KR20080033828A - Electromagnetic shielding filter, method for preparing the same and pdp filter comprising the same - Google Patents

Abstract

An electromagnetic shielding filter, a method for preparing the same, and a PDP(Plasma Display Panel) filter including the same are provided to shield an electromagnetic wave and improve a bright room contrast ratio. A method for preparing an electromagnetic shielding filter includes the steps of: applying a photosensitive film onto both surfaces of an Fe plate or an Fe alloy plate having a thickness of 110 to 190 micrometers; attaching and exposing masks to the both surfaces of the Fe plate or the Fe alloy plate coated with the photosensitive film; forming a pattern by removing an unexposed portion; forming a mesh layer having a line width of 5 to 55 micrometers, a horizontal pitch(33) of 1500 to 2000 micrometers, a vertical pitch(34) of 120 to 180 micrometers, and an aperture ratio of 70% or higher by etching an exposed portion with an etching liquid; and forming a transparent layer in an top, a bottom, or top and bottom of the mesh layer.

Description

Electromagnetic shielding filter, manufacturing method thereof and plasma display panel filter including the same {Electromagnetic shielding filter, method for preparing the same and PDP filter comprising the same}

1 is a plan view showing the structure of the electromagnetic wave shielding filter according to the prior art.

FIG. 2 is a cross-sectional view of the electromagnetic wave shielding filter illustrated in FIG. 1 taken along the line AA ′.

3 is a graph showing the amount of electromagnetic waves emitted from the PDP for each frequency region.

4 is a plan view showing the structure of the electromagnetic shielding filter according to the present invention.

5 is a cross-sectional view of the electromagnetic wave shielding filter illustrated in FIG. 4 taken along the line AA ′.

6 is a cross-sectional view of an electromagnetic shielding filter according to another embodiment of the present invention.

7 is a schematic diagram of a PDP filter according to the present invention.

8 is a view comparing electromagnetic shielding ability of the electromagnetic shielding filter and the conventional Cu mesh type electromagnetic shielding filter according to the present invention.

9 is a graph showing the amount of electromagnetic waves emitted from the PDP for each frequency region after the electromagnetic wave shielding filter is mounted according to the present invention.

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

10: mesh 11: frame

12: upper blackening layer 13: lower blackening layer

20: base film 31: thickness

32: line width 32 ': upper line width

32 ": Lower line width 33: Horizontal pitch

34: longitudinal pitch 200: mesh layer

300: transparent layer 400: blackening layer

500: electromagnetic wave shielding filter 600: dye layer

700: antireflection layer

The present invention relates to an electromagnetic shielding filter, and more particularly, to an electromagnetic shielding filter having an excellent electromagnetic shielding ratio of a low frequency region of 230 MHz or less, a method of manufacturing the electromagnetic shielding filter, and a plasma display panel filter including the same.

In general, a plasma display panel (hereinafter referred to as a PDP) is discharged from a gas between electrodes by a direct current or an alternating voltage applied to the electrode, and emits light by exciting phosphors by radiation of ultraviolet rays. Compared to the CRT, it is possible to increase in size and thickness and to display various types of display capabilities such as display capacity, brightness, contrast, afterimage, viewing angle, etc., and thus it is in the spotlight as a next generation display device.

However, since PDP generates images by applying high voltage and high frequency for plasma discharge, it emits more electromagnetic waves and near infrared rays than color cathode rays or liquid crystal display devices. It may cause malfunction. Accordingly, in order to use such a PDP device, it is required to suppress the emission of electromagnetic waves and near infrared rays emitted from the PDP device to a predetermined value or less. In addition, the surface reflection of the phosphor is not only high, the color purity due to the orange light emitted from the encapsulated helium (He) or xenon (Xe) has a disadvantage that does not reach the cathode ray tube.

Therefore, in order to shield electromagnetic waves and near infrared rays while reducing reflected light and improving color purity, a PDP filter having functions such as electromagnetic shielding, near infrared shielding, light surface reflection prevention and / or color purity improvement is employed.

Among the PDP filters, in the early stage of PDP development, a transparent conductive film such as Ag multi-deposition filter satisfying an industrial level Class A (surface resistance <2.5 Ω / □) was widely used. As the demand surges, copper etched meshes that can satisfy class B (surface resistance <1.5 Ω / □) are widely used.

Figure 1 shows a conventional electromagnetic shielding filter of the mesh type. Such a mesh type electromagnetic wave shielding filter is typically coated with a polyethylene terephthalate base film 20 using an application roller, and then coated with a transparent adhesive of acrylic, urethane, polyester or epoxy resins, and then using a laminating roller. A Cu-based filter can be produced by laminating an electrolytic copper foil of about 10 m, and then can be produced by etching in the form of a frame 11 and a mesh 10 having a line width of 10 m and a pitch of 300 m using photolithography.

However, the electromagnetic shielding filter of the Cu mesh type has a problem that the manufacturing cost of the filter is increased because the raw material base film with the electrolytic copper foil is expensive, and the electromagnetic shielding rate is not high in the low frequency region of 230 MHz or less.

2 is a cross-sectional view of the electromagnetic shielding filter of FIG. 1 taken along the line A-A '. Since the copper mesh 10 has a metallic luster, the light emitted from the PDP display screen is reflected on the mesh. In order to solve the problem that the reflected screen is returned to the display screen or the external incident light is reflected, the visibility of the display screen is deteriorated. In general, the lower surface and the upper surface of the mesh are blackened (12, 13) or the black surface is blackened. In this blackening process, only the back side of the copper foil is first blackened, and then attached to the base film, and then a pattern is formed through etching, and the remaining front and side surfaces of the copper mesh must be blackened again. There was a problem of falling.

Accordingly, the first technical problem to be achieved by the present invention is to provide an electromagnetic shielding filter having excellent electromagnetic shielding ratio and low manufacturing yield in the low frequency region of 230 MHz or less.

The second technical problem to be achieved by the present invention is to provide a method for manufacturing the electromagnetic shielding filter.

The third technical problem to be achieved by the present invention is to provide a plasma display panel filter including the electromagnetic shielding filter.

The present invention to achieve the first technical problem,

A mesh layer of Fe or Fe alloy material having a thickness of 110 to 190 µm, a line width of 5 to 55 µm, a horizontal pitch of 1500 to 2000 µm, a vertical pitch of 120 to 180 µm, and an opening ratio of 70% or more; And a transparent layer stacked on the upper, lower, or upper and lower portions of the mesh layer and filling the voids of the mesh layer, and providing an electromagnetic shielding amount of 30 dB or more in a low frequency region of 230 MHz or less.

According to an embodiment of the present invention, the mesh of the mesh layer may be provided with a blackening layer on both the top, bottom and side surfaces.

In addition, the structure of the mesh may have a masonry masonry shape by forming a staggered mesh column in the center of the gap between the rows of the mesh in the transverse direction to filter the one gap.

According to another embodiment of the present invention, the upper, lower or upper and lower portions of the mesh layer may be further included one or more transparent layer filling the voids of the mesh layer.

According to another embodiment of the present invention, it is preferable that the lower line width is wider than the upper line width of the mesh.

According to a preferred embodiment of the present invention, the transparent layer may further include a near-infrared shielding dye, color correction dye or a mixture thereof.

The present invention to achieve the second technical problem,

(a) applying a photosensitive film on both sides of the Fe or Fe alloy plate having a thickness of 110 ~ 190㎛;

(b) attaching and exposing a mask on both sides of the Fe or Fe alloy plate coated with the photoresist;

(c) a developing step of forming a pattern by removing unexposed portions;

(d) etching the exposed portion with an etching solution to form a mesh layer having a line width of 5 to 55 µm, a horizontal pitch of 1500 to 2000 µm, a vertical pitch of 120 to 180 µm, and an opening ratio of 70% or more; ; And

(e) providing a method of manufacturing an electromagnetic shielding filter comprising forming a transparent layer on the upper, lower, or upper and lower portions of the mesh layer.

According to one embodiment of the present invention, after the step (d) may further comprise a step of blackening the Fe or Fe alloy plate on which the mesh is formed.

In addition, the line width of the upper pattern in step (c) may be narrower than the line width of the lower pattern.

The present invention to achieve the third technical problem,

It provides a plasma display panel filter including the electromagnetic shielding filter according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

The electromagnetic wave shielding filter according to the present invention is characterized in that the electromagnetic shielding ability of the low frequency region of 230MHz or less is excellent and the manufacturing yield is excellent since the blackening treatment can be performed simultaneously with the lower surface and the remaining surface.

3 shows the amount of electromagnetic waves emitted from the PDP for each frequency region. The electromagnetic wave in the low frequency region of 230 MHz or less is particularly problematic because the electromagnetic wave emitted from the image display portion of the PDP panel is mainly in the region of 230 MHz or less. Therefore, the tolerance of the emitted electromagnetic waves is generally 30 dB below 230 MHz and 37 dB in the high frequency region exceeding 230 MHz. In particular, electromagnetic waves in the 500 MHz region are known to have a very low shielding rate even when an electromagnetic shielding filter is installed. In the conventional Cu mesh type electromagnetic shielding filter, the electromagnetic shielding amount in the low frequency region of 230 MHz or less was not enough as 30 dB, but the electromagnetic shielding filter according to the present invention has excellent electromagnetic shielding ability because it has an electromagnetic shielding amount of 30 dB or more. (See Figure 9).

4 is a plan view of the electromagnetic shielding filter according to the present invention, and FIG. 5 is a cross-sectional view of the electromagnetic shielding filter taken along the line AA ′. Referring to the drawings, the shape of the mesh may be one having a masonry shape by forming a staggered mesh column in the center of the pores between the rows of the mesh in the horizontal direction alternately across the gap, When the mesh row is formed in a straight line shape, the viewing angle may be deteriorated.

The mesh layer 200 of the electromagnetic wave shielding filter according to the present invention has a thickness 31 of 110 to 190 μm, a line width 32 of 5 to 55 μm, a horizontal pitch 33 of 1500 to 2000 μm, and a longitudinal direction. The pitch 34 is 120 to 180㎛, the aperture ratio is made of Fe or Fe alloy material of 70% or more, the thickness 31 of the mesh layer 200 of the mesh layer of the conventional Cu mesh type electromagnetic shielding film It corresponds to about 10 times or more compared with the thickness about 10 micrometers. When the thickness 31 is less than 110㎛, there is a disadvantage that the electromagnetic wave shielding ability is lowered and the strength is lowered unless there is a separate base layer, and when it exceeds 190㎛, the thickness of the mesh layer is too thick even though the improvement of the electromagnetic shielding ability is weak. The disadvantage is losing. That is, since the electromagnetic wave shielding filter according to the present invention can maintain a predetermined strength even without a separate substrate layer, a process of laminating copper copper foil and the base film in the conventional Cu mesh type electromagnetic shielding filter can be omitted. This increases. When the line width 32 of the mesh is less than 5 μm, the strength of the mesh layer 200 may be weakened. When the line width 32 of the mesh is more than 55 μm, the visibility of the image may be adversely affected, and the line width 32 of the mesh is Preferably it is 5-25 micrometers. The pitch 33 in the horizontal direction of the mesh is 1500-2000 μm and the pitch 34 in the vertical direction is 120-180 μm. The pitch of the conventional electromagnetic shielding filter of Cu mesh type is 300 μm in both horizontal and vertical directions. In the case of the mesh layer 200 used in the present invention, a rectangular line shape is used, whereas the vertical pitch 34 is very small, whereas the horizontal pitch 33 is very large. The reason why the longitudinal pitch 34 is adjusted to 120 to 180 mu m is that when the electromagnetic shielding filter is mounted on the panel by making the pitch between the electrodes of the rear plate in the PDP about 300 mu m smaller than the pitch between the electrodes. This is to prevent moiré from occurring even if the horizontal direction of the mesh and the longitudinal direction of the electrode are horizontally placed without any bias. When the pitch 33 in the horizontal direction is less than 1500 μm, the opening ratio may drop. When the pitch 33 is greater than 2000 μm, the strength of the mesh layer 200 may be weakened. On the other hand, the aperture ratio is a variable that depends on the pitch and line width, but when it is less than 70%, the luminance is lowered, which is not preferable.

On the other hand, the material of the mesh layer 200 is characterized in that the Fe or Fe alloy, it is easy to perform the etching process using the Fe or Fe alloy plate that has been used for the conventional shadow mask as will be described later This also has the effect of reducing costs. The Fe alloy means Ni-Fe, Ni-Fe-Mo, and the like, but is not limited thereto.

The mesh of the mesh layer 200 may include a blackening layer 400 on all of the top, bottom, and side surfaces of the mesh layer 200. Since the Fe or the Fe alloy has a metallic luster, the light emitted from the PDP display screen is the mesh. This is to solve the problem that the visibility of the display screen is deteriorated by being reflected back to the display screen or being reflected by external incident light. On the other hand, when the blackening layer 400 is provided, it may also play a role of improving the contrast ratio by the role of absorbing external light at the same time.

The electromagnetic wave shielding filter according to the present invention may further include one or more transparent layers 300 stacked on the upper, lower or upper and lower portions of the mesh layer 200 and filling the pores of the mesh layer 200. 300 reinforces the strength of the mesh layer 200 and improves the impact resistance of the entire filter and plays a role of transparency. When the electromagnetic wave shielding filter is bonded with a functional film such as an antireflection layer, due to the thickness of 110 to 190 μm, voids exist in the bonding surface and light scattering from the PDP panel occurs due to the difference in refractive index between the air layer and the polymer layer. This causes a decrease. Therefore, the process of removing the said space | gap using transparent resin is called transparency. The resin used in the transparent process is not particularly limited as long as it is commonly used in the art and may be by using a hot melt resin, using an adhesive, or filling a fluid resin. In general, transparent resins for imparting impact resistance include impact resistant materials such as PET, PC, PSA, EVA, urethane, SBC, PVC, rubber resin, UV resin, more specifically, elastic high toughness, high strength semi-hardening or Fully curable vinyl resin, acrylic (acrylate), silicone, sulfone, epoxy, styrene, ester, carbonate, amide, imide, urethane, butadiene, olefin, ethylene, propylene Examples thereof include resins such as resins, EVA, and the like, and examples of the transparent resin imparting adhesiveness include rubber, acrylic, and silicone resins. In the electromagnetic wave shielding filter according to the present invention, one or more of the above-described transparent resins may be stacked on the upper, lower, or upper and lower portions of the mesh layer 200.

6 is a cross-sectional view of an electromagnetic shielding filter according to another embodiment of the present invention. The line width of the mesh is formed to have a lower line width 32 "wider than the upper line width 32 '. For example, the upper line width 32' may be set to 5 mu m and the lower line width 32" may be set to 25 mu m. have. This is to maximize the light emitted from the panel and to minimize external incident light. The cross section of the mesh may have a coke-shaped convex shape in the center as shown in FIG. 6 in the case of etching both sides of the Fe or Fe alloy plate.

According to a preferred embodiment of the present invention, the transparent layer 300 may further include a near-infrared shielding dye, a color correction dye, or a mixture thereof, in which case there is an advantage that the thickness of the PDP filter can be reduced. The near-infrared shielding dyes and color correction dyes that can be used in the above are not particularly limited to those commonly used in the art, for example, the near-infrared shielding dyes which absorb near-white seats of wavelengths between 850 and 1250 nm. Nium-based, nickeldithiol-based, phthalocyanine-based, cyanine-based or mixtures thereof may be used, and as color correction dyes, anthraquinone-based, cyanine-based, azo-based, which can selectively absorb neon light having a wavelength between 580 and 620 nm Naphthalocyanine series, methine series or mixtures thereof can be used. In the case of using both dyes, it is preferable that there is no problem such as deterioration during mixing.

Method for producing an electromagnetic shielding filter according to the present invention comprises the steps of: (a) applying a photosensitive film on both sides of the Fe or Fe alloy plate thickness 110 ~ 190㎛; (b) attaching and exposing a mask on both sides of the Fe or Fe alloy plate coated with the photoresist; (c) a developing step of forming a pattern by removing unexposed portions; (d) etching the exposed portion with an etching solution to form a mesh layer having a line width of 5 to 55 µm, a horizontal pitch of 1500 to 2000 µm, a vertical pitch of 120 to 180 µm, and an opening ratio of 70% or more; ; And (e) characterized in that it comprises the step of forming a transparent layer on the top, bottom or top and bottom of the mesh layer.

The material used in the step of applying the photosensitive film is not particularly limited as long as it is commonly used in the art, for example, a dry film resist can be used. The etching solution used in the step (d) may also be used without particular limitation as long as it is commonly used in the art, for example, a mixed solution of ferric chloride and hydrochloric acid may be used.

On the other hand, the step of forming the transparent layer of step (e) may be separately prepared after the transparent layer is laminated or coated with a liquid transparent layer forming polymer by a doctor blade coating method or the like. The transparent layer may be formed on any one surface of the mesh layer or both surfaces thereof. In order to remove the voids, the transparent layer may be formed on both surfaces and fill all of the voids therein. The thickness of the transparent layer is not particularly limited, but when both are formed on both sides, it is preferable to make the total thickness exceed 200 μm for the purpose of transparency.

After the step (d) it may further comprise a step of blackening the Fe or Fe alloy plate on which the mesh is formed, which is to prevent the deterioration of visibility by reflection of external light or emitted light as already mentioned. The blackening process is not particularly limited as long as it is commonly used in the art, and because the blackening layer formed by the blackening treatment can maintain the electromagnetic shielding ability only if it has conductivity, the conductive oxide film treatment or electroplating Preferably, the blackening layer is preferably formed on the upper, lower, left, and right surfaces of the mesh in view of improving visibility.

On the other hand, the blackening step is characterized in that it is carried out collectively unlike the conventional Cu mesh type electromagnetic shielding filter, in the case of the electromagnetic shielding filter according to the present invention because it does not use a base film as a support by the etching This is because the entire mesh can be blackened by immersing the prepared mesh layer in the blackening solution as a whole. That is, according to the method for manufacturing an electromagnetic wave shielding filter according to the present invention, since the blackening treatment step is completed once, the process efficiency can be significantly improved.

As mentioned above, in step (c), it is preferable that the upper width of the upper pattern is narrower than the lower width of the lower pattern so that the upper part is etched more than the lower part during etching so that the upper line width of the mesh is narrower than the lower line width. .

The PDP filter according to the present invention is characterized by including the electromagnetic wave shielding filter, the dye layer and the anti-reflection layer, etc. FIG. 7 is a schematic view of the PDP filter according to the present invention. Referring to FIG. 7, the dye layer 600 is stacked on top of the electromagnetic wave shielding filter 500 according to the present invention, and the anti-reflection layer 700 is sequentially stacked on the opposite side thereof. It is not limited.

The dye layer 600 may be a layer in which a near infrared shielding dye and a color correction dye are mixed, or may be a composite layer of a near infrared shielding layer and a color correction layer.

The anti-reflection layer 700 is formed to reduce the reflection of external light to improve visibility. The anti-reflection layer 700 may be made of fluorine-based transparent polymer resin or magnesium fluoride, silicon-based resin, silicon oxide thin film, or the like having low refractive index in the visible region. have. If necessary, an antireflection layer may also be formed on the upper part of the dye layer 600 to improve visibility.

Hereinafter, the present invention will be described in more detail with reference to preferred examples, but the present invention is not limited thereto.

Example 1

After degreasing both sides of the 150-micrometer-thick Fe-Ni alloy plate, the dry film resist was laminated on both surfaces of the said alloy plate. Next, a latent image pattern was formed by exposing the dry film resist using a mask, and then immersed in a mixed aqueous solution of hydrogen peroxide and sulfuric acid to develop a non-exposed portion. After that, the alloy plate is transferred to an etching box, and then sprayed and etched with an etchant mixed with ferric chloride and hydrochloric acid to give an upper line width of 5 μm, a lower line width of 25 μm, a horizontal pitch of 1800 μm, and a vertical pitch of 150 μm. A shielding filter was prepared.

Test Example 1

The electromagnetic wave shielding filter manufactured in Example 1 and a Cu mesh type electromagnetic shielding filter having a mesh layer having a conventional pitch of 300 µm and a thickness and line width of 10 µm were mounted on the PDP panel, and the electromagnetic shielding capability was measured. The results are shown in FIG. Referring to FIG. 8 (a), in the case of the conventional Cu mesh type electromagnetic shielding filter, the electromagnetic shielding filter according to the present invention of FIG. 8 (b) is far lower than 30 MHz in the low frequency region of 230 MHz or less. It can be seen that it is very excellent as 33 to 47MHz.

In addition, FIG. 9 is a graph showing the amount of electromagnetic waves emitted from the PDP for each frequency region after the electromagnetic wave shielding filter according to the present invention is mounted. The graph of FIG. 9 is a graph of FIG. Compared with the electromagnetic shielding filter), the electromagnetic wave shielding filter according to the present invention has an electromagnetic emission amount of about 20 dB in the low frequency region of 230 MHz or less, which is much lower than the above-mentioned electromagnetic emission emission tolerance of 30 dB. Can be.

As described above, the electromagnetic wave shielding filter according to the present invention has excellent electromagnetic shielding ability with an electromagnetic shielding amount of 30 dB or more in a low frequency region of 230 MHz or less, and does not include a separate base layer, and also performs a blackening process at a time. Because of this, the manufacturing process efficiency is excellent, and the contrast ratio can be improved while shielding the electric wave.

Claims (10)

A mesh layer of Fe or Fe alloy material having a thickness of 110 to 190 μm, a line width of 5 to 55 μm, a horizontal pitch of 1500 to 2000 μm, a vertical pitch of 120 to 180 μm, and an opening ratio of 70% or more And an electromagnetic shielding amount of 30 dB or more in a low frequency region of 230 MHz or less. The electromagnetic wave shielding filter according to claim 1, wherein the mesh of the mesh layer includes blackening layers on all of the top, bottom, and side surfaces thereof. 2. The electromagnetic shielding filter according to claim 1, wherein the mesh structure has a masonry masonry shape in which longitudinal mesh rows are alternately formed by filtering one void at the center of the pores between the horizontal rows of the mesh. The electromagnetic wave shielding filter of claim 1, further comprising at least one transparent layer stacked on the upper, lower, or upper and lower portions of the mesh layer and filling the pores of the mesh layer. The electromagnetic wave shielding filter according to claim 1, wherein the lower line width is wider than the upper line width of the mesh. The electromagnetic wave shielding filter according to claim 1, wherein the transparent layer further comprises a near-infrared shielding dye, a color correction dye, or a mixture thereof. (a) applying a photosensitive film on both sides of the Fe or Fe alloy plate having a thickness of 110 ~ 190㎛; (b) attaching and exposing a mask on both sides of the Fe or Fe alloy plate coated with the photoresist; (c) a developing step of forming a pattern by removing unexposed portions; (d) etching the exposed portion with an etching solution to form a mesh layer having a line width of 5 to 55 µm, a horizontal pitch of 1500 to 2000 µm, a vertical pitch of 120 to 180 µm, and an opening ratio of 70% or more; ; And (e) forming a transparent layer on the upper, lower or upper and lower portions of the mesh layer. The method of claim 7, wherein After the step (d) further comprising the step of blackening the Fe or Fe alloy plate on which the mesh is formed. The method of claim 7, wherein The line width of the upper pattern in step (c) is narrower than the line width of the lower pattern manufacturing method of the electromagnetic shielding filter. A plasma display panel filter comprising the electromagnetic shielding filter according to any one of claims 1 to 6.

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