Conductive particles, conductive materials, and connection structures

Abstract

The present invention relates to a conductive particle, comprising: an insulating core; and a conductive layer containing at least two or more elements on the insulating core; at least two or more diffraction rings are formed in a diffraction pattern obtained by analyzing the conductive layer using X-ray diffraction (XRD).

Description

Technical Field

[0001] The present invention relates to conductive particles having a metal conductive layer on the surface of an insulating core, and more particularly to conductive particles used as a core conductive material in an anisotropic conductive adhesive material for connecting fine-pitch circuits. In addition, it relates to a conductive material and a connection structure using the conductive particles. Background Art

[0002] An anisotropic conductive material is a bonding material that transmits an electrical signal between upper / lower electrodes but does not transmit an electrical signal between left / right electrodes. An anisotropic conductive material is a bonding material mainly used for connecting a large number of electrodes such as a display screen to a driving integrated circuit (IC).

[0003] Conductive materials are generally used in anisotropic conductive materials such as anisotropic conductive films, anisotropic conductive adhesives, anisotropic conductive pastes, anisotropic conductive inks, and anisotropic conductive sheets, which are used in a dispersed form by mixing with a curing agent, an adhesive, a resin binder, and other additives.

[0004] Anisotropic conductive materials are used in, for example, FOG (Film on Glass; flexible substrate - glass substrate), COF (Chip on Film; semiconductor chip - flexible substrate), COG (Chip on Glass; semiconductor chip - glass substrate), and FOB (Film on Board; flexible substrate - glass epoxy resin substrate).

[0005] When assuming the bonding of a semiconductor chip and a flexible substrate, an anisotropic conductive material can be used to form a connection structure that electrically connects the electrodes of the substrate and the electrodes of the semiconductor chip by disposing the anisotropic conductive material above the flexible substrate, laminating the semiconductor chip, and then curing the anisotropic conductive material under a pressurized / heated state.

[0006] When conductive particles are used in the anisotropic conductive material, they are mixed with a curing agent, an adhesive, a resin binder, and additives such as fillers, and when a connection structure is formed after pressurization / heating, the electrical connection between the upper / lower electrodes can be maintained through the curing / bonding of the anisotropic conductive material.

[0007] However, in order to improve the conductivity of the conductive layer, the existing conductive particles having a metal conductive layer on the surface of the insulating core are formed into multiple layers. However, in the above-described case, since a part thereof may be amorphous or there may be a boundary between the respective layers of the conductive layer, the resistance on the boundary surface may increase, resulting in an increase in the connection resistance of the anisotropic conductive material using the conductive particles and further causing a problem of an increase in the reliability resistance. Summary of the Invention

[0008] An object of an embodiment of the present invention is to solve the problems existing in the prior art as described above, and to provide a conductive particle having a single conductive layer, high strength, low initial connection resistance, and low resistance increase rate, an anisotropic conductive material including the conductive particle, and an anisotropic connection structure.

[0009] One aspect of the present invention relates to a conductive particle, including:

[0010] an insulating core; and

[0011] a conductive layer including at least two or more elements on the insulating core;

[0012] In a diffraction pattern obtained by analyzing the conductive layer using X-ray diffraction (XRD), at least two or more diffraction rings are formed, and an average length of a major axis of crystal grains of the conductive layer is 8 nm to 13 nm.

[0013] The conductive layer includes at least one element selected from the group consisting of Ni, B, P, N, Pd, Pt, W, Au, Ag, Mo, and Co, and a radius of the innermost diffraction ring in the diffraction rings is preferably 4.93 (l / nm) ± 0.2 (l / nm).

[0014] When the conductive layer is divided into a first region adjacent to the insulating core, a second region adjacent to the first region, and a third region adjacent to the second region and located on the outermost side, it is preferably a single layer without an interlayer boundary between the regions in the first region, the second region, and the third region.

[0015] It is preferable that the content of elements in the conductive layer varies according to the region.

[0016] The conductive layer preferably includes at least two or more elements selected from the group consisting of at least B, P, N, Pd, Pt, W, Au, Ag, Mo, and Co.

[0017] At this time, it is preferable that the conductive particles further include protrusions on the surface of the conductive layer, and it is preferable that an insulating layer or insulating particles are further included on the surface of the conductive layer, and it is preferable that the outermost part of the conductive layer is subjected to rust prevention treatment with a hydrophobic rust inhibitor.

[0018] Another aspect of the present invention provides an anisotropic conductive material including at least one of the conductive particles.

[0019] Another aspect of the present invention provides a connection structure including at least one of the conductive particles.

[0020] Another aspect of the present invention provides an electronic device including at least one of the conductive particles.

[0021] The conductive particles according to the embodiments of the present invention include a plurality of metal elements in the conductive layer and have a single-layer structure, so that the boundary surface can be eliminated in the conductive layer, and the crystallinity can be imparted to the conductive layer, and due to the advantages of the crystal structure, while improving the conductivity, it has a low resistance and high hardness.

[0022] Therefore, by using the conductive particles according to the embodiments of the present invention, an anisotropic conductive material and an anisotropic connection structure can be provided, which can maintain a low resistance increase, reduce the initial connection resistance value, and also have a low resistance increase after a high temperature / high humidity reliability test. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a 500,000-fold image of the conductive layer of the conductive particles according to the embodiments of the present invention taken by a field emission transmission electron microscope (FETEM (field emission transmission electron microscopy)-JEM-2100F, 200 kV).

[0024] Figure 2 It is a diffraction pattern of the conductive layer of the conductive particles according to the embodiments of the present invention measured by X-ray diffraction (XRD, X-RAY DIFFRACTOMETER, product name: SmartLab, manufacturer: RICAKU, target: Cu, electromagnetic wave used: Ka).

[0025] Figure 3 It is a schematic diagram illustrating a method for calculating the radius of the diffraction ring.

[0026] Figure 4 It is a schematic diagram illustrating the analysis position of the conductive layer of the conductive particles according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] Before proceeding with a detailed description of the present invention, it should be understood that the terms used in this specification are only for describing specific embodiments and are not intended to limit the scope of the present invention, which should only be defined by the scope of the appended claims. Unless otherwise mentioned, all technical and scientific terms used in this specification have the same meaning as commonly understood by a person having ordinary general technical knowledge.

[0028] Throughout this specification and the claims, unless otherwise mentioned, the terms "comprise", "comprises", and "comprising" are only used to indicate the inclusion or incorporation of the recited objects, steps, or a series of objects and steps, and do not exclude any other object, step, or a series of objects or steps.

[0029] Furthermore, unless otherwise explicitly stated to the contrary, multiple embodiments of the present invention can be combined with any other embodiment. In particular, any feature designated as preferred or optimal can also be combined with any other feature and multiple features designated as preferred or optimal.

[0030] The conductive particles applicable to the embodiments of the present invention are conductive particles that electrically connect the electrodes by being included between the electrodes, and the electrodes use oxide electrodes such as indium tin oxide (ITO) and zinc oxide (ZnO), metal electrodes made of metals, and metal powders. For example, a paste electrode formed by mixing Ag or Cu powder with a resin to produce a paste and using the paste to form an electrode can be used. The electrodes can include at least one of the oxide electrode, the metal electrode, and the paste electrode.

[0031] The conductive particles applicable to the embodiments of the present invention include insulating core particles and a conductive layer disposed on the surface of the insulating core particles, and may have protrusions on the surface having the same or different conductive substances as the conductive layer.

[0032] The insulating core particles applicable to the embodiments of the present invention are not particularly limited. For example, resin microparticles or organic / inorganic hybrid particles can be used.

[0033] The resin microparticles are copolymers obtained by polymerizing monomers such as polyurethanes, styrenes, acrylates, benzenes, epoxies, amines, and imides, or modified monomers thereof, or mixed monomers of the monomers, by methods such as seed polymerization, dispersion polymerization, suspension polymerization, and emulsion polymerization.

[0034] In the case of organic / inorganic hybrid particles with a core-shell structure, when the core is an organic substance, the shell is an inorganic substance, and when the core is an inorganic substance, the shell is an organic substance. The organic substance used can be the monomer or modified monomer or mixed monomer. In the case of inorganic substances, oxides such as SiO2, TiO2, Al2O3, and ZrO2, nitrides such as AlN, Si3N4, TiN, and BaN, and carbides such as WC, TiC, and SiC can be used. As a method for forming the shell, methods such as chemical coating method, sol-gel method, spray coating method, chemical vapor deposition (CVD), physical vapor deposition (PVD), and electroplating method can be adopted. In addition, forms such as dispersing inorganic particles into an organic matrix, dispersing organic particles into an inorganic matrix, and dispersing organic substances / inorganic substances at 50:50 with each other can also be adopted.

[0035] The conductive layer of the conductive particles applicable to the embodiments of the present invention is a conductive layer containing at least two or more elements. At this time, the conductive layer contains at least two or more elements selected from the group consisting of at least B, P, N, Ni, Pd, Pt, W, Au, Ag, Mo, and Co.

[0036] Preferably, it contains at least one or more elements selected from the group consisting of nickel, B, P, N, Pd, Pt, W, Au, Ag, Mo, and Co.

[0037] For example, it can be composed of alloys of two metals such as nickel-phosphorus, nickel-boron, nickel-tungsten, and nickel-nitrogen, or alloys of three metals such as nickel-phosphorus-tungsten, nickel-boron-tungsten, nickel-phosphorus-cobalt, nickel-phosphorus-palladium, and nickel-boron-palladium. In addition, it can also be composed of alloys of four metals such as nickel-phosphorus-boron-tungsten, nickel-phosphorus-palladium-tungsten, and nickel-boron-tungsten-platinum. In addition, it can also be composed of alloys of five or more metals.

[0038] The reason why nickel is necessarily included in all the examples is that nickel has excellent conductivity and the insulating core used in the conductive particles mainly uses polymer beads, and nickel has excellent adhesion to plastics.

[0039] The conductive layer applicable to the embodiments of the present invention is a single layer without an interlayer boundary inside. Although the content of elements inside the conductive layer changes according to the region inside the conductive layer, it is manufactured in a way that forms a polycrystalline form throughout the region. The reason for manufacturing the conductive layer using a polycrystalline form with smaller grain boundaries is that it has an advantage in conductivity.

[0040] Therefore, the conductive layer of the conductive particles applicable to one embodiment of the present invention contains two or more elements, and is a polycrystalline layer of a single layer having crystal grains with an average major axis length of 8 to 13 nm and no interlayer boundaries.

[0041] At this time, as a result of measuring the diffraction patterns of all regions of the conductive layer using X-ray diffraction (XRD), a plurality of diffraction rings are formed, and the radius of the innermost diffraction ring among the formed diffraction rings is preferably 4.93 ± 0.2 (l / nm). In addition, when measuring the X-ray diffraction (XRD) diffraction pattern, the radius of the diffraction ring is measured in the reciprocal lattice, and thus l / nm is used as a unit for convenience.

[0042] The size of the crystal grains and the length of the radius of the innermost diffraction ring as described above depend on the types, contents, and reaction rates of the elements used. That is, since the elements and their contents contained inside the conductive layer of the present invention vary according to regions, the radius of the innermost diffraction ring in each region of the conductive layer will also change in the size of the crystal grains or the results of measuring the diffraction patterns of all regions of the conductive layer using X-ray diffraction (XRD).

[0043] At this time, even when the content varies in different regions, the conductive layer of the present invention has crystal grain sizes with an average major axis length of 8 to 13 nm in all regions of the conductive layer, and the radius of the innermost diffraction ring among the diffraction rings of the X-ray diffraction (XRD) analysis diffraction pattern is within 4.93 (l / nm) ± 0.2 (l / nm). Thereby, a single layer with a relatively high adhesion force to the insulating core and no interlayer boundaries formed within the conductive layer can be formed.

[0044] For example, the conductive layer can be divided into a first region adjacent to the insulating core, a second region adjacent to the first region, and a third region adjacent to the second region and located on the outermost side based on regions, and the conductive layer can also be divided into a fourth region formed with a first content, a fifth region formed with a second content, and a sixth region formed with a third content based on content.

[0045] At this time, the conductive layer applicable to the embodiment of the present invention satisfies the above-described average major axis length and the radius range of the innermost diffraction ring in the first region, the second region, and the third region or the fourth region, the fifth region, and the sixth region.

[0046] Through Figure 1 the field emission transmission electron microscope (FETEM) photograph of the conductive layer of the conductive particles applicable to one embodiment of the present invention taken at a magnification of 500,000 and Figure 2The diffraction pattern obtained by X-ray diffraction (XRD) analysis of the conductive layer can confirm that the conductive layer of the embodiment to which the present invention is applied is a crystal form having grain boundaries as described above.

[0047] As Figure 1 shown, grain boundaries with different crystallization directions can be observed, whereby a polycrystalline conductive layer can be confirmed. In addition, it can be confirmed that the size of the grains of the conductive particles is 5.13 to 12.76 nm based on the major axis, with an average of approximately 9.76 nm.

[0048] In addition, Figure 2 multiple diffraction rings appear, whereby its crystallinity can be confirmed. At this time, the radius of the innermost diffraction ring in the diffraction rings is within the range described above.

[0049] In addition, the manufacturing method of the single-layer conductive layer containing two or more elements, having no interlayer boundary surface, and having a grain boundary size of polycrystalline to which the embodiment of the present invention is applied is not particularly limited, and can be achieved by electroless plating by adjusting the element content and reaction rate in the gold plating layer.

[0050] For example, electroless Ni plating can use sodium hypophosphite for Ni-P plating according to the type of reducing agent; use sodium borohydride (SHB), dimethyl amine borane (DMAB), diethyl amine borane (DEAB), etc. for Ni-B plating; use hydrazine for Ni-N plating to form a gold plating surface layer. In addition, alloy electroless plating such as Ni-P-W, Ni-B-W, Ni-P-Co-W, Ni-B-Co-W, Ni-W, Ni-Co, Ni-Pd, Ni-P-Pd, etc. can be carried out by adding metal salts containing metals such as Pd, Pt, W, Au, Ag, Mo, and Co.

[0051] At this time, in electroless plating with Ni-P as the main component, when the P content is relatively high, although the corrosion resistance can be improved by forming an amorphous layer, there are problems of weak strength and an increase in resistance in terms of conductivity (P is 110 μΩcm @ 20 °C, while Ni is 6.97 μΩcm @ 20 °C). Therefore, controlling the P content to less than 3% is beneficial to the formation of crystal form.

[0052] In addition, in electroless plating with Ni-B as the main component, because the specific resistance of B is very high (1.5×10^12 μΩcm @ 20 °C), as long as a few percent of B is contained, an amorphous gold plating layer will be formed. Therefore, controlling the B content to less than 0.5% is beneficial to the formation of crystal form.

[0053] In electroless gold plating with Ni-N as the main component, although its corrosion resistance is lower than that of Ni-P and Ni-B, a crystalline conductive layer can be formed when the content of N is 2% or less.

[0054] In addition, the conductive layer composed of Ni-P, Ni-B, and Ni-N as described above can also be used. However, in cases where strength or corrosion resistance is particularly required or in order to ensure other physical properties, elements such as Pd, Pt, W, Au, Ag, Mo, and Co can be further included and a single crystalline gold plating layer can be formed using an alloy electroless gold plating method.

[0055] At this time, in order to form a polycrystalline form without interlayer boundaries and with a small grain size, it is necessary to control the reaction rate while controlling the content of elements. The reaction rate can be adjusted using the amount of reducing agent, the temperature of the plating solution, and the pH.

[0056] In the case where the reaction rate is too slow, the gold plating layer will be formed in an amorphous form. In the case where the reaction rate is too fast, the plating may be unstable or defective due to the disruption of the balance of the plating solution, making it difficult to commercialize the product.

[0057] The shape of the protrusions of the conductive particles of the present invention is not particularly limited. It can be shapes such as spherical, needle-shaped, and polygonal. The shape of the protrusions of the present invention is not particularly limited. Preferably, the size of the protrusions is a protruding form of 50 nm to 500 nm, and more preferably, the size of the protrusions is 100 to 300 nm.

[0058] The method for forming the protrusions of the conductive particles of the present invention is not particularly limited. For example, after coating a catalyst substance on the surface of the insulating core particles, a conductive layer and protrusions can be formed by electroless gold plating. A conductive layer and protrusions can also be formed by electroless gold plating after adhering small metal or inorganic particles to the insulating core particles.

[0059] It is advisable to form an insulating layer on the outermost contour of the conductive particles of the present invention. With the miniaturization and increased integration of electronic products, the pitch of the electrodes will become smaller. Therefore, in the case where there are no insulating particles on the outermost contour, electrical conduction with adjacent electrodes may occur. As methods for forming the insulating layer, there are methods such as chemically attaching insulating particles to the outermost contour of the conductive particles using functional groups, coating by spraying or dipping after dissolving the insulating solution in a solvent, and coating by hot air and impact after attaching the insulating particles to the outermost contour of the conductive particles, etc.

[0060] It is advisable to perform rust prevention treatment on the conductive layer of the conductive particles of the present invention. This is because, through rust prevention treatment, the contact angle with water can be increased, thereby improving the reliability in a high-humidity environment, and the performance degradation of the connecting components caused by impurities dissolving in water can also be reduced. Therefore, a rust inhibitor with hydrophobicity is usually used. As the coating method, methods such as impregnation and spraying after dissolving the rust inhibitor in a solvent can be adopted.

[0061] The present invention can manufacture an anisotropic conductive material by dispersing conductive particles into a binder resin. The anisotropic conductive material includes anisotropic conductive paste, anisotropic conductive film, anisotropic conductive sheet, etc.

[0062] The resin binder is not particularly limited. For example, vinyl resins such as styrene-based, acrylic-based, and vinyl acetate-based resins, thermoplastic resins such as polyolefin and polyamide, curable resins such as polyurethane and epoxy resin, etc. can be used. The resins can be used alone or in combination of two or more. For the purpose of polymerization or curing, radical initiators such as benzoyl peroxide (BPO) or photoinitiators such as trimethylbenzoyl phenylphosphinate (TPO), epoxy resin latent curing agents such as HX3941HP, etc. can be used alone or in combination. In addition, other substances can be added to the anisotropic conductive material binder resin within the range that does not hinder the achievement of the object of the present invention. For example, colorants, softeners, heat stabilizers, light stabilizers, antioxidants, and inorganic particles can be added.

[0063] The manufacturing method of the anisotropic conductive material is not particularly limited. For example, it can be used as an anisotropic conductive paste by uniformly dispersing conductive particles into a resin binder, or it can be coated thinly on a release paper to be used as an anisotropic film.

[0064] The connection structure of the present invention is a connection structure that connects circuit boards using the conductive particles or the anisotropic conductive material of the present invention between circuit boards. For example, it can be used in the connection between the display semiconductor chip of a smart phone and the glass substrate constituting the circuit, or as a method for connecting μ-LED and mini-LED to a circuit board.

[0065] <Example 1>

[0066] 1) Synthesis of insulating core particles

[0067] After adding 1,100 g of tetramethylolmethane tetraacrylate (TMMT), 400 g of divinylbenzene (DVB), 15 g of 1,6 - hexanediol diacrylate (HDDA), and 30 g of styrene into a 3 L glass beaker, and then adding 5 g of an initiator, benzoyl peroxide (BPO), a treatment is carried out in a 40 kHz ultrasonic bath for 10 minutes to prepare a first solution.

[0068] Add 3,000 g of deionized water, 500 g of a dispersion stabilizer, polyvinylpyrrolidone (PVP) - 30K, and 200 g of a surfactant, dioctyl sulfosuccinate sodium salt (Solusol) into a 5 L polypropylene (PP) beaker to prepare a second solution.

[0069] Put the first solution and the second solution into a 50 L reactor and add 40,000 g of deionized water. Next, perform a treatment with an ultrasonic homogenizer (Homogeniser, 20 kHz, 600 W) for 90 minutes. While rotating the solution at 120 rpm, heat it up to 35 °C and maintain it for 3 hours. Then, heat it up to 85 °C again and maintain it for 16 hours after the solution reaches 85 °C to carry out a polymerization process treatment.

[0070] Obtain core resin particles by performing filtration, washing, classification, and drying processes on the polymerized particles. As the average diameter of the manufactured core resin particles, the mode value measured using a laser particle size analyzer (Particle Size Analyzer, BECKMAN MULTISIZER TM3) is used. The number of core particles measured at this time is 75,000. Its average diameter is 3.51 μm.

[0071] 2) Formation of a conductive layer on the outer contour of the insulating core particles

[0072] ① Catalyst treatment process

[0073] Put 30 g of the manufactured insulating core particles into a solution containing 800 g of deionized water, 0.5 g of a surfactant, Triton X100, and 10 g of sulfuric acid, and perform a treatment in an ultrasonic bath for 1 hour to carry out a washing and degreasing process to remove excess unreacted monomers and grease components present on the insulating core particles. At the end of the washing and degreasing process, perform 3 times of water washing with 45 °C deionized water.

[0074] The insulating core particles that have completed the degreasing and water washing processes are put into a solution prepared by dissolving 150 g of stannous chloride and 300 g of 35 - 37% hydrochloric acid in 600 g of deionized water, and subjected to sensitization treatment by impregnation and stirring at 30 °C for 30 minutes, followed by three water washes.

[0075] The sensitized insulating core is put into 1 g of palladium chloride, 200 g of 35 - 37% hydrochloric acid, and 600 g of deionized water, and subjected to activation treatment at 40 °C for 1 hour. During the activation treatment, ultrasonic waves are applied using an ultrasonic bath. After the activation treatment, three water washing processes are carried out.

[0076] The activated insulating core is put into a solution of 100 g of 35 - 37% hydrochloric acid and 600 g of deionized water and stirred at room temperature for 10 minutes for acceleration treatment. After the acceleration treatment, three water washes are carried out to obtain the insulating core treated with electroless gold plating catalyst.

[0077] ② Gold plating process

[0078] 3500 g of deionized water is put into a 5 L reactor, and 70 g of nickel sulfate as a Ni salt, 5 g of sodium acetate as a complexing agent, 2 g of lactic acid, 0.001 g of Pb - acetate and 0.001 g of sodium thiosulfate as stabilizers, and 1 g of PEG - 600 as a surfactant are dissolved in sequence to prepare solution a. The catalyst - treated insulating core is put into the prepared solution a, and subjected to dispersion treatment for 10 minutes using an ultrasonic homogenizer. After the dispersion treatment, the pH of the solution is adjusted to 8.0 with ammonia water - solution b.

[0079] Solution c is prepared by dissolving 300 g of deionized water, 33 g of dimethylaminobenzaldehyde (DMAB) as a reducing agent, and 0.002 g of sodium thiosulfate as a stabilizer in a 1 L beaker.

[0080] Solution d is prepared by dissolving 500 g of deionized water, 155 g of nickel sulfate, and 10 g of sodium hydroxide in a 1 L beaker.

[0081] While maintaining the temperature of the 5 L reactor solution b at 20 °C, solution c is fed in at a rate of 5 g per minute using a metering pump, and after heating the reactor temperature to 35 °C at a heating rate of 0.33 °C per minute, it is maintained.

[0082] Before the temperature of the 5 L reactor solution b reached 35°C, ammonia water was additionally added to adjust the pH to 8.0, and no ammonia water was added after 75°C.

[0083] After introducing the solution c and waiting for 5 minutes, solution d was introduced into the 5 L reactor at a rate of 20 g per minute using a metering pump.

[0084] After the introduction of the solution c was completed, it was maintained for 30 minutes to obtain Ni-plated conductive particles.

[0085] <Example 2>

[0086] Except for adding 3 g of potassium gold cyanide to solution d based on Example 1, it was manufactured in the same manner.

[0087] <Example 3>

[0088] 2500 g of deionized water was introduced into a 5 L reactor, and 70 g of nickel sulfate as a Ni salt, 5 g of sodium acetate as a complexing agent, 2 g of lactic acid, 0.001 g of Pb-acetate and 0.001 g of sodium thiosulfate as stabilizers, and 1 g of PEG-600 as a surfactant were dissolved in sequence to produce solution a. The catalyst-treated insulating core was introduced into the produced solution a, and dispersion treatment was performed for 10 minutes using an ultrasonic homogenizer. After the dispersion treatment, the pH of the solution was adjusted to 5.5 - solution b using ammonia water.

[0089] Solution c was prepared by dissolving 500 g of deionized water, 280 g of sodium hypophosphite as a reducing agent, and 0.002 g of sodium thiosulfate as a stabilizer in a 1 L beaker.

[0090] Solution d was prepared by dissolving 500 g of deionized water, 155 g of nickel sulfate, and 5 g of sodium hydroxide in a 1 L beaker.

[0091] While maintaining the temperature of the 5 L reactor solution b at 65°C, solution c was introduced at a rate of 5 g per minute using a metering pump, and after heating the reactor temperature to 75°C at a heating rate of 0.33°C and then maintaining it.

[0092] Before the temperature of the 5 L reactor solution b reached 75°C, ammonia water was additionally added to adjust the pH to 5.5, and no ammonia water was added after 75°C.

[0093] After introducing the solution c and waiting for 5 minutes, solution d was introduced into the 5 L reactor at a rate of 20 g per minute using a metering pump.

[0094] After the introduction of solution c was completed, the mixture was maintained for 30 minutes to obtain conductive particles with a crystalline Ni-P gold plating layer formed thereon.

[0095] <Example 4>

[0096] Manufacture was carried out in the same manner except that solution d was prepared by dissolving 500 g of deionized water, 155 g of nickel sulfate, 10 g of hydrochloric acid, and 0.5 h of palladium chloride (PdCl2) on the basis of Example 1.

[0097] <Test Example>

[0098] The conductive particles obtained through Examples 1 to 4 were evaluated.

[0099] 1) Measurement of the size of the insulating core particles

[0100] As the average diameter of the insulating core particles, the mode value measured using a laser particle size analyzer (Particle Size Analyzer, BECKMAN MULTISIZER TM3) was used. The number of conductive particles measured at this time was 75,000.

[0101] 2) X-ray diffraction (XRD) analysis

[0102] In Table 1, the radii of the first to fourth (1st - 4th) diffraction rings measured in the diffraction pattern obtained by X-ray diffraction (XRD, X-ray diffraction - SmartLab) using a Cu target on the conductive layer of the conductive particles are tabulated. At this time, as the radius of the diffraction ring, after calculating four diameters passing through the center for one diffraction ring in the manner shown in Figure 3 using an electron micrograph (Digital Micrograph, ver3.42.3048.0), the average value of the four diameters was calculated, and finally divided by 2 to calculate the radius r. In addition, as the measurement sites of the measured conductive layer, the first region adjacent to the insulating core, the second region adjacent to the first region, and the third region adjacent to the second region and located on the outermost side were measured respectively.

[0103]

Table 1

[0104]

[0105]

[0106] 3) Grain boundary analysis

[0107] The measurement results of the major axis lengths of the grain boundaries of Examples 1 to 3 as described above were tabulated in Table 2.

[0108]

Table 2

[0109]

[0110] 4) Measurement of connection resistance

[0111] ① Fabrication of anisotropic conductive film

[0112] After uniformly stirring 2 g of naphthalene-based epoxy resin HP4032D (manufactured by DIC, trade name), 20 g of phenoxy resin YP-50 (manufactured by TOTOHwaseong, trade name), 25 g of acrylic epoxy resin VR-60 (manufactured by Showa Denko, trade name), 22 g of thermosetting agent HXA-3922HP (manufactured by Asahi Chemical, trade name), and 5 g of epoxy silane coupling agent A-187 (manufactured by Momentive, trade name), a mixture with a solid content of 50% was produced using toluene as a solvent. After adding the conductive particles at a weight ratio of 10% to the mixture, mixing was carried out for 5 minutes using a co-rotating mixer under the conditions of 400 rpm for revolution and 150 rpm for rotation, thereby producing an anisotropic conductive paste. After forming a 20-μm-thick film on a release film using the anisotropic conductive paste, drying was carried out in the atmosphere at 75 °C for 1 minute using a hot air drying path, and finally an anisotropic conductive film with a thickness of 12 μm was produced.

[0113] ② Electrodes for resistance measurement

[0114] As the electrodes for measuring resistance, a glass substrate with a transparent electrode formed by evaporating indium tin oxide (ITO) on the glass substrate and a flexible printed circuit board (FPCB) with an electrode width of 20 μm and an electrode interval of 50 μm were produced.

[0115] ③ Bonding

[0116] The anisotropic conductive film was cut into a width of 3 mm, and using a bonding jig with a width of 1 mm and a length of 30 mm, it was pressed on a substrate with indium tin oxide (ITO) under the conditions of 0.2 MPa, 120 °C, and 10 seconds. Next, after placing the flexible printed circuit board (FPCB), bonding was carried out under the conditions of 45 MPa, 200 °C, and 20 seconds to produce a connection structure.

[0117] ④ Measurement of initial connection resistance

[0118] The resistance of the flexible printed circuit board (FPCB) using the connection structure was measured. The resistance was measured using an ADCMT 6871E Digital Multimeter 2probe.

[0119] ⑤ Reliability Resistance Measurement

[0120] The reliability resistance was measured after placing it at 85°C and 100% humidity for 100 hours.

[0121] To measure the resistance, after putting the connector that had been placed for 100 hours into an oven at 100°C for 24 hours to remove the residual moisture, the resistance was measured using an ADCMT 6871E Digital Multimeter 2probe. The structure is shown in Table 3.

[0122] The criteria for judgment related to the initial contact resistance are as follows.

[0123] OOO: 2Ω or less

[0124] OO: More than 2Ω and 3Ω or less

[0125] O: More than 3Ω and 5Ω or less

[0126] ×: More than 5Ω

[0127] The criteria for judgment related to the increase in connection resistance after 85°C and 100-hour reliability are as follows.

[0128] OOO: An increase of 2Ω or less

[0129] OO: An increase of more than 2Ω and 4Ω or less

[0130] O: An increase of more than 4Ω and 6Ω or less

[0131] ×: An increase of more than 6Ω

[0132]

Table 3

[0133]

[0134] In the features, structures, effects, etc. exemplified in the above-described respective embodiments, those with ordinary knowledge in the field to which the embodiments belong can combine or modify them with other embodiments. Therefore, the content related to the above-described combinations and modifications should also be construed as being included within the scope of the present invention.

Claims

1. A conductive particle, comprising: An insulating core; And, A conductive layer containing at least two elements on the insulating core; In the diffraction pattern obtained by analyzing the conductive layer using X-ray diffraction (XRD), at least two diffraction rings are formed, and the average length of the major axis of the grains of the conductive layer is 8 nm to 13 nm; Wherein, there is no interlayer boundary in the conductive layer; Wherein, the radius of the innermost diffraction ring in the diffraction pattern is 4.93 (l / nm) ± 0.2 (l / nm); The conductive layer contains Ni and at least one element selected from the group consisting of B, P, N, Pd, Pt, W, Au, Ag, Mo, and Co.

2. The conductive particle according to claim 1, When the conductive layer is divided into a first region adjacent to the insulating core, a second region adjacent to the first region, and a third region adjacent to the second region and located on the outermost side, it is a single layer without boundaries between the respective regions of the first region, the second region, and the third region.

3. The conductive particle according to claim 2, The content of the elements in the conductive layer varies according to the first region, the second region, and the third region.

4. The conductive particle according to claim 1, The conductive layer contains Ni and at least two elements selected from the group consisting of B, P, N, Pd, Pt, W, Au, Ag, Mo, and Co.

5. The conductive particle according to any one of claims 1 to 4, An insulating layer or insulating particles are further included on the surface of the conductive layer.

6. The conductive particle according to any one of claims 1 to 4, The outermost contour of the conductive layer is subjected to rust prevention treatment using a hydrophobic rust inhibitor.

7. An anisotropic conductive material, Comprising the conductive particle according to any one of claims 1 to 6.

8. A connection structure, Comprising the conductive particle according to any one of claims 1 to 6.

9. An electronic device, Comprising the conductive particle according to any one of claims 1 to 6.

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