CN111462935A - Conductive particle and method for producing same - Google Patents

Conductive particle and method for producing same Download PDF

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Publication number
CN111462935A
CN111462935A CN202010400236.XA CN202010400236A CN111462935A CN 111462935 A CN111462935 A CN 111462935A CN 202010400236 A CN202010400236 A CN 202010400236A CN 111462935 A CN111462935 A CN 111462935A
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CN
China
Prior art keywords
conductive
particles
particle
dendritic
resin
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
CN202010400236.XA
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Chinese (zh)
Inventor
卞经纬
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Wuxi Wuhao Machinery Equipment Co ltd
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Wuxi Wuhao Machinery Equipment Co ltd
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Priority to CN202010400236.XA priority Critical patent/CN111462935A/en
Publication of CN111462935A publication Critical patent/CN111462935A/en
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
    • H01B1/026—Alloys based on copper
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/04—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of carbon-silicon compounds, carbon or silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/24—Conductive material dispersed in non-conductive organic material the conductive material comprising carbon-silicon compounds, carbon or silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/09—Use of materials for the conductive, e.g. metallic pattern
    • H05K1/092—Dispersed materials, e.g. conductive pastes or inks

Abstract

The conductive particle of the present invention comprises: a core body comprising an electrically conductive substance; and a coating layer which coats the core body, is composed of a conductive material different from the core body, and at least a part of which constitutes an outermost layer. The coating layer may cover at least a part of the core body, and a high coverage ratio is preferable in order to obtain a superior conductive characteristic.

Description

Conductive particle and method for producing same
Technical Field
The present invention relates to conductive particles and a method for producing the same.
Background
A conductive sheet, an electromagnetic wave shielding sheet, or the like is generally used for a printed wiring board. The conductive sheet is required to have a conductive property with excellent stability with time, and therefore, the properties of the conductive filler contained in the sheet are important.
Silver powder is excellent in conductive properties as a conductive filler, and conductive flakes containing silver powder are currently in practical use. However, the price of silver powder is higher than that of resin or other raw materials, which increases the cost. Therefore, due to recent increase in the price of silver, the price of conductive sheets using silver powder or the like has increased to a serious problem.
Disclosure of Invention
The conductive particle of the present invention is a so-called core-shell particle, and includes: a core body comprising an electrically conductive substance; and a coating layer which coats the core body, is composed of a conductive material different from the core body, and at least a part of which constitutes an outermost layer. The coating layer may cover at least a part of the core body, and a high coverage ratio is preferable in order to obtain a superior conductive characteristic. From the viewpoint of the conductive property, the average coverage of the coating layer is 60% or more, more preferably 70% or more, and still more preferably 80% or more.
The conductive particles can be composed of only the core body and the coating layer, and may include other layers. For example, a layer such as an intermediate layer or a bonding layer may be formed between the core body and the coating layer. The core body, the coating layer, and the other layer may be each independently constituted by a single type, or may be constituted by a plurality of types.
The conductive particle of the present invention has an average value of a roundness coefficient obtained by the following formula (1) of 0.15 to 0.4, and has an outer edge formed in at least one of a plurality of notches and branch leaves.
Radius coefficient ═ (area × 4 pi)/(circumference)2Formula (1)
From the circularity coefficient of the above formula (1), the degree of unevenness (undulation) at the outer edge of the conductive particle can be understood. The roundness factor of the whole sphere is 1, and the roundness factor decreases as the roughness increases. That is, the circle diameter coefficient is larger than 0 and 1 or less. The area in the above formula (1) is a length in which the inner area of a line forming the outer periphery in the two-dimensional projection is defined as a flat surface, and the outer periphery of the conductive particle in the two-dimensional projection of the flat surface is defined as a circumferential length.
The core-shell type conductive particles having an average value of the circularity coefficient obtained by the above formula (1) of 0.15 to 0.4 and having a plurality of recesses and/or branches formed on the outer periphery thereof are used, and thus the cost can be reduced, the conductive properties are excellent, and the film can be made thin. The lower limit of the circularity factor is more preferably 0.15 or more, and still more preferably 0.20 or more, from the viewpoint of preventing the conductive filler from penetrating the insulating layer. The upper limit of the circularity coefficient is more preferably 0.4 or less, and still more preferably 0.3 or less, from the viewpoint of sheet resistance of the conductive layer.
As shown in fig. 1-2, the circularity coefficient of the dendritic conductive particles is substantially 0.11 or less, and the circularity coefficient of the scale-like conductive particles is about 0.4 or more and about 0.5 or less.
The conductive particle of the present invention has an average value of a circularity coefficient indicating a degree of circularity, which is obtained by the following formula (2), preferably 2 or more and 5 or less.
The circularity factor (maximum diameter × maximum diameter × pi)/(4 × area) is expressed by the formula (2)
Here, the maximum diameter is the length of the maximum length of the selected particle. From the viewpoint of preventing the conductive filler from penetrating the insulating layer, a more preferable upper limit value of the circularity factor is 4.5 or less, and more preferably 4.0 or less. From the viewpoint of sheet resistance of the conductive layer, a more preferable lower limit value of the circularity factor is 2 or more, and more preferably 2.4 or more. From the circular coefficient, it is known whether the shape of the entire particle is close to a circle (the smaller the value is, the closer to a circle).
The conductive particles of the present invention have a leaf-like conductive particle having at least one of a plurality of scale leaves and branch leaves. The thickness of the conductive particles is preferably 0.1 to 2 μm, more preferably 0.2 to 1 μm.
The conductive particles preferably have an average particle diameter (D50) of 1 to 100 μm. The average particle diameter (D50) of the conductive particles is more preferably 3 μm or more, and still more preferably 50 μm or less.
The core body functions as an inner core portion of the conductive particle. The core body is preferably composed of only a conductive substance from the viewpoint of enhancing the conductive property, but may contain a non-conductive substance. The raw material of the core body is not particularly limited as long as it satisfies these requirements, and examples thereof include conductive metals, conductive carbons, conductive resins, and the like. Examples of the conductive metal include: gold, platinum, copper, nickel, aluminum, iron, an alloy thereof, ITO, or the like, and copper is preferable in terms of price and conductivity. In addition, the conductive carbon is preferably, for example: acetylene black, ketjen black, furnace black, carbon nanotubes, carbon nanofibers, graphite, graphene, and the like. The conductive resin is preferably poly (3, 4-ethylenedioxythiophene), polyacetylene, polysilfuran, or the like. The core body is preferably itself electrically conductive.
The coating layer is made of a conductive material different from the core body. Examples of the conductive material that can be used for the coating layer include those listed as the core body. Among them, the use of a substance having high conductive properties is in accordance with the object of the present invention. Specifically, gold, platinum or silver is preferable, and silver is more preferable. In the conventional technology, a conductive material other than metal, for example, a conductive resin or the like has low conductivity, but if the conductivity is improved by the future technical progress, the conductive resin or the like can be used as the coating layer. From the viewpoint of both cost reduction and improvement of the conductive property, it is preferable to use a conductive material having an excellent conductive property of the coating layer and a conductive material having a cost advantage of the core body. And an electrically conductive intermediate layer may be provided between the core body and the coating layer.
The coating layer is preferably coated at a ratio of 1 to 40 parts by weight, more preferably 5 to 30 parts by weight, and still more preferably 5 to 20 parts by weight, relative to 100 parts by weight of the core body. For example, when copper is used as the core and silver is used as the coating layer, the price of the conductive particles can be effectively reduced while maintaining the conductive properties.
According to the conductive particle of the present invention, the average value of the circularity coefficient is within the above range, and the conductive particle is a leaf-like conductive particle having an outer edge shape including at least one of a notch and a branch, and is excellent in conductive characteristics. Compared with the flaky (scaly) conductive particles with little unevenness or fluctuation, the conductive particles have increased unevenness, and the outer edge of the particles has a leaf-like shape including at least one of notches and branched leaves, so that the contact points of the conductive particles can be increased when the conductive particles are formed into a sheet-like shape. Further, the dendritic conductive particles have a problem that it is difficult to form a thin film, but the conductive particles of the present invention can be easily formed into a thin film. In addition, the core body and the coating layer use different conductive materials, so that the material selection can be increased, and the cost can be reduced.
The method for producing conductive particles of the present invention comprises: the method comprises the steps of preparing conductive dendritic particles and a solid medium for colliding the dendritic particles to deform the dendritic particles (step 1), and colliding the dendritic particles and the solid medium in a closed container to deform the dendritic particles (step 2).
In step 1, dendritic particles are prepared as particles having conductive properties, so-called dendrites (dendrites), as shown in fig. 1-2. As the dendritic particles, non-lobed conductive particles that are precursors of lobed conductive particles including a core body and a coating layer can be suitably used. Further, the dendritic particles may be composed of only the core body. In this case, after the process of step 2, a step of providing a coating layer as the core body of step 3 is performed.
The solid medium is preferably made of metal such as steel, glass, zirconia, alumina, plastic, titania, ceramics, or the like. The closed vessel may be a known dispersing machine such as a ball mill or a sand mill, or a pulverizer. The shape of the solid medium is preferably a concave-convex shape such as a spherical shape or an elliptical shape. The size of the solid medium is, for example, about 0.1 to 3 mm.
And 2, putting the dendritic particles and the solid medium into a closed container, and enabling the dendritic particles to collide with the solid medium. The dendritic particles are subjected to collision with the solid medium to deform the dendritic particles, thereby obtaining leaf-like conductive particles. In the production of the conductive particles, the solid medium may be collided with the resin. The conductive resin composition described later can be produced simultaneously with the production of the conductive particles.
In the production of the conductive particles, a thickener, a dispersant, or the like can be used as an additive for the conductive particles. Excessive sedimentation of particles can be suppressed by using a thickener. Examples of the tackifier include silica-based compounds, polycarbonate-based compounds, polyurethane-based compounds, urea-based compounds, and polyamide-based compounds. The use of the dispersant can improve the dispersibility of the conductive particles. Examples of the dispersant include: an acidic dispersant formed of a carbonic acid or phosphoric acid group, or a salt-type dispersant obtained by neutralizing an acid base group with an amine group-containing basic dispersant.
Drawings
FIG. 1 is an electron micrograph of a scale-like silver powder.
FIG. 2 is an electron micrograph of the dendritic silver-plated copper powder.
Detailed Description
As an example of the conductive particles, a silver-plated copper powder will be described below.
[ example 1]
First, dendritic silver-plated copper powder having silver plating applied to copper powder is prepared. The silver-plated copper powder and the solid medium are put into a closed container, and the solid medium is collided with the silver-plated copper powder in the closed container, so that the dendritic silver-plated copper powder is deformed into the conductive particles. The solid medium is allowed to collide with the branch parts of the silver-plated copper powder, and the conductive particles having the scale leaves or branch leaves of the present invention can be obtained. The conductive resin composition described later can be produced at the same time as the conductive particles by adding the conductive resin composition and the additive.
[ example 2]
First, dendritic copper powder is prepared. The copper powder and the solid medium are put into a closed container, and the solid medium collides with the copper powder in the closed container to deform the dendritic copper powder into the shape of the conductive particle of the invention. The solid medium is allowed to collide with the branch part of the copper powder to obtain the copper powder with scale leaves or branch leaves. Next, the copper powder having the scale leaves or the branch leaves obtained is coated with silver by plating treatment, whereby the conductive particles having the scale leaves or the branch leaves of the present invention can be obtained.
Next, the conductive resin composition of the present invention will be described. The conductive resin composition of the present invention comprises the conductive particles of the present invention and a resin. The conductive resin composition of the present invention may contain conductive particles other than the conductive particles of the present invention. However, the conductive particles other than the conductive particles of the present invention are preferably about 3 parts by weight or less with respect to 100 parts by weight of the resin, for example.
As the resin used for the conductive resin composition, a thermoplastic resin or a curable resin can be used. The curable resin is preferably a thermosetting resin or a photocurable resin.
Examples of the thermoplastic resin include: polyolefin-based resins, vinyl-based resins, styrene/acrylic-based resins, diene-based resins, vinyl-based resins, petroleum resins, cellulose-based resins, polyamide resins, polyurethane resins, polyester resins, polycarbonate resins, polyimide-based resins, fluorine resins, and the like.
The polyolefin-based resin is preferably a homopolymer or copolymer of ethylene, propylene, and α -olefin compound, and specific examples thereof include ethylene-propylene rubber, olefin-based thermoplastic elastomers, and α -olefin polymers.
The vinyl resin is preferably a polymer obtained by polymerizing vinyl ester such as vinyl acetate or a copolymer of vinyl ester and an olefin compound such as ethylene. Specific examples thereof include: ethylene-vinyl acetate copolymers, partially saponified polyvinyl alcohols, and the like.
The styrene/acrylic resin is preferably a homopolymer or copolymer of styrene, (meth) acrylonitrile, acrylamides, (meth) acrylate, maleimide, and the like. Specifically, examples thereof include: polystyrene, polyacrylonitrile, acrylic acid copolymers, ethylene-methyl methacrylate copolymers, and the like.
The diene resin is preferably a homopolymer or a copolymer of a conjugated diene compound such as butadiene or isoprene, or a hydrogenated product thereof. Specific examples thereof include: ethylene-butadiene rubber, styrene-isoprene block copolymer, and the like.
The terpene resin is preferably a polymer formed from a terpene or a hydride thereof. Specific examples thereof include: a vinyl resin and a hydrogenated vinyl resin.
The petroleum resin is preferably dicyclopentadiene type petroleum resin or hydrogenated petroleum resin.
The cellulose-based resin is preferably a cellulose acetate butyrate resin.
The polycarbonate resin is preferably bisphenol a polycarbonate.
The polyimide-based resin is preferably a thermoplastic polyimide, a polyamideimide resin, or a polyamideimide resin.
The conductive sheet of the present invention includes a conductive layer formed from the conductive resin composition of the present invention. The method for producing the conductive sheet is not particularly limited, and the conductive resin composition is applied to a releasable sheet to form a conductive layer. The conductive sheet may be a single layer of only a conductive layer, or may be a laminate of other functional layers, support layers, or the like. Examples of the functional layer include layers having insulation properties, thermal conductivity, electromagnetic wave absorption properties, hard coat properties, water vapor barrier properties, oxygen barrier properties, low dielectric constant properties, high dielectric constant properties, low dissipation factor properties, high dissipation factor properties, heat resistance, and the like. Among them, when the conductive sheet of the present invention is used in the field of printed wiring boards, it preferably contains a thermosetting resin from the viewpoint of heat resistance.
The foregoing coating method can use, for example: gravure printing, contact coating, die coating, lip coating, comma coating, doctor blade coating, roll coating, knife coating, spray coating, bar coating, spin coating, dip coating, and the like.
The thickness of the conductive layer in the conductive sheet is preferably 1 to 100 μm, and more preferably 3 to 50 μm.
The electromagnetic wave shielding sheet of the present invention comprises a conductive layer and an insulating layer formed from the conductive resin composition of the present invention. The method for producing the electromagnetic wave shielding sheet is not particularly limited, and a method for bonding the conductive layer and the insulating layer produced by the above-described method is used. The insulating layer may be a previously formed insulating film, or an insulating resin composition may be applied to a releasable sheet to form an insulating layer, and the insulating layer may be bonded to a conductive layer with the releasable sheet. Alternatively, the insulating layer may be formed by directly applying an insulating resin composition to the conductive layer.

Claims (5)

1. A conductive particle is a leaf-shaped particle, wherein a plurality of projections and/or recesses are formed on the outer edge of the leaf-shape, and the average value of the radius coefficient obtained by the following formula (1) is 0.15 to 0.4;
radius coefficient ═ (area × 4 pi)/(circumference)2Formula (1);
wherein the circumference is a length of an outer periphery of the conductive particle when projected two-dimensionally; the area is a size of a region defined by an outer periphery when the conductive particles are projected two-dimensionally.
2. The conductive particle according to claim 1, wherein the thickness is 0.1 μm or more and 2 μm or less.
3. The conductive particle according to claim 1 or 2, wherein the leaf-like particle is a film-formed dendritic particle; the said bulge and the said notch leave the trace of the branch of the said dendritic particle.
4. A conductive resin composition comprising the conductive particles as set forth in any one of claims 1 to 3 and a resin.
5. A method for manufacturing conductive particles, comprising the steps of: a step of preparing conductive dendritic particles and a solid medium for colliding the dendritic particles to deform the dendritic particles; and a step of causing the dendritic particles and the solid medium to collide with each other in a closed container, thereby deforming the dendritic particles so that an average value of a radius coefficient obtained by the following formula (1) is 0.15 or more and 0.4 or less, and a plurality of recesses and/or projections are formed in an outer edge shape;
radius coefficient ═ (area × 4 pi)/(circumference)2Formula (1);
wherein the circumference is a length of an outer periphery of the conductive particle when projected two-dimensionally; the area is a size of a region defined by an outer periphery when the conductive particles are projected two-dimensionally.
CN202010400236.XA 2020-05-12 2020-05-12 Conductive particle and method for producing same Withdrawn CN111462935A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010400236.XA CN111462935A (en) 2020-05-12 2020-05-12 Conductive particle and method for producing same

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Application Number Priority Date Filing Date Title
CN202010400236.XA CN111462935A (en) 2020-05-12 2020-05-12 Conductive particle and method for producing same

Publications (1)

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CN111462935A true CN111462935A (en) 2020-07-28

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Country Status (1)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103391973A (en) * 2011-03-01 2013-11-13 纳美仕有限公司 Electrically conductive composition
CN104170023A (en) * 2012-03-06 2014-11-26 东洋油墨Sc控股株式会社 Conductive fine particles, method for manufacturing same, conductive resin composition, conductive sheet, and electromagnetic shielding sheet
CN107427912A (en) * 2015-03-26 2017-12-01 住友金属矿山株式会社 Cover silver-bearing copper powder and the conductive paste, conductive coating paint, conductive sheet of silver-bearing copper powder are covered using this

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103391973A (en) * 2011-03-01 2013-11-13 纳美仕有限公司 Electrically conductive composition
CN104170023A (en) * 2012-03-06 2014-11-26 东洋油墨Sc控股株式会社 Conductive fine particles, method for manufacturing same, conductive resin composition, conductive sheet, and electromagnetic shielding sheet
CN106424711A (en) * 2012-03-06 2017-02-22 东洋油墨Sc控股株式会社 Conductive fine particles, method for manufacturing same, conductive resin composition, conductive sheet, and electromagnetic shielding sheet
CN107427912A (en) * 2015-03-26 2017-12-01 住友金属矿山株式会社 Cover silver-bearing copper powder and the conductive paste, conductive coating paint, conductive sheet of silver-bearing copper powder are covered using this

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Application publication date: 20200728