Conductive particles, conductive materials, and connecting structures

Abstract

To provide conductive particles which can effectively suppress occurrence of mutual aggregation of the conductive particles.SOLUTION: A conductive particle includes a base material particle and a conductive part disposed on a surface of the base material particle, in which the conductive part contains a component capable of metal diffusion at 400°C or below or the conductive part can be melt-deformed at 400°C or below, the conductive part has a solder part, and an area including the solder part is 99% or less based on 100% of the total area of the base material particle.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to conductive particles in which a conductive portion is disposed on the surface of base material particles. The present invention also relates to a conductive material and a connection structure using the above conductive particles.

Background Art

[0002] An electronic component in which a connector (first member) and a printed wiring board (second member) are electrically connected by pins is widely known. In the above electronic component, the pins are inserted into through holes or the like formed in the printed wiring board, or directly disposed on electrode portions on the wiring board, and are connected to the printed wiring board by soldering.

[0003] Patent Document 1 below discloses a connection structure of an electronic component in which the other ends of a plurality of pins (20) whose one ends are connected to a first member (10) are aligned using an alignment member (50) and connected to a second member (30). In the connection structure of the above electronic component, the alignment member (50) aligns the pins (20) at the outer peripheral portion in the axial direction (A), then rotates with respect to the axial direction (A) and disengages from the pins (20), and is removed from the pins (20).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, thinning and miniaturization of electronic devices have been progressing. Therefore, in the connection between a substrate and an electronic component, it is difficult to cope with narrow pitch in the conventional connection by pins. Therefore, a solder paste or the like may be used for the electrical connection between the substrate and the electronic component.

[0006] However, with conventional solder pastes, aggregation of solder particles can occur.

[0007] The object of the present invention is to provide conductive particles that can effectively suppress the occurrence of aggregation between conductive particles. Another object of the present invention is to provide a conductive material and a connecting structure using the above conductive particles. [Means for solving the problem]

[0008] In a broader sense, the present invention provides conductive particles comprising a base particle and a conductive portion disposed on the surface of the base particle, wherein the conductive portion contains a component that can be metal-diffused at 400°C or below, or the conductive portion is melt-deformable at 400°C or below, the conductive portion has a solder portion, and the area of ​​the portion with the solder portion is 99% or less of the total surface area of ​​the base particle.

[0009] In a particular aspect of the conductive particles according to the present invention, the solder portion is a solder particle.

[0010] In a particular aspect of the conductive particles according to the present invention, the material of the solder particles contains a tin-containing alloy, pure tin, or tin in a state different from a tin-containing alloy and different from pure tin.

[0011] In a specific aspect of the conductive particles according to the present invention, the material of the solder particles is pure tin.

[0012] In a specific surface of the conductive particles according to the present invention, the height of the solder particles is 10 nm or more and 10 μm or less.

[0013] In a specific plane of the conductive particles according to the present invention, the aspect ratio of the solder particles is 0.05 or more and 5 or less.

[0014] In a particular aspect of the conductive particles according to the present invention, the conductive particles have a metal colloid deposit or a metal film on the outer surface of the solder granules.

[0015] In a specific surface of the conductive particles according to the present invention, the area of ​​the portion containing the metal colloid precipitate or the metal film is 5% or more and 100% or less of the total surface area of ​​the solder particles.

[0016] In a particular aspect of the conductive particles according to the present invention, the metal species of the metal colloid precipitate or the metal species of the metal film is nickel, cobalt, lead, gold, zinc, palladium, copper, silver, bismuth, or indium.

[0017] In a specific surface of the conductive particles according to the present invention, the particle diameter is 0.5 μm or more and 500 μm or less.

[0018] A broad aspect of the present invention provides a conductive material comprising conductive particles and a binder, wherein the conductive particles are the conductive particles described above.

[0019] A connection structure is provided, 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 connecting portion connecting the first connection target member and the second connection target member, wherein the connecting portion is formed of conductive particles or of a conductive material including the conductive particles and a binder, the conductive particles are the conductive particles described above, and the first electrode and the second electrode are electrically connected by the conductive particles. [Effects of the Invention]

[0020] The conductive particles according to the present invention include base material particles and a conductive portion disposed on the surface of the base material particles. In the conductive particles according to the present invention, the conductive portion contains a component capable of metal diffusion at 400°C or lower, or the conductive portion is melt deformable at 400°C or lower. In the conductive particles according to the present invention, the conductive portion has a solder portion. In the conductive particles according to the present invention, the area of the portion having the solder portion is 99% or less of the total surface area of the base material particles. Since the conductive particles according to the present invention are provided with the above configuration, the occurrence of aggregation of the conductive particles can be effectively suppressed.

Brief Description of Drawings

[0021] [Figure 1] FIG. 1 is a cross-sectional view showing conductive particles according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing conductive particles according to a second embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view showing conductive particles according to a third embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view showing conductive particles according to a fourth embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view showing conductive particles according to a fifth embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view showing conductive particles according to a sixth embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view showing conductive particles according to a seventh embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view showing conductive particles according to an eighth embodiment of the present invention. [Figure 9] FIG. 9 is a front cross-sectional view schematically showing a connection structure using the conductive particles according to the third embodiment of the present invention. [Figure 10] FIG. 10 is a front cross-sectional view schematically showing an enlarged connection portion between the conductive particles and the electrode in the connection structure shown in FIG. 9.

Embodiments for Carrying Out the Invention

[0022] The details of the present invention will be described below.

[0023] (Conductive particles) The conductive particles according to the present invention comprise a base particle and a conductive portion disposed on the surface of the base particle. In the conductive particles according to the present invention, the conductive portion contains a component that can be metal-diffused at 400°C or below, or the conductive portion is meltable and deformable at 400°C or below. In the conductive particles according to the present invention, the conductive portion may contain a component that can be metal-diffused at 400°C or below, and the conductive portion may be meltable and deformable at 400°C or below. In the conductive particles according to the present invention, the conductive portion may contain a component that can be metal-diffused at 400°C or below, and the conductive portion may be meltable and deformable at 400°C or below. In the conductive particles according to the present invention, the conductive portion has a solder portion. In the conductive particles according to the present invention, the area of ​​the portion with the solder portion is 99% or less of the total surface area of ​​the base particle.

[0024] In this invention, metal diffusion refers to the diffusion of metal atoms in conductive parts and connection parts due to heat, pressure, deformation, etc.

[0025] In this invention, melt deformation refers to a state in which some or all of its components melt, making it easily deformable by external pressure.

[0026] Since the conductive particles according to the present invention have the above-described configuration, the occurrence of aggregation between conductive particles can be effectively suppressed.

[0027] In recent years, electronic devices have become thinner and smaller. As a result, conventional pin connections between circuit boards and electronic components are no longer sufficient to accommodate the narrower pin pitches. Therefore, solder paste and similar materials are sometimes used for electrical connections between circuit boards and electronic components.

[0028] However, with conventional solder pastes, aggregation of solder particles can occur.

[0029] The inventors have found that aggregation of conductive particles can be suppressed by using specific conductive particles. In the present invention, the conductive portion contains a component that can undergo metal diffusion at 400°C or below, or the conductive portion is meltable and deformable at 400°C or below. In the conductive particles according to the present invention, the conductive portion has a solder portion. Preferably, the solder portion is solder granules. In the conductive particles according to the present invention, the conductive portion can form a metallic bond with a joint portion such as an electrode, and the solder portion (solder granules) can form a metallic bond with a joint portion such as an electrode. Therefore, significantly better conductivity characteristics can be obtained than with conventional physical contact. Furthermore, in the conductive particles according to the present invention, since the solder portion (solder granules) can form a metallic bond with a joint portion such as an electrode, it is not necessary to melt the entire conductive portion during joining. As a result, in the present invention, the conductivity reliability between electrodes can be improved even when the thickness of the conductive portion is relatively thin. Furthermore, in the present invention, since it is not necessary to increase the thickness of the conductive portion, aggregation of conductive particles can be effectively suppressed.

[0030] In this invention, using specific conductive particles greatly contributes to achieving the effects described above.

[0031] The temperature at which the components of the conductive part can undergo metal diffusion and the melting deformation temperature of the conductive part can be achieved by selecting the material of the conductive part. For example, by using solder or a solder alloy as the material of the conductive part and forming a solder portion, it is easy to set the temperature at which the components of the conductive part can undergo metal diffusion and the melting deformation temperature of the conductive part to 400°C or less. In the conductive particles, the conductive part has a solder portion. The conductive part may also be a solder portion.

[0032] The metal diffusion state of the conductive part described above is evaluated as follows.

[0033] Prepare a conductive paste containing 10% by weight of conductive particles.

[0034] A transparent glass substrate with copper electrodes on its upper surface is prepared. A semiconductor chip with gold electrodes on its lower surface is also prepared.

[0035] A conductive paste is applied to the transparent glass substrate to form a conductive paste layer. Next, the semiconductor chips are stacked on the conductive paste layer so that their electrodes face each other. Then, while adjusting the temperature of the head so that the temperature of the conductive paste layer reaches 250°C, a pressurized heating head is placed on the top surface of the semiconductor chips, and a pressure of 0.5 MPa is applied to cure the conductive paste layer at 250°C to obtain a connection structure.

[0036] The connecting structure is mechanically polished so as to pass through the center, and the cross-section of the conductive particles is cut out using an ion milling device. Alternatively, to facilitate the mechanical polishing of the connecting structure, it may be embedded in resin, and the embedded connecting structure may be mechanically polished.

[0037] Next, using a transmission electron microscope (FE-TEM), the diffusion state of the metal is observed by line analysis or elemental mapping of the contact area between the conductive particles and the copper and gold electrodes using an energy-dispersive X-ray spectrometer (EDX).

[0038] By observing the diffusion state of the above-mentioned metal, it can be confirmed that the outer periphery of the conductive particles is undergoing metallic diffusion relative to the copper and gold electrodes.

[0039] Furthermore, by mapping the diffusion state of the above-mentioned metals, the contact ratio between the outer surface of the conductive particles and the copper and gold electrodes can be calculated, thereby enabling quantitative analysis.

[0040] The melting deformation temperature of the conductive part described above is evaluated as follows.

[0041] The melting and deformation temperature of the conductive part can be measured using a differential scanning calorimeter (DSC-6300, manufactured by Yamato Scientific Co., Ltd.). The measurement is performed using 15 g of conductive particles under the following conditions: heating range of 30°C to 500°C, heating rate of 5°C / min, and nitrogen purge rate of 5 ml / min.

[0042] Next, confirm that the conductive part has melted at the melting temperature obtained in the above measurement. Place 1 g of conductive particles in a container and put it in an electric furnace. Set the electric furnace to the same temperature as the melting temperature obtained in the above measurement and heat it in a nitrogen atmosphere for 10 minutes. After that, remove the heated conductive particles from the electric furnace and check the melted state (or solidified state after melting) of the conductive part using a scanning electron microscope. Alternatively, the conductive part may be melted and deformed by melting a portion of the conductive part, such as the solder part (solder grains).

[0043] In the conductive particles according to the present invention, the area of ​​the solder portion (solder coverage) is 99% or less of the total surface area of ​​the base particle. The area of ​​the solder portion (solder coverage) is preferably 95% or less, more preferably 90% or less, even more preferably 85% or less, and particularly preferably 70% or less of the total surface area of ​​the base particle. The area of ​​the solder portion (solder coverage) is preferably 5% or more, more preferably 30% or more, and even more preferably 60% or more of the total surface area of ​​the base particle. When the coverage (solder coverage) is above the lower limit and below the upper limit, the occurrence of aggregation between conductive particles can be suppressed more effectively. When the coverage (solder coverage) is above the lower limit, metallic bonding can be formed more easily between the solder portion and the joint portion such as an electrode.

[0044] The area of ​​the solder portion (solder coverage) within 100% of the total surface area of ​​the above-mentioned substrate particles can be calculated by performing elemental mapping by SEM-EDX analysis of the cross-section of the conductive particles and then performing image analysis.

[0045] The particle size of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 500 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, particularly preferably 20 μm or less, and most preferably 10 μm or less. When the particle size of the conductive particles is above the lower limit and below the upper limit, the contact area between the conductive particles and the electrode can be sufficiently large, and aggregated conductive particles are less likely to form when forming the conductive part, making it less likely for the conductive part to peel off from the surface of the substrate particles.

[0046] The particle diameter of the conductive particles described above is preferably the average particle diameter, and more preferably the number-average particle diameter. The particle diameter of the conductive particles can be determined, for example, by observing 50 arbitrary conductive particles with an electron microscope or optical microscope and calculating the average particle diameter of each conductive particle, or by using a particle size distribution analyzer. In observation with an electron microscope or optical microscope, the particle diameter of a single conductive particle is determined as the particle diameter at the equivalent diameter of a circle. In observation with an electron microscope or optical microscope, the average particle diameter at the equivalent diameter of a circle of any 50 conductive particles is approximately equal to the average particle diameter at the equivalent diameter of a sphere. In a particle size distribution analyzer, the particle diameter of a single conductive particle is determined as the particle diameter at the equivalent diameter of a sphere. It is preferable to calculate the average particle diameter of the conductive particles using a particle size distribution analyzer.

[0047] The coefficient of variation (CV value) of the particle size of the conductive particles is preferably 10% or less, more preferably 5% or less. When the coefficient of variation of the particle size of the conductive particles is below the upper limit, the contact area between the conductive particles and the electrode can be sufficiently large.

[0048] The coefficient of variation (CV value) mentioned above can be measured as follows.

[0049] CV value (%) = (ρ / Dn) × 100 ρ: Standard deviation of the particle size of conductive particles Dn: Average particle size of conductive particles

[0050] The shape of the conductive particles is not particularly limited. The conductive particles may be spherical, or have other shapes, such as flattened shapes.

[0051] The present invention will be described in detail below with reference to the drawings.

[0052] Figure 1 is a cross-sectional view showing conductive particles according to the first embodiment of the present invention.

[0053] The conductive particle 1 shown in Figure 1 comprises a base particle 2 and a conductive portion 3 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 covered by the conductive portion 3.

[0054] The conductive portion 3 as a whole has a first conductive portion 3A disposed on the surface of the base particle 2 and a second conductive portion (solder portion) 3B disposed on the surface of the first conductive portion 3A. The first conductive portion 3A is disposed on the surface of the base particle 2. The first conductive portion 3A is disposed between the base particle 2 and the second conductive portion (solder portion) 3B. The first conductive portion 3A is in contact with the base particle 2. The second conductive portion (solder portion) 3B is in contact with the first conductive portion 3A. Therefore, the first conductive portion 3A is disposed on the surface of the base particle 2, and the second conductive portion (solder portion) 3B is disposed on the surface of the first conductive portion 3A. In the above conductive particle, the base particle may or may not be completely covered by the first conductive portion. The base particle may have portions that are not covered by the first conductive portion. The first conductive part and the second conductive part (solder part) may be formed as different conductive parts or as the same conductive part. The second conductive part (solder part) is formed of solder. Preferably, the second conductive part (solder part) is solder granules, as described later. In the conductive granules, the first conductive part is arranged on the surface of the base material granules, and preferably, the solder granules are arranged on the surface of the first conductive part.

[0055] In conductive particle 1, the conductive part 3 contains a component that can undergo metal diffusion at 400°C or below, or the conductive part 3 is melt-deformable at 400°C or below. The conductive part 3 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive part 3 may be melt-deformable at 400°C or below. The conductive part 3 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive part 3 may be melt-deformable at 400°C or below. In conductive particle 1, the second conductive part 3B (solder part) is a component that can undergo metal diffusion at 400°C or below. In conductive particle 1, the second conductive part 3B (solder part) is melt-deformable at 400°C or below. In the above conductive particle, the first conductive part may be a component that can undergo metal diffusion at 400°C or below, and the first conductive part may be melt-deformable at 400°C or below. In the conductive particles described above, the first conductive portion and the second conductive portion (solder portion) may be composed of a material that can undergo metal diffusion at 400°C or below, and the first conductive portion and the second conductive portion (solder portion) may be meltable and deformable at 400°C or below.

[0056] Figure 2 is a cross-sectional view showing conductive particles according to a second embodiment of the present invention.

[0057] The conductive particle 11 shown in Figure 2 comprises a base particle 2 and a conductive portion 12 disposed on the surface of the base particle 2. In the second embodiment, the conductive portion 12 is in contact with the surface of the base particle 2. The conductive particle 11 is a coated particle in which the surface of the base particle 2 is covered by the conductive portion 12.

[0058] The only difference between conductive particle 1 and conductive particle 11 is the first conductive portion. Specifically, conductive particle 1 has a single-layer first conductive portion 3A, while conductive particle 11 has a two-layer first conductive portion consisting of a firsta conductive portion 12A and a firstb conductive portion 12B.

[0059] The conductive portion 12 as a whole has a first a conductive portion 12A disposed on the surface of the base particle 2, a first b conductive portion 12B disposed on the surface of the first a conductive portion 12A, and a second conductive portion (solder portion) 12C disposed on the surface of the first b conductive portion 12B. The first a conductive portion 12A is disposed on the surface of the base particle 2. The first b conductive portion 12B is disposed on the surface of the first a conductive portion 12A. The first a conductive portion 12A and the first b conductive portion 12B are disposed between the base particle 2 and the second conductive portion (solder portion) 12C. The first a conductive portion 12A is in contact with the base particle 2. The second conductive portion (solder portion) 12C is in contact with the first b conductive portion 12B. Accordingly, the first conductive portion 12A is arranged on the surface of the base particle 2, the first conductive portion 12B is arranged on the surface of the first conductive portion 12A, and the second conductive portion (solder portion) 12C is arranged on the surface of the first conductive portion 12B. In the above conductive particles, the base particle may or may not be completely covered by the first conductive portion and the first conductive portion. The base particle may have portions that are not covered by the first conductive portion and the first conductive portion. The first conductive portion, the first conductive portion and the second conductive portion (solder portion) may be formed as different conductive portions or as the same conductive portion. The second conductive portion (solder portion) is formed of solder. Preferably, the second conductive portion (solder portion) is solder granules as described later. In the conductive particles described above, it is preferable that the conductive portion of 1a is arranged on the surface of the substrate particles, the conductive portion of 1b is arranged on the surface of the conductive portion of 1a, and the solder particles are arranged on the surface of the conductive portion of 1b.

[0060] In conductive particles 11, the conductive portion 12 contains a component that can undergo metal diffusion at 400°C or below, or the conductive portion 12 is melt-deformable at 400°C or below. The conductive portion 12 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 12 may be melt-deformable at 400°C or below. The conductive portion 12 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 12 may be melt-deformable at 400°C or below. In conductive particles 11, the second conductive portion 12C (solder portion) is a component that can undergo metal diffusion at 400°C or below. In conductive particles 11, the second conductive portion 12C (solder portion) is melt-deformable at 400°C or below. In the above conductive particles, the conductive portion 1a or the conductive portion 1b may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 1a or the conductive portion 1b may be melt-deformable at 400°C or below. In the conductive particles described above, the conductive portion of the first a, the conductive portion of the first b, and the second conductive portion (solder portion) may be composed of a material that can undergo metal diffusion at 400°C or below, and the conductive portion of the first a, the conductive portion of the first b, and the second conductive portion (solder portion) may be meltable and deformable at 400°C or below.

[0061] Figure 3 is a cross-sectional view showing conductive particles according to a third embodiment of the present invention.

[0062] The conductive particle 21 shown in Figure 3 comprises a base particle 2 and a conductive portion 22 disposed on the surface of the base particle 2. In the third embodiment, the conductive portion 22 is in contact with the surface of the base particle 2. The conductive particle 21 is a coated particle in which the surface of the base particle 2 is covered with the conductive portion 22.

[0063] The only difference between conductive particle 1 and conductive particle 21 is the shape of the second conductive part (solder part). Specifically, in conductive particle 1, the shape of the second conductive part (solder part) 3B is that of a part of a sphere, whereas in conductive particle 21, the shape of the second conductive part (solder part) 22B is needle-shaped and paraboloidal in shape.

[0064] The conductive portion 22 as a whole has a first conductive portion 22A disposed on the surface of the base particle 2 and a second conductive portion (solder portion) 22B disposed on the surface of the first conductive portion 22A. 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 (solder portion) 22B. The first conductive portion 22A is in contact with the base particle 2. The second conductive portion (solder portion) 22B is in contact with the first conductive portion 22A. Therefore, the first conductive portion 22A is disposed on the surface of the base particle 2, and the second conductive portion (solder portion) 22B is disposed on the surface of the first conductive portion 22A. In the above conductive particle, the base particle may or may not be completely covered by the first conductive portion. The base particle may have portions that are not covered by the first conductive portion. The first conductive part and the second conductive part (solder part) may be formed as different conductive parts or as the same conductive part. The second conductive part (solder part) is formed of solder. Preferably, the second conductive part (solder part) is solder granules as described later.

[0065] In conductive particles 21, the conductive portion 22 contains a component that can undergo metal diffusion at 400°C or below, or the conductive portion 22 is melt-deformable at 400°C or below. The conductive portion 22 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 22 may be melt-deformable at 400°C or below. The conductive portion 22 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 22 may be melt-deformable at 400°C or below. In conductive particles 21, the second conductive portion 22B (solder portion) is a component that can undergo metal diffusion at 400°C or below. In conductive particles 21, the second conductive portion 22B (solder portion) is melt-deformable at 400°C or below. In the above conductive particles, the first conductive portion may contain a component that can undergo metal diffusion at 400°C or below, and the first conductive portion may be melt-deformable at 400°C or below. In the conductive particles described above, the first conductive portion and the second conductive portion (solder portion) may be composed of a material that can undergo metal diffusion at 400°C or below, and the first conductive portion and the second conductive portion (solder portion) may be meltable and deformable at 400°C or below.

[0066] Figure 4 is a cross-sectional view showing conductive particles according to a fourth embodiment of the present invention.

[0067] The conductive particle 31 shown in Figure 4 comprises a base particle 2 and a conductive portion 32 disposed on the surface of the base particle 2. In the fourth embodiment, the conductive portion 32 is in contact with the surface of the base particle 2. The conductive particle 31 is a coated particle in which the surface of the base particle 2 is covered with the conductive portion 32.

[0068] The conductive particles 21 and 31 differ only in their conductive portions. Specifically, in conductive particle 21, the conductive portion 22 is formed by a first conductive portion 22A and a second conductive portion (solder portion) 22B, whereas in conductive particle 31, the conductive portion 32 is formed by a first conductive portion 32A, a second conductive portion (solder portion) 32B and a third conductive portion 32C.

[0069] The conductive portion 32 as a whole has a first conductive portion 32A disposed on the surface of the base particle 2, a second conductive portion (solder portion) 32B disposed on the surface of the first conductive portion 32A, and a third conductive portion 32C disposed on the surfaces of the first conductive portion 32A and the second conductive portion (solder portion) 32B. The first conductive portion 32A is disposed on the surface of the base particle 2. The third conductive portion 32C is disposed on the surfaces of the first conductive portion 32A and the second conductive portion (solder portion) 32B. The first conductive portion 32A is in contact with the base particle 2. The second conductive portion (solder portion) 32B is in contact with the first conductive portion 32A. The third conductive portion 32C is in contact with the first conductive portion 32A and the second conductive portion (solder portion) 32B. Therefore, the first conductive portion 32A is located on the surface of the base particle 2, the second conductive portion (solder portion) 32B is located on the surface of the first conductive portion 32A, and the third conductive portion 32C is located on the surfaces of the first conductive portion 32A and the second conductive portion (solder portion) 32B. In the above conductive particles, the base particle may or may not be completely covered by the first conductive portion. The base particle may have portions that are not covered by the first conductive portion. In the above conductive particles, the base particle may or may not be completely covered by the third conductive portion. The base particle may have portions that are not covered by the third conductive portion. The first conductive part, the second conductive part (solder part), and the third conductive part may be formed as different conductive parts or as the same conductive part. The second conductive part (solder part) is formed of solder. Preferably, the second conductive part (solder part) is solder granules, as described later. In the conductive particles, it is preferable that the first conductive part is arranged on the surface of the base particle, the solder granules are arranged on the surface of the first conductive part, and the third conductive part is arranged on the surfaces of the first conductive part and the solder granules.

[0070] In conductive particles 31, the conductive portion 32 contains a component that can undergo metal diffusion at 400°C or below, or the conductive portion 32 is melt-deformable at 400°C or below. The conductive portion 32 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 32 may be melt-deformable at 400°C or below. The conductive portion 32 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 32 may be melt-deformable at 400°C or below. In conductive particles 31, the second conductive portion 32B (solder portion) is a component that can undergo metal diffusion at 400°C or below. In conductive particles 31, the second conductive portion 32B (solder portion) is melt-deformable at 400°C or below. In the above conductive particles, the first conductive portion may contain a component that can undergo metal diffusion at 400°C or below, and the first conductive portion may be melt-deformable at 400°C or below. In the conductive particles described above, the third conductive portion may be a component that can undergo metal diffusion at 400°C or below, and the third conductive portion may be melt-deformable at 400°C or below. In the conductive particles described above, the first conductive portion, the second conductive portion (solder portion), and the third conductive portion may be a component that can undergo metal diffusion at 400°C or below, and the first conductive portion, the second conductive portion (solder portion), and the third conductive portion may be melt-deformable at 400°C or below.

[0071] Figure 5 is a cross-sectional view showing conductive particles according to the fifth embodiment of the present invention.

[0072] The conductive particle 41 shown in Figure 5 comprises a base particle 2, a conductive portion 42 disposed on the surface of the base particle 2, and a metal colloid precipitate 43 disposed on the surface of the conductive portion 42. In the fifth embodiment, the conductive portion 42 is in contact with the surface of the base particle 2. The conductive particle 41 is a coated particle in which the surface of the base particle 2 is covered with the conductive portion 42.

[0073] The only difference between conductive particle 1 and conductive particle 41 is the presence or absence of metal colloid precipitates 43. That is, in conductive particle 1, no metal colloid precipitates are arranged on the surface of the conductive part 3, whereas in conductive particle 41, metal colloid precipitates 43 are arranged on the surface of the conductive part 42.

[0074] The conductive portion 42 as a whole has a first conductive portion 42A disposed on the surface of the base particle 2 and a second conductive portion (solder portion) 42B disposed on the surface of the first conductive portion 42A. The first conductive portion 42A is disposed on the surface of the base particle 2. The first conductive portion 42A is disposed between the base particle 2 and the second conductive portion (solder portion) 42B. The first conductive portion 42A is in contact with the base particle 2. The second conductive portion (solder portion) 42B is in contact with the first conductive portion 42A. Therefore, the first conductive portion 42A is disposed on the surface of the base particle 2, and the second conductive portion (solder portion) 42B is disposed on the surface of the first conductive portion 42A. In the above conductive particle, the base particle may or may not be completely covered by the first conductive portion. The base particle may have portions that are not covered by the first conductive portion. The first conductive part and the second conductive part (solder part) may be formed as different conductive parts or as the same conductive part. The second conductive part (solder part) is formed of solder. Preferably, the second conductive part (solder part) is solder granules, as described later. In the conductive granules, the first conductive part is arranged on the surface of the base material granules, and preferably, the solder granules are arranged on the surface of the first conductive part.

[0075] A metal colloid precipitate 43 is disposed on the surface of the conductive portion 42. The metal colloid precipitate may be disposed only on the surface of the first conductive portion, or only on the surface of the second conductive portion (solder portion), or on the surfaces of both the first conductive portion and the second conductive portion (solder portion). Preferably, the metal colloid precipitate is disposed only on the surface of the second conductive portion (solder portion), and preferably only on the surface of the solder particles. In the conductive particles, the conductive portion may or may not be completely covered by the metal colloid precipitate. The conductive portion may have portions that are not covered by the metal colloid precipitate.

[0076] In conductive particles 41, the conductive portion 42 contains a component that can undergo metal diffusion at 400°C or below, or the conductive portion 42 is melt-deformable at 400°C or below. The conductive portion 42 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 42 may be melt-deformable at 400°C or below. The conductive portion 42 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 42 may be melt-deformable at 400°C or below. In conductive particles 41, the second conductive portion 42B (solder portion) is a component that can undergo metal diffusion at 400°C or below. In conductive particles 41, the second conductive portion 42B (solder portion) is melt-deformable at 400°C or below. In the above conductive particles, the first conductive portion may contain a component that can undergo metal diffusion at 400°C or below, and the first conductive portion may be melt-deformable at 400°C or below. In the conductive particles described above, the first conductive portion and the second conductive portion (solder portion) may be composed of a material that can undergo metal diffusion at 400°C or below, and the first conductive portion and the second conductive portion (solder portion) may be meltable and deformable at 400°C or below.

[0077] Figure 6 is a cross-sectional view showing conductive particles according to the sixth embodiment of the present invention.

[0078] The conductive particle 51 shown in Figure 6 comprises a base particle 2, a conductive portion 52 disposed on the surface of the base particle 2, and a metal colloid precipitate 53 disposed on the surface of the conductive portion 52. In the sixth embodiment, the conductive portion 52 is in contact with the surface of the base particle 2. The conductive particle 51 is a coated particle in which the surface of the base particle 2 is covered with the conductive portion 52.

[0079] The only difference between conductive particles 11 and conductive particles 51 is the presence or absence of metal colloid deposits 53. Specifically, in conductive particles 11, no metal colloid deposits are present on the surface of the conductive portion 12, whereas in conductive particles 51, metal colloid deposits 53 are present on the surface of the conductive portion 52.

[0080] The conductive portion 52 as a whole has a first a conductive portion 52A disposed on the surface of the base particle 2, a first b conductive portion 52B disposed on the surface of the first a conductive portion 52A, and a second conductive portion (solder portion) 52C disposed on the surface of the first b conductive portion 52B. The first a conductive portion 52A is disposed on the surface of the base particle 2. The first b conductive portion 52B is disposed on the surface of the first a conductive portion 52A. The first a conductive portion 52A and the first b conductive portion 52B are disposed between the base particle 2 and the second conductive portion (solder portion) 52C. The first a conductive portion 52A is in contact with the base particle 2. The second conductive portion (solder portion) 52C is in contact with the first b conductive portion 52B. Accordingly, the first conductive portion 52A is arranged on the surface of the base particle 2, the first conductive portion 52B is arranged on the surface of the first conductive portion 52A, and the second conductive portion (solder portion) 52C is arranged on the surface of the first conductive portion 52B. In the above conductive particles, the base particle may or may not be completely covered by the first conductive portion and the first conductive portion. The base particle may have portions that are not covered by the first conductive portion and the first conductive portion. The first conductive portion, the first conductive portion and the second conductive portion (solder portion) may be formed as different conductive portions or as the same conductive portion. The second conductive portion (solder portion) is formed of solder. Preferably, the second conductive portion (solder portion) is solder granules as described later. In the conductive particles described above, it is preferable that the conductive portion of 1a is arranged on the surface of the substrate particles, the conductive portion of 1b is arranged on the surface of the conductive portion of 1a, and the solder particles are arranged on the surface of the conductive portion of 1b.

[0081] A metal colloid precipitate 53 is disposed on the surface of the conductive portion 52. The metal colloid precipitate may be disposed only on the surface of the first conductive portion 1b, or only on the surface of the second conductive portion (solder portion), or on the surfaces of both the first conductive portion 1b and the second conductive portion (solder portion). Preferably, the metal colloid precipitate is disposed only on the surface of the second conductive portion (solder portion), and preferably only on the surface of the solder particles. In the conductive particles, the conductive portion may or may not be completely covered by the metal colloid precipitate. The conductive portion may have portions that are not covered by the metal colloid precipitate.

[0082] In conductive particles 51, the conductive portion 52 contains a component that can undergo metal diffusion at 400°C or below, or the conductive portion 52 is melt-deformable at 400°C or below. The conductive portion 52 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 52 may be melt-deformable at 400°C or below. The conductive portion 52 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 52 may be melt-deformable at 400°C or below. In conductive particles 51, the second conductive portion 52C (solder portion) is a component that can undergo metal diffusion at 400°C or below. In conductive particles 51, the second conductive portion 52C (solder portion) is melt-deformable at 400°C or below. In the above conductive particles, the conductive portion 1a or the conductive portion 1b may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 1a or the conductive portion 1b may be melt-deformable at 400°C or below. In the conductive particles described above, the conductive portion of the first a, the conductive portion of the first b, and the second conductive portion (solder portion) may be composed of a material that can undergo metal diffusion at 400°C or below, and the conductive portion of the first a, the conductive portion of the first b, and the second conductive portion (solder portion) may be meltable and deformable at 400°C or below.

[0083] Figure 7 is a cross-sectional view showing conductive particles according to the seventh embodiment of the present invention.

[0084] The conductive particle 61 shown in Figure 7 comprises a base particle 2, a conductive portion 62 disposed on the surface of the base particle 2, and a metal film 63 disposed on the surface of the conductive portion 62. In the seventh embodiment, the conductive portion 62 is in contact with the surface of the base particle 2. The conductive particle 61 is a coated particle in which the surface of the base particle 2 is covered with the conductive portion 62.

[0085] The only difference between conductive particle 1 and conductive particle 61 is the presence or absence of the metal film 63. That is, in conductive particle 1, the metal film is not placed on the surface of the conductive part 3, whereas in conductive particle 61, the metal film 63 is placed on the surface of the conductive part 62.

[0086] The conductive portion 62 as a whole has a first conductive portion 62A disposed on the surface of the base particle 2 and a second conductive portion (solder portion) 62B disposed on the surface of the first conductive portion 62A. The first conductive portion 62A is disposed on the surface of the base particle 2. The first conductive portion 62A is disposed between the base particle 2 and the second conductive portion (solder portion) 62B. The first conductive portion 62A is in contact with the base particle 2. The second conductive portion (solder portion) 62B is in contact with the first conductive portion 62A. Therefore, the first conductive portion 62A is disposed on the surface of the base particle 2, and the second conductive portion (solder portion) 62B is disposed on the surface of the first conductive portion 62A. In the above conductive particle, the base particle may or may not be completely covered by the first conductive portion. The base particle may have portions that are not covered by the first conductive portion. The first conductive part and the second conductive part (solder part) may be formed as different conductive parts or as the same conductive part. The second conductive part (solder part) is formed of solder. Preferably, the second conductive part (solder part) is solder granules, as described later. In the conductive granules, the first conductive part is arranged on the surface of the base material granules, and preferably, the solder granules are arranged on the surface of the first conductive part.

[0087] A metal film 63 is disposed on the surface of the conductive portion 62. The metal film may be disposed only on the surface of the first conductive portion, or only on the surface of the second conductive portion (solder portion), or on the surfaces of both the first conductive portion and the second conductive portion (solder portion). Preferably, the metal film is disposed only on the surface of the second conductive portion (solder portion), and preferably only on the surface of the solder particles. In the conductive particles, the conductive portion may or may not be completely covered by the metal film. The conductive portion may have portions that are not covered by the metal film.

[0088] In conductive particles 61, the conductive portion 62 contains a component that can undergo metal diffusion at 400°C or below, or the conductive portion 62 is meltable and deformable at 400°C or below. The conductive portion 62 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 62 may be meltable and deformable at 400°C or below. The conductive portion 62 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 62 may be meltable and deformable at 400°C or below. In conductive particles 61, the second conductive portion 62B (solder portion) is a component that can undergo metal diffusion at 400°C or below. In conductive particles 61, the second conductive portion 62B (solder portion) is meltable and deformable at 400°C or below. In the above conductive particles, the first conductive portion may contain a component that can undergo metal diffusion at 400°C or below, and the first conductive portion may be meltable and deformable at 400°C or below. In the conductive particles described above, the first conductive portion and the second conductive portion (solder portion) may be composed of a material that can undergo metal diffusion at 400°C or below, and the first conductive portion and the second conductive portion (solder portion) may be meltable and deformable at 400°C or below.

[0089] Figure 8 is a cross-sectional view showing conductive particles according to the eighth embodiment of the present invention.

[0090] The conductive particle 71 shown in Figure 8 comprises a base particle 2, a conductive portion 72 disposed on the surface of the base particle 2, and a metal film 73 disposed on the surface of the conductive portion 72. In the eighth embodiment, the conductive portion 72 is in contact with the surface of the base particle 2. The conductive particle 71 is a coated particle in which the surface of the base particle 2 is covered with the conductive portion 72.

[0091] The only difference between conductive particles 11 and conductive particles 71 is the presence or absence of the metal film 73. That is, in conductive particles 11, the metal film is not placed on the surface of the conductive portion 12, whereas in conductive particles 71, the metal film 73 is placed on the surface of the conductive portion 72.

[0092] The conductive portion 72 as a whole has a first a conductive portion 72A disposed on the surface of the base particle 2, a first b conductive portion 72B disposed on the surface of the first a conductive portion 72A, and a second conductive portion (solder portion) 72C disposed on the surface of the first b conductive portion 72B. The first a conductive portion 72A is disposed on the surface of the base particle 2. The first b conductive portion 72B is disposed on the surface of the first a conductive portion 72A. The first a conductive portion 72A and the first b conductive portion 72B are disposed between the base particle 2 and the second conductive portion (solder portion) 72C. The first a conductive portion 72A is in contact with the base particle 2. The second conductive portion (solder portion) 72C is in contact with the first b conductive portion 72B. Accordingly, the first conductive portion 72A is arranged on the surface of the base particle 2, the first conductive portion 72B is arranged on the surface of the first conductive portion 72A, and the second conductive portion (solder portion) 72C is arranged on the surface of the first conductive portion 72B. In the above conductive particles, the base particle may or may not be completely covered by the first conductive portion and the first conductive portion. The base particle may have portions that are not covered by the first conductive portion and the first conductive portion. The first conductive portion, the first conductive portion and the second conductive portion (solder portion) may be formed as different conductive portions or as the same conductive portion. The second conductive portion (solder portion) is formed of solder. Preferably, the second conductive portion (solder portion) is solder granules as described later. In the conductive particles described above, it is preferable that the conductive portion of 1a is arranged on the surface of the substrate particles, the conductive portion of 1b is arranged on the surface of the conductive portion of 1a, and the solder particles are arranged on the surface of the conductive portion of 1b.

[0093] A metal film 73 is disposed on the surface of the conductive portion 72. The metal film may be disposed only on the surface of the first conductive portion 1b, or only on the surface of the second conductive portion (solder portion), or on the surfaces of both the first conductive portion 1b and the second conductive portion (solder portion). Preferably, the metal film is disposed only on the surface of the second conductive portion (solder portion), and preferably only on the surface of the solder particles. In the conductive particles, the conductive portion may or may not be completely covered by the metal film. The conductive portion may have portions that are not covered by the metal film.

[0094] In conductive particles 71, the conductive portion 72 contains a component that can undergo metal diffusion at 400°C or below, or the conductive portion 72 is melt-deformable at 400°C or below. The conductive portion 72 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 72 may be melt-deformable at 400°C or below. The conductive portion 72 may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 72 may be melt-deformable at 400°C or below. In conductive particles 71, the second conductive portion 72C (solder portion) is a component that can undergo metal diffusion at 400°C or below. In conductive particles 71, the second conductive portion 72C (solder portion) is melt-deformable at 400°C or below. In the above conductive particles, the conductive portion 1a or the conductive portion 1b may contain a component that can undergo metal diffusion at 400°C or below, and the conductive portion 1a or the conductive portion 1b may be melt-deformable at 400°C or below. In the conductive particles described above, the conductive portion of the first a, the conductive portion of the first b, and the second conductive portion (solder portion) may be composed of a material that can undergo metal diffusion at 400°C or below, and the conductive portion of the first a, the conductive portion of the first b, and the second conductive portion (solder portion) may be meltable and deformable at 400°C or below.

[0095] Further details about conductive particles are described below. In the following description, "(meth)acrylic" means either or both "acrylic" and "methacrylic," "(meth)acryloxy" means either or both "acryloxy" and "methacryloxy," and "(meth)acrylate" means either or both "acrylate" and "methacrylate."

[0096] (base material particles) The material of the above-mentioned base material particles is not particularly limited. The material of the above-mentioned base material particles may be an organic material or an inorganic material. Examples of base material particles formed solely from the above-mentioned organic material include resin particles. Examples of base material particles formed solely from the above-mentioned inorganic material include inorganic particles excluding metals. Examples of base material particles formed from both the above-mentioned organic material and the above-mentioned inorganic material include organic-inorganic hybrid particles. From the viewpoint of further improving the compressibility of the base material particles, the above-mentioned base material particles are preferably resin particles or organic-inorganic hybrid particles, and more preferably resin particles.

[0097] Examples of the above organic materials include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyamide-imide, polyetheretherketone, polyethersulfone, divinylbenzene polymers, and divinylbenzene copolymers. Examples of the above divinylbenzene copolymers include divinylbenzene-styrene copolymers and divinylbenzene-(meth)acrylic acid ester copolymers. Since the compression characteristics of the above-mentioned base material particles can be easily controlled to a suitable range, it is preferable that the material of the above-mentioned base material particles is a polymer obtained by polymerizing one or more polymerizable monomers having ethylenically unsaturated groups.

[0098] When the above-mentioned base material particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group can be a non-crosslinked monomer or a crosslinked monomer.

[0099] The above non-crosslinked monomers include vinyl compounds such as styrene monomers like styrene, α-methylstyrene, and chlorostyrene; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; vinyl acid ester compounds such as vinyl acetate, vinyl butyrate, vinyl laurate, and vinyl stearate; halogen-containing monomers such as vinyl chloride and vinyl fluoride; and (meth)acrylic compounds such as 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, and cyclohexyl Alkyl (meth)acrylate compounds such as (meth)acrylate and isobornyl (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; halogen-containing (meth)acrylate compounds such as trifluoromethyl (meth)acrylate and pentafluoroethyl (meth)acrylate; olefin compounds such as diisobutylene, isobutylene, linearene, ethylene, and propylene as α-olefin compounds; and isoprene and butadiene as conjugated diene compounds.

[0100] The above crosslinkable monomers include vinyl monomers such as divinylbenzene, 1,4-divinyloxybutane, and divinylsulfone; polyfunctional (meth)acrylate compounds such as tetramethylolmethane tetra(meth)acrylate, polytetramethylene glycol diacrylate, 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, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; and allyl compounds. Examples include triallyl(iso)cyanurate, triallyl trimellitate, diallyl phthalate, diallyl acrylamide, and diallyl ether; as silane compounds, silane alkoxide compounds such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, isopropyltrimethoxysilane, isobutyltrimethoxysilane, cyclohexyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, trimethoxysilylstyrene, γ-(meth)acryloxypropyltrimethoxysilane, 1,3-divinyltetramethyldisiloxane, methylphenyldimethoxysilane, and diphenyldimethoxysilane;Examples include polymerizable double-bond-containing silane alkoxides such as vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsilane, dimethoxyethylvinylsilane, diethoxymethylvinylsilane, diethoxyethylvinylsilane, ethylmethyldivinylsilane, methylvinyldimethoxysilane, ethylvinyldimethoxysilane, methylvinyldiethoxysilane, ethylvinyldiethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane; cyclic siloxanes such as decamethylcyclopentasiloxane; modified (reactive) silicone oils such as one-ended modified silicone oil, two-ended silicone oil, and side-chain type silicone oil; and carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride.

[0101] Examples of the inorganic materials mentioned above include silica, alumina, barium titanate, zirconia, carbon black, silicate glass, borosilicate glass, lead glass, soda-lime glass, and alumina silicate glass.

[0102] The above-mentioned base material particles may be organic-inorganic hybrid particles. The above-mentioned base material particles may also be core-shell particles. When the above-mentioned base material particles are organic-inorganic hybrid particles, examples of inorganic materials for the above-mentioned base material particles include silica, alumina, barium titanate, zirconia, and carbon black. It is preferable that the above-mentioned inorganic material is not a metal. The above-mentioned base material particles formed from silica are not particularly limited, but examples include base material particles obtained by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, and then firing as necessary. Examples of the above-mentioned organic-inorganic hybrid particles include organic-inorganic hybrid particles formed from a crosslinked alkoxysilyl polymer and an acrylic resin.

[0103] The above organic-inorganic hybrid particles are preferably core-shell type organic-inorganic hybrid particles having a core and a shell disposed on the surface of the core. The core is preferably an organic core. The shell is preferably an inorganic shell. The above substrate particles are preferably organic-inorganic hybrid particles having an organic core and an inorganic shell disposed on the surface of the organic core.

[0104] Examples of materials for the above-mentioned organic core include the organic materials mentioned above.

[0105] Examples of materials for the inorganic shell include the inorganic substances listed above as materials for the base particles. The material for the inorganic shell is preferably silica. The inorganic shell is preferably formed by forming a shell-like substance from a metal alkoxide on the surface of the core using a sol-gel method, and then firing the shell-like substance. The metal alkoxide is preferably a silane alkoxide. The inorganic shell is preferably formed from a silane alkoxide.

[0106] The particle size of the above-mentioned base material particles is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 500 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, particularly preferably 20 μm or less, and most preferably 10 μm or less. When the particle size of the above-mentioned base material particles is above the lower limit and below the upper limit, it can be used even more suitably to obtain conductive particles. When the particle size of the above-mentioned base material particles is above the lower limit and below the upper limit, the contact area between the conductive particles and the electrode can be sufficiently increased, and aggregated conductive particles are less likely to form when forming the conductive part, and the conductive part is less likely to peel off from the surface of the base material particles.

[0107] The particle size of the above-mentioned base material particles is particularly preferably between 1 μm and 50 μm. When the particle size of the above-mentioned base material particles is within the range of 1 μm and 50 μm, aggregation becomes less likely when forming a conductive portion on the surface of the base material particles, and aggregated conductive particles are less likely to be formed. Furthermore, when the particle size of the above-mentioned base material particles is within the range of 1 μm and 50 μm, it can be used even more suitably to obtain conductive particles.

[0108] The particle size of the above-mentioned base material particles refers to the diameter if the base material particles are spherical, and if the base material particles are not spherical, it refers to the diameter assuming they are spherical to the extent of their volume.

[0109] The particle diameter of the above-mentioned substrate particles represents the number-average particle diameter. The particle diameter of the above-mentioned substrate particles can be determined by observing 50 arbitrary substrate particles with an electron microscope or optical microscope and calculating the average particle diameter of each substrate particle, or by using a particle size distribution analyzer. When observing with an electron microscope or optical microscope, the particle diameter of a single substrate particle is determined as the particle diameter at the equivalent diameter of a circle. When observing with an electron microscope or optical microscope, the average particle diameter at the equivalent diameter of a circle of any 50 substrate particles is approximately equal to the average particle diameter at the equivalent diameter of a sphere. When using a particle size distribution analyzer, the particle diameter of a single substrate particle is determined as the particle diameter at the equivalent diameter of a sphere. It is preferable to calculate the average particle diameter of the above-mentioned substrate particles using a particle size distribution analyzer. When measuring the particle diameter of conductive particles, for example, it can be measured as follows.

[0110] A resin body for conductive particle testing is prepared by adding conductive particles to Kulzer's "Technovit 4000" so that the conductive particle content is 30% by weight, and then dispersing them. A cross-section of the conductive particles is cut out using an ion milling device (Hitachi High-Technologies Corporation's "IM4000") so as to pass through the vicinity of the center of the conductive particles dispersed in the resin body for testing. Then, using a field emission scanning electron microscope (FE-SEM), 50 conductive particles are randomly selected, and the base particles of each conductive particle are observed. The particle diameter of the base particles in each conductive particle is measured, and these are arithmetic mean to obtain the particle diameter of the base particles.

[0111] (Conductive part) The conductive particles according to the present invention comprise a base particle and a conductive portion disposed on the surface of the base particle. The conductive portion preferably contains a metal.

[0112] In the conductive particles described above, the conductive portion contains a component that can undergo metal diffusion at 400°C or below, or the conductive portion can melt and deform at 400°C or below. By lowering the temperature at which metal diffusion occurs, metallic bonding can be formed more easily with bonding portions such as electrodes. For this reason, the temperature at which metal diffusion occurs is preferably 350°C or below, more preferably 300°C or below, even more preferably 250°C or below, and particularly preferably 200°C or below. The temperature at which metal diffusion occurs can be controlled depending on the type of metal.

[0113] Furthermore, it is preferable that the conductive part is meltable and deformable at 400°C or below. Preferably, the conductive part is meltable and deformable at 350°C or below, more preferably at 300°C or below, even more preferably at 250°C or below, and particularly preferably at 200°C or below. If the melting and deformation temperature of the conductive part is within the above preferred range, the melting and deformation temperature can be lowered, the amount of energy consumed during heating can be reduced, and thermal degradation of the connected member can be suppressed. The melting and deformation temperature of the conductive part can be controlled by the type of metal of the conductive part. The conductive part may have portions exceeding 200°C, portions exceeding 250°C, portions exceeding 300°C, portions exceeding 350°C, and portions exceeding 400°C.

[0114] The metal constituting the conductive part is not particularly limited. Examples of metals constituting the conductive part include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, tungsten, molybdenum, and alloys thereof. Furthermore, examples of metals constituting the conductive part include tin-doped indium oxide (ITO) and solder. Only one type of metal may be used to constitute the conductive part, or two or more types may be used in combination.

[0115] In the present invention, it is preferable that the metal constituting the conductive part is selected such that the conductive part contains a component that can be metal-diffused at 400°C or below, and that the conductive part can be melted and deformed at 400°C or below. The conductive part preferably contains solder, and preferably has a soldered portion. The soldered portion is formed by solder. It is preferable that the conductive part has a soldered portion formed by solder.

[0116] From the viewpoint of more effectively lowering the connection resistance, the conductive part preferably contains nickel, gold, palladium, silver, copper, tin, or an alloy containing tin, and more preferably contains nickel, gold, palladium, tin, or an alloy containing tin.

[0117] In 100% by weight of the conductive part containing silver, the silver content is preferably 0.1% by weight or more, more preferably 1% by weight or more, preferably 100% by weight or less, and more preferably 90% by weight or less. The silver content may be 80% by weight or less, 60% by weight or less, 40% by weight or less, 20% by weight or less, or 10% by weight or less. When the silver content is above the lower limit and below the upper limit, the occurrence of aggregation between conductive particles can be suppressed even more effectively.

[0118] In 100% by weight of the conductive part containing copper, the copper content is preferably 0.1% by weight or more, more preferably 1% by weight or more, preferably 100% by weight or less, and more preferably 90% by weight or less. The copper content may be 80% by weight or less, 60% by weight or less, 40% by weight or less, 20% by weight or less, or 10% by weight or less. When the copper content is above the lower limit and below the upper limit, the occurrence of aggregation between conductive particles can be suppressed even more effectively.

[0119] In 100% by weight of the conductive portion containing tin or a tin-containing alloy, the content of tin or a tin-containing alloy is preferably 20% by weight or more, more preferably 50% by weight or more, and particularly preferably 90% by weight or more. When the content of tin or the tin-containing alloy is above the lower limit, the occurrence of aggregation between conductive particles can be suppressed even more effectively.

[0120] The solder described above is preferably a metal with a melting point of 450°C or lower (low melting point metal). A low melting point metal refers to a metal with a melting point of 450°C or lower. The melting point of the low melting point metal is preferably 300°C or lower, more preferably 160°C or lower. The solder also contains tin. The tin content in the solder is preferably 30% by weight or more, more preferably 40% by weight or more, even more preferably 70% by weight or more, and particularly preferably 90% by weight or more, out of 100% by weight of the metal. When the tin content in the solder is above the lower limit mentioned above, the conductivity reliability is further improved.

[0121] The nickel, copper, and tin content can be measured using a high-frequency inductively coupled plasma atomic emission spectrometer (Horiba, Ltd. "ICP-AES") or an X-ray fluorescence analyzer (Shimadzu Corporation "EDX-800HS"), etc.

[0122] By using the solder described above, the solder melts and joins to the electrodes, creating electrical conductivity between them. For example, because surface contact rather than point contact is more likely to occur between the solder and the electrodes, the connection resistance is reduced. Furthermore, the use of solder increases the bonding strength between the solder and the electrodes, making delamination between the solder and electrodes less likely and thus more effectively improving conductivity reliability.

[0123] The low-melting-point metal constituting the solder described above is not particularly limited. The low-melting-point metal is preferably tin or an alloy containing tin. Examples of such alloys include tin-silver alloys, tin-copper alloys, tin-silver-copper alloys, tin-bismuth alloys, tin-zinc alloys, and tin-indium alloys. Due to their excellent wettability to electrodes, the low-melting-point metal is preferably tin, tin-silver alloys, tin-silver-copper alloys, tin-bismuth alloys, and tin-indium alloys, and more preferably tin-bismuth alloys and tin-indium alloys.

[0124] The solder described above is preferably a filler material with a liquidus temperature of 450°C or lower, based on JIS Z3001: Welding Terminology. Examples of the solder's composition include metal compositions containing zinc, gold, silver, lead, copper, tin, bismuth, indium, etc. The solder is preferably a low-melting-point, lead-free tin-indium system (117°C eutectic) or tin-bismuth system (139°C eutectic). In other words, the solder is preferably lead-free and contains either tin and indium, or tin and bismuth.

[0125] To further enhance the bonding strength, the solder may contain metals such as nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese, chromium, molybdenum, and palladium. Furthermore, from the viewpoint of further enhancing the bonding strength, it is preferable that the solder contains nickel, copper, antimony, aluminum, or zinc. From the viewpoint of further enhancing the bonding strength, the content of these metals for enhancing bonding strength is preferably 0.0001% by weight or more, and preferably 1% by weight or less, per 100% by weight of the solder.

[0126] The conductive portion may be formed from a single layer. The conductive portion may be formed from multiple layers. That is, the conductive portion may have a laminated structure of two or more layers. From the viewpoint of more effectively improving conductivity reliability, it is preferable that the conductive portion has a laminated structure of two or more layers.

[0127] The method for forming the conductive portion on the surface of the above-mentioned substrate particles is not particularly limited. Examples of methods for forming the conductive portion include the following: electroless plating; electroplating; physical impact; mechanochemical reaction; physical vapor deposition or physical adsorption; and coating the surface of the substrate particles with metal powder or a paste containing metal powder and a binder. The method for forming the conductive portion is preferably electroless plating, electroplating, or physical impact. Examples of physical vapor deposition include vacuum deposition, ion plating, and ion sputtering. As for the physical impact method, a theta composer (manufactured by Tokuju Kogyo Co., Ltd.) can be used.

[0128] The thickness of the conductive portion is preferably 10 nm or more, more preferably 500 nm or more, preferably 10 μm or less, more preferably 5 μm or less, even more preferably 1 μm or less, and particularly preferably 800 nm or less. The thickness of the conductive portion refers to the total thickness of the conductive portion when the conductive portion has a laminated structure of two or more layers. When the thickness of the conductive portion is above the lower limit and below the upper limit, the occurrence of aggregation between conductive particles can be suppressed even more effectively. Furthermore, when the thickness of the conductive portion is above the lower limit and below the upper limit, sufficient conductivity can be obtained and the hardening of the conductive particles can be prevented.

[0129] When the conductive portion has a laminated structure of two or more layers, the thickness of the outermost conductive layer is preferably 10 nm or more, more preferably 500 nm or more, preferably 10 μm or less, more preferably 5 μm or less, even more preferably 1 μm or less, and particularly preferably 800 nm or less. When the thickness of the outermost conductive layer is above the lower limit and below the upper limit, the occurrence of aggregation between conductive particles can be suppressed even more effectively.

[0130] The thickness of the conductive portion can be measured, for example, by observing the cross-section of the conductive particle using a transmission electron microscope (TEM). Preferably, the thickness of the conductive portion is the thickness of the part of any conductive particle where the conductive portion is thickest. Preferably, the thickness of the conductive portion can be determined by calculating the average value of the conductive portion thickness of 10 arbitrary conductive particles.

[0131] Solder particles: In the conductive particles described above, the conductive portion has a solder portion. The conductive portion has a solder portion formed by solder.

[0132] From the viewpoint of more effectively suppressing the aggregation of conductive particles, it is preferable that the solder portion is made of solder granules. In the case of conductive particles, it is preferable that the conductive portion has solder granules. For example, it is preferable that the second conductive portion (solder portion) 3B in Figure 1, the second conductive portion (solder portion) 12C in Figure 2, the second conductive portion (solder portion) 22B in Figure 3, and the second conductive portion (solder portion) 32B in Figure 4 are made of solder granules. Also, it is preferable that the second conductive portion (solder portion) 42B in Figure 5, the second conductive portion (solder portion) 52C in Figure 6, the second conductive portion (solder portion) 62B in Figure 7, and the second conductive portion (solder portion) 72C in Figure 8 are made of solder granules.

[0133] The solder particles described above are different from the protrusions described later. The solder particles can form metallic bonds with the joint portion, such as an electrode. The solder particles are used to join electrodes and the like. Because the conductive part has the solder particles, the solder particles can easily form metallic bonds with the joint portion, such as an electrode, so it is not necessary to melt the entire conductive part during joining. As a result, the reliability of conductivity between electrodes can be improved even when the thickness of the conductive part is relatively thin. Furthermore, since it is not necessary to increase the thickness of the conductive part, aggregation of conductive particles can be effectively suppressed.

[0134] Furthermore, because the solder particles are relatively small, their outer surfaces are less susceptible to oxidation, thus suppressing the effects of oxide film. As a result, the solder particles can more easily form metallic bonds with the joint portion, such as electrodes. On the other hand, if the conductive particles are not solder particles but a solder layer coated with solder, the outer surface of the solder layer is relatively easily oxidized, making it difficult to suppress the effects of oxide film. As a result, the solder layer cannot easily form metallic bonds with the joint portion, such as electrodes, requiring measures such as increasing the thickness of the solder layer, making it difficult to suppress the aggregation of conductive particles.

[0135] The shape of the solder particles described above is not particularly limited. The shape of the solder particles is preferably needle-shaped or part of a sphere. The needle-shaped shape is preferably pyramidal, conical, or paraboloid of revolution, more preferably conical or paraboloid of revolution, and even more preferably conical. The shape of the solder particles may be pyramidal, conical, or paraboloid of revolution.

[0136] The material of the solder particles described above is not particularly limited. Preferably, the solder particles are composed of metal. Preferably, the material of the solder particles contains a tin-containing alloy, pure tin, or tin in a state different from both a tin-containing alloy and pure tin. The material of the solder particles may contain a tin-containing alloy or pure tin. The material of the solder particles may be a tin-containing alloy or pure tin. The material of the solder particles may contain tin in a state different from both a tin-containing alloy and pure tin. From the viewpoint of more effectively suppressing the occurrence of aggregation between conductive particles, it is more preferable that the material of the solder particles be pure tin. Note that the material of the solder particles being pure tin means that the tin content is 90% by weight or more in 100% by weight of the solder particle material. The tin content in 100% by weight of the solder particle material may be less than 90% by weight, 80% by weight or less, 75% by weight or less, or 70% by weight or less.

[0137] In 100% by weight of tin-containing solder particles, the tin content is preferably 20% by weight or more, more preferably 40% by weight or more, even more preferably 90% by weight or more, preferably 99.5% by weight or less, and more preferably 99% by weight or less. When the tin content is above the lower limit and below the upper limit, the occurrence of aggregation between conductive particles can be suppressed more effectively. When the tin content is above the lower limit and below the upper limit, the solder particles can form metallic bonds more easily with the joint portion such as an electrode.

[0138] The height of the solder particles is preferably 10 nm or more, more preferably 250 nm or more, even more preferably 350 nm or more, particularly preferably 500 nm or more, preferably 10 μm or less, and more preferably 5 μm or less. When the height of the solder particles is above the lower limit and below the upper limit, the aggregation of conductive particles can be suppressed more effectively. When the height of the solder particles is above the lower limit and below the upper limit, the solder particles can form metallic bonds more easily with the joint portion such as an electrode, resulting in better conductivity than physical contact and further increasing the joint strength.

[0139] The solder particle height described above represents the distance from the outer surface of the first conductive part to the tip of the solder particle (solder part), assuming there is no solder particle (solder part), on the line (dashed line L1 shown in Figure 1) connecting the center of the conductive particle and the tip of the solder particle (solder part). That is, in Figure 1, it represents the distance from the intersection point L2 of the dashed line L1 and the outer surface of the first conductive part to the tip of the solder particle (solder part). Preferably, the solder particle height described above is the average of the solder particle heights on a single conductive particle. Preferably, the solder particle height described above is the average of the solder particle heights at five locations on the conductive particle.

[0140] The height of the solder particles mentioned above can be measured, for example, as follows:

[0141] A resin body for conductive particle inspection is prepared by adding conductive particles to Kulzer's "Technovit 4000" so that the conductive particle content is 30% by weight, and then dispersing them. A cross-section of the conductive particles is cut out using an ion milling device (Hitachi High-Technologies Corporation's "IM4000") so as to pass through the vicinity of the center of the conductive particles dispersed in the inspection resin body. Then, a field emission scanning electron microscope (FE-SEM) is used to randomly select conductive particles and observe the solder particles on the conductive particles. The height of the solder particles at five locations on the conductive particle is measured, and these are arithmetic mean to obtain the height of the solder particles.

[0142] The aspect ratio of the solder particles is preferably 0.05 or higher, more preferably 0.47 or higher, even more preferably 0.5 or higher, preferably 5 or lower, and more preferably 3 or lower. When the aspect ratio of the solder particles is above the lower limit and below the upper limit, the occurrence of aggregation between conductive particles can be suppressed even more effectively. When the aspect ratio of the solder particles is above the lower limit and below the upper limit, the solder particles can form metallic bonds with the bonding portion such as an electrode even more easily, and a sufficient area between the solder particles and the bonding portion such as an electrode can be secured.

[0143] The aspect ratio of the solder grain described above is the ratio of the height of the solder grain to the width of the solder grain (height of solder grain / width of solder grain), and is calculated from the height and width of the solder grain. The height of the solder grain, as described above, indicates the distance from the outer surface of the first conductive part to the tip of the solder grain (solder part), assuming there is no solder grain (solder part), on the line connecting the center of the conductive particle and the tip of the solder grain (solder part) (dashed line L1 shown in Figure 1). The width of the solder grain indicates the maximum distance of the straight line connecting two points on the outer circumference of the solder grain (solder part) in a direction perpendicular to the line connecting the center of the conductive particle and the tip of the solder grain (solder part). Preferably, the width of the solder grain described above is the average width of the solder grains in one conductive particle. Preferably, the width of the solder grain described above is the average value of the widths of five solder grains in the conductive particle.

[0144] The width of the solder particles mentioned above can be measured, for example, as follows:

[0145] A resin body for conductive particle inspection is prepared by adding conductive particles to Kulzer's "Technovit 4000" so that the conductive particle content is 30% by weight, and then dispersing them. A cross-section of the conductive particles is cut out using an ion milling device (Hitachi High-Technologies Corporation's "IM4000") so as to pass through the vicinity of the center of the conductive particles dispersed in the inspection resin body. Then, a field emission scanning electron microscope (FE-SEM) is used to randomly select conductive particles and observe the solder particles on the conductive particles. The width of the solder particles at five locations on the conductive particle is measured, and these measurements are arithmetically averaged to obtain the width of the solder particle.

[0146] The width of the solder particles is preferably 250 nm or more, more preferably 500 nm or more, even more preferably 650 nm or more, preferably 3000 nm or less, more preferably 1700 nm or less, and even more preferably 1500 nm or less. When the width of the solder particles is above the lower limit and below the upper limit, the occurrence of aggregation between conductive particles can be suppressed even more effectively. When the width of the solder particles is above the lower limit and below the upper limit, the solder particles can form metallic bonds with the joint portion such as an electrode even more easily, resulting in conductivity characteristics superior to physical contact and further increasing the joint strength.

[0147] The method for forming the solder particles described above is not particularly limited. Examples of methods for forming the solder particles include electroless plating and electroplating. In this invention, plating is considered to be the case not only when the formed shape is a film, but also when it is granular.

[0148] In the above-mentioned conductive particles, it is preferable that a metal colloid precipitate or a metal film is present on the outer surface of the solder grain. In the above-mentioned conductive particles, a metal colloid precipitate may be present on the outer surface of the solder grain, or a metal film may be present.

[0149] When the conductive particles satisfy the above-described preferred embodiment, the melting point or metal diffusion temperature of the solder particles (solder portion) and the conductive portion can be changed, making the temperature more suitable for the joint portion such as an electrode. As a result, the solder particles can form a metallic bond with the joint portion such as an electrode more easily.

[0150] Of the total surface area of ​​the solder particles, the area of ​​the portion containing the metal colloid precipitate or metal film (coverage rate of the metal colloid precipitate or metal film) is preferably 5% or more, more preferably 40% or more, preferably 100% or less, and more preferably 95% or less. When the coverage rate (coverage rate of the metal colloid precipitate or metal film) is above the lower limit and below the upper limit, the melting point or metal diffusion temperature of the solder particles (solder portion) and the conductive portion can be changed, making it possible to achieve a temperature more suitable for the joint portion such as an electrode. As a result, the solder particles can form a metallic bond with the joint portion such as an electrode more easily.

[0151] The area of ​​the portion of the solder particle containing the metal colloid precipitate or metal film (coverage rate of the metal colloid precipitate or metal film) can be calculated by performing elemental mapping on the cross-section of the solder particle in the conductive particle using SEM-EDX analysis and then performing image analysis.

[0152] The metal species of the metal colloid precipitate or the metal film is preferably nickel, cobalt, lead, gold, zinc, palladium, copper, silver, bismuth, or indium, and more preferably copper, silver, bismuth, or indium. When the metal species of the metal colloid precipitate or the metal film satisfies the above preferred embodiment, the melting point or metal diffusion temperature of the solder particles (solder portion) and the conductive portion can be changed, making the temperature more suitable for the joint portion such as an electrode. As a result, the solder particles can form metallic bonds with the joint portion such as an electrode more easily.

[0153] The metal colloid used to obtain the above-mentioned metal colloid precipitate is preferably nickel colloid, cobalt colloid, lead colloid, gold colloid, zinc colloid, palladium colloid, copper colloid, silver colloid, bismuth colloid, or indium colloid. More preferably, the metal colloid used to obtain the above-mentioned metal colloid precipitate is copper colloid, silver colloid, bismuth colloid, or indium colloid. The metal film used is preferably a nickel thin film, cobalt thin film, lead thin film, gold thin film, zinc thin film, palladium thin film, copper thin film, silver thin film, bismuth thin film, or indium thin film. More preferably, the metal film used is a copper thin film, silver thin film, bismuth thin film, or indium thin film. When the above-mentioned metal colloid precipitate or metal film satisfies the above-mentioned preferred embodiments, the melting point or metal diffusion temperature of the solder particles (solder portion) and the conductive portion can be changed, and the temperature can be made more suitable for the joint portion such as an electrode. As a result, the solder particles can form metallic bonds with the joint portion such as an electrode more easily.

[0154] The above-mentioned metal colloid precipitate is preferably metal fine particles. The particle size of the metal fine particles is preferably 1 nm or more, more preferably 10 nm or more, preferably 1 μm or less, and more preferably 0.5 μm or less. The thickness of the metal film is preferably 1 nm or more, more preferably 10 nm or more, preferably 1 μm or less, and more preferably 0.5 μm or less. When the particle size of the metal fine particles or the thickness of the metal film satisfies the above-mentioned preferred embodiments, the melting point or metal diffusion temperature of the solder particles (solder portion) and the conductive portion can be changed, making it possible to set a temperature more suitable for the joint portion such as an electrode. As a result, the solder particles can form a metallic bond with the joint portion such as an electrode more easily.

[0155] The particle size of the metal colloid precipitate or the thickness of the metal film can be measured, for example, as follows.

[0156] A resin body for conductive particle inspection is prepared by adding conductive particles to Kulzer's "Technovit 4000" so that the conductive particle content is 30% by weight, and then dispersing them. A cross-section of the conductive particles is cut out using an ion milling device (Hitachi High-Technologies Corporation's "IM4000") so as to pass through the vicinity of the center of the conductive particles dispersed in the inspection resin body. Then, conductive particles are randomly selected using a field emission scanning electron microscope (FE-SEM), and the metal colloidal precipitates or metal films on the solder particles are observed. The particle size of the metal colloidal precipitates or the thickness of the metal film are measured at five locations on the solder particles, and these are arithmetic mean to obtain the particle size of the metal colloidal precipitates or the thickness of the metal film.

[0157] The method for forming a metal colloid deposit or metal film on the outer surface of the solder particles is not particularly limited. Examples of methods for forming a metal colloid deposit or metal film on the outer surface of the solder particles include electroless plating, electroplating, physical impact, and physical deposition or physical adsorption.

[0158] (core substance) The conductive particles preferably have protrusions on the outer surface of the conductive portion. The conductive particles preferably have protrusions on the conductive surface. The protrusions preferably number in number. An oxide film is often formed on the surface of the electrode that comes into contact with the conductive particles. When conductive particles with protrusions on the surface of the conductive portion are used, the oxide film can be effectively removed by the protrusions by pressing the conductive particles and the electrode together. As a result, the electrode and the conductive portion make contact more reliably, the contact area between the conductive particles and the electrode can be sufficiently increased, and the connection resistance can be reduced more effectively. Furthermore, when conductive particles are dispersed in a binder and used as a conductive material, the protrusions of the conductive particles can more effectively remove the binder between the conductive particles and the electrode. As a result, the contact area between the conductive particles and the electrode can be sufficiently increased, and the connection resistance can be reduced more effectively.

[0159] The above-mentioned protrusions are different from the solder particles described above. These protrusions are used to remove oxide films present on the surface of conductive particles and electrodes, or to remove binders between conductive particles and electrodes.

[0160] 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 part is formed by electroless plating, and a method in which a conductive part is formed on the surface of a base particle by electroless plating, then a core material is attached, and then a conductive part is formed by electroless plating. Furthermore, it is not necessary to use the above-mentioned core material to form the above-mentioned protrusions.

[0161] Other methods for forming the above-mentioned protrusions include adding a core material during the process of forming the conductive portion on the surface of the substrate particles. Alternatively, to form the protrusions, a method may be used in which a conductive portion is formed on the substrate particles by electroless plating without using the above-mentioned core material, then plating is deposited in a protruding manner on the surface of the conductive portion, and then the conductive portion is formed by further electroless plating.

[0162] Methods for attaching a core material to the surface of base particles include adding the core material to a dispersion of base particles and accumulating and attaching the core material to the surface of the base particles by van der Waals forces, and adding the core material to a container containing base particles and attaching the core material to the surface of the base particles by mechanical action such as rotating the container. From the viewpoint of controlling the amount of core material to be attached, the method of attaching the core material to the surface of base particles is preferably one in which the core material is accumulated and attached to the surface of the base particles in a dispersion.

[0163] The materials constituting the core material mentioned above include conductive materials and non-conductive materials. Examples of conductive materials include metals, metal oxides, conductive nonmetals such as graphite, and conductive polymers. Examples of conductive polymers include polyacetylene. Examples of non-conductive materials include silica, alumina, and zirconia. From the viewpoint of more effectively eliminating oxide films, it is preferable that the core material be hard. From the viewpoint of more effectively lowering the connection resistance between electrodes, it is preferable that the core material be a metal.

[0164] The above metals are not particularly limited. Examples of the above metals include gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, as well as alloys composed of two or more metals such as tin-lead alloys, tin-copper alloys, tin-silver alloys, tin-lead-silver alloys, and tungsten carbide. From the viewpoint of more effectively lowering the connection resistance between electrodes, the above metals are preferably nickel, copper, silver, or gold. The above metals may be the same as or different from the metals constituting the conductive part (conductive layer).

[0165] The shape of the core material is not particularly limited. The core material is preferably in the form of a lump. Examples of core material include particulate lumps, aggregates formed by the aggregation of multiple fine particles, and irregularly shaped lumps.

[0166] The particle size of the core material is preferably 0.001 μm or larger, more preferably 0.05 μm or larger, more preferably 0.9 μm or smaller, and more preferably 0.2 μm or smaller. When the particle size of the core material is above the lower limit and below the upper limit, the connection resistance between electrodes can be reduced even more effectively.

[0167] The particle diameter of the core material described above is preferably the average particle diameter, and more preferably the number-average particle diameter. The particle diameter of the core material can be determined by observing 50 arbitrary core materials with an electron microscope or optical microscope and calculating the average particle diameter of each core material, or by using a particle size distribution analyzer. In observation with an electron microscope or optical microscope, the particle diameter of one core material is determined as the particle diameter at the equivalent diameter of a circle. In observation with an electron microscope or optical microscope, the average particle diameter at the equivalent diameter of a circle of any 50 core materials is approximately equal to the average particle diameter at the equivalent diameter of a sphere. In a particle size distribution analyzer, the particle diameter of one core material is determined as the particle diameter at the equivalent diameter of a sphere. It is preferable to calculate the average particle diameter of the core material described above using a particle size distribution analyzer.

[0168] The number of protrusions per conductive particle is preferably three or more, more preferably five or more. There is no particular upper limit to the number of protrusions. The upper limit of the number of protrusions can be appropriately selected considering the particle size of the conductive particles, etc. If the number of protrusions is above the lower limit, the connection resistance between electrodes can be lowered even more effectively.

[0169] The number of protrusions can be calculated by observing any conductive particle with an electron microscope or optical microscope. Preferably, the number of protrusions is determined by observing 50 arbitrary conductive particles with an electron microscope or optical microscope and calculating the average number of protrusions on each conductive particle.

[0170] The height of the above-mentioned protrusion is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, and more preferably 0.2 μm or less. When the height of the above-mentioned protrusion is above the lower limit and below the upper limit, the connection resistance between electrodes can be reduced even more effectively.

[0171] The height of the above-mentioned protrusions can be calculated by observing the protrusions on any conductive particle using an electron microscope or an optical microscope. Preferably, the height of the protrusions on a single conductive particle is calculated by taking the average height of all the protrusions on that conductive particle as the height of the protrusions on that single conductive particle. Preferably, the height of the protrusions can be determined by calculating the average height of the protrusions on 50 arbitrary conductive particles.

[0172] (Insulating material) Preferably, the conductive particles have an insulating material disposed on the outer surface of the conductive portion. In this case, using the conductive particles for connecting electrodes can more effectively prevent short circuits between adjacent electrodes. Specifically, when multiple conductive particles come into contact, an insulating material is present between the multiple electrodes, thus preventing short circuits between adjacent electrodes in the lateral direction rather than between electrodes in the vertical direction. Furthermore, when connecting electrodes, the insulating material between the conductive particles and the electrodes can be easily removed by applying pressure to the conductive particles with the two electrodes. Moreover, if the conductive particles have protrusions on the outer surface of the conductive portion, the insulating material between the conductive portion and the electrodes can be removed even more easily.

[0173] Since the insulating material can be more easily removed when the electrodes are crimped together, it is preferable that the insulating material be insulating particles.

[0174] Examples of materials for the insulating substance include the organic materials mentioned above, the inorganic materials mentioned above, and the inorganic materials listed above as materials for the base particles. Preferably, the material for the insulating substance is the organic material mentioned above.

[0175] Other materials that can be used as insulating materials include polyolefin compounds, (meth)acrylate polymers, (meth)acrylate copolymers, block polymers, thermoplastic resins, crosslinked thermoplastic resins, thermosetting resins, and water-soluble resins. The insulating material may be used individually or in combination of two or more types.

[0176] Examples of the polyolefin compounds mentioned above include polyethylene, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid ester copolymer. Examples of the (meth)acrylate polymers mentioned above include polymethyl (meth)acrylate, polydodecyl (meth)acrylate, and polystearyl (meth)acrylate. Examples of the block polymers mentioned above include polystyrene, styrene-acrylic acid ester copolymer, SB-type styrene-butadiene block copolymer, and SBS-type styrene-butadiene block copolymer, as well as hydrogenated versions thereof. Examples of the thermoplastic resins mentioned above include vinyl polymers and vinyl copolymers. Examples of the thermosetting resins mentioned above include epoxy resins, phenolic resins, and melamine resins. Examples of crosslinked products for the thermoplastic resins mentioned above include polyethylene glycol methacrylate, alkoxylated trimethylolpropane methacrylate, and alkoxylated pentaerythritol methacrylate. Examples of the water-soluble resins mentioned above include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide, and methylcellulose. In addition, a chain transfer agent may be used to adjust the degree of polymerization. Examples of chain transfer agents include thiols and carbon tetrachloride.

[0177] Methods for distributing the insulating material on the surface of the conductive part include chemical methods and physical or mechanical methods. Chemical methods include interfacial polymerization, suspension polymerization in the presence of particles, and emulsion polymerization. Physical or mechanical methods include spray drying, hybridization, electrostatic deposition, spraying, dipping, and vacuum deposition. From the viewpoint of more effectively improving insulation reliability and conductivity reliability when electrodes are electrically connected, it is preferable that the method for distributing the insulating material on the surface of the conductive part is a physical method.

[0178] The outer surface of the conductive part and the outer surface of the insulating material may each be coated with a compound having a reactive functional group. The outer surface of the conductive part and the outer surface of the insulating material do not have to be directly chemically bonded, but may be indirectly chemically bonded by a compound having a reactive functional group. After introducing carboxyl groups to the outer surface of the conductive part, the carboxyl groups may be chemically bonded to the functional groups on the outer surface of the insulating material via a polymer electrolyte such as polyethyleneimine.

[0179] When the insulating material is an insulating particle, the particle size of the insulating particle can be appropriately selected depending on the particle size of the conductive particle and the application of the conductive particle. The particle size of the insulating particle is preferably 10 nm or more, more preferably 100 nm or more, even more preferably 300 nm or more, particularly preferably 500 nm or more, preferably 4000 nm or less, more preferably 2000 nm or less, even more preferably 1500 nm or less, particularly preferably 1000 nm or less. If the particle size of the insulating particle is above the lower limit, it becomes difficult for the conductive parts of multiple conductive particles to come into contact with each other when the conductive particles are dispersed in the binder. If the particle size of the insulating particle is below the upper limit, it becomes unnecessary to increase the pressure too much to remove the insulating particle between the electrode and the conductive particle when connecting electrodes, and it also becomes unnecessary to heat to a high temperature.

[0180] The particle diameter of the insulating particles described above is preferably the average particle diameter, and more preferably the number-average particle diameter. The particle diameter of the insulating particles can be determined by observing 50 arbitrary insulating particles with an electron microscope or optical microscope and calculating the average particle diameter of each insulating particle, or by using a particle size distribution analyzer. In observation with an electron microscope or optical microscope, the particle diameter of a single insulating particle is determined as the particle diameter at the equivalent diameter of a circle. In observation with an electron microscope or optical microscope, the average particle diameter at the equivalent diameter of a circle of any 50 insulating particles is approximately equal to the average particle diameter at the equivalent diameter of a sphere. In a particle size distribution analyzer, the particle diameter of a single insulating particle is determined as the particle diameter at the equivalent diameter of a sphere. It is preferable to calculate the average particle diameter of the insulating particles described above using a particle size distribution analyzer. When measuring the particle diameter of the insulating particles in the conductive particles described above, it can be measured, for example, as follows.

[0181] Conductive particles are added to Kulzer's "Technovit 4000" to a content of 30% by weight, and dispersed to create an embedded resin body for conductive particle inspection. An ion milling device (Hitachi High-Technologies Corporation's "IM4000") is used to cut a cross-section of the conductive particles, passing through the vicinity of the center of the dispersed conductive particles in the embedded resin body. Then, using a field emission scanning electron microscope (FE-SEM), 50 conductive particles are randomly selected, and the insulating particles of each conductive particle are observed. The particle diameter of the insulating particles in each conductive particle is measured, and these are arithmetic mean to obtain the particle diameter of the insulating particles.

[0182] (Conductive materials) The conductive material according to the present invention comprises conductive particles and a binder. The conductive particles are the conductive particles described above. The conductive particles are preferably dispersed in the binder and used as a conductive material. The conductive material is preferably an anisotropic conductive material. The conductive material is preferably used for electrical connections between electrodes. The conductive material is preferably a conductive material for circuit connections. In the conductive material, since the conductive particles described above are used, the connection resistance between electrodes can be more effectively reduced, and the occurrence of aggregation between conductive particles can be more effectively suppressed. In the conductive material, since the conductive particles described above are used, when electrodes are electrically connected, the conductivity reliability can be more effectively increased, and the insulation reliability can be more effectively increased.

[0183] The above-mentioned binder is not particularly limited. Known insulating resins and solvents can be used as the binder. The binder 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.

[0184] Examples of the binders mentioned above include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, elastomers, and solvents. Only one type of binder may be used, or two or more types may be used in combination.

[0185] Examples of vinyl resins include vinyl acetate resin, acrylic resin, and styrene resin. Examples of thermoplastic resins include polyolefin resin, ethylene-vinyl acetate copolymer, and polyamide resin. Examples of curable resins include epoxy resin, urethane resin, polyimide resin, and unsaturated polyester resin. The curable resin may be a room-temperature curing resin, a thermosetting resin, a photocuring resin, or a moisture-curing resin. The curable resin may be used in combination with a curing agent. Examples of thermoplastic block copolymers include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, and hydrogenated styrene-isoprene-styrene block copolymer. Examples of elastomers include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

[0186] Examples of the above solvents include water and organic solvents. Organic solvents are preferred because they can be easily removed. Examples of the above organic solvents include alcohol compounds such as ethanol, ketone compounds such as acetone, methyl ethyl ketone, and cyclohexanone, aromatic hydrocarbon compounds such as toluene, xylene, and tetramethylbenzene, glycol ether compounds such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol monomethyl ether, ester compounds such as ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propylene carbonate, aliphatic hydrocarbon compounds such as octane and decane, and petroleum-based solvents such as petroleum ether and naphtha.

[0187] In addition to the conductive particles and binder, the conductive material may also contain various additives such as fillers, bulking agents, softeners, plasticizers, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents, and flame retardants.

[0188] The method for dispersing the conductive particles in the binder is not particularly limited and can be any conventionally known dispersion method. Examples of methods for dispersing the conductive particles in the binder include the following: A method in which the conductive particles are added to the binder and then mixed and dispersed using a planetary mixer or the like. A method in which the conductive particles are uniformly dispersed in water or an organic solvent using a homogenizer or the like, then added to the binder and mixed and dispersed using a planetary mixer or the like. A method in which the binder is diluted with water or an organic solvent, then the conductive particles are added and mixed and dispersed using a planetary mixer or the like.

[0189] The viscosity (η25) of the conductive material at 25°C is preferably 30 Pa·s or more, more preferably 50 Pa·s or more, preferably 400 Pa·s or less, and more preferably 300 Pa·s or less. When the viscosity of the conductive material at 25°C is above the lower limit and below the upper limit, the connection resistance between electrodes can be more effectively reduced, and the connection reliability between electrodes can be more effectively improved. The viscosity (η25) can be appropriately adjusted depending on the type and amount of the components used.

[0190] The viscosity (η25) described above can be measured, for example, using an E-type viscometer (TVE22L manufactured by Toki Sangyo Co., Ltd.) under conditions of 25°C and 5 rpm.

[0191] The conductive material according to the present invention 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 without conductive particles may be laminated onto a conductive film containing conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

[0192] In 100% by weight of the conductive material, the binder content 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, preferably 99.99% by weight or less, and more preferably 99.9% by weight or less. When the binder content is above the lower limit and below the upper limit, the connection resistance between electrodes can be more effectively reduced, and the connection reliability between electrodes can be more effectively improved.

[0193] In 100% by weight of the above conductive material, the content of the above conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 80% by weight or less, more preferably 60% by weight 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 above conductive particles is above the lower limit and below the upper limit, the connection resistance between electrodes can be more effectively reduced, and the connection reliability between electrodes can be more effectively improved.

[0194] Flux: The conductive material may contain flux. Using flux can more effectively improve conductivity reliability when electrodes are electrically connected. The flux is not particularly limited. Flux commonly used in soldering and the like can be used.

[0195] Examples of the fluxes mentioned above include zinc chloride, mixtures of zinc chloride and inorganic halides, mixtures of zinc chloride and inorganic acids, molten salts, phosphoric acid, derivatives of phosphoric acid, organic halides, hydrazine, amine compounds, organic acids, and rosin. Only one of these fluxes may be used, or two or more may be used in combination.

[0196] Examples of the molten salt include ammonium chloride. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamic acid, and glutaric acid. Examples of the rosin include activated rosin and inactivated rosin. The flux is preferably an organic acid having two or more carboxyl groups, or rosin. The flux may be an organic acid having two or more carboxyl groups, or rosin. The use of an organic acid or rosin having two or more carboxyl groups further improves the conductivity reliability between electrodes.

[0197] Examples of organic acids having two or more carboxyl groups include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

[0198] Examples of the above-mentioned amine compounds include cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, imidazole, benzimidazole, phenylimidazole, carboxybenzimidazole, benzotriazole, and carboxybenzotriazole.

[0199] The above-mentioned rosin is a rosin whose main component is abietic acid. Examples of such rosins include abietic acid and acrylic-modified rosin. The flux is preferably a rosin, and more preferably abietic acid. The use of this preferred flux further enhances the conductivity reliability between electrodes.

[0200] The activation temperature (melting point) of the flux is preferably 50°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, preferably 200°C or lower, more preferably 190°C or lower, even more preferably 160°C or lower, even more preferably 150°C or lower, and even more preferably 140°C or lower. When the activation temperature of the flux is above the lower limit and below the upper limit, the flux effect is exerted more effectively, and the conductivity reliability between electrodes can be increased more effectively. The activation temperature (melting point) of the flux is preferably 80°C or higher and 190°C or lower. The activation temperature (melting point) of the flux is particularly preferably 80°C or higher and 140°C or lower.

[0201] Examples of fluxes whose active temperature (melting point) is between 80°C and 190°C include dicarboxylic acids such as succinic acid (melting point 186°C), glutaric acid (melting point 96°C), adipic acid (melting point 152°C), pimelic acid (melting point 104°C), and suberic acid (melting point 142°C), as well as benzoic acid (melting point 122°C) and malic acid (melting point 130°C).

[0202] Furthermore, it is preferable that the boiling point of the flux is 200°C or lower.

[0203] The flux may be dispersed in the conductive material or attached to the surface of the conductive particles. From the viewpoint of more effectively improving conductivity reliability when electrodes are electrically connected, it is preferable that the flux is attached to the surface of the conductive particles.

[0204] From the viewpoint of more effectively improving conductivity reliability, the flux is preferably a salt of an acid compound and a base compound.

[0205] The above acid compound is preferably an organic compound having a carboxyl group. Examples of the above acid compound include aliphatic carboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, citric acid, and malic acid; cyclic aliphatic carboxylic acids such as cyclohexyl carboxylic acid and 1,4-cyclohexyldicarboxylic acid; and aromatic carboxylic acids such as isophthalic acid, terephthalic acid, trimellitic acid, and ethylenediaminetetraacetic acid. From the viewpoint of further effectively improving conductivity reliability, the above acid compound is preferably glutaric acid, cyclohexyl carboxylic acid, or adipic acid.

[0206] The above base compound is preferably an organic compound having an amino group. Examples of the above base compound include diethanolamine, triethanolamine, methyldiethanolamine, ethyldiethanolamine, cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, 2-methylbenzylamine, 3-methylbenzylamine, 4-tert-butylbenzylamine, N-methylbenzylamine, N-ethylbenzylamine, N-phenylbenzylamine, N-tert-butylbenzylamine, N-isopropylbenzylamine, N,N-dimethylbenzylamine, imidazole compounds, and triazole compounds. From the viewpoint of further effectively improving conductivity reliability, the above base compound is preferably benzylamine.

[0207] The flux content in 100% by weight of the conductive material is preferably 0.5% by weight or more, preferably 30% by weight or less, and more preferably 25% by weight or less. When the flux content is above the lower limit and below the upper limit, an oxide film is less likely to form on the electrode surface, and the oxide film formed on the electrode surface can be removed more effectively.

[0208] (Connection structure) The connection structure according to the present invention comprises 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 connecting portion connecting the first connection target member and the second connection target member. In the connection structure according to the present invention, the connecting portion is formed of conductive particles or of a conductive material containing the conductive particles and a binder. In the connection structure according to the present invention, the conductive particles are the conductive particles described above. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by the conductive particles.

[0209] Figure 9 is a schematic front cross-sectional view showing a connection structure using conductive particles according to a fourth embodiment of the present invention.

[0210] The connecting structure 81 shown in Figure 9 comprises a first member to be connected 82, a second member to be connected 83, and a connecting portion 84 that connects the first member to be connected 82 and the second member to be connected 83. The connecting portion 84 is formed of a conductive material containing conductive particles 21. Note that in Figure 9, the conductive particles 21 are shown schematically for illustrative purposes.

[0211] The first connection target member 82 has a plurality of first electrodes 82a on its surface (upper surface). The second connection target member 83 has a plurality of second electrodes 83a on its surface (lower surface). The first electrodes 82a and the second electrodes 83a are electrically connected by one or more conductive particles 21. Therefore, the first connection target member 82 and the second connection target member 83 are electrically connected by the conductive particles 21.

[0212] The method for manufacturing the above-mentioned connection structure is not particularly limited. An example of a method for manufacturing the connection structure is to place the conductive material between the first connection target member and the second connection target member to obtain a laminate, and then heat and pressurize the laminate. Heating and pressurizing melt the conductive portion (solder portion) of the conductive particles 21, and the electrodes are electrically connected by the conductive particles 21. Furthermore, if the binder contains a thermosetting compound, the thermosetting compound heats up, and the heat-cured material forms the connection portion that connects the first connection target member and the second connection target member. The pressure for the pressurization is 9.8 × 10⁻⁶. 4 Pa~4.9×10 6 The pressure is Pa. The heating temperature is 120°C to 220°C.

[0213] Figure 10 is a schematic, enlarged front cross-sectional view showing the connection portion between the conductive particles and the electrode in the connection structure shown in Figure 9.

[0214] As shown in Figure 10, in the connecting structure 81, when the laminate is heated and pressurized, the second conductive portion (solder portion) 22B of the conductive particle 21 melts, and then the molten second conductive portion (solder portion) 22Ba comes into sufficient contact with the first electrode 82a and the second electrode 83a. In other words, by using conductive particles 21 whose surface layer is a solder portion, the contact area between the conductive particles 21 and the first electrode 82a and the second electrode 83a is increased compared to when conductive particles whose surface layer of the conductive layer is a metal such as nickel, gold, or copper are used. As a result, the conductivity reliability of the connecting structure 81 is increased.

[0215] The first and second connection targets described above are not particularly limited. Specifically, the first and second connection targets include electronic components such as semiconductor chips, semiconductor packages, LED chips, LED packages, capacitors, and diodes, as well as electronic components such as resin films, printed circuit boards, flexible printed circuit boards, flexible flat cables, rigid-flexible circuit boards, glass epoxy circuit boards, and glass circuit boards. It is preferable that the first and second connection targets are electronic components.

[0216] Examples of electrodes provided on the above-mentioned connection target member include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. When the above-mentioned connection target member is a flexible printed circuit board, the electrodes are preferably gold electrodes, nickel electrodes, tin electrodes, silver electrodes, or copper electrodes. When the above-mentioned connection target member is a glass substrate, the electrodes are preferably aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, or tungsten electrodes. In the case of aluminum electrodes, the electrodes may be made solely of aluminum, or they may be electrodes in which an aluminum layer is 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.

[0217] The present invention will be specifically described below with reference to examples and comparative examples. The present invention is not limited to the following examples.

[0218] (Example 1) Preparation of conductive particle 1: Divinylbenzene copolymer resin particles ("Micropearl SP-220, particle size 20 μm" manufactured by Sekisui Chemical Co., Ltd.) were prepared as the base particle (S1).

[0219] 10 parts by weight of base particles (S1) were dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of palladium catalyst solution using an ultrasonic disperser, and the base particles (S1) were removed by filtering the solution. Next, 100 parts by weight of a 1% by weight solution of dimethylamine borane was added to the base particles (S1) to activate the surface of the base particles (S1). After thoroughly washing the activated base particles (S1) with water, a suspension (A1) was obtained by adding them to 500 parts by weight of distilled water and dispersing them.

[0220] The suspension (A1) was placed in a solution containing 25 g / L nickel sulfate, 15 ppm thallium nitrate, and 10 ppm bismuth nitrate to obtain a particle mixture (B1).

[0221] In addition, a nickel plating solution (C1) (pH 5.5) containing 100 g / L nickel sulfate, 40 g / L sodium hypophosphite, 15 g / L sodium citrate, 25 ppm thallium nitrate, and 10 ppm bismuth nitrate was prepared.

[0222] Furthermore, as an electroless tin plating solution for solder particle formation, a tin plating solution (D1) was prepared by adjusting the pH of a mixture containing 15 g / L tin sulfate, 45 g / L ethylenediaminetetraacetic acid, and 1.5 g / L phosphinic acid to 8.5 with sodium hydroxide.

[0223] Furthermore, as a reducing solution, a reducing solution (E1) was prepared by adjusting the pH of a solution containing 5 g / L of sodium borohydride to 10.0 with sodium hydroxide.

[0224] The nickel plating solution (C1) was gradually added dropwise to a particle mixture (B1) at 50°C in which particles were dispersed, and electroless nickel plating was performed. The dropping rate of the nickel plating solution (C1) was 12.5 mL / min, and the dropping time was 30 minutes, during which electroless nickel plating was performed (Ni plating process). In this way, a particle mixture (F1) was obtained containing particles having a nickel-phosphorus alloy conductive part as a first conductive part on the surface of the substrate particles S1.

[0225] Subsequently, the particle mixture (F1) was filtered to remove the particles, and these were washed with water to obtain particles in which a nickel-phosphorus alloy conductive portion was arranged on the surface of the base particle S1. After thoroughly washing these particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain the particle mixture (G1).

[0226] Next, the tin plating solution (D1) was gradually added to the particle mixture (G1) at 60°C in which the particles were dispersed. Then, the reducing solution (E1) was added dropwise, and electroless tin plating was performed. The dropping rate of the reducing solution (E1) was 0.5 mL / min, the dropping time was 40 minutes, and then the mixture was stirred for 10 minutes to perform electroless tin plating. After that, the particles were removed by filtration, washed with water, and dried to obtain conductive particles 1 having a nickel-phosphorus alloy conductive part and a tin conductive part (solder grains) on the surface of the base particle S1 (total thickness of the conductive part in the area without solder grains: 0.1 μm, height of solder grains: 0.6 μm).

[0227] ( reference Example 2) Preparation of conductive particles 2: A suspension (A1) of Example 1 was prepared.

[0228] The above suspension (A1) was placed in a solution containing 2 g / L potassium gold cyanide, 10 g / L sodium citrate, 0.5 g / L ethylenediaminetetraacetic acid, and 5 g / L sodium hydroxide to obtain a particle mixture (B2).

[0229] In addition, a gold plating solution (C2) (pH 8.0) was prepared as an electroless gold plating solution, containing 10 g / L of potassium gold cyanide, 20 g / L of sodium citrate, 5 ppm of thallium nitrate, 3.0 g / L of ethylenediaminetetraacetic acid, 20 g / L of sodium hydroxide, and 10 g / L of dimethylamine borane.

[0230] In addition, the tin plating solution (D1) and reducing solution (E1) from Example 1 were prepared as tin solutions for solder particle formation.

[0231] The gold plating solution (C2) was gradually added dropwise to a particle mixture (B2) at 60°C in which particles were dispersed, and electroless gold plating was performed. The dropping rate of the gold plating solution (C2) was 2 mL / min, and the dropping time was 45 minutes for electroless gold plating. In this way, a particle mixture (D2) containing particles in which a gold metal portion was arranged as a first conductive portion on the surface of the substrate particle S1 was obtained.

[0232] Subsequently, the particle mixture (D2) was filtered to remove the particles, and these particles were washed with water to obtain particles on which the gold conductive portion was arranged on the surface of the base particle S1. After thoroughly washing these particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain the particle mixture (E2).

[0233] Subsequently, solder particles were formed using the tin plating solution (D1) and the reducing solution (E1) in the same manner as in Example 1, and a particle mixture (F2) containing particles with solder particles formed on the gold conductive portion was obtained.

[0234] Subsequently, the particle mixture (F2) was filtered to remove the particles, which were then washed with water to obtain particles on which gold conductive parts were arranged on the surface of the base material particles S1 and solder particles were formed. After thoroughly washing these particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain the particle mixture (G2).

[0235] Next, electroless gold plating was performed by gradually dropping the gold plating solution (C2) onto a particle mixture (G2) at 60°C in which the particles were dispersed. The dropping rate of the gold plating solution (C2) was 1 mL / min, and the dropping time was 1 minute. After that, the particles were removed by filtration, washed with water, and dried to obtain conductive particles 2 having a gold conductive portion (total thickness of the conductive portion: 0.1 μm) on the surface of the substrate particle S1 and a gold thin film (thickness of the metal film: 0.01 μm) on top of solder particles (height of the solder particles: 0.6 μm).

[0236] ( reference Example 3) Preparation of conductive particles 3: Conductive particles comprising a nickel-phosphorus alloy conductive portion and solder particles were obtained in the same manner as in Example 1. The obtained conductive particles were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (A3).

[0237] In addition, a silver plating solution (B3) was prepared by adjusting the pH of a mixture of 30 g / L silver nitrate, 100 g / L succinimide, and 20 g / L formaldehyde to pH 8.0 with ammonia water as an electroless silver plating solution.

[0238] Furthermore, a particle mixture (C3) was obtained by mixing and dispersing the above 60°C suspension (A3) in the above silver plating solution (B3).

[0239] Next, the above silver plating solution (B3) was gradually added dropwise to the particle mixture (C3) at 60°C in which the particles were dispersed, and electroless silver plating was performed. The silver plating solution (B3) was added at a dropping rate of 10 mL / min for 10 minutes, and electroless plating was performed. After that, the particles were removed by filtration, washed with water, and dried to obtain conductive particles 3 having a nickel-phosphorus alloy conductive part (total thickness of the conductive part: 0.1 μm) and solder particles (height of the solder particles: 0.6 μm) on the surface of the substrate particles S1, and a thin silver film (thickness of the metal film: 0.01 μm) on top of the solder particles (height of the solder particles).

[0240] ( reference Example 4) Preparation of conductive particles 4: reference A suspension (A3) for Example 3 was prepared.

[0241] In addition, a silver solution (B4) was prepared by adjusting the pH of a mixture containing 1 g / L silver nitrate, 30 g / L ethylenediaminetetraacetic acid, and 20 ppm polyethylene glycol (molecular weight 6000) to pH 11 with sodium hydroxide.

[0242] Furthermore, a solution containing 10 g / L of sodium borohydride and 40 g / L of sodium hydroxide was prepared as a reducing solution for metal colloid precipitate formation (D4).

[0243] Furthermore, a particle mixture (C4) was obtained by mixing and dispersing the above suspension (A3) in the above silver solution (B4).

[0244] Next, 1 part by weight of the metal colloid precipitate formation reducing solution (D4) was added to the particle mixture (C4) at 25°C in which the particles were dispersed, and the mixture was stirred for 10 minutes. After that, the particles were removed by filtration, washed with water, and dried to obtain conductive particles 4 having silver colloid precipitates (particle size of metal colloid precipitates: 0.02 μm) on the surface of the conductive particles.

[0245] ( reference Example 5) Preparation of conductive particles 5: reference A suspension (A3) for Example 3 was prepared.

[0246] In addition, an indium solution (B5) was prepared by adjusting the pH of a mixture containing 5 g / L indium chloride, 40 g / L ethylenediaminetetraacetic acid, and 0.01 g / L polyvinylpyrrolidone to 10 with sodium hydroxide.

[0247] Also, as a reducing solution, reference A reducing solution (D4) for colloid precipitate formation was prepared for Example 4.

[0248] The above suspension (A3) was mixed and dispersed in the above indium solution (B5) to obtain a particle mixture (C5).

[0249] Ten parts by weight of the above-mentioned reducing solution for metal colloid precipitate formation (D4) was added to a particle mixture (C5) at 50°C in which particles were dispersed, and the mixture was stirred for 60 minutes. After that, the particles were removed by filtration, washed with water, and dried to obtain conductive particles 5 having indium colloid precipitates (particle size of metal colloid precipitates: 0.01 μm) on the surface of the conductive particles.

[0250] ( reference Example 6) Preparation of conductive particles 6: reference A suspension (A3) for Example 3 was prepared.

[0251] In addition, a copper solution (B6) was prepared by adjusting the pH of a mixture containing 10 g / L of copper sulfate pentahydrate, 40 g / L of ethylenediaminetetraacetic acid, and 0.1 g / L of polyvinylpyrrolidone to 9.0 with sodium hydroxide.

[0252] Also, as a reducing solution, reference A reducing solution (D4) for forming metal colloid precipitates was prepared for Example 4.

[0253] The above suspension (A3) was mixed and dispersed in the above copper solution (B6) to obtain a particle mixture (C6).

[0254] Five parts by weight of the above-mentioned reducing solution for metal colloid precipitate formation (D4) was added to a particle mixture (C6) at 25°C in which particles were dispersed, and the mixture was stirred for 60 minutes. After that, the particles were removed by filtration, washed with water, and dried to obtain conductive particles 6 having copper colloid precipitates (particle size of metal colloid precipitates: 0.01 μm) on the surface of the conductive particles.

[0255] ( reference Example 7) Preparation of conductive particles 7: As an electroless tin plating solution for solder particle formation, a tin plating solution (B7) was prepared by adjusting the pH of a mixture containing 15 g / L tin sulfate, 45 g / L ethylenediaminetetraacetic acid, 1.5 g / L phosphinic acid, and 10 g / L trehalose dihydrate to 9.0 with sodium hydroxide.

[0256] Conductive particles 7 were obtained in the same manner as in Example 1, except that the electroless tin plating solution for solder particle formation (D1) was replaced with the electroless tin plating solution for solder particle formation (B7) (total thickness of the conductive part in the area without solder particles: 0.2 μm, height of solder particles: 0.9 μm).

[0257] (Example 8) Preparation of conductive particles 8: (1) Preparation of silicone oligomers In a 100 ml separable flask placed in a hot bath, 1 part by weight of 1,3-divinyltetramethyldisiloxane and 20 parts by weight of 0.5% p-toluenesulfonic acid aqueous solution were added. After stirring at 40°C for 1 hour, 0.05 parts by weight of sodium bicarbonate was added. Then, 10 parts by weight of dimethoxymethylphenylsilane, 49 parts by weight of dimethyldimethoxysilane, 0.6 parts by weight of trimethylmethoxysilane, and 3.6 parts by weight of methyltrimethoxysilane were added, and the mixture was stirred for 1 hour. After that, 1.9 parts by weight of 10% potassium hydroxide aqueous solution was added, and the temperature was raised to 85°C. The reaction was carried out by stirring for 10 hours under reduced pressure using an aspirator. After the reaction was complete, the pressure was returned to atmospheric pressure and cooled to 40°C. 0.2 parts by weight of acetic acid was added, and the mixture was allowed to stand in a separatory funnel for at least 12 hours. The lower layer after two-layer separation was removed and purified using an evaporator to obtain a silicone oligomer.

[0258] (2) Preparation of silicone particle materials (including organic polymers) Solution A was prepared by dissolving 0.5 parts by weight of tert-butyl-2-ethylperoxyhexanoate (polymerization initiator, NOF Corporation's "Perbutyl O") in 30 parts by weight of the obtained silicone oligomer. Aqueous solution B was prepared by mixing 0.8 parts by weight of a 40% aqueous solution of triethanolamine lauryl sulfate (emulsifier) ​​and 80 parts by weight of a 5% aqueous solution of polyvinyl alcohol (degree of polymerization: approximately 2000, degree of saponification: 86.5-89 mol%, Nippon Synthetic Chemical Co., Ltd.'s "Gosenol GH-20") in 150 parts by weight of deionized water. Solution A was placed in a separable flask in a hot bath, and then aqueous solution B was added. Emulsification was then performed using a Shirasu Porous Glass (SPG) membrane (average pore size approximately 1 μm). The temperature was then raised to 85°C, and polymerization was carried out for 9 hours. The entire amount of polymerized particles was washed with water by centrifugation and freeze-dried. After drying, the aggregated particles were ground in a ball mill until the desired ratio (average secondary particle diameter / average primary particle diameter) was achieved, yielding silicone particles (base particle S2) with a particle diameter of 3.0 μm.

[0259] Conductive particles 8 were obtained in the same manner as in Example 1, except that the above-mentioned base material particles S1 were changed to the above-mentioned base material particles S2.

[0260] (Example 9) Fabrication of conductive particles 9: Except for using acrylic silicone oil (X-22-2445, manufactured by Shin-Etsu Chemical Co., Ltd.) at both ends instead of silicone oligomer, silicone particles (base particles S3) with a particle size of 3.0 μm were obtained in the same manner as in Example 8.

[0261] Conductive particles 9 were obtained in the same manner as in Example 1, except that the above-mentioned base material particles S1 were changed to the above-mentioned base material particles S3.

[0262] (Example 10) Preparation of conductive particles 10: A base particle S4 was prepared that differed from base particle S1 only in its particle size, with a particle size of 3.0 μm.

[0263] Conductive particles 10 were obtained in the same manner as in Example 1, except that the above-mentioned base material particles S1 were changed to the above-mentioned base material particles S4.

[0264] (Example 11) Preparation of conductive particles 11: A base particle S5 was prepared that differed from base particle S1 only in its particle size, with a particle size of 10.0 μm.

[0265] Conductive particles 11 were obtained in the same manner as in Example 1, except that the above-mentioned base material particles S1 were changed to the above-mentioned base material particles S5.

[0266] (Example 12) Preparation of conductive particles 12: A new base particle S6 was prepared, which differed from base particle S1 only in its particle size, with a particle size of 35.0 μm.

[0267] Conductive particles 12 were obtained in the same manner as in Example 1, except that the above-mentioned base material particles S1 were changed to the above-mentioned base material particles S6.

[0268] (Example 13) Preparation of Conductive Particles 13: The suspension (A1) of Example 1 was prepared.

[0269] A metal nickel slurry (average particle diameter: 150 nm) was prepared, and one part by weight thereof was added to the above suspension (A1) over 3 minutes to obtain a particle mixture (B13) containing base material particles S1 to which a core material was attached. Thereafter, electroless nickel plating was carried out in the same manner as in Example 1 using the nickel plating solution (C1) to obtain a particle mixture (F13) containing particles having a nickel-phosphorus alloy conductive part as the first conductive part on the surface of the base material particles containing a metal nickel core material.

[0270] Thereafter, the particle mixture (F13) was filtered to take out the particles, and the particles were washed with water to obtain particles having a nickel-phosphorus alloy conductive part containing a metal nickel core material disposed on the surface of the base material particles S1. After thoroughly washing these particles, they were added to 500 parts by weight of distilled water and dispersed to obtain a particle mixture (G13).

[0271] Thereafter, in the same manner as in Example 1, solder grains were formed using the tin plating solution (D1) and the reducing solution (E1) to obtain a particle mixture (H13) containing particles having solder grains formed on the nickel-phosphorus alloy conductive part.

[0272] Thereafter, the particles were taken out by filtration, washed with water, and dried to obtain conductive particles 13 having a nickel-phosphorus alloy conductive part (thickness of the entire conductive part in the portion without the core material: 0.1 μm) containing a core material and solder grains (height of the solder grains: 0.6 μm) on the surface of the base material particles S1.

[0273] (Example 14) Preparation of Conductive Particles 14: A titanium oxide particle slurry (average particle diameter: 150 nm) was prepared.

[0274] Conductive particles 14 were obtained in the same manner as in Example 13, except that the metal nickel particle slurry was changed to the titanium oxide particle slurry.

[0275] (Example 15) Preparation of conductive particles 15: An alumina particle slurry (average particle size 150 nm) was prepared.

[0276] Conductive particles 15 were obtained in the same manner as in Example 13, except that the metallic nickel particle slurry was replaced with the alumina particle slurry.

[0277] (Example 16) Preparation of conductive particles 16: A 1000 mL separable flask equipped with a four-neck separable cover, stirring blade, three-way stopcock, condenser, and temperature probe was prepared. 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 weighed into the separable flask and placed in deionized water to a solid content of 5% by weight. The mixture was then stirred at 200 rpm and polymerization was carried out at 70°C under a nitrogen atmosphere for 24 hours. After the reaction was complete, the mixture was freeze-dried to obtain insulating particles with ammonium groups on the surface, an average particle size of 220 nm, and a CV value of 10%.

[0278] Insulating particles were dispersed in deionized water under ultrasonic irradiation to obtain a 10% by weight aqueous dispersion of insulating particles.

[0279] Ten g of conductive particles obtained in Example 1 were dispersed in 500 mL of deionized water, and four g of an aqueous dispersion of insulating particles were added. The mixture was stirred at room temperature for six hours. After filtering through a 30 μm mesh filter, the mixture was further washed with methanol and dried to obtain conductive particles 16 with insulating particles attached.

[0280] Observation using a scanning electron microscope (SEM) revealed that only one layer of insulating particles was formed on the surface of the conductive particle 16. Image analysis calculated the coverage area of ​​the insulating particles (i.e., the projected area of ​​the particle diameter of the insulating particles) for an area of ​​2.5 μm from the center of the conductive particle 16, and the coverage rate was found to be 30%.

[0281] (Example 17) Preparation of conductive particles 17: In Example 1, conductive particles 17 were obtained in the same manner as in Example 1, except that the dropping time of the reducing solution (E1) was changed to 20 minutes, and the conductive particles 17 had a nickel-phosphorus alloy conductive portion and a tin conductive portion (solder particles) on the surface of the substrate particle S1 (total thickness of the conductive portion in the area without solder particles: 0.1 μm, height of solder particles: 0.3 μm).

[0282] (Comparative Example 1) Preparation of conductive particle A: A particle mixture (G1) was obtained in the same manner as in Example 1.

[0283] Furthermore, a tin plating solution (d1) was prepared by adjusting the pH of a mixture containing 20 g / L tin chloride, 50 g / L nitrilotriacetic acid, 2 g / L thiourea, 1 g / L thiomalic acid, 7.5 g / L ethylenediaminetetraacetic acid, and 15 g / L titanium trichloride with sulfuric acid to 7.0, as an electroless tin plating solution.

[0284] Next, electroless tin plating was performed by gradually dropping the tin plating solution (d1) onto a particle mixture (G1) at 70°C in which the particles were dispersed. The dropping rate of the tin plating solution (d1) was 30 mL / min, and the dropping time was 20 minutes. After that, the particles were removed by filtration, washed with water, and dried to obtain conductive particles A having a nickel-phosphorus alloy conductive part and a tin conductive part (total thickness of conductive part: 0.3 μm) on the surface of the substrate particles S1.

[0285] (Comparative Example 2) Preparation of conductive particle B: A particle mixture (G13) was prepared in the same manner as in Example 13.

[0286] Moreover, an electroless tin plating solution (d1) of Comparative Example 1 was prepared.

[0287] Electroless tin plating was carried out in the same manner as in Comparative Example 1 to obtain conductive particles B having a nickel-phosphorus alloy conductive portion containing a core material and a tin conductive portion (the thickness of the entire conductive portion in the portion without the core material: 0.3 μm) on the surface of the base material particles S1.

[0288] (Comparative Example 3) Production of conductive particles C: In the same manner as in Example 1, a particle mixture (F1) was obtained.

[0289] [[ID=十七]]Then, the particle mixture (F1) was filtered to take out the particles, washed with water, and dried to obtain conductive particles C having a nickel-phosphorus alloy conductive portion disposed on the surface of the base material particles S1 (the thickness of the conductive portion: 0.1 μm).

[0290] (Evaluation) <http: / / www.google.com / search?q=%220000978%22(1) Metal diffusion state of the conductive portion The obtained conductive particles were added to and dispersed in "Structobond XN-5A" manufactured by Mitsui Chemicals, Inc. so that the content became 10% by weight to prepare an anisotropic conductive paste.

[0291] A transparent glass substrate having a copper electrode pattern with L / S of 200 μm / 200 μm on the upper surface was prepared. Also, a semiconductor chip having a gold electrode pattern with L / S of 200 μm / 200 μm on the lower surface was prepared.

[0292] [[ID=三十二]] The anisotropic conductive paste immediately after production was applied onto the transparent glass substrate to a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the semiconductor chip was laminated on the anisotropic conductive paste layer such that the electrodes faced each other. Then, while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer became 250°C, a pressure heating head was placed on the upper surface of the semiconductor chip, and a pressure of 0.5 MPa was applied to cure the anisotropic conductive paste layer at 250°C to obtain a connection structure.

[0293] In the obtained connection structure, the metal diffusion state of the conductive part was determined by observing the cross-section of the connection structure.

[0294] Using a transmission electron microscope (FE-TEM, JEOL Ltd. "JEM-2010FEF"), the diffusion state of the conductive portion was observed by elemental mapping of the contact areas between conductive particles and copper and gold electrode patterns using an energy-dispersive X-ray spectrometer (EDX). The diffusion state of the conductive portion was determined according to the following criteria.

[0295] [Criteria for determining the diffusion state of conductive parts] A: In the connection, the conductive portion of the conductive particle is metal-diffused with the copper electrode pattern and the gold electrode pattern. B: In the connection, the conductive portion of the conductive particles does not undergo metal diffusion with the copper electrode pattern and the gold electrode pattern.

[0296] (2) Melting deformation state of the conductive part The connection structure obtained from the evaluation in (1) above was prepared. The prepared connection structure was placed in a Kulzer "Technovit 4000" and cured to create an embedded resin body for inspection of the connection structure. An ion milling device (Hitachi High-Technologies Corporation "IM4000") was used to cut out a cross-section of conductive particles, passing through the vicinity of the center of the connection structure in the embedded resin body for inspection.

[0297] Then, using a scanning electron microscope (FE-SEM), the obtained connection structure was observed in cross-section to confirm whether the conductive portion of the conductive particles had melted, deformed, and then solidified. The melting and deformation state of the conductive portion was determined according to the following criteria.

[0298] [Criteria for determining the melting and deformation state of conductive parts] A: The conductive part has melted and deformed, then solidified. B: The conductive part has not melted or deformed.

[0299] (3) Bonding condition of conductive parts A connection structure was prepared based on the evaluation in (1) above. The prepared connection structure was placed in a Kulzer Technovit 4000 and cured to create an embedded resin body for inspection of the connection structure. An ion milling device (Hitachi High-Technologies Corporation IM4000) was used to cut out a cross-section of conductive particles, passing through the vicinity of the center of the connection structure in the embedded resin body for inspection.

[0300] Then, the bonding state of the conductive parts was confirmed by cross-sectional observation of the obtained connection structure using a scanning electron microscope (FE-SEM). The bonding state of the conductive parts was judged according to the following criteria.

[0301] [Criteria for determining the bonding condition of conductive parts] A: In the connection area, in 5 or more out of 10 conductive particles, the conductive portion melts and deforms before solidifying and joining with the electrode. B: In the connection area, in 1 to 5 conductive particles out of 10 conductive particles, the conductive portion melts and deforms, then solidifies and joins with the electrode. C: In the connection area, none of the 10 conductive particles had their conductive portion melted or deformed; they were bonded to the electrode solely by metal diffusion. D: In the connection area, none of the 10 conductive particles are joined together.

[0302] (4) Area of ​​the portion containing solder (solder particles) out of 100% of the total surface area of ​​the substrate particles (coverage rate of solder (solder particles)) For the obtained conductive particles, the area of ​​the solder portion within 100% of the total surface area of ​​the substrate particles (solder coverage rate) was calculated. The above coverage rate (solder coverage rate) was calculated by performing elemental mapping by SEM-EDX analysis of the cross-section of the conductive particles and then performing image analysis.

[0303] (5) Particle size of conductive particles The particle size of the obtained conductive particles was calculated using a particle size distribution analyzer (Beckman Coulter's "Multisizer 4"). Specifically, the particle size was determined by measuring the particle size of approximately 100,000 conductive particles and calculating the average value.

[0304] (6) Thickness of the sufficient portion The obtained conductive particles were added to Kulzer's "Technovit 4000" to a content of 30% by weight, dispersed, and used to create an embedded resin body for testing. An ion milling device (Hitachi High-Technologies Corporation's "IM4000") was used to cut a cross-section of the conductive particles dispersed in the embedded resin body, passing through the vicinity of the center of the particles.

[0305] Then, using a field emission transmission electron microscope (FE-TEM) (JEOL Ltd. "JEM-ARM200F"), ten conductive particles were randomly selected, and the conductive portion of each conductive particle was observed. The thickness of the part of the conductive portion with the maximum thickness in each conductive particle was measured, and these were arithmetic mean to determine the thickness of the conductive portion.

[0306] (7) Aggregation of conductive particles The obtained conductive particles were observed to confirm whether or not aggregation of conductive particles had occurred. Aggregation of conductive particles was determined under the following conditions.

[0307] [Criteria for determining aggregation of conductive particles] ○○: No aggregation of conductive particles has occurred. ○: A small amount of aggregated conductive particles has occurred. △: A small amount of large aggregates have occurred among the aggregates of conductive particles. ×: Aggregation of conductive particles is occurring.

[0308] Small agglomeration refers to agglomeration where four or fewer particles are connected by a plating film, while large agglomeration refers to agglomeration where five or more particles are connected by a plating film.

[0309] (8) Height of solder particles The obtained conductive particles were added to Kulzer's "Technovit 4000" and dispersed to create an embedded resin body for conductive particle inspection, with a content of 30% by weight. An ion milling device (Hitachi High-Technologies Corporation's "IM4000") was used to cut a cross-section of the conductive particles dispersed in the embedded resin body, passing through the vicinity of the center of the particles.

[0310] Then, using a field emission scanning electron microscope (FE-SEM), conductive particles were randomly selected, and the solder particles on the conductive particles were observed. The height of the solder particles at five locations on the conductive particles was measured, and these were arithmetic mean values ​​were used to determine the total solder particle height.

[0311] (9) Aspect ratio of solder grains The aspect ratio of a solder particle is the ratio of its height to its width (solder particle height / solder particle width), and was calculated from the solder particle height and width.

[0312] The width of the solder particles mentioned above was measured as follows.

[0313] The obtained conductive particles were added to Kulzer's "Technovit 4000" and dispersed to create an embedded resin body for conductive particle inspection, with a content of 30% by weight. An ion milling device (Hitachi High-Technologies Corporation's "IM4000") was used to cut a cross-section of the conductive particles dispersed in the embedded resin body, passing through the vicinity of the center of the particles.

[0314] Then, using a field emission scanning electron microscope (FE-SEM), conductive particles were randomly selected, and the solder particles on the conductive particles were observed. The width of the solder particles at five locations on the conductive particles was measured, and these measurements were arithmetically averaged to obtain the solder particle width. From the obtained solder particle height and width, the aspect ratio of the solder particle (solder particle height / solder particle width) was calculated.

[0315] (10) Area of ​​the portion of the total surface area of ​​the solder grain that has metal colloid deposits or metal films (coverage rate of metal colloid deposits or metal films) For the obtained conductive particles, the area of ​​the portion containing metal colloidal precipitates or metal films within 100% of the total surface area of ​​the solder grains (coverage rate of metal colloidal precipitates or metal films) was calculated. The above coverage rate (coverage rate of metal colloidal precipitates or metal films) was calculated by performing elemental mapping by SEM-EDX analysis of the cross-section of the solder grains in the conductive particles and then performing image analysis.

[0316] The results are shown in Tables 1-4 below.

[0317] [Table 1]

[0318] [Table 2]

[0319] [Table 3]

[0320] [Table 4] [Explanation of symbols]

[0321] 1…Conductive particles 2...Base material particles 3...Conductive part 3A...First conductive part 3B...Second conductive part (solder part) 11... Conductive particles 12...Conductive part 12A...1a conductive part 12B...1b conductive part 12C...Second conductive part (solder part) 21... Conductive particles 22...Conductive part 22A...First conductive part 22B...Second conductive part (solder part) 22Ba... Molten second conductive part (solder part) 31... Conductive particles 32...Conductive part 32A...First conductive part 32B...Second conductive part (solder part) 32C...Third conductive part 41... Conductive particles 42...Conductive part 42A...First conductive part 42B...Second conductive part (solder part) 43…Metal colloid precipitates 51... Conductive particles 52...Conductive part 52A...1a conductive part 52B...1b conductive part 52C...Second conductive part (solder part) 53…Metal colloid precipitates 61... Conductive particles 62... Conductive part 62A...First conductive part 62B...Second conductive part (solder part) 63… Metal film 71... Conductive particles 72...Conductive part 72A...1a conductive part 72B...1b conductive part 72C...Second conductive part (solder part) 73… Metal film 81...Connection structure 82...First connection target member 82a...First electrode 83...Second connection target member 83a...Second electrode

Claims

1. Substrate particles and The substrate particles are further comprising a conductive portion disposed on the surface of the substrate particles, The conductive portion contains a component that can be metall-diffused at 400°C or below, or the conductive portion is meltable and deformable at 400°C or below. The conductive part has a soldered portion, The aforementioned solder portion is made of solder particles, The material of the aforementioned solder particles is pure tin. Of the total surface area of ​​the substrate particles, the area of ​​the portion containing the solder is 99% or less. The solder particles are located on the outer surface of the conductive part. Conductive particles having an aspect ratio (height of solder particle / width of solder particle) of 0.05 or more and 0.60 or less.

2. The conductive particles according to claim 1, wherein the height of the solder particles is 10 nm or more and 10 μm or less.

3. The conductive particle according to claim 1 or 2, wherein the outer surface of the solder particle has a metal colloid precipitate or a metal film.

4. The conductive particle according to claim 3, wherein the area of ​​the portion containing the metal colloid precipitate or the metal film is 5% or more and 100% or less of the total surface area of ​​the solder particle.

5. The conductive particle according to claim 3 or 4, wherein the metal species of the metal colloid precipitate or the metal film is nickel, cobalt, lead, gold, zinc, palladium, copper, silver, bismuth, or indium.

6. A conductive particle according to any one of claims 1 to 5, wherein the particle diameter is 0.5 μm or more and 500 μm or less.

7. It comprises conductive particles and a binder. A conductive material wherein the conductive particles are the conductive particles described in any one of claims 1 to 6.

8. 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 connecting portion is formed of conductive particles, or is formed of a conductive material containing the conductive particles and a binder. The conductive particles are the conductive particles described in any one of claims 1 to 6. A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.

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