coated with a hydrophobic substance,
The grafting rate represented by the following formula A is 2.0 mass% or more,
The content of the inorganic oxide particles in the conductive particle layer is 10% by mass or more with respect to the total amount of the adhesive contained in the conductive particle layer,
The content of the inorganic oxide particles in the adhesive layer is 0% by mass or more and less than 30% by mass with respect to the total amount of the adhesive contained in the adhesive layer.
Anisotropic conductive film.
Grafting rate = 100 × (mass of the hydrophobic substance) / (mass of the inorganic oxide particles) (A) The hydrophobic substance is silicone;
The anisotropic conductive film according to claim 1. The degree of polymerization of the silicone is 3 or more,
The anisotropic conductive film according to claim 2. The inorganic oxide particles are silica having a particle size of 5 to 30 nm.
The anisotropic conductive film as described in any one of Claims 1-3. The coverage of the insulator in the conductive particles is 10 to 40%.
The anisotropic conductive film as described in any one of Claims 1-4. The adhesive layer is laminated on both sides of the conductive particle layer,
The average value of the thickness of the adhesive layer laminated on one side of the conductive particle layer is 4 μm or less.
The anisotropic conductive film as described in any one of Claims 1-5. The content of the inorganic oxide particles in the conductive particle layer is 40% by mass or less based on the total amount of the adhesive contained in the conductive particle layer.
The anisotropic conductive film as described in any one of Claims 1-6. The volume of the conductive particle layer is 50% by volume or less with respect to the entire anisotropic conductive film,
The anisotropic conductive film as described in any one of Claims 1-7.

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