JP2010129455A - Conductive particle, anisotropic conductive material, connection structure, and manufacturing method of conductive particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide conductive particles capable of sufficiently removing a binder resin between the conductive particles and an electrode, and reducing connection resistance between the electrodes after connection for example in the case it is dispersed in the binder resin and used to connect between the electrodes. <P>SOLUTION: The conductive particles 1 are provided which are equipped with base material particles 2 and a conductive layer 3 formed on a surface 2a of the base material particles 2, in which the uppermost surface layer of the conductive layer 3 is an alloy layer containing copper and beryllium, the beryllium content in the total 100 wt.% of copper and beryllium contained in the alloy layer is within a range of 0.01 to 4 wt.%, and the copper content in 100 wt.% of the alloy layer is 95 wt.% or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a conductive particle comprising a base particle and a conductive layer formed on the surface of the base particle, for example, a conductive particle that can be used for connection between electrodes, and a different particle using the conductive particle. The present invention relates to an isotropic conductive material, a connection structure, and a method for producing conductive particles.

  Anisotropic conductive materials such as anisotropic conductive pastes, anisotropic conductive inks, anisotropic conductive adhesives, anisotropic conductive films, and anisotropic conductive sheets are widely known. In these anisotropic conductive materials, conductive particles are dispersed in paste, ink, or resin.

  The anisotropic conductive material is used for connection between an IC chip and a flexible printed circuit board, connection between an IC chip and a circuit board having an ITO electrode, or the like. For example, after an anisotropic conductive material is arranged between the electrode of the IC chip and the electrode of the circuit board, these electrodes can be connected by heating and pressurizing.

As an example of the conductive particles used for the anisotropic conductive material, Patent Document 1 listed below discloses a conductive particle including a crosslinked polymer fine particle and a metal layer formed on the surface of the crosslinked polymer fine particle. It is disclosed.
JP 2003-157717 A

  In Patent Document 1, the metal layer is formed of copper or an alloy containing copper. Moreover, the Example has described the electroconductive particle in which the said metal layer was formed with copper.

  However, Patent Document 1 does not describe any metal other than copper contained in the alloy containing copper for forming the metal layer. Furthermore, in the Example, the electroconductive particle in which the said metal layer was formed with the alloy containing copper is not described, but the electroconductive particle in which the said metal layer was formed with copper is only described.

  When the metal layer is substantially formed only of copper, the ductility of the metal layer is relatively high, and the flexibility of the metal layer may be too high.

  By the way, for example, when connecting electrodes using an anisotropic conductive material obtained by dispersing conductive particles in a binder resin, a compressive load is applied to the conductive particles sandwiched between the electrodes. It is done. At this time, the binder resin between the electrodes and the conductive particles is excluded, and the electrodes are electrically connected via the conductive particles.

  When the metal layer is substantially formed only of copper, the binder resin between the conductive particles and the electrode may not be sufficiently removed when the compressive load is applied. Furthermore, the connection resistance between the electrodes may increase after the connection.

  The object of the present invention is, for example, when dispersed in a binder resin and used to connect the electrodes, the binder resin between the conductive particles and the electrodes can be sufficiently eliminated, and the electrodes after the connection It is an object of the present invention to provide conductive particles that can reduce the connection resistance between them, an anisotropic conductive material and a connection structure using the conductive particles, and a method for producing the conductive particles.

  According to the present invention, comprising the base particle and a conductive layer formed on the surface of the base particle, the outermost surface layer of the conductive layer is an alloy layer containing copper and beryllium, and the alloy layer The total content of copper and beryllium in 100% by weight of beryllium is in the range of 0.01 to 4% by weight, and the copper content in 100% by weight of the alloy layer is 95% by weight or more. Conductive particles are provided.

  In another specific aspect of the conductive particle according to the present invention, an antioxidant is attached to the surface of the conductive layer.

  In still another specific aspect of the conductive particle according to the present invention, the antioxidant is a nitrogen-containing compound.

  In another specific aspect of the conductive particles according to the present invention, when the alloy layer is measured by X-ray diffraction, a half width calculated from a peak representing a (111) crystal orientation plane of copper is 0.52 to 0.52. It is within the range of 1.7 °.

  The anisotropic conductive material which concerns on this invention contains the electroconductive particle comprised according to this invention, and binder resin.

  A connection structure according to the present invention includes a first connection target member, a second connection target member, and a connection portion that electrically connects the first and second connection target members, The connecting portion is formed of an electrically conductive particle constituted according to the present invention or an anisotropic conductive material containing the electrically conductive particle and a binder resin.

  According to the present invention, there is also provided a method for producing conductive particles of the present invention, wherein the copper and beryllium are contained as the outermost surface layer of the conductive layer using an electroless copper plating solution containing a beryllium compound. A method for producing conductive particles for forming an alloy layer is provided.

  On the specific situation with the manufacturing method of the electroconductive particle which concerns on this invention, the said electroless copper plating solution contains the said beryllium compound with the density | concentration of 0.1-14 g / L.

  In the conductive particles according to the present invention, the outermost surface layer of the conductive layer is an alloy layer containing copper and beryllium, and the content of beryllium in a total of 100% by weight of copper and beryllium contained in the alloy layer is 0. In the range of 0.01 to 4% by weight and the copper content in the alloy layer 100% by weight is 95% by weight or more, for example, dispersed in a binder resin and used for connection between electrodes In this case, the binder resin between the conductive particles and the electrode can be sufficiently eliminated. Furthermore, the connection resistance between electrodes can be lowered after connection.

  Hereinafter, the present invention will be described in detail.

  In FIG. 1, sectional drawing of the electroconductive particle which concerns on one Embodiment of this invention is shown.

  As shown in FIG. 1, the conductive particle 1 includes a base particle 2 and a conductive layer 3 formed on the surface 2 a of the base particle 2. An antioxidant 4 is attached to the surface 3 a of the conductive layer 3.

  Examples of the substrate particle 2 include resin particles, inorganic particles, organic-inorganic hybrid particles, and metal particles.

  Examples of the resin for forming the resin particles include divinylbenzene resin, styrene resin, acrylic resin, urea resin, imide resin, phenol resin, polyester resin, and vinyl chloride resin. Examples of the inorganic substance for forming the inorganic particles include silica or carbon black. Examples of the organic / inorganic hybrid particles include organic / inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin. Examples of the metal for forming the metal particles include silver, copper, nickel, silicon, gold, and titanium.

  The average particle diameter of the substrate particles 2 is preferably in the range of 1 to 100 μm. When the average particle diameter of the base particle 2 is smaller than 1 μm, the connection reliability between the electrodes may be lowered. When the average particle diameter of the base particle 2 is larger than 100 μm, the distance between the electrodes may be too large.

  The “average particle size” indicates a number average particle size. The average particle diameter can be measured using, for example, a Coulter counter (manufactured by Beckman Coulter).

  The conductive layer 3 of the conductive particles 1 is formed of one layer. The conductive layer may be formed of a plurality of layers. That is, the conductive layer may have a stacked structure of two or more layers.

  The conductive layer 3 is an alloy layer containing copper and beryllium. Since the conductive layer 3 is formed of one layer, the outermost surface layer of the conductive layer is formed of an alloy layer containing copper and beryllium.

  When the conductive layer is formed of one layer, the entire conductive layer 3 is formed of an alloy layer containing copper and beryllium. When the conductive layer is formed of a plurality of layers, the outermost surface layer of the conductive layer, that is, the outermost layer is formed of an alloy layer containing copper and beryllium.

  The beryllium content in a total of 100% by weight of copper and beryllium contained in the alloy layer is in the range of 0.01 to 4% by weight. When the content of beryllium in the total 100% by weight of copper and beryllium contained in the alloy layer is in the range of 0.01 to 4% by weight, the outermost surface layer of the conductive layer is substantially formed only of copper. Compared with the case where it is done, the ductility or the softness | flexibility of outermost surface layer can be made low. For this reason, for example, when the conductive particles are dispersed in the binder resin and used for connection between the electrodes, the binder resin between the conductive particles and the electrodes can be sufficiently eliminated. Furthermore, the connection resistance between electrodes can be lowered after connection. A preferable lower limit of the beryllium content in a total of 100 wt% of copper and beryllium contained in the alloy layer is 0.2 wt%, and a preferable upper limit is 1.6 wt%.

  The content of copper in a total of 100% by weight of copper and beryllium contained in the alloy layer is in the range of 96 to 99.99% by weight. When the content of copper in the total 100% by weight of copper and beryllium contained in the alloy layer is in the range of 96 to 99.99% by weight, the connection resistance between the electrodes can be lowered. A preferable lower limit of the copper content in a total of 100% by weight of copper and beryllium contained in the alloy layer is 98.4% by weight, and a preferable upper limit is 99.8% by weight.

  The copper content in 100% by weight of the alloy layer is 95% by weight or more. When the copper content in 100% by weight of the alloy layer is 95% by weight or more, the connection resistance between the electrodes can be lowered. The copper content in 100% by weight of the alloy layer is preferably 96% by weight or more, and more preferably 98% by weight or more. The alloy layer may contain nonmetallic components such as phosphorus and boron.

  When the alloy layer is measured by X-ray diffraction, the half width calculated from the peak representing the (111) crystal orientation plane of copper is preferably in the range of 0.52 to 1.7 °. In this case, since the alloy layer becomes hard because the copper alloy crystals contained in the alloy layer become fine, the effect of eliminating the binder resin between the conductive particles and the electrode can be further enhanced. . A more preferable lower limit of the half width is 0.56 °, and a more preferable upper limit is 1.3 °.

  The method for measuring the content of beryllium and copper in a total of 100% by weight of copper and beryllium contained in the alloy layer, and the method for measuring the content of copper in 100% by weight of the alloy layer are known various analytical methods. There is no particular limitation. Examples of the measuring method include atomic absorption analysis or atomic spectrum analysis. In the atomic absorption analysis method, a flame atomic absorption photometer, an electric heating furnace atomic absorption photometer, or the like is used. Examples of the atomic spectrum analysis method include plasma emission analysis or plasma ion source mass spectrometry.

  The method for forming the conductive layer 3 on the surface 2a of the substrate particle 2 is not particularly limited. Examples of the method for forming the conductive layer 3 include methods such as electroless plating, electroplating, and sputtering. Especially, it is preferable that the method of forming the conductive layer 3 on the surface 2a of the base particle 2 is a method of forming by electroless plating. Moreover, it is preferable that the method of forming the alloy layer containing copper and beryllium is a method of forming by electroless plating.

  In the method of forming by electroless plating, generally, a catalyzing step and an electroless plating step are performed. Hereinafter, an example of a method for forming a conductive layer containing copper and beryllium on the surface of resin particles by electroless plating will be described.

  In the catalyzing step, a catalyst serving as a starting point for forming a plating layer by electroless plating is formed on the surface of the resin particles.

  As a method of forming the catalyst on the surface of the resin particles, for example, after adding the resin particles to a solution containing palladium chloride and tin chloride, the surface of the resin particles is activated with an acid solution or an alkali solution, Method of depositing palladium on the surface of the particles, adding resin particles to a solution containing palladium sulfate, and then activating the surface of the resin particles with a solution containing a reducing agent to deposit palladium on the surface of the resin particles Methods and the like. As the reducing agent, sodium hypophosphite or dimethylamine borane is used.

  In the electroless plating step, for example, a copper plating bath containing a copper compound such as a copper salt and a reducing agent is used. By immersing the resin particles in the copper plating bath, copper can be deposited on the surface of the resin particles on which the catalyst is formed. As the reducing agent, sodium hypophosphite, dimethylamine borane, formaldehyde, hydrazine or the like is used.

  By containing a beryllium compound such as a beryllium salt in the copper plating bath, an alloy layer containing copper and beryllium can be formed on the surface of the resin particles. In the method of forming by electroless plating, it is preferable to use an electroless copper plating solution containing a beryllium compound.

  As a method of bringing the content of beryllium in the total 100% by weight of copper and beryllium contained in the alloy layer within the above range, for example, when forming a conductive layer by electroless copper plating, in the electroless copper plating solution And a method of adjusting the concentration of the beryllium compound.

  Specific examples of the beryllium compounds include beryllium sulfate, beryllium oxalate, beryllium nitrate, beryllium phosphate, beryllium silicate, beryllium oxide, beryllium acetate, beryllium chloride, or beryllium fluoride. The beryllium compound is preferably a beryllium salt.

  The electroless copper plating solution preferably contains a beryllium compound at a concentration of 0.1 to 14 g / L. In this case, the beryllium content in a total of 100% by weight of copper and beryllium contained in the alloy layer can be easily controlled within the above range.

  The electroless copper plating solution contains a copper compound. Specific examples of the copper compound include copper sulfate, copper chloride, or copper pyrophosphate. The copper compound is preferably a copper salt.

  The electroless copper plating solution preferably contains a copper compound at a concentration of 20 to 60 g / L. In this case, the copper content in the total 100 wt% of copper and beryllium contained in the alloy layer and the copper content in the alloy layer 100 wt% can be easily controlled within the above range.

  The alloy layer may contain a metal other than copper and beryllium. The other metal is not particularly limited. Examples of the other metal include gold, silver, platinum, zinc, iron, lead, tin, nickel, bismuth, aluminum, cobalt, indium, chromium, titanium, antimony, germanium, cadmium, sodium, and palladium.

  When the conductive layer is formed of a plurality of layers, the metal for forming a layer other than the outermost surface layer is not particularly limited. Examples of the metal include gold, silver, copper, platinum, zinc, iron, lead, tin, nickel, bismuth, aluminum, cobalt, indium, chromium, titanium, antimony, germanium, cadmium, palladium, tin-lead alloy, tin -Copper alloy, tin-silver alloy, tin-lead-silver alloy, etc. are mentioned.

  The thickness of the conductive layer 3 is preferably in the range of 5 to 500 nm, and more preferably in the range of 10 to 400 nm. When the thickness of the conductive layer 3 is less than 5 nm, the conductivity of the conductive particles 1 may be insufficient. When the thickness of the conductive layer 3 exceeds 500 nm, the difference in thermal expansion coefficient between the base particle 2 and the conductive layer 3 increases, and the conductive layer 3 may be easily peeled off from the base particle 2 in some cases. When the conductive layer is formed of a plurality of layers, the thickness of the outermost surface layer, that is, the alloy layer containing copper and beryllium, is preferably in the range of 10 to 400 nm.

  The antioxidant 4 is preferably attached to the surface 3 a of the conductive layer 3. The surface 3a of the conductive layer 3 is preferably surface-treated with an antioxidant. The outermost surface layer of the conductive layer 3 is an alloy layer containing copper and beryllium. Since the alloy layer contains copper, it is easily oxidized. When the antioxidant 4 is attached to the surface 3a of the conductive layer 3, the oxidation of the surface 3a of the conductive layer 3 can be suppressed. For this reason, the connection reliability between the electrodes connected through the conductive particles 1 can be enhanced.

  The antioxidant is not particularly limited. Examples of the antioxidant include nitrogen-containing compounds. As the nitrogen-containing compound, benzotriazole compound, imidazole compound, thiazole compound, triazine, 2-mercaptopyrimidine, indole, pyrrole, adenine, thiobarbituric acid, thiouracil, rhodanine, thiozolidinethione, 1-phenyl-2-tetrazoline-5 -Thion, 2-mercaptopyridine, etc. are mentioned. The said antioxidant may be used independently and 2 or more types may be used together.

  As the benzotriazole compound, benzotriazole, 4-methyl-1H-benzotriazole, 4-carboxy-1H-benzotriazole, 5-methyl-1H-benzotriazole, 5,6-dimethyl-1H-benzotriazole, or benzotriazolebutyl Examples include esters. Examples of the imidazole compound include imidazole and benzimidazole. Examples of the thiazole compound include thiazole and benzothiazole.

  The antioxidant 4 is preferably a nitrogen-containing compound, and more preferably a benzotriazole compound. When these preferable antioxidants are used, the oxidation of the surface 3a of the conductive layer 3 can be further suppressed.

  In order to adhere the antioxidant 4 to the surface 3 a of the conductive layer 3, a solution containing the antioxidant 4 may be used.

  The solution containing the antioxidant 4 may contain a chelating agent, a pH adjuster, a surfactant, a silane coupling agent, or a metal powder. A chelating agent, a pH adjuster, a surfactant, a silane coupling agent, or a metal powder may be attached to the surface 3 a of the conductive layer 3.

  The chlorine ion concentration of the antioxidant 4 is preferably 5 ppm or less. In this case, since the eluted chlorine ions are reduced, the corrosion of the electrode can be prevented.

  The method for attaching the antioxidant 4 to the surface 3a of the conductive layer 3 is not particularly limited. As this method, there is a method in which the surface 3 a of the conductive layer 3 is surface-treated with an antioxidant 4 or a solution containing the antioxidant 4. Especially, since the antioxidant 4 can be uniformly attached to the surface 3 a of the conductive layer 3, the conductive particles before the antioxidant 4 is attached are treated with the antioxidant 4 or the solution containing the antioxidant 4. The method of immersing in is preferable. The conductive particles before the antioxidant 4 is attached are immersed in the antioxidant 4 or a solution containing the antioxidant 4, and after the antioxidant 4 is attached to the surface 3a of the conductive layer 3, as necessary. Then, drying may be performed.

(Anisotropic conductive material)
The anisotropic conductive material according to the present invention contains the conductive particles of the present invention and a binder resin.

  The binder resin is not particularly limited. As the binder resin, generally an insulating resin is used. Examples of the binder resin include a vinyl resin, a thermoplastic resin, a curable resin, a thermoplastic block copolymer, or an elastomer. Binder resin may be used independently 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 resin, ethylene-vinyl acetate copolymer, polyamide resin, and the like. 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. The curable resin may be used in combination with a curing agent. 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, or a styrene-isoprene- Examples thereof include a hydrogenated product of a styrene block copolymer. Examples of the elastomer include styrene-butadiene copolymer rubber or acrylonitrile-styrene block copolymer rubber.

  In addition to conductive particles and binder resin, anisotropic conductive materials include, for example, fillers, extenders, softeners, plasticizers, polymerization catalysts, curing catalysts, colorants, antioxidants, thermal stabilizers, and light stabilizers. You may contain various additives, such as an agent, a ultraviolet absorber, a lubricant, an antistatic agent, or a flame retardant.

  The method for dispersing the conductive particles in the binder resin is not particularly limited, and a conventionally known dispersion method can be used. As a method for dispersing the conductive particles in the binder resin, for example, after adding the conductive particles in the binder resin, kneading and dispersing with a planetary mixer or the like, the conductive particles in water or an organic solvent. After uniformly dispersing with a homogenizer, etc., add it into the binder resin, knead and disperse with a planetary mixer, etc., or dilute the binder resin with water or an organic solvent, then add conductive particles And a method of kneading and dispersing with a planetary mixer or the like.

  The anisotropic conductive material of the present invention can be used as an anisotropic conductive paste, anisotropic conductive ink, anisotropic conductive adhesive, anisotropic conductive film, or anisotropic conductive sheet. When the anisotropic conductive material containing the conductive particles of the present invention is used as a film-like adhesive such as an anisotropic conductive film or an anisotropic conductive sheet, the film-like shape containing the conductive particles is used. A film-like adhesive that does not contain conductive particles may be laminated on the adhesive.

(Connection structure)
FIG. 2 is a front sectional view schematically showing a connection structure using conductive particles according to an embodiment of the present invention.

  The connection structure 21 shown in FIG. 2 is a connection that electrically connects the first connection target member 22, the second connection target member 23, and the first and second connection target members 22 and 23. Part 24. The connection part 24 is formed of an anisotropic conductive film containing the conductive particles 1.

  A plurality of electrodes 22 b are provided on the upper surface 22 a of the first connection target member 22. A plurality of electrodes 23 b are provided on the lower surface 23 a of the second connection target member 23. A second connection target member 23 is laminated on the upper surface 22 a of the first connection target member 22 via an anisotropic conductive film containing the conductive particles 1. The electrode 22 b and the electrode 23 b are electrically connected by the conductive particles 1. In FIG. 2, the conductive particles 1 are shown schematically.

  In the connection structure 21, since the conductive particles 1 are used, the conductive particles 1 and the electrodes 22b are applied when a compressive load is applied after the anisotropic conductive film is disposed between the electrodes 22b and 23b. , 23b can be sufficiently eliminated. That is, the binder resin in the portion indicated by A in FIG. 2 can be sufficiently eliminated, and therefore the conductive particles 1 and the electrodes 22b and 23b can be sufficiently brought into contact with each other. For this reason, connection failure between the electrodes 22b and 23b hardly occurs, and connection reliability can be improved.

  Specific examples of the first and second connection target members 22 and 23 include electronic components such as semiconductor chips, capacitors, and diodes, or circuit boards such as printed boards, flexible printed boards, and glass boards.

  The manufacturing method of the connection structure 21 is not specifically limited. As an example of the manufacturing method of the connection structure 21, the anisotropic conductive film is disposed between the first connection target member 22 and the second connection target member 23 to obtain a laminate, The method of heating and pressurizing a laminated body is mentioned.

  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
A mixed liquid containing 800 parts by weight of a 3% by weight aqueous solution of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., GH-20), 70 parts by weight of divinylbenzene, 30 parts by weight of trimethylolpropane trimethacrylate, and 2 parts by weight of benzoyl peroxide. And stirred with a homogenizer to adjust the particle size. Then, it heated up to 80 degreeC under nitrogen stream, stirring, and reacted for 15 hours, and obtained particle | grains.

  The obtained particles were washed with distilled water and methanol and then classified to obtain resin particles having an average particle size of 4.1 μm and a coefficient of variation of 5.0%.

  Etching was performed by dispersing 10 g of the obtained resin particles in a pre-dip solution for powder plating (Okuno Pharmaceutical Co., Ltd.) and stirring at 30 ° C. for 30 minutes. After etching, the resin particles were washed with water, added to 100 mL of a palladium catalyst solution containing 1% by weight of palladium sulfate, and stirred at 30 ° C. for 30 minutes to adsorb palladium ions to the resin particles. Next, the resin particles on which palladium ions were adsorbed were filtered, washed with water, and then added to a 0.5 wt% dimethylamine borane solution (pH 6.0) to obtain resin particles activated with palladium. Distilled water (500 mL) was added to the palladium-activated resin particles, and the suspension was sufficiently dispersed using an ultrasonic processor.

  Also, an electroless copper plating solution containing copper sulfate (pentahydrate) 40 g / L, EDTA 100 g / L, sodium gluconate 50 g / L, beryllium sulfate 3.5 g / L, formaldehyde 25 g / L and a crystal modifier ( pH 10.5) was prepared.

  While stirring the obtained suspension at 50 ° C., the electroless copper plating solution was gradually added to the suspension to perform electroless copper plating. When a conductive layer having a thickness of 0.1 μm was formed on the surface of the resin particles, the addition of the electroless copper plating solution was completed. Then, the electroconductive particle A by which the alloy layer containing copper and beryllium as a conductive layer was formed in the surface of the resin particle was obtained by wash | cleaning with alcohol and vacuum-drying.

  1 g of the obtained conductive particles A were dispersed in 1000 mL of distilled water (specific resistance 18 MΩ), put in an autoclave with a stirrer, stirred and washed for 10 hours at 0.1 MPa and 121 ° C., filtered and dried ( First process). Conductive particles A1g subjected to the first treatment are dispersed in 1000 mL of distilled water (specific resistance 18 MΩ), placed in an autoclave with a stirrer, stirred and washed at 0.1 MPa and 121 ° C. for 10 hours, and filtered. , Dried (second treatment).

  Next, a phosphoric acid aqueous solution (pH 5) containing calcium pyrophosphate 2.5 g / L and 5-methyl-1H-benzotriazole 50 mg / L as an antioxidant was prepared as a solution containing an antioxidant.

  The conductive particles A subjected to the first and second treatments were immersed in the phosphoric acid aqueous solution at 25 ° C. for 0.5 hours. Then, the electroconductive particle which antioxidant adhered to the surface of the electroconductive layer was obtained by vacuum-drying for 8 hours at 50 degreeC.

(Examples 2 to 5)
In the same manner as in Example 1 except that the concentration of beryllium sulfate in the electroless copper plating solution was changed from 3.5 g / L to the concentration shown in Table 1 below, the antioxidant adhered to the surface of the conductive layer. Conductive particles were obtained.

(Comparative Example 1)
Conductive particles having an antioxidant attached to the surface of the conductive layer were obtained in the same manner as in Example 1 except that beryllium sulfate was not added to the electroless copper plating solution.

(Comparative Examples 2 and 3)
In the same manner as in Example 1 except that the concentration of beryllium sulfate in the electroless copper plating solution was changed from 3.5 g / L to the concentration shown in Table 1 below, the antioxidant adhered to the surface of the conductive layer. Conductive particles were obtained.

(Evaluation)
(1) Ratio of copper and beryllium Add 5g of conductive particles with antioxidant on the surface of the conductive layer to a mixture of 5mL of 60% nitric acid and 10mL of 37% hydrochloric acid to completely dissolve the conductive layer. A solution was obtained. Using the obtained solution, the content of each metal contained in the alloy layer was analyzed with an ICP-MS analyzer (manufactured by Hitachi, Ltd.). The contents of copper and beryllium in a total of 100% by weight of copper and beryllium contained in the conductive layer (alloy layer) were calculated. Furthermore, the copper content in 100% by weight of the conductive layer (alloy layer) was calculated.

(2) Half width calculated from a peak representing the (111) crystal orientation plane of copper Using a powder X-ray diffractometer (manufactured by Rigaku Corporation), a scan speed of 4.000 ° / min and a scan step of 0.020 ° Under these conditions, an X-ray diffraction measurement of an alloy layer of conductive particles having an antioxidant attached to the surface of the conductive layer was performed to obtain a powder X-ray diffraction image. The full width at half maximum was determined from the peak representing the (111) crystal orientation plane of copper in the obtained powder X-ray diffraction image.

(3) Connection resistance Two substrates on which copper patterns with L / S of 100 μm / 100 μm were formed were prepared. Moreover, the anisotropic electrically conductive paste containing 10 weight part of electroconductive particles obtained by the Example and the comparative example and 90 weight part of struct bond XN-5A (made by Mitsui Chemicals) as binder resin was prepared.

  After applying the anisotropic conductive paste on the top surface of the substrate so that the conductive particles are in contact with the copper pattern, the other substrate is laminated so that the copper pattern is in contact with the conductive particles while aligning the position of the copper pattern. The laminate was obtained by pressure bonding. Then, the anisotropic conductive paste was hardened by heating a laminated body at 180 degreeC for 1 minute, and the connection structure was obtained.

  The connection resistance between the electrodes of the obtained connection structure was measured by a four-terminal method, and the obtained measurement value was used as the connection resistance.

  The results are shown in Table 1 below.

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

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Conductive particle 2 ... Resin particle 2a ... Surface 3 ... Conductive layer 3a ... Surface 4 ... Antioxidant 21 ... Connection structure 22 ... 1st connection object member 22a ... Upper surface 22b ... Electrode 23 ... 2nd connection object Member 23a ... Lower surface 23b ... Electrode 24 ... Connection part

Claims (8)

Comprising substrate particles and a conductive layer formed on the surface of the substrate particles;
The outermost surface layer of the conductive layer is an alloy layer containing copper and beryllium;
The beryllium content in a total of 100% by weight of copper and beryllium contained in the alloy layer is in the range of 0.01 to 4% by weight, and the copper content in the alloy layer of 100% by weight is 95% by weight. That is the conductive particles.   The conductive particle according to claim 1, wherein an antioxidant is attached to a surface of the conductive layer.   The electroconductive particle of Claim 2 whose said antioxidant is a nitrogen-containing compound.   The half width calculated from the peak representing the (111) crystal orientation plane of copper when the alloy layer is measured by X-ray diffraction is in the range of 0.52 to 1.7 °. Electroconductive particle of any one of these.   An anisotropic conductive material containing the conductive particles according to claim 1 and a binder resin. A first connection target member, a second connection target member, and a connection part that electrically connects the first and second connection target members;
The connection structure in which the said connection part is formed with the anisotropic conductive material containing the electroconductive particle of any one of Claims 1-4, or this electroconductive particle and binder resin. It is the manufacturing method of the electroconductive particle of any one of Claims 1-4,
The manufacturing method of electroconductive particle which forms the alloy layer containing the said copper and beryllium as the outermost surface layer of the said conductive layer using the electroless copper plating solution containing a beryllium compound.   The method for producing conductive particles according to claim 7, wherein the electroless copper plating solution contains the beryllium compound at a concentration of 0.1 to 14 g / L.

Images