JP2020013787A - Conductive material and connection structure - Google Patents

Abstract

To provide a conductive material capable of effectively preventing generation of crack or warpage at a connection part when a connection structure is obtained by electrically connecting electrodes, and effectively enhancing adhesive force of the connection part.SOLUTION: The conductive material contains a plurality of conductive particles, a plurality of fillers and a binder resin. When a cured article of the conductive material is obtained by heating and pressing the conductive material under a heating condition of 150°C for 10 sec. and a pressing condition of 3 MPa, the fillers are unevenly distributed in the cured article, and the number of fillers existing in an area by a distance of 1/2 of particle diameter of the conductive particle from a surface of the conductive particle toward the outside is 70% or more of all of the fillers (100%) contained in the cured article.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive material containing conductive particles. Further, the present invention relates to a connection structure using the conductive material.

  Anisotropic conductive materials such as anisotropic conductive pastes and films are widely known. In the anisotropic conductive material, conductive particles are dispersed in a binder resin. In addition, as the conductive particles, conductive particles having a surface of a conductive layer subjected to insulation treatment may be used.

  The anisotropic conductive material is used to obtain various connection structures. Examples of the connection using the anisotropic conductive material include a connection between a flexible printed board and a glass substrate (FOG (Film on Glass)), a connection between a semiconductor chip and a flexible printed board (COF (Chip on Film)), The connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)), the connection between a flexible printed board and a glass epoxy substrate (FOB (Film on Board)), and the like can be given.

  As an example of the anisotropic conductive material, Patent Document 1 below discloses an adhesive film composed of a curable resin composition. In the above adhesive film, the glass transition temperature after curing is 65 ° C to 110 ° C. The adhesive film has an elastic modulus at 40 ° C. after curing of 1500 MPa or less. The adhesive film has an elastic modulus at 100 ° C. after curing of 10 MPa or more.

  Patent Document 2 below discloses an anisotropic conductive material containing conductive particles and a curable compound. In the anisotropic conductive material, the conductive particles include base particles and a conductive layer covering the surface of the base particles. In the anisotropic conductive material, the compression recovery rate of the base particles is 50% or less. In the anisotropic conductive material, the elasticity at 40 ° C. of the cured product obtained by curing the anisotropic conductive material is 1500 MPa or less. In the anisotropic conductive material, the cured product has an elastic modulus at 100 ° C. of 10 MPa or more.

JP 2010-100840 A JP 2012-209097 A

  When the connection structure is obtained from the anisotropic conductive material, for example, an anisotropic conductive material containing conductive particles is arranged on the first member to be connected, and then the second member to be connected is connected. And heating and pressurizing. Thereby, the anisotropic conductive material is cured to form a connection portion for electrically connecting the electrodes via the conductive particles, thereby obtaining a connection structure.

  When obtaining the connection structure, stress may be applied to the connection target member or the connection portion due to a difference in the material of the connection target member, the heat history of the connection portion, or the like. This stress may cause cracks and warpage in the connection target member and the connection portion.

  As a method of preventing the occurrence of cracks and warpage in the connection portion and the like, a method of alleviating internal stress and the like can be mentioned. As a method of relaxing internal stress, for example, a method of adding stress relaxation particles such as silicone particles to a connection portion or the like can be mentioned.

  However, in the method of adding the stress relaxation particles to the connection portion or the like, as the amount of the stress relaxation particles increases, the adhesive force of the connection portion decreases, and it is difficult to bond the connection portion and the member to be connected. There is. With a conventional anisotropic conductive material, it is difficult to achieve both the prevention of cracks and warpage in the connection portion and the enhancement of the adhesive strength of the connection portion.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a connection structure by electrically connecting electrodes, thereby effectively preventing cracks and warpage in the connection portion, and reducing the adhesive force of the connection portion. It is to provide a conductive material that can be effectively enhanced. Another object of the present invention is to provide a connection structure using the above conductive material.

  According to a broad aspect of the present invention, there is provided a conductive material including a plurality of conductive particles, a plurality of fillers, and a binder resin, wherein the conductive material is heated at 150 ° C. for 10 seconds and heated at 3 MPa. When heated and pressurized under pressure conditions to obtain a cured product of the conductive material, the filler is unevenly distributed in the cured product, and the total number of the fillers contained in the cured product is 100%. A conductive material is provided, in which the ratio of the number of the fillers present in a region extending from the surface of the conductive particles outward to a distance of 1/2 of the particle diameter of the conductive particles is 70% or more. Is done.

  In one specific aspect of the conductive material according to the present invention, the total number of the fillers contained in the cured product is 100% of the particle diameter of the conductive particles inward from the surface of the cured product. The ratio of the number of the fillers existing in the region up to the distance of 5 is less than 50%.

  In a specific aspect of the conductive material according to the present invention, a storage elastic modulus at 25 ° C. of the cured product is 1000 MPa or more and 6000 MPa or less.

  In a specific aspect of the conductive material according to the present invention, the filler is disposed on a surface of the conductive particle.

  In a specific aspect of the conductive material according to the present invention, the content of the filler is 0.5% by weight or more and 45% by weight or less in 100% by weight of the conductive material.

  In a specific aspect of the conductive material according to the present invention, the storage elastic modulus at 25 ° C. of the filler is 500 MPa or more and 1700 MPa or less.

  According to a broad aspect of the present invention, a first connection target member having a first electrode on a surface, a second connection target member having a second electrode on a surface, the first connection target member, A connection portion connecting the second connection target member, wherein a material of the connection portion is a conductive material including a plurality of conductive particles, a plurality of fillers, and a binder resin; And the second electrode are electrically connected by the conductive particles, and out of 100% of the total number of the fillers contained in the connection portion, from the surface of the conductive particles to the outside. Thus, a connection structure is provided in which the proportion of the number of the fillers existing in a region up to a distance of 1/2 of the particle diameter of the conductive particles is 70% or more.

  In a specific aspect of the connection structure according to the present invention, in the total number of fillers included in the connection portion, 100% of the particle diameter of the conductive particles is inward from the surface of the connection portion. The ratio of the number of the fillers existing in the region up to the distance of / 5 is less than 50%.

  In a specific aspect of the connection structure according to the present invention, a storage elastic modulus at 25 ° C. of the connection portion is 1000 MPa or more and 6000 MPa or less.

  In a specific aspect of the connection structure according to the present invention, the filler is disposed on a surface of the conductive particle.

  The conductive material according to the present invention includes a plurality of conductive particles, a plurality of fillers, and a binder resin. In the conductive material according to the present invention, when the conductive material is heated and pressed under heating conditions of 150 ° C. and 10 seconds, and under a pressure of 3 MPa, a cured product of the conductive material is obtained. The filler is unevenly distributed in the object. In the conductive material according to the present invention, the total number of the fillers contained in the cured product is 100%, from the surface of the conductive particles to the outside, to a distance of 1/2 of the particle diameter of the conductive particles. Is 70% or more. In the conductive material according to the present invention, since the above configuration is provided, when a connection structure is obtained by electrically connecting the electrodes, the occurrence of cracks and warpage in the connection portion is effectively prevented. And the adhesive strength of the connection portion can be effectively increased.

  The connection structure according to the present invention includes a first connection target member having a first electrode on the surface, a second connection target member having a second electrode on the surface, the first connection target member, And a connecting portion connecting the second connection target member. In the connection structure according to the present invention, the material of the connection portion is a conductive material including a plurality of conductive particles, a plurality of fillers, and a binder resin. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by the conductive particles. In the connection structure according to the present invention, a distance of 1/2 of the particle diameter of the conductive particles from the surface of the conductive particles to the outside in 100% of the total number of the fillers contained in the connection portion. Up to 70% or more. In the connection structure according to the present invention, since the above-described configuration is provided, it is possible to effectively prevent the occurrence of cracks and warpage in the connection portion, and to effectively increase the adhesive force of the connection portion. Can be.

FIG. 1 is a sectional view schematically showing a cured product of a conductive material according to one embodiment of the present invention. FIG. 2 is a cross-sectional view showing conductive particles with filler used in the conductive material according to the present invention. FIG. 3 is a cross-sectional view illustrating a first modified example of the conductive particles with a filler. FIG. 4 is a cross-sectional view showing a second modified example of the conductive particles with filler. FIG. 5 is a cross-sectional view schematically showing a connection structure using the conductive material according to the present invention. FIG. 6 is a schematic diagram for explaining each region for determining the ratio of the number of fillers in the cured product of the conductive material according to the present invention. FIG. 7 is a schematic diagram for explaining each region for calculating the ratio of the number of fillers in the connection structure according to the present invention.

  Hereinafter, details of the present invention will be described.

(Conductive material)
The conductive material according to the present invention includes a plurality of conductive particles, a plurality of fillers, and a binder resin. In the conductive material according to the present invention, when the conductive material is heated and pressed under the heating conditions of 150 ° C. and 10 seconds, and the pressurizing condition of 3 MPa, the cured product of the conductive material is obtained. The filler is unevenly distributed in the object. In the conductive material according to the present invention, the total number of the fillers contained in the cured product is 100%, from the surface of the conductive particles to the outside, to a distance of 1/2 of the particle diameter of the conductive particles. Is 70% or more.

  In the conductive material according to the present invention, the filler contained in the cured product exists relatively densely at a position close to the conductive particles and relatively sparse at a position far from the conductive particles. The filler may be disposed on the surface of the conductive particles, or may not be disposed on the surface of the conductive particles. Preferably, the filler is disposed on a surface of the conductive particles. In addition, at a position far from the conductive particles (for example, a position far away from the conductive particles), the filler contained in the cured product may not be present.

  In the conductive material according to the present invention, since the above configuration is provided, when a connection structure is obtained by electrically connecting the electrodes, the occurrence of cracks and warpage in the connection portion is effectively prevented. And the adhesive strength of the connection portion can be effectively increased.

  A connection structure can be obtained by electrically connecting electrodes on a substrate using an anisotropic conductive material. In manufacturing the connection structure, stress may be applied to the connection target member or the connection portion due to a difference in the material of the connection target member, the heat history of the connection portion, or the like. This stress may cause cracks and warpage in the connection target member and the connection portion.

  Examples of a method for preventing the occurrence of cracks and warpage in the connection target member and the connection portion include a method in which stress relaxation particles such as silicone particles are added to the connection portion to reduce internal stress. However, in order to prevent the occurrence of cracks and warpage by using the stress relaxing particles, it is necessary to add a relatively large amount of the stress relaxing particles to the connection portion. If a relatively large amount of the stress relaxing particles is added to the connecting portion, the stress relaxing particles are also arranged on the surface of the connecting portion, and the ratio of the binder resin on the surface of the connecting portion relatively decreases. Since the adhesive strength of the connecting part is expressed by the binder resin on the surface of the connecting part, if the ratio of the binder resin on the surface of the connecting part relatively decreases, the adhesive strength of the connecting part decreases, and the connecting part is connected. It may be difficult to adhere to the target member. With a conventional anisotropic conductive material, it is difficult to achieve both the prevention of cracks and warpage in the connection portion and the enhancement of the adhesive strength of the connection portion.

  The present inventors have found that by using a specific conductive material, it is possible to both prevent the occurrence of cracks and warpage in the connection portion and increase the adhesive strength of the connection portion. According to the present invention, a relatively large amount of filler exhibiting a stress relaxation effect can be added to the connection portion, and the filler can be prevented from being arranged on the surface of the connection portion. As a result, when a connection structure is obtained by electrically connecting the electrodes, it is possible to effectively prevent the occurrence of cracks and warpage in the connection portion, and to effectively reduce the adhesive force of the connection portion. Can be enhanced.

  In the present invention, use of a specific conductive material greatly contributes to obtaining the above-described effects.

  The conductive material according to the present invention includes a plurality of conductive particles, a plurality of fillers, and a binder resin. When the conductive material is heated and pressed under heating conditions of 150 ° C. and 10 seconds, and under a pressure of 3 MPa to obtain a cured product of the conductive material, in the cured product, the filler is conductive. Are unevenly distributed around the conductive particles.

  The shape of the cured product is not particularly limited. The shape of the cured product may be a rectangular parallelepiped shape or a shape other than a rectangular parallelepiped shape. The thickness of the cured product in the height direction is preferably uniform. When obtaining the cured product used for judging the uneven distribution state, it is preferable to obtain a cured product having a length of 1 mm to 100 mm, a width of 0.5 mm to 50 mm, and a height of 1 mm to 200 mm. In particular, it is preferable to obtain a cured product in a rectangular parallelepiped shape having a length of 5 mm to 20 mm, a width of 1 mm to 10 mm, and a height of 50 mm to 150 mm, and it is more preferable to obtain a cured product in a rectangular shape having a length of 10 mm, 5 mm, and 100 mm .

  When the conductive material according to the present invention is actually used (for example, when a connection structure is manufactured using the conductive material, etc.), the curing conditions of the conductive material are heating conditions of 150 ° C. and 10 seconds, Further, the heating and pressurizing under the pressurizing condition of 3 MPa need not be performed.

  In the conductive material according to the present invention, the total number of the fillers contained in the cured product is 100%, from the surface of the conductive particles to the outside, to a distance of 1/2 of the particle diameter of the conductive particles. The ratio of the number of the fillers present in the region (first region, R1) is 70% or more. The proportion of the number of the fillers present in the first region (R1) is preferably 80% or more, more preferably 85% or more, based on 100% of the total number of the fillers contained in the cured product. The proportion of the number of the fillers present in the first region (R1) in the total number of the fillers contained in the cured product of 100% may be 75% or less. The upper limit of the ratio of the number of the fillers present in the first region (R1) to 100% of the total number of the fillers contained in the cured product is not particularly limited. The proportion of the number of the fillers present in the first region (R1) in the total number of the fillers contained in the cured product of 100% may be 95% or less. The ratio of the number of the fillers present in the first region (R1) is the ratio of the number of the fillers in which at least a part of the filler is included in the first region (R1). If the ratio of the number of the fillers present in the first region (R1) is equal to or larger than the lower limit, when a connection structure is obtained by electrically connecting the electrodes, cracks and warpage in the connection portion are obtained. Can be more effectively prevented, and the adhesive strength of the connection portion can be more effectively increased. The first region (R1) is a region between the outer surface of the conductive particle 1 and the broken line L1 in FIG. The distance between the outer surface of the conductive particles 1 and the broken line L1 is の of the particle diameter of the conductive particles 1.

  The proportion of the number of the fillers present in the first region (R1) in 100% of the total number of the fillers contained in the cured product is determined by scanning the cured product of the conductive material with a scanning electron microscope (SEM) or the like. It can be calculated by observing using. Specifically, the cured product of the conductive material is cut with a cross section polisher (CP) or the like, and the cross section of the cured product is observed with a scanning electron microscope. The ratio of the filler is calculated by measuring the number of fillers in the first region (R1) in the cut surface of the cured product and the number of fillers in regions other than the first region (R1). can do.

  As a method for setting the ratio of the number of the fillers present in the first region (R1) in the total number of the fillers contained in the cured product to 100% or more to 70% or more, the following method is exemplified. A method for producing conductive particles with filler in which a filler is attached on the surface of conductive particles by a hybridizer or the like, and producing a conductive material and a cured product of the conductive material using the conductive particles with filler. A method in which conductive particles and a filler are kneaded in a binder resin, and an external magnetic field is applied to generate an attractive force between the conductive particles and the filler. A method in which conductive particles having interactive properties such as magnetism and a filler are kneaded together with a binder resin. A method in which a functional group that produces a bond such as a chemical bond or a coordinate bond is introduced into the surface of the conductive particles and the surface of the filler, and kneaded together with a binder resin. A method in which a filler is attached to conductive particles by chemical bonding or intermolecular attraction, and then the conductive particles to which the filler is attached are dispersed in a binder resin.

  A surface on one side in the thickness direction of the cured product is a first surface, and a surface on the other side in the thickness direction of the cured product is a second surface.

  In a total number of 100% of the filler contained in the cured product, from the surface (one surface, the first surface) of the cured product toward the inside, 1/5 of the particle diameter of the conductive particles was used. The ratio of the number of the fillers existing in the region (the second region, R2) up to the distance is preferably less than 50%, more preferably 20% or less. The lower limit of the ratio of the number of the fillers present in the second region (R2) to 100% of the total number of the fillers contained in the cured product is not particularly limited. The proportion of the number of the fillers present in the second region (R2) in the total number of the fillers contained in the cured product of 100% may be 5% or more. The ratio of the number of the fillers present in the second region (R2) is the ratio of the number of the fillers in which at least a part of the filler is included in the second region (R2). When the ratio of the number of the fillers present in the second region (R2) is equal to or less than the upper limit, when a connection structure is obtained by electrically connecting the electrodes, cracks and warpage in the connection portion are obtained. Can be more effectively prevented, and the adhesive strength of the connection portion can be more effectively increased. The second region (R2) is a region between the first surface 51a and the broken line L2 in FIG. The distance between the first surface 51a and the broken line L2 is １ ／ of the particle diameter of the conductive particles 1.

  In a total number of 100% of the filler contained in the cured product, 1/5 of the particle diameter of the conductive particles is inward from the surface of the cured product (the other surface, the second surface) to the inside. The ratio of the number of the fillers existing in the region up to the distance (third region, R3) is preferably less than 50%, more preferably 20% or less. The lower limit of the ratio of the number of the fillers present in the third region (R3) to 100% of the total number of the fillers contained in the cured product is not particularly limited. The proportion of the number of the fillers present in the third region (R3) in the total number of the fillers contained in the cured product of 100% may be 5% or more. The ratio of the number of fillers present in the third region (R3) is the ratio of the number of fillers in which at least a part of the filler is included in the third region (R3). When the ratio of the number of the fillers existing in the third region (R3) is equal to or less than the upper limit, when a connection structure is obtained by electrically connecting the electrodes, cracks and warpage in the connection portion are obtained. Can be more effectively prevented, and the adhesive strength of the connection portion can be more effectively increased. The third region (R3) is a region between the second surface 51b and the broken line L3 in FIG. The distance between the second surface 51b and the broken line L3 is １ ／ of the particle diameter of the conductive particles 1.

  As a method of controlling the number of the fillers in the second region (R2) or the third region (R3) in 100% of the total number of the fillers contained in the cured product to the preferred range, The following methods are mentioned. A method for producing conductive particles with filler in which a filler is attached on the surface of conductive particles by a hybridizer or the like, and producing a conductive material and a cured product of the conductive material using the conductive particles with filler. A method in which conductive particles having interactive properties such as magnetism and a filler are kneaded together with a binder resin. A method in which a functional group that produces a bond such as a chemical bond or a coordinate bond is introduced into the surface of the conductive particles and the surface of the filler, and kneaded together with a binder resin. A method in which a filler is attached to conductive particles by chemical bonding or intermolecular attraction, and then the conductive particles to which the filler is attached are dispersed in a binder resin.

  The proportion of the number of the fillers present in the second region (R2) or the third region (R3) in 100% of the total number of the fillers contained in the cured product is determined by the ratio of the cured material of the conductive material. It can be calculated by observing using a scanning electron microscope (SEM) or the like. Specifically, the cured product of the conductive material is cut with a cross section polisher (CP) or the like, and the cross section of the cured product is observed with a scanning electron microscope. The number of fillers in the second region (R2) in the cut surface of the cured product and the number of fillers in regions other than the second region (R2), or the number of fillers in the cut surface of the cured product By measuring the number of fillers in the third region (R3) and the number of fillers in regions other than the third region (R3), the ratio of the number of fillers can be calculated.

  The ratio of the number of the fillers present in the second region (R2) or the third region (R3) in 100% of the total number of the fillers contained in the cured product is controlled within the above-described preferred range. Examples of the method include the following methods. A method for producing a conductive particle with a filler in which a filler is attached on the surface of the conductive particle, and using the conductive particle with a filler to produce a conductive material and a cured product of the conductive material. A method in which conductive particles having interactive properties such as magnetism and a filler are kneaded together with a binder resin. A method in which a functional group that produces a bond such as a chemical bond or a coordinate bond is introduced into the surface of the conductive particles and the surface of the filler, and kneaded together with a binder resin.

  The storage elastic modulus of the cured product at 25 ° C. is preferably 1000 MPa or more, more preferably 1200 MPa or more, preferably 6000 MPa or less, more preferably 2500 MPa or less. When the storage elastic modulus at 25 ° C. of the cured product is equal to or more than the lower limit and equal to or less than the upper limit, when a connection structure is obtained by electrically connecting the electrodes, generation of cracks and warpage in the connection portion may occur. It can be more effectively prevented, and the adhesive strength of the connection portion can be more effectively increased.

  The storage elastic modulus at 25 ° C. of the cured product can be measured by a dynamic viscoelasticity measuring device (“RSA3” manufactured by TA Instruments). The measurement by the dynamic viscoelasticity measuring device is performed by using a measurement sample obtained by cutting the cured product into a size of 10 mm in length, 1 mm to 10 mm in width, and 15 mm to 50 mm in height, at a frequency of 10 Hz, a strain of 1%, and a temperature of -10. C. to 210.degree. C. and a temperature rising rate of 5.degree. C./min. From the measurement results, the storage modulus at 25 ° C. is calculated.

  The viscosity (η25) at 25 ° C. of the conductive material is preferably 5 Pa · s or more, more preferably 50 Pa · s or more, preferably 1000 Pa · s or less, more preferably 500 Pa · s or less. When the viscosity (η25) at 25 ° C. of the conductive material is equal to or higher than the lower limit and equal to or lower than the upper limit, insulation reliability between the electrodes can be more effectively increased, and conduction reliability between the electrodes can be further improved. It can be more effectively increased. The viscosity (η25) can be appropriately adjusted depending on the types and amounts of the components.

  The viscosity (η25) can be measured, for example, using an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.) at 25 ° C. and 5 rpm.

  The conductive material according to the present invention can be used as a conductive paste and a conductive film. When the conductive material according to the present invention is a conductive film, a film containing no conductive particles may be laminated on a conductive film containing conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film. The conductive material is suitably used for electrical connection of electrodes. The conductive material is preferably a circuit connecting material.

  Hereinafter, the cured product of the conductive material according to the present invention will be specifically described with reference to the drawings.

  FIG. 1 is a sectional view schematically showing a cured product of a conductive material according to one embodiment of the present invention.

  A cured material 51 of a conductive material shown in FIG. 1 includes conductive particles 1, a filler 3, and a cured material portion 52. The cured product 51 is obtained by heating and pressing the conductive material under the heating conditions of 150 ° C. and 10 seconds and the pressing condition of 3 MPa. In the cured product 51, the filler 3 is unevenly distributed. The filler may be disposed on the surface of the conductive particles, or may not be disposed. Preferably, the filler is disposed on a surface of the conductive particles. The filler is preferably attached on the surface of the conductive particles. The filler and the conductive particles are preferably contained in the conductive material in the form of conductive particles with filler in which the filler is disposed on the surface of the conductive particles. The filler and the conductive particles are preferably present in the cured product in the form of the conductive particles with the filler. By using a conductive material containing the conductive particles with the filler, even if the filler is added in a relatively large amount, the filler can be unevenly distributed around the conductive particles and arranged on the surface of the cured product. The ratio of the filler to be obtained can be reduced.

  The filler may be present in a region other than the first region (R1) described above. The filler is preferably present in a region other than the second region (R2) and in a region other than the third region (R3). In FIG. 1, the conductive particles 1 are schematically illustrated for convenience of illustration.

  Next, the conductive particles (conductive particles with filler) contained in the conductive material will be described below.

  FIG. 2 is a cross-sectional view showing conductive particles with filler used in the conductive material according to the present invention.

  The conductive particles with filler 1 shown in FIG. 2 include conductive particles 2 and a plurality of fillers 3 arranged on the surface of the conductive particles 2. It is preferable that the filler 3 is formed of a material having an insulating property.

  The conductive particles 2 have base particles 11 and conductive portions 12 arranged on the surface of the base particles 11. In the conductive particles 1 with filler, the conductive portion 12 is a conductive layer. The conductive portion 12 covers the surface of the base particle 11. The conductive particles 2 are coated particles in which the surfaces of the base particles 11 are coated with the conductive portions 12. The conductive particles 2 have a conductive portion 12 on the surface. In the conductive particles, the conductive portion may cover the entire surface of the base particle, or the conductive portion may cover a part of the surface of the base particle.

  Filler 3 is arranged on the surface of conductive particles 2. The plurality of fillers 3 are in contact with the surface of the conductive particles 2 and adhere to the surface of the conductive particles 2. The plurality of fillers 3 are in contact with the outer surface of the conductive part 12 of the conductive particles 2 and adhere to the outer surface of the conductive part 12.

  FIG. 3 is a cross-sectional view illustrating a first modified example of the conductive particles with a filler.

  The conductive particles with filler 1A shown in FIG. 3 include conductive particles 2A and a plurality of fillers 3 arranged on the surface of the conductive particles 2A.

  The conductive particles 2 and the conductive particles 2A are different between the conductive particles with a filler 1 and the conductive particles with a filler 1A.

  The conductive particles 2A include base particles 11, conductive portions 12A arranged on the surface of the base particles 11, and a plurality of core substances 13A. The conductive part 12A is a conductive layer. The conductive portion 12A is in contact with the base particles 11. The conductive portion 12A covers the surface of the base particle 11. The conductive particles 2A are coated particles in which the surfaces of the base particles 11 are coated with the conductive portions 12A. The conductive particles 2A have a conductive portion 12A on the surface.

  The conductive particles 2A have a plurality of protrusions 14A on the outer surface of the conductive portion 12A. The conductive portion 12A has a plurality of protrusions 14A on the outer surface. A plurality of core substances 13 </ b> A are arranged on the surface of the base particle 11. The plurality of core substances 13A are embedded in the conductive part 12A. The core material 13A is arranged inside the protrusion 14A. The conductive portion 12A covers a plurality of core materials 13A. The outer surface of the conductive portion 12A is raised by the plurality of core materials 13A, and the protrusions 14A are formed.

  FIG. 4 is a cross-sectional view showing a second modified example of the conductive particles with filler.

  4 includes conductive particles 2B and a plurality of fillers 3 arranged on the surface of the conductive particles 2B.

  The conductive particles 2A and the conductive particles 2B are different between the conductive particles 1A with the filler and the conductive particles 1B with the filler.

  The conductive particles 2 </ b> B have the base particles 11 and the conductive parts 12 </ b> B arranged on the surface of the base particles 11. The conductive particles 2B have no core substance.

  The presence / absence of a core substance is different between the conductive particles 2A and the conductive particles 2B, and as a result, the conductive portions are different. In the conductive particles with filler 1A, the core material 13A is used and the conductive portion 12A is formed so as to cover the core material 13A, whereas in the conductive particles with filler 1B, the core material is used. Instead, a conductive portion 12B is formed.

  The conductive portion 12B has a first portion and a second portion thicker than the first portion. The conductive particles 2B have a plurality of protrusions 14B on the outer surface of the conductive portion 12B. The conductive portion 12B has a plurality of protrusions 14B on the outer surface. The portion excluding the plurality of protrusions 14B is the first portion of the conductive portion 12B. The plurality of protrusions 14B are the above-described second portions where the thickness of the conductive portion 12B is large.

  Hereinafter, each component contained in the conductive material will be described.

(Conductive particles)
It is preferable that the conductive particles have base particles and a conductive portion disposed on the surface of the base particles. The conductive portion may have a single-layer structure or a multi-layer structure of two or more layers.

  The particle size of the conductive particles is preferably 1 μm or more, more preferably 2 μm or more, preferably 50 μm or less, more preferably 20 μm or less. When the particle size of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, when connecting the electrodes using the conductive particles, the contact area between the conductive particles and the electrodes is sufficiently large, In addition, it is difficult to form aggregated conductive particles when forming the conductive portion. In addition, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive portion does not easily peel off from the surface of the base particles.

  The particle size of the conductive particles is preferably an average particle size, and more preferably a number average particle size. The particle size of the conductive particles can be determined, for example, by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope, calculating the average value of the particle size of each conductive particle, or measuring the particle size distribution by laser diffraction. Required.

  When the particle diameter of the conductive particles is measured by a method of observing 50 arbitrary conductive particles with an electron microscope or an optical microscope in the conductive particles, the measurement can be performed, for example, as follows. A conductive particle inspection embedding resin is prepared by adding and dispersing the conductive particles to “Technobit 4000” manufactured by Kulzer so that the content of the conductive particles becomes 30% by weight. The cross section of the conductive particles is cut out using an ion milling apparatus (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass near the center of the conductive particles dispersed in the resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification is set to 25,000 times, 50 conductive particles are randomly selected, and each conductive particle is observed. The equivalent circle diameter of each conductive particle is measured, and arithmetically averaged to obtain the particle diameter of the conductive particle.

  The coefficient of variation (CV value) of the particle diameter of the conductive particles is preferably 10% or less, more preferably 5% or less. When the variation coefficient of the particle diameter of the conductive particles is equal to or less than the upper limit, the reliability of conduction between the electrodes and the reliability of insulation can be more effectively improved.

  The variation coefficient (CV value) can be measured as follows.

CV value (%) = (ρ / Dn) × 100
ρ: Standard deviation of particle size of conductive particles Dn: Average value of particle size of conductive particles

  The shape of the conductive particles is not particularly limited. The shape of the conductive particles may be spherical, non-spherical, flat, or the like.

  In 100% by weight of the conductive material, the content of the conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 80% by weight or less, more preferably 60% by weight. %, More preferably 40% by weight or less, particularly preferably 20% by weight or less, and most preferably 10% by weight or less. When the content of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, conduction reliability and insulation reliability between electrodes can be further improved.

Base particles:
Examples of the base particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The base particles are preferably base particles excluding metal particles, more preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. The base particles may be base particles excluding inorganic particles. The base particles may be core-shell particles including a core and a shell disposed on a surface of the core. The core may be an organic core, and the shell may be an inorganic shell.

  Various organic substances are suitably used as the material of the resin particles. Examples of the material of the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polycarbonate, polyamide, Phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, polyphenylene oxide, polyacetal, Polyimide, polyamide imide, polyetheretherketone, Polyether sulfone, divinyl benzene polymer, and divinylbenzene copolymer, and the like. Examples of the divinylbenzene-based copolymer include a divinylbenzene-styrene copolymer and a divinylbenzene- (meth) acrylate copolymer. Since the hardness of the resin particles can be easily controlled to a suitable range, the material of the resin particles is a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group. Is preferred.

  When the resin particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group includes a non-crosslinkable monomer. And a crosslinkable monomer.

  Examples of the non-crosslinkable monomer include styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, Alkyl (meth) acrylate compounds such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate, and glycidyl (meth) (Meth) acrylate compounds containing an oxygen atom such as acrylate; nitrile-containing monomers such as (meth) acrylonitrile; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether and propyl vinyl ether; vinyl acetate, vinyl butyrate, vinyl laurate, and stearin Acid vinyl ester compounds such as vinyl acid; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene And other halogen-containing monomers.

  Examples of the crosslinkable monomer include tetramethylolmethanetetra (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanedi (meth) acrylate, trimethylolpropanetri (meth) acrylate, and dipentane. Erythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Polyfunctional (meth) acrylate compounds such as acrylate, (poly) tetramethylene glycol di (meth) acrylate and 1,4-butanediol di (meth) acrylate; triallyl (iso) Nurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, and silane-containing monomers such as γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane Body and the like.

  The term "(meth) acrylate" refers to acrylate and methacrylate. The term "(meth) acryl" refers to acryl and methacryl.

  The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of the method include a method of performing suspension polymerization in the presence of a radical polymerization initiator, and a method of performing polymerization by swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles.

  When the base particles are inorganic particles or organic-inorganic hybrid particles other than metal particles, examples of the inorganic substance for forming the base particles include silica, alumina, barium titanate, zirconia, and carbon black. . Preferably, the inorganic substance is not a metal. The particles formed of the silica are not particularly limited. For example, after hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, baking is optionally performed. Particles obtained by performing the method are exemplified. Examples of the organic-inorganic hybrid particles include, for example, organic-inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

  The organic-inorganic hybrid particles are preferably core-shell type organic-inorganic hybrid particles having a core and a shell disposed on the surface of the core. Preferably, the core is an organic core. Preferably, the shell is an inorganic shell. From the viewpoint of effectively reducing the connection resistance between the electrodes, the base particles are preferably organic-inorganic hybrid particles having an organic core and an inorganic shell disposed on the surface of the organic core.

  Examples of the material for the organic core include the materials for the resin particles described above.

  Examples of the material for the inorganic shell include the inorganic substances mentioned as the material for the base particles described above. The material of the inorganic shell is preferably silica. The inorganic shell is preferably formed by forming a metal alkoxide into a shell by a sol-gel method on the surface of the core, and then firing the shell. The metal alkoxide is preferably a silane alkoxide. It is preferable that the inorganic shell is formed of a silane alkoxide.

  When the base particles are metal particles, examples of the metal as a material of the metal particles include silver, copper, nickel, silicon, gold, and titanium.

  The particle diameter of the base particles is preferably 0.6 μm or more, more preferably 0.8 μm or more, preferably 49.8 μm or less, more preferably 49.6 μm or less. When the particle diameter of the base particles is equal to or greater than the lower limit and equal to or less than the upper limit, small conductive particles can be obtained even if the distance between the electrodes is reduced and the thickness of the conductive layer is increased. Further, when the conductive portion is formed on the surface of the base material particles, it is difficult to aggregate, and it is difficult to form the aggregated conductive particles.

  The particle diameter of the base particles is particularly preferably 0.9 μm or more and 49.9 μm or less. When the particle diameter of the base particles is in the range of 0.9 μm or more and 49.9 μm or less, it becomes difficult to aggregate when forming the conductive portion on the surface of the base particles, and the aggregated conductive particles are formed. It becomes difficult.

  The particle diameter of the base particles indicates a number average particle diameter. The particle diameter of the base particles is determined using a particle size distribution measuring device or the like. The particle diameter of the base particles is preferably determined by observing 50 arbitrary base particles with an electron microscope or an optical microscope, calculating an average value, or performing a laser diffraction particle size distribution measurement. In the case of measuring the particle diameter of the base particles in the conductive particles, the measurement can be performed, for example, as follows.

  A conductive particle inspection embedding resin is prepared by adding and dispersing the conductive particles to “Technobit 4000” manufactured by Kulzer so that the content of the conductive particles becomes 30% by weight. The cross section of the conductive particles is cut out using an ion milling apparatus (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass near the center of the conductive particles dispersed in the resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 25,000 times, 50 conductive particles were randomly selected, and the base particles of each conductive particle were observed. I do. The circle-equivalent diameter of the base particles in each conductive particle is measured as a particle diameter, and arithmetically averaged to obtain the particle diameter of the base particles.

Conductive part:
Preferably, the conductive portion includes a metal. The metal constituting the conductive portion is not particularly limited. Examples of the metal include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium, and alloys thereof. Further, tin-doped indium oxide (ITO) may be used as the metal. One of the above metals may be used alone, or two or more thereof may be used in combination. From the viewpoint of further lowering the connection resistance between the electrodes, an alloy containing tin, nickel, palladium, copper or gold is preferable, and nickel or palladium is more preferable.

  From the viewpoint of effectively improving conduction reliability, it is preferable that the conductive portion and the outer surface portion of the conductive portion contain nickel. The content of nickel in 100% by weight of the conductive portion containing nickel is preferably 10% by weight or more, more preferably 50% by weight or more, still more preferably 60% by weight or more, further preferably 70% by weight or more, and particularly preferably. Is 90% by weight or more. The content of nickel in the conductive portion containing 100% by weight of nickel may be 97% by weight or more, 97.5% by weight or more, or 98% by weight or more.

  Note that a hydroxyl group is often present on the surface of the conductive portion due to oxidation. Generally, a hydroxyl group is present on the surface of a conductive portion formed of nickel due to oxidation. A filler can be disposed on the surface of the conductive portion having such a hydroxyl group (the surface of the conductive particles) via a chemical bond.

  The conductive portion may be formed of one layer. The conductive portion may be formed of a plurality of layers. That is, the conductive portion may have a laminated structure of two or more layers. When the conductive portion is formed of a plurality of layers, the metal forming the outermost layer is preferably gold, nickel, palladium, copper or an alloy containing tin and silver, and is preferably gold. More preferred. When the metal constituting the outermost layer is one of these preferable metals, the connection resistance between the electrodes is further reduced. Further, when the metal constituting the outermost layer is gold, the corrosion resistance is further improved.

  The method for forming the conductive portion on the surface of the base particles is not particularly limited. As a method of forming the conductive portion, for example, a method by electroless plating, a method by electroplating, a method by physical collision, a method by mechanochemical reaction, a method by physical vapor deposition or physical adsorption, and a metal powder or A method in which a paste containing a metal powder and a binder is coated on the surface of the base particles is exemplified. The method for forming the conductive portion is preferably a method by electroless plating, electroplating or physical collision. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering. In the method based on the physical collision, for example, a sheeter composer (manufactured by Tokuju Kosakusho) is used.

  The thickness of the conductive portion is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 10 μm or less, more preferably 1 μm or less, and still more preferably 0.3 μm or less. When the thickness of the conductive portion is equal to or greater than the lower limit and equal to or less than the upper limit, sufficient conductivity is obtained, and the conductive particles are not too hard, and the conductive particles are sufficiently formed at the time of connection between the electrodes. Can be deformed.

  When the conductive portion is formed of a plurality of layers, the thickness of the outermost conductive portion is preferably 0.001 μm or more, more preferably 0.01 μm or more, preferably 0.5 μm or less, more preferably Is 0.1 μm or less. When the thickness of the conductive portion of the outermost layer is equal to or more than the lower limit and equal to or less than the upper limit, the conductive portion of the outermost layer becomes uniform, the corrosion resistance becomes sufficiently high, and the connection resistance between the electrodes is sufficiently low. can do.

  The thickness of the conductive portion can be measured, for example, by observing a cross section of the conductive particles using a transmission electron microscope (TEM).

Core material:
The conductive particles preferably have a plurality of protrusions on the outer surface of the conductive portion. An oxide film is often formed on the surface of the electrode connected by the conductive particles. When conductive particles having protrusions on the surface of the conductive portion are used, the oxide film can be effectively removed by the protrusions by arranging the conductive particles between the electrodes and pressing them. For this reason, the electrode and the conductive portion are more securely in contact with each other, and the connection resistance between the electrodes is further reduced. Further, at the time of connection between the electrodes, the filler between the conductive particles and the electrodes can be effectively eliminated by the protrusions of the conductive particles. For this reason, the conduction reliability between the electrodes is further improved.

  As a method of forming the projections, a method of forming a conductive portion by electroless plating after attaching a core substance to the surface of the base particle, and a method of forming a conductive portion by electroless plating on the surface of the base particle After that, a method of attaching a core substance and further forming a conductive portion by electroless plating may be used. As another method of forming the above-mentioned projections, after forming a first conductive portion on the surface of the base particles, a core substance is disposed on the first conductive portion, and then the second conductive portion is formed. And a method of adding a core substance in the middle of forming a conductive part (such as the first conductive part or the second conductive part) on the surface of the base particles. Also, in order to form projections, without using the above-mentioned core substance, after forming a conductive portion on the base particles by electroless plating, plating is deposited in the form of protrusions on the surface of the conductive portion. May be used to form a conductive portion.

  As a method of attaching the core substance to the surface of the base particles, for example, in a dispersion of the base particles, the core substance is added, the core substance is accumulated on the surface of the base particles by van der Waals force, Examples of the method include a method of attaching the core substance to a container containing the base particles, and a method of attaching the core substance to the surface of the base particles by mechanical action such as rotation of the container. From the viewpoint of controlling the amount of the core substance to be attached, the method of attaching the core substance to the surface of the base particles may be a method of accumulating and attaching the core substance to the surface of the base particles in the dispersion. preferable.

  Examples of the substance constituting the core substance include a conductive substance and a non-conductive substance. Examples of the conductive material include metals, metal oxides, conductive non-metals such as graphite, and conductive polymers. Examples of the conductive polymer include polyacetylene. Examples of the non-conductive substance include silica, alumina, and zirconia. From the viewpoint of further improving the conduction reliability between the electrodes, it is preferable that the core substance is a metal.

  The metal is not particularly limited. Examples of the metal include metals such as gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, and tin-lead. Alloys composed of two or more metals such as alloys, tin-copper alloys, tin-silver alloys, tin-lead-silver alloys, and tungsten carbide are exemplified. From the viewpoint of further improving the conduction reliability between the electrodes, the metal is preferably nickel, copper, silver or gold. The metal may be the same as or different from the metal forming the conductive part (conductive layer).

  The shape of the core material is not particularly limited. The shape of the core material is preferably a lump. Examples of the core material include a particulate mass, an aggregate of a plurality of fine particles aggregated, and an irregular mass.

  The particle diameter (average particle diameter) of the core substance is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, more preferably 0.2 μm or less. When the particle diameter of the core material is not less than the lower limit and not more than the upper limit, the connection resistance between the electrodes can be effectively reduced.

  The particle diameter of the core substance is preferably an average particle diameter, and more preferably a number average particle diameter. The particle diameter of the core substance is, for example, observing 50 arbitrary core substances with an electron microscope or an optical microscope, calculating the average value of the particle diameter of each core substance, and performing laser diffraction type particle size distribution measurement. Required by

  In the case where the particle diameter of the core material is measured by a method of observing 50 arbitrary core materials of the conductive particles with an electron microscope or an optical microscope, the measurement can be performed, for example, as follows. A conductive particle inspection embedding resin is prepared by adding and dispersing the conductive particles to “Technobit 4000” manufactured by Kulzer so that the content of the conductive particles becomes 30% by weight. The cross section of the conductive particles is cut out using an ion milling apparatus (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass near the center of the conductive particles dispersed in the resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 200,000, 50 conductive particles were randomly selected, and the core material of each conductive particle was observed. I do. The equivalent circle diameter of the core material in each conductive particle is measured and arithmetically averaged to obtain the particle diameter of the core material of the conductive particles.

Filler:
The conductive material includes a plurality of fillers. The filler is preferably a stress relaxing filler, and is preferably a stress relaxing particle. Preferably, the filler is disposed on a surface of the conductive particles. When a conductive material containing conductive particles with filler, in which the filler is disposed on the surface of the conductive particles, is used as a material for the connection portion, cracks and warpage in the connection portion can be effectively prevented from occurring, In addition, the adhesive strength of the connection portion can be effectively increased. Specifically, by using a conductive material containing the conductive particles with filler as a material of the connection portion, even if the filler is added in a relatively large amount to the connection portion, the filler is unevenly distributed around the conductive particles. And the proportion of the filler disposed on the surface of the connection portion can be reduced. As a result, when a connection structure is obtained by electrically connecting the electrodes, it is possible to effectively prevent the occurrence of cracks and warpage in the connection portion and to effectively increase the adhesive force of the connection portion. Both what you can do and what you can do.

  The filler preferably has an insulating property, and is preferably formed of a material having an insulating property. In this case, when the conductive particles with filler are used for connection between electrodes, a short circuit between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles with a filler come into contact with each other, a filler is present between the plurality of electrodes, so that a short circuit between horizontally adjacent electrodes, not between upper and lower electrodes, can be prevented. At the time of connection between the electrodes, the filler between the conductive portion of the conductive particles and the electrode can be easily removed by pressurizing the conductive particles with the filler with the two electrodes. Further, in the case of conductive particles having a plurality of protrusions on the outer surface of the conductive portion, the filler between the conductive portion of the conductive particles and the electrode can be more easily removed.

  The particle size of the filler can be appropriately selected depending on the particle size of the conductive particles, the use of the conductive particles, and the like. The particle diameter of the filler is preferably 100 nm or more, more preferably 200 nm or more, preferably 2000 nm or less, more preferably 800 nm or less. When the particle diameter of the filler satisfies the lower limit, when the conductive particles with filler are dispersed in the conductive material, it is difficult for the conductive portions of the plurality of conductive particles with filler to contact each other. When the particle diameter of the filler satisfies the upper limit, in connecting the electrodes, in order to eliminate the filler between the electrode and the conductive particles, it is not necessary to increase the pressure too high, and heat to a high temperature. There is no need. When the particle size of the filler satisfies the lower limit and the upper limit, the insulation reliability can be more effectively improved when the electrodes are electrically connected.

  The particle diameter of the filler is preferably an average particle diameter, and more preferably a number average particle diameter. The particle size of the filler is determined using a particle size distribution measuring device or the like. The particle size of the filler is preferably determined by observing 50 arbitrary fillers with an electron microscope or an optical microscope, calculating an average value, or performing a laser diffraction type particle size distribution measurement. In the case of measuring the particle diameter of the filler in the conductive particles with a filler, for example, the measurement can be performed as follows.

  The conductive particles with a filler are added to “Technobit 4000” manufactured by Kulzer Co., Ltd. so as to have a content of 30% by weight, and dispersed to prepare an embedded resin for conductive particle inspection. Using an ion milling apparatus (“IM4000” manufactured by Hitachi High-Technologies Corporation), a section of the conductive particles with filler is cut out so as to pass near the center of the conductive particles with filler dispersed in the resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 50,000 times, 50 conductive particles with filler were randomly selected, and the filler of each conductive particle with filler was selected. Observe. The equivalent circle diameter of the filler in each filler-added conductive particle is measured as a particle diameter, and the arithmetic average thereof is used as the particle diameter of the filler.

  The ratio of the particle size of the conductive particles to the particle size of the filler (particle size of the conductive particles / particle size of the filler) is preferably 3.75 or more, more preferably 8.3 or more, and preferably It is 120 or less, more preferably 25 or less. When the ratio (particle diameter of conductive particles / particle diameter of filler) is equal to or more than the lower limit and equal to or less than the upper limit, when the electrodes are electrically connected, insulation reliability is more effectively increased. Can be.

  The storage elastic modulus at 25 ° C. of the filler is preferably 500 MPa or more, more preferably 1000 MPa or more, preferably 1700 MPa or less, more preferably 1500 MPa or less. When the storage elastic modulus at 25 ° C. of the filler is equal to or greater than the lower limit and equal to or less than the upper limit, when a connection structure is obtained by electrically connecting the electrodes, the occurrence of cracks and warpage in the connection portion is more increased. This can be more effectively prevented, and the adhesive strength of the connection portion can be more effectively increased.

  The storage elastic modulus at 25 ° C. of the filler can be measured by a dynamic viscoelasticity measuring device (“RSA3” manufactured by TA Instruments). The measurement by the above dynamic viscoelasticity measuring device is performed using a measurement sample having a length of 10 mm, a width of 1 mm to 10 mm, and a thickness of 15 mm to 50 mm, a frequency of 10 Hz, a strain of 1%, a temperature of -10 ° C to 210 ° C, and a heating rate. It is performed under the condition of 5 ° C./min. From the measurement results, the storage modulus at 25 ° C. is calculated. The measurement sample is prepared using the same raw material as the filler.

  Examples of the filler material include an insulating resin. Examples of the insulating resin include materials of resin particles that can be used as base particles. The filler may be the resin particles described above.

  Specific examples of the insulating resin as the filler material include polyolefin compounds, (meth) acrylate polymers, (meth) acrylate copolymers, block polymers, thermoplastic resins, crosslinked thermoplastic resins, and thermosetting resins. Resins and water-soluble resins.

  Examples of the polyolefin compound include polyethylene, an ethylene-vinyl acetate copolymer, and an ethylene-acrylate copolymer. Examples of the (meth) acrylate polymer include polymethyl (meth) acrylate, polyethyl (meth) acrylate, and polybutyl (meth) acrylate. Examples of the block polymer include polystyrene, styrene-acrylate copolymer, SB-type styrene-butadiene block copolymer, SBS-type styrene-butadiene block copolymer, and hydrogenated products thereof. Examples of the thermoplastic resin include a vinyl polymer and a vinyl copolymer. Examples of the thermosetting resin include an epoxy resin, a phenol resin, and a melamine resin. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide, and methyl cellulose. Further, a chain transfer agent may be used for adjusting the degree of polymerization. Examples of the chain transfer agent include thiol and carbon tetrachloride.

  Examples of a method for disposing the filler on the surface of the conductive particles include a chemical method and a physical or mechanical method. Examples of the chemical method include an interfacial polymerization method, a suspension polymerization method in the presence of particles, and an emulsion polymerization method. Examples of the physical or mechanical method include spray drying, hybridization, electrostatic adhesion, spraying, dipping, and vacuum deposition. From the viewpoint of more effectively improving the insulation reliability when the electrodes are electrically connected, the method of disposing the filler on the surface of the conductive particles is preferably a physical method.

  The outer surface of the conductive particles and the outer surface of the filler may each be coated with a compound having a reactive functional group. The outer surface of the conductive particles and the outer surface of the insulating particles may not be directly chemically bonded, or may be chemically bonded indirectly by a compound having a reactive functional group. After introducing a carboxyl group to the outer surface of the conductive particles, the carboxyl group may be chemically bonded to a functional group on the outer surface of the filler via a polymer electrolyte such as polyethyleneimine.

  In the conductive particles with a filler, two or more kinds of fillers having different particle diameters may be used in combination. By using two or more kinds of fillers with different particle diameters in combination, the small particle diameter filler enters the gap covered by the large particle diameter filler, and the filler is more efficiently arranged on the surface of the conductive particles. can do.

  The coefficient of variation (CV value) of the particle size of the filler is preferably 20% or less. When the variation coefficient of the particle diameter of the filler is equal to or less than the upper limit, the thickness of the filler of the obtained conductive particles with filler becomes more uniform, and the pressure is more easily applied uniformly at the time of conductive connection. And the connection resistance between the electrodes can be further reduced.

  The variation coefficient (CV value) can be measured as follows.

CV value (%) = (ρ / Dn) × 100
ρ: standard deviation of the particle size of the filler Dn: average value of the particle size of the filler

  The shape of the filler is not particularly limited. The filler may have a spherical shape, a shape other than a spherical shape, or a flat shape.

  In 100% by weight of the conductive material, the content of the filler is preferably 0.5% by weight or more, more preferably 5% by weight or more, preferably 45% by weight or less, more preferably 20% by weight or less. . When the content of the filler is equal to or more than the lower limit and equal to or less than the upper limit, when a connection structure is obtained by electrically connecting the electrodes, the occurrence of cracks and warpage in the connection portion is more effectively achieved. In addition, the bonding strength of the connection portion can be more effectively increased.

(Binder resin)
The conductive material contains a binder resin. The binder resin is not particularly limited. As the binder resin, a known insulating resin is used. The binder resin preferably contains a thermoplastic component (thermoplastic compound) or a curable component, and more preferably contains a curable component. Examples of the curable component include a photocurable component and a thermosetting component. The photocurable component preferably contains a photocurable compound and a photopolymerization initiator. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent.

  Examples of the binder resin include a vinyl resin, a thermoplastic resin, a curable resin, a thermoplastic block copolymer, and an elastomer. The binder resin may be used alone or in combination of two or more.

  Examples of the vinyl resin include a vinyl acetate resin, an acrylic resin, and a styrene resin. Examples of the thermoplastic resin include a polyolefin resin, an ethylene-vinyl acetate copolymer, and a polyamide resin. Examples of the curable resin include an epoxy resin, a urethane resin, a polyimide resin, and an unsaturated polyester resin. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin may be used in combination with a curing agent. Examples of the thermoplastic block copolymer include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, and styrene-isoprene. -Hydrogenated products of styrene block copolymers. Examples of the elastomer include a styrene-butadiene copolymer rubber and an acrylonitrile-styrene block copolymer rubber.

  The conductive material may be, for example, a filler, a bulking agent, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, and a light stabilizer, in addition to the conductive particles and the binder resin. And various additives such as an agent, an ultraviolet absorber, a lubricant, an antistatic agent and a flame retardant.

  A method for dispersing the conductive particles in the binder resin may be a conventionally known dispersion method, and is not particularly limited. Examples of a method for dispersing the conductive particles in the binder resin include the following methods. A method in which the conductive particles are added to the binder resin, and then kneaded and dispersed with a planetary mixer or the like. A method in which the conductive particles are uniformly dispersed in water or an organic solvent using a homogenizer or the like, then added to the binder resin, and kneaded and dispersed with a planetary mixer or the like. After diluting the binder resin with water or an organic solvent, the conductive particles are added, and the mixture is kneaded and dispersed by a planetary mixer or the like.

  In 100% by weight of the conductive material, the content of the binder resin is preferably 10% by weight or more, more preferably 30% by weight or more, further preferably 50% by weight or more, particularly preferably 70% by weight or more, and preferably Is 99.99% by weight or less, more preferably 99.9% by weight or less. When the content of the binder resin is equal to or more than the lower limit and equal to or less than the upper limit, the conductive particles are efficiently arranged between the electrodes, and the connection reliability of the connection target member connected by the conductive material is further increased. Can be.

(Connection structure)
The connection structure according to the present invention includes a first connection target member having a first electrode on the surface, a second connection target member having a second electrode on the surface, the first connection target member, And a connecting portion connecting the second connection target member. In the connection structure according to the present invention, the material of the connection portion is a conductive material including a plurality of conductive particles, a plurality of fillers, and a binder resin. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by the conductive particles. In the connection structure according to the present invention, in the total number 100% of the fillers contained in the connection portion, a distance of 1/2 of the particle diameter of the conductive particles from the surface of the conductive particles to the outside. Up to 70% or more.

  In the connection structure according to the present invention, since the above-described configuration is provided, it is possible to effectively prevent the occurrence of cracks and warpage in the connection portion, and to effectively increase the adhesive force of the connection portion. Can be.

  A connection structure can be obtained by electrically connecting electrodes on a substrate using an anisotropic conductive material. In manufacturing the connection structure, stress may be applied to the connection target member or the connection portion due to a difference in the material of the connection target member, the heat history of the connection portion, or the like. This stress may cause cracks and warpage in the connection target member and the connection portion.

  Examples of a method for preventing the occurrence of cracks and warpage in the connection target member and the connection portion include a method in which stress relaxation particles such as silicone particles are added to the connection portion to reduce internal stress. However, in order to prevent the occurrence of cracks and warpage by using the stress relaxing particles, it is necessary to add a relatively large amount of the stress relaxing particles to the connection portion. If a relatively large amount of the stress relaxing particles is added to the connecting portion, the stress relaxing particles are also arranged on the surface of the connecting portion, and the ratio of the binder resin on the surface of the connecting portion relatively decreases. Since the adhesive strength of the connecting part is expressed by the binder resin on the surface of the connecting part, if the ratio of the binder resin on the surface of the connecting part relatively decreases, the adhesive strength of the connecting part decreases, and the connecting part is connected. It may be difficult to adhere to the target member. With a conventional anisotropic conductive material, it is difficult to achieve both the prevention of cracks and warpage in the connection portion and the enhancement of the adhesive strength of the connection portion.

  The present inventors have found that by using a specific conductive material, it is possible to both prevent the occurrence of cracks and warpage in the connection portion and increase the adhesive strength of the connection portion. According to the present invention, a relatively large amount of filler exhibiting a stress relaxation effect can be added to the connection portion, and the filler can be prevented from being arranged on the surface of the connection portion. As a result, when a connection structure is obtained by electrically connecting the electrodes, it is possible to effectively prevent the occurrence of cracks and warpage in the connection portion, and to effectively reduce the adhesive force of the connection portion. Can be enhanced.

  In the present invention, use of a specific conductive material greatly contributes to obtaining the above-described effects.

  In the connection structure according to the present invention, a distance of 1/2 of the particle diameter of the conductive particles from the surface of the conductive particles to the outside in 100% of the total number of the fillers contained in the connection portion. The ratio of the number of the fillers existing in the region up to (the fourth region, R4) is 70% or more. The proportion of the number of the fillers present in the fourth region (R4) is preferably 80% or more, more preferably 85% or more, based on 100% of the total number of the fillers contained in the connection portion. The proportion of the number of the fillers present in the fourth region (R4) in the total number of the fillers contained in the cured product of 100% may be 75% or less. The upper limit of the ratio of the number of the fillers present in the fourth region (R4) to 100% of the total number of the fillers included in the connection portion is not particularly limited. The proportion of the number of the fillers present in the fourth region (R4) in the total number of the fillers included in the connection portion may be 96% or less. The ratio of the number of the fillers existing in the fourth region (R4) is the ratio of the number of the fillers in which at least a part of the filler is included in the fourth region (R4). When the ratio of the number of the filler present in the fourth region (R4) is equal to or more than the lower limit, generation of cracks and warpage in the connection portion can be more effectively prevented, and the connection portion can be prevented. Can be more effectively increased. The fourth region (R4) is a region between the outer surface of the conductive particle 1 and the broken line L4 in FIG. The distance between the outer surface of the conductive particles 1 and the broken line L4 is の of the particle diameter of the conductive particles 1.

  The proportion of the number of the fillers present in the fourth region (R4) in the total number 100% of the fillers contained in the connection portion (cured product) is determined by scanning the connection portion in the connection structure with a scanning electron microscope. It can be calculated by observation using (SEM) or the like. Specifically, the connection portion of the connection structure is cut with a cross section polisher (CP) or the like, and the cross section of the connection portion is observed with a scanning electron microscope. By measuring the number of the fillers in the fourth region (R4) in the cut surface of the connection portion and the number of the fillers in the region other than the fourth region (R4), the ratio of the number of the fillers is measured. Can be calculated.

  As a method of setting the ratio of the number of the fillers present in the fourth region (R4) in the total number of the fillers included in the connection portion to 100% or more to 70% or more, the conductive material (filled A method of manufacturing a connection structure using a conductive material containing conductive particles).

  Specifically, as a method of setting the ratio of the number of the fillers present in the fourth region (R4) to the total number of the fillers included in the connection portion (cured product) of 100% to 70% or more. Examples include the following methods. A method for producing conductive particles with filler in which a filler is attached on the surface of conductive particles by a hybridizer or the like, and producing a conductive material and a cured product of the conductive material using the conductive particles with filler. A method in which conductive particles and a filler are kneaded in a binder resin, and an external magnetic field is applied to generate an attractive force between the conductive particles and the filler. A method in which conductive particles having interactive properties such as magnetism and a filler are kneaded together with a binder resin. A method in which a functional group that produces a bond such as a chemical bond or a coordinate bond is introduced into the surface of the conductive particles and the surface of the filler, and kneaded together with a binder resin. A method in which a filler is attached to conductive particles by chemical bonding or intermolecular attraction, and then the conductive particles to which the filler is attached are dispersed in a binder resin.

  A surface on one side in the thickness direction of the connection portion is a first surface, and a surface on the other side in the thickness direction of the connection portion is a second surface.

  Of the total number of fillers contained in the connection portion, 100% of the particle diameter of the conductive particles from the surface of the connection portion (the surface on one side, the first surface) to the inside in the total number of 100%. The proportion of the number of the fillers existing in the region (the fifth region, R5) up to the distance is preferably less than 50%, more preferably 20% or less. The lower limit of the ratio of the number of the fillers present in the fifth region (R5) to 100% of the total number of the fillers included in the connection portion is not particularly limited. The proportion of the number of the fillers present in the fifth region (R5) in the total number of the fillers included in the connection portion, which is 100%, may be 5% or more. The number of the fillers present in the fifth region (R5) is a ratio of the number of the fillers in which at least a part of the filler is included in the fifth region (R5). When the number of the fillers present in the fifth region (R5) is equal to or less than the upper limit, generation of cracks and warpage in the connection portion can be more effectively prevented, and adhesion of the connection portion can be prevented. The power can be more effectively increased. The fifth region (R5) is a region between the first surface 84a and the broken line L5 in FIG. The distance between the first surface 84a and the broken line L5 is １ ／ of the particle diameter of the conductive particles 1.

  Of the total number of the fillers contained in the connection portion, 100% of the particle diameter of the conductive particles from the surface of the connection portion (the surface on the other side, the second surface) to the inside in 100%. The ratio of the number of the fillers existing in the region up to the distance (sixth region, R6) is preferably less than 50%, more preferably 20% or less. The lower limit of the ratio of the number of the fillers present in the sixth region (R6) to 100% of the total number of the fillers contained in the connection portion is not particularly limited. The proportion of the number of the fillers present in the sixth region (R6) in the total number of the fillers included in the connection portion, which is 100%, may be 5% or more. The ratio of the number of the fillers present in the sixth region (R6) is the ratio of the number of the fillers in which at least a part of the filler is included in the sixth region (R6). When the ratio of the number of the filler present in the sixth region (R6) is equal to or less than the upper limit, generation of cracks and warpage in the connection portion can be more effectively prevented, and the connection portion can be prevented. Can be more effectively increased. The sixth region (R6) is a region between the second surface 84b and the broken line L6 in FIG. The distance between the second surface 84b and the broken line L6 is １ ／ of the particle diameter of the conductive particles 1.

  The proportion of the number of the fillers present in the fifth region (R5) or the sixth region (R6) in the total number of the fillers contained in the connection portion in 100% is determined by the connection portion in the connection structure. Can be calculated by observing using a scanning electron microscope (SEM) or the like. Specifically, the connection portion of the connection structure is cut with a cross section polisher (CP) or the like, and the cross section of the connection portion is observed with a scanning electron microscope. The number of fillers in the fifth region (R5) in the cut surface of the connection portion and the number of fillers in regions other than the fifth region (R5), or the number of fillers in the cut surface of the connection portion By measuring the number of fillers in the sixth region (R6) and the number of fillers in regions other than the sixth region (R6), the ratio of the number of fillers can be calculated.

  The number of the fillers in the fifth region (R5) or the sixth region (R6) in the total number of the fillers contained in the connection portion (cured product) of 100% is controlled to the preferred range described above. Examples of the method include a method of manufacturing a connection structure using the above-described conductive material (conductive material including conductive particles with a filler).

  Specifically, the number of the fillers in the fifth region (R5) or the sixth region (R6) in 100% of the total number of the fillers contained in the connection portion (cured product) is calculated as follows. As a method of controlling to a preferable range, the following supplementary method is mentioned. A method for producing conductive particles with filler in which a filler is attached on the surface of conductive particles by a hybridizer or the like, and producing a conductive material and a cured product of the conductive material using the conductive particles with filler. A method in which conductive particles having interactive properties such as magnetism and a filler are kneaded together with a binder resin. A method in which a functional group that produces a bond such as a chemical bond or a coordinate bond is introduced into the surface of the conductive particles and the surface of the filler, and kneaded together with a binder resin. A method in which a filler is attached to conductive particles by chemical bonding or intermolecular attraction, and then the conductive particles to which the filler is attached are dispersed in a binder resin. A method in which conductive particles and fillers are kneaded in a binder resin to form a sheet, and then another sheet is placed on the surface of the sheet and cured. In particular, after kneading the conductive particles and filler in a binder resin to form a sheet, the method of placing and curing another sheet on the surface of the sheet is combined with the other method described above to form the above form. It can be achieved more effectively.

  The storage elastic modulus at 25 ° C. of the connection portion is preferably 1000 MPa or more, more preferably 1200 MPa or more, preferably 6000 MPa or less, more preferably 2500 MPa or less. When the storage elastic modulus at 25 ° C. of the connection portion is equal to or more than the lower limit and equal to or less than the upper limit, generation of cracks and warpage in the connection portion can be more effectively prevented, and the adhesive force of the connection portion Can be more effectively increased.

  The storage elastic modulus at 25 ° C. of the connection portion can be measured by a dynamic viscoelasticity measurement device (“RSA3” manufactured by TA Instruments). The measurement by the dynamic viscoelasticity measuring device is performed by using a measurement sample obtained by cutting the connection portion into a size of 10 mm in length, 1 mm to 10 mm in width, and 15 mm to 50 mm in thickness, at a frequency of 10 Hz, a strain of 1%, and a temperature of -10. C. to 210.degree. C. and a temperature rising rate of 5.degree. C./min. From the measurement results, the storage modulus at 25 ° C. is calculated.

  FIG. 5 is a cross-sectional view schematically showing a connection structure using the conductive material according to the present invention.

  The connection structure 81 illustrated in FIG. 5 includes a first connection target member 82, a second connection target member 83, and a connection unit that connects the first connection target member 82 and the second connection target member 83. 84. The connection portion 84 is formed of a conductive material including the conductive particles 1, the filler 3, and the binder resin. The filler may be disposed on the surface of the conductive particles, or may not be disposed. Preferably, the filler is disposed on a surface of the conductive particles. The filler is preferably attached on the surface of the conductive particles. The filler and the conductive particles are preferably contained in the conductive material in the form of conductive particles with filler in which the filler is disposed on the surface of the conductive particles. By using the conductive material containing the filler-containing conductive particles as the material of the connection portion, even if the filler is added to the connection portion in a relatively large amount, the filler can be unevenly distributed around the conductive particles, The ratio of the filler disposed on the surface of the connection portion can be reduced.

  The connection portion 84 is preferably formed by curing a conductive material including a plurality of conductive particles with filler. The filler may be present in a region other than the above-described fourth region (R4). The filler is preferably present in a region other than the fifth region (R5) and in a region other than the sixth region (R6). In FIG. 5, the conductive particles 1 are schematically illustrated for convenience of illustration. The conductive particles 1A or 1B may be used instead of the conductive particles 1.

  The first connection target member 82 has a plurality of first electrodes 82a on the surface (upper surface). The second connection target member 83 has a plurality of second electrodes 83a on the surface (lower surface). The first electrode 82a and the second electrode 83a are electrically connected by one or more conductive particles 1. Therefore, the first connection target member 82 and the second connection target member 83 are electrically connected by the conductive particles 1.

  The method for manufacturing the connection structure is not particularly limited. As an example of a method for manufacturing a connection structure, the conductive material is arranged between a first connection target member and a second connection target member, and after obtaining a laminate, the laminate is heated and pressed. Method and the like. The pressure of the thermocompression bonding is preferably 40 MPa or more, more preferably 60 MPa or more, preferably 90 MPa or less, more preferably 70 MPa or less. The heating temperature of the thermocompression bonding is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, preferably 140 ° C. or lower, more preferably 120 ° C. or lower. When the pressure and temperature of the thermocompression bonding are equal to or higher than the lower limit and equal to or lower than the upper limit, the filler can be easily detached from the surface of the conductive particle with the filler at the time of conductive connection, and the conduction reliability between the electrodes is further enhanced. Can be.

  When the laminate is heated and pressed, the filler present between the conductive particles and the first and second electrodes can be eliminated. For example, at the time of the heating and pressurization, the conductive particles, the filler present between the first electrode and the second electrode, the surface of the conductive particles with filler from the surface Easily desorbs. At the time of the heating and pressurization, a part of the filler may be detached from the surface of the conductive particles with filler, and the surface of the conductive portion may be partially exposed. A portion where the surface of the conductive portion is exposed contacts the first electrode and the second electrode, thereby electrically connecting the first electrode and the second electrode via the conductive particles. be able to.

  The first connection target member and the second connection target member are not particularly limited. Specifically, the first connection target member and the second connection target member include electronic components such as a semiconductor chip, a semiconductor package, an LED chip, an LED package, a capacitor and a diode, a resin film, a printed board, and a flexible print. Examples include electronic components such as a circuit board such as a board, a flexible flat cable, a rigid flexible board, a glass epoxy board, and a glass board. The first connection target member and the second connection target member are preferably electronic components.

  Examples of the electrodes provided on the connection target member include metal electrodes such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, a SUS electrode, and a tungsten electrode. When the member to be connected is a flexible printed circuit board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, a silver electrode, or a copper electrode. When the member to be connected is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, or a tungsten electrode. Note that when the electrode is an aluminum electrode, the electrode may be an electrode formed only of aluminum, or may be an electrode in which an aluminum layer is stacked on a surface of a metal oxide layer. Examples of the material of the metal oxide layer include indium oxide doped with a trivalent metal element, zinc oxide doped with a trivalent metal element, and the like. Examples of the trivalent metal element include Sn, Al, and Ga.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited only to the following examples.

(Example 1)
(1) Preparation of Conductive Particles Resin particles (base particles) (particle diameter: 3.00 μm) formed of a copolymer resin of tetramethylolmethanetetraacrylate and divinylbenzene were prepared. After 10 parts by weight of the base particles were dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, the base particles were taken out by filtering the solution. Next, the base particles were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surfaces of the base particles. After sufficiently washing the substrate particles having activated surfaces, the dispersion was added to 500 parts by weight of distilled water and dispersed to obtain a dispersion. Next, 1 g of a nickel particle slurry (average particle diameter: 0.15 μm) was added to the dispersion over 3 minutes to obtain a suspension containing the base material particles to which the core substance was attached.

  A nickel plating solution (pH 8.5) containing 0.35 mol / L of nickel sulfate, 1.38 mol / L of dimethylamine borane, and 0.5 mol / L of sodium citrate was prepared.

  While stirring the obtained suspension at 70 ° C., the nickel plating solution was gradually dropped into the suspension, and electroless nickel plating was performed. Then, the particles are taken out by filtering the suspension, washed with water, and dried to form conductive particles (conductive layer (nickel-boron layer, 0.15 μm thickness) formed on the surface of the base particles) ( (Particle size 3.30 μm).

(2) Preparation of Filler The following composition was placed in a 1000 mL separable flask equipped with a four-port separable cover, a stirring blade, a three-way cock, a cooling tube, and a temperature probe. Distilled water was added so as to give a weight%, and the mixture was stirred at 200 rpm and polymerized at 50 ° C. for 5 hours under a nitrogen atmosphere. The composition comprises 45 mmol of glycidyl methacrylate, 380 mmol of methyl methacrylate, 13 mmol of ethylene glycol dimethacrylate, 0.5 mmol of acid phosphooxypolyoxyethylene glycol methacrylate, and 2,2′-azobis {2- [N- (2- Carboxyethyl) amidino] propane｝ 1 mmol. After completion of the reaction, the mixture was freeze-dried to obtain a filler (particle diameter: 360 nm) having a P-OH group derived from acid phosphooxypolyoxyethylene glycol methacrylate on the surface.

(3) Preparation of Conductive Particle with Filler The filler obtained above was dispersed in distilled water under ultrasonic irradiation to obtain a 10% by weight aqueous dispersion of the filler. 10 g of the obtained conductive particles were dispersed in 500 mL of distilled water, 1 g of a 10% by weight aqueous dispersion of filler was added, and the mixture was stirred at room temperature for 8 hours. After filtering through a 3 μm mesh filter, the resultant was further washed with methanol and dried to obtain conductive particles with filler.

(4) Preparation of conductive material (anisotropic conductive paste) 7 parts by weight of the obtained conductive particles with filler, 25 parts by weight of bisphenol A type phenoxy resin, 4 parts by weight of fluorene type epoxy resin, and phenol novolak type epoxy A conductive material (anisotropic conductive paste) was obtained by blending 30 parts by weight of resin and SI-60L (manufactured by Sanshin Chemical Industry Co., Ltd.) and defoaming and stirring for 3 minutes. In 100% by weight of the obtained conductive material, the content of the conductive particles was 10.0% by weight, and the content of the filler was 0.5% by weight.

(5) Preparation of Connection Structure Transparent glass substrate (first connection target) having an IZO electrode pattern (first electrode, Vickers hardness of metal on the electrode surface of 100 Hv) having an L / S of 10 μm / 10 μm formed on the upper surface Members) were prepared. Also, a semiconductor chip (second connection target member) having an Au electrode pattern (second electrode, Vickers hardness of the metal on the electrode surface of 50 Hv) having an L / S of 10 μm / 10 μm formed on the lower surface was prepared.

  On the transparent glass substrate, the obtained anisotropic conductive paste was applied so as to have a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the semiconductor chip was laminated on the anisotropic conductive paste layer such that the electrodes faced each other. Then, while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer becomes 100 ° C., the pressurizing and heating head is placed on the upper surface of the semiconductor chip, and the pressure of 60 MPa is applied to the anisotropic conductive paste layer. The composition was cured at 100 ° C. to obtain a connection structure.

(Examples 2 to 6 and Comparative Examples 1 to 3)
A process for preparing conductive particles with filler and a conductive material (anisotropic conductive paste) such that the content of conductive particles and the content of filler in 100% by weight of conductive material are the values shown in Table 1 below. Conductive particles, fillers, conductive particles with filler, conductive material, and connection structure were obtained in the same manner as in Example 1 except that the manufacturing process was changed.

(Example 7)
In preparing the conductive material, the amount of the fluorene type epoxy resin in the composition of the conductive material was changed from 4 parts by weight to 10 parts by weight, and the amount of the phenol novolak type epoxy resin was changed from 30 parts by weight to 60 parts by weight. changed. Further, the production process of the conductive particles with filler and the conductive material (anisotropic conductive material) are adjusted so that the content of the conductive particles and the content of the filler in 100% by weight of the conductive material are the values shown in Table 1 below. Paste) was changed. Except for the above change, conductive particles, fillers, conductive particles with filler, conductive material and connection structure were obtained in the same manner as in Example 3.

(Example 8)
In preparing the conductive material, the amount of the fluorene type epoxy resin in the composition of the conductive material was changed from 4 parts by weight to 15 parts by weight, and the amount of the phenol novolak type epoxy resin was changed from 30 parts by weight to 70 parts by weight. changed. Further, the production process of the conductive particles with filler and the conductive material (anisotropic conductive material) are adjusted so that the content of the conductive particles and the content of the filler in 100% by weight of the conductive material are the values shown in Table 1 below. Paste) was changed. Except for the above change, conductive particles, fillers, conductive particles with filler, conductive material and connection structure were obtained in the same manner as in Example 3.

(Evaluation)
(1) Ratio of the number of fillers The obtained conductive material was heated and pressed under heating conditions of 150 ° C. and 10 seconds, and under a pressure of 3 MPa to obtain a cured product of the conductive material having a uniform thickness. . Using the obtained cured product, a region extending from the surface of the conductive particles in the total number of fillers contained in the cured product to 100% and extending outward from the surface of the conductive particles to a distance of 1/2 of the particle diameter of the conductive particles ( The ratio of the number of fillers present in the first region, R1), was calculated. In addition, in the total number of fillers contained in the cured product of 100%, from the surface of the cured product (one surface, the first surface) to the inside to a distance of 1/5 of the particle diameter of the conductive particles. The ratio of the number of the fillers present in the region (the second region, R2) was calculated. Further, in the total number of fillers contained in the cured product of 100%, from the surface of the cured product (the surface on the other side, the second surface) to the inside to a distance of 1/5 of the particle diameter of the conductive particles. The ratio of the number of the fillers existing in the region (third region, R3) was calculated.

  Using a scanning electron microscope (SEM), the proportion of the number of the fillers present in the first region (R1) in 100% of the total number of the fillers contained in the cured product was determined using the cured product of the conductive material. It was calculated by observation. Specifically, the cured product of the conductive material is cut with a cross section polisher (CP) or the like, and the cross section of the cured product is observed with a scanning electron microscope. By measuring the number of fillers in the first region (R1) in the cut surface of the cured product and the number of fillers in regions other than the first region (R1), the ratio of the number of fillers is measured. Was calculated. The ratio of the number of the fillers present in the second region (R2) or the third region (R3) in 100% of the total number of the fillers contained in the cured product is determined as the cured product of the conductive material. It was calculated by observation using a scanning electron microscope (SEM). Specifically, the cured product of the conductive material is cut with a cross section polisher (CP) or the like, and the cross section of the cured product is observed with a scanning electron microscope. The number of fillers in the second region (R2) in the cut surface of the cured product, the number of fillers in regions other than the second region (R2), and the number of fillers in the cut surface of the cured product By measuring the number of fillers in the third region (R3) and the number of fillers in regions other than the third region (R3), the ratio of the number of fillers was calculated.

  In addition, using the obtained connection structure, in the total number of fillers contained in the connection portion, 100%, from the surface of the conductive particles to the outside, to a distance of 1/2 of the particle diameter of the conductive particles. The ratio of the number of fillers present in the region (fourth region, R4) was calculated. Further, in the total number of fillers included in the connection portion, the distance from the surface of the connection portion (one surface, the first surface) to the inside to a distance of 1/5 of the particle diameter of the conductive particles in 100% of the total number of fillers contained in the connection portion. The ratio of the number of fillers present in the region (fifth region, R5) was calculated. Also, in the total number of fillers included in the connection portion, the distance from the surface of the connection portion (the surface on the other side, the second surface) to the inside is 100% of the total number of fillers contained in the connection portion, which is 1/5 of the particle diameter of the conductive particles. The ratio of the number of fillers present in the region (sixth region, R6) was calculated.

  The proportion of the number of fillers present in the fourth region (R4) in 100% of the total number of fillers contained in the connection part was determined by using a scanning electron microscope (SEM) for the connection part in the connection structure. It calculated by observing using. Specifically, the connection portion of the connection structure is cut with a cross section polisher (CP) or the like, and the cross section of the connection portion is observed with a scanning electron microscope. By measuring the number of the fillers in the fourth region (R4) in the cut surface of the connection portion and the number of the fillers in the region other than the fourth region (R4), the ratio of the number of the fillers is measured. Was calculated. The ratio of the number of the fillers present in the fifth region (R5) or the sixth region (R6) in the total number of the fillers contained in the connection portion in 100% is determined by the connection portion in the connection structure. Was calculated by observing using a scanning electron microscope (SEM). Specifically, the connection portion of the connection structure is cut with a cross section polisher (CP) or the like, and the cross section of the connection portion is observed with a scanning electron microscope. The number of fillers in the fifth region (R5) in the cut surface of the connection portion, the number of fillers in regions other than the fifth region (R5), and the number of fillers in the cut surface of the connection portion The ratio of the number of fillers was calculated by measuring the number of fillers in the sixth region (R6) and the number of fillers in regions other than the sixth region (R6).

(2) Storage Elastic Modulus at 25 ° C. Using the same raw material as the obtained filler, a measurement sample A having a length of 10 mm, a width of 1 mm to 10 mm, and a thickness of 15 mm to 50 mm was prepared. Using a dynamic viscoelasticity measuring device ("RSA3" manufactured by TA Instruments), the measurement sample A was subjected to conditions of a frequency of 10 Hz, a strain of 1%, a temperature of -10C to 210C, and a heating rate of 5C / min. Was measured. From the measurement results, the storage elastic modulus at 25 ° C. of the filler was calculated.

  The obtained conductive material was heated and pressed under a heating condition of 150 ° C. and 10 seconds and a pressing condition of 3 MPa to obtain a cured product of the conductive material. The obtained cured product was cut into a size of 10 mm in length, 1 mm to 10 mm in width, and 15 mm to 50 mm in thickness to prepare a measurement sample B. Using a dynamic viscoelasticity measuring device (“RSA3” manufactured by TA Instruments), the measurement sample B was subjected to conditions of a frequency of 10 Hz, a strain of 1%, a temperature of −10 ° C. to 210 ° C., and a heating rate of 5 ° C./min. Was measured. From the measurement results, the storage modulus at 25 ° C. of the cured product was calculated.

  The connection portion of the obtained connection structure was cut out into a size of 10 mm in length, 1 mm to 10 mm in width, and 15 mm to 50 mm in thickness to prepare a measurement sample C. Using a dynamic viscoelasticity measuring device ("RSA3" manufactured by TA Instruments), the measurement sample C was subjected to conditions of a frequency of 10 Hz, a strain of 1%, a temperature of -10C to 210C, and a heating rate of 5C / min. Was measured. From the measurement results, the storage elastic modulus at 25 ° C. of the connection portion was calculated. When it is difficult to cut out the connection portion of the connection structure to a size having a thickness of 15 mm to 50 mm, the connection portion may be appropriately changed to a cutable thickness.

(3) Adhesive strength (die shear strength)
The obtained connection structure was evaluated for die shear strength at 25 ° C. at a speed of 300 μm / sec using a die shear tester (“DAGE 4000” manufactured by Arctec). The adhesive strength (die shear strength) was determined based on the following criteria.

[Criteria for adhesive strength (die shear strength)]
○○○: Die shear strength is 800N or more ○○: Die shear strength is 600N or more and less than 800N ○: Die shear strength is 400N or more and less than 600N ×: Die shear strength is less than 400N

(4) Warpage Using the obtained connection structure, it was visually confirmed whether or not the first connection target member was warped. Warpage was determined according to the following criteria.

[Criteria for warpage]
○○○: no warpage ○○: slight warpage ○: warpage (warpage is greater than the evaluation result of ○○, no problem in actual use)
×: Warpage occurred (affecting actual use)

(5) Crack Using a scanning electron microscope (SEM), using the obtained connection structure, it is determined whether or not a crack has occurred in the connection portion, the first connection target member, or the second connection target member. Confirmed. Cracks were determined according to the following criteria.

[Crack judgment criteria]
○○○: No cracks ○○: Cracks slightly generated ○: Cracks generated (more cracks than the evaluation results of ○○, no practical problems)
×: Cracks occurred (affecting actual use)

  The results are shown in Table 1 below.

1, 1A, 1B ... conductive particles with filler 2, 2A, 2B ... conductive particles 3 ... filler 11 ... base particles 12, 12A, 12B ... conductive part 13A ... core material 14A, 14B ... protrusion 51 ... cured product 51a ... one surface (first surface)
51b... The other surface (second surface)
52: cured product part 81: connection structure 82: first member to be connected 82a: first electrode 83: second member to be connected 83a: second electrode 84: connection part

Claims (10)

A conductive material including a plurality of conductive particles, a plurality of fillers, and a binder resin,
When the conductive material is heated and pressed under heating conditions of 150 ° C. and 10 seconds, and a pressurizing condition of 3 MPa, when a cured product of the conductive material is obtained,
In the cured product, the filler is unevenly distributed,
Of the total number of the fillers contained in the cured product, 100% of the fillers present in a region extending outward from the surface of the conductive particles up to a distance of 1/2 of the particle diameter of the conductive particles. A conductive material having a number ratio of 70% or more.   The number of the fillers present in a region up to a distance of 1/5 of the particle diameter of the conductive particles from the surface of the cured product toward the inside in 100% of the total number of the fillers contained in the cured product. Is less than 50%.   The conductive material according to claim 1, wherein the cured product has a storage elastic modulus at 25 ° C. of 1000 MPa or more and 6000 MPa or less.   The conductive material according to claim 1, wherein the filler is disposed on a surface of the conductive particles.   The conductive material according to any one of claims 1 to 3, wherein the content of the filler is 0.5% by weight or more and 45% by weight or less in 100% by weight of the conductive material.   The conductive material according to claim 1, wherein a storage elastic modulus of the filler at 25 ° C. is 500 MPa or more and 1700 MPa or less. A first connection target member having a first electrode on its surface;
A second member to be connected having a second electrode on its surface;
The first connection target member, and a connection portion connecting the second connection target member,
The material of the connection portion is a conductive material including a plurality of conductive particles, a plurality of fillers, and a binder resin,
The first electrode and the second electrode are electrically connected by the conductive particles,
Of the total number of the fillers contained in the connection portion, 100% of the fillers present in a region extending outward from the surface of the conductive particles up to a distance of 1/2 of the particle diameter of the conductive particles. The connection structure, wherein the proportion of the number is 70% or more.   The number of the fillers present in a region up to a distance of 1/5 of the particle diameter of the conductive particles from the surface of the connection portion toward the inside in 100% of the total number of the fillers included in the connection portion. Is less than 50%.   The connection structure according to claim 7, wherein a storage elastic modulus at 25 ° C. of the connection portion is 1000 MPa or more and 6000 MPa or less.   The connection structure according to any one of claims 7 to 9, wherein the filler is disposed on a surface of the conductive particle.

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