JP2017069191A - Conductive particle, conductive material and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive particle capable of electrically connecting electrodes at low voltage and capable of reducing connection resistance even when electrodes are electrically connected at low voltage.SOLUTION: The conductive particle has a substrate particle and a conductive part arranged on a surface of the substrate particle, a ratio of compressive elasticity modulus at 20% compression to compressive elasticity modulus at 40% compression is 1.35 or more, a ratio of compressive elasticity modulus at 30% compression to compressive elasticity modulus at 40% compression is 0.85 or more and compressive recovery rate at 40% compression is 30% or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive particle in which a conductive portion is arranged on the surface of a base particle. The present invention also relates to a conductive material and a connection structure using the conductive particles.

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

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

As an example of the conductive particles, Patent Document 1 below discloses conductive particles having polymer particles and a conductive metal layer on the surface of the polymer particles. The breaking point load of the polymer particles is 9.8 mN (1.0 gf) or less. Patent Document 1 describes that the 10% K value of the polymer particles may be 7350 N / mm ² (750 kgf / mm ² ) to 49000 N / mm ² (5000 kgf / mm ² ).

Patent Document 2 below discloses conductive particles having a compression hardness of 150 to 400 Kgf / mm ² at 30% compression deformation.

WO2012 / 020799A1 JP 2013-171656 A

  In recent years, flexible panels that can be bent freely have been developed. In the flexible panel, a flexible printed circuit board made of plastic such as polyimide or polyester is used as the panel substrate.

  For example, when an anisotropic conductive material is used to electrically connect an electrode of a semiconductor chip and an electrode of a flexible printed board, an anisotropic material containing conductive particles between the flexible printed board and the semiconductor chip is used. An electrically conductive material is disposed. Next, it heats and pressurizes. Accordingly, the anisotropic conductive material is cured, and the electrodes are electrically connected through the conductive particles to obtain a connection structure.

  When the driving semiconductor chip is directly mounted on the flexible flexible printed circuit board as described above, it is necessary to perform mounting at a low pressure in order to suppress deformation of the flexible printed circuit board.

  However, in mounting at low pressure, the conductive particles and the oxide film present on the surface of the electrode are not sufficiently pierced, and the conductive particles are not sufficiently deformed, so that a sufficient contact area with the electrode cannot be secured. , Connection resistance tends to be high. In addition, due to the high compression recovery rate of the conductive particles, when the connection structure after connection is exposed to high temperature and high humidity, a force acts to return the conductive particles to their original shape, resulting in high connection resistance. May be.

  An object of the present invention is to provide conductive particles capable of electrically connecting electrodes at a low pressure and capable of reducing connection resistance even when the electrodes are electrically connected at a low pressure. .

  Another object of the present invention is to provide a conductive material and a connection structure using the conductive particles.

  According to a wide aspect of the present invention, the compression elastic modulus when compressed by 40% of the compression elastic modulus when compressed by 20%, comprising base particles and conductive portions arranged on the surface of the base particles. The ratio of the compression elastic modulus at 30% compression to the compression elastic modulus at 40% compression is 0.85 or higher, and the compression recovery rate at 40% compression is 30%. Conductive particles are provided that are:

On the specific situation with the electroconductive particle which concerns on this invention, the compression elastic modulus when compressed 10% is 5000 N / mm < ² > or more.

  On the specific situation with the electroconductive particle which concerns on this invention, the particle diameter of the said base particle is 1.0 micrometer or more and 5.0 micrometers or less.

  On the specific situation with the electroconductive particle which concerns on this invention, the said base material particle is a resin particle or an organic inorganic hybrid particle.

  On the specific situation with the electroconductive particle which concerns on this invention, the said electroconductive particle has several protrusion on the outer surface of the said electroconductive part.

  On the specific situation with the electroconductive particle which concerns on this invention, the said electroconductive particle is the some core substance which has raised the outer surface of the said electroconductive part so that the said some protrusion may be formed in the said electroconductive part. Is provided.

  On the specific situation with the electroconductive particle which concerns on this invention, the Mohs hardness of the said core substance is 5 or more.

  On the specific situation with the electroconductive particle which concerns on this invention, the surface area of the part with the said protrusion is 30% or more in the total surface area 100% of the outer surface of the said electroconductive part.

  On the specific situation with the electroconductive particle which concerns on this invention, the said electroconductive particle is provided with the insulating substance arrange | positioned on the outer surface of the said electroconductive part.

  On the specific situation with the electroconductive particle which concerns on this invention, the said electroconductive particle is used for conduction | electrical_connection of a flexible printed circuit board.

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

  According to a wide aspect of the present invention, the first connection target member, the second connection target member, the connection portion connecting the first connection target member, and the second connection target member; There is provided a connection structure in which the material of the connection portion is the above-described conductive particles or a conductive material containing the conductive particles and a binder resin.

  In the electroconductive particle which concerns on this invention, the electroconductive part is arrange | positioned on the surface of base material particle, ratio (20% K value / 40% K value) is 1.35 or more, ratio (30% K value) / 40% K value) is 0.85 or more, and the compression recovery rate at 40% compression is 30% or less, so that the electrodes can be electrically connected at a low pressure, and the electrodes can be electrically connected at a low pressure. Even if they are connected, the connection resistance can be lowered.

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

  Details of the present invention will be described below.

(Conductive particles)
The electroconductive particle which concerns on this invention is equipped with base material particle and the electroconductive part arrange | positioned on the surface of this base material particle.

  In the conductive particles according to the present invention, the ratio (20%) of the compressive elastic modulus (20% K value) when the conductive particles are compressed by 20% to the compressive elastic modulus (40% K value) when compressed by 40%. K value / 40% K value) is 1.35 or more.

  In the conductive particles according to the present invention, the ratio (30% K value / 40% K value) of the compression elastic modulus when compressed to 30% to the compressive elastic modulus when compressed by 40% is 0.85 or more.

  The compression recovery rate at 40% compression of the conductive particles according to the present invention is 30% or less.

  In the present invention, since the above configuration is provided, the electrodes can be electrically connected at a low pressure, and the connection resistance can be lowered even if the electrodes are electrically connected at a low pressure. In the present invention, even when mounted at a low pressure, the conductive film or the oxide film present on the surface of the electrode can be sufficiently penetrated, and the conductive particle can be largely deformed to ensure a sufficient contact area with the electrode. . Further, in the present invention, due to the low compression recovery rate of the conductive particles, even if the connection structure after connection is exposed to high temperature and high humidity, the force that the conductive particles try to return to the original shape is excessive. The connection resistance can be kept low without acting.

  The present inventor controls only 20% K value, only 30% K value, only 40% K value, or the compression recovery rate in conductive particles used for mounting at low pressure. It has been found that it is difficult to reduce the connection resistance and maintain the low connection resistance only by controlling only the control. Furthermore, in order to lower the connection resistance and maintain a low connection resistance, the present inventor has said ratio (20% K value / 40% K value), and said ratio (30% K value / 40% K value). And the compression recovery rate needs to satisfy the above relationship.

  When the ratio (20% K value / 40% K value) is 1.35 or more, the conductive film or the oxide film existing on the surface of the electrode is easily broken at the initial stage of compression of the conductive particles. Since the contact area between the conductive particles and the electrode is increased in the latter half of the compression of the conductive particles, the connection resistance is lowered. From the viewpoint of further reducing the connection resistance, the ratio (20% K value / 40% K value) is preferably 1.5 or more. The upper limit of the ratio (20% K value / 40% K value) is not particularly limited. The ratio (20% K value / 40% K value) may be 5 or less.

  When the ratio (30% K value / 40% K value) is 0.85 or more, the contact area between the conductive particles and the electrode becomes large in the middle and late compression of the conductive particles, so the connection resistance is low. Become. From the viewpoint of further reducing the connection resistance, the ratio (30% K value / 40% K value) is preferably 0.9 or more. The upper limit of the ratio (30% K value / 40% K value) is not particularly limited. The ratio (30% K value / 40% K value) may be 3 or less.

  Since the compression recovery rate at 40% compression of the conductive particles is 30% or less, even if the connected structure after connection is exposed to high temperature and high humidity, the force that the conductive particles try to return to the original shape Does not act excessively, and the connection resistance can be kept low. The compression recovery rate is preferably less than 30%, more preferably 20% or less.

  As a method for controlling the ratio (20% K value / 40% K value), the ratio (30% K value / 40% K value), and the compression recovery rate during the 40% compression within the above range, a base material is used. Method of adjusting physical properties by adjusting particle monomer type, monomer molecular weight, cross-linking material, polymerization temperature, polymerization time, etc., and adjusting the metal type of the conductive part, alloy type, thickness of the conductive part, etc. to adjust the hardness And the like.

From the viewpoint of effectively breaking through the conductive film or the oxide film existing on the surface of the electrode and further reducing the connection resistance, the compression modulus (10% K value) when the conductive particles are compressed by 10% is Preferably it is 5000 N / mm ² or more, more preferably 6500 N / mm ² or more. From the viewpoint of increasing the contact area and further reducing the connection resistance, the 10% K value of the conductive particles is preferably 25000 N / mm ² or less, more preferably 20000 N / mm ² or less.

  The 10% K value, 20% K value, 30% K value and 40% K value of the conductive particles can be measured as follows.

  Using a micro-compression tester, the conductive particles are compressed on a cylindrical indenter end face (diameter 50 μm, made of diamond) under conditions of applying a maximum test load of 90 mN over 30 seconds at 25 ° C. The load value (N) and compression displacement (mm) at this time are measured. From the measured value obtained, the compression elastic modulus can be obtained by the following formula. As the micro compression tester, for example, “Fischer Scope H-100” manufactured by Fischer is used.

K value (N / mm ² ) = (3/2 ^1/2 ) · F · S ⁻³ / ² · R ^−1/2
F: Load value when the conductive particles are 10%, 20%, 30% or 40% compressively deformed (N)
S: Compression displacement (mm) when conductive particles are 10%, 20%, 30% or 40% compressively deformed
R: radius of conductive particles (mm)

  The compression recovery rate can be measured as follows.

  Spread conductive particles on the sample stage. About one dispersed conductive particle, 40% of the conductive particles are in the center direction of the conductive particles at 25 ° C. on the end surface of a cylindrical indenter (diameter: 100 μm, made of diamond) using a micro compression tester. Apply a load (reverse load value) until compressive deformation. Thereafter, unloading is performed up to the origin load value (0.40 mN). The load-compression displacement during this period is measured, and the compression recovery rate can be obtained from the following equation. The load speed is 0.33 mN / sec. As the micro compression tester, for example, “Fischer Scope H-100” manufactured by Fischer is used.

  Compression recovery rate (%) = [(L1-L2) / L1] × 100

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

  From the viewpoint of further reducing the connection resistance and further improving the conduction reliability, the surface area of the portion having the protrusion is preferably 10% or more, more preferably 30% or more, out of the total surface area of 100% of the conductive particles. Preferably, it is 95% or less, more preferably 90% or less.

  Hereinafter, the present invention will be specifically described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing conductive particles according to the first embodiment of the present invention.

  The conductive particles 1 shown in FIG. 1 have base material particles 2 and conductive portions 3. The conductive portion 3 is disposed on the surface of the base particle 2. In the first embodiment, the conductive portion 3 is in contact with 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. In the conductive particle 1, the conductive part 3 is a single-layer conductive part (conductive layer).

  Unlike the conductive particles 11 and 21 described later, the conductive particles 1 do not have a core substance. The conductive particles 1 do not have protrusions on the conductive surface, and do not have protrusions on the outer surface of the conductive portion 3. The conductive particles 1 are spherical.

  As described above, the conductive particles according to the present invention may not have protrusions on the conductive surface, may not have protrusions on the outer surface of the conductive portion, and may be spherical. . Moreover, the electroconductive particle 1 does not have an insulating substance unlike the electroconductive particles 11 and 21 mentioned later. However, the conductive particles 1 may have an insulating substance disposed on the outer surface of the conductive portion 3.

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

  A conductive particle 11 shown in FIG. 2 includes a base particle 2, a conductive portion 12, a plurality of core substances 13, and a plurality of insulating substances 14. The conductive portion 12 is disposed on the surface of the base particle 2 so as to be in contact with the base particle 2. In the conductive particles 11, the conductive portion 12 is a single-layer conductive portion (conductive layer).

  The conductive particles 11 have a plurality of protrusions 11a on the conductive surface. The conductive portion 12 has a plurality of protrusions 12a on the outer surface. A plurality of core substances 13 are arranged on the surface of the base particle 2. The plurality of core materials 13 are embedded in the conductive portion 12. The core substance 13 is disposed inside the protrusions 11a and 12a. The conductive portion 12 covers a plurality of core substances 13. The outer surface of the conductive portion 12 is raised by the plurality of core materials 13, and protrusions 11 a and 12 a are formed.

  The conductive particles 11 have an insulating substance 14 disposed on the outer surface of the conductive portion 12. At least a part of the outer surface of the conductive portion 12 is covered with the insulating material 14. The insulating substance 14 is made of an insulating material and is an insulating particle. Thus, the electroconductive particle which concerns on this invention may have the insulating substance arrange | positioned on the outer surface of an electroconductive part. However, the conductive particles according to the present invention do not necessarily have an insulating substance.

  FIG. 3 is a cross-sectional view showing conductive particles according to the third embodiment of the present invention.

  The conductive particles 21 shown in FIG. 3 include base material particles 2, conductive portions 22, a plurality of core materials 13, and a plurality of insulating materials 14. The conductive part 22 as a whole has a first conductive part 22A on the base particle 2 side and a second conductive part 22B on the side opposite to the base particle 2 side.

  The conductive particles 11 and the conductive particles 21 differ only in the conductive part. That is, the conductive particles 11 are formed with the conductive portion 12 having a single-layer structure, whereas the conductive particles 21 are formed with the first conductive portion 22A and the second conductive portion 22B having a two-layer structure. ing. The first conductive portion 22A and the second conductive portion 22B are formed as separate conductive portions.

  The first conductive portion 22 </ b> A is disposed on the surface of the base particle 2. 22 A of 1st electroconductive parts are arrange | positioned between the base particle 2 and the 2nd electroconductive part 22B. The first conductive portion 22 </ b> A is in contact with the base material particle 2. Accordingly, the first conductive portion 22A is disposed on the surface of the base particle 2, and the second conductive portion 22B is disposed on the surface of the first conductive portion 22A. The conductive particles 21 have a plurality of protrusions 21a on the conductive surface. The conductive portion 22 has a plurality of protrusions 22a on the outer surface. The first conductive portion 22A has a protrusion 22Aa on the outer surface. The second conductive portion 22B has a plurality of protrusions 22Ba on the outer surface. In the conductive particles 21, the conductive portion 22 is a two-layer conductive portion (conductive layer).

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

[Base material particles]
Examples of the substrate particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The base particle may be a core-shell particle including a core and a shell disposed on the surface of the core. The core may be an organic core. The shell may be an inorganic shell. Base particles excluding metal particles are preferable, and inorganic particles or organic-inorganic hybrid particles excluding resin particles, metal particles are more preferable. Resin particles or organic-inorganic hybrid particles are particularly preferred because they are more excellent due to the effects of the present invention.

  The substrate particles are preferably resin particles formed of a resin. When connecting between electrodes using the said electroconductive particle, after arrange | positioning the said electroconductive particle between electrodes, the said electroconductive particle is compressed by crimping | bonding. When the substrate particles are resin particles, the conductive particles are easily deformed during the pressure bonding, and the contact area between the conductive particles and the electrode is increased. For this reason, the conduction | electrical_connection reliability between electrodes becomes high.

  Various resins are suitably used as the resin that is the material of the resin particles. Examples of the resin that is a material of 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; Terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene oxide , Polyacetal, polyimide, polyamideimide, polyetheretherke Emissions, polyethersulfone, and polymers such as obtained by a variety of polymerizable monomer having an ethylenically unsaturated group is polymerized with one or more thereof. Since the hardness of the substrate particles can be easily controlled within a suitable range, the resin for forming the resin particles is obtained by polymerizing one or more polymerizable monomers having a plurality of ethylenically unsaturated groups. A polymer is preferred.

  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. And the monomer.

  Examples of the non-crosslinkable monomer include styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl ( Alkyl (meth) acrylate compounds such as meth) acrylate and isobornyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate, glycidyl (meth) acrylate, etc. Elemental-containing (meth) acrylate compounds; Nitrile-containing monomers such as (meth) acrylonitrile; Halogen-containing substances such as trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride, chlorostyrene And monomers.

  Examples of the crosslinkable monomer include tetramethylolmethane tetra (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipenta Erythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Polyfunctional (meth) acrylate compounds such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanide Silane-containing monomers such as salts, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallylacrylamide, diallyl ether, γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane, etc. Is mentioned.

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

  In the case where the substrate particles are inorganic particles or organic-inorganic hybrid particles excluding metal particles, examples of the inorganic material that is a material of the substrate particles include silica and carbon black. The inorganic substance is preferably not a metal. The particles formed from the silica are not particularly limited. For example, after forming a crosslinked polymer particle by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups, firing may be performed as necessary. The particle | grains obtained by performing are mentioned. Examples of the organic / inorganic hybrid particles include organic / inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

  When the substrate particles are metal particles, examples of the metal that is a material of the metal particles include silver, copper, nickel, silicon, gold, and titanium. However, the substrate particles are preferably not metal particles, and preferably not copper particles.

  The particle diameter of the substrate particles is preferably 0.1 μm or more, more preferably 1.0 μm or more, further preferably 1.5 μm or more, particularly preferably 2.0 μm or more, preferably 1000 μm or less, more preferably It is 500 μm or less, more preferably 300 μm or less, further preferably 50 μm or less, still more preferably 30 μm or less, particularly preferably 8.0 μm or less, and most preferably 5.0 μm or less. When the particle diameter of the substrate particles is equal to or greater than the lower limit, the contact area between the conductive particles and the electrodes is increased, so that the conduction reliability between the electrodes is further increased and the conductive particles are connected via the conductive particles. The connection resistance between the electrodes is further reduced. Further, when the conductive portion is formed on the surface of the base particle by electroless plating, it becomes difficult to aggregate, and the aggregated conductive particles are hardly formed. When the particle diameter of the substrate particles is not more than the above upper limit, the conductive particles are easily compressed, the connection resistance between the electrodes is further reduced, and the interval between the electrodes is further reduced.

  The particle diameter of the base particle indicates a diameter when the base particle is a true sphere, and indicates a maximum diameter when the base particle is not a true sphere.

  The particle diameter of the substrate particles is particularly preferably 1.0 μm or more and 5.0 μm or less. When the particle diameter of the substrate particles is in the range of 1.0 μm or more and 5.0 μm or less, even when the distance between the electrodes is small and the thickness of the conductive part is increased, small conductive particles can be obtained. And connection resistance can be made low effectively.

[Conductive part]
The metal for forming the conductive part is not particularly limited. Examples of the metal include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, ruthenium, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, and silicon. And alloys thereof. Examples of the metal include tin-doped indium oxide (ITO) and solder. Since the connection resistance between the electrodes can be further reduced, an alloy containing tin, nickel, palladium, copper or gold is preferable, and nickel or palladium is preferable.

  Like the conductive particles 1 and 11, the conductive part may be formed of one layer. Like the electroconductive particle 21, the electroconductive part may be formed of the some layer. That is, the conductive part may have a laminated structure of two or more layers. When the conductive portion is formed of a plurality of layers, the outermost layer is preferably a gold layer, a nickel layer, a palladium layer, a copper layer, or an alloy layer containing tin and silver. When the outermost layer is these preferred conductive layers, the connection resistance between the electrodes is further reduced. Further, when the outermost layer is a noble metal layer, the corrosion resistance is further enhanced.

  The method for forming the conductive part on the surface of the substrate particle is not particularly limited. As a method for forming the conductive portion, for example, a method by electroless plating, a method by electroplating, a method by physical vapor deposition, and a method of coating the surface of base particles with metal powder or a paste containing metal powder and a binder Etc. Since formation of the conductive part is simple, a method by electroless plating is preferred. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering.

  The particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 520 μm or less, more preferably 500 μm or less, still more preferably 100 μm or less, still more preferably 50 μm or less, particularly preferably. Is 30 μm or less. When the particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, when the electrodes are connected using the conductive particles, the contact area between the conductive particles and the electrode becomes sufficiently large, and the conductive part When forming the conductive particles, it becomes difficult to form aggregated conductive particles. Further, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive portion is difficult to peel from the surface of the base particle. Further, when the particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, the conductive particles can be suitably used for the use of the conductive material.

  The particle diameter of the conductive particles means the diameter when the conductive particles are true spherical, and means the maximum diameter when the conductive particles have a shape other than the true spherical shape.

  The thickness of the conductive part (total thickness of the conductive part) is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 10 μm or less, more preferably 1 μm or less, and even more preferably 0.5 μm or less, Especially preferably, it is 0.3 micrometer or less. The thickness of the conductive portion is the thickness of the entire conductive layer when the conductive portion is a multilayer. When the thickness of the conductive part is not less than the above lower limit and not more than the above upper limit, sufficient conductivity can be obtained, and the conductive particles are not too hard, and the conductive particles are sufficiently deformed when connecting the electrodes. .

  When the conductive part is formed of a plurality of layers, the thickness of the outermost conductive layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, preferably 0.5 μm or less, more preferably Is 0.2 μm or less. When the thickness of the outermost conductive layer is not less than the above lower limit and not more than the above upper limit, the coating with the outermost conductive layer becomes uniform, the corrosion resistance becomes sufficiently high, and the connection resistance between the electrodes is further increased. Lower. Further, when the outermost layer is a gold layer, the thinner the gold layer, the lower the cost.

  The thickness of the conductive portion can be measured by observing the cross section of the conductive particles using, for example, a transmission electron microscope (TEM).

  From the viewpoint of effectively increasing the conductivity, the conductive particles preferably have a conductive portion containing nickel. In 100% by weight of the conductive part containing nickel, the nickel content is preferably 50% by weight or more, more preferably 65% by weight or more, still more preferably 70% by weight or more, still more preferably 75% by weight or more, and even more preferably. Is 80% by weight or more, particularly preferably 85% by weight or more, and most preferably 90% by weight or more. In 100% by weight of the conductive part containing nickel, the content of nickel is preferably 100% by weight (total amount) or less, 99% by weight or less, or 95% by weight or less. When the nickel content is at least the above lower limit, the connection resistance between the electrodes is further reduced. Moreover, when there are few oxide films on the surface of an electrode or an electroconductive part, there exists a tendency for the connection resistance between electrodes to become low, so that there is much content of nickel.

  The measuring method of content of the metal contained in the said electroconductive part can use various known analytical methods, and is not specifically limited. Examples of this measuring method include absorption spectrometry or spectrum analysis. In the above-mentioned absorption analysis method, a flame absorptiometer, an electric heating furnace absorptiometer or the like can be used. Examples of the spectrum analysis method include a plasma emission analysis method and a plasma ion source mass spectrometry method.

  When measuring the average content of the metal contained in the conductive part, it is preferable to use an ICP emission analyzer. Examples of commercially available ICP emission analyzers include ICP emission analyzers manufactured by HORIBA.

  The conductive part may contain phosphorus or boron in addition to nickel. The conductive portion may contain a metal other than nickel. In the conductive part, when a plurality of metals are included, the plurality of metals may be alloyed.

  In 100% by weight of the conductive part containing nickel and phosphorus or boron, the content of phosphorus or boron is preferably 0.1% by weight or more, more preferably 1% by weight or more, preferably 10% by weight or less, more preferably Is 5% by weight or less. When the content of phosphorus or boron is not more than the above lower limit and the above upper limit, the resistance of the conductive portion is further reduced, and the conductive portion contributes to the reduction of connection resistance.

[Core material]
The conductive particles preferably have protrusions on the conductive surface. The conductive particles preferably have protrusions on the outer surface of the conductive part. It is preferable that there are a plurality of protrusions. An oxide film is often formed on the surface of the electrode connected by the conductive particles. Furthermore, an oxide film is often formed on the surface of the conductive part of the conductive particles. By using the conductive particles having the protrusions, the oxide film is effectively excluded by the protrusions by placing the conductive particles between the electrodes and then pressing them. For this reason, an electrode and electroconductive particle can be contacted still more reliably and the connection resistance between electrodes can be made low. Furthermore, when the conductive particles have an insulating material on the surface, or when the conductive particles are dispersed in a binder resin and used as a conductive material, the conductive particles and the electrodes are separated by protrusions of the conductive particles. The resin in between can be effectively eliminated. For this reason, the conduction | electrical_connection reliability between electrodes becomes still higher.

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

  As a method for forming the protrusions, a method of forming a conductive part by electroless plating after attaching a core substance to the surface of the base particle, and a method of forming a conductive part by electroless plating on the surface of the base particle And a method of forming a conductive part by electroless plating, and a method of adding a core substance in the middle of forming the conductive part by electroless plating on the surface of the substrate particles.

  Examples of the material of the core substance include a conductive substance and a non-conductive substance. Examples of the conductive material include conductive non-metals such as metals, metal oxides, and graphite, and conductive polymers. Examples of the conductive polymer include polyacetylene. Examples of the non-conductive substance include silica, alumina, tungsten carbide, titanium oxide, barium titanate and zirconia. As the metal that is the material of the core substance, the metals mentioned as the material of the conductive material can be used as appropriate.

  Specific examples of the core material include barium titanate (Mohs hardness 4.5), nickel (Mohs hardness 5), silica (silicon dioxide, Mohs hardness 6-7), titanium oxide (Mohs hardness 7), zirconia. (Mohs hardness 8-9), alumina (Mohs hardness 9), tungsten carbide (Mohs hardness 9), diamond (Mohs hardness 10), and the like. The inorganic particles are preferably nickel, silica, titanium oxide, zirconia, alumina, tungsten carbide or diamond, more preferably silica, titanium oxide, zirconia, alumina, tungsten carbide or diamond, titanium oxide, zirconia. Alumina, tungsten carbide or diamond is more preferable, and zirconia, alumina, tungsten carbide or diamond is particularly preferable. From the viewpoint of easily controlling the ratio (20% K value / 40% K value), the ratio (30% K value / 40% K value) and the compression recovery rate within a suitable range, The Mohs hardness is preferably 4 or more, more preferably 6 or more, still more preferably 7 or more, and particularly preferably 7.5 or more.

  The shape of the core material is not particularly limited. The shape of the core substance is preferably a lump. Examples of the core substance include a particulate lump, an agglomerate in which a plurality of fine particles are aggregated, and an irregular lump.

  The average diameter (average particle diameter) of the core substance is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, more preferably 0.2 μm or less. When the average diameter of the core substance is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes is effectively reduced.

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

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

  The average height of the plurality of protrusions is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, more preferably 0.3 μm or less. When the average height of the protrusions is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes is effectively reduced.

[Insulating material]
The conductive particles preferably include an insulating material disposed on the surface of the conductive part. In this case, when the conductive particles are used for connection between the electrodes, a short circuit between adjacent electrodes can be further prevented. Specifically, when a plurality of conductive particles are in contact with each other, an insulating material is present between the plurality of electrodes, so that it is possible to prevent a short circuit between electrodes adjacent in the lateral direction instead of between the upper and lower electrodes. It should be noted that the insulating material between the conductive portion of the conductive particles and the electrode can be easily removed by pressurizing the conductive particles with the two electrodes when connecting the electrodes. When the conductive particles have a plurality of protrusions on the outer surface of the conductive part, the insulating substance between the conductive part of the conductive particles and the electrode can be more easily removed.

  The insulating substance is preferably an insulating particle because the insulating substance can be more easily removed when the electrodes are pressed.

  Specific examples of the insulating resin that is the material of the insulating material include polyolefins, (meth) acrylate polymers, (meth) acrylate copolymers, block polymers, thermoplastic resins, crosslinked thermoplastic resins, heat Examples thereof include curable resins and water-soluble resins.

  The average diameter (average particle diameter) of the insulating material can be appropriately selected depending on the particle diameter of the conductive particles, the use of the conductive particles, and the like. From the viewpoint of improving the insulating performance, insulating materials having different average diameters may be mixed and used. The average diameter (average particle diameter) of the insulating substance is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 1 μm or less, more preferably 0.5 μm or less. When the average diameter of the insulating material is equal to or greater than the lower limit, when the conductive particles are dispersed in the binder resin, the conductive portions in the plurality of conductive particles are difficult to contact each other. When the average diameter of the insulating particles is not more than the above upper limit, it is not necessary to increase the pressure too much in order to eliminate the insulating substance between the electrodes and the conductive particles when connecting the electrodes, There is no need to heat to high temperatures.

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

(Conductive material)
The conductive material according to the present invention includes the conductive particles described above and a binder resin. The conductive particles are preferably dispersed in a binder resin and used as a conductive material. The conductive material is preferably an anisotropic conductive material. The conductive particles and the conductive material are each preferably used for electrical connection between electrodes. The conductive material is preferably a circuit connection material.

  The binder resin is not particularly limited. The binder resin preferably includes a thermoplastic component (thermoplastic compound) or a curable component, and more preferably includes a curable component. Examples of the curable component include a photocurable component and a thermosetting component. It is preferable that the said photocurable component contains a photocurable compound and a photoinitiator. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent. Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers. As for the said binder resin, only 1 type may be used and 2 or more types may be used together.

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

  The conductive material and the binder resin preferably contain a thermoplastic component or a thermosetting component. The conductive material and the binder resin may contain a thermoplastic component or may contain a thermosetting component. The conductive material and the binder resin preferably contain a thermosetting component. The thermosetting component preferably contains a curable compound that can be cured by heating and a thermosetting agent. The thermosetting agent is preferably a thermal cation curing initiator. The curable compound curable by heating and the thermosetting agent are used in an appropriate blending ratio so that the binder resin is cured. When the binder resin contains a thermal cation curing initiator, an acid is easily contained in the cured product. However, the connection resistance between the electrodes can be kept low by using the conductive particles according to the present invention.

  The conductive material includes, for example, a filler, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent, and the like. Various additives such as a flame retardant may be included.

  The conductive material can be used as a conductive paste and a conductive film. When the conductive material is a conductive film, a film that does not include conductive particles may be laminated on a conductive film that includes conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

  The content of the binder resin in 100% by weight of the conductive material is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, particularly preferably 70% by weight or more, preferably It is 99.99 weight% or less, More preferably, it is 99.9 weight% or less. When the content of the binder resin is not less than the above lower limit and not more than the above upper limit, the conductive particles are efficiently arranged between the electrodes, and the conduction reliability of the connection target member connected by the conductive material is further increased.

  In 100% by weight of the conductive material, the content of the conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 80% by weight or less, more preferably 60% by weight. Hereinafter, it is more preferably 40% by weight or less, particularly preferably 20% by weight or less, and most preferably 10% by weight or less. When the content of the conductive particles is not less than the above lower limit and not more than the above upper limit, the conduction reliability between the electrodes is further enhanced.

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

  The connection structure includes a first connection object member, a second connection object member, and a connection part connecting the first and second connection object members, and the material of the connection part is the above-described material. The conductive material is preferably a conductive material containing the conductive particles and the binder resin described above. It is preferable that the connection portion is a connection structure formed of the conductive particles of the present invention or a conductive material containing the conductive particles and a binder resin. In the case where conductive particles are used, the connection portion itself is conductive particles. That is, the first and second connection target members are connected by the conductive particles.

  FIG. 4 is a front cross-sectional view schematically showing a connection structure using conductive particles according to the first embodiment of the present invention.

  4 includes a first connection target member 52, a second connection target member 53, and a connection portion 54 that connects the first and second connection target members 52 and 53. Prepare. The connection portion 54 is formed by curing a conductive material including the conductive particles 1. In FIG. 4, the conductive particles 1 are schematically shown for convenience of illustration. Instead of the conductive particles 1, conductive particles 11, 21, etc. may be used.

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

The manufacturing method of the connection structure is not particularly limited. As an example of the manufacturing method of the connection structure, the conductive material is disposed between the first connection target member and the second connection target member to obtain a multilayer body, and then the multilayer body is heated. And a method of applying pressure. The pressure of the pressurization is about 1.0 × 10 ^{6 to} 4.9 × 10 ⁸ Pa per total area of the connection portion of the bump electrode. The temperature of the said heating is about 120-220 degreeC.

  In the present invention, the electrodes can be electrically connected at a low pressure. The pressurizing pressure at a low pressure is preferably 100 MPa or less, more preferably 80 MPa or less, per total area of the connection portion of the bump electrode.

  The bump electrode is an electrode protruding from the connection target member. The total area of the connection part of the bump electrode is not limited to the area of the part in contact with the conductive particles, but in plan view (when viewed in the stacking direction of the first connection target member, the connection part, and the second connection target member I) means the total area of the opposing portions of the two electrodes.

  Specific examples of the connection target member include electronic components such as semiconductor chips, capacitors, and diodes, and electronic components such as printed boards, flexible printed boards, glass epoxy boards, and glass boards. The connection target member is preferably an electronic component. The conductive particles are preferably used for electrical connection of electrodes in an electronic component.

  At least one of the first connection target member and the second connection target member is preferably a flexible printed circuit board. At least one of the first connection target member and the second connection target member is preferably a semiconductor chip. It is preferable that the first connection target member and the second connection target member are a flexible printed circuit board and a semiconductor chip. The material of the flexible printed circuit board is preferably polyimide or polyester, and in the case of polyester, it is preferably polyethylene terephthalate (PET). The conductive particles and the conductive material are preferably used for conduction of a flexible printed board.

  Examples of the electrode provided on the connection target member include metal electrodes such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a copper electrode, a silver electrode, a titanium electrode, a molybdenum electrode, and a tungsten electrode. When the connection object member is a flexible printed board, the electrode is preferably a gold electrode, a nickel electrode, a titanium electrode, a tin electrode, or a copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a titanium electrode, a copper electrode, a molybdenum electrode, or a tungsten electrode. In addition, when the said electrode is an aluminum electrode, the electrode formed only with aluminum may be sufficient and the electrode by which the aluminum layer was laminated | stacked on the surface of the metal oxide layer may be sufficient. Examples of the material 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.

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

Example 1
Polystyrene particles having an average particle diameter of 0.85 μm were prepared as seed particles. 3.0 g of the polystyrene particles, 500 g of ion-exchanged water, and 120 g of a 5% by weight aqueous solution of polyvinyl alcohol were mixed and dispersed by ultrasonic waves, and then added to a separable flask and stirred uniformly. Further, as an internal forming material, 49 g of cyclohexyl methacrylate as organic compound A, 1.5 g of 2,2′-azobis (methyl isobutyrate) (“V-601” manufactured by Wako Pure Chemical Industries, Ltd.), and triethanolamine lauryl sulfate 3.0 g and 40 g of ethanol were added to 400 g of ion-exchanged water to prepare an emulsion A. The emulsified liquid A is further added to the separable flask to which the polystyrene particles as seed particles are added, and the mixture is stirred for 4 hours. The seed particles absorb the organic compound A, and the internally formed material is swollen. A suspension containing was obtained. Next, 49 g of divinylbenzene (purity 96 wt%) as an organic compound B, 1.5 g of benzoyl peroxide (“NIPER BW” manufactured by NOF Corporation), and 3.0 g of lauryl sulfate triethanolamine as surface portion forming materials And 40 g of ethanol were added to 400 g of ion-exchanged water to prepare an emulsion B. The emulsion B was further added to the separable flask containing the suspension, and the mixture was stirred for 4 hours to absorb the organic compound B in the seed particles in which the internal forming material was swollen. Thereafter, 360 g of a 5% by weight aqueous solution of polyvinyl alcohol was added, heating was started, and the mixture was reacted at 75 ° C. for 5 hours and then at 85 ° C. for 6 hours to obtain substrate particles A having a particle size of 3 μm.

  After dispersing 10 parts by weight of the above base particle A in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, the base particle A was taken out by filtering the solution. . Subsequently, the base particle A was added to 100 parts by weight of a 1% by weight dimethylamine borane solution to activate the surface of the base particle A. The substrate particles A whose surface was activated were sufficiently washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain a dispersion. Next, 1 g of alumina particle slurry (average particle size 150 nm) was added to the dispersion over 3 minutes to obtain a suspension containing base material particles A to which the core material was adhered.

  Further, a nickel plating solution (pH 8.5) containing 0.35 mol / L of nickel sulfate, 1.38 mol / L of dimethylamine borane and 0.5 mol / L of sodium citrate was prepared.

  While stirring the obtained suspension at 60 ° C., the nickel plating solution was gradually added dropwise to the suspension to perform electroless nickel plating. Thereafter, the suspension is filtered to take out the particles, washed with water, and dried to dispose a nickel-boron conductive layer (thickness 0.15 μm) on the surface of the base particle A, and the surface is a conductive layer. Conductive particles were obtained. Of the total surface area of 100% of the outer surface of the conductive part, the surface area of the portion with protrusions was 70%.

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

(Example 3)
Conductive particles were obtained in the same manner as in Example 1 except that the protrusion was formed by adjusting so that the amount of precipitation was partially changed when forming the conductive portion without using the particle slurry for forming the protrusion.

Example 4
As the internal forming material, the addition amount of cyclohexyl methacrylate of organic compound A was changed from 49 g to 59.2 g, and as the surface forming material, the addition amount of divinylbenzene of organic compound B was changed from 49 g to 39.2 g. Conductive particles were obtained in the same manner as in Example 1 except that the prepared base particle B was used.

(Example 5)
As an internal forming material, the addition amount of cyclohexyl methacrylate of organic compound A was changed from 49 g to 39.2 g, and as a surface portion forming material, the addition amount of divinylbenzene of organic compound B was changed from 49 g to 58.8 g. Conductive particles were obtained in the same manner as in Example 1 except that the prepared base particle C was used.

(Example 6)
As an internal forming material, the addition amount of cyclohexyl methacrylate of organic compound A was changed from 49 g to 34.3 g, and as a surface portion forming material, the addition amount of divinylbenzene of organic compound B was changed from 49 g to 63.7 g. Except having used the produced base material particle D, it carried out similarly to Example 1, and obtained electroconductive particle.

(Example 7)
Conductive particles were obtained in the same manner as in Example 1 except that only the particle diameter was changed from the base particle A and the base particle E having a particle diameter of 2.0 μm was used.

(Example 8)
Conductive particles were obtained in the same manner as in Example 1 except that only the particle diameter was changed from the base particle A and the base particle F having a particle diameter of 4.8 μm was used.

Example 9
Conductive particles were obtained in the same manner as in Example 1 except that only the particle diameter was changed from the base particle A and the base particle G having a particle diameter of 7.0 μm was used.

(Example 10)
Conductive particles were obtained in the same manner as in Example 1 except that the thickness of the conductive part was changed to 0.10 μm.

(Example 11)
Conductive particles were obtained in the same manner as in Example 1 except that the thickness of the conductive part was changed to 0.05 μm.

(Example 12)
Conductive particles were obtained in the same manner as in Example 1 except that the thickness of the conductive part was changed to 0.2 μm.

(Example 13)
Conductive particles were obtained in the same manner as in Example 4 except that the thickness of the conductive part was changed to 0.2 μm.

(Example 14)
Conductive particles were obtained in the same manner as in Example 1 except that the conductive part was changed to a nickel-phosphorus conductive layer (phosphorus content 8 wt%).

(Example 15)
The composition of the nickel plating solution was changed, the thickness of the nickel-boron conductive layer (thickness 0.15 μm) in Example 1 was changed to 0.12 μm, and on the outer surface of the conductive part whose thickness was changed, Conductive particles were obtained in the same manner as in Example 1 except that titanium (III) chloride was used as the reducing agent, a high-purity nickel plating layer (thickness 30 nm) was formed, and a multi-layer conductive portion was formed. It was.

(Example 16)
Conductive particles were obtained in the same manner as in Example 1 except that the surface area of the portion with protrusions was changed to 25% out of 100% of the total surface area of the outer surface of the conductive part.

(Example 17)
To a 1000 mL separable flask equipped with a four-neck separable cover, stirring blade, three-way cock, condenser and temperature probe, 100 mmol of methyl methacrylate and N, N, N-trimethyl-N-2-methacryloyloxyethyl A monomer composition containing 1 mmol of ammonium chloride and 1 mmol of 2,2′-azobis (2-amidinopropane) dihydrochloride was weighed in ion-exchanged water so that the solid content was 5% by weight, and then at 200 rpm. The mixture was stirred and polymerized at 70 ° C. for 24 hours under a nitrogen atmosphere. After completion of the reaction, it was freeze-dried to obtain insulating particles having an ammonium group on the surface, an average particle size of 220 nm, and a CV value of 10%.

  The insulating particles were dispersed in ion exchange water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion of insulating particles.

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

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

(Comparative Example 1)
As the substrate particles H, divinylbenzene copolymer resin particles (“Micropearl SP-203” manufactured by Sekisui Chemical Co., Ltd.) were prepared. Except having changed the base material particle A into the base material particle H, it carried out similarly to Example 1, and obtained electroconductive particle.

(Comparative Example 2)
Polytetramethylene glycol 38 g, diacrylate and divinylbenzene 152 g, benzoyl peroxide 2.6 g, lauryl sulfate triethanolamine 10 g and ethanol 130 g were added to ion-exchanged water 1000 g and stirred to obtain an emulsion. The resulting emulsion was added to the polymer seed particle solution in several batches and stirred for 12 hours. Thereafter, 360 g of a 5% by weight aqueous solution of polyvinyl alcohol was added, heating was started, and the mixture was reacted at 75 ° C. for 5 hours and then at 85 ° C. for 6 hours to obtain substrate particles I having a particle diameter of 3 μm. Except having changed the base material particle A into the base material particle I, it carried out similarly to Example 1, and obtained electroconductive particle.

(Comparative Example 3)
The amount of cyclohexyl methacrylate added to organic compound A as an internal forming material was changed from 49 g to 29.4 g, and the amount of divinylbenzene added to organic compound B as a surface portion forming material was changed from 49 g to 68.6 g. Conductive particles were obtained in the same manner as in Example 1 except that the base particles J produced in this way were used.

(Comparative Example 4)
The amount of cyclohexyl methacrylate added as organic compound A was changed from 49 g to 24.5 g as an internal forming material, and the amount of divinylbenzene added as organic compound B was changed from 49 g to 73.5 g as a surface forming material. Conductive particles were obtained in the same manner as in Example 1 except that the base material particles K produced in this manner were used.

(Comparative Example 5)
Conductive particles were obtained in the same manner as in Example 1 except that the thickness of the conductive part was changed to 0.07 μm.

(Evaluation)
(1) Compression modulus (10% K value, 20% K value, 30% K value and 40% K value) when conductive particles are compressed by 10%, 20%, 30% or 40%
The above-mentioned compression elastic modulus (10% K value, 20% K value, 30% K value and 40% K value) of the obtained conductive particles was measured by the above-described method using a micro compression tester (Fischer Scope manufactured by Fischer). H-100 ").

(2) 40% compression recovery rate of conductive particles Using the above-described method, the 40% compression recovery rate of the obtained conductive particles was measured using a micro compression tester (Fischer Scope H-100 manufactured by Fischer). Measured.

(3) Initial connection resistance The obtained conductive particles are added to “Strectbond XN-5A” manufactured by Mitsui Chemicals so that the content becomes 10% by weight. Produced.

  A polyimide substrate (flexible printed circuit board) having a Ti—Al—Ti multilayer electrode pattern having an L / S of 20 μm / 20 μm on the upper surface was prepared. Further, a semiconductor chip having a gold electrode pattern with L / S of 20 μm / 20 μm on the lower surface was prepared.

  On the polyimide substrate, the anisotropic conductive paste immediately after preparation was applied to a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the semiconductor chip was stacked on the anisotropic conductive paste layer so that the electrodes face each other. Then, while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer becomes 150 ° C., a pressure heating head is placed on the upper surface of the semiconductor chip, and an anisotropy is applied by applying a pressure of 40 MPa per total bump area. The conductive paste layer was cured at 150 ° C. to obtain a connection structure. The connection resistance between the opposing electrodes of the obtained connection structure was measured by the 4-terminal method. The initial connection resistance was determined according to the following criteria.

[Evaluation criteria for initial connection resistance]
○○○: Connection resistance is 2.0Ω or less ○○: Connection resistance is over 2.0Ω, 3.0Ω or less ○: Connection resistance is over 3.0Ω, 5.0Ω or less Δ: Connection resistance is 5.0Ω 10.0Ω or less exceeding X: Connection resistance is 10.0Ω or more

(4) Connection resistance after exposure to high temperature and high humidity (long-term reliability)
The connection structure obtained by the above (3) evaluation of the initial connection resistance was left in a high-temperature and high-humidity tank at 85 ° C. and a humidity of 85% for 100 hours. In the connection structure after being left, the connection resistance between the opposing electrodes of the connection structure was measured by a four-terminal method. Further, the connection resistance after being exposed to high temperature and high humidity was determined according to the following criteria.

[Evaluation criteria for connection resistance after exposure to high temperature and high humidity]
○○○: Less than 125% average connection resistance (after leaving) compared to the average value of connection resistance (before leaving) ○○: Connection resistance (after leaving) compared to the average value of connection resistance (before leaving) Average value of 125% or more and less than 150% ○: Compared to the average value of connection resistance (before leaving), the average value of connection resistance (after leaving) is 150% or more and less than 200% △: Connection resistance (before leaving) Compared to the average value of the connection resistance (after leaving), the average value of the connection resistance (after leaving) is 200% or more and less than 300%.

DESCRIPTION OF SYMBOLS 1 ... Conductive particle 2 ... Base material particle 3 ... Conductive part 11 ... Conductive particle 11a ... Protrusion 12 ... Conductive part 12a ... Protrusion 13 ... Core substance 14 ... Insulating substance 21 ... Conductive particle 21a ... Protrusion 22 ... Conductive part 22a ... projection 22A ... first conductive part 22Aa ... projection 22B ... second conductive part 22Ba ... projection 51 ... connection structure 52 ... first connection target member 52a ... first electrode 53 ... second connection target member 53a ... 2nd electrode 54 ... Connection part

Claims (12)

Comprising substrate particles and a conductive portion disposed on the surface of the substrate particles,
The ratio of the compression elastic modulus at 20% compression to the compression elastic modulus at 40% compression is 1.35 or more,
The ratio of the compressive modulus when compressed by 30% to the compressive modulus when compressed by 40% is 0.85 or more,
Conductive particles having a compression recovery rate of 30% or less at 40% compression. The electroconductive particle of Claim 1 whose compression elastic modulus when compressed 10% is 5000 N / mm < ² > or more.   The electroconductive particle of Claim 1 or 2 whose particle diameter of the said base material particle is 1.0 micrometer or more and 5.0 micrometers or less.   The electroconductive particle of any one of Claims 1-3 whose said base material particle is a resin particle or an organic inorganic hybrid particle.   The electroconductive particle of any one of Claims 1-4 which has several protrusion on the outer surface of the said electroconductive part.   6. The conductive particle according to claim 5, further comprising a plurality of core substances that project the outer surface of the conductive portion so as to form the plurality of protrusions in the conductive portion.   The electroconductive particle of Claim 6 whose Mohs hardness of the said core substance is 5 or more.   The electroconductive particle of any one of Claims 5-7 whose surface area of the part with the said protrusion is 30% or more in 100% of the total surface area of the outer surface of the said electroconductive part.   The electroconductive particle of any one of Claims 1-8 provided with the insulating substance arrange | positioned on the outer surface of the said electroconductive part.   The electroconductive particle of any one of Claims 1-9 used for conduction | electrical_connection of a flexible printed circuit board.   The electroconductive material containing the electroconductive particle of any one of Claims 1-10, and binder resin. A first connection target member;
A second connection target member;
A connecting portion connecting the first connection target member and the second connection target member;
A connection structure in which the material of the connection part is the conductive particle according to any one of claims 1 to 10, or a conductive material containing the conductive particle and a binder resin.

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