JP2010056236A - Frequency selecting member, method for manufacturing such requency selecting member, and wave absorber having such requency selecting member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a frequency selecting member for a wave absorber which maintains a thin shape and exhibits a proper frequency selecting characteristic with favorable appearance. <P>SOLUTION: In the frequency selecting member for the wave absorber in which a transparent substrate, a conductive layer, and an additional layer formed for coating a surface of the conductive layer are laminated in this order, the conductive layer is patterned to a plurality of segments, a space is formed between the respective segments, and the additional layer is so disposed on the conductive layer as to leave the space and incldues a substantially flat exposed surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a frequency selection member and a method for manufacturing such a frequency selection member. Moreover, this invention relates to the electromagnetic wave absorber which has such a frequency selection member.

  In order to prevent the influence of electromagnetic waves from electronic devices used in close proximity to each other, a radio wave absorber that absorbs unnecessary electromagnetic waves is used.

  Conventional radio wave absorbers, for example, are configured by installing a transparent conductive layer such as ITO (indium tin oxide) on a transparent substrate and a transparent reflective film on the transparent substrate. The reflective member thus formed is arranged in parallel with a predetermined interval through a spacer layer (see Patent Documents 1 and 2).

When an unnecessary electromagnetic wave is incident on the radio wave absorber configured as described above via the absorbent member, the incident unnecessary electromagnetic wave is reflected by the reflective member, passes through the absorbent member again, and then from the radio wave absorber. Will be emitted. Here, the distance between the absorbing member and the reflecting member provided by the spacer layer is set so that the phase of the electromagnetic wave radiated from the radio wave absorber is inverted by 180 ° from the phase of the incident electromagnetic wave. Therefore, the electromagnetic wave incident on the radio wave absorber is canceled by the electromagnetic wave radiated from the radio wave absorber, and as a result, the unnecessary electromagnetic wave can be lost.
Japanese Patent Laid-Open No. 6-120688 JP 2008-28062 A JP 2008-4951 A

  In a conventional radio wave absorber, when an unnecessary electromagnetic wave is properly absorbed (disappeared), the distance between the absorbing member and the reflecting member, that is, the thickness of the spacer layer needs to be extremely large (for example, 1 GHz) When electromagnetic waves are targeted, about 10 cm). This is because when the phase of the electromagnetic wave incident on the radio wave absorber and the electromagnetic wave radiated from the radio wave absorber are reversed, the thickness of the spacer layer needs to be designed to be 1/4 of the wavelength λ. It is. For this reason, the conventional radio wave absorber has a problem that the thickness of the spacer layer is limited, and the thickness of the radio wave absorber cannot be reduced too much.

  On the other hand, recently, a technique has been developed in which a layer called a frequency selective surface (FSS) is provided between the absorbent member and the reflective member so as to narrow the distance between the two. In addition, a technique has been developed that causes the absorbent member itself to exhibit a function as a frequency selection layer by patterning the transparent conductive layer described above (for example, Patent Document 3).

  An absorptive member (hereinafter referred to as a “frequency selection member”) provided with such a patterned transparent conductive layer is formed on a transparent substrate 20 such as PET, as shown in FIG. Further, the pattern 32 of the conductive oxide 30S such as ITO is formed by a technique such as screen printing or gravure printing. The minimum value of the line width between the conductive oxides 30S thus obtained (that is, the width W of the gap 35 in FIG. 1) is about 50 μm. In a normal case, an additional layer 40 is further provided on the patterned conductive layer 30 as shown in FIG. The additional layer 40 has a role of protecting the surface of the patterned conductive layer 30 from the outside or preventing reflection of incident electromagnetic waves. The additional layer 40 is installed by a general film forming technique such as sputtering or vapor deposition.

  However, when trying to install the additional layer 40 on the patterned conductive layer 30, as shown in FIG. 1B, due to the presence of the gap 35 between the conductive oxides 30S, the additional layer 40 A concave portion 36 is formed on the exposed surface 39. Moreover, the gap 35 between the conductive oxides 30 </ b> S is filled with the material constituting the additional layer 40 due to the additional layer 40.

  In the frequency selection member 1 having such a configuration, although each member (the substrate 20, the conductive layer 30, and the additional layer 40) is made of a transparent material, light is emitted due to the unevenness of the exposed surface 39 of the additional layer 40. There is a problem that the appearance of the frequency selecting member 1 is deteriorated.

  In addition, when such a frequency selection member 1 is applied to a radio wave absorber, the gap 35 is filled with the additional layer 40 and the space is lost, so that the appropriate frequency selection characteristics predicted at the time of design cannot be obtained. There may be a problem that the radio wave absorption performance is deteriorated.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a frequency selection member that has a good appearance and maintains appropriate frequency selection characteristics while maintaining a thin shape. Another object of the present invention is to provide a method for manufacturing such a frequency selection member, and a radio wave absorber including such a frequency selection member.

In the present invention,
A frequency selective member for a radio wave absorber in which a transparent substrate, a conductive layer, and an additional layer provided to cover the surface of the conductive layer are laminated in this order,
The conductive layer is patterned into a plurality of segments, and spaces are formed between the segments.
The additional layer is disposed on the conductive layer so that the space remains, and has a substantially flat exposed surface. A frequency selection member for a radio wave absorber is provided.

  Here, in the frequency selection member of the present invention, the width of the space between the segments may be in the range of 10 nm to 100 nm.

Moreover, in the frequency selection member of the present invention, the transparent base material substantially transmits laser light,
The conductive layer absorbs at least a portion of the laser beam;
The additional layer may substantially reflect or transmit the laser light.

  In the present application, “substantially transmit (permit)” means the transmittance, reflectance, and absorptance of a certain member with respect to laser light having a specific wavelength (where transmittance + reflectivity + absorbance = 1). ) Means the highest transmittance. Further, “substantially reflect” means that the transmittance, reflectance, and absorptance of a certain member with respect to laser light having a specific wavelength (transmittance + reflectance + absorption rate = 1) This means that the reflectance is the highest.

  In the frequency selection member of the present invention, the conductive layer may be made of at least one material selected from the group consisting of tin oxide, zinc oxide, silver, and ITO (indium tin oxide).

  In the frequency selection member of the present invention, the transparent substrate is made of PET (polyethylene terephthalate), PC (polycarbonate), TAC (triacetylcellulose), PEN (polyethylene naphthalate), and PMMA (polymethacrylate). It may be composed of at least one selected material.

In the frequency selection member of the present invention, the laser beam is an Nd: YAG laser beam having a wavelength of about 1064 nm,
The additional layer may include at least one material selected from the group consisting of silicon nitride (SiN), silicon dioxide (SiO ₂ ), silicon carbide (SiC), and silicon oxynitride (SiON).

In the frequency selection member of the present invention, the laser beam is an Nd: YAG laser beam (second harmonic) having a wavelength of about 532 nm,
The additional layer is at least one selected from the group consisting of aluminum nitride (AlN), hafnium dioxide (HfO ₂ ), magnesium difluoride (MgF ₂ ), silicon nitride (SiN), and silicon dioxide (SiO ₂ ). Materials may be included.

In the present invention,
A reflective member composed of a substrate having a reflective film on the surface;
A frequency selection member having the aforementioned characteristics;
A radio wave absorber comprising:

Furthermore, in the present invention,
(A) installing a conductive layer on the transparent substrate;
(B) installing an additional layer on the conductive layer;
(C) after the step of (b), patterning the conductive layer, substantially transmitting the transparent substrate, substantially transmitting or reflecting the additional layer, The conductive layer is selectively patterned by irradiating at least partly absorbed laser light from the substrate side; and
There is provided a method of manufacturing a frequency selection member for a radio wave absorber.

  Here, in the method for producing a frequency selection member of the present invention, the conductive layer may be made of a material selected from the group consisting of tin oxide, zinc oxide, silver, and ITO (indium tin oxide).

  Moreover, in the manufacturing method of the frequency selection member of this invention, the said transparent base material is from PET (polyethylene terephthalate), PC (polycarbonate), TAC (triacetylcellulose), PEN (polyethylene naphthalate), and PMMA (polymethacrylate). It may be composed of at least one material selected from the group consisting of:

In the method for manufacturing a frequency selective member of the present invention, the laser beam is an Nd: YAG laser beam having a wavelength of about 1064 nm,
The additional layer may include at least one material selected from the group consisting of silicon nitride (SiN), silicon dioxide (SiO ₂ ), silicon carbide (SiC), and silicon oxynitride (SiON).

  In the present invention, it is possible to provide a frequency selection member that has a good appearance and maintains an appropriate frequency selection characteristic while maintaining a thin shape. Moreover, in this invention, it becomes possible to provide the method of manufacturing such a frequency selection member, and a radio wave absorber provided with such a frequency selection member.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 shows a schematic cross-sectional view of an example of the frequency selection member according to the present invention. The frequency selection member 100 according to the present invention is configured by laminating a transparent substrate 120, a conductive layer 130, and an additional layer 140 in this order.

  The transparent substrate 120 serves as a carrier that supports the conductive layer 130 and the additional layer 140. The transparent substrate 120 is made of a material such as a transparent plastic material, for example. Examples of the transparent plastic material include PET (polyethylene terephthalate), PC (polycarbonate), TAC (triacetyl cellulose), PEN (polyethylene naphthalate), PMMA (polymethacrylate), and the like.

  As will be described later, the transparent substrate 120 is made of any material as long as it has a sufficiently low absorption rate with respect to laser light having a predetermined wavelength λ and substantially transmits such laser light. May be used. In FIG. 3, the graph which showed the wavelength dependence of the absorptance about various transparent materials is shown. For example, it can be seen that the aforementioned PET has a very low absorptivity of less than 5% for a wide range of light ranging from 400 nm to 2000 nm (excluding the wavelength of 1700 nm). The thickness of the transparent substrate 120 is not particularly limited. However, if the thickness is too large, the total thickness when applied to the radio wave absorber is increased. Therefore, the thickness is preferably about 100 nm to 1 mm, for example, 50 μm or 100 μm. It is.

  The conductive layer 130 has a role of so-called “frequency selection” that transmits only incident electromagnetic waves having a specific range of frequencies. As shown in FIG. 2, the conductive layer 130 is patterned so as to have a plurality of segments 130S, and spaces 135 are formed between the segments 130S. When viewed from the top (not shown), the shape of each segment 130S is not particularly limited, and each segment 130S has various shapes such as a square and a rectangle, as well as various shapes such as a circle and an ellipse. You may do it.

  The thickness of the conductive layer 130 is not particularly limited, but is generally in the range of 50 nm to 100 nm when used for a radio wave absorber. Preferably, it is the range of 80 nm-100 nm. On the other hand, the width W1 of the space 135 is, for example, in the range of 10 nm to 100 nm. However, the width W1 is set based on the frequency range of incident electromagnetic waves targeted by the frequency selection member 100.

  The conductive layer 130 is made of a transparent metal oxide, and for example, tin oxide, zinc oxide, silver, ITO (indium tin oxide), or the like is used. As will be described later, the conductive layer 130 is made of a material having a large absorption rate (absorption rate of 10% or more) with respect to laser light having a predetermined wavelength λ. For example, as shown in FIG. 3, ITO has a large absorption rate (absorption rate of 10% or more) for light having a wavelength of 950 nm or more.

  The additional layer 140 is a transparent layer provided to cover the surface of the conductive layer 130. By providing the additional layer 140, the surface of the frequency selection member 100 can be provided with characteristics such as scratch resistance and antifouling resistance. Further, the additional layer 140 may provide antireflection properties.

  Although the thickness of the additional layer 140 is not specifically limited, For example, it is the range of 5 nm-1 mm. Preferably, it is the range of 10 nm-5 micrometers.

  As will be described later, the additional layer 140 has a sufficiently low absorption rate for laser light having a predetermined wavelength λ (absorption rate of 5% or less), and substantially transmits or reflects such laser light. Consists of materials that A specific material of the additional layer 140 will be described later.

  Next, the characteristics of the frequency selection member 100 according to the present invention configured as described above will be described in comparison with a conventional frequency selection member.

  FIG. 1 schematically shows a method for manufacturing a conventional frequency selection member 1.

  As shown in FIG. 1A, a conventional frequency selection member 1 having a patterned transparent conductive layer is formed on a transparent substrate 20 such as PET by ITO or other techniques such as screen printing and gravure printing. The pattern 32 of the conductive oxide 30S as described above is formed. The line width of the pattern 32 formed by such a method (that is, the width W of the gap 35 in FIG. 1) is about 50 μm, and the conductive material separated on the transparent substrate 20 at a relatively wide interval. A pattern 32 of the oxide 30S is formed.

  Next, as shown in FIG. 1 (b), it is added on the patterned conductive layer 30 by a general film forming technique such as physical vapor deposition such as sputtering or chemical vapor deposition such as thermal CVD. Layer 40 is installed. Here, as described above, since the relatively wide gap 35 is formed in the conductive layer 30, the material constituting the additional layer 40 easily enters the gap 35 during film formation. be able to. Accordingly, the gap 35 is filled with the intrusion material. Further, due to this influence, a concave portion 36 corresponding to the pattern of the gap 35 is formed on the exposed surface 39 of the additional layer 40 finally obtained.

  In the frequency selection member 1 having such a configuration, although each member (the substrate 20, the conductive layer 30, and the additional layer 40) is made of a transparent material, light is emitted due to the unevenness of the exposed surface 39 of the additional layer 40. This causes a problem that the frequency selection member 1 is not good in appearance. Moreover, when such a frequency selection member 1 is applied to a radio wave absorber, the gap 35 is filled with the additional layer 40, and the space between the conductive oxides 30S is lost. There may be a problem that the frequency selection characteristic cannot be obtained and the radio wave absorption performance is deteriorated.

  On the other hand, in the frequency selection member 100 according to the present invention, as shown in FIG. 2, a space 135 remains between the conductive oxides 130S, and the additional layer 140 is not filled therein. Further, even if the exposed surface 139 of the additional layer 140 is in a state immediately after the additional layer 140 is installed, the exposed surface 139 is a substantially flat surface, and the concave portion as described above is not formed.

  Therefore, in the frequency selection member 100 according to the present invention, it is possible to significantly suppress the conventional problem that light scattering occurs on the surface of the additional layer 140 and the appearance is deteriorated. In addition, when the frequency selection member 100 according to the present invention is installed in a radio wave absorber, it is possible to obtain an appropriate frequency selection characteristic as predicted at the time of design, and thus an appropriate radio wave absorption characteristic can be obtained.

(Method for producing patterned member according to the present invention)
Next, with reference to FIG. 4 and FIG. 5, an example of the manufacturing method of the frequency selection member by this invention which has the above characteristics is demonstrated. Note that the following method is merely an example of a method for manufacturing a frequency selection member according to the present invention, and it is obvious to those skilled in the art that the frequency selection member according to the present invention may be manufactured by other methods. Let's go.

  FIG. 4 is a view showing a flowchart of a method of manufacturing a frequency selection member according to the present invention. FIG. 5 is a diagram schematically showing a process of forming a frequency selection member according to the present invention.

  As shown in FIG. 4, in the method for manufacturing a frequency selection member according to the present invention, a step of installing a conductive layer on a transparent substrate (Step S110) and a step of installing an additional layer on the conductive layer (Step S120). And a step of selectively patterning the conductive layer using a laser beam (step S130). Hereinafter, each step will be described in detail.

(Installation of conductive layer on transparent substrate)
First, the transparent base material 120 for installing the conductive layer 130 is prepared. The transparent base material 120 is selected from the above-mentioned transparent plastic materials, for example. The transparent substrate 120 is, for example, PET. The thickness of the transparent substrate 120 is, for example, 100 μm.

  Before installing the conductive layer, the surface of the transparent substrate 120 is preferably washed. The surface cleaning is performed, for example, by dry cleaning using an ion beam. In this case, argon gas is mixed with about 30% oxygen and power of 100 W is input. Thereby, the surface of the transparent base 120 is irradiated with argon and oxygen ions ionized by the ion beam source, and the surface can be dry-cleaned.

  Next, as shown in FIG. 5A, a conductive layer 130 ′ is installed on the cleaned surface of the transparent substrate 120. The conductive layer 130 ′ may be placed on the transparent substrate by any method. The conductive layer 130 ′ is disposed on the transparent substrate 120 by physical vapor deposition such as sputtering or ion plating, or chemical vapor deposition such as thermal CVD or plasma CVD. In addition, as shown to Fig.5 (a), electroconductive layer 130 'is installed so that the whole surface of the transparent base material 120 may be covered.

  The conductive layer 130 ′ is made of the transparent metal oxide as described above. Although the thickness of a conductive layer is not specifically limited, For example, it is 50 nm.

(Installation of additional layers)
Next, as shown in FIG. 5B, the additional layer 140 is provided on the conductive layer 130 ′ described above. The additional layer may be disposed on the conductive layer 130 ′ by any method. The additional layer 140 is disposed on the conductive layer 130 ′ by, for example, physical vapor deposition such as sputtering or ion plating, or chemical vapor deposition such as thermal CVD or plasma CVD. In addition, as shown in FIG.5 (b), the additional layer 140 is installed so that the whole surface of conductive layer 130 'may be covered. The thickness of the additional layer 140 is, for example, about 10 nm.

(Conductive layer patterning)
Next, the conductive layer 130 ′ between the transparent substrate 120 and the additional layer 140 is patterned into a desired pattern. The method according to the present invention is characterized in that the laser beam 110 is used for the patterning process. In the method according to the present invention, the laser beam 110 is irradiated from the transparent substrate 120 side as shown in FIG.

  Here, as described above, the transparent substrate 120 is made of a material that transmits the laser beam 110 and does not substantially absorb the laser beam. The additional layer 140 is made of a material that substantially transmits or reflects the laser beam 110 and does not absorb the laser beam (absorption rate of 5% or less). Therefore, in the present invention, the laser beam 110 is selectively absorbed only by the conductive layer 130 ′, and only the conductive layer 130 ′ can be selectively processed.

FIG. 6 shows an example of such a combination of the type and wavelength λ of the laser light 110 and a material having a low absorptance at the wavelength λ (that is, a candidate material for the additional layer 140). For example, when Nd: YAG laser light having a wavelength of 1064 nm (fundamental wavelength) is used, as the additional layer 140, silicon nitride (SiN), silicon dioxide (SiO ₂ ), silicon carbide (SiC), and silicon oxynitride (SiON One or more materials selected from the group consisting of: In addition, in the second harmonic of Nd: YAG laser light (wavelength 532 nm), aluminum nitride (AlN), hafnium dioxide (HfO ₂ ), magnesium difluoride (MgF ₂ ), silicon nitride (SiN), silicon dioxide (SiO ₂₎ ) And mixtures thereof can be used. The same applies to the case of Er: YAG laser (fundamental frequency 2940 nm), Ho: YAG laser (fundamental frequency 2100 nm), and the like. However, the combination of FIG. 6 is only an example, and there are many combinations of other laser light having a wavelength in the range of 400 nm to 2000 nm and a material with low absorptance at the wavelength λ other than the example of FIG. It will be apparent to those skilled in the art.

  When any one of such combinations of laser light and material is used, the irradiated laser light 110 is not absorbed by the additional layer 140 but is selectively absorbed only by the conductive layer 130 ′.

  Therefore, by using an appropriate combination of the laser beam 110 and the additional layer 140, only the conductive film 130 ′ can be selectively patterned by irradiation with the laser beam 110.

The irradiation energy of the laser beam 110 irradiated from the transparent substrate 120 side varies depending on the type, wavelength, and the like of the laser beam used. For example, Nd: YAG having a wavelength λ of 1064 nm (basic wavelength) is used. When using laser light, the irradiation fluence may be up to about 30,000 mJ / cm ² . Further, when Nd: YAG laser light having a wavelength λ of 532 nm (second harmonic) is used, the irradiation fluence may be about 7,000 mJ / cm ^{2 at} the maximum. The pulse width may be 5 pico to 1000 nanoseconds, the pulse period may be 10 to 1000 microseconds, and the scanning speed may be about 10 to 5000 mm / min.

  Through the steps as described above, the frequency selection member 100 as shown in FIG. 5D can be obtained. In the frequency selection member 100, an appropriate space 135 is formed between the substrate 120 and the additional layer 140, more specifically, between the segments 130S of the conductive layer 130. Here, The material of the additional layer 140 is not filled.

  The frequency selection member obtained by the method of the present invention has a conventional problem, that is, the surface of the frequency selection member (that is, the exposed surface 139 of the additional layer 140) is uneven, or the adjacent segments 130S of the conductive layer 130 are adjacent to each other. The problem that the space 135 is blocked by another material can be significantly suppressed.

  Further, in general, in the patterning process of the conductive layer 130 ′ by laser light, fine pattern processing can be performed as compared with a conventional conductive layer installation technique such as a screen printing method. Therefore, in the method according to the present invention, the interval between adjacent segments 130S (W1 in FIG. 2) can be formed finer than in the prior art, and the degree of freedom of pattern formation of the conductive layer 130 is significantly increased. For example, W1 can be in the range of 10 nm to 100 nm. W1 is, for example, 50 nm.

(Radio wave absorber)
Such a frequency selection member 100 according to the present invention can be applied to a radio wave absorber. FIG. 7 schematically shows a cross-sectional view of an example of such a radio wave absorber 200. In FIG. 7, the dimensions of each member, particularly the thickness, are exaggerated and do not necessarily correspond to the actual dimensions.

  The radio wave absorber 200 according to the present invention includes the frequency selection member 100 having the above-described characteristics and a reflective member 270. In addition, a frame-shaped spacer 260 is interposed between the two, whereby a space portion 265 is formed inside the frame-shaped spacer 260.

  The frequency selection member 100 includes the transparent substrate 120, the patterned conductive layer 130, and the additional layer 140 as described above. The reflective member 270 includes a substrate 290 and a reflective film 280 installed on the substrate 290.

  Various materials can be used for the reflective film 280 depending on a required resistance value and transmittance. The reflective film 280 may have, for example, a multilayer structure in which oxide layers and metal layers are alternately stacked. The film thickness of the oxide layer is, for example, in the range of 10 to 100 nm. In other parts, it is the range of 40-140 nm, for example. On the other hand, the thickness of the metal layer is, for example, in the range of 5 to 50 nm.

  Usually, the oxide layer is composed of one or more metal oxides selected from the group consisting of aluminum oxide, zinc oxide, indium oxide, titanium oxide, niobium oxide, and tin oxide. In particular, the oxide layer is preferably composed of zinc oxide containing one or more elements selected from the group consisting of tin, aluminum, chromium, titanium, silicon, boron, magnesium, and gallium. On the other hand, the metal layer is preferably a layer made of a silver alloy containing one or more other metals selected from the group consisting of gold, palladium and bismuth.

  In FIG. 7, the frequency selection member 100 is disposed such that the additional layer 140 side is the outside and the transparent substrate 120 side is in contact with the space portion 265. However, the orientation of the frequency selection member 100 may be reversed. Similarly, in FIG. 7, the reflective member 270 is disposed so that the reflective film 280 side is in contact with the space portion 265. However, the direction of this arrangement may be reversed.

  Next, the operation of the radio wave absorber 200 configured as described above will be described.

  The radio wave absorber 200 includes the frequency selection member 100, and only unnecessary electromagnetic waves having a specific range of frequencies selectively enter the radio wave absorber 200 through the frequency selection member 100. The unnecessary electromagnetic wave 240 passes through the space portion 265 and reaches the surface of the reflective film 280 of the reflective member 270. The unnecessary electromagnetic wave 240 is reflected by the surface of the reflective film 280 and this time travels in the space 265 in the opposite direction. Thereafter, the unnecessary electromagnetic wave 240 passes through the frequency selection member 100 again and is emitted from the radio wave absorber 200. The thickness D2 of the space 265 is set so that the phase of the electromagnetic wave radiated from the radio wave absorber 200 is inverted by exactly 180 ° from the phase of the incident electromagnetic wave. Therefore, the electromagnetic wave incident on the radio wave absorber 200 is canceled by the electromagnetic wave radiated from the radio wave absorber, and as a result, the unnecessary electromagnetic wave can be eliminated.

  Here, in the radio wave absorber according to the present invention, since the frequency selection member 100 functions as a conventional FSS layer, the distance between the frequency selection member 100 and the reflective member 270, that is, the thickness D2 of the space portion 265 is significantly reduced. be able to. The thickness D2 of the space portion 265 is, for example, in a range of 2 cm to 3 cm when an electromagnetic wave of 1 GHz is targeted.

  Here, in the radio wave absorber according to the present invention, as described above, the conductive layer 130 of the frequency selection member 100 is appropriately patterned as compared with the conventional one. That is, the space 135 is not filled with a foreign material made of the material constituting the additional layer 140, and the space 135 remains appropriately. Further, the exposed surface of the additional layer 140 is substantially flat, and the unevenness of the surface is significantly suppressed.

  Therefore, in the radio wave absorber according to the present invention, it is possible to obtain appropriate radio wave absorption characteristics for a specific frequency range while keeping the overall thickness sufficiently thin. In addition, it is possible to provide a good-looking radio wave absorber without irregular reflection of light on the surface.

  Next, another radio wave absorber different from that shown in FIG. 7 will be described. FIG. 8 schematically shows a cross section of another electromagnetic wave absorber. In FIG. 8, the dimensions of each member, particularly the thickness, are exaggerated and do not necessarily correspond to actual dimensions.

  The radio wave absorber 300 is basically configured in the same manner as the radio wave absorber 200 shown in FIG. 7, and includes a reflective member 270 and a frequency selection member 101. In addition, a frame-shaped spacer 260 is interposed between the two, whereby a space portion 265 is formed inside the frame-shaped spacer 260. However, in the radio wave absorber 300, the frequency selection member 101 has an additional member that is not included in the frequency selection member 100 described above.

  More specifically, the frequency selection member 101 is configured by laminating a transparent substrate 120, a patterned conductive layer 130, an additional layer 140, and a reinforcing material 340 in this order. In addition, the adhesion layer 320 is arrange | positioned between the reinforcement material 340 and the additional layer 140, and, thereby, the additional layer 140 and the reinforcement material 340 are joined.

  The reinforcing material 340 is provided to give strength to the frequency selection member 101. Therefore, the thickness of the reinforcing material 340 is thicker than that of the transparent substrate 120, and the thickness is, for example, about 0.5 mm to 1 mm. The reinforcing material 340 may be made of, for example, polycarbonate or PET.

  Similarly, a reinforcing material 350 is laminated on the substrate 290 on the reflective layer side. An adhesive layer 330 is disposed between the reinforcing material 350 and the substrate 290, whereby the substrate 290 and the reinforcing material 350 are joined.

  In the radio wave absorber 300 having such a configuration, since the reinforcing members 340 and 350 can obtain high strength, it is possible to provide a radio wave absorber with higher durability.

  The present invention can be used for a radio wave absorber or the like.

It is the figure which showed typically an example of the manufacturing method of the frequency selection member used for the conventional electromagnetic wave absorber. It is sectional drawing which showed typically an example of the frequency selection member by this invention. It is the graph which showed the wavelength dependence of the absorptance about each transparent material. 3 is a flowchart of a method for manufacturing a frequency selection member according to the present invention. It is the figure which showed schematically the formation process of the frequency selection member by this invention. It is the figure which showed an example of the combination of the kind and wavelength of a laser beam, and the material of an additional layer. It is sectional drawing which showed typically an example of the electromagnetic wave absorber 200 by this invention. It is sectional drawing which showed typically an example of another electromagnetic wave absorber 300 by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conventional frequency selection member 20 Transparent base material 30 Conductive layer 30S Conductive oxide 32 Conductive oxide pattern 35 Gap 36 Recess 39 Exposed surface 40 Additional layer 100 Frequency selection member 101 by this invention Another frequency selection by this invention Member 110 Laser beam 120 Transparent substrate 130 Conductive layer (after pattern processing)
130 'conductive layer (before pattern processing)
130S segment 135 space 139 exposed surface 140 additional layer 200 radio wave absorber 240 according to the present invention 240 unwanted electromagnetic wave 260 spacer 265 space 270 reflective member 280 reflective film 290 substrate 300 another radio wave absorber 320 adhesive layer 330 adhesive layer 340 reinforcing material 350 Reinforcement.

Claims (12)

A frequency selective member for a radio wave absorber in which a transparent substrate, a conductive layer, and an additional layer provided to cover the surface of the conductive layer are laminated in this order,
The conductive layer is patterned into a plurality of segments, and spaces are formed between the segments.
The frequency selecting member for a radio wave absorber, wherein the additional layer is disposed on the conductive layer so that the space remains, and has a substantially flat exposed surface.   The frequency selection member for a radio wave absorber according to claim 1, wherein the width of the space between the segments is in the range of 10 nm to 100 nm. The transparent substrate substantially transmits laser light;
The conductive layer absorbs at least a portion of the laser beam;
The frequency selection member for a radio wave absorber according to claim 1, wherein the additional layer substantially reflects or transmits the laser light.   The conductive layer is made of at least one material selected from the group consisting of tin oxide, zinc oxide, silver, and ITO (indium tin oxide). The frequency selection member for electromagnetic wave absorbers as described.   The transparent substrate is composed of at least one material selected from the group consisting of PET (polyethylene terephthalate), PC (polycarbonate), TAC (triacetylcellulose), PEN (polyethylene naphthalate), and PMMA (polymethacrylate). The frequency selection member for a radio wave absorber according to any one of claims 1 to 4, wherein the frequency selection member is used. The laser beam is an Nd: YAG laser beam having a wavelength of about 1064 nm,
The additional layer includes at least one material selected from the group consisting of silicon nitride (SiN), silicon dioxide (SiO ₂ ), silicon carbide (SiC), and silicon oxynitride (SiON). The frequency selection member for electromagnetic wave absorbers in any one of Claims 1-5. The laser beam is an Nd: YAG laser beam (double wave) having a wavelength of about 532 nm,
The additional layer is at least one selected from the group consisting of aluminum nitride (AlN), hafnium dioxide (HfO ₂ ), magnesium difluoride (MgF ₂ ), silicon nitride (SiN), and silicon dioxide (SiO ₂ ). The frequency selection member for a radio wave absorber according to any one of claims 1 to 5, comprising a material. A reflective member composed of a substrate having a reflective film on the surface;
The frequency selection member according to claim 1,
An electromagnetic wave absorber comprising: (A) installing a conductive layer on the transparent substrate;
(B) installing an additional layer on the conductive layer;
(C) after the step of (b), patterning the conductive layer, substantially transmitting the transparent substrate, substantially transmitting or reflecting the additional layer, The conductive layer is selectively patterned by irradiating at least partly absorbed laser light from the substrate side; and
The manufacturing method of the frequency selection member for electromagnetic wave absorbers which has this.   10. The radio wave absorber according to claim 9, wherein the conductive layer is made of at least one material selected from the group consisting of tin oxide, zinc oxide, silver, and ITO (indium tin oxide). Method of producing a frequency selection member for use.   The transparent substrate is composed of at least one material selected from the group consisting of PET (polyethylene terephthalate), PC (polycarbonate), TAC (triacetylcellulose), PEN (polyethylene naphthalate), and PMMA (polymethacrylate). The method for producing a frequency selecting member for a radio wave absorber according to claim 9 or 10, wherein: The laser beam is an Nd: YAG laser beam having a wavelength of about 1064 nm,
The additional layer includes at least one material selected from the group consisting of silicon nitride (SiN), silicon dioxide (SiO ₂ ), silicon carbide (SiC), and silicon oxynitride (SiON). Item 12. A method for producing a frequency selecting member for a radio wave absorber according to any one of Items 9 to 11.

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