JP2020057612A - Conductive particle, conductive material, and connection structure - Google Patents

Abstract

To provide a conductive particle that can be efficiently disposed between electrodes upon electrically connecting the electrodes, and can reduce connection resistance.SOLUTION: The conductive particle of the present invention includes a base particle and a conductive part, in which the conductive part includes a first conductive part having a crystalline structure and a second conductive part having a crystal structure. The first conductive part is disposed on the surface of the base particle; and the second conductive part is disposed on an outer surface of the first conductive part and in contact with the first conductive part. A difference in terms of an absolute value between the crystallite size in the first conductive part and the crystallite size in the second conductive part is 5 nm or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive particle having a base particle and a conductive part disposed on a surface of the base particle. The present invention also relates to a conductive material and a connection structure using the conductive particles.

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

  In order to obtain various connection structures, the anisotropic conductive material includes, for example, a connection between a flexible printed board and a glass substrate (FOG (Film on Glass)) and a connection between a semiconductor chip and a flexible printed board (COF ( Chip on Film), connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)), connection between a flexible printed board and a glass epoxy substrate (FOB (Film on Board)), and the like.

  As an example of the conductive particles, Patent Literature 1 listed below discloses base particles containing a resin, a buffer layer covering the surface of the base particles, and Au covering the buffer layer. And a conductive particle having a layer. The thickness of the buffer layer is 0.01 to 0.1 μm. The buffer layer contains Ni, Ag, Cu, Al, or an alloy thereof (excluding Ni-P).

  Patent Document 2 listed below discloses conductive particles having base particles and a conductive metal layer covering the surface of the base particles. The conductive metal layer includes a nickel plating layer. In the nickel plating layer, when a cross section in the thickness direction of the nickel plating layer was observed at a magnification of 100,000 by using a scanning electron microscope, a grain boundary was observed in the cross section, and the grain boundary structure was not observed. It is not a columnar structure oriented in the thickness direction of the nickel plating layer.

  Patent Document 3 below discloses conductive particles having base particles and a conductive metal layer covering the surface of the base particles. The conductive metal layer contains nickel. In the conductive particles, the crystallite diameter of nickel in the [111] direction measured by the powder X-ray diffraction method is 3 nm or less.

JP-A-11-39937 JP 2013-73694 A WO2013 / 042785A1

  When the connection structure is obtained by electrically connecting the electrodes using conventional conductive particles as described in Patent Documents 1 to 3, the connection resistance may be increased.

  When electrically connecting the electrodes using conductive particles, generally, the conductive particles are arranged between the electrodes, and heating and pressing are performed. With conventional conductive particles, it may be difficult to efficiently arrange a plurality of conductive particles between electrodes. There is a problem that the conductive particles are easily arranged not only in the line (L) where the electrode is formed but also in the space (S) where the electrode is not formed. For this reason, on the premise that conductive particles are also arranged in a space, it may be necessary to use a large amount of conductive particles. Furthermore, as a result of disposing conductive particles in the space, there is a problem that insulation failure is likely to occur. In addition, when the number of the conductive particles arranged in the portion where the electrode is formed is small, the connection resistance increases.

  An object of the present invention is to provide a conductive particle capable of efficiently arranging conductive particles between the electrodes when the electrodes are electrically connected, and reducing the connection resistance. . It is another object of the present invention to provide a conductive material and a connection structure using the conductive particles.

  According to a broad aspect of the present invention, the electroconductive part includes a base material particle and a conductive part, and the conductive part includes a first conductive part having a crystalline structure, and a second conductive part having a crystalline structure, A first conductive portion is disposed on a surface of the base particle, and the second conductive portion is disposed on an outer surface of the first conductive portion so as to be in contact with the first conductive portion. The conductive particles have an absolute value of a difference between a crystallite size in the first conductive portion and a crystallite size in the second conductive portion of 5 nm or more.

  In a specific aspect of the conductive particles according to the present invention, a crystallite size in the first conductive portion is smaller than or larger than a crystallite size in the second conductive portion.

  In a specific aspect of the conductive particles according to the present invention, the first conductive portion contains nickel.

  In a specific aspect of the conductive particles according to the present invention, the second conductive portion includes nickel.

  In a specific aspect of the conductive particles according to the present invention, the conductive portion has a plurality of protrusions on an outer surface.

  In a specific aspect of the conductive particles according to the present invention, the surface area of the portion having the protrusion is 10% or more, based on 100% of the total surface area of the outer surface of the conductive portion.

  In a specific aspect of the conductive particles according to the present invention, the average height of the plurality of protrusions is 5 nm or more and 1000 nm or less.

  In a specific aspect of the conductive particles according to the present invention, the bases of the plurality of protrusions have an average diameter of 5 nm or more and 1000 nm or less.

  In a specific aspect of the conductive particles according to the present invention, the ratio of the average height of the plurality of protrusions to the average diameter of the base of the plurality of protrusions is 0.1 or more and 10 or less.

  In a specific aspect of the conductive particles according to the present invention, the conductive particles, in the conductive portion, so as to form a plurality of the protrusions, a plurality of core material raised the surface of the conductive portion. Prepare.

  In a specific aspect of the conductive particles according to the present invention, the material of the core substance has a Mohs hardness of 5 or more.

  In a specific aspect of the conductive particles according to the present invention, in the measurement of the entirety of the conductive part having a crystal structure in the conductive part, it is determined from the half-value width of the diffraction peak obtained by X-ray diffraction and Scherrer's formula. The average crystallite size of the (111), (200), (220), (311), and (222) planes is 10 nm or more.

  In a specific aspect of the conductive particles according to the present invention, in the measurement of the entire conductive portion having a crystal structure in the conductive portion, the half width of the diffraction peak obtained by X-ray diffraction and the Williamson-Hall equation Is 10 nm or more.

  In a specific aspect of the conductive particles according to the present invention, in the measurement of the entire conductive part having a crystal structure in the conductive part, the crystallite size of the (220) plane in X-ray diffraction is D (220). When the crystallite size of the (111) plane is D (111), the ratio (D (220) / D (111)) is 0.01 or more.

  In a specific aspect of the conductive particles according to the present invention, the particle size of the conductive particles is 1.0 μm or more and 10.0 μm or less.

  In a specific aspect of the conductive particles according to the present invention, the base particles are resin particles or organic-inorganic hybrid particles.

  In a specific aspect of the conductive particles according to the present invention, an outer surface of the conductive portion is subjected to a rust prevention treatment.

  In a specific aspect of the conductive particles according to the present invention, the outer surface of the conductive portion is rust-proofed with a compound having an alkyl group having 6 to 22 carbon atoms.

  In a specific aspect of the conductive particles according to the present invention, the outer surface of the conductive portion is subjected to a rust-proofing treatment with a phosphorus-free compound.

  In a specific aspect of the conductive particles according to the present invention, the conductive particles include an insulating substance disposed on an outer surface of the conductive unit.

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

  According to a wide aspect of the present invention, a first connection target member, a second connection target member, a connection portion connecting the first connection target member, and the second connection target member, A connection structure, wherein the material of the connection portion is the above-described conductive particles or a conductive material including the conductive particles and a binder resin.

  The conductive particles according to the present invention include base particles and a conductive part, and the conductive part includes a first conductive part having a crystalline structure, and a second conductive part having a crystalline structure. The first conductive portion is disposed on a surface of the base particle, and the second conductive portion is disposed on an outer surface of the first conductive portion so as to be in contact with the first conductive portion. And the absolute value of the difference between the crystallite size in the first conductive portion and the crystallite size in the second conductive portion is 5 nm or more. In addition, the conductive particles can be efficiently arranged between the electrodes. Further, the connection resistance between the electrodes can be reduced.

FIG. 1 is a sectional view showing the conductive particles according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating the conductive particles according to the second embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a conductive particle according to the third embodiment of the present invention. FIG. 4 is a sectional view showing the conductive particles according to the fourth embodiment of the present invention. FIG. 5 is a cross-sectional view illustrating a conductive particle according to a fifth embodiment of the present invention. FIG. 6 is a cross-sectional view schematically showing a connection structure using the conductive particles according to the first embodiment of the present invention.

  Hereinafter, details of the present invention will be described.

(Conductive particles)
The conductive particles according to the present invention include base particles and a conductive part. The conductive part includes a first conductive part having a crystalline structure and a second conductive part having a crystalline structure. The first conductive portion is disposed on a surface of the base particle. The second conductive portion is disposed on an outer surface of the first conductive portion so as to be in contact with the first conductive portion. The absolute value of the difference between the crystallite size (1) in the first conductive part and the crystallite size (2) in the second conductive part is 5 nm or more.

  In the conductive particles according to the present invention, since the above-described configuration is employed, when the electrodes are electrically connected, the conductive particles can be efficiently arranged between the electrodes. Further, the connection resistance between the electrodes can be reduced. The present inventors have found that in order to efficiently arrange conductive particles between electrodes and to sufficiently reduce the connection resistance between the electrodes, the crystallite size (1) and the crystallite size ( It was found that it was only necessary to make 2) different. In addition, the present inventors have found that in order to arrange conductive particles between electrodes fairly efficiently and to considerably reduce the connection resistance between electrodes, the crystallite size (1) of the adjacent conductive layer and the crystallite It has been found that merely different size (2) is not sufficient, and that the absolute value of the difference between crystallite size (1) and crystallite size (2) needs to be 5 nm or more. When the absolute value of the difference between the crystallite size (1) and the crystallite size (2) is 5 nm or more, the absolute value of the difference between the crystallite size (1) and the crystallite size (2) is less than 5 nm. As compared with a certain case, the number of conductive particles arranged between the electrodes increases, and the connection resistance between the electrodes decreases.

  In recent years, with the miniaturization of electronic devices, the distance between the line (L) where the electrode is formed and the space (S) where the electrode is not formed has become narrower. For example, there is an increasing need to electrically connect fine electrodes having an L / S of 30 μm or less / 30 μm or less. When electrically connecting electrodes having a small L / S, the use of conventional conductive particles makes it easy to reduce the number of conductive particles arranged in the line (L), so that connection resistance is likely to increase, Furthermore, since many conductive particles are easily arranged in the space (S), there is a problem that insulation failure is particularly likely to occur.

  On the other hand, by using the conductive particles according to the present invention, the electrodes can be efficiently arranged on the line (L), the connection resistance can be effectively reduced, and the space (S) can be further reduced. It becomes difficult to dispose the conductive particles, and the occurrence of insulation failure can be effectively suppressed.

  In recent years, the distance between the line (L) where the electrode is formed and the space (S) where the electrode is not formed has become narrower, and the number of lines (L) has increased. I have. The number of conductive particles arranged on one line (L) of such an electrode tends to decrease, and as a result, the connection resistance tends to increase. On the other hand, for the purpose of increasing the number of conductive particles arranged on one line (L) of such an electrode, it is conceivable to increase the content of the conductive particles in the conductive material. When the content of the conductive particles in the conductive material is increased, insulation failure easily occurs. In the present invention, the connection resistance can be sufficiently reduced without increasing the content of the conductive particles in the conductive material.

  In addition, by providing two conductive portions having different crystallite sizes so as to be in contact with each other, external stress is reduced, and even if the thickness of the entire conductive portion is reduced, cracking of the conductive portion can be suppressed. Furthermore, good conduction reliability is exhibited even when the thickness of the conductive portion is reduced in order to reduce the size of the conductive particles corresponding to a small L / S.

  The conductive particles may have another conductive layer inside the first conductive layer, and may have another conductive layer outside the second conductive layer. From the viewpoint of further lowering the connection resistance and further enhancing the conduction reliability, the number of the conductive layers is preferably 2 or more, more preferably 4 or more, preferably 10 or less, more preferably 8 or more. It is as follows.

  From the viewpoint of more efficiently arranging the conductive particles between the electrodes and further reducing the connection resistance between the electrodes, the absolute value of the difference between the crystallite size (1) and the crystallite size (2) is It is preferably at least 8 nm, more preferably at least 10 nm. The upper limit of the absolute value of the difference between the crystallite size (1) and the crystallite size (2) is not particularly limited. The absolute value of the difference between the crystallite size (1) and the crystallite size (2) may be 100 nm or less, or may be 50 nm or less.

  The crystallite size (1) in the first conductive portion located inside may be larger or smaller than the crystallite size (2) in the second conductive portion located outside.

  Methods for reducing the crystallite size in the conductive portion include fineness by increasing the phosphorus content in the Ni conductive portion, miniaturization by increasing the boron content in the Ni conductive portion, and organic gloss in the plating solution. Miniaturization by the addition of an agent, and miniaturization by the addition of a metallic brightener. In particular, an increase in the content of phosphorus and boron in the conductive portion of nickel plating and the addition of an organic brightener are effective in miniaturizing the crystallite size in the conductive portion.

  Methods for increasing the content of phosphorus and boron in the nickel-plated conductive portion include a method of lowering the pH of the plating solution to reduce the reaction rate of the nickel plating solution, a method of lowering the temperature of the nickel plating solution, and a method of increasing the nickel plating solution. A method of increasing the concentration of the phosphorus-based reducing agent and the boron-based reducing agent therein, and a method of increasing the concentration of the complexing agent in the nickel plating solution. One of these methods may be used alone, or two or more may be used in combination.

  Examples of the organic brightener include saccharin, sodium naphthalene disulfonic acid, sodium naphthalene trisulfonic acid, sodium allyl sulfonate, sodium propargyl sulfonate, butynediol, propargyl alcohol, coumarin, formalin, ethoxylated polyethyleneimine, and polyalkyl. Examples include imine, polyethyleneimine, gelatin, dextrin, thiourea, polyvinyl alcohol, polyethylene glycol, polyacrylamide, cinnamic acid, nicotinic acid, and benzalacetone. As the organic brightener, only one kind may be used, or two or more kinds may be used in combination.

  Further, preferred examples of the organic brightener include ethoxylated polyethyleneimine, polyalkylimine, polyethyleneimine, and polyethylene glycol.

  When there are a plurality of conductive particles, the crystallite size can be measured, for example, as follows.

  The conductive particles are added to “Technobit 4000” manufactured by Kulzer so as to have a content of 30% by weight and dispersed to prepare an embedded resin for conductive particle inspection. A section of the conductive particles is cut out using an ion milling apparatus (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass near the center of the conductive particles dispersed in the conductive resin inspection resin.

  Using FE-SEM-EBSP, crystal grain mapping measurement is performed on the cross section of the conductive particles. The crystallite size is determined by checking the particle size distribution chart of the crystallite size. From the obtained crystallite sizes (1) and (2), the absolute value of the difference between the crystallite size (1) in the first conductive part and the crystallite size (2) in the second conductive part is calculated. calculate. The crystallite sizes (1) and (2) may be obtained from the half-width of the diffraction peak obtained by X-ray diffraction and the Scherrer's formula, and the half-width of the diffraction peak obtained by X-ray diffraction and the Williamson-Hall equation You may ask from.

  From the viewpoint of effectively lowering the connection resistance between the electrodes, in the measurement of the entire conductive part having the crystal structure in the conductive part, the half-width of the diffraction peak obtained by X-ray diffraction and the Scherrer equation are used. It is preferable that the calculated (111), (200), (220), (311), and (222) planes have an average crystallite size of 10 nm or more. The crystallite size is determined by averaging five values of the crystallite sizes of the (111), (200), (220), (311) and (222) planes.

  From the viewpoint of effectively reducing the connection resistance between the electrodes, in the measurement of the entire conductive part having the crystal structure in the conductive part, the half width of the diffraction peak obtained by X-ray diffraction and the Williamson-Hole It is preferable that the crystallite size obtained from the equation is 10 nm or more.

  From the viewpoint of effectively reducing the connection resistance between the electrodes, in the measurement of the entire conductive part having the crystal structure in the conductive part, the crystallite size of the (220) plane in the X-ray diffraction is D (220). ), And when the crystallite size of the (111) plane is D (111), the ratio (D (220) / D (111)) is preferably 0.01 or more.

  The average value of the crystallite size in each direction can be measured as follows.

  Powder X-ray diffraction measurement is performed using an X-ray diffractometer (“RINT2500VHF” manufactured by Rigaku Corporation). The crystallite size of the (111), (200), (220), (311) and (222) planes determined from the half width of the diffraction peak obtained by X-ray diffraction using CuKα radiation and the Scherrer's formula The crystallite size is determined from the average value.

  First, a base material particle and a conductive part are provided, and the conductive part includes a first conductive part having a crystal structure and a second conductive part having a crystal structure, and the first conductive part Is disposed on the surface of the base particle, and the second conductive portion is provided on the outer surface of the first conductive portion so as to be in contact with the first conductive portion. The crystallite size (A) is measured.

  Next, a base particle and a conductive part are provided, and the conductive part is only a first conductive part having a crystal structure, and the first conductive part is provided on a surface of the base particle. The crystallite size (B) of the arranged particles is measured.

  An absolute value of a difference between a crystallite size (A) including the first conductive portion and the second conductive portion and a crystallite size (B) of only the first conductive portion is calculated.

  The crystallite size is calculated by the following Scherrer's formula.

Scherrer equation: D = Kλ / βcosθ
D: crystallite size K: Scherrer constant λ: wavelength of X-ray β: half width [rad]
θ: diffraction angle

  Further, the crystallite size in the entire conductive part having a crystal structure in the conductive part can be measured as follows.

  The powder X-ray diffraction measurement of the obtained conductive particles is performed using an X-ray diffractometer (“RINT2500VHF” manufactured by Rigaku Corporation). The half-width of the diffraction peak obtained by X-ray diffraction using CuKα rays and the crystallite size of the entire conductive part having the crystal structure in the conductive part of the conductive particles obtained by the Williamson-Hall equation are calculated.

  The crystallite size of the entire conductive part having the crystal structure in the conductive part is calculated by the following Williamson-Hall equation.

Williamson-Hall equation: Δ2θ · cos θ / λ = 0.9 / D + 2ε · sin θ / λ D: crystallite size λ: X-ray wavelength Δ2θ: half-width [rad]
θ: Diffraction angle ε: Lattice strain

  The crystallite size is plotted according to the following Williamson-Hall equation, taking 2 sin θ / λ on the horizontal axis and Δ2θ · cos θ / λ on the vertical axis. The crystallite size (D) of the entire conductive portion having the following is calculated.

  The crystallite size ratio between the crystallite size D (111) on the (111) plane and the crystallite size D (220) on the (220) plane can be measured as follows.

  The powder X-ray diffraction measurement of the obtained conductive particles is performed using an X-ray diffractometer (“RINT2500VHF” manufactured by Rigaku Corporation). The crystallite size of the conductive particles obtained on the (111) plane and the (220) plane obtained from the half width of the diffraction peak obtained by X-ray diffraction using CuKα radiation and the Scherrer equation is calculated.

  First, the half-width of the diffraction peak of the (111) plane obtained by the X-ray diffraction using the CuKα ray and the crystallite size D (111) of the obtained conductive particles of the (111) plane obtained from the Scherrer's equation are calculated. calculate.

  Next, the crystallite size D (220) of the obtained conductive particles of the (220) plane obtained from the half value width of the diffraction peak of the (220) plane obtained by X-ray diffraction using the CuKα ray and the Scherrer's formula Is calculated.

  Then, a ratio D (220) / D (111) of the obtained crystallite size of the (111) plane and the crystallite size of the (220) plane is calculated.

  The crystallite size is calculated by the following Scherrer's formula.

Scherrer equation: D = Kλ / βcosθ
D: crystallite size K: Scherrer constant λ: wavelength of X-ray β: half width [rad]
θ: diffraction angle

  From the viewpoint of further reducing the connection resistance and further improving the conduction reliability, the conductive particles preferably have a plurality of protrusions on the outer surface of the conductive portion. Further, it is preferable that the conductive particles include a plurality of core materials that protrude the surface of the conductive portion so as to form the plurality of protrusions in the conductive portion.

  From the viewpoint of further lowering the connection resistance and further improving the conduction reliability, the surface area of the projections is preferably 10% or more, more preferably 25% or more, in the total surface area of 100% of the conductive particles. , More preferably 30% or more, preferably 95% or less, more preferably 90% or less. The surface area of the portion having the protrusion can be determined by observing the conductive particles with an electron microscope or an optical microscope, and calculating the percentage of the surface area of the portion having the protrusion to the projected area of the particle. In the case of a plurality of conductive particles, the surface area of the portion where the protrusions are provided is preferably obtained by observing 10 arbitrary conductive particles with an electron microscope or a field emission scanning electron microscope (FE-SEM), It is determined by calculating the average value of the percentage of the surface area of the portion where the protrusions exist with respect to the projected area of the particles.

  Hereinafter, the present invention will be clarified by describing specific embodiments and examples of the present invention with reference to the drawings. In the drawings referred to, the size, thickness, and the like are appropriately changed from the actual size and thickness for convenience of illustration.

  FIG. 1 is a sectional view showing the conductive particles according to the first embodiment of the present invention. Note that different configurations in each embodiment can be appropriately replaced and combined.

  As shown in FIG. 1, the conductive particles 1 include base particles 2, a first conductive part 3 having a crystal structure, and a second conductive part 4 having a crystal structure. The first conductive part 3 and the second conductive part 4 form a layer interface. The absolute value of the difference between the crystallite size (1) in the first conductive part 3 and the crystallite size (2) in the second conductive part 4 is equal to or greater than the above lower limit. The first conductive part 3 and the second conductive part 4 constitute an entire conductive part. The second conductive part 4 is the outermost layer in the conductive part. In the conductive particles 1, a multilayer conductive portion is formed.

  The first conductive part 3 is arranged on the surface of the base particle 2. The first conductive part 3 is arranged between the base particles 2 and the second conductive part 4. The second conductive part 4 is arranged on the outer surface of the first conductive part 3. The second conductive part 4 is in contact with the first conductive part 3. The conductive particles 1 are coated particles in which the surface of the base particles 2 is covered with the first conductive portion 3 and the second conductive portion 4.

  Although not shown, the outer surface of the second conductive portion 4 is rust-proofed. Therefore, the conductive particles 1 are provided with a rust prevention film on the outer surface of the second conductive portion 4.

  The conductive particles 1 have no core material. The conductive particles 1 have no protrusion on the conductive surface. The conductive particles 1 are spherical. The first conductive part 3 and the second conductive part 4 have no projection on the surface. Thus, the conductive particles according to the present invention may not have conductive protrusions and may be spherical. Further, the conductive particles 1 have no insulating material. However, the conductive particles 1 may have an insulating substance disposed on the surface of the second conductive portion 4.

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

  The conductive particles 21 shown in FIG. 2 include the base particles 2, a first conductive portion 22 having a crystal structure, a second conductive portion 23 having a crystal structure, a core material 24, and an insulating material 25. Prepare. The absolute value of the difference between the crystallite size (1) in the first conductive part 22 and the crystallite size (2) in the second conductive part 23 is equal to or greater than the above lower limit. The first conductive part 22 is arranged on the surface of the base particle 2. The second conductive part 23 is disposed on the outer surface of the first conductive part 22. The second conductive part 23 is in contact with the first conductive part 22.

  Although not shown, the outer surface of the second conductive portion 23 is rust-proofed. Therefore, the conductive particles 21 are provided with a rust preventive film on the outer surface of the second conductive portion 23.

  The conductive particles 21 have protrusions 21a on the conductive surface. There are a plurality of protrusions 21a. The first conductive part 22 and the second conductive part 23 have a plurality of protrusions 22a, 23a on the outer surface. A plurality of core substances 24 are arranged on the surface of the base particles 2. The plurality of core substances 24 are embedded in the first conductive part 22 and the second conductive part 23. The core substance 24 is arranged inside the projections 21a, 22a, 23a. The first conductive part 22 and the second conductive part 23 cover a plurality of core substances 24. The outer surfaces of the first conductive portion 22 and the second conductive portion 23 are raised by the plurality of core substances 24, and projections 21a, 22a, and 23a are formed.

  Thus, the conductive particles may have a protrusion on the conductive outer surface. The conductive particles may have protrusions on the outer surface of the conductive part. In addition, the conductive particles have no protrusion on the outer surface of the inner conductive portion (such as the first conductive portion) and have protrusions on the outer surface of the outer conductive portion (such as the second conductive portion). May be.

  The conductive particles 21 have an insulating material 25 disposed on the outer surface of the second conductive portion 23. At least a part of the outer surface of the second conductive portion 23 is covered with the insulating material 25. The insulating substance 25 is formed of a material having an insulating property, and is an insulating particle. Thus, the conductive particles may have an insulating material disposed on the outer surface of the conductive part.

FIG. 3 is a cross-sectional view illustrating a conductive particle according to the third embodiment of the present invention.
The conductive particles 21A shown in FIG. 3 differ in the presence or absence of the conductive particles 21 and the core substance 24, and as a result, the shapes of the first conductive portions 22, 22A are different. Otherwise, the conductive particles 21 and 21A are formed similarly.

  The conductive particles 21A do not have a core substance. The core material is not embedded in the first conductive portion 22A. The conductive particles 21A have protrusions 21Aa on the conductive surface. The first conductive portion 22A has a plurality of protrusions 22Aa on the outer surface. As in the case of the conductive particles 21A, the core material may not be necessarily used to form the protrusions.

  FIG. 4 is a sectional view showing the conductive particles according to the fourth embodiment of the present invention.

  As shown in FIG. 4, the conductive particles 31 include the base particles 2, another conductive portion 32, a first conductive portion 33 having a crystal structure, and a second conductive portion 34 having a crystal structure. Prepare. The absolute value of the difference between the crystallite size (1) in the first conductive part 33 and the crystallite size (2) in the second conductive part 34 is equal to or greater than the above lower limit. The first conductive part 33 and the second conductive part 34 are conductive parts. The second conductive part 34 is the outermost layer in the conductive part.

  The other conductive part 32 is arranged on the surface of the base particle 2. Another conductive part 32 is arranged between the base particles 2 and the first conductive part 33. The first conductive part 33 is arranged on the outer surface of another conductive part 32. The first conductive part 33 is arranged between the other conductive part 32 and the second conductive part 34. The second conductive part 34 is arranged on the outer surface of the first conductive part 33. The second conductive part 34 is in contact with the first conductive part 33. The conductive particles 31 are coated particles in which the surface of the base particles 2 is covered with another conductive portion 32, a first conductive portion 33, and a second conductive portion 34.

  In the conductive particles 1, the first conductive portions 3 are directly laminated on the surface of the base particles 2. Like the conductive particles 31, another conductive portion 32 may be disposed between the base particles 2 and the first conductive portion 33. The first conductive portion 33 may be arranged on the surface of the base particle 2 via another conductive portion 32.

  FIG. 5 is a cross-sectional view illustrating a conductive particle according to a fifth embodiment of the present invention.

  As shown in FIG. 5, the conductive particles 41 include the base particles 2, a first conductive portion 42 having a crystal structure, a second conductive portion 43 having a crystal structure, and another conductive portion 44. Prepare. The absolute value of the difference between the crystallite size (1) in the first conductive part 42 and the crystallite size (2) in the second conductive part 43 is equal to or larger than the above lower limit. The first conductive part 42 and the second conductive part 43 are conductive parts. The other conductive part 44 is the outermost layer in the conductive part.

  The first conductive part 42 is arranged on the surface of the base particle 2. The first conductive part 42 is arranged between the base particles 2 and the second conductive part 43. The second conductive portion 43 is arranged on the outer surface of the first conductive portion 42. The second conductive part 43 is in contact with the first conductive part. A second conductive part 43 is arranged between the first conductive part 42 and another conductive part 44. The other conductive part 44 is arranged on the outer surface of the second conductive part 43. The conductive particles 41 are coated particles in which the surface of the base particles 2 is coated with the first conductive part 42, the second conductive part 43, and another conductive part 44.

  In the conductive particles 1, the second conductive part 4 is the outermost layer in the conductive part. Like the conductive particles 41, another conductive portion 44 may be arranged on the outer surface of the second conductive portion 43. However, since the effects of the present invention can be effectively obtained, the second conductive portion is preferably located at the outermost position in the conductive portion, and is preferably the outermost layer in the conductive portion.

  The conductive particles 41 may have an insulating material disposed on the surface of another conductive portion 44. It is preferable that the conductive particles 41 have an anti-rust treatment on the outer surfaces of the other conductive portions 44 and have a rust-proof film.

  Hereinafter, the details of the base particles and the conductive portion will be described. In the following description, “(meth) acryl” means one or both of “acryl” and “methacryl”, and “(meth) acrylate” means one or both of “acrylate” and “methacrylate”. means.

[Base particle]
Examples of the base particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The base particles are preferably base particles excluding metal particles, more preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. The base particles may be core-shell particles.

  The base particles are more preferably resin particles or organic-inorganic hybrid particles, and may be resin particles or organic-inorganic hybrid particles. The use of these preferred substrate particles results in conductive particles that are more suitable for electrical connection between the electrodes.

  When connecting the electrodes using the conductive particles, the conductive particles are compressed between the electrodes by placing the conductive particles between the electrodes and then pressing the electrodes. When the base particles are resin particles or organic-inorganic hybrid particles, the conductive particles are likely to be deformed at the time of the press bonding, and the contact area between the conductive particles and the electrode is increased. For this reason, the connection resistance between the electrodes is further reduced.

  Various organic substances are suitably used as the resin for forming the resin particles. Examples of the resin for forming 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 polymethyl acrylate; Alkylene terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene Oxide, polyacetal, polyimide, polyamideimide, polyetherether Tons, polyethersulfone, and polymers such as obtained by a variety of polymerizable monomer having an ethylenically unsaturated group is polymerized with one or more thereof. The resin for forming the resin particles can be designed and synthesized with resin particles having any properties at the time of compression suitable for the conductive material, and the hardness of the base particles can be easily controlled to a suitable range. Is preferably a polymer obtained by polymerizing one or more polymerizable monomers having a plurality of ethylenically unsaturated groups.

  When the resin particles are obtained by polymerizing a monomer having an ethylenically unsaturated group, the monomer having an ethylenically unsaturated group includes a non-crosslinkable monomer and a crosslinkable monomer. And a dimer.

  Examples of the non-crosslinkable monomer include styrene-based monomers such as styrene and α-methylstyrene; carboxyl-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; methyl ( (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl ( Alkyl (meth) acrylates such as meth) acrylate and isobornyl (meth) acrylate; oxygen such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate, and glycidyl (meth) acrylate (Meth) acrylates; nitrile-containing monomers such as (meth) acrylonitrile; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether and propyl vinyl ether; vinyl acids such as vinyl acetate, vinyl butyrate, vinyl laurate and vinyl stearate Esters; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; halogen-containing monomers such as trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene; Is mentioned.

  Examples of the crosslinkable monomer include tetramethylolmethanetetra (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanedi (meth) acrylate, trimethylolpropanetri (meth) acrylate, and dipentane. Erythritol 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) Polyfunctional (meth) acrylates such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, and 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanurate And silane-containing monomers such as triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane. Can be

  The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of the method include a method of performing suspension polymerization in the presence of a radical polymerization initiator, and a method of performing polymerization by swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles.

  When the base particles are inorganic particles or organic-inorganic hybrid particles other than metal particles, examples of the inorganic substance for forming the base particles include silica, alumina, barium titanate, zirconia, and carbon black. . Preferably, the inorganic substance is not a metal. The particles formed of the silica are not particularly limited. For example, after hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, baking is optionally performed. Particles obtained by performing the method are exemplified. Examples of the organic-inorganic hybrid particles include, for example, organic-inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

  The organic-inorganic hybrid particles are preferably core-shell type organic-inorganic hybrid particles having a core and a shell disposed on the surface of the core. Preferably, the core is an organic core. Preferably, the shell is an inorganic shell. From the viewpoint of effectively reducing the connection resistance between the electrodes, the base particles are preferably organic-inorganic hybrid particles having an organic core and an inorganic shell disposed on the surface of the organic core.

  Examples of the material for forming the organic core include a resin for forming the above-described resin particles.

  Examples of the material for forming the inorganic shell include an inorganic material for forming the base particles described above. The material for forming the inorganic shell is preferably silica. The inorganic shell is preferably formed by forming a metal alkoxide into a shell by a sol-gel method on the surface of the core, and then firing the shell. The metal alkoxide is preferably a silane alkoxide. It is preferable that the inorganic shell is formed of a silane alkoxide.

  When the base particles are metal particles, examples of the metal for forming the metal particles include silver, copper, nickel, silicon, gold, and titanium. However, the base particles are preferably not metal particles.

  The particle diameter of the base particles is preferably 0.1 μm or more, more preferably 0.5 μm or more, still more preferably 1 μm or more, preferably 5 μm or less, more preferably 3 μm or less. When the particle diameter of the base material particles is equal to or greater than the lower limit and equal to or less than the upper limit, small conductive particles can be obtained even when the distance between the electrodes is small and the thickness of the conductive portion is large.

  The particle diameter of the base particles indicates a diameter when the base particles are truly spherical, and indicates a maximum diameter when the base particles are not true spherical.

  For a plurality of base particles, the particle size of the base particles can be determined, for example, as an average particle size of the base particles measured by an arbitrary particle size measuring device. For example, a particle size distribution analyzer using principles such as laser light scattering, electric resistance change, and image analysis after imaging can be used. In the case of a plurality of base particles, more specifically, in the case of a plurality of base particles, as a method of measuring the particle size of the base particles, for example, a particle size distribution analyzer (manufactured by Beckman Coulter, Inc.) Multisizer 4 "), a method of measuring the particle diameter of about 100,000 particles and measuring the average particle diameter. The above average particle diameter indicates a number average particle diameter.

[Conductive part]
The conductive particles have the first conductive portion and the second conductive portion as the conductive portions. As the metal contained in the conductive portion, the first conductive portion and the second conductive portion, nickel, gold, silver, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, palladium, Examples include rhodium, ruthenium, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, tungsten, molybdenum, and tin-doped indium oxide (ITO). These metals may be alloyed in the conductive part. One of these metals may be used alone, or two or more thereof may be used in combination.

  From the viewpoint of easily adjusting the crystallite size, efficiently arranging the conductive particles between the electrodes, and effectively reducing the connection resistance between the electrodes, the first conductive portion is made of gold, copper, or the like. , Nickel or palladium, and preferably nickel. From the viewpoint of easily adjusting the crystallite size, efficiently arranging the conductive particles between the electrodes, and effectively reducing the connection resistance between the electrodes, the second conductive portion is made of gold, copper, or the like. , Nickel or palladium, and preferably nickel.

  The conductive portion containing nickel includes not only a case where only nickel is used as a metal but also a case where nickel and another metal are used. The conductive portion containing nickel may be a nickel alloy portion.

  The conductive portion containing nickel preferably contains nickel as a main metal. The content (average content) of nickel is preferably 50% by weight or more based on 100% by weight of the conductive portion containing nickel. In 100% by weight of the conductive portion containing nickel, the content of nickel is preferably 65% by weight or more, more preferably 80% by weight or more, and further preferably 90% by weight or more. When the content of nickel is equal to or more than the lower limit, the connection resistance between the electrodes is further reduced.

  The conductive portion containing nickel preferably contains copper, tungsten, or molybdenum, and more preferably contains tungsten or molybdenum. The use of copper, tungsten or molybdenum further reduces the connection resistance between the electrodes. The content of copper, the content of tungsten, and the content of molybdenum in 100% by weight of the conductive portion containing nickel are preferably 0.1% by weight or more, more preferably 5% by weight or more, and preferably 20% by weight or less. It is more preferably at most 10% by weight. When the copper content, the tungsten content, and the molybdenum content are not less than the lower limit and not more than the upper limit, the connection resistance between the electrodes is effectively reduced.

  From the viewpoint of further lowering the connection resistance between the electrodes, the conductive portion containing nickel preferably contains phosphorus or boron. The conductive portion containing nickel may contain boron. In 100% by weight of the conductive portion containing nickel, the content of phosphorus and the content of boron are preferably more than 0% by weight, more preferably 0.1% by weight or more, and still more preferably 2% by weight or more. Is at most 20% by weight, more preferably at most 15% by weight. When the content of phosphorus and the content of boron are not less than the lower limit and not more than the upper limit, the connection resistance is further reduced.

  In order to further reduce the connection resistance between the electrodes and further enhance the connection reliability between the electrodes under high temperature and high humidity, the content of phosphorus is 15% by weight in the conductive portion containing 100% by weight of nickel. More preferably, it is less than. From the viewpoint of effectively exhibiting both low connection resistance between the electrodes and high connection reliability between the electrodes under high temperature and high humidity, the conductive portion containing nickel preferably contains phosphorus, and the nickel Is contained in 100% by weight of the conductive part, the content of phosphorus is more than 0% by weight, more preferably 0.1% by weight or more, further preferably 2% by weight or more. When the content of phosphorus is equal to or more than the lower limit, the connection resistance is further reduced. From the viewpoint of further reducing the connection resistance, the content of phosphorus is preferably 13% by weight or less, more preferably 11% by weight or less, and still more preferably 3% by weight or less, in 100% by weight of the conductive portion containing nickel. is there.

  Each of the thickness of the first conductive portion and the thickness of the second conductive portion is preferably 5 nm or more, more preferably 30 nm or more, further preferably 60 nm or more, preferably 300 nm or less, more preferably 200 nm or less. , More preferably 150 nm or less, particularly preferably 130 nm or less. When the thickness of the first conductive portion and the thickness of the second conductive portion are not less than the lower limit and not more than the upper limit, the oxide film on the surface of the electrode is more effectively removed, and the connection resistance between the electrodes is reduced. Even lower. The thickness indicates the average thickness of the first conductive portion and the average thickness of the second conductive portion in the conductive particles.

  In the case of a plurality of conductive particles, the thickness of the conductive part can be determined, for example, as follows. The conductive particles are added to “Technobit 4000” manufactured by Kulzer so as to have a content of 30% by weight and dispersed to prepare an embedded resin for conductive particle inspection. A section of the conductive particles is cut out using an ion milling apparatus (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass near the center of the conductive particles dispersed in the conductive resin inspection resin.

  Then, using a field emission scanning electron microscope (FE-SEM), the image magnification is set to 50,000 times, for example, 50 conductive particles are randomly selected, and the conductive portion of each conductive particle is selected. Observed. The thickness of the conductive part in the obtained conductive particles is measured, and the result is arithmetically averaged to obtain the thickness of the conductive part.

  The total thickness of the first conductive portion and the second conductive portion is preferably 10 nm or more, more preferably 120 nm or more, preferably 600 nm or less, and more preferably 300 nm or less. When the total thickness of the first conductive portion and the second conductive portion is equal to or more than the lower limit and equal to or less than the upper limit, the oxide film on the surface of the electrode is more effectively removed, and the connection resistance between the electrodes is reduced. Is much lower.

  Further, in the present invention, since two conductive portions having different crystallite sizes are provided so as to be in contact with each other, good conduction reliability is exhibited even when the thickness of the conductive portion is reduced.

  Further, the conductive particles according to the present invention may further have another conductive portion on the base particle side or the outer surface side of the first and second conductive portions. The other conductive portion may include the same type of metal as the metal included in the first and second conductive portions, or may include a different type of metal. For example, the metals contained in the other conductive portion include Au, Ag, Cu, Pt, Fe, Pb, Al, Cr, Pa, Rh, Ru, Sb, Bi, Ge, Sn, Co, In, Ni, Examples include W, Pd, Ir, Mo, Ti, and alloys containing one or more of these.

  The particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1.0 μm or more, preferably 100 μm or less, more preferably 20 μm or less, still more preferably 10.0 μm or less, and still more preferably 5 μm or less. 0.0 μm or less, particularly preferably 4.0 μm or less. When the particle size of the conductive particles is equal to or greater than the lower limit and equal to or less than the upper limit, when the conductive particles are used to connect the electrodes, the contact area between the conductive particles and the electrodes becomes sufficiently large, and Aggregated conductive particles are less likely to be formed when forming the portion. In addition, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive portion does not easily peel off from the surface of the base particles. The particle diameter of the conductive particles may be 3.0 μm or less.

  The particle diameter of the conductive particles indicates a diameter when the conductive particles are truly spherical, and indicates a maximum diameter when the conductive particles are not truly spherical.

  With a plurality of conductive particles, the particle size of the conductive particles can be determined as follows. The conductive particles are added to “Technobit 4000” manufactured by Kulzer so as to have a content of 30% by weight and dispersed to prepare an embedded resin for conductive particle inspection. A section of the conductive particles is cut out using an ion milling apparatus (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass near the center of the conductive particles dispersed in the conductive resin inspection resin.

  Then, using a field emission scanning electron microscope (FE-SEM), for example, 50 conductive particles are randomly selected, and the conductive part and the base particle part of each conductive particle are observed. The particle size of the obtained conductive particles is measured and arithmetically averaged to obtain an average particle size of the conductive particles. The above average particle diameter indicates a number average particle diameter.

  In the method of forming the first conductive portion containing nickel by electroless plating, generally, a catalyzing step and an electroless plating step are performed. Hereinafter, an example of a method of forming an alloy plating layer containing nickel, phosphorus, and tungsten on the surface of resin particles by electroless plating will be described.

  In the catalyzing step, a catalyst serving as a starting point for forming a plating layer by electroless plating is formed on the surface of the resin particles.

  As a method for forming the catalyst on the surface of the resin particles, for example, after adding the resin particles to a solution containing palladium chloride and tin chloride, the surface of the resin particles is activated with an acid solution or an alkali solution, A method for precipitating palladium on the surface of the resin particles, and a solution containing palladium sulfate and aminopyridine, after adding the resin particles, the surface of the resin particles is activated by a solution containing a reducing agent, the resin particles Examples include a method of depositing palladium on the surface. As the reducing agent, a phosphorus-containing reducing agent is used. By using a phosphorus-containing reducing agent as the reducing agent, a conductive layer containing phosphorus can be formed. When a conductive layer containing boron is formed, a boron-containing reducing agent may be used as the reducing agent.

  In the electroless plating step, a nickel plating bath containing a nickel-containing compound, a phosphorus-containing reducing agent or a boron-containing reducing agent, a tungsten-containing compound, a complexing agent, and a stabilizer is suitably used.

  By immersing the resin particles in the nickel plating bath, nickel can be precipitated on the surface of the resin particles having the catalyst formed on the surface, and a conductive layer containing nickel, phosphorus, and tungsten can be formed.

  Examples of the nickel-containing compound include nickel sulfate and nickel chloride. The nickel-containing compound is preferably a nickel salt.

  Examples of the phosphorus-containing reducing agent include sodium hypophosphite. A boron-containing reducing agent may be used in addition to the phosphorus-containing reducing agent. Examples of the boron-containing reducing agent include dimethylamine borane, sodium borohydride and potassium borohydride.

  Examples of the tungsten-containing compound include tungsten boride and sodium tungstate.

  Preferred examples of the complexing agent include monocarboxylic acid-based complexing agents such as sodium acetate and sodium propionate; dicarboxylic acid-based complexing agents such as disodium malonate; and tricarboxylic acid-based complexing agents such as disodium succinate. Agent; hydroxy acid complexing agent such as lactic acid, DL-malic acid, Rochelle salt, sodium citrate and sodium gluconate; amino acid complexing agent such as glycine and EDTA; amine complexing agent such as ethylenediamine; maleic acid And other organic acid-based complexing agents. As the complexing agent, only one kind may be used, or two or more kinds may be used in combination.

  Examples of the stabilizer include a lead compound, a bismuth compound, and a thallium compound. Specific examples of these stabilizers include sulfates, carbonates, acetates, nitrates, and hydrochlorides of metals (lead, bismuth, and thallium) constituting the compounds. In consideration of the influence on the environment, a bismuth compound or a thallium compound is preferable.

  It is preferable that the conductive particles have a plurality of protrusions on a conductive surface. The conductive particles preferably have a plurality of protrusions on the outer surface of the conductive portion. The conductive particles preferably have a plurality of protrusions on the outer surface of the first conductive portion. The conductive particles preferably have a plurality of protrusions on the outer surface of the second conductive portion. An oxide film is often formed on the surface of the electrode connected by the conductive particles. By using the conductive particles having conductive protrusions, the conductive particles are arranged between the electrodes and then pressed, whereby the oxide film is effectively removed by the protrusions. For this reason, the electrode and the conductive particles can be more reliably brought into contact, and the connection resistance between the electrodes can be further reduced. Further, when the conductive particles have an insulating material on the surface, or when the conductive particles are dispersed in a resin and used as a conductive material, the protrusions of the conductive particles cause insulation between the conductive particles and the electrodes. Substances or resins can be effectively eliminated. For this reason, the reliability of conduction between the electrodes can be improved.

  The number of protrusions on the outer surface of the conductive portion per conductive particle is preferably 3 or more, more preferably 5 or more. The upper limit of the number of the protrusions is not particularly limited. The upper limit of the number of protrusions can be appropriately selected in consideration of the particle diameter of the conductive particles and the like.

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

  The height of the projection is a virtual line (dashed line shown in FIG. 2) of the conductive portion on the line (dashed line L1 shown in FIG. 2) connecting the center of the conductive particles and the tip of the projection when it is assumed that there is no projection. L2) The distance from the top (on the outer surface of the spherical conductive particle assuming that there is no projection) to the tip of the projection. That is, in FIG. 2, the distance from the intersection of the broken lines L1 and L2 to the tip of the projection is shown.

[Core substance]
It is preferable that the conductive particles include a plurality of core substances that protrude the surface of the conductive portion so as to form the plurality of protrusions in the conductive portion. Since the core material is embedded in the conductive portion, it is easy for the conductive portion to have a plurality of protrusions on the outer surface. However, in order to form the protrusions on the outer surfaces of the conductive particles and the conductive portion, the core material may not be necessarily used. For example, as a method of forming projections without using a core substance by electroless plating, a metal nucleus is generated by electroless plating, a metal nucleus is attached to the surface of the base material particles or the conductive portion, and furthermore, a conductive material is formed by electroless plating. And the like.

  As a method of forming the protrusions, a method of forming a conductive portion by electroless plating after attaching a core substance to the surface of the base particles, and a method of forming a conductive portion by electroless plating on the surface of the base particles And a method in which a conductive substance is formed by electroless plating, and a method in which the core substance is added in the middle of forming a conductive part by electroless plating on the surface of the base particles. For example, as a method of forming the above-mentioned protrusions without using a core substance, a method of forming a protrusion by depositing a metal nucleus with a reducing agent on a metal complex during electroless plating and adsorbing the particles on the particles, and a method of forming a protrusion by electroless plating A method in which a metal hydroxide is formed with a strong alkali solution to form a metal hydroxide in a strong alkali solution and a projection is formed by adsorbing the metal complex on the particles, and a metal nucleus is precipitated by adding a palladium complex as a catalyst during electroless plating to form a particle. And a method of forming a projection by adding a plating precipitation inhibitor during electroless plating and controlling the plating deposition growth rate. Above all, since the size of the projection nucleus is easily controlled, a method of forming the projection by depositing the metal nucleus with a reducing agent on the metal complex during electroless plating and adsorbing the metal complex on the particles is preferable.

  The step of depositing the metal nucleus of the metal complex in the electroless plating with a reducing agent and adsorbing the particles on the particles is usually performed a plurality of times, preferably once, as a series of steps of adding a reducing agent solution and dropping an electroless plating solution. The above method is more preferably performed three times or more, more preferably five times or more, to form a projection nucleus.

  Examples of the reducing agent include sodium hypophosphite, hydrazine, formalin, formic acid, dimethylamine borane, sodium borohydride and potassium borohydride.

  As a method of disposing the core material on the surface of the base particles, for example, a core material is added to a dispersion of the base particles, and the core material is added to the surface of the base particles, for example, van der Waals force. And a method in which a core substance is added to a container containing base particles, and the core substance is attached to the surface of the base particles by mechanical action such as rotation of the container. . Among them, a method of accumulating and attaching the core substance to the surface of the base particles in the dispersion liquid is preferable because the amount of the core substance to be attached is easily controlled.

  Since the core material is embedded in the conductive portion, it is easy for the conductive portion to have a plurality of protrusions on the outer surface. However, in order to form projections on the conductive surface of the conductive particles and the surface of the conductive portion, the core material may not be necessarily used.

  Examples of the material of the core substance include a conductive substance and a non-conductive substance. Examples of the conductive material include metals, metal oxides, conductive non-metals such as graphite, and conductive polymers. Examples of the conductive polymer include polyacetylene. Examples of the non-conductive substance include silica, alumina, barium titanate, and zirconia. Among them, metals are preferable because conductivity can be increased and connection resistance can be effectively reduced. The core material is preferably metal particles. As the metal that is the material of the core substance, the metals listed as the material of the conductive material can be appropriately used.

  Specific examples of the material of the core substance include barium titanate (Mohs hardness 4.5), nickel (Mohs hardness 5), silica (silicon dioxide, Mohs hardness 6 to 7), titanium oxide (Mohs hardness 7), and zirconia. (Mohs hardness 8 to 9), alumina (Mohs hardness 9), tungsten carbide (Mohs hardness 9), diamond (Mohs hardness 10) and the like. The inorganic particles are preferably nickel, silica, titanium oxide, zirconia, alumina, tungsten carbide or diamond, more preferably silica, titanium oxide, zirconia, alumina, tungsten carbide or diamond, and titanium oxide, zirconia. , Alumina, tungsten carbide or diamond, more preferably zirconia, alumina, tungsten carbide or diamond. The Mohs hardness of the material of the core substance is preferably 5 or more, more preferably 6 or more, still more preferably 7 or more, and particularly preferably 7.5 or more.

  The shape of the core material is not particularly limited. The shape of the core material is preferably a lump. Examples of the core material include a particulate mass, an aggregate of a plurality of fine particles aggregated, and an irregular mass.

  The average diameter (average particle diameter) of the core material 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 average diameter of the core material is equal to or greater than the lower limit and equal to or less than the upper limit, the connection resistance between the electrodes is effectively reduced.

  The “average diameter (average particle diameter)” of the core material indicates a number average diameter (number average particle diameter). The average diameter of the core substance can be determined by observing 50 arbitrary core substances with an electron microscope or an optical microscope and calculating an average value.

  From the viewpoint of effectively lowering the connection resistance, the average height of the plurality of protrusions is preferably 5 nm or more and 1000 nm or less. The average height of the plurality of protrusions is an average of the height of each protrusion per conductive particle.

  From the viewpoint of effectively reducing the connection resistance, the average diameter of the bases of the plurality of protrusions is preferably 5 nm or more and 1000 nm or less. The average diameter of the base of the plurality of protrusions is an average of the diameter of the base of each protrusion per conductive particle. The diameter of one base indicates the maximum diameter of a portion where the conductive portion of the conductive particle starts to protrude.

  From the viewpoint of effectively lowering the connection resistance, the ratio of the average height of the plurality of projections to the average diameter of the base of the plurality of projections is preferably 0.1 or more and 10 or less.

[Insulating material]
The conductive particles preferably include an insulating material disposed on an outer surface of the conductive unit. In this case, when the conductive particles are used for connection between the electrodes, a short circuit between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles come into contact with each other, an insulating substance is present between the plurality of electrodes, so that a short circuit between horizontally adjacent electrodes, not between upper and lower electrodes, can be prevented. When the conductive particles are pressurized by the two electrodes at the time of connection between the electrodes, the insulating material between the conductive portion of the conductive particles and the electrode can be easily removed. When the conductive particles have a plurality of protrusions on the outer surface of the conductive portion, the insulating material between the conductive portion of the conductive particles and the electrode can be easily removed.

  The insulating material is preferably an insulating particle because the insulating material can be more easily removed at the time of pressure bonding between the electrodes.

  Specific examples of the insulating resin as the material of the insulating substance include polyolefins, (meth) acrylate polymers, (meth) acrylate copolymers, block polymers, thermoplastic resins, crosslinked thermoplastic resins, and thermosetting. And a water-soluble resin.

  Examples of the polyolefins include polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer and the like. Examples of the (meth) acrylate polymer include polymethyl (meth) acrylate, polyethyl (meth) acrylate, and polybutyl (meth) acrylate. 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. Examples of the thermoplastic resin include a vinyl polymer and a vinyl copolymer. Examples of the thermosetting resin include an epoxy resin, a phenol resin, and a melamine resin. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide, and methyl cellulose. Among them, a water-soluble resin is preferable, and polyvinyl alcohol is more preferable.

  Examples of a method for disposing an insulating material on the outer surface of the conductive portion include a chemical method and a physical or mechanical method. Examples of the chemical method include an interfacial polymerization method, a suspension polymerization method in the presence of particles, and an emulsion polymerization method. Examples of the physical or mechanical method include spray drying, hybridization, electrostatic adhesion, spraying, dipping, and vacuum deposition. Among them, a method of disposing the insulating material on the surface of the conductive portion via a chemical bond is preferable because the insulating material is difficult to be removed.

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

  The average diameter (average particle diameter) of the insulating material can be appropriately selected depending on the particle diameter of the conductive particles, the use of the conductive particles, and the like. The average diameter (average particle diameter) of the insulating material is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 1 μm or less, more preferably 0.5 μm or less. When the average diameter of the insulating material is equal to or larger than the lower limit, when the conductive particles are dispersed in the binder resin, it is difficult for the conductive portions of the plurality of conductive particles to contact each other. When the average diameter of the insulating particles is equal to or less than the upper limit, when connecting between the electrodes, in order to eliminate the insulating material between the electrodes and the conductive particles, it is not necessary to increase the pressure too high, high temperature There is no need for heating.

  The “average diameter (average particle diameter)” of the insulating material indicates a number average diameter (number average particle diameter). The average diameter of the insulating substance is determined using a particle size distribution measuring device or the like.

[Rust prevention treatment]
In order to suppress the corrosion of the conductive particles and reduce the connection resistance between the electrodes, it is preferable that the outer surface of the conductive portion is subjected to a rust-proof treatment.

  From the viewpoint of further improving the conduction reliability, the outer surface of the conductive portion is preferably subjected to a rust-proof treatment with a compound having an alkyl group having 6 to 22 carbon atoms. The surface of the conductive portion may be rust-proofed with a compound containing no phosphorus, or may be rust-proofed with a compound containing an alkyl group having 6 to 22 carbon atoms and containing no phosphorus. From the viewpoint of further improving the conduction reliability, it is preferable that the outer surface of the conductive portion is rust-proofed with an alkyl phosphate compound or an alkyl thiol. By the rust prevention treatment, a rust prevention film can be formed on the outer surface of the conductive portion.

  The rust prevention film is preferably formed of a compound having an alkyl group having 6 to 22 carbon atoms (hereinafter, also referred to as compound A). The outer surface of the conductive portion is preferably surface-treated with the compound A. When the alkyl group has 6 or more carbon atoms, rust is more unlikely to occur in the entire conductive part, and rust is more difficult to occur in the conductive part in particular. When the carbon number of the alkyl group is 22 or less, the conductivity of the conductive particles increases. From the viewpoint of further increasing the conductivity of the conductive particles, the alkyl group in the compound A preferably has 16 or less carbon atoms. The alkyl group may have a linear structure or a branched structure. The alkyl group preferably has a linear structure.

  The compound A is not particularly limited as long as it has an alkyl group having 6 to 22 carbon atoms. The compound A has a phosphoric acid ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof, a phosphite ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof, and has an alkyl group having 6 to 22 carbon atoms. It is preferably at least one selected from the group consisting of alkoxysilanes, alkylthiols having an alkyl group having 6 to 22 carbon atoms, and dialkyl disulfides having an alkyl group having 6 to 22 carbon atoms. That is, the compound A having an alkyl group having 6 to 22 carbon atoms is at least one selected from the group consisting of a phosphate ester or a salt thereof, a phosphite ester or a salt thereof, an alkoxysilane, an alkylthiol, and a dialkyldisulfide. It is preferred that By using these preferred compounds A, it is possible to further reduce rust on the conductive portion. From the viewpoint of making rust less likely to occur, the compound A is preferably the phosphoric acid ester or a salt thereof, a phosphite or a salt thereof, or an alkylthiol, and the phosphoric acid ester or a salt thereof, Alternatively, a phosphite or a salt thereof is more preferable. As the compound A, only one type may be used, or two or more types may be used in combination.

  The compound A preferably has a reactive functional group capable of reacting with the outer surface of the conductive part, and preferably has a reactive functional group capable of reacting with the outer surface of the conductive part. The compound A preferably has a reactive functional group capable of reacting with the insulating material. The rust prevention film is preferably chemically bonded to the conductive part. It is preferable that the rust preventive film is chemically bonded to the insulating material. More preferably, the rust preventive film is chemically bonded to both the conductive portion and the insulating material. Due to the presence of the reactive functional group, and due to the chemical bond, peeling of the rust-preventive film is less likely to occur. It becomes more difficult to detach more unintentionally.

  Examples of the phosphate having an alkyl group having 6 to 22 carbon atoms or a salt thereof include, for example, hexyl phosphate, heptyl phosphate, monooctyl phosphate, monononyl phosphate, monodecyl phosphate, Monoundecyl phosphate, monododecyl phosphate, monotridecyl phosphate, monotetradecyl phosphate, monopentadecyl phosphate, monohexyl phosphate monosodium salt, monoheptyl phosphate monosodium phosphate Salt, monooctyl phosphate monosodium salt, monononyl phosphate monosodium salt, monodecyl phosphate monosodium salt, monoundecyl phosphate monosodium salt, monododecyl phosphate monosodium salt, Phosphate mono tridecyl ester monosodium salt, phosphate acid mono tetradecyl ester monosodium salt and phosphoric acid mono pentadecyl ester monosodium salt. You may use the potassium salt of the said phosphoric acid ester.

  Examples of the phosphite having an alkyl group having 6 to 22 carbon atoms or a salt thereof include hexyl phosphite, heptyl phosphite, monooctyl phosphite, monononyl phosphite, Monodecyl phosphate, monoundecyl phosphite, monododecyl phosphite, monotridecyl phosphite, monotetradecyl phosphite, monopentadecyl phosphite, monohexyl phosphite Ester monosodium salt, monoheptyl phosphite monosodium salt, monooctyl phosphite monosodium salt, monononyl phosphite monosodium salt, monodecyl phosphite monosodium salt, monophosphite Decyl ester monosodium salt, phosphorous acid Dodecyl ester monosodium salt, phosphorous acid mono-tridecyl ester monosodium salt, phosphorous acid mono-tetradecyl ester monosodium salt and phosphorous acid mono-pentadecyl ester monosodium salt. The potassium salt of the above phosphite may be used.

  Examples of the alkoxysilane having an alkyl group having 6 to 22 carbon atoms include, for example, hexyltrimethoxysilane, hexyltriethoxysilane, heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, and nonyltrisilane. Methoxysilane, nonyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, undecyltrimethoxysilane, undecyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, tridecyltrimethoxysilane, tridecyltriethoxy Examples include silane, tetradecyltrimethoxysilane, tetradecyltriethoxysilane, pentadecyltrimethoxysilane, and pentadecyltriethoxysilane.

  Examples of the alkylthiol having an alkyl group having 6 to 22 carbon atoms include, for example, hexylthiol, heptylthiol, octylthiol, nonylthiol, decylthiol, undecylthiol, dodecylthiol, tridecylthiol, tetradecylthiol, and pentadecyl. Thiol and hexadecyl thiol. The alkyl thiol preferably has a thiol group at the terminal of the alkyl chain.

  Examples of the dialkyl disulfide having an alkyl group having 6 to 22 carbon atoms include, for example, dihexyl disulfide, diheptyl disulfide, dioctyl disulfide, dinonyl disulfide, didecyl disulfide, diundecyl disulfide, didodecyl disulfide, ditridecyl disulfide, ditetra Decyl disulfide, dipentadecyl disulfide, dihexadecyl disulfide and the like.

(Conductive material)
The conductive material according to the present invention includes the conductive particles described above and a binder resin. The conductive particles are preferably used by being dispersed in a binder resin, and are preferably used by being dispersed in a binder resin as a conductive material. 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 circuit connecting material.

  The binder resin is not particularly limited. As the binder resin, a known insulating resin is used.

  The binder resin preferably contains a thermoplastic component (thermoplastic compound) or a curable component, and more preferably contains a curable component. Examples of the curable component include a photocurable component and a thermosetting component. The photocurable component preferably contains a photocurable compound and a photopolymerization initiator. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent. Examples of the binder resin include a vinyl resin, a thermoplastic resin, a curable resin, a thermoplastic block copolymer, and an elastomer. The binder resin may be used alone or in combination of two or more.

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

  The conductive material may be, for example, a filler, a bulking agent, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, and a light stabilizer, in addition to the conductive particles and the binder resin. And various additives such as an agent, an ultraviolet absorber, a lubricant, an antistatic agent and a flame retardant.

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

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

  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, preferably 80% by weight or less, more preferably 60% by weight. The content is more preferably 40% by weight or less, particularly preferably 20% by weight or less, and most preferably 10% by weight or less. When the content of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, conduction reliability between the electrodes is further increased.

(Connection structure)
A connection structure can be obtained by connecting the connection target members using the conductive particles or using a conductive material including the conductive particles and a binder resin.

  The connection structure includes a first connection target member, a second connection target member, and a connection portion that connects the first and second connection target members. It is preferable that the conductive particles include conductive particles described above, or a conductive material including the above-described conductive particles and a binder resin. It is preferable that the connection portion is formed of the above-described conductive particles or a connection structure formed of a conductive material including the above-described conductive particles and a binder resin. When conductive particles are used, the connection part itself is a conductive particle. That is, the first and second connection target members are connected by the conductive particles.

  FIG. 5 is a cross-sectional view schematically illustrating a connection structure using the conductive particles according to the first embodiment of the present invention.

  The connection structure 51 shown in FIG. 5 includes a first connection target member 52, a second connection target member 53, and a connection portion 54 connecting the first and second connection target members 52, 53. Prepare. The connection portion 54 is formed by curing a conductive material containing the conductive particles 1. In FIG. 5, the conductive particles 1 are schematically illustrated for convenience of illustration. Instead of the conductive particles 1, conductive particles 21, 31, 41 and the like may be used.

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

The method for manufacturing the connection structure is not particularly limited. As an example of a method for manufacturing a connection structure, the conductive material is arranged between a first connection target member and a second connection target member, and after obtaining a laminate, the laminate is heated and pressed. Method and the like. The pressure for the pressurization is about 9.8 × 10 ^{4 to} 4.9 × 10 ⁶ Pa. The heating temperature is about 120 to 220 ° C.

  Specific examples of the connection target member include electronic components such as a semiconductor chip, a capacitor and a diode, and electronic components such as a circuit board such as a printed board, a flexible printed board, a glass epoxy board, and a glass board. Preferably, the connection target member is an electronic component. The conductive particles are preferably used for electrical connection of electrodes in an electronic component.

  Examples of the electrodes provided on the connection target member include metal electrodes such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a copper electrode, a silver electrode, a molybdenum electrode, and a tungsten electrode. When the member to be connected is a flexible printed circuit board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode or a copper electrode. When the member to be connected is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, or a tungsten electrode. When the electrode is an aluminum electrode, the electrode may be an electrode formed only of aluminum, or may be an electrode in which an aluminum layer is laminated on a surface of a metal oxide layer. Examples of the material of the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited only to the following examples.

(Example 1)
As the base particles A, divinylbenzene copolymer resin particles having a particle size of 2.5 μm (“Micropearl SP-2025” manufactured by Sekisui Chemical Co., Ltd.) were prepared.

  A conductive part was formed on the surface of the base particle A as follows. The crystallite size was different between the inner first conductive part in the conductive part and the outer second conductive part in the conductive part.

  After 100 parts by weight of the base particles A was dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, the base particles A were taken out by filtering the solution. . Next, the base particles A were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surfaces of the base particles A. After sufficiently washing the base material particles A having activated surfaces, the dispersion was added to 500 parts by weight of distilled water and dispersed to obtain a dispersion.

  Next, 1 part by weight of an alumina particle slurry (average particle size: 150 nm) was added to the above dispersion over 3 minutes to obtain a suspension (1) containing the base material particles A to which the core substance was attached.

  Further, a first nickel plating solution (pH 4.0) containing 0.12 mol / L of nickel sulfate, 2.00 mol / L of sodium hypophosphite, and 0.25 mol / L of sodium citrate was prepared.

  Also, a second nickel plating solution (pH 10.0) containing 0.12 mol / L of nickel sulfate, 0.30 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  While stirring the obtained suspension (1) at 60 ° C., the first nickel plating solution was gradually dropped into the suspension (1), and electroless nickel-phosphorus plating was performed. A nickel-phosphorus conductive layer (phosphorus content: 15% by weight) was formed as a conductive portion. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-phosphorus plating ( 2) was obtained.

  Thereafter, the suspension (2) was filtered to remove the particles, and the particles were washed with water to obtain particles having a first conductive portion (thickness: 49 nm) formed on the surface of the base particle A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  Subsequently, the second nickel plating solution (pH 10.0) was gradually dropped, and electroless nickel plating was performed, and a nickel-boron conductive layer (boron content 0.6% by weight) was used as an outer second conductive portion. Was formed. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-boron plating ( 4) was obtained.

  Thereafter, the suspension (4) is filtered to remove the particles, washed with water, and dried to remove the particles having the second conductive portion (52 nm thick) disposed on the outer surface of the first conductive portion. Obtained.

  In this way, a conductive portion (thickness: 101 nm) is formed on the surface of the base material particle A, and the surface area of the portion having protrusions is 74% of the total surface area of 100% of the outer surface of the conductive portion. Particles were obtained.

(Example 2)
Conductive particles were obtained in the same manner as in Example 1 except that the alumina particle slurry was changed to a nickel slurry (150 nm).

(Example 3)
A first nickel plating solution (pH 6.0) containing 0.12 mol / L of nickel sulfate, 1.50 mol / L of sodium hypophosphite, and 0.25 mol / L of sodium citrate was prepared.

  Also, a second nickel plating solution (pH 10.0) containing 0.12 mol / L of nickel sulfate, 0.30 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  While stirring the suspension (1) obtained in Example 1 at 65 ° C., the first nickel plating solution was gradually dropped into the suspension (1), and electroless nickel-phosphorus plating was performed. Then, a nickel-phosphorus conductive layer (phosphorus content 9% by weight) was formed as a first conductive portion. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-phosphorus plating ( 2) was obtained.

  Thereafter, the suspension (2) was filtered to take out the particles, and the particles were washed with water to obtain particles having a first conductive portion (thickness: 48 nm) formed on the surface of the base particle A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  Subsequently, the second nickel plating solution (pH 10.0) is gradually dropped, and electroless nickel plating is performed, and a nickel-boron conductive layer (boron content: 0.6% by weight) is used as an outer second conductive portion. Was formed. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-boron plating ( 4) was obtained.

  Thereafter, the suspension (4) is filtered to remove the particles, washed with water, and dried to remove the particles having the second conductive portion (52 nm thick) disposed on the outer surface of the first conductive portion. Obtained.

  In this manner, a conductive portion (thickness: 100 nm) is formed on the surface of the base material particle A, and the surface area of the portion having protrusions is 74% of the total surface area of 100% of the outer surface of the conductive portion. Particles were obtained.

(Example 4)
A first nickel plating solution (pH 4.0) containing 0.12 mol / L of nickel sulfate, 2.00 mol / L of sodium hypophosphite, and 0.25 mol / L of sodium citrate was prepared.

  Further, a second nickel plating solution (pH 8.0) containing 0.12 mol / L of nickel sulfate, 2.00 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  While stirring the suspension (1) obtained in Example 1 at 60 ° C., the first nickel plating solution was gradually dropped into the suspension (1), and electroless nickel-phosphorus plating was performed. Then, a nickel-phosphorus conductive layer (phosphorus content: 15% by weight) was formed as a first conductive portion. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-phosphorus plating ( 2) was obtained.

  Thereafter, the suspension (2) was filtered to remove the particles, and the particles were washed with water to obtain particles having a first conductive portion (thickness: 49 nm) formed on the surface of the base particle A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  Subsequently, the second nickel plating solution (pH 8.0) is gradually dropped, and electroless nickel plating is performed, and a nickel-boron conductive layer (boron content: 1.2% by weight) is used as an outer second conductive portion. Was formed. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-boron plating ( 4) was obtained.

  Thereafter, the suspension (4) is filtered to take out the particles, washed with water, and dried to remove the particles having the second conductive portion (thickness: 50 nm) arranged on the outer surface of the first conductive portion. Obtained.

  In this way, a conductive portion (thickness: 99 nm) is formed on the surface of the base particle A, and a conductive portion having a projection with a surface area of 74% of the total surface area of the outer surface of the conductive portion is 100%. Particles were obtained.

(Example 5)
A first nickel plating solution (pH 6.0) containing 0.12 mol / L of nickel sulfate, 1.50 mol / L of sodium hypophosphite, and 0.25 mol / L of sodium citrate was prepared.

  Further, a second nickel plating solution (pH 8.0) containing 0.12 mol / L of nickel sulfate, 2.00 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  While stirring the suspension (1) obtained in Example 1 at 65 ° C., the first nickel plating solution was gradually dropped into the suspension (1), and electroless nickel-phosphorus plating was performed. Then, a nickel-phosphorus conductive layer (phosphorus content 9% by weight) was formed as a first conductive portion. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-phosphorus plating ( 2) was obtained.

  Thereafter, the suspension (2) was filtered to take out the particles, and the particles were washed with water to obtain particles having a first conductive portion (thickness: 48 nm) formed on the surface of the base particle A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  Subsequently, the second nickel plating solution (pH 8.0) is gradually dropped, and electroless nickel plating is performed, and a nickel-boron conductive layer (boron content: 1.2% by weight) is used as an outer second conductive portion. Was formed. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-boron plating ( 4) was obtained.

  Thereafter, the suspension (4) is filtered to take out the particles, washed with water, and dried to remove the particles having the second conductive portion (thickness: 50 nm) arranged on the outer surface of the first conductive portion. Obtained.

  In this way, a conductive part (98 nm thick) is formed on the surface of the base material particle A, and the surface area of the portion having the protrusions is 74% of the total surface area of 100% of the outer surface of the conductive part. Particles were obtained.

(Example 6)
A first nickel plating solution (pH 10.0) containing 0.12 mol / L of nickel sulfate, 0.30 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  Further, a second nickel plating solution (pH 4.0) containing 0.12 mol / L of nickel sulfate, 2.00 mol / L of sodium hypophosphite, and 0.25 mol / L of sodium citrate was prepared.

  While stirring the suspension (1) obtained in Example 1, the first nickel plating solution (pH 10) was gradually dropped into the suspension (1), and electroless nickel-boron plating was performed. A nickel-boron conductive layer (boron content: 0.6% by weight) was formed as a first conductive portion. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-boron plating ( 2) was obtained.

  Thereafter, the suspension (2) was filtered to take out the particles, and the particles were washed with water to obtain particles having the first conductive portion (thickness: 52 nm) formed on the surfaces of the base particles A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  While continuously stirring the obtained suspension (3), the above-mentioned second nickel plating solution (pH 4.0) was gradually dropped, electroless nickel-phosphorus plating was performed, and the outer second conductive portion was formed. A nickel-phosphorus conductive layer (phosphorus content: 15% by weight) was formed. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-phosphorus plating ( 4) was obtained.

  Thereafter, the suspension (4) is filtered to remove the particles, washed with water, and dried to remove the particles having the second conductive portion (49 nm thick) disposed on the outer surface of the first conductive portion. Obtained.

  In this way, a conductive portion (thickness: 101 nm) is formed on the surface of the base material particle A, and the surface area of the portion having protrusions is 74% of the total surface area of 100% of the outer surface of the conductive portion. Particles were obtained.

(Example 7)
A first nickel plating solution (pH 7.0) containing 0.12 mol / L of nickel sulfate, 0.50 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  Further, a second nickel plating solution (pH 10.0) containing 0.12 mol / L of nickel sulfate, 2.00 mol / L of hydrazinium sulfate, and 0.25 mol / L of glycine was prepared.

  While stirring the suspension (1) obtained in Example 1 at 50 ° C., the first nickel plating solution (pH 7.0) was gradually dropped into the suspension (1). -Performed boron plating to form a nickel-boron conductive layer (boron content: 2.0% by weight) as a first conductive portion. The suspension was stirred until the pH of the suspension was stabilized, and it was confirmed that the bubbling of hydrogen stopped. Thus, a suspension (2) after electroless nickel-boron plating was obtained.

  Thereafter, the suspension (2) was filtered to take out the particles, and the particles were washed with water to obtain particles having the first conductive portion (thickness: 52 nm) formed on the surfaces of the base particles A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  While stirring the obtained suspension (3) at 80 ° C., the second nickel plating solution (pH 10.0) was gradually dropped, and electroless pure nickel plating was performed. A nickel conductive layer (boron content 0%, phosphorus content 0%) was formed as a part. By filtering the above suspension, the particles were taken out, washed with water, and then stirred until the pH became stable. It was confirmed that hydrogen bubbling stopped, and the suspension after electroless pure nickel plating (4 ) Got.

  Thereafter, the suspension (4) is filtered to remove the particles, washed with water, and dried to remove the particles having the second conductive portion (49 nm thick) disposed on the outer surface of the first conductive portion. Obtained.

  In this way, a conductive portion (thickness: 101 nm) is formed on the surface of the base material particle A, and the surface area of the portion having protrusions is 74% of the total surface area of 100% of the outer surface of the conductive portion. Particles were obtained.

(Example 8)
After 100 parts by weight of the base particles A was dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, the base particles A were taken out by filtering the solution. . Next, the base particles A were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surfaces of the base particles A. After sufficiently washing the base material particles A having activated surfaces, the dispersion was added to 500 parts by weight of distilled water and dispersed to obtain a dispersion.

  Next, the suspension was added to the above dispersion so as to have a concentration of 30 ppm of thallium nitrate and 20 ppm of bismuth nitrate to obtain a suspension (1) containing the base particles A.

  A first nickel plating solution (pH 7.0) containing 0.12 mol / L of nickel sulfate, 0.50 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  Separately, a projection forming plating solution (pH 12.0) containing dimethylamine borane 2.5 mol / L and sodium hydroxide 0.05 mol / L was prepared.

  Further, a second nickel plating solution (pH 10.0) containing 0.12 mol / L of nickel sulfate, 2.00 mol / L of hydrazinium sulfate, and 0.25 mol / L of glycine was prepared.

  While stirring the obtained suspension (1) at 50 ° C., the first nickel plating solution was gradually dropped into the suspension (1), and electroless nickel-boron plating was performed. Thereafter, in order to further form projections on the conductive layer, a plating solution for projection formation was gradually dropped to form projections. The drop rate of the plating solution for forming projections was 1 ml / min. Was carried out. During the dropping of the projection forming plating solution, the generated Ni projection nuclei were adhered to the base particles while being dispersed by ultrasonic agitation, and the height of the projections was increased by nickel plating.

  A nickel-boron conductive layer (boron content: 2.0% by weight) having a protrusion containing no core substance was formed as a first conductive portion. Thereafter, the mixture was stirred until the pH was stabilized, and it was confirmed that the bubbling of hydrogen stopped. Thus, a suspension (2) after electroless nickel-boron plating was obtained.

  Thereafter, the suspension (2) was filtered to take out the particles, and the particles were washed with water to obtain particles having the first conductive portion (thickness: 52 nm) formed on the surfaces of the base particles A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

    While stirring the obtained suspension (3) at 80 ° C., the second nickel plating solution (pH 10.0) was gradually dropped, and electroless pure nickel plating was performed. A nickel conductive layer (boron content 0%, phosphorus content 0%) was formed as a part. By filtering the above suspension, the particles were taken out, washed with water, and then stirred until the pH became stable. After confirming that hydrogen bubbling stopped, the suspension after electroless pure nickel plating (4 ) Got.

  Thereafter, the suspension (4) is filtered to remove the particles, washed with water, and dried to remove the particles having the second conductive portion (49 nm thick) disposed on the outer surface of the first conductive portion. Obtained.

  In this manner, a conductive portion (thickness: 101 nm) is formed on the surface of the base particle A, and a conductive portion having a protrusion having a surface area of 90% of the total surface area of the outer surface of the conductive portion is 100%. Particles were obtained.

(Example 9)
A first nickel plating solution (pH 6.0) containing 0.09 mol / L of nickel sulfate, 1.50 mol / L of sodium hypophosphite, and 0.25 mol / L of sodium citrate was prepared.

  Further, a second nickel plating solution (pH 8.0) containing 0.09 mol / L of nickel sulfate, 2.00 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  Further, a third nickel plating solution (pH 6.0) containing 0.09 mol / L of nickel sulfate, 1.50 mol / L of sodium hypophosphite, and 0.25 mol / L of sodium citrate was prepared.

  While stirring the suspension (1) obtained in Example 1 at 65 ° C., the first nickel plating solution was gradually dropped into the suspension (1), and electroless nickel-phosphorus plating was performed. Then, a nickel-phosphorus conductive layer (phosphorus content 9% by weight) was formed as a first conductive portion. The suspension was stirred until the pH was stabilized, and it was confirmed that the bubbling of hydrogen stopped. Thus, a suspension (2) after electroless nickel-phosphorus plating was obtained.

  Thereafter, the suspension (2) was filtered to remove the particles, and the particles were washed with water to obtain particles having the first conductive portion (thickness: 33 nm) formed on the surface of the base particles A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  Subsequently, the second nickel plating solution (pH 8.0) is gradually dropped, and electroless nickel plating is performed, and a nickel-boron conductive layer (boron content: 1.2% by weight) is used as an outer second conductive portion. Was formed. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-boron plating ( 4) was obtained.

  Thereafter, the suspension (4) was filtered to take out the particles, and the particles were washed with water to obtain particles having the second conductive portion (thickness: 35 nm) formed on the surface of the first conductive portion. . After sufficiently washing the particles with water, the suspension was added to 500 parts by weight of distilled water and dispersed to obtain a suspension (5).

  While stirring the obtained suspension (5) at 65 ° C., the third nickel plating solution was gradually dropped into the suspension (5), and electroless nickel-phosphorus plating was performed. A nickel-phosphorus conductive layer (phosphorus content 9% by weight) was formed as a conductive portion. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-phosphorus plating ( 6) was obtained.

  Thereafter, the suspension (6) is filtered to remove the particles, washed with water, and dried to remove the particles having the third conductive portion (thickness 33 nm) arranged on the outer surface of the second conductive portion. Obtained.

  In this way, a conductive portion (thickness: 101 nm) is formed on the surface of the base material particle A, and the surface area of the portion having protrusions is 74% of the total surface area of 100% of the outer surface of the conductive portion. Particles were obtained.

  In the ninth embodiment, the second conductive portion can be regarded as the first conductive portion, and the third conductive portion can be regarded as the second conductive portion.

(Example 10)
After 100 parts by weight of the base particles A was dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, the base particles A were taken out by filtering the solution. . Next, the base particles A were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surfaces of the base particles A. After sufficiently washing the base material particles A having activated surfaces, the dispersion was added to 500 parts by weight of distilled water and dispersed to obtain a dispersion.

  Next, the suspension was added to the above dispersion so as to have a concentration of 30 ppm of thallium nitrate and 20 ppm of bismuth nitrate to obtain a suspension (1) containing the base particles A.

  A first nickel plating solution (pH 10.0) containing 0.09 mol / L of nickel sulfate, 0.30 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  Separately, a projection forming plating solution (pH 12.0) containing dimethylamine borane 2.5 mol / L and sodium hydroxide 0.05 mol / L was prepared.

  Further, a second nickel plating solution (pH 7.0) containing 0.09 mol / L of nickel sulfate, 0.50 mol / L of dimethylamine borane and 0.25 mol / L of sodium citrate was prepared.

  Further, a third nickel plating solution (pH 10.0) containing 0.12 mol / L of nickel sulfate, 2.00 mol / L of hydrazinium sulfate, and 0.25 mol / L of glycine was prepared.

  While stirring the obtained suspension (1) at 60 ° C., the first nickel plating solution was gradually dropped into the suspension (1), and electroless nickel-boron plating was performed. Thereafter, in order to further form protrusions on the conductive layer, a plating solution for forming protrusions was gradually dropped to form protrusions. The drop rate of the plating solution for forming projections was 1 ml / min. Was carried out. During the dropping of the projection forming plating solution, the generated Ni projection nuclei were adhered to the base particles while being dispersed by ultrasonic agitation, and the height of the projections was increased by nickel plating.

  A nickel-boron conductive layer (boron content: 0.6% by weight) having a projection containing no core substance was formed as a first conductive portion. Thereafter, the mixture was stirred until the pH was stabilized, and it was confirmed that the bubbling of hydrogen stopped. Thus, a suspension (2) after electroless nickel-boron plating was obtained.

  Thereafter, the suspension (2) was filtered to remove the particles, and the particles were washed with water to obtain particles having the first conductive portion (thickness: 33 nm) formed on the surface of the base particles A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  While stirring the obtained suspension (3) at 50 ° C., the second nickel plating solution (pH 7.0) was gradually dropped continuously, and electroless nickel plating was performed. A nickel-boron conductive layer (boron content: 2.0% by weight) was formed as a conductive portion. The above suspension was stirred until the pH was stabilized, and it was confirmed that the bubbling of hydrogen stopped. Thus, a suspension (4) after electroless nickel-boron plating was obtained.

  Thereafter, the suspension (4) was filtered to take out the particles, and the particles were washed with water to obtain particles having the second conductive portion (thickness: 35 nm) formed on the surface of the first conductive portion. . After sufficiently washing the particles with water, the suspension was added to 500 parts by weight of distilled water and dispersed to obtain a suspension (5).

  While stirring the obtained suspension (5) at 80 ° C., the above-mentioned third nickel plating solution was gradually dropped into the suspension (5), and electroless pure nickel plating was performed. A nickel conductive layer (boron content 0%, phosphorus content 0%) was formed as a part. The suspension was stirred until the pH was stabilized, and it was confirmed that the bubbling of hydrogen stopped. Thus, a suspension (6) after electroless pure nickel plating was obtained.

  Thereafter, the suspension (6) is filtered to remove the particles, washed with water, and dried to remove the particles having the third conductive portion (thickness 33 nm) arranged on the outer surface of the second conductive portion. Obtained.

  In this manner, a conductive portion (thickness: 101 nm) is formed on the surface of the base particle A, and a conductive portion having a protrusion having a surface area of 90% of the total surface area of the outer surface of the conductive portion is 100%. Particles were obtained.

  In the tenth embodiment, the second conductive portion can be regarded as the first conductive portion, and the third conductive portion can be regarded as the second conductive portion.

(Example 11)
A first nickel plating solution (pH 6.0) containing 0.07 mol / L of nickel sulfate, 1.50 mol / L of sodium hypophosphite, and 0.25 mol / L of sodium citrate was prepared.

  Further, a second nickel plating solution (pH 8.0) containing 0.07 mol / L of nickel sulfate, 2.00 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  Further, a third nickel plating solution (pH 6.0) containing 0.07 mol / L of nickel sulfate, 1.50 mol / L of sodium hypophosphite, and 0.25 mol / L of sodium citrate was prepared.

  In addition, a fourth nickel plating solution (pH 8.0) containing 0.07 mol / L of nickel sulfate, 2.00 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  While stirring the suspension (1) obtained in Example 1 at 65 ° C., the first nickel plating solution was gradually dropped into the suspension (1), and electroless nickel-phosphorus plating was performed. Then, a nickel-phosphorus conductive layer (phosphorus content 9% by weight) was formed as a first conductive portion. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-phosphorus plating ( 2) was obtained.

  Thereafter, the suspension (2) was filtered to remove the particles, and the particles were washed with water to obtain particles having the first conductive portion (25 nm in thickness) formed on the surface of the base particles A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  Subsequently, the second nickel plating solution (pH 8.0) is gradually dropped, and electroless nickel plating is performed, and a nickel-boron conductive layer (boron content: 1.2% by weight) is used as an outer second conductive portion. Was formed. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-boron plating ( 4) was obtained.

  Thereafter, the suspension (4) was filtered to take out the particles, and the particles were washed with water to obtain particles having the second conductive portion (24 nm thick) formed on the surface of the first conductive portion. . After sufficiently washing the particles with water, the suspension was added to 500 parts by weight of distilled water and dispersed to obtain a suspension (5).

  While stirring the obtained suspension (5) at 65 ° C., the third nickel plating solution was gradually dropped into the suspension (5), and electroless nickel-phosphorus plating was performed. A nickel-phosphorus conductive layer (phosphorus content 9% by weight) was formed as a conductive portion. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-phosphorus plating ( 6) was obtained.

  Thereafter, the suspension (6) was filtered to take out the particles, and the particles were washed with water to obtain particles having a third conductive portion (thickness: 25 nm) formed on the surface of the second conductive portion. . After sufficiently washing the particles with water, the suspension was added to 500 parts by weight of distilled water and dispersed to obtain a suspension (7).

  Subsequently, the fourth nickel plating solution (pH 8.0) was gradually dropped, and electroless nickel plating was performed, and a nickel-boron conductive layer (boron content 1.2% by weight) was used as an outer second conductive portion. Was formed. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-boron plating ( 8) was obtained.

  Thereafter, the suspension (8) is filtered to remove the particles, washed with water, and dried to remove the particles having the fourth conductive portion (24 nm in thickness) disposed on the outer surface of the third conductive portion. Obtained.

  In this way, a conductive part (98 nm thick) is formed on the surface of the base material particle A, and the surface area of the portion having the protrusions is 74% of the total surface area of 100% of the outer surface of the conductive part. Particles were obtained.

  In the eleventh embodiment, the second conductive portion can be regarded as a first conductive portion, the third conductive portion can be regarded as a second conductive portion, and the third conductive portion can be regarded as a first conductive portion. The fourth conductive part can be regarded as a second conductive part.

(Example 12)
After 100 parts by weight of the base particles A was dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, the base particles A were taken out by filtering the solution. . Next, the base particles A were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surfaces of the base particles A. After sufficiently washing the base material particles A having activated surfaces, the dispersion was added to 500 parts by weight of distilled water and dispersed to obtain a dispersion.

  Next, the suspension was added to the above dispersion so as to have a concentration of 30 ppm of thallium nitrate and 20 ppm of bismuth nitrate to obtain a suspension (1) containing the base particles A.

  A first nickel plating solution (pH 7.0) containing 0.07 mol / L of nickel sulfate, 0.50 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  Separately, a projection forming plating solution (pH 12.0) containing dimethylamine borane 2.5 mol / L and sodium hydroxide 0.05 mol / L was prepared.

  In addition, a second nickel plating solution (pH 10.0) containing 0.07 mol / L of nickel sulfate, 0.30 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  A first nickel plating solution (pH 7.0) containing 0.07 mol / L of nickel sulfate, 0.50 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  Further, a fourth nickel plating solution (pH 10.0) containing 0.07 mol / L of nickel sulfate, 2.00 mol / L of hydrazinium sulfate, and 0.25 mol / L of glycine was prepared.

  While stirring the obtained suspension (1) at 50 ° C., the first nickel plating solution was gradually dropped into the suspension (1), and electroless nickel-boron plating was performed. Thereafter, in order to further form projections on the conductive layer, a plating solution for projection formation was gradually dropped to form projections. The drop rate of the plating solution for forming projections was 1 ml / min. Was carried out. During the dropping of the projection forming plating solution, the generated Ni projection nuclei were adhered to the base particles while being dispersed by ultrasonic agitation, and the height of the projections was increased by nickel plating.

  A nickel-boron conductive layer (boron content: 2.0% by weight) having a protrusion containing no core substance was formed as a first conductive portion. Thereafter, the mixture was stirred until the pH was stabilized, and it was confirmed that the bubbling of hydrogen stopped. Thus, a suspension (2) after electroless nickel-boron plating was obtained.

  Thereafter, the suspension (2) was filtered to remove the particles, and the particles were washed with water to obtain particles having the first conductive portion (25 nm in thickness) formed on the surface of the base particles A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  While stirring the obtained suspension (3) at 60 ° C., the above-mentioned second nickel plating solution (pH 10.0) was gradually dropped, and electroless nickel plating was performed to form an outer second conductive portion. A nickel-boron conductive layer (boron content: 0.6% by weight) was formed. The above suspension was stirred until the pH was stabilized, and it was confirmed that the bubbling of hydrogen stopped. Thus, a suspension (4) after electroless nickel-boron plating was obtained.

  Thereafter, the suspension (4) was filtered to take out the particles, and the particles were washed with water to obtain particles having the second conductive portion (24 nm thick) formed on the surface of the first conductive portion. . After sufficiently washing the particles with water, the suspension was added to 500 parts by weight of distilled water and dispersed to obtain a suspension (5).

  While stirring the obtained suspension (5) at 60 ° C., the third nickel plating solution was gradually dropped into the suspension (5), and electroless nickel-boron plating was performed. A nickel-boron conductive layer (boron content: 0.6% by weight) was formed as a conductive portion. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-boron plating ( 6) was obtained.

  Thereafter, the suspension (6) was filtered to take out the particles, and the particles were washed with water to obtain particles having a third conductive portion (thickness: 25 nm) formed on the surface of the second conductive portion. . After sufficiently washing the particles with water, the suspension was added to 500 parts by weight of distilled water and dispersed to obtain a suspension (7).

  While stirring the obtained suspension (7) at 80 ° C., the above-mentioned fourth nickel plating solution (pH 10.0) was gradually dropped, and electroless nickel plating was performed to form an outer second conductive portion. A pure nickel conductive layer (boron content 0%, phosphorus content 0%) was formed. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. It is confirmed that hydrogen bubbling stops, and the suspension after electroless pure nickel plating (8 ) Got.

  Thereafter, the suspension (8) is filtered to remove the particles, washed with water, and dried to remove the particles having the fourth conductive portion (24 nm in thickness) disposed on the outer surface of the third conductive portion. Obtained.

  In this way, a conductive portion (98 nm in thickness) is formed on the surface of the base material particle A, and the surface area of the protrusion is 90% of the total surface area of 100% of the outer surface of the conductive portion. Particles were obtained.

  In Example 12, the second conductive part can be regarded as the first conductive part, the third conductive part can be regarded as the second conductive part, and the third conductive part can be regarded as the first conductive part. The fourth conductive part can be regarded as a second conductive part.

(Example 13)
Conductive particles were obtained in the same manner as in Example 1 except that the base particles A were different from the base particles A only in the particle diameter, and were changed to the base particles B having a particle diameter of 1.5 μm. .

(Example 14)
Conductive particles were obtained in the same manner as in Example 1, except that the base particles A were changed to the base particles C having a particle diameter of 3.5 μm, which was different from the base particles A only in the particle diameter. .

(Example 15)
Conductive particles were obtained in the same manner as in Example 1, except that the base particles A were changed to base particles D having a particle diameter of 5 μm, which was different from the base particles A only.

(Example 16)
The addition amount of the alumina particle slurry (average particle diameter: 150 nm) was changed from 1 part by weight to 0.25 part by weight, and the surface area of the protrusions was changed to 25% of the total surface area of 100% of the outer surface of the conductive part. Except for this, conductive particles were obtained in the same manner as in Example 1.

(Example 17)
The surface of divinylbenzene copolymer resin particles having a particle diameter of 2.0 μm (“Micropearl SP-202” manufactured by Sekisui Chemical Co., Ltd.) was coated with an inorganic shell (250 nm in thickness) using a condensation reaction by a sol-gel reaction. Core-shell type organic-inorganic hybrid particles (base particles E) were obtained. Conductive particles were obtained in the same manner as in Example 1, except that the base particles A were changed to the base particles E.

(Example 18)
In a 500 mL reaction vessel equipped with a stirrer and a thermometer, 300 g of a 0.13% by weight aqueous ammonia solution was placed. Next, in an aqueous ammonia solution in a reaction vessel, 4.1 g of methyltrimethoxysilane, 19.2 g of vinyltrimethoxysilane, and 0.7 g of silicone alkoxy oligomer (“X-41-1053” manufactured by Shin-Etsu Chemical Co., Ltd.) Was slowly added. After the hydrolysis and condensation reaction were allowed to proceed while stirring, 2.4 mL of a 25% by weight aqueous ammonia solution was added, and the particles were isolated from the aqueous ammonia solution, and the obtained particles were subjected to an oxygen partial pressure of 10 ⁻¹⁷ atm. The mixture was calcined at 350 ° C. for 2 hours to obtain organic-inorganic hybrid particles having a particle diameter of 2.5 μm (base particles F). Conductive particles were obtained in the same manner as in Example 1, except that the base particles A were changed to the base particles F.

(Example 19)
In a 1000 mL separable flask equipped with a 4-neck separable cover, a stirring blade, a three-way cock, a condenser tube and a temperature probe, 100 mmol of methyl methacrylate and N, N, N-trimethyl-N-2-methacryloyloxyethyl were added. A monomer composition containing 1 mmol of ammonium chloride and 1 mmol of 2,2′-azobis (2-amidinopropane) dihydrochloride was weighed into ion-exchanged water so that the solid content ratio was 5% by weight, and then 200 rpm. The mixture was stirred and polymerized at 70 ° C. for 24 hours under a nitrogen atmosphere. After the completion of the reaction, the resultant was freeze-dried to obtain insulating particles having an ammonium group on the surface, an average particle diameter of 220 nm and a CV value of 10%.

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

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

  Observation with a scanning electron microscope (SEM) revealed that only one coating layer of insulating particles was formed on the surface of the conductive particles. The coverage of the insulating particles with respect to the area 2.5 μm from the center of the conductive particles (that is, the projected area of the particle diameter of the insulating particles) was calculated by image analysis, and the coverage was 30%.

(Comparative Example 1)
After 100 parts by weight of the base particles A was dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, the base particles A were taken out by filtering the solution. . Next, the base particles A were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surfaces of the base particles A. After sufficiently washing the base material particles A having activated surfaces, the dispersion was added to 500 parts by weight of distilled water and dispersed to obtain a dispersion.

  Next, the suspension was added to the above dispersion so as to have a concentration of 10 ppm of thallium nitrate and 5 ppm of bismuth nitrate to obtain a suspension (1) containing the base particles A.

  A first nickel plating solution (pH 6.0) containing 0.12 mol / L of nickel sulfate, 1.50 mol / L of sodium hypophosphite, and 0.25 mol / L of sodium citrate was prepared.

  Further, a second nickel plating solution (pH 7.0) containing 0.12 mol / L of nickel sulfate, 4.00 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  While stirring the obtained suspension (1) at 65 ° C., the first nickel plating solution was gradually dropped into the suspension (1), and electroless nickel-phosphorus plating was performed. A nickel-phosphorus conductive layer (phosphorus content 9% by weight) was formed as a conductive portion. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-phosphorus plating ( 2) was obtained.

  Thereafter, the suspension (2) was filtered to take out the particles, and the particles were washed with water to obtain particles having a first conductive portion (thickness: 48 nm) formed on the surface of the base particle A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  Subsequently, the second nickel plating solution (pH 7.0) was gradually dropped, and electroless nickel plating was performed, and a nickel-boron conductive layer (boron content: 2.2% by weight) was used as an outer second conductive portion. Was formed. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-boron plating ( 4) was obtained.

  Thereafter, the suspension (4) is filtered to take out the particles, washed with water, and dried to remove the particles having the second conductive portion (thickness: 53 nm) on the outer surface of the first conductive portion. Obtained.

  In this manner, the conductive portion (thickness: 101 nm) is formed on the surface of the base material particle A, and the conductive portion in which the surface area of the protrusion is 0% is 100% of the total surface area of the outer surface of the conductive portion. Particles were obtained.

(Comparative Example 2)
A first nickel plating solution (pH 4.0) containing 0.12 mol / L of nickel sulfate, 2.00 mol / L of sodium hypophosphite, and 0.25 mol / L of sodium citrate was prepared.

  Further, a second nickel plating solution (pH 7.0) containing 0.12 mol / L of nickel sulfate, 4.00 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  While stirring the suspension (1) obtained in Example 1 at 60 ° C., the first nickel plating solution was gradually dropped into the suspension (1), and electroless nickel-phosphorus plating was performed. Then, a nickel-phosphorus conductive layer (phosphorus content: 15% by weight) was formed as a first conductive portion. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-phosphorus plating ( 2) was obtained.

  Thereafter, the suspension (2) was filtered to remove the particles, and the particles were washed with water to obtain particles having a first conductive portion (thickness: 49 nm) formed on the surface of the base particle A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  Subsequently, the second nickel plating solution (pH 7.0) was gradually dropped, and electroless nickel plating was performed, and a nickel-boron conductive layer (boron content: 2.2% by weight) was used as an outer second conductive portion. Was formed. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-boron plating ( 4) was obtained.

  Thereafter, the suspension (4) is filtered to take out the particles, washed with water, and dried to remove the particles having the second conductive portion (thickness: 53 nm) on the outer surface of the first conductive portion. Obtained.

  In this manner, a conductive portion (102 nm in thickness) is formed on the surface of the base material particle A, and a conductive portion having a projection with a surface area of 74% of the total surface area of 100% of the outer surface of the conductive portion. Particles were obtained.

(Comparative Example 3)
A first nickel plating solution (pH 6.0) containing 0.12 mol / L of nickel sulfate, 1.50 mol / L of sodium hypophosphite, and 0.25 mol / L of sodium citrate was prepared.

  Further, a second nickel plating solution (pH 7.0) containing 0.12 mol / L of nickel sulfate, 4.00 mol / L of dimethylamine borane, and 0.25 mol / L of sodium citrate was prepared.

  While stirring the suspension (1) obtained in Example 1 at 65 ° C., the first nickel plating solution was gradually dropped into the suspension (1), and electroless nickel-phosphorus plating was performed. Then, a nickel-phosphorus conductive layer (phosphorus content 9% by weight) was formed as a first conductive portion. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-phosphorus plating ( 2) was obtained.

  Thereafter, the suspension (2) was filtered to take out the particles, and the particles were washed with water to obtain particles having a first conductive portion (thickness: 48 nm) formed on the surface of the base particle A. After sufficiently washing the particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a suspension (3).

  Subsequently, the second nickel plating solution (pH 7.0) was gradually dropped, and electroless nickel plating was performed, and a nickel-boron conductive layer (boron content: 2.2% by weight) was used as an outer second conductive portion. Was formed. By filtering the above suspension, the particles are taken out, washed with water, and then stirred until the pH is stabilized. After confirming that hydrogen bubbling stops, the suspension after electroless nickel-boron plating ( 4) was obtained.

  Thereafter, the suspension (4) is filtered to take out the particles, washed with water, and dried to remove the particles having the second conductive portion (thickness: 53 nm) on the outer surface of the first conductive portion. Obtained.

  In this way, a conductive portion (thickness: 101 nm) is formed on the surface of the base material particle A, and the surface area of the portion having protrusions is 74% of the total surface area of 100% of the outer surface of the conductive portion. Particles were obtained.

(Evaluation)
(1) Crystallite size in particle cross section The obtained conductive particles were added to “Technobit 4000” manufactured by Kulzer Co., Ltd. so as to have a content of 30% by weight, dispersed, and embedded for conductive particle inspection. A resin was made. The cross section of the conductive particles was cut out using an ion milling apparatus (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass near the center of the conductive particles dispersed in the conductive resin inspection embedded resin.

  Using FE-SEM-EBSP (manufactured by TSL), grain mapping measurement was performed on the cross section of the conductive particles. The crystallite size was determined by checking the particle size distribution chart of the crystallite size. The absolute value of the difference between the crystallite size (1) in the first conductive part and the crystallite size (2) in the second conductive part, the crystallite size (2) in the second conductive part, The absolute value of the difference between the crystallite size (3) in the third conductive part and the crystallite size (3) in the third conductive part and the crystallite size (4) in the fourth conductive part The absolute value of the difference was calculated. The crystallite sizes (1), (2), (3), and (4) can be obtained from the half value width of the diffraction peak obtained by X-ray diffraction and the Williamson-Hall equation, and similar values can be obtained.

(2) Average value of crystallite size in each direction Powder X-ray diffraction measurement was performed using an X-ray diffractometer (“RINT2500VHF” manufactured by Rigaku Corporation). The crystallite size of the (111), (200), (220), (311) and (222) planes determined from the half width of the diffraction peak obtained by X-ray diffraction using CuKα radiation and the Scherrer's formula The crystallite size was calculated from the average value.

  The XRD measurement conditions were 45 kV, 50 mA, and a scan rate of 4.0 deg / min. The measurement was performed with a scan step of 0.02 deg and a measurement range of 5.0 to 110.0 deg in 2θ.

  First, the crystallite size (A) of the particles including the conductive part in the outermost layer was measured.

  Next, the crystallite size (B) of the above-mentioned outermost layer before the formation of the conductive portion was measured.

  The absolute value of the difference between the crystallite size (A) of the particles including the conductive part in the outermost layer and the crystallite size (B) of the particles before the formation of the conductive part in the outermost layer was calculated.

  The crystallite size was calculated by the following Scherrer's formula.

D = Kλ / βcosθ
D: crystallite size K: Scherrer constant λ: wavelength of X-ray β: half width [rad]
θ: diffraction angle

(3) Crystallite size in the entire conductive part having the crystal structure in the conductive part (whole conductive part) Powder of conductive particles obtained by using an X-ray diffractometer (“RINT2500VHF” manufactured by Rigaku Corporation) X-ray diffraction measurement was performed. The half width of the diffraction peak obtained by X-ray diffraction using CuKα radiation and the crystallite size of the entire conductive part having the crystal structure in the conductive part of the conductive particles obtained by the Williamson-Hall equation were calculated. In Examples 1 to 8 and Examples 13 to 19 and Comparative Examples 1 to 3, the entirety of the conductive portion having the crystal structure in the conductive portion is the entire first and second conductive portions. In the ninth and tenth embodiments, the entire conductive portion having the crystal structure in the conductive portion is the entire first, second, and third conductive portions. In the eleventh and twelfth embodiments, the entire conductive portion having the crystal structure in the conductive portion is the entire first, second, third, and fourth conductive portions.

  The XRD measurement conditions were 45 kV, 50 mA, and a scan rate of 4.0 deg / min. The measurement was performed with a scan step of 0.02 deg and a measurement range of 5.0 to 110.0 deg in 2θ.

  The crystallite size was calculated by the following Williamson-Hall equation.

Δ2θ · cos θ / λ = 0.9 / D + 2ε · sin θ / λ
D: crystallite size λ: wavelength of X-ray Δ2θ: half width [rad]
θ: Diffraction angle ε: Lattice strain

  The crystallite size is plotted by taking 2 sin θ / λ on the horizontal axis and Δ2θ · cos θ / λ on the vertical axis in the above-mentioned Williamson-Hall equation. Calculated.

(4) Crystallite size ratio of crystallite size D (111) on (111) plane and crystallite size D (220) on (220) plane Obtained using an X-ray diffractometer (“RINT2500VHF” manufactured by Rigaku Corporation). The obtained conductive particles were subjected to powder X-ray diffraction measurement. The crystallite size of the conductive particles obtained on the (111) plane and the (220) plane obtained from the half width of the diffraction peak obtained by X-ray diffraction using CuKα radiation and the Scherrer equation was calculated.

  The XRD measurement conditions were 45 kV, 50 mA, and a scan rate of 4.0 deg / min. The measurement was performed with a scan step of 0.02 deg and a measurement range of 5.0 to 110.0 deg in 2θ.

  First, the half-width of the diffraction peak of the (111) plane obtained by the X-ray diffraction using the CuKα ray and the crystallite size D (111) of the obtained conductive particles of the (111) plane obtained from the Scherrer's equation are calculated. Calculated.

  Next, the crystallite size D (220) of the obtained conductive particles of the (220) plane obtained from the half value width of the diffraction peak of the (220) plane obtained by X-ray diffraction using the CuKα ray and the Scherrer's formula Was calculated.

  Then, the ratio D (220) / D (111) of the obtained crystallite size of the (111) plane and the crystallite size of the (220) plane was calculated.

  The crystallite size was calculated by the following Scherrer's formula.

D = Kλ / βcosθ
D: crystallite size K: Scherrer constant λ: wavelength of X-ray β: half width [rad]
θ: diffraction angle

(5) Content of Nickel, Phosphorus, and Boron in 100% by Weight of First, Second, Third, and Fourth Conducting Parts The Kulzer Co., Ltd. manufactured the obtained conductive particles so that the content was 30% by weight. Was added to “Technobit 4000” and dispersed to prepare an embedded resin for conductive particle inspection. The cross section of the conductive particles was cut out by using an ion milling apparatus (“IM4000” manufactured by Hitachi High-Technologies) so as to pass near the center of the conductive particles dispersed in the conductive resin inspection resin.

  The contents of nickel, boron, and phosphorus in the first, second, third, and fourth conductive portions were measured by FE-TEM / EDX analysis (“JEM-ARM200F” manufactured by JEOL) for the cross section of the conductive particles. It was measured. The average content in each of the first, second, third, and fourth conductive portions was determined.

(6) Cracking of conductive part 1 g of the obtained conductive particles, 60 g of toluene, and zirconia balls having a diameter of 0.5 mm were mixed and stirred with a stirring blade having a diameter of 3 cm at 400 rpm for 2 minutes. After drying the solid-liquid separated particles, SEM observation was performed. The number of conductive particles having a crack in the conductive portion out of 1,000 conductive particles was counted, and the crack in the conductive portion was determined based on the following criteria.

[Judgment criteria for cracks in conductive part]
○: Ratio of the number of conductive particles having cracks in the conductive portion is less than 3% ○: Ratio of the number of conductive particles having cracks in the conductive portion is 3% or more and less than 10% △: The ratio of the number of the conductive particles having cracks is 10% or more and less than 20%. ×: The ratio of the number of the conductive particles having cracks in the conductive portion is 20% or more.

(7) Accuracy of arrangement of conductive particles on electrodes (capture rate)
The obtained conductive particles were added to "Structbond XN-5A" manufactured by Mitsui Chemicals, Inc. so as to have a content of 10% by weight, and dispersed to prepare an anisotropic conductive paste.

  A transparent glass substrate having on its upper surface an ITO electrode pattern having an L / S of 30 μm / 30 μm was prepared. Further, a semiconductor chip having a copper electrode pattern having an L / S of 30 μm / 30 μm on the lower surface was prepared.

  On the transparent glass substrate, an anisotropic conductive paste immediately after the preparation was applied to a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the semiconductor chip was laminated on the anisotropic conductive paste layer such that the electrodes faced each other. Then, while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer becomes 185 ° C., the pressure heating head is placed on the upper surface of the semiconductor chip, and the pressure of 3 MPa is applied to remove the anisotropic conductive paste layer Curing was performed at 185 ° C. to obtain a connection structure.

  In the obtained connection structure, the ratio (%) of the number of the conductive particles arranged on the electrode to the total number of 100% by weight of the conductive particles contained in the connection portion formed of the conductive material was evaluated. . The arrangement accuracy of the conductive particles on the electrodes was determined based on the following criteria.

[Judgment criteria for placement accuracy of conductive particles on electrodes]
○: Ratio of the number of conductive particles arranged on the electrode is 80% or more ○: Ratio of the number of conductive particles arranged on the electrode is 70% or more and less than 80% △: On the electrode The ratio of the number of conductive particles arranged is 60% or more and less than 70%. ×: The ratio of the number of conductive particles arranged on the electrode is less than 60%.

(8) Conduction Reliability The connection resistance between the upper and lower electrodes of the 15 connection structures obtained in the above evaluation (7) was measured by a four-terminal method. The average value of the two connection resistances was calculated. The connection resistance can be obtained by measuring the voltage when a constant current flows from the relationship of voltage = current × resistance. The connection resistance was determined based on the following criteria.

[Criteria for connection resistance (continuity reliability)]
○: Average connection resistance is 8.0Ω or less ○: Average connection resistance exceeds 8.0Ω and 10.0Ω or less △: Average connection resistance exceeds 10.0Ω and 15.0Ω or less × : Average connection resistance exceeds 15.0Ω

(9) Insulation Reliability Fifteen connection structures obtained in the above evaluation (7) were left at 85 ° C. and 85% humidity for 500 hours. In the connection structure after the standing, 5 V was applied between adjacent electrodes, the resistance was measured at 25 points, and the average value of the insulation resistance was calculated. The insulation reliability was determined based on the following criteria.

[Criteria for insulation reliability]
○: Insulation resistance is 1000 MΩ or more ○: Insulation resistance is 100 MΩ or more and less than 1000 MΩ △: Insulation resistance is 10 MΩ or more and less than 100 MΩ ×: Insulation resistance is less than 10 MΩ

  The results are shown in Table 1 below.

  Although specific examples of the conductive particles that have not been subjected to the rust prevention treatment are shown, it has been confirmed that when the rust prevention treatment is performed, the conduction reliability is further improved. For the rust prevention treatment, a compound having an alkyl group having 6 to 22 carbon atoms is preferably used, and a compound containing no phosphorus is preferably used.

1, 21, 21A, 31, 41 ... conductive particles 2 ... base particles 3, 22, 22A, 33, 42 ... first conductive parts 4, 23, 34, 43 ... second conductive parts 21a, 21Aa, 22a, 22Aa, 23a ... Projection 24 ... Core material 25 ... Insulating material 32, 44 ... Other conductive parts 51 ... Connection structure 52 ... First connection target member 52a ... First electrode 53 ... Second connection target member 53a: second electrode 54: connecting portion

Claims (23)

Comprising a base particle and a conductive part,
The conductive portion includes a first conductive portion having a crystal structure, and a second conductive portion having a crystal structure,
The first conductive portion is disposed on the surface of the base particles,
The second conductive portion is disposed on an outer surface of the first conductive portion so as to be in contact with the first conductive portion,
Conductive particles, wherein an absolute value of a difference between a crystallite size in the first conductive portion and a crystallite size in the second conductive portion is 5 nm or more.   The conductive particles according to claim 1, wherein a crystallite size in the first conductive portion is smaller than a crystallite size in the second conductive portion.   The conductive particles according to claim 1, wherein a crystallite size in the first conductive portion is larger than a crystallite size in the second conductive portion.   The conductive particles according to claim 1, wherein the first conductive portion includes nickel.   The conductive particles according to claim 1, wherein the second conductive portion includes nickel.   The conductive particles according to claim 1, wherein the conductive portion has a plurality of protrusions on an outer surface.   The conductive particles according to claim 6, wherein the surface area of the portion having the protrusion is 10% or more based on 100% of the total surface area of the outer surface of the conductive portion.   The conductive particle according to claim 6, wherein an average height of the plurality of protrusions is 5 nm or more and 1000 nm or less.   The conductive particles according to any one of claims 6 to 8, wherein the bases of the plurality of protrusions have an average diameter of 5 nm or more and 1000 nm or less.   The conductive particles according to any one of claims 6 to 9, wherein a ratio of an average height of the plurality of protrusions to an average diameter of a base of the plurality of protrusions is 0.1 or more and 10 or less.   The conductive particles according to any one of claims 6 to 10, further comprising a plurality of core substances that protrude the surface of the conductive portion so as to form the plurality of protrusions in the conductive portion.   The conductive particles according to claim 11, wherein the material of the core substance has a Mohs hardness of 5 or more.   In the measurement of the entire conductive portion having a crystal structure in the conductive portion, the (111) plane, the (200) plane, and the (220) plane obtained from the half value width of the diffraction peak obtained by X-ray diffraction and Scherrer's formula The conductive particles according to any one of claims 1 to 12, wherein a crystallite size based on an average of crystallite sizes of the (311) plane and the (222) plane is 10 nm or more.   In a measurement of the entire conductive part having a crystal structure in the conductive part, a half-width of a diffraction peak obtained by X-ray diffraction and a crystallite size determined from a Williamson-Hall equation are 10 nm or more. 14. The conductive particles according to any one of 1 to 13.   In the measurement of the entire conductive part having the crystal structure in the conductive part, the crystallite size of the (220) plane in X-ray diffraction is set to D (220), and the crystallite size of the (111) plane is set to D (111). The conductive particles according to any one of claims 1 to 14, wherein the ratio (D (220) / D (111)) is 0.01 or more.   The conductive particles according to any one of claims 1 to 15, wherein the particle size of the conductive particles is 1.0 µm or more and 10.0 µm or less.   The conductive particles according to any one of claims 1 to 16, wherein the base particles are resin particles or organic-inorganic hybrid particles.   The conductive particles according to any one of claims 1 to 17, wherein an outer surface of the conductive portion has been subjected to a rust prevention treatment.   The conductive particles according to claim 18, wherein an outer surface of the conductive portion is rust-proofed by a compound having an alkyl group having 6 to 22 carbon atoms.   The conductive particles according to claim 18 or 19, wherein an outer surface of the conductive portion has been subjected to a rust-preventive treatment with a compound containing no phosphorus.   The conductive particles according to any one of claims 1 to 20, further comprising an insulating material disposed on an outer surface of the conductive portion.   A conductive material comprising the conductive particles according to any one of claims 1 to 21 and a binder resin. A first connection target member;
A second member to be connected;
The first connection target member, and the second connection target member,
A connection structure, wherein a material of the connection portion is the conductive particles according to any one of claims 1 to 21, or a conductive material including the conductive particles and a binder resin.

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