KR20080069861A - Au-free electroconductive particles and anisotropic-electroconductive adhesive using the same - Google Patents

Abstract

A gold-free conductive particle is provided to realize excellent cost efficiency and to ensure excellent connection reliability, oxidation stability and electric conductivity even in the absence of a thin gold layer. A gold-free conductive particle(50) comprises: polymer powder(53) having an elastic modulus of at least 1,000 kgf/mm^2(10% strain) and a recovery ratio of 40-80%; a thin metal layer(54) formed on the surface of the polymer and free from gold(Au); and an anti-oxidative layer(52) formed on the surface of the thin metal layer and capable of electric connection by being partially removed at the portion that is in contact with the counter circuit electrode under heating and pressurization.

Description

Conductive particles not containing gold and anisotropic conductive adhesive material having same {Au-FREE ELECTROCONDUCTIVE PARTICLES AND ANISOTROPIC-ELECTROCONDUCTIVE ADHESIVE USING THE SAME}

1 is a schematic diagram showing an anisotropic conductive adhesive material interposed between substrates having opposing circuit electrodes;

2 is a schematic diagram showing a circuit connection structure electrically connected by an anisotropic conductive adhesive material,

3 is a schematic cross-sectional view of the conductive particles according to an embodiment of the present invention,

4 is a graph illustrating a method for measuring a recovery rate of polymer powder.

The present invention relates to conductive particles used for an anisotropic conductive adhesive material and the like and an anisotropic conductive adhesive material having the same.

With the development of technology, recent electronic devices have been rapidly miniaturized and thinned. As a result, the connection between the fine circuits or the connection between the micro components and the fine circuits is greatly increased. Anisotropic conductive adhesive materials are used for the connection of such fine circuits. The anisotropic conductive adhesive material contains an insulating adhesive component and a plurality of conductive particles dispersed in the insulating adhesive component. A method of connecting the microcircuits using the same will be described below.

Referring to FIG. 1, an insulating adhesive component 40 and an insulating adhesive component 40 are formed between circuit electrodes 11 and 21 provided on the lower surface of the plate 10 and the upper surface of the lower plate 20 so as to face each other. An anisotropic conductive adhesive material 30 composed of a plurality of conductive particles 50 dispersed in 40 is interposed. Then, when thermally compressed at a predetermined temperature and pressure, as shown in FIG. 2, the circuit electrodes 11 and 21 to which the conductive particles 50 interposed between the circuit electrodes 11 and 21 are opposed are electrically connected. At the same time, insulation is ensured between adjacent circuits. In addition, as the insulating adhesive component 40 is completely cured, the upper plate 10 and the lower plate 20 are firmly adhered to each other.

In such an anisotropic conductive adhesive material, electroconductive plating is performed on the surface of the polymer powder to form a nickel thin layer, and then conductive particles in which a gold plating layer is formed on the surface of the nickel thin layer through substitution plating are generally used. The gold plating layer formed on the outermost side of the conductive particles exhibits excellent electrical conductivity and prevents oxidation of the thin nickel layer. Moreover, connection reliability of electroconductive particle improves because of ductility peculiar to gold.

However, the electroconductive particle which formed the gold foil layer in this way has a problem that it is very expensive and inferior in economic efficiency. About 80% or more of the cost of the anisotropically conductive adhesive material is occupied by electroconductive particle, and about 90% or more of the cost of electroconductive particle is a material cost of the gold plating layer formed in the outermost part of electroconductive particle.

Therefore, there is an urgent need for conductive particles that can secure excellent connection reliability, oxidation stability, and good electrical conductivity without introducing a thin layer of gold (Au).

The technical problem to be solved by the present invention is to solve the above-mentioned problems, it is very economical not to use gold, it is possible to ensure excellent connection reliability, oxidation stability and good electrical conductivity without introducing a thin layer of gold (Au) It is to provide an electrically conductive particle and an anisotropic conductive adhesive material having the same.

In order to achieve the above technical problem, the conductive particles according to the present invention has a 10% strain modulus of 1,000kgf / mm ² Polymer powder having a recovery rate of 40 to 80% or more; A thin metal layer formed on the surface of the polymer powder and not containing gold (Au); And an anti-oxidation film coated on the surface of the thin metal layer, wherein a portion in contact with the opposing circuit electrode is removed by heating and pressurization to enable electrical connection. The electroconductive particle of this invention uses the polymeric powder which has a predetermined | prescribed high elasticity and a high recovery rate as a core material, and introduces an antioxidant film in the outermost part, and is excellent in connection reliability, oxidation stability, and favorable, without introducing the thin layer of gold (Au). Electrical conductivity can be secured.

In the conductive particles of the present invention, the polymer powder is a styrene monomer, an acrylic monomer, meta-divinylbenzene, para-divinylbenzene, 4,4'-divinylbiphenylene, 1,5-divinylnaphthalene, Cyclohexanedimethanol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, 1,2-ethanediol diacrylate, 1,3 Propanedioldiacrylate, 1,3-butanedioldiacrylate, 1,4-butanedioldiacrylate, 1,5-pentanedioldiacrylate, neopentylglycoldiacrylate, 1,6-hexanedioldiacrylate Late, bisphenol A diacrylate, cyclohexane dimethanol dimethacrylate, bisphenol A dimethacrylate, methacrylated polybutadiene, triethylene glycol dimethacrylate, ethylene glycol dimethacrylate, 1 It is preferable to manufacture using the polymer superposed | polymerized by the 4-, butanediol dimethacrylate, 1, 6- hexanediol dimethacrylate, neopentyl glycol dimethacrylate, urethane acrylate.

Moreover, in the electroconductive particle of this invention, it is preferable to form an antioxidant film with the organic compound etc. of 10,000 g / mol or less of molecular weight containing at least 1 or more of a hydrophobic oil, a phosphoric acid compound, an amine, or a nitrile group.

The above-mentioned conductive particles can be used as an anisotropic conductive adhesive material for dispersing in an insulating adhesive component to connect a fine circuit or the like.

Hereinafter, the present invention will be described in detail. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the configuration shown in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

3 is a schematic cross-sectional view of the conductive particles according to an embodiment of the present invention.

Referring to Figure 3, the core material of the conductive particles 50 of the present invention 10% strain modulus of 1,000kgf / mm ² Above, the polymer powder 53 whose recovery rate is 40 to 80% is used. The 10% strain modulus (K ₁₀ ) and the recovery rate are defined by Equations 1 and 2, respectively.

In Equation 1, F is a load applied at 10% deformation, R is a radius of the powder, and S represents a 10% displacement. 10% strain modulus is 0.263 Measure while applying load at the speed of gf / sec.

L ₁ and L ₂ in Equation 2 are defined as follows. In other words, when the load is increased to a maximum test force of 1 gf by increasing the load at a rate of 0.0268 gf / sec, and then the load is removed to a minimum test force of 0.1 at the same speed, the displacement from the minimum test force to the maximum test force is increased when the load is increased. L _1, and the recovery displacement from the maximum test force to the minimum test force when the load is reduced is L ₂ (see FIG. 4).

As mentioned above, the gold plating layer formed in the outermost part of electroconductive particle improves the connection reliability of electroconductive particle by ductility peculiar to gold. Therefore, in order to secure connection reliability when the gold plating layer is not formed, the polymer powder used as the core material of the conductive particles of the present invention has a 10% strain modulus of 1,000 kgf / mm ^2. The recovery rate is 40 to 80%. 1,000kgf / mm ² The above-mentioned high strain modulus improves the peelability to the electrode of the conductive particle value at the time of connecting the opposing circuit electrode using the anisotropic conductive adhesive material containing electroconductive particle, and raises connection reliability. On the other hand, if the recovery rate is less than 40% or more than 80%, the connection reliability is rather poor. That is, although the electrodes connected to each other by the crimping of electroconductive particle generate | occur | produce between electrodes by removal of a crimping load, when the recovery rate is less than 40%, the space | interval between spreading electrodes cannot be narrowed and a problem arises in connection reliability. In addition, when the recovery rate exceeds 80%, the contact surface between the conductive particles and the electrode may be reduced due to the high recovery rate of the conductive particles as the compressive load is removed, resulting in poor connection.

The polymer powder having 10% strain modulus and recovery rate in the above-mentioned range is styrene monomer, acrylic monomer, meta-divinylbenzene, para-divinylbenzene, 4,4'-divinylbiphenylene, 1,5-di Vinyl naphthalene, cyclohexanedimethanol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, 1,2-ethanediol diacrylate, 1,3-propanedioldiacrylate, 1,3-butanedioldiacrylate, 1,4-butanedioldiacrylate, 1,5-pentanedioldiacrylate, neopentylglycoldiacrylate, 1,6-hexane Diol diacrylate, bisphenol A diacrylate, cyclohexane dimethanol dimethacrylate, bisphenol A dimethacrylate, methacrylated polybutadiene, triethylene glycol dimethacrylate, ethylene glycol dimeth It can be prepared using various polymers polymerized with acrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, urethane acrylate, and the like. The average particle diameter of powder is a range which can be used for electroconductive particle, such as an anisotropically conductive adhesive material, for example, 1-1,000 micrometers.

On the surface of the polymer powder 53, a thin metal layer 54 containing no gold (Au) is formed. The thin metal layer 54 is a metal coated on conductive particles such as an anisotropic conductive adhesive material, and may be formed of a common metal except gold (Au), which is very expensive, for example, nickel, copper, silver, tin, cobalt, and the like. Can be. The thin metal layer 54 is formed of a single metal thin layer 54, such as a nickel plating layer, a copper plating layer, or the like, as shown in FIG. 3, or two or more metal thin layers or more layers, such as a nickel plating layer / copper plating layer. It can also be formed. The thickness of the metal thin layer 54 may be, for example, 60 to 3,000 nm, but is not limited thereto.

Specific examples of the method of forming the nickel thin layer 54 using the electroless plating method on the surface of the polymer powder 53 are as follows, and the method of forming the copper thin layer is similar.

First, the polymer powders are treated with a degreasing agent to clean the surface, and then immersed in a mixed solution of SnCl ₂ , HCl, and water, followed by washing to be sensitized. Subsequently, it is immersed in a mixed solution of PdCl ₂ , HCl and water, and then washed and activated. The activated particles are plated at a temperature of about 50 ^o C by dropping method using a nickel plating solution [NiSO ₄ , KH ₂ PO ₂ , citric acid, plating stabilizer, water].

In the electroconductive particle 50 of this invention, the surface of the metal thin layer 54 is coated with the antioxidant film 52 which removes the part which contacted the opposing circuit electrode by heating and pressurization, and enables electrical connection.

As described above, when the gold plating layer is not formed on the surface of the metal thin layer not containing gold, a phenomenon in which the resistance of the metal thin layer is increased by an oxidation reaction may occur. The conductive particles 50 of the present invention solved this problem by coating the anti-oxidation film 52 on the metal thin layer 54 surface. The anti-oxidation film 52 formed on the surface of the thin metal layer 54 is dispersed in an anisotropic conductive adhesive material, and when the circuit electrodes facing each other by heating and pressing are removed, the portions contacted with the circuit electrodes in the thermal bonding process are removed. Electrical connection of 50 is made possible.

The antioxidant film 52 may be formed of an organic compound having a molecular weight of 10,000 g / mol or less including at least one hydrophobic oil, a phosphoric acid compound, an amine or a nitrile group.

As hydrophobic oils, mineral oils, silicone oils, and the like may be used alone or in combination thereof. Phosphoric acid compounds include phosphoric acid (H ₃ PO ₄ ), zinc phosphate (Zn ₃ (PO ₄ ) ₂ ), and zinc nitrate (Zn ( NO ₃ ) ₂ ) and the like can be used alone or in combination of two or more thereof. As the organic compound having a molecular weight of 10,000 g / mol or less including at least one amine or nitrile group, dodecylamine, dodecyldiamine, pentylamine, octylamine, etc. may be used alone or in combination of two or more thereof. Can be.

When the antioxidant film is formed using the hydrophobic oil, the polymer powder having the metal thin layer is deposited on the hydrophobic oil and stirred for about 10 minutes to form an antioxidant film on the surface, and then prepared by separating.

When forming an anti-oxidation film using an organic compound having a molecular weight of 10,000 g / mol or less containing at least one phosphoric acid compound or an amine or nitrile group, it is dissolved in about 0.5 to 5% by weight of a solvent and the polymer powder having a thin metal layer is deposited. After forming an anti-oxidation film on the surface, the solvent is evaporated after separation to dry it.

The conductive particles of the present invention described above can be used as an anisotropic conductive adhesive material for dispersing in a conventional insulating adhesive component such as a curable epoxy resin to connect a microcircuit or the like. Not only the electroconductive particle of this invention, but the electroconductive particle normally used within the limit which does not impair the objective of this invention can be used for an anisotropic electroconductive adhesive material together. The content of the conductive fine particles in the anisotropic conductive adhesive material is usually about 3 to 30% by weight, preferably 5 to 10% by weight, but is not limited thereto.

Hereinafter, examples will be described in order to describe the present invention in more detail. However, embodiments according to the present invention can be modified in many different forms, the scope of the present invention should not be construed as limited by the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

<Example 1>

Ni plating was performed using polymer powder polymerized using hexanediol-diacrylate having a particle diameter of 4 µm, an elastic modulus of 1500 kgf / mm ² , and a recovery rate of 50%.

First, the surface was cleaned with a degreasing agent, and then immersed in a mixed solution of 10 g of SnCl ₂ , 40 ml of HCl, and 1000 ml of water for 5 minutes, and then sensitized by washing.

Subsequently, it was immersed in ₂ g of PdCl ₂ , 20 ml of HCl, and 1000 ml of water for 5 minutes, and then washed and activated. Then, nickel plating solution [NiSO ₄ 10g, KH ₂ PO ₂ 20g, citric acid 20g, plating stabilizer 5mg, water 1000ml ] Was plated at a temperature of 50 ^° C. by a dropping method in which the plating solution injection rate was adjusted to 5 ml / min.

The average particle diameter of the conductive fine particles after plating was 4.3 µm. Thus, the conductive fine particles were deposited in an aqueous solution of 2% by weight of dodecyldiamine in the conductive fine particles prepared to form an antioxidant film on the surface thereof, and then the solvent was evaporated to prepare conductive particles having a dodecyldiamine film formed thereon. It was.

For the oxidation stability test of the conductive particles thus prepared, after exposure of SO ₃ gas at a temperature of 80 ^° C. for 1 day, 7 wt% conductive particles, 50 wt% epoxy resin, 3 wt% curing agent and 40 wt% Rubber particles of% were added to prepare an anisotropic conductive film.

<Example 2>

An anisotropic conductive film was prepared in the same manner as in Example 1 except that mineral oil was used instead of dodecyldiamine as an antioxidant film forming material. When forming an antioxidant film with mineral oil, conductive fine particles having a thin metal layer were deposited on the mineral oil, stirred for about 10 minutes to form an antioxidant film on the surface thereof, and then prepared by separating.

<Example 3>

Anisotropic conductive films were prepared in the same manner as in Example 1, except that Cu electroless plating was further performed after Ni electroless plating and before the formation of the anti-oxidation coating. Cu electroless plating method is as follows.

First, Ni-plated fine particles were immersed in a mixed solution of 10 g of SnCl ₂ , 40 ml of HCl, and 1000 ml of water for 5 minutes, followed by washing for sensitization. Subsequently, they were immersed in a mixed solution of ₂ g of PdCl ₂ , 20 ml of HCl, and 1000 ml of water for 5 minutes, and then washed and activated. Then, using a copper plating solution [CuSO ₄ 10g, citric acid 20g, plating stabilizer 5mg, water 1000ml] The plating solution injection rate was plated at a temperature of 40 ^° C by the dropping method adjusted to 5ml / min. The diameter of the conductive fine particles after copper plating was about 4.4 mu m.

Comparative Example 1

An anisotropic conductive film was prepared in the same manner as in Example 1 except that the antioxidant film was not formed on the surface of the conductive particles.

Comparative Example 2

Divinylbenzene having a particle diameter of 4 μm, an elastic modulus of 300 kgf / mm ² , and a recovery rate of 10% was used as the polymer powder, and the same method as in Example 1 was performed except that no antioxidant film was formed on the surface of the conductive particles. An anisotropic conductive film was produced.

Comparative Example 3

Anisotropic conductive films were prepared in the same manner as in Example 1, except that divinylbenzene having a particle diameter of 4 μm, an elastic modulus of 300 kgf / mm ² , and a recovery rate of 10% was used as the polymer powder.

The connection test and the insulation resistance were measured by mounting test of the anisotropic conductive films of the manufactured example and the comparative example, and the result is shown in following Table 1.

Connection resistance (I) Connection resistance (II) Example 1 O O Example 2 O O Example 3 O O Comparative Example 1 × × Comparative Example 2 × × Comparative Example 3 × ×

In Table 1, connection resistance (I) refers to the resistance measured immediately after mounting, connection resistance (II) refers to the resistance measured 30 days after mounting, O is the resistance is less than 2W, × It shows the case where resistance is 10W or more.

Referring to the results of Table 1, according to the present invention, a polymer powder having a high 10% strain modulus and a recovery range of a predetermined range is used as a core material, and the conductive particles coated with an antioxidant film on the outermost portion are gold (Au) plating layers. This means that excellent connection reliability, oxidation stability, and good electrical conductivity can be secured without forming a film.

As described above, the conductive particles of the present invention use the polymer powder having a predetermined high elasticity and a high recovery rate as a core material and introduce an anti-oxidation film at the outermost portion, thereby making up about 90% or more of the cost of the conductive particles. Excellent connection reliability, oxidation stability and good electrical conductivity can be ensured without introducing a thin layer of Au).

Claims (11)

10% strain modulus 1,000kgf / mm ² Polymer powder having a recovery rate of 40 to 80% or more; A thin metal layer formed on the surface of the polymer powder and not containing gold (Au); And Electroconductive particle is coated on the surface of the thin metal layer, and provided with an anti-oxidation film to remove the portion in contact with the opposite circuit electrode by heating and pressing to enable electrical connection. The method of claim 1, Conductive particles, characterized in that the average particle size of the polymer powder is 1 to 1,000㎛. The method of claim 1, The polymer powder is a styrene monomer, an acrylic monomer, meta-divinylbenzene, para-divinylbenzene, 4,4'-divinylbiphenylene, 1,5-divinyl naphthalene, cyclohexane dimethanol diacrylate , Diethylene glycol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, 1,2-ethanediol diacrylate, 1,3-propanediol diacrylate, 1 , 3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, bisphenol A diacrylate, Cyclohexanedimethanol dimethacrylate, bisphenol A dimethacrylate, methacrylated polybutadiene, triethylene glycol dimethacrylate, ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate , 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate and urethane acrylate polymerized by polymerizing any one selected from the group consisting of conductive particles, characterized in that made of a mixture of two or more thereof . The method of claim 1, The metal thin layer is conductive particles, characterized in that made of any one metal selected from the group consisting of nickel, copper, silver, tin and cobalt. The method of claim 1, The metal thin layer is conductive particles, characterized in that the metal thin layer selected from the group consisting of a nickel plating layer, a copper plating layer and a nickel plating layer / copper plating layer. The method of claim 1, The thickness of the said metal thin layer is 60-3,000 nm, Electroconductive particle characterized by the above-mentioned. The method of claim 1, The anti-oxidation film is conductive particles, characterized in that formed with any one selected from the group consisting of hydrophobic oils, phosphoric acid compounds and organic compounds having a molecular weight of 10,000 g / mol or less containing at least one or more amine or nitrile groups. The method of claim 7, wherein The hydrophobic oil is conductive particles, characterized in that any one selected from the group consisting of mineral oil, silicone oil and mixtures thereof. The method of claim 7, wherein The phosphoric acid compound may be any one selected from the group consisting of phosphoric acid (H ₃ PO ₄ ), zinc phosphate (Zn ₃ (PO ₄ ) ₂ ) and zinc nitrate (Zn (NO ₃ ) ₂ ) or a mixture of two or more thereof. Electroconductive particle characterized by the above-mentioned. The method of claim 7, wherein An organic compound having a molecular weight of 10,000 g / mol or less including at least one or more amine or nitrile groups is any one selected from the group consisting of dodecylamine, dodecyldiamine, pentylamine, and octylamine, or a mixture of two or more thereof. Electroconductive particle made into. In the anisotropic conductive adhesive material containing an insulating adhesive component and a plurality of conductive particles dispersed in the insulating adhesive component, The said electroconductive particle is the electroconductive particle of any one of Claims 1-10, The anisotropic conductive adhesive material characterized by the above-mentioned.

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