JPWO2011122152A1 - Electromagnetic wave shielding film and electromagnetic wave shielding member - Google Patents

Abstract

Provided is an electromagnetic wave shielding film having high light transmittance in the visible wavelength region, high electromagnetic wave shielding ability, and low film stress. The electromagnetic wave shielding film 3 is formed by alternately laminating a plurality of high refractive index films 3H having a relatively high refractive index and a plurality of low refractive index films 3L having a relatively low refractive index. The plurality of high refractive index films 3H include a plurality of ITO films. The electromagnetic wave shielding film 3 does not have a metal film. When the total thickness of the electromagnetic wave shielding film 3 is t0 and the total thickness of the plurality of ITO films is t1, t1 / t0 is 0.3 or more.

Description

  The present invention relates to an electromagnetic wave shielding film and an electromagnetic wave shielding member. In particular, the present invention relates to an electromagnetic wave shielding film including an ITO film and an electromagnetic wave shielding member including the same.

  In recent years, the influence of electromagnetic waves leaking inside or outside of a device through a display on an electronic device or a human body has been regarded as a problem. In view of this, for example, the following Patent Document 1 and Patent Document 2 disclose an electromagnetic wave shielding film having an electromagnetic wave shielding ability.

Specifically, Patent Document 1 discloses an electromagnetic wave shielding film in which an Nb ₂ O ₅ layer, an ITO layer, an Ag layer, and an ITO layer are repeatedly laminated in this order.

On the other hand, Patent Document 2, as an electromagnetic wave shielding film for spectacle lens, and the SiO ₂ film having an optical thickness of 46～60Nm, the ITO film having an optical thickness of 65～79Nm, SiO ₂ film having an optical thickness of 18~22nm A film made of a material containing at least one of TiO ₂ , ZrO ₂ , and Ta ₂ O ₅ with an optical film thickness of 200 to 254 nm and an SiO ₂ film with an optical film thickness of 103 to 126 nm are laminated in this order. An electromagnetic wave shielding film is disclosed. Patent Document 2 describes that the electromagnetic wave shielding film also has an antireflection function.

JP 2006-121085 A Japanese Patent Laid-Open No. 11-149063

  The Ag layer used in the electromagnetic wave shielding film described in Patent Document 1 has a very high electromagnetic wave shielding ability. For this reason, as described in Patent Document 1, an electromagnetic wave shielding film having high electromagnetic wave shielding ability can be realized by using an Ag layer. However, the Ag layer has a low light transmittance in the visible wavelength region. Therefore, it is difficult to sufficiently increase the light transmittance in the visible wavelength region with an electromagnetic wave shielding film including a metal layer such as an Ag layer.

  On the other hand, as in the electromagnetic wave shielding film described in Patent Document 2, when only an ITO film is used as a film having an electromagnetic wave shielding ability, the light transmittance in the visible wavelength region is higher than when a metal film is used. Can be high. However, the electromagnetic wave shielding ability of the ITO film is lower than the electromagnetic wave shielding ability of the Ag film. In order to achieve high electromagnetic wave shielding ability using an ITO film, it is necessary to form a thick ITO film.

  However, since the ITO film also has absorption in the visible wavelength range, when the ITO film is thickened, the light transmittance in the visible wavelength range tends to decrease. Specifically, the light transmittance of the short wavelength side portion in the visible wavelength region is lowered. For this reason, in Patent Document 2, the optical film thickness of the ITO film is very small, 65 to 79 nm (physical film thickness, about 34 nm to 41 nm). Therefore, it is difficult for the electromagnetic wave shielding film described in Patent Document 2 to obtain a sufficiently high electromagnetic wave shielding ability.

  Further, when the thickness of the electromagnetic shielding film is increased in order to realize high electromagnetic shielding ability, the film stress of the electromagnetic shielding film tends to increase. For this reason, there exists a possibility that curvature may generate | occur | produce in the electromagnetic wave shielding member which consists of a board | substrate with which the electromagnetic wave shielding film was formed, or peeling of an electromagnetic wave shielding film may generate | occur | produce.

  The present invention has been made in view of such a point, and an object thereof is to provide an electromagnetic wave shielding film having high light transmittance in the visible wavelength region, high electromagnetic wave shielding ability, and low film stress. It is in.

  The electromagnetic wave shielding film according to the present invention is formed by alternately laminating a plurality of high refractive index films having a relatively high refractive index and a plurality of low refractive index films having a relatively low refractive index. The plurality of high refractive index films include a plurality of ITO films. The electromagnetic wave shielding film according to the invention does not have a metal film. In the present invention, when the total thickness of the electromagnetic wave shielding film is t0 and the total thickness of the plurality of ITO films is t1, t1 / t0 is 0.3 or more. For this reason, the ratio of the ITO film in the electromagnetic wave shielding film is high, and high electromagnetic wave shielding ability can be realized without increasing the thickness of the electromagnetic wave shielding film. Further, since the film stress of the ITO film is low, the film stress of the entire electromagnetic wave shielding film can be reduced by increasing the proportion of the ITO film in the electromagnetic wave shielding film. Therefore, according to the present invention, an electromagnetic wave shielding film having high electromagnetic wave shielding ability and low film stress can be realized.

  Further, as described above, in the present invention, since the electromagnetic wave shielding film is configured by the laminated film of the high refractive index film and the low refractive index film, light reflection can be suppressed. Therefore, according to the present invention, an electromagnetic wave shielding film having a high light transmittance in the visible wavelength region can be realized.

  As described above, according to the present invention, an electromagnetic wave shielding film having a high electromagnetic wave shielding ability, a high light transmittance in the visible wavelength region, and a small film stress can be realized.

  In the present invention, the visible wavelength range refers to a wavelength range of 400 nm to 650 nm.

  In the present invention, t1 / t0 is preferably 0.4 or more. In this case, the ratio of the ITO film to the electromagnetic wave shielding film becomes higher. Therefore, according to this configuration, it is possible to realize an electromagnetic wave shielding film having higher electromagnetic wave shielding ability, higher light transmittance in the visible wavelength region, and smaller film stress.

  In the present invention, the electromagnetic wave shielding film is preferably configured such that the average light reflectance in the visible wavelength region is 1.5% or less.

  In the present invention, t0 is preferably in the range of 400 nm to 2000 nm. If t0 is too large, the film stress of the electromagnetic wave shielding film may become too large. On the other hand, if t0 is too small, the light reflectance in the visible wavelength region may be too high.

  In the present invention, t1 is preferably in the range of 120 nm to 1000 nm. If t1 is too large, the light transmittance in the visible wavelength region may be too low. On the other hand, if t1 is too small, a sufficiently high electromagnetic wave shielding ability may not be obtained.

  In the present invention, the total number of high refractive index films and low refractive index films is preferably in the range of 4-25. If the total number of high refractive index films and low refractive index films is too small, it may be difficult to increase the light transmittance over the entire visible wavelength range. On the other hand, if the total number of high-refractive index films and low-refractive index films is too large, the film stress of the electromagnetic wave shielding film may become too large, and the time required for forming the electromagnetic wave shielding film becomes too long. There is.

  The electromagnetic wave shielding member according to the present invention includes a transparent substrate and the electromagnetic wave shielding film according to the present invention formed on the transparent substrate. For this reason, the electromagnetic wave shielding member according to the present invention has a high electromagnetic wave shielding ability, a high light transmittance in the visible wavelength region, and the electromagnetic wave shielding member according to the present invention has a small warpage and an electromagnetic wave shielding film. Is difficult to peel off.

In the present invention, the “transparent substrate” refers to a substrate having an average internal transmittance of 80% or more in the visible wavelength region. Here, the “internal transmittance” of the transparent substrate refers to the intensity (I) of light incident on the transparent substrate without being reflected on the surface of the transparent substrate, out of the light entering the transparent substrate at an incident angle of 0 °. ₀ )), the ratio (I ₁ / I ₀ ) of the intensity (I ₁ ) of the light emitted from the transparent substrate.

  When the thickness of the transparent substrate is in the range of 0.2 mm to 2.0 mm, the electromagnetic wave shielding member is likely to warp due to the film stress of the electromagnetic wave shielding film, so that the film stress of the electromagnetic wave shielding film can be reduced. The invention is more suitably applied.

  According to the present invention, it is possible to provide an electromagnetic wave shielding film having high light transmittance in the visible wavelength region, high electromagnetic wave shielding ability, and small film stress.

FIG. 1 is a schematic cross-sectional view of an electromagnetic wave shielding member according to an embodiment of the present invention. FIG. 2 is a graph showing the light transmittance and light reflectance of the electromagnetic wave shielding films according to Examples 1 to 3. FIG. 3 is a graph showing the electromagnetic wave shielding ability of the electromagnetic wave shielding film in Example 1 and Comparative Example 1. FIG. 4 is a graph showing the electromagnetic wave shielding ability of the electromagnetic wave shielding film in Example 2 and Comparative Example 2. FIG. 5 is a graph showing the electromagnetic wave shielding ability of the electromagnetic wave shielding film in Example 3 and Comparative Example 3.

  Hereinafter, a preferred embodiment in which the present invention is implemented will be described taking the electromagnetic wave shielding member 1 shown in FIG. 1 as an example. However, the electromagnetic wave shielding member 1 is merely an example. The electromagnetic wave shielding member according to the present invention is not limited to the electromagnetic wave shielding member 1 at all.

  As shown in FIG. 1, the electromagnetic wave shielding member 1 includes a transparent substrate 2. The material of the transparent substrate 2 is not particularly limited as long as it transmits light in the visible wavelength range. The transparent substrate 2 can be formed of glass, resin, ceramics, or the like, for example. The thickness of the transparent substrate 2 is not particularly limited, but is preferably about 0.2 mm to 2.0 mm.

  An electromagnetic wave shielding film 3 is formed on the transparent substrate 2. The electromagnetic wave shielding film 3 has both an electromagnetic wave shielding ability and a light reflection suppressing function in the visible wavelength region.

  The electromagnetic wave shielding film 3 is composed of a laminated film in which a plurality of high refractive index films 3H and a plurality of low refractive index films 3L are alternately laminated. The electromagnetic wave shielding film 3 does not have a metal film such as an Ag film, for example.

  The high refractive index film 3H is a film having a relatively high refractive index as compared with the low refractive index film 3L. The low refractive index film 3L is a film having a relatively low refractive index as compared with the high refractive index film 3H. The refractive index in the visible wavelength region of the high refractive index film 3H is not particularly limited, but can be, for example, 1.8 or more. The refractive index in the visible wavelength region of the low refractive index film 3L is not particularly limited, but may be 1.6 or less, for example.

  The low refractive index film 3L is made of, for example, an oxide, nitride, or fluoride of an alkaline earth metal such as silicon, Ca, Ba, or Sr.

The high refractive index film 3H includes a plurality of ITO (Indium Tin Oxide) films. All of the high refractive index films 3H among the plurality of high refractive index films 3H may be made of an ITO film, or two or more of the plurality of high refractive index films 3H are made of an ITO film. The other high refractive index film 3H may be composed of a high refractive index film other than the ITO film. Specific examples of the high refractive index film other than the ITO film include an Nb ₂ O ₅ film, a TiO ₂ film, a ZrO ₂ film, a Ta ₂ O ₅ film, a La ₂ O ₃ film, and a Y ₂ O ₃ film.

  Since the electromagnetic wave shielding ability is substantially determined by the thickness and quantity of the ITO film, how much of the plurality of high refractive index films 3H is constituted by the ITO film is determined based on the desired electromagnetic wave shielding ability. Can do. Moreover, the configuration of the high refractive index film 3H other than the ITO film can be determined according to the desired light reflection suppressing function in the visible wavelength range, the light transmittance, the wavelength dependency of the light refractive index, and the like.

  The thickness and the number of films of the high-refractive index film 3H and the low-refractive index film 3L can be appropriately determined according to the desired electromagnetic wave shielding ability, the light reflection suppression function in the visible wavelength range, and the like. The thicknesses of the high refractive index film 3H and the low refractive index film 3L can be set to about 5 nm to 200 nm, for example. The total number of high refractive index films 3H and low refractive index films 3L is preferably about 4 to 25, for example. If the total number of high refractive index films 3H and low refractive index films 3L is too small, it may be difficult to increase the light transmittance over the entire visible wavelength range. On the other hand, if the total number of the high refractive index film 3H and the low refractive index film 3L is too large, the film stress of the electromagnetic wave shielding film 3 may become too large, and the time required for forming the electromagnetic wave shielding film 3 may be increased. May be too long.

  In this embodiment, when the total thickness of the electromagnetic wave shielding film 3 is t0 and the total thickness of the plurality of ITO films is t1, t1 / t0 is 0.3 or more. For this reason, the ratio of the ITO film to the electromagnetic wave shielding film 3 is high. Therefore, high electromagnetic shielding ability can be realized without increasing the thickness of the electromagnetic shielding film 3.

Further, the film stress of the ITO film is smaller than the film stress of other high refractive index films such as a TiO ₂ film and an Nb ₂ O ₅ film. For this reason, by increasing the proportion of the ITO film in the electromagnetic wave shielding film 3, the film stress of the entire electromagnetic wave shielding film 3 can be reduced. Therefore, peeling of the electromagnetic wave shielding film 3 from the transparent substrate 2 and warping of the electromagnetic wave shielding member 1 can be suppressed. In particular, when the thickness of the transparent substrate 2 is in the range of 0.2 mm to 2.0 mm, the electromagnetic wave shielding member 1 is likely to warp due to the film stress of the electromagnetic wave shielding film 3. Therefore, the technique of the present embodiment that can reduce the film stress of the electromagnetic wave shielding film 3 is particularly preferably applied when the thickness of the transparent substrate 2 is in the range of 0.2 mm to 2.0 mm.

  Furthermore, in this embodiment, since the thickness of the electromagnetic wave shielding film 3 can be reduced, the light absorption rate in the electromagnetic wave shielding film 3 can be reduced. The electromagnetic wave shielding film 3 is composed of a laminated film of a high refractive index film 3H and a low refractive index film 3L. For this reason, the light reflection of the incident light to the electromagnetic wave shielding film 3 can be suppressed. Therefore, the light transmittance in the visible wavelength region can be increased.

  As described above, by setting t1 / t0 to 0.3 or more, it is possible to realize the electromagnetic wave shielding film 3 having high electromagnetic wave shielding ability, high light transmittance in the visible wavelength region, and small film stress. it can.

  From the viewpoint of realizing higher electromagnetic shielding ability, light transmittance, and smaller film stress, t1 / t0 is preferably larger. Specifically, t1 / t0 is preferably 0.4 or more. However, if t1 / t0 is too large, it will be difficult for the electromagnetic wave shielding film 3 to have a configuration capable of reducing the light reflectance in the entire visible wavelength range. Therefore, t1 / t0 is preferably 0.5 or less, and more preferably 0.45 or less.

  The electromagnetic wave shielding film 3 is preferably configured such that the average light reflectance in the visible wavelength region is 1.5% or less.

  t0 is preferably in the range of 400 nm to 2000 nm. If t0 is too large, the film stress of the electromagnetic wave shielding film 3 may become too large. On the other hand, if t0 is too small, the light reflectance in the visible wavelength region may be too high.

  t1 is preferably in the range of 120 nm to 1000 nm. If t1 is too large, the light transmittance in the visible wavelength region may be too low. On the other hand, if t1 is too small, a sufficiently high electromagnetic wave shielding ability may not be obtained.

  Hereinafter, the present invention will be described in more detail on the basis of specific examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented without departing from the scope of the present invention. Is possible.

Example 1
An electromagnetic wave shielding film having a film configuration shown in Table 1 below is formed on a transparent substrate made of a glass substrate having a thickness of 0.4 mm and a size of 200 mm square (OA-10 manufactured by Nippon Electric Glass Co., Ltd.) by sputtering. Thus, an electromagnetic wave shielding member was produced.

  The light transmittance and light reflectance in the visible wavelength region of the produced electromagnetic wave shielding member were measured with a spectrophotometer (U-4000 manufactured by Hitachi, Ltd.). The results are shown in FIG.

  Moreover, as a result of measuring the maximum curvature amount of the produced electromagnetic wave shielding member, it was 1.3 mm.

(Example 2)
Except that an electromagnetic wave shielding film having a film configuration shown in Table 2 below was formed, an electromagnetic wave shielding member was produced in the same manner as in Example 1, and the light transmittance and the light reflectance were measured. The results are shown in FIG. Moreover, as a result of measuring the maximum amount of warpage of the electromagnetic wave shielding member produced in this example in the same manner as in Example 1, it was 1.5 mm.

(Example 3)
An electromagnetic wave shielding member was prepared in the same manner as in Example 1 except that an electromagnetic wave shielding film having a film configuration shown in Table 3 below was formed, and the light transmittance and the light reflectance were measured. The results are shown in FIG. It was 1.7 mm as a result of measuring the maximum curvature amount of the electromagnetic wave shielding member produced in the present example in the same manner as in Example 1.

(Comparative Example 1)
An electromagnetic wave shielding member was produced in the same manner as in Example 1 except that an electromagnetic wave shielding film having a film configuration shown in Table 1 below was formed. It was 1.8 mm as a result of measuring the maximum curvature amount of the electromagnetic wave shielding member produced in this comparative example like Example 1.

(Comparative Example 2)
An electromagnetic wave shielding member was produced in the same manner as in Example 1 except that an electromagnetic wave shielding film having a film configuration shown in Table 2 below was formed. It was 2.0 mm as a result of measuring the largest curvature amount of the electromagnetic wave shielding member produced in this comparative example like Example 1.

(Comparative Example 3)
An electromagnetic wave shielding member was produced in the same manner as in Example 1 except that an electromagnetic wave shielding film having a film configuration shown in Table 3 below was formed. It was 2.3 mm as a result of measuring the maximum curvature amount of the electromagnetic wave shielding member produced in this comparative example in the same manner as in Example 1.

  In addition, the refractive index shown to the said Tables 1-3 is a refractive index in wavelength 550nm.

  From the results shown in FIG. 2, according to the present invention, an electromagnetic wave shielding film is formed by a laminated film in which a plurality of high refractive index films including a plurality of ITO films and a plurality of low refractive index films are alternately laminated. It can be seen that light reflection in the wavelength range can be suppressed and high light transmittance in the visible wavelength range can be obtained.

  As shown in Tables 1 to 3, in Comparative Examples 1 to 3 where t1 / t0 is less than 0.3, the maximum warpage amount was large. On the other hand, in Examples 1 to 3 in which t1 / t0 was 0.3 or more, the maximum warpage amount was small. From these results, it can be seen that the warpage of the electromagnetic wave shielding member can be reduced by increasing the proportion of the ITO film in the electromagnetic wave shielding film and setting a plurality of t1 / t0 to be 0.3 or more. From this result, it is understood that the film stress of the electromagnetic wave shielding film can be reduced by increasing the proportion of the ITO film in the electromagnetic wave shielding film and setting t1 / t0 to 0.3 or more. Moreover, it turns out that the film stress of an electromagnetic wave shielding film can be reduced more effectively by making t1 / t0 into 0.4 or more.

(Evaluation of electromagnetic wave shielding ability)
The electromagnetic wave shielding ability of the electromagnetic wave shielding member produced in each of Examples 1 to 3 and Comparative Examples 1 to 3 was evaluated in the following manner. That is, the electromagnetic wave shielding members of Examples 1 to 3 and Comparative Examples 1 to 3 are arranged between the radiation unit that radiates electromagnetic waves and the reception unit. And the electromagnetic wave attenuation was measured from the electromagnetic wave radiated | emitted from the radiation | emission part and the electromagnetic wave received in the receiving part. Similarly, the amount of electromagnetic wave attenuation was measured when the glass plate used for the electromagnetic wave shielding member (without the electromagnetic wave shielding film) was disposed between the radiating part and the receiving part. And the electromagnetic wave attenuation amount in the glass plate single-piece | unit is subtracted from the electromagnetic wave attenuation amount measured for every electromagnetic wave shielding member, and the electromagnetic wave attenuation by the electromagnetic wave shielding film of each electromagnetic wave shielding member of Examples 1-3 and Comparative Examples 1-3 Got the amount. The electromagnetic wave shielding ability is evaluated by the electromagnetic wave attenuation amount, and the electromagnetic wave shielding ability is higher as the electromagnetic wave attenuation amount is larger. The results are shown in FIGS. 3 to 5 and Tables 4 to 6 below. Note that the measurement range of the electromagnetic wave attenuation was 100 MHz to 1 GHz. Tables 4 to 6 below show the amount of electromagnetic wave attenuation by the electromagnetic wave shielding film at 500 MHz.

  From the results shown in FIGS. 3 to 5 and Tables 4 to 6, it is understood that high electromagnetic wave shielding ability can be obtained by setting t1 / t0 to 0.3 or more. From the above results, it can be seen that by setting t1 / t0 to 0.3 or more, an electromagnetic wave shielding member having a high electromagnetic wave shielding ability and a small film stress of the electromagnetic wave shielding film can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Electromagnetic shielding member 2 ... Transparent substrate 3 ... Electromagnetic shielding film 3H ... High refractive index film 3L ... Low refractive index film

Claims (8)

A plurality of high refractive index films having a relatively high refractive index and a plurality of low refractive index films having a relatively low refractive index are alternately laminated, and the plurality of high refractive index films include a plurality of ITO. An electromagnetic wave shielding film that includes a film and does not have a metal film,
An electromagnetic wave shielding film in which t1 / t0 is 0.3 or more, where t0 is a total thickness of the plurality of ITO films, and t1 is a total thickness of the plurality of ITO films.   The electromagnetic wave shielding film according to claim 1, wherein t1 / t0 is 0.4 or more.   The electromagnetic wave shielding film according to claim 1 or 2, wherein an average light reflectance in a visible wavelength region is 1.5% or less.   The electromagnetic wave shielding film according to any one of claims 1 to 3, wherein t0 is in a range of 400 nm to 2000 nm.   The electromagnetic wave shielding film according to claim 1, wherein t1 is in a range of 120 nm to 1000 nm.   The electromagnetic wave shielding film according to any one of claims 1 to 5, wherein the total number of the high refractive index film and the low refractive index film is in a range of 4 to 25. A transparent substrate;
An electromagnetic wave shielding member comprising the electromagnetic wave shielding film according to any one of claims 1 to 6 formed on the transparent substrate.   The electromagnetic wave shielding member according to claim 7, wherein a thickness of the transparent substrate is in a range of 0.2 mm to 2.0 mm.

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