KR20070010428A - Complex sheet for shielding electromagnetic wave of mobile phone and manufacturing method for the same - Google Patents

Abstract

A complex sheet for a shielding electromagnetic wave of a mobile phone and a manufacturing method therefor are provided to improve a transceiving sensitivity by efficiently shielding an unnecessary electromagnetic wave for transceiving a mobile phone. In a complex sheet for shielding an electromagnetic wave of a mobile phone, a sheet-formed conductor(100) plays a role of changing an incident electromagnetic wave into a current. And, a sheet-formed absorber(110) plays a role of absorbing the incident electromagnetic wave by a dielectric polarization of a ferrite with being stacked on the sheet-formed conductor(100).

Description

Complex sheet for shielding electromagnetic wave of mobile phone and manufacturing method for the same}

1 is a perspective view showing a composite sheet for shielding electromagnetic wave of a mobile phone according to an embodiment of the present invention.

2A and 2B are diagrams for explaining how the composite sheet of FIG. 1 is actually used in a mobile phone.

3A to 3D are cross-sectional views illustrating a method of manufacturing the composite sheet for shielding electric wave of a mobile phone according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100: conductor 110: absorber

300: coating liquid 310: spray injector

320: flat surface

The present invention relates to an electromagnetic shielding composite sheet and a method for manufacturing the same, and more particularly, to a composite sheet for shielding mobile phone electromagnetic waves and a method of manufacturing the same.

Electromagnetic wave is a form of energy generated by the use of electricity, and is a synthesized wave of an electric field and a magnetic field.

These electromagnetic waves are classified into γ-ray (gamma ray), X-ray, ultraviolet ray, visible light (light), infrared ray, radio wave (ultra high frequency, high frequency, low frequency, ultra low frequency), microwave in order of high frequency. Can be. In other words, radio waves are a kind of electromagnetic waves, whose frequency is less than 3000 GHz (three trillion vibrations per second), and have become indispensable in daily life.

In particular, recently, mobile devices such as mobile phones emit a large amount of electromagnetic waves in the form of radio waves for communication with a base station through an antenna and a main body mounted inside the device. Although controversial, it is a general opinion that it is harmful to the human body.

The criteria for the effect of electromagnetic waves on the human body is the Specific Absorption Rate (SAR), that is, the degree to which the human body absorbs electromagnetic waves per unit mass (W / kg). As a result, countries have regulated that the absorption rate of electromagnetic waves in the human head does not exceed the standard.

In particular, in 1998, the Federal Communications Commission (FCC) enacted the regulation of electromagnetic wave effects on mobile phones, and has now regulated and enforced regulations in many countries around the world, including Korea. SAR limit of 1.6W / kg in Europe and 2.0W / kg in Europe and Japan)

The path from which electromagnetic waves are emitted from the mobile phone may be through the mobile phone body, but most harmful electromagnetic waves are radiated through an antenna formed on the top of the mobile phone body. Therefore, as the direct exposure of the human body to the antenna formed on the outside of the mobile phone body decreases, the electromagnetic wave absorption rate decreases.

However, in the case of a slide type mobile phone, which has appeared as a fold type follow-up design, the LCD display unit and the cover part which is pushed up during the call are covered with the antenna more significantly than the conventional folding type mobile phone. The less the antenna of the mobile phone is covered, the more the electromagnetic radiation emitted by the antenna is absorbed by the human body, resulting in an increase in the electromagnetic wave absorption rate.

In addition, flexible copper clad laminates (FCCLs) are used in all mobile phones. In the case of a slider type mobile phone, a relatively long copper clad flexible film is used compared to a clamshell mobile phone. . Since the copper-clad flexible film is used as a circuit board, a metal wire is disposed therein, and since such a wire acts as an antenna, it may radiate unnecessary electromagnetic waves that impede transmission and reception of a mobile phone. have.

Therefore, in order to reduce electromagnetic waves caused by external antenna radiation in the slide phone, a mobile phone having an antenna formed inside the main body of the mobile phone has been recently developed, but the mobile phone has been developed. There is a problem that the reception rate is lower than that of a cell phone having an antenna.

Therefore, while the external shape of the slide-type mobile phone can be taken similarly to the current method, more research is needed on how to effectively shield electromagnetic waves emitted from the mobile phone.

The technical problem to be achieved by the present invention is to reduce the electromagnetic wave absorption rate by shielding the electromagnetic radiation emitted from the external antenna in the slide-type mobile phone, shielding the unnecessary electromagnetic radiation emitted from the copper clad laminated film used as the circuit board of the mobile phone An object of the present invention is to provide a composite sheet for shielding electromagnetic waves of a mobile phone, which can eliminate reception disturbances.

Another object of the present invention is to provide a method for manufacturing a composite sheet for shielding electromagnetic wave of a mobile phone according to the present invention.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

The composite sheet for shielding electromagnetic wave of a mobile phone according to an embodiment of the present invention for solving the above technical problem is a sheet-like conductor that functions to change the incident electromagnetic wave into a current, and the electromagnetic wave stacked on the conductor It includes a sheet-shaped absorbent that functions to absorb by the dielectric polarization of ferrite.

Method for manufacturing a composite sheet for shielding electromagnetic wave of a mobile phone according to an embodiment of the present invention for solving the above other technical problem is (a) 20 to 60% by weight conductive metal powder, 5 to 20% by weight binder, 10 to 30% by weight solvent Preparing a coating liquid comprising%, and a mesh type electromagnetic wave absorber in which 50 to 95% by weight of ferritic metal powder is dispersed in a polymer resin or silicon having 5 to 50% by weight, (b) spraying the coating liquid on a flat surface And drying to form a sheet-shaped conductor, and (c) adhering the mesh type electromagnetic wave absorber onto the dried conductor.

Specific details of other embodiments are included in the detailed description and the accompanying drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, only the present embodiments to make the disclosure of the present invention complete, and common knowledge in the art to which the present invention pertains. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

In addition, in the drawings, the size and thickness of layers and films or regions are exaggerated for clarity of description, and when any film or layer is described as being formed "on" of another film or layer, It may be directly on top of the other film or layer, and a third other film or layer may be interposed therebetween.

1 is a perspective view showing a composite sheet for shielding electromagnetic wave of a mobile phone according to an embodiment of the present invention.

As shown in FIG. 1, the composite sheet for shielding electromagnetic wave of a mobile phone according to an exemplary embodiment of the present invention includes a conductor 100 and an absorber 110.

Conductor 100 is a conductive metal powder, such as silver (Ag) powder, silver-coated copper powder, metal powder containing at least one of silver-coated nickel powder is uniformly dispersed throughout the polymer resin or silicon to have a total conductivity. It may be in the form of a sheet or may be a thin metal film such as aluminum, copper, or nickel.

The specific gravity of the metal powder in the conductor 100 accounts for 20 to 60% by weight based on the total weight of the conductor 100 when the weight is given by weight.

In this case, the polymer resin used may be one of a polyurethane (specifically, water-dispersible polyurethane) resin and an acrylic resin.

When the electromagnetic wave (wave) is incident on the conductor 100, the conductor 100 changes in the form of a current on the surface of the conductor 100 so that it flows along the surface of the conductor 100 in the form of a conductive sheet to the outside of the current. By shielding the electromagnetic wave is shielded.

The absorber 110 is formed by adhesion or adhesion to the conductor 100 and functions to absorb incident electromagnetic waves by dielectric polarization of ferrite.

That is, the absorber 110 has a form in which a metal powder having a ferrite property is dispersed in a polymer resin such as a polyurethane resin or an acrylic resin or silicon, and a ferrite has a dielectric dipole present therein. The dielectric polarization is resisted in a certain form according to the electromagnetic waves, and the dielectric polarization changes the electromagnetic waves incident on the absorber 110 with the resistance heat generated while the dielectric polarization resists. (The electromagnetic waves appear to be absorbed by the absorber. )

The ferrite metal powder used to prepare the absorber 110 is an iron (Fe) powder, a sand alloy alloy powder, which is an iron alloy containing about 10% silicon and about 5% aluminum, and 35 to 80% nickel. A metal powder containing at least one of permalloy powder, nickel-zinc ferrite powder, and manganese-zinc ferrite powder containing a sufficient amount of nickel-iron alloy may be used.

The specific gravity of the metal powder having ferrite properties in the absorber 110 accounts for 50 to 95% by weight based on the weight%.

The conductor 100 and the absorber 110 described above are adhesion-laminated with each other by a predetermined pressure-sensitive adhesive.

2A and 2B are diagrams for explaining how the composite sheet 10 of FIG. 1 is actually used in a mobile phone.

The electromagnetic wave shielding composite sheet 10 according to the present invention is invented to shield electromagnetic waves in a mobile phone, especially a slide type mobile phone, and when used in a slide type mobile phone, a cover part of a slide mobile phone ( 200, namely, it is attached to the back side of the surface on which the LCD of the member on which the information display LCD is formed is used.

However, in order to attach the composite sheet according to the present invention to the slide-type mobile phone, a certain adhesive or adhesive should be placed between the mobile phone and the composite sheet.

In the case of adhering or adhering the composite sheet to the mobile phone, the conductive layer 100 may be in contact with the mobile phone as shown in FIG. 2A, and as shown in FIG. 2B, the absorbing layer (not shown on the absorbing layer is shown on FIG. 2B). The same effect can be obtained by contacting the mobile phone can be seen with reference to the experimental examples to be described later.

3A to 3D are cross-sectional views illustrating a method of manufacturing the composite sheet 10 for shielding electric wave of a mobile phone according to the present invention.

In order to manufacture the composite sheet 10 for shielding electromagnetic wave of a mobile phone according to the present invention, first, as shown in FIG. 3a, a coating liquid 300 for manufacturing a conductor and an electromagnetic wave absorber 110 in a sheet form are prepared.

The coating solution 300 is prepared in the form of an emulsion or paste having a constant viscosity or fluidity, and specific components and contents thereof are 20 to 60 wt% of the conductive metal powder, 5 to 20 wt% of the binder, and 10 to solvent. 30 weight percent. In addition, the coating solution 300 may further include an additive such as a plasticizer or a surfactant.

The metal powder used in the preparation of the coating liquid 300 includes at least one of silver powder, silver coated copper powder, and silver coated nickel powder, and the binder is polyurethane (preferably water-based polyurethane), acrylic It consists of one of resin, melamine resin or silicone. In addition, one of alcohols, acetone, ether ether, normal methylpyrrolidone, and butyl cellussolve is used as a solvent used in the preparation of the coating solution 300.

The absorber 110 refers to the same member as the absorber 110 described above, and the detailed description thereof will be referred to the absorber 110 described above. Absorber 110 may be prepared in the form of a mesh (mesh) or plate, in the present invention, the absorber 110 in the form of a mesh is prepared.

Next, as shown in FIG. 3B, the coating liquid 300 is placed in the spray injector 310 and sprayed to have a uniform thickness on the flat surface 320.

The reason for using the spray injector 310 is to form a film having the same thickness in a relatively large area. Thereafter, as shown in FIG. 3C, most (about 80 to 95%) of the solvent is volatilized in the coating solution 300 coated on the flat surface 320, and the surface has a slight viscosity, thereby providing adhesion. Let dry until it is in condition. As a result, a conductor 100 in the form of a sheet having a predetermined thickness and adhesive force on the surface is formed.

Next, the absorber 110 prepared as shown in FIG. 3d is laminated in a manner of adhering onto the conductor 100 in the form of a viscous sheet on the surface.

The conductor 100 and the absorber 110 stacked in this way are dried until the solvent of the conductor 100 volatilizes and the viscosity of the surface disappears, and then the conductor 100 is adjusted to the size of the absorber 110. After cutting, the composite sheet for shielding electromagnetic waves of a mobile phone is completed.

Hereinafter, a concrete experimental example will be described that the reception rate of the cellular phone is actually improved when the composite sheet for shielding the electromagnetic wave of the cellular phone according to the embodiment of the present invention is actually applied to the slider type cellular phone. Details not described herein are omitted because they can be sufficiently inferred by those skilled in the art.

However, the scale used in this experiment was measured using a function of checking the antenna sensitivity or the reception state in a mobile phone called a debug screen. For reference, the higher the debug screen value, the lower the reception rate. Conversely, a lower debug screen value means a higher reception rate, typically 5 minutes in two places (place 1 and place 2), taking into account the fact that the debug screen value changes over time in the same place. 10 times or more were measured and the average value was measured, respectively.

In Table 1, Experimental Example 1 is a case of attaching the composite sheet of the present invention to the slide phone, but the surface of the conductor is attached to the mobile phone, Experimental Example 2 is attached to the slide sheet of the present invention, but the surface of the absorber Is attached to the mobile phone, Experimental Example 3 is a case where only the conductor is attached to the mobile phone, Experimental Example 4 displays the debug screen value when only the absorber is attached to the mobile phone.

As shown in Table 1, when only the conductor or the absorber is attached to the mobile phone as shown in Experimental Example 3 and Experimental Example 4, the reception rate tends not to be improved, but as shown in Experimental Example 1 and Experimental Example 2 When the embodiment of the present invention in which the absorber is in the form of a composite sheet is applied, it can be seen that the tendency of the screen debug value is lowered.

However, it can be seen that there is no significant difference in the results of Experimental Example 1 and Experimental Example 2 which contact surface of the absorber and the conductor has a beneficial effect.

 Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above embodiments but may be manufactured in various forms, and having ordinary skill in the art to which the present invention pertains. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

In addition, the composite sheet according to the embodiment of the present invention was mainly invented for use in a slide-type mobile phone, it will be apparent to those skilled in the art that the same effect can be obtained even when used in a flip-type or folding-type mobile phone.

According to the composite sheet for shielding electromagnetic wave of a mobile phone according to an embodiment of the present invention and a method of manufacturing the same, one or more of the following effects are present.

First, the electromagnetic wave absorption rate (SAR) of the human body can be lowered by effectively shielding the electromagnetic waves generated from the antenna of the mobile phone.

Second, it effectively improves the transmission and reception sensitivity of the mobile phone by effectively blocking the electromagnetic waves that are unnecessary for the transmission and reception of the mobile phone generated from the copper foil laminated flexible film used as a circuit board inside the mobile phone.

Claims (14)

A sheet-like conductor that functions to change the incident electromagnetic wave into a current; And A composite sheet for shielding a mobile phone electromagnetic wave, comprising a sheet-shaped absorber laminated on the conductor and absorbing incident electromagnetic waves by dielectric polarization of ferrite. The method of claim 1, The conductor is a composite sheet for electromagnetic shielding of a mobile phone, characterized in that the conductive metal powder is dispersed in a polymer resin or silicon or in the form of a metal thin film. The method of claim 1, The absorber is a composite sheet for electromagnetic shielding of the mobile phone having a surface of the mesh pattern. The method of claim 1, The absorber is a composite sheet for shielding electromagnetic wave of a mobile phone, characterized in that the ferrite metal powder is dispersed in a polymer resin or silicon. The method of claim 2, The metal powder is a composite sheet for electromagnetic shielding of mobile phones, characterized in that it comprises at least one of silver powder, silver coated copper powder, silver coated nickel powder. The method of claim 4, wherein Metal powder having a ferrite property is a composite sheet for electromagnetic shielding of the mobile phone, characterized in that it comprises at least one of iron (Fe) powder, sand dust alloy powder, permalloy powder, nickel-zinc ferrite powder, manganese-zinc ferrite powder. The method according to claim 2 or 4, The polymer resin is a composite sheet for electromagnetic shielding of the mobile phone, characterized in that one of polyurethane resin, acrylic resin. (a) 20 to 60% by weight of the conductive metal powder, 5 to 20% by weight of the binder, 10 to 30% by weight of the solvent, and 50 to 95% by weight of the ferritic metal powder have a polymer resin of 5 to 50% by weight. Or preparing a mesh type electromagnetic wave absorber dispersed in silicon; (b) spraying the coating solution on a flat surface and drying to prepare a conductor in the form of a sheet having an adhesive force on the surface; And (c) a method of manufacturing a composite sheet for shielding electromagnetic wave of a mobile phone, comprising the step of adhesively-laminating the mesh type electromagnetic wave absorber on the dried conductor. The method of claim 8, The coating solution and the mesh-type electromagnetic wave absorber further comprises an emulsifier or / and surfactant manufacturing method of the mobile phone electromagnetic wave shielding composite sheet. The method of claim 8, The conductive metal powder is a silver powder, a copper powder coated with silver, a method for manufacturing a composite sheet for shielding electromagnetic wave of a mobile phone, characterized in that it comprises one or more of silver coated nickel powder. The method of claim 8, Metal powder having a ferrite property of the composite sheet for shielding electromagnetic wave of the mobile phone, characterized in that it comprises at least one of iron (Fe) powder, sand dust alloy powder, permalloy powder, nickel-zinc ferrite powder, manganese-zinc ferrite powder Manufacturing method. The method of claim 8, The binder is a method of manufacturing a composite sheet for shielding electromagnetic wave of a mobile phone, characterized in that the polyurethane resin, acrylic resin, melamine resin, silicon. The method of claim 8, The solvent is a method for producing a composite sheet for shielding electromagnetic wave of a mobile phone, characterized in that one of alcohols, acetone, ether ether, normal methylpyrrolidone, butyl cellosolve. Cell phone comprising a composite sheet for shielding electromagnetic waves of claim 1.

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