Conductive particles, conductive materials and connection structures

Abstract

Provided are electroconductive particles capable of increasing reliability of electrical conduction and increasing reliability of insulation.　The electroconductive particles according to the present invention comprise base particles, and an electroconductive portion positioned on the surface of the base particles. When the electroconductive particles are compressed, at least one configuration among configurations A, B, C, and D is satisfied.　Configuration A: The ratio of the voltage change rate when compressed by 10% to the voltage change rate when compressed by 20% is 0.35 or less. Configuration B: The ratio of the voltage change rate when compressed by 10% to the voltage change rate when compressed by 30% is 0.25 or less. Configuration C: The ratio of the voltage change rate when compressed by 10% to the voltage change rate when compressed by 40% is 0.25 or less. Configuration D: the voltage change rate when compressed by 10% to the voltage change rate when compressed by 50% is 0.25 or less.

Description

[Technical Field]

[0001] The present invention relates to conductive particles that can be used for electrical connection between electrodes, etc. The present invention also relates to a conductive material and a connection structure that use the conductive particles. [Background technology]

[0002] Anisotropic conductive materials such as anisotropic conductive pastes and anisotropic conductive films are widely known. In the anisotropic conductive materials, conductive particles are dispersed in a binder resin. In addition, the conductive particles may be conductive particles having a base particle and a conductive portion disposed on the surface of the base particle.

[0003] The anisotropic conductive material is used to obtain various connection structures, such as a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), a connection between a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), a connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)), and a connection between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)).

[0004] As an example of the conductive particle, Patent Document 1 below discloses a conductive particle (conductive particle with insulating particles) comprising a conductive particle body having a conductive layer at least on its surface, and a plurality of insulating particles attached to the surface of the conductive particle body. The conductive particle body has a nickel-containing conductive layer on its surface, and the nickel-containing conductive layer has a plurality of protrusions on its surface. The coverage ratio, which is the area of ​​the portion covered by the insulating particles relative to the entire surface area of ​​the conductive particle body, is 60% or more and 95% or less. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-016414 Summary of the Invention [Problem to be solved by the invention]

[0006] To improve the insulation reliability of conductive particles, conductive particles with insulating particles attached to the surface of the conductive particle body are sometimes used. When vertical electrodes are electrically connected using conductive particles such as those described in Patent Document 1, the insulation reliability between horizontal electrodes that should not be connected can be improved to a certain extent. However, insulating particles located between the electrodes and the conductive particle body may not be sufficiently removed, resulting in poor electrical continuity between the vertical electrodes. Furthermore, when dispersing conductive particles or connecting vertical electrodes, insulating particles may detach from the surface of the conductive particle, causing multiple conductive particle bodies to come into contact laterally, thereby preventing sufficient insulation reliability between the horizontal electrodes. As a result, short circuits may occur between adjacent electrodes.

[0007] Furthermore, in recent years, in conductive materials containing conductive particles, the particle diameter of the conductive particles has been decreasing due to the trend toward finer pitches for wiring and connectors in printed wiring boards and the like.

[0008] When electrically connecting vertical electrodes using conductive particles with small particle diameters, the thickness of the conductive portion of the conductive particles may be increased to sufficiently reduce the connection resistance between the vertical electrodes. However, when the thickness of the conductive portion is increased, the conductive particles may aggregate when the conductive portion is formed by plating. When the conductive particles aggregate, laterally adjacent electrodes are more likely to be connected, which may make it difficult to improve the insulation reliability between the laterally adjacent electrodes.

[0009] Furthermore, if the thickness of the conductive portion is reduced in order to prevent the conductive particles from agglomerating, it may be difficult to sufficiently reduce the connection resistance between the upper and lower electrodes, resulting in insufficient improvement in the reliability of electrical conduction.

[0010] With conventional conductive particles, it is difficult to improve both electrical conductivity and insulation reliability.

[0011] An object of the present invention is to provide conductive particles that can improve conduction reliability and insulation reliability, and to provide a conductive material and a connection structure using the conductive particles. [Means for solving the problem]

[0012] According to a broad aspect of the present invention, there is provided a conductive particle comprising a base particle and a conductive portion disposed on the surface of the base particle, and satisfying at least one of the following configurations A, B, C, and D:

[0013] Configuration A: The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 20% is 0.35 or less. Configuration B: The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 30% is 0.25 or less. Configuration C: The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 40% is 0.25 or less. Configuration D: The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 50% is 0.25 or less.

[0014] In a specific aspect of the conductive particles according to the present invention, the conductive particles satisfy the above-mentioned configuration B.

[0015] In a specific aspect of the conductive particles according to the present invention, the voltage change rate when the conductive particles are compressed by 10% is 10% or less, and the voltage change rate when the conductive particles are compressed by 30% is 60% or more.

[0016] In a specific aspect of the conductive particle according to the present invention, the base particle contains a conductive metal inside the base particle.

[0017] In a specific aspect of the conductive particle according to the present invention, the base particle is a resin particle.

[0018] In a specific aspect of the conductive particle according to the present invention, the base particle is a porous particle.

[0019] In a specific aspect of the conductive particles according to the present invention, the BET specific surface area is 10 m 2 / g or more.

[0020] In a specific aspect of the conductive particle according to the present invention, the conductive portion has a thickness of 50 nm or less.

[0021] In a specific aspect of the conductive particle according to the present invention, the conductive particle does not have protrusions on the outer surface of the conductive portion.

[0022] In a specific aspect of the conductive particle according to the present invention, the conductive particle includes an insulating material disposed on an outer surface of the conductive portion.

[0023] In a specific aspect of the conductive particles according to the present invention, the conductive particles have a particle diameter of 0.1 μm or more and 1000 μm or less.

[0024] According to a broad aspect of the present invention, there is provided a conductive material including the conductive particles described above and a binder resin.

[0025] According to a broad aspect of the present invention, there is provided a connection structure comprising a first connection target member having a first electrode on its surface, a second connection target member having a second electrode on its surface, and a connection portion connecting the first connection target member and the second connection target member, wherein the connection portion is formed from conductive particles or from a conductive material containing conductive particles and a binder resin, the conductive particles being the conductive particles described above, and the first electrode and the second electrode being electrically connected by the conductive particles. [Effects of the Invention]

[0026] The conductive particle according to the present invention comprises a base particle and a conductive portion disposed on the surface of the base particle, and satisfies at least one of the above-mentioned structures A, B, C, and D. Because the conductive particle according to the present invention has the above-mentioned structure, it is possible to improve the conduction reliability and the insulation reliability. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a cross-sectional view showing a conductive particle according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing a conductive particle according to a second embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view showing a conductive particle according to a third embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view showing an example of a connection structure using conductive particles according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be described in detail below.

[0029] (Conductive particles) The conductive particle according to the present invention comprises a base particle and a conductive portion disposed on the surface of the base particle, and satisfies at least one of the following configurations A, B, C, and D.

[0030] Configuration A: The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 20% is 0.35 or less. Configuration B: The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 30% is 0.25 or less. Configuration C: The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 40% is 0.25 or less. Configuration D: The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 50% is 0.25 or less.

[0031] The conductive particles according to the present invention have the above-described configuration, and therefore can improve both electrical conduction reliability and insulation reliability. When electrodes are electrically connected, the conductive particles according to the present invention can effectively reduce the connection resistance between the vertically connected electrodes, thereby improving electrical conduction reliability. The conductive particles according to the present invention can sufficiently reduce the connection resistance between the vertically connected electrodes even when the conductive portion is relatively thin. Furthermore, the conductive particles according to the present invention can improve the insulation reliability between horizontally connected electrodes that should not be connected. In particular, the conductive particles according to the present invention can sufficiently improve insulation reliability even when the conductive particles do not have an insulating material on their outer surfaces. As a result, short circuits between adjacent electrodes can be prevented.

[0032] With conventional conductive particles, it is difficult to improve both electrical conductivity and insulation reliability.

[0033] The present inventors have found that the use of specific conductive particles can improve both electrical conductivity and insulation reliability. The conductive particles according to the present invention exhibit a smaller voltage change rate when compressed by 10% than when compressed by 20%, 30%, 40%, or 50%. The conductive particles according to the present invention exhibit better conductivity when compressed by 20%, 30%, 40%, or 50% than when compressed by 10%. Specifically, the conductive particles according to the present invention exhibit low conductivity when in contact with vertically adjacent electrodes (e.g., when compressed by approximately 10% between two connection target members or two electrodes). The conductive particles according to the present invention exhibit high conductivity when compressed to some extent by vertically adjacent electrodes (e.g., when compressed by 30% or more between two connection target members or two electrodes by pressure, etc.).

[0034] When the conductive particles according to the present invention satisfy the above-mentioned configuration A, high conductivity can be exhibited by compressing the conductive particles by 20% when used. When the conductive particles according to the present invention satisfy the above-mentioned configuration B, high conductivity can be exhibited by compressing the conductive particles by 30% when used. When the conductive particles according to the present invention satisfy the above-mentioned configuration C, high conductivity can be exhibited by compressing the conductive particles by 40% when used. When the conductive particles according to the present invention satisfy the above-mentioned configuration D, high conductivity can be exhibited by compressing the conductive particles by 50% when used.

[0035] The conductive particles according to the present invention may satisfy at least two of the above-mentioned constitutions A to D, may satisfy at least three of the above-mentioned constitutions A to D, or may satisfy all four of the above-mentioned constitutions A to D. When the conductive particles according to the present invention satisfy two or more of the above-mentioned constitutions A to D, high conductivity can be exhibited over a wider range of compression ratios within the range of 20 to 50% when the conductive particles are compressed.

[0036] The conductive particles according to the present invention may satisfy only the above-mentioned configuration A, may satisfy only the above-mentioned configuration B, may satisfy only the above-mentioned configuration C, or may satisfy only the above-mentioned configuration D. The conductive particles according to the present invention may satisfy both the above-mentioned configuration A and the above-mentioned configuration B, may satisfy both the above-mentioned configuration A and the above-mentioned configuration C, may satisfy both the above-mentioned configuration A and the above-mentioned configuration D, may satisfy both the above-mentioned configuration B and the above-mentioned configuration C, may satisfy both the above-mentioned configuration B and the above-mentioned configuration D, may satisfy both the above-mentioned configuration C and the above-mentioned configuration D. The conductive particles according to the present invention may satisfy both the above-mentioned configuration A, the above-mentioned configuration B, and the above-mentioned configuration C, may satisfy both the above-mentioned configuration A, the above-mentioned configuration B, and the above-mentioned configuration D, may satisfy both the above-mentioned configuration A, the above-mentioned configuration C, and the above-mentioned configuration D, or may satisfy both the above-mentioned configuration B, the above-mentioned configuration C, and the above-mentioned configuration D. Furthermore, the conductive particles according to the present invention may satisfy both the above-mentioned configuration A, the above-mentioned configuration B, the above-mentioned configuration C, and the above-mentioned configuration D. As long as the conductive particles of the present invention satisfy at least one of the structures A, B, C, and D, they may not satisfy the structure A, may not satisfy the structure B, may not satisfy the structure C, or may not satisfy the structure D.

[0037] In order to more effectively exert the effects of the present invention, it is preferable that the conductive particles satisfy the above-mentioned configuration B.

[0038] The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 20% is preferably 0.35 or less. In conductive particles satisfying the above configuration A, the ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 20% is 0.35 or less. In conductive particles satisfying the above configuration A, the ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 20% is preferably 0.30 or less, more preferably 0.25 or less, even more preferably 0.20 or less, particularly preferably 0.15 or less, and most preferably 0.10 or less. In this case, the insulation reliability is further improved. The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 20% may be 0 or more, may exceed 0, or may be 0.001 or more.

[0039] The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 30% is preferably 0.25 or less. In conductive particles satisfying the above-mentioned configuration B, the ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 30% is 0.25 or less. In conductive particles satisfying the above-mentioned configuration B, the ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 30% is preferably 0.20 or less, more preferably 0.15 or less, even more preferably 0.10 or less, particularly preferably 0.05 or less, and most preferably 0.01 or less. In this case, the insulation reliability is further improved. The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 30% may be 0 or more, may exceed 0, or may be 0.001 or more.

[0040] The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 40% is preferably 0.25 or less. In conductive particles satisfying the above configuration C, the ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 40% is 0.25 or less. In conductive particles satisfying the above configuration C, the ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 40% is preferably 0.20 or less, more preferably 0.15 or less, even more preferably 0.10 or less, particularly preferably 0.05 or less, and most preferably 0.01 or less. In this case, the insulation reliability is further improved. The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 40% may be 0 or more, may exceed 0, or may be 0.001 or more.

[0041] The ratio of the voltage change rate when the conductive particles are compressed 10% to the voltage change rate when the conductive particles are compressed 50% is preferably 0.25 or less. In conductive particles satisfying the above-mentioned configuration D, the ratio of the voltage change rate when the conductive particles are compressed 10% to the voltage change rate when the conductive particles are compressed 50% is 0.25 or less. In conductive particles satisfying the above-mentioned configuration D, the ratio of the voltage change rate when the conductive particles are compressed 10% to the voltage change rate when the conductive particles are compressed 50% is preferably 0.20 or less, more preferably 0.15 or less, even more preferably 0.10 or less, particularly preferably 0.05 or less, and most preferably 0.01 or less. In this case, the insulation reliability is further improved. The ratio of the voltage change rate when the conductive particles are compressed 10% to the voltage change rate when the conductive particles are compressed 50% may be 0 or more, may exceed 0, or may be 0.001 or more.

[0042] From the viewpoint of further improving insulation reliability, the voltage change rate when the conductive particles are compressed by 10% is preferably 10% or less, more preferably 8% or less. When the conductive particles satisfy each of the above configurations A, B, C, and D, it is preferable that the conductive particles satisfy the preferred characteristics of the voltage change rate when compressed by 10%. The voltage change rate when the conductive particles are compressed by 10% may be 0% or more, or may even exceed 0%.

[0043] From the viewpoint of more effectively improving the conduction reliability and insulation reliability, the voltage change rate when the conductive particles are compressed by 20% is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more, and is preferably 75% or less, and more preferably 70% or less. When the conductive particles satisfy the above-mentioned configuration A, it is preferable that the conductive particles satisfy the preferred characteristics of the voltage change rate when compressed by 20%.

[0044] From the viewpoint of more effectively improving the conduction reliability and insulation reliability, the voltage change rate when the conductive particles are compressed by 30% is preferably 60% or more, more preferably 65% ​​or more, and even more preferably 70% or more, and is preferably 99% or less, and more preferably 90% or less. When the conductive particles satisfy the above-mentioned configuration B, it is preferable that the conductive particles satisfy the preferred characteristics of the voltage change rate when compressed by 30%.

[0045] From the viewpoint of more effectively improving the conduction reliability and insulation reliability, the voltage change rate when the conductive particles are compressed by 40% is preferably 75% or more, more preferably 80% or more, and even more preferably 85% or more, and is preferably 99% or less, and more preferably 95% or less. When the conductive particles satisfy the above-mentioned configuration C, it is preferable that the conductive particles satisfy the preferred characteristics of the voltage change rate when compressed by 40%.

[0046] From the viewpoint of more effectively improving the conduction reliability and insulation reliability, the voltage change rate when the conductive particles are compressed by 50% is preferably 75% or more, more preferably 80% or more, and even more preferably 85% or more, and is preferably 99% or less, and more preferably 95% or less. When the conductive particles satisfy the above-mentioned configuration D, it is preferable that the conductive particles satisfy the preferred characteristics of the voltage change rate when compressed by 50%.

[0047] From the viewpoint of more effectively improving the conduction reliability and insulation reliability, it is preferable that the voltage change rate when the conductive particles are compressed by 10% is 10% or less, and that when the conductive particles are compressed by 30%, the voltage change rate is 60% or more.

[0048] The rate of change in voltage when the conductive particles are compressed can be measured as follows.

[0049] Voltage change rate (%) = {(voltage before compression - voltage after compression) / voltage before compression} x 100

[0050] The voltage of the conductive particles before compression and the voltage when the conductive particles are compressed by 10%, 20%, 30%, 40%, or 50% can be measured at 25°C using a micro-compression tester for resistance measurement ("ENT-NEXUS" manufactured by Elionix).

[0051] The BET specific surface area of ​​the conductive particles is preferably 10 m 2 / g or more, more preferably 12m 2 / g or more, more preferably 15m 2 / g or more, preferably 1200m 2 / g or less, more preferably 1000m 2 / g or less, more preferably 800m 2 Regarding a more preferable range, the BET specific surface area of ​​the conductive particles is preferably 50 m 2 / g or more, more preferably 100m 2 / g or more, more preferably 150m 2 / g or more, particularly preferably 200m 2 / g or more, most preferably 250m 2 When the BET specific surface area is equal to or greater than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited.

[0052] The BET specific surface area of ​​the conductive particles can be measured from the nitrogen adsorption isotherm according to the BET method. Examples of devices for measuring the BET specific surface area of ​​the conductive particles include the "NOVA4200e" manufactured by Quantachrome Instruments.

[0053] The particle diameter of the conductive particles is preferably 0.1 μm or more, more preferably 1 μm or more, and preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 100 μm or less, even more preferably 50 μm or less, even more preferably 20 μm or less, and particularly preferably 10 μm or less. When the particle diameter of the conductive particles is above the above lower limit and below the above upper limit, when electrodes are connected using the conductive particles, the contact area between the conductive particles and the electrodes is sufficiently large, and agglomerated conductive particles are less likely to form when forming a conductive portion. Furthermore, the gap between electrodes connected via the conductive particles is not too large, and the conductive portion is less likely to peel off from the surface of the resin particles. Furthermore, when the particle diameter of the conductive particles is above the above lower limit and below the above upper limit, the conductive particles can be suitably used as a conductive material.

[0054] The particle diameter of the conductive particles means the diameter when the conductive particles are spherical, and when the conductive particles are other than spherical, means the diameter when the conductive particles are assumed to be a perfect sphere with a volume equivalent to that of the conductive particles.

[0055] The particle diameter of the conductive particles is preferably an average particle diameter, and more preferably a number average particle diameter. The particle diameter of the conductive particles can be determined by observing 50 random conductive particles with an electron microscope or optical microscope and calculating the average particle diameter of each conductive particle, or by using a particle size distribution analyzer. When observed with an electron microscope or optical microscope, the particle diameter of each conductive particle is determined as the particle diameter in equivalent circle diameter. When observed with an electron microscope or optical microscope, the average particle diameter of 50 random conductive particles in equivalent circle diameter is approximately equal to the average particle diameter in equivalent sphere diameter. When observed with a particle size distribution analyzer, the particle diameter of each conductive particle is determined as the particle diameter in equivalent sphere diameter. The particle diameter of the conductive particles is preferably calculated using a particle size distribution analyzer.

[0056] The coefficient of variation (CV value) of the particle diameter of the conductive particles is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. When the coefficient of variation of the particle diameter of the conductive particles is equal to or less than the upper limit, the electrical conductivity reliability and insulating reliability between electrodes can be more effectively improved.

[0057] The coefficient of variation (CV value) can be measured as follows.

[0058] CV value (%) = (ρ / Dn) × 100 ρ: Standard deviation of the particle size of the conductive particles Dn: average particle diameter of conductive particles

[0059] The 10% K value (compressive elastic modulus when compressed by 10%) of the conductive particles is preferably 100 N / mm 2 More preferably, 1000N / mm 2 or more, preferably 25000N / mm 2 Less than or equal to 20,000 N / mm 2 When the 10% K value of the conductive particles is equal to or greater than the above lower limit and equal to or less than the above upper limit, the connection resistance can be further reduced and the conduction reliability can be further improved.

[0060] The 30% K value (compressive elastic modulus when compressed by 30%) of the conductive particles is preferably 100 N / mm 2 More preferably, 1000N / mm 2 or more, preferably 15000N / mm 2 Less than or equal to 10,000 N / mm 2 When the 30% K value of the conductive particles is equal to or greater than the above lower limit and equal to or less than the above upper limit, the connection resistance can be further reduced and the conduction reliability can be further improved.

[0061] The ratio of the 10% K value of the conductive particles to the 30% K value of the conductive particles (10% K value of conductive particles / 30% K value of conductive particles) is preferably 1.5 or more, more preferably 1.55 or more, and preferably 5 or less, more preferably 4.5 or less. When the ratio (10% K value of conductive particles / 30% K value of conductive particles) is equal to or greater than the above lower limit and equal to or less than the above upper limit, the connection resistance can be further reduced and the conduction reliability can be further improved.

[0062] The 10% K value and the 30% K value of the conductive particles can be measured as follows.

[0063] Using a micro-compression tester, one conductive particle is compressed with the end face of a smooth cylindrical indenter (diameter 100 μm, made of diamond) under conditions of 25°C, a compression speed of 0.3 mN / sec, and a maximum test load of 20 mN. The load value (N) and compression displacement (mm) at this time are measured. From the obtained measured values, the compressive elastic modulus (10% K value and 30% K value) can be calculated using the following formula. As the micro-compression tester, a Fischerscope H-100 manufactured by Fischer GmbH or the like is used. The 10% K value and the 30% K value of the conductive particle are preferably calculated by arithmetically averaging the 10% K value and the 30% K value of 50 arbitrarily selected conductive particles.

[0064] 10% K value and 30% K value (N / mm 2 )=(3 / 2 1 / 2 )·F·S -3 / 2 ·R -1 / 2 F: Load value (N) when the conductive particles are compressed by 10% or 30% S: Compression displacement (mm) when the conductive particles are compressed by 10% or 30% R: Radius of conductive particle (mm)

[0065] The compressive elastic modulus universally and quantitatively represents the hardness of the conductive particles. The compressive elastic modulus can be used to quantitatively and unambiguously represent the hardness of the conductive particles. Furthermore, the ratio (10% K value of the conductive particles / 30% K value of the conductive particles) can quantitatively and unambiguously represent the physical properties of the conductive particles at the time of initial compression.

[0066] The shape of the conductive particles is not particularly limited, and may be spherical, may be a shape other than spherical, or may be flat or the like.

[0067] The present invention will be specifically described below with reference to the drawings.

[0068] FIG. 1 is a cross-sectional view showing a conductive particle according to a first embodiment of the present invention.

[0069] The conductive particle 1 shown in FIG. 1 has a base particle 2 and a conductive portion 3. The conductive portion 3 is disposed on the surface of the base particle 2. In the first embodiment, the conductive portion 3 is in contact with the surface of the base particle 2. The conductive particle 1 is a coated particle in which the surface of the base particle 2 is coated with the conductive portion 3.

[0070] In the conductive particle 1, the base particle 2 contains a conductive metal inside the base particle body. The base particle 2 is, for example, a porous particle. The base particle 2 has a base particle body and a conductive metal.

[0071] In the conductive particle 1, the conductive portion 3 is a single-layer conductive layer. In the conductive particle 1, the base particle 2 contains a conductive metal inside the base particle 2. In the conductive particle, the conductive portion may cover the entire surface of the base particle, or the conductive portion may cover only a portion of the surface of the base particle. In the conductive particle, the conductive portion may be a single-layer conductive layer, or may be a multi-layer conductive layer composed of two or more layers.

[0072] Unlike conductive particles 11 and 21 described later, conductive particle 1 does not have a core material. Conductive particle 1 does not have protrusions on its surface. Conductive particle 1 is spherical. Conductive portion 3 does not have protrusions on its outer surface. As such, the conductive particle according to the present invention may not have protrusions on its conductive surface and may be spherical. Furthermore, unlike conductive particles 11 and 21 described later, conductive particle 1 does not have an insulating material. However, conductive particle 1 may have an insulating material disposed on the outer surface of conductive portion 3.

[0073] FIG. 2 is a cross-sectional view showing a conductive particle according to a second embodiment of the present invention.

[0074] 2 includes a base particle 2, a conductive portion 12, a plurality of core materials 13, and a plurality of insulating materials 14. The conductive portion 12 is disposed on the surface of the base particle 2 so as to be in contact with the base particle 2.

[0075] In the conductive particle 11, the conductive portion 12 is a single-layer conductive layer. In the conductive particle, the conductive portion may cover the entire surface of the base particle, or the conductive portion may cover only a portion of the surface of the base particle. In the conductive particle, the conductive portion may be a single-layer conductive layer, or may be a multi-layer conductive layer composed of two or more layers.

[0076] The conductive particle 11 has a plurality of protrusions 11a on its conductive surface. The conductive portion 12 has a plurality of protrusions 12a on its outer surface. A plurality of core materials 13 are arranged on the surface of the base particle 2. The plurality of core materials 13 are embedded in the conductive portion 12. The core materials 13 are arranged inside the protrusions 11a, 12a. The conductive portion 12 covers the plurality of core materials 13. The outer surface of the conductive portion 12 is raised by the plurality of core materials 13, forming the protrusions 11a, 12a.

[0077] The conductive particle 11 has an insulating material 14 disposed on the outer surface of the conductive portion 12. At least a portion of the outer surface of the conductive portion 12 is coated with the insulating material 14. The insulating material 14 is formed from a material having insulating properties and is an insulating particle. In this way, the conductive particle according to the present invention may have an insulating material disposed on the outer surface of the conductive portion. However, the conductive particle according to the present invention does not necessarily have to have an insulating material.

[0078] FIG. 3 is a cross-sectional view showing a conductive particle according to a third embodiment of the present invention.

[0079] 3 includes a base particle 2, a conductive portion 22, a plurality of core materials 13, and a plurality of insulating materials 14. The conductive portion 22 as a whole includes a first conductive portion 22A on the base particle 2 side and a second conductive portion 22B on the opposite side to the base particle 2 side.

[0080] The only difference between conductive particle 11 and conductive particle 21 is the conductive portion. That is, conductive particle 11 has conductive portion 12 with a single layer structure, while conductive particle 21 has first conductive portion 22A and second conductive portion 22B with a two-layer structure. First conductive portion 22A and second conductive portion 22B are formed as separate conductive portions.

[0081] The first conductive portion 22A is disposed on the surface of the base particle 2. The first conductive portion 22A is disposed between the base particle 2 and the second conductive portion 22B. The first conductive portion 22A is in contact with the base particle 2. The second conductive 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 22B is disposed on the surface of the first conductive portion 22A. The conductive particle 21 has a plurality of protrusions 21a on its conductive surface. The conductive portion 22 has a plurality of protrusions 22a on its outer surface. The first conductive portion 22A has a plurality of protrusions 22Aa on its outer surface. The second conductive portion 22B has a plurality of protrusions 22Ba on its outer surface.

[0082] Other details of the conductive particles will be described below.

[0083] In this specification, "(meth)acrylate" means one or both of "acrylate" and "methacrylate", and "(meth)acrylic" means one or both of "acrylic" and "methacrylic".

[0084] (base material particles) The material of the base particles is not particularly limited. The material of the base particles may be an organic material or an inorganic material. Examples of base particles formed only from the organic material include resin particles. Examples of base particles formed only from the inorganic material include inorganic particles excluding metals. Examples of base particles formed from both the organic material and the inorganic material include organic-inorganic hybrid particles. From the viewpoint of further improving the compression properties of the base particles, the base particles are preferably resin particles or organic-inorganic hybrid particles, and more preferably resin particles. From the viewpoint of more effectively exerting the effects of the present invention, the base particles are preferably resin particles.

[0085] Furthermore, from the viewpoint of more effectively exerting the effects of the present invention, the base particles are preferably porous particles. The base particles preferably have a porous structure. The base particles are preferably resin particles having a porous structure, and are preferably resin particles that are porous particles.

[0086] Examples of the organic material 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, phenolic resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyamide-imide, polyether ether ketone, polyether sulfone, and divinylbenzene polymer. The divinylbenzene polymer may be a divinylbenzene copolymer. Examples of the divinylbenzene copolymer include a divinylbenzene-styrene copolymer and a divinylbenzene-(meth)acrylic acid ester copolymer. The material of the base particle is preferably a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group, since this allows the compression characteristics of the base particle to be easily controlled within a suitable range.

[0087] When the base particle is obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group may be a non-crosslinkable monomer or a crosslinkable monomer.

[0088] Examples of the non-crosslinkable monomer include vinyl compounds such as styrene monomers, α-methylstyrene, and chlorostyrene; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; acid vinyl 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 (meth)acrylate. Examples of suitable (meth)acrylate compounds include alkyl (meth)acrylate compounds such as (meth)acrylate and isobornyl (meth)acrylate; oxygen-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; α-olefin compounds such as diisobutylene, isobutylene, linearene, ethylene, and propylene; and conjugated diene compounds such as isoprene and butadiene.

[0089] Examples of the crosslinkable monomer include vinyl compounds such as vinyl monomers like divinylbenzene, 1,4-divinyloxybutane, and divinylsulfone; (meth)acrylic compounds such as polyfunctional (meth)acrylate compounds like 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 of silane compounds include triallyl (iso) cyanurate, triallyl trimellitate, diallyl phthalate, diallyl acrylamide, and diallyl ether; examples of silane compounds include 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 of suitable silane alkoxides include polymerizable double bonds 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 single-end-modified silicone oil, double-end-modified silicone oil, and side-chain silicone oil; and carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride.

[0090] The base particles can be obtained by polymerizing the polymerizable monomer having the ethylenically unsaturated group. The polymerization method is not particularly limited, and includes known methods such as radical polymerization, ionic polymerization, polycondensation (condensation polymerization, polycondensation), addition condensation, living polymerization, and living radical polymerization. Another polymerization method includes suspension polymerization in the presence of a radical polymerization initiator.

[0091] Examples of the inorganic material include silica, alumina, barium titanate, zirconia, carbon black, silicate glass, borosilicate glass, lead glass, soda-lime glass, and alumina silicate glass.

[0092] The base particles may be organic-inorganic hybrid particles. The base particles may be core-shell particles. When the base particles are organic-inorganic hybrid particles, examples of inorganic materials for the base particles include silica, alumina, barium titanate, zirconia, and carbon black. The inorganic material is preferably not a metal. The base particles formed from silica are not particularly limited, but examples include base particles obtained by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, followed by firing as necessary. Examples of the organic-inorganic hybrid particles include organic-inorganic hybrid particles formed from a crosslinked alkoxysilyl polymer and an acrylic resin.

[0093] The organic-inorganic hybrid particles are preferably core-shell 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 base particle is preferably an organic-inorganic hybrid particle having an organic core and an inorganic shell disposed on the surface of the organic core.

[0094] Examples of the material for the organic core include the organic materials described above.

[0095] Examples of materials for the inorganic shell include the inorganic substances listed as materials for the base particle described above. 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 by 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.

[0096] Furthermore, from the viewpoint of more effectively achieving the effects of the present invention, it is preferable that the base particle contains a conductive metal inside the base particle. Details of the conductive metal contained inside the base particle will be described later. It is preferable that the base particle has a base particle body and a conductive metal inside the base particle body. It is more preferable that the base particle contains a conductive metal inside the base particle (base particle body), which is a porous particle. When the base particle contains a conductive metal inside, the conductive particles are compressed when connecting upper and lower electrodes, so that not only a conductive path is formed on the surface (conductive portion) of the conductive particle, but also a conductive path can be formed inside the conductive particle (conductive metal). Furthermore, the conductive metal inside the conductive particle contributes to a reduction in connection resistance even if it does not form a complete conductive path. As a result, even if the thickness of the conductive portion is relatively thin, the connection resistance between the upper and lower electrodes can be sufficiently reduced and the conduction reliability can be further improved. From the viewpoint of further improving the compression characteristics of the base particle, it is preferable that the base particle body is a resin particle body or an organic-inorganic hybrid particle body, and more preferably a resin particle body. Furthermore, from the viewpoint of more effectively exerting the effects of the present invention, the base particle body is preferably a porous particle body. The base particle body preferably has a porous structure. The base particle body is preferably a resin particle body having a porous structure.

[0097] The BET specific surface area of ​​the base particles is preferably 8 m 2 / g or more, more preferably 12m 2 / g or more, preferably 1200m 2 / g or less, more preferably 1000m 2 / g or less. When the BET specific surface area is equal to or greater than the lower limit and equal to or less than the upper limit, the conductive metal can be easily contained inside the base particle. When the BET specific surface area is equal to or greater than the lower limit and equal to or less than the upper limit, the effects of the present invention can be more effectively exhibited.

[0098] The BET specific surface area of ​​the base particles can be measured from the nitrogen adsorption isotherm according to the BET method. Examples of devices for measuring the BET specific surface area of ​​the base particles include the "NOVA4200e" manufactured by Quantachrome Instruments.

[0099] The total pore volume of the substrate particles is preferably less than 0.01 cm 3 / g or more, more preferably 0.1 cm 3 / g or more, preferably 3 cm 3 / g or less, more preferably 1.5cm 3 / g or less. When the total pore volume is equal to or greater than the lower limit and equal to or less than the upper limit, the conductive metal can be easily contained inside the base particle. When the total pore volume is equal to or greater than the lower limit and equal to or less than the upper limit, the effects of the present invention can be more effectively exhibited. In the conductive particle, the pore volume also includes the volume of the portion where the conductive metal is contained in the pore. In the conductive particle, the pore volume is the total pore volume of the portion where the conductive metal is not contained in the pore and the portion where the conductive metal is contained in the pore.

[0100] The total pore volume of the base particle can be measured from a nitrogen adsorption isotherm according to the BJH method. Examples of a device for measuring the total pore volume of the base particle include the "NOVA4200e" manufactured by Quantachrome Instruments.

[0101] The average pore diameter of the base particles is preferably 10 nm or less, more preferably 5 nm or less. There is no particular limitation on the lower limit of the average pore diameter of the base particles. The average pore diameter of the base particles may be 1 nm or more. When the average pore diameter is equal to or greater than the lower limit and equal to or less than the upper limit, the effects of the present invention can be more effectively exhibited. When the average pore diameter is equal to or greater than the lower limit and equal to or less than the upper limit, the conductive metal can be easily contained inside the base particles.

[0102] The average pore size of the base particles can be measured from a nitrogen adsorption isotherm according to the BJH method. Examples of devices for measuring the average pore size of the base particles include the NOVA4200e manufactured by Quantachrome Instruments.

[0103] The porosity of the base particle is preferably 5% or more, more preferably 10% or more, and preferably 90% or less, more preferably 70% or less. When the porosity is above the lower limit and below the upper limit, the conductive metal can be easily contained inside the base particle. When the porosity is above the lower limit and below the upper limit, the effects of the present invention can be more effectively achieved. Note that in the conductive particle, the porosity also includes the portion where the conductive metal is contained in the voids. In the conductive particle, the porosity is the total porosity of the portion where the conductive metal is not contained in the voids and the portion where the conductive metal is contained in the voids.

[0104] The porosity of the base particle can be calculated by measuring the cumulative amount of mercury intrusion against the applied pressure using mercury intrusion porosimetry. Examples of devices for measuring the porosity of the base particle include the mercury porosimeter "Poremaster 60" manufactured by Quantachrome Instruments.

[0105] Base particles satisfying the preferred ranges for the BET specific surface area, porosity, and the like can be obtained, for example, by a base particle manufacturing method comprising the following steps: Mixing a polymerizable monomer with an organic solvent that does not react with the polymerizable monomer to prepare a polymerizable monomer solution; Adding the polymerizable monomer solution and an anionic dispersion stabilizer to a polar solvent and emulsifying to obtain an emulsion; Adding the emulsion in several portions to allow the seed particles to absorb the monomer, thereby obtaining a suspension containing seed particles swollen with the monomer; Polymerizing the polymerizable monomer to obtain base particles. Examples of the polymerizable monomer include monofunctional monomers and polyfunctional monomers. The organic solvent that does not react with the polymerizable monomer is not particularly limited as long as it is incompatible with polar solvents such as water, which are the polymerization medium. Examples of the organic solvent include cyclohexane, toluene, xylene, ethyl acetate, butyl acetate, allyl acetate, propyl acetate, chloroform, methylcyclohexane, and methyl ethyl ketone. The amount of the organic solvent added is preferably 105 to 215 parts by weight, and more preferably 110 to 210 parts by weight, relative to 100 parts by weight of the polymerizable monomer component. When the amount of the organic solvent added is within the above preferred range, the BET specific surface area, porosity, etc. can be controlled within more suitable ranges, making it easier to obtain dense pores inside the particles.

[0106] Base particles satisfying the preferred ranges for the BET specific surface area, porosity, and the like have a relatively large number of voids within the base particle. Therefore, when forming a conductive portion on the surface of the base particle, the conductive portion fills the fine voids within the base particle, allowing the conductive metal to be easily incorporated into the base particle. Furthermore, in the conductive particle, when connecting upper and lower electrodes, the conductive particles are preferably compressed, deforming the conductive particles, and the conductive metal within the base particle comes into contact with each other, forming a conductive path. In the conductive particle, a conductive path is formed not only on the surface (conductive portion) of the conductive particle, but also inside the conductive particle (conductive metal). As a result, even when the thickness of the conductive portion is relatively thin, the connection resistance between the upper and lower electrodes can be sufficiently reduced. Furthermore, in the conductive particle, when forming a conductive portion on the surface of the base particle, the conductive portion fills the fine voids within the base particle, effectively improving the adhesion of the conductive portion in the conductive particle and effectively suppressing peeling of the conductive portion in the conductive particle.

[0107] The particle diameter of the base particle is preferably 0.1 μm or more, more preferably 1 μm or more. The particle diameter of the base particle is preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 300 μm or less, even more preferably 50 μm or less, and even more preferably 10 μm or less. When the particle diameter of the base particle is above the lower limit, the contact area between the conductive particles and the electrode is increased, thereby further improving the electrical connection reliability between the electrodes and further reducing the connection resistance between the electrodes connected via the conductive particles. Furthermore, when forming a conductive portion on the surface of the base particle by electroless plating, it is possible to make it difficult for agglomerated conductive particles to be formed. When the particle diameter of the base particle is below the upper limit, the conductive particles are easily compressed sufficiently, further reducing the connection resistance between the electrodes and further reducing the gap between the electrodes.

[0108] The particle diameter of the base particles is particularly preferably 1 μm or more and 5 μm or less. When the particle diameter of the base particles is within the range of 1 μm or more and 5 μm or less, aggregation is unlikely to occur when forming the conductive portion on the surface of the base particles, and aggregated conductive particles are unlikely to be formed.

[0109] The particle size of the base particle refers to the diameter when the base particle is spherical, and when the base particle is other than spherical, it refers to the diameter when the base particle is assumed to be a perfect sphere with a volume equivalent to that of the base particle.

[0110] The particle diameter of the base particles indicates the number average particle diameter. The particle diameter of the base particles can be determined by observing 50 random base particles with an electron microscope or optical microscope and calculating the average particle diameter of each base particle, or by using a particle size distribution analyzer. When observed with an electron microscope or optical microscope, the particle diameter of each base particle is determined as the particle diameter in equivalent circle diameter. When observed with an electron microscope or optical microscope, the average particle diameter in equivalent circle diameter of 50 random base particles is approximately equal to the average particle diameter in equivalent sphere diameter. When observed with a particle size distribution analyzer, the particle diameter of each base particle is determined as the particle diameter in equivalent sphere diameter. The average particle diameter of the base particles is preferably calculated using a particle size distribution analyzer. When measuring the particle diameter of the base particles in the conductive particles, it can be measured, for example, as follows.

[0111] The conductive particles were added to Kulzer's Technovit 4000 to a content of 30% by weight and dispersed to prepare an embedding resin for conductive particle inspection. An ion milling machine (Hitachi High-Technologies Corporation's IM4000) was used to cut out a cross section of the conductive particles so that it passed through the center of the dispersed conductive particles in the embedding resin. Then, using a field emission scanning electron microscope (FE-SEM) with an image magnification set to 25,000x, 50 conductive particles were randomly selected and the substrate particles of each conductive particle were observed. The particle diameter of the substrate particles in each conductive particle was measured, and the arithmetic average was calculated to determine the particle diameter of the substrate particles.

[0112] (Conductive parts and conductive metals) The conductive particle according to the present invention comprises a base particle and a conductive portion disposed on the surface of the base particle. From the viewpoint of more effectively exerting the effects of the present invention, it is preferable that the base particle in the conductive particle according to the present invention contains a conductive metal inside the base particle. The conductive metal may form a linear conductive metal portion or a mesh-like conductive metal portion. It is preferable that the conductive portion contains a metal. The metal constituting the conductive portion is not particularly limited. The conductive metal is not particularly limited. The metal constituting the conductive portion and the conductive metal may be the same metal or different metals. It is preferable that the metal most abundant in the conductive portion and the metal most abundant in the conductive metal are the same.

[0113] Examples of the metal constituting the conductive portion and the conductive metal 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. Examples of the metal constituting the conductive portion and the conductive metal include tin-doped indium oxide (ITO) and solder. Only one type of metal constituting the conductive portion and one type of conductive metal may be used, or two or more types may be used in combination.

[0114] From the viewpoint of more effectively reducing the connection resistance between the electrodes, the conductive portion preferably contains nickel, gold, palladium, silver, or copper, and more preferably contains nickel, gold, or palladium.

[0115] The nickel content in 100% by weight of the nickel-containing conductive portion is preferably 10% by weight or more, more preferably 50% by weight or more, even more preferably 60% by weight or more, even more preferably 70% by weight or more, and particularly preferably 90% by weight or more. The nickel content in 100% by weight of the nickel-containing conductive portion may be 97% by weight or more, 97.5% by weight or more, 98% by weight or more, or 100% by weight or less.

[0116] In addition, hydroxyl groups often exist on the surface of the conductive part due to oxidation. Generally, hydroxyl groups exist on the surface of a conductive part made of nickel due to oxidation. An insulating substance can be arranged on the surface of such a conductive part (surface of a conductive particle) having hydroxyl groups via chemical bonding.

[0117] The conductive portion may be formed of one layer. The conductive portion may be formed of multiple layers. That is, the conductive portion may have a laminated structure of two or more layers. When the conductive portion is formed of multiple layers, the metal constituting the outermost layer is preferably gold, nickel, palladium, copper, or an alloy containing tin and silver, and more preferably gold. When the metal constituting the outermost layer is one of these preferred metals, the connection resistance between electrodes is further reduced. Furthermore, when the metal constituting the outermost layer is gold, corrosion resistance is further improved.

[0118] The method for forming the conductive portion on the surface of the base particle is not particularly limited. Examples of methods for forming the conductive portion include electroless plating, electroplating, physical collision, mechanochemical reaction, physical vapor deposition or physical adsorption, and coating the surface of the base particle with a metal powder or a paste containing a metal powder and a binder. The method for forming the conductive portion is preferably electroless plating, electroplating, or physical collision. Examples of physical vapor deposition methods include vacuum deposition, ion plating, and ion sputtering. Examples of physical collision methods include a Sheeter Composer (manufactured by Tokuju Manufacturing Co., Ltd.).

[0119] The method for incorporating a conductive metal into the base particle is not particularly limited. Examples of methods for incorporating a conductive metal into the base particle include electroless plating using porous base particles (base particle bodies) and electroplating using porous base particles (base particle bodies). Since porous base particles (base particle bodies) have a relatively large number of voids inside, when forming a conductive portion on the surface of the base particle, a conductive portion-forming material (plating solution, etc.) can be inserted into the fine voids inside the base particle. By precipitating the conductive metal from the conductive portion-forming material that has penetrated into the base particle, the conductive metal can be easily incorporated into the base particle. Examples of porous base particles include base particles that satisfy the preferred ranges of the BET specific surface area and porosity.

[0120] The thickness of the conductive portion is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, and preferably 50 nm or less, more preferably 45 nm or less, even more preferably 40 nm or less. The thickness of the conductive portion refers to the thickness of the entire conductive portion when the conductive portion is multilayered. When the thickness of the conductive portion is equal to or greater than the lower limit and equal to or less than the upper limit, the electrical conductivity reliability can be further improved, and the conductive particles can be sufficiently deformed during connection between electrodes without becoming too hard. The conductive particles according to the present invention can effectively improve electrical conductivity reliability even when the thickness of the conductive portion is 50 nm or less.

[0121] When the conductive portion is formed of multiple layers, the thickness of the conductive portion of the outermost layer is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, and preferably 50 nm or less, more preferably 45 nm or less, even more preferably 40 nm or less. When the thickness of the conductive portion of the outermost layer is equal to or greater than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, the coating by the conductive portion of the outermost layer becomes uniform, the corrosion resistance is sufficiently high, and the connection resistance between electrodes can be sufficiently low. Furthermore, when the metal constituting the outermost layer is gold, the thinner the thickness of the outermost layer, the lower the cost can be.

[0122] The thickness of the conductive portion can be measured by observing the cross section of the conductive particle using, for example, a transmission electron microscope (TEM). The thickness of the conductive portion is preferably calculated by averaging the thickness of five arbitrary conductive portions as the thickness of the conductive portion of one conductive particle, and more preferably by averaging the thickness of the entire conductive portion as the thickness of the conductive portion of one conductive particle. The thickness of the conductive portion is preferably determined by calculating the average thickness of the conductive portion of each of 10 arbitrary conductive particles.

[0123] The content of the conductive metal in 100% by volume of the conductive particles is preferably 5% by volume or more, more preferably 10% by volume or more, and preferably 70% by volume or less, more preferably 50% by volume or less. When the content of the conductive metal is above the above lower limit and below the above upper limit, the effects of the present invention can be more effectively exhibited. The content of the conductive metal in 100% by volume of the conductive particles is particularly preferably 10% by volume or more and 40% by volume or less. When the content of the conductive metal is within the range of 10% by volume or more and 40% by volume or less, the conduction reliability can be further improved. Note that the content of the conductive metal refers to the total content of the metal constituting the conductive portion and the conductive metal contained inside the base particle. Whether or not a conductive metal is contained inside the base particle is preferably determined by extracting a cross-section of the conductive particle using a focused ion beam and observing the cross-section using a transmission electron microscope (TEM).

[0124] The content of the conductive metal can be calculated as follows.

[0125] Conductive metal content (volume content) = D x M / Dmetal x 100 D: Specific gravity of conductive particles M: Metallization rate of conductive particles Dmetal: specific gravity of conductive metal

[0126] The metallization rate of the conductive particles can be calculated using ICP emission spectrometry, etc., and the specific gravity of the conductive particles can be measured using a true hydrometer, etc. Furthermore, the specific gravity of the conductive metal can be calculated using a value specific to the metal.

[0127] (protrusion) The conductive particles may or may not have protrusions on the outer surface of the conductive part. The conductive particles may or may not have protrusions on the conductive surface. The number of protrusions may be multiple. The conductive particles may have multiple protrusions. From the viewpoint of more effectively achieving the effects of the present invention, it is preferable that the conductive particles do not have protrusions on the outer surface of the conductive part. When the conductive particles do not have protrusions on the outer surface of the conductive part, unintended conduction is less likely to occur when the conductive particles are in contact with electrodes in the vertical direction (for example, when compressed by about 10% between second connection target members or between two electrodes). Even when the conductive particles do not have protrusions on the outer surface of the conductive part, good conduction can be achieved after conductive connection, and conduction reliability can be sufficiently increased.

[0128] (insulating material) The conductive particles may or may not include an insulating material disposed on the outer surface of the conductive portion. When conductive particles including an insulating material are used to connect electrodes, short circuits between adjacent electrodes can be more effectively prevented. Specifically, when multiple conductive particles come into contact with each other, the insulating material exists between the multiple electrodes, preventing short circuits between horizontally adjacent electrodes rather than between upper and lower electrodes. When connecting electrodes, applying pressure to the conductive particles with two electrodes can easily remove the insulating material between the conductive portion of the conductive particle and the electrode. Furthermore, when the conductive particles have protrusions on the outer surface of the conductive portion, the insulating material between the conductive portion of the conductive particle and the electrode can be more easily removed. However, since the conductive particles according to the present invention have the above-described configuration, insulation reliability can be improved without using an insulating material.

[0129] The insulating material is preferably insulating particles, since this allows the insulating material to be more easily removed when the electrodes are pressed together. The conductive particles according to the present invention do not necessarily have to include insulating particles.

[0130] Since the conductive particles according to the present invention have the above-described structure, even if the conductive particles do not have insulating particles on their outer surfaces, the insulating reliability can be sufficiently improved, and as a result, short circuits between adjacent electrodes can be prevented.

[0131] Examples of the insulating material include the above-mentioned resins and inorganic substances. The insulating material is preferably the above-mentioned resin. Only one type of insulating material may be used, or two or more types may be used in combination.

[0132] Examples of the inorganic materials include silica, alumina, barium titanate, zirconia, carbon black, silicate glass, borosilicate glass, lead glass, soda-lime glass, and alumina silicate glass.

[0133] Other examples of the insulating material include polyolefin compounds, (meth)acrylate polymers, (meth)acrylate copolymers, block polymers, thermoplastic resins, crosslinked thermoplastic resins, thermosetting resins, and water-soluble resins.

[0134] Examples of the polyolefin compound include polyethylene, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid ester copolymer. Examples of the (meth)acrylate polymer include polymethyl (meth)acrylate, polydodecyl (meth)acrylate, and polystearyl (meth)acrylate. Examples of the block polymer include polystyrene, styrene-acrylic acid ester copolymer, SB-type styrene-butadiene block copolymer, SBS-type styrene-butadiene block copolymer, and hydrogenated versions thereof. Examples of the thermoplastic resin include vinyl polymers and vinyl copolymers. Examples of the thermosetting resin include epoxy resin, phenolic resin, and melamine resin. Examples of the crosslinked thermoplastic resin include polyethylene glycol methacrylate, alkoxylated trimethylolpropane methacrylate, and alkoxylated pentaerythritol methacrylate. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide, and methylcellulose. A chain transfer agent may be used to adjust the degree of polymerization. Examples of the chain transfer agent include thiol and carbon tetrachloride.

[0135] Methods for disposing the insulating material on the surface of the conductive part include chemical methods and physical or mechanical methods. Examples of the chemical methods include interfacial polymerization, suspension polymerization in the presence of particles, and emulsion polymerization. Examples of the 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 conduction reliability when electrodes are electrically connected, the method for disposing the insulating material on the surface of the conductive part is preferably a physical method.

[0136] 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 may not be directly chemically bonded, but may be indirectly chemically bonded via a compound having a reactive functional group. After introducing a carboxyl group into the outer surface of the conductive part, the carboxyl group may be chemically bonded to the functional group on the outer surface of the insulating material via a polymer electrolyte such as polyethyleneimine.

[0137] When the insulating material is insulating particles, the particle diameter of the insulating particles can be appropriately selected depending on the particle diameter of the conductive particles and the application of the conductive particles. The particle diameter of the insulating particles 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, and 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 diameter of the insulating particles is above the lower limit, when the conductive particles are dispersed in the binder resin, the conductive portions of multiple conductive particles are less likely to contact each other. If the particle diameter of the insulating particles is below the upper limit, excessive pressure and high temperature heating are not required to remove the insulating particles between the electrodes and the conductive particles when connecting electrodes.

[0138] The particle diameter of the insulating particles is preferably an average particle diameter, and more preferably a number-average particle diameter. The particle diameter of the insulating particles can be determined by observing 50 random 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. When observed with an electron microscope or optical microscope, the particle diameter of each insulating particle is determined as the particle diameter in equivalent circle diameter. When observed with an electron microscope or optical microscope, the average particle diameter of 50 random insulating particles in equivalent circle diameter is approximately equal to the average particle diameter in equivalent sphere diameter. When observed with a particle size distribution analyzer, the particle diameter of each insulating particle is determined as the particle diameter in equivalent sphere diameter. The average particle diameter of the insulating particles is preferably calculated using a particle size distribution analyzer. When measuring the particle diameter of the insulating particles in the conductive particles, it can be measured, for example, as follows.

[0139] Conductive particles were added to Kulzer's Technovit 4000 to a content of 30% by weight and dispersed to prepare an embedding resin for conductive particle inspection. An ion milling machine (Hitachi High-Technologies Corporation's IM4000) was used to cut out a cross section of the conductive particles so that it passed through the center of the dispersed insulating particles in the embedding resin. Then, a field emission scanning electron microscope (FE-SEM) was used to set the image magnification to 50,000 times, randomly selecting 50 conductive particles and observing the insulating particles of each conductive particle. The particle diameter of the insulating particles in each conductive particle was measured, and the arithmetic average was used to determine the particle diameter of the insulating particles.

[0140] The ratio of the particle size of the conductive particles to the particle size of the insulating particles (particle size of conductive particles / particle size of insulating particles) is preferably 4 or more, more preferably 8 or more, and preferably 200 or less, more preferably 100 or less. When the ratio (particle size of conductive particles / particle size of insulating particles) is equal to or more than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited.

[0141] (Conductive materials) The conductive material according to the present invention includes the conductive particles described above and a binder resin. The conductive particles are preferably dispersed in the binder resin and used as a conductive material. The conductive material is preferably an anisotropic conductive material. The conductive material is preferably used for electrically connecting electrodes. The conductive material is preferably a circuit connecting material.

[0142] The binder resin is not particularly limited. Known insulating resins are used as the binder resin. The binder resin preferably contains a thermoplastic component (thermoplastic compound) or a curable component, and more preferably contains a curable component. Examples of the curable component include a photocurable component and a thermosetting component. The photocurable component preferably contains a photocurable compound and a photopolymerization initiator. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent. Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers. Only one type of the binder resin may be used, or two or more types may be used in combination.

[0143] Examples of the vinyl resin include vinyl acetate resin, acrylic resin, and styrene resin. Examples of the thermoplastic resin include polyolefin resin, ethylene-vinyl acetate copolymer, and polyamide resin. Examples of the curable resin include epoxy resin, urethane resin, polyimide resin, and unsaturated polyester resin. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin may be used in combination with a curing agent. Examples of the thermoplastic block copolymer include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, a hydrogenated product of styrene-butadiene-styrene block copolymer, and a hydrogenated product of styrene-isoprene-styrene block copolymer. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

[0144] In addition to the conductive particles and the binder resin, the conductive material may contain various additives such as fillers, extenders, softeners, plasticizers, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents, and flame retardants.

[0145] The conductive particles can be dispersed in the binder resin by a conventionally known dispersion method. Examples of the method for dispersing the conductive particles in the binder resin include the following: A method in which the conductive particles are added to the binder resin and then kneaded 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 resin, and then kneaded and dispersed using a planetary mixer or the like. A method in which the binder resin is diluted with water or an organic solvent or the like, then the conductive particles are added, and then kneaded and dispersed using a planetary mixer or the like.

[0146] The viscosity (η25) of the conductive material at 25°C is preferably 30 Pa·s or more, more preferably 50 Pa·s or more, and preferably 400 Pa·s or less, more preferably 300 Pa·s or less. When the viscosity of the conductive material at 25°C is equal to or greater than the lower limit and equal to or less than the upper limit, the connection reliability between electrodes can be more effectively improved. The viscosity (η25) can be adjusted appropriately by changing the types and amounts of the components.

[0147] The viscosity (η25) 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.

[0148] The conductive material can be used as a conductive paste, a conductive film, or the like. When the conductive material according to the present invention is a conductive film, a film not containing conductive particles may be laminated on a conductive film containing conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

[0149] The content of the binder resin in 100% by weight of the conductive material is preferably 10% by weight or more, more preferably 30% by weight or more, even more preferably 50% by weight or more, particularly preferably 70% by weight or more, and is preferably 99.99% by weight or less, more preferably 99.9% by weight or less. When the content of the binder resin is equal to or more than the lower limit and equal to or less than the upper limit, the conductive particles are efficiently arranged between the electrodes, and the connection reliability of the connection target members connected by the conductive material is further improved.

[0150] The content of the conductive particles in 100% by weight of the conductive material is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and is preferably 80% by weight or less, more preferably 60% by weight or less, even more preferably 40% by weight or less, even more preferably 20% by weight or less, and particularly preferably 10% by weight or less. When the content of the conductive particles is equal to or more than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited.

[0151] (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 connection part connecting the first connection target member and the second connection target member. In the connection structure according to the present invention, the connection part is formed from conductive particles or from a conductive material containing conductive particles and a binder resin, the conductive particles are the conductive particles described above, and the first electrode and the second electrode are electrically connected by the conductive particles.

[0152] The connection structure can be obtained through a step of arranging the conductive particles or the conductive material between the first connection target member and the second connection target member, and a step of electrically connecting the first and second connection target members by thermocompression bonding. If the conductive particles contain the insulating material, it is preferable that the insulating material be released from the conductive particles during the thermocompression bonding.

[0153] When the conductive particles are used alone, the connection portion itself is a conductive particle. That is, the first connection target member and the second connection target member are connected by the conductive particles. The conductive material used to obtain the connection structure is preferably an anisotropic conductive material.

[0154] FIG. 4 is a cross-sectional view showing an example of a connection structure using conductive particles according to the first embodiment of the present invention.

[0155] The connection structure 51 shown in Fig. 4 includes a first member to be connected 52, a second member to be connected 53, and a connection portion 54 connecting the first and second members to be connected 52, 53. The connection portion 54 is formed by curing a conductive material containing conductive particles 1. Note that in Fig. 4, the conductive particles 1 are shown schematically for the sake of convenience. Instead of the conductive particles 1, other conductive particles such as conductive particles 11 and 21 may be used.

[0156] The first connection target member 52 has a plurality of first electrodes 52a on its surface (upper surface). The second connection target member 53 has a plurality of second electrodes 53a on its surface (lower surface). The first electrodes 52a and the second electrodes 53a are electrically connected by one or more conductive particles 1. Therefore, the first and second connection target members 52 and 53 are electrically connected by the conductive particles 1.

[0157] The method for manufacturing the connection structure is not particularly limited. The method for manufacturing the connection structure preferably includes the following steps.

[0158] A first placement step of placing the above-mentioned conductive particles or a conductive material containing the above-mentioned conductive particles and a binder resin on the surface of a first connection target member having a first electrode on its surface.

[0159] a second placement step of placing a second connection target member having a second electrode on a surface of the conductive particles or conductive material opposite to the first connection target member side;

[0160] a thermocompression bonding step in which the laminate obtained in the second arrangement step is heated and pressed;

[0161] The pressure of the thermocompression bonding is preferably 40 MPa or more, more preferably 60 MPa or more, and preferably 90 MPa or less, more preferably 70 MPa or less. The heating temperature of the thermocompression bonding is preferably 80°C or more, more preferably 100°C or more, and preferably 140°C or less, more preferably 120°C or less. When the pressure and temperature of the thermocompression bonding are not less than the above lower limit and not more than the above upper limit, the effects of the present invention can be more effectively exhibited. Furthermore, when the conductive particles contain the insulating particles, the insulating particles can be easily detached from the surface of the conductive particles during conductive connection.

[0162] When the conductive particles contain insulating particles, the insulating particles present between the conductive particles and the first and second electrodes can be removed when the laminate is heated and pressurized. For example, during the heating and pressurization, the insulating particles present between the conductive particles and the first and second electrodes are easily detached from the surfaces of the conductive particles. During the heating and pressurization, some of the insulating particles may detach from the surfaces of the conductive particles, partially exposing the surfaces of the conductive portions. The exposed surfaces of the conductive portions may contact the first and second electrodes, thereby electrically connecting the first and second electrodes via the conductive particles.

[0163] The first and second connection target members are not particularly limited. Specific examples of the first and second connection target members 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 boards, glass epoxy boards, and glass boards. The first and second connection target members are preferably electronic components.

[0164] Examples of the electrode provided on the connection target member include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. When the connection target member is a flexible printed circuit board, the electrode is preferably a gold electrode, nickel electrode, tin electrode, silver electrode, or copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, copper electrode, molybdenum electrode, silver electrode, or tungsten electrode. When the electrode is an aluminum electrode, it may be an electrode made of aluminum alone, or an electrode 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.

[0165] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0166] The following materials were prepared:

[0167] Base particles (porous resin particles, used as the base particle body): Base material particle A (particle diameter 4μm, BET specific surface area 550m 2 / g, prepared according to Synthesis Example 1 below) Base material particle B (particle diameter 4μm, BET specific surface area 335m 2 / g, prepared according to Synthesis Example 2 below) Base material particle C (particle diameter 4μm, BET specific surface area 156m 2 / g, prepared according to Synthesis Example 3 below) Base particles (non-porous resin particles): Base material particle D (particle diameter 4μm, BET specific surface area 3m 2 / g, Sekisui Chemical Co., Ltd. "SP-204")

[0168] (Synthesis Example 1) Polystyrene particles with an average particle size of 0.79 μm were prepared as seed particles. 3.9 parts by weight of the polystyrene particles, 500 parts by weight of ion-exchanged water, and 120 parts by weight of a 5 wt% aqueous polyvinyl alcohol solution were mixed to prepare a mixed solution. The mixed solution was dispersed using ultrasonic waves, then placed in a separable flask and stirred uniformly.

[0169] Next, 150 parts by weight of divinylbenzene (monomer component), 2 parts by weight of 2,2'-azobis(methyl isobutyrate) ("V-601" manufactured by Wako Pure Chemical Industries, Ltd.), and 2 parts by weight of benzoyl peroxide ("Niper BW" manufactured by NOF Corporation) were mixed together. 9 parts by weight of triethanolamine lauryl sulfate, 50 parts by weight of toluene (solvent), and 1100 parts by weight of ion-exchanged water were then added to prepare an emulsion.

[0170] The above emulsion was added in several portions to the above mixture in the separable flask, and the mixture was stirred for 12 hours to allow the seed particles to absorb the monomer, thereby obtaining a suspension containing seed particles swollen with the monomer.

[0171] Thereafter, 490 parts by weight of a 5% by weight aqueous solution of polyvinyl alcohol was added, and heating was started to carry out a reaction at 85° C. for 9 hours, whereby base particles A were obtained.

[0172] (Synthesis Example 2) Base particle B was obtained in the same manner as base particle A, except that the amount of toluene (solvent) used was changed to 35 parts by weight.

[0173] (Synthesis Example 3) Base particles C were obtained in the same manner as base particles A, except that the amount of toluene (solvent) used was changed to 25 parts by weight.

[0174] Example 1 (1) Preparation of conductive particles After washing and drying the base particles, 10 parts by weight of the base particles were dispersed in 250 parts by weight of an alkaline solution containing 5% by weight of palladium catalyst solution using an ultrasonic disperser, and the solution was filtered to extract the base particles. The base particles were then added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surface of the base particles. The surface-activated base particles were thoroughly washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain a dispersion.

[0175] Also, a nickel plating solution (pH 8.5) containing 0.35 mol / L of nickel sulfate, 1.38 mol / L of dimethylamine borane, and 0.5 mol / L of sodium citrate was prepared.

[0176] While stirring the resulting dispersion at 60°C, 200 parts by weight of the nickel plating solution was gradually added dropwise to the dispersion to perform electroless nickel plating. The dispersion was then filtered to remove the particles, which were then washed with water and dried to form a nickel-boron conductive layer on the surface of the base particles, thereby obtaining conductive particles having conductive portions on their surfaces.

[0177] (2) Preparation of conductive material (anisotropic conductive paste) Seven parts by weight of the obtained conductive particles, 25 parts by weight of bisphenol A-type phenoxy resin, 4 parts by weight of fluorene-type epoxy resin, 30 parts by weight of phenol novolac-type epoxy resin, and SI-60L (manufactured by Sanshin Chemical Industry Co., Ltd.) were mixed together, and the mixture was degassed and stirred for 3 minutes to obtain a conductive material (anisotropic conductive paste).

[0178] (3) Fabrication of connection structure A transparent glass substrate was prepared, on the top surface of which was formed an IZO electrode pattern (first electrode, Vickers hardness of the metal on the electrode surface: 100 Hv) with an L / S of 10 μm / 10 μm. A semiconductor chip was also prepared, on the bottom surface of which was formed an Au electrode pattern (second electrode, Vickers hardness of the metal on the electrode surface: 50 Hv) with an L / S of 10 μm / 10 μm. The resulting anisotropic conductive paste was applied to a thickness of 30 μm on the transparent glass substrate to form an anisotropic conductive paste layer. Next, the semiconductor chip was stacked on the anisotropic conductive paste layer with the electrodes facing each other. Next, a magnetization process was performed from above the electrodes. A pressure heating head was then placed on the top surface of the semiconductor chip, while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer was 100°C. A pressure of 85 MPa was applied, and the anisotropic conductive paste layer was cured at 100°C, resulting in a connection structure.

[0179] Example 2 Conductive particles, a conductive material (anisotropic conductive paste), and a connection structure were obtained in the same manner as in Example 1, except that the amount of alkaline solution containing 5% by weight of palladium catalyst solution was changed to 500 parts by weight.

[0180] Example 3 Conductive particles, a conductive material (anisotropic conductive paste), and a connection structure were obtained in the same manner as in Example 1, except that the amount of alkaline solution containing 5% by weight of palladium catalyst solution was changed to 1000 parts by weight.

[0181] Example 4 Conductive particles, a conductive material (anisotropic conductive paste), and a connection structure were obtained in the same manner as in Example 1, except that base particles B were used.

[0182] Example 5 Conductive particles, a conductive material (anisotropic conductive paste), and a connection structure were obtained in the same manner as in Example 1, except that base particles B were used and the amount of alkaline solution containing 5% by weight of palladium catalyst solution was changed to 500 parts by weight.

[0183] Example 6 Conductive particles, a conductive material (anisotropic conductive paste), and a connection structure were obtained in the same manner as in Example 1, except that base particle B was used and the amount of alkaline solution containing 5 wt% palladium catalyst solution was changed to 1,000 parts by weight.

[0184] Example 7 Conductive particles, a conductive material (anisotropic conductive paste), and a connection structure were obtained in the same manner as in Example 1, except that base particle C was used.

[0185] Example 8 Conductive particles, a conductive material (anisotropic conductive paste), and a connection structure were obtained in the same manner as in Example 1, except that base particle C was used and the amount of alkaline solution containing 5% by weight of palladium catalyst solution was changed to 500 parts by weight.

[0186] Example 9 Conductive particles, a conductive material (anisotropic conductive paste), and a connection structure were obtained in the same manner as in Example 1, except that base particle C was used and the amount of alkaline solution containing 5 wt% palladium catalyst solution was changed to 1,000 parts by weight.

[0187] Example 10 A dispersion liquid was obtained in the same manner as in Example 1, except that base particles C were used. Next, 1 g of nickel particle slurry (average particle diameter 100 nm) was added to the dispersion liquid over 3 minutes to obtain a suspension containing base particles C to which core materials were attached. Thereafter, electroless nickel plating was performed on the suspension in the same manner as in Example 1 to obtain conductive particles, a conductive material (anisotropic conductive paste), and a connection structure.

[0188] Example 11 The following monomer composition was placed in a 1000 mL separable flask equipped with a four-neck separable cover, stirring blade, three-way stopcock, condenser, and temperature probe. Ion-exchanged water was then weighed out to give a solids content of 5% by weight of the monomer composition. The mixture was stirred at 200 rpm and polymerized at 70°C under a nitrogen atmosphere for 24 hours. The monomer composition contained 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. After the reaction was complete, the mixture was freeze-dried to yield insulating particles with ammonium groups on their surfaces, an average particle size of 220 nm, and a CV value of 10%.

[0189] The insulating particles were dispersed in ion-exchanged water under ultrasonic irradiation to obtain a 10 wt % aqueous dispersion of the insulating particles.

[0190] 10 g of the conductive particles obtained in Example 10 were dispersed in 500 mL of ion-exchanged water, 4 g of an aqueous dispersion of insulating particles was added, and the mixture was stirred at room temperature for 6 hours. After filtering through a 3 μm mesh filter, the mixture was washed with methanol and dried to obtain conductive particles with insulating particles attached thereto (conductive particles with insulating particles).

[0191] Observation with a scanning electron microscope (SEM) revealed that only one insulating particle coating layer was formed on the surface of the conductive particle. Image analysis was used to calculate the area covered by the insulating particles (i.e., the projected area of ​​the insulating particle diameter) relative to an area of ​​2.5 μm from the center of the conductive particle, and the coverage rate was found to be 40%.

[0192] A conductive material (anisotropic conductive paste) and a connection structure were obtained in the same manner as in Example 1, except that the obtained conductive particles (conductive particles with insulating particles) were used.

[0193] (Comparative Example 1) A dispersion liquid was obtained in the same manner as in Example 1, except that base particles D were used. Next, 1 g of nickel particle slurry (average particle diameter 100 nm) was added to the dispersion liquid over 3 minutes to obtain a suspension containing base particles D to which a core substance was attached. Thereafter, conductive particles, a conductive material (anisotropic conductive paste), and a connection structure were obtained in the same manner as in Example 1, except that the amount of nickel plating solution used was changed to 300 parts by weight.

[0194] (Comparative Example 2) Conductive particles with insulating particles attached thereto (conductive particles with insulating particles) were obtained in the same manner as in Example 11, except that base particle D was used. Furthermore, when observed with a scanning electron microscope (SEM), it was found that only one coating layer of insulating particles was formed on the surface of the conductive particle. When the coverage area of ​​the insulating particles (i.e., the projected area of ​​the particle diameter of the insulating particles) relative to an area of ​​2.5 μm from the center of the conductive particle was calculated by image analysis, the coverage rate was 40%.

[0195] A conductive material (anisotropic conductive paste) and a connection structure were obtained in the same manner as in Example 1, except that the obtained conductive particles (conductive particles with insulating particles) were used.

[0196] (Comparative Example 3) To the dispersion liquid obtained in Example 1, 1 g of nickel particle slurry (average particle diameter 100 nm) was added over 3 minutes to obtain a suspension containing base particles A to which a core substance was attached. Conductive particles, a conductive material (anisotropic conductive paste), and a connection structure were obtained in the same manner as in Example 1, except that the amount of nickel plating solution used was changed to 300 parts by weight.

[0197] (evaluation) (1) Voltage change rate when conductive particles are compressed Using a microcompression tester for resistance measurement ("ENT-NEXUS" manufactured by Elionix), one conductive particle was compressed with a cylindrical (50 μm diameter, BeAu) smooth indenter tip at 25°C, a compression rate of 0.3 mN / s, and a maximum test load of 40 mN. The voltage of the conductive particle before compression, the voltage at 10%, 20%, 30%, 40%, and 50% compression were measured. The voltage of the conductive particle was calculated by arithmetically averaging the voltages of 50 randomly selected conductive particles. From the measured voltages, the voltage change rates at 10% compression (D10), 20% compression (D20), 30% compression (D30), 40% compression (D40), and 50% compression (D50) were calculated using the method described above. The ratio (D10 / D20) of the voltage change rate when the conductive particles were compressed 10% to the voltage change rate (D20) when the conductive particles were compressed 20% was calculated. The ratio (D10 / D30) of the voltage change rate when the conductive particles were compressed 10% to the voltage change rate (D30) when the conductive particles were compressed 30% was calculated. The ratio (D10 / D40) of the voltage change rate when the conductive particles were compressed 10% to the voltage change rate (D40) when the conductive particles were compressed 40% was calculated. The ratio (D10 / D50) of the voltage change rate when the conductive particles were compressed 10% to the voltage change rate (D50) when the conductive particles were compressed 50% was calculated.

[0198] (2) Conduction reliability The connection resistance A between the upper and lower electrodes of the 20 connection structures obtained was measured using the four-terminal method. Note that, based on the relationship voltage = current × resistance, the connection resistance can be determined by measuring the voltage when a constant current is passed. The conductivity reliability was evaluated according to the following criteria.

[0199] [Conductivity reliability criteria] ○○: Connection resistance A is 5Ω or less ○: Connection resistance A is over 5Ω and 10Ω or less ×: Connection resistance A is over 10Ω and 20Ω or less ××: Connection resistance A exceeds 20 Ω

[0200] (3) Insulation reliability (occurrence rate of short circuits) The 20 connection structures thus obtained were checked for the presence or absence of leakage between adjacent electrodes by measuring the resistance value with a tester. 8 The rate of short circuit occurrence was determined as the percentage of connection structures with a resistance of 0.1Ω or less. The insulation reliability was evaluated according to the following criteria.

[0201] [Insulation reliability (short circuit occurrence rate) criteria] ○○: Short circuit occurrence rate is 5% or less ○: The incidence of short circuits is over 5% and 10% or less ×: The incidence of short circuits is more than 10% and less than 20% ××: Short circuit occurrence rate exceeds 20%

[0202] The results are shown in Tables 1 to 4 below.

[0203] [Table 1]

[0204] [Table 2]

[0205] [Table 3]

[0206] [Table 4]

[0207] The cross-sections of the obtained conductive particles were extracted using a focused ion beam and observed using a transmission electron microscope (TEM). In the conductive particles obtained in Examples 1 to 11 and Comparative Example 3, a conductive metal derived from the material of the conductive portion was contained inside the base particle. On the other hand, in the conductive particles obtained in Comparative Examples 1 and 2, a conductive metal derived from the material of the conductive portion was not contained inside the base particle. [Explanation of symbols]

[0208] 1...Conductive particles 2...Base material particles 3...Conductive part 11...Conductive particles 11a...Protrusion 12...Conductive part 12a...Protrusion 13…core substance 14...Insulating material 21...Conductive particles 21a...Protrusion 22...Conductive part 22a...protrusion 22A...First conductive part 22Aa…Protrusion 22B...Second conductive part 22Ba...Protrusion 51...Connection structure 52...First connection target member 52a...first electrode 53...Second connecting member 53a...second electrode 54...Connection

Claims

1. A conductive particle includes a base particle and a conductive portion disposed on a surface of the base particle, The conductive portion has a thickness of 50 nm or less, The BET specific surface area of ​​the conductive particles is 15 m 2 / g or more; The conductive particles satisfy at least one of the following structures A, B, C, and D: In the measurement of the voltage change rate described below, the conductive particles are compressed by 10%, 20%, 30%, 40%, or 50% using an "ENT-NEXUS" compression tester manufactured by Elionix under conditions of 25°C, a compression speed of 0.3 mN / sec, and a maximum test load of 40 mN, and the voltage is measured at 25°C in a state where the conductive particles are compressed by 10%, 20%, 30%, 40%, or 50%. Configuration A: The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 20% is 0.12 or less. Configuration B: The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 30% is 0.08 or less. Configuration C: The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 40% is 0.08 or less. Configuration D: The ratio of the voltage change rate when the conductive particles are compressed by 10% to the voltage change rate when the conductive particles are compressed by 50% is 0.08 or less.

2. The conductive particles according to claim 1 , which satisfy the composition B.

3. A conductive particle as described in claim 2, wherein the voltage change rate when the conductive particle is compressed by 30% is 60% or more.

4. The conductive particle according to any one of claims 1 to 3, wherein the base particle contains a conductive metal inside the base particle.

5. The conductive particle according to any one of claims 1 to 4, wherein the base particle is a resin particle.

6. The conductive particle according to any one of claims 1 to 5, wherein the base particle is a porous particle.

7. The conductive particle according to any one of claims 1 to 6, wherein the conductive portion has no protrusions on its outer surface.

8. The conductive particle according to any one of claims 1 to 7, comprising an insulating material disposed on an outer surface of the conductive portion.

9. The conductive particles according to any one of claims 1 to 8, wherein the particle diameter of the conductive particles is 0.1 µm or more and 1000 µm or less.

10. The conductive particles according to any one of claims 1 to 9, and a binder resin.

11. a first connection target member having a first electrode on a surface thereof; a second connection target member having a second electrode on its surface; a connection portion connecting the first connection target member and the second connection target member, the connecting portion is formed of conductive particles or a conductive material containing conductive particles and a binder resin, The conductive particles are the conductive particles according to any one of claims 1 to 9, A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.

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