1. Field of the Invention
The present invention relates to electromagnetic wave absorption components and devices, and particularly to electromagnetic wave absorption components and device that utilize a carbon nanocoil or carbon fiber as an electromagnetic wave absorption material.
2. Description of Related Art
An electronic device or apparatus derived by electric power generates electromagnetic waves during operation. Along with the consumer's increasing demands on efficiency of the electronic devices such as integrated circuits or mobile phones, operating frequency and signal frequency of the electronic devices such as clock frequency of microprocessors and carrier frequency in mobile communication systems have reached a level of gigahertz (GHz). However, neither the impedance at the input end nor the impedance at the output end of the electronic devices, such as microprocessors, can perfectly match, and thus generate the electromagnetic waves. The electromagnetic waves not only adversely affect the efficiency of the electronic devices but also possibly interfere with the operation of other electronic components. Particularly for precision integrated circuits or microprocessors, internal or external EMI (electromagnetic interference) may cause erroneous calculations and efficiency losses. Meanwhile, since the carrier frequency of mobile phones also reaches the level of GHz, subscribers who closely use mobile phones for a lengthy time are exposed to a high frequency electromagnetic wave environment which may cause deterioration of health.
Therefore, in recent years, there have been constantly developed various techniques for insulating or absorbing electromagnetic waves so as to reduce the adverse effects of the electromagnetic waves on human bodies or insulate electromagnetic waves from the surrounding environment. Currently, a microwave-absorbing foam is commonly used as an electromagnetic wave absorption material. Since it has the characteristics of a lighter weight, high electromagnetic wave absorption efficiency and effective shielding for interferences, it is widely applied in EMI shielding, electromagnetic wave insulation, noise suppression and for military purposes. In addition to preventing electromagnetic waves from interfering with the operation of electronic devices, the microwave-absorbing foam prevents the adverse effects of environmental electromagnetic waves from human bodies. However, the current products of PU microwave-absorbing foam in the market have a sponge-like open-pore structure which is moisture absorbent and thus is not applicable to an outdoor activity.
At present time, the most common method adopted in the industry for absorbing electromagnetic waves or suppressing noises involves adding various kinds of electrically conductive materials such as Cu, Ni, Zn or metallic compounds in the housing of electronic devices or apparatus, or coating a conductive layer through such as copper electroplating or sand blasting on the interior of the housing, or embedding a metal sheet on the inner side of the housing. However, such method increases the fabrication cost and results in an environmental problem.
A more advanced technique for absorbing electromagnetic waves or suppressing noises is achieved in the art by adding an electromagnetic wave absorption material to an insulation substrate. For example, Mn—Zn ferrite or Ni—Zn ferrite can be used as an electromagnetic wave absorption material and added to silicone gel, as disclosed by Japan Patent No. JP-A11-335472. However, such a method is only applicable in a low frequency range. Also, the ferrite material is easy to rust and thus is not suitable for long-term use. Further, Taiwan Patent Publication No. 143069 discloses the use of a BaTiO3 powder for electromagnetic wave absorption. Nevertheless, since there is a large difference between the weight of BaTiO3 and the substrate (such as plastic or rubber material), BaTiO3 cannot be uniformly distributed in the substrate. In this regard, the electromagnetic wave absorption effect is only locally decreased. Since the use of BaTiO3 requires an increased cost, it is not suitable as a candidate material that is cost-effective and has good electromagnetic wave absorption efficiency.
Therefore, it is desirable to provide electromagnetic wave absorption components that are cost-effective and of easy use in daily life and electronic devices, and meanwhile achieve good effects on suppressing noises or insulating harmful electromagnetic waves. However, the electromagnetic wave absorption and noise suppression techniques in the art cannot achieve the desired effect and cannot be widely applied to the level of daily life or large-scale industries.
Accordingly, there is a practical need to efficiently protect the precise electronic devices in operation from being interfered by external electromagnetic noises, insulate electromagnetic waves scattered out from the electronic devices, and selectively absorb or shield the electromagnetic waves harmful to human bodies.
In view of the above drawbacks, the present invention provides an electromagnetic wave absorption component that is capable of absorbing electromagnetic waves of specific frequencies and has low cost and high absorption efficiency.
According to the present invention, the electromagnetic wave absorption component comprises: an electromagnetic shield constituted by at least one material selected from the group consisting of a carbon nanocoil and a carbon fiber; and a solidified layer formed of a mixture of a solidifiable material and the electromagnetic shield after solidification.
The present invention further provides an electromagnetic wave absorption device, which is formed by stacking at least two such electromagnetic wave absorption components, wherein the stacking is by way of depositing on a solidified layer of a first electromagnetic wave absorption component a mixture of a solidifiable material and an electromagnetic shield before solidification and solidifying the material so as to form a second electromagnetic wave absorption component stacked on the first electromagnetic wave absorption component.
According to another embodiment of the present invention, the electromagnetic wave absorption component comprises: an electromagnetic shield constituted by at least one material selected from the group consisting of a carbon nanocoil and a carbon fiber; and a solidified layer formed by solidifying a solidifiable material and for encapsulating the electromagnetic shield.
The electromagnetic wave absorption components and device according to the present invention can not only absorb electromagnetic waves of specific frequencies, but also enhance the electromagnetic wave absorption effect through the stacked structure. The solidified layer can be applied to a variety of daily applications and electronic industries, so as to protect the precise electronic devices in operation against external electromagnetic noises, insulate electromagnetic waves scattered out from the electronic devices and meanwhile selectively absorb or shield the electromagnetic waves harmful to human bodies or other organisms.
The following illustrative embodiments are provided to illustrate the disclosure of the present invention, these and other advantages and effects can be apparent to those skilled in the art after reading the disclosure of this specification.
In the present embodiment, the electromagnetic wave absorption component 100 comprises an electromagnetic shield 101 and a solidified layer 103, wherein the electromagnetic shield 101 is constituted by at least one of the group consisting of a carbon nanocoil (CNC) and a carbon fiber, and the solidified layer 103 is formed of a mixture of a solidifiable material and the electromagnetic shield 101 after solidification.
It should be noted that the composition of the electromagnetic wave absorption component 100 is not limited to the drawing. That is, although the electromagnetic shield 101 is granularly distributed in the solidified layer 103, the electromagnetic shield 101 can be mixed with the solidifiable material in any possible way to be fixed in the solidified layer 103 after the solidifiable material is solidified.
In the present embodiment, if the carbon nanocoil is used as the electromagnetic shield 101, the electromagnetic wave absorption efficiency of the electromagnetic wave absorption component 100 depends on the mass ratio of the carbon nanocoil to the solidifiable material in the solidified layer 103, the thickness of the solidified layer 103 and the average molecular length of the carbon nanocoil. For example, if a plurality of solidified layers 103 has the same thickness and the carbon nanocoils thereof have the same average molecular length, the electromagnetic wave absorption efficiency of the solidified layers 103 depends on the mass ratio of the carbon nanocoil to the solidifiable material. Similarly, if the solidified layers 103 have the same thickness and the same mass ratio of the carbon nanocoil to the solidifiable material, the electromagnetic wave absorption efficiency of the solidified layers 103 depends on the average molecular length of the respective carbon nanocoils of the solidified layers 103. In addition, if the solidified layers 103 have the same mass ratio of the carbon nanocoil to the solidifiable material and the carbon nanocoils thereof have the same average molecular length, the electromagnetic wave absorption efficiency of the solidified layers 103 is proportional to the thickness of the solidified layers 103.
The above-mentioned molecular length of a carbon nanocoil varies according to the growth time of the carbon nanocoil. In general, a carbon nanocoil with longer growth time has longer average molecular length. The electromagnetic wave absorption effect achieved through carbon nanocoils of different molecular lengths will be described later. In the present embodiment, the electromagnetic shield 101 and the solidifiable material are uniformly mixed and solidified to form the solidified layer 103. The solidifiable material is polydimethyl siloxane (PDMS). By using polydimethyl siloxane as the solidifiable material, the electromagnetic shield 101 can be mixed with polydimethyl siloxane as a mixture, and after polydimethyl siloxane is solidified, the electromagnetic shield can be fixed in the solidified polydimethyl siloxane. As a result, the electromagnetic shield 101 can be easily fixed to a substrate requiring electromagnetic wave absorption or noise suppression. The electromagnetic wave absorption component 100 can be attached to the substrate through a tape that is disposed on a surface of the solidified layer 103 of the electromagnetic wave absorption component 100.
On the other hand, if the carbon fiber is used as the electromagnetic shield 101, the electromagnetic wave absorption efficiency of the electromagnetic wave absorption component 100 depends on the mass ratio of the carbon fiber to the solidifiable material in the solidified layer 101 and the thickness of the solidified layer 101.
The application environment of the electromagnetic wave absorption component 100 is not limited to
As shown in
Same as the electromagnetic shield 101 of
In the present embodiment, if the carbon nanocoil is used as the electromagnetic shield 201, the electromagnetic wave absorption efficiency of the electromagnetic wave absorption component 200 depends on the thickness of the electromagnetic shield 201 formed of the carbon nanocoil and the average molecular length of the carbon nanocoil. For example, the electromagnetic wave absorption efficiency of two electromagnetic shields 201 having the same thickness depends on the average molecular length of the respective carbon nanocoils of the electromagnetic shields 201. Similarly, if the carbon nanocoils of the electromagnetic shields 201 have the same average molecular length, the electromagnetic wave absorption efficiency of the electromagnetic shields 201 is proportional to the respective thickness of the electromagnetic shields 201.
On the other hand, if a material of carbon fiber is used as the electromagnetic shield 201, the electromagnetic wave absorption efficiency of the electromagnetic wave absorption component 200 only depends on the thickness of the electromagnetic shield 201 formed of the carbon fiber.
The application environment of the electromagnetic wave absorption component 200 is not limited to
In
As shown in
Next, as shown in
It should be noted that the bulges are not limited to the cone shape. Instead, they can have different shapes according to the practical need. As shown in
Therein, the stacking method involves depositing on the solidified layer of a first electromagnetic wave absorption component 502 a solidifiable material mixed with an electromagnetic shield and solidifying it so as to form a second electromagnetic wave absorption component 504 on the first electromagnetic wave absorption component 502. Subsequently, a third electromagnetic wave absorption component 506 is stacked on the second electromagnetic wave absorption component 504 using the same stacking method.
In the present embodiment, the first electromagnetic wave absorption component 502, the second electromagnetic wave absorption component 504 and the third electromagnetic wave absorption component 506 can respectively have different electromagnetic wave absorption efficiencies. For example, the electromagnetic shields of the electromagnetic wave absorption components 502, 504, 506 can have carbon nanocoils of different average molecular lengths such that the electromagnetic wave absorption components 502, 504, 506 obtain the maximum electromagnetic wave absorption values at different frequencies. Further, the electromagnetic wave absorption components 502, 504, 506 can have different mass ratios of the electromagnetic shield to the solidifiable material so as to obtain different maximum electromagnetic wave absorption values even at the same frequency.
Referring to
According to the present invention, at least one of a carbon nanocoil and a carbon fiber is encapsulated in a solidified layer, or a solidifiable material is mixed with at least one of a carbon nanocoil and a carbon fiber and solidified so as to reduce the cost and improve the electromagnetic wave absorption efficiency. Further, due to solidification of the solidifiable material, the electromagnetic wave absorption components and devices formed therefrom are applicable to various applications requiring insulation or absorption of electromagnetic waves.
The above-described descriptions of the detailed embodiments are only to illustrate the preferred implementation according to the present invention, and it is not to limit the scope of the present invention. Accordingly, all modifications and variations completed by those with ordinary skill in the art should fall within the scope of present invention defined by the appended claims.
Number | Date | Country | Kind |
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98132038 | Sep 2009 | TW | national |