TWI869564B - Electromagnetic wave permeable multilayer structure and manufacturing method thereof - Google Patents

Abstract

The electromagnetic wave transparent multilayer component of the present invention comprises: a substrate, an indium oxide layer formed on the substrate, and a metal layer formed on the indium oxide layer, wherein the metal layer includes a plurality of parts which are discontinuous with each other in at least a part, and the ratio of oxygen atoms to indium atoms and the total ratio of at least one metal atom of Sn and Zn (O/(In+M) ratio) when measuring the surface of the indium oxide layer by X-ray photoelectron spectroscopy is less than 1.15.

Description

Electromagnetic wave transparent multilayer structure and manufacturing method thereof

The present invention relates to an electromagnetic wave permeable multilayer component and a manufacturing method thereof.

Conventionally, components having electromagnetic wave permeability and metallic luster have been suitably used in devices for transmitting and receiving electromagnetic waves because they have both a high-end appearance due to their metallic luster and electromagnetic wave permeability.

When metal is used for a component with a metallic luster, the transmission and reception of electromagnetic waves is substantially impossible or hindered. Therefore, in order not to hinder the transmission and reception of electromagnetic waves and not to damage the design, an electromagnetic wave permeable multilayer component having both metallic luster and electromagnetic wave permeability is required.

Such electromagnetic wave-transmissive multilayer components are expected to be used as devices for transmitting and receiving electromagnetic waves in various devices that require communication, such as door handles of cars equipped with smart keys, in-car communication devices, mobile phones, personal computers and other electronic devices. Furthermore, in recent years, with the development of IoT technology, applications in a wide range of fields such as refrigerators and other household appliances that did not previously communicate are also expected.

Regarding electromagnetic wave transparent laminated components, Patent Document 1 describes an electromagnetic wave transparent metallic glossy component, which is characterized by having: an indium oxide-containing layer disposed on a surface of a substrate, and a metal layer laminated on the indium oxide-containing layer, and the metal layer includes a plurality of parts that are discontinuous with each other in at least a portion. [Prior art document] [Patent document]

Patent document 1: Japanese Patent Application Publication No. 2018-69462

[The problem the invention is trying to solve]

The metal layer of the electromagnetic wave transparent multilayer component of the prior art depends on its formation method and the type of substrate, but can only be formed to a thickness of about 50 nm. If the thickness is greater than this, the metal is formed into islands and overlaps each other, and the resistance value decreases sharply, so the electromagnetic wave transmittance is significantly impaired. Therefore, the thickness of the metal layer must be managed at the level of several nanometers, which makes it difficult to achieve stable production and causes the problem of reduced yield.

The present invention is completed to solve the above-mentioned problems of the prior art, and its purpose is to provide an electromagnetic wave transparent multilayer component with excellent electromagnetic wave transmittance and the thickness of the metal layer can be controlled within a wide range. [Technical means to solve the problem]

The inventors of the present invention have conducted repeated and in-depth studies to solve the above-mentioned problems and have found that the above-mentioned problems can be solved by setting the oxygen concentration of the indium oxide-containing layer within a specific range, thereby completing the present invention.

That is, the present invention is as follows. [1] An electromagnetic wave transparent multilayer structure comprising: a substrate, an indium oxide-containing layer formed on the substrate, and a metal layer formed on the indium oxide-containing layer; wherein the metal layer includes a plurality of portions that are discontinuous with each other in at least a portion; and when the surface of the indium oxide-containing layer is measured by X-ray photoelectron spectroscopy, the ratio of oxygen atoms to indium atoms and the total of at least one metal atom M of Sn and Zn (O/(In+M) ratio) is 1.15 or less. [2] An electromagnetic wave transparent multilayer structure as described in [1] above, wherein the indium oxide-containing layer is provided in a continuous state. [3] The electromagnetic wave transparent multilayer structure as described in [1] or [2] above, wherein the indium oxide-containing layer contains any one of indium oxide (In ₂ O ₃ ), indium tin oxide (ITO), or indium zinc oxide (IZO). [4] The electromagnetic wave transparent multilayer structure as described in any one of [1] to [3] above, wherein the metal layer is a layer containing aluminum or an aluminum alloy. [5] The electromagnetic wave transparent multilayer structure as described in any one of [1] to [4] above, wherein the thickness of the indium oxide-containing layer is 1 nm to 1000 nm. [6] The electromagnetic wave transparent multilayer structure as described in any one of [1] to [5] above, wherein the thickness of the metal layer is 10 nm to 200 nm. [7] An electromagnetic wave transparent multilayer structure as described in any one of [1] to [6] above, wherein the ratio of the thickness of the metal layer to the thickness of the indium oxide-containing layer (thickness of the metal layer/thickness of the indium oxide-containing layer) is 0.02 to 100. [8] An electromagnetic wave transparent multilayer structure as described in any one of [1] to [7] above, wherein the sheet resistance is 100 Ω/□ or more. [9] An electromagnetic wave transparent multilayer structure as described in any one of [1] to [8] above, wherein the plurality of portions are formed into an island shape. [10] An electromagnetic wave transparent multilayer structure as described in any one of [1] to [9] above, wherein the substrate is any one of a substrate film, a resin molded substrate, a glass substrate, or an article to be given a metallic luster. [11] A method for manufacturing an electromagnetic wave transparent multilayer component according to any one of [1] to [10], comprising: an indium oxide layer forming step of forming an indium oxide layer on a substrate; and a metal layer forming step of forming a metal layer on the indium oxide layer; wherein the indium oxide layer forming step uses a metal target containing indium as a main component, and forms the indium oxide layer on the substrate by reactive sputtering while supplying an inert gas and oxygen. [Effects of the Invention]

According to the present invention, an electromagnetic wave transparent multilayer component can be provided, which has excellent electromagnetic wave transmittance and can control the thickness of the metal layer within a wide range.

The present invention is described in detail below with reference to the attached drawings, but the present invention is not limited to the following embodiments and can be implemented with any changes without departing from the gist of the present invention. In addition, "~" indicating a numerical range is used to include the numerical values before and after it as the lower limit and the upper limit.

<1. Basic structure> The electromagnetic wave transparent multilayer component of the embodiment of the present invention is characterized by comprising: a substrate, an indium oxide layer formed on the substrate, and a metal layer formed on the indium oxide layer; and the metal layer includes a plurality of parts that are discontinuous with each other in at least a part, and the ratio of oxygen atoms to indium atoms and at least one metal atom M of Sn and Zn (O/(In+M) ratio) when measuring the surface of the indium oxide layer by X-ray photoelectron spectroscopy is less than 1.15.

FIG1(a) shows a schematic cross-sectional view of an electromagnetic wave transparent multilayer member 1 according to an embodiment of the present invention, and FIG1(b) shows an example of an electron microscope photograph (SEM image) of the surface of the electromagnetic wave transparent multilayer member 1 according to an embodiment of the present invention. The image size of the electron microscope photograph is 1.2 μm×0.9 μm.

As shown in FIG. 1( a ), the electromagnetic wave transparent multilayer structure 1 includes: a substrate 10 , an indium oxide-containing layer 11 formed on the substrate 10 , and a metal layer 12 formed on the indium oxide-containing layer 11 .

The indium oxide-containing layer 11 is disposed on the surface of the substrate 10. The indium oxide-containing layer 11 may be disposed directly on the surface of the substrate 10, or may be disposed indirectly via a protective film or the like disposed on the surface of the substrate 10.

The indium oxide containing layer 11 is preferably provided in a continuous state, in other words, without gaps, on the surface of the substrate 10. By providing it in a continuous state, the smoothness and corrosion resistance of the indium oxide containing layer 11 and even the electromagnetic wave transparent multilayer component 1 can be improved, and the indium oxide containing layer 11 can be easily formed uniformly in the surface.

The metal layer 12 is stacked on the indium oxide-containing layer 11. The metal layer 12 includes a plurality of portions 12a. By being stacked on the indium oxide-containing layer 11, the portions 12a are discontinuous with each other in at least a portion, in other words, are separated by gaps 12b in at least a portion. Since the portions 12a are separated by gaps 12b, the sheet resistance of the portions 12a increases, and since the interaction with the radio waves is reduced, the radio waves can pass through.

Each of the portions 12a is a collection of sputtered particles formed by evaporating or sputtering a metal. When the sputtered particles form a thin film on a substrate such as the substrate 10, the surface diffusion of the particles on the substrate affects the shape of the thin film.

In addition, the "discontinuous state" mentioned in this specification means a state where the sheets are separated from each other by the gap 12b and are electrically insulated from each other. By being electrically insulated, the sheet resistance becomes larger, and the desired electromagnetic wave permeability is obtained. The form of the discontinuity is not particularly limited, and includes, for example, islands, cracks, etc.

Here, "island-like" refers to a structure in which the particles are independent of each other, slightly separated from each other, or partially in contact with each other, as shown in the electron microscope photograph (SEM image) of the surface of the metal layer of the electromagnetic wave-transmissive multilayer component in Figure 1(b).

Furthermore, the crack structure is a structure in which the metal film is divided by cracks. The metal layer 12 with the crack structure can be formed, for example, by providing a metal film layer on an indium oxide-containing layer formed on a substrate, and bending and stretching it to generate cracks in the metal film layer. At this time, the metal layer 12 with the crack structure can be easily formed by providing a brittle layer made of a material with poor elasticity, that is, a material that is easy to generate cracks by stretching, between the indium oxide-containing layer and the metal film layer.

As described above, the discontinuous state of the metal layer 12 is not particularly limited, but it is preferably set to be an "island shape" from the perspective of production efficiency.

Electromagnetic wave permeability The electromagnetic wave permeability of the laminated member 1 can be evaluated by, for example, the amount of electromagnetic wave permeability attenuation. The amount of electromagnetic wave permeability attenuation can be measured by, for example, the method described later in the embodiment.

In addition, since there is a correlation between the radio wave transmission attenuation in the microwave band (28 GHz) and the radio wave transmission attenuation in the millimeter wave radar band (76-80 GHz), the values are relatively close, and the electromagnetic wave transparent multilayer structure with excellent electromagnetic wave transmittance in the microwave band is also excellent in electromagnetic wave transmittance in the millimeter wave radar band.

The attenuation of microwave band (28 GHz) radio waves is preferably less than 10[-dB], more preferably less than 5[-dB], and most preferably less than 2[-dB]. If the attenuation of microwave band (28 GHz) radio waves is more than 10[-dB], more than 90% of the radio waves will be cut off.

The sheet resistance of the electromagnetic wave permeable multilayer structure 1 is also correlated with the electromagnetic wave permeability.

The sheet resistance of the electromagnetic wave transparent multilayer member 1 is preferably 100 Ω/□ or more. In this case, the electromagnetic wave transmission attenuation in the microwave band (28 GHz) can be set to less than 10[-dB].

The sheet resistance of the electromagnetic wave transparent multilayer member 1 is more preferably 200 Ω/□ or more, further preferably 600 Ω/□ or more, and particularly preferably 1000 Ω/□ or more.

The sheet resistance of the electromagnetic wave permeable multilayer member 1 can be measured by the eddy current measurement method in accordance with JIS-Z2316-1:2014.

The electromagnetic wave transmission attenuation and sheet resistance of the electromagnetic wave transparent multilayer component 1 are affected by the material or thickness of the indium oxide layer 11 or the metal layer 12.

<2. Substrate> Based on the electromagnetic wave permeability, the substrate 10 may be, for example, resin, glass, ceramic, etc.

The substrate 10 may be a substrate film, a resin molded product substrate, a glass substrate, or any object to be given a metallic luster.

More specifically, as the substrate film, for example, a transparent film comprising a homopolymer or copolymer of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate, polyamide, polyvinyl chloride, polycarbonate (PC), cycloolefin polymer (COP), polystyrene, polypropylene (PP), polyethylene, polycycloolefin, polyurethane, polyacrylic polymer (PMMA), ABS, etc. can be used.

According to these components, the brightness and electromagnetic wave transmittance are not affected. However, from the perspective of the subsequent formation of the indium oxide layer 11 and the metal layer 12, it is preferred that the layer be resistant to high temperatures such as evaporation or sputtering.

Therefore, among the above materials, for example, polyethylene terephthalate, polyethylene naphthalate, polyacrylic polymer, polycarbonate, cycloolefin polymer, ABS, polypropylene, and polyurethane are preferred.

Among them, polyethylene terephthalate, cycloolefin polymers, polycarbonate, and polyacrylic acid polymers are preferred because of their good balance between heat resistance and cost.

The substrate film may be a single-layer film or a multilayer film. Based on ease of processing, the thickness is preferably 6 μm to 250 μm, for example.

The substrate film may be subjected to plasma treatment or bonding treatment to enhance adhesion with the indium oxide-containing layer 11 and the metal layer 12. In addition, the substrate film is preferably free of particles.

Here, it should be noted that the base film is only one example of an object (substrate 10) on the surface of which the indium oxide-containing layer 11 may be formed.

As described above, the base 10 includes, in addition to the base film, a resin molded material base, a glass base, and the object itself to be given a metallic luster.

Examples of resin molding substrates and articles to be given a metallic luster include: vehicle structural parts, vehicle accessories, electronic equipment casings, home appliance casings, structural parts, mechanical parts, various automotive parts, electronic equipment parts, furniture, kitchen supplies and other movable products for daily use, medical equipment, building material parts, other structural parts, and exterior parts.

<3. Indium oxide-containing layer> The indium oxide-containing layer 11 is formed on the substrate 10. The indium oxide-containing layer 11 may be directly disposed on the surface of the substrate 10, or may be indirectly disposed via a protective film or the like disposed on the surface of the substrate 10.

The indium oxide-containing layer 11 is preferably provided in a continuous state, in other words, without gaps, on the surface of the substrate 10 to be given a metallic luster. By providing the indium oxide-containing layer 11 in a continuous state, the smoothness and corrosion resistance of the indium oxide-containing layer 11, and even the metal layer 12 and the electromagnetic wave transparent multilayer component 1 can be improved. In addition, it is also easy to form the indium oxide-containing layer 11 without unevenness in the surface.

In this way, by providing the indium oxide-containing layer 11 on the substrate 10, that is, by forming the indium oxide-containing layer 11 on the substrate 10 and depositing the metal layer 12 described later thereon, it is easy to form the metal layer 12 in a discontinuous state.

The details of the above mechanism may not be clear, but it is believed that when the sputtering particles formed by metal evaporation or sputtering form a thin film on the substrate, the surface diffusion of the particles on the substrate affects the shape of the thin film. The higher the temperature of the substrate and the lower the wettability of the metal layer to the substrate, the more likely it is to form a discontinuous structure. In addition, it is believed that by providing an indium oxide layer on the substrate, the surface diffusion of the metal particles on its surface is promoted, making it easier for the metal layer to grow in a discontinuous state.

Furthermore, in the electromagnetic wave transparent multilayer structure of the embodiment of the present invention, the indium oxide layer 11 is characterized in that the ratio of oxygen atoms to indium atoms and at least one metal atom M of Sn and Zn (O/(In+M) ratio) when the surface is measured by X-ray photoelectron spectroscopy is less than 1.15.

By setting the oxygen atomic ratio of the indium oxide-containing layer 11 to be 1.15 or less, the thickness of the metal layer 12 formed on the indium oxide-containing layer 11 can be controlled within a wide range.

In addition, M in the above oxygen atomic ratio (O/(In+M) ratio) means the total amount of metal atoms of Sn and Zn contained in the indium oxide-containing layer when the indium oxide-containing layer contains metal atoms of both Sn and Zn.

The oxygen atomic ratio of the indium oxide-containing layer 11 is 1.15 or less, preferably 1.13 or less. The lower limit of the oxygen atomic ratio is not particularly limited, and is, for example, 0.5 or more.

The reason why the thickness of the metal layer 12 can be controlled within a wide range by setting the oxygen atomic ratio of the indium oxide-containing layer 11 to 1.15 or less is not clear, but is presumed as follows.

That is, it is believed that in the process of forming the metal layer 12, the ease of forming a discontinuous structure is related to the surface diffusion on the component to which the metal layer 12 is applied (in the present invention, the indium oxide-containing layer 11). The higher the temperature of the component and the lower the wettability of the metal layer 12 to the component, the easier it is to form a discontinuous structure.

In the present invention, by suppressing the oxygen concentration of the indium oxide-containing layer 11 as the member to be provided with the metal layer 12 to a certain value or less, the wettability can be further reduced and the formation of the discontinuous structure can be promoted. Therefore, it is estimated that the thickness of the discontinuous structure can be controlled within a wide range.

The indium oxide-containing layer 11 may contain a metal-containing material such as indium oxide (In ₂ O ₃ ), indium tin oxide (ITO), or indium zinc oxide (IZO).

By including the above-mentioned metal-containing substance in the indium oxide-containing layer 11, a continuous film can be formed along the surface of the substrate. In this case, the metal layer 12 laminated on the indium oxide-containing layer 11 can be easily formed into a discontinuous structure such as an island. Furthermore, in this case, the metal layer 12 contains not only tin (Sn) or indium (In), but also various metals such as aluminum that are difficult to form a discontinuous structure and difficult to use in this application.

The thickness of the indium oxide layer 11 is generally preferably less than 1000 nm, more preferably less than 50 nm, and even more preferably less than 20 nm, from the viewpoints of sheet resistance, electromagnetic wave transmittance, and production efficiency.

On the other hand, when the deposited metal layer 12 is set to a discontinuous state, the thickness of the indium oxide-containing layer 11 is preferably 1 nm or more, more preferably 2 nm or more, and even more preferably 5 nm or more.

<4. Metal layer> The metal layer 12 is formed on the indium oxide-containing layer 11. The metal layer 12 is a layer having a metallic color, preferably a layer having a metallic luster. There is no particular limitation on the material forming the metal layer 12, and it may contain metal, resin, or metal and resin.

In the electromagnetic wave transparent multilayer component of the embodiment of the present invention, the thickness of the metal layer 12 can be controlled within a wide range by setting the oxygen atomic ratio of the indium oxide layer 11 to a specific range. Therefore, the thickness of the metal layer 12 can be set within a wide range of 10 nm to 200 nm, for example, and the yield rate is improved, and stable production can be achieved.

From the viewpoint of fully exerting the metal luster, the thickness of the metal layer 12 is usually preferably not less than 10 nm. On the other hand, from the viewpoint of sheet resistance and electromagnetic wave transmittance, it is usually preferably not more than 200 nm.

For example, the thickness of the metal layer 12 is preferably 10 nm to 100 nm, and more preferably 10 nm to 70 nm. This thickness is also suitable for forming a uniform film with high production efficiency. In addition, the appearance of the final product, that is, the resin molded product, is also good.

The metal layer 12 is formed on the indium oxide-containing layer 11 and includes a plurality of portions which are discontinuous with each other in at least a portion.

In the case where the metal layer 12 is continuous on the indium oxide-containing layer 11, although sufficient metallic luster is obtained, the amount of electromagnetic wave transmission attenuation becomes very large, and electromagnetic wave transmittance cannot be ensured.

The metal layer 12 is preferably a material that can exhibit sufficient brightness and has a low melting point, because the metal layer 12 is preferably formed by thin film growth using sputtering.

For such reasons, a metal having a melting point of about 1100°C or less is suitable as the metal layer 12, for example, preferably a metal containing at least one metal selected from aluminum (Al), zinc (Zn), lead (Pb), copper (Cu), silver (Ag), and any alloy containing the metal as a main component.

In particular, the metal layer 12 preferably contains aluminum or an aluminum alloy for reasons of brightness, stability, price, etc.

Furthermore, when an aluminum alloy is used, it is preferred that the aluminum content of the metal layer 12 be set to 50 mass % or more.

The equivalent circular diameter of the portion 12a of the metal layer 12 is not particularly limited, but is generally 10 to 1000 nm. The average particle size of the plurality of portions 12a refers to the average value of the equivalent circular diameters of the plurality of portions 12a.

The circle equivalent diameter of the portion 12a is the diameter of a perfect circle that is equivalent to the area of the portion 12a.

Furthermore, the distance between the portions 12a is not particularly limited, but is usually 10 to 1000 nm.

The ratio of the thickness of the metal layer 12 to the thickness of the indium oxide-containing layer 11 (thickness of the metal layer 12/thickness of the indium oxide-containing layer 11) is preferably in the range of 0.02 to 100, more preferably in the range of 0.1 to 100, and further preferably in the range of 0.3 to 35. By setting the above range, a uniform film can be formed with high production efficiency. In addition, the appearance of the final product, i.e., the resin molded product, is also good. <5. Other layers>

Furthermore, the electromagnetic wave transparent multilayer member 1 of the embodiment of the present invention may have other layers in addition to the indium oxide-containing layer 11 and the metal layer 12 described above, depending on the application.

As other layers, there can be cited: an optical adjustment layer (color adjustment layer) of a high refractive material for adjusting the appearance such as color, a protective layer (scratch resistance layer) for improving durability such as scratch resistance, a barrier layer (corrosion resistance layer), an easy-to-adhesion layer, a hard coating layer, an anti-reflection layer, a light extraction layer, and an anti-glare layer.

<6. Manufacturing method of electromagnetic wave transparent multilayer component> The manufacturing method of the electromagnetic wave transparent multilayer component of this embodiment is characterized in that it includes: an indium oxide layer forming step, which forms an indium oxide layer on a substrate; and a metal layer forming step, which forms a metal layer on the indium oxide layer; and the indium oxide layer forming step uses a metal target containing indium as a main component, while supplying inert gas and oxygen, and forming the indium oxide layer on the substrate by reactive sputtering. The following describes each step in detail.

(1) Indium oxide layer formation step In this step, an indium oxide layer 11 is formed on the substrate 10. The ratio of oxygen atoms to indium atoms and at least one metal atom M of Sn and Zn (O/(In+M) ratio) of the formed indium oxide layer 11 when its surface is measured by X-ray photoelectron spectroscopy is 1.15 or less.

In order to achieve the above oxygen ratio, in this step, a metal target containing indium as the main component is used, and an indium oxide layer is formed on the substrate by reactive sputtering while supplying inert gas and oxygen. If the above method is used, the oxygen atomic ratio within the above range can be achieved by appropriately setting the oxygen partial pressure ratio, adjusting the amount of oxygen supplied, and performing reactive sputtering.

Previously, indium oxide-containing layers were formed by using indium oxide (In ₂ O ₃ ), indium tin oxide (ITO), and indium zinc oxide (IZO) as targets. In the above methods, since the target originally contains oxygen, it is difficult to adjust the oxygen concentration of the formed indium oxide-containing layer.

On the other hand, in the present invention, a metal target containing indium without oxygen as the main component is used, and an indium oxide layer is formed by reactive sputtering while supplying an inert gas and oxygen. This can suppress the oxygen concentration in the indium oxide layer to a relatively low level, and as a result, the thickness of the metal layer 12 can be controlled within a wide range.

As the reactive sputtering, for example, a direct current (DC) or high frequency (RF) magnetron sputtering method with a pressure of 0.1 to 1.0 Pa can be used.

As a metal target with indium as the main component, there is no particular limitation as long as it does not contain oxygen. For example, in addition to indium, tin (Sn) and zinc (Zn) may also be contained. As a composition formula, it can be expressed as In _X M _1-X (0.7≦x≦1, M=at least one metal element containing Sn and Zn). Here, "main component" means the component with the largest content ratio (mass basis) among all the components in the metal target.

Indium is preferably contained in the metal target in an amount of 70 mass % or more, more preferably 90 mass % or more.

When tin (Sn) is contained, the metal target preferably contains 2.5 to 30 mass %, and more preferably contains 3 to 10 mass %, for example.

When zinc (Zn) is contained, the metal target preferably contains 2 to 20 mass %, more preferably 5 to 15 mass %, for example.

Argon and nitrogen are usually used as inert gas. When argon is used as inert gas, the oxygen partial pressure ratio (O ₂ /Ar+O ₂ ) can be appropriately set to obtain the oxygen atomic ratio of the present invention. The oxygen partial pressure ratio is usually preferably 28% or less, more preferably 27% or less, and further preferably 26% or less. In addition, the oxygen partial pressure ratio is, for example, 10% or more and 26% or less.

The indium oxide-containing layer formed as described above is preferably an indium oxide such as indium oxide (In ₂ O ₃ ), indium tin oxide (ITO), and indium zinc oxide (IZO).

(2) Indium oxide-containing layer formation step Next, a metal layer 12 is deposited on the indium oxide-containing layer 11. In this case, for example, sputtering can be used. In addition, it is preferred that the indium oxide-containing layer 11 and the metal layer 12 are in direct contact without any other layer interposed therebetween. However, if the surface diffusion mechanism of the metal layer 12 on the indium oxide-containing layer 11 described above can be ensured, no other layer may be interposed therebetween.

<7. Application of electromagnetic wave permeable multilayer components> The electromagnetic wave permeable multilayer components of this embodiment are preferably used in devices or articles for transmitting and receiving electromagnetic waves and their parts, etc., because they have electromagnetic wave permeability. For example, they can be used in: structural parts for vehicles, vehicle-mounted products, housings of electronic devices, housings of home appliances, structural parts, mechanical parts, various automotive parts, parts for electronic devices, furniture, kitchen supplies, etc. for daily use, medical equipment, parts of building materials, other structural parts and exterior parts, etc.

More specifically, in terms of vehicle-related parts, we can cite: instrument panels, armrest boxes, door handles, door trims, gear levers, pedals, glove boxes, bumpers, hoods, fenders, trunks, doors, roofs, pillars, seats, steering wheels, ECU boxes, electrical equipment parts, engine peripheral parts, drive systems, gear peripheral parts, intake and exhaust system parts, and cooling system parts, etc.

More specifically, the electronic devices and household electrical appliances include refrigerators, washing machines, vacuum cleaners, microwave ovens, air conditioners, lighting devices, electric water heaters, televisions, clocks, ventilating fans, projectors, speakers and other household electrical appliances, personal computers, mobile phones, smart phones, digital cameras, tablet PCs, portable music players, portable game consoles, chargers, batteries and other electronic information devices. [Example]

The present invention is described in more detail below by way of examples and comparative examples. Various samples are prepared for the electromagnetic wave permeable multilayer component 1. The sheet resistance and the electromagnetic wave attenuation are measured as evaluations of the electromagnetic wave permeability, and the gloss and L* are measured as evaluations of the brightness. In addition, the thickness of the indium oxide layer and the metal layer, and the oxygen composition ratio of the indium oxide layer are measured. In addition, a base film is used as the substrate 10.

[Electromagnetic wave transmittance] (1) Sheet resistance The sheet resistance of a laminate of a metal layer and an indium oxide-containing layer was measured by the eddy current measurement method in accordance with JIS-Z2316 using the non-contact resistance measuring device NC-80MAP manufactured by Napson.

(2) Radio wave transmission attenuation The 28 GHz radio wave transmission attenuation was measured and evaluated using the free space method measurement device LAF-26.5A manufactured by KEYCOM and the spectrum analyzer MS4644BCXA signal Analyzer NA9000A manufactured by Anritsu and Agilent. (Evaluation of electromagnetic wave transmission) Less than 2[-dB]: ◎ More than 2[-dB] but less than 5[-dB]: ○ More than 5[-dB] but less than 10[-dB]: Δ More than 10[-dB]: ×

[Gloss] (3) 20ﾟ mirror gloss and L* The 20ﾟ mirror gloss ([GU]) and L* of the metal layer were measured using a portable gloss meter PG-II M manufactured by Nippon Denshoku Industries in accordance with JIS-Z8741.

(4) Film thickness measurement method <Thickness of metal layer> Taking into account the unevenness of the metal layer, more specifically, the unevenness of the thickness of the portion 12a shown in FIG1(a), the average value of the thickness of the portion 12a is set as the thickness of the metal layer. In addition, the thickness of each portion 12a is set to the thickness of the thickest part in the direction perpendicular to the substrate 10. Hereinafter, this average value is conveniently referred to as the "maximum thickness". FIG2(a) and FIG2(b) show examples of electron microscope photographs (TEM images) of cross sections of electromagnetic wave-transmissive multilayer components. When obtaining the maximum thickness, first, in the metal layer appearing on the surface of the electromagnetic wave permeable multilayer component as shown in FIG. 2(a) and FIG. 2(b), a square area 3 with a side of 5 cm as shown in FIG. 3 is appropriately captured, and points "a" to "e" of a total of 5 locations obtained by dividing the center lines A and B of the longitudinal and transverse sides of the square area 3 into 4 equal parts are selected as the measurement locations. Next, in the cross-sectional images of each of the selected measurement locations as shown in FIG. 2(a) and FIG. 2(b), a viewing angle area including approximately 5 parts 12a is captured. The thickness of each of the approximately 5 parts 12a of each of the measurement locations of the total 5 locations, that is, the thickness of each of the 25 (5 × 5 locations) parts 12a is obtained, and the average value thereof is set as the "maximum thickness".

<Thickness of indium oxide layer> The thickness of the indium oxide layer is measured using the same method as the metal layer. That is, the thickness of the indium oxide layer corresponding to the 25 parts 12a selected when measuring the thickness of the metal layer is obtained, and the average value is obtained and set as the thickness of the indium oxide layer.

(5) Oxygen composition ratio of indium oxide layer The indium oxide layer before the metal layer was formed was analyzed by using an ESCA analysis device (Quantera SXM) manufactured by ULVAC-PHI. After the surface of the indium oxide layer was cleaned to 2 nm (about 1 nm etching depth in _SiO2 conversion), a single-color AlKα X-ray source was used to perform quantitative analysis on the sample surface at a photoelectron extraction angle of 45° to calculate the element ratio (atomic%). Then, the oxygen composition ratio of O/(In+M) (M=Sn) was calculated using the obtained In, Sn, and O (atomic%).

[Example 1] A PET film (thickness 50 μm) on which a hard coating layer containing no particles was formed was used as a substrate film. First, using an In-Sn alloy target (Sn ratio 5 mass%), ITO was formed on the hard coating layer by DC pulse sputtering (150 kHz) in such a way that the oxygen partial pressure ratio (O ₂ /(Ar+O ₂ )) became 26%. The temperature of the substrate film when forming the ITO layer was set to 130°C. Next, an aluminum (Al) layer was formed on the ITO layer by alternating current sputtering (AC: 40 kHz), and the electromagnetic wave transparent multilayer structure shown in Table 1 was obtained. The obtained aluminum layer was a discontinuous layer. The temperature of the substrate film when forming the Al layer was set to 130°C.

[Examples 2 to 7] Except for changing the time for forming the ITO layer and the time for forming the aluminum (Al) layer, the laminated components of Examples 2 to 7 shown in Table 1 were obtained in the same manner as in Example 1. Electron microscopic photographs (TEM images) of the cross sections of the laminated components of Examples 4 to 7 are shown in Figures 4(a) to 4(d), respectively.

[Comparative Example 1] The same method as in Example 5 was used except that the oxygen partial pressure ratio (O ₂ /(Ar+O ₂ )) during the ITO film formation of Example 5 was changed to 29%, and the laminated structure of Comparative Example 1 shown in Table 1 was obtained. The electron microscope photograph (TEM image) of the cross section of the laminated structure of Comparative Example 1 is shown in FIG5(a). [Comparative Examples 2-3] The same method as in Example 1 was used except that the time for forming the ITO layer and the time for forming the aluminum (Al) layer were changed, and the laminated structures of Comparative Examples 2-3 shown in Table 1 were obtained. The electron microscope photograph (TEM image) of the cross section of the laminated structure of Comparative Example 3 is shown in FIG5(b). [Comparative Example 4] The same procedure as in Comparative Example 1 was followed except that the target material was changed to an ITO target (Sn ratio 10 mass %) and the oxygen partial pressure ratio (O ₂ /(Ar+O ₂ )) during ITO film formation was changed to 0%, to obtain a multilayer structure of Comparative Example 4 shown in Table 1. The evaluation results are shown in Table 1 below.

[Table 1] Table 1 Metal layer Indium oxide layer Electromagnetic wave permeability Brightness Metal materials Thickness [nm] Target material After film formation Oxygen composition ratio O/(In+M) (M=Sn) Thickness [nm] Sheet resistance [Ω/□] Radio wave transmission attenuation @28GHz [-dB] evaluate 20° gloss [GU] L* Embodiment 1 Al 32.3 In+Sn(5% by mass) ITO 1.10 4.4 ＞3000 0.1 ◎ 1590 87.6 Embodiment 2 Al 32.6 In+Sn(5% by mass) ITO 1.10 15.3 2869 0.9 ◎ 986 71.5 Embodiment 3 Al 37.3 In+Sn(5% by mass) ITO 1.10 11.1 ＞3000 0.2 ◎ 1405 82.1 Embodiment 4 Al 37.6 In+Sn(5% by mass) ITO 1.10 15.6 2665 0.9 ◎ 1098 73.3 Embodiment 5 Al 52.4 In+Sn(5% by mass) ITO 1.10 15.5 2442 1 ◎ 1244 78.8 Embodiment 6 Al 52.6 In+Sn(5% by mass) ITO 1.10 10.5 ＞3000 0.5 ◎ 1726 88.3 Embodiment 7 Al 81.9 In+Sn(5% by mass) ITO 1.10 15.5 2111 1.6 ◎ 1518 84.8 Comparison Example 1 Al 51.6 In+Sn(5% by mass) ITO 1.18 5.7 2.5 41.6 × 1970 93.1 Comparison Example 2 Al 66.5 In+Sn(5% by mass) ITO 1.18 5.7 1.1 57.1 × 2130 95.1 Comparison Example 3 Al 82.1 In+Sn(5% by mass) ITO 1.18 5.5 0.8 56.5 × 2080 95.5 Comparison Example 4 Al 55.8 ITO(Sn10 mass%) ITO 1.18 6.3 3.2 37 × 1799 92.6

As can be clearly seen from Table 1, in the laminated structures of Examples 1 to 7, the sheet resistance is high and the electromagnetic wave transmission attenuation is low, showing excellent electromagnetic wave transmission. In addition, the brightness is sufficient. This is considered to be due to the fact that the formation of the metal layer of the island-like discontinuous structure is promoted, as can be seen from the electron microscope photographs (TEM images) of the cross-sections of the laminated structures of Examples 4 to 7 shown in Figures 4(a) to 4(d).

On the other hand, the sheet resistance of the laminated components of Comparative Examples 1 to 4 is significantly lower, and the electromagnetic wave transmission attenuation is also higher, and the electromagnetic wave transmission is poorer than that of the embodiment. This is considered to be due to the fact that many island-shaped metal layers are partially overlapped, as can be seen from the electron microscope photographs (TEM images) of the cross-sections of the laminated components of Comparative Examples 1 and 3 shown in Figures 5(a) and 5(b).

In addition, for metals other than aluminum (Al) specifically used in the above embodiments, metals with lower melting points such as zinc (Zn), lead (Pb), copper (Cu), and silver (Ag) can also be considered to form a discontinuous structure using the same method.

The present invention is not limited to the aforementioned embodiments, and can be appropriately modified and embodied within the scope of the invention.

In the above, various embodiments are described with reference to the drawings, but it should be understood that the present invention is not limited to the above examples. Anyone familiar with the art can obviously think of various changes or modifications within the scope of the patent application, and it should be understood that they also fall within the technical scope of the present invention. In addition, the constituent elements of the above embodiments can be arbitrarily combined within the scope of the invention.

In addition, this invention application is based on the Japanese patent application (Japanese Patent Application No. 2020-040057) filed on March 9, 2020, and its contents are used as a reference in this invention application. [Industrial Applicability]

The electromagnetic wave permeable multilayer structure of the present invention can be used in devices or articles that transmit and receive electromagnetic waves and their parts, etc. For example, it can also be used in various uses that require both design and electromagnetic wave permeability, such as vehicle structural parts, vehicle-mounted products, electronic device casings, home appliance casings, structural parts, mechanical parts, various automobile parts, electronic device parts, furniture, kitchen supplies, etc., for movable daily use, medical equipment, building material parts, other structural parts, and exterior parts.

1: Electromagnetic wave permeable multilayer component 3: Square area 10: Substrate 11: Indium oxide layer 12: Metal layer 12a: Part 12b: Gap A, B: Center line a~e: Points

FIG. 1(a) is a schematic cross-sectional view of an electromagnetic wave-transmissive laminated component 1 in one embodiment of the present invention. FIG. 1(b) is an electron microscope photograph (SEM image) of the surface of the electromagnetic wave-transmissive laminated component 1 in one embodiment of the present invention. FIG. 2(a) and FIG. 2(b) show examples of electron microscope photographs (TEM images) of a cross section of an electromagnetic wave-transmissive laminated component in one embodiment of the present invention. FIG. 3 is a diagram for explaining a method for measuring the thickness of a metal layer of an electromagnetic wave-transmissive laminated component in one embodiment of the present invention. FIG. 4(a) to FIG. 4(d) show electron microscope photographs (TEM images) of cross sections of laminated components of Examples 4 to 7, respectively. FIG. 5( a ) and FIG. 5( b ) show electron microscope photographs (TEM images) of the cross sections of the layered components of Comparative Examples 1 and 3.

1: Electromagnetic wave permeability multilayer components

10: Matrix

11: Contains indium oxide layer

12: Metal layer

12a: Partial

12b: Gap

Claims (11)

An electromagnetic wave transparent multilayer structure, comprising: a substrate, an indium oxide layer formed on the substrate, and a metal layer formed on the indium oxide layer; wherein the metal layer includes a plurality of parts that are discontinuous with each other in at least one part; when the surface of the indium oxide layer is measured by X-ray photoelectron spectroscopy, the total ratio of oxygen atoms to indium atoms and at least one metal atom M of Sn and Zn (O/(In+M) ratio) is less than 1.15. The electromagnetic wave transparent multilayer structure as claimed in claim 1, wherein the aforementioned indium oxide-containing layer is arranged in a continuous state. The electromagnetic wave transparent multilayer structure of claim 1 or 2, wherein the indium oxide-containing layer contains any one of indium oxide (In ₂ O ₃ ), indium tin oxide (ITO), or indium zinc oxide (IZO). For the electromagnetic wave transparent multilayer structure of claim 1 or 2, the aforementioned metal layer is a layer containing aluminum or aluminum alloy. For the electromagnetic wave transparent multilayer component of claim 1 or 2, the thickness of the aforementioned indium oxide layer is 1nm~1000nm. For the electromagnetic wave transparent multilayer component of claim 1 or 2, the thickness of the aforementioned metal layer is 10nm~200nm. For the electromagnetic wave transparent multilayer component of claim 1 or 2, the ratio of the thickness of the aforementioned metal layer to the thickness of the aforementioned indium oxide-containing layer (the thickness of the aforementioned metal layer/the thickness of the aforementioned indium oxide-containing layer) is 0.02~100. For example, the electromagnetic wave permeable multilayer structure of claim 1 or 2, wherein the sheet resistance is 100Ω/□ or more. The electromagnetic wave permeable multilayer structure as claimed in claim 1 or 2, wherein the aforementioned multiple parts are formed into an island shape. The electromagnetic wave transparent multilayer structure of claim 1 or 2, wherein the substrate is a substrate film, a resin molding substrate, a glass substrate, or any of the articles to be given a metallic luster. A method for manufacturing an electromagnetic wave transparent multilayer component according to any one of claims 1 to 10, comprising: an indium oxide layer forming step, in which an indium oxide layer is formed on a substrate; and a metal layer forming step, in which a metal layer is formed on the indium oxide layer; and the indium oxide layer forming step uses a metal target containing indium as a main component, while supplying an inert gas and oxygen, to form the indium oxide layer on the substrate by reactive sputtering.