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

Abstract

The present invention provides conductive particles which are less susceptible to agglomeration, and which improve conduction reliability of an obtained connection structure even in cases where conductive connection is performed at relatively low temperatures.　Conductive particles (1) according to the present invention each have a base material particle (2) and a conductive part (3) that is disposed on the surface of the base material particle (2). The conductive part (3) contains tin and indium. When an X-ray diffraction spectrum of the conductive part (3) is measured, a peak exists in the range of 20.5° to 23.5° and in the range of 32.5° to 34°, and the ratio P of the area of the peak that is present in the range of 20.5° to 23.5° to the area of the peak that is present in the range of 32.5° to 34° is 0.0001 to 0.2 inclusive.

Description

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

[0001] The present invention relates to a conductive particle having a base particle and a conductive portion disposed on the surface of the base particle, and a method for producing the same. The present invention also relates to a conductive material and a connection structure using the conductive particle.

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

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

[0004] In recent years, in order to reduce the burden on substrates and the like, mounting (conductive connection) is sometimes performed in a low-temperature environment (for example, 150°C or lower). In order to improve the conductive connectivity when performing conductive connection at low temperatures, a method of melting the metal on the surface of conductive particles to bond them to electrodes is sometimes used. In this case, when conventional conductive particles are used to electrically connect electrodes at a relatively low temperature to produce a connection structure, there is a problem in that the metal in the conductive particles is difficult to melt, and the conductive reliability cannot be sufficiently increased (the connection resistance cannot be sufficiently reduced).

[0005] Conductive particles with a low-melting-point metal (low-melting metal) disposed on the surface may be used so that the metal in the conductive particles can sufficiently melt even when mounted at low temperatures.

[0006] Patent Document 1 listed below discloses conductive microparticles in which an inner metal layer having a melting point of 900°C or higher is formed on the surface of a base microparticle, and an outer metal layer having a melting point of 350°C or lower is formed outside the inner metal layer.

[0007] Japanese Patent Application Publication No. 5-36306

[0008] In the conductive particles described in Patent Document 1, a plurality of conductive particles may aggregate during storage. Aggregation of conductive particles poses a problem in that connection resistance cannot be sufficiently reduced. With conventional conductive particles, it is difficult to enhance both the performance of suppressing aggregation of conductive particles and improving the electrical conductivity reliability of a connection structure obtained by conductive connection at a relatively low temperature.

[0009] An object of the present invention is to provide conductive particles and a method for producing the same that can suppress aggregation of the conductive particles and improve the electrical conductivity reliability of the resulting connection structure even when conductive connection is made at a relatively low temperature. Another object of the present invention is to provide a conductive material and a connection structure using the conductive particles.

[0010] This specification discloses the following conductive particles, a method for manufacturing conductive particles, a conductive material, and a connection structure.

[0011] Item 1. A conductive particle having a base particle and a conductive portion disposed on a surface of the base particle, the conductive portion containing tin and indium, wherein when an X-ray diffraction spectrum of the conductive portion is measured, peaks are present in a region of 20.5° or more and 23.5° or less and a region of 32.5° or more and 34° or less, and the ratio P of the area of ​​the peak present in the region of 20.5° or more and 23.5° or less to the area of ​​the peak present in the region of 32.5° or more and 34° or less is 0.0001 or more and 0.2 or less.

[0012] Item 2. The conductive particles according to Item 1, wherein the total content of tin and indium is 5% by weight or more based on 100% by weight of the conductive particles.

[0013] Item 3. The conductive particles according to Item 1 or 2, wherein the ratio P is 0.001 or more and 0.2 or less.

[0014] Item 4. The conductive particles according to Item 3, wherein the ratio P is 0.01 or more and 0.2 or less.

[0015] Item 5. The conductive particles according to Item 3, wherein the ratio P is 0.005 or more and 0.01 or less.

[0016] Item 6. The conductive particles according to any one of Items 1 to 5, wherein the particle diameter of the conductive particles is 1 μm or more and 100 μm or less.

[0017] Item 7. The conductive particle according to any one of Items 1 to 6, wherein the conductive portion has a plurality of protrusions on its outer surface.

[0018] Item 8. The conductive particle according to any one of Items 1 to 7, wherein the conductive portion contains a metal salt, and the average content of the metal salt in a region extending from the outer surface of the conductive portion to a thickness of half the thickness of the conductive portion is greater than 50% by weight, relative to 100% by weight of the metal salt content in the entire conductive portion.

[0019] Item 9. The conductive particle according to any one of Items 1 to 8, wherein the conductive portion contains a metal salt, and the metal salt contains indium hydroxide.

[0020] Item 10. A method for producing conductive particles according to any one of Items 1 to 9, comprising forming the conductive portion on a surface of the base particle by electroless plating.

[0021] Item 11. A conductive material comprising the conductive particles according to any one of items 1 to 9 and a binder resin.

[0022] Item 12. A connection structure comprising a first connection-target member having a first electrode on its surface, a second connection-target member having a second electrode on its surface, and a connection portion connecting the first connection-target member and the second connection-target member, wherein a material of the connection portion contains the conductive particles according to any one of Items 1 to 9, and the first electrode and the second electrode are electrically connected by the conductive particles.

[0023] The conductive particle according to the present invention is a conductive particle having a base particle and a conductive portion disposed on the surface of the base particle. In the conductive particle according to the present invention, the conductive portion contains tin and indium. When the X-ray diffraction spectrum of the conductive portion of the conductive particle according to the present invention is measured, peaks are present in the region of 20.5° to 23.5° and the region of 32.5° to 34°. When the X-ray diffraction spectrum of the conductive portion of the conductive particle according to the present invention is measured, the ratio P of the area of ​​the peak present in the region of 20.5° to 23.5° to the area of ​​the peak present in the region of 32.5° to 34° is 0.0001 to 0.2. Because the conductive particle according to the present invention has the above configuration, aggregation of the conductive particles is suppressed, and the electrical conductivity reliability of the resulting connection structure can be improved even when conductive connection is made at a relatively low temperature.

[0024] FIG. 1 is a cross-sectional view showing a conductive particle according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a conductive particle according to a second embodiment of the present invention. FIG. 3 is a cross-sectional view showing a conductive particle according to a third embodiment of the present invention. FIG. 4 is a cross-sectional view showing a conductive particle according to a fourth embodiment of the present invention. FIG. 5 is a schematic diagram for explaining a region of 1 / 2 thickness from the outer surface of a conductive portion toward the inside. FIG. 6 is a cross-sectional view schematically showing a connection structure using a conductive particle according to the first embodiment of the present invention. FIG. 7 is an X-ray diffraction spectrum of the conductive portion of the conductive particle obtained in Example 7.

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

[0026] (Conductive Particles) The conductive particles according to the present invention are conductive particles having a base particle and a conductive portion disposed on the surface of the base particle. In the conductive particles according to the present invention, the conductive portion contains tin and indium. In the conductive particles according to the present invention, when the X-ray diffraction spectrum of the conductive portion is measured, peaks are present in the region of 20.5° to 23.5° and the region of 32.5° to 34°. In the conductive particles according to the present invention, when the X-ray diffraction spectrum of the conductive portion is measured, the ratio P of the area of ​​the peak present in the region of 20.5° to 23.5° to the area of ​​the peak present in the region of 32.5° to 34° is 0.0001 to 0.2.

[0027] The conductive particles according to the present invention have the above-described configuration, and therefore, even when a conductive connection is made at a relatively low temperature (even when electrodes are electrically connected), the conductive portion melts, thereby improving the reliability of conduction. That is, the reliability of conduction between upper and lower electrodes that should be connected can be improved. Furthermore, because the conductive portion melts quickly, the reliability of insulation between lateral electrodes that should not be connected can also be ensured.

[0028] In conventional conductive particles having a low-melting metal disposed on the surface, the surface is very soft, and therefore multiple conductive particles may aggregate during storage. When the conductive particles aggregate, there is a problem that the connection resistance cannot be sufficiently reduced. On the other hand, the conductive particles according to the present invention have the above-described configuration, and therefore can suppress the aggregation of the conductive particles.

[0029] Furthermore, when a conductive connection is made using solder particles in which both the center portion and the outer surface portion of the conductive portion are formed of solder, the entire particle is likely to melt and collapse, resulting in insufficient bonding when there is variation in the distance between the upper and lower electrodes, and the reliability of the electrical connection between the upper and lower electrodes that should be connected cannot be improved. Furthermore, there is a problem that the collapsed solder particles protrude from between the electrodes, causing a short circuit between horizontal electrodes that should not be connected. Furthermore, with conductive materials containing solder particles, multiple solder particles tend to aggregate and settle within the conductive material during storage, which makes it difficult to sufficiently reduce connection resistance.

[0030] On the other hand, since the conductive particles according to the present invention have the above-mentioned configuration, they can improve the reliability of conduction between upper and lower electrodes that should be connected and the reliability of insulation between lateral electrodes that should not be connected, compared to solder particles in which both the central portion and the outer surface portion of the conductive portion are formed of solder. Furthermore, since the conductive particles according to the present invention have the above-mentioned configuration, they can suppress the aggregation of the conductive particles.

[0031] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

[0032] FIG. 1 is a cross-sectional view showing a conductive particle according to a first embodiment of the present invention.

[0033] 1 includes a base particle 2 and a conductive portion 3 disposed on the surface of the base particle 2. The conductive portion 3 coats the surface of the base particle 2. The conductive particle 1 is a coated particle in which the surface of the base particle 2 is coated with the conductive portion 3.

[0034] In the conductive particle 1, the conductive portion 3 is a single-layer conductive layer. In the conductive particle, the conductive portion may be a single-layer conductive layer or a multi-layer conductive layer composed of two or more layers. In the conductive particle, the conductive portion may cover the entire surface of the base particle, or may cover only a portion of the surface.

[0035] In the conductive particle 1, the conductive portion 3 contains tin and indium. When the X-ray diffraction spectrum of the conductive particle 1 is measured, peaks exist in a region of 20.5° or more and 23.5° or less and a region of 32.5° or more and 34° or less. When the X-ray diffraction spectrum of the conductive particle 1 is measured, the ratio P of the area of ​​the peak existing in the region of 20.5° or more and 23.5° or less to the area of ​​the peak existing in the region of 32.5° or more and 34° or less is 0.0001 or more and 0.2 or less.

[0036] In the conductive particle 1, the conductive portion 3 is an alloy layer containing an alloy of two or more metals. In the above conductive particle, the conductive portion may be an alloy layer containing an alloy of two types of metals, an alloy layer containing an alloy of three types of metals, or an alloy layer containing an alloy of three or more metals. In the above conductive particle, the conductive portion may be an alloy layer containing an alloy of 10 or less types of metals, or an alloy layer containing an alloy of five or less types of metals.

[0037] FIG. 2 is a cross-sectional view showing a conductive particle according to a second embodiment of the present invention.

[0038] 2 has a base particle 2 and a conductive portion 13 disposed on the surface of the base particle 2. The conductive portion 13 coats the surface of the base particle 2. The conductive particle 11 is a coated particle in which the surface of the base particle 2 is coated with the conductive portion 13.

[0039] In the conductive particle 11, the conductive portion 13 is a conductive layer having a two-layer structure. The conductive portion 13 has a first conductive portion 13A and a second conductive portion 13B. The first conductive portion 13A is disposed on the surface of the base particle 2. The first conductive portion 13A is in contact with the base particle 2. The first conductive portion 13A is disposed between the base particle 2 and the second conductive portion 13B. The second conductive portion 13B is disposed on the surface of the first conductive portion 13A. The second conductive portion 13B is in contact with the first conductive portion 13A. The second conductive portion 13B is the outermost conductive portion in the conductive particle 11.

[0040] In the conductive particle 11, the conductive portion 13 contains tin and indium. In the conductive particle 11, the first conductive portion 13A may contain tin, and the second conductive portion 13B may contain tin. In the conductive particle 11, the first conductive portion 13A may contain indium, and the second conductive portion 13B may contain indium. In the conductive particle 11, the first conductive portion 13A may contain tin and indium, and the second conductive portion 13B may contain tin and indium.

[0041] In the conductive particle 11, when the X-ray diffraction spectrum of the conductive portion 13 is measured, peaks exist in a region of 20.5° or more and 23.5° or less and a region of 32.5° or more and 34° or less. In the conductive particle 11, when the X-ray diffraction spectrum of the conductive portion 13 is measured, the ratio P of the area of ​​the peak existing in the region of 20.5° or more and 23.5° or less to the area of ​​the peak existing in the region of 32.5° or more and 34° or less is 0.0001 or more and 0.2 or less.

[0042] In the conductive particle, the conductive portion may have an alloy layer containing an alloy of two or more metals. In the conductive particle, the first conductive portion may be an alloy layer containing an alloy of two or more metals, and the second conductive portion may be an alloy layer containing an alloy of two or more metals. In the conductive particle, the first conductive portion may be an alloy layer containing an alloy of 10 or less metals, or may be an alloy layer containing an alloy of 5 or less metals. In the conductive particle, the second conductive portion may be an alloy layer containing an alloy of 10 or less metals, or may be an alloy layer containing an alloy of 5 or less metals.

[0043] FIG. 3 is a cross-sectional view showing a conductive particle according to a third embodiment of the present invention.

[0044] 3 has a base particle 2 and a conductive portion 23 disposed on the surface of the base particle 2. The conductive portion 23 coats the surface of the base particle 2. The conductive particle 21 is a coated particle in which the surface of the base particle 2 is coated with the conductive portion 23.

[0045] In the conductive particle 21, the conductive portion 23 is a single conductive layer.

[0046] The conductive particles 21 (particularly the conductive portions 23) have a plurality of protrusions 23a on their surfaces. In the conductive particles 21, a core material is not disposed on the surface of the base particle 2. The conductive particles 21 do not have a core material.

[0047] In the conductive particle 21, the conductive portion 23 contains tin and indium. When the X-ray diffraction spectrum of the conductive portion 23 of the conductive particle 21 is measured, peaks exist in a region of 20.5° or more and 23.5° or less and a region of 32.5° or more and 34° or less. When the X-ray diffraction spectrum of the conductive portion 23 of the conductive particle 21 is measured, the ratio P of the area of ​​the peak existing in the region of 20.5° or more and 23.5° or less to the area of ​​the peak existing in the region of 32.5° or more and 34° or less is 0.0001 or more and 0.2 or less.

[0048] FIG. 4 is a cross-sectional view showing a conductive particle according to a fourth embodiment of the present invention.

[0049] The conductive particle 31 shown in FIG. 4 has a base particle 2, a conductive portion 33 disposed on the surface of the base particle 2, and a plurality of core materials .

[0050] In the conductive particle 31, the conductive portion 33 is a single conductive layer.

[0051] The conductive particle 31 (particularly, the conductive portion 33) has a plurality of protrusions 33a on its surface. A plurality of core materials 34 are arranged on the surface of the base particle 2. The plurality of core materials 34 are embedded in the conductive portion 33. The core materials 34 are arranged inside the protrusions 33a. The conductive portion 33 covers the plurality of core materials 34. The outer surface of the conductive portion 33 is raised by the plurality of core materials 34, forming the protrusions 33a.

[0052] In the conductive particle 31, the conductive portion 33 contains tin and indium. When the X-ray diffraction spectrum of the conductive portion 33 of the conductive particle 31 is measured, peaks exist in a region of 20.5° or more and 23.5° or less and a region of 32.5° or more and 34° or less. When the X-ray diffraction spectrum of the conductive portion 33 of the conductive particle 31 is measured, the ratio P of the area of ​​the peak existing in the region of 20.5° or more and 23.5° or less to the area of ​​the peak existing in the region of 32.5° or more and 34° or less is 0.0001 or more and 0.2 or less.

[0053] Other details of the conductive particles will be described below.

[0054] In this specification, "(meth)acrylate" refers to acrylate and methacrylate, "(meth)acrylic" refers to acrylic and methacrylic, and "(meth)acryloyl" refers to acryloyl and methacryloyl.

[0055] When the X-ray diffraction spectrum of the conductive portion of the conductive particles is measured, peaks are present in the region of 20.5° to 23.5° and the region of 32.5° to 34°. Because the conductive particles have the above-described configuration, aggregation of the conductive particles can be suppressed despite the indium content.

[0056] When the X-ray diffraction spectrum of the conductive part has peaks in the region of 20.5° to 23.5° and the region of 32.5° to 34°, it is preferable that the height of the highest peak in the region of 32.5° to 34° is higher than the height of the highest peak in the region of 20.5° to 23.5°. In this case, the volume resistivity of the conductive particles can be reduced, and as a result, the initial conductivity reliability of the resulting connection structure can be improved.

[0057] When the X-ray diffraction spectrum of the conductive portion of the conductive particle is measured, at least one peak is present in the region of 20.5° to 23.5°. When the X-ray diffraction spectrum of the conductive portion of the conductive particle is measured, at least one peak is present in the region of 32.5° to 34°. When the X-ray diffraction spectrum of the conductive portion of the conductive particle is measured, one peak or multiple peaks may be present in the region of 20.5° to 23.5°. When the X-ray diffraction spectrum of the conductive portion of the conductive particle is measured, one peak or multiple peaks may be present in the region of 32.5° to 34°. When the X-ray diffraction spectrum of the conductive portion of the conductive particle is measured, a peak may be present in a region other than the region of 20.5° to 23.5° and the region of 32.5° to 34°. In this specification, "the presence of a peak" in a certain region means that the entire peak (from the start point to the end point) is present in that region.

[0058] The X-ray diffraction spectrum of the conductive portion can be measured using an X-ray diffractometer (e.g., RINT2500VHF manufactured by Rigaku Corporation). The X-ray diffraction spectrum of the conductive portion can be measured, for example, under conditions of 45 kV, 50 mA, a scan rate of 4.0 deg / min, a scan step of 0.02 deg, and a measurement range 2θ of 5.0 deg to 60.0 deg. The X-ray diffraction spectrum of the conductive portion is preferably measured at intervals of 0.10° or less, more preferably at intervals of 0.05° or less, even more preferably at intervals of 0.02° or less, and particularly preferably at intervals of less than 0.02°. The X-ray diffraction spectrum of the conductive portion is preferably measured in a range encompassing the entire range from 20.5° to 34°.

[0059] In the conductive particle, when the X-ray diffraction spectrum of the conductive portion is measured, the ratio P of the area of ​​the peak present in the region of 20.5° or more and 23.5° or less to the area of ​​the peak present in the region of 32.5° or more and 34° or less is 0.0001 or more and 0.2 or less.

[0060] When the X-ray diffraction spectrum of the conductive portion is measured, the ratio of the area of ​​the peak present in the region of 20.5° to 23.5° to the area of ​​the peak present in the region of 32.5° to 34° is defined as the ratio P (area of ​​the peak present in the region of 20.5° to 23.5° / area of ​​the peak present in the region of 32.5° to 34°). The ratio P is 0.0001 or more and 0.2 or less. The ratio P is preferably 0.0005 or more, more preferably 0.0007 or more, even more preferably 0.001 or more, even more preferably 0.003 or more, particularly preferably 0.005 or more, and preferably 0.15 or less, more preferably 0.10 or less, and even more preferably 0.05 or less. When the ratio P is equal to or greater than the lower limit, aggregation of the conductive particles can be more effectively suppressed. When the ratio P is equal to or less than the upper limit, the volume resistivity of the conductive particles can be further reduced, and the electrical conductivity reliability of the resulting connection structure can be further improved even when conductive connection is made at a relatively low temperature.

[0061] From the viewpoint of more effectively suppressing the aggregation of the conductive particles, the ratio P is preferably 0.01 or more, and more preferably 0.01 to 0.2. From the viewpoint of further reducing the volume resistivity of the conductive particles and further improving the conductivity reliability of the resulting connection structure even when conductive connection is performed at a relatively low temperature, the ratio P is preferably 0.01 or less, and more preferably 0.001 to 0.01. From the viewpoint of more effectively suppressing the aggregation of the conductive particles, further reducing the volume resistivity of the conductive particles, and further improving the conductivity reliability of the resulting connection structure even when conductive connection is performed at a relatively low temperature, the ratio P is preferably 0.005 to 0.01. The range of the ratio P can be set by appropriately selecting the lower limit and the upper limit.

[0062] The area of ​​the peaks present in each region in the X-ray diffraction spectrum of the conductive part can be measured, for example, as follows. In the X-ray diffraction spectrum of the conductive part, the average value of the region in which no peaks are present in the obtained spectrum is calculated and used as the baseline count value. Next, the sum of the values ​​obtained by dividing the baseline count value from each count value of the peaks present in the region of 20.5° to 23.5° is used as the "area of ​​the peaks present in the region of 20.5° to 23.5°." Similarly, the sum of the values ​​obtained by dividing the baseline count value (background noise) from the count values ​​of the peaks present in the region of 32.5° to 34° is used as the "area of ​​the peaks present in the region of 32.5° to 34°."

[0063] Examples of methods for easily controlling the ratio P within a preferred range include the following: A method of incorporating a metal salt, as described below, when forming a conductive portion. A method of adjusting the amount of metal salt in a plating solution during electroless plating when forming a conductive portion. A method of adjusting the amount (concentration, dropping speed, dropping time, etc.) of a strong acid or strong base added to precipitate a metal salt during the electroless plating. More specifically, examples of methods for increasing the numerical value of the ratio P include the following: A method of increasing the amount of metal salt added when forming a conductive portion. A method of increasing the amount of metal salt in a plating solution during electroless plating when forming a conductive portion. A method of increasing the amount of strong acid or strong base added to precipitate a metal salt during the electroless plating (by increasing the concentration or dropping speed, or by extending the dropping time).

[0064] The ratio P can be controlled by the content of the metal salt in the conductive portion. Specifically, the value of the ratio P increases by increasing the content of the metal salt in the conductive portion relative to the metal contained in the conductive portion as a simple metal or alloy. The value of the ratio P decreases by decreasing the content of the metal salt in the conductive portion relative to the metal contained in the conductive portion as a simple metal or alloy.

[0065] In addition, when there are multiple peaks in the region of 20.5° or more and 23.5° or less, or in the region of 32.5° or more and 34° or less, the area of ​​the peak present in the region of 20.5° or more and 23.5° or less and the area of ​​the peak present in the region of 32.5° or more and 34° or less indicate the total area of ​​all peaks present in the region.

[0066] The particle diameter of the conductive particles is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more, and is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less. When the particle diameter of the conductive particles is equal to or more than the above lower limit and equal to or less than the above upper limit, good electrical conductivity reliability and insulating reliability can be achieved.

[0067] The particle diameter of the conductive particles is preferably an average particle diameter, and the average particle diameter indicates a number-average particle diameter. The particle diameter of the conductive particles can be determined, for example, by observing 50 random conductive particles with an electron microscope or an optical microscope and calculating the average particle diameter of each conductive particle, or by performing laser diffraction particle size distribution measurement.

[0068] From the viewpoint of more effectively exerting the effects of the present invention, the coefficient of variation (CV value) of the particle diameter of the conductive particles is preferably 10% or less, more preferably 5% or less. The lower limit of the coefficient of variation (CV value) of the particle diameter of the conductive particles is not particularly limited. The coefficient of variation (CV value) of the particle diameter of the conductive particles may be 0% or more, or may be 1% or more.

[0069] The coefficient of variation (CV value) can be measured as follows.

[0070] CV value (%) = (ρ / Dn) × 100, where ρ: standard deviation of particle diameter of conductive particles, and Dn: average particle diameter of conductive particles.

[0071] The shape of the conductive particles is not particularly limited, and may be spherical, or may be a shape other than spherical, such as flat.

[0072] From the viewpoint of further suppressing the occurrence of cracks when stress is applied, the 10% K value of the conductive particles is preferably 500 N / mm２ More preferably, 1000 N / mm ２ or more, preferably 17000 N / mm ２ or less, more preferably 13,000 N / mm ２ The following is the result.

[0073] The 10% K value of the conductive particles can be measured, for example, as follows.

[0074] Using a micro-compression tester, the conductive particles are compressed with a cylindrical (diameter 50 μm, made of diamond) smooth indenter end face at 25°C under the condition of applying a maximum test load of 60 mN for 20 seconds. The load value (N) and compression displacement (mm) at this time are measured. From the obtained measured values, the 10% K value (compressive elastic modulus) can be calculated using the following formula. As the micro-compression tester, for example, a Fischerscope H-100 manufactured by Fischer can be used.

[0075] 10% K value (N / mm ２ ) = (3 / 2 １／２ ) F.S. －３／２ ・R －１／２ F: Load value (N) when the conductive particle is compressed and deformed by 10%; S: Compression displacement (mm) when the conductive particle is compressed and deformed by 10%; R: Radius of the conductive particle (mm).

[0076] The conductive particles are dispersed in a binder resin and are suitably used to obtain a conductive material.

[0077] <Base Particles> Examples of the base particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The base particles are preferably base particles excluding metal particles, and more preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. The base particles may be core-shell particles having a core and a shell disposed on the surface of the core. The core may be an organic core, and the shell may be an inorganic shell.

[0078] Examples of materials for 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; polycarbonate, polyamide, phenol-formaldehyde resin, melamine-formaldehyde resin, benzoguanamine-formaldehyde resin, urea-formaldehyde resin, phenolic resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyamide-imide, polyether ether ketone, polyether sulfone, and divinylbenzene polymer. The divinylbenzene polymer may be a divinylbenzene copolymer. Examples of the divinylbenzene copolymer include a divinylbenzene-styrene copolymer and a divinylbenzene-(meth)acrylic acid ester copolymer. The material of the resin particles is preferably a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group, since this allows the hardness of the resin particles to be easily controlled within a suitable range.

[0079] When the resin particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group may be a non-crosslinkable monomer or a crosslinkable monomer.

[0080] Examples of the non-crosslinkable monomer include styrene-based monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride; alkyl (meth)acrylate compounds such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; and alkyl (meth)acrylate compounds such as 2-hydroxyethyl (meth)acrylate and glycerol (meth)acrylate. nitrile-containing monomers such as (meth)acrylonitrile; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; vinyl acid ester compounds such as vinyl acetate, vinyl butyrate, vinyl laurate, and vinyl stearate; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; and halogen-containing monomers such as trifluoromethyl (meth)acrylate, pentafluoroethyl (meth)acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene.

[0081] Examples of the crosslinkable monomer include tetramethylolmethane tetra(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol poly(meth)acrylate, pentaerythritol tetra(meth)acrylate, glycerol tri(meth)acrylate, glycerol di(meth)acrylate, (poly)ethylene glycol Examples of suitable crosslinkable monomers include polyfunctional (meth)acrylate compounds such as 1,4-butanediol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; triallyl (iso)cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, and silane-containing monomers such as γ-(meth)acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane. From the viewpoint of maintaining the shape of the flux-containing particles even at the glass transition temperature of the resin particles, the crosslinkable monomer is preferably (poly)ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, or dipentaerythritol poly(meth)acrylate.

[0082] The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method, such as a suspension polymerization method in the presence of a radical polymerization initiator, or a method in which non-crosslinked seed particles are used to swell and polymerize the monomer together with the radical polymerization initiator.

[0083] When the base particles are inorganic particles other than metals or organic-inorganic hybrid particles, the inorganic materials for forming the base particles include silica, alumina, barium titanate, zirconia, and carbon black.The inorganic materials are preferably not metals.The particles formed by silica include, for example, particles obtained by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, and then optionally baking the particles.The organic-inorganic hybrid particles include, for example, organic-inorganic hybrid particles formed by crosslinked alkoxysilyl polymers and acrylic resins.

[0084] The organic-inorganic hybrid particles are preferably core-shell organic-inorganic hybrid particles having a core and a shell disposed on the surface of the core. The core is preferably an organic core. The shell is preferably an inorganic shell. From the viewpoint of effectively reducing the connection resistance between electrodes, the base particle is preferably an organic-inorganic hybrid particle having an organic core and an inorganic shell disposed on the surface of the organic core.

[0085] Examples of the material for the organic core include the materials for the resin particles described above.

[0086] Examples of materials for the inorganic shell include the inorganic substances listed as materials for the base particle described above. The material for the inorganic shell is preferably silica. The inorganic shell is preferably formed by forming a shell-like substance from a metal alkoxide on the surface of the core by a sol-gel method and then firing the shell-like substance. The metal alkoxide is preferably a silane alkoxide. The inorganic shell is preferably formed from a silane alkoxide.

[0087] When the base particles are metal particles, examples of the metal that is the material of the metal particles include silver, copper, nickel, silicon, gold, and titanium.

[0088] The particle diameter of the base particle is preferably 0.5 μm or more, more preferably 9.5 μm or more, and preferably 100 μm or less, more preferably 49.95 μm or less, and even more preferably 39.95 μm or less. When the particle diameter of the base particle is above the lower limit and below the upper limit, the distance between the electrodes becomes small, and even if the thickness of the conductive part is increased, conductive particles with small particle diameters can be obtained. Furthermore, when the conductive part is formed on the surface of the base particle, the particles are less likely to aggregate, and aggregated conductive particles are less likely to be formed.

[0089] The shape of the base particles is not particularly limited, and may be spherical, or may be a shape other than spherical, such as flat.

[0090] The particle diameter of the base particle is preferably an average particle diameter, and the average particle diameter indicates a number average particle diameter. The particle diameter of the base particle is determined using a particle size distribution measuring device or the like. The particle diameter of the base particle is preferably determined by observing 50 random base particles with an electron microscope or optical microscope and calculating the average value. When measuring the particle diameter of the base particle of the conductive particle, for example, it can be measured as follows.

[0091] The conductive particles were added to Kulzer's Technovit 4000 so that the content was 30% by weight, and dispersed to prepare an embedding resin for testing containing the conductive particles. An ion milling machine (Hitachi High-Technologies Corporation's IM4000) was used to cut out a cross section of the conductive particles (substrate particles) dispersed in the embedding resin for testing, passing through the vicinity of the center of the particles. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 1000x, 50 conductive particles were randomly selected, and the substrate particles of each conductive particle were observed. The particle diameter of the substrate particles in each conductive particle was measured, and the arithmetic average was calculated to determine the particle diameter of the substrate particles. The image magnification may be changed, for example, to 100x, depending on the particle diameter of the conductive particles.

[0092] <Core Material and Protrusions> The conductive particles preferably have a plurality of protrusions on the outer surface of the conductive portion. Generally, an oxide film is often formed on the surface of an electrode that contacts the conductive particles. When conductive particles having protrusions on their surfaces are used, the protrusions can effectively remove the oxide film during conductive connection. This ensures more reliable contact between the electrode and the conductive particles, allowing the contact area between the conductive particles and the electrode to be sufficiently increased, thereby more effectively reducing connection resistance. Furthermore, when the conductive particles are dispersed in a binder and used as a conductive material, the protrusions of the conductive particles can more effectively remove the binder between the conductive particles and the electrode. This allows the contact area between the conductive particles and the electrode to be sufficiently increased, thereby more effectively reducing connection resistance.

[0093] Methods for forming protrusions on the surface of conductive particles include a method in which a core substance is attached to the surface of a base particle and then a conductive portion is formed by electroless plating, and a method in which a conductive portion is formed on the surface of a base particle by electroless plating, then a core substance is attached, and then a conductive layer is formed by electroless plating.

[0094] Examples of methods for adhering a core substance to the surface of a base particle include a method of adding a core substance to a dispersion of the base particle and accumulating and adhering the core substance to the surface of the base particle by, for example, van der Waals forces, and a method of adding a core substance to a container containing the base particle and adhering the core substance to the surface of the base particle by mechanical action such as rotating the container. Among these, the method of adhering a core substance to the surface of the base particle in a dispersion is preferred because it is easy to control the amount of core substance to be adhered.

[0095] The conductive particle may have a first conductive portion on the surface of the base particle and a second conductive portion on the surface of the first conductive portion. A core material may be attached to the surface of the base particle. In this case, it is preferable that the core material is coated with the first conductive portion and the second conductive portion. Also, a core material may be attached to the surface of the first conductive portion. In this case, it is preferable that the core material is coated with the second conductive portion.

[0096] The material constituting the core material includes conductive materials and non-conductive materials. The conductive material includes, for example, conductive non-metals such as metals, metal oxides, and graphite, and conductive polymers. The conductive polymer includes polyacetylene. The non-conductive material includes silica, alumina, and zirconia. From the viewpoint of increasing conductivity, the material constituting the core material is preferably a metal. The core material is preferably a metal particle.

[0097] Examples of the metal include gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, as well as alloys composed of two or more metals, such as tin-lead alloys, tin-copper alloys, tin-silver alloys, tin-lead-silver alloys, and tungsten carbide. Of these, nickel, copper, silver, and gold are preferred. The metal constituting the core material may be the same as or different from the metal constituting the conductive portion (conductive layer).

[0098] The shape of the core material is not particularly limited. The core material is preferably in the form of a mass. Examples of the core material include a particulate mass, an aggregate of multiple microparticles, and an amorphous mass.

[0099] The average height of the plurality of protrusions is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 0.1 μm or more, and is preferably 0.9 μm or less, and more preferably 0.5 μm or less. When the average height of the protrusions is equal to or greater than the above lower limit and equal to or less than the above upper limit, the connection resistance between the electrodes can be effectively reduced, and the electrical connection reliability can be further improved.

[0100] <Conductive Portion> In the present invention, the conductive particle has a conductive portion on its surface. The conductive portion is disposed on the surface of the base particle. The conductive portion contains tin and indium. The conductive portion may contain an indium salt in addition to indium contained as a simple metal or an alloy.

[0101] The conductive portion may or may not contain a metal other than tin and indium. Examples of metals constituting the conductive portion include gold, silver, copper, tin, platinum, palladium, zinc, lead, aluminum, cobalt, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, as well as alloys thereof. Furthermore, tin-doped indium oxide (ITO) may be used as the metal. Only one of the above metals may be used, or two or more may be used in combination.

[0102] In the conductive particle, the conductive portion may be formed of one layer or multiple layers. The conductive portion may have a laminated structure of two or more layers. From the viewpoint of more effectively exerting the effects of the present invention, when the conductive portion is formed of multiple layers, it is preferable that tin is contained in the outermost layer of the conductive portion, it is preferable that indium is contained in the outermost layer of the conductive portion, and it is more preferable that tin and indium are contained in the outermost layer of the conductive portion.

[0103] From the viewpoint of more effectively exerting the effects of the present invention, it is preferable that the conductive portion of the conductive particle has an alloy layer containing an alloy of tin and indium. The alloy layer may contain an alloy of tin, indium, and a metal other than tin and indium. The alloy layer may contain an alloy of two or more types of metals, an alloy of three or more types of metals, an alloy of 10 or less types of metals, or an alloy of five or less types of metals. The range of the number of types of metals contained in the alloy layer can be set by appropriately selecting the lower limit and the upper limit.

[0104] The thickness of the conductive portion is preferably 0.001 μm or more, more preferably 0.01 μm or more, even more preferably 0.1 μm or more, and preferably 0.75 μm or less, more preferably 0.5 μm or less, and even more preferably 0.3 μm or less. When the thickness of the conductive portion is equal to or greater than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited. The thickness of the conductive portion is the average thickness per conductive particle. When the conductive portion is formed of one layer, the thickness of the conductive portion is the thickness of one layer. When the conductive portion is formed of multiple layers, the thickness of the conductive portion is the total thickness of the multiple layers.

[0105] The thickness of the layer containing tin and indium is preferably 0.001 μm or more, more preferably 0.01 μm or more, even more preferably 0.1 μm or more, and preferably 0.75 μm or less, more preferably 0.5 μm or less, and even more preferably 0.3 μm or less. When the thickness of the layer containing tin and indium is equal to or greater than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited. The thickness of the layer containing tin and indium is the average thickness per conductive particle. When the conductive portion is formed of multiple layers and includes a layer containing tin and indium and a layer not containing tin and indium, the thickness of the layer containing tin and indium is the thickness of only the layer containing tin and indium.

[0106] In the conductive particle, when the conductive portion has an alloy layer containing an alloy of tin and indium, from the viewpoint of more effectively exerting the effects of the present invention, it is preferable that the alloy layer containing an alloy of tin and indium is the outermost layer of the conductive portion.

[0107] The thickness of the alloy layer containing an alloy of tin and indium is preferably 0.001 μm or more, more preferably 0.01 μm or more, even more preferably 0.1 μm or more, and preferably 0.75 μm or less, more preferably 0.5 μm or less, and even more preferably 0.3 μm or less. When the thickness of the alloy layer containing an alloy of tin and indium is equal to or greater than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited. Note that the thickness of the alloy layer containing an alloy of tin and indium is the average thickness per conductive particle.

[0108] The thickness of the conductive portion, the thickness of the layer containing tin and indium, and the thickness of the alloy layer containing an alloy of tin and indium can be measured, for example, by observing the cross section of the conductive particle using a transmission electron microscope (TEM).

[0109] From the viewpoint of improving the thermal cycle characteristics of the resulting connection structure, it is preferable that the conductive portion of the conductive particles does not contain bismuth or contains 10% by weight or less of bismuth per 100% by weight of the conductive portion, and it is more preferable that the conductive portion does not contain bismuth.

[0110] From the viewpoint of exerting the effects of the present invention more effectively, the tin content in 100% by weight of the conductive particles is preferably 2% by weight or more, more preferably 5% by weight or more, and even more preferably 10% by weight or more, and is preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 30% by weight or less.

[0111] From the viewpoint of exerting the effects of the present invention more effectively, the tin content in the conductive particles, relative to 100% by weight of the conductive portion, is preferably 5% by weight or more, more preferably 10% by weight or more, even more preferably 18% by weight or more, and is preferably 70% by weight or less, more preferably 60% by weight or less, even more preferably 50% by weight or less.

[0112] From the viewpoint of more effectively exerting the effects of the present invention, the indium content, based on 100% by weight of the conductive particles, is preferably 2% by weight or more, more preferably 5% by weight or more, even more preferably 10% by weight or more, and preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 30% by weight or less. The indium content includes the content of indium contained as a simple metal. The indium content includes the content of indium contained as an alloy. In other words, when the conductive portion contains an alloy of indium and another metal (such as tin), the indium content includes the content of indium in the alloy of indium and the other metal. When the conductive portion contains an indium salt, the indium content does not include the content of indium in the indium salt.

[0113] From the viewpoint of exerting the effects of the present invention more effectively, the indium content in 100% by weight of the conductive portion of the conductive particle is preferably 5% by weight or more, more preferably 10% by weight or more, even more preferably 18% by weight or more, and is preferably 70% by weight or less, more preferably 60% by weight or less, even more preferably 50% by weight or less.

[0114] From the viewpoint of more effectively exerting the effects of the present invention, the total content of tin and indium in 100% by weight of the conductive particles is preferably 5% by weight or more, more preferably 10% by weight or more, even more preferably 20% by weight or more, and is preferably 80% by weight or less, more preferably 70% by weight or less, even more preferably 60% by weight or less. Note that, when the conductive portion has an alloy layer containing an alloy of tin and indium, the total content of tin and indium indicates the content of the alloy of tin and indium.

[0115] From the viewpoint of more effectively exerting the effects of the present invention, the total content of tin and indium in 100% by weight of the conductive portion in the conductive particle is preferably 10% by weight or more, more preferably 20% by weight or more, even more preferably 30% by weight or more, and is preferably 99% by weight or less, more preferably 95% by weight or less, even more preferably 80% by weight or less. Note that, when the conductive portion has an alloy layer containing an alloy of tin and indium, the total content of tin and indium indicates the content of the alloy of tin and indium.

[0116] The indium content of the layer containing tin and indium (100 wt%) is preferably 10 wt% or more, more preferably 20 wt% or more, and even more preferably 36 wt% or more, and is preferably 99.9 wt% or less, more preferably 98 wt% or less, even more preferably 95 wt% or less, still more preferably 90 wt% or less, particularly preferably 80 wt% or less, and most preferably 72 wt% or less. When the indium content is equal to or more than the lower limit and equal to or less than the upper limit, the effects of the present invention can be more effectively exhibited.

[0117] When the conductive portion has an alloy layer containing an alloy of tin and indium, the content of indium in 100% by weight of the alloy layer containing an alloy of tin and indium is preferably 10% by weight or more, more preferably 20% by weight or more, even more preferably 36% by weight or more, and is preferably 99.9% by weight or less, more preferably 98% by weight or less, even more preferably 95% by weight or less, still more preferably 90% by weight or less, particularly preferably 80% by weight or less, and most preferably 72% by weight or less. When the content of indium is equal to or more than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited.

[0118] The contents of tin and indium (and other metals) in the conductive particles, the conductive portion, and the alloy layer containing an alloy of tin and indium can be measured using a high-frequency inductively coupled plasma optical emission spectrometer, an X-ray fluorescence spectrometer, or the like. Examples of the high-frequency inductively coupled plasma optical emission spectrometer include the "ICP-AES" manufactured by Horiba, Ltd. Examples of the X-ray fluorescence spectrometer include the "EDX-800HS" manufactured by Shimadzu Corporation.

[0119] From the viewpoint of improving the adhesion between the conductive portion and the base particle, the conductive portion of the conductive particle preferably contains copper or nickel. The conductive portion of the conductive particle may contain copper or nickel.

[0120] From the viewpoint of improving the adhesion between the conductive portion and the base particle, it is preferable that the conductive portion of the conductive particle has a layer containing copper or nickel. From the viewpoint of improving the adhesion between the conductive portion and the base particle, it is preferable that the base particle be in contact with the layer containing copper or nickel. From the viewpoint of improving the adhesion between the conductive portion and the base particle, it is preferable that the layer containing copper or nickel is the innermost layer of the conductive portion. From the viewpoint of improving the adhesion between the conductive portion and the base particle, it is preferable that the metal constituting the innermost layer of the conductive portion is copper or nickel, and more preferably nickel.

[0121] The thickness of the copper or nickel-containing layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, even more preferably 0.05 μm or more, particularly preferably 0.1 μm or more, and is preferably 2 μm or less, more preferably 1.5 μm or less, even more preferably 1 μm or less, particularly preferably 0.75 μm or less. When the thickness of the copper or nickel-containing layer is equal to or greater than the lower limit and equal to or less than the upper limit, the contact area between the conductive particles and the electrode can be increased, and the electrical conductivity reliability can be further improved. Note that the thickness of the copper or nickel-containing layer is the average thickness per conductive particle.

[0122] The thickness of the copper or nickel-containing layer can be measured by observing the cross section of the conductive particle using, for example, a transmission electron microscope (TEM).

[0123] From the viewpoint of further improving the conduction reliability, the conductive portion preferably has a conductive layer having a melting point of 200°C or lower. The conductive portion preferably has a conductive layer having a melting point of 190°C or lower, more preferably has a conductive layer having a melting point of 180°C or lower, even more preferably has a conductive layer having a melting point of 170°C or lower, and even more preferably has a conductive layer having a melting point of 160°C or lower. The conductive portion more preferably has a conductive layer having a melting point of 155°C or lower, particularly preferably has a conductive layer having a melting point of 150°C or lower, particularly more preferably has a conductive layer having a melting point of 140°C or lower, and most preferably has a conductive layer having a melting point of 135°C or lower. When the conductive portion has the above-mentioned preferred conductive layer, the conduction reliability can be further improved. The conductive portion may have only one conductive layer having a melting point of 200°C or lower, or may have two or more conductive layers.

[0124] From the viewpoint of enhancing the bonding strength and adhesion between the conductive particles and the electrode, the conductive layer having a melting point of 200° C. or less is preferably an outer surface layer of the conductive part. From the viewpoint of enhancing the bonding strength and adhesion between the conductive particles and the electrode, when the conductive part is composed of two or more conductive layers, the conductive layer having a melting point of 200° C. or less is preferably an outermost layer of the conductive part.

[0125] From the viewpoint of melting the conductive portion well, when the conductive portion is two or more conductive layers, it is preferable that the two or more conductive layers are stacked (arranged) so that the melting points of the conductive layers increase in order from the outer surface to the inner surface of the conductive portion. From the viewpoint of melting the conductive portion well, when the conductive portion is two or more conductive layers, it is preferable that the two or more conductive layers are stacked in order of decreasing melting point from the outer surface to the inner surface of the conductive portion. From the viewpoint of melting the conductive portion well, it is preferable that the melting point of the outer conductive layer of two or more adjacent conductive layers is lower than the melting point of the inner conductive layer.

[0126] From the viewpoint of melting the conductive part well and more effectively exerting the effects of the present invention, it is preferable that the conductive part has a layer containing copper or nickel and an alloy layer containing an alloy of tin and indium. From the viewpoint of melting the conductive part well, it is preferable that the alloy layer containing an alloy of tin and indium is disposed on the outer surface of the copper or nickel layer.

[0127] From the viewpoint of more effectively exerting the effects of the present invention, the melting point of the entire conductive portion of the conductive particle is preferably 200° C. or lower, more preferably 160° C. or lower, even more preferably 155° C. or lower, particularly preferably 150° C. or lower, and most preferably 140° C. or lower. The melting point of the entire conductive portion of the conductive particle may be 25° C. or higher, or may be 50° C. or higher.

[0128] The melting point of the entire conductive portion can be measured by the following method.

[0129] 35 mg of conductive particles are measured using a differential scanning calorimeter (DSC) at a temperature increase rate of 5° C. / min. If there are multiple peaks, the peak with the lowest melting point is taken as the peak for the entire conductive portion.

[0130] From the viewpoint of further suppressing aggregation of the conductive particles, the conductive portion preferably contains a metal salt. Examples of the metal salt include indium hydroxide, indium oxide, tin oxide, indium chloride, tin chloride, indium sulfate, tin sulfate, and copper sulfate. Only one type of the metal salt may be used, or two or more types may be used in combination.

[0131] From the viewpoint of further suppressing aggregation of the conductive particles, the metal salt preferably contains indium hydroxide, indium oxide, or tin oxide, and more preferably contains indium hydroxide.

[0132] The type of metal salt contained in the conductive portion can be identified by the following method: An X-ray diffraction spectrum of the conductive portion is measured using an X-ray diffractometer (RINT2500VHF manufactured by Rigaku Corporation), and the shape of the spectrum peak appearing between 0° and 90° is analyzed to identify the type of metal salt.

[0133] The content of the metal salt in 100% by weight of the conductive particles is preferably 0.002% by weight or more, more preferably 0.005% by weight or more, even more preferably 0.01% by weight or more, and preferably 10.00% by weight or less, more preferably 3.00% by weight or less, and even more preferably 0.50% by weight or less. When the content of the metal salt is equal to or greater than the lower limit, aggregation of the conductive particles can be further suppressed. When the content of the metal salt is equal to or less than the upper limit, the volume resistivity of the conductive particles can be reduced, and the electrical conductivity reliability of the resulting connection structure can be improved even when conductive connection is made at a relatively low temperature.

[0134] The content of the metal salt in the conductive particles, relative to 100% by weight of the conductive portion, is preferably 0.005% by weight or more, more preferably 0.01% by weight or more, even more preferably 0.03% by weight or more, and is preferably 20.00% by weight or less, more preferably 5.00% by weight or less, and even more preferably 1.00% by weight or less. When the content of the metal salt is equal to or greater than the lower limit, aggregation of the conductive particles can be further suppressed. When the content of the metal salt is equal to or less than the upper limit, the volume resistivity of the conductive particles can be reduced, and the electrical conductivity reliability of the resulting connection structure can be improved even when conductive connection is made at a relatively low temperature.

[0135] When the metal salt contains indium hydroxide, the content of indium hydroxide in the conductive portion is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more, even more preferably 0.05 parts by weight or more, and preferably 10.00 parts by weight or less, more preferably 2.50 parts by weight or less, and even more preferably 2.00 parts by weight or less, relative to 100 parts by weight of indium content in the conductive portion. When the content of indium hydroxide in the conductive portion is equal to or greater than the lower limit, aggregation of the conductive particles can be further suppressed. When the content of indium hydroxide in the conductive portion is equal to or less than the upper limit, the volume resistivity of the conductive particles can be reduced, and the conductive reliability of the resulting connection structure can be improved even when conductive connection is made at a relatively low temperature.

[0136] In the conductive portion, the metal salt may or may not be uniformly distributed. From the viewpoint of further suppressing aggregation of the conductive particles, it is preferable that the average content of the metal salt in a region (R2) extending from the outer surface of the conductive portion to half the thickness inward is higher than the average content of the metal salt in a region (R1) extending from the inner surface of the conductive portion to half the thickness outward. In Figure 5, the region (R1) is the region inside the dashed line L1 of the conductive portion 3. In Figure 5, the region (R2) is the region outside the dashed line L1 of the conductive portion 3.

[0137] Of the 100% by weight content of the metal salt in the entire conductive portion, the average content of the metal salt in the region (R2) extending from the outer surface of the conductive portion to the half-thickness inward is preferably greater than 50% by weight, more preferably at least 70% by weight, even more preferably at least 80% by weight, and preferably at most 99% by weight, more preferably at most 95% by weight, even more preferably at most 92% by weight. When the average content of the metal salt in the region (R2) extending from the outer surface of the conductive portion to the half-thickness inward is equal to or greater than the above-mentioned lower limit, aggregation of conductive particles during storage can be further suppressed, and the conductivity reliability of the resulting connection structure can be further improved. When the average content of the metal salt in the region (R2) extending from the outer surface of the conductive portion to the half-thickness inward is equal to or less than the above-mentioned upper limit, aggregation of conductive particles can be further suppressed.

[0138] The average content of the metal salt in 100% by weight of the region (R1) extending from the inner surface of the conductive portion outward to half the thickness is preferably 0.0001% by weight or more, more preferably 0.001% by weight or more, even more preferably 0.005% by weight or more, and is preferably 5.0% by weight or less, more preferably 3.0% by weight or less, and even more preferably 1.0% by weight or less. When the average content of the metal salt in 100% by weight of the region (R1) is equal to or more than the lower limit and equal to or less than the upper limit, the electrical conductivity reliability of the resulting connection structure can be further improved.

[0139] The average content of the metal salt in 100% by weight of the region (R2) extending from the outer surface of the conductive portion to the inside at half the thickness is preferably 0.02% by weight or more, more preferably 0.04% by weight or more, even more preferably 0.07% by weight or more, and is preferably 15.00% by weight or less, more preferably 5.0% by weight or less, and even more preferably 3.0% by weight or less. When the average content of the metal salt in 100% by weight of the region (R2) is equal to or more than the lower limit and equal to or less than the upper limit, aggregation of the conductive particles during storage can be further suppressed.

[0140] The average content of the metal salt in the region (R1) and the region (R2) can be measured, for example, by the following method. A thin film slice (for example, 100 nm thick) passing through the center of the obtained conductive particle is prepared using a focused ion beam. Using a transmission electron microscope FE-TEM ("JEM-2010FEF" manufactured by JEOL Ltd.), the content of the metal salt in the thickness direction of the conductive portion is measured with an energy dispersive X-ray analyzer (EDS). From the results, the average content of the metal salt in the region (R1) and the region (R2) is determined.

[0141] From the viewpoint of preventing oxidation of the metal of the conductive part and removing oxide films and foreign matter on the surface of the conductive part to further enhance the reliability of conduction, it is preferable that the outer surface of the conductive part is surface-treated with flux. The flux is not particularly limited.

[0142] Examples of the flux include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, phosphoric acid, a derivative of phosphoric acid, an organic halide, hydrazine, an amine compound, an organic acid, and pine resin. Only one type of the flux may be used, or two or more types may be used in combination.

[0143] Examples of the molten salt include ammonium chloride. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamic acid, and glutaric acid. Examples of the pine resin include activated pine resin and non-activated pine resin. The flux is preferably an organic acid having two or more carboxyl groups or pine resin. The flux may be an organic acid having two or more carboxyl groups or pine resin. The use of an organic acid having two or more carboxyl groups or pine resin further increases connection strength and electrical reliability.

[0144] Examples of the organic acid having two or more carboxyl groups include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

[0145] Examples of the amine compound include cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, imidazole, benzimidazole, phenylimidazole, carboxybenzimidazole, benzotriazole, and carboxybenzotriazole.

[0146] The rosin is a rosin containing abietic acid as a main component. Examples of the rosin include abietic acid and acrylic-modified rosin. The flux is preferably a rosin, and more preferably abietic acid. The use of this preferred flux further enhances the flux effect.

[0147] The activation temperature (melting point) of the flux is preferably 50° C. or higher, more preferably 70° C. or higher, and even more preferably 80° C. or higher, and is preferably 200° C. or lower, more preferably 190° C. or lower, still more preferably 160° C. or lower, still more preferably 150° C. or lower, and even more preferably 140° C. or lower. When the activation temperature (melting point) of the flux is equal to or higher than the lower limit and equal to or lower than the upper limit, the flux effect is further enhanced.

[0148] The melting point of the flux can be determined by differential scanning calorimetry (DSC). Examples of DSC devices include the "EXSTAR DSC7020" manufactured by SII.

[0149] The boiling point of the flux is preferably 200° C. or less.

[0150] The flux is preferably a flux that releases cations when heated, which further increases connection strength and electrical reliability.

[0151] The flux that releases cations when heated includes the above-mentioned thermal cationic initiator (thermal cationic curing agent).

[0152] From the viewpoint of further enhancing the flux effect, the flux is preferably a salt of an acid compound and a basic compound.

[0153] The acid compound is preferably an organic compound having a carboxyl group. Examples of the acid compound include aliphatic carboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, citric acid, and malic acid, alicyclic carboxylic acids such as cyclohexylcarboxylic acid and 1,4-cyclohexyldicarboxylic acid, and aromatic carboxylic acids such as isophthalic acid, terephthalic acid, trimellitic acid, and ethylenediaminetetraacetic acid. From the viewpoint of more effectively increasing connection strength and more effectively increasing conduction reliability, the acid compound is preferably glutaric acid, cyclohexylcarboxylic acid, or adipic acid.

[0154] The basic compound is preferably an organic compound having an amino group. Examples of the basic compound include diethanolamine, triethanolamine, methyldiethanolamine, ethyldiethanolamine, cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, 2-methylbenzylamine, 3-methylbenzylamine, 4-tert-butylbenzylamine, N-methylbenzylamine, N-ethylbenzylamine, N-phenylbenzylamine, N-tert-butylbenzylamine, N-isopropylbenzylamine, N,N-dimethylbenzylamine, imidazole compounds, and triazole compounds. From the viewpoint of more effectively increasing connection strength and more effectively increasing conduction reliability, the basic compound is preferably benzylamine.

[0155] The area of ​​the conductive portion (coverage by the conductive portion) is preferably 80% or more, more preferably 90% or more, of the total surface area (100%) of the base particle. The upper limit of the coverage by the conductive portion is not particularly limited. The coverage by the conductive portion may be 100%, 100% or less, or 99% or less. When the coverage by the conductive portion is equal to or greater than the lower limit, the electrical connection reliability can be further effectively improved when electrodes are electrically connected.

[0156] The thickness of the conductive portion is preferably 0.005 μm or more, more preferably 0.01 μm or more, even more preferably 0.05 μm or more, and preferably 10 μm or less, more preferably 1 μm or less, even more preferably 0.5 μm or less. When the thickness of the conductive portion is equal to or greater than the lower limit and equal to or less than the upper limit, the electrical connection reliability is more effectively improved, and the conductive particles can be sufficiently deformed when connecting electrodes without becoming too hard. Note that the thickness of the conductive portion is the average thickness per conductive particle.

[0157] When the conductive portion is formed of multiple layers, the thickness of the outermost layer of the conductive portion is preferably 0.001 μm or more, more preferably 0.01 μm or more, and preferably 0.5 μm or less, more preferably 0.3 μm or less. When the thickness of the outermost layer of the conductive portion is equal to or greater than the lower limit and equal to or less than the upper limit, the outermost layer of the conductive portion becomes uniform, the corrosion resistance is sufficiently high, and the connection resistance between electrodes can be sufficiently low. Note that the thickness of the outermost layer of the conductive portion is the average thickness per conductive particle.

[0158] The thickness of the conductive portion and the thickness of the outermost layer of the conductive portion can be measured by observing the cross section of the conductive particle using, for example, a transmission electron microscope (TEM).

[0159] The method for forming the conductive portion on the surface of the base particle is not particularly limited. Examples of methods for forming the conductive portion include electroless plating, electroplating, physical collision, mechanochemical reaction, physical vapor deposition or physical adsorption, and coating the surface of the base particle with a metal powder or a paste containing a metal powder and a binder. The method for forming the conductive portion is preferably electroless plating, electroplating, or physical collision. Examples of physical vapor deposition methods include vacuum deposition, ion plating, and ion sputtering. Furthermore, the physical collision method uses, for example, a sheeter composer (manufactured by Tokuju Manufacturing Co., Ltd.).

[0160] <Insulating Particles> The conductive particles according to the present invention preferably have a plurality of insulating particles on their surfaces. In this case, when the conductive particles are used to connect electrodes, short-circuiting between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles come into contact with each other, the insulating particles are present between the plurality of electrodes, preventing short-circuiting between laterally adjacent electrodes rather than between upper and lower electrodes. When connecting electrodes, applying pressure to the conductive particles with two electrodes can easily remove the insulating particles between the conductive particles and the electrodes. Furthermore, when the conductive particles have a plurality of protrusions on the outer surface of the conductive portion, the insulating particles between the conductive particles and the electrodes can be even more easily removed.

[0161] The insulating particles are preferably polymers of a polymerizable compound. The polymerizable compound is not particularly limited. Examples of the polymerizable compound include the materials of the resin particles described above. From the viewpoint of improving the adhesion between the conductive particles and the insulating particles and further increasing the insulation reliability, the insulating particles are preferably resin particles.

[0162] Methods for disposing the insulating particles on the surface of the conductive part include chemical methods and physical or mechanical methods. Examples of the chemical methods include interfacial polymerization, suspension polymerization in the presence of particles, and emulsion polymerization. Examples of the physical or mechanical methods include spray drying, hybridization, electrostatic deposition, spraying, dipping, and vacuum deposition. From the viewpoint of more effectively improving insulation reliability and conduction reliability when electrodes are electrically connected, the method for disposing the insulating particles on the surface of the conductive part is preferably a physical method.

[0163] The particle diameter of the insulating particles can be appropriately selected depending on the particle diameter of the conductive particles and the application of the conductive particles. The particle diameter of the insulating particles is preferably 10 nm or more, more preferably 100 nm or more, even more preferably 200 nm or more, particularly preferably 300 nm or more, and preferably 4000 nm or less, more preferably 2000 nm or less, even more preferably 1500 nm or less, particularly preferably 1000 nm or less. If the particle diameter of the insulating particles is above the lower limit, when the conductive particles are dispersed in the binder resin, multiple conductive particles are less likely to come into contact with each other. If the particle diameter of the insulating particles is below the upper limit, there is no need to apply excessive pressure or heat to a high temperature to remove the insulating particles between the electrodes and the conductive particles when connecting electrodes.

[0164] The particle diameter of the insulating particles is preferably an average particle diameter, and the average particle diameter indicates a number-average particle diameter. The particle diameter of the insulating particles is determined using a particle size distribution measuring device or the like. The particle diameter of the insulating particles is preferably determined by observing 50 random insulating particles with an electron microscope or optical microscope, calculating the average value, or by performing laser diffraction particle size distribution measurement. When measuring the particle diameter of the insulating particles in the conductive particles, for example, it can be measured as follows.

[0165] Conductive particles were added to Kulzer's Technovit 4000 to a content of 30% by weight and dispersed to prepare a test embedding resin containing conductive particles. An ion milling machine (Hitachi High-Technologies Corporation's IM4000) was used to cut out a cross section of the conductive particles so that it passed through the center of the dispersed conductive particles in the test embedding resin. Then, a field emission scanning electron microscope (FE-SEM) was used, with the image magnification set to 50,000 times. 50 conductive particles were randomly selected, and the insulating particles of each conductive particle were observed. The equivalent circle diameter of the insulating particles in each conductive particle was measured as the particle diameter, and the arithmetic average of these was used to determine the particle diameter of the insulating particles.

[0166] The conductive particles according to the present invention may contain two or more types of insulating particles having different particle diameters. By using two or more types of insulating particles having different particle diameters, the insulating particles having smaller particle diameters can enter gaps covered by the insulating particles having larger particle diameters, and the insulating particles can be arranged on the surfaces of the conductive particles more efficiently.

[0167] The coefficient of variation (CV value) of the particle diameter of the insulating particles is preferably 20% or less. When the coefficient of variation of the particle diameter of the insulating particles is equal to or less than the upper limit, the thickness of the insulating particles in the obtained conductive particles becomes more uniform, making it easier to apply uniform pressure during conductive connection, and further reducing the connection resistance between electrodes. The lower limit of the coefficient of variation (CV value) of the particle diameter of the insulating particles is not particularly limited. The coefficient of variation (CV value) of the particle diameter of the insulating particles may be 0% or more, or may be 1% or more.

[0168] The coefficient of variation (CV value) can be measured as follows.

[0169] CV value (%) = (ρ / Dn) × 100, where ρ: standard deviation of particle diameter of insulating particles, and Dn: average particle diameter of insulating particles.

[0170] The shape of the insulating particles is not particularly limited, and may be spherical, or may be a shape other than spherical, such as flat.

[0171] From the viewpoint of improving insulation reliability, the area of ​​the portion covered by the insulating particles (coverage rate by the insulating particles) out of the total surface area (100%) of the conductive portion is preferably 30% or more, more preferably 35% or more, and is preferably 70% or less, more preferably 60% or less.

[0172] The coverage rate of the insulating particles can be measured, for example, by the following method. Using a field emission scanning electron microscope (FE-SEM) set at an image magnification of 50,000 times, 20 conductive particles are randomly selected and the surface of each conductive particle is observed. For the obtained conductive particles, the percentage of the surface area of ​​the portion covered with the insulating particles relative to the projected area of ​​the entire particle is measured, and the arithmetic average is taken as the coverage rate of the insulating particles.

[0173] The coverage rate of the insulating particles can also be measured by mapping analysis such as EDX associated with SEM.

[0174] The method for controlling the coverage rate of the insulating particles is not particularly limited, and can be controlled by, for example, the amount of inorganic particles added to the base particles, the mixing time, etc.

[0175] (Method for producing conductive particles) The method for producing conductive particles according to the present invention is the method for producing conductive particles described above. The method for producing conductive particles according to the present invention includes a step of forming the conductive portion on the surface of the base particle by electroless plating.

[0176] Examples of methods for easily incorporating the metal salt into the conductive part include the following: a method of adding a large amount of metal salt to a plating solution in the electroless plating; a method of dissolving a metal salt in a plating solution in the electroless plating and then adding a large amount of a strong acid or a strong base to precipitate the metal salt, which is then incorporated into the conductive part; and a method of performing electroless plating using a solvent in which the metal salt is insoluble, and adding the metal salt during the reaction to incorporate it into the conductive part.

[0177] (Conductive Material) The conductive material according to the present invention includes the conductive particles described above and a binder resin. The conductive particles are preferably dispersed in the binder resin for use. The conductive particles are preferably dispersed in the binder resin for use 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 conductive material for circuit connection.

[0178] The binder resin is not particularly limited. A known insulating resin is used as the binder resin. The binder resin preferably contains a thermoplastic component (thermoplastic compound) or a curable component, and more preferably contains a curable component. 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.

[0179] Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, elastomers, etc. The binder resins may be used alone or in combination of two or more.

[0180] Examples of the vinyl resin include vinyl acetate resin, acrylic resin, and styrene resin. Examples of the thermoplastic resin include polyolefin resin, ethylene-vinyl acetate copolymer, and polyamide resin. Examples of the curable resin include epoxy resin, urethane resin, polyimide resin, and unsaturated polyester resin. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin may be used in combination with a curing agent. Examples of the thermoplastic block copolymer include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, a hydrogenated product of styrene-butadiene-styrene block copolymer, and a hydrogenated product of styrene-isoprene-styrene block copolymer. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

[0181] In addition to the conductive particles and the binder resin, the conductive material may contain various additives such as fillers, extenders, softeners, plasticizers, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents, and flame retardants.

[0182] The method for dispersing the conductive particles in the binder resin can be a conventionally known dispersion method and is not particularly limited. Examples of the method for dispersing the conductive particles in the binder resin include the following methods: A method in which the conductive particles are added to the binder resin and then kneaded and dispersed using a planetary mixer or the like; A method in which the conductive particles are uniformly dispersed in water or an organic solvent using a homogenizer or the like, then added to the binder resin and then kneaded and dispersed using a planetary mixer or the like; A method in which the binder resin is diluted with water or an organic solvent or the like, then the conductive particles are added, and then kneaded and dispersed using a planetary mixer or the like.

[0183] The viscosity (η25) of the conductive material at 25°C is preferably 30 Pa·s or more, more preferably 50 Pa·s or more, and preferably 400 Pa·s or less, more preferably 300 Pa·s or less. When the viscosity of the conductive material at 25°C is equal to or greater than the lower limit and equal to or less than the upper limit, the insulation reliability between electrodes can be more effectively improved, and the conduction reliability between electrodes can be more effectively improved. The viscosity (η25) can be appropriately adjusted by the types and amounts of the blended components.

[0184] The viscosity (η25) can be measured, for example, using an E-type viscometer ("TVE22L" manufactured by Toki Sangyo Co., Ltd.) under conditions of 25° C. and 5 rpm.

[0185] The conductive material can be used as a conductive paste, a conductive film, or the like. When the conductive material is a conductive film, a film not containing conductive particles may be laminated on a conductive film containing conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

[0186] The content of the binder resin in 100% by weight of the conductive material is preferably 10% by weight or more, more preferably 30% by weight or more, even more preferably 50% by weight or more, particularly preferably 70% by weight or more, and is preferably 99.99% by weight or less, more preferably 99.9% by weight or less. When the content of the binder resin is equal to or more than the lower limit and equal to or less than the upper limit, the conductive particles are efficiently arranged between the electrodes, and the connection reliability of the connection target members connected by the conductive material can be further improved.

[0187] The content of the conductive particles in 100% by weight of the conductive material is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and is preferably 80% by weight or less, more preferably 60% by weight or less, even more preferably 40% by weight or less, particularly preferably 20% by weight or less, and most preferably 10% by weight or less. When the content of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, the conductivity reliability and insulation reliability can be further improved.

[0188] (Connection structure) A connection structure according to the present invention comprises a first connection-target member having a first electrode on its surface, a second connection-target member having a second electrode on its surface, and a connection portion connecting the first connection-target member and the second connection-target member. In the connection structure according to the present invention, the material of the connection portion contains the conductive particles described above. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by the conductive particles.

[0189] FIG. 6 is a cross-sectional view that schematically shows a connection structure using conductive particles according to the first embodiment of the present invention.

[0190] The connection structure 51 shown in Figure 6 includes a first connection target member 52, a second connection target member 53, and a connection portion 54 connecting the first connection target member 52 and the second connection target member 53. The material of the connection portion 54 includes conductive particles 1. The connection portion 54 may be formed from a conductive material including the conductive particles 1. The connection portion 54 is preferably formed by curing a conductive material including a plurality of conductive particles 1. Note that the conductive particles 1 are shown schematically in Figure 6 for convenience of illustration. Instead of the conductive particles 1, conductive particles 11, conductive particles 21, or conductive particles 31 may be used.

[0191] The first connection target member 52 has a plurality of first electrodes 52a on its surface (upper surface). The second connection target member 53 has a plurality of second electrodes 53a on its surface (lower surface). The first electrodes 52a and the second electrodes 53a are electrically connected by one or more conductive particles 1. Therefore, the first connection target member 52 and the second connection target member 53 are electrically connected by the conductive portions 3 of the conductive particles 1.

[0192] The method for manufacturing the connection structure is not particularly limited. One example of a method for manufacturing a connection structure includes placing the conductive material between a first connection target member and a second connection target member to obtain a laminate, and then heating and pressurizing the laminate. The pressure of the thermocompression bonding is preferably 40 MPa or more, more preferably 60 MPa or more, and preferably 90 MPa or less, more preferably 70 MPa or less. The heating temperature of the thermocompression bonding is preferably 80°C or more, more preferably 100°C or more, and preferably 140°C or less, more preferably 120°C or less. When the pressure and temperature of the thermocompression bonding are equal to or greater than the lower limit and equal to or less than the upper limit, if the conductive particles have insulating particles on their surfaces, the insulating particles can be easily detached from the surfaces of the conductive particles during conductive connection, thereby further improving the reliability of conduction between electrodes.

[0193] When the laminate is heated and pressurized, the insulating particles present between the conductive particles and the first and second electrodes can be removed. For example, when the laminate is heated and pressurized, the insulating particles present between the conductive particles and the first and second electrodes are easily detached from the surface of the insulating particle-attached conductive particles. Note that when the laminate is heated and pressurized, some of the insulating particles may detach from the surface of the insulating particle-attached conductive particles, partially exposing the surface of the conductive portion. The exposed surface of the conductive portion may contact the first and second electrodes, thereby electrically connecting the first and second electrodes via the conductive particles.

[0194] The first and second connection target members are not particularly limited. Specific examples of the first and second connection target members include electronic components such as semiconductor chips, semiconductor packages, LED chips, LED packages, capacitors, and diodes, as well as electronic components such as resin films, printed circuit boards, flexible printed circuit boards, flexible flat cables, rigid-flexible boards, glass epoxy boards, and glass boards. The first and second connection target members are preferably electronic components.

[0195] Examples of the electrodes provided on the connection target members include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. When the connection target members are flexible printed circuit boards, the electrodes are preferably gold electrodes, nickel electrodes, tin electrodes, silver electrodes, or copper electrodes. When the connection target members are glass substrates, the electrodes are preferably aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, or tungsten electrodes. When the electrodes are aluminum electrodes, they may be formed solely from aluminum, or may be electrodes in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of materials for the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

[0196] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0197] Example 1 (1) Preparation of Conductive Particles Divinylbenzene copolymer resin particles (base particle A, "Micropearl SP-220" manufactured by Sekisui Chemical Co., Ltd.) having a particle diameter of 20.0 μm were prepared. 10 parts by weight of the base particle 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, and the solution was then filtered to extract the base particle A. Next, the base particle A was added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surface of the base particle A. The surface-activated base particle A was thoroughly washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain dispersion A.

[0198] Further, a nickel plating solution (1) (pH 8.5) containing 0.14 mol / L of nickel sulfate, 0.46 mol / L of dimethylamine borane, and 0.2 mol / L of sodium citrate was prepared.

[0199] While stirring dispersion A at 70°C, nickel plating solution (1) was added dropwise to dispersion A at a rate of 30 mL / min for 10 minutes. Subsequently, nickel plating solution (1) was added dropwise at a rate of 10 mL / min for 40 minutes, and then at a rate of 4 mL / min for 80 minutes, thereby controlling the boron content incorporated into the plating film and performing electroless nickel-boron alloy plating. The dispersion was then filtered to remove particles, which were then washed with water and dried to obtain particles A having a first conductive portion (nickel layer, thickness 200 nm) disposed on the surface of base particle A.

[0200] Ten parts by weight of the resulting particles A were dispersed in 500 parts by weight of ion-exchanged water using an ultrasonicator to obtain suspension B. A tin-indium plating solution (1) (adjusted to pH 8.5 with sodium hydroxide) containing 15 g / L of tin sulfate, 34 g / L of indium sulfate, 70 g / L of ethylenediaminetetraacetic acid, 30 g / L of sodium gluconate, and 1.5 g / L of phosphinic acid was prepared. Furthermore, reducing solution A (adjusted to pH 10.0 with sodium hydroxide) containing 5 g / L of sodium borohydride was prepared.

[0201] While stirring the obtained suspension B at 55°C, the tin-indium plating solution (1) was gradually added to suspension B, and then electroless tin-indium plating was performed by reduction with reducing solution A to form second conductive portions. Particles B were obtained in which second conductive portions (tin-indium layer, thickness 15 nm) were disposed on the surfaces of the first conductive portions.

[0202] 10 parts by weight of the obtained particles B were dispersed in 500 parts by weight of ion-exchanged water using an ultrasonicator to obtain suspension C. A tin-indium plating solution (2) (adjusted to pH 8.5 with sodium hydroxide) containing 10 g / L of tin sulfate, 40 g / L of indium sulfate, 70 g / L of ethylenediaminetetraacetic acid, 30 g / L of sodium gluconate, and 1.5 g / L of phosphinic acid was prepared. Furthermore, a reducing solution B (adjusted to pH 10.0 with sodium hydroxide) containing 2.5 g / L of sodium borohydride was prepared. Furthermore, a sodium hydroxide (10 g / L) aqueous solution was prepared as pH adjuster A.

[0203] While stirring the obtained suspension C at 60°C, the tin-indium plating solution (2) was gradually added to the suspension C, and then, while adding pH adjuster A at a rate of 1.0 g / min, electroless tin-indium plating was performed by reduction with reducing solution B, thereby forming a third conductive portion.

[0204] Thereafter, the suspension C was filtered to extract the particles, which were then washed with water and dried to obtain conductive particles having a first conductive portion (nickel layer), a second conductive portion (tin / indium layer), and a third conductive portion (tin / indium / indium hydroxide layer, thickness 25 nm) arranged on the surface of the base particle A.

[0205] (2) Preparation of Conductive Material The following materials were mixed to obtain a mixture: 10 parts by weight of bisphenol A epoxy resin ("Epicoat 1009" manufactured by Mitsubishi Chemical Corporation); 40 parts by weight of acrylic rubber (weight average molecular weight of approximately 800,000); 200 parts by weight of methyl ethyl ketone; 50 parts by weight of a microcapsule-type curing agent ("HX3941HP" manufactured by Asahi Kasei E-materials Corporation); and 2 parts by weight of a silane coupling agent ("SH6040" manufactured by Toray Dow Corning Silicones Co., Ltd.). Conductive particles were added to this mixture to a content of 3% by weight and dispersed to obtain a conductive material.

[0206] The obtained conductive material was applied to a 50 μm-thick PET (polyethylene terephthalate) film with one side treated for release, and dried with hot air at 70° C. for 5 minutes to prepare an anisotropic conductive film (conductive material). The thickness of the obtained anisotropic conductive film was 50 μm.

[0207] (3) Fabrication of Connection Structure A polyimide substrate (flexible printed circuit board) having an Au electrode pattern (electrode (Au circuit): Ni / Au thin film on Cu) with an L / S of 200 μm / 200 μm on its upper surface was prepared. In addition, a printed circuit board having an Au electrode pattern (electrode (Au bump): Ni / Au thin film on Cu) with an L / S of 200 μm / 200 μm on its lower surface was prepared. The obtained anisotropic conductive film was applied to the upper surface of the polyimide substrate by heating at 80° C. and 0.98 MPa (10 kgf / cm ２), and then the separator was peeled off. The Au bumps on the printed circuit board were then aligned with the Au circuits on the polyimide substrate. Next, a pressure and heating head was placed on the top surface of the semiconductor chip, and a low pressure of 2 MPa calculated from the bonding area was applied while the anisotropic conductive material layer was cured at 140°C, yielding a connection structure.

[0208] Examples 2, 5, 10-12 In the step of forming the third conductive portion, the tin-indium plating solution (2) was changed to a tin-indium plating solution (2a) containing 10 g / L of tin sulfate, 40 g / L of indium sulfate, 65 g / L of ethylenediaminetetraacetic acid, 40 g / L of sodium gluconate, and 2.5 g / L of phosphinic acid. Furthermore, the reducing solution B was changed to a reducing solution Ba containing 1.5 g / L of sodium borohydride (adjusted to pH 10.0 with sodium hydroxide), and the pH adjuster A was changed to sodium hydroxide (5 g / L). In Examples 2, 5, 10-12, the dripping time of the tin-indium plating solution (2a) and the dripping rate of the reducing solution Ba were changed. Thus, conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1, except that the configuration of the conductive portion was changed as shown in Tables 1-3 below.

[0209] Examples 3, 6, 8, 9, 23, and 24: In the step of forming the third conductive portion, the tin-indium plating solution (2) was changed to a tin-indium plating solution (2b) containing 10 g / L of tin sulfate, 40 g / L of indium sulfate, 50 g / L of ethylenediaminetetraacetic acid, 20 g / L of sodium gluconate, and 1.5 g / L of phosphinic acid. Furthermore, the reducing solution B was changed to a reducing solution Bb containing 2.5 g / L of sodium borohydride (adjusted to pH 10.5 with sodium hydroxide), and the pH adjuster A was changed to sodium hydroxide (12.5 g / L). In Examples 3, 6, 8, 9, 23, and 24, the dripping time of the tin-indium plating solution (2b) and the dripping rate of the reducing solution Bb were changed. Thus, conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1, except that the configuration of the conductive portion was changed as shown in Tables 1, 2, and 6 below.

[0210] Examples 4, 13, and 14 In the step of forming the third conductive portion, the tin-indium plating solution (2) was changed to a tin-indium plating solution (2c) containing 10 g / L of tin sulfate, 40 g / L of indium sulfate, 65 g / L of ethylenediaminetetraacetic acid, 50 g / L of sodium gluconate, and 2.5 g / L of phosphinic acid. Furthermore, the reducing solution B was changed to a reducing solution Bc containing 1.0 g / L of sodium borohydride (adjusted to pH 10.0 with sodium hydroxide), and the pH adjuster A was changed to sodium hydroxide (2.5 g / L). In Examples 4, 13, and 14, the dripping time of the tin-indium plating solution (2c) and the dripping rate of the reducing solution Bc were changed. Thus, conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1, except that the configuration of the conductive portion was changed as shown in Tables 1 and 3 below.

[0211] Example 7 In the step of forming the third conductive portion, the tin-indium plating solution (2) was changed to a tin-indium plating solution containing 10 g / L of tin sulfate, 40 g / L of indium sulfate, 70 g / L of ethylenediaminetetraacetic acid, 20 g / L of sodium gluconate, and 1.5 g / L of phosphinic acid. Furthermore, the reducing solution B was changed to a reducing solution containing 2.5 g / L of sodium borohydride (adjusted to pH 11.0 with sodium hydroxide), and the pH adjuster A was changed to sodium hydroxide (12.5 g / L). In this way, conductive particles, a conductive material, and a connection structure were obtained in the same manner as in Example 1, except that the configuration of the conductive portion was changed as shown in Table 2 below.

[0212] Example 15 In the step of forming the second conductive portion, the tin-indium plating solution (1) was changed to a tin-indium plating solution containing 20 g / L of tin sulfate, 25 g / L of indium sulfate, 70 g / L of ethylenediaminetetraacetic acid, 30 g / L of sodium gluconate, and 1.5 g / L of phosphinic acid. Furthermore, the reducing agent A was changed to a reducing solution containing 5 g / L of sodium borohydride (adjusted to pH 10.5 with sodium hydroxide), and sodium hydroxide (12.5 g / L) was used as a pH adjuster to form the second conductive portion. In this way, conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1, except that the configuration of the conductive portion was changed as shown in Table 3 below.

[0213] (Examples 16 to 19) Base particle A was changed to base particle B ("Micropearl SP-203" manufactured by Sekisui Chemical Co., Ltd.), base particle C ("Micropearl SP-205" manufactured by Sekisui Chemical Co., Ltd.), base particle D ("Micropearl SP-210" manufactured by Sekisui Chemical Co., Ltd.), and base particle E ("Micropearl SP-250" manufactured by Sekisui Chemical Co., Ltd.), respectively. Conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1, except that the configuration of the conductive portion was changed as shown in Table 4 below.

[0214] Example 20 In the step of forming the third conductive portion, the tin-indium plating solution (2) was changed to a tin-indium plating solution containing 10 g / L of tin sulfate, 40 g / L of indium sulfate, 70 g / L of ethylenediaminetetraacetic acid, 30 g / L of sodium gluconate, 1.5 g / L of phosphinic acid, and 0.1 g / L of tin oxide powder (average particle diameter 100 nm). In this way, conductive particles, a conductive material, and a connection structure were obtained in the same manner as in Example 1, except that the configuration of the conductive portion was changed as shown in Table 4 below.

[0215] Example 21 In the step of forming the second conductive portion, the tin-indium plating solution (1) was changed to a tin-indium plating solution containing 15 g / L of tin sulfate, 34 g / L of indium sulfate, 70 g / L of ethylenediaminetetraacetic acid, 30 g / L of sodium gluconate, 1.5 g / L of phosphinic acid, and 0.05 g / L of indium oxide powder (average particle diameter 100 nm). In the step of forming the third conductive portion, the tin-indium plating solution (2) was changed to a tin-indium plating solution containing 10 g / L of tin sulfate, 40 g / L of indium sulfate, 70 g / L of ethylenediaminetetraacetic acid, 30 g / L of sodium gluconate, 1.5 g / L of phosphinic acid, and 0.05 g / L of indium oxide powder (average particle diameter 100 nm). In this way, conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1, except that the composition of the conductive portion was changed as shown in Table 5 below.

[0216] Example 22 In the step of forming the third conductive portion, the tin-indium plating solution (2) was changed to a tin-indium plating solution containing 10 g / L of tin sulfate, 40 g / L of indium sulfate, 70 g / L of ethylenediaminetetraacetic acid, 30 g / L of sodium gluconate, 1.5 g / L of phosphinic acid, and 0.1 g / L of indium oxide powder (average particle diameter 100 nm). In this way, conductive particles, a conductive material, and a connection structure were obtained in the same manner as in Example 1, except that the configuration of the conductive portion was changed as shown in Table 5 below.

[0217] Comparative Example 1 In the step of forming the third conductive portion, the tin-indium plating solution (2) was changed to a tin-indium plating solution containing 10 g / L of tin sulfate, 40 g / L of indium sulfate, 70 g / L of ethylenediaminetetraacetic acid, 60 g / L of sodium gluconate, and 3.0 g / L of phosphinic acid. Furthermore, the reducing solution B was changed to a reducing solution containing 2.5 g / L of sodium borohydride (adjusted to pH 10.0 with sodium hydroxide), and the pH adjuster A was changed to sodium hydroxide (1.0 g / L). In this way, conductive particles, a conductive material, and a connection structure were obtained in the same manner as in Example 1, except that the configuration of the conductive portion was changed as shown in Table 7 below.

[0218] Comparative Example 2 Electroless nickel-boron alloy plating was performed on base particle A in the same manner as in Example 1 to obtain particle A in which a first conductive portion (nickel layer, thickness 200 nm) was disposed on the surface of base particle A. Electroless tin-indium plating was performed on the obtained particle A to form a second conductive portion. Particle D in which a second conductive portion (tin-indium layer, thickness 160 nm) was disposed on the surface of the first conductive portion was obtained.

[0219] Ten parts by weight of the resulting particles D were dispersed in 500 parts by weight of ion-exchanged water using an ultrasonicator to obtain suspension D. A tin-indium plating solution (2) (adjusted to pH 8.5 with sodium hydroxide) containing 10 g / L of tin sulfate, 40 g / L of indium sulfate, 70 g / L of ethylenediaminetetraacetic acid, 30 g / L of sodium gluconate, and 1.5 g / L of phosphinic acid was prepared. Furthermore, a reducing solution A (adjusted to pH 10.0 with sodium hydroxide) containing 5 g / L of sodium borohydride was prepared.

[0220] While stirring the obtained suspension D at 60°C, the tin-indium plating solution (2) was gradually added to the suspension D, and then electroless tin-indium plating was performed by reduction with the reducing solution A, thereby forming a third conductive portion.

[0221] The suspension D was then filtered to remove the particles, which were then washed with water and dried to obtain particles E in which a first conductive portion (nickel layer), a second conductive portion (tin-indium layer), and a third conductive portion (tin-indium, thickness 163 nm) were disposed on the surface of the base particle A. The obtained particles E were heated at 120°C for 30 seconds in an atmospheric environment to obtain conductive particles in which a thin film oxide (indium hydroxide) was formed on the outer surface of the third conductive portion. A conductive material and a connection structure were obtained in the same manner as in Example 1, except that the obtained conductive particles were used.

[0222] Comparative Example 3 In the step of forming the third conductive portion, the tin-indium plating solution (2) was changed to a tin-indium plating solution containing 10 g / L of tin sulfate, 40 g / L of indium sulfate, 40 g / L of ethylenediaminetetraacetic acid, 10 g / L of sodium gluconate, and 1.5 g / L of phosphinic acid. Furthermore, reducing solution B was changed to 3.0 g / L of sodium borohydride (adjusted to pH 10.5 with sodium hydroxide), pH adjuster A was changed to sodium hydroxide (20.0 g / L), and the composition of the conductive portion was changed to that shown in Table 7. Conductive particles, a conductive material, and a connection structure were obtained in the same manner as in Example 1.

[0223] Comparative Examples 4 to 7 In the step of forming the third conductive portion, the tin-indium plating solution (2) was changed to a tin-indium plating solution containing 10 g / L of tin sulfate, 40 g / L of indium sulfate, 70 g / L of ethylenediaminetetraacetic acid, 30 g / L of sodium gluconate, 1.5 g / L of phosphinic acid, and 0.1 g / L of each metal salt powder (average particle diameter 100 nm) shown in Table 8. In this way, conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1, except that the configuration of the conductive portion was changed as shown in Table 8.

[0224] Comparative Example 8: As the conductive particles, solder particles having no base particles ("Sn ４８ In ５２ A conductive material and a connection structure were obtained in the same manner as in Example 1, except that "Polymer-Type 5" (particle diameter: 20 μm) was used.

[0225] (Evaluation) (1) Average content of metal salt in region (R2) out of 100% by weight of the metal salt content in the entire conductive portion. A thin film slice passing through the center of the obtained conductive particle was prepared using a focused ion beam. Using a field emission transmission electron microscope (JEOL Ltd., "JEM-2010FEF"), the metal salt content in the thickness direction of the conductive portion was measured with an energy dispersive X-ray analyzer (EDS). From these results, the metal salt content in the entire conductive portion and the average metal salt content in region (R2) extending from the outer surface of the conductive portion to half the thickness (region 50% of the thickness on the outer surface side) were determined. The components other than metal salt in the conductive portion were tin, indium, nickel, phosphorus, or boron. Furthermore, the above measurements provided the distribution of the metal salt content in the thickness direction of the conductive portion. From these results, the average metal salt content in region (R2) out of 100% by weight of the metal salt content in the entire conductive portion was obtained. The type of metal salt contained in the conductive portion was identified using an X-ray diffraction device (RINT2500VHF manufactured by Rigaku Corporation).

[0226] (2) X-ray diffraction spectrum For the obtained conductive particles, the X-ray diffraction spectrum of the conductive portion was measured using an X-ray diffractometer (Rigaku Denki Co., Ltd. "RINT2500VHF"), and the presence or absence of peaks in the region of 20.5 ° to 23.5 ° and the region of 32.5 ° to 34 ° was observed. Using the method described above, the ratio P of the area of ​​the peak present in the region of 20.5 ° to 23.5 ° to the area of ​​the peak present in the region of 32.5 ° to 34 ° (area of ​​the peak present in the region of 20.5 ° to 23.5 ° / area of ​​the peak present in the region of 32.5 ° to 34 °) was obtained. The measurement conditions for the X-ray diffraction spectrum were 45 kV, 50 mA, a scan rate of 4.0 deg / min, a scan step of 0.02 deg, and a measurement range of 5.0 deg to 60.0 deg in 2θ.

[0227] (3) Aggregation Inhibition of Conductive Particles Three glass containers were prepared, and 10 g of the obtained conductive particles was filled into each glass container. The containers were then stirred using a tabletop shaker at 60 Hz with an amplitude of 0.8 mm for 15 minutes, 30 minutes, or 90 minutes, respectively.

[0228] Three compositions were prepared by mixing the following materials: 10 parts by weight of bisphenol A epoxy resin ("Epicoat 1009" manufactured by Mitsubishi Chemical Corporation); 40 parts by weight of acrylic rubber (weight-average molecular weight: approximately 800,000); and 200 parts by weight of methyl ethyl ketone. 50 parts by weight of a microcapsule-type curing agent ("HX3941HP" manufactured by Asahi Kasei Chemicals Corporation); and 2 parts by weight of a silane coupling agent ("SH6040" manufactured by Toray Dow Corning Silicones Co., Ltd.). Stirred conductive particles were added to the resulting compositions to a content of 3 wt% and dispersed to obtain conductive materials. The resulting conductive materials were molded into sheets to produce anisotropic conductive films (anisotropic conductive materials) with a thickness of 100 μm.

[0229] The resulting anisotropic conductive film was stored at 25°C for 72 hours. After storage, an arbitrary 5 cm x 10 cm area of ​​the anisotropic conductive film was observed using an optical microscope, and the number of agglomerated conductive particles (aggregates) with a major axis of 100 µm or more was counted. The aggregation suppression ability of the conductive particles was evaluated according to the following criteria.

[0230] [Evaluation criteria for the aggregation suppression of conductive particles] ○○○: 2 or less aggregates ○○: 3 to 9 aggregates ○: 10 to 19 aggregates ×: 20 or more aggregates

[0231] (4) Conduction Reliability (4-1) Volume Resistivity of Conductive Particles The volume resistivity of the obtained conductive particles was measured using a "Powder Resistivity Measurement System" manufactured by Mitsubishi Chemical Corp. The volume resistivity of the conductive particles was judged according to the following criteria.

[0232] [Criteria for determining volume resistivity of conductive particles] ○○○: Less than 0.0008 Ω·cm ○○: 0.0008 Ω·cm or more and less than 0.0015 Ω·cm ○: 0.0015 Ω·cm or more and less than 0.003 Ω·cm ×: 0.003 Ω·cm or more

[0233] (4-2) Connection Resistance of Connection Structure (Between Upper and Lower Electrodes) For the 20 connection structures obtained, the connection resistance between the upper and lower electrodes was measured using the four-terminal method, and the average value was used as the connection resistance value of the connection structure. Note that, based on the relationship voltage = current × resistance, the connection resistance can be determined by measuring the voltage when a constant current is passed. The connection resistance of the connection structure was evaluated according to the following criteria.

[0234] [Criteria for determining the connection resistance of the connection structure] ○○○: Connection resistance is less than 0.35Ω ○○: Connection resistance is 0.35Ω or more and less than 0.41Ω ○: Connection resistance is 0.41Ω or more and less than 0.55Ω ×: Connection resistance is 0.55Ω or more or cannot be measured

[0235] The configurations of the conductive particles and the results are shown in Tables 1 to 8 below.

[0236]

[0237]

[0238]

[0239]

[0240]

[0241]

[0242]

[0243]

[0244] In Comparative Example 8, in which solder particles were used, the entire solder particle melted and collapsed, causing poor connections between multiple upper and lower electrodes, making it impossible to measure the connection resistance.

[0245] 7 shows the X-ray diffraction spectrum (a spectrum normalized by the maximum value of the peak intensity between 32.5° and 34°) of the conductive portion of the conductive particle obtained in Example 7. In the X-ray diffraction spectrum of FIG. 7, the peak present in the range of 20.5° to 23.5° is attributed to the metal salt (indium hydroxide), and the peak present in the range of 32.5° to 34° is attributed to the tin / indium layer.

[0246] DESCRIPTION OF SYMBOLS 1, 11, 21, 31... Conductive particles 2... Base particle 3, 13, 23, 33... Conductive portion 13A... First conductive portion 13B... Second conductive portion 23a, 33a... Projection 34... Core substance 51... Connection structure 52... First connection target member 52a... First electrode 53... Second connection target member 53a... Second electrode 54... Connection portion

Claims

1. Conductive particles having base material particles and a conductive portion disposed on the surface of the base material particles, wherein the conductive portion contains tin and indium, when measuring the X-ray diffraction spectrum of the conductive portion, peaks exist in a region of 20.5° or more and 23.5° or less and a region of 32.5° or more and 34° or less, and a ratio P of the area of the peak existing in the region of 20.5° or more and 23.5° or less to the area of the peak existing in the region of 32.5° or more and 34° or less is 0.0001 or more and 0.2 or less, the conductive particles.

2. The conductive particles according to claim 1, wherein the total content of tin and indium in 100% by weight of the conductive particles is 5% by weight or more.

3. The conductive particles according to claim 1 or 2, wherein the ratio P is 0.001 or more and 0.2 or less.

4. The conductive particles according to claim 3, wherein the ratio P is 0.01 or more and 0.2 or less.

5. The conductive particles according to claim 3, wherein the ratio P is 0.005 or more and 0.01 or less.

6. The conductive particles according to claim 1 or 2, wherein the particle diameter of the conductive particles is 1 μm or more and 100 μm or less.

7. The conductive particles according to claim 1 or 2, having a plurality of protrusions on the outer surface of the conductive portion.

8. The conductive portion contains a metal salt, and in 100% by weight of the content of the metal salt in the entire conductive portion, the average content of the metal salt in a region having a thickness of 1 / 2 from the outer surface of the conductive portion toward the inside exceeds 50% by weight, the conductive particles according to claim 1 or 2.

9. The conductive portion contains a metal salt, and the metal salt contains indium hydroxide, the conductive particles according to claim 1 or 2.

10. A method for manufacturing the conductive particles according to claim 1 or 2, comprising a step of forming the conductive portion on the surface of the base material particles by electroless plating, the method for manufacturing conductive particles.

11. A conductive material containing the conductive particles according to claim 1 or 2 and a binder resin.

12. A first connection target member having a first electrode on its surface, a second connection target member having a second electrode on its surface, and a connection portion connecting the first connection target member and the second connection target member, wherein the material of the connection portion contains the conductive particles according to claim 1 or 2, and the first electrode and the second electrode are electrically connected by the conductive particles, the connection structure.