Electromagnetic wave shield

Abstract

To provide an electromagnetic wave shield that is advantageous from the viewpoint of achieving the shielding of obliquely incident electromagnetic waves with a simple configuration.SOLUTION: An electromagnetic wave shield 1a has a first surface 11 and a second surface 12. The electromagnetic wave shield 1a includes a dielectric. The first surface 11 is a surface for causing electromagnetic waves to be incident. The second surface 12 is a surface for causing at least part of the electromagnetic waves incident toward the first surface 11 to outgo. The electromagnetic wave shield 1a satisfies at least one condition selected from a group consisting of (I-1), (I-2), and (I-3) below when electromagnetic waves WEM are transmitted so as to be incident toward the first surface 11 at incident angles θ of 45°, 60°, and 75°: 10 Log|PR45 / PT45|≥5.0[dB] (I-1); 10 Log|PR60 / PT60|≥5.0[dB] (I-2); and 10 Log|PR75 / PT75|≥5.0[dB] (I-3).SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to an electromagnetic wave shield. [Background technology]

[0002] 2. Description of the Related Art Conventionally, it has been known to use a radio wave absorber to shield electromagnetic waves.

[0003] For example, Patent Documents 1 and 2 describe wave absorbers having a support, a resistive film, a dielectric layer, and a reflective layer. These wave absorbers exhibit a predetermined absorption performance for TM polarized waves, TE polarized waves, or circularly polarized waves incident at 45°. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6901629 [Patent Document 2] Patent No. 6901630 Summary of the Invention [Problem to be solved by the invention]

[0005] The radio wave absorbers described in Patent Documents 1 and 2 have a support, a resistive film, a dielectric layer, and a reflective layer. For example, it is understood that the resistive film needs to have a predetermined resistance value, and the reflective layer needs to be made of a material capable of reflecting radio waves, such as a metal film. For this reason, the radio wave absorbers described in Patent Documents 1 and 2 have room for reexamination from the perspective of realizing shielding of obliquely incident electromagnetic waves with a simpler configuration.

[0006] Therefore, the present invention provides an electromagnetic wave shield that is advantageous from the viewpoint of realizing shielding of obliquely incident electromagnetic waves with a simple configuration. [Means for solving the problem]

[0007] The present invention provides An electromagnetic wave shield, Contains a dielectric, a first surface for receiving an electromagnetic wave; a second surface for emitting at least a portion of the electromagnetic wave incident toward the first surface, When electromagnetic waves having at least one frequency in the range of 10 GHz to 300 GHz are transmitted so as to be incident on the first surface at angles of incidence of 45°, 60°, and 75°, at least one first condition selected from the group consisting of the following (I-1), (I-2), and (I-3) is satisfied: In the first condition, P T45 is the power [W] of the electromagnetic wave transmitted so that the incident angle is 45°, P R45 is the power [W] of the electromagnetic wave received at a receiving surface including an end point, at the outside, of a first line segment that extends from an incident point of the electromagnetic wave on the electromagnetic wave shield in a direction parallel to the incident direction of the electromagnetic wave, intersecting the second surface, to the outside of the electromagnetic wave shield, when the electromagnetic wave is transmitted so that the incident angle is 45°, P T60 is the power [W] of the electromagnetic wave transmitted so that the incident angle is 60°, P R60 is the power [W] of the electromagnetic wave received at a receiving surface including an end point, at the outside, of a second line segment that extends from an incident point of the electromagnetic wave on the electromagnetic wave shield in a direction parallel to the incident direction of the electromagnetic wave, intersecting the second surface, to the outside of the electromagnetic wave shield, when the electromagnetic wave is transmitted so that the incident angle is 60°, P T75 is the power [W] of the electromagnetic wave transmitted so that the incident angle is 75°, P R75 is the power [W] of the electromagnetic wave received at a receiving surface including an end point, at the outside, of a third line segment that extends from the incident point of the electromagnetic wave on the electromagnetic wave shield in a direction parallel to the incident direction of the electromagnetic wave, intersecting the second surface, to the outside of the electromagnetic wave shield, when the electromagnetic wave is transmitted so that the incident angle is 75°. Provides electromagnetic wave shielding. |10Log(P R45 / P T45 )|≧5.0[dB] (I-1) |10Log(P R60 / P T60 )|≧5.0[dB] (I-2) |10Log(P R75 / P T75 )|≧5.0[dB] (I-3) [Effects of the Invention]

[0008] The above-described electromagnetic wave shield is advantageous in that it can block obliquely incident electromagnetic waves with a simple configuration. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 1A is a perspective view showing an example of an electromagnetic wave shield according to the present invention. [Figure 1B] FIG. 1B is a side view of the electromagnetic wave shield shown in FIG. 1A. [Figure 1C] FIG. 1C is a plan view of the electromagnetic wave shield shown in FIG. 1A. [Figure 2] FIG. 2 is a diagram for explaining the conditions that the electromagnetic wave shield shown in FIG. 1A must meet. [Figure 3] FIG. 3 is a plan view showing another example of the electromagnetic wave shield according to the present invention. [Figure 4] FIG. 4 is a side view showing yet another example of the electromagnetic wave shield according to the present invention. [Figure 5A] FIG. 5A is a diagram showing a method for measuring return loss. [Figure 5B] FIG. 5B is a diagram showing a method for measuring the transmission attenuation. [Figure 6] FIG. 6 is a perspective view schematically showing the analysis model. [Figure 7] FIG. 7 is a perspective view showing an analytical model of an electromagnetic wave shield according to a comparative example. [Figure 8A] FIG. 8A is a graph showing the relationship between the transmission attenuation T and the ratio Sp / Se. [Figure 8B] FIG. 8B is a graph showing the relationship between the transmission attenuation T and the ratio Sp / Se. [Figure 8C] FIG. 8C is a graph showing the relationship between the transmission attenuation T and the ratio Sp / Se. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The present invention will be described with reference to the accompanying drawings, in which the x-axis, y-axis, and z-axis are perpendicular to one another.

[0011] As shown in FIGS. 1A, 1B, and 1C, the electromagnetic wave shield 1a has a first surface 11 and a second surface 12. The electromagnetic wave shield 1a includes a dielectric. The first surface 11 is a surface for receiving electromagnetic waves. The first surface 11 is, for example, a flat surface. The second surface 12 is a surface for emitting at least a portion of the electromagnetic waves that are incident toward the first surface 11. The second surface 12 is, for example, a flat surface.

[0012] 2 is a diagram for explaining the conditions that the electromagnetic wave shield 1a must satisfy. EM When the electromagnetic wave W is transmitted so as to be incident on the first surface 11 at an incident angle θ of 45°, 60°, or 75°, it satisfies at least one condition selected from the group consisting of the following (I-1), (I-2), and (I-3): EM has at least one frequency in the range of 10 GHz to 300 GHz. T45 is the electromagnetic wave W transmitted so that the incident angle θ is 45° EM The power [W] of R45 is the electromagnetic wave W so that the incident angle θ is 45° EM is the power [W] of the electromagnetic wave received at the receiving plane RP when T60 is the electromagnetic wave W transmitted so that the incident angle θ is 60° EM The power [W] of R60 is the electromagnetic wave W such that the incident angle θ is 60°EM is the power [W] of the electromagnetic wave received at the receiving plane RP when T75 is the electromagnetic wave W transmitted so that the incident angle θ is 75° EM The power [W] of R75 is the electromagnetic wave W such that the incident angle θ is 75° EM is the power [W] of the electromagnetic wave received at the receiving surface RP when the electromagnetic wave W EM When the incident angle θ is 45°, 60°, and 75°, the receiving surface RP includes an end point EP of the line segment LS that is outside the electromagnetic wave shield 1a. EM The electromagnetic wave W EM The incident point IP is, for example, the point at which the electromagnetic wave W EM The incident point corresponds to the center of the beam of electromagnetic wave W EM has a beam diameter of, for example, 30 mm. The receiving plane RP is a circle with a diameter of 30 mm that is perpendicular to the line segment LS and has the end point EP as its center. The distance between the end point EP and the electromagnetic wave shield 1a is, for example, 100 mm or more. |10Log(P R45 / P T45 )|≧5.0[dB] (I-1) |10Log(P R60 / P T60 )|≧5.0[dB] (I-2) |10Log(P R75 / P T75 )|≧5.0[dB] (I-3)

[0013] Power P T45 , P T60 , and P T75 As mentioned above, each of the transmitted electromagnetic waves W EM Power P T45 , P T60 , and P T75 For example, when the electromagnetic wave shield 1a is not installed, the electromagnetic wave W EMand the electromagnetic wave W EM Therefore, it is possible to receive and measure the power P T45 , P T60 , and P T75 Each of the transmitted electromagnetic waves W EM It does not have to be a directly measured power.

[0014] When the electromagnetic wave shield 1a satisfies at least one condition selected from the group consisting of (I-1), (I-2), and (I-3) above, the electromagnetic wave W transmitted to be incident on the electromagnetic wave shield 1a is EM is not limited to a specific type of electromagnetic wave. EM The electromagnetic wave may be a transverse magnetic wave (TM wave), a transverse electric wave (TE wave), a circularly polarized wave, or any other type of radio wave. For example, when at least one type of electromagnetic wave selected from the group consisting of a TM wave, a TE wave, and a circularly polarized wave is incident on the electromagnetic wave shield 1a, at least one condition selected from the group consisting of (I-1), (I-2), and (I-3) above may be satisfied.

[0015] As described above, the second surface 12 of the electromagnetic wave shield 1a transmits at least a portion of the electromagnetic waves incident toward the first surface 11. However, since the electromagnetic wave shield 1a satisfies at least one condition selected from the group consisting of (I-1), (I-2), and (I-3) above, it is advantageous from the perspective of shielding obliquely incident electromagnetic waves. In addition, the electromagnetic wave shield 1a can satisfy the above conditions as long as it contains a dielectric, even if it does not contain any material other than the dielectric. Therefore, the electromagnetic wave shield 1a is advantageous from the perspective of shielding obliquely incident electromagnetic waves with a simple configuration. In this specification, an electromagnetic wave shield is an article that can function to attenuate the energy of electromagnetic waves. The principle by which the electromagnetic wave shield attenuates the energy of electromagnetic waves is not limited to a specific principle. The principle may utilize, for example, phenomena such as reflection, transmission, absorption, diffraction, and interference associated with the interaction between the electromagnetic wave and the electromagnetic wave shield, as well as phenomena such as scattering and diffusion of the electromagnetic wave resulting from these phenomena.

[0016] The electromagnetic wave shield 1a preferably satisfies both the condition (I-1) and the condition (I-2). In this case, the electromagnetic wave shield 1a can easily block electromagnetic waves that are incident obliquely at various angles of incidence and prevent the effects of the electromagnetic waves from reaching a specific region.

[0017] The electromagnetic wave shield 1a does not have, for example, a conductive portion. To shield electromagnetic waves, it is conceivable to reflect the electromagnetic waves using a conductive portion such as a metal film. On the other hand, the electromagnetic wave shield 1a can satisfy at least one condition selected from the group consisting of (I-1), (I-2), and (I-3) above, even if it does not have a conductive portion. This makes it easy to shield obliquely incident electromagnetic waves with a simple configuration. The electromagnetic wave shield 1a may be composed only of a dielectric material, or may include a conductive portion.

[0018] The imaginary part ε″ of the relative permittivity of the dielectric material included in the electromagnetic wave shield 1a is not limited to a specific value. For example, the imaginary part ε″ of the relative permittivity of the dielectric material included in the electromagnetic wave shield 1a is set to a value that is equal to or greater than a specific value.g The imaginary part ε" of the dielectric constant of the dielectric in the above formula (I) is 0.1 or less. When attenuating electromagnetic waves by utilizing dielectric loss, it seems desirable that the value of the imaginary part ε" of the dielectric be large. On the other hand, according to the electromagnetic wave shield 1a, even if the imaginary part ε" of the dielectric constant of the dielectric is as small as 0.1 or less, at least one condition selected from the group consisting of the above (I-1), (I-2), and (I-3) can be satisfied by adjusting the phenomenon that occurs in the electromagnetic wave shield 1a due to the interaction between the electromagnetic wave and the electromagnetic wave. The imaginary part ε" may be 0.05 or less, or may be 0.01 or less.

[0019] The real part ε′ of the relative dielectric constant of the dielectric material included in the electromagnetic wave shield 1a is not limited to a specific value. For example, g The real part ε' of the relative permittivity of the dielectric in this case is 2.0 to 4.0. Even in such cases, at least one condition selected from the group consisting of (I-1), (I-2), and (I-3) above can be satisfied by adjusting the phenomenon that occurs in the electromagnetic wave shield 1a due to the interaction between the electromagnetic wave and the electromagnetic wave. The real part ε' may be 3.8 or less, 3.6 or less, 3.4 or less, 3.2 or less, 3.0 or less, 2.8 or less, 2.6 or less, or 2.4 or less.

[0020] The dielectric included in the electromagnetic wave shield 1a is not limited to a specific material. The dielectric may be, for example, a resin. The resin may be, for example, a thermoplastic resin. Examples of the resin include polyethylene, polypropylene, polyvinyl alcohol, polyethylene terephthalate, polybutylene terephthalate, ethylene-vinyl acetate copolymer, polystyrene, acrylonitrile styrene, acrylonitrile-butadiene-styrene copolymer, ASA resin, AES resin, acrylic resin such as PMMA, MS resin, MBS resin, cycloolefin resin, polyacetal resin, polyamide resin, polyester resin, polycarbonate resin, polyurethane resin, liquid crystal polymer, EPDM, PPS, PEEK, PPE, polysulfone resin, polyimide resin, fluorine-based resin, thermoplastic elastomer such as olefin-based thermoplastic elastomer (TPO), and acrylic elastomer. The resin may be a thermosetting resin. Examples of the thermosetting resin include epoxy resin, acrylic resin, and silicone resin. The dielectric may contain only a single type of resin or multiple types of resins.

[0021] The electromagnetic wave shield 1a may contain, for example, a filler. The filler may be a coloring material such as carbon black, an inorganic reinforcing material such as talc, glass fiber, or mineral, or a softener. The electromagnetic wave shield 1a may contain additives such as a flame retardant and a plasticizer. The electromagnetic wave shield 1a may not contain a filler. In this case, the manufacturing cost of the electromagnetic wave shield 1a tends to be low.

[0022] 1A, 1B, and 1C, the electromagnetic wave shield 1a has, for example, a plurality of protrusions 15. The plurality of protrusions 15 protrude from the first surface 11 in the direction opposite to the second surface 12, for example. The plurality of protrusions 15 may also protrude from the second surface 12 in the direction opposite to the first surface 11. With this configuration, even if the electromagnetic wave shield 1a has a simple configuration, it is likely to satisfy at least one condition selected from the group consisting of (I-1), (I-2), and (I-3) above.

[0023] The electromagnetic wave shield 1a can be used as an electromagnetic wave shield for applications such as millimeter-wave radar, millimeter-wave wireless communication, and millimeter-wave sensing. Devices incorporating the electromagnetic wave shield 1a can be used, for example, in automobiles and wireless base stations. When the electromagnetic wave shield 1a is for millimeter-wave radar, the electromagnetic wave shield 1a can be used for millimeter-wave radar operating in one frequency band selected from the group consisting of the 24 GHz band, the 60 GHz band, the 76 GHz band, and the 79 GHz band. The electromagnetic wave shield 1a does not necessarily block electromagnetic waves of a specific wavelength, but may block electromagnetic waves of a wide wavelength range. However, electromagnetic waves of a specific wavelength λ can be considered as the "target to be shielded." For example, in the case of an electromagnetic wave shield installed with an automotive millimeter-wave radar that substantially irradiates electromagnetic waves with a frequency of 76 to 77 GHz, i.e., a substantially irradiated wavelength of 3.89 to 3.94 mm, the wavelength λ of the center frequency of 76.5 GHz can be determined as the wavelength λ to be shielded by the electromagnetic wave shield. If the electromagnetic shield is described as being for an automotive millimeter-wave radar using electromagnetic waves with a frequency of 77 to 81 GHz, i.e., a wavelength of 3.70 to 3.89 mm, then 3.79 mm, which corresponds to the wavelength of the center frequency of 79 GHz, can be determined as the wavelength λ that the electromagnetic shield is intended to shield.If the electromagnetic shield is described as being for an automotive millimeter-wave radar using electromagnetic waves with a frequency of 24.05 to 24.25 GHz, i.e., a wavelength of 12.36 to 12.47 mm, then 12.41 mm, which corresponds to the wavelength of the center frequency of 24.15 GHz, can be determined as the wavelength λ that the electromagnetic shield is intended to shield. If it is stated that the electromagnetic wave shield is for millimeter wave radar, which uses electromagnetic waves with a frequency of 60.0 to 60.1 GHz, i.e., with a wavelength of 4.99 to 5.00 mm, then the wavelength λ of the center frequency of 60.05 GHz, 4.99 mm, can be determined to be the wavelength that this electromagnetic wave shield is intended to shield.If a product is marketed as an electromagnetic shield for millimeter-wave radio, where the frequency of the electromagnetic waves used is 27-29.5 GHz, i.e., the wavelength of the electromagnetic waves used is 10.16-11.10 mm, then 10.61 mm, which corresponds to the wavelength of the center frequency of 28.25 GHz, can be determined as the wavelength λ that the electromagnetic shield is intended to block. If a product is marketed as an electromagnetic shield for frequencies of 70-90 GHz, i.e., the wavelength of the center frequency of 3.33-4.28 mm, then 3.75 mm, which corresponds to the wavelength of the center frequency of 80 GHz, can be determined as the wavelength λ that the electromagnetic shield is intended to block.

[0024] The protruding length p of the protruding portion 15 i is not limited to a specific value. i is the dimension of the protrusion 15 in the protrusion direction of the protrusion 15. Protrusion length p i is compared with the specific wavelength λ that is the target of shielding by the electromagnetic wave shield, the protrusion length p i For example, 0.25λ≦p i 1B, in the electromagnetic wave shield 1a, the protrusion 15 protrudes in a direction perpendicular to the first plane 11.

[0025] Projection length p i The protrusion length p may be 0.30λ or more, 0.35λ or more, 0.40λ or more, 0.45λ or more, or 0.50λ or more. i may be 1.2λ or less, may be 1.1λ or less, may be 1.0λ or less, or may be 0.9λ or less.

[0026] For example, 50% or more of the protrusions 15 are in a range of 0.25λ≦p i ≦1.3λ. 60% or more of the protrusions 15 satisfy the condition of 0.25λ≦p i70% or more of the protrusions 15 may satisfy the condition of 0.25λ≦p i 80% or more of the protrusions 15 on a number basis may satisfy the condition of 0.25λ≦p i ≦1.3λ. 90% or more of the protrusions 15 on a number basis may satisfy the condition of 0.25λ≦p i All of the plurality of protrusions 15 may satisfy the condition of 0.25λ≦p i The condition of ≦1.3λ may be satisfied.

[0027] Width w of protrusion 15 i is not limited to a specific value. i The width w is the dimension of the outline of the protrusion 15 in the direction opposite to the protrusion direction, in which the distance between a pair of parallel straight lines tangent to the outline is the smallest. i When compared with the specific wavelength λ that is the target of shielding by the electromagnetic wave shield, the width w of at least one of the plurality of protrusions 15 i For example, 0.51λ≦w i ≦1.6λ is satisfied. This makes it easier for the electromagnetic wave shield 1a to exhibit the desired shielding performance when electromagnetic waves with a wavelength λ are incident on the electromagnetic wave shield 1a at an angle.

[0028] Width w i The width w may be 0.55λ or more, 0.60λ or more, 0.65λ or more, 0.70λ or more, or 0.75λ or more. i may be 1.5λ or less, may be 1.4λ or less, may be 1.3λ or less, may be 1.2λ or less, may be 1.1λ or less, or may be 1.0λ or less.

[0029] For example, 50% or more of the protrusions 15 are in a range of 0.51λ≦w i ≦1.6λ. 60% or more of the protrusions 15 meet the condition of 0.51λ≦w i70% or more of the protrusions 15 may satisfy the condition of 0.51λ≦w i 80% or more of the protrusions 15 may satisfy the condition of 0.51λ≦w i ≦1.6λ. 90% or more of the protrusions 15 may satisfy the condition of 0.51λ≦w i All of the plurality of protrusions 15 may satisfy the condition of 0.51λ≦w i The condition of ≦1.6λ may be satisfied.

[0030] Distance between protrusions 15 i i is not limited to a specific value. i is the shortest distance between the protrusions 15 in a direction parallel to the first surface 11 or the second surface 12. i When comparing with the specific wavelength λ that is the target of shielding by the electromagnetic wave shield, the interval i i For example, 0.51λ≦w i ≦1.6λ is satisfied. This makes it easier for the electromagnetic wave shield 1a to exhibit the desired shielding performance when electromagnetic waves with a wavelength λ are incident on the electromagnetic wave shield 1a at an angle.

[0031] Interval i i may be 0.55λ or more, 0.60λ or more, 0.65λ or more, 0.70λ or more, or 0.75λ or more. i may be 1.5λ or less, may be 1.4λ or less, or may be 1.3λ or less.

[0032] The shape of the protrusion 15 is not limited to a specific shape. For example, the protrusion 15 has at least one shape selected from the group consisting of a circle, a triangle, a rectangle, and a polygon with five or more corners in a plan view of the first surface 11 or the second surface 12. As shown in Fig. 1C, in the electromagnetic wave shield 1a, the protrusion 15 has, for example, a rectangular shape in a plan view of the first surface 11.

[0033] The protrusions 15 are formed to have at least one shape selected from the group consisting of a cylinder, a prism, a cone, a pyramid, a truncated cone, and a truncated pyramid, for example. The protrusions 15 may also be formed to have stripes.

[0034] The arrangement of the multiple protrusions 15 is not limited to a specific arrangement. For example, the multiple protrusions 15 may be arranged in at least one arrangement selected from the group consisting of an arrangement on lattice points, an arrangement on parallel lines, and a random arrangement when viewed from a plane on the first surface 11 or the second surface 12. This arrangement allows the electromagnetic wave shield 1a to easily exhibit the desired shielding performance over a wide range when electromagnetic waves of wavelength λ are obliquely incident on the electromagnetic wave shield 1a. The lattice points are points forming a planar lattice. The planar lattice is an arrangement of points on a plane that is invariant with parallel movement of a fixed distance in two independent directions. According to the arrangement on lattice points, the multiple protrusions 15 are arranged so that corresponding specific positions of the multiple protrusions 15 form a planar lattice. According to the arrangement on parallel lines, the multiple protrusions 15 are arranged so that corresponding specific linear portions of the multiple protrusions 15 form parallel lines. According to the random arrangement, the corresponding specific positions or linear portions of the multiple protrusions 15 are randomly arranged. As shown in FIG. 1C, in the electromagnetic wave shield 1a, the protrusions 15 are arranged, for example, on parallel lines that are equally spaced apart when the first surface 11 is viewed in plan.

[0035] The electromagnetic wave shield 1a satisfies at least one of the following conditions (II-1) and (II-2): With this configuration, when electromagnetic waves with a wavelength λ are obliquely incident on the electromagnetic wave shield 1a, the electromagnetic wave shield 1a is likely to exhibit the desired shielding performance over a wide range. p is the area of ​​the plurality of protrusions 15 when the first surface 11 or the second surface 12 is viewed in plan. e is the total area of ​​the electromagnetic wave shield 1a in plan view of the first surface 11. o is the total area of ​​the electromagnetic wave shield 1a in plan view of the second surface 12. 0.2≦S p / S e ≦0.8 (II-1) 0.2≦S p / S o ≦0.8 (II-2)

[0036] If the electromagnetic wave shield 1a satisfies the condition (II-1), S p / S e may be 0.25 or more, 0.30 or more, or 0.35 or more. p / S e may be 0.75 or less, may be 0.70 or less, may be 0.65 or less, or may be 0.60 or less.

[0037] 1A, 1B, and 1C, in the electromagnetic wave shield 1a, the first surface 11 and the second surface 12 are parallel to each other. In this case, the distance d between the first surface 11 and the second surface 12 is i is not limited to a specific value. i is, for example, 1 mm or more and 3 mm or less. In this case, the electromagnetic wave shield 1a can be easily formed.

[0038] The electromagnetic wave shield 1a is, for example, a resin molded product, which tends to reduce the manufacturing cost of the electromagnetic wave shield 1a.

[0039] The electromagnetic wave shield 1a can be modified from various perspectives. The electromagnetic wave shield 1a may be modified to an electromagnetic wave shield 1b shown in FIG. 3 or an electromagnetic wave shield 1c shown in FIG. 4. The electromagnetic wave shields 1b and 1c are each configured in the same manner as the electromagnetic wave shield 1a, except for portions that will be particularly described. The components of the electromagnetic wave shields 1b and 1c that correspond to the components of the electromagnetic wave shield 1a are denoted by the same reference numerals, and detailed description thereof will be omitted. The description of the electromagnetic wave shield 1a also applies to the electromagnetic wave shields 1b and 1c, unless technically inconsistent.

[0040] 3, in the electromagnetic wave shield 1b, the multiple protrusions 15 can be square-shaped when viewed from the top of the first surface 11. In addition, the multiple protrusions 15 are arranged on the lattice points of a parallelogram lattice. This configuration makes it easier for the electromagnetic wave shield 1b to exhibit the desired shielding performance when electromagnetic waves are obliquely incident on the electromagnetic wave shield 1b from various directions.

[0041] 4, in the electromagnetic wave shield 1c, the multiple protrusions 15 may protrude along a direction parallel to the first surface 11 and a direction inclined from a direction perpendicular to the first surface 11. With this configuration, even when the electromagnetic wave shield 1c needs to be formed so that the first surface 11 forms an inclined surface, the electromagnetic wave shield 1c is likely to exhibit the desired shielding performance against obliquely incident electromagnetic waves.

[0042] In the electromagnetic wave shields 1a, 1b, and 1c, the interaction between the electromagnetic wave shield and the electromagnetic waves that occurs to shield the electromagnetic waves is not limited to a specific interaction. Each of the electromagnetic wave shields 1a, 1b, and 1c, for example, transmits at least a portion of the radio waves incident toward the first surface 11 and emits the radio waves in a scattered state from the second surface 12. In other words, each of the electromagnetic wave shields 1a, 1b, and 1c can function as a radio wave-transmitting scatterer. This makes it easier to shield obliquely incident electromagnetic waves with a simple configuration.

[0043] Each of the electromagnetic wave shields 1a, 1b, and 1c has a scattering rate of, for example, 0.1% or more. The scattering rate is the ratio of the intensity of a specific transmitted scattered wave to the intensity of a straight transmitted wave that is emitted from the second output surface 12 when an electromagnetic wave is incident on the first surface 11 at a predetermined incident angle, and is determined, for example, according to the following formula (1). The intensity of the transmitted scattered wave in formula (1) is, for example, the sum of the intensities of the transmitted scattered waves having a scattering angle of (15 × k)°. The scattering angle is the angle between the emission direction of the straight transmitted wave and the emission direction of the transmitted scattered wave. k is an integer from 1 to n. For example, when the incident angle is 45°, n = 8; when the incident angle is 60°, n = 7; and when the incident angle is 75°, n = 6. Scattering rate = Intensity of transmitted scattered wave / Intensity of straight transmitted wave Equation (1)

[0044] The intensity of the transmitted scattered wave and the intensity of the straight transmitted wave can be determined, for example, by measuring the transmission attenuation in the straight direction and the transmission attenuation at a predetermined scattering angle when an electromagnetic wave is incident on the first surface 11 at a predetermined incident angle, with reference to Japanese Industrial Standard JIS R 1679:2007. The transmission attenuation is expressed by the following formula (2). In formula (2), P i is the received power and P0 is the transmitted power. i / P0| corresponds to the intensity of the transmitted wave. Transmission attenuation = |10Log(P i / P0)| Expression (2)

[0045] The scattering rate of each of the electromagnetic wave shields 1a, 1b, and 1c may be 1% or more, 5% or more, 10% or more, 20% or more, 50% or more, 100% or more, 150% or more, or 200% or more. [Example]

[0046] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0047] [Dielectric constant] Using a Keycom EAS02 radio wave transceiver, the return loss of a 2.0 mm thick polypropylene (PP) plate in the 70 to 90 GHz range was measured according to the procedure described below, with reference to Japanese Industrial Standard JIS R 1679:2007. As shown in Figure 5A, a sample holder SH, a millimeter-wave lens L, and a transceiver TR were arranged, and radio waves were transmitted and received with a stainless steel metal plate placed on the sample holder SH. The metal plate had a diameter of 150 mm and a thickness of 2 mm. The state in which the radio waves are completely reflected by the metal plate, resulting in a return loss of 0 dB, was used as the standard for measuring the return loss when radio waves are incident perpendicularly on the PP resin plate. A PP resin plate was placed on the sample holder SH instead of the metal plate, and radio waves were transmitted and received, and the return loss was measured.

[0048] Next, the transmission attenuation of the above-mentioned PP resin flat plate in the 70 to 90 GHz range was measured with reference to JIS R 1679:2007. For this measurement, the measurement system shown in Figure 5B was used. As shown in Figure 5B, this measurement system consisted of a sample holder SH, a millimeter-wave lens L, a transmitter T, and a receiver R. Radio waves E, transmitted from the transmitter T and adjusted to a 30 mm diameter (beam diameter) by the millimeter-wave lens L, were irradiated onto the sample holder SH. Radio waves E were transmitted and received with nothing placed in the sample holder SH. The state in which the transmission attenuation was 0 dB (total transmission of radio waves) was used as the reference for measuring the transmission attenuation of normal incidence relative to the surface direction of each sample. Next, a PP resin flat plate was placed on the sample holder SH, and then the receiver R was positioned so that the transmitter T and the receiver R were aligned in the perpendicular direction to the plate. In this state, radio waves E with a wavelength λ were transmitted and received, and the transmission attenuation was measured. The transmission attenuation is expressed as the absolute value calculated by the following equation (3): In equation (3), P i is the received power and P0 is the transmitted power. |10Log(P i / P0)| Expression (3)

[0049] The impedance Z and propagation constant γ of a material are expressed by the following equations (4) and (5). In equations (4) and (5), Z0 is the impedance of air. μ r is the relative permeability of the material, and μ r =μ r '-jμ r There is a relationship between ε and ε. r is the relative permittivity of the material, and ε r =ε r '-jε r '' is the relationship between λ and j. λ is the wavelength of radio waves. j is the imaginary unit. Z=Z0(μ r / ε r ) 0.5 Formula (4) γ=(j2π / λ)ε r 0.5 μ r 0.5 Formula (5)

[0050] When the thickness of the object is t, the return loss and transmission loss can be expressed by the above impedance Z and propagation constant γ using transmission line theory as follows: In equations (6) and (7), the relationships are A = cosh(γt), B = Z sinh(γt), C = (1 / Z) sinh(γt), and D = cosh(γt). Transmission attenuation (dB) = 20Log{2 / (A+B / Z0+CZ0+D)} Equation (6) Return loss (dB) = 20 Log {(A + B / Z0 - CZ0 - D) / (A + B / Z0 + CZ0 + D) Equation (7)

[0051] Relative permeability μ r and relative permittivity ε r The predicted values ​​of Z and γ were substituted into equations (6) and (7), and the return loss and transmission loss in the range of 70 to 90 GHz were calculated from equations (6) and (7) based on the obtained Z and γ and the thickness of the PP resin plate, 2.0 mm.

[0052] The curve of return loss calculated from the measured values ​​and the curve of return loss calculated from the above formulas (4), (5), and (7) were subjected to curve fitting using the least squares method. In addition, the curve of transmission loss calculated from the measured values ​​and the curve of transmission loss calculated from the above formulas (4), (5), and (6) were subjected to curve fitting using the least squares method. In this way, the most likely relative permittivity ε of PP was obtained. r As a result, the real part ε' and imaginary part ε" of the relative permittivity of PP were found to be 2.30 and 0.00, respectively.

[0053] [Electromagnetic field analysis] An electromagnetic field analysis of the analytical model M1 shown in Figure 6 was performed using Ansys' electromagnetic field analysis software HFSS "Version 2021R1." In analytical model M1, calculation target spaces V1 and V2 are defined. In analytical model M1, the electric field strength in calculation target spaces V1 and V2 was found by numerically solving Maxwell's equations. The finite element method was applied inside these calculation target spaces, and the moment method was applied at the boundaries of these calculation target spaces.

[0054] An evaluation object S1 was present in the calculation target space V1. Based on the measurement results of the dielectric constant of the PP described above, the real part ε' and imaginary part ε" of the dielectric constant of a part of the evaluation object S1 were set to 2.30 and 0.00, respectively. Furthermore, as shown in Tables 1 to 3, for comparison, the real part ε' of another part of the evaluation object S1 was set to 1.50 to 1.90. The evaluation object S1 was a plate-like object with multiple protrusions. The evaluation object S1 was a square with a side length of 70 mm in a plan view, and had multiple protrusions formed on one main surface of the 2.5 mm thick flat plate, the protrusions being ridges arranged at equal intervals on parallel straight lines in a plan view. The side of each protrusion was perpendicular to one main surface of the flat plate and inclined at an angle of 3° with respect to a plane parallel to the parallel straight line, narrowing in the protrusion direction. The corners of the tips of the protrusions were formed to have a radius of curvature of 0.5 mm. The protrusion length p i, the distance between the protrusions in a direction parallel to one of the main surfaces of the flat plate i i , and the width w of the protrusion at the boundary between one of the main surfaces of the flat plate and the protrusion i A plurality of evaluation objects S1 were prepared by adjusting the respective values ​​as shown in Table 1. In addition, when one main surface of the evaluation object S1 is viewed in plan, the total area S of the region where a plurality of protrusions exist on that main surface is e The area S occupied by multiple protrusions p The ratio S p / S e The results are shown in Tables 1 to 3. The other main surface of the evaluation object S1 was flat.

[0055] The electric field intensity in the calculation target space V1 and calculation target space V2 was calculated when TM waves with a 30 mm diameter (beam diameter) and a frequency of 76.5 GHz (wavelength λ: approximately 3.919 mm) were incident on the evaluation target S1 at angles of incidence of 45°, 60°, and 75° relative to one of the main surfaces of the evaluation target S1, which has multiple protrusions, or to the other flat main surface of the evaluation target S1. The amplitude direction of the electric field of the TM waves included a component parallel to the longitudinal direction of the protrusions. On the other hand, the component of the electric field amplitude direction of the TM waves parallel to one of the main surfaces of the flat plate and perpendicular to the longitudinal direction of the protrusions was zero.

[0056] The calculation target space V2 was located away from the evaluation target S1 and contained a receiving surface F. The receiving surface F was a circle with a diameter of 30 mm, and at the center of the circle was the endpoint of a line segment that ran from the incident point of the TM wave on the evaluation target S1 to the other principal surface or one of the principal surfaces and parallel to the direction of incidence of the TM wave. The distance between the center of the receiving surface F and the evaluation target S1 was set to 120 mm. The intersection of the line segment with the other principal surface of the evaluation target S1 was defined as the origin. The incident point was located on the same line as the center of the receiving surface F and the origin.

[0057] The transmission power P of the TM wave when it is incident on the evaluation target S1 at each incident angle θ Tθ [W] and the received power P of the electromagnetic wave at the receiving surface F RθBased on the calculated value of [W], the transmission attenuation T [dB] was calculated using the following formula (8). In the analytical model, when a TM wave is transmitted without an evaluation object being placed, the power of the electromagnetic wave received at the receiving surface F is expressed as the transmission power P Tθ The electric field strength was calculated when TM waves were incident on one of the principal surfaces of the evaluation object S1, which had multiple protrusions. In analyses Nos. 2 to 29, 31 to 58, and 60 to 81 in Tables 1 to 3, the electric field strength was calculated when TM waves were incident on the other flat principal surface of the evaluation object S1. The arrangement of the evaluation object S1 in the calculation object space V1 for analyses Nos. 82, 83, and 84 was flipped 180° from the arrangement of the evaluation object S1 in the calculation object space V1 for analyses Nos. 28, 57, and 81, respectively. T=|10Log(P Rθ / P Tθ )| Expression (8)

[0058] An analytical model M2 was created in the same manner as analytical model M1, except that an evaluation object S2 shown in Figure 7 was used instead of evaluation object S1. Evaluation object S2 is a flat plate with a square shape with a side length of 70 mm in plan view and a thickness of 2.5 mm. There are no protrusions on either main surface of evaluation object S2, and both main surfaces are flat. The real and imaginary parts of the relative permittivity of evaluation object S2 were set to 2.30 and 0.00, respectively.

[0059] The electric field strength was calculated in the calculation target space V1 and the calculation target space V2 when a TM wave with a frequency of 76.5 GHz (wavelength λ: approximately 3.919 mm) having a diameter (beam diameter) of 30 mm was incident on the evaluation target S1 at an incident angle of 45°, 60°, and 75° to one of the main surfaces of the evaluation target S2. The transmission power P of the TM wave when incident on the evaluation target S2 at each incident angle θ was calculated. Tθ [W] and the received power P of the electromagnetic wave at the receiving surface F Rθ Based on the calculated value of [W], the transmission attenuation T [dB] was calculated using the above formula (8). The results are shown in Tables 1 to 3. Analysis Nos. 1, 30, and 59 in Tables 1 to 3 show the analysis conditions and analysis results of the analysis model M2 including the evaluation object S2.

[0060] As shown in Tables 1 to 3, in Analysis Nos. 1, 30, and 59 for the analytical model M2 including the evaluation object S2, the transmission attenuation T was less than 5 dB. In addition, in Analysis Nos. 2, 10, 32, 36, and 38 to 40, in which the real part of the relative dielectric constant of the evaluation object S1 was less than 2.0, the transmission attenuation T was less than 5 dB. This suggests that in the analytical model M1 in which the evaluation object S1 has multiple protrusions, the transmission attenuation T can be made 5 dB or more by adjusting the relative dielectric constant and the dimensions of the protrusions.

[0061] Figure 8A shows the transmission attenuation T and ratio S for analyses Nos. 2 to 28. p / S e 8B is a graph showing the relationship between the transmission attenuation T and the ratio S in analysis Nos. 29 and 31 to 57. p / S e 8C is a graph showing the relationship between the transmission attenuation T and the ratio S in analysis Nos. 58 and 60 to 81. p / S e 8A to 8C are graphs showing the relationship between the ratio S p / S e It was suggested that when is small, the transmission attenuation T tends to be large.

[0062] A first aspect of the present invention is An electromagnetic wave shield, Contains a dielectric, a first surface for receiving an electromagnetic wave; a second surface for emitting at least a portion of the electromagnetic wave incident toward the first surface, When electromagnetic waves having at least one frequency in the range of 10 GHz to 300 GHz are transmitted so as to be incident on the first surface at angles of incidence of 45°, 60°, and 75°, at least one first condition selected from the group consisting of the following (I-1), (I-2), and (I-3) is satisfied: In the first condition, P T45 is the power [W] of the electromagnetic wave transmitted so that the incident angle is 45°, P R45 is the power [W] of the electromagnetic wave received at a receiving surface including an end point, at the outside, of a first line segment that extends from an incident point of the electromagnetic wave on the electromagnetic wave shield in a direction parallel to the incident direction of the electromagnetic wave, intersecting the second surface, to the outside of the electromagnetic wave shield, when the electromagnetic wave is transmitted so that the incident angle is 45°, P T60 is the power [W] of the electromagnetic wave transmitted so that the incident angle is 60°, P R60 is the power [W] of the electromagnetic wave received at a receiving surface including an end point, at the outside, of a second line segment that extends from an incident point of the electromagnetic wave on the electromagnetic wave shield in a direction parallel to the incident direction of the electromagnetic wave, intersecting the second surface, to the outside of the electromagnetic wave shield, when the electromagnetic wave is transmitted so that the incident angle is 60°, P T75 is the power [W] of the electromagnetic wave transmitted so that the incident angle is 75°, P R75 is the power [W] of the electromagnetic wave received at a receiving surface including an end point, at the outside, of a third line segment that extends from the incident point of the electromagnetic wave on the electromagnetic wave shield in a direction parallel to the incident direction of the electromagnetic wave, intersecting the second surface, to the outside of the electromagnetic wave shield, when the electromagnetic wave is transmitted so that the incident angle is 75°. Provides electromagnetic wave shielding. |10Log(P R45 / P T45 )|≧5.0[dB] (I-1) |10Log(P R60 / P T60 )|≧5.0[dB] (I-2) |10Log(P R75 / P T75 )|≧5.0[dB] (I-3)

[0063] A second aspect of the present invention is the method for manufacturing a semiconductor device according to the first aspect, The electromagnetic wave shield does not have a conductive portion.

[0064] A third aspect of the present invention is the method according to the first or second aspect, The electromagnetic wave shield is provided, wherein the imaginary part ε″ of the relative permittivity of the dielectric material is 0.1 or less at at least one frequency within the range of 10 GHz to 300 GHz.

[0065] A fourth aspect of the present invention is any one of the first to third aspects, The electromagnetic wave shield is provided, wherein the real part ε' of the relative dielectric constant of the dielectric material is 2.0 to 4.0 at at least one frequency within the range of 10 GHz to 300 GHz.

[0066] A fifth aspect of the present invention is any one of the first to fourth aspects, The electromagnetic wave shield satisfies both the condition (I-1) and the condition (I-2).

[0067] A sixth aspect of the present invention is directed to any one of the first to fifth aspects, An electromagnetic wave shield is provided having a plurality of protrusions protruding from the first surface in a direction opposite to the second surface, or protruding from the second surface in a direction opposite to the first surface.

[0068] A seventh aspect of the present invention is the method according to the sixth aspect, The electromagnetic wave shield is configured to block electromagnetic waves having a wavelength λ, At least one of the plurality of protrusions has a protrusion length p i , 0.25λ≦p i Satisfy the condition of ≦1.3λ Provides electromagnetic wave shielding.

[0069] An eighth aspect of the present invention is the sixth or seventh aspect, The electromagnetic wave shield is configured to block electromagnetic waves having a wavelength λ, The width w of at least one of the plurality of protrusions i is 0.51λ≦w i Satisfy the condition of ≦1.6λ Provides electromagnetic wave shielding.

[0070] A ninth aspect of the present invention is the method according to any one of the sixth to eighth aspects, The electromagnetic wave shield is configured to block electromagnetic waves having a wavelength λ, The distance between the protrusions i i is 0.51λ≦i i Satisfy the condition of ≦1.6λ Provides electromagnetic wave shielding.

[0071] A tenth aspect of the present invention is the method according to any one of the sixth to ninth aspects, The protrusion has at least one shape selected from the group consisting of a circle, a triangle, a rectangle, and a polygon having five or more corners in a plan view of the first surface or the second surface. Provides electromagnetic wave shielding.

[0072] An eleventh aspect of the present invention is the method according to the tenth aspect, An electromagnetic wave shield is provided in which the plurality of protrusions, when viewed in a plane on the first surface or the second surface, take on at least one arrangement selected from the group consisting of an arrangement on lattice points, an arrangement on parallel lines, and a random arrangement.

[0073] A twelfth aspect of the present invention is the method according to any one of the sixth to eleventh aspects, The electromagnetic wave shield satisfies at least one second condition selected from the group consisting of the following conditions (II-1) and (II-2): In the second condition, S p is the area of ​​the plurality of protrusions when viewed in plan view of the first surface or the second surface, S e is the total area of ​​the electromagnetic wave shield in a plan view of the first surface, S o is the total area of ​​the electromagnetic wave shield in a plan view of the second surface, Provides electromagnetic wave shielding. 0.2≦S p / S e≦0.8 (II-1) 0.2≦S p / S o ≦0.8 (II-2)

[0074] [Table 1]

[0075] [Table 2]

[0076] [Table 3]

[0077] [Table 4] [Explanation of symbols]

[0078] 1a, 1b, 1c Electromagnetic wave shield 11 Front page 12 Second side 15 Protrusion EP endpoint RP receiving surface IP point of entry

Claims

1. 1. An electromagnetic wave shield, comprising: Including a dielectric a first surface for receiving an electromagnetic wave; a second surface for emitting at least a portion of the electromagnetic wave incident toward the first surface, When electromagnetic waves W EM having at least one frequency in the range of 10 GHz to 300 GHz are transmitted so as to be incident on the first surface at angles of incidence of 45°, 60°, and 75°, at least one first condition selected from the group consisting of the following (I-1), (I-2), and (I-3) is satisfied, In the first condition, P T45 is the power [W] of the electromagnetic wave W EM transmitted so that the incident angle is 45°, P R45 is the power [W] of the electromagnetic wave received at a receiving surface including an end point at the outside of a first line segment that extends from an incident point of the electromagnetic wave W EM on the electromagnetic wave shield in a direction parallel to the incident direction of the electromagnetic wave W EM, intersecting the second surface, to the outside of the electromagnetic wave shield, when the electromagnetic wave W EM is transmitted so that the incident angle is 45°, P T60 is the power [W] of the electromagnetic wave W EM transmitted so that the incident angle is 60°, P R60 is the power [W] of the electromagnetic wave received at a receiving surface including an end point at the outside of a second line segment that extends from an incident point of the electromagnetic wave W EM on the electromagnetic wave shield in a direction parallel to the incident direction of the electromagnetic wave W EM, intersecting the second surface, to the outside of the electromagnetic wave shield, when the electromagnetic wave W EM is transmitted so that the incident angle is 60°, P T75 is the power [W] of the electromagnetic wave W EM transmitted so that the incident angle is 75°, P R75 is the power [W] of the electromagnetic wave received at a receiving surface including an end point at the outside of the electromagnetic wave shield of a third line segment that extends from an incident point of the electromagnetic wave W EM on the electromagnetic wave shield in a direction parallel to the incident direction of the electromagnetic wave W EM, intersecting the second surface, to the outside of the electromagnetic wave shield, when the electromagnetic wave W EM is transmitted so that the incident angle is 75°; Electromagnetic wave shielding. |10Log(P R45 / P T45 )|≧5.0[dB] (I-1) |10Log(P R60 / P T60 )|≧5.0[dB] (I-2) |10Log(P R75 / P T75 )|≧5.0[dB] (I-3)

2. The electromagnetic wave shield according to claim 1 , wherein the electromagnetic wave shield does not have a conductive portion.

3. 2. The electromagnetic wave shield according to claim 1, wherein the imaginary part ε″ of the relative dielectric constant of the dielectric material at at least one frequency included in the range of 10 GHz to 300 GHz is 0.1 or less.

4. 2. The electromagnetic wave shield according to claim 1, wherein the real part ε' of the relative dielectric constant of the dielectric material at at least one frequency included in the range of 10 GHz to 300 GHz is 2.0 to 4.

0.

5. 2. The electromagnetic shield according to claim 1, wherein the electromagnetic shield satisfies both the condition (I-1) and the condition (I-2).

6. 2. The electromagnetic wave shield of claim 1, comprising a plurality of protrusions protruding from the first surface in a direction opposite to the second surface, or protruding from the second surface in a direction opposite to the first surface.

7. The electromagnetic wave shield is intended to block electromagnetic waves having a wavelength λ, At least one of the plurality of protrusions has a protrusion length p i 0.25λ≦p i Satisfy the condition of ≦1.3λ; 7. The electromagnetic wave shield according to claim 6.

8. The electromagnetic wave shield is intended to block electromagnetic waves having a wavelength λ, The width w of at least one of the plurality of protrusions i 0.51 λ ≦ w i Satisfy the condition of ≦1.6λ, 7. The electromagnetic wave shield according to claim 6.

9. The electromagnetic wave shield is intended to block electromagnetic waves having a wavelength λ, The distance between the protrusions i i 0.51 λ≦i i Satisfy the condition of ≦1.6λ, 7. The electromagnetic wave shield according to claim 6.

10. 7. The electromagnetic wave shield according to claim 6, wherein the protrusion has at least one shape selected from the group consisting of a circle, a triangle, a rectangle, and a polygon having five or more corners, when viewed in a plan view of the first surface or the second surface.

11. 11. The electromagnetic shield according to claim 10, wherein the plurality of protrusions, when viewed in a plan view of the first surface or the second surface, have at least one arrangement selected from the group consisting of an arrangement on lattice points, an arrangement on parallel lines, and a random arrangement.

12. The electromagnetic wave shield satisfies at least one second condition selected from the group consisting of the following conditions (II-1) and (II-2): In the second condition, S p is an area of ​​the plurality of protrusions when viewed in a plan view of the first surface or the second surface, S e is the total area of ​​the electromagnetic wave shield in a plan view of the first surface, S o is the total area of ​​the electromagnetic wave shield in a plan view of the second surface, 7. The electromagnetic wave shield according to claim 6. .. ≦ p + e ≦...(II)) .. ≦ p + o ≦...(II).

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