KR100924151B1 - Laminating elastic electric conductor and Method of making the same - Google Patents

Abstract

Preparing a support; Performing a liquid silicone rubber coating in which the conductive powder is dispersed and mixed on the support; Stacking a polymer film coated with a fluorine resin on a surface thereof while the liquid silicone rubber coating is cured; Intermediate curing the cure-cured liquid silicone rubber coating while pressing the polymer film; Peeling off the polymer film coated with the fluorine resin from the surface of the intermediate cured silicone rubber coating; And completely curing the intermediate cured silicone rubber coating to form an elastic conductive layer.

Surface Roughness, Lamination, Silicone Rubber, Hardening, Peeling, Fluorine Resin, Self Weight, Self Adhesive

Description

Laminating elastic electric conductor and Method of making the same

The present invention relates to a laminated elastic electrical conductor and a method of manufacturing the same, in particular, has a good surface roughness, excellent and uniform surface electrical conductivity, metal powder does not fall well due to external friction, good adhesion to the support and laminated elastic electrical It relates to a conductor and a method of manufacturing the same.

Conventionally, a metal powder is uniformly mixed with a silicone rubber resin on a gum, and then subjected to an extrusion or pressing process and then thermally cured to prepare an elastic electric conductor in a tube or sheet shape. However, in general, the silicone rubber of the gum has a high viscosity, especially when a large amount of metal powder is filled for excellent conductivity, the viscosity is higher, so that it is difficult to perform extrusion and pressing, thereby limiting the thickness of the elastic conductor. In addition, the silicone rubber resin of the gum has a disadvantage that the adhesive strength with the support is bad.

In addition, when the viscosity is high, there is a disadvantage in that it is not possible to continuously work in using the press process.

When the extrusion process is used, most of the hardening takes place in the air, so the metal powder is exposed to the surface of the elastic conductor with high and unevenness due to the self-weight of the materials used during the curing process, resulting in a rough surface of the elastic conductor and protruding metal powder. There is a risk of falling due to external friction, and the surface electrical conductivity falls.

According to another conventional manufacturing technique, a liquid conductive silicone rubber coating solution is prepared by uniformly mixing a metal powder with a liquid silicone rubber resin, and then the coating solution is coated on a support such as a fiber and then heat or moisture cured at atmospheric pressure. Manufactured. At this time, in order to smooth the coating work, the viscosity of the coating liquid should be lowered by using a diluent. In case of coating with a good electrical conductivity and thin thickness, the materials used in the liquid coating agent harden due to their own weight and the metal powder becomes high and unevenly on the surface of the elastic conductor. Exposed to the outside. Furthermore, since the surface of the laminated elastic conductor thus manufactured is hardened in atmospheric air during the manufacturing process, the metal powder is highly and unevenly exposed on the surface of the elastic conductor so that the surface of the elastic conductor becomes rough and the protruding metal powder is exposed to external friction. There is a high possibility of falling by the fall and the density of the surface of the elastic conductor is low, the surface electrical conductivity is lowered. In addition, the adhesive force between the support and the elastic conductor is weak because it is adhered to the support while being cured by moisture at atmospheric pressure.

As such, when the surface roughness is poor due to the metal powder exposed to the outside of the laminated elastic conductor surface highly and unevenly, the yield of the vacuum pickup is poor when the vacuum pickup for automatic surface mounting, the laminated elastic electrical conductor Highly protruding metal powder on the surface of the surface may cause problems on the automatic surface mounter and PCB circuits.

Accordingly, the present invention is proposed to solve such a problem, and an object of the present invention is to provide a laminated elastic electric conductor having a low thickness and improved surface roughness.

Another object of the present invention is to provide a laminated elastic electrical conductor having excellent adhesion to a support.

Another object of the present invention is to provide a laminated elastic electrical conductor in which metal powder does not fall well due to external mechanical friction.

Another object of the present invention is to provide a laminated elastic electrical conductor having a uniform and good surface electrical conductivity.

The above object is to prepare a support; Performing a liquid silicone rubber coating in which the conductive powder is dispersed and mixed on the support; Stacking a polymer film coated with a fluorine resin on a surface thereof while the liquid silicone rubber coating is cured; Intermediate curing the cure-cured liquid silicone rubber coating while pressing the polymer film; Peeling off the polymer film coated with the fluorine resin from the surface of the intermediate cured silicone rubber coating; And completely curing the intermediate cured silicone rubber coating to form an elastic electroconductive layer.

Preferably, the support may comprise foam rubber, fiber mesh, woven fiber, polymer film, ceramic substrate, or metal foil.

Preferably, the liquid silicone rubber coating may contain 50% to 85% by weight of the electrically conductive powder.

Further, preferably, the electrically conductive powder may be a metal powder including carbon, nickel, copper, silver, or a powder made of gold, or a copper powder coated on a surface of gold or silver.

In addition, the curing may be moisture curing, the polymer film may be a PET film.

Preferably, the surface electrical resistance of the elastic conductive layer is less than 1Ω, the thickness is between 0.02mm and 0.3mm, the hardness may be less than Shore A 70.

The above object is composed of a support and an elastic conductive layer laminated on the surface of the support, wherein the elastic conductive layer is formed by curing a liquid silicone rubber coating in which an electrically conductive powder is dispersed and mixed, The surface of the coating is pressurized by a polymer film coated with a fluorine resin to thereby expose the electroconductive powder after the curing onto the surface at a uniform height and by a laminated elastic electric conductor having a surface roughness corresponding to the polymer film. Is achieved.

Preferably, the elastic conductive layer may be further laminated on the back surface of the support.

In addition, the metal foil may be bonded to the back surface of the elastic conductive layer laminated on the back surface.

In addition, an electrical medium including a conductive rubber, a conductive thread, or a metal wire may be embedded through the support or formed on the side of the support to electrically connect the respective elastic conductive layers.

According to the above constitution, since the surface of the electrically conductive coating cured is cured while being pressurized while the polymer film coated with the fluorine resin is covered, the surface roughness of the resultant fully cured elastic conductive layer is moderately cured. By the surface of the polymer film that was in contact with the way, the metal powder protrudes to the surface uniformly at a suitable height and has good surface roughness and excellent electrical conductivity.

Moreover, since it hardens | cures by pressing in the state which interposed the electrically conductive coating between a polymer film and a support body, it has uniform and good adhesive force with a support body.

In addition, when the liquid conductive coating is cast and cured while applying an appropriate external pressure, the mixtures constituting the liquid conductive coating are uniformly distributed to the support layer or surface by pressure, atmospheric pressure, and self-weight so that they are uniformly distributed. After complete curing, the elastic conductive layer has more desirable properties than when cured at atmospheric pressure.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention.

1 is a perspective view showing a laminated elastic electrical conductor according to an embodiment of the present invention.

The elastic conductive layer 10 is adhered to the support 20 to form a laminated elastic conductive member.

The support 20 includes foam rubber, fiber mesh, woven fiber, polymer film, ceramic substrate, or metal foil.

After the elastic conductive layer 10 is hardened by the moisture mixed with the metal powder is dispersed and cast on the support 20 with a liquid electroconductive silicone rubber coating having adhesion with the support 20 after curing, Is cured at atmospheric pressure, moderately cured underneath the polymer film under constant pressure, and fully cured by peeling off the polymer film.

As such, after casting, the materials used for the coating of the liquid electroconductive silicone rubber during the temporary curing and the intermediate curing process have excellent and uniform adhesion with the support 20 due to the self-weight caused by atmospheric pressure and the pressure applied from the outside after the temporary curing. Will have

In addition, the surface of the elastic electroconductive layer 10 after the temporary curing is subjected to a certain pressure under the polymer film is intermediately cured, the metal powder uniformly mixed distribution distribution in the liquid electroconductive coating before curing is the elastic conductive layer after the intermediate curing ( 10) The surface is uniformly exposed to a certain height so that the surface roughness and electrical conductivity are good.

Hereinafter, the manufacturing method of the laminated elastic electric conductor of the above-mentioned structure is demonstrated.

2 is a flowchart illustrating a method of manufacturing a laminated elastic electric conductor according to an embodiment of the present invention.

Referring to Figure 2, first, the support is prepared (step S21). The support 20 is, for example, an insulating foamed silicone rubber on a roll having a width of 200 mm, a thickness of 2 mm, and a hardness of about Shore A 30. In addition, as the support 20, a fiber mesh, a woven fiber, a polymer film, a metal foil, or an insulating ceramic sheet may be applied in addition to the insulating foam silicone rubber. The support 20 may be selected and applied to improve the mechanical strength of the elastic conductive layer 10 or to provide excellent elasticity or to impart additional characteristics such as a ceramic sheet. If necessary, the surface of the support 20 is subjected to a surface treatment such as a primer in advance in order to improve adhesion.

Subsequently, a conductive powder of carbon, nickel, copper, silver, or gold, or a metal powder including copper powder coated on the surface of gold or silver is added to the liquid moisture-curable silicone rubber in a weight ratio of 50% to 85%. The liquid conductive electroconductive silicone rubber coating made by mixing is cast on the support 20 (step S22).

Here, the liquid moisture-curable silicone rubber is a product having a self-adhesive force with the support 20 after curing while being cured by moisture at room temperature, for example, may be a product number LDC21 of the US Dow Corning. Here, if the amount of the metal powder to be mixed in order to impart electrical conductivity, the conductivity of the conductive layer 10 after curing is good, but the elastic force is bad, it is difficult to cast. Diluents such as toluene can be mixed with the liquid conductive silicone rubber mixed with metal powder to adjust the viscosity.Too much addition of toluene lowers the viscosity before curing, resulting in better processability but lowering the density of silicone rubber after curing. The conductivity and elastic force worsen.

In the casting step for the coating, preferably, the casting of the liquid electrically conductive silicone rubber is carried out in a semi-vacuum or nitrogen atmosphere with low humidity, and a thickness in the range of 20 μm to 300 μm by a knife casting process. The electrically conductive silicone rubber in the furnace is coated on the surface of the support 20.

Subsequently, the cast liquid electroconductive silicone rubber coating is cured by leaving it for about 30 seconds to 10 minutes in an atmosphere of atmospheric pressure having a humidity of about 70% to 90% and a temperature of about 25 ° C to 90 ° C (step S23). ). The temporary curing conditions are adjusted by changing the formulation of the coating liquid, the thickness of the coating layer, and the curing temperature and humidity.

Here, the temporary curing means that the electroconductive coating of the cast liquid has been cured to a certain degree. Preferably, after the temporary curing, the fluororesin-coated film is attached and then peeled off again. It refers to the point when the conductive silicone rubber coating is not raised or buried along the film. In other words, when a polymer film coated with a fluorine resin is laminated on the surface of the electrically conductive coating of the cured liquid and then peeled off, a sticky phenomenon due to self-adhesive force does not occur between the coating surface and the polymer film. Means.

At this time, the temporary curing conditions change according to the ambient humidity and temperature. For example, when the humidity and temperature are high, the temporary curing time is increased.

Subsequently, after the liquid silicone rubber coating is cured, a polymer film coated with a fluororesin is immediately laminated on the cured electrically conductive coating (step S24). For example, the fluorine resin may be Teflon of DuPont, USA, and the polymer film may be a PET film having a thickness of 0.1 mm. The reason for using the polymer film coated with the fluorine resin is to easily peel off the polymer film from the surface of the intermediate cured coating as described below.

Thereafter, while the polymer film coated with the fluorine resin is laminated, the polymer film is pressed for a predetermined time using a continuous roller or the like (step S25), and the cured electrically conductive silicone rubber coating is intermediately cured (step S26). The cured electroconductive silicone rubber coating results in an intermediate cured electroconductive silicone rubber coating inside the polymer film.

Preferably, the curing temperature is in the range of 25 ° C. to 85 ° C., and the humidity is suitably 60% to 90%.

Here, preferably, the intermediate curing means a time point in a state where the fluorine resin does not have adhesion with a film or other object not coated. In other words, while temporary curing means that the liquid silicone mixture having fluidity is partially contained inside the silicone rubber coating which has not yet been cured by the external pressure, intermediate curing refers to the coating of the coating which is not yet cured by the external pressure. It means a state in which the liquid silicone mixture having fluidity therein is not contained. Here, the liquid silicone mixture having fluidity has self adhesive strength after curing.

Through such a process, the electrically conductive silicone rubber coating surface hardened by the pressure applied to the polymer film by the roller is in a state in which the liquid silicone mixture flows out to the surface of the coating under pressure. In this state the surface of the coating is intermediate cured so that the surface of the electroconductive coating has roughness similar to the surface roughness of the polymer film, and the metal powder is arranged with uniform density at a constant height on the surface of the electroconductive coating.

At this time, if the external pressure is too high, the amount of liquid silicone mixture flowing out increases, which improves the surface roughness. However, the surface of the electroconductive coating is mostly buried in the metal powder by the large amount of liquid silicone mixture that comes out. Therefore, the right pressure should be applied at the right time. As such, the polymer film and the cured coating have a weak force with each other and are bonded to each other to achieve intermediate curing by ambient moisture.

In addition, the adhesive force with the support 20 after the complete curing is improved by the liquid silicone mixture flowing out of the electrically conductive coating cured by pressure even on the back surface of the electroconductive coating in contact with the support 20. Preferably, the curing conditions of the intermediate curing except for the external pressure are similar to the temporary curing conditions.

Thereafter, the polymer film coated with the fluorine resin attached to the surface of the intermediate cured electroconductive coating is peeled off (step S27). At this time, the polymer film coated with the fluorine resin is easily peeled off from the surface of the intermediate conductive electroconductive coating due to the property of the fluorine resin.

 Thereafter, the intermediate cured electroconductive coating from which the polymer film has been removed is completely cured in the air to prepare an elastic electroconductive layer 10 (step S28). At this time, preferably the curing conditions are 25 ℃ to 80 ℃ temperature and 60% to 85% humidity. That is, the surface of the intermediate cured electroconductive coating in contact with the polymer film is somewhat slow in moisture cure by the polymer film, thereby removing the polymer film located on the surface of the intermediate cured coating so that the full cure is accelerated.

By fully cured herein is meant a state in which the intermediate cured coating has a stable inherent physical property in which the cured coating is further cured and there is no further change in physical properties.

Through the above process, the lower portion of the liquid moisture curable electroconductive silicone coating adheres well to the support 20 while being moisture cured, and the surface of the upper portion of the elastic electroconductive layer 10 is made of metal powder with a uniform height. Exposed with a constant density, the surface roughness of the elastic conductive layer 10 is improved and has a uniform and excellent electrical conductivity.

Preferably, the surface electrical resistance of the fully cured elastic conductive layer 10 is 1 Ω or less and the hardness is Shore A 70 or less.

In general, when a liquid conductive coating liquid is applied to the support 20 and coated, and then cured at atmospheric pressure in the absence of external pressure, the metal powder contained in the conductive coating liquid after complete curing is applied to the elastic conductive layer 10. Disorderly exposed to irregular height on the surface, roughness of the surface is rough, electrical conductivity is bad and irregular.

However, according to the present invention, since the intermediate curing is performed while the PET film coated with the fluorine resin is coated on the surface of the cured electroconductive coating, the resultant fully cured elastic conductive layer 10 is formed. The surface roughness of the metal powder protrudes uniformly and uniformly to the surface by the surface of the PET film which was in contact during the intermediate curing, and has good surface roughness and excellent electrical conductivity.

Furthermore, since the curing is performed while the electroconductive coating is interposed between the PET film and the support 20, the support film 20 also has a uniform and good adhesion.

In addition, when the liquid conductive coating is cast and then cured while applying an appropriate external pressure, the mixtures constituting the liquid conductive coating are uniformly distributed to the support layer 20 or the surface by pressure, atmospheric pressure, and self weight. Because of their placement, the elastic conductive layer 10 after complete curing has more desirable properties than when cured at atmospheric pressure.

Figure 3 is a perspective view of a laminated elastic electrical conductor according to another embodiment of the present invention.

Elastic conductive layers 10 and 30 are formed on the front and rear surfaces of the support 20, respectively, to form a laminated elastic conductive material.

The support 20 includes foam rubber, fiber mesh, woven fiber, polymer film, ceramic substrate, or metal foil, as described above.

The elastic conductive layer 30, like the elastic conductive layer 10, is formed by casting, pressing and curing a liquid electroconductive coating in which a metal powder is dispersed and mixed on a polymer film.

Preferably, a metal foil may be bonded to the back surface of the elastic conductive layer 30, and reflow soldering may be performed by bonding the metal foil. At this time, the metal foil is bonded in the process of curing the elastic conductive layer 30.

Also, in order to electrically connect the upper elastic conductive layer 10 and the lower elastic conductive layer 30, the conductive rubber, the conductive thread, or the metal wire may be embedded to penetrate the support 20. Or on both sides.

Although the above has been described with reference to the embodiments of the present invention, various modifications are possible at the level of those skilled in the art. Therefore, the scope of the present invention should not be limited to the above embodiment but should be interpreted by the claims described below.

1 is a perspective view showing a laminated elastic electrical conductor according to an embodiment of the present invention.

2 is a flowchart illustrating a method of manufacturing a laminated elastic electric conductor according to an embodiment of the present invention.

Figure 3 is a perspective view of a laminated elastic electrical conductor according to another embodiment of the present invention.

Claims (13)

Preparing a support; Performing a liquid silicone rubber coating in which the conductive powder is dispersed and mixed on the support; Stacking a polymer film coated with a fluorine resin on a surface thereof while the liquid silicone rubber coating is cured; Intermediate curing the cure-cured liquid silicone rubber coating while pressing the polymer film; Peeling off the polymer film coated with the fluorine resin from the surface of the intermediate cured silicone rubber coating; And Fully curing the intermediate cured silicone rubber coating to form an elastic conductive layer. The method according to claim 1, Wherein said support comprises a foam rubber, a fiber mesh, a woven fiber, a polymer film, a ceramic substrate, or a metal foil. The method according to claim 1, The method of manufacturing a laminated elastic electrical conductor, characterized in that 50% to 85% by weight of the electrically conductive powder in the liquid silicone rubber coating. The method according to claim 1 or 3, The electrically conductive powder is carbon, nickel, copper, silver, or a powder made of gold, or a metal powder comprising a copper powder coated with gold or silver on the surface, characterized in that the manufacturing method of the laminated elastic electric conductor. The method according to claim 1, Said temporary curing, intermediate curing and complete curing are moisture curing. The method according to claim 1, The polymer film is a laminated elastic electrical conductor manufacturing method, characterized in that the PET film. delete It consists of a support and an elastic conductive layer laminated on the surface of the support, The elastic conductive layer is formed by curing a liquid silicone rubber coating in which the conductive powder is dispersed and mixed, and during the curing, the surface of the coating is pressurized by a polymer film coated with a fluorine resin, thereby curing the conductive powder. Is exposed on the surface with a uniform height and has a surface roughness corresponding to the polymer film. delete The method according to claim 8, Laminated elastic electrical conductor, characterized in that the elastic conductive layer is further laminated on the back surface of the support. The method according to claim 10, Laminated elastic electrical conductor, characterized in that the metal foil is bonded to the back surface of the elastic conductive layer laminated on the back surface. delete The method according to claim 10, An electrical medium comprising a conductive rubber, a conductive thread, or a metal wire is embedded through the support or formed on the side of the support so that each of the elastic conductive layers is electrically connected to each other. .

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