KR20130060898A - Shield film of electromagnetic wave - Google Patents

Abstract

PURPOSE: An electromagnetic wave shield film is provided to effectively shield harmful electromagnetic waves since the electromagnetic wave shield film is capable of shielding a magnetic component as well as an electric component of the electromagnetic waves. CONSTITUTION: An electromagnetic wave absorber covering layer(4) is formed on a ground sheet layer(2). The electromagnetic wave absorber covering layer is formed of a soft magnetic alloy of 3 elements or 5 elements. A protection layer(6) is formed on the electromagnetic wave absorber covering layer. A bonding layer(10) is formed on the lower surface of the ground sheet layer. A release paper(11) is attached on the bonding layer.

Description

Electromagnetic shielding film {SHIELD FILM OF ELECTROMAGNETIC WAVE}

The present invention relates to electromagnetic shielding in electronic devices, and more particularly, to an improvement of an electromagnetic shielding film for improving electromagnetic shielding.

Normally, harmful electromagnetic waves are set to 150KHz or higher, and the International Cancer Research Institute (IARC) under the World Health Organization (WHO) classifies mobile phone use as a case of 'cancer'. It came to presentation.

At present, the regulation range using electromagnetic waves around the world is generally in the range of 30KHz to 300GHz. The KHz band is mainly used for aircraft, ships, AM broadcasting, etc., the MHz band is used for FM broadcasting, TV, mobile phones, etc., and the GHz band is mainly used for satellite broadcasting, wireless LAN, smart phones, and next-generation mobile terminals.

As the frequency of use of electromagnetic waves moves from KHz band to MHz band and GHz band these days, the wavelength of signal is getting shorter, so the environment similar to the frequency wavelength used in circuits in portable electronic devices such as mobile phones is created. Due to the interference of unnecessary electromagnetic waves applied, the inherent operation quality of the device may be degraded, and harmful electromagnetic waves generated inside portable electronic devices may affect the human body.

Since harmful electromagnetic waves generated from portable electronic devices, especially mobile phones, may adversely affect the human body, various electromagnetic shielding materials are used to shield the harmful electromagnetic waves.

A representative example of the shielding scale is a shielding effect, which refers to the degree to which noise passes through the shielding material and decreases in strength, and the unit is dB.

The formula for shielding effect (SE) is SE = 20 log (Et / Ei).

Here, 'SE' is a shielding effect, 'Ei' is an electric field of incident electromagnetic waves, and 'Et' is an electric field of electromagnetic waves transmitted through the shielding material.

In the result of shielding effect, 10 ~ 30dB means minimum shielding effect, 30 ~ 60dB means shielding effect, and 60 ~ 90dB means high shielding effect. And, more than 90dB indicates the highest level of shielding effect.

A common way of shielding electromagnetic waves is electromagnetic reflection.

In the electromagnetic shielding shielding material, a movable charge carrier must exist to reflect the electromagnetic wave, so that the conductive material may be a shielding material. Since the higher the conductivity, the higher the electromagnetic wave reflection effect, a material having high electrical conductivity such as silver, copper, gold, and aluminum is used as the conductive material used for electromagnetic wave reflection. In addition, a highly conductive carbon material such as graphite sheet, graphene, and carbon nano-tute (CNT) may be used.

Most common electromagnetic shielding products form thin films or sheets of conductive materials for reflecting electromagnetic waves such as silver, copper, gold, aluminum, and carbon. These electromagnetic shielding products are effective in the electric field of electromagnetic waves but have a magnetic field. Is vulnerable.

Since electromagnetic and magnetic fields always exist in the electromagnetic waves, the electromagnetic wave must be blocked only by blocking both the magnetic field component as well as the magnetic field component.

However, the shielding material that effectively blocks all the electromagnetic fields in the portable electronic device has not been developed yet, so improvement is required.

Accordingly, an object of the present invention is to provide an electromagnetic shielding film that can effectively shield the electromagnetic wave of the electronic device by blocking all the electric field components and magnetic field components as much as possible.

According to the above object, the present invention, in the electromagnetic wave shielding film, the soft magnetic electromagnetic wave absorber film layer and the protective film layer of the electromagnetic wave absorbing material is formed on the base sheet layer in order to form a film, the electromagnetic wave absorbing material is absorption loss compared to copper The soft magnetic alloy having 100 to 10,000 is composed of one of three to five element alloy materials to increase the electrical conductivity and magnetic permeability at the same time to maximize the absorption of electromagnetic waves, characterized in that the energy loss of electromagnetic waves is large.

The present invention has the advantage of effectively blocking harmful electromagnetic waves by shielding not only the electric field component of the electromagnetic wave but also the magnetic field component of the electromagnetic wave in the electronic device to be extinguished by the absorption method rather than reflecting the electromagnetic wave in implementing the electromagnetic shielding film.

1 is a cross-sectional configuration of an electromagnetic shielding film according to an embodiment of the present invention,
2 and 3 are views illustrating a modification of the electromagnetic shielding film of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, in implementing the electromagnetic wave shielding film, the electromagnetic wave shielding mechanism is not dedicated to the conventional electromagnetic wave reflection method but absorbs and disappears the electromagnetic wave by the electromagnetic wave absorption method.

In order to absorb harmful electromagnetic waves, an electric dipole or magnetic dipole must be present in the shielding material. These dipoles interact with the electromagnetic fields of electromagnetic waves to absorb energy and convert it into thermal energy. That is, when an electromagnetic field is applied from the outside, fine electric and magnetic dipoles that are disorderly distributed inside the material are aligned with the direction of the electromagnetic field. The alignment of the fine polarizations within the material does not keep up with the rate of change of the electromagnetic field. As a result, hysteresis occurs in which time delay occurs between the external electromagnetic field and the polarization induced in the material. The hysteresis phenomenon converts and dissipates electromagnetic energy into thermal energy.

The absorbing effect of the electromagnetic wave is greater as the energy loss lost while the electromagnetic wave passes through the shielding material.

Absorption loss (Absorption Loss) indicating the absorption effect of the electromagnetic wave is represented by the following equation (1).

Where σ is the electrical conductivity and μ is the magnetic permeability

As can be seen from the 'electromagnetic wave absorption loss' shown in Equation 1, superior electromagnetic wave absorption is possible only when the shielding material has high electrical conductivity and magnetic permeability.

However, almost all the units have a low self-permeability when the electrical conductivity is high, and conversely, when the high self-permeability, the electrical conductivity is low.

Therefore, in the present invention, the electromagnetic wave shielding film is implemented as an electromagnetic wave absorber made of an alloy material of three to five element alloys in order to solve such a conflict, thereby simultaneously increasing the electrical conductivity and magnetic permeability to maximize the electromagnetic wave absorption effect. To do.

Alloy materials with excellent electromagnetic wave absorption loss include mumetal, super permallay, supermallay, and conetic.

Of the alloy materials with excellent electromagnetic wave absorption loss, three-element alloys (such as mumetals) are more effective but have lower absorption rates than quaternary alloys (such as superpermalloy). Therefore, it is more preferable that a four-element alloy becomes the material of the electromagnetic wave shielding film of this invention, and a five-element alloy can also be used as needed in order to acquire a strong electromagnetic wave absorption rate.

The inventors of the present inventors observed and examined the data, it was confirmed that the absorption loss is increased while the electromagnetic wave decreases as the frequency increases. Therefore, the higher the frequency of the electromagnetic pile will improve the performance of the electromagnetic shielding film of the present invention.

The frequency used in portable electronic devices such as mobile phones is gradually increasing to 1GHz, 1.8GHz, and 2.2GHz bands as smartphones emerge in the 800MHz band. Therefore, the electromagnetic wave absorbing electromagnetic shielding film of the present invention will be more useful for shielding electromagnetic waves in portable electronic devices, such as high frequency band.

). 즉 상기 실효두께(δ)는 주파수(f), 자기투자율(μ), 전기전도도(σ) 등의 값이 커짐에 따라 감소하게 되는 것이다. The electromagnetic field strength of electromagnetic waves decreases exponentially with the depth penetrated into the epidermal layer of the conductor. The thickness of the skin layer where the value of electromagnetic field strength decreases by 1 / e times is called the "effective thickness (δ)", and the effective thickness (δ) is inversely proportional to the square root of frequency (f), magnetic permeability (μ), electrical conductivity (σ), and the like. In a relationship

). That is, the effective thickness δ decreases as the values of the frequency f, the magnetic permeability μ, and the electrical conductivity σ become larger.

Knowing the electrical conductivity (σ) and the magnetic permeability (μ), as shown in Equation 1 above, the electromagnetic wave absorption loss can be calculated, and also the electromagnetic wave reflection loss can be calculated.

Electromagnetic return loss is as shown in [Equation 2].

Table 1 shows the relationship between the electrical conductivity (σr), magnetic permeability (μr), electromagnetic wave absorption loss, and electromagnetic wave reflection loss of other metal materials compared to copper.

Metal material Electrical conductivity
[σr] Self-permeability
[μr] Absorption loss
σr × μr Return loss
σr / μr silver 1.05 One 1.05 1.05 Copper One One One One gold 0.7 One 0.7 0.7 aluminum 0.61 One 0.61 0.61 Brass 0.26 One 0.26 0.26 Bronze 0.18 One 0.18 0.18 Tin 0.15 One 0.15 0.15 Lead 0.08 One 0.08 0.08 nickel 0.2 100 20 2 x E-3 Stainless steel # 430 0.02 500 10 4 x E-5 Mumetal (at 1KHz) 0.03 20,000 600 1.5 × E-6 Supermalloy (at 1KHz) 0.03 100,000 3,000 3 x E-7

When the incident frequency is 1 GHz, the effective thickness δ of copper is 2.09 m, and the effective thickness δ of nickel is 0.47 m. Copper having higher conductivity has a larger effective thickness (δ) than nickel because copper has a relatively low magnetic permeability (μr) than nickel. Referring to Table 1, the magnetic permeability (μr) of copper is "1" and the magnetic permeability (μr) of nickel is "100", and it can be seen that copper has a much lower magnetic permeability than nickel.

Applicants have confirmed that among the alloys, mumetal, conetic, super permalloy, supermalloy, HITPERM, FINEMET ^® , metalglass, Hi-Mu80 ^® , Conetic AA and the like have a high absorption loss, that is, a material having an absorption loss in the range of 100 to 10,000 compared to copper, and is a soft magnetic alloy material.

Moreover, it is more preferable to form a soft magnetic alloy having a magnetic permeability of 20,000 or more, which is one of the parameters related to the absorption loss (electric conductivity and magnetic permeability), among the three-, four-, and five-element alloys, in which the absorption loss is in the range of 100 to 10,000 compared to copper. Good.

Among the soft magnetic alloy materials having excellent absorption loss, the three-element alloy materials include supermalloy and mumetal, and the four-element alloy materials include Hi-Mu80 ^® , super permalloy, and conetic. Among the soft magnetic alloy materials having excellent absorption loss, the five-element alloy materials include HITPERM, FINEMET ^® , metalglass, and cone AA.

The mainstream elements of the three- and four-element alloys are nickel (Ni), the next element is iron (Fe), and the rest are Cu, Mo, Si, Cr, Mn, and the like.

The main element of the five-element alloy is nickel (Ni), and iron (Fe) may be used instead of nickel, and in some cases, cobalt (Co) is also used.

Examples of the three-element, four-element, and five-element alloys having excellent absorption loss employed in the present invention and the preferred optimum element alloy ratios applied to the electromagnetic wave shielding film of the present invention are as follows.

* Example of three element alloy

Mumetal: Ni 75%, Fe 20%, Cu 5%

* Example of 4-element alloy

Hi-Mu80 ^® : Ni 80%, Fe 15.5%, Mo 4%, Mn 0.5%

Super permalloy: 74% Ni, 16% Fe, 6% Cr, 4% Si

Conetic: 77% Ni, 14% Fe, 5% Cu, 4% Mo

* Example of 5 Elemental Alloy

HITPERM: Fe 62%, Co 26%, Zr 7%, B 4%, Cu 1%

-FINEMET ^® : Fe 73.5%, Si 13.5%, B 9%, Nb 3%, Cu 1%

Metal glass: Co 65%, Fe 14%, Ni 2%, Si 15%, B 4%

Conetic AA: Ni 80%, Fe 15%, Mo 4.2%, Mn 0.5%, Si 0.3%

As the soft magnetic alloy of three to five elements used in the present invention can be seen in the above example, Ni or Fe is essentially included, and Mo, Cu, Mn, and Si may be selectively included to control absorption loss. Ni and Fe occupy the main ratio range, and Mo, Cu, Mn and Si occupy the minority ratio range.

The alloys are materials having a high absorption loss, and among them, the best absorption loss is, as shown in Table 1, the supermalloy. In addition, the absorption loss of the supermalloy having similar characteristics to that of the supermalloy is good.

Therefore, the soft magnetic alloys are effective for shielding electromagnetic waves of portable electronic devices, especially portable electronic devices operating in the GHz band. The super magnetic alloy having the best electromagnetic absorption loss (3,000 electromagnetic wave absorption loss) or the supermalloy material shields electromagnetic waves. Is preferred.

The best electromagnetic wave absorber film for implementing the shielding film of the present invention is a super elemental alloy of 40 to 85% Ni, 16 to 60% Fe, 6% Cr and 4% Si as a four-element alloy. Can be mentioned.

In addition, considering the effective thickness and reflection loss, a soft magnetic material containing a copper component such as mumetal may also be used for electromagnetic shielding. This is because soft magnetic materials not only have magnetic dipoles but also some electric dipoles, so that the copper component may contribute to the electromagnetic wave reflection loss.

1 is a cross-sectional configuration diagram of an electromagnetic wave shielding film 100 according to an exemplary embodiment of the present invention, and the electromagnetic wave absorber coating layer 4 of the alloy material is formed on the base sheet layer 2, and the electromagnetic wave absorber coating layer 4 is formed. The protective film layer 6 which consists of a protective film, a coating layer, etc. is formed on it.

In FIG. 1, the electromagnetic wave shielding film 100 of the present invention may be completed by selectively forming an adhesive layer 10 on the bottom of the base sheet layer 2, and if necessary, as shown in FIG. 3. The heat dissipation layer 8 may be selectively formed on the?

In addition, the heat dissipation layer 8 and the adhesive layer 10 shown in FIG. 3 may alternate positions of formation.

Figure 2 also shows a modified example of the electromagnetic wave shielding film 100 of the present invention, in Figure 2, the protective layer 6 of Figure 1 is not formed, and the selectable heat dissipation layer 8 is also not formed, the base The adhesive layer 10 having the release paper 11 is formed on the absorber coating layer 4 formed on one surface of the sheet layer 2.

In the electromagnetic shielding film 100, the material of the base sheet layer 2 may be a polyester film, polyethylene terephthalate (PET), polyethylenenaphthalate (PEN), polyimide (PI) film, etc. Can be used as

As the most preferable electromagnetic wave shielding film 100 of the present invention, a soft magnetic electromagnetic wave absorber coating layer 4 and a protective film layer 6 of electromagnetic wave absorbing material are formed on the base sheet layer 2, but the electromagnetic wave absorbing material is Soft magnetic alloys with absorption loss of 100 to 10,000 compared to copper, consisting of super elemental alloy superpermalloy with 40 to 85% Ni, 16 to 60% Fe, 6% Cr and 4% Si. Can be.

According to the embodiment of the present invention, the sputtering deposition method or the ion beam deposition method is advantageous for the formation of the electromagnetic wave absorber coating layer 4 made of three to five element soft magnetic alloys. Sputtering deposition is advantageous for the electromagnetic wave absorber made of a three-element or four-element alloy, and ion beam deposition is advantageous for the electromagnetic wave absorber made of the five-element alloy.

The film formation of the electromagnetic wave absorber coating layer 4 may be performed by a metal deposition method, an electroless plating method, other coating methods, or equivalent methods other than sputter deposition and ion beam deposition depending on the material properties and needs.

The protective film layer 6 formed on the electromagnetic wave absorber coating layer 4 may be used as a urethane material or the like, and may be finished with another protective film or a protective coating or carbon fiber.

The heat dissipation layer 8 selectively formed on the protective film layer 6 is used for dissipating heat generated from the main body device, that is, for heat dissipation. The heat dissipation layer 8 is formed of a heat dissipating sponge, metal fiber, metal foam, and carbon. It can be mounted in fiber form.

A release paper 11 is formed on the adhesive layer 10 formed on the bottom surface of the base sheet layer 2 to remove the release paper 11 and attach the electromagnetic shielding film 100 of the present invention to a place desired by the user. have.

On the other hand, as a modification of the present invention, an electromagnetic wave reflector coating layer may be further formed by coating aluminum or copper having an electromagnetic wave reflector function between the base sheet layer 2 and the electromagnetic wave absorber coating layer 4 to include an electromagnetic wave reflecting function. . The electromagnetic wave reflector coating layer may be made of aluminum, copper, nickel, or carbon material, and may be made of gold or silver having a relatively high price but excellent conductivity.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. Therefore, the scope of the present invention should not be limited by the described embodiments, but should be determined by the scope of claims and equivalents thereof.

The present invention can be used for electromagnetic shielding in portable electronic devices.

(2)-Base sheet layer (4)-Electromagnetic wave absorber coating layer
(6)-passivation layer (8)-heat dissipation layer
(10)-Adhesive layer (11)-Release paper
(100)-Electromagnetic shielding film

Claims (8)

In the electromagnetic shielding film,
A soft magnetic electromagnetic wave absorber coating layer and a protective film layer made of an electromagnetic wave absorbing material are formed on the base sheet layer. Electromagnetic shielding film, characterized in that composed of one of the element alloy material.
The electromagnetic shielding film of claim 2, wherein the magnetic permeability associated with the absorption loss of the three-, four-, and five-element alloys is formed of a soft magnetic alloy of 20,000 or more.
The electromagnetic shielding film of claim 2, wherein the four-element alloy material comprises Hi-Mu80 ^® , super permalloy, and conetic.
3. The electromagnetic shielding film of claim 2, wherein the three-element alloy material comprises mumetal.
The electromagnetic shielding film of claim 2, wherein the five-element alloy material comprises HITPERM, FINEMET ^® , metalglass, and cone AA.
In the electromagnetic shielding film,
A soft magnetic electromagnetic wave absorber coating layer and a protective film layer made of an electromagnetic wave absorbing material are formed on the base sheet layer. Electromagnetic shielding film, characterized by consisting of a four-element alloy super permalloy consisting of 16-60%, Cr <6%, Si <4%.
The method according to any one of claims 1 to 5, wherein one surface of the electromagnetic shielding film is selectively formed of one of the heat radiation layer and the adhesive layer, the other surface of the electromagnetic shielding film is selectively formed on the other surface of the electromagnetic shielding film Electromagnetic shielding film, characterized in that configured to be.
In the electromagnetic shielding film,
On the base sheet layer, a soft magnetic electromagnetic wave absorber coating layer made of an electromagnetic wave absorbing material and an adhesive layer are formed. Electromagnetic shielding film, characterized in that composed of a soft magnetic alloy of one of the materials and the magnetic permeability related to the absorption loss is 20,000 or more.

Images