KR102247321B1 - Method for controlling electromagnetic properties of metal coated carbon fiber - Google Patents

Abstract

According to the present invention, provided is a method for controlling electromagnetic properties of a metal coated carbon fiber which comprises: a first step of selecting a type of metal to be coated on carbon fiber and a coating method in order to match complex dielectric constant and complex permeability of a metal coated carbon fiber to set values; and a second step of coating the metal on the carbon fiber in accordance with the selected type of metal and coating method while making a shape of the metal to be coated on the carbon fiber into a set shape, and matching the complex dielectric constant and the complex permeability of the metal coated carbon fiber to the set values.

Description

Method for controlling electromagnetic properties of metal coated carbon fiber

The present invention relates to a method for controlling electromagnetic properties of a metal coated carbon fiber.

Metal-coated carbon fiber is a material coated with metals such as copper, silver, nickel, and cobalt on carbon fiber.

The metal-coated carbon fiber has the properties of a metal having high thermal conductivity and electrical conductivity, and the strength and light weight inherent in carbon fiber at the same time, and has excellent electromagnetic wave shielding function and physical strength.

For this reason, the metal-coated carbon fiber can be used in various fields such as electromagnetic wave shielding materials, heating wires, and sensors of various products such as smartphones, monitors, and TVs.

Nevertheless, we have yet to find out what kind of metal is coated on carbon fiber, how to coat metal on carbon fiber, electromagnetic properties of metal coated carbon fiber according to the shape of metal coated on carbon fiber, and how to control these properties. R&D is insufficient.

Korean registered patent (10-2002012)

An object of the present invention is to provide a method for controlling electromagnetic properties of a metal-coated carbon fiber, which can solve the above-described problems.

A method for controlling electromagnetic properties of a metal-coated carbon fiber to achieve the above object,

A first step of selecting a type of metal to be coated on the carbon fiber and a coating method for matching the complex dielectric constant and the complex permeability of the metal-coated carbon fiber to a set value; And

The metal is coated on the carbon fiber according to the selected metal type and coating method, but the complex dielectric constant and the complex permeability of the metal-coated carbon fiber are adjusted to the set value by coating while making the shape of the metal coated on the carbon fiber into a set shape. It characterized in that it comprises a second step of fitting.

In the present invention, in order to make the complex dielectric constant and complex permeability of the metal-coated carbon fiber to a set value, the type of metal to be coated on the carbon fiber and the coating method are selected, and accordingly, the metal is coated on the carbon fiber, The coated metal is coated while making the shape of the coated metal into a set shape, and the complex dielectric constant and complex permeability of the metal-coated carbon fiber are finally adjusted to the set value. The electromagnetic properties of the metal-coated carbon fiber are determined by the complex dielectric constant and the complex permeability of the metal-coated carbon fiber thus matched.

In summary, the electromagnetic properties of the metal-coated carbon fiber are set in advance according to the fields of use such as electromagnetic wave shielding material, heating wire, and sensor, and the complex dielectric constant and complex permeability of the metal-coated carbon fiber are determined accordingly. In order to control the complex dielectric constant and complex permeability of such a metal-coated carbon fiber, the present invention is used.

Therefore, using the present invention, it is possible to precisely adjust the electromagnetic properties of the metal-coated carbon fiber according to the field of use, such as electromagnetic wave shielding material, heating wire, and sensor.

1 is a flow chart showing a method of controlling electromagnetic properties of a metal-coated carbon fiber according to an embodiment of the present invention.
FIG. 2 is a photo of carbon fiber coated with silver, FIG. 2(a) is a photo coated by sputtering on carbon fiber for 5 minutes, and FIG. 2(b) is a photo on which silver is sputtered on carbon fiber for 10 minutes. This is a coated photo.
FIG. 3 is a photo of nickel coated on carbon fiber, FIG. 3 (a) is a photo coated by electroless plating on carbon fiber for 20 seconds, and FIG. 3 (b) is a photo of nickel coated on carbon fiber for 30 seconds. Figure 3 (c) is a photo coated by electroless plating, and Figure 3 (c) is a photo coated by electroless plating on carbon fiber for 1 minute, and Figure 3 (d) is a photo on which nickel is electrolessly plated on carbon fiber for 2 minutes. It is a coated photo, and FIG. 3(e) is a photo coated by electroless plating on carbon fiber for 5 minutes with nickel.
4 is a graph comparing electromagnetic wave shielding performance of PU (polyurethane), PS (polystyrene), MCF/PU tape, Cu/PS tape, and CF/PU tape according to the intensity of the frequency of the electromagnetic wave.
5 is a view for explaining the degree of reflection, absorption, and transmission of electromagnetic waves of the shielding material, FIG. 5(a) is a CF/PU tape, FIG. 5(b) is an MCF/PU tape, and FIG. 5(c) is a Cu/PS It is a diagram showing the degree of reflection, absorption, and transmission of electromagnetic waves of a tape.
6 to 8 are graphs for explaining the complex dielectric constant of an MCF/PU tape.
9 to 11 are graphs for explaining the complex permeability of the MCF/PU tape.
12 is a table summarized by comparing the shielding performance of MCF/PU tape, CF/PU tape, and Cu/PS tape according to the intensity of the frequency of electromagnetic waves.

Hereinafter, a method of controlling electromagnetic properties of a metal-coated carbon fiber according to an embodiment of the present invention will be described in detail.

As shown in Figure 1, the method of adjusting the electromagnetic properties of the metal-coated carbon fiber according to an embodiment of the present invention,

A first step (S11) of selecting the type of metal to be coated on the carbon fiber and a coating method in order to match the complex dielectric constant and the complex permeability of the metal-coated carbon fiber to a set value;

The metal is coated on the carbon fiber according to the selected metal type and coating method, but the complex dielectric constant and the complex permeability of the metal-coated carbon fiber are adjusted to the set value by coating while making the shape of the metal coated on the carbon fiber into a set shape. It consists of a second step (S12) matching.

[Example 1]

The first step S11 will be described.

Silver is selected as the type of metal to be coated on the carbon fiber.

The coating method of the metal to be coated on the carbon fiber is selected by the sputtering method, which is a physical vapor deposition method.

The second step (S12) will be described.

Silver is sputtered on the carbon fiber for 5 minutes, and as shown in Fig. 2(a), it is made into round grains having a size of about 1 μm, which is a set shape, and coated on the carbon fiber.

Silver is sputtered on the carbon fiber for 10 minutes to form a cylindrical shape surrounding the outer circumferential surface of the carbon fiber, as shown in FIG. 2(b), and coated on the carbon fiber.

Silver is coated on the carbon fiber by the silver selected in the first step (S11) and the second step (S12), the selected sputtering method, the selected silver, and the sputtering method, but if the shape of silver is adjusted according to the sputtering time, silver coating The complex dielectric constant and complex permeability of the carbon fiber can be finally adjusted to the set value. When the complex dielectric constant and complex permeability of the silver-coated carbon fiber are determined, the electromagnetic properties of the silver-coated carbon fiber are also determined.

The description of the present invention will be made in more detail in the second experimental example from which various experimental data were extracted than in the first experimental example.

[Example 2]

The first step S11 will be described.

The type of metal to be coated on the carbon fiber is selected with nickel.

The coating method of the metal to be coated on the carbon fiber is selected by electroless plating, which is a chemical plating method.

The second step (S12) will be described.

Nickel is electrolessly plated on the carbon fiber for 20 seconds, and as shown in Fig. 3(a), it is made into round grains having a size of about 1 μm, which is a set shape, and coated on the carbon fiber.

Nickel is electrolessly plated on the carbon fiber for 30 seconds, and as shown in FIG. 3(b), the carbon fiber is coated in the shape of round grains having a size of about 1.2 μm.

Nickel is electrolessly plated on the carbon fiber for 1 minute, and as shown in FIG. 3(c), the carbon fiber is coated in the shape of round grains having a size of 1.5 μm.

Nickel is electrolessly plated on the carbon fiber for 2 minutes, and as shown in Fig. 3(d), it is made into a polygonal shape having a size of 2 μm, which is a set shape, and coated on the carbon fiber.

Nickel is electrolessly plated on the carbon fiber for 5 minutes to form an elliptical shape having a size of 10 μm, which is a set shape, as shown in FIG. 3(e), and coated on the carbon fiber.

The nickel selected in the first step (S11) and the second step (S12), the selected electroless plating method, the selected nickel, and the carbon fiber are coated with nickel by the electroless plating method. By adjusting the shape, the complex dielectric constant and the complex permeability of the nickel-coated carbon fiber can be finally adjusted to the set values. When the complex dielectric constant and complex permeability of the nickel-coated carbon fiber are determined, the electromagnetic properties of the nickel-coated carbon fiber are also determined.

Hereinafter, the electromagnetic wave shielding performance of the shielding material containing the nickel-coated carbon fiber in which the complex dielectric constant and the complex permeability are adjusted will be described.

Here, the complex dielectric constant and complex permeability of the nickel-coated carbon fiber are made into an elliptical shape having a size of 10 μm, as shown in FIG. 3(e), by electroless plating nickel on the carbon fiber for 5 minutes, It was controlled by coating on carbon fiber. Of course, the complex dielectric constant and the complex permeability can be variously adjusted by making nickel into different shapes.

As shown in Figure 4,

Nickel-coated carbon fiber shielding material is made by coating a nickel-coated carbon fiber on polyurethane. (Hereinafter referred to as “MCF/PU tape”)

Copper shielding is made by coating copper with polystyrene. (Hereinafter referred to as “Cu/PS tape”)

Carbon fiber shielding material is made by coating carbon fiber on polyurethane. (Hereinafter referred to as “CF/PU tape”)

As shown in FIG. 4, PU (polyurethane) and PS (polystyrene) used as the base film do not exhibit an electromagnetic wave shielding effect.

As shown in Figure 4, the shielding efficiency of the CF/PU tape is 98.0945% (-17.2 dB). As shown in Fig. 5(a), the CF/PU tape reflects and transmits the applied electromagnetic wave (Incident EM Wave). Reflected electromagnetic waves affect external electronic devices due to interference, and transmitted electromagnetic waves affect internal electronic devices wrapped by shielding materials, so it is not suitable as a shielding material with CF/PU tape.

4, the shielding efficiency of the Cu/PS tape is 99.99997% (-65.4 dB). As shown in FIG. 5(b), the Cu/PS tape mostly reflects the applied electromagnetic wave (Incident EM Wave) and transmits it by attenuating a small part. Cu/PS tape is very good in protecting internal electronic devices from external electromagnetic waves, but it can affect external electronic devices as a second interference phenomenon due to the reflected electromagnetic waves. It is not suitable as a shielding material.

4, the shielding efficiency of the MCF/PU tape is 99.9998% (-57.3 dB). As shown in Fig. 5(c), the MCF/PU tape partially reflects, mostly absorbs, and attenuates a part of the applied electromagnetic wave (Incident EM Wave). For this reason, MCF/PU tape is excellent in protecting internal electronic devices from external electromagnetic waves, and has excellent absorption performance, so that the influence of external electronic devices can be minimized. These MCF/PU tapes show a minute difference of 0.00016% (-8.1dB) from Cu/PS tapes in electromagnetic wave shielding performance, and are suitable for use as shielding materials.

The reason can be explained by the complex dielectric constant and complex permeability of MCF/PU tape.

6 and 7, the complex dielectric constant is a complex number and is expressed by ε′ as a real part and ε″ as an imaginary part.

The complex dielectric constant responds to an external electric field, and molecules form dielectric polarization (+/-) in the opposite direction of the electric field, and an electric field is formed inside the medium (MCF, CF, Cu, etc.), indicating the degree to which the intensity of the external electric field is reduced. .

The real part of the complex dielectric constant represents the rate at which the external electric field is reduced in the medium, and the intensity of the external electric field is reduced in the medium with a high dielectric constant.

Meanwhile, as the frequency increases, the external electric field strength cannot be reduced according to the speed of the propagation due to inertia, but at this time, the external electric field strength may be reduced by the imaginary part of the complex dielectric constant.

The loss of the complex dielectric constant shown in FIG. 8 is calculated as (the complex dielectric constant imaginary part (ε″)/the complex dielectric constant real part (ε')). As the loss of the complex dielectric constant increases, the intensity of the external electric field can be reduced. As shown in FIG. 8, the MCF/PU tape increases the complex dielectric constant loss as the frequency increases, and thus the strength of the external electric field can be greatly reduced.

9 and 10, the complex permeability is expressed as a complex number, which is a real part µ'and an imaginary part µ″.

The complex permeability represents the degree to which magnetic polarization (N/S) occurs in a material in response to an external magnetic field, thereby forming a magnetic field, thereby reducing the intensity of the external magnetic field.

The complex magnetic permeability real part represents a reduced ratio in the medium of the external magnetic field, and the strength of the external magnetic field decreases as the magnetic field generated in the medium increases.

If a material with a large complex permeability imaginary part is used, it acts as a resistance element and absorbs unnecessary noise.

The complex permeability loss shown in FIG. 11 is calculated as (complex permeability imaginary part (μ″)/complex permeability real part (μ′)). An electromagnetic wave absorption occurs when the double magnetic permeability loss is 1 or more.

As shown in FIG. 11, the MCF/PU tape has a large loss of complex permeability (10 or more) due to the magnetic Ni coated on the surface. For this reason, MCF/PU tape can greatly reduce the magnetic field strength among electromagnetic waves.

As shown in FIG. 12, the shielding performance of the MCF/PU tape having the complex dielectric constant and the complex permeability described above was compared with the CF/PU tape and the Cu/PS tape and summarized in a table.

As shown in FIG. 12, it can be seen that the shielding performance of the MCF/PU tape is not significantly different from the shielding performance of the Cu/PS tape.

When the above-described method of controlling the electromagnetic properties of the metal-coated carbon fiber is used, in addition to the electromagnetic wave shielding material, the electromagnetic properties of the metal-coated carbon fiber can be precisely controlled according to the fields of use, such as heating wires and sensors.

Claims (5)

delete delete A first step of selecting the type of metal to be coated on the carbon fiber and a coating method; And
A second step of coating a metal on the carbon fiber according to the selected metal type and coating method, but making the shape of the metal coated on the carbon fiber into a set shape, and coating it,
In the first step,
The metal to be coated on the carbon fiber is silver, and the silver is coated on the carbon fiber by a sputtering method,
In the second step,
The electron of the metal-coated carbon fiber, characterized in that by controlling the sputtering time of the silver on the carbon fiber, the silver is coated on the carbon fiber in a round grain shape, or in a cylindrical shape covering all the outer peripheral surfaces of the carbon fiber How to control miracle properties. delete A first step of selecting the type of metal to be coated on the carbon fiber and a coating method; And
A second step of coating a metal on the carbon fiber according to the selected metal type and coating method, but making the shape of the metal coated on the carbon fiber into a set shape, and coating it,
In the first step,
The metal to be coated on the carbon fiber is nickel, and the nickel is coated on the carbon fiber by sputtering electroless plating,
In the second step,
By controlling the electroless plating time of the nickel on the carbon fiber, the nickel is coated on the carbon fiber in a round grain shape, a polygonal shape, or an elliptical shape. How to control electromagnetic properties.

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