TW201927970A - Conductive adhesive composition and isotropic conductive film formed therefrom capable of exhibiting uniform electrical conductivity - Google Patents

Abstract

The present invention relates to a conductive adhesive composition and, more particularly, to a conductive adhesive composition which is excellent in adhesion to a surface to be adhered, good in heat resistance and flexibility, excellent in electrical conductivity, and capable of uniformly dispersing a filler, thereby exhibiting uniform electrical conductivity, and an isotropic conductive film formed therefrom. Furthermore, the conductive adhesive composition is characterized by comprising: a main resin including a first polyurethane resin and a second polyurethane resin with a glass transition temperature different from that of the first polyurethane resin; and a conductive filler, wherein the glass transition temperature of the first polyurethane resin is 30 DEG C to 60 DEG C, and the glass transition temperature of the second polyurethane resin is -5 DEG C to 20 DEG C.

Description

Conductive adhesive composition and isotropic conductive film formed therefrom

The present invention relates to a conductive adhesive composition. More specifically, it has excellent adhesion to the surface to be adhered, good heat resistance and flexibility, excellent electrical conductivity, and can evenly disperse fillers, so that it can exhibit uniform electrical conductivity. Adhesive composition and isotropic conductive film formed from the same.

In recent years, the miniaturization and high functionality of electronic devices have accelerated the miniaturization of component connection terminals. Therefore, in the field of electronic packaging, various thin film adhesives that can easily connect these terminals are used in IC chips and flexible The tendency of adhesion of printed wiring boards (FPC), IC chips, and glass substrates formed with indium tin oxide (ITO) electrode circuits.

In particular, flexible printed circuit boards (FPCBs) have recently been used in various fields. Flexible printed circuit boards are electronic components developed with miniaturization and weight reduction of electronic products. They have excellent processability, heat resistance, bending resistance, and chemical resistance, and are flexible printed circuits with high heat resistance. The board is suitable for use. Specifically, as the core component of all electronic products, the above flexible printed circuit boards are widely used in cameras, computers and peripherals, mobile phones, video and audio equipment, video cameras, printers, DVDs, TFT LCD monitors, satellite equipment, military equipment , Medical equipment, etc. The flexible printed circuit board can be individually three-dimensionally wired, and the device can be miniaturized and lightened. In addition, the flexible printed circuit board has high durability against repeated bending, can realize high-density wiring, has no wiring errors, is well assembled, and has high reliability. Moreover, the flexible printed circuit board has the advantage that it can be manufactured in a continuous production manner.

In the case of a flexible printed circuit board, a conductive adhesive sheet for electrically connecting a circuit board body such as a flexible printed wiring board (FPC) and the like, and a circuit element such as a reinforcing board, and a circuit board body and a circuit are required. Conductive adhesive for circuit boards that are electrically connected to each other.

The main characteristics required for such an adhesive are as follows: it can be cured at a relatively low temperature in a short period of time, so as not to cause thermal damage to the circuit substrate, and to provide an electrical connection between the substrates.

On the other hand, the conventional conductive adhesive has a problem in that it cannot exhibit excellent effects such as adhesion to the surface to be adhered and holding power, heat resistance, flexibility, electrical conductivity, and filler dispersibility.

For this reason, it is urgent to research and develop a conductive adhesive that has excellent adhesion to the adhered surface, good heat resistance and flexibility, excellent electrical conductivity, and can uniformly disperse fillers, so that it can exhibit uniform electrical conductivity. Adhesive.

Prior art literature

Patent literature

(Patent Document 1) KR 10-2005-0051089 A

The present invention was developed in order to solve the above-mentioned problems, and the object thereof is to provide an excellent adhesive force to the adhered surface, good heat resistance and flexibility, excellent electrical conductivity, and uniform dispersion of the filler, so that it can exhibit uniform electrical conductivity. A conductive adhesive composition and an isotropic conductive film formed from the same.

In order to achieve the above object, the present invention provides a conductive adhesive composition, comprising: a main resin, including a first polyurethane-based resin and a second polyurethane-based resin having different glass transition temperatures; and a conductive filler.

According to an embodiment of the present invention, the glass transition temperature of the first polyurethane-based resin may be 30 ° C to 60 ° C, and the glass transition temperature of the second polyurethane-based resin may be -5 ° C to 20 ° C.

In addition, the main resin may include the first polyurethane-based resin and the second polyurethane-based resin in a weight ratio of 1: 0.2 to 0.6.

In addition, the acid value of the first polyurethane-based resin may be 15 to 27 mgKOH / g, and the acid value of the second polyurethane-based resin may be 29 to 41 mgKOH / g.

In addition, the main resin may further include a third polyurethane-based resin, and the glass transition temperature of the third polyurethane-based resin is -35 ° C to -10 ° C.

In addition, the main resin may include the first polyurethane-based resin and the third polyurethane-based resin in a weight ratio of 1: 0.04 to 0.2.

And, the acid value of the third polyurethane-based resin may be 2.5 mgKOH / g or less.

In addition, the conductive adhesive composition may further include an epoxy resin, and the epoxy equivalent of the epoxy resin is 80 to 300 g / eq.

In addition, the conductive adhesive composition may further include 0.1 to 1 part by weight of an antifoaming agent relative to 100 parts by weight of the main resin.

In addition, the content of the conductive filler may be 60 to 140 parts by weight relative to 100 parts by weight of the main resin.

In another aspect, the present invention provides a conductive adhesive composition, comprising: a main resin including at least one polyurethane-based resin; and a conductive filler having an average particle diameter of 3 to 20 ㎛.

According to an embodiment of the present invention, the conductive filler may satisfy the following conditions (1) and (2): (1) (2) Wherein, a, b and c are respectively D10 (㎛), D50 (㎛) and D90 (㎛) of the conductive filler.

In addition, D10 of the conductive filler may be 1 to 5 ㎛, D50 may be 5 to 20 ㎛, and D90 may be 20 to 35 ㎛.

In addition, the content of the conductive filler may be 60 to 140 parts by weight relative to 100 parts by weight of the main resin.

In addition, the apparent density (Apparent Density, AD) of the conductive filler may be 0.4 to 1, the tap density (TD) may be 0.8 to 2, and the specific surface area may be 3000 to 5000 ㎠ / g.

In addition, the conductive filler may include copper particles coated with silver on a surface, and a weight ratio of the copper to the silver may be 1: 0.02 to 0.2.

In addition, the conductive adhesive composition may further include 0.1 to 1 part by weight of an antifoaming agent relative to 100 parts by weight of the main resin.

In another aspect, the present invention provides an isotropic conductive film, including: a conductive adhesive layer formed of the above-mentioned conductive adhesive composition; and a release film provided on one side of the conductive adhesive layer.

The conductive adhesive composition of the present invention and the isotropic conductive film formed therefrom have the effects of excellent adhesion to the adhered surface, good heat resistance and flexibility, excellent electrical conductivity and uniform dispersion of the filler, As a result, uniform conductivity can be exhibited.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily implement the concepts of the present invention. It should be noted, however, that the present invention is not limited to the exemplary embodiments but can be implemented in various other ways.

A conductive adhesive composition according to an embodiment of the present invention includes: a main resin including a first polyurethane-based resin and a second polyurethane-based resin having glass transition temperatures different from each other; and a conductive filler.

First, the main resin will be described.

As the main resin, any main resin generally usable in a conductive adhesive composition in the art may be used without limitation. Preferably, it may include a urethane resin, and more preferably, it may include vitrification. Two types of polyurethane-based resins whose transition temperatures are different from each other, and more preferably, three types of polyurethane-based resins whose glass transition temperatures are different from each other may be in terms of adhesion, adhesion retention, flexibility, and heat resistance of the conductive film described below. advantageous.

The glass transition temperature (Tg ₁ ) of the first polyurethane-based resin may be 30 ° C. to 60 ° C., preferably, 30 ° C. to 50 ° C., and the glass transition temperature (Tg) of the second polyurethane-based resin. ₂ ) It may be -5 ° C to 20 ° C, preferably, 0 ° C to 20 ° C. If the glass transition temperature of the first polyurethane-based resin is less than 30 ° C, resin flow can occur during hot pressing. If the glass transition temperature of the first polyurethane-based resin is greater than 60 ° C, automatic positioning is performed. Adhesion may decrease during the welding (pre-fixation) step. In addition, if the glass transition temperature of the second polyurethane-based resin is less than -5 ° C, resin flow may occur during hot pressing, and if the glass transition temperature of the second polyurethane-based resin is greater than 20 ° C, then Adhesion may decrease during the automatic tack welding (pre-fixation) step.

According to an embodiment of the present invention, the main resin may include the first polyurethane-based resin and the second polyurethane-based resin in a weight ratio of 1: 0.2 to 0.6, and preferably includes the first polyurethane resin in a weight ratio of 1: 0.25 to 0.55. A polyurethane-based resin and a second polyurethane-based resin. If the weight ratio of the first polyurethane-based resin and the second polyurethane-based resin is less than 1: 0.2, the problem of insufficient adhesion may occur in the process of automatic tack welding (prefixing / 120 ° C, less than 1 second). If the weight ratio of the first polyurethane-based resin and the second polyurethane-based resin is greater than 1: 0.6, the problem of resin flowing and the resin flowing out during the process of hot pressing (150 ° C, 30 Kgf / cm ² , 60 minutes) may occur.

Moreover, the acid value of the first polyurethane-based resin may be 15 to 27 mgKOH / g, and preferably, the acid value may be 17 to 25 mgKOH / g. If the acid value of the first polyurethane-based resin is less than 15 mgKOH / g, the adhesion to the substrate may be reduced. If the acid value of the first polyurethane-based resin is greater than 27 mgKOH / g, the conductive filler may occur. Oxidation problem, and there may be a problem that the average resistance increases during constant temperature and humidity evaluation and PCT evaluation.

In addition, the acid value of the second polyurethane-based resin may be 29 to 41 mgKOH / g, and preferably, the acid value may be 31 to 39 mgKOH / g. If the acid value of the second polyurethane-based resin is less than 29 mgKOH / g, the adhesion to the substrate may decrease, and if the acid value of the second polyurethane-based resin is greater than 41 mgKOH / g, a conductive filler may occur Oxidation problem, and there may be a problem that the average resistance increases during constant temperature and humidity evaluation and PCT evaluation.

In addition, the weight average molecular weight of the first polyurethane-based resin may be 16,000 to 23,000, preferably 16,500 to 22,000, and the weight average molecular weight of the second polyurethane-based resin may be 8,000 to 15,000, preferably, It can be from 8,500 to 14,000. If the weight average molecular weight of the first polyurethane-based resin is less than 16,000 or the weight average molecular weight of the second polyurethane-based resin is less than 8,000, the adhesion to the adhered surface may decrease or the flexibility may decrease. If the weight average molecular weight of the resin-based resin is more than 23,000 or the weight average molecular weight of the second polyurethane-based resin is more than 15,000, the heat resistance may be reduced.

On the other hand, the main resin according to an embodiment of the present invention may further include a third polyurethane-based resin, and the glass transition temperature of the third polyurethane-based resin is -35 ° C to -10 ° C, preferably, The glass transition temperature of the third polyurethane-based resin is -30 ° C to -10 ° C. If the glass transition temperature of the third polyurethane-based resin is less than -35 ° C, removal of bubbles in the conductive adhesive composition may not be easy, and heat resistance may be poor. If the glass transition temperature of the third polyurethane-based resin is Above -10 ° C, the flexibility of the isotropic conductive film which will be described below may decrease, and the adhesion may decrease.

According to an embodiment of the present invention, the main resin may include the first polyurethane-based resin and the third polyurethane-based resin in a weight ratio of 1: 0.04 to 0.2, and preferably, the main resin may be included in a weight ratio of 1: 0.06 to 0.18. The first polyurethane-based resin and the third polyurethane-based resin. If the weight ratio of the first polyurethane-based resin and the third polyurethane-based resin is less than 1: 0.04, tack welding and adhesion are reduced, and flexibility is reduced. If the weight ratio of the first polyurethane-based resin and the third polyurethane-based resin is greater than 1: 0.2, there may be problems that the viscosity of the dried coating film increases, the heat resistance decreases, and the resin flow increases.

In addition, the acid value of the third polyurethane-based resin may be 2.5 mgKOH / g or less, and preferably, the acid value may be 2.0 mgKOH / g or less. If the acid value of the third polyurethane-based resin is more than 2.5 mgKOH / g, there may be a problem that the average circuit resistance before and after the PCT evaluation increases or the flexibility decreases.

Moreover, the weight average molecular weight of the third polyurethane-based resin may be 24,000 to 32,000, and preferably, it may be 25,000 to 31,000. If the weight average molecular weight of the third polyurethane-based resin is less than 24,000, the adhesion to the adhered surface may be reduced, or flexibility may be decreased. If the weight average molecular weight of the third polyurethane-based resin is more than 32,000, heat resistance May be reduced.

On the other hand, in a case where the conductive adhesive composition according to an embodiment of the present invention includes a first polyurethane-based resin, a second polyurethane-based resin, and a third polyurethane-based resin that have different glass transition temperatures from each other, the The first polyurethane-based resin, the second polyurethane-based resin, and the third polyurethane-based resin may all satisfy the following condition (3) and condition (4).

As condition (3), it can be , Preferably, can be . As condition (4), it can be , Preferably, can be .

If in condition (3), Above 70, the removal of air bubbles in the conductive adhesive composition may not be easy, and the flexibility of the isotropic conductive film which will be described below may be reduced. And, if in the condition (4), Above 1.2, the removal of air bubbles in the conductive adhesive composition may not be easy, and the flexibility of the isotropic conductive film described below may be reduced.

The conductive adhesive composition according to an embodiment of the present invention may further include an epoxy resin having an epoxy equivalent of 80 to 300 g / eq. Preferably, the conductive adhesive composition may further include an epoxy having an epoxy equivalent of 100 to 280 g / eq. Similar resins. If the epoxy equivalent of the epoxy-based resin is less than 80 g / eq, the adhesion force is reduced, the surface resistance becomes high, and problems may occur in terms of heat resistance. If the epoxy equivalent of the epoxy-based resin is more than 300 g / eq , The adhesion and adhesion may be reduced.

Wherein, the content of the epoxy-based resin may be 5 to 30 parts by weight, and preferably 10 to 25 parts by weight, relative to 100 parts by weight of the main resin. If the content of the epoxy-based resin is less than 5 parts by weight relative to 100 parts by weight of the main resin, a problem may occur in that the heat resistance of the isotropic conductive film described below is reduced. If the content of the epoxy-based resin is more than 30 parts by weight relative to 100 parts by weight of the main resin, a problem may occur in that the adhesive force with the plastic substrate is reduced.

The conductive adhesive composition according to an embodiment of the present invention may further include a solvent. The solvent can be used without limitation as long as it is a solvent generally usable in an adhesive composition, and it can be selected from the group consisting of toluene, dimethylformamide, xylene, benzene, and n- Methylpyrrolidone, n-octylpyrrolidone, dimethylsulfine, ethylcarbitol, butylcarbitol, ethyl cellosolve, butyl cellosolve, dimethylpyrazole, dipropylene glycol, n-butyl ether One or more solvents in the group consisting of methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl acetate, methanol, ethanol, isopropanol, n-propanol, and butanol, more preferably, it can be used One or more solvents selected from the group consisting of toluene and dimethylformamide.

Wherein, the content of the solvent may be 10 to 70 parts by weight with respect to 100 parts by weight of the main resin, and preferably 15 to 65 parts by weight, but the present invention is not limited thereto.

The conductive adhesive composition according to an embodiment of the present invention may further include a defoaming agent to remove air bubbles in the composition.

As the antifoaming agent, any antifoaming agent that is generally used in the adhesive composition in the art may be used without limitation. Preferably, it may include polysiloxane.

In addition, the content of the defoaming agent may be 0.1 to 1 part by weight, and preferably 0.2 to 0.8 part by weight with respect to 100 parts by weight of the main resin, but the present invention is not limited thereto.

Next, the conductive filler will be described.

According to an embodiment of the present invention, the content of the conductive filler may be 60 to 140 parts by weight with respect to 100 parts by weight of the main resin, and preferably 65 to 135 parts by weight. If the content of the conductive filler is less than 60 parts by weight relative to 100 parts by weight of the main resin, problems such as a decrease in heat resistance and an increase in surface resistance and circuit resistance may occur. If the content of the conductive filler is more than 140 parts by weight relative to 100 parts by weight of the main resin, there may be a problem that the adhesion force is reduced.

A conductive adhesive composition according to another embodiment of the present invention includes: a main resin including at least one polyurethane-based resin; and a conductive filler having an average particle diameter of 3 to 20 ㎛.

Hereinafter, a conductive adhesive composition according to another embodiment of the present invention will be described, but a description of the same portions as the above-mentioned conductive adhesive composition will be omitted.

The average particle diameter of the conductive filler may be 3 to 20 ㎛, and preferably, the average particle diameter may be 5 to 15 ㎛. If the average particle diameter of the conductive filler is less than 3 ㎛, there may be a problem of increased resin flow. If the average particle diameter of the conductive filler is more than 20 ㎛, there may be a decrease in adhesion due to uneven surface of the conductive adhesive layer. The problem of increased surface roughness.

And, the conductive filler according to another embodiment of the present invention can satisfy the following conditions (1) and (2).

As condition (1), it can be , Preferably, can be . As condition (2), it can be , Preferably, can be Wherein, a, b and c are D10 (㎛), D50 (㎛) and D90 (㎛) of the conductive filler, respectively.

If in condition (1), More than 56, the amount of conductive filler contaminated on the surface of the conductive adhesive layer described below may increase, and the surface roughness may increase due to the uneven surface of the conductive adhesive layer, tack welding, adhesion and adhesion Force is reduced. And, in the condition (2), More than 8, the amount of conductive filler contaminated on the surface of the conductive adhesive layer described below may increase, and the surface roughness may increase due to the uneven surface of the conductive adhesive layer, tack welding, adhesion and adhesion Force is reduced.

On the other hand, D10 of the conductive filler may be 1 to 5㎛, preferably, D10 may be 1.5 to 4.5㎛, D50 may be 5 to 20㎛, preferably, D50 may be 5.5 to 19㎛, and D90. It can be 20 ~ 35㎛, preferably D90 can be 21 ~ 33㎛.

If the D10 of the conductive filler is less than 1 ㎛, the tack welding, adhesion, and adhesion may decrease due to an increase in the amount of the conductive filler contaminated on the surface of the conductive adhesive layer to be described below. If the D10 of the filler is larger than 5 则, the surface roughness of the conductive adhesive layer may be increased due to the unevenness of the surface of the conductive adhesive layer, and the tack welding, adhesion and adhesion will be reduced. In addition, if the D50 of the conductive filler is less than 5 ㎛, the amount of conductive filler contaminated on the surface of the conductive adhesive layer to be described below may increase, which may lead to a decrease in tack welding, adhesion, and adhesion. If the D50 of the conductive filler is greater than 20 ㎛, the surface roughness of the conductive adhesive layer may be increased due to the unevenness of the surface of the conductive adhesive layer, and the tack welding, adhesion, and adhesion are reduced. In addition, if the D90 of the conductive filler is less than 20 ㎛, the amount of conductive filler contaminated on the surface of the conductive adhesive layer to be described below may increase, which may lead to a decrease in tack welding, adhesion, and adhesion. If the D90 of the conductive filler is greater than 35 ㎛, the surface roughness of the conductive adhesive layer may be increased due to the unevenness of the surface of the conductive adhesive layer, and the tack welding, adhesion, and adhesion are reduced.

The apparent density (Apparent Density, AD) of the conductive filler according to another embodiment of the present invention may be 0.4 to 1.0, preferably, the apparent density may be 0.5 to 0.8, and the tap density (TD) may be 0.8 ~ 2.0, preferably, the tap density may be 0.9 ~ 1.5. If the apparent density of the conductive filler is less than 0.4, there may be problems that the specific surface area increases, the dispersibility decreases, and the adhesion decreases. If the apparent density of the conductive filler is greater than 1, there may be problems that the volume is reduced compared to the same content, the conductivity is reduced, and the surface resistance is increased. In addition, if the tap density of the conductive filler is less than 0.8, the specific surface area of the conductive filler increases, resulting in an increase in the oil absorption of the resin, thereby reducing the adhesive force, and greatly reducing the thickness during the hot pressing process. If the tap density of the conductive filler is greater than 2.0, the problem of sedimentation of the conductive filler may occur, and the resin flow problem may occur due to the small oil absorption of the resin.

In addition, the specific surface area of the conductive filler may be 3000 to 5000 ㎠ / g, and preferably, 3200 to 4800 ㎠ / g. If the specific surface area of the conductive filler is less than 3000 ㎠ / g, there may be a problem of sedimentation of the conductive filler and a decrease in volume as compared with the same content, leading to a decrease in conductivity, and an increase in resin flow may exist. If the specific surface area of the conductive filler is more than 5000 ㎠ / g, there may be problems that the viscosity increases due to an increase in the oil absorption of the resin, the dispersibility decreases, and the adhesive force decreases.

On the other hand, as a conductive filler according to another embodiment of the present invention, as long as it is a material that can generally be used in the field, it can be used without limitation. Preferably, copper particles coated with silver on the surface are used to conduct electricity. Sexuality can be beneficial.

Wherein, in the copper particles coated with silver on the surface, the weight ratio of the copper to the silver is 1: 0.02 to 0.2, preferably 1: 0.05 to 0.15, from the viewpoint of conductivity. May be advantageous.

The shape of the conductive filler is not limited as long as it is a shape that can be generally used in the art. Preferably, a shape selected from the group consisting of flake shape, spherical shape, dendritic shape, granular shape, and fibrous shape The conductive filler having at least one shape in the formed group, more preferably, a conductive filler having at least one shape selected from the group consisting of a dendritic shape, a sheet shape, and a fiber shape.

On the other hand, as shown in FIG. 1, the isotropic conductive film 100 according to the present invention includes: a conductive adhesive layer 110 formed of the above-mentioned conductive adhesive composition; and a release film 120 disposed on the conductive adhesive layer 110. one side.

First, the conductive adhesive layer 110 will be described.

The conductive adhesive layer 110 may be different according to a required application, a kind of an adhered surface, and the like, and therefore, there is no particular limitation on this in the present invention. As an example, the thickness of the conductive adhesive layer 110 included in the isotropic conductive film 100 according to the present invention may be 20 to 100 ㎛, and preferably, the thickness may be 30 to 80 ㎛, but the present invention is not limited thereto.

In addition, the conductive adhesive layer 110 may include a conductive filler 111 uniformly dispersed in the layer.

Next, the release film 120 will be described.

As the release film 120, as long as it is a release film that can generally be used in an isotropic conductive film, it can be used without limitation. Preferably, a PET film can be used, and more preferably, a coating film can be used. A PET film of at least one of silicone, fluorine, and acrylic, but the present invention is not limited thereto.

In addition, the thickness of the release film 120 may be different according to the thickness of the conductive adhesive layer 110. Preferably, the thickness may be 20 to 100 ㎛, and more preferably, the thickness may be 30 to 80 ㎛, but the present invention is not limited to this. this.

In addition, as the release force of the release film 120, as long as it is the release force of a release film generally provided on an adhesive film, there is no restriction. Preferably, the release force may be 100 to 300 gf / Inch, more preferably, it can be 150 ~ 250 gf / inch, but the present invention is not limited to this.

On the other hand, the residual adhesion rate of the release film 120 may be 93% or more, and preferably, 95% or more. Wherein, the residual adhesion rate refers to a ratio of the adhesion force to the adhesion force after 24 hours when the initial adhesion force is 100. As an example, when the initial adhesion force is 100 and the adhesion force is 95 after 24 hours from the initial adhesion force, the residual adhesion rate may be 95%.

On the other hand, the conductive adhesive composition of the present invention and the isotropic conductive film formed therefrom have the effects of excellent adhesion to the adhered surface, good heat resistance and flexibility, excellent electrical conductivity, and can make The filler is uniformly dispersed so that it can exhibit uniform electrical conductivity.

Hereinafter, the present invention will be described more specifically with reference to examples, but the following examples should not be construed to limit the scope of the present invention, but should be construed to promote understanding of the present invention.

< Examples 1 ＞

( 1 ) Preparation of conductive adhesive composition

First, as a conductive filler, a solvent prepared by mixing toluene and dimethylformamide at a weight ratio of 1: 0.14 was mixed with an apparent density of 0.7, a tap density of 1.1, and a specific surface area of 4,100 ㎠ / g. Silver-coated copper particles with an oxygen content of 0.07% or less and an average particle size of 8 ㎛. The weight ratio of copper to silver is 1: 0.11, and the particle size distribution D10 of the conductive filler is 2.7 ㎛, D50 is 8.6 ㎛, and D90 is 21.5 ㎛.

A mixture is prepared by mixing a main resin in a solvent mixed with a conductive filler, and the main resin is obtained by mixing a weight average molecular weight of 18,000, a glass transition temperature (Tg ₁ ) of 40 ° C, and an acid value in a weight ratio of 1: 0.4. 21 mgKOH / g of a first polyurethane-based resin and a second polyurethane-based resin having a weight average molecular weight of 13,000, a glass transition temperature (Tg ₂ ) of 10 ° C., and an acid value of 35 mgKOH / g.

Wherein, the content of the solvent is 42 parts by weight and the content of the conductive filler is 114 parts by weight with respect to 100 parts by weight of the main resin in the mixture.

In the mixture, bisphenol A as an epoxy resin and polysiloxane as an antifoaming agent having an epoxy equivalent of 190 g / eq were mixed so that the content of bisphenol A relative to 100 parts by weight of the main resin. The content was 20 parts by weight, and the content of polysiloxane was 0.6 parts by weight, and then air bubbles were removed by using a vacuum to prepare a conductive adhesive composition.

( 2 ) Preparation of isotropic conductive film

As the release film, the prepared conductive adhesive combination was coated on one side of a PET film having a thickness of 50㎛ on the surface, a release force of 200 gf / inch, and a residual adhesion rate of 97%. And then dried to form an isotropic conductive film having a conductive adhesive layer having a thickness of 50 ㎛.

< Examples 2 ~ 42 And comparative example 1 ~ 4 ＞

In addition to changing the glass transition temperature, weight ratio, quantity, acid value, epoxy equivalent of epoxy resin, average particle size and particle size distribution of conductive fillers (D10, D50 and D90), except for the filler content, the apparent density and the tap density, were prepared in the same manner as in Example 1 as shown in Tables 1 to 7 for isotropic conductive films.

< Experimental example 1 ＞

The lower physical properties of the isotropic conductive films prepared according to the examples and comparative examples were evaluated, and the results are shown in Tables 1 to 7 below.

1. Surface roughness measurement

For the isotropic conductive films prepared according to the examples and comparative examples, the surface roughness Ra values were measured using the surface roughness meter and are shown in Tables 1 to 7 below.

2. Tack welding and adhesion evaluation

For the isotropic conductive films prepared according to the examples and comparative examples, it is judged whether or not a tack welding process is performed in the circuit resistance sample preparation process, and thus the results of the adhesion evaluation are shown in Tables 1 to 7 below.

3. Surface resistance measurement

For the isotropic conductive films prepared according to the examples and comparative examples, a surface resistance meter was used to measure the surface resistance, and 9 points were measured to obtain an average resistance. The results are shown in Tables 1 to 7 below.

< Experimental example 2 ＞

The isotropic conductive film and the reinforcing plate (SUS) prepared according to the examples and comparative examples were thermally laminated (120 ° C, 0.5 seconds), the release film was removed, and then tack welding (120 ° C, 0.5 seconds, pre-fixed), and subjected to a hot pressing (150 ° C, 30 Kgf / cm ² , 60 minutes) process and baking (160 ° C, 60 minutes) to prepare a circuit resistance sample. The following physical properties were evaluated, and the results are shown in Tables 1 to 7 below.

1. Circuit resistance measurement

The resistance of the samples prepared based on the circuit resistance sample preparation method described above using the isotropic conductive films prepared according to the examples and comparative examples was measured, and the circuit resistance was obtained by measuring the average resistance of 10 samples. The results are shown in Table 1. Go to Table 7.

2. Reflow evaluation

The isotropic conductive films prepared according to the examples and comparative examples were used to prepare samples based on the circuit resistance sample preparation method described above. The average of before and after passing the prepared 10 circuit resistance samples through a 260 ° C peak reflow tester twice was averaged. The circuit resistance was measured, and the results are shown in Tables 1 to 7.

3. Float Evaluation

The isotropic conductive films prepared according to the examples and comparative examples were used to prepare samples based on the circuit resistance sample preparation method described above. For the 10 circuit resistance samples prepared, the solder was melted at a temperature of 260 ± 5 ° C using a lead bath. And the average circuit resistance before and after immersing the sample was measured every 10 seconds, and the results are shown in Tables 1 to 7.

4. Constant temperature and humidity evaluation

The isotropic conductive films prepared according to the examples and comparative examples were used to prepare samples based on the above-mentioned circuit resistance sample preparation method, and the prepared 10 circuit resistance samples were placed at 85 ° C and 85% humidity for 96 hours before and after The average circuit resistance was measured, and the results are shown in Tables 1 to 7.

5. PCT Evaluation

The isotropic conductive films prepared according to the examples and comparative examples were used to prepare samples based on the circuit resistance sample preparation method described above, and the prepared 10 circuit resistance samples were left at 121 ° C, 2 atmospheres, and 100% humidity for 12 hours. The average circuit resistance was measured before and after, and the results are shown in Tables 1 to 7.

6. Thermal shock evaluation

The isotropic conductive films prepared according to the examples and comparative examples were used to prepare samples based on the circuit resistance sample preparation method described above, and a cycle of -45 ° C [15 minutes] ↔ 125 ° C [15 minutes] was measured to pass the samples through The average circuit resistance before and after 100 cycles is shown in Tables 1 to 7.

7. Resin flow evaluation

The isotropic conductive films prepared according to the examples and comparative examples were used to prepare samples based on the circuit resistance sample preparation method described above. Among the 10 circuit resistance samples prepared, the resin leaked between the reinforcing board and the flexible printed circuit board The average value was measured, and the results are shown in Tables 1 to 7.

< Experimental example 3 ＞

The isotropic conductive film and the reinforcing plate (SUS) prepared according to the examples and comparative examples were thermally laminated (120 ° C, 0.5 seconds), the release film was removed, and then positioning was performed on the polyimide portion (covering film). Welding (120 ° C, 0.5 seconds, pre-fixed), hot pressing (150 ° C, 30Kgf / cm ² , 60 minutes) and baking (condition: 160 ° C, 60 minutes) to prepare a length of 150㎜ and a width of 10 Rhenium polyimide adheres tightly to the sample.

Laminating an isotropic conductive film and a reinforcing plate (SUS) by thermal lamination (120 ° C, 0.5 seconds), removing the release film, and then performing tack welding (120 ° C, 0.5 seconds, prefixing) on a gold-plated (Au) part After hot pressing (150 ° C, 30 Kgf / cm ² , 60 minutes) and baking (160 ° C, 60 minutes), a gold adhesion sample having a length of 150 ㎜ and a width of 10 制备 was prepared.

Then, the lower physical properties of the polyimide adhesion force sample and the gold adhesion force sample were evaluated. The results are shown in Tables 1 to 7.

1. Adhesion force measurement

For the isotropic conductive films prepared according to the examples and comparative examples, the adhesion force of the samples prepared by the polyimide adhesion force sample and the gold adhesion force sample preparation method was measured, wherein the adhesion force was 180 The average value of 10 samples was measured under the conditions of a peeling angle of ° and a peeling speed of 50 ㎜ / min, and the results are shown in Tables 1 to 7 below. ＜ 表 1 ＞ Table 1 ＜ 表 2 ＞ Table 2 ＜ 表 3 ＞ Table 3 ＜ 表 4 ＞ Table 4 ＜ 表 5 ＞ Table 5 <Table 6> ＜ 表 7 ＞ Table 7

As can be seen from the above Tables 1 to 7, all satisfy Example 1 of the glass transition temperature, weight ratio, quantity, acid value, epoxy equivalent of the epoxy resin and the like of the preferred polyurethane resin according to the present invention. 3, 4, 7, 8, 16, 18, and 19 have good adhesion compared to Examples 2, 5, 6, 9-15, 17, 20-20, and Comparative Examples 1 and 2, which do not satisfy at least one of them. The surface roughness, surface resistance and circuit resistance are lower, and the results of reflow evaluation, floating welding evaluation, constant humidity and constant temperature evaluation, PCT evaluation and thermal shock evaluation are excellent, the resin flow is low, and the adhesion is good.

In addition, it can be seen that Examples 27, 28, 30, and 32, which satisfy the average particle diameter, particle size distribution (D10, D50, and D90), filler content, apparent density, and tap density of the preferred conductive filler according to the present invention Compared with Examples 29, 31, 33 to 42, and Comparative Examples 3 and 4 which did not satisfy at least one of them, the adhesion was good, the surface roughness, surface resistance, and circuit resistance were lower, reflow evaluation, floating soldering evaluation, and constant humidity The results of constant temperature evaluation, PCT evaluation, and thermal shock evaluation were excellent, the resin flow value was low, and the adhesion was good.

As described above, an embodiment of the present invention is described, but the gist of the present invention is not limited to the embodiments in the present invention. Those skilled in the art can add, modify, delete, add, etc. the constituent elements within the same gist range Other embodiments can be easily proposed, and these belong to the gist of the present invention.

100‧‧‧isotropic conductive film

110‧‧‧ conductive adhesive layer

111‧‧‧Conductive filler

120‧‧‧ release film

FIG. 1 is a cross-sectional view of an isotropic conductive film including a conductive adhesive composition according to an embodiment of the present invention.

Claims (18)

A conductive adhesive composition, comprising: a main resin comprising a first polyurethane-based resin and a second polyurethane-based resin having different glass transition temperatures; and a conductive filler. The conductive adhesive composition according to item 1 of the scope of the patent application, wherein the glass transition temperature of the first polyurethane-based resin is 30 ° C to 60 ° C, and the glass transition of the second polyurethane-based resin is The temperature is -5 ℃ ~ 20 ℃. The conductive adhesive composition according to item 1 of the scope of the patent application, wherein the main resin comprises a first polyurethane-based resin and a second polyurethane-based resin in a weight ratio of 1: 0.2 to 0.6. The conductive adhesive composition according to item 1 of the scope of patent application, wherein the acid value of the first polyurethane-based resin is 15 to 27 mgKOH / g, and the acid value of the second polyurethane-based resin is 29 to 41 mgKOH / g. The conductive adhesive composition according to item 1 of the scope of the patent application, wherein the main resin further includes a third polyurethane-based resin, and the third polyurethane-based resin has a glass transition temperature of -35 ° C to- 10 ° C. The conductive adhesive composition according to item 5 of the scope of the patent application, wherein the main resin comprises a first polyurethane-based resin and a third polyurethane-based resin in a weight ratio of 1: 0.04 to 0.2. The conductive adhesive composition according to item 5 of the scope of patent application, wherein the third polyurethane-based resin has an acid value of 2.5 mgKOH / g or less. The conductive adhesive composition according to item 1 of the scope of application for a patent, further comprising an epoxy resin, and the epoxy equivalent of the epoxy resin is 80 to 300 g / eq. The conductive adhesive composition according to item 1 of the scope of application for a patent, wherein the conductive resin composition further comprises 0.1 to 1 part by weight of an antifoaming agent relative to 100 parts by weight of the main resin. The conductive adhesive composition according to item 1 of the scope of patent application, wherein the content of the conductive filler is 60 to 140 parts by weight relative to 100 parts by weight of the main resin. A conductive adhesive composition, comprising: a main resin including at least one polyurethane-based resin; and a conductive filler having an average particle diameter of 3 to 20 ㎛. The conductive adhesive composition according to item 11 of the scope of application for a patent, wherein the conductive fillers satisfy the following conditions (1) and (2): (1) (2) Wherein, a, b and c are respectively D10 (㎛), D50 (㎛) and D90 (㎛) of the conductive filler. The conductive adhesive composition according to item 11 of the scope of patent application, wherein the conductive filler has D10 of 1 to 5 ㎛, D50 of 5 to 20 ㎛, and D90 of 20 to 35 ㎛. The conductive adhesive composition according to item 11 of the scope of patent application, wherein the content of the conductive filler is 60 to 140 parts by weight relative to 100 parts by weight of the main resin. The conductive adhesive composition according to item 11 of the scope of patent application, wherein the conductive filler has an apparent density of 0.4 to 1, a tap density of 0.8 to 2, and a specific surface area of 3000 to 5000 ㎠ / g. . The conductive adhesive composition according to item 11 of the scope of patent application, wherein the conductive filler includes copper particles coated with silver on a surface, and a weight ratio of the copper to the silver is 1: 0.02 ~ 0.2. The conductive adhesive composition according to item 11 of the scope of patent application, further comprising 0.1 to 1 part by weight of an antifoaming agent relative to 100 parts by weight of the main resin. An isotropic conductive film, comprising: a conductive adhesive layer formed of the conductive adhesive composition according to any one of claims 1 to 17; and a release film provided on the conductive film. One side of the adhesive layer.