JP2021036525A - Base particle, conductive particle, conductive material, and connection structure - Google Patents

Abstract

To provide a base particle that can achieve both of low connection resistance and high conduction reliability when a conductive particle formed by forming a conductive layer on the surface of the base particle is used for electric connection between electrodes.SOLUTION: The base particle of the present invention is to be used, after a conductive layer is formed on the surface thereof, to obtain a conductive particle having the conductive layer. The base particle shows a compressive elastic modulus of 100 N/mm2 or more and 8000 N/mm2 or less at 10% compression. A ratio of the compressive elastic modulus at 10% compression to a compressive elastic modulus at 20% compression is 1.20 or more; and a ratio of the compressive elastic modulus at 20% compression to a compressive elastic modulus at 30% compression is 0.85 or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to substrate particles in which a conductive layer is formed on the surface and used to obtain conductive particles having the conductive layer. The present invention also relates to conductive particles, conductive materials and connecting structures using the above-mentioned base material particles.

Anisotropic conductive materials such as anisotropic conductive pastes and anisotropic conductive films are widely known. In the anisotropic conductive material, conductive particles are dispersed in the binder resin.

The anisotropic conductive material is used to electrically connect electrodes of various connection target members such as a flexible printed circuit board (FPC), a glass substrate, and a semiconductor chip to obtain a connection structure. Further, as the conductive particles, conductive particles having a base material particles and a conductive layer arranged on the surface of the base material particles may be used.

As an example of the base material particles used for the above-mentioned conductive particles, in the following Patent Documents 1 and 2, a base material which is a resin particle and at least one conductive metal layer formed on the surface of the base material are provided. The conductive particles having are disclosed.

In Patent Document 1, the average dispersed particle size based on the number of resin particles is 1.0 to 2.5 μm. The compressive elastic modulus (10% K value) when the diameter of the resin particles is displaced by 10% is 12000 N / mm ² or more.

In Patent Document 2, the average particle size of the resin particles is 1.0 to 2.5 μm. When the average particle diameter (unit: μm) of the resin particles, the load value when the diameter of the resin particles is displaced by 30% (30% load value; unit: mN), and the diameter of the resin particles are displaced by 40%. The load value of (40% load value; unit: mN) satisfies the following equation.

(40% load value-30% load value) / Average particle size x 0.1 ≧ 12

WO2012 / 102199A1 Japanese Unexamined Patent Publication No. 2012-185918

When electrically connecting the electrodes with conductive particles, an anisotropic conductive material containing the conductive particles is arranged between the electrodes, and the electrodes are heated and pressurized. The conductive particles are compressed. At this time, if a recess (indentation) in which the conductive particles are pushed is formed in the electrode, the conduction reliability between the electrodes can be improved. On the other hand, when the contact area between the electrode and the deformed conductive particles is large, the connection resistance is low and the conductivity is high.

However, with the conventional conductive particles as described in Patent Documents 1 and 2, the contact area between the electrode and the deformed conductive particles becomes small and the conductivity becomes low, or a recess cannot be sufficiently formed in the electrode. In addition, the reliability of conduction between the electrodes may decrease. If the electrodes are not sufficiently formed with recesses, the connection resistance may increase when the connection structure electrically connected between the electrodes is exposed to high temperature or high humidity conditions.

That is, with conventional conductive particles, there is a problem that it is difficult to achieve both low connection resistance and high conduction reliability.

An object of the present invention is a group capable of achieving both low connection resistance and high conduction reliability when conductive particles having a conductive layer formed on a surface are used for electrical connection between electrodes. It is to provide wood particles. Another object of the present invention is to provide conductive particles, a conductive material, and a connecting structure using the above-mentioned base material particles.

According to a broad aspect of the present invention, a conductive layer is formed on the surface and used to obtain conductive particles having the conductive layer, and the compressive elastic modulus when compressed by 10% is 100 N / mm ² or more, 8000 N. / Mm ² or less, the ratio of the compressive modulus when compressed by 10% to the compressive modulus when compressed by 20% is 1.20 or more, and compressed by 30% of the compressive modulus when compressed by 20%. Substrate particles are provided having a ratio of to compressive modulus at 0.85 or less.

In a specific aspect of the substrate particles according to the present invention, the particle size is 0.5 μm or more and 50 μm or less.

In a specific aspect of the substrate particles according to the present invention, the compression recovery rate when compressed by 30% is 40% or more.

In a particular aspect of the substrate particles according to the present invention, there are at least two regions from the center of the substrate particles toward the surface where the materials for forming the substrate particles are different.

In a particular aspect of the substrate particles according to the present invention, there are at least three regions from the center of the substrate particles toward the surface where the materials for forming the substrate particles are different.

In a specific aspect of the base particles according to the present invention, the material for forming the base particles is a polymer of a polymerizable composition containing a compound having a structural unit represented by the following formula (1).

In the above equation (1), m and n each represent an integer of 1 or more.

According to a broad aspect of the present invention, conductive particles comprising the above-mentioned base particles and a conductive layer arranged on the surface of the base particles are provided.

In certain aspects of the conductive particles according to the present invention, the conductive particles further comprise an insulating material disposed on the outer surface of the conductive layer.

In certain aspects of the substrate particles according to the present invention, the conductive particles have protrusions on the outer surface of the conductive layer.

According to a broad aspect of the present invention, the conductive particles include the conductive particles and the binder resin, and the conductive particles include the above-mentioned base particles and a conductive layer arranged on the surface of the base particles. A conductive material is provided.

According to a broad aspect of the present invention, 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 the above. It is provided with a connecting portion connecting the second connection target member, and the material of the connecting portion is a conductive material, or is a conductive material containing the conductive particles and a binder resin, and the conductive material. The sex particles include the above-mentioned base material particles and a conductive layer arranged on the surface of the base material particles, and the first electrode and the second electrode are electrically connected by the conductive particles. The connection structure that has been provided is provided.

The substrate particles according to the present invention have a compressive modulus of 100 N / mm ² or more and 8000 N / mm ² or less when compressed by 10%, and are compressed by 20% of the compressive modulus when compressed by 10%. Since the ratio to the elastic modulus is 1.20 or more and the ratio of the compressive elastic modulus when compressed by 20% to the compressive elastic modulus when compressed by 30% is 0.85 or less, a conductive layer is formed on the surface. When conductive particles are used for electrical connection between electrodes, both low connection resistance and high conduction reliability can be achieved at the same time.

FIG. 1 is a cross-sectional view schematically showing conductive particles according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the conductive particles according to the second embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing the conductive particles according to the third embodiment of the present invention. FIG. 4 is a cross-sectional view schematically showing a connection structure using the conductive particles shown in FIG.

Hereinafter, the present invention will be described in detail. In the following description, "(meth) acrylic" means one or both of "acrylic" and "methacryl", and "(meth) acrylic" means one or both of "acrylic" and "methacryl". Meaning, "(meth) acrylate" means one or both of "acrylate" and "methacrylate".

(Base particle)
The base material particles according to the present invention are used to obtain conductive particles having a conductive layer formed on the surface thereof. In the base particle according to the present invention, the compressive elastic modulus (10% K value) when compressed by 10% is 100 N / mm ² or more and 8000 N / mm ² or less. In the base particle according to the present invention, the ratio (10% K value / 20%) of the compressive elastic modulus (10% K value) when compressed by 10% to the compressive elastic modulus (20% K value) when compressed by 20%. K value) is 1.20 or more. In the base particle according to the present invention, the ratio (20% K value / 30%) of the compressive elastic modulus (20% K value) when compressed by 20% to the compressive elastic modulus (30% K value) when compressed by 30%. K value) is 0.85 or less.

In the present invention, since the above configuration is provided, when conductive particles having a conductive layer formed on the surface are used for electrical connection between electrodes, low connection resistance and high conduction reliability can be obtained. Both can be compatible.

In the present invention, the contact area between the electrode and the deformed conductive particles can be increased, and the connection resistance can be reduced. This is because the conductive particles are satisfactorily deformed at the time of connection between the electrodes because they are relatively flexible at the time of medium-term deformation (effect of the 20% K value).

Further, in the present invention, recesses (indentations) can be sufficiently formed in the electrodes, and the reliability of conduction between the electrodes can be improved. For example, the connection resistance can be kept low even when the connection structure electrically connected between the electrodes is exposed to high temperature or high humidity conditions. This is because the conductive particles are relatively hard at the time of initial deformation (effect of 10% K value) and at the time of late deformation (effect of 30% K value), so that the conductive particles are effectively pushed into the electrodes. It is believed that there is. The starting point of the recess is formed in the electrode at the time of initial deformation (effect of 10% K value), and the recess is sufficiently formed in the electrode at the time of late deformation (effect of 30% K value).

The 10% K value is 100 N / mm ² or more and 8000 N / mm ² or less. The 10% K value is preferably at 500 N / mm ² or more, preferably 5000N / mm ² or less. When the 10% K value is at least the above lower limit, the continuity reliability becomes even higher. When the 10% K value is not more than the upper limit, the connection resistance is effectively lowered and the conduction reliability is effectively increased.

The above ratio (10% K value / 20% K value) is 1.20 or more. The above ratio (10% K value / 20% K value) is preferably 1.30 or more, more preferably 1.40 or more, preferably 3.00 or less, and more preferably 2.80 or less. When the above ratio (10% K value / 20% K value) is not more than the above upper limit, the connection resistance is effectively lowered and the conduction reliability is effectively increased.

The above ratio (20% K value / 30% K value) is 0.85 or less. The above ratio (20% K value / 30% K value) is preferably 0.10 or more, and preferably 0.80 or less. When the above ratio (20% K value / 30% K value) is not more than the above upper limit, the connection resistance is effectively lowered and the conduction reliability is effectively increased.

The compressive elastic modulus (10% K value, 20% K value, and 30% K value) of the base particle can be measured as follows.

A microcompression tester is used to compress a single substrate particle on a cylindrical (diameter 100 μm, made of diamond) smoothing indenter end face under conditions of 25 ° C., a compression rate of 0.3 mN / sec, and a maximum test load of 20 mN. To do. At this time, the load value (N) and the compressive displacement (mm) are measured. From the obtained measured values, the compressive elastic modulus can be calculated by the following formula. As the microcompression tester, for example, "Fisherscope H-100" manufactured by Fisher Co., Ltd. is used.

10% K value, 20% K value or 30% K value (N / mm ² ) = (3/2 ^1/2 ) ・ F ・ S ^-3/2・ R- ^{1 / 2}
F: Load value (N) when the base particle is compressed and deformed by 10%, 20% or 30%.
S: Compressive displacement (mm) when the substrate particles are compressed and deformed by 10%, 20%, or 30%.
R: Radius of substrate particles (mm)

The compressive elastic modulus universally and quantitatively represents the hardness of the substrate particles. By using the compressive elastic modulus, the hardness of the base particle can be expressed quantitatively and uniquely.

The compression recovery rate when the base particles are compressed by 30% is preferably 30% or more, more preferably 40% or more, still more preferably 50% or more. When the compression recovery rate is at least the above lower limit, the substrate particles are likely to be sufficiently followed and deformed in response to fluctuations in the spacing between the electrodes. In addition, the base particles are less likely to be damaged. Therefore, poor connection between the electrodes is less likely to occur. The compression recovery rate of the base particles is preferably 105% or less.

The compression recovery rate can be measured as follows.

The substrate particles are sprayed on the sample table. A load (reversal load value) is applied to one of the sprayed base particles in the direction of the center of the base particles until the base particles are compressed and deformed by 30% using a microcompression tester. After that, the load is removed to the origin load value (0.40 mN). The load-compressive displacement during this period can be measured, and the compression recovery rate can be calculated from the following formula. The load speed is 0.33 mN / sec. As the microcompression tester, for example, "Fisherscope H-100" manufactured by Fisher Co., Ltd. is used.

Compression recovery rate (%) = [(L1-L2) / L1] x 100
L1: Compressive displacement from the origin load value when applying a load to the reversing load value L2: Unloading displacement from the reversing load value when releasing the load to the origin load value

The particle size of the base particles is preferably 0.1 μm or more, more preferably 0.5 μm or more, still more preferably 1 μm or more, still more preferably 1.5 μm or more, particularly preferably 2 μm or more, and most preferably 2. It is 5 μm or more, preferably 1000 μm or less, more preferably 500 μm or less, still more preferably 300 μm or less, still more preferably 50 μm or less, still more preferably 30 μm or less, particularly preferably 10 μm or less, and most preferably 5 μm or less. When the particle size of the base particles is equal to or greater than the above lower limit and equal to or less than the above upper limit, the 10% K value, the 20% K value, the 30% K value, the above ratio (10% K value / 20% K value), and the above ratio. (20% K value / 30% K value) and the compression recovery rate can easily show suitable values, and the base particle can be suitably used for the use of conductive particles.

The particle size of the base material particles means a diameter when the base material particles are spherical, and is assumed to be a true sphere corresponding to the volume when the base material particles have a shape other than the true sphere. It means the diameter when it is used. Further, the particle size of the base material particles means the average particle size of the base material particles measured by an arbitrary particle size measuring device. For example, a particle size distribution measuring machine using principles such as laser light scattering, change in electrical resistance, and image analysis after imaging can be used. More specifically, in the case of a plurality of base particles, as a method for measuring the particle size of the base particles, for example, a particle size distribution measuring device (“Multisizer 4” manufactured by Beckman Coulter) is used, and about 100,000 particles are used. A method of measuring the particle size of the particles and measuring the average particle size can be mentioned. The average particle size indicates a number average particle size.

From the viewpoint of effectively reducing the connection resistance between the electrodes, the particle size of the base particles is 0.5 μm or more and 50 μm or less, and the compression recovery rate of the base particles is 40% or more. preferable.

From the viewpoint of effectively lowering the connection resistance and effectively increasing the conduction reliability, there may be at least two regions in which the material for forming the base particles is different from the center to the surface of the base particles. preferable. It is preferable that at least two such regions exist so as to satisfy the above ratio (10% K value / 20% K value) and the above ratio (20% K value / 30% K value). In this case, the material for forming the base particle is different between the first region (part) and the second region (part) outside the first region.

From the viewpoint of effectively lowering the connection resistance and effectively increasing the conduction reliability, there may be at least three regions in which the material for forming the base particles is different from the center to the surface of the base particles. preferable. It is preferable that at least three such regions exist so as to satisfy the above ratio (10% K value / 20% K value) and the above ratio (20% K value / 30% K value). In this case, the first region (part), the second region (part) outside the first region, and the third region (part) outside the second region The material for forming the base particles is different.

From the viewpoint of effectively lowering the connection resistance and effectively increasing the conduction reliability, the polymerizable composition containing the compound having the structural unit represented by the following formula (1) as the material for forming the base particle. It is preferably a polymer of.

In the above equation (1), m and n each represent an integer of 1 or more.

From the viewpoint of effectively lowering the connection resistance and effectively increasing the conduction reliability, the material for forming the base particle is formed in the central region of the base particle and the outer region surrounding the central region. It is preferable that they are different.

It is preferable that the hardness of the base material particles changes from the center of the base material particles to the surface. The base material particles preferably have a gradation portion whose hardness changes from the center of the base material particles to the surface.

The composition of the base material may be different from the center of the base particle to the surface at the layer interface, or may be different from the center of the base particle to the surface without the layer interface.

The base particle is not preferably a core-shell particle having a core and a shell arranged on the surface of the core, and preferably has no interface between the core and the shell in the base particle. The base particles preferably have no interface in the base particles, and more preferably do not have an interface in which different surfaces are in contact with each other. The base particles preferably do not have a discontinuity where the surface is present, and preferably do not have a discontinuity where the structural surface is present.

From the viewpoint of easily achieving good compressive deformation characteristics and compressive fracture characteristics, it is preferable that the composition of the internal forming material and the composition of the surface forming material are different in the above-mentioned base material particles. It is preferable that the inside of the base particle is formed by using the internal forming material and the surface portion is formed by using the surface forming material. Further, it is preferable that the base material particles have a region containing both the internal forming material and the surface forming material. In the base particle, it is preferable that the base particle has a region in the center which contains the internal forming material and does not contain the surface forming material or contains the surface forming material in an amount of less than 25%.

In the base material particles, it is preferable that the base material particles have a region on the surface that contains the surface portion forming material and does not contain the internal forming material or contains the internal forming material in an amount of less than 25%. It is preferable that the whole base particles do not have a single composition. The internal forming material is a material forming a region including the center of the base particle, and is preferably different from the material forming the surface. The surface portion forming material is a material forming a region including the surface of the base material particles, and is preferably different from the material forming the center of the base material particles.

It is preferable that the surface portion forming material is contained in a distance portion (position of the broken line r1 shown in FIG. 1) having a thickness of 1/10 from the surface of the base material particles inward. In this case, the surface-forming material is generally different from the surface-treating agent that surface-treats the particles. For example, when the particles are surface-treated with a silane coupling agent or the like, the thickness of the surface-treated substance is not so thick.

From the viewpoint of easily achieving good compressive deformation characteristics and compressive fracture characteristics, the composition of the internal forming material and the composition of the surface forming material are different, and the surface forming material is aromatic (di) vinyl. It is preferably at least one selected from the group consisting of compounds, (meth) acrylic compounds and silane alkoxides. The aromatic (di) vinyl compound may be an aromatic vinyl compound or an aromatic divinyl compound. From the viewpoint of easily achieving good compressive deformation characteristics and compressive fracture characteristics, the composition of the internal forming material and the composition of the surface forming material are different, and the internal forming material and the surface forming material are aromatic, respectively. It is preferably at least one selected from the group consisting of group (di) vinyl compounds, (meth) acrylic compounds and silane alkoxides. In this case, it is preferable that the internal forming material is a (meth) acrylic compound and the surface forming material is at least one of an aromatic (di) vinyl compound and a silane alkoxide.

From the viewpoint of easily achieving good compressive deformation characteristics and compressive fracture characteristics, the internal forming material is preferably a (meth) acrylic compound, and the internal forming material is a (meth) acrylic compound, and the surface portion is formed. More preferably, the material is silane alkoxide.

The center of the substrate particles does not contain aromatic (di) vinyl polymer, (meth) acrylic polymer and aromatic (di) vinyl- (meth) acrylic copolymer, or is aromatic (di) vinyl weight. It is preferable that at least one selected from the group consisting of coalesced, (meth) acrylic polymer and aromatic (di) vinyl- (meth) acrylic copolymer is contained in an amount of less than 25% (in the case of two or more kinds). Calculate the total content). The surface of the base particle preferably does not contain a polycondensate of silane alkoxide or contains a polycondensate of silane alkoxide in an amount of less than 25% (in the case of two or more kinds, the total content is calculated). The region having a thickness of 1/10 (region R1 shown in FIG. 1) from the surface of the base material particles toward the inside is preferably formed of a surface forming material, and the aromatic (di) vinyl polymer, (. More preferably, it is formed of at least one selected from the group consisting of a meta) acrylic polymer and an aromatic (di) vinyl- (meth) acrylic copolymer.

The base particle preferably has a region in which the composition of the base particle forming material changes continuously or stepwise from the center of the base particle to the surface, and the composition of the base particle forming material is continuous. It is more preferable to have a region that is changing. The base particle preferably has a region in which the content of each component in the composition is inclined from the center toward the surface.

When a polycondensate of silane alkoxide is used, the base particle preferably has a region in which the carbon atom content continuously changes from the center of the base particle toward the surface. The base material particles preferably have a region in which the content of silicon atoms changes continuously from the center of the base material particles toward the surface. As the carbon atom content increases, the flexibility of the base particle portion having a high carbon atom content tends to increase, and the 10% K value tends to decrease. When the content of silicon atoms is high, the flexibility of the base particles in the base particle portion having a high content of silicon atoms tends to be low, and the 30% K value tends to be high.

The content of the silicon atom at the center of the base particle is preferably 10% by weight or less, more preferably 5% by weight or less. The center of the base particle does not have to contain a silicon atom. It is preferable that the center of the base particle does not contain a silicon atom. The content of the carbon atom contained in the center of the base particle is preferably 50% by weight or more, more preferably 60% by weight or more, still more preferably 65% by weight or more. The lower the content of silicon atoms in the center of the base particles and the higher the content of carbon atoms in the center of the base particles, the more flexible the base particles are due to the composition of the center of the base particles. It will be even higher.

The content of silicon atoms contained in the surface of the base particles and the material for forming the surface portion of the base particles is preferably 50% by weight or more, more preferably 54% by weight or more, still more preferably 56% by weight or more, and particularly preferably 56% by weight or more. It is 60% by weight or more. The surface of the base particle and the material for forming the surface of the base particle do not have to contain carbon atoms, respectively.

The thickness of the region containing the surface forming material is preferably 50 nm or more, more preferably 75 nm or more, further preferably 125 nm or more, preferably 500 nm or less, and more preferably 300 nm or less. When the thickness of the region containing the surface forming material is at least the above lower limit and at least the above upper limit, complete destruction and scattering of the substrate particles are further suppressed, and the ratio (10% K value / 20% K value) is further suppressed. , The above ratio (20% K value / 30% K value) and the above compression recovery rate show more suitable values, and the base material particles can be suitably used for the use of conductive particles. The thickness of the region containing the surface forming material is the average thickness per base particle. The thickness of the region containing the surface forming material can be controlled by controlling the sol-gel method or the like.

The aspect ratio of the base particles is preferably 2 or less, more preferably 1.5 or less, still more preferably 1.2 or less. The above aspect ratio indicates a major axis / minor axis. In the case of a plurality of base particles, preferably, the above aspect ratio is set by observing 10 arbitrary base particles with an electron microscope or an optical microscope, and setting the maximum diameter and the minimum diameter to the major diameter and the minor diameter, respectively. It is obtained by calculating the average value of the major axis / minor axis of the particles.

From the viewpoint of effectively reducing the connection resistance in the connection structure, it is preferable that the inside of the base material particles is formed of an organic compound. Since the inside of the base material particles is formed of an organic compound, complete destruction and scattering of the base material particles can be suppressed.

From the viewpoint of effectively reducing the connection resistance in the connection structure, the surface of the base material particles is preferably formed by hydrolyzing and polycondensing the alkoxysilane compound. In this case, the destruction and scattering of the surface portion of the base particle are further suppressed.

When the material for forming the inside of the base particles is an organic compound, the above ratio (10% K value / 20% K value), the above ratio (20% K value / 30% K value), and the above compression recovery rate are the above values. Is easy to satisfy.

Examples of the organic compound that can be used as the internal forming material include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; and acrylics such as polymethylmethacrylate and polymethylacrylate. Resin: Polyalkylene terephthalate, polysulfone, polycarbonate, polyamide, phenolformaldehyde resin, melamineformaldehyde resin, benzoguanamineformaldehyde resin, ureaformaldehyde resin, various polymerizable monomers having ethylenically unsaturated groups are polymerized by one or more. A polymer obtained by subjecting the mixture, a silanealkoxide polymer having an organic functional group, a polycondensate and the like are used. Among them, as described above, the internal forming material is preferably a (meth) acrylic polymer. Since the internally formed material is a (meth) acrylic polymer, it is easy to design and synthesize base particles having any compression physical characteristics suitable for a conductive material.

When the internal forming material or the like is a (meth) acrylic compound, examples of the (meth) acrylic compound include a non-crosslinkable monomer and a crosslinkable monomer. The (meth) acrylic compound is preferably not a silane alkoxide.

Examples of the non-crosslinkable monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate. Alkyl (meth) acrylates such as cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxy Examples thereof include oxygen atom-containing (meth) acrylates monomers such as ethylene (meth) acrylate and glycidyl (meth) acrylate.

Examples of the crosslinkable monomer include tetramethylolmethanetetra (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanedi (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipenta. Erislitol Hexa (meth) Acrylate, Dipenta Erythritol Penta (Meta) Acrylate, Gloxy Tri (Meta) Acrylate, Gglycerol Di (Meta) Acrylate, (Poly) Ethylene Glycol Di (Meta) Acrylate, (Poly) Ppropylene Glycol Di (Meta) Examples thereof include polyfunctional (meth) acrylate monomers such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, and 1,4-butanediol di (meth) acrylate.

The (meth) acrylic polymer can be obtained by polymerizing the above-mentioned monomer by a known method. Examples of this method include a method of suspension polymerization in the presence of a radical polymerization initiator, a method of swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles, and the like.

Examples of the compound that can be used as the surface forming material include, for example, an aromatic (di) vinyl compound such as divinylbenzene, a silane compound having an alkoxy group, and the like. Among them, the surface forming material and the like are preferably divinylbenzene or silane alkoxide. Only one kind of the surface forming material may be used, or two or more kinds may be used in combination.

The silane alkoxide is not particularly limited. The silane alkoxide preferably has a vinyl group because it can be polymerized with an organic compound which is an internal forming material. Examples of the silane alkoxide having a vinyl group include vinyl trimethoxysilane, vinyl triethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-methacryloxy. Examples thereof include propylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane.

As a method of forming the base material particles using the surface-forming material, for example, the surface-forming material is dissolved in the internal-forming material and phase-separated by utilizing the reaction rate or the SP value difference. Method: The internal forming material is first swelled with a radical polymerization initiator using non-crosslinked seed particles, and then the surface forming material is later swelled with a radical polymerization initiator having a different activity temperature to polymerize in two steps. The method and the surface forming material are first swollen with a radical polymerization initiator using non-crosslinked seed particles, and then the surface forming material is later swollen, and the surface forming material is swelled at the interface with water by the sol-gel method. Examples thereof include a method of polycondensing the mixture and then subjecting the mixture to polymerization by radical polymerization.

From the viewpoint of effectively lowering the connection resistance in the connection structure, the substrate particles are prepared by first swelling the internal forming material together with the radical polymerization initiator using non-crosslinked seed particles, and then the active temperature later. The surface forming material is swelled with different radical polymerization initiators and polymerized in two steps, or the internal forming material is first swelled with the radical polymerization initiator using non-crosslinked seed particles, and then the surface is later formed. It is preferably obtained by swelling the part-forming material, polycondensing the surface-forming material at the interface with water by the solgel method, and then polymerizing by radical polymerization.

As a specific method of the sol-gel method, tetraethoxysilane is added to a dispersion liquid containing an internal portion formed of an internal forming material, a solvent such as water, alcohol, or ketone, a surfactant, and an acidic or basic catalyst. Examples thereof include a method in which an interfacial sol reaction is carried out by coexisting a silane alkoxide such as the above.

(Conductive particles)
The conductive particles include the above-mentioned base particles and a conductive layer arranged on the surface of the base particles.

FIG. 1 shows a cross-sectional view of the conductive particles according to the first embodiment of the present invention.

The conductive particles 1 shown in FIG. 1 have a base particle 11 and a conductive layer 2 arranged on the surface of the base particle 11. The conductive layer 2 covers the surface of the base particle 11. The conductive particles 1 are coated particles in which the surface of the base particles 11 is coated with the conductive layer 2.

FIG. 2 shows a cross-sectional view of the conductive particles according to the second embodiment of the present invention.

The conductive particles 21 shown in FIG. 2 have a base particle 11 and a conductive layer 22 arranged on the surface of the base particle 11. The conductive layer 22 has a first conductive layer 22A which is an inner layer and a second conductive layer 22B which is an outer layer. The first conductive layer 22A is arranged on the surface of the base particle 11. The second conductive layer 22B is arranged on the surface of the first conductive layer 22A.

FIG. 3 shows a cross-sectional view of the conductive particles according to the third embodiment of the present invention.

The conductive particle 31 shown in FIG. 3 has a base particle 11, a conductive layer 32, a plurality of core substances 33, and a plurality of insulating substances 34.

The conductive layer 32 is arranged on the surface of the base particle 11. The conductive particles 31 have a plurality of protrusions 31a on the conductive surface. The conductive layer 32 has a plurality of protrusions 32a on the outer surface. As described above, the conductive particles may have protrusions on the conductive surface of the conductive particles, or may have protrusions on the outer surface of the conductive layer. A plurality of core substances 33 are arranged on the surface of the base particle 11. The plurality of core substances 33 are embedded in the conductive layer 32. The core material 33 is arranged inside the protrusions 31a and 32a. The conductive layer 32 covers a plurality of core substances 33. The outer surface of the conductive layer 32 is raised by the plurality of core substances 33, and protrusions 31a and 32a are formed.

The conductive particles 31 have an insulating substance 34 arranged on the outer surface of the conductive layer 32. At least a part of the outer surface of the conductive layer 32 is covered with the insulating substance 34. The insulating substance 34 is formed of an insulating material and is an insulating particle. As described above, the conductive particles may have an insulating substance arranged on the outer surface of the conductive layer.

The metal for forming the conductive layer is not particularly limited. Examples of the metal include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, tarium, germanium, cadmium, silicon and tungsten. , Molybdenum and alloys thereof. Examples of the metal include tin-doped indium oxide (ITO) and solder. Among them, tin-containing alloys, nickel, palladium, copper or gold are preferable, and nickel or palladium is preferable, because the connection resistance between the electrodes can be further lowered.

The conductive layer may be formed of one layer, such as the conductive particles 1, 31. Like the conductive particles 21, the conductive layer may be formed of a plurality of layers. That is, the conductive layer may have a laminated structure of two or more layers. When the conductive layer is formed of a plurality of layers, the outermost layer is preferably a gold layer, a nickel layer, a palladium layer, a copper layer or an alloy layer containing tin and silver, and is preferably a gold layer. Is more preferable. When the outermost layer is these preferable conductive layers, the connection resistance between the electrodes becomes even lower. Further, when the outermost layer is a gold layer, the corrosion resistance is further improved.

The method of forming the conductive layer on the surface of the base particle is not particularly limited. Examples of the method for forming the conductive layer include a method by electroless plating, a method by electroplating, a method by physical vapor deposition, and a method of coating a metal powder or a paste containing the metal powder and a binder on the surface of the substrate particles. And so on. Of these, the electroless plating method is preferable because the conductive layer can be easily formed. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering.

The particle size of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 520 μm or less, more preferably 500 μm or less, still more preferably 100 μm or less, still more preferably 50 μm or less, particularly preferably. Is 20 μm or less. When the particle size of the conductive particles is equal to or greater than the above lower limit and equal to or less than the above upper limit, the contact area between the conductive particles and the electrodes becomes sufficiently large and the conductive layer is formed when the electrodes are connected using the conductive particles. It becomes difficult for agglomerated conductive particles to be formed when the particles are formed. In addition, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer does not easily peel off from the surface of the base particles. Further, when the particle size of the conductive particles is not less than the above lower limit and not more than the above upper limit, the conductive particles can be suitably used for the use of the conductive material.

The particle size of the conductive particles means a diameter when the conductive particles are spherical, and when the conductive particles have a shape other than spherical, it is assumed to be a true sphere corresponding to the volume. Means the diameter of.

The thickness of the conductive layer 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, still more preferably 0.3 μm or less. The thickness of the conductive layer is the thickness of the entire conductive layer when the conductive layer is multi-layered. When the thickness of the conductive layer is not less than the above lower limit and not more than the above upper limit, sufficient conductivity can be obtained, and the conductive particles are not too hard and the conductive particles are sufficiently deformed at the time of connection between the electrodes. ..

When the conductive layer is formed of a plurality of layers, the thickness of the outermost conductive layer 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 layer of the outermost layer is not less than the above lower limit and not more than the above upper limit, the coating by the conductive layer of the outermost layer becomes uniform, the corrosion resistance becomes sufficiently high, and the connection resistance between the electrodes is further increased. It gets lower. Further, when the outermost layer is a gold layer, the thinner the gold layer, the lower the cost.

The thickness of the conductive layer can be measured by observing the cross section of the conductive particles using, for example, a transmission electron microscope (TEM). As for the thickness of the conductive layer, the average value of the thickness of any of the conductive layers at five points is taken as the thickness of the conductive layer of one particle. In the case of a plurality of conductive particles, the thickness of the conductive layer is preferably obtained by calculating an average value of 10 arbitrary conductive particles.

The conductive particles may have protrusions on the conductive surface. The conductive particles may have protrusions on the outer surface of the conductive layer. It is preferable that the number of the protrusions is plurality. An oxide film is often formed on the surface of the conductive layer and the surface of the electrode connected by the conductive particles. When conductive particles having protrusions are used, the oxide film is effectively removed by the protrusions by arranging the conductive particles between the electrodes and crimping them. Therefore, the electrodes and the conductive layer of the conductive particles can be brought into contact with each other more reliably, and the connection resistance between the electrodes can be lowered. Further, when the conductive particles have an insulating substance on the surface, or when the conductive particles are dispersed in the binder resin and used as a conductive material, the protrusions of the conductive particles cause the conductive particles to be connected to the electrode. The insulating substance or binder resin between them can be effectively eliminated. Therefore, the continuity reliability between the electrodes can be improved.

As a method of forming protrusions on the surface of the conductive particles, a method of forming a conductive layer by electroless plating after adhering a core material to the surface of the base particles, and electroless plating on the surface of the base particles. After forming the conductive layer by the above method, a core material is attached to the conductive layer, and then the conductive layer is formed by electroless plating. Further, it is not necessary to use the core substance in order to form the protrusions.

As a method of forming the above-mentioned protrusions, a method of forming a conductive layer by electroless plating after adhering a core material to the surface of the base particle, and a method of forming a conductive layer by electroless plating on the surface of the base particle. , A method of adhering the core material and further forming the conductive layer by electroless plating, and a method of adding the core material in the middle of forming the conductive layer by electroless plating on the surface of the base particle. For example, as a method of forming protrusions by electroless plating without using a core material, metal nuclei are generated by electroless plating, metal nuclei are attached to the surface of base material particles or a conductive layer, and further conductive by electroless plating. Examples thereof include a method of forming a layer.

The conductive particles may include an insulating substance arranged on the outer surface of the conductive layer. In this case, if conductive particles are used for the connection between the electrodes, a short circuit between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles come into contact with each other, an insulating substance exists between the plurality of electrodes, so that it is possible to prevent a short circuit between the electrodes adjacent to each other in the lateral direction rather than between the upper and lower electrodes. By pressurizing the conductive particles with the two electrodes when connecting the electrodes, the insulating substance between the conductive layer of the conductive particles and the electrodes can be easily removed. When the conductive particles have protrusions on the surface of the conductive layer, the insulating substance between the conductive layer of the conductive particles and the electrodes can be removed more easily. The insulating substance is preferably an insulating resin layer or insulating particles, and more preferably insulating particles. The insulating particles are preferably insulating resin particles.

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

(Conductive material)
The conductive material includes the above-mentioned conductive particles and a binder resin. The conductive particles are preferably dispersed in the binder resin and used as a conductive material. The conductive material is preferably an anisotropic conductive material. The conductive material is preferably used for electrical connection of electrodes. The conductive material is preferably a circuit connection material.

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 vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers. Only one kind of the binder resin may be used, or two or more kinds may be used in combination.

Examples of the vinyl resin include vinyl acetate resin, acrylic resin, styrene resin and the like. Examples of the thermoplastic resin include polyolefin resins, ethylene-vinyl acetate copolymers, and polyamide resins. Examples of the curable resin include epoxy resin, urethane resin, polyimide resin, unsaturated polyester resin and the like. 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 a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a hydrogenated additive of a styrene-butadiene-styrene block copolymer, and a styrene-isoprene. -Hydrogen additives for styrene block copolymers and the like can be mentioned. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

In addition to the conductive particles and the binder resin, the conductive material includes, 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 photostabilizer. It may contain various additives such as an agent, an ultraviolet absorber, a lubricant, an antistatic agent and a flame retardant.

The conductive material can be used as a conductive paste, a conductive film, or the like. When the conductive material according to the present invention is a conductive film, a film containing no conductive particles may be laminated on the conductive film containing the conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

The content of the binder resin in 100% by weight of the conductive material is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, particularly preferably 70% by weight or more, and preferably 70% by weight or more. It is 99.99% by weight or less, more preferably 99.9% by weight or less. When the content of the binder resin is not less than the above lower limit and not more than the above 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 improved.

The content of the conductive particles in 100% by weight of the conductive material 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. Below, it is 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 not less than the above lower limit and not more than the above upper limit, the conduction reliability between the electrodes is further increased.

(Connection structure)
A connection structure can be obtained by connecting the members to be connected using the above-mentioned conductive particles or by using a conductive material containing the above-mentioned conductive particles and a binder resin.

The connection structure includes a first connection target member, a second connection target member, and a connection portion connecting the first connection target member and the second connection target member, and the connection portion. The material is preferably the above-mentioned conductive particles or a conductive material containing the above-mentioned conductive particles and a binder resin. It is preferable that the connecting portion is a connecting structure formed of the above-mentioned conductive particles or a conductive material containing the above-mentioned conductive particles and a binder resin. When the conductive particles are used alone, the connecting portion itself is the conductive particles. That is, the first and second connection target members are connected by the conductive particles. The conductive material used to obtain the connection structure is preferably an anisotropic conductive material.

The first connection target member preferably has a first electrode on its surface. The second connection target member preferably has a second electrode on its surface. It is preferable that the first electrode and the second electrode are electrically connected by the conductive particles.

FIG. 4 is a cross-sectional view schematically showing a connection structure using the conductive particles 1 shown in FIG.

The connection structure 51 shown in FIG. 4 is a connection connecting the first connection target member 52, the second connection target member 53, the first connection target member 52, and the second connection target member 53. A unit 54 is provided. The connecting portion 54 is formed of a conductive material containing the conductive particles 1 and the binder resin. In FIG. 4, for convenience of illustration, the conductive particles 1 are shown schematically. Instead of the conductive particles 1, other conductive particles such as the conductive particles 21 and 31 may be used.

The first connection target member 52 has a plurality of first electrodes 52a on the surface (upper surface). The second connection target member 53 has a plurality of second electrodes 53a on the surface (lower surface). The first electrode 52a and the second electrode 53a are electrically connected by one or more conductive particles 1. Therefore, the first and second connection target members 52 and 53 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, a method in which the conductive material is arranged between a first connection target member and a second connection target member, a laminate is obtained, and then the laminate is heated and pressurized. And so on. The pressurizing pressure is about 9.8 × 10 ^{4 to} 4.9 × 10 ⁶ Pa. The heating temperature is about 120 to 220 ° C. The pressure of the pressurization for connecting the electrodes of the flexible printed circuit board, the electrodes arranged on the resin film, and the electrodes of the touch panel is about 9.8 × 10 ^{4 to} 1.0 × 10 ⁶ Pa.

Specific examples of the connection target member include electronic components such as semiconductor chips, capacitors and diodes, and electronic components such as printed circuit boards, flexible printed circuit boards, glass epoxy boards and circuit boards such as glass substrates. The conductive material is preferably a conductive material for connecting electronic components. The conductive paste is a paste-like conductive material, and is preferably coated on the connection target member in the paste-like state.

The conductive particles and the conductive material are also suitably used for a touch panel. Therefore, it is also preferable that the connection target member is a flexible substrate or a connection target member in which electrodes are arranged on the surface of the resin film. The connection target member is preferably a flexible substrate, and is preferably a connection target member in which electrodes are arranged on the surface of the resin film. When the flexible substrate is a flexible printed circuit board or the like, the flexible substrate generally has electrodes on its surface.

Examples of the electrode 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 silver electrode, a molybdenum electrode, and a tungsten electrode. When the connection target member is a flexible substrate, the electrode is preferably a gold electrode, a nickel electrode, a tin 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, or a tungsten electrode. When the electrode is an aluminum electrode, it may be an electrode formed only of aluminum, or an electrode in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of the material of the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. 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 to the following examples.

(Example 1)
(1) Preparation of Base Particles Polystyrene particles having an average particle diameter of 0.85 μm were prepared as seed particles. 3.0 g of the polystyrene particles, 500 g of ion-exchanged water, and 120 g of a 5 wt% aqueous solution of polyvinyl alcohol were mixed, dispersed by ultrasonic waves, added to a separable flask, and stirred uniformly.

Further, as the organic compound A, 43.8 g of polytetramethylene glycol diacrylate, 1.1 g of 2,2'-azobis (methyl isobutyrate) (“V-601” manufactured by Wako Pure Chemical Industries, Ltd.), and triethanolamine lauryl sulfate. 2.4 g of amine and 30.7 g of ethanol were added to 165 g of ion-exchanged water and emulsified with an ultrasonic homogenizer for 20 minutes to prepare an emulsion A.

The emulsion A was further added to a separable flask to which the polystyrene particles as seed particles were added, and the mixture was stirred for 4 hours to allow the seed particles to absorb the organic compound A, and the seed particles in which the internal forming material was swollen. A suspension containing the above was obtained.

Next, as the organic compound B, 43.8 g of divinylbenzene (purity 96% by weight), 1.1 g of benzoyl peroxide (“Niper BW” manufactured by Nichiyu Co., Ltd.), 2.4 g of triethanolamine lauryl sulfate, and ethanol 30 .7 g was added to 165 g of ion-exchanged water and emulsified with an ultrasonic homogenizer for 20 minutes to prepare an emulsion B.

The emulsion B was further added to the separable flask containing the suspension, and the mixture was stirred for 4 hours to allow the seed particles in which the internal forming material was swollen to absorb the organic compound B.

Then, 307 g of a 5.5 wt% aqueous solution of polyvinyl alcohol was added, and heating was started and reacted at 70 ° C. for 5 hours and then at 85 ° C. for 6 hours to obtain base particles having an average particle size of 3.23 μm.

(2) Preparation of Conductive Particles The obtained base material particles were washed and dried. Then, a nickel layer was formed on the surface of the obtained base material particles by an electroless plating method to prepare conductive particles. The thickness of the nickel layer was 0.1 μm.

(Example 2)
The polytetramethylene glycol diacrylate of organic compound A was changed to 1,4-butanediol diacrylate, ethanol was changed to N, N-dimethylformamide, and 43.8 g of divinylbenzene (purity 96% by weight) of organic compound B was added. , 1,4-Butanediol diacrylate (41.6 g) and pentaerythritol tetraacrylate (2.2 g), except that ethanol was changed to N, N-dimethylformamide, the substrate particles and the same as in Example 1. Conductive particles were prepared.

(Example 3)
Substrate particles and conductive particles were prepared in the same manner as in Example 2 except that divinylbenzene (purity 96% by weight) of the organic compound B was changed to 1,4-butanediol diacrylate.

(Example 4)
Same as in Example 2 except that 43.8 g of 1,4-butanediol diacrylate of organic compound A was changed to 41.6 g of 1,4-butanediol diacrylate and 2.2 g of isobolonyl methacrylate. To prepare base particles and conductive particles.

(Example 5)
The basis was the same as in Example 2 except that 43.8 g of 1,4-butanediol diacrylate of organic compound A was changed to 35.8 g of 1,4-butanediol diacrylate and 9.0 g of cyclohexyl methacrylate. Material particles and conductive particles were produced.

(Example 6)
As the organic compound A, 35.0 g of polytetramethylene glycol diacrylate, 0.9 g of 2,2′-azobis (methyl isobutyrate) (“V-601” manufactured by Wako Pure Chemical Industries, Ltd.), and triethanolamine lauryl sulfate 1 0.8 g and 24.6 g of ethanol were added to 132 g of ion-exchanged water to prepare an emulsion A.

The emulsion A was further added to a separable flask to which the polystyrene particles as seed particles were added, and the mixture was stirred for 4 hours to allow the seed particles to absorb the organic compound A, and the seed particles in which the internal forming material was swollen. A suspension containing the above was obtained.

Next, as the organic compound B, 35.0 g of divinylbenzene (purity 96% by weight), 0.9 g of benzoyl peroxide (“Niper BW” manufactured by Nichiyu Co., Ltd.), 1.8 g of triethanolamine lauryl sulfate, and ethanol 24 .6 g was added to 157 g of ion-exchanged water to prepare an emulsion B.

The emulsion B was further added to the separable flask containing the suspension, and the mixture was stirred for 4 hours to allow the seed particles in which the internal forming material was swollen to absorb the organic compound B.

Then, 246 g of a 5.5 wt% aqueous solution of polyvinyl alcohol was added, and heating was started and reacted at 70 ° C. for 5 hours and then at 85 ° C. for 6 hours to obtain base particles having an average particle size of 2.58 μm. Then, conductive particles were produced in the same manner as in Example 1.

(Example 7)
As the organic compound A, 87.6 g of polytetramethylene glycol diacrylate, 2.2 g of 2,2′-azobis (methyl isobutyrate) (“V-601” manufactured by Wako Pure Chemical Industries, Ltd.), and triethanolamine lauryl sulfate 4 0.8 g and 61.4 g of ethanol were added to 330 g of ion-exchanged water and emulsified with an ultrasonic homogenizer for 20 minutes to prepare an emulsion A.

The emulsion A was further added to a separable flask to which the polystyrene particles as seed particles were added, and the mixture was stirred for 6 hours to allow the seed particles to absorb the organic compound A, and the seed particles in which the internal forming material was swollen. A suspension containing the above was obtained.

Next, as the organic compound B, 87.6 g of divinylbenzene (purity 96% by weight), 2.2 g of benzoyl peroxide (“Niper BW” manufactured by Nichiyu Co., Ltd.), 4.8 g of triethanolamine lauryl sulfate, and ethanol 61 .4 g was added to 330 g of ion-exchanged water and emulsified with an ultrasonic homogenizer for 20 minutes to prepare an emulsion B.

The emulsion B was further added to the separable flask containing the suspension, and the mixture was stirred for 6 hours to allow the seed particles in which the internal forming material was swollen to absorb the organic compound B.

Then, 614 g of a 5.5 wt% aqueous solution of polyvinyl alcohol was added, and heating was started and reacted at 70 ° C. for 7 hours and then at 85 ° C. for 9 hours to obtain base particles having an average particle size of 5.03 μm. Then, conductive particles were produced in the same manner as in Example 1.

(Example 8)
Divinylbenzene (purity 96% by weight) 42.7 g as organic compound A, styrene monomer 42.7 g as organic compound B, cyclohexyl methacrylate 2.1 g as organic compound C, and benzoyl peroxide (Nippon Oil Co., Ltd. "Niper BW" ”) 0.9 g, 2,2′-azobis (methyl isobutyrate) (“V-601” manufactured by Wako Pure Chemical Industries, Ltd.) 0.9 g, 3.6 g of triethanolamine lauryl sulfate, and 49.2 g of ethanol. Was added to 314 g of ion-exchanged water and emulsified with an ultrasonic homogenizer for 20 minutes to prepare an emulsified solution.

The mixture was stirred in a separable flask containing the emulsion for 12 hours, and the seed particles were allowed to absorb the organic compounds A, B, and C.

Then, 246 g of a 5.5 wt% aqueous solution of polyvinyl alcohol was added, and heating was started and reacted at 70 ° C. for 7 hours and then at 85 ° C. for 9 hours to obtain base particles having an average particle size of 3.02 μm. Then, conductive particles were produced in the same manner as in Example 1.

(Example 9)
In a 20 L reaction vessel equipped with a stirrer and a thermometer, 12000 g of a 0.13 wt% ammonia aqueous solution and 10 g of methanol were placed. Next, 950 g of vinyltrimethoxysilane was slowly added to the aqueous ammonia and methanol solution in the reaction vessel. The hydrolysis and condensation reactions were allowed to proceed with stirring, and then 100 mL of a 25 wt% aqueous ammonia solution was added, and then the particles were isolated from the aqueous ammonia solution. After evacuating the inside of the rotary firing furnace, the isolated particles were ^{heated at an oxygen partial pressure of 10-17} atm at 150 ° C. for 1 hour while flowing nitrogen at a rate of 2 L / min, and then at 360 ° C. for 2 hours. Firing was performed to obtain substrate particles. Then, conductive particles were prepared in the same manner as in Example 1.

(Example 10)
(1) Palladium Adhesion Step The substrate particles obtained in Example 1 were prepared. The obtained substrate particles were etched and washed with water. Next, resin particles were added to 100 mL of a palladium-catalyzed solution containing 8% by weight of a palladium catalyst, and the mixture was stirred. Then it was filtered and washed. Substrate particles were added to a 0.5 wt% dimethylamine borane solution having a pH of 6 to obtain base particles to which palladium was attached.

(2) Core Material Adhesion Step The base particles to which palladium was attached were stirred in 300 mL of ion-exchanged water for 3 minutes and dispersed to obtain a dispersion liquid. Next, 1 g of a metal nickel particle slurry (average particle size 100 nm) was added to the dispersion over 3 minutes to obtain base particles to which a core substance was attached.

(3) Electroless Nickel Plating Step In the same manner as in Example 1, a nickel layer was formed on the surface of the base particle to prepare conductive particles. The thickness of the nickel layer was 0.1 μm.

(Example 11)
(1) Preparation of Insulating Particles 100 mmol of methyl methacrylate and N, N, N-trimethyl are placed in a 1000 mL separable flask equipped with a 4-port separable cover, a stirring blade, a three-way cock, a cooling tube and a temperature probe. Ion-exchanged water containing 1 mmol of −N-2-methacryloyloxyethylammonium chloride and 1 mmol of 2,2′-azobis (2-amidinopropane) dihydrochloride having a solid content of 5% by weight. After weighing, the mixture was stirred at 200 rpm and polymerized at 70 ° C. for 24 hours in a nitrogen atmosphere. After completion of the reaction, the reaction was freeze-dried to obtain insulating particles having an ammonium group on the surface and having an average particle size of 220 nm and a CV value of 10%.

The insulating particles were dispersed in ion-exchanged water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion of the insulating particles.

10 g of the conductive particles obtained in Example 1 was dispersed in 500 mL of ion-exchanged water, 4 g of an aqueous dispersion of insulating particles was added, and the mixture was stirred at room temperature for 6 hours. After filtering with a 3 μm mesh filter, the mixture was further washed with methanol and dried to obtain conductive particles to which insulating particles were attached.

When observed with a scanning electron microscope (SEM), only one coating layer of insulating particles was formed on the surface of the conductive particles. When the covering area of the insulating particles (that is, the projected area of the particle size of the insulating particles) was calculated for an area of 2.5 μm from the center of the conductive particles by image analysis, the covering ratio was 30%.

(Comparative Example 1)
Polystyrene particles having an average particle diameter of 0.85 μm were prepared as seed particles. 3.0 g of the polystyrene particles, 500 g of ion-exchanged water, and 120 g of a 5 wt% aqueous solution of polyvinyl alcohol were mixed, dispersed by ultrasonic waves, added to a separable flask, and stirred uniformly.

Further, as the organic compound A, 61 g of cyclohexyl acrylate, 1.6 g of 2,2'-azobis (methyl isobutyrate) (“V-601” manufactured by Wako Pure Chemical Industries, Ltd.), and 3.3 g of triethanolamine lauryl sulfate were used. 42.7 g of ethanol was added to 340 g of ion-exchanged water and emulsified with an ultrasonic homogenizer for 20 minutes to prepare an emulsion A.

The emulsion A was further added to a separable flask to which the polystyrene particles as seed particles were added, and the mixture was stirred for 4 hours to allow the seed particles to absorb the organic compound A, and the seed particles in which the internal forming material was swollen. A suspension containing the above was obtained.

Next, as organic compound B, 61 g of divinylbenzene (purity 96% by weight), 1.6 g of benzoyl peroxide (“Niper BW” manufactured by Nichiyu Co., Ltd.), 3.3 g of triethanolamine lauryl sulfate, and 42.7 g of ethanol. Was added to 340 g of ion-exchanged water and emulsified with an ultrasonic homogenizer for 20 minutes to prepare an emulsion B.

The emulsion B was further added to the separable flask containing the suspension, and the mixture was stirred for 4 hours to allow the seed particles in which the internal forming material was swollen to absorb the organic compound B.

Then, 340 g of a 5.5 wt% aqueous solution of polyvinyl alcohol was added, and heating was started and reacted at 70 ° C. for 5 hours and then at 85 ° C. for 6 hours to obtain base particles having an average particle size of 4.76 μm.

Conductive particles were produced from the obtained base material particles in the same manner as in Example 1.

(Comparative Example 2)
As organic compound A, 31.4 g of polytetramethylene glycol diacrylate, 13.5 g of divinylbenzene (purity 96% by weight), and 2,2'-azobis (methyl isobutyrate) (Wako Pure Chemical Industries, Ltd. "V-601" ”) 1.2 g, 2.4 g of triethanolamine lauryl sulfate, and 31.4 g of ethanol were added to 314 g of ion-exchanged water and emulsified with an ultrasonic homogenizer for 20 minutes to prepare an emulsion A.

The emulsion A was further added to a separable flask to which the polystyrene particles as seed particles were added, and the mixture was stirred for 4 hours to allow the seed particles to absorb the organic compound A, and the seed particles in which the internal forming material was swollen. A suspension containing the above was obtained.

Next, as the organic compound B, 31.4 g of polytetramethylene glycol diacrylate, 13.5 g of divinylbenzene (purity 96% by weight), 1.2 g of benzoyl peroxide (“Niper BW” manufactured by Nichiyu Co., Ltd.), and lauryl. 2.4 g of triethanolamine sulfate and 31.4 g of ethanol were added to 314 g of ion-exchanged water and emulsified with an ultrasonic homogenizer for 20 minutes to prepare an emulsion B. Substrate particles and conductive particles were produced in the same manner as in Example 1 except for the above.

(Comparative Example 3)
Same as Comparative Example 2 except that benzoyl peroxide (NOF "Niper BW") was changed to 2,2'-azobis (methyl isobutyrate) (Wako Pure Chemical Industries, Ltd. "V-601"). To prepare base particles and conductive particles.

(Evaluation)
(1) Average particle size of base material particles About 100,000 particle sizes of the obtained base material particles were measured using a particle size distribution measuring device (“Multisizer 4” manufactured by Beckman Coulter), and the average particle size was measured. did.

(2) Compressive modulus of base particles (10% K value, 20% K value and 30% K value)
The compressive elastic modulus (10% K value, 20% K value, and 30% K value) of the obtained base material particles was measured at 23 ° C. by the above-mentioned method, and the microcompression tester (Fisher Co., Ltd. It was measured using a scope H-100 "). The 10% K value / 20% K value and the 20% K value / 30% K value were determined.

(3) Compression Recovery Rate of Base Material Particles The compression recovery rate of the base material particles was measured by the above-mentioned method using a microcompression tester (“Fisherscope H-100” manufactured by Fisher Co., Ltd.).

(4) Connection resistance Fabrication of connection structure:
Bisphenol A type epoxy resin ("Epicoat 1009" manufactured by Mitsubishi Chemical Corporation) 10 parts by weight, acrylic rubber (weight average molecular weight about 800,000) 40 parts by weight, methyl ethyl ketone 200 parts by weight, microcapsule type curing agent (Asahi Kasei E-Material) 50 parts by weight of "HX3941HP" manufactured by Zu Co., Ltd. and 2 parts by weight of a silane coupling agent ("SH6040" manufactured by Toray Dow Corning Silicone Co., Ltd.) are mixed, and conductive particles are added so as to have a content of 3% by weight. And dispersed to obtain a resin composition.

The obtained resin composition was applied to a PET (polyethylene terephthalate) film having a thickness of 50 μm on which one side was mold-released, and dried with hot air at 70 ° C. for 5 minutes to prepare an anisotropic conductive film. The thickness of the obtained anisotropic conductive film was 12 μm.

The obtained anisotropic conductive film was cut into a size of 5 mm × 5 mm. A glass substrate (width 3 cm, length 3 cm) provided with an aluminum electrode (height 0.2 μm, L / S = 20 μm / 20 μm) having a routing wire for resistance measurement on one side of the cut anisotropic conductive film. ) Was attached to the center of the aluminum electrode. Next, a two-layer flexible printed circuit board (width 2 cm, length 1 cm) provided with the same aluminum electrodes was aligned so that the electrodes overlapped with each other, and then bonded. The laminate of the glass substrate and the two-layer flexible printed circuit board was thermocompression bonded under the pressure bonding conditions of 40 N, 180 ° C., and 15 seconds to obtain a connection structure.

Measurement of connection resistance:
The connection resistance between the opposing electrodes of the obtained connection structure was measured by the 4-terminal method.

[Evaluation criteria for connection resistance]
○ ○: Connection resistance is 3.0Ω or less ○: Connection resistance is more than 3.0Ω and 4.0Ω or less △: Connection resistance is more than 4.0Ω and 5.0Ω or less ×: Connection resistance is more than 5.0Ω

(5) Observation of electrodes (state of indentation)
Using a differential interference microscope, observe the electrodes provided on the glass substrate from the glass substrate side of the connection structure obtained in (4) Evaluation of connection resistance above, and observe the state of indentations on the electrodes in contact with the conductive particles. It was evaluated according to the following evaluation criteria. In addition, using a metallurgical microscope, the presence or absence of voids in the electrode portion in contact with the conductive particles was observed. The presence or absence of indentation on the electrode was observed with a differential interference microscope so ^{that the electrode area was 0.02 mm 2,} and the number of indentations per ^{0.02 mm 2 electrode was calculated.} Arbitrary 10 points were observed with a differential interference microscope, ^{the average value of the number of indentations per 0.02 mm 2} electrode was calculated, and the state of indentations was determined according to the following criteria.

[Criteria for determining the state of indentations]
○ ○: 25 or more indentations per ^{0.02 mm electrode 2} ○: 20 or more indentations per ^{0.02 mm electrode 2 and} less than 25 Δ: 5 or more indentations per ^{0.02 mm electrode 2 and 20} Less than ×: Less than 5 indentations per ^{0.02 mm 2 electrode}

(6) Conductivity reliability The connection structure obtained in the above evaluation of (4) connection resistance was left at 85 ° C. and 85% (high temperature and high humidity) for 120 hours. After being left unattended, the increase in connection resistance was evaluated. The connection resistance between the opposing electrodes of the connection structure after being left to stand was measured by the 4-terminal method. From the connection resistance of the connection structure after being left unattended, the continuity reliability of the connection structure was judged according to the following criteria.

[Evaluation criteria for conduction reliability of connection structures]
○○: The rate of increase in connection resistance after leaving is less than 15% of the connection resistance before leaving ○: The rate of increase in connection resistance after leaving is 15% or more, 30% of the connection resistance before leaving. Less than Δ: Increase rate of connection resistance after leaving is 30% or more and less than 50% with respect to connection resistance before leaving ×: Increase rate of connection resistance after leaving is 50% with respect to connection resistance before leaving that's all

Details and results of the base particles are shown in Table 1 below.

1 ... Conductive particles 2 ... Conductive layer 11 ... Base material particles 21 ... Conductive particles 22 ... Conductive layer 22A ... First conductive layer 22B ... Second conductive layer 31 ... Conductive particles 31a ... Protrusions 32 ... Conductive layer 32a ... Protrusion 33 ... Core material 34 ... Insulating material 51 ... Connection structure 52 ... First connection target member 52a ... First electrode 53 ... Second connection target member 53a ... Second electrode 54 ... Connection portion

Claims (11)

A conductive layer is formed on the surface, and it is used to obtain conductive particles having the conductive layer.
The compressive elastic modulus when compressed by 10% is 100 N / mm ² or more and 8000 N / mm ² or less.
The ratio of the compressive elastic modulus when compressed by 10% to the compressive elastic modulus when compressed by 20% is 1.20 or more.
Substrate particles in which the ratio of the compressive modulus when compressed by 20% to the compressive modulus when compressed by 30% is 0.85 or less. The base particle according to claim 1, wherein the particle size is 0.5 μm or more and 50 μm or less. The base particle according to claim 1 or 2, wherein the compression recovery rate when compressed by 30% is 40% or more. The base particle according to any one of claims 1 to 3, wherein at least two regions in which the material for forming the base particle is different exists from the center of the base particle toward the surface. The base particle according to claim 4, wherein at least three regions in which the material for forming the base particle is different exists from the center of the base particle to the surface. The base particle according to any one of claims 1 to 5, wherein the material for forming the base particle is a polymer of a polymerizable composition containing a compound having a structural unit represented by the following formula (1). ..

In the above equation (1), m and n each represent an integer of 1 or more. The base particle according to any one of claims 1 to 6 and
A conductive particle comprising a conductive layer arranged on the surface of the base particle. The conductive particle according to claim 7, further comprising an insulating substance arranged on the outer surface of the conductive layer. The conductive particles according to claim 7 or 8, which have protrusions on the outer surface of the conductive layer. Contains conductive particles and binder resin,
A conductive material in which the conductive particles include the base material particles according to any one of claims 1 to 6 and a conductive layer arranged on the surface of the base material particles. A first connection target member having a first electrode on its surface,
A second connection target member having a second electrode on the surface,
The first connection target member and the connection portion connecting the second connection target member are provided.
The material of the connecting portion is a conductive material, or is a conductive material containing the conductive particles and a binder resin.
The conductive particles include the base material particles according to any one of claims 1 to 6 and a conductive layer arranged on the surface of the base material particles.
A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.

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