Conductive particles, conductive material, and connection structure

Abstract

Provided are conductive particles that can decrease connection resistance and increase conduction reliability when the conductive particles are used for electrical connection between electrodes.　A conductive particle according to the present invention comprises a base material particle and a conductive part disposed on the surface of the base material particle. The compressive elasticity modulus value of the conductive particle at 10% compression is greater than or equal to the compressive elasticity modulus value of the conductive particle at 20% compression. The compressive elasticity modulus value of the conductive particle at 20% compression is greater than or equal to the compressive elasticity modulus value of the conductive particle at 30% compression. The ratio of the absolute value of the difference between the compressive elasticity modulus value of the conductive particle at 10% compression and the compressive elasticity modulus value of the conductive particle at 20% compression to the compressive elasticity modulus value of the conductive particle at 20% compression is less than or equal to 0.20.

Description

Conductive particles, conductive materials and connection structures

[0001] The present invention relates to a conductive particle including a base particle and a conductive portion disposed on the surface of the base particle. The present invention also relates to a conductive material and a connection structure using the conductive particle.

[0002] Anisotropic conductive materials such as anisotropic conductive pastes and anisotropic conductive films are widely known, and in these anisotropic conductive materials, conductive particles are dispersed in a binder resin.

[0003] The anisotropic conductive material is used to electrically connect electrodes of various connection target components such as flexible printed circuit boards (FPCs), glass substrates, and semiconductor chips to obtain connection structures. Furthermore, as the conductive particles, conductive particles having a base particle and a conductive portion disposed on the surface of the base particle may be used.

[0004] As an example of a base particle used in a conductive particle, Patent Document 1 below discloses polymer microparticles having a breaking load of 9.8 mN (1.0 gf) or less, and states that the polymer microparticles preferably satisfy the relationship 10% K value > 30% K value > 20% K value.

[0005] WO2012 / 020799A1

[0006] When electrically connecting electrodes with conductive particles, an anisotropic conductive material containing conductive particles is placed between the electrodes and heated and pressurized, during which the conductive particles are compressed.

[0007] Generally, an oxide film is often formed on the surface of an electrode connected by conductive particles or on the surface of the conductive part of the conductive particle. If an oxide film is formed, the electrode and the conductive particle (conductive part) cannot make sufficient contact with each other, which causes an increase in the connection resistance between the electrodes. Therefore, it is desirable to remove the oxide film.

[0008] However, when conductive particles are produced using conventional base particles such as those described in Patent Document 1, the compressive modulus at the initial stage of compression (for example, when the conductive particles are compressed by 10% to 20%) is relatively low, and therefore, it may not be possible to sufficiently remove the oxide film on the surface of the electrode or the conductive particle (conductive portion). As a result, conductive particles using conventional base particles may have high connection resistance between electrodes, making it impossible to improve conduction reliability.

[0009] That is, conventional conductive particles have the problem that it is difficult to achieve both low connection resistance and high conduction reliability.

[0010] An object of the present invention is to provide conductive particles that can achieve both low connection resistance and high conduction reliability when used for electrical connection between electrodes, and to provide a conductive material and a connection structure using the conductive particles.

[0011] According to a broad aspect of the present invention, there is provided a conductive particle comprising a base particle and a conductive portion disposed on the surface of the base particle, wherein the compressive modulus value when compressed by 10% is equal to or greater than the compressive modulus value when compressed by 20%, and the compressive modulus value when compressed by 20% is equal to or greater than the compressive modulus value when compressed by 30%, and the ratio of the absolute value of the difference between the compressive modulus value when compressed by 10% and the compressive modulus value when compressed by 20% to the compressive modulus value when compressed by 20% is 0.20 or less.

[0012] In a specific aspect of the conductive particles according to the present invention, the ratio of the absolute value of the difference between the compressive modulus value when compressed by 10% and the compressive modulus value when compressed by 20% to the compressive modulus value when compressed by 20% is 0.15 or less.

[0013] In a specific aspect of the conductive particles according to the present invention, the compressive modulus when compressed by 10% is 13,000 N / mm ２ or more, and the compressive elastic modulus when compressed by 20% is 13,000 N / mm ２ or more, and the compressive elastic modulus when compressed by 30% is 13,000 N / mm ２ That's all.

[0014] In a specific aspect of the conductive particles according to the present invention, the compressive modulus of elasticity when compressed by 10% is 15,000 N / mm ２ or more, and the compressive elastic modulus when compressed by 20% is 15,000 N / mm ２ That's all.

[0015] In a specific aspect of the conductive particles according to the present invention, the compressive modulus when compressed by 10% is greater than the compressive modulus when compressed by 20%, and the compressive modulus when compressed by 20% is greater than the compressive modulus when compressed by 30%.

[0016] In a specific aspect of the conductive particle according to the present invention, the base particle is a resin particle or an organic-inorganic hybrid particle.

[0017] In a specific aspect of the conductive particle according to the present invention, the base particle is an organic-inorganic hybrid particle.

[0018] In a specific aspect of the conductive particle according to the present invention, the particle diameter of the base particle is 1.0 μm or more and 10 μm or less.

[0019] In a specific aspect of the conductive particle according to the present invention, the conductive particle includes an insulating material disposed on an outer surface of the conductive portion.

[0020] In a specific aspect of the conductive particle according to the present invention, the conductive particle has protrusions on the outer surface of the conductive portion.

[0021] According to a broad aspect of the present invention, there is provided a conductive material including the conductive particles described above and a binder resin.

[0022] According to a broad aspect of the present invention, there is provided a connection structure comprising a first connection target member having a first electrode on its surface, a second connection target member having a second electrode on its surface, and a connection portion connecting the first connection target member and the second connection target member, wherein the material of the connection portion contains the above-mentioned conductive particles, and the first electrode and the second electrode are electrically connected by the conductive particles.

[0023] The conductive particle according to the present invention comprises a base particle and a conductive portion disposed on the surface of the base particle. The conductive particle according to the present invention exhibits a compressive modulus of elasticity at 10% compression that is equal to or greater than the compressive modulus at 20% compression, and the compressive modulus at 20% compression that is equal to or greater than the compressive modulus at 30% compression. The conductive particle according to the present invention exhibits a ratio of the absolute value of the difference between the compressive modulus at 10% compression and the compressive modulus at 20% compression to the compressive modulus at 20% compression of 0.20 or less. Because the conductive particle according to the present invention has the above-described configuration, when the conductive particle is used for electrical connection between electrodes, the connection resistance can be reduced and the electrical conductivity reliability can be improved.

[0024] Fig. 1 is a cross-sectional view schematically showing a conductive particle according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view schematically showing a conductive particle according to a second embodiment of the present invention. Fig. 3 is a cross-sectional view schematically showing a conductive particle according to a third embodiment of the present invention. Fig. 4 is a cross-sectional view schematically showing a connection structure using the conductive particle shown in Fig. 1.

[0025] The present invention will be described in detail below.

[0026] (Conductive Particle) The conductive particle according to the present invention comprises a base particle and a conductive portion disposed on the surface of the base particle. In the conductive particle according to the present invention, the compressive modulus value when compressed by 10% is equal to or greater than the compressive modulus value when compressed by 20%, and the compressive modulus value when compressed by 20% is equal to or greater than the compressive modulus value when compressed by 30%. In the conductive particle according to the present invention, the ratio of the absolute value of the difference between the compressive modulus value when compressed by 10% and the compressive modulus value when compressed by 20% to the compressive modulus value when compressed by 20% is 0.20 or less.

[0027] The compressive modulus when compressed by 10%, 20%, and 30% are defined as the 10% K value, 20% K value, and 30% K value, respectively. The conductive particles according to the present invention satisfy the following relationship. Note that the "absolute value of the difference between the compressive modulus when compressed by 10% and the compressive modulus when compressed by 20%" is the ratio (absolute value of the difference between the 10% K value and the 20% K value / 20% K value). Furthermore, when the 10% K value is greater than or equal to the 20% K value, the "absolute value of the difference between the compressive modulus when compressed by 10% and the compressive modulus when compressed by 20%" is the "value obtained by subtracting the compressive modulus when compressed by 20% from the compressive modulus when compressed by 10%."

[0028] 10% K value ≧ 20% K value 20% K value ≧ 30% K value (10% K value - 20% K value) / 20% K value ≦ 0.20

[0029] In other words, the conductive particles according to the present invention satisfy the following relationship:

[0030] 10% K value ≧ 20% K value ≧ 30% K value (10% K value − 20% K value) / 20% K value ≦ 0.20

[0031] Conventional conductive particles have the problem that the oxide film on the surface of the electrode or conductive particle (conductive portion) cannot be sufficiently removed, resulting in high connection resistance between electrodes and making it impossible to improve conductivity reliability.

[0032] In the conductive particles according to the present invention, the ratio of the absolute value of the difference between the compressive modulus values ​​at 10% compression and the compressive modulus values ​​at 20% compression to the compressive modulus value at 20% compression is smaller than that of conventional conductive particles. That is, in the conductive particles according to the present invention, the absolute value of the difference between the compressive modulus values ​​at 10% compression and the compressive modulus values ​​at 20% compression is relatively small, so that the oxide coating on the surface of the electrode or the conductive particle (conductive portion) can be sufficiently removed at the beginning of compression. As a result, when the conductive particles are used for electrical connection between electrodes, both low connection resistance and high conduction reliability can be achieved.

[0033] In recent years, there has been an increasing demand for organic electroluminescence (organic EL) display elements that offer good visibility, can be made thinner, and can be driven at low DC voltages. Titanium electrodes are often used in organic EL display elements. While conventional conductive particles have difficulty in sufficiently removing the oxide film on the surface of titanium electrodes, the conductive particles of the present invention, having the above-described configuration, can sufficiently remove the oxide film on the surface of the electrodes even when titanium electrodes are used, thereby achieving both low connection resistance and high electrical conductivity reliability.

[0034] Furthermore, the conductive particles according to the present invention have a compressive modulus of elasticity at 10% compression that is equal to or greater than that at 20% compression, and a compressive modulus of elasticity at 20% compression that is equal to or greater than that at 30% compression, so that the contact area between the electrode and the deformed conductive particles can be increased during the middle and later stages of compression. As a result, when the conductive particles are used for electrical connection between electrodes, both low connection resistance and high conduction reliability can be achieved.

[0035] In the conductive particles, the compressive modulus value when compressed by 10% may be the same as the compressive modulus value when compressed by 20%. In the conductive particles, the compressive modulus value when compressed by 20% may be the same as the compressive modulus value when compressed by 30%. In the conductive particles, the compressive modulus value when compressed by 10%, the compressive modulus value when compressed by 20%, and the compressive modulus value when compressed by 30% may be the same. From the viewpoint of more effectively exhibiting the effects of the present invention, it is preferable that the compressive modulus value when compressed by 10% of the conductive particles is greater than the compressive modulus value when compressed by 20%. From the viewpoint of more effectively exhibiting the effects of the present invention, it is preferable that the compressive modulus value when compressed by 20% of the conductive particles is greater than the compressive modulus value when compressed by 30%. From the viewpoint of more effectively exerting the effects of the present invention, it is preferable that the compressive modulus of the conductive particles when compressed by 10% is greater than the compressive modulus of the conductive particles when compressed by 20%, and that the compressive modulus of the conductive particles when compressed by 20% is greater than the compressive modulus of the conductive particles when compressed by 30%.

[0036] From the viewpoint of more effectively exerting the effects of the present invention, in the conductive particles, the ratio of the absolute value of the difference between the compressive modulus value when compressed by 10% and the compressive modulus value when compressed by 20% to the compressive modulus value when compressed by 20% is preferably less than 0.20, more preferably 0.15 or less, and even more preferably 0.13 or less. From the viewpoint of more effectively exerting the effects of the present invention, in the conductive particles, the ratio (absolute value of the difference between the 10% K value and the 20% K value / 20% K value) is preferably more than 0, more preferably 0.05 or more, and even more preferably 0.10 or more.

[0037] The compressive elastic modulus value (10% K value) when the conductive particles are compressed by 10% is preferably 10,000 N / mm ２ More preferably, 12,000 N / mm ２ More preferably, 13,000 N / mm ２ More preferably, 15,000 N / mm ２ When the 10% K value of the conductive particles is equal to or greater than the lower limit, the oxide film on the surface of the electrode or the conductive particles (conductive portion) can be more effectively removed at the beginning of compression, and the connection resistance can be further reduced. The 10% K value of the conductive particles is preferably 50,000 N / mm ２ or less, more preferably 40,000 N / mm ２ or less, more preferably 30,000 N / mm ２ Below, particularly preferably 25000 N / mm ２ When the 10% K value of the conductive particles is equal to or less than the upper limit, the contact area between the electrode and the deformed conductive particles can be increased, thereby further reducing the connection resistance.

[0038] The compressive elastic modulus value (20% K value) when the conductive particles are compressed by 20% is preferably 10,000 N / mm ２ More preferably, 12,000 N / mm ２ More preferably, 13,000 N / mm ２ More preferably, 15,000 N / mm ２When the 20% K value of the conductive particles is equal to or greater than the lower limit, the oxide film on the surface of the electrode or the conductive particles (conductive portion) can be more effectively removed at the beginning of compression, and the connection resistance can be further reduced. The 20% K value of the conductive particles is preferably 40,000 N / mm ２ or less, more preferably 30,000 N / mm ２ or less, more preferably 25,000 N / mm ２ Below, particularly preferably 20,000 N / mm ２ When the 20% K value of the conductive particles is equal to or less than the upper limit, the contact area between the electrode and the deformed conductive particles can be increased, thereby further reducing the connection resistance.

[0039] The compressive elastic modulus value (30% K value) when the conductive particles are compressed by 30% is preferably 8000 N / mm ２ More preferably, 10,000 N / mm ２ More preferably, 12000 N / mm ２ More preferably, 13,000 N / mm ２ When the 30% K value of the conductive particles is equal to or greater than the lower limit, depressions (indentations) formed in the electrodes by the conductive particles being pressed into the electrodes during the middle and later stages of compression can further improve the reliability of conduction between the electrodes. The 30% K value of the conductive particles is preferably 40,000 N / mm ２ or less, more preferably 30,000 N / mm ２ or less, more preferably 25,000 N / mm ２ Below, particularly preferably 20,000 N / mm ２ When the 30% K value of the conductive particles is equal to or less than the upper limit, the contact area between the electrode and the deformed conductive particles can be increased in the middle and late stages of compression, and both low connection resistance and high conduction reliability can be more effectively achieved.

[0040] From the viewpoint of more effectively exerting the effects of the present invention, the ratio of the compressive modulus value when compressed by 10% (10% K value) to the compressive modulus value when compressed by 20% (20% K value) in the conductive particles is preferably 1.00 or more, more preferably 1.05 or more, and even more preferably 1.10 or more. From the viewpoint of more effectively exerting the effects of the present invention, the ratio (10% K value / 20% K value) is preferably 1.20 or less, more preferably less than 1.20, even more preferably 1.15 or less, and particularly preferably 1.13 or less.

[0041] From the viewpoint of more effectively exerting the effects of the present invention, the ratio of the compressive modulus value when compressed by 10% (10% K value) to the compressive modulus value when compressed by 30% (30% K value) in the conductive particles is preferably 1.00 or more, more preferably 1.20 or more, and even more preferably 1.30 or more. From the viewpoint of more effectively exerting the effects of the present invention, the ratio (10% K value / 30% K value) is preferably 1.80 or less, more preferably 1.70 or less, even more preferably 1.60 or less, and particularly preferably 1.50 or less.

[0042] From the viewpoint of more effectively exerting the effects of the present invention, the ratio of the compressive modulus value when compressed by 20% (20% K value) to the compressive modulus value when compressed by 30% (30% K value) in the conductive particles is preferably 1.00 or more, more preferably 1.05 or more, and even more preferably 1.10 or more. From the viewpoint of more effectively exerting the effects of the present invention, the ratio (20% K value / 30% K value) is preferably 1.60 or less, more preferably 1.50 or less, even more preferably 1.40 or less, and particularly preferably 1.30 or less.

[0043] The 10% K value, 20% K value, and 30% K value of the conductive particles can be measured as follows.

[0044] Using a micro-compression tester, the conductive particles are compressed with a smooth cylindrical indenter end face (diameter 50 μm, made of diamond) under conditions of 25°C and a maximum test load of 90 mN for 30 seconds. The load value (N) and compression displacement (mm) at this time are measured. From the obtained measured values, the compressive elastic modulus can be calculated using the following formula. As the micro-compression tester, for example, a Fischerscope H-100 manufactured by Fischer can be used.

[0045] K value (N / mm ２ ) = (3 / 2 １／２ ) F.S. －３／２ ・R －１／２ F: Load value (N) when the conductive particle is compressed and deformed by 10%, 20%, or 30%; S: Compression displacement (mm) when the conductive particle is compressed and deformed by 10%, 20%, or 30%; R: Radius of the conductive particle (mm).

[0046] Methods for controlling the 10% K value, the 20% K value, the 30% K value, and the ratio (absolute value of the difference between the 10% K value and the 20% K value / 20% K value) within preferred ranges include the following methods: A method for adjusting physical properties by adjusting the monomer type, monomer molecular weight, monomer blending amount, crosslinking agent, polymerization temperature, polymerization time, firing oxygen concentration, firing temperature, etc. of the base particle; A method for adjusting hardness by adjusting the metal type, alloy type, thickness, etc. of the conductive portion.

[0047] From the viewpoint of further improving the effects of the present invention, the compression recovery rate of the conductive particles is preferably 50% or more, more preferably 60% or more, and even more preferably 65% ​​or more, and is preferably 95% or less, more preferably 90% or less, and even more preferably 85% or less.

[0048] The compression recovery rate can be measured as follows.

[0049] Conductive particles are scattered on a sample stage. For each scattered conductive particle, a micro-compression tester is used, and a load (reversed load value) is applied at 25°C toward the center of the conductive particle with the smooth end face of a cylindrical indenter (diameter 100 μm, made of diamond) until the conductive particle is compressed and deformed by 30%. The load is then released to the origin load value (0.40 mN). The load-compression displacement during this period is measured, and the compression recovery rate can be calculated using the following formula. The loading rate is 0.33 mN / sec. For example, a Fischerscope H-100 manufactured by Fischer is used as the micro-compression tester.

[0050] Compression recovery rate (%) = [L2 / L1] x 100 L1: Compression displacement from the load value for origin when applying a load to the reverse load value L2: Unloading displacement from the reverse load value when releasing the load to the load value for origin

[0051] The particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1.0 μm or more, and preferably 500 μm or less, more preferably 300 μm or less, even more preferably 100 μm or less, and particularly preferably 30 μm or less. When the particle diameter of the conductive particles is above the above lower limit and below the above upper limit, when electrodes are connected using the conductive particles, the contact area between the conductive particles and the electrodes is sufficiently large, and agglomerated conductive particles are less likely to be formed when forming a conductive part. In addition, the gap between the electrodes connected via the conductive particles is not too large, and the conductive part is less likely to peel off from the surface of the base particle. In addition, when the particle diameter of the conductive particles is above the above lower limit and below the above upper limit, the conductive particles can be suitably used for conductive material applications.

[0052] The particle diameter of the conductive particles is preferably an average particle diameter, and more preferably a number average particle diameter. The particle diameter of the conductive particles can be determined, for example, by observing 50 random conductive particles with an electron microscope or optical microscope and calculating the average particle diameter of each conductive particle, or by performing laser diffraction particle size distribution measurement. In observation with an electron microscope or optical microscope, the particle diameter of each conductive particle is determined as the particle diameter in equivalent circle diameter. In observation with an electron microscope or optical microscope, the average particle diameter in equivalent circle diameter of 50 random conductive particles is approximately equal to the average particle diameter in equivalent sphere diameter. In laser diffraction particle size distribution measurement, the particle diameter of each conductive particle is determined as the particle diameter in equivalent sphere diameter. The particle diameter of the conductive particles is preferably calculated by laser diffraction particle size distribution measurement.

[0053] The present invention will be specifically described below with reference to the drawings.

[0054] FIG. 1 is a cross-sectional view showing a conductive particle according to a first embodiment of the present invention.

[0055] The conductive particle 1 shown in Fig. 1 has a base particle 2 and a conductive portion 3. The conductive portion 3 is disposed on the surface of the base particle 2. In the first embodiment, the conductive portion 3 is in contact with the surface of the base particle 2. The conductive particle 1 is a coated particle in which the surface of the base particle 2 is coated with the conductive portion 3. In the conductive particle 1, the conductive portion 3 is a single-layer conductive portion (conductive layer).

[0056] Unlike conductive particles 11 and 21 described later, conductive particle 1 does not have a core substance. Conductive particle 1 does not have protrusions on its surface, and there are no protrusions on the outer surface of conductive portion 3. Conductive particle 1 is spherical.

[0057] Thus, the conductive particles according to the present invention may not have protrusions on their surfaces, may not have protrusions on the outer surface of the conductive portion, and may be spherical. Furthermore, unlike the conductive particles 11 and 21 described below, the conductive particle 1 does not have an insulating material. However, the conductive particle 1 may have an insulating material disposed on the outer surface of the conductive portion 3.

[0058] FIG. 2 is a cross-sectional view showing a conductive particle according to a second embodiment of the present invention.

[0059] 2 includes a base particle 2, a conductive portion 12, a plurality of core materials 13, and a plurality of insulating materials 14. The conductive portion 12 is disposed on the surface of the base particle 2 so as to be in contact with the base particle 2. In the conductive particle 11, the conductive portion 12 is a single-layer conductive portion (conductive layer).

[0060] The conductive particle 11 has a plurality of protrusions 11a on its surface. The conductive portion 12 has a plurality of protrusions 12a on its outer surface. A plurality of core materials 13 are arranged on the surface of the base particle 2. The plurality of core materials 13 are embedded in the conductive portion 12. The core materials 13 are arranged inside the protrusions 11a, 12a. The conductive portion 12 covers the plurality of core materials 13. The outer surface of the conductive portion 12 is raised by the plurality of core materials 13, forming the protrusions 11a, 12a.

[0061] The conductive particle 11 has an insulating material 14 disposed on the outer surface of the conductive portion 12. At least a portion of the outer surface of the conductive portion 12 is coated with the insulating material 14. The insulating material 14 is an insulating particle formed from a material having insulating properties. In this way, the conductive particle according to the present invention may have an insulating material disposed on the outer surface of the conductive portion. However, the conductive particle according to the present invention does not necessarily have to have an insulating material.

[0062] FIG. 3 is a cross-sectional view showing a conductive particle according to a third embodiment of the present invention.

[0063] 3 includes a base particle 2, a conductive portion 22, a plurality of core materials 13, and a plurality of insulating materials 14. The conductive portion 22 as a whole includes a first conductive portion 22A on the base particle 2 side and a second conductive portion 22B on the opposite side to the base particle 2 side.

[0064] The only difference between the conductive particle 11 and the conductive particle 21 is the configuration of the conductive portion. That is, the conductive particle 11 has a conductive portion 12 with a single layer structure, whereas the conductive particle 21 has a first conductive portion 22A and a second conductive portion 22B with a two-layer structure. The first conductive portion 22A and the second conductive portion 22B are formed as separate conductive portions.

[0065] The first conductive portion 22A is disposed on the surface of the base particle 2. The first conductive portion 22A is disposed between the base particle 2 and the second conductive portion 22B. The first conductive portion 22A is in contact with the base particle 2. Therefore, the first conductive portion 22A is disposed on the surface of the base particle 2, and the second conductive portion 22B is disposed on the surface of the first conductive portion 22A. The conductive particle 21 has a plurality of protrusions 21a on its surface. The conductive portion 22 has a plurality of protrusions 22a on its outer surface. The first conductive portion 22A has protrusions 22Aa on its outer surface. The second conductive portion 22B has a plurality of protrusions 22Ba on its outer surface. In the conductive particle 21, the conductive portion 22 is a two-layer conductive portion (conductive layer).

[0066] Other details of the conductive particles will be described below. In the following description, "(meth)acrylic" means either or both of "acrylic" and "methacrylic", and "(meth)acrylate" means either or both of "acrylate" and "methacrylate".

[0067] [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 may be core-shell particles having a core and a shell disposed on the surface of the core. The core may be an organic core. The shell may be an inorganic shell. In order to achieve even better effects of the present invention, the base particles are preferably resin particles or organic-inorganic hybrid particles, and more preferably organic-inorganic hybrid particles.

[0068] The base particles are preferably resin particles formed from a resin. When connecting electrodes using the conductive particles, the conductive particles are placed between the electrodes and then compressed by pressure bonding. If the base particles are resin particles, the conductive particles are easily deformed during the pressure bonding, increasing the contact area between the conductive particles and the electrodes. This further improves the reliability of conduction between the electrodes.

[0069] As the resin that is the material of the resin particles, various organic substances can be suitably used.As the resin that is the material of the resin particles, for example, can be enumerated: polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, polybutadiene and other polyolefin resins; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polyalkylene terephthalate, 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, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyamideimide, polyetheretherketone, polyethersulfone, and the polymer obtained by polymerizing one or more of various polymerizable monomers having ethylenic unsaturated groups. Since the hardness of the base particle can be easily controlled within a suitable range, it is preferable that the resin for forming the resin particles is a polymer obtained by polymerizing one or more polymerizable monomers having multiple ethylenically unsaturated groups.

[0070] When the resin particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group may be a non-crosslinkable monomer or a crosslinkable monomer.

[0071] Examples of the non-crosslinkable monomer include styrene-based 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, cyclohexyl (meth)acrylate, and isobornyl Examples of the monomer include alkyl (meth)acrylate compounds such as (meth)acrylate; oxygen atom-containing (meth)acrylate compounds such as 2-hydroxyethyl (meth)acrylate, glycerol (meth)acrylate, polyoxyethylene (meth)acrylate, and glycidyl (meth)acrylate; nitrile-containing monomers such as (meth)acrylonitrile; and halogen-containing monomers such as trifluoromethyl (meth)acrylate, pentafluoroethyl (meth)acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene.

[0072] Examples of the crosslinkable monomer include tetramethylolmethane tetra(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, glycerol tri(meth)acrylate, glycerol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly) Examples of suitable monomers include polyfunctional (meth)acrylate compounds such as propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; and silane-containing monomers such as triallyl (iso)cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, γ-(meth)acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane.

[0073] The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method, such as a suspension polymerization method in the presence of a radical polymerization initiator, or a method in which non-crosslinked seed particles are used to swell and polymerize the monomer together with the radical polymerization initiator.

[0074] When the base particle is an inorganic particle other than a metal particle or an organic-inorganic hybrid particle, the inorganic material of the base particle can be silica, carbon black, etc. The inorganic material is preferably not a metal. The particles formed by silica are not particularly limited, but can be, for example, particles obtained by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, and then optionally baking the particles. The organic-inorganic hybrid particles can be, for example, organic-inorganic hybrid particles formed by crosslinked alkoxysilyl polymer and acrylic resin.

[0075] When the base particles are metal particles, examples of the metal particles include silver, copper, nickel, silicon, gold, titanium, etc. However, the base particles are preferably not metal particles, and are preferably not copper particles.

[0076] The compressive elastic modulus value (10% K value) when the base particle is compressed by 10% is preferably 9500 N / mm ２ More preferably, 10,500 N / mm ２ More preferably, 13,500 N / mm ２ More preferably, 16,500 N / mm ２ When the 10% K value of the base particle is equal to or greater than the lower limit, the oxide film on the surface of the electrode or conductive particle (conductive portion) can be more effectively removed at the beginning of compression, and the connection resistance can be further reduced. The 10% K value of the base particle is preferably 31,500 N / mm ２ or less, more preferably 30,500 N / mm ２ or less, more preferably 27500 N / mm ２ Below, particularly preferably 24500 N / mm ２When the 10% K value of the base particle is equal to or less than the upper limit, the contact area between the electrode and the deformed conductive particles can be increased, thereby further reducing the connection resistance.

[0077] The compressive elastic modulus value (20% K value) when the base particle is compressed by 20% is preferably 9000 N / mm ２ More preferably, 10,000 N / mm ２ More preferably, 13,000 N / mm ２ More preferably, 16,000 N / mm ２ When the 20% K value of the base particle is equal to or greater than the lower limit, the oxide film on the surface of the electrode or conductive particle (conductive portion) can be more effectively removed at the beginning of compression, and the connection resistance can be further reduced. The 20% K value of the base particle is preferably 31,000 N / mm ２ or less, more preferably 30,000 N / mm ２ or less, more preferably 27000 N / mm ２ Below, particularly preferably 24000 N / mm ２ When the 20% K value of the base particle is equal to or less than the upper limit, the contact area between the electrode and the deformed conductive particles can be increased, thereby further reducing the connection resistance.

[0078] The compressive elastic modulus value (30% K value) when the base particle is compressed by 30% is preferably 8000 N / mm ２ More preferably, 9000 N / mm ２ More preferably, 12000 N / mm ２ More preferably, 15,000 N / mm ２ When the 30% K value of the base particle is equal to or greater than the lower limit, depressions (indentations) formed in the electrodes by the conductive particles being pressed into them during the middle and later stages of compression can further improve the reliability of conduction between the electrodes. The 30% K value of the base particle is preferably 30,000 N / mm ２ or less, more preferably 29000 N / mm ２ or less, more preferably 27000 N / mm ２ Below, particularly preferably 24000 N / mm ２When the 30% K value of the base particle is equal to or less than the upper limit, the contact area between the electrode and the deformed conductive particles can be increased in the middle and late stages of compression, and both low connection resistance and high conduction reliability can be more effectively achieved.

[0079] The particle diameter of the base particle is preferably 0.1 μm or more, more preferably 1.0 μm or more, even more preferably 1.5 μm or more, particularly preferably 2.0 μm or more. The particle diameter of the base particle is preferably 500 μm or less, more preferably 300 μm or less, even more preferably 50 μm or less, even more preferably 30 μm or less, particularly preferably 10 μm or less, and most preferably 5.0 μm or less. When the particle diameter of the base particle is above the lower limit, the contact area between the conductive particle and the electrode is increased, thereby further improving the electrical connection reliability between the electrodes and further reducing the connection resistance between the electrodes connected via the conductive particle. Furthermore, when forming a conductive portion on the surface of the base particle by electroless plating, agglomerated conductive particles are less likely to be formed. When the particle diameter of the base particle is below the upper limit, the conductive particles are easily compressed sufficiently, further reducing the connection resistance between the electrodes and further reducing the gap between the electrodes.

[0080] The particle diameter of the base particles refers to the 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 random base particles with an electron microscope or optical microscope and calculating the average value. When observed with an electron microscope or optical microscope, the particle diameter of each base particle is determined as the particle diameter in equivalent circle diameter. When observed with an electron microscope or optical microscope, the average particle diameter in equivalent circle diameter of 50 random base particles is approximately equal to the average particle diameter in equivalent sphere diameter. When observed with a particle size distribution measuring device, the particle diameter of each base particle is determined as the particle diameter in equivalent sphere diameter. The particle diameter of the base particles is preferably calculated using a particle size distribution measuring device. When measuring the particle diameter of the base particles in the conductive particles, it can be measured, for example, as follows.

[0081] The conductive particles were added to Kulzer's Technovit 4000 to a content of 30% by weight and dispersed to prepare an embedding resin for conductive particle inspection. An ion milling machine (Hitachi High-Technologies Corporation's IM4000) was used to cut out a cross section of the conductive particles so as to pass through the vicinity of the center of the conductive particles dispersed in the embedding resin. Then, using a field emission scanning electron microscope (FE-SEM) with an image magnification set to 25,000x, 50 conductive particles were randomly selected and the substrate particles of each conductive particle were observed. The particle diameter of the substrate particles in each conductive particle was measured, and the arithmetic average was calculated to determine the particle diameter of the substrate particles.

[0082] [Conductive Part] The metal for forming the conductive part is not particularly limited. Examples of the metal include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, ruthenium, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, and alloys thereof. Examples of the metal include tin-doped indium oxide (ITO) and solder. Since the connection resistance between electrodes can be further reduced, alloys containing tin, nickel, palladium, copper, or gold are preferred, and nickel or palladium is preferred.

[0083] As in the conductive particles 1 and 11, the conductive portion may be formed of a single layer. As in the conductive particle 21, the conductive portion may be formed of multiple layers. That is, the conductive portion may have a laminated structure of two or more layers. When the conductive portion is formed of multiple layers, the outermost layer is preferably a gold layer, a nickel layer, a palladium layer, a ruthenium layer, a copper layer, or an alloy layer containing tin and silver, and more preferably a gold layer, a palladium layer, or a ruthenium layer. When the outermost layer is one of these preferred conductive layers, the connection resistance between the electrodes is further reduced. Furthermore, when the outermost layer is a precious metal layer, corrosion resistance is further improved.

[0084] The method for forming the conductive portion on the surface of the base particle is not particularly limited. Examples of the method for forming the conductive portion include electroless plating, electroplating, physical vapor deposition, and coating the surface of the base particle with a metal powder or a paste containing a metal powder and a binder. Electroless plating is preferred because it is easy to form the conductive portion. Examples of the physical vapor deposition method include vacuum deposition, ion plating, and ion sputtering.

[0085] The thickness of the conductive portion (thickness of the entire conductive portion) is preferably 10 nm or more, more preferably 100 nm or more, even more preferably 120 nm or more, and preferably 1000 nm or less, more preferably 500 nm or less, even more preferably 300 nm or less, particularly preferably 250 nm or less, and most preferably 200 nm or less. The thickness of the conductive portion is the thickness of the entire conductive layer when the conductive portion is multilayered. When the thickness of the conductive portion is equal to or greater than the above lower limit and equal to or less than the above upper limit, sufficient conductivity is obtained, and the conductive particles do not become too hard, so that the conductive particles deform sufficiently when connecting electrodes.

[0086] When the conductive portion is formed of multiple layers, the thickness of the outermost conductive layer is preferably 1 nm or more, more preferably 10 nm or more, and preferably 500 nm or less, more preferably 200 nm or less. When the thickness of the outermost conductive layer is equal to or greater than the lower limit and equal to or less than the upper limit, the coating by the outermost conductive layer becomes uniform, the corrosion resistance becomes sufficiently high, and the connection resistance between electrodes becomes further lower. Furthermore, when the outermost layer is a gold layer, the thinner the gold layer, the lower the cost.

[0087] The thickness of the conductive portion can be measured by observing the cross section of the conductive particle using, for example, a transmission electron microscope (TEM).

[0088] From the viewpoint of effectively increasing conductivity, the conductive particles preferably have a conductive portion containing nickel. In 100% by weight of the nickel-containing conductive portion, the nickel content is preferably 50% by weight or more, more preferably 65% ​​by weight or more, even more preferably 70% by weight or more, even more preferably 75% by weight or more, even more preferably 80% by weight or more, particularly preferably 85% by weight or more, and most preferably 90% by weight or more. In 100% by weight of the nickel-containing conductive portion, the nickel content is preferably 100% by weight or less (total amount), and may be 99% by weight or less, or may be 95% by weight or less. When the nickel content is above the lower limit, the connection resistance between electrodes is further reduced. Furthermore, when there is little oxide film on the surface of the electrode or conductive portion, the higher the nickel content, the lower the connection resistance between electrodes tends to be.

[0089] The method for measuring the metal content of the conductive portion can be any known analytical method, and is not particularly limited. Examples of such a measuring method include absorption spectrometry and spectral analysis. In the absorption spectrometry, a flame absorption spectrometer, an electric heating furnace absorption spectrometer, or the like can be used. Examples of the spectral analysis method include plasma emission spectrometry and plasma ion source mass spectrometry.

[0090] When measuring the average content of metals contained in the conductive portion, it is preferable to use an ICP optical emission analyzer. Examples of commercially available ICP optical emission analyzers include an ICP optical emission analyzer manufactured by HORIBA.

[0091] The conductive portion may contain phosphorus or boron in addition to nickel. The conductive portion may also contain a metal other than nickel. When the conductive portion contains multiple metals, the multiple metals may be alloyed.

[0092] In 100% by weight of the conductive portion containing nickel and phosphorus or boron, the content of phosphorus or boron is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and is preferably 10% by weight or less, more preferably 5% by weight or less. When the content of phosphorus or boron is equal to or less than the above lower limit or the above upper limit, the connection resistance of the conductive portion is further reduced, and the conductive portion contributes to reducing the connection resistance.

[0093] [Core Material] From the viewpoint of further reducing the connection resistance and further increasing the conduction reliability, it is preferable that the conductive particle has a plurality of protrusions on the outer surface of the conductive part. Furthermore, it is preferable that the conductive particle has a plurality of core materials in the conductive part that raise the outer surface of the conductive part so as to form the plurality of protrusions.

[0094] The core material is embedded in the conductive part, which makes it easy to form a plurality of protrusions on the outer surface of the conductive part. However, it is not necessary to use the core material to form the protrusions on the surface of the conductive particle and the surface of the conductive part.

[0095] Methods for forming the above-mentioned protrusions include a method in which a core material is attached to the surface of a base particle and then a conductive portion is formed by electroless plating, a method in which a conductive portion is formed on the surface of a base particle by electroless plating, then a core material is attached, and then a conductive portion is formed by electroless plating, and a method in which a core material is added during the process of forming a conductive portion on the surface of a base particle by electroless plating.

[0096] Examples of the material for the core substance include conductive and non-conductive substances. Examples of the conductive substance include conductive non-metals such as metals, metal oxides, and graphite, and conductive polymers. Examples of the conductive polymer include polyacetylene. Examples of the non-conductive substance include silica, alumina, tungsten carbide, titanium oxide, barium titanate, and zirconia. As the metal for the core substance, any of the metals listed as the materials for the conductive material can be used as appropriate.

[0097] Specific examples of the core material include barium titanate (Mohs hardness 4.5), nickel (Mohs hardness 5), silica (silicon dioxide, Mohs hardness 6-7), titanium oxide (Mohs hardness 7), zirconia (Mohs hardness 8-9), alumina (Mohs hardness 9), tungsten carbide (Mohs hardness 9), and diamond (Mohs hardness 10). The inorganic particles are preferably nickel, silica, titanium oxide, zirconia, alumina, tungsten carbide, or diamond, and more preferably silica, titanium oxide, zirconia, alumina, tungsten carbide, or diamond. The inorganic particles are further preferably titanium oxide, zirconia, alumina, tungsten carbide, or diamond, and particularly preferably zirconia, alumina, tungsten carbide, or diamond. The Mohs hardness of the core material is preferably 4 or higher, more preferably 6 or higher, even more preferably 7 or higher, and particularly preferably 7.5 or higher. When the Mohs hardness of the material of the core substance is equal to or higher than the lower limit, the 10% K value, the 20% K value, the 30% K value, and the ratio (absolute value of the difference between the 10% K value and the 20% K value / 20% K value) can be easily controlled within a suitable range.

[0098] The shape of the core material is not particularly limited. The core material is preferably in the form of a mass. Examples of the core material include particulate masses, aggregates formed by aggregating multiple microparticles, and amorphous masses.

[0099] The average particle size of the core material is preferably 0.001 μm or more, more preferably 0.05 μm or more, and preferably 0.9 μm or less, more preferably 0.2 μm or less. When the average particle size of the core material is equal to or more than the lower limit and equal to or less than the upper limit, the connection resistance between electrodes is effectively reduced.

[0100] The average particle size of the core material is preferably a number average particle size, which can be determined by observing 50 random core materials under an electron microscope or an optical microscope and calculating the average value.

[0101] The number of the protrusions per conductive particle is preferably 3 or more, more preferably 5 or more. The upper limit of the number of the protrusions is not particularly limited. The upper limit of the number of the protrusions can be appropriately selected taking into account the particle diameter of the conductive particle, etc.

[0102] From the viewpoint of further reducing the connection resistance and further increasing the conductivity reliability, the surface area of ​​the portion where the protrusions are located is preferably 10% or more, more preferably 30% or more, and preferably 95% or less, more preferably 90% or less, of the total surface area (100%) of the conductive particle.

[0103] The average height of the plurality of protrusions is preferably 0.001 μm or more, more preferably 0.05 μm or more, and is preferably 0.9 μm or less, more preferably 0.5 μm or less. When the average height of the protrusions is equal to or greater than the lower limit and equal to or less than the upper limit, the connection resistance between the electrodes is effectively reduced.

[0104] [Insulating Material] The conductive particles preferably include an insulating material disposed on the surface of the conductive portion. In this case, using the conductive particles to connect electrodes can further prevent short circuits between adjacent electrodes. Specifically, when multiple conductive particles come into contact with each other, the insulating material exists between the multiple electrodes, preventing short circuits not between upper and lower electrodes but between laterally adjacent electrodes. When connecting the electrodes, applying pressure to the conductive particles with two electrodes can easily remove the insulating material between the conductive portion of the conductive particle and the electrode. When the conductive particles have multiple protrusions on the outer surface of the conductive portion, the insulating material between the conductive portion of the conductive particle and the electrode can be more easily removed.

[0105] The insulating material is preferably insulating particles, since this allows the insulating material to be more easily removed when the electrodes are pressed together.

[0106] Specific examples of the insulating resin that is the material for the insulating substance include polyolefins, (meth)acrylate polymers, (meth)acrylate copolymers, block polymers, thermoplastic resins, crosslinked thermoplastic resins, thermosetting resins, and water-soluble resins.

[0107] The particle size of the insulating material can be appropriately selected depending on the particle size of the conductive particles and the application of the conductive particles. Furthermore, from the viewpoint of improving insulating performance, insulating materials with different particle sizes may be mixed and used. The particle size of the insulating material is preferably 0.005 μm or more, more preferably 0.01 μm or more, and preferably 1 μm or less, more preferably 0.5 μm or less. If the particle size of the insulating material is above the lower limit, when the conductive particles are dispersed in the binder resin, the conductive portions of multiple conductive particles are less likely to contact each other. If the particle size of the insulating particles is below the upper limit, excessive pressure and high temperature heating are not required to remove the insulating material between the electrodes and the conductive particles when connecting electrodes.

[0108] (Conductive Material) The conductive material according to the present invention includes the conductive particles described above 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 particles and the conductive material are preferably used for electrical connection between electrodes. The conductive particles and the conductive material are preferably used for electrical connection between electrodes of an organic EL display element. The conductive material is preferably a circuit connection material.

[0109] The binder resin is not particularly limited. 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 type of the binder resin may be used, or two or more types may be used in combination.

[0110] Examples of the vinyl resin include vinyl acetate resin, acrylic resin, and styrene resin. Examples of the thermoplastic resin include polyolefin resin, ethylene-vinyl acetate copolymer, and polyamide resin. Examples of the curable resin include epoxy resin, urethane resin, polyimide resin, and unsaturated polyester resin. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. Examples of the thermoplastic block copolymer include a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a hydrogenated styrene-butadiene-styrene block copolymer, and a hydrogenated styrene-isoprene-styrene block copolymer. Examples of the elastomer include a styrene-butadiene copolymer rubber and an acrylonitrile-styrene block copolymer rubber.

[0111] The conductive material and the binder resin preferably contain a thermoplastic component or a thermosetting component. The conductive material and the binder resin may contain a thermoplastic component or a thermosetting component. The conductive material and the binder resin preferably contain a thermosetting component. The thermosetting component preferably contains a curable compound that can be cured by heating and a thermosetting agent. The thermosetting agent is preferably a thermal cationic curing initiator. The curable compound that can be cured by heating and the thermosetting agent are used in an appropriate blend ratio so that the binder resin cures. If the binder resin contains a thermal cationic curing initiator, acid is likely to be contained in the cured product. However, by using the conductive particles according to the present invention, the connection resistance between electrodes can be maintained low.

[0112] The conductive material may contain various additives such as a filler, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent, and a flame retardant.

[0113] The conductive material can be used as a conductive paste, a conductive film, or the like. When the conductive material is a conductive film, a film not containing 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.

[0114] 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, even more preferably 50% by weight or more, particularly preferably 70% by weight or more, and is preferably 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 electrical conductivity reliability of the connection target members connected by the conductive material is further improved.

[0115] 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, and is preferably 80% by weight or less, more preferably 60% by weight or less, even 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, the reliability of conduction between electrodes is further improved.

[0116] (Connection Structure) A connection structure can be obtained by connecting members to be connected using the conductive particles or a conductive material containing the conductive particles and a binder resin.

[0117] The connection structure includes a first connection target member having a first electrode on its surface, a second connection target member having a second electrode on its surface, and a connection portion connecting the first and second connection target members, the connection portion being made of a material containing the conductive particles described above. In the connection structure, the first electrode and the second electrode are connected by the conductive particles.

[0118] FIG. 4 is a front cross-sectional view that schematically shows a connection structure using conductive particles according to the first embodiment of the present invention.

[0119] The connection structure 51 shown in Fig. 4 includes a first connection target member 52, a second connection target member 53, and a connection portion 54 connecting the first and second connection target members 52, 53. The connection portion 54 is formed by curing a conductive material containing conductive particles 1. Note that in Fig. 4, the conductive particles 1 are shown schematically for convenience of illustration. Instead of the conductive particles 1, conductive particles 11, 21, etc. may be used.

[0120] The first connection target member 52 has a plurality of first electrodes 52a on its surface (upper surface). The second connection target member 53 has a plurality of second electrodes 53a on its surface (lower surface). The first electrodes 52a and the second electrodes 53a are electrically connected by one or more conductive particles 1. Therefore, the first and second connection target members 52, 53 are electrically connected by the conductive particles 1.

[0121] The method for manufacturing the connection structure is not particularly limited. One example of the method for manufacturing the connection structure is a method in which the conductive material is placed between the first connection target member and the second connection target member to obtain a laminate, and then the laminate is heated and pressurized. The pressure of the pressurization is 1.0 × 10 per total area of ​​the connection portions of the electrodes. ６ Pa ~ 4.9 x 10 ８ The heating temperature is about 120°C to 220°C.

[0122] The total area of ​​the connection portions of the electrodes is not limited to the area of ​​the portions in contact with the conductive particles, but refers to the total area of ​​the opposing portions of the two electrodes when viewed in a plane (when viewed in the stacking direction of the first connection target member, the connection portion, and the second connection target member).

[0123] Specific examples of the connection target components include electronic components such as semiconductor chips, capacitors, and diodes, as well as circuit boards such as printed circuit boards, flexible printed circuit boards, glass epoxy boards, and glass boards. The connection target components are preferably electronic components. The conductive particles are preferably used for electrically connecting electrodes in electronic components.

[0124] At least one of the first connection target member and the second connection target member is preferably a flexible printed circuit board. At least one of the first connection target member and the second connection target member is preferably a semiconductor chip. The first connection target member and the second connection target member are preferably a flexible printed circuit board and a semiconductor chip. The material of the flexible printed circuit board is preferably polyimide or polyester, and in the case of polyester, polyethylene terephthalate (PET) is preferable. The conductive particles and the conductive material are suitably used for conduction of the flexible printed circuit board.

[0125] Examples of the electrode provided on the connection target member include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, silver electrodes, titanium electrodes, molybdenum electrodes, and tungsten electrodes. When the connection target member is a flexible printed circuit board, the electrode is preferably a gold electrode, nickel electrode, titanium electrode, tin electrode, or copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, titanium electrode, copper electrode, molybdenum electrode, or tungsten electrode. When the electrode is an aluminum electrode, it may be formed solely from aluminum, or may be an electrode having an aluminum layer laminated on the surface of a metal oxide layer. Examples of materials for 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. In particular, the conductive particles according to the present invention can sufficiently remove the oxide film on the surface of a titanium electrode, thereby achieving both low connection resistance and high electrical reliability. The conductive particles according to the present invention are preferably conductive particles for conductive connection of titanium electrodes. The conductive particles according to the present invention may be used for conductive connection between titanium electrodes, or may be used for conductive connection between titanium electrodes and electrodes other than titanium electrodes. The titanium electrode is an electrode containing titanium.

[0126] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0127] The following materials were prepared:

[0128] (Base particles) Base particle A: resin particles (divinylbenzene copolymer resin particles, "Micropearl SP-203" manufactured by Sekisui Chemical Co., Ltd., average particle diameter 3.0 μm) Base particle B: organic-inorganic hybrid particles (prepared according to Synthesis Example 1 below, average particle diameter 3.0 μm) Base particle C: organic-inorganic hybrid particles (different from base particle B only in particle diameter, average particle diameter 2.5 μm) Base particle D: organic-inorganic hybrid particles (different from base particle B only in particle diameter, average particle diameter 10 μm)

[0129] Synthesis Example 1 600 g of aqueous ammonia solution (0.13 wt %) was placed in a 1000 mL beaker. Next, 38.4 g of vinyltrimethoxysilane, 8.2 g of methyltrimethoxysilane, and 1.4 g of silicone alkoxy oligomer ("X-41-1053" manufactured by Shin-Etsu Chemical Co., Ltd.) were gently added and stirred. After the reaction solution became cloudy, 4.8 mL of 25 wt % aqueous ammonia solution was added, and the mixture was filtered to separate the powder. The collected powder was calcined at 600°C under conditions of an oxygen concentration of 0 ppm to 500 ppm, to obtain base particle B.

[0130] Example 1 Base particles B were added to 500 parts by weight of distilled water and dispersed to obtain a dispersion. 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 also prepared. While stirring the resulting suspension at 60°C, the nickel plating solution was gradually added dropwise to the suspension to perform electroless nickel plating. The suspension was then filtered to remove the particles, which were then washed with water and dried to form a nickel-boron conductive layer (thickness 142 nm) on the surface of base particles B, thereby obtaining conductive particles having a conductive layer on the surface.

[0131] Example 2 Conductive particles were obtained in the same manner as in Example 1, except that the nickel plating solution was changed to a nickel-phosphorus alloy plating solution prepared by adjusting the pH of a mixed solution containing 200 g / L of nickel sulfate, 85 g / L of sodium hypophosphite, 30 g / L of sodium citrate, 50 ppm of thallium nitrate, and 20 ppm of bismuth nitrate to 6.5, and that the thickness of the conductive portion was changed.

[0132] Example 3 Conductive particles were obtained in the same manner as in Example 1, except that the nickel plating solution was changed to a pure nickel plating solution in which a mixed solution containing 200 g / L of nickel sulfate, 50 g / L of hydrazine hydrate, 30 g / L of sodium citrate, 50 ppm of thallium nitrate, and 20 ppm of bismuth nitrate was adjusted to pH 6.5, and the thickness of the conductive portion was changed.

[0133] Example 4: Base particles B were added to 100 parts by weight of a 1 wt% dimethylamine borane solution to activate the surfaces of the base particles B. The surface-activated base particles B were thoroughly washed with water and then added to 500 parts by weight of distilled water and dispersed to obtain a dispersion. Next, 1 g of nickel particle slurry (average particle diameter 150 nm) was added to the dispersion over 3 minutes to obtain a suspension containing base particles B with core materials 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 also prepared. While stirring the resulting suspension at 60°C, the nickel plating solution was gradually added dropwise to the suspension to perform electroless nickel plating. The suspension was then filtered to remove the particles, which were then washed with water and dried to form a nickel-boron conductive layer (thickness 158 nm) on the surface of the base particles B, thereby obtaining conductive particles with a conductive surface. The surface area of ​​the portion with the protrusions was 70% of the total surface area of ​​the outer surface of the conductive portion, which was 100%.

[0134] Example 5 Conductive particles were obtained in the same manner as in Example 4, except that the nickel particle slurry was changed to an alumina particle slurry (average particle diameter 150 nm) and the thickness of the conductive portion was changed.

[0135] Example 6 Conductive particles were obtained in the same manner as in Example 4, except that the nickel particle slurry was changed to a titanium oxide particle slurry (average particle diameter 150 nm) and the thickness of the conductive portion was changed.

[0136] (Example 7) Conductive particles were obtained in the same manner as in Example 1, except that no particle slurry was used to form the protrusions, and the protrusions were formed by adjusting the amount of precipitation to vary partially during the formation of the conductive portion, and the thickness of the conductive portion was changed.

[0137] (Example 8) Conductive particles were obtained in the same manner as in Example 4, except that a palladium plating layer (thickness: 20 nm) was formed on the outer surface of the nickel-boron conductive layer when producing the conductive particles, and the thickness of the conductive portion was changed.

[0138] (Example 9) Conductive particles were obtained in the same manner as in Example 4, except that a gold plating layer (thickness 20 nm) was formed on the outer surface of the nickel-boron conductive layer when producing the conductive particles, and the thickness of the conductive portion was changed.

[0139] Example 10 Conductive particles were obtained in the same manner as in Example 1, except that base particle B was changed to base particle A and the thickness of the conductive portion was changed.

[0140] Example 11 Conductive particles were obtained in the same manner as in Example 2, except that base particle B was changed to base particle A and the thickness of the conductive portion was changed.

[0141] Example 12 Conductive particles were obtained in the same manner as in Example 4, except that base particle B was changed to base particle C and the thickness of the conductive portion was changed.

[0142] Example 13 Conductive particles were obtained in the same manner as in Example 4, except that base particle B was changed to base particle D and the thickness of the conductive portion was changed.

[0143] Example 14 A monomer composition containing 100 mmol of methyl methacrylate, 1 mmol of N,N,N-trimethyl-N-2-methacryloyloxyethylammonium chloride, and 1 mmol of 2,2'-azobis(2-amidinopropane) dihydrochloride was prepared. The monomer composition was weighed into a 1000 mL separable flask equipped with a four-neck separable cover, a stirring blade, a three-way stopcock, a condenser, and a temperature probe, and ion-exchanged water was added to the monomer composition so that the solids content was 5 wt%. The mixture was then stirred at 200 rpm and polymerized for 24 hours at 70°C under a nitrogen atmosphere. After the reaction was completed, the mixture was freeze-dried to obtain insulating particles having ammonium groups on the surface, an average particle size of 220 nm, and a CV value of 10%.

[0144] The insulating particles were dispersed in ion-exchanged water under ultrasonic irradiation to obtain a 10 wt % aqueous dispersion of the insulating particles.

[0145] 10 g of the conductive particles obtained in Example 4 were dispersed in 500 mL of ion-exchanged water, 4 g of the aqueous dispersion of insulating particles was added, and the mixture was stirred at room temperature for 6 hours. After filtering through a 3 μm mesh filter, the mixture was further washed with methanol and dried to obtain conductive particles having insulating particles attached thereto.

[0146] Observation with a scanning electron microscope (SEM) revealed that only one coating layer of insulating particles was formed on the surface of the conductive particles. Image analysis was used to calculate the coverage area of ​​the insulating particles (i.e., the projected area of ​​the particle diameter of the insulating particles) relative to the surface area at a distance of 1.66 μm from the center of the conductive particle, and the coverage rate was found to be 30%.

[0147] (Example 15) Conductive particles were obtained in the same manner as in Example 4, except that a ruthenium plating layer (thickness: 20 nm) was formed on the outer surface of the nickel-boron conductive layer when producing the conductive particles, and the thickness of the conductive portion was changed.

[0148] Comparative Example 1 Conductive particles were obtained in the same manner as in Example 1, except that the base particle B was changed to the base particle A and the thickness of the conductive portion was changed.

[0149] Comparative Example 2 Conductive particles were obtained in the same manner as in Example 4, except that base particle B was changed to base particle A and the thickness of the conductive portion was changed.

[0150] Comparative Example 3 Conductive particles were obtained in the same manner as in Example 14, except that base particle B was changed to base particle A and the thickness of the conductive portion was changed.

[0151] Comparative Example 4 Conductive particles were obtained in the same manner as in Example 14, except that base particle B was changed to base particle A and the thickness of the conductive portion was changed.

[0152] (Evaluation) (1) Compressive modulus (10% K value, 20% K value, and 30% K value) and ratio (absolute value of the difference between the 10% K value and the 20% K value / 20% K value) of the conductive particles The compressive modulus (10% K value, 20% K value, and 30% K value) of the obtained conductive particles was measured using a micro-compression tester (Fisherscope H-100 manufactured by Fischer) by the method described above. In addition, the ratio of the absolute value of the difference between the compressive modulus value when compressed by 10% and the compressive modulus value when compressed by 20% to the compressive modulus value when compressed by 20% (absolute value of the difference between the 10% K value and the 20% K value / 20% K value) was calculated.

[0153] (2) Connection Resistance The obtained conductive particles were added to Mitsui Chemicals' "Structbond XN-5A" to a content of 10 wt% and dispersed to prepare an anisotropic conductive paste. A polyimide substrate (flexible printed circuit board) was prepared, having a Ti-Al-Ti multilayer electrode pattern with an L / S of 20 μm / 20 μm on its upper surface. A semiconductor chip was also prepared, having a gold electrode pattern with an L / S of 20 μm / 20 μm on its lower surface. The anisotropic conductive paste immediately after preparation was applied to the polyimide substrate to a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the semiconductor chip was stacked on the anisotropic conductive paste layer with the electrodes facing each other. A pressure heating head was then placed on the upper surface of the semiconductor chip, while adjusting the head temperature so that the temperature of the anisotropic conductive paste layer was 150°C. A pressure of 40 MPa per total bump area was applied, and the anisotropic conductive paste layer was cured at 150°C to obtain a connection structure. The connection resistance A between the opposing electrodes of the resulting connection structure was measured by a four-terminal method. The connection resistance was evaluated according to the following criteria.

[0154] [Evaluation criteria for connection resistance] ○○○: Connection resistance A is 2.0Ω or less. ○○: Connection resistance A is greater than 2.0Ω and less than 3.0Ω. ○: Connection resistance A is greater than 3.0Ω and less than 5.0Ω. ×: Connection resistance A exceeds 5.0Ω.

[0155] (3) Conduction reliability: The connection structure after evaluation of the connection resistance in (2) above was left for 500 hours under conditions of 85°C and 85% humidity. After leaving the connection structure for 500 hours, the connection resistance B between the upper and lower electrodes was measured by the four-terminal method. The conduction reliability after leaving the connection structure at high temperature and high humidity was evaluated based on the connection resistances A and B according to the following criteria.

[0156] [Evaluation criteria for conduction reliability] ○○○: Connection resistance B is less than 1.25 times the connection resistance A. ○○: Connection resistance B is 1.25 times or more but less than 1.5 times the connection resistance A. ○: Connection resistance B is 1.5 times or more but less than 2.0 times the connection resistance A. ×: Connection resistance B is 2.0 times or more the connection resistance A.

[0157] The details and results are shown in Tables 1 and 2 below.

[0158]

[0159]

[0160] REFERENCE SIGNS LIST 1...Conductive particle 2...Base particle 3...Conductive portion 11...Conductive particle 11a...Protrusion 12...Conductive portion 12a...Protrusion 13...Core material 14...Insulating material 21...Conductive particle 21a...Protrusion 22...Conductive portion 22a...Protrusion 22A...First conductive portion 22Aa...Protrusion 22B...Second conductive portion 22Ba...Protrusion 51...Connection structure 52...First connection target member 52a...First electrode 53...Second connection target member 53a...Second electrode 54...Connection portion

Claims

1. The system comprises base particles and conductive parts disposed on the surface of the base particles, The compressive modulus of elasticity when compressed by 10% is greater than or equal to the compressive modulus of elasticity when compressed by 20%, AND the compressive modulus of elasticity when compressed by 20% is greater than or equal to the compressive modulus of elasticity when compressed by 30%. The ratio of the absolute difference between the compressive modulus value when compressed by 10% and the compressive modulus value when compressed by 20% to the compressive modulus value when compressed by 20% is 0.12 or less. Conductive particles having a compressive modulus of 12,000 N / mm² or more when compressed by 30%.

2. comprising base material particles and conductive parts disposed on the surface of the base material particles, The compressive modulus of elasticity when compressed by 10% is greater than or equal to the compressive modulus of elasticity when compressed by 20%, AND the compressive modulus of elasticity when compressed by 20% is greater than or equal to the compressive modulus of elasticity when compressed by 30%. The ratio of the absolute difference between the compressive modulus value when compressed by 10% and the compressive modulus value when compressed by 20% to the compressive modulus value when compressed by 20% is 0.15 or less. Conductive particles having a compressive modulus of elasticity of 12,000 N / mm² or more and 16,340 N / mm² or less when compressed by 30%.

3. The compressive modulus when compressed by 10% is 13,000 N / mm². ２ That's all. The compressive modulus when compressed by 20% is 13,000 N / mm². ２ That's all. The compressive modulus when compressed by 30% is 13,000 N / mm². ２ The conductive particles according to claim 1 or 2.

4. The conductive particle according to claim 1 or 2, wherein the value of the compressive modulus when compressed by 10% is 15,000 N / mm² or more.

5. The compressive modulus when compressed by 10% is 15,000 N / mm². ２ That's all. The compressive modulus when compressed by 20% is 15,000 N / mm². ２ The conductive particles according to claim 1 or 2.

6. The conductive particle according to claim 1 or 2, wherein the value of the compressive modulus when compressed by 30% is 13,740 N / mm² or more and 16,340 N / mm² or less.

7. The conductive particle according to claim 1 or 2, wherein the value of the compressive modulus when compressed by 10% is greater than the value of the compressive modulus when compressed by 20%, and the value of the compressive modulus when compressed by 20% is greater than the value of the compressive modulus when compressed by 30%.

8. The conductive particles according to claim 1 or 2, wherein the base material particles are resin particles or organic-inorganic hybrid particles.

9. The conductive particle according to claim 1 or 2, wherein the base material particles are resin particles.

10. The conductive particle according to claim 1 or 2, wherein the base material particles are organic-inorganic hybrid particles.

11. The conductive particle according to claim 1 or 2, wherein the particle diameter of the base material particle is 1.0 μm or more and 10 μm or less.

12. The conductive particle according to claim 1 or 2, comprising an insulating material disposed on the outer surface of the conductive portion.

13. The conductive particle according to claim 1 or 2, having protrusions on the outer surface of the conductive portion.

14. A conductive material comprising conductive particles according to claim 1 or 2 and a binder resin.

15. A first connection target member having a first electrode on its surface, A second connection target member having a second electrode on its surface, It comprises a connecting portion that connects the first member to be connected and the second member to be connected, The material of the connecting portion includes the conductive particles described in claim 1 or 2. A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.