KR20180037663A - Thermosetting conductive adhesive film for high-stepped structures - Google Patents

Abstract

The present invention relates to a thermosetting conductive adhesive film for high-stepped structures, which is produced by dispersing a dendritic metal powder in a thermosetting adhesive, and more specifically, to a thermosetting conductive adhesive film, in which one or more kinds of thermosetting adhesive resin/resins selected from a group consisting of an epoxy resin, an acrylic resin, a polyurethane resin, an ethylene vinyl acetate resin, a polyethylene resin, an epoxy-modified polyurethane resin, a polypropylene resin, a polystyrene resin and a polyvinyl chloride resin is/are filled with one or more kinds of dendritic conductive filler/fillers selected from a group consisting of gold, silver, nickel, copper, aluminum, silver plated nickel, silver plated copper, nickel plated graphite and silver plated ceramic, wherein the thermosetting conductive adhesive film has a film shape having self-adhesive property and is applicable to a high-stepped product such as a pressure sensor.

Description

TECHNICAL FIELD [0001] The present invention relates to a conductive film for high-

TECHNICAL FIELD The present invention relates to a thermosetting conductive film for high-stiffness, and more particularly, to a thermosetting conductive film for high-stiffness produced by dispersing a dendritic metal powder in a thermosetting adhesive.

Electromagnetic shielding materials are commonly applied to both FPCB (Flexible Printed Circuit Board) and Rigid PCB. In the case of the conductive adhesive film, it is applied to the multi-layer FPCB and functions to ground the electrode and the reinforcing plate. Flexibility is not required. In the case of the rigid PCB, the electromagnetic wave shielding film is not required to be flexible, and therefore, an inexpensive thin metal foil is often used.

However, in the case of FPCB, which requires repeated bending characteristics, the metal thin film or liquid paste paint has a poor flexing characteristic, which limits its use. Therefore, in the case of electromagnetic shielding materials used for FPCB, adhesive films with good heat adhesion and excellent flexibility, heat resistance, abrasion resistance and electrical conductivity are most suitable as shielding materials. Ultra-slim electromagnetic wave shielding films for FPCB are generally used for insulating layer, And a transfer film and a release film which are respectively transparent to the upper and lower surfaces thereof are attached. The insulating layer is made of a casting film layer, the metal thin film layer is made of a silver deposition layer, and the conductive adhesive layer is composed of an adhesive resin such as epoxy, urethane or acrylic mixed with a metal powder such as gold, silver, do.

Recently, there has been an increase in the number of high-stage types with a step height of 150 μm or more between the flex portion and the rigid portion of the multilayer FPCB such as the Flex-Rigid substrate. Accordingly, the demand for the shielding film, Are increasing together. In particular, a high-speed electromagnetic wave shielding film is required to develop a film that can cope with high-stage differences while maintaining various characteristics of an ultrathin electromagnetic wave shielding film. Further, development of a film that can cope with high-stage difference of a multi-layer FPC such as a Flex-Rigid substrate has been demanded by replacing an ultrathin electromagnetic wave shielding film divided into an existing adhesive layer and a conductive layer with a single-layer conductive adhesive layer.

KR 10-0874689 KR 20-0400977

An object of the present invention is to provide a method for manufacturing a high-strength steel sheet, which comprises a thermosetting resin for melting by heat and having self-adhesiveness in consideration of bonding properties in a high- And to provide a thermosetting conductive film.

It is still another object of the present invention to provide a method for producing a thermosetting conductive film for high-stage vehicles according to the present invention, which comprises a step of dispersing a dendritic metal powder in a thermosetting adhesive.

In order to achieve the above object, the present invention provides a thermosetting conductive film for a high-stage machine in which a thermosetting adhesive resin is filled with a conductive filler in the form of a dendrite.

In addition,

i) dissolving the thermosetting adhesive resin in an organic solvent;

ii) adding a dendritic conductive filler to the solution of step i) and uniformly dispersing the conductive filler to prepare a conductive film coating solution;

iii) vacuum degassing the conductive film coating solution prepared in step ii) using a vacuum deaerator;

iv) coating the vacuum degassed coating liquid prepared in step iii) with a uniform thickness on the substrate; And

v) aging the thermosetting conductive sheet coated in step iv);

Curable conductive film for high-stage use.

The present invention also provides a substrate on which an electrode pattern with a thermosetting conductive film according to the present invention is adhered.

In addition, the present invention provides a pressure sensor to which the thermosetting conductive film according to the present invention is adhered.

The present invention can be closely adhered in a stepped region when thermosetting resin is used by thermosetting resin. By applying a dendritic metal powder, the connection state between metal powders is not cut off even after an external force such as a banding or a twist is applied. A thermosetting conductive film suitable for the product structure of a high-stage car can be produced.

The present invention also relates to a process for producing a conductive film for a high-stiffness heat-curable conductive film, which comprises dispersing a dendritic metal powder in a thermosetting adhesive to form a conductive film, By establishing the optimum conditions, it is possible to maintain the appearance and maintain low surface resistance even after the application of external force such as banding and twist to overcome the problem of high resistance due to low adhesion probability of conductive filler with high adhesive force for bonding property in high- .

FIG. 1 is a graph showing the particle shape of dendrite-type silver plated copper having an apparent density (AD) of 0.7 to 1.2 g / cm ³ .
Fig. 2 is a graph showing the particle shape of dendritic silver-plated copper having an apparent density (AD) of 1.3 to 1.9 g / cm < ³ >.
FIG. 3 is a view showing a particle shape of dendritic silver-plated copper having an apparent density (AD) of 2.0 to 3.0 g / cm ³ .
4 is a schematic view of a pressure sensor to which a thermosetting conductive film is applied.

Hereinafter, the present invention will be described in detail.

The present invention provides a thermosetting conductive film for a high-stage in which a thermosetting adhesive resin is filled with a conductive filler in the form of a dendrite.

The thermosetting adhesive resin is a binder which is melted by heat to have a self-adhesive property. The binder is an epoxy resin, an acrylic resin, a polyurethane resin, an epoxy-modified urethane resin, an ethylene vinyl acetate resin, a polyethylene resin, a polypropylene resin, It is preferable to use one or two kinds of thermosetting adhesive resins selected from the group consisting of polyvinyl chloride resins and epoxy resins, and it is more preferable to use an epoxy-modified urethane resin.

Although general urethane resin is superior in flexibility, elasticity and restoring force, it has a disadvantage in that it has lower heat resistance and lower bonding strength than epoxy resin. However, urethane resin modified with epoxy functional group maintains flexibility, elasticity, It has an excellent adhesive strength and heat resistance.

The conductive filler may be one or two selected from the group consisting of gold, silver, nickel, copper, aluminum, silver plated nickel, silver plated copper, nickel plated graphite and silver plated ceramic for imparting conductivity to the thermosetting adhesive sheet. It is preferable to use a conductive filler of a kind or more, and silver-plated copper is more preferably used.

The conductive filler preferably has a dendritic shape. When the shape of the conductive filler is spherical, the filler filling rate in the binder is high, but the workability is lowered due to the high sedimentation speed. When the conductive filler is applied to a product having a high-stage difference, the contact probability of the filler in the binder is low. When the filler is in the form of a flake, the filler has a low density. When the filler is put into a binder and left to mix, the filler floats on the binder, resulting in deterioration in workability. In order to obtain sufficient resistance, There is a possibility that the price of the product will rise.

The density ratio of the conductive filler is preferably 40 to 70%. When the density ratio is less than 40%, the particle size of the conductive filler becomes small and the dendrite-shaped branch shape becomes a very sharp shape. In the process of uniformly dispersing the conductive filler in the resin using a high-speed stirrer, The bending test for measuring the resistance after bending and spreading the sheet several times may cause a phenomenon that the resistance of the conductive filler increases as the probability of contact of the conductive filler decreases. Also, when the density ratio exceeds 70%, the particle size of the conductive filler increases and the number of conductive fillers existing per unit area decreases. As a result, the resistance of the conductive filler in the bending test decreases and the resistance increases or breaks The silver content may increase and the unit price may increase.

Here, the density ratio can be expressed by the following Equation 1.

[Equation 1]

Density ratio (%) = AD / TD X 100,

In Equation 1, AD (Apparent density) is the apparent density of the metal body, and TD (Tap density) is the tap density of the metal body.

The conductive filler preferably has an average particle diameter of 10 to 40 mu m. When the average particle diameter is less than 10 mu m, it is difficult to ensure the desired conductivity and a larger amount of the conductive filler must be filled. When the average particle diameter exceeds 40 mu m, in the process of coating the conductive film, There is a possibility that defects such as irregularities occur on the surface.

The packing ratio of the conductive filler is preferably 40 to 70%. If the filling rate of the filler is less than 40%, the conductive performance can not be achieved and the shielding efficiency may decrease. If it exceeds 70%, the adhesive force may be lowered due to over filling of the filler and the flexibility of the film may be lowered, have.

In addition,

i) dissolving the thermosetting adhesive resin in an organic solvent;

ii) adding a dendritic conductive filler to the solution of step i) and uniformly dispersing the conductive filler to prepare a conductive film coating solution;

iii) vacuum degassing the conductive film coating solution prepared in step ii) using a vacuum deaerator;

iv) coating the vacuum degassed coating liquid prepared in step iii) with a uniform thickness on the substrate; And

v) aging the thermosetting conductive sheet coated in step iv);

Curable conductive film for high-stage use.

In the above manufacturing method, the thermosetting adhesive resin of step i) may be at least one selected from the group consisting of an epoxy resin, an acrylic resin, a polyurethane resin, an epoxy-modified urethane resin, an ethylene vinyl acetate resin, a polyethylene resin, a polypropylene resin, a polystyrene resin, It is preferable to use one or two kinds of thermosetting adhesive resins selected from the group consisting of vinyl resins, and it is more preferable to use an epoxy-modified urethane resin.

The organic solvent is preferably a mixture of one or more of methyl ethyl ketone (MEK), toluene or ethyl acetate (EA), more preferably methyl ethyl ketone (MEK) and toluene . When methyl ethyl ketone (MEK) is used alone, the volatility of the solvent is high, so the drying time of the coating solution is high during the coating operation and the workability is lowered. When toluene and ethyl acetate (EA) So that the coating liquid may not be uniformly dispersed. The proportion of the mixed organic solvent is preferably in the range of 60 parts by weight of methyl ethyl ketone and 40 parts by weight of toluene in 100 parts by weight of the total organic solvent. More preferably 70 parts by weight of methyl ethyl ketone and 30 parts by weight of toluene. If the ratio of toluene exceeds 40, the compatibility decreases. If the ratio of toluene is less than 30, the volatilization improving effect of the solvent may be insignificant.

The conductive filler of step ii) may be one or two selected from the group consisting of gold, silver, nickel, copper, aluminum, silver plated nickel, silver plated copper, nickel plated graphite and silver plated ceramic. It is preferable to use a conductive filler of a kind or more, and silver-plated copper is more preferably used.

The density ratio of the conductive filler is preferably 40 to 70%, more preferably 50 to 60%.

The average particle diameter of the conductive filler is preferably 10 to 40 탆, more preferably 12 to 20 탆.

The packing ratio of the conductive filler is preferably 40 to 70%, more preferably 50 to 60%.

In the above production process, the aging of step (v) is preferably aged at 40 to 60 ° C for 20 to 40 hours, more preferably at 50 ° C for at least 24 hours.

The present invention also provides a substrate on which an electrode pattern with a thermosetting conductive film according to the present invention is adhered.

In addition, the present invention provides a pressure sensor to which the thermosetting conductive film according to the present invention is adhered.

In order to improve bonding properties in a high-stage product structure such as a pressure sensor, a thermosetting resin can be used to adhere tightly in a step region during thermal curing, and a dendritic metal powder is applied, The connection state between the metal powders is not cut off, and a low surface resistance can be maintained.

The following examples further illustrate the present invention. However, the following examples are intended to illustrate the present invention, and the scope of the present invention should not be construed as being limited to the following examples. Accordingly, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

< Example  1> Thermosetting type  Preparation of conductive film

100 parts by weight of a modified urethane resin modified with an epoxy functional group and 30 parts by weight of an organic solvent in which methyl ethyl ketone and toluene were mixed in an amount of 70 to 30 were dissolved and dissolved in an electrically conductive filler so as to have an average particle diameter of 12 탆 and a density ratio of 55% by weight (55% fill ratio) of silver plated copper in the form of 56% dendrites was added to 100 parts by weight of the resin, uniformly dispersed using a mechanical high-speed stirrer, and the dispersed coating solution was vacuum degassed using a vacuum deaerator To prepare a conductive film coating solution. The conductive film coating solution thus prepared was cast on a polyethylene terephthalate (PET) film substrate to a uniform thickness using a comma coater and dried to prepare a conductive film having a thickness of 50 탆. The conductive film was aged at 50 캜 for 24 hours to obtain a thermosetting conductive film .

< Example  2> Conductivity filler Density ratio  Other Thermosetting type  Preparation of conductive film

A thermosetting conductive film was prepared in the same manner as in Example 1 except that silver plated copper in the form of a dendrite having a density ratio of 34% as a conductive filler was used.

< Example  3> Conductivity filler Density ratio  Other Thermosetting type  Preparation of conductive film

A thermosetting conductive film was prepared in the same manner as in Example 1 except that silver plated copper in the form of a dendrite having a density ratio of 72% as a conductive filler was used.

< Example  4> Conductivity filler  Different average particle diameters Thermosetting type  Preparation of conductive film

A thermosetting conductive film was prepared in the same manner as in Example 1 except that silver plated copper in the form of dendrites having an average particle diameter of 60 占 퐉 was used as the conductive filler.

< Example  5> conductivity filler  If the addition amount is different Thermosetting type  Preparation of conductive film

A thermosetting conductive film was prepared in the same manner as in Example 1, except that silver plated copper in dendritic form was added in an amount of 30 parts by weight (30% by weight) relative to 100 parts by weight of resin.

< Example  6> conductivity filler  If the addition amount is different Thermosetting type  Preparation of conductive film

A thermosetting conductive film was prepared in the same manner as in Example 1, except that silver plated copper in the form of dendrites was added in an amount of 80 parts by weight (80% by weight) relative to 100 parts by weight of the resin.

< Example  7> When thermosetting adhesive resin is different Thermosetting type  Preparation of conductive film

A thermosetting conductive film was prepared in the same manner as in <Example 1> except that a general urethane resin not modified with an epoxy functional group was used as the thermosetting adhesive resin.

< Example  8> Conductivity filler  Different form Thermosetting type  Preparation of conductive film

A thermosetting conductive film was prepared in the same manner as in <Example 1> except that silver-plated copper in the form of a sphere was used as the conductive filler.

< Example  9> Conductivity filler  Different form Thermosetting type  Preparation of conductive film

A thermosetting conductive film was prepared in the same manner as in <Example 1> except that silver plated copper in the form of flake was used as the conductive filler.

< Experimental Example  1> Thermosetting type  Performance Analysis of Conductive Film

<1-1> Adhesion test

The thermosetting conductive film was cut to a width of 10 mm and a length of 50 mm and thermally adhered to a polyimide film having a thickness of 25 탆 and hot pressed at 170 캜 and 1 MPa pressure for 1 hour using a hot press on a SUS 304 adherend, The degree of peel strength was measured at a rate of 90 degrees.

<1-2> Bending  Test

The surface resistance was measured by fixing the both ends of the film and bending 100,000 times in a test method in which one end of the fixed end was bent toward the other end and bent.

<1-3> Twisting  Test

The surface resistance was measured by twisting the film ten thousand times by a test method that beat the film by a force rotated in a direction orthogonal to the rotation axis of the bending test.

As a result, in Comparative Example 1, the surface resistance was high. In Comparative Example 2, the outer appearance of the coating was broken or poor, and cracking or fracture occurred after bending and twisting.

In particular, Example 1 exhibited a higher adhesive strength, lower surface resistance, maintained appearance, and lower surface resistance after bending and twisting than the comparative examples.

Coating Appearance Adhesion Surface resistance Bending  after
Surface resistance Bending  after
Exterior Twisting  after
Surface resistance Twisting  after
Exterior Example 1 O 1.23 kgf / cm 0.048 Ω / □ 0.125 Ω / □ O 0.164Ω / □ O Example 2 O 1.08 kgf / cm 0.451 Ω / □ 1.038Ω / □ O 1.137Ω / □ O Example 3 O 1.31 kgf / cm 1.521 Ω / □ 6.339Ω / □ O 0.879KΩ / □ △
(crack
Occur) Example 4 X
(Due to particles
Line) With a break
Due to
Not measurable 0.035 Ω / □ With a break
Due to
Not measurable X With a break
Due to
Not measurable X Example 5 O 1.49 kgf / cm 23.118Ω / □ 38.243Ω / □ O 41.212 Ω / □ O Example 6 △
(Smoothness
Bad) 0.42 kgf / cm 0.038 Ω / □ With a break
Due to
Not measurable X With a break
Due to
Not measurable X Example 7 O 0.64 kgf / cm 0.056 Ω / □ 0.156 Ω / □ O 0.158 Ω / □ O Comparative Example 1 O 1.11 kgf / cm 5.861Ω / □ 8.487Ω / □ O 10.231 Ω / □ O Comparative Example 2 △
(Smoothness
Bad) 0.92 kgf / cm 2.147Ω / □ 1.226KΩ / □ △
(crack
Occur) With a break
Due to
Not measurable X

Therefore, in the production of the thermosetting conductive film of the present invention, it was confirmed that there is a remarkable difference in performance depending on the form of the conductive filler, thereby establishing the optimum process conditions.

Claims (14)

A thermosetting conductive film for a high-stiffness type in which a thermosetting adhesive resin is filled with a conductive filler in the form of a dendrite.
The method according to claim 1,
Wherein the thermosetting adhesive resin is selected from the group consisting of an epoxy resin, an acrylic resin, a polyurethane resin, an ethylene vinyl acetate resin, a polyethylene resin, an epoxy modified polyurethane resin, a polypropylene resin, a polystyrene resin and a polyvinyl chloride resin Type or two or more kinds of thermosetting conductive films for high-speed vehicles.
3. The method of claim 2,
Wherein the thermosetting adhesive resin is an epoxy-modified polyurethane resin.
The method according to claim 1,
Wherein the conductive filler is one or more selected from the group consisting of gold, silver, nickel, copper, aluminum, silver plated nickel, silver plated copper, nickel plated graphite and silver plated ceramic. Conductive film.
5. The method of claim 4,
Wherein the conductive filler is silver-plated copper.
The method according to claim 1,
Wherein the conductive filler has a density ratio of 40 to 70% (w / v).
The method according to claim 1,
Wherein the conductive filler has an average particle diameter of 10 to 40 占 퐉.
The method according to claim 1,
Wherein the filling ratio of the conductive filler is 40 to 70% (w / w).
i) dissolving the thermosetting adhesive resin in an organic solvent;
ii) adding a dendritic conductive filler to the solution of step i) and uniformly dispersing the conductive filler to prepare a conductive film coating solution;
iii) vacuum degassing the conductive film coating solution prepared in step ii) using a vacuum deaerator;
iv) coating the vacuum degassed coating liquid prepared in step iii) with a uniform thickness on the substrate; And
v) aging the thermosetting conductive sheet coated in step iv);
Curing type conductive film for high-stiffness.
10. The method of claim 9,
Wherein the organic solvent of step i) is a mixture of methyl ethyl ketone (MEK) and toluene.
11. The method of claim 10,
Wherein the mixed organic solvent is used in a ratio of 60 to 70 parts by weight of methyl ethyl ketone and 30 to 40 parts by weight of toluene in 100 parts by weight of the total organic solvent.
10. The method of claim 9,
Wherein the aging of the step (v) is aged at 40 to 60 캜 for 20 to 40 hours.
A substrate on which an electrode pattern to which the thermosetting conductive film of any one of claims 1 to 8 is adhered is formed.
A pressure sensor to which the thermosetting conductive film of any one of claims 1 to 8 is adhered.

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