Resin molded body

Abstract

To provide a resin molded body that offers excellent electromagnetic shielding properties while enabling shielding of high-frequency electromagnetic waves with a high degree of design flexibility. [Solution] A resin molded article comprising a resin and a coil-shaped conductive member, wherein the coil pitch of the coil-shaped member is 0.5 μm or more and 20.0 μm or less.

Description

[Technical Field]

[0001] This disclosure relates to a resin molded article. [Background technology]

[0002] Communication devices such as mobile phones and smartphones utilize electromagnetic waves to enable wireless communication, and with the advancement of technology in this field, the frequency bands of electromagnetic waves used have expanded. Specifically, wireless communication systems conforming to the IMT-Advanced standard set by the International Telecommunication Union (ITU) are defined, and the frequency band, which was approximately 800MHz in the first-generation mobile communication system (1G), has been expanded to approximately 3GHz in the fourth-generation mobile communication system (4G). Furthermore, in the currently adopted fifth-generation mobile communication system (5G), the frequency band has been expanded to the 28GHz band in order to achieve high speed, large capacity, low latency, and multiple connections, and development of the sixth-generation mobile communication system (6G), which will utilize frequency bands of 100GHz or higher as the next-generation communication system, is currently underway. While the use of electromagnetic waves in high frequency bands is attracting attention, the higher frequency of the electromagnetic waves used makes it easier for problems such as malfunction of electronic devices, communication failures, information leakage, and health problems to occur, thus requiring electromagnetic noise control (EMC). Specifically, there is a need for the development of novel materials that can suppress both emission EMI (perpetrators) and immunity EMS (victims). One way to solve this problem is to use electromagnetic wave control materials that can reduce the effects of electromagnetic waves from the surroundings. Electromagnetic wave control materials come in a variety of forms, such as semiconductor packages / modules, housings for electrical / electronic equipment, adhesive materials for semiconductor mounting substrates or cables, wallpaper for buildings such as server rooms, or clothing such as aprons to protect the human body.

[0003] Various types of electromagnetic wave control materials exist, and research is being conducted extensively in this field. For example, there are reflective materials that reflect electromagnetic waves by using large metal plates, and absorbing materials that absorb electromagnetic waves by using materials in which conductive components are mixed with organic materials such as resin or rubber. For example, advances in research on absorbing materials have shown that it is effective to use materials with structures that are an order of magnitude smaller than the wavelength of the electromagnetic waves to be shielded. As a means of forming such structures, the development of materials containing small fillers is progressing. Patent Document 1 discloses a sheet comprising a composite having an insulating layer and a conductive layer containing flake-shaped silver powder having a specific particle size and bulk density in a binder resin, which exhibits excellent electromagnetic wave shielding performance at a frequency of 1 GHz. Patent Document 2 discloses a sheet comprising a composite having ferrite particles in a binder resin that are single crystals having a specific average particle size and a perfectly spherical particle shape, which can shield electromagnetic waves in the frequency band of 1 MHz to 1 GHz. Furthermore, Patent Document 3 discloses a sheet comprising a composite having a specific amount or more of nickel nanowire in a binder resin, which exhibits excellent handling and flexibility, and can shield electromagnetic waves in the frequency band of 18.0 to 26.5 GHz.

[0004] On the other hand, the sheets disclosed in Patent Documents 1 to 3 have the problem of not being able to handle electromagnetic waves in the frequency band of next-generation wireless communication systems, which are more than an order of magnitude larger than the frequency band used in conventional wireless communication systems. To solve this problem, sheets using coil-shaped conductive members have also been developed, as disclosed in Patent Document 4. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-86930 [Patent Document 2] International Publication No. 2017 / 212997 [Patent Document 3] Japanese Patent Publication No. 2019-67997 [Patent Document 4] International Publication No. 2022 / 009960 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the technology of shielding electromagnetic waves using coil-shaped conductive members, development has primarily focused on improving electromagnetic shielding characteristics. On the other hand, electromagnetic shielding members using coil-shaped conductive members offer greater design flexibility compared to electromagnetic shielding members made of metal cases, etc.

[0007] Therefore, this disclosure provides a resin molded article that has excellent electromagnetic shielding properties while enabling shielding of high-frequency electromagnetic waves with a high degree of design flexibility. [Means for solving the problem]

[0008] As a result of diligent research, the inventors of the present invention have found that the above problem can be solved by setting the coil pitch of the coil shape constituting the conductive member to a specific range, and have arrived at the invention described herein.

[0009] In other words, this disclosure has the following features. [1] A resin molded article comprising a resin and a coil-shaped conductive member, The coil pitch of the aforementioned coil shape is 0.5 μm or more and 20.0 μm or less. Resin molded body. [2] The resin molded article according to [1], wherein the thickness of the strands constituting the coil shape is 0.1 μm or more and 10.0 μm or less. [3] The thickness is 10.0 μm or more and 100.0 μm or less, A resin molded article according to [1] or [2], wherein the electromagnetic shielding performance determined by electromagnetic wave transmittance measurement is -20.0 dB or less. [4] The resin molded body according to any one of [1] to [3], wherein the number of turns of the coil shape is 3 or more and 100 or less. [5] The resin molded body according to any one of [1] to [4], wherein the ratio of the coil radius to the height of the conductive member is 0.4 or more and 5.0 or less. [6] The resin molded body according to any one of [1] to [5], wherein the number of the conductive members contained in the resin molded body is 2 or more. [7] The resin molded body according to [6], wherein the distance between the central axes of the coil shapes of adjacent conductive members is 5.0 μm or more and 1000.0 μm or less. [8] The resin molded body according to any one of [1] to [7], wherein at least a part of the coil shape is a tapered shape in which the coil radius gradually increases or decreases. [9] The minimum value of the coil radius is 5.0 μm or more, and the maximum value of the coil radius is 1000.0 μm or less, The resin molded body according to [8].

[10] The resin molded body according to any one of [1] to [9], which is in a sheet shape.

[11] The resin molded body according to

[10] , which is an electromagnetic shielding sheet. [Advantages of the Invention]

[0010] According to the present disclosure, it is possible to provide a resin molded body that enables shielding of electromagnetic waves in a high-frequency band with excellent electromagnetic wave shielding characteristics and high design freedom. [Brief Description of the Drawings]

[0011] [Figure 1] It is a diagram schematically showing one aspect of a conductive member. [Figure 2] It is a diagram for explaining the form of a conductive member. [Figure 3] It is a diagram schematically showing one aspect of a conductive member. [Figure 4] It is a diagram for explaining the coil radius of a conductive member. [Figure 5] It is a diagram for explaining the form of a conductive member. [Figure 6] This diagram schematically represents the experimental apparatus used for evaluating electromagnetic shielding characteristics. [Figure 7] This diagram schematically represents one embodiment of a resin sheet having a C-shaped conductive member and a columnar conductive member connected to the end of the C-shaped member. [Figure 8] This figure schematically represents one aspect of a laminated sheet, which is formed by laminating resin sheets having a C-shaped conductive member and a columnar conductive member connected to the end of the C-shaped member. [Figure 9] This figure schematically represents the basic form of the resin molded body used in the simulation experiment in the example. [Figure 10] This figure shows the evaluation results of the electromagnetic wave shielding characteristics of the resin molded body in the example. [Figure 11] This figure shows the evaluation results of the electromagnetic wave shielding characteristics of the resin molded body in the example. [Figure 12] This figure schematically represents the basic form of the resin molded body used in the simulation experiment in the example. [Figure 13] This figure shows the evaluation results of the electromagnetic wave shielding characteristics of the resin molded body in the example. [Modes for carrying out the invention]

[0012] The embodiments of this disclosure are described in detail below, but the configurations and combinations thereof in each embodiment are examples only, and additions, omissions, substitutions, and other modifications can be made as appropriate without departing from the spirit of this disclosure. This disclosure is not limited by the embodiments, but is limited only by the scope of the claims. In this disclosure, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, and "A~B" means that it is greater than or equal to A and less than or equal to B. Furthermore, although this disclosure describes multiple embodiments, various conditions in each embodiment can be applied to each other to the extent applicable. Furthermore, the expression "A or B" in this disclosure can be interpreted as "at least one selected from the group consisting of A and B." Furthermore, in this disclosure, "multiple" means "two or more." The dimensions, materials, shapes, and relative arrangements of the components described in this disclosure are examples only.

[0013] <Resin molded product> One embodiment of the present disclosure is a resin molded article (hereinafter also simply referred to as "resin molded article") which is a resin molded article comprising a resin and a coil-shaped conductive member, wherein the coil pitch of the coil-shaped member is 0.5 μm or more and 20.0 μm or less.

[0014] The inventors have focused on developing a coil-shaped conductive member as a structure that can absorb strong electromagnetic waves in the terahertz region. In the coil shape, it can be considered as a series of interconnected pseudo-C-shaped surface structures. When these are considered as a circuit, it was found that the effect of electromagnetic wave absorption due to LC resonance, where the coil shape itself has inductance L and the gap has capacitance C, can be obtained. Furthermore, it was discovered that absorption can be obtained due to the resonance effect caused by the magnetic field entering the coil.

[0015] As a result of diligent research by the inventors, it has been found that by using a conductive member in the shape of a coil having a coil pitch within the range described above, it is possible to obtain a resin molded body that has excellent electromagnetic wave shielding characteristics, is easy to miniaturize, and therefore offers a high degree of design freedom. The inventors speculate that this is because the resonance conditions of the current induced in the coil by electromagnetic waves are optimized to match the coil pitch within the range described above, thereby enabling high shielding performance with a short coil length. In particular, when the resin molded body is in sheet form, it is possible to reduce the thickness while maintaining excellent electromagnetic shielding properties. By using such a resin molded body, it becomes easier to miniaturize the product to which the resin molded body is applied, and the design flexibility of the product is improved. In this disclosure, thinning is one aspect of miniaturization.

[0016] Furthermore, in the above embodiment, since a lightweight material such as a polymer material can be used as the binder for the conductive member, it is easier to reduce the weight compared to conventional electromagnetic wave shielding members that use metal plates. Furthermore, methods of electromagnetic shielding using electromagnetic shielding members include reflecting electromagnetic waves incident from the side where the product to be shielded is located, and absorbing electromagnetic waves. However, when electromagnetic waves are reflected by the shielding member, although the amount of electromagnetic waves passing through the shielding member is reduced, there are concerns that the reflected electromagnetic waves may hit electronic equipment and cause malfunctions. Therefore, from this viewpoint, it is preferable to perform electromagnetic shielding by absorption rather than reflection as much as possible. When a metal plate is used as the shielding member, it is difficult to prevent reflection because electromagnetic waves are basically reflected by the metal surface. On the other hand, in the above embodiment, a polymer material or the like can be used as the binder of the conductive member, which is easier to prevent the reflection of electromagnetic waves and is also easier to absorb electromagnetic waves compared to a metal material.

[0017] Furthermore, conventionally, metal cases, mainly stainless steel cases, have been used as electromagnetic shielding materials in semiconductor modules. Such stainless steel cases can shield from external electromagnetic waves by reflecting them. While reflection can block the entry and exit of electromagnetic waves, because multiple semiconductor elements are present inside the case, metal materials are more prone to diffuse reflection of electromagnetic waves emitted from semiconductor elements within the case compared to polymer materials, and consequently, are more likely to cause malfunctions in adjacent semiconductor elements. Furthermore, since the stainless steel case is conductive, it needs to be installed so as not to come into contact with the exposed terminals in order to prevent the short circuits mentioned above, which limits the space-saving possibilities. When a conventional stainless steel case is replaced with a resin molded body of the same shape according to this embodiment, the resin molded body is an absorber, which reduces the likelihood of diffuse reflection within the case and thus the risk of malfunction. Furthermore, because it has high resistance, it can be used in contact with exposed terminals, making it easier to save space. In addition, since the resin molded body according to this embodiment can be formed by coating or spraying, it can be closely attached to multiple semiconductors, including terminals, achieving extreme space saving while maintaining its performance as an absorber.

[0018] [Conductive material] (Composition of conductive components) The conductive member is a coil-shaped member. In this disclosure, a coil shape is a shape composed of lines that surround a central axis and extend in the direction of the central axis, or a shape composed of lines that surround a central axis and lines that extend in the direction of the central axis, etc. The shape of the conductive member as viewed from the direction of the central axis is not particularly limited and may be circular, triangular, square, pentagonal, or any other polygonal shape. The central axis of the conductive member may be a straight line, a curved line, or a line of any shape.

[0019] Specific examples of conductive members include the one shown in Figure 1. Examples of component shapes include a spiral shape as shown in Figure 1(a), and a shape composed of multiple C-shaped structures and columnar structures connecting the multiple C-shaped structures in the direction of the central axis, as shown in Figure 1(b). Specifically, Figure 1(b) is a shape composed of a structure in which the end of a columnar shape is connected to the end of a C-shape, and the other end of another C-shape is connected to the other end of the columnar shape, and so on, resulting in a coil shape overall.

[0020] When the coil shape of the conductive member is composed of a plurality of C-shaped structures as shown in Figure 1(b) and a columnar structure connecting the plurality of C-shaped structures in the direction of the central axis, the embodiment is not particularly limited. For example, as will be shown in the description of the manufacturing method below, the C-shaped structure portion is made of a conductive thin film, and the columnar structure portion connecting the plurality of C-shaped structures is made of a columnar conductive member. The C-shape may be a circular ring with a portion missing, as shown in Figure 1(b), or the shape of this ring may be a polygon such as a triangle or quadrilateral with a portion missing. However, from the viewpoint of availability and ease of manufacture, a circular ring with a portion missing is preferred. In any of these embodiments, as long as there is a central axis, the effect of absorbing electromagnetic waves due to LC resonance based on external electromagnetic waves can be obtained. The shape of the column is not particularly limited; it can be cylindrical, triangular, or rectangular, or any other polygonal shape. However, a cylindrical shape is preferred from the viewpoint of ease of availability and manufacturing. The C-shaped structural portion and the columnar structural portion may be made of the same material or different materials, but from the viewpoint of reducing manufacturing costs, it is preferable that they be made of the same material.

[0021] Figure 2 shows one embodiment of a conductive member. Figure 2 is a view of two conductive members observed from a direction perpendicular to the central axis direction of the coil shape constituting the conductive member. In Figure 2, C is the central axis, D is the maximum value of the coil diameter (twice the coil radius R), H is the height of the conductive member, P is the coil pitch of the coil shape, W is the thickness of the wires constituting the coil shape, and M is the distance between the central axes of the coil shapes of adjacent conductive members. These parameters can be measured by internal observation using CT-X-rays.

[0022] The cross-sectional shape of the wires constituting the coil shape is not particularly limited and may be, for example, circular, triangular, or other polygonal shapes.

[0023] The type of material used for the conductive member is not particularly limited as long as it is conductive. Examples include carbon materials such as carbon, alloys made from combinations of metal elements such as copper (Cu), aluminum (Al), iron (Fe), gold (Au), silver (Ag), platinum (Pt), magnesium (Mg), zinc (Zn), tungsten (W), titanium (Ti), nickel (Ni), or manganese (Mn), or metal-containing compounds such as oxides, halides, or sulfides of these metal elements or alloys. The conductive member may also be a composite material in which these conductive materials are incorporated into a resin, or a coil-shaped resin with a thin metal film applied to its surface by a plating or other treatment. Among these, copper (Cu), iron (Fe), or tungsten (W) are preferred materials for conductive members, particularly tungsten (W), because their elastic modulus is suitable for coil processing, they have good corrosion resistance when incorporated into resin, and their coefficient of linear expansion is small, resulting in good durability of the resin molded product. Furthermore, from the viewpoint of being able to be manufactured with a 3D printer, a composite material in which a conductive material is incorporated into the resin, or a material in which a thin metal film is provided on the surface of a coil-shaped resin by a treatment such as plating, is preferred. When using resin as the material for a conductive member, the type of resin is not particularly limited, and the same type of resin that constitutes the matrix of the resin molded body described later can be used. However, it is preferable that the type of resin used as the material for the conductive member is different from the type of resin that constitutes the matrix of the resin molded body.

[0024] The conductive members may be composed of only a single metal or alloy, but a plating coating may be formed on their surface. Furthermore, to prevent short circuits between conductive members as much as possible, the surface may be coated with an insulating resin, or an oxide film may be formed on the surface. For example, an oxide film can be formed by high-temperature treatment of the conductive members.

[0025] There are no particular restrictions on the number of conductive components in a resin molded body, but from the viewpoint of ensuring sufficient electromagnetic shielding performance, it is usually set at 50 components / cm². 3That's all. 100 pieces / cm 3 Preferably, the number is 200 or more, or 200 pieces / cm 3 It is more preferable that the number be greater than or equal to 300 pieces / cm². 3 It is even more preferable that the number be greater than or equal to 10,000 pieces / cm². 3 The following applies: 5000 pieces / cm 3 Preferably, the following: 3000 pieces / cm 3 It is more preferable that the following conditions are met: 1000 pieces / cm 3 The following is even more preferable: The number of the above-mentioned conductive components can be measured by internal observation using CT-X-rays.

[0026] The content of conductive material in the resin molded body is not particularly limited and can be appropriately designed depending on the material of the conductive material.

[0027] The arrangement of the conductive members is not particularly limited and may be random, but it is preferable that they be arranged to form a periodic structure. In this disclosure, a periodic structure means an arrangement in which the conductive members are aligned within a resin molded body, and more specifically, an arrangement in which the conductive members are arranged at periodic intervals within the resin. The arrangement is not particularly limited and may include arrangements that form a circular shape or a polygonal shape such as a triangle or square. This aligned arrangement may consist of one layer or two or more layers. Furthermore, when a resin molded body is constructed by laminating multiple layers, the arrangement of the conductive members in each layer can be arbitrarily set. For example, the arrangement of the conductive members may be random in all layers, the arrangement of the conductive members may be arranged to form a periodic structure in all layers, or a laminate combining these arrangements may be used.

[0028] The coil radius R is not particularly limited, but from the viewpoint of ensuring sufficient electromagnetic shielding, it is preferably 40.0 μm or more, more preferably 60.0 μm or more, even more preferably 80.0 μm or more, and particularly preferably 100.0 μm or more. Furthermore, from the viewpoint of ensuring sufficient electromagnetic shielding, it is preferably 500.0 μm or less, more preferably 400.0 μm or less, even more preferably 300.0 μm or less, and particularly preferably 200.0 μm or less. In this specification, unless otherwise specified, parameters are treated as their average values. For example, if a resin molded body contains multiple conductive members, "coil radius" means "the average value of the coil radii of the multiple conductive members." The same applies to other parameters. The same applies to the examples; for example, the number of turns of the coil shape in Experiment B of Example is 32.8, but this is also an average value.

[0029] The height H of the conductive member is not particularly limited, but from the viewpoint of improving shielding performance, it is preferably 10.0 μm or more, more preferably 20.0 μm or more, even more preferably 30.0 μm or more, and particularly preferably 40.0 μm or more. Furthermore, from the viewpoint of making it difficult to thin the resin molded article, it is preferably 400.0 μm or less, more preferably 300.0 μm or less, even more preferably 200.0 μm or less, and particularly preferably 100.0 μm or less.

[0030] The ratio of the coil radius of the coil shape to the height of the conductive member is not particularly limited, but from the viewpoint of ensuring sufficient electromagnetic shielding performance, it is preferably 0.4 or more, more preferably 0.6 or more, even more preferably 0.8 or more, and 1.0 or more. It is particularly preferable that the value be 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, and especially preferably 2.0 or less, from the viewpoint of ensuring sufficient electromagnetic shielding. Furthermore, if the coil shape is a tapered shape as described later, the above coil radius may be treated as the maximum value of the coil radius.

[0031] The coil pitch P of the coil shape is not particularly limited as long as it is between 0.5 μm and 20.0 μm, but may be greater than or equal to the lower limit of the wire thickness W described later. From the viewpoint of avoiding contact between wires, it is preferable that it be 1.0 μm or more, more preferably 2.0 μm or more, even more preferably 2.5 μm or more, and particularly preferable 3.0 μm or more. Furthermore, from the viewpoint of making it difficult to thin the resin molded product, it is preferable that it be 17.0 μm or less, more preferably 15.0 μm or less, even more preferably 13.0 μm or less, and particularly preferable 11.0 μm or less.

[0032] The ratio of the height H of the conductive member to the coil pitch P of the coil shape is not particularly limited, but from the viewpoint of ensuring sufficient electromagnetic wave shielding performance, it is preferably 0.9 or more, more preferably 1.0 or more, even more preferably 2.0 or more, and particularly preferably 3.0 or more. Furthermore, from the viewpoint of making it difficult to thin the resin molded body, it is preferably 150 or less, more preferably 100.0 or less, even more preferably 33 or less, and particularly preferably 10 or less.

[0033] The thickness W of the wires constituting the coil shape is not particularly limited, but from the viewpoint of improving rigidity and making it less prone to deformation during molding by injection molding, etc., it is usually 0.09 μm or more, preferably 0.1 μm or more, more preferably 1.0 μm or more, and even more preferably 2.0 μm or more. Furthermore, from the viewpoint of reducing weight, the thickness W is usually less than 30.0 μm, preferably 10.0 μm or less, more preferably 9.0 μm or less, and even more preferably 8.0 μm or less.

[0034] The number of conductive members included in the resin molded body may be two or more. When there are two or more conductive members, the distance M between the central axes of the coil shapes of adjacent conductive members is not particularly limited. However, from the viewpoint of preventing contact between conductive members, it is usually 4.0 μm or more, preferably 5.0 μm or more, more preferably 50.0 μm or more, and even more preferably 200.0 μm or more. Furthermore, from the viewpoint of ensuring sufficient electromagnetic shielding, it is usually 1500.0 μm or less, preferably 1000.0 μm or less, more preferably 900.0 μm or less, and even more preferably 750.0 μm or less.

[0035] The number of turns in the coil shape is not particularly limited, but from the viewpoint of ensuring sufficient electromagnetic wave shielding performance, it is usually 3 or more, preferably 4 or more, more preferably 6 or more, and even more preferably 10 or more. Also, it is usually 100 or less, preferably 50 or less, more preferably 33 or less, and even more preferably 20 or less.

[0036] The winding direction of the coil shape is not particularly limited and may be in either direction. Furthermore, if the number of conductive members included in the resin molded body is two or more, the winding direction of the coil shape of all conductive members may be the same, but from the viewpoint of suppressing the dependence of the characteristics on the polarization of the incident electromagnetic wave, the winding direction of the coil shape of at least some of the conductive members may be different from the winding direction of any one conductive member adjacent to that conductive member, and may also be different from the winding direction of all conductive members adjacent to that conductive member.

[0037] The position of the ends of the wires that make up the coil shape is not particularly restricted; for example, the center of the coil shape. When viewed from the axial direction, the angle formed by the straight line connecting one end of the wire constituting the coil shape to the central axis and the straight line connecting the other end of the wire constituting the coil shape to the central axis may be 10° or less, or it may be approximately 0°. When viewed from the central axis direction of the coil shape, the line A is defined as the line connecting the end of the wire constituting the coil shape on the side with the larger coil radius to the central axis. In this case, the angle between the line A of at least some of the conductive members and the line A of any one conductive member adjacent to the conductive member is not particularly limited, but may be 10° or less, approximately 0°, or approximately 90°. Furthermore, the angle between the line A of at least some of the conductive members and the line A of all conductive members adjacent to the conductive member may be independently selected from the group consisting of approximately 0°, approximately 90°, approximately 180°, and approximately 270°, or may be selected from the group consisting of approximately 90°, approximately 180°, and approximately 270°.

[0038] The conductive member may be completely embedded in a matrix such as resin, or it may not be completely embedded (only a part of it may be embedded), that is, a part of the conductive member may be exposed to the outside air.

[0039] From the viewpoint of reducing the reflectivity of electromagnetic waves while maintaining sufficient electromagnetic shielding performance, it is preferable that at least a portion of the coil shape constituting the conductive member has a tapered shape in which the coil radius gradually increases or decreases. In this case, the coil shape constituting the conductive member may have a tapered shape in part, or the entire coil may have a tapered shape. Specifically, a tapered shape refers to a coil shape with n turns in which the coil radius of the k-th turn is smaller than the coil radius of the (k-1)-th turn. Here, n represents an integer of 3 or greater, and k represents an integer satisfying 1 ≤ k ≤ n. Furthermore, the orientation of the coil shape is not limited; it is sufficient that the relationship is satisfied such that the coil radius of the k-th turn is smaller than the coil radius of the (k-1)-th turn, when the first turn is considered to be at one end of the coil shape.

[0040] Specific examples of conductive members having a tapered shape include the one shown in Figure 3. Examples of conductive members include a helical shape as shown in Figures 3(a) and (b), and a shape composed of multiple C-shaped structures and a columnar structure connecting the multiple C-shaped structures in the direction of the central axis as shown in Figures 3(c) and (d). Specifically, Figures 3(c) and (d) are shapes composed by repeating a structure in which the end of a columnar shape is connected to the end of a C-shape, and the end of another C-shape is connected to the other end of the columnar shape, resulting in a coil shape overall.

[0041] The conductive members in Figure 3(a) and Figure 3(b) have different orientations, but both are conductive members with a tapered shape overall. In the case of the conductive member in Figure 3(a), the winding at the X-side end is the nth winding, and the winding at the Y-side end is the first winding. Similarly, in the case of the conductive member in Figure 3(b), the winding at the Y-side end is the nth winding, and the winding at the X-side end is the first winding. Likewise, in the case of the conductive member in Figure 3(c), the winding at the X-side end is the nth winding, and the winding at the Y-side end is the first winding. Also, in the case of the conductive member in Figure 3(d), the winding at the Y-side end is the nth winding, and the winding at the X-side end is the first winding.

[0042] The coil radius in a tapered shape will be explained using Figure 4. Figure 4 shows a coil shape with 4 turns observed from a direction perpendicular to the central axis C. When the coil shape is viewed from a direction perpendicular to the central axis C, the tapered shape is composed of multiple line segments as shown in Figure 4. Specifically, the tapered shape in Figure 4 is composed of points ( It is composed of line segments connecting PA-4) and point (PB-4), line segments connecting point (PB-4) and point (PA-3), line segments connecting point (PA-3) and point (PB-3), ..., line segments connecting point (PA-2) and point (PB-2), line segments connecting point (PB-1) and point (PA-1), and line segments connecting point (PA-1) and point (PB-1). In this case, when viewing the tapered shape from a direction perpendicular to the central axis C, if the distance between the line (LA-4) passing through point (PA-4) and parallel to the central axis, and the line (LB-4) passing through point (PB-4) and parallel to the central axis, is D-4, then the coil radius for the fourth winding is (D-4) / 2. Similarly, The coil radius for the third winding is half the distance between the line (LA-3) passing through point (PA-3) and parallel to the central axis, and the line (LB-3) passing through point (PB-3) and parallel to the central axis ((D-3) / 2). The coil radius for the second winding is half the distance between the line (LA-2) passing through point (PA-2) and parallel to the central axis, and the line (LB-2) passing through point (PB-2) and parallel to the central axis ((D-2) / 2). The coil radius for the first winding is half the distance between the line (LA-1) passing through point (PA-1) and parallel to the central axis, and the line (LB-1) passing through point (PB-1) and parallel to the central axis ((D-1) / 2).

[0043] The minimum coil radius represents the smallest coil radius in a single tapered shape. In other words, in Figure 4, (D-1) / 2 is the minimum coil radius. From the viewpoint of ensuring sufficient electromagnetic shielding performance, the minimum value of the coil radius is preferably 4.0 μm or more, more preferably 5.0 μm or more, even more preferably 50.0 μm or more, and particularly preferably 80.0 μm or more. Furthermore, from the viewpoint of ensuring sufficient electromagnetic shielding performance, it is preferably 500.0 μm or less, more preferably 400.0 μm or less, even more preferably 300.0 μm or less, and particularly preferably 200.0 μm or less. In this specification, unless otherwise specified, parameters are treated as their average values. For example, if a resin molded body contains multiple conductive members, "minimum coil radius" means "the average value of the minimum coil radii of the multiple conductive members." The same applies to other parameters.

[0044] The maximum coil radius represents the maximum coil radius in a single tapered shape. In other words, in Figure 4, (D-4) / 2 is the maximum coil radius. From the viewpoint of ensuring sufficient electromagnetic shielding performance, the maximum value of the coil radius is preferably 40.0 μm or more, more preferably 60.0 μm or more, even more preferably 80.0 μm or more, and particularly preferably 100.0 μm or more. Furthermore, from the viewpoint of ensuring sufficient electromagnetic shielding performance, it is preferably 1200.0 μm or less, more preferably 1000.0 μm or less, even more preferably 500.0 μm or less, and particularly preferably 300.0 μm or less.

[0045] While there are no particular restrictions on the range of increase or decrease in the coil radius, from the viewpoint of fully exhibiting the reflectance reduction effect, it is preferable that it be 0.5 μm or more, more preferably 1.0 μm or more, even more preferably 2.0 μm or more, and particularly preferable 3.0 μm or more. Furthermore, from the viewpoint of fully exhibiting the reflectance reduction effect, it is preferable that it be 100.0 μm or less, more preferably 50.0 μm or less, even more preferably 30.0 μm or less, and particularly preferable 20.0 μm or less. The range of increase or decrease is the difference between adjacent coil radii, and in Figure 4, for example, it is a value represented as (D-2) / 2 - (D-1) / 2, etc.

[0046] There is no particular limit to the number of tapered shapes included in the coil shape that constitutes a single conductive member. It may be 1 or more, 2 or more, 3 or more, and it may be 6 or less, 5 or less, or 4 or less. Examples of configurations where there are multiple tapered shapes include, for instance, when considering two tapered shapes, the configuration in which the smaller diameter side of one tapered shape is connected to the larger diameter side of the other tapered shape, the configuration in which the larger diameter side of one tapered shape is connected to the larger diameter side of the other tapered shape, and the configuration in which the two tapered shapes are connected by a non-tapered shape.

[0047] Figure 5 shows one embodiment of a conductive member having a tapered shape. Figure 5 is a view of two conductive members observed from a direction perpendicular to the central axis direction of the coil shape constituting the conductive member. In Figure 5, C is the central axis, Dmax is the maximum value of the coil diameter (twice the maximum value of the coil radius), Dmin is the minimum value of the coil diameter (twice the minimum value of the coil radius), H is the height of the conductive member, P is the coil pitch of the coil shape, W is the thickness of the wires constituting the coil shape, and M is the distance between the central axes of the coil shapes of adjacent conductive members. These parameters can be measured by internal observation using CT-X-rays.

[0048] (Properties of conductive materials) • Volume resistivity The volume resistivity of the conductive material is not particularly limited, as long as it is a value sufficient to allow a small current to flow. The inventors' studies confirmed that the resonant frequency hardly changed between copper with a volume resistivity of 1.55 μΩcm (0°C) and tungsten with a volume resistivity of 4.9 μΩcm (0°C). An example of a value sufficient to allow a small current to flow is the volume resistivity of 3352.8 μΩcm (20°C) when using carbon (graphite).

[0049] • Thermal conductivity The thermal conductivity of the conductive material is not particularly limited. The inventors' investigations confirmed that the resonant frequency hardly changed between copper with a thermal conductivity of 394 W / m·K and tungsten with a thermal conductivity of 174.3 W / m·K.

[0050] [resin] (Composition of the resin) The type of resin is not particularly limited as long as it can contain the conductive material mentioned above, and it may be a thermosetting resin or a thermoplastic resin. However, since high temperatures may occur depending on the application of the electromagnetic wave shielding sheet, a thermosetting resin is preferred. Examples of thermosetting resins include thermosetting resins and photocurable resins. Examples of thermosetting resins include thermosetting acrylic resins, unsaturated polyester resins, epoxy resins, melamine resins, phenolic resins, silicone resins, polyimide resins, urethane resins, etc. Examples of photocurable resins include photocurable epoxy, photocurable polyester, photocurable vinyl compounds, photocurable epoxy (meth)acrylate, or photocurable urethane (meth)acrylate, etc. Among these, unsaturated polyester resins, photocurable polyesters, epoxy resins, or photocurable epoxy are preferred, and epoxy resins or photocurable epoxy are particularly preferred from the viewpoint of heat resistance. These resins may be used individually, or two or more may be used in combination in any type and ratio. Furthermore, from the standpoint of preventing environmental pollution, the resin is preferably made of a biodegradable material, such as cellulose.

[0051] The resin content in the resin molded article is not particularly limited, but from the viewpoint of ensuring sufficient electromagnetic shielding performance, it is usually 60% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and even more preferably 95% by weight or more. It is particularly preferable that the amount be 7% by weight or more, and usually 99.99% by weight or less, preferably 99.90% by weight or less, more preferably 99.5% by weight or less, and even more preferably 99.0% by weight or less.

[0052] (Properties of resin) • Refractive index The refractive index of the resin is not particularly limited, but from the viewpoint of improving electromagnetic wave shielding performance, it is usually 1.05 or higher and 3.00 or lower, and preferably 1.6 or higher and 1.7 or lower for polyester. The refractive index can be measured by known methods.

[0053] ·Volume resistivity The volume resistivity of the resin is not particularly limited, but from the viewpoint of ensuring insulation, the larger it is, the more preferable. For example, 10 6 Ω·cm or more is preferable. The upper limit of the volume resistivity is not particularly limited, but for example, it may be 10 20 Ω·cm or less, and may be 10 18 Ω·cm or less. The volume resistivity of the resin can be measured using a known method for measuring the volume resistivity of a sheet after preparing a sheet-shaped resin.

[0054] [Other components] The resin molded body may have materials other than the above-mentioned conductive member and resin (other materials). For example, inorganic fillers other than the conductive member (including conventional coil-shaped conductive members), or resin fillers, etc. can be mentioned. For example, by adding an inorganic filler, not only can the contact between the conductive members be suppressed, but also the linear expansion coefficient of the resin molded body can be adjusted, thereby making it easy to prevent warping, deflection, undulation, etc., of the resin molded body. The content of the inorganic filler other than the conductive member in the resin molded body is not particularly limited and may be arbitrarily contained within the range where the effects of the present embodiment can be obtained.

[0055] [Sheet] The shape of the resin molded body is not particularly limited and can be appropriately set according to the application. However, from the viewpoint of electromagnetic shielding applications, it is preferably used in a sheet shape. Hereinafter, specific conditions when the resin molded body is in a sheet shape will be described. The sheet shape is not particularly limited as long as it can be recognized as a sheet and can be appropriately changed according to the place where the sheet is installed. The sheet may be a single-layer sheet or a laminated sheet. In the case of a laminated sheet, it may be a mode in which a plurality of sheets that are resin molded bodies according to the present embodiment are laminated, or a mode in which other sheets are laminated to impart various functions.

[0056] The thickness of the sheet is not particularly limited, but from the viewpoint of ensuring sufficient electromagnetic shielding, it is usually 10.0 μm or more, preferably 20.0 μm or more, more preferably 30.0 μm or more, and even more preferably 40.0 μm or more. Furthermore, from the viewpoint of miniaturization, weight reduction, and thinning of electronic devices such as mobile phones, smartphones, and tablets in recent years, it is usually 400.0 μm or less, preferably 300.0 μm or less, more preferably 200.0 μm or less, and even more preferably 100.0 μm or less.

[0057] The sheet's shape is planar, but it may have irregularities to the extent that it can be considered approximately planar, or it may be partially curved. Furthermore, the shape of the sheet observed from the surface may be circular, triangular, quadrilateral, or other polygonal shapes.

[0058] [Characteristics of resin molded products] (Electromagnetic shielding performance) In this disclosure, the electromagnetic shielding performance is evaluated by assessing the power transmittance T(ω) using the following method. This evaluation method is based on terahertz time-domain spectroscopy, which was used in the transmittance measurement experiment. This evaluation is preferably performed using a sheet-shaped resin molded body, and in this case, it is preferable to perform the measurement so that electromagnetic waves are incident in the thickness direction of the sheet shape. A schematic diagram of a terahertz time-domain spectrometer is shown in Figure 6. In terahertz time-domain spectroscopy, the output from one or two femtosecond lasers is generally used as the pump light and probe light. The pump light acts as the light that excites the terahertz wave. The probe light is used to synchronize the timing of the measurement of the terahertz wave. By changing the arrival times of the pump light and probe light, the electric field component of the terahertz wave in the time domain is measured. The electric field E after the terahertz wave has passed through the sample. sam (t) and the electric field E after passing through air without a sample. ref (t) is detected. These values ​​are used to derive the complex refractive index, complex dielectric constant, transmittance, power spectrum, etc. From the data obtained from the above measurements, the transmittance is derived using the Fourier transform. The resulting electric field waveform E sam (t), E ref When we perform a Fourier transform on each of (t), we get E sam (ω), E ref (ω) is obtained. The power transmittance T(ω) is expressed using these equations (A) below.

[0059]

number

[0060] The above transmittance can be measured using a terahertz spectroscopy system (for example, the TAS7500TSH manufactured by Advantest).

[0061] The shield performance L (dB) can be determined from the above power transmission rate T(ω) and the following formula (B). L = 10 × Log 10 (T(ω)) (B) The shielding performance L is not particularly limited, but is preferably -15.0 dB or less. Furthermore, from the viewpoint of preventing malfunctions of electronic devices such as computers, it is preferably -20.0 dB or less, more preferably -30.0 dB or less, even more preferably -40.0 dB or less, particularly preferably -60.0 dB or less, and especially preferably -80.0 dB or less. There is no need to set a lower limit, but it is usually -90.0 dB or higher. The shielding performance of electromagnetic waves is expressed as -20.0 dB (shielding rate: 90%) when the electromagnetic wave amplitude is reduced to 1 / 10, -40.0 dB (shielding rate: 99%) when it is reduced to 1 / 100, -60.0 dB (shielding rate: 99.9%) when it is reduced to 1 / 1000, and -80.0 dB (shielding rate: 99.99%) when it is reduced to 1 / 10000. In particular, an embodiment in which the thickness of the resin molded body is 10.0 μm or more and 100.0 μm or less, and the electromagnetic wave shielding performance determined by electromagnetic wave transmittance measurement is -20.0 dB or less is preferred.

[0062] <Method for manufacturing molded articles> The following describes embodiments relating to various methods for manufacturing resin molded articles, but the above-described methods for manufacturing resin molded articles are not limited to these methods. Furthermore, manufacturing conditions that can be applied to each embodiment can be applied to each other. In addition, to the extent applicable, the conditions for the above-described molded articles can be applied to the conditions for the following manufacturing methods.

[0063] [First manufacturing method] Another embodiment of the present disclosure, the method for manufacturing a first molded article (which in this description will also be simply referred to as the "first manufacturing method"), A composition preparation step to obtain a liquid composition containing a resin and a coil-shaped conductive member. The process includes a curing step which involves curing the liquid composition, The coil pitch of the aforementioned coil shape is 0.5 μm or more and 20.0 μm or less. This is a method for manufacturing a resin molded product. The first manufacturing method may include steps other than the composition preparation step and curing step described above.

[0064] [Composition preparation process] The first manufacturing method includes a composition preparation step to obtain a liquid composition containing the resin and conductive member described above. The method for obtaining the liquid composition containing the resin and conductive member is not particularly limited and includes, for example, a method of mixing liquid resin and conductive member, or a method of dissolving the resin in a solvent to obtain a solution and then mixing the solution with the conductive member. The mixing method is not particularly limited and known methods can be applied. The method for manufacturing the conductive member is not particularly limited; it can be manufactured by known methods, or it can be manufactured using a 3D printer.

[0065] When using a solvent, the type of solvent is not particularly limited as long as it can dissolve the resin mentioned above and any other materials that need to be dissolved. Furthermore, if molding is possible without using a solvent, then the solvent may be omitted. Furthermore, a curing agent may be added depending on the type of resin used, and any known type of curing agent can be used as appropriate depending on the resin. The curing agent content in the composition can be, for example, 0.05 to 15% by mass. Furthermore, a polymerization initiator may be added depending on the type of resin used. For example, a thermal radical generator such as a peroxide like benzoyl peroxide can be used as a thermal polymerization initiator, and a photoradical generator, photocation generator, or photoanion generator can be used as a photopolymerization initiator.

[0066] Another embodiment of the present disclosure is a liquid composition, Includes resin and coil-shaped conductive members, The coil pitch of the aforementioned coil shape is 0.5 μm or more and 15.0 μm or less. It is a liquid composition, and there are no particular limitations on its manufacturing method, but it can be obtained by the method described in the liquid composition preparation process. Another embodiment of the present disclosure is a molded article which is a cured product of the above-described liquid composition. The conditions for the molded article can be similarly applied to the conditions for the molded article described above.

[0067] [Curing process] The first manufacturing method includes a curing step, which involves curing the liquid composition described above. The curing method is not particularly limited and can be appropriately changed depending on the type of resin. For example, curing can be done using heat or light such as ultraviolet light. Furthermore, if the resin used is a thermoplastic resin and the composition is prepared in a molten state after applying heat, curing can be done by natural standing or cooling. The curing temperature and time vary depending on the material used and are not particularly limited as long as they are sufficient to cure the composition.

[0068] [Second manufacturing method] Another embodiment of the present disclosure, a second method for manufacturing a molded article (which in this description will also be simply referred to as the "second manufacturing method"), A method for manufacturing a resin molded article including a resin and a coil-shaped conductive member, A process for producing a resin sheet containing a C-shaped conductive member, comprising producing a plurality of resin sheets having the resin, a C-shaped conductive member, and a columnar conductive member connected to the end of the C-shape, and A lamination process in which multiple resin sheets are laminated such that the end of a C-shaped conductive member on one sheet and a columnar conductive member on the other sheet are in contact in the direction of the central axis. Includes, The coil pitch of the aforementioned coil shape is 0.5 μm or more and 15.0 μm or less. This is a method for manufacturing a resin molded product.

[0069] The second manufacturing method comprises the above-described step of producing a resin sheet containing a C-shaped conductive member and a lamination step, but may also include other steps. An example of the second manufacturing method, including these other steps, is shown below.

[0070] [Resin composition manufacturing process] The second manufacturing method may include a resin composition preparation step in which the above-mentioned resins and other materials are dissolved in a solvent and mixed to produce a resin composition. The conditions for this step can be similarly applied to the resin composition preparation step in the first manufacturing method.

[0071] [Process for manufacturing C-shaped conductive material-containing resin sheet] The second manufacturing method includes a step for producing a resin sheet containing a C-shaped conductive member, which involves producing a plurality of resin sheets, each having a resin, a C-shaped conductive member, and a columnar conductive member connected to the end of the C-shape. The method for producing such a resin sheet is not particularly limited, but for example, one method involves preparing a mold in which the C-shaped conductive member and the columnar conductive member are arranged, pouring the resin composition obtained in the above resin composition production step into the mold, curing the resin, and obtaining a resin sheet containing a C-shaped conductive member, as shown in Figure 7, having a cured resin composition 11 (also simply referred to as "resin 11"), a C-shaped conductive member 12, and a columnar conductive member 13. Methods for curing the resin include using heat or light such as ultraviolet light. Furthermore, methods commonly used in the manufacture of printed circuit boards can be used. Specifically, after producing a resin sheet by curing the above resin composition, holes (vias) are drilled or lasered in the locations where the columnar conductive members will be placed, forming foil-shaped conductive members on one side of the sheet. Then, a photosensitive resist is coated or laminated in a pattern such that the foil-shaped conductive members remain in a C shape after etching, and then etching is performed to laminate the C-shaped conductive members onto the resin sheet. As a method for laminating C-shaped conductive members onto a resin sheet using etching, in addition to the above method using a photosensitive resist, it may also be done by printing an etching resist pattern. Subsequently, a paste of the conductive member is poured into the holes and cured to form columnar conductive members, thereby obtaining a resin sheet containing C-shaped conductive members. It is preferable that no air remains in the columnar areas, as this can increase the volume resistivity and may cause expansion, explosion, and destruction at the reflow temperature of semiconductor component mounting. The parameters for the C-shaped conductive member and the columnar conductive member can be appropriately set based on the description of each parameter in the resin molded body described above. Furthermore, in the embodiment using the C-shaped conductive member described above, the average angle between the plane of the sheet and its central axis is subject to the average angle conditions described above.

[0072] [Lamination process] The second manufacturing method involves, among the multiple sheets produced in the above-described process for producing a resin sheet containing a C-shaped conductive member, the end of the C-shaped conductive member in one sheet and the other sheet The process involves laminating multiple resin sheets so that they are in contact with a columnar conductive member in the direction of the central axis. One lamination method is to laminate the sheets so that the end of a C-shaped conductive member on one sheet is in contact with a columnar conductive member on the other sheet in the direction of the central axis, as shown in Figure 8.

[0073] <Applications of molded products> Applications of the molded body described above include electromagnetic shielding, and another embodiment of this disclosure is an electromagnetic shield having the molded body described above.

[0074] Another embodiment of the present invention has the above-described molded body, Semiconductor modules containing semiconductor devices (for example, modules in which semiconductor elements are covered and packaged in a molded body, such as SOP, QFP, QFN, BGA, etc.); Electronic devices or telecommunications equipment such as smartphones, tablets, smartwatches, smart security devices, surveillance devices, or smart home appliances; Automotive equipment such as safety systems, mobile media, communications, wireless headsets, battery-powered, electric, or hybrid powertrains, or high-voltage battery systems; consumer electronics such as computer circuits, wireless transmitters (including smartphones), electric motors, flat panel displays, or liquid crystal displays (LCDs); Medical devices such as smart beds, ventilators, CT scanners, or transducers that need to acquire information such as pulse and blood pressure and convert it into electronic signals; Aerospace equipment such as aircraft, vehicles, elastomer gaskets, conductive paints, or EMI shielding displays; Systems such as railway systems, mass transit systems, high-voltage contact switching systems, signal transmission systems, or control systems; or Other equipment (equipment other than those listed above that may be equipped with molded bodies); And so on. The manner in which the molded body is used in each of the above embodiments is not particularly limited, and any configuration in which the molded body is included as a single component is acceptable. Furthermore, each embodiment is particularly preferably used for applications as an electromagnetic wave shielding sheet.

[0075] In particular, when used as an electromagnetic shielding sheet, it can be used arbitrarily for any purpose of shielding electromagnetic waves. For example, by installing the electromagnetic shielding sheet around electronic devices that may malfunction due to electromagnetic waves, such malfunctions can be suppressed. In particular, the above-mentioned electromagnetic shielding sheet is superior to conventional electromagnetic shielding sheets in shielding electromagnetic waves in the high-frequency band. Therefore, it can shield from electromagnetic waves originating from communication devices such as mobile phones and smartphones, which are being developed to operate at higher frequencies, especially above 100 GHz, for the purpose of increasing speed, capacity, and latency. This makes it applicable to a wider range of fields than conventional electromagnetic shielding sheets. Furthermore, with the above-mentioned sheet, a particularly large electromagnetic shielding effect can be obtained when the plane of the sheet is perpendicular to the direction in which the electromagnetic waves are coming from the outside. [Examples]

[0076] The present disclosure will be further described below with reference to examples. However, this disclosure shall not be construed as being limited to the following examples.

[0077] <Experiment A: Simulation Experiment> We conducted a simulation experiment to evaluate the electromagnetic shielding performance L(dB) of a resin molded body using ANSYS HFSS®, a full-wave 3D electromagnetic field software from ANSYS Incorporated.

[0078] As shown in Figure 9, the base of a rectangular parallelepiped resin molded body has resin and coil-shaped conductive members arranged on it. A simulation experiment was conducted in which a model was created in which this configuration was arranged infinitely in the X-axis and Y-axis directions, and electromagnetic waves were incident from direction A to measure the electromagnetic shielding performance L (dB). Note that the conditions such as the number of turns of the coil shape constituting the conductive member shown in Figure 9 are merely examples, and the actual input values ​​are as shown in Table 1. The simulation experiment was conducted under the conditions shown below and the conditions shown in Table 1, which will be described later.

[0079] [Basic form size] • Length in the X direction Lx: Same as M listed in Table 1 • Length in the Y direction Ly: Same as M listed in Table 1. • Length Lz in the Z direction: Same as H listed in Table 1.

[0080] [Resin conditions] The resin conditions were set as follows: real part of dielectric constant ε' and dielectric loss tangent tanδ. Specifically, the real part of the dielectric constant was expressed using the value shown in equation (1) below, and the dielectric loss tangent was expressed using the value shown in equation (2) below. n' is the real part of the refractive index, and n'' is the imaginary part of the refractive index. These were set assuming average values ​​for typical polyesters and are known calculation formulas. The real part of the permittivity ε' = n' 2 -n” 2 (1) Dielectric loss tangent tanδ = (2n'n) / (n' 2 -n” 2 ) (2)

[0081] [Conditions for conductive materials] • Coil radius R: See Table 1 • Height H of conductive material: See Table 1 • Coil shape and coil pitch P: See Table 1 • Thickness W of the wires that make up the coil shape: See Table 1 • Distance M between the central axes of the coil shapes of adjacent conductive members: See Table 1 • Number of turns in the coil shape: As shown in the table: As shown in Table 1 The starting point (S in Figure 9) and ending point (E in Figure 9) of the coil shape were positioned such that their Y-direction coincided with the center of the coil, and their X-direction was in the positive direction of the X-axis (to the right in Figure 9). Note that the notation for the start and end points of the coil shape is a convenient notation for indicating the winding direction. The endpoint of the coil shape on the negative side of the Z-axis (downward side in Figure 9) is called the start point, and the endpoint of the coil shape on the positive side of the Z-axis (upward side in Figure 9) is called the end point. The conductivity of the conductive material was determined using the value for tungsten. Specifically, "MA Ordal, RJ The tungsten plasma frequency of 5.17 × 10⁻¹⁰ is reported in the paper "Bell, RW Alexander, LL Long, and MR Querry, Appl. Opt. 24, 4493 (1985)." 4 cm -1 oh and scattering frequency 4.87 × 10⁻⁶ 2 cm -1 The calculations were performed using conductivity with frequency characteristics calculated from the Drude model.

[0082] [Conditions for electromagnetic waves] The response was calculated when electromagnetic waves polarized in the Y direction in Figure 9, with frequencies ranging from 100 GHz to 500 GHz, were incident from the negative Z direction to the positive Z direction in Figure 9. The electromagnetic waves polarized in the Y direction and X direction in Figure 9 are denoted as "Y-polarized" and "X-polarized," respectively.

[0083] [Evaluation of electromagnetic shielding performance level L] The electromagnetic shielding performance was evaluated by calculating the shielding performance L(dB) from the power transmittance T(ω) obtained by performing an electromagnetic field simulation, based on the following equation (B). L = 10 × Log 10 (T(ω)) (B) Furthermore, the power reflectance R(ω) was calculated from the electromagnetic field simulation, and the power transmittance T(ω) was also calculated. The power absorption rate A(ω) was calculated based on the following formula (C) in conjunction with ). A = 1 - T(ω) - R(ω) (C) The evaluation results of the electromagnetic shielding performance L for each resin molded product are shown in Figures 10 and 11 and Table 1 below. Note that the shielding performance L shown in Table 1 is the value evaluated at a frequency of 300 GHz. Absorption and reflectance are expressed as percentages, and the values ​​calculated above have been multiplied by 100. Also, the graphs in Figures 10 and 11 do not show all the data listed in Table 1, but only a portion of it. Specifically, the experimental results for Examples 1-5 and Comparative Example 1 in Table 1 correspond to the graphs in Figure 10, and the experimental results for Examples 6-8 in Table 1 correspond to the graphs in Figure 11. In the embodiments described herein, the electromagnetic shielding performance L was evaluated using values ​​measured with polarization in the Y-axis direction.

[0084] [Table 1]

[0085] Next, as shown in Figure 12, a model was set up in which the basic form of a rectangular resin molded body, which has resin and conductive members in the shape of a coil and a tapered shape arranged infinitely in the X-axis and Y-axis directions, and a simulation experiment was conducted to measure the electromagnetic shielding performance L (dB) by injecting electromagnetic waves from direction A. The simulation experiment was conducted under the same conditions as in Example 1 described above, except that the conditions for the conductive material were changed as follows.

[0086] [Basic form size] • Length in the X direction Lx: Same as M listed in Table 2 • Length in the Y direction Ly: Same as M listed in Table 2. • Length Lz in the Z direction: Same as H listed in Table 2.

[0087] [Resin conditions] The resin conditions were set to be the same as those for Example 1 described above.

[0088] [Conditions for conductive materials] • Maximum coil radius Rmax: See Table 2 • Decrease in coil radius per turn (decrease amount): See Table 2. • Height H of conductive material: See Table 2 • Coil shape and coil pitch P: See Table 2. • Thickness W of the wires that make up the coil shape: See Table 2 • Distance M between the central axes of the coil shapes of adjacent conductive members (same as the length of the resin in the X and Y directions): See Table 2. The start and end points of the coil were positioned such that, in Figure 12, the Y-direction coincided with the center of the coil and the X-direction was in the positive direction of the X-axis. The conductivity of the conductive member was set under the same conditions as in Example 1 described above.

[0089] [Conditions for electromagnetic waves] The electromagnetic wave conditions were set to be the same as those in Example 1 described above.

[0090] [Evaluation of electromagnetic shielding performance level L] The electromagnetic shielding performance L was evaluated using the same method as in Example 1 described above. The evaluation results of the electromagnetic shielding performance L for each resin molded product are shown in Figure 13 and Table 2 below. Note that the shielding performance L, absorptivity, and reflectivity shown in Table 2 are values ​​evaluated at a frequency of 300 GHz. Furthermore, the absorptivity and reflectivity are expressed as percentages, and the values ​​calculated above have been multiplied by 100.

[0091] [Table 2]

[0092] From Table 1 and Figures 10, 11, and 13, the influence of each parameter of the shielding material on shielding performance was revealed as follows. Table 1 and Figures 10 and 11 show that when the coil pitch is between 0.5 μm and 20.0 μm, the electromagnetic shielding performance L at 300 GHz is excellent. In particular, even when the coil pitch was reduced to 3 μm, excellent electromagnetic shielding performance L of approximately -20 dB at 300 GHz could be maintained. On the other hand, coils that were not tapered and achieved a shielding performance L of -20.0 dB tended to have higher reflectivity, with the lowest being 74.3% in Example 8. In contrast, the results for the tapered coils shown in Table 2 and Figure 13 demonstrated that it is possible to suppress reflectivity while maintaining high shielding performance, with an electromagnetic wave shielding performance L of -20.8 dB and a reflectivity of 44.3% at 300 GHz with a maximum radius of 128.5 μm.

[0093] <Experiment B: Verification of the simulation experiment> The electromagnetic shielding performance of a sheet-shaped resin molded body was actually fabricated and evaluated, and the results were compared and verified with those of the simulation experiment. Note that the resin molded body used in this experiment B differs from the resin molded body according to the embodiment of this disclosure. Specifically, instead of a conductive member in which at least a portion of the coil shape is tapered, a conventional conductive member with a constant coil radius was used to manufacture the resin molded body, and the electromagnetic shielding performance was evaluated. In Reference Example 1, the electromagnetic waves incident on the resin molded body are linearly polarized. However, the orientation of the start and end points of the coil in the actually fabricated sheet could not be controlled and was randomly distributed, so the direction of polarization of the electromagnetic waves relative to the coil could not be specified. In the simulation experiment of Reference Example 2, in order to incorporate the effect of the random distribution of the coil start and end points in Reference Example 1, the response to electromagnetic waves polarized in the Y and X directions was calculated separately, and then the average was calculated.

[0094] [Actual sheet manufacturing: Reference example 1] The following resin material was poured into a mold capable of producing a sheet with an overall size of 30 mm (length) x 30 mm (width) and 60 pockets (through holes) with an outer diameter of 350 μm, arranged in a grid pattern with a center-to-center distance of 500 μm between the holes. The center-to-center distance of these holes corresponds to the coil alignment pitch. In this process, the lattice-like arrangement of pockets was positioned at the center of the sheet, that is, the center of the lattice-like arrangement and the center of the sheet were aligned. Subsequently, the resin material described below was heated at a curing temperature of 120°C for 10 minutes to obtain a cured sheet. After that, the cured sheet was placed in an oven and heated at 150°C for 60 minutes to obtain a pocket-containing sheet. Subsequently, the following conductive material components were placed in all pockets of this pocket-containing sheet such that the average angle between the central axis of the metal coil and the planar direction of the sheet was 90°. Subsequently, while maintaining the arrangement of the conductive material members described above, a resin similar to the resin material described above was poured into each pocket of the sheet, and after curing under the same curing conditions as described above, the resulting sheet was ground to a thickness of 2 mm to obtain a 2 mm thick sheet.

[0095] (raw materials) • Resin material: A mixture of cold-embedded resin JP-21111001 (polyester resin) manufactured by Struas Co., Ltd. and a hardener (M agent) also manufactured by Struas Co., Ltd. The mixing ratio is cold embedding resin:hardener = 100 mL:1.5 mL, and the curing time is 40 minutes at room temperature. • Conductive material: A coil-shaped conductive material was used that met the conditions shown in the sheet manufacturing description below and the conditions shown in Table 2 below.

[0096] (Sheet manufacturing) Tungsten coils with an outer diameter of 300 μm, a wire diameter of 30 μm, and a pitch of 60 μm were arranged in a grid pattern in a resin material with a period of 500 μm. The orientation of the coils was perpendicular to the in-plane direction of the sheet. After the resin cured, the sheet was ground down to a thickness of 2 mm and a coil length of 2 mm, resulting in a 2 mm thick sheet.

[0097] [Electromagnetic shielding performance] The electromagnetic shielding performance was evaluated by measuring the power transmittance T(ω) and power reflectance R(ω) using a terahertz spectroscopy system (TAS7500TSH manufactured by Advantest). Next, the shield performance L(dB) was calculated from the power transmittance T(ω) obtained by measurement, based on the following formula (B). L = 10 × Log 10 (T(ω)) (B) Furthermore, based on the following formula (C), the power reflectance R(ω) and power transmittance T(ω) are combined and the power reflectance R(ω) is calculated. The Wah absorption rate A(ω) was calculated. A = 1 - T(ω) - R(ω) (C) The table shows the evaluation results of the electromagnetic shielding performance L for each sheet. Note that the shielding performance L shown in the table is the value evaluated at a frequency of 300 GHz. The evaluation results for the electromagnetic shielding performance L of the resin molded body are shown in Table 3 below. Note that the shielding performance L, absorptivity, and reflectivity shown in Table 3 are values ​​evaluated at a frequency of 300 GHz. Absorptivity and reflectivity are expressed as percentages, and the values ​​calculated above have been multiplied by 100.

[0098] [Simulation Experiment: Reference Example 2] We conducted a simulation experiment to evaluate the electromagnetic shielding performance L(dB) of a resin molded body using ANSYS HFSS®, a full-wave 3D electromagnetic field software from ANSYS Incorporated.

[0099] As shown in Figure 9, a model was created in which a rectangular resin molded body, with resin and coil-shaped conductive members arranged in an infinite number of positions in the X and Y axes, and a simulation experiment was conducted to measure the electromagnetic shielding performance L (dB) by injecting electromagnetic waves from direction A. Note that the conditions such as the number of turns of the coil shape constituting the conductive member shown in Figure 9 are merely examples, and the actual input values ​​are as shown in Table 3. The simulation experiment was conducted under the conditions shown below and the conditions shown in Table 3 described later.

[0100] [Basic form size] • Length in the X direction Lx: Same as M listed in Table 3. • Length in the Y direction Ly: Same as M listed in Table 3. • Length Lz in the Z direction: Same as H listed in Table 3.

[0101] [Resin conditions] [Resin conditions] The resin conditions were set as follows: real part of dielectric constant ε' and dielectric loss tangent tanδ. Specifically, the real part of the dielectric constant was expressed using the value shown in equation (1) below, and the dielectric loss tangent was expressed using the value shown in equation (2) below. n' is the real part of the refractive index, and n'' is the imaginary part of the refractive index. These were set assuming average values ​​for typical polyesters and are known calculation formulas. The real part of the permittivity ε' = n' 2 -n” 2 (1) Dielectric loss tangent tanδ = (2n'n) / (n' 2 -n” 2 ) (2)

[0102] [Conditions for conductive materials] • Coil radius R: See Table 3 • Height H of conductive material: See Table 3 • Coil shape and coil pitch P: See Table 3. • Thickness W of the wires that make up the coil shape: See Table 3 • Distance M between the central axes of the coil shapes of adjacent conductive members (same as the length of the resin in the X and Y directions): See Table 3. • Number of turns in the coil shape: 32.8 • Winding direction of the coil shape: Same as in Example 1. The conductivity of the conductive member was set under the same conditions as in Example 1 described above.

[0103] [Conditions for electromagnetic waves] The electromagnetic wave conditions were the same as in Comparative Example 1.

[0104] [Evaluation of electromagnetic shielding properties] As part of the electromagnetic shielding characteristics, the absorption and reflectivity of electromagnetic waves were evaluated, using the same method as the measurement of the electromagnetic shielding performance L in Experiment A described above. The evaluation results for electromagnetic shielding performance L are shown in Table 3 below. Note that the shielding performance L shown in Table 3 is the value evaluated at a frequency of 300 GHz. Absorption and reflection rates are expressed as percentages, and the values ​​calculated above have been multiplied by 100.

[0105] [Table 3]

[0106] Table 3 shows that the measured reflectance and absorptance at 300 GHz were 60.9% and 39.1%, respectively, which were close to the simulation results of 61.7% and 38.3%. As the simulation results correspond well to the measured values, the effectiveness of the characterization of the shielding material by simulation used in the embodiment of this disclosure is demonstrated.

[0107] From the above, it was found that by including a resin and a coil-shaped conductive member, and configuring the coil-shaped conductive member to have a coil pitch of 0.5 μm to 20.0 μm, it is possible to provide a resin molded body that has excellent electromagnetic wave shielding characteristics, is easy to miniaturize, and enables shielding of high-frequency electromagnetic waves with a high degree of design freedom. [Explanation of symbols]

[0108] 10 C-shaped conductive material-containing resin sheet 11 resin 12 C-shaped conductive member 13. Columnar conductive member

Claims

1. A resin molded article comprising resin and a coil-shaped conductive member, The coil pitch of the aforementioned coil shape is 0.5 μm or more and 20.0 μm or less. Resin molded body.

2. The resin molded article according to claim 1, wherein the thickness of the strands constituting the coil shape is 0.1 μm or more and 10.0 μm or less.

3. The thickness is 10.0 μm or more and 100.0 μm or less. The resin molded article according to claim 1, wherein the electromagnetic wave shielding performance determined by electromagnetic wave transmittance measurement is -20.0 dB or less.

4. The resin molded article according to claim 1, wherein the number of turns of the coil shape is 3 or more and 100 or less.

5. The resin molded article according to claim 1, wherein the ratio of the coil radius to the height of the conductive member is 0.4 or more and 5.0 or less.

6. The resin molded body according to claim 1, wherein the number of conductive members included in the resin molded body is two or more.

7. The resin molded article according to claim 6, wherein the distance between the central axes of the coil shapes of adjacent conductive members is 5.0 μm or more and 1000.0 μm or less.

8. The resin molded article according to claim 1, wherein at least a portion of the coil shape is a tapered shape in which the coil radius gradually increases or decreases.

9. The minimum value of the coil radius is 5.0 μm or more. The maximum value of the coil radius is 1000.0 μm or less. The resin molded article according to claim 8.

10. A resin molded article according to claim 1, which is in the shape of a sheet.

11. The resin molded article according to claim 10, which is an electromagnetic wave shielding sheet.

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