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CN-122029306-A - Method for producing conductive particles and conductive powder

CN122029306ACN 122029306 ACN122029306 ACN 122029306ACN-122029306-A

Abstract

A method for producing conductive particles, comprising a first step of mixing core particles with an electroless nickel plating bath containing a nickel salt, a reducing agent and a complexing agent to prepare a slurry containing primary plating particles having a nickel initial thin film layer formed on the surfaces of the core particles, and a second step of continuously adding an aqueous solution containing the nickel salt, an aqueous solution containing the reducing agent and an aqueous solution containing an alkali to the slurry obtained in the first step, and thereafter stopping the addition and holding the slurry for a period of 10 minutes to 120 minutes, and then continuously adding the aqueous solution containing the nickel salt, the aqueous solution containing the reducing agent and the aqueous solution containing an alkali to the slurry again to perform electroless plating treatment on the primary plating particles.

Inventors

  • Keidai Ohata
  • Gao Qiaozhe

Assignees

  • 日本化学工业株式会社

Dates

Publication Date
20260512
Application Date
20241011
Priority Date
20231013

Claims (6)

  1. 1. A method for producing conductive particles, comprising: A first step of mixing core particles with an electroless nickel plating bath containing a nickel salt, a reducing agent and a complexing agent to prepare a slurry containing primary plating particles having a nickel initial thin film layer formed on the surfaces of the core particles, and And a second step of continuously adding an aqueous solution containing a nickel salt, an aqueous solution containing a reducing agent, and an aqueous solution containing a base to the slurry obtained in the first step, stopping the addition and holding the slurry for a period of 10 minutes to 120 minutes, and continuously adding the aqueous solution containing a nickel salt, the aqueous solution containing a reducing agent, and the aqueous solution containing a base to the slurry again, thereby subjecting the primary plating particles to electroless plating.
  2. 2. The method for producing conductive particles according to claim 1, wherein, The addition time when the aqueous solution containing nickel salt, the aqueous solution containing the reducing agent, and the aqueous solution containing the alkali are continuously added to the slurry obtained in the first step is 25 minutes or longer.
  3. 3. The method for producing conductive particles according to claim 1 or 2, After the slurry is held in the second step, the addition time when the aqueous solution containing nickel salt, the aqueous solution containing reducing agent, and the aqueous solution containing alkali are continuously added again is 40 minutes or longer.
  4. 4. The method for producing conductive particles according to claim 1 or 2, In the second step, an aqueous solution containing a nickel salt and a mixed aqueous solution containing a reducing agent and a base are added to the slurry of the first step, respectively.
  5. 5. The method for producing conductive particles according to claim 1 or 2, In the second step, the metal nanoparticles are added during stopping the addition of the aqueous solution containing nickel salt, the aqueous solution containing the reducing agent, and the aqueous solution containing the base and maintaining the slurry.
  6. 6. A conductive powder is characterized in that, Which is composed of conductive particles having protrusions on the surface of the particles, When 0.05g of the conductive powder was put into a SUS cylindrical container having a diameter of 150mm, and the SUS cylindrical hammer having a weight of 2kg was rotated 20 times to mill the conductive powder, the number of falling protrusions per 100 conductive particles was 5 or less.

Description

Method for producing conductive particles and conductive powder Technical Field The present invention relates to a method for producing conductive particles, and a conductive powder containing the conductive particles. Background As conductive particles used as a conductive material of an anisotropic conductive material such as an anisotropic conductive film or an anisotropic conductive paste, conductive particles in which a conductive layer made of a metal is formed on the surface of a core particle are generally known. In recent years, along with miniaturization and miniaturization of electronic devices, in connection between electrode terminals having a small pitch, an electric connection between an electrode and a wiring is realized by a conductive layer of conductive particles. As the conductive layer of the conductive particles, a coating film formed by plating a surface of the core particles with a metal such as nickel by electroless plating is often used, and various efforts have been made to achieve the target characteristics. As an example, patent document 1 discloses that conductive particles having a protruding structure on the surface are obtained by electroless plating with fine particles of an amino resin present on the surface of a base material particle. Patent document 1 describes that since the surface of the base material particles has excellent adhesion to the amino resin fine particles, the conductive particles thus obtained can have both good conductivity and connection reliability without coming off the protrusions. Patent document 2 discloses resin particles each including a spherical portion and a peripheral portion having a plurality of projections formed on the surface thereof, wherein the resin particles having a composition different from that of the spherical portion and the peripheral portion are subjected to electroless plating to obtain conductive particles each having projections formed on the surface thereof. Patent document 3 discloses that, by electroless plating of resin particles composed of a peripheral portion having a plurality of protruding portions on the surface and a spherical portion surrounded by the peripheral portion, conductive particles having protrusions formed on the surface can be obtained as in patent document 2. Both of these documents describe that connection reliability can be ensured by suppressing the disengagement of the protrusions. Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2011-150802 Patent document 2 International publication WO2015/141716 pamphlet Patent document 3 Japanese patent laid-open publication 2016-85959 Disclosure of Invention Technical problem to be solved by the invention As an object of forming the protrusions on the conductive layer of the conductive particles, the protrusions are mainly used to pierce the oxide film present on the electrode surface, thereby reducing the connection resistance and improving the connection reliability at the time of connection between the electrodes. However, since the conductive particles described in the above patent documents each have a conductive layer formed on the core resin particles having the protrusions, the protrusions are difficult to separate, but there is room for improvement in connection reliability and connection resistance. That is, although the strength of the protrusions is desired to be high in order to pierce the oxide film of the electrode, when the inside of the protrusions is made of resin, sufficient strength cannot be obtained, and it tends to be difficult to pierce the oxide film, and since the conductive layer of the thin film is formed in the protrusion-shaped portion made of resin, there is a tendency that the resistance is higher than that of the protrusions made of only metal. On the other hand, conductive particles having protrusions made of only metal have advantages of higher strength and lower resistance than those described in the above patent document, but since the protrusions are formed to protrude directly from the conductive layer, there is a problem in that the protrusions are easily detached from the conductive layer by an impact from the outside. That is, if stable and fixed protrusions can be formed on the conductive layer, it is possible to provide conductive particles excellent in connection reliability and connection resistance. Accordingly, an object of the present invention is to provide conductive particles which can effectively pierce an oxide film of an electrode by forming stable and fixed protrusions on a conductive layer of the conductive particles to prevent the protrusions from coming off. Technical means for solving the technical problems As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have found that self-decomposed substances, which are generated in an electroless nickel plating bath and become nuclei of protrusion