Conductive particles, method for manufacturing conductive particles, conductive material, and connection structure

Abstract

The present invention provides a conductive particle that can effectively improve the conduction reliability between electrodes and can effectively prevent the cracking of a conductive portion due to external impact. The conductive particle of the present invention includes: a base material particle, a first conductive portion provided on the surface of the base material particle, and a second conductive portion provided on the outer surface of the first conductive portion. When observing the outer surface of the second conductive portion using an electron microscope, there are no pinholes having a size of 50 nm or more in the maximum length direction, or there is 1 pinhole / μm 2 or less having a size of 50 nm or more in the maximum length direction.

Description

[0001] This application is a divisional application of a patent application with Chinese Application No. 201880030129.3, invention title "Conductive Particles, Method for Manufacturing Conductive Particles, Conductive Material, and Connection Structure", and the filing date of June 21, 2018. Technical Field

[0002] The present invention relates to conductive particles, for example, used for electrically connecting between electrodes. In addition, the present invention relates to a method for manufacturing the conductive particles, a conductive material using the conductive particles, and a connection structure. Background Art

[0003] Anisotropic conductive materials such as anisotropic conductive pastes and anisotropic conductive films are well-known. In this anisotropic conductive material, conductive particles are dispersed in a binder resin. In addition, as the conductive particles, conductive particles having a surface of a conductive layer subjected to an insulating treatment can be used.

[0004] The anisotropic conductive material is used to obtain various connection structures. As connections through the anisotropic conductive material, for example, connections such as a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), a semiconductor chip and a glass substrate (COG (Chip on Glass)), and a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)) can be cited.

[0005] As an example of the conductive particles, Patent Document 1 below discloses conductive particles including base particles and a conductive metal layer covering the surface of the base particles. The base particles are polymer particles having a glass transition temperature (Tg) of 50°C or higher and 100°C or lower. The thickness of the conductive metal layer is 0.01 μm to 0.15 μm.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-064559 Summary of the Invention

[0009] Technical Problem to be Solved by the Invention

[0010] In recent years, with the development of various electronic devices, substrate materials have also become diversified. For example, curved panels, flexible panels that can be freely bent, etc. have been developed. Since the curved panels etc. require flexibility, discussions are underway to use plastic substrates such as polyimide substrates as flexible components for curved panels etc. instead of conventional glass substrates.

[0011] When directly mounting a semiconductor chip etc. on a plastic substrate, since the plastic substrate is liable to be deformed or cracked due to the temperature or pressure during mounting, it is necessary to make the temperature or pressure during mounting as low as possible. If the temperature or pressure during mounting is lowered, the conductive particles cannot be sufficiently deformed when making a conductive connection between the electrodes. As a result, it may be difficult to sufficiently ensure the contact area between the conductive particles and the electrodes. In addition, the force that causes the compressed conductive particles to return to their original shape may act, and a phenomenon called rebound may occur. When rebound occurs, it is sometimes difficult to maintain a sufficient contact area between the conductive particles and the electrodes. As a result, the conduction reliability between the electrodes sometimes decreases.

[0012] In addition, by using the conventional conductive particles described in Patent Document 1, high connection reliability can be exhibited to some extent even when the temperature or pressure during mounting is low. However, since the base particles are relatively soft, the conductive metal layer of the conductive particles is liable to be cracked (the conductive part is cracked) due to external impact. For conventional conductive particles, it is difficult to prevent the cracking of the conductive part due to external impact.

[0013] An object of the present invention is to provide conductive particles that can effectively improve the conduction reliability between electrodes and can effectively prevent the cracking of the conductive part due to external impact. In addition, the present invention provides a manufacturing method using the conductive particles, a conductive material using the conductive particles, and a connection structure.

[0014] Technical means for solving the technical problem

[0015] According to a broad aspect of the present invention, there is provided a conductive particle including: base particles, a first conductive part provided on the surface of the base particles, and a second conductive part provided on the outer surface of the first conductive part. When observing the outer surface of the second conductive part using an electron microscope, there are no pinholes having a size of 50 nm or more in the maximum length direction, or there is 1 / μm 2 or less of pinholes having a size of 50 nm or more in the maximum length direction.

[0016] According to a broad aspect of the present invention, there is provided a conductive particle comprising: a base particle, a first conductive portion provided on the surface of the base particle, and a second conductive portion provided on the outer surface of the first conductive portion. When observing the outer surface of the second conductive portion using an electron microscope, there are no pinholes with a size of 50 nm or more in the maximum length direction, or there is 1 pinhole per μm 2 or less of pinholes having a size of 50 nm or more and 200 nm or less in the maximum length direction as follows.

[0017] According to a specific aspect of the conductive particle according to the present invention, the conductive particle satisfies the following formula (1) and has a compression recovery rate of 10% or less at 25°C,

[0018] A ≤ 5500 - B × 100… Formula (1)

[0019] In the formula (1), A is the 10% K value (N / mm 2 ) of the conductive particle, and B is the average particle diameter (μm) of the conductive particle.

[0020] According to a specific aspect of the conductive particle of the present invention, its average particle diameter is 3 μm or more and 30 μm or less.

[0021] According to a specific aspect of the conductive particle of the present invention, the second conductive portion includes gold, silver, palladium, platinum, copper, cobalt, ruthenium, indium, or tin.

[0022] According to a specific aspect of the conductive particle of the present invention, the ionization tendency of the metal contained in the first conductive portion is greater than the ionization tendency of the metal contained in the second conductive portion.

[0023] According to a specific aspect of the conductive particle according to the present invention, the first conductive portion contains nickel and phosphorus.

[0024] According to a specific aspect of the conductive particle of the present invention, in the thickness direction of the first conductive portion, the phosphorus content on the second conductive portion side in the first conductive portion is greater than the phosphorus content on the base particle side in the first conductive portion.

[0025] According to a broad aspect of the present invention, there is provided a method for manufacturing a conductive particle, which includes the following steps: using a conductive particle having a base particle and a first conductive portion provided on the surface of the base particle, and applying a plating treatment on the outer surface of the first conductive portion to provide a second conductive portion. In this step, the second conductive portion is formed so that when observing the outer surface of the second conductive portion using an electron microscope, there are no pinholes with a size of 50 nm or more in the maximum length direction, or there is 1 pinhole per μm 2A pinhole having a size of 50 nm or more in the maximum length direction as described below.

[0026] According to a broad aspect of the present invention, there is provided a conductive material comprising: the conductive particles and a binder resin.

[0027] According to a broad aspect of the present invention, there is provided a connection structure including: a first connection object member having a first electrode on its surface, a second connection object member having a second electrode on its surface, and a connection portion connecting the first connection object member and the second connection object member together, wherein the material of the connection portion is the conductive particles or a conductive material containing the conductive particles and a binder resin, and the first electrode and the second electrode are electrically connected through the conductive particles.

[0028] Advantages of the Invention

[0029] A conductive particle of the present invention includes: a base particle, a first conductive portion provided on the surface of the base particle, and a second conductive portion provided on the outer surface of the first conductive portion. When observing the outer surface of the second conductive portion using an electron microscope, there are no pinholes having a size of 50 nm or more in the maximum length direction, or there is 1 per μm 2 A pinhole having a size of 50 nm or more and 200 nm or less in the maximum length direction as described below. Due to the above technical features, the conductive particles of the present invention can effectively improve the conduction reliability between electrodes and effectively prevent the rupture of the conductive portion caused by external impact.

[0030] A conductive particle of the present invention includes: a base particle, a first conductive portion provided on the surface of the base particle, and a second conductive portion provided on the outer surface of the first conductive portion. When observing the outer surface of the second conductive portion using an electron microscope, there are no pinholes having a size of 50 nm or more in the maximum length direction, or there is 1 per μm 2 A pinhole having a size of 50 nm or more and 200 nm or less in the maximum length direction as described below. Due to the above structural and technical features, the manufacturing method of the conductive particles of the present invention can effectively improve the conduction reliability between electrodes and can effectively prevent the rupture of the conductive portion caused by external impact.

[0031] The manufacturing method of the conductive particles of the present invention includes the following steps: using conductive particles having a base particle and a first conductive portion provided on the surface of the base particle, and performing a plating process on the outer surface of the first conductive portion to provide a second conductive portion, wherein the second conductive portion is formed such that when observing the outer surface of the second conductive portion using an electron microscope, there are no pinholes having a size of 50 nm or more in the maximum length direction, or there is 1 per μm2 A pinhole having a size of 50 nm or more in the maximum length direction as described below. In the method for manufacturing the conductive particles of the present invention, due to the above-described technical features, the conduction reliability between electrodes can be effectively improved, and the breakage of the conductive portion due to external impact can be effectively prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a cross-sectional view showing the conductive particles of the first embodiment of the present invention;

[0033] Figure 2 is a cross-sectional view showing the conductive particles of the second embodiment of the present invention;

[0034] Figure 3 is a cross-sectional view schematically showing a connection structure using the conductive particles of the first embodiment of the present invention;

[0035] Figure 4 is a view showing an image of the surface of the conductive particles manufactured in Example 1;

[0036] Figure 5 is a view showing an image of the surface of the conductive particles manufactured in Comparative Example 1; DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, the specific embodiments of the present invention will be described in detail.

[0038] (Conductive Particles)

[0039] A conductive particle of the present invention includes: a base particle; a first conductive portion provided on the surface of the base particle; and a second conductive portion provided on the outer surface of the first conductive portion. In the conductive particle of the present invention, when observing the outer surface of the second conductive portion using an electron microscope, preferably, there is no pinhole having a size of 50 nm or more in the maximum length direction, or there is 1 pinhole / μm 2 or less of the following pinholes having a size of 50 nm or more in the maximum length direction. In this case, in the conductive particle of the present invention, when there is such a pinhole, the number of the pinholes per 1 μm 2 is calculated to be 1 or less. In the conductive particle of the present invention, the maximum length in the length direction of the calculated pinhole is 50 nm or more. In this case, in the conductive particle of the present invention, when there is such a pinhole, the number of the pinholes per 1 μm 2 is calculated to be 1 or less. Regarding the conductive particle of the present invention, the size in the maximum length direction of the calculated pinhole is 50 nm or more.

[0040] Regarding the conductive particles of the present invention, when observing the outer surface of the second conductive portion with an electron microscope, it is preferable that there are no pinholes with a size of 50 nm or more in the maximum length direction, or there is 1 pinhole per μm 2 or less, and the size of the pinhole in the maximum length direction is 50 nm or more and 200 nm or less. In this case, regarding the conductive particles of the present invention, the number of the pinholes per 1 μm 2 is calculated to be 1 or less. Regarding the conductive particles of the present invention, the size of the calculated pinhole in the maximum length direction is 50 nm or more and 200 nm or less.

[0041] Since the present invention has the above technical features, it can effectively improve the conduction reliability between electrodes and effectively prevent the rupture of the conductive portion due to external impact.

[0042] Even under the conditions of low temperature and pressure during installation, it is necessary to use conductive particles with relatively soft base particles to obtain a connection structure with high connection reliability. However, for conductive particles with relatively soft base particles, the conductive portion is prone to rupture due to external impact. The inventors of the present invention have deeply discussed suppressing the rupture of the conductive portion due to external impact, and as a result, it has been found that the rupture of the conductive portion caused by external impact is caused by pinholes generated in the displacement gold plating treatment for forming the conductive portion of the conductive particles. The inventors of the present invention have found that in the case of using conductive particles with relatively soft base particles, the rupture of the conductive portion caused by external impact starts from the pinholes. Since the present invention has the above technical features, it can effectively prevent the rupture of the conductive portion due to external impact.

[0043] For example, the pinholes are formed when nickel is dissolved in ionic form on the surface of the first conductive portion formed by nickel plating and the second conductive portion is formed by displacement gold plating. For example, when the metal in the first conductive portion is dissolved, the missing portion of the first conductive portion is a pinhole.

[0044] In the conductive particles of the present invention, when observing the outer surface of the second conductive portion with an electron microscope, it is preferable that there are no pinholes with a size of 50 nm or more in the maximum length direction.

[0045] In the conductive particles of the present invention, when observing the outer surface of the second conductive portion with an electron microscope, if there are the pinholes, there are 1 pinhole per μm 2 or less, and the size of the pinhole in the maximum length direction is 50 nm or more. When observing the outer surface of the second conductive portion with an electron microscope, it is preferable that there is 1 pinhole per μm 2A pinhole having a size of 50 nm or more in the maximum length direction below. When the number of the pinholes is within the preferred range, the conduction reliability between electrodes can be further effectively improved, and the breakage of the conductive part due to external impact can be further effectively prevented.

[0046] Regarding the conductive particles of the present invention, when observing the outer surface of the second conductive part using an electron microscope, it is preferred that there are no pinholes having a size of 50 nm or more and 200 nm or less in the maximum length direction.

[0047] For the conductive particles of the present invention, when there are such pinholes when observing the outer surface of the second conductive part using an electron microscope, there is 1 per μm 2 A pinhole having a size of 50 nm or more and 200 nm or less in the maximum length direction below. From the viewpoint of further effectively improving the conduction reliability between electrodes and from the viewpoint of further effectively preventing the breakage of the conductive part caused by external impact, the size in the maximum length direction of the pinhole having a size of 50 nm or more in the maximum length direction is preferably 150 nm or less, more preferably 100 nm or less. When observing the outer surface of the second conductive part using an electron microscope, it is preferred that the number of pinholes having a size of 50 nm or more and 200 nm or less in the maximum length direction is present at 0.1 per μm 2 Below. When the number of the pinholes is within the preferred range, the conduction reliability between electrodes can be further effectively improved, and the breakage of the conductive part caused by external impact can be further effectively prevented.

[0048] Regarding the presence or absence of the pinholes, for example, it can be confirmed by observing arbitrary conductive particles using an electron microscope. Specifically, in a part other than the part 0.5 μm inward from the outer periphery of arbitrary conductive particles, it can be determined by observing five arbitrary positions using an electron microscope, and it can be confirmed whether there are the pinholes.

[0049] For example, the size in the maximum length direction of the pinholes can be calculated by observing arbitrary conductive particles using an electron microscope. The size in the maximum length direction of the pinholes is the distance obtained by connecting two points on the outer periphery of the pinhole into a straight line, and is the maximum size of the distance obtained by connecting two points on the outer periphery of the pinhole into a straight line.

[0050] The shape of the pinholes is not particularly limited. The shape of the pinholes can be circular or a shape other than circular. When the shape of the pinholes is circular, the size in the maximum length direction of the pinholes corresponds to the maximum diameter.

[0051] Generally, when forming a conductive portion by electroless plating or the like, minute regions where the conductive portion is not formed may be formed. The maximum lengthwise dimension of these regions is usually less than 50 nm. In the present invention, these small regions are not included in the pinholes.

[0052] From the viewpoint of further effectively improving the conduction reliability between electrodes, the conductive particles preferably satisfy the relationship of the following formula (1).

[0053] A ≤ 5500 - B × 100 … Formula (1)

[0054] In the formula (1), A is the 10% K value (N / mm 2 ) of the conductive particles, and B is the average particle diameter (μm) of the conductive particles.

[0055] From the viewpoint of further improving the conduction reliability between electrodes, the 10% K value of the conductive particles is preferably 500 N / mm 2 or more, more preferably 1000 N / mm 2 or more, and preferably 4500 N / mm 2 or less, more preferably 4000 N / mm 2 or less.

[0056] The 10% K value (compression modulus when the conductive particles are compressed by 10%) of the conductive particles can be measured as follows.

[0057] Using a micro compression tester, under the conditions of a pressure speed of 0.33 mN / s and a maximum test load of 20 mN, a conductive particle is compressed with the smooth end face of a cylinder (diameter 100 μm, made of diamond). The load value (N) and the compression displacement (mm) at this time are measured. Based on the obtained measurement values, the 10% K value (10% compression modulus) at 25°C can be determined by the following equation. As the micro compression tester, for example, "Micro Compression Tester MCT-W200" manufactured by Shimadzu Corporation, "Fisher Scope H-100" manufactured by Fisher Company, etc. can be used. The 10% K value of the conductive particles at 25°C is preferably calculated by averaging the 10% K values of 50 randomly selected conductive particles at 25°C.

[0058] 10% K value (N / mm 2 ) = (3 / 2 1 / 2 ) · F · S -3 / 2 · R -1 / 2

[0059] F: Load value (N) when the conductive particles are compressed and deformed by 10%

[0060] S: Compression displacement (mm) when the conductive particles are compressed and deformed by 10%

[0061] R: Radius of the conductive particles (mm)

[0062] The K value generally and quantitatively represents the hardness of the conductive particles. By using the K value, the hardness of the conductive particles can be quantitatively and uniquely represented.

[0063] From the viewpoint of further improving the conduction reliability between electrodes, the compression recovery rate of the conductive particles at 25°C is preferably 10% or less, more preferably 8% or less. There is no particular limitation on the lower limit of the compression recovery rate of the conductive particles at 25°C. The compression recovery rate of the conductive particles at 25°C can be 3% or more.

[0064] The compression recovery rate of the conductive particles at 25°C can be measured as follows.

[0065] Disperse the conductive particles on the sample stage. For one dispersed conductive particle, using a micro-compression tester, at 25°C, with the smooth end face of a cylindrical indenter (diameter 100 μm, made of diamond), along the central direction of the conductive particle, when the particle size is 10 μm or more, apply a load (reverse load value) up to 50 mN, and when the particle size is less than 10 μm, apply a load (reverse load value) up to 10 mN. Then, release the load until the origin load value (0.40 mN). The load-compression displacement during this period can be measured, and the compression recovery rate at 25°C can be determined according to the following equation. It should be noted that the load speed is 0.33 mN / sec. As the micro-compression tester, for example, "Micro Compression Tester MCT-W200" manufactured by Shimadzu Corporation, "Fisher Scope H-100" manufactured by Fisher Company, etc. can be used.

[0066] Compression recovery rate (%) = [L2 / L1] × 100

[0067] L1: Compression displacement from the origin load value to the rebound load value when applying the load

[0068] L2: Unloading displacement from the rebound load value to the origin load value when releasing the load

[0069] Since the conductive particles have the above compression characteristics, the conductive particles are suitable for use in conductive connection applications in bent parts. When the conductive particles are used for conductive connection in a bent part, they effectively exhibit particularly excellent conduction reliability.

[0070] The conductive particles have the compression characteristics, and are therefore preferably used for the conductive connection of electrodes of flexible components, and more preferably for the conductive connection of electrodes of flexible components in a bent state. By using the conductive particles, the flexible component can be used in a bent state and exhibit high conduction reliability.

[0071] Examples of the connection structure using a flexible component include a flexible panel. The flexible panel can be used as a curved panel. The conductive particles are preferably used for forming the connection part of the flexible panel, and are preferably used for forming the connection part of the curved panel.

[0072] The average particle size of the conductive particles is preferably 3 μm or more, more preferably 5 μm or more, further preferably 7 μm or more, particularly preferably 10 μm or more, preferably 1000 μm or less, more preferably 100 μm or less, further preferably 30 μm or less, particularly preferably 25 μm or less, and most preferably 20 μm or less. When the average particle size of the conductive particles is 3 μm or more and 30 μm or less, the conductive particles can be preferably used for conductive connection applications. When the average particle size of the conductive particles is above the lower limit and below the upper limit, the connection resistance between the electrodes can be further effectively reduced, and the conduction reliability between the electrodes can be further effectively improved.

[0073] The average particle size of the conductive particles is more preferably the number average particle size. The average particle size of the conductive particles can be obtained, for example, by calculating the average value of 50 arbitrary conductive particles observed with an electron microscope or an optical microscope; or by performing multiple measurements using a laser diffraction particle size distribution measuring device and calculating the average value of the measurement results.

[0074] The coefficient of variation of the particle size of the conductive particles is preferably as low as possible, but is usually 0.1% or more, preferably 10% or less, more preferably 8% or less, and further preferably 5% or less. When the coefficient of variation of the particle size of the conductive particles is above the lower limit and below the upper limit, the conduction reliability can be further improved. Among them, the coefficient of variation of the particle size of the conductive particles can be less than 5%.

[0075] The coefficient of variation (CV value) can be measured as follows.

[0076] CV value (%) = (ρ / Dn) × 100

[0077] ρ: Standard deviation of the particle size of the conductive particles

[0078] Dn: Average particle size of the conductive particles

[0079] The shape of the conductive particles is not particularly limited. The shape of the conductive particles can be spherical, or can be a shape other than spherical such as flat.

[0080] Next, the specific embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the following embodiments, and within the scope not impairing the features of the present invention, the following embodiments can be appropriately modified or improved. It should be noted that in the accompanying drawings for reference, the actual dimensions, thicknesses, etc. are appropriately changed for the sake of convenience in explanation.

[0081] Figure 1 is a cross-sectional view showing the conductive particles of the first embodiment of the present invention;

[0082] Figure 1 The conductive particles 1 shown include a base particle 2, a first conductive part 3, and a second conductive part 4. The first conductive part 3 is provided on the surface of the base particle 2. The second conductive part 4 is provided on the surface of the first conductive part 3. The first conductive part 3 is provided between the base particle 2 and the second conductive part 4. The first conductive part 3 is in contact with the surface of the base particle 2. The first conductive part 3 covers the surface of the base particle 2. The second conductive part 4 is in contact with the surface of the first conductive part 3. The second conductive part 4 covers the surface of the first conductive part 3. The conductive particles 1 are coated particles formed by coating the surface of the base particle 2 with the first conductive part 3 and the second conductive part 4. The second conductive part 4 is located on the outermost surface of the conductive part and is the outermost layer. In the conductive particles 1, multiple conductive parts are formed.

[0083] Figure 1 In the conductive particles 1 shown, the presence state of the pinholes satisfies the technical features.

[0084] In the conductive particles 1, the first conductive part 3 covers the entire surface of the base particle 2 to form a conductive layer.

[0085] The first conductive part may cover the entire surface of the base particle or may not cover the entire surface of the base particle. The first conductive part may form a conductive layer that coats the entire surface of the base particle, or may not form a conductive layer that coats the entire surface of the base particle. The first conductive part may be a conductive layer. The conductive particles may have an area where the base particle is not coated by the first conductive part.

[0086] In the conductive particles 1, the second conductive part 4 coats the entire surface of the first conductive part 3 to form a conductive layer. The second conductive part may coat the entire surface of the first conductive part or may not coat the entire surface of the first conductive part. The second conductive part may form a conductive layer that coats the entire surface of the first conductive part, or may form a conductive layer that does not coat the entire surface of the first conductive part. The second conductive part may be a conductive layer. The conductive particles may have an area where the first conductive part is not coated by the second conductive part.

[0087] The conductive particle 1 does not have a core material. The conductive particle 1 does not have protrusions on the outer surface of the conductive part. The conductive particle 1 is spherical. The first conductive part 3 and the second conductive part 4 do not have protrusions on the outer surface. As described above, the conductive particles of the present invention may not have protrusions on the surface of the conductive part and may be spherical. In addition, the conductive particle 1 does not have an insulating material. Among them, the conductive particle 1 may have an insulating material provided on the outer surface of the second conductive part 4.

[0088] In addition, in the conductive particle 1, the first conductive part 3 is directly laminated on the surface of the base material particle 2. For the conductive particle, other conductive parts may be provided between the base material particle and the first conductive part. The first conductive part may also be provided on the surface of the base material particle through other conductive parts.

[0089] Figure 2 It is a cross-sectional view showing the conductive particles of the second embodiment of the present invention.

[0090] Figure 2 The shown conductive particle 21 includes a base material particle 2, a first conductive part 22, a second conductive part 23, a plurality of core materials 24, and an insulating material 25. The first conductive part 22 is provided on the surface of the base material particle 2. The second conductive part 23 is provided on the surface of the first conductive part 22. The plurality of core materials 24 are provided on the surface of the base material particle 2. The first conductive part 22 and the second conductive part 23 cover the base material particle 2 and the plurality of core materials 24. The conductive particle 21 is a coated particle formed by covering the surfaces of the base material particle 2 and the core material 24 with the first conductive part 22 and the second conductive part 23.

[0091] The conductive particle 21 has a plurality of protrusions 21a on the outer surface of the conductive part. The first conductive part 22 and the second conductive part 23 have a plurality of protrusions 22a and 23a on the outer surface. The plurality of core materials 24 are buried in the first conductive part 22 and the second conductive part 23. The core material 24 is provided inside the protrusions 21a, 22a, and 23a. Due to the plurality of core materials 24, the outer surfaces of the first conductive part 22 and the second conductive part 23 bulge to form the protrusions 21a, 22a, and 23a. As described above, the conductive particle may have protrusions on the outer surface of the conductive part. In addition, the conductive particle may have protrusions on the outer surface of the second conductive part and no protrusions on the outer surface part of the first conductive part. The conductive particle may have a plurality of core materials that cause the surface of the second conductive part to bulge inside or on the inner side of the second conductive part, so as to form a plurality of protrusions. The core material may be located inside the first conductive part, inside the first conductive part, or outside the first conductive part.

[0092] The conductive particles 21 use a plurality of core materials 24 to form protrusions 21a, 22a, and 23a. The conductive particles may not use a plurality of the core materials to form the protrusions. The conductive particles may not have a plurality of the core materials.

[0093] The conductive particles 21 have an insulating material 25 provided on the outer surface of the second conductive portion 23. At least a part of the region of the outer surface of the second conductive portion 23 is covered by the insulating material 25. The insulating material 25 is formed of a material having insulating properties and is an insulating particle. As described above, the conductive particles may have an insulating material provided on the outer surface of the conductive portion. Among them, the conductive particles may not necessarily have an insulating material.

[0094] Other details of the conductive particles will be described in detail below. It should be noted that in the following description, “(meth)acrylic acid” means one or both of “acrylic acid” and “methacrylic acid”, and “(meth)acrylate” means one or both of “acrylate” and “methacrylate”.

[0095] (Substrate particles)

[0096] Examples of the substrate particles include resin particles, inorganic particles other than metal particles, organic-inorganic hybrid particles, and metal particles. The substrate particles are preferably substrate particles other than metal particles, more preferably resin particles, inorganic particles other than metal particles, or organic-inorganic hybrid particles. The substrate particles may be core-shell particles having a core and a shell provided on the surface of the core.

[0097] The substrate particles are more preferably resin particles or organic-inorganic hybrid particles, and may be resin particles or organic-inorganic hybrid particles. By using these preferred substrate particles, the effects of the present invention can be more effectively exerted, and conductive particles more suitable for electrically connecting between electrodes can be obtained.

[0098] When the conductive particles are used to connect between electrodes, the conductive particles are disposed between the electrodes, and then the conductive particles are compressed by crimping. When the substrate particles are resin particles or organic-inorganic hybrid particles, the conductive particles are easily deformed during the crimping, and the contact area between the conductive particles and the electrodes becomes larger. Therefore, the conduction reliability between the electrodes is further improved.

[0099] As the material of the resin particles, various resins are preferably used. Examples of the material of the resin particles include: polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polyacrylate; alkylene terephthalate, polycarbonate, polyamide, phenolic 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, polysulfone, polyphenylene ether, polyacetal, polyimide, polyamideimide, polyetheretherketone, polyethersulfone, and polymers obtained by polymerizing one or more kinds of various polymerizable monomers having an ethylenically unsaturated group.

[0100] Since resin particles having physical properties suitable for a conductive material at any compression can be designed and synthesized, and the hardness of the base material particles can be easily controlled within an appropriate range, the material of the resin particles is preferably a polymer obtained by polymerizing one or more kinds of polymerizable monomers having an ethylenically unsaturated group.

[0101] When the resin particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, as the polymerizable monomer having an ethylenically unsaturated group, a non-crosslinkable monomer and a crosslinkable monomer can be used.

[0102] Examples of the non-crosslinkable monomer include: styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride; (meth)acrylic acid alkyl ester compounds such as (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester, (meth)acrylic acid butyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid lauryl ester, (meth)acrylic acid cetyl ester, (meth)acrylic acid stearyl ester, (meth)acrylic acid cyclohexyl ester, and (meth)acrylic acid isobornyl ester; oxygen atom-containing (meth)acrylic ester compounds such as (meth)acrylic acid 2-hydroxyethyl ester, glycerol (meth)acrylate, polyoxyethylene (meth)acrylate, and (meth)acrylic acid glycidyl ester; nitrile group-containing monomers such as (meth)acrylonitrile; vinyl ester compounds such as vinyl acetate, vinyl butyrate, vinyl laurate, and vinyl stearate; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; halogen-containing monomers such as (meth)acrylic acid trifluoromethyl ester, (meth)acrylic acid pentafluoroethyl ester, vinyl chloride, vinyl fluoride, and chlorostyrene.

[0103] As the crosslinkable monomer, for example, the following can be mentioned: tetra(2-hydroxyethyl)methane tetra(meth)acrylate, tetra(2-hydroxyethyl)methane tri(meth)acrylate, tetra(2-hydroxyethyl)methane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, glycerol tri(meth)acrylate, glycerol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate and other polyfunctional (meth)acrylate compounds; triaryl (iso)cyanurates, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, γ-(meth)acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane and other silane-containing monomers, etc.

[0104] The resin particles can be obtained by polymerizing a polymerizable monomer having the ethylenically unsaturated group by a known method. As such a method, a suspension polymerization method in the presence of a radical polymerization initiator; a method of swelling non-crosslinked seed particles with a radical polymerization initiator and polymerizing a monomer can be mentioned, etc.

[0105] When the base material particles are inorganic particles other than metal particles or organic-inorganic hybrid particles, as the inorganic substance of the material of the base material particles, the following can be mentioned: silica, alumina, barium titanate, zirconia, carbon black, etc. The inorganic substance is preferably non-metallic. The particles formed of the silica are not particularly limited, and for example, particles obtained by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyls to form crosslinked polymer particles and then firing as needed can be mentioned. As the organic-inorganic hybrid particles, for example, organic-inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin can be mentioned, etc.

[0106] The organic-inorganic hybrid particles are preferably core-shell type organic-inorganic hybrid particles having a core and a shell provided on the surface of the core. The core is preferably an organic core. The shell is preferably an inorganic shell. From the viewpoint of more effectively reducing the connection resistance between electrodes, the base material particles are preferably organic-inorganic hybrid particles having an organic core and an inorganic shell provided on the surface of the organic core.

[0107] As the material of the organic core, the material of the resin particles etc. can be mentioned.

[0108] As the material of the inorganic shell, the inorganic substances listed as the material of the base material particles can be cited. The material of the inorganic shell is preferably silica. The inorganic shell is preferably formed on the surface of the core by forming a metal alkoxide in the shell by the sol-gel method and then firing the shell-like material. The metal alkoxide is preferably a silane alkoxide. The inorganic shell is preferably formed from a silane alkoxide.

[0109] When the base material particles are metal particles, examples of the metal as the material of the metal particles include silver, copper, nickel, silicon, gold, and titanium. Among them, the base material particles are preferably non-metal particles.

[0110] The particle size of the base material particles is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 2.5 μm or more, particularly preferably 3 μm or more, preferably 1000 μm or less, more preferably 100 μm or less, further preferably 30 μm or less, and particularly preferably 5 μm or less. When the particle size of the base material particles is below the upper limit or above the lower limit, the contact area between the conductive particles and the electrode becomes larger, the conduction reliability between the electrodes is further improved, and the connection resistance between the connected electrodes can be further effectively reduced. In addition, when a conductive portion is formed on the surface of the base material particles, it is difficult to aggregate, and it becomes difficult to form aggregated conductive particles. When the particle size of the base material particles is below the upper limit, the conductive particles can be easily compressed sufficiently, and the connection resistance between the electrodes connected via the conductive particles can be further effectively reduced. In addition, even if the interval between the electrodes is reduced and the thickness of the conductive portion is increased, smaller conductive particles can be obtained.

[0111] The particle size of the base material particles represents the diameter when the base material particles are spherical, and when the base material particles are non-spherical, it represents the maximum diameter.

[0112] The particle size of the base material particles represents the number average particle size. The particle size of the base material particles can be obtained using a particle size distribution measuring device or the like. The particle size of the base material particles is preferably obtained by observing 50 arbitrary base material particles with an electron microscope or an optical microscope and calculating the average value. In the case of measuring the particle size of the base material particles in the conductive particles, the measurement can be performed as follows.

[0113] Conductive particles were added and dispersed in "Technobit 4000" manufactured by Kulzer so that the content of the conductive particles was 30% by weight, and an embedded resin for checking the conductive particles was prepared. The cross-section of the conductive particles was cut using an ion milling device ("IM 4000" manufactured by Hitachi High-Technologies Corporation) so that the cross-section passed near the center of the conductive particles dispersed in the embedded resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 25,000 times, and 50 conductive particles were randomly selected to observe the base particles of each conductive particle. The particle size of the base particles in each conductive particle was measured and averaged as the particle size of the base particles.

[0114] (The first conductive part and the second conductive part)

[0115] The conductive particles have a first conductive part. There is no particular limitation on the metal used as the material of the first conductive part. Examples of the metal include: gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, etc., and alloys of these substances. In addition, examples of the metal include indium tin oxide (ITO) doped with tin and solder. The metal used as the material of the first conductive part can be used alone or in combination of two or more.

[0116] From the viewpoint of further effectively improving the conduction reliability between electrodes, the metal used as the material of the first conductive part preferably includes an alloy containing nickel, tin, nickel, palladium, copper or gold, and more preferably nickel or palladium.

[0117] From the viewpoint of further effectively improving the conduction reliability between electrodes, the first conductive part preferably contains nickel and phosphorus. The first conductive part is preferably a nickel-containing conductive part and preferably contains nickel as the main metal. The nickel content in 100% by weight of the first conductive part is preferably 10% by weight or more, more preferably 50% by weight or more, further preferably 60% by weight or more, further preferably 70% by weight or more, and particularly preferably 90% by weight or more. The nickel content in 100% by weight of the first conductive part can be 97% by weight or more, or 97.5% by weight or more, or 98% by weight or more. When the nickel content of the first conductive part is above the lower limit, the conduction reliability between electrodes is further effectively improved.

[0118] The phosphorus content in 100% by weight of the first conductive part is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and preferably 15% by weight or less, more preferably 10% by weight or more. When the phosphorus content of the first conductive part is above the lower limit and below the upper limit, the connection resistance between the electrodes is further effectively reduced.

[0119] From the viewpoint of further effectively improving the conduction reliability between the electrodes and further effectively preventing the cracking of the conductive part due to external impact, it is preferred that in the thickness direction of the first conductive part, the phosphorus content on the second conductive part side in the first conductive part is greater than the phosphorus content on the base material particle side of the first conductive part.

[0120] It is preferred that the phosphorus content in 100% by weight of the region of the first 1 / 2 thickness of the first conductive part from the second conductive part side towards the inside (the region with a thickness of 50% on the outer surface side) is higher than the phosphorus content in 100% by weight of the region of the first 1 / 2 thickness of the first conductive part from the base material particle side towards the outside (the region with a thickness of 50% on the inner surface side). By setting the phosphorus content in 100% by weight of the region with a thickness of 50% on the outer surface side to be higher than the phosphorus content in 100% by weight of the 50% thickness on the inner surface side, the conduction reliability between the electrodes is further effectively improved, and the breakage of the conductive part due to external impact can be further effectively prevented.

[0121] The phosphorus content in 100% by weight of the region of the first 1 / 2 thickness of the first conductive part from the second conductive part side towards the inside (the region with a thickness of 50% on the outer surface side) is preferably 1% by weight or more, more preferably 3% by weight or more, preferably 15% by weight or less, more preferably 10% by weight or less. When the phosphorus content in 100% by weight of the region with a thickness of 50% on the outer surface side is above the lower limit and below the upper limit, the conduction reliability between the electrodes can be further effectively improved. The breakage of the conductive part due to external impact can be further effectively prevented.

[0122] The phosphorus content in 100% by weight of the region of the first 1 / 2 thickness of the first conductive part from the base material particle side towards the outside (the region with a thickness of 50% on the inner surface side) is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, preferably 10% by weight or less, more preferably 5% by weight or less. When the phosphorus content in 100% by weight of the region with a thickness of 50% on the inner surface side is above the lower limit and below the upper limit, the conduction reliability between the electrodes can be further effectively improved, and the breakage of the conductive part due to external impact can be further effectively prevented.

[0123] The phosphorus content is measured using an energy-dispersive X-ray analyzer (EDS) generated by a field emission transmission electron microscope ("JEM-2010FEF" manufactured by JEOL Ltd.) on a thin film section of conductive particles prepared using a focused ion beam.

[0124] The thickness of the first conductive portion is preferably 100 nm or more, more preferably 150 nm or more, preferably 300 nm or less, and more preferably 250 nm or less. When the thickness of the first conductive portion is above the lower limit and below the upper limit, the connection resistance between the electrodes can be further effectively reduced. The thickness of the first conductive portion refers to the thickness of the portion where the first conductive portion is formed, excluding the portion where the first conductive portion is not formed. The thickness of the first conductive portion represents the average thickness of the first conductive portion in the conductive particles.

[0125] The thickness of the first conductive portion is measured, for example, by observing the cross-section of the conductive particles using a transmission electron microscope (TEM).

[0126] The conductive particles have a second conductive portion. The second conductive portion preferably contains gold, silver, palladium, platinum, copper, cobalt, ruthenium, indium, or tin, more preferably contains gold or silver, and even more preferably contains gold.

[0127] Examples of metals that can be used for the second conductive portion include: gold, silver, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, palladium, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, tungsten, molybdenum, and indium tin oxide (ITO). These metals can be used alone or in combination of two or more.

[0128] The second conductive portion is preferably a conductive portion containing gold, and preferably contains gold as the main metal. The gold content in 100% by weight of the second conductive portion is preferably 10% by weight or more, more preferably 50% by weight or more, further preferably 60% by weight or more, further preferably 70% by weight or more, and preferably 90% by weight or more. The gold content in 100% by weight of the second conductive portion can be 97% by weight or more, or 97.5% by weight or more, or 98% by weight or more. When the gold content in the second conductive portion is above the lower limit, the connection resistance between the electrodes can be further effectively reduced.

[0129] From the perspective of further effectively improving the conduction reliability between the electrodes and from the perspective of further effectively preventing the conductive portion from cracking due to external impact, it is preferred that the ionization tendency of the metal contained in the first conductive portion is greater than the ionization tendency of the metal contained in the second conductive portion.

[0130] The thickness of the second conductive portion is preferably 20 nm or more, more preferably 25 nm or more, preferably 40 nm or less, and more preferably 35 nm or less. When the thickness of the second conductive portion is above the lower limit and below the upper limit, the connection resistance between the electrodes is further effectively reduced. The thickness of the second conductive portion refers to the thickness of the portion where the second conductive portion is formed, excluding the portion where the second conductive portion is not formed. The thickness of the second conductive portion represents the average thickness of the second conductive portion in the conductive particles.

[0131] The thickness of the second conductive portion can be measured, for example, by observing the cross-section of the conductive particles using a transmission electron microscope (TEM).

[0132] There is no particular limitation on the method for forming the first conductive portion and the second conductive portion. Examples of the method for forming the first conductive portion and the second conductive portion include: a method based on electroless plating; a method based on electroplating; a method based on physical vapor deposition; and a method of coating a paste containing metal powder or containing metal powder and a binder on the particle surface. Since the formation of the conductive portion is simple, a method based on electroless plating is preferred. Examples of the physical vapor deposition method include vacuum evaporation, ion plating, and ion sputtering.

[0133] Examples of the method for controlling the contents of nickel and phosphorus in the first conductive portion include the following methods. When the first conductive portion is formed by electroless plating, a method of controlling the pH of the nickel plating solution. When the first conductive portion is formed by electroless plating, a method of adjusting the concentration of the phosphorus-containing reducing agent. A method of adjusting the nickel concentration in the nickel plating solution.

[0134] The manufacturing method of the conductive particles uses a process of providing a second conductive portion on the outer surface of a conductive particle having a base particle and a first conductive portion disposed on the surface of the base particle by plating treatment. Through this process, conductive particles having the second conductive portion on the outer surface of the first conductive portion are obtained.

[0135] When forming the first conductive part, in the thickness direction of the first conductive part, preferably, the phosphorus content on the side of the second conductive part in the first conductive part is more than the phosphorus content on the side of the base material particles in the first conductive part. Forming the first conductive part in a preferred manner can further effectively improve the conduction reliability between electrodes and can further effectively prevent the cracking of the conductive part due to external impact. In the thickness direction of the first conductive part, making the phosphorus content on the side of the second conductive part in the first conductive part more than the phosphorus content on the side of the base material particles in the first conductive part can suppress the dissolution of metals (such as nickel, etc.) that are the materials of the first conductive part. As a result, the generation of pinholes in the first conductive part can be further effectively suppressed, and the cracking of the conductive part due to external impact can be further effectively prevented.

[0136] From the perspective of further effectively improving the conduction reliability between electrodes and from the perspective of further effectively preventing the cracking of the conductive part caused by external impact, in the plating process for forming the second conductive part, it is preferable to use displacement gold plating and reduction gold plating in combination. When forming the second conductive part, using displacement gold plating and reduction gold plating in combination can suppress the dissolution of metals (such as nickel, etc.) that are the materials of the first conductive part. As a result, the generation of pinholes in the first conductive part can be further effectively suppressed, and the cracking of the conductive part caused by external impact can also be further effectively prevented.

[0137] In addition, as another method for suppressing the dissolution of metals (such as nickel, etc.) that are the materials of the first conductive part, a method of pre-plating nickel before performing the plating process for forming the second conductive part can be cited. By pre-plating nickel, the nickel for dissolution that is dissolved through the plating process (displacement gold plating and reduction gold plating) for forming the second conductive part can be pre-set on the surface of the first conductive part. During the plating process (displacement gold plating and reduction gold plating) for forming the second conductive part, the dissolution of the nickel for dissolution can suppress the dissolution of metals (such as nickel, etc.) that are the materials of the first conductive part. As a result, the generation of pinholes in the first conductive part can be further effectively suppressed, and the cracking of the conductive part due to external impact can be further effectively prevented.

[0138] From the perspective of further effectively improving the conduction reliability between electrodes and from the perspective of further effectively preventing the rupture of the conductive portion caused by external shocks, it is preferable that the manufacturing method of the conductive particles is obtained by combining the above methods. Specifically, it is preferable to combine the following (first technical feature), (second technical feature), and (third technical feature). (First technical feature) Regarding the manufacturing method of the conductive particles, the phosphorus content on the side of the second conductive portion in the first conductive portion in the thickness direction of the first conductive portion is greater than the phosphorus content on the side of the base material particles in the first conductive portion. (Second technical feature) The plating treatment for forming the second conductive portion combines displacement gold plating and reduction gold plating. (Third technical feature) Before performing the plating treatment for forming the second conductive portion, nickel plating is performed in advance. By combining all the above technical features, when observing the outer surface of the second conductive portion using an electron microscope, the second conductive portion can be formed and there are no pinholes with a size of 50 nm or more in the maximum length direction, or there is 1 pinhole / μm 2 or less with a size of 50 nm or more in the maximum length direction as follows.

[0139] (Core material)

[0140] It is preferable that the conductive particles have a plurality of protrusions on the outer surfaces of the first conductive portion and the second conductive portion. The conductive particles preferably have a plurality of protrusions on the outer surfaces of the first conductive portion and the second conductive portion, whereby the conduction reliability between the electrodes can be further enhanced. Usually, an oxide film is formed on the surface of the electrode connected by the conductive particles. And usually, an oxide coating film is formed on the surfaces of the first conductive portion and the second conductive portion of the conductive particles. By using the conductive particles having the protrusions, the conductive particles can be disposed between the electrodes, and then, by pressing, the oxide coating film can be effectively removed through the protrusions. Therefore, the contact between the electrode and the conductive particles can be made more reliably, and the connection resistance between the electrodes can be reduced more effectively. In addition, when the conductive particles have an insulating substance on the surface, or when the conductive particles are dispersed in an adhesive resin and used as a conductive material, due to the protrusions of the conductive particles, the resin between the conductive particles and the electrode is effectively excluded. Therefore, the conduction reliability between the electrodes can be further effectively improved.

[0141] The core material is embedded in the first conductive portion and the second conductive portion, whereby a plurality of protrusions can be easily formed on the outer surfaces of the first conductive portion and the second conductive portion. Among them, it is not necessarily required to use a core material to form protrusions on the surfaces of the first conductive portion and the second conductive portion.

[0142] As a method for forming the protrusion, a method in which a core material is attached to the surface of base material particles and then the first conductive portion and the second conductive portion are formed by electroless plating; and a method in which the core material is attached after the first conductive portion is formed by electroless plating on the surface of the base material particles and then the second conductive portion is formed by electroless plating, etc. As other methods for forming the protrusion, a method in which the core material is disposed on the first conductive portion after the first conductive portion is formed on the surface of the base material particles and then the second conductive portion is formed; and a method in which the core material is added at an intermediate stage of forming a conductive portion (such as the first conductive portion or the second conductive portion, etc.) on the surface of the base material particles, etc. In addition, in order to form the protrusion, the following method can be used: the first conductive portion is formed by electroless plating on the base material particles without using the core material, and then, a plating layer is precipitated in a protrusion shape on the surface of the first conductive portion, and the second conductive portion can be formed by electroless plating.

[0143] As a method for disposing the core material on the outer surface of the base material particles, for example, a method in which the core material is added to a dispersion of the base material particles and the core material is aggregated and adhered to the surface of the base material particles by van der Waals force or the like; a method in which the core material is added to a container containing the base material particles and the core material is attached to the surface of the base material particles by mechanical action such as rotation of the container, etc. Since the amount of the core material to be attached can be easily controlled, a method in which the core material is accumulated and attached to the surface of the base material particles in the dispersion is preferred.

[0144] The material of the core material is not particularly limited. As the material of the core material, for example, conductive materials and non-conductive materials can be cited. As the conductive material, metals, metal oxides, conductive non-metals such as graphite, and conductive polymers, etc. can be cited. As the conductive polymer, polyacetylene, etc. can be cited. As the non-conductive material, silica, alumina, barium titanate, zirconia, etc. can be cited. Since the conductivity can be increased and the connection resistance can be effectively reduced, the core material is preferably a metal. The core material is preferably metal particles. As the metal of the material of the core material, the metals cited as the material of the conductive material can be appropriately used.

[0145] The Mohs hardness of the material of the core substance is preferably high. Examples of materials with high Mohs hardness include: barium titanate (Mohs hardness 4.5), nickel (Mohs hardness 5), silicon dioxide (silica, Mohs hardness 6 - 7), titanium oxide (Mohs hardness 7), zirconium oxide (Mohs hardness 8 - 9), aluminum oxide (Mohs hardness 9), tungsten carbide (Mohs hardness 9), diamond (Mohs hardness 10), etc. The core substance is preferably nickel, silicon dioxide, titanium oxide, zirconium oxide, aluminum oxide, tungsten carbide or diamond, more preferably silicon dioxide, titanium oxide, zirconium oxide, aluminum oxide, tungsten carbide or diamond. The core substance is more preferably titanium oxide, zirconium oxide, aluminum oxide, tungsten carbide or diamond, particularly preferably zirconium oxide, aluminum oxide, tungsten carbide or diamond. The Mohs hardness of the material of the core substance is preferably 4 or more, more preferably 5 or more, further preferably 6 or more, further preferably 7 or more, particularly preferably 7.5 or more.

[0146] The shape of the core substance material is not particularly limited. The shape of the core substance is preferably a block. Examples of the core substance include a particulate block, an agglomerated block formed by aggregation of a plurality of fine particles, and an amorphous block.

[0147] The particle size of the core substance is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, more preferably 0.2 μm or less. When the particle size of the core substance is above the lower limit and below the upper limit, the connection resistance between electrodes can be effectively reduced.

[0148] The particle size of the core substance represents the number average particle size. The particle size of the core substance is preferably obtained by observing any 50 core substances with an electron microscope or an optical microscope and calculating the average value.

[0149] The number of the protrusions corresponding to one conductive particle is preferably 3 or more, more preferably 5 or more. The upper limit of the number of the protrusions is not particularly limited. The upper limit of the number of the protrusions is appropriately selected in consideration of the particle size of the conductive particle and the use of the conductive particle, etc.

[0150] The number of the protrusions corresponding to one conductive particle is preferably obtained by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating the average value.

[0151] The height of a plurality of the protrusions is preferably 0.001 μm or more, more preferably 0.05 μm or more, and preferably 0.9 μm or less, more preferably 0.2 μm or less. When the height of the protrusions is above the lower limit and below the upper limit, the connection resistance between electrodes can be effectively reduced.

[0152] The height of a plurality of the protrusions is obtained by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating the average value.

[0153] (Insulating substance)

[0154] The conductive particles preferably include an insulating substance provided on the surface of the conductive portion. In this case, when the conductive particles are used for connection between electrodes, short circuits between adjacent electrodes can be further prevented. Specifically, when a plurality of conductive particles are in contact with each other, an insulating substance exists between the plurality of electrodes, so that short circuits between adjacent electrodes in the lateral direction rather than between the upper and lower electrodes can be prevented. It should be noted that, in addition, when connecting between electrodes, by pressing the conductive particles with two electrodes, the insulating substance between the conductive portion of the conductive particles and the electrodes can be easily removed. When the conductive particles have a plurality of protrusions on the outer surface of the conductive portion, the insulating substance between the conductive portion of the conductive particles and the electrodes can be further easily removed.

[0155] From the perspective that the insulating substance can be more easily removed when pressing between electrodes, it is preferred that the insulating substance is insulating particles.

[0156] As the material of the insulating substance, examples include inorganic substances such as those listed as the material of the resin particles and the material of the base particles. The material of the insulating substance is preferably the material of the resin particles. The insulating substance is preferably the resin particles or the organic-inorganic hybrid particles, and can be either resin particles or organic-inorganic hybrid particles.

[0157] As other materials of the insulating substance, examples include: polyolefin compounds, (meth)acrylate polymers, (meth)acrylate copolymers, block polymers, thermoplastic resins, crosslinked products of thermoplastic resins, thermosetting resins, and water-soluble materials, etc. The materials of the insulating substance can be used alone or in combination of two or more.

[0158] Examples of the polyolefin compound include polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, etc. Examples of the (meth)acrylate polymer include poly(methyl)methacrylate, poly(dodecyl)(meth)acrylate, poly(stearyl)(meth)acrylate, etc. Examples of the block polymer include polystyrene, styrene-acrylate copolymer, SB type styrene-butadiene block copolymer, SBS type styrene-butadiene block copolymer, and hydrogenated products thereof, etc. Examples of the thermoplastic resin include vinyl polymer and vinyl copolymer, etc. Examples of the thermosetting resin include epoxy resin, phenolic resin, melamine resin, etc. Examples of the crosslinked product of the thermoplastic resin include those into which polyethylene glycol methacrylate, alkoxylated trimethylolpropane methacrylate, alkoxylated pentaerythritol methacrylate, etc. are introduced. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide, and methyl cellulose, etc. In addition, a chain transfer agent can be used to adjust the degree of polymerization. Examples of the chain transfer agent include mercaptan and carbon tetrachloride, etc.

[0159] Examples of the method for providing an insulating substance on the surface of the conductive portion (second conductive portion) include chemical methods, physical or mechanical methods, etc. Examples of the chemical method include interfacial polymerization method, suspension polymerization method in the presence of particles, and emulsion polymerization method, etc. Examples of the physical or mechanical method include spray drying method, hybridization method, electrostatic adhesion method, spraying method, dipping, and vacuum evaporation method, etc. Since the insulating substance is not easily detached, it is preferable to provide the insulating substance on the surface of the second conductive portion by chemical bond.

[0160] The outer surface of the conductive portion (second conductive portion) and the surface of the insulating substance can be respectively coated with a compound having a reactive functional group. The outer surface of the conductive portion (second conductive portion) and the surface of the insulating substance may not be directly chemically bonded, but may be indirectly chemically bonded through a compound having a reactive functional group. After introducing a carboxyl group into the outer surface of the conductive portion (second conductive portion), the carboxyl group can be chemically bonded to the functional group on the surface of the insulating substance through a polyelectrolyte such as polyethyleneimine.

[0161] The particle size of the insulating material can be appropriately selected according to the particle size of the conductive particles and the use of the conductive particles, etc. The particle size of the insulating material is preferably 10 nm or more, more preferably 100 nm or more, preferably 4000 nm or less, and more preferably 2000 nm or less. When the particle size of the insulating material is above the lower limit, the conductive particles are dispersed in the binder resin, and the conductive portions of multiple conductive particles are not likely to contact each other. When the particle size of the insulating material is below the upper limit, when connecting between electrodes, it is not necessarily required to apply too high pressure and it is not necessary to heat to a high temperature to remove the insulating material between the electrodes and the conductive particles.

[0162] The particle size of the insulating material is expressed as the number average particle size. The particle size of the insulating material can be obtained using a particle size distribution measuring device, etc. Preferably, the particle size of the insulating material is obtained by observing 50 arbitrary insulating materials with an electron microscope or an optical microscope and calculating the average value. In the case of measuring the particle size of the insulating material for the conductive particles, for example, it can be measured by the following method.

[0163] The conductive particles are added and dispersed in "Technobit 4000" manufactured by Kulzer so that the content of the conductive particles is 30% by weight, and an embedded resin for checking the conductive particles is prepared. The cross-section of the conductive particles is cut using an ion milling device ("IM 4000" manufactured by Hitachi High-Technologies Corporation) so that the cross-section passes near the center of the conductive particles dispersed in the embedded resin for checking. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification is set to 50,000 times, 50 conductive particles are randomly selected, and the base particles of each conductive particle are observed. The particle size of the insulating material in each conductive particle is measured, averaged, and used as the particle size of the insulating material.

[0164] (Conductive material)

[0165] The conductive material of the present invention includes the conductive particles and the binder resin. The conductive particles are preferably used by being dispersed in the binder resin, and are preferably used as a conductive material by being dispersed in the binder resin. The conductive material is preferably an anisotropic conductive material. The conductive material is preferably used for electrical connection between electrodes. The conductive material is preferably a conductive material for circuit connection.

[0166] The binder resin is not particularly limited. A known insulating resin is 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. As the curable component, a photocurable component and a thermosetting component can be cited. The photocurable component preferably contains a photocurable compound and a photoinitiator. The thermosetting component preferably contains a thermosetting compound and a curing agent.

[0167] Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers, etc. The binder resin can be used alone or in combination of two or more.

[0168] Examples of the vinyl resin include vinyl acetate resin, acrylic resin, and styrene resin, etc. Examples of the thermoplastic resin include polyolefin resin, ethylene-vinyl acetate copolymer, and polyamide resin, etc. Examples of the curable resin include epoxy resin, polyurethane resin, polyimide resin, unsaturated polyester resin, etc. It should be noted that the curable resin can be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin can be used in combination with a curing agent. Examples of the thermoplastic block copolymer include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated product of styrene-butadiene-styrene block copolymer, and hydrogenated product of styrene-isoprene-styrene block copolymer, etc. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber, etc.

[0169] In addition to the conductive particles and the binder resin, the conductive material may further contain various additives such as fillers, extenders, softeners, plasticizers, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, UV absorbers, lubricants, antistatic agents, and flame retardants, etc.

[0170] From the viewpoint of more effectively reducing the connection resistance between electrodes and from the viewpoint of more effectively improving the conduction reliability between electrodes, the viscosity (η25) of the conductive material at 25 °C is preferably 20 Pa·s or more, more preferably 30 Pa·s or more, preferably 400 Pa·s or less, and more preferably 300 Pa·s or less. The viscosity (η25) can be appropriately adjusted according to the type and mixing amount of the mixed components.

[0171] The viscosity can be measured, for example, using an E-type viscometer (“TVE 22L” manufactured by Toki Sangyo Co., Ltd.) under the conditions of 25 °C and 5 rpm.

[0172] The conductive material can be used as a conductive paste, a conductive film, and the like. When the conductive material is a conductive film, a film containing no conductive particles can be laminated on the conductive film containing conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

[0173] In 100% by weight of the conductive material, the content of the binder resin is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, and particularly preferably 70% by weight or more. It is preferably 99.99% by weight or less, and more preferably 99.9% by weight or less. When the content of the binder resin is above the lower limit and below the upper limit, the conductive particles are effectively disposed between the electrodes, and further effectively improves the connection reliability of the connection target components connected by the conductive material.

[0174] In 100% by weight of the conductive material, the content of the conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and preferably 80% by weight or less, more preferably 60% by weight or less, still more preferably 40% by weight or less, particularly preferably 20% by weight or less, and most preferably 10% by weight or less. When the content of the conductive particles is above the lower limit and below the upper limit, the conduction reliability between the electrodes is further enhanced.

[0175] (Connection structure)

[0176] By using the conductive particles or a conductive material containing the conductive particles and a binder resin to connect the connection target components, a connection structure can be obtained.

[0177] The connection structure includes: a first connection target component, a second connection target component, and a connection portion that connects the first connection target component and the second connection target component together. The material of the connection portion is preferably the conductive particles, or preferably a conductive material containing the conductive particles and a binder resin. Preferably, the connection portion is formed of the conductive particles, or formed of a conductive material containing the conductive particles and a binder resin. When using conductive particles, the connection portion itself is the conductive particles.

[0178] The first connection target component preferably has a first electrode on its surface. The second connection target component preferably has a second electrode on its surface. Preferably, the first electrode and the second electrode are electrically connected through the conductive particles.

[0179] The connection structure preferably includes a flexible member as the first connection target member or the second connection target member. At this time, at least one of the first connection target member and the second connection target member may be a flexible member, and both the first connection target member and the second connection target member may be flexible members. It is preferred to use the connection structure in a state where the flexible member is bent. It is preferred to use the connection structure in a state where the connection portion is bent.

[0180] Figure 3 It is a cross-sectional view schematically showing a connection structure using the conductive particles of the first embodiment of the present invention.

[0181] Figure 3 The shown connection structure 51 includes a first connection target member 52, a second connection target member 53, and a connection portion 54 connecting the first connection target member 52 and the second connection target member 53. The connection portion 54 is formed of a conductive material containing conductive particles 1. It is preferred that the conductive material has thermosetting properties, and the connection portion 54 is formed by thermally curing the conductive material. It should be noted that, Figure 3 for the sake of easy explanation, the conductive particles 1 are schematically shown. Conductive particles 21 or the like can be used instead of the conductive particles 1.

[0182] 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 connection target member 52 and the second connection target member 53 are electrically connected through the conductive particles 1.

[0183] The manufacturing method of the connection structure is not particularly limited. As an example of manufacturing the connection structure, a method in which the conductive material is disposed between the first connection target member and the second connection target member, and after obtaining a laminate, the laminate is further heated and pressed, etc. The pressure of the hot pressing is about 0.5×10 6 Pa to 5×10 6 Pa. The heating temperature of the hot pressing is about 70°C to 230°C. The heating temperature of the hot pressing is preferably 80°C or higher, more preferably 100°C or higher, preferably 200°C or lower, more preferably 150°C or lower. The pressure of the hot pressing is preferably 0.5×10 6 Pa or higher, more preferably 1×10 6 Pa or higher, preferably 5×10 6 Pa or lower, more preferably 3×10 6Below Pa. When the pressure and temperature of the hot pressing are above the lower limit and below the upper limit, the conduction reliability between the electrodes can be further effectively improved.

[0184] As the connection target components, specifically, the following can be cited: electronic components such as semiconductor chips, capacitors, and diodes, and circuit boards such as printed circuit boards, flexible printed circuits, glass epoxy substrates, and glass substrates, etc. The connection target components are preferably electronic components. The conductive particles are preferably used for electrically connecting the electrodes in the electronic components.

[0185] As the electrodes provided in the connection target components, the following can be cited: metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, silver electrodes, SUS electrodes, copper electrodes, molybdenum electrodes, and tungsten electrodes. When the connection target component is a flexible printed board, the electrodes are preferably gold electrodes, nickel electrodes, tin electrodes, or copper electrodes. When the connection target component is a glass substrate, the electrodes are preferably aluminum electrodes, copper electrodes, molybdenum electrodes, or tungsten electrodes. It should be noted that in the case where the electrode is an aluminum electrode, it can be an electrode formed solely of aluminum, or an electrode formed by laminating an aluminum layer on the surface of a metal oxide layer. As the material of the metal oxide layer, indium oxide doped with a trivalent metal element, zinc oxide doped with a trivalent metal element, etc. can be cited. As the trivalent metal element, Sn, Al, Ga, etc. can be cited.

[0186] Hereinafter, the present invention will be specifically described by way of examples and comparative examples. The present invention is not limited to the following examples.

[0187] Base material particles:

[0188] Base material particle A: Copolymer resin particles of resin particles, divinylbenzene, and isobornyl acrylate, particle size: 10 μm

[0189] Base material particle B: Copolymer resin particles of resin particles, divinylbenzene, and isobornyl acrylate, particle size: 5 μm

[0190] Base material particle C: Copolymer resin particles of resin particles, divinylbenzene, and isobornyl acrylate, particle size: 20 μm

[0191] (Example 1)

[0192] (1) Formation of the first conductive portion (nickel layer)

[0193] 10 parts by weight of base material particles A are dispersed in 100 parts by weight of an alkaline solution containing 5 wt% of a palladium catalyst solution using an ultrasonic disperser. Then, the solution is filtered to remove the base material particles A. Then, the base material particles A are added to 100 parts by weight of a 1 wt% dimethylamine borane solution to activate the surface of the base material particles A. After thoroughly washing the base material particles A whose surface has been activated, they are added to 500 parts by weight of distilled water and dispersed to obtain a suspension.

[0194] In addition, a nickel plating solution (pH 9.0) containing 0.25 mol / L nickel sulfate, 0.25 mol / L sodium hypophosphite, and 0.15 mol / L sodium citrate is prepared.

[0195] The obtained suspension is stirred at 70 °C, and the nickel plating solution is gradually added dropwise to the suspension for electroless nickel plating. Then, the particles are taken out by filtering the suspension, washed with water, and dried to obtain particles with a first conductive portion (nickel-phosphorus layer, thickness 200 nm) provided on the surface of the base material particles A. The nickel content in the conductive layer is 94.5 wt% and the phosphorus content is 5.5 wt% by 100 wt%.

[0196] (2) Formation of the second conductive portion (gold layer)

[0197] Particles with a first conductive portion provided on the surface of 10 parts by weight of the base material particles A are added to 100 parts by weight of distilled water and dispersed to obtain a suspension. In addition, a reduced gold plating solution containing 0.03 mol / L of gold cyanide and 0.1 mol / L of hydroquinone as a reducing agent is prepared. The obtained suspension is stirred at 70 °C, and the reduced gold plating solution is gradually added dropwise to the suspension for reduced gold plating. Thereafter, the particles are taken out by filtering the suspension, washed with water, and dried to obtain conductive particles. In the obtained conductive particles, a second conductive portion (gold layer, thickness 31 nm) is provided on the outer surface of the first conductive portion. Figure 4 is an image showing the surface of the conductive particles manufactured in Example 1.

[0198] (Example 2)

[0199] (1) Formation of the first conductive portion (nickel layer)

[0200] 10 parts by weight of base material particles B are dispersed in 100 parts by weight of an alkaline solution containing 5 wt% of a palladium catalyst solution using an ultrasonic disperser. Then, the base material particles B are taken out by filtering the solution. Then, the base material particles B are added to 100 parts by weight of a 1 wt% dimethylamine borane solution to activate the surface of the base material particles B. After thoroughly washing the base material particles B whose surface has been activated, they are added to 500 parts by weight of distilled water and dispersed to obtain a suspension.

[0201] In addition, a nickel plating solution (pH 9.0) containing 0.25 mol / L nickel sulfate, 0.25 mol / L sodium hypophosphite, and 0.15 mol / L sodium citrate was prepared.

[0202] The obtained suspension was stirred at 70°C, and the nickel plating solution was gradually added dropwise to the suspension for electroless nickel plating. Then, the particles were taken out by filtering the suspension, and after washing with water and drying, particles with a first conductive portion (nickel-phosphorus layer, thickness 210 nm) provided on the surface of the substrate particles B were obtained. The nickel content in the conductive layer was 94.5% by weight, and the phosphorus content was 5.5% by weight.

[0203] (2) Formation of nickel plating layer

[0204] 10 parts by weight of the particles with the first conductive portion provided on the surface of the substrate particles B were added to 100 parts by weight of distilled water and dispersed to obtain a suspension. In addition, a nickel solution containing 10% by weight nickel sulfate, 10% by weight sodium hypophosphite, 4% by weight sodium hydroxide, and 20% by weight sodium succinate in a volume of 52 mL was prepared. The obtained suspension was stirred at 80°C, and the nickel solution was continuously added dropwise at 5 mL / min, and the plating reaction was carried out by stirring for 20 minutes. After confirming that hydrogen was no longer generated, the plating reaction was terminated. Thereafter, the particles were taken out by filtering the suspension, washed with water and dried, to obtain particles with the first conductive portion and a nickel plating layer provided on the surface of the substrate particles B.

[0205] (3) Formation of the second conductive portion (gold layer)

[0206] 10 parts by weight of the particles provided with the first conductive portion and the nickel plating layer were added to 100 parts by weight of distilled water using an ultrasonic disperser and dispersed to obtain a suspension. In addition, a reducing gold plating solution containing 0.03 mol / L gold cyanide and 0.1 mol / L hydroquinone as a reducing agent was prepared. The obtained suspension was stirred at 70°C, and the reducing gold plating solution was gradually added dropwise to the suspension for reducing gold plating. Thereafter, the particles were taken out by filtering the suspension, washed with water and dried, to obtain conductive particles. In the obtained conductive particles, the second conductive portion (gold layer, thickness 30 nm) was provided on the outer surface of the first conductive portion.

[0207] (Example 3)

[0208] When the substrate particles B were changed to substrate particles C and the thickness of the second conductive portion was changed to 35 nm during the formation of the first conductive portion, conductive particles were obtained in the same manner as in Example 2 except for this. In the obtained conductive particles, the second conductive portion (gold layer, thickness 35 nm) was provided on the outer surface of the first conductive portion.

[0209] (Example 4)

[0210] When forming the first conductive part, substrate particles B were changed to substrate particles A, 1 part by weight of metallic nickel particles (average particle diameter 150 nm) was added to the resulting suspension to obtain a suspension containing substrate particles A with a core substance attached thereto, the thickness of the second conductive part was changed to 29 nm, and in other respects, conductive particles were obtained in the same manner as in Example 2. In the obtained conductive particles, the second conductive part (gold layer, thickness 29 nm) was provided on the outer surface of the first conductive part. The obtained conductive particles had a plurality of protrusions on the outer surfaces of the first conductive part and the second conductive part.

[0211] (Example 5)

[0212] When forming the second conductive part, substrate particles B were changed to substrate particles A, the thickness of the first conductive part was changed to 230 nm, 0.03 mol / L of gold cyanide was changed to 0.015 mol / L of gold cyanide, and the thickness of the second conductive part was changed to 15 nm. In other respects, conductive particles were obtained in the same manner as in Example 2. In the obtained conductive particles, the second conductive part (gold layer, thickness 15 nm) was provided on the outer surface of the first conductive part.

[0213] (Example 6)

[0214] When forming the second conductive part, gold cyanide was changed to palladium sulfate, and the thickness of the second conductive part was changed to 30 nm. In other respects, conductive particles were obtained in the same manner as in Example 1. In the obtained conductive particles, the second conductive part (palladium layer, thickness 30 nm) was provided on the outer surface of the first conductive part.

[0215] (Example 7)

[0216] When forming the first conductive part, substrate particles B were changed to substrate particles A, and the thickness of the second conductive part was changed to 32 nm. In other respects, conductive particles were obtained in the same manner as in Example 2. In the obtained conductive particles, the second conductive part (gold layer, thickness 32 nm) was provided on the outer surface of the first conductive part.

[0217] (Comparative Example 1)

[0218] Prepare a displacement gold plating solution without hydroquinone as a reducing agent. When forming the second conductive part, change the reduction gold plating to a displacement gold plating solution, change the reduction gold plating solution to a displacement gold plating solution to form the second conductive part, form the second conductive part by replacing the reduction gold plating solution with the displacement gold plating solution, change the thickness of the conductive part to 32 nm, and obtain conductive particles in the same manner as in Example 1 except for this. In the obtained conductive particles, a second conductive part (gold layer, thickness 32 nm) is provided on the outer surface of the first conductive part. It should be noted that Figure 5 shows an image of the surface of the conductive particles prepared in Comparative Example 1.

[0219] (Evaluation)

[0220] (1) Existence state of pinholes

[0221] Observe the surface of the second conductive part of the obtained conductive particles with an electron microscope ("FE-SEM SU8010" manufactured by Hitachi High-Technologies Corporation) to evaluate whether there is a first pinhole with a size of 50 nm or more in the maximum length direction. Specifically, evaluate whether the pinhole exists by observing any five positions with an electron microscope in a part other than the part 0.5 μm from the outer periphery of the obtained conductive particles toward the inside. When there is a first pinhole with a size of 50 nm or more in the maximum length direction, measure the number of first pinholes with a size of 50 nm or more in the maximum length direction corresponding to 1 μm 2 In addition, evaluate whether there is a second pinhole with a size of 50 nm or more and 200 nm or less in the maximum length direction. When there is a second pinhole with a size of 50 nm or more and 200 nm or less in the maximum length direction, measure the number of second pinholes with a size of 50 nm or more and 200 nm or less in the maximum length direction corresponding to 1 μm 2

[0222] (2) 10% K value

[0223] Measure the 10% K value of the obtained conductive particles by the above method.

[0224] (3) Compression recovery rate at 25 °C

[0225] Measure the compression recovery rate of the obtained conductive particles at 25 °C by the above method.

[0226] (4) Average particle size

[0227] The average particle size of the obtained conductive particles was measured using a "laser diffraction particle size distribution measuring device" manufactured by Horiba, Ltd. In addition, the average particle size of the conductive particles was calculated by averaging the results of 20 measurements.

[0228] (5) Phosphorus content in the thickness direction of the first conductive part

[0229] A thin film section of the obtained conductive particles was prepared using a focused ion beam. Using a field emission transmission electron microscope ("JEM-2010FEF" manufactured by JEOL Ltd.), the phosphorus content in the thickness direction of the first conductive part was measured by an energy dispersive X-ray analyzer (EDS). From this result, the phosphorus content in 100% by weight of the region of the first half thickness from the substrate particle side toward the outside (the region with a thickness of 50% on the inner surface side) and the phosphorus content in 100% by weight of the region of the first half thickness from the second conductive part side toward the inside (the region with a thickness of 50% on the outer surface side) of the first conductive part were obtained.

[0230] (6) Rupture of the conductive part

[0231] The obtained conductive particles were used to evaluate the rupture of the conductive part. The rupture of the conductive part was evaluated as follows. The rupture of the conductive part was determined according to the following criteria.

[0232] Evaluation method for rupture of the conductive part:

[0233] Using an electron microscope, photographs of 1000 conductive particles were taken at a magnification of about 100 conductive particles per sheet. The obtained photographs of 1000 conductive particles were observed, and the number of conductive particles having a rupture with a length of more than half the diameter of the conductive particle was measured.

[0234] [Judgment criteria for rupture of the conductive part]

[0235] ○: The number of conductive particles having a rupture is less than 100

[0236] ×: The number of conductive particles having a rupture is 100 or more

[0237] (7) Initial connection resistance

[0238] Preparation of the connection structure X:

[0239] The obtained conductive particles were added to "Structbond XN-5A" manufactured by Mitsui Chemicals, Inc., so that the content of the obtained conductive particles was 10% (by weight), and an anisotropic conductive paste was prepared by dispersing them.

[0240] Prepare a transparent glass substrate with an ITO electrode pattern having an L / S of 20 μm / 20 μm on the upper surface. Additionally, prepare a semiconductor chip with a gold electrode pattern having an L / S of 20 μm / 20 μm on the lower surface.

[0241] On the transparent glass substrate, coat the anisotropic conductive paste just after preparation to a thickness of 30 μm to form an anisotropic conductive paste layer. Then, stack the semiconductor chip on the anisotropic conductive paste layer such that the electrodes face each other. Thereafter, adjust the temperature of the head so that the temperature of the anisotropic conductive paste layer is 120 °C, and place the pressure heating head on the upper surface of the semiconductor chip, apply a low pressure of 1 MPa calculated from the pressure area, and cure the anisotropic conductive paste layer at 100 °C to obtain a connection structure X.

[0242] Preparation of connection structure Y:

[0243] Change the temperature during curing of the anisotropic conductive material layer to 150 °C, and otherwise manufacture connection structure Y in the same manner as connection structure X.

[0244] Preparation of connection structure Z:

[0245] Change the temperature during curing of the anisotropic conductive material layer to 200 °C, and otherwise manufacture connection structure Z in the same manner as connection structure X.

[0246] Measure the connection resistance A between the upper and lower electrodes of the obtained connection structures X, Y, and Z respectively by the four-terminal method. It should be noted that from the relationship of voltage = current × resistance, by measuring the voltage when a constant current flows, the connection resistance A can be obtained. Determine the initial connection resistance from the connection resistance A based on the following criteria.

[0247] [Criteria for Judging Initial Connection Resistance]

[0248] ○○○: The connection resistance A is 2.0 Ω or less

[0249] ○○: The connection resistance A is greater than 2.0 Ω and 3.0 Ω or less

[0250] ○: The connection resistance A is greater than 3.0 Ω and 5.0 Ω or less

[0251] △: The connection resistance A is greater than 5.0 Ω and 10 Ω or less

[0252] ×: The connection resistance A is greater than 10 Ω

[0253] (8) Connection Resistance after High Temperature and High Humidity Exposure (Conduction Reliability)

[0254] The connected structures X, Y, and Z after the evaluation of the initial connection resistance (7) are placed under the conditions of 85°C and 85% humidity for 500 hours. After 500 hours of placement, the connection resistance B between the upper and lower electrodes of the connected structures X, Y, and Z is measured by the four-terminal method respectively. The connection resistance (conductivity reliability) after the high-temperature and high-humidity placement of the connection resistances A and B is judged according to the following criteria.

[0255] [Criteria for Judging the Connection Resistance (Conductivity Reliability) after High-Temperature and High-Humidity Placement]

[0256] ○○○: The connection resistance B is less than 1.25 times the connection resistance A

[0257] ○○: The connection resistance B is 1.25 times or more and less than 1.5 times the connection resistance A

[0258] ○: The connection resistance B is 1.5 times or more and less than 2 times the connection resistance A

[0259] △: The connection resistance B is 2 times or more and less than 5 times the connection resistance A

[0260] ×: The connection resistance B is 5 times or more the connection resistance A

[0261] The results are shown in Tables 1 and 2 below.

[0262]

[0263]

[0264] Symbol Explanation

[0265] 1... Conductive particles

[0266] 2... Substrate particles

[0267] 3... First conductive part

[0268] 4... Second conductive part

[0269] 21... Conductive particles

[0270] 21a... Protrusion

[0271] 22... First conductive part

[0272] 22a... Protrusion

[0273] 23... Second conductive part

[0274] 23a... Protrusion

[0275] 24... Core material

[0276] 25... Insulating material

[0277] 51...Connecting structure

[0278] 52...First connection object component

[0279] 52a...First electrode

[0280] 53...Second connection object component

[0281] 53a...Second electrode

[0282] 54...Connection part

Claims

1. A conductive particle, comprising: a base material particle, a first conductive portion provided on the surface of the base material particle, and a second conductive portion provided on the outer surface of the first conductive portion, wherein the compression recovery rate of the conductive particle at 25°C is 10% or less, When observing the outer surface of the second conductive portion using an electron microscope, there are no pinholes with a size of 50 nm or more in the maximum length direction, or there is 1 pinhole / μm 2 or less with a size of 50 nm or more in the maximum length direction.

2. A conductive particle, comprising: a base material particle, a first conductive portion provided on the surface of the base material particle, and a second conductive portion provided on the outer surface of the first conductive portion, wherein the compression recovery rate of the conductive particle at 25°C is 10% or less, When observing the outer surface of the second conductive portion using an electron microscope, there are no pinholes with a size of 50 nm or more in the maximum length direction, or there is 1 / μm 2 or less of pinholes with a size of 50 nm or more and 200 nm or less in the maximum length direction.

3. The conductive particle according to claim 1 or 2, which satisfies the following formula (1), A ≤ 5500 - B × 100... Formula (1) In the above formula (1), A is the 10% K value of the above conductive particles, and its unit is N / mm 2 , B is the average particle diameter of the conductive particle, and the unit is μm.

4. The conductive particle according to claim 1 or 2, wherein The average particle diameter of the conductive particle is 3 μm or more and 30 μm or less.

5. The conductive particles according to claim 1 or 2, wherein, The second conductive portion includes gold, silver, palladium, platinum, copper, cobalt, ruthenium, indium or tin.

6. The conductive particle according to claim 1 or 2, wherein, The ionization tendency of the metal contained in the first conductive portion is greater than the ionization tendency of the metal contained in the second conductive portion.

7. The conductive particles according to claim 1 or 2, wherein The first conductive portion contains nickel and phosphorus.

8. The conductive particle according to claim 1 or 2, wherein, In the thickness direction of the first conductive portion, the phosphorus content on the second conductive portion side in the first conductive portion is greater than the phosphorus content on the base material particle side in the first conductive portion.

9. A method for manufacturing a conductive particle, comprising the following steps: using a conductive particle having a base material particle and a first conductive portion provided on the surface of the base material particle, and applying a plating treatment on the outer surface of the first conductive portion to provide a second conductive portion, to obtain a conductive particle having a compression recovery rate of 10% or less at 25°C, wherein, Form the second conductive portion such that when observing the outer surface of the second conductive portion using an electron microscope, there are no pinholes with a size of 50 nm or more in the maximum length direction, or there is 1 pinhole or less per μm with a size of 50 nm or more in the maximum length direction. 2 Hereinafter, the size in the maximum length direction is 50 nm or more.

10. A conductive material, comprising: the conductive particle according to any one of claims 1 to 8 and an adhesive resin.

11. A connection structure, comprising: a first connection object member having a first electrode on its surface, a second connection object member having a second electrode on its surface, and a connection portion connecting the first connection object member and the second connection object member together, wherein the material of the connection portion is the conductive particle according to any one of claims 1 to 8, or a conductive material containing the conductive particle and an adhesive resin, and the first electrode and the second electrode are electrically connected through the conductive particle.

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