JP2001216841A - Conductive partiulates and conductive connecting fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide soft conductive particulates used as a conductive material for conductive adhesive, anisotropic conductive adhesive and anisotropic conductive sheet that have softness, without damaging the board on which micro devices are mounted and its wiring, and an conductive connecting fabric composed of them. SOLUTION: The conductive particulates are formed an conductive layer on surface of base-material particles, and when the electroconductive corpuscles were deformed 10% at the loading rate of 0.28 mN/sec in a compression test, 10%K value is less than E Mpa expressed by the following formula 1, where in the formula, D denotes particle diameter of the conductive particulates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to conductive fine particles used as a conductive material such as a conductive adhesive for mounting a micro element, an anisotropic conductive adhesive, or an anisotropic conductive sheet. The present invention relates to a conductive connection structure.

[0002]

2. Description of the Related Art In the field of electronic packaging, in order to connect a pair of fine electrodes, a conductive paste is prepared by mixing metal particles such as gold, silver and nickel and a binder resin. The connection between fine electrodes is performed by filling between the electrodes.
However, such metal particles have a non-uniform shape and a specific gravity greater than that of the binder resin, so that it has been difficult to uniformly disperse them in the binder resin.

It is known that conductive fine particles are formed by providing a metal plating layer on the surface of inorganic particles such as glass beads and silica beads having a relatively uniform particle diameter. However, since the conductive fine particles based on the inorganic particles are too hard, they are difficult to compressively deform. Therefore, if an attempt is made to connect the electrodes using such conductive fine particles, the contact area between the conductive fine particles and the electrode surface does not increase, and it is difficult to reduce the contact resistance.

Japanese Patent Application Laid-Open No. 59-2815 discloses that conductive particles are formed by providing a metal plating layer on the surface of particles such as glass beads, silica beads and glass fibers having a relatively uniform particle diameter. It has been disclosed. However, since the conductive fine particles disclosed in the above publication are too hard, they are difficult to compressively deform. Therefore, if an attempt is made to connect the electrodes using the conductive fine particles, the contact area between the conductive fine particles and the electrode surface does not increase, and it is difficult to reduce the contact resistance.

JP-A-62-185749 and JP-A-1-225776 disclose conductive fine particles using organic fine particles such as polyphenylene sulfide particles and phenol resin particles as base particles. However, the conductive fine particles using such synthetic resin particles as the base particles are softer than the above-mentioned glass beads, silica beads, glass fibers, and the like. There is a problem that the material may be damaged and the ITO layer may be cracked. Also, to reduce damage to electronic materials,
There is a demand for a bonding material that can press-bond electrodes at a lower load and lower temperature.

[0006]

SUMMARY OF THE INVENTION In view of the above, the present invention has the flexibility of not damaging a substrate on which a microelement is mounted and its wiring, and has excellent electrical bonding, connection resistance and connection reliability. It is an object of the present invention to provide flexible conductive fine particles used as a conductive material for a conductive adhesive, an anisotropic conductive adhesive, and an anisotropic conductive sheet, and a conductive connection structure using the same.

[0007]

The present invention relates to conductive fine particles comprising a conductive layer formed on the surface of substrate particles, wherein the conductive fine particles are subjected to a load test at a load rate of 0.28 mN / sec in a compression test. Are conductive fine particles whose 10% K value is equal to or less than E MPa represented by the following formula (1) when deformed by 10%. E = 90D ² -1500D + 7000 (MPa) (1) In the formula, D represents the particle diameter (μm) of the conductive fine particles.
In this specification, the compression test is defined as Table 6-5.
The test is performed in accordance with the compression test method described in JP-A-03180. Hereinafter, the present invention will be described in detail.

In the compression test, when the conductive fine particles are deformed by 10% at a load rate of 0.28 mN / sec, the 10% K value of the conductive fine particles of the present invention is expressed by the following formula (1). It is the following. E = 90D ² -1500D + 7000 (MPa) (1) In the formula, D represents the particle diameter (μm) of the conductive fine particles. In the present specification, the 10% K value is a value represented by the following formula (2). 10% K value = (3 / √2) · ^FS -3 / 2 · R ^-1/2 (MPa) (2) In the formula, F is a load value at 20 ° C. and 10% compressive deformation (MPa × mm ² ), S represents compressive deformation (mm), and R represents radius (mm). The smaller the 10% K value,
Easy to deform.

The conductive fine particles are usually used in a compressed state in order to reduce the connection resistance value. At this time, the conductive fine particles may be deformed by low pressure and have a softness that does not damage the upper and lower substrates and the material. When selecting conductive fine particles, the particle strength is an important factor. If the load required to distort the conductive fine particles is too large, the base film or the like may be damaged.

The compression elastic modulus and the breaking load of the conductive fine particles of the present invention can be determined in accordance with the compression test method described in Japanese Patent Publication No. 6-503180. That is, conductive fine particles are scattered on a steel plate having a smooth surface, and placed on a sample table of a micro compression tester (PCT-200, manufactured by Shimadzu Corporation), and one particle is selected by a microscope. Next, at room temperature, the applied load rate was 0.28 mN / sec, the maximum test load was 20 mN, and the diamond diameter was 50 μm.
When the conductive fine particles are compressed on the smooth end face of
The compression modulus (% K value) at the time of% strain and the load when the conductive fine particles are broken are obtained.

In the present invention, the 10% K value is preferably not more than E'MPa represented by the following formula (4). E ′ = 90D ² −1500D + 6700 (MPa) (4)

In particular, when the conductive fine particles of the present invention have a particle diameter of 10 μm, the 10% K value is 700 MPa.
The following is preferred. If the K value at which the compressive deformation rate is 10% exceeds 700 MPa, it is difficult to deform under low pressure, and the upper and lower substrates are damaged. The lower limit of the K value at a deformation rate of 10% is not particularly limited from the viewpoint of damage to the substrate, but it is difficult to obtain conductive fine particles of 49 MPa or less in consideration of the actual base material of the particles.

The conductive fine particles of the present invention have a particle diameter of 10 μm.
In the case of m, the breaking strain is preferably 30% or more when the conductive fine particles are compressed at a load applying speed of 0.28 mN / sec in a compression test. In the present specification, the breaking strain is a value correlated with the amount of deformation of the conductive fine particles at the time when the conductive fine particles are broken by performing a compression test using the above-mentioned micro-compression tester.
It is shown by. Breaking strain (%) = Amount of deformation at break (L) / particle diameter (D) × 100 (3)

The conductive fine particles are often used in a state of being compressed by 30% or more of the particle diameter for vertical conduction. At this time, if the conductive fine particles are broken, the conduction performance between terminals is reduced. The breaking strain of the fine particles is preferably 30% or more.

The conductive fine particles of the present invention preferably have a Cv value of 8 or less. In the present specification, the Cv value is a value represented by the following equation (5). Cv value = (σ / Dn) × 100 (5) In the formula, σ represents the standard deviation of the particle diameter, and Dn represents the number average particle diameter. The standard deviation and the number average particle diameter are values obtained by observing and measuring 300 arbitrary conductive fine particles with an electron microscope. When the Cv value exceeds 8, the dispersion of the particle diameter becomes large, so that when connecting the electrodes via the conductive fine particles, the number of the conductive fine particles not involved in the connection increases, and a leak phenomenon occurs between the electrodes. There is. More preferably, it is 5 or less.

The conductive fine particles of the present invention are not particularly limited as long as they satisfy the above-mentioned mechanical properties. However, from the viewpoint of physical properties and simplicity of production, a conductive layer is formed on the surface of the base particles. Preferably, the base particles are made of an organic polymer.

The monomer constituting the organic polymer is not particularly restricted but includes, for example, polyethylene glycol di (meth) acrylate such as ethylene glycol di (meth) acrylate and polypropylene such as propylene glycol di (meth) acrylate. Glycol di (meth) acrylate, polytetramethylene glycol di (meth)
2,2- such as acrylate, neopentylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 2,2-bis [4- (methacryloxyethoxy) phenyl] propane di (meth) acrylate Bis [4- (methacryloxypolyethoxy) phenyl] propanedi (meth) acrylate, 2,2-hydrogenated bis [4- (acryloxypolyethoxy) phenyl]
Propanedi (meth) acrylate, 2,2-bis [4-
(Acryloxyethoxypolypropoxy) phenyl] propanedi (meth) acrylate; styrene; α-methylstyrene, p-methylstyrene, p-chlorostyrene,
Styrene derivatives such as chloromethylstyrene; vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; unsaturated nitriles such as acrylonitrile; methyl (meth) acrylate, ethyl (meth) acrylate;
Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, ethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, cyclohexyl (meth) (Meth) acrylate derivatives such as acrylates; conjugated dienes such as butadiene and isoprene; divinylbenzene;
1,6-hexanediol di (meth) acrylate, trimethylolpropanetri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolpropanetetra (meth) acrylate, diallyl phthalate and its isomer, triallyl isocyanurate And its derivatives, trimethylolpropane tri (meth) acrylate and its derivatives, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, isooctyl (meth)
Acrylate, isoamyl (meth) acrylate and the like can be mentioned. These monomers may be used alone,
Two or more kinds may be used in combination.

The conductive layer formed on the surface of the base particles is made of a conductive material. The conductive material is not particularly limited, for example, nickel, gold, silver,
Examples include copper, cobalt, tin, indium, ITO, and alloys containing these as main components. These may be used alone or in combination of two or more.

The method for forming a conductive layer on the surface of the conductive fine particles of the present invention is not particularly limited. For example, a method by electroless plating, a method in which a paste obtained by mixing metal fine powder alone or in a binder with a base particle is used. A physical vapor deposition method such as vacuum vapor deposition, ion plating, and ion sputtering.

A method for forming a conductive layer by the above electroless plating method will be described below with reference to the case of gold displacement plating as an example. Gold displacement plating is divided into an etching process, an activation process, a chemical nickel plating process, and a gold displacement plating process. The etching step is a pretreatment step for improving the adhesion of the plating layer to the base particles by forming irregularities on the surface of the base particles, and as an etching solution, for example, an aqueous solution of sodium hydroxide, concentrated hydrochloric acid, Examples thereof include concentrated sulfuric acid and chromic anhydride.

The activation step is a step for forming a catalyst layer on the surface of the etched base particles and activating the catalyst layer. The activation of the catalyst layer promotes the deposition of metallic nickel in a chemical nickel plating step described below. By dispersing the base particles in the catalyst solution, the catalyst layer containing Pd ²⁺ and Sn ²⁺ on the surface of the base particles is treated with concentrated sulfuric acid or concentrated hydrochloric acid, and Pd ²⁺ is metallized to the surface of the base particles. Precipitates. The metallized palladium is activated and sensitized by a palladium activator such as a concentrated solution of sodium hydroxide.

The chemical nickel plating step is a step in which a metal nickel layer is further formed on the surface of the base particles on which the catalyst layer has been formed. For example, nickel chloride is reduced with sodium hypophosphite and nickel is reduced. Precipitates on the surface of the substrate particles.

In the gold displacement plating step, the base particles coated with nickel as described above are placed in a potassium gold cyanide solution, and while the temperature is raised, nickel is eluted to deposit gold on the surface of the base particles.

The thickness of the conductive layer (when the conductive layer is composed of a plurality of layers, the combined thickness) is 0.02 to 5 μm.
It is preferred that When the thickness of the conductive layer is less than 0.02 μm, desired conductivity is hardly obtained. When the thickness exceeds 5 μm, aggregation of the conductive fine particles easily occurs at the time of production, and the conductive fine particles are sandwiched between the opposing electrodes. Therefore, when both electrodes are pressurized, the flexibility of the conductive fine particles is hardly effectively exhibited.

The base particles have an average particle diameter of 1 to 20 μm.
m is preferable. When the average particle diameter is less than 1 μm, the particle diameter of the obtained conductive fine particles is too small, and when connecting between the electrodes, good connection is not easily obtained and poor conduction is likely to occur. When the particle diameter of the obtained conductive fine particles is too large, when a leak occurs between adjacent electrodes or when the conductive fine particles are mixed with a binder, the problem is liable to settle, and it is difficult to form a uniform conductive adhesive.

The conductive fine particles of the present invention have a recovery rate of 30%
It is preferable that it is above. In the present specification, the recovery rate refers to a micro-compression tester (manufactured by Shimadzu Corporation) similar to that used for measuring the above-mentioned compression modulus (10% K value) and the like.
PCT-200) and a load speed of 0.28 mN /
sec, the restoration rate when the obtained conductive fine particles were compressed on the smooth end face of a diamond-made cylinder having a diameter of 50 μm under the conditions of an origin load value of 1.0 mN and a reversal load value of 10 mN. When the recovery rate is less than 30%, when the base particles are polymer fine particles, the obtained conductive fine particles may be deformed or the like, resulting in poor connection. It is more preferably at most 40%.

The conductive fine particles of the present invention provide a film substrate on which a micro element is mounted by controlling a load value required for deforming the conductive fine particles to reduce the connection resistance value to a certain value or less. It has flexibility not to damage wiring, and has excellent electrical connection, connection resistance and connection reliability.

The conductive fine particles of the present invention are used as a conductive material such as a conductive adhesive for mounting microelements, an anisotropic conductive adhesive, and an anisotropic conductive sheet, and are used for bonding substrates or parts.

The method of joining the above-mentioned substrate or component is not particularly limited as long as it is a method of joining using conductive fine particles, and examples thereof include the following methods. (1) A method in which an anisotropic conductive sheet is placed on a substrate or component having an electrode formed on its surface, and then a substrate or component having the other electrode surface is placed and heated and pressed for joining. (2) A method in which anisotropic conductive adhesive is supplied and joined by means such as screen printing or a dispenser instead of using an anisotropic conductive sheet. (3) A method in which a liquid binder is supplied to a gap between two electrode portions bonded together via conductive fine particles, followed by curing and bonding.

As described above, a joined body of substrates or parts,
That is, a conductive connection structure can be obtained. A conductive connection structure using the conductive fine particles of the present invention is also one of the present invention.

[0031]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Examples 1 to 8 and Comparative Examples 1 to 4 Example 1 In a separable flask reactor, 10 parts by weight of polytetramethylene glycol diacrylate, 10 parts by weight of isooctyl acrylate, and a polymerization initiator were used. 1.3 parts by weight of benzoyl oxide was added and mixed uniformly. Next, 20 parts by weight of a 3% aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd.) and 0.5 part by weight of sodium dodecyl sulfate were added, and after stirring well, 140 parts by weight of ion-exchanged water was added. The resulting solution was reacted at 80 ° C. for 15 hours under a nitrogen stream while stirring. After the obtained fine particles were washed with hot water and acetone, a classification operation was performed, and the average particle diameter was 10 μm.
Was obtained. Perform plating on the substrate particles,
Conductive fine particles of nickel layer 850% and gold layer 400% were obtained. The particle diameters of arbitrary 400 particles of the obtained conductive fine particles were measured with an electron microscope, and the average particle diameter and the particle diameter distribution were determined. The obtained values are shown in Table 1.

(Example 2) Polymerization was carried out in the same composition as in Example 1, and base particles having an average particle diameter of 5 µm were obtained by a classification operation. The base particles were subjected to plating to obtain conductive fine particles of a nickel layer 680% and a gold layer 400%. The particle diameters of arbitrary 400 particles of the obtained conductive fine particles were measured with an electron microscope, and the average particle diameter and the particle diameter distribution were determined. The obtained values are shown in Table 1.

Example 3 Polymerization was carried out in the same composition as in Example 1, and base particles having an average particle diameter of 3 μm were obtained by a classification operation. The base particles were plated to obtain conductive fine particles of a nickel layer 770% and a gold layer 300%. The particle diameters of arbitrary 400 particles of the obtained conductive fine particles were measured with an electron microscope, and the average particle diameter and the particle diameter distribution were determined. The obtained values are shown in Table 1.

Example 4 [Synthesis of Seed Particles] 18 parts by weight of polyvinylpyrrolidone (weight average molecular weight 30,000, manufactured by Wako Pure Chemical Industries, Ltd .: K-30), 2.9 parts by weight of Aerosol OT (manufactured by Wako Pure Chemical Industries, Ltd.) And 20 parts by weight of azobismethylvaleronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) are dissolved in a mixture of 350 parts by weight of methanol and 50 parts by weight of water.
0 parts by weight and 10 parts by weight of α-methylstyrene were added. Thereafter, the temperature was raised to 60 ° C. and polymerization was performed for 24 hours to obtain seed particles. The average particle size of the seed particles was 2.5 μm.

[Synthesis of Base Particles] To 4 parts by weight of the above seed particles, 200 parts by weight of ion-exchanged water and 0.2 parts by weight of sodium lauryl sulfate were added and uniformly dispersed, and then polytetramethylene glycol diacrylate 110 was added. Parts by weight, 110 parts by weight of isooctyl acrylate and 12 parts by weight of benzoyl peroxide were mixed and dispersed with a homogenizer to finely disperse and emulsify. The obtained emulsion was added to the dispersion of the seed particles, and the mixture was stirred at 25 ° C. and a rotation speed of 100 rpm for 12 hours to be absorbed by the seed particles. After 200 parts by weight of a 5% by weight aqueous solution of polyvinyl alcohol was added to this dispersion, polymerization was carried out at 80 ° C. for 12 hours under a nitrogen stream. Fine particles were taken out from the obtained dispersion by centrifugation, and the dispersant was completely washed with hot water and acetone and then dried to obtain base particles. The obtained base particles had an average particle size of 10 μm.
The base particles are subjected to a plating treatment to form a nickel layer 850.
{, Conductive fine particles of gold layer 400} were obtained. The particle diameters of arbitrary 400 particles of the obtained conductive fine particles were measured with an electron microscope, and the average particle diameter and the particle diameter distribution were determined. The obtained values are shown in Table 1.

Example 5 A polytetramethylene glycol diacrylate 20 was placed in a separable flask reactor.
Parts by weight and 1.3 parts by weight of benzoyl peroxide as a polymerization initiator were added and uniformly mixed. Next, 20 parts by weight of a 3% aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd.) and 0.5 part by weight of sodium dodecyl sulfate were added, and after stirring well, 140 parts by weight of ion-exchanged water was added. The resulting solution was reacted at 80 ° C. for 15 hours under a nitrogen stream while stirring. After the obtained fine particles were washed with hot water and acetone, classification operation was performed to obtain base particles having an average particle diameter of 10 μm. The base particles were subjected to plating to obtain conductive fine particles of a nickel layer 850% and a gold layer 400%. The particle diameters of arbitrary 400 particles of the obtained conductive fine particles were measured with an electron microscope, and the average particle diameter and the particle diameter distribution were determined. The obtained values are shown in Table 1.

Example 6 Polymerization was carried out in the same composition as in Example 5, and base particles having an average particle diameter of 5 μm were obtained by a classification operation. The base particles were subjected to plating to obtain conductive fine particles of a nickel layer 680% and a gold layer 400%. The particle diameters of arbitrary 400 particles of the obtained conductive fine particles were measured with an electron microscope, and the average particle diameter and the particle diameter distribution were determined. The obtained values are shown in Table 1.

(Example 7) NK ester APG700 (manufactured by Shin-Nakamura Chemical Co., Ltd.) was placed in a separable flask reactor.
10 parts by weight, 10 parts by weight of isooctyl acrylate, and 1.3 parts by weight of benzoyl peroxide as a polymerization initiator were uniformly mixed. Next, 20 parts by weight of a 3% aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd.) and 0.5 parts by weight of sodium dodecyl sulfate were added and stirred well.
0 parts by weight were added. The resulting solution was reacted at 80 ° C. for 15 hours under a nitrogen stream while stirring. After the obtained fine particles were washed with hot water and acetone, classification operation was performed to obtain particles having an average particle diameter of 10 μm. The particles were plated to obtain conductive fine particles of a nickel layer 850% and a gold layer 400%. The particle diameters of arbitrary 400 particles of the obtained conductive fine particles were measured with an electron microscope, and the average particle diameter and the particle diameter distribution were determined. The obtained values are shown in Table 1.

Example 8 In a separable flask reactor, 20 parts by weight of isooctyl acrylate and 1.3 parts by weight of benzoyl peroxide as a polymerization initiator were charged and uniformly mixed. Next, polyvinyl alcohol (Kuraray Co., Ltd.)
% Aqueous solution and 0.5 parts by weight of sodium dodecyl sulfate were added and stirred well, and then 140 parts by weight of ion exchanged water was added. While stirring the obtained solution under a nitrogen stream,
The reaction was performed at 80 ° C. for 15 hours. After the obtained fine particles were washed with hot water and acetone, a classification operation was performed to obtain base particles having an average particle diameter of 5 μm. The base particles were subjected to plating to obtain conductive fine particles of a nickel layer 680% and a gold layer 400%. The particle diameters of arbitrary 400 particles of the obtained conductive fine particles were measured with an electron microscope, and the average particle diameter and the particle diameter distribution were determined. The obtained values are shown in Table 1.

Comparative Example 1 In a separable flask reactor, 20 parts by weight of divinylbenzene and 1.3 parts by weight of benzoyl peroxide as a polymerization initiator were uniformly mixed. Next, 20 parts by weight of a 3% aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd.) and 0.5 part by weight of sodium dodecyl sulfate were added, and after stirring well, 140 parts by weight of ion-exchanged water was added. The resulting solution was reacted at 80 ° C. for 15 hours under a nitrogen stream while stirring. After the obtained fine particles were washed with hot water and acetone, a classification operation was performed to obtain base particles having an average particle diameter of 5 μm. The base particles were subjected to plating to obtain conductive fine particles of a nickel layer 850% and a gold layer 400%. The particle diameters of arbitrary 400 particles of the obtained conductive fine particles were measured with an electron microscope, and the average particle diameter and the particle diameter distribution were determined. The obtained values are shown in Table 1.

Comparative Example 2 Polytetramethylene glycol diacrylate 16 was placed in a separable flask reactor.
Parts by weight, 4 parts by weight of divinylbenzene, and 1.3 parts by weight of benzoyl peroxide as a polymerization initiator were uniformly mixed.
Next, 20 parts by weight of a 3% aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd.) and 0.5 part by weight of sodium dodecyl sulfate were added, and after stirring well, 140 parts by weight of ion-exchanged water was added. 80 ° C. under a nitrogen stream while stirring the obtained solution.
For 15 hours. After the obtained fine particles were washed with hot water and acetone, a classification operation was performed, and the average particle diameter was 10 μm.
m of base particles were obtained. The base particles were subjected to plating to obtain conductive fine particles of a nickel layer 850% and a gold layer 400%. The particle diameters of arbitrary 400 particles of the obtained conductive fine particles were measured with an electron microscope, and the average particle diameter and the particle diameter distribution were determined. The obtained values are shown in Table 1.

(Comparative Example 3) Polymerization was carried out in the same composition as in Comparative Example 2, and base particles having an average particle diameter of 5 µm were obtained by a classification operation. The base particles were subjected to plating to obtain conductive fine particles of a nickel layer 680% and a gold layer 400%. The particle diameters of arbitrary 400 particles of the obtained conductive fine particles were measured with an electron microscope, and the average particle diameter and the particle diameter distribution were determined. The obtained values are shown in Table 1.

Comparative Example 4 In a separable flask reactor, 16 parts by weight of methyl methacrylate, 4 parts by weight of ethylene glycol dimethacrylate, and 1.3 parts by weight of benzoyl peroxide as a polymerization initiator were uniformly mixed. Next, 20 parts by weight of a 3% aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd.) and 0.5 part by weight of sodium dodecyl sulfate were added, and after stirring well, 140 parts by weight of ion-exchanged water was added. The resulting solution was reacted at 80 ° C. for 15 hours under a nitrogen stream while stirring. After the obtained fine particles were washed with hot water and acetone, a classification operation was performed, and the average particle diameter was 10 μm.
Was obtained. Perform plating on the substrate particles,
Conductive fine particles of nickel layer 850% and gold layer 400% were obtained. The particle diameters of arbitrary 400 particles of the obtained conductive fine particles were measured with an electron microscope, and the average particle diameter and the particle diameter distribution were determined. The obtained values are shown in Table 1.

[Evaluation] The conductive fine particles obtained in Examples 1 to 8 and Comparative Examples 1 to 4 were evaluated as follows. (Micro compression test) The mechanical strength of the conductive fine particles was measured using a micro compression tester (PCT-200, manufactured by Shimadzu Corporation), and the obtained conductive fine particles were subjected to a load applying speed of 0.28 mN.
/ Sec, the maximum test load was 20 mN, and the 10% K value was measured.

(Evaluation of recovery rate) Using a micro-compression tester (PCT-200, manufactured by Shimadzu Corporation), a load application speed of 0.2
8 mN / sec, origin load value 1.0 mN, reversal load value 1
Under a condition of 0 mN, the obtained conductive fine particles were compressed on a smooth end face of a diamond-made cylinder having a diameter of 50 μm to determine a recovery rate.

(Observation of pressed state) The obtained conductive fine particles were mixed and dispersed in a binder solution obtained by dissolving a mixture of an epoxy resin and an acrylic resin in toluene. After the obtained dispersion was applied onto a release film, toluene was evaporated to produce an anisotropic conductive film having a thickness of 30 μm. The obtained anisotropic conductive film and a 100-μm-thick polycarbonate film substrate were superimposed on a 1.5-mm-thick glass plate, and heated and pressed at 150 ° C. for 2 minutes to produce a conductive joined body. The state of the conductive fine particles in the obtained conductive joined body was observed with an optical microscope. The results are shown in Table 1. Table 2 shows E values and E 'values corresponding to the respective particle diameters.

[0048]

[Table 1]

[0049]

[Table 2]

[Examples 9 to 13 and Comparative Examples 5 to 6] (Example 9) 20 parts by weight of polytetramethylene glycol diacrylate and 1.3 parts by weight of benzoyl peroxide were charged into a separable flask reactor and homogenized. Was dissolved. Next, 20 parts by weight of a 3% aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd.) and 0.5 part by weight of sodium dodecyl sulfate were charged and stirred well, and then 140 parts by weight of ion-exchanged water were added. After stirring for 1 to 2 hours, the particle diameter of the monomer droplet is 5 to 5.
After adjusting to about 15 μm, under a nitrogen stream,
The reaction was carried out at 80 ° C. for 15 hours to obtain polymer fine particles. After the obtained fine particles were washed with hot water and acetone, classification operation was performed to obtain particles having an average particle diameter of 10 μm. The particles were subjected to plating to obtain conductive fine particles of a nickel layer 880% and a gold layer 400%.

Example 10 Example 10 was repeated except that 10 parts by weight of polytetramethylene glycol diacrylate and 10 parts by weight of isooctyl acrylate were used instead of 20 parts by weight of polytetramethylene glycol diacrylate. Performed similarly to 9. The average particle diameter of the base particles was 10 μm, and conductive fine particles of a nickel layer 820 # and a gold layer 440 # were obtained.

(Example 11) In Example 10, 10 parts by weight of polytetramethylene glycol diacrylate was used.
Example 10 was repeated except that 6 parts by weight of polytetramethylene glycol diacrylate and 14 parts by weight of isooctyl acrylate were used instead of 10 parts by weight of isooctyl acrylate. The average particle diameter of the base particles is 10 μm, and the nickel layer 830 #, the gold layer 410
導電 of conductive fine particles were obtained.

(Example 12) In Example 9, instead of 20 parts by weight of polytetramethylene glycol diacrylate, 10 parts by weight of polypropylene glycol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd .: NK ester APG700), 10 parts by weight of isooctyl acrylate Example 9 was repeated except that parts by weight were used. The average particle diameter of the base particles is 10 μm, and the nickel layer 840 # and the gold layer 400 #
Was obtained.

(Example 13) [Synthesis of seed particles] 18 parts by weight of polyvinylpyrrolidone (weight average molecular weight 30,000, manufactured by Wako Pure Chemical Industries, Ltd .: K-30), 2.9 parts by weight of aerosol OT (manufactured by Wako Pure Chemical Industries, Ltd.) Part, and 2,2-
After dissolving 20 parts by weight of azobis-2,4-dimethylvaleronitrile (V-65, manufactured by Wako Pure Chemical Industries, Ltd.) in a mixed solution of 350 parts by weight of methanol and 50 parts by weight of water, the mixture was stirred under a nitrogen stream. 90 parts by weight of styrene and 10 parts by weight of α-methylstyrene were charged. The temperature was raised to 60 ° C. and polymerization was performed for 24 hours to obtain seed particles. The average particle size of the seed particles is 2.
It was 5 μm.

[Synthesis of Base Particles] Polytetramethylene glycol diacrylate (110 parts by weight), isoamyl acrylate (110 parts by weight), benzoyl peroxide (12 parts by weight) and ion-exchanged water (2,000 parts by weight) were mixed, finely dispersed by a homogenizer, and singly mixed. A monomer emulsion was obtained. 4 parts by weight of the seed particles obtained above, 200 parts by weight of ion-exchanged water, and 0.2 parts by weight of sodium lauryl sulfate were put into a separable flask reactor equipped with a cooling tube, a stirring blade, and a nitrogen inlet tube, and seed particles were dispersed. A liquid was prepared. Subsequently, the monomer emulsion was added to the seed particle dispersion, and the mixture was stirred at 25 ° C. and 100 rpm for 24 hours to allow the seed particles to absorb the monomer. After 200 parts by weight of a 5% by weight aqueous solution of polyvinyl alcohol was added to this dispersion, polymerization was carried out at 80 ° C. for 12 hours under a nitrogen stream. After the completion of the polymerization, the fine particles were separated by centrifugation, the dispersant was completely washed with hot water and acetone, and then dried to obtain polymer fine particles (base particles). The average particle diameter of the obtained base particles was 10 μm. Perform plating on the substrate particles,
Conductive fine particles of nickel layer 850% and gold layer 400% were obtained.

Comparative Example 5 The procedure of Example 9 was repeated, except that 20 parts by weight of divinylbenzene was used instead of 20 parts by weight of polytetramethylene glycol diacrylate. The average particle size of the base particles is 10μ
m, and conductive fine particles of a nickel layer 850 ° and a gold layer 420 ° were obtained.

Comparative Example 6 In Example 9, polytetramethylene glycol diacrylate 1 was replaced with 20 parts by weight of polytetramethylene glycol diacrylate.
Example 9 was repeated except that 6 parts by weight and 4 parts by weight of divinylbenzene were used. The average particle size of the base particles is 1
Conductive fine particles of 0 μm, a nickel layer 830 #, and a gold layer 410 # were obtained.

[Evaluation] The above Examples 9 to 13 and Comparative Example 5
The following evaluation was performed on the conductive fine particles obtained in Nos. 6 to 6. The results are shown in Table 3. (Micro compression test) The 10% K value and the breaking strain were determined in the same manner as in Example 1. (Observation of crimping state) The same procedure as in Example 1 was performed.

[0059]

[Table 3]

[0060]

Since the present invention has the above-described structure, even if the substrate is a flexible substrate such as plastic, it has excellent flexibility without damaging the substrate on which the micro-element is mounted and its wiring. The present invention provides conductive fine particles that can be used as a conductive adhesive, anisotropic conductive adhesive, or a conductive material of an anisotropic conductive sheet having electrical bonding and connection reliability, and a conductive connection structure using the same. it can.

Claims (9)

[Claims] 1. A conductive fine particle comprising a base particle and a conductive layer formed on the surface thereof, wherein the conductive fine particle has a load of 0.28 mN / sec in a compression test.
Conductive fine particles having a 10% K value of not more than E MPa represented by the following formula (1) when deformed by 0%. E = 90D ² -1500D + 7000 (MPa) (1) In the formula, D represents the particle diameter (μm) of the conductive fine particles. 2. The conductive fine particles according to claim 1, wherein the 10% K value is equal to or less than E ′ MPa represented by the following formula (4). E ′ = 90D ² −1500D + 6700 (MPa) (4) 3. The particle size is 10 μm and 10%
3. The conductive fine particles according to claim 1, wherein the K value is 700 MPa or less. 4. In a compression test, a load application speed of 0.2
The conductive fine particles according to claim 3, wherein when the conductive fine particles are compressed at 8 mN / sec, the breaking strain is 30% or more. 5. The conductive fine particles according to claim 1, wherein the Cv value is 8 or less. 6. The conductive fine particles according to claim 1, wherein the base particles are made of an organic polymer. 7. The base particles have an average particle diameter of 1 to 20 μm.
The conductive fine particles according to claim 1, 2, 3, 4, 5, or 6, wherein 8. The conductive fine particles according to claim 1, wherein the recovery rate is 30% or more. 9. A conductive connection structure comprising the conductive fine particles according to claim 1, 2, 3, 4, 5, 6, 7, or 8.