JP7162439B2 - electromagnetic wave shield - Google Patents

Description

The present invention relates to an electromagnetic wave shield, and more particularly to an electromagnetic wave shield in which a layered portion made of a material having electromagnetic shielding performance is formed on a base portion.

A vehicle such as a hybrid vehicle is equipped with electronic devices such as a PCU (power control unit) and an ECU (electronic control unit) housed in a dedicated housing. In recent years, this type of unit is becoming mainstream to be arranged in the engine room. In the engine room, there are several devices that generate electromagnetic waves, such as various motors, and the PCU and the like are in an environment where they are constantly exposed to electromagnetic waves. Therefore, in order to protect the PCU and the like from electromagnetic interference (EMI), a metal (for example, aluminum die-cast) housing for shielding electromagnetic waves is conventionally used.

By the way, although a metal housing can effectively shield electromagnetic waves, it inevitably leads to an increase in weight, which has a negative effect on reducing the weight of the vehicle as a whole. Therefore, in recent years, proposals have been made to form a housing using a synthetic resin material that is lighter than metal. However, although synthetic resin housings are lightweight and excellent in moldability and corrosion resistance, they have the disadvantage that, unlike metal materials, synthetic resin materials themselves do not have electromagnetic shielding performance. Therefore, an electromagnetic wave shielding housing has been conventionally proposed in which a resin material is used as a base portion and a layer (layered portion) made of a metal material having electromagnetic shielding performance is formed on one side of the base portion (for example, see Patent Documents 1 and 2). reference). Patent Document 1 discloses that an aluminum deposition layer is formed as a layered portion on the inner surface of a resin molding. Further, Patent Document 2 discloses that an aluminum foil is adhered as a layered portion to the inner surface of a resin molding.

JP 2012-228904 A JP-A-04-135815

In the case of the electromagnetic wave shielding housing of the prior art, if the thickness of the layered portion made of the metal material is small, the desired electromagnetic shielding performance cannot be imparted, and the PCU and the like cannot be protected from electromagnetic waves. . When the layered portion made of a metal material is formed to a certain thickness, it is possible to impart desired electromagnetic shielding performance, but as a result of an increase in the amount of metal material used, the cost of the electromagnetic wave shielding housing increases. lead to weight gain.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electromagnetic wave shield capable of imparting desired electromagnetic shielding performance while suppressing the thickness of the layered portion formed on the base portion. is to provide

In order to solve the above problems, the invention described in means 1 is an electromagnetic wave shield exposed to electromagnetic waves of 1 GHz or more, which is an injection molded PPS resin product having a front surface and a back surface and having a thickness of 1.0 mm or more. and the material forming the base portion are made of materials having different conductivities, are formed along the surface direction of the base portion, and are formed on the front surface and the back surface of the base portion. A plurality of layered portions are formed so as to cover the back surface and are spaced apart from each other by a thickness of 1.0 mm or more in the stacking direction, and the plurality of layered portions are all formed by sputtering. In the case where each of the aluminum layers has an equal thickness of 0.1 μm or more and 1.0 μm or less, and the total thickness of the layered portions of the plurality of layers is T, electromagnetic shielding is performed using an evaluation jig. The electromagnetic wave transmission attenuation, which is the shielding performance at 1 GHz to 6 GHz, measured by the coaxial tube method for evaluating the electromagnetic wave transmission attenuation of the material has a common structure except that the layered portion is a single layer and has a thickness of T. It is higher than the shielding performance at 1 GHz to 6 GHz measured by the same method for a sample having an electromagnetic wave characterized by being 60 dB or more of the electromagnetic shielding performance when a blank is not placed on the evaluation jig. The gist of it is shielding.
The invention described in means 2 is an electromagnetic wave shielding body exposed to electromagnetic waves of 1 GHz or higher, which comprises a base portion which is an injection-molded body made of PPS resin and having a front surface and a back surface and having a thickness of 1.0 mm or more; made of a material having a conductivity different from that of the material forming the portion, formed along the surface direction of the base portion, and formed on the front surface and the back surface of the base portion so as to cover the front surface and the back surface; Thus, a plurality of layered portions are arranged with a thickness of 1.0 mm or more from each other in the stacking direction, and the plurality of layered portions are formed by sputtering and have a thickness of 0.2 μm or more and 1.0 μm or less. and a second stainless alloy layer of 0.2 μm or more and 1.0 μm or less or a copper layer of 0.5 μm formed by sputtering, and the second stainless alloy layer or the When the copper layer has the same thickness as the first stainless alloy layer and the total thickness of the layered portions of the plurality of layers is T, the electromagnetic wave transmission attenuation amount of the electromagnetic wave shielding material is evaluated using an evaluation jig. The electromagnetic wave transmission attenuation, which is the shielding performance at 1 GHz to 6 GHz, measured by the coaxial tube method that performs The gist of the present invention is an electromagnetic shielding material characterized by being higher than the measured shielding performance at 1 GHz to 6 GHz and having 50 dB or more of the electromagnetic shielding performance of a blank in which no sample is placed on the evaluation jig.

Therefore, according to the inventions described in means 1 and 2, by arranging a plurality of layered portions apart from each other in the stacking direction, the shielding performance (shielding performance in the plane direction) is higher than when the layered portion is a single layer. can be imparted, and electromagnetic waves can be effectively shielded. Therefore, it is possible to provide desired electromagnetic shielding performance while suppressing the thickness of the layered portion.

The gist of the invention described in means 3 is that, in means 1 or 2 , the electronic device housing forms a part of a vehicle-mounted electronic device housing.

Therefore, according to the invention described in means 3 , it is possible to effectively protect an electronic device mounted on a vehicle from electromagnetic waves.

As described in detail above, according to the inventions described in claims 1 to 3 , there is provided an electromagnetic wave shield capable of imparting desired electromagnetic shielding performance while suppressing the thickness of the layered portion formed on the base portion. can be provided.

1 is a schematic perspective view showing an electromagnetic wave shielding body (electromagnetic wave shielding cover) of an embodiment embodying the present invention; FIG. FIG. 2 is an enlarged cross-sectional view of the main part of the electromagnetic wave shielding cover of the embodiment; 5 is a graph showing the relationship between frequency and electric field shielding performance when the same kind of metal is used in an example embodying the embodiment; 5 is a graph showing the relationship between frequency and magnetic field shielding performance when the same kind of metal is used in an example embodying the embodiment; 5 is a graph showing the relationship between frequency and electromagnetic shielding performance when the same kind of metal is used in an example embodying the embodiment; 5 is a graph showing the relationship between frequency and electric field shielding performance when the same kind of metal is used in an example embodying the embodiment; 5 is a graph showing the relationship between frequency and magnetic field shielding performance when the same kind of metal is used in an example embodying the embodiment; 5 is a graph showing the relationship between frequency and electromagnetic shielding performance when the same kind of metal is used in an example embodying the embodiment; 5 is a graph showing the relationship between frequency and electric field shielding performance when dissimilar metals are used in an example embodying the embodiment; 5 is a graph showing the relationship between frequency and magnetic field shielding performance when dissimilar metals are used in an example embodying the embodiment; 5 is a graph showing the relationship between frequency and electromagnetic shielding performance when dissimilar metals are used in an example embodying the embodiment;

An embodiment embodying an electromagnetic wave shield of the present invention will be described in detail below with reference to FIGS. 1 to 11. FIG.

As shown in FIG. 1, the electromagnetic wave shielding body of the present embodiment forms a part of a vehicle-mounted PCU housing 1 (electronic equipment housing) disposed in an engine room. is an electromagnetic wave shielding cover 3 for closing the upper opening of a bottomed box-shaped aluminum housing body 2 . The PCU housing 1 accommodates a wiring board 4 on which circuits for motor control and engine control of a hybrid vehicle are configured, for example. This PCU housing 1 is used in a state where it is exposed to electromagnetic waves of 100 MHz or higher, particularly 1 GHz or higher, for example.

As shown in FIG. 2, the electromagnetic wave shielding cover 3 includes a base portion 11 and a layered portion 12. As shown in FIG.

The base portion 11 constituting the electromagnetic wave shielding cover 3 is a molded body having a front surface 11a and a back surface 11b. Here, the base portion 11 is not particularly limited as long as it has a shape having a front surface 11a and a back surface 11b. Preferably. This is because the plate-like portion has a front surface 11a and a back surface 11b and is suitable as a place for forming the layered portion 12 of multiple layers. Note that the plate-like portion may not necessarily be flat, and may be curved or have a step, for example. The thickness of the plate-like portion is arbitrary and not particularly limited, but is set to, for example, 0.1 mm or more, further 0.5 mm or more, particularly 1.0 mm or more. Moreover, the size of the base portion 11 is arbitrary, and is determined according to the size of the wiring board 4 to be accommodated.

The material forming the base portion 11 is not particularly limited, and can be widely selected from, for example, synthetic resin, wood, paper, ceramics, and metal. In view of the point of use, synthetic resin is particularly suitable because it has properties such as light weight and insulating properties. As a molding method for obtaining the base portion 11, which is a molded body, various conventionally known techniques can be employed. Specifically, for example, not only methods using molds such as press molding and injection molding, but also methods not using molds (cutting, 3D printing, etc.) are allowed. Here, an injection-molded body made of a thermoplastic resin can be mentioned as a suitable base portion 11 . This is because an injection-molded article made of a thermoplastic resin is excellent in moldability, cost efficiency, light weight, workability, insulating properties, and the like. Specific examples of thermoplastic resins include PPS resins, PBT resins, PA resins, PP resins, PPE resins, ABS resins, etc. Among these, it is preferable to select PPS resins. This is because PPS resin is a general-purpose product and is relatively inexpensive. In addition, the PPS resin is compatible with many metal materials such as aluminum, so that the adhesiveness of the layered portion 12 can be improved. Here, it is preferable to select an injection-molded body made of a material containing inorganic fibers in a matrix of PPS resin as the base portion 11. This provides the electromagnetic wave shielding cover 3 with high shape stability and adhesion of the layered portion 12. becomes easier to obtain.

The layered portion 12 constituting the electromagnetic wave shielding cover 3 is formed in multiple layers along the surface direction of the base portion 11 (that is, the front surface 11a and the rear surface 11b). The number of layers of the layered portion 12 is not limited to two layers, and may be three layers, four layers, or the like. These multiple layered portions 12 are spaced apart from each other in the stacking direction perpendicular to the surface direction. When the layered portions 12 of a plurality of layers are not separated from each other in the stacking direction and are arranged in close contact with each other, they are substantially regarded as a single layer. Therefore, the desired electromagnetic shielding effect cannot be obtained unless the thickness is formed to some extent.

At least one layer of the multiple layers of the layered portion 12 is preferably formed on the surface layer of the base portion 11 (that is, on the front surface 11a or the rear surface 11b), and particularly formed on the front surface 11a and the rear surface 11b. It is desirable that In this case, since the substrate portion 11 is interposed between the layered portions 12 of the plurality of layers, the layered portions 12 of the plurality of layers can be arranged at a distance corresponding to the thickness of the substrate portion 11 . . Moreover, in the case of such an arrangement mode, the layered portion 12 having multiple layers can be formed relatively easily. The layered portion 12 having multiple layers may be formed so as to completely cover the front surface 11a and the back surface 11b of the base portion 11, or may be formed so as to cover only a specific portion. Furthermore, the layered portion 12 of multiple layers may or may not cover the side surface of the base portion 11, in other words, the surface positioned between the front surface 11a and the rear surface 11b and perpendicular thereto. Of course, at least one layer of the multiple layers of the layered portion 12 may be formed as an inner layer of the base portion 11, or all the layers may be formed as an inner layer. Here, the adjacent layered portions 12 of a plurality of layers may not only be spaced apart from each other with part or all of the base portion 11 separated, but may also be spaced apart from each other with a gap. In other words, the layered portion 12 does not necessarily need to be directly in surface contact with and supported by the substrate portion 11, which is a support. It may be supported by point contact or the like.

The layered portion 12 having multiple layers is preferably made of a material having conductivity different from that of the material forming the base portion 11 , specifically, made of a material having a higher conductivity than the material forming the base portion 11 . This is because it is difficult to provide a suitable electric field shielding effect unless such a material is used. Moreover, it is preferable that the layered portion 12 of multiple layers be made of a material having a higher magnetic permeability than the material forming the base portion 11 . This is because it is difficult to provide a suitable magnetic field shielding effect if the material is not such a material.

For example, when the base portion 11 is formed of a synthetic resin material, a metal layer, a carbon layer, a ceramic layer, or the like can be selected as the layered portion 12 having multiple layers, and it is particularly preferable to select a metal layer. . This is because, in general, among metal materials, there are not a few materials having higher electrical conductivity and magnetic permeability than synthetic resin materials, so there is a large degree of freedom in material selection. Specific examples of such metal layers include metal layers made of gold, silver, copper, platinum, iron, aluminum, titanium, nickel, cobalt, chromium, tin, lead, etc., and alloys containing these metals as components. Layers (eg, stainless alloy layers, solder alloy layers, etc.) can be mentioned. Among these, an aluminum layer is particularly suitable. This is because aluminum is an inexpensive metal material, which contributes to cost reduction, and is relatively lightweight, which contributes to overall weight reduction.

Each layer of the layered portion 12 having a plurality of layers may be formed using the same kind of metal material, or each layer may be formed using a different kind of metal material. As specific examples of the former, for example, an aspect in which an aluminum layer is formed on the front surface 11a side and an aluminum layer on the back surface 11b side, an aspect in which a copper layer is formed on the front surface 11a side and a copper layer on the back surface 11b side, and a surface 11a side and a stainless alloy layer formed on the rear surface 11b side. As a specific example of the latter, for example, an aspect in which an aluminum layer is formed on the front surface 11a side and a copper layer is formed on the back surface 11b side, an aspect in which an aluminum layer is formed on the front surface 11a side and a stainless alloy layer is formed on the back surface 11b side, and a surface 11a A mode in which a copper layer is formed on the side and a stainless alloy layer is formed on the back surface 11b side.

The metal layer typified by aluminum is formed on the surface 11a and the back surface 11b of the base portion 11 by, for example, a conventionally known film forming method, specifically plating, chemical vapor deposition (CVD), sputtering, vacuum deposition, ion deposition, or the like. This is because it can be formed by various techniques such as physical vapor deposition (PVD) such as plating, and by these techniques a thin and uniform layer can be formed relatively easily. In addition, a method of applying a liquid material containing metal by a roll coating method, a spray coating method, a curtain coating method, a method of printing the liquid material, a method of attaching a metal foil using an adhesive, etc. may be adopted. is also possible. The metal layer is preferably formed by a physical film-forming method such as sputtering among the above-mentioned methods. This is because a metal thin film (sputtering layer) formed by a sputtering method or the like has excellent adhesion to the base portion 11 even if it is thin. In addition, the sputtered layer has a smooth surface, and has no burrs, so there is no risk of contamination by foreign matter.

The thickness of the metal layer (for example, an aluminum layer) as the layered portion 12 of multiple layers is not limited and is arbitrary. be done. This is because if the metal layer is thicker than the base portion 11, the ratio of the metal material to the synthetic resin material is increased, which makes it difficult to reduce the cost and weight of the electromagnetic wave shielding cover 3. Moreover, it is difficult to impart desired physical strength to the entire electromagnetic wave shielding cover 3 .

The thickness of the metal layers (e.g., aluminum layers) may be, for example, 1.0 μm or less for each layer, preferably 0.2 μm or less, and in particular 0.1 μm or more and 0.15 μm or less. It's good. The reason for this is that the metal layer itself is extremely thin, although a higher electromagnetic shielding effect is imparted than when a single layer having the same thickness as the total thickness of the metal layers is formed on the front or back surface of the base. This is because the cost can be effectively reduced and the weight can be reduced. If the thickness of each layer exceeds 1.0 μm, it may be difficult to effectively reduce the cost and weight. Conversely, if the thickness of each layer is less than 0.1 μm, it may be difficult to impart a desired electromagnetic shielding effect, or the layered portion 12 may peel off when other members come into contact with the base portion 11 . is likely to be exposed. The thickness of the metal layer (for example, an aluminum layer) as the layered portion 12 of multiple layers may be the same for each layer, but may be different. good too.

When the layered portion 12 of multiple layers is made of an aluminum layer, it is preferable to configure the electromagnetic wave shielding cover 3 in combination with the base portion 11 made of an injection molded body made of PPS resin. This is because, as described above, the PPS resin has good compatibility with aluminum, so that the adhesion of the layered portion 12 to the base portion 11 can be improved.

The thickness of the layered portion 12 of multiple layers may be the same everywhere along the plane direction, or may be different depending on different places in the plane direction. In addition, the thickness of the layered portion 12 of multiple layers may be the same for each layer, but may be different.

Here, when the total thickness of the layered portion 12 of the plurality of layers is T, it is assumed that the electromagnetic wave shielding cover 3 of the present embodiment is used as a sample and the electric field shielding performance is measured using a predetermined evaluation jig. do. Similarly, it is assumed that samples having a common structure except that the layered portion 12 is a single layer and have a thickness of T are measured for electric field shielding performance using the evaluation jig in the same manner. At this time, the former (this embodiment) sample having multiple layered portions 12 has higher electric field shielding performance than the latter sample having a single-layered layered portion 12 .

When the above comparison is made by the KEC method (method of the Kansai Electronics Industry Development Center) for evaluating electromagnetic shielding materials using an electric field evaluation jig, the following can be specifically said. That is, the electric field shielding performance at 300 kHz to 1 GHz measured by the KEC method for the present embodiment was obtained by measuring samples having a common structure except that the layered portion 12 was a single layer and had a thickness of T by the same method. It is higher than the electric field shielding performance at 300 KHz to 1 GHz measured in the previous section. In this case, the electric field shielding performance at 300 kHz to 1 GHz measured by the KEC method is preferably 50 dB or more of the electric field shielding performance when the sample is not placed in the electric field evaluation jig, and is preferably 60 dB or more. is more preferable, and 70 dB or more is particularly preferable. If such a difference is provided, it can be said that the electromagnetic wave shielding cover 3 has a desired and sufficient electric field shielding performance in the above frequency range.

When the above comparison is made by the KEC method (method of the Kansai Electronics Industry Development Center) for evaluating electromagnetic shielding materials using a magnetic field evaluation jig, the following can be specifically said. That is, the magnetic field shielding performance at 300 kHz to 1 GHz measured by the KEC method for the present embodiment was obtained by measuring samples having a common structure except that the layered portion 12 was a single layer and had a thickness of T by the same method. It is higher than the magnetic field shielding performance at 300 KHz to 1 GHz measured in the previous section. In this case, the magnetic field shielding performance at 300 kHz to 1 GHz measured by the KEC method is preferably 20 dB or more of the magnetic field shielding performance when the sample is not placed in the magnetic field evaluation jig, and is preferably 30 dB or more. is more preferable, and 40 dB or more is particularly preferable. If such a difference is provided, it can be said that the electromagnetic wave shielding cover 3 has a desired and sufficient magnetic field shielding performance in the above frequency range.

When the above comparison is made by the coaxial tube method for evaluating the electromagnetic wave transmission attenuation of the electromagnetic wave shielding material, the following can be specifically said. That is, the shielding performance (electromagnetic wave transmission attenuation) at 1 GHz to 6 GHz measured by the above-described coaxial tube method for the present embodiment has the same structure except that the layered portion 12 is a single layer and has a thickness of T. It is higher than the shielding performance at 1 GHz to 6 GHz measured by the same method for the sample having the same. In this case, the shield performance (electromagnetic wave transmission attenuation) at 1 GHz to 6 GHz measured by the coaxial tube method is preferably 50 dB or more of the electric field shield performance when a blank is not placed on the evaluation jig, and is preferably 60 dB. It is more preferably 70 dB or more, and particularly preferably 70 dB or more. If such a difference is provided, it can be said that the electromagnetic wave shielding cover 3 has a desired and sufficient electromagnetic shielding performance in the above frequency range.

Examples that embody the present embodiment more concretely will be introduced below, but the present invention is not limited to the examples.

[Example 1] Comparative test 1 when the same kind of metal (aluminum) is used for the layered portion 12

In Example 1, several test pieces shown below were produced in order to conduct a comparative test of electric field shielding performance by the KEC method. Here, a plate material (150 mm square, 3.0 mm thick) made of commercially available PPS resin was used as the base portion 11 . Then, an aluminum layer as the layered portion 12 was formed by sputtering so as to entirely cover one or both surfaces of the base portion 11 .

In the graph of FIG. 3, "AL_0.1 μm_single side" means that a 0.1 μm aluminum layer (that is, a single layered portion 12) is formed on one side of the base portion 11. As shown in FIG.

“AL_0.1 μm_both sides” means that a 0.1 μm aluminum layer (that is, two layered portions 12) is formed on both surfaces of the base portion 11 made of PPS resin.

“AL — 0.2 μm — one side” means that a 0.2 μm aluminum layer (that is, a single layered portion 12) is formed on one side of the base portion 11 made of PPS resin.

“AL_0.2 μm_both sides” means that 0.2 μm aluminum layers (that is, two layers 12) are formed on both surfaces of the base portion 11 made of PPS resin.

"AL_0.5 μm_single side" means that a 0.5 μm aluminum layer (that is, a single layered portion 12) is formed on one side of the base portion 11 made of PPS resin.

“AL_0.5 μm_both sides” means that a 0.5 μm aluminum layer (that is, two layered portions 12) is formed on both surfaces of the base portion 11 made of PPS resin.

“AL — 1.0 μm — one side” means that a 1.0 μm aluminum layer (that is, a single layered portion 12) is formed on one side of the base portion 11 made of PPS resin.

“AL_1.0 μm_both sides” means that a 1.0 μm aluminum layer (that is, two layered portions 12) is formed on both surfaces of the base portion 11 made of PPS resin.

Also, "PPS" means that the aluminum layer is not formed on either side of the base portion 11 made of PPS resin.

"ADC 12" means that an aluminum die-cast plate material is used as the base portion 11 instead of PPS resin, and an aluminum layer is not formed.

"Blank" means that the measurement was performed without placing anything on the evaluation jig.

In the graph of FIG. 3, the horizontal axis indicates frequency (GHz), and the vertical axis indicates electric field shield performance (dB) measured by the KEC method using an electric field evaluation jig. The value of the electric field shielding performance (dB) is measured every 100 kHz in the range from 200 kHz to 1 GHz, the measured values are plotted on a graph, and the results are shown by connecting each point with a line segment.

As shown in FIG. 3, the "PPS" in which no aluminum layer is formed has almost the same measurement value as the "blank", and therefore, the electric field shielding performance cannot be exhibited only by the base portion 11 made of PPS resin. I found out.

For example, "AL_0.1 μm_both sides" can be grasped as a sample in which the total thickness of the two-layered layered portion 12 is T (that is, 0.1 μm+0.1 μm=0.2 μm). On the other hand, "AL_0.2 μm_single side" can be grasped as samples having a common structure except that the layered portion 12 is a single layer and the thickness is T (that is, 0.2 μm). Then, when the measured values of the electric field shielding performance at 300 kHz to 1 GHz measured by the KEC method were compared, the line segment indicating "AL_0.1 μm_both sides" in the graph was higher than the line segment indicating "AL_0.2 μm_single side". was also generally lower. Therefore, it was found that the "AL_0.1 μm_both side" sample gave better overall results than the "AL_0.2 μm_single side" sample. Incidentally, the electric field shielding performance of the "AL_0.1 μm_both sides" sample is about 50 dB to 60 dB better than that of the "blank" sample, and it can be said that it has the desired and sufficient electric field shielding performance in the above frequency range. It was something.

In addition, when the measured values of the electric field shielding performance at 300 kHz to 1 GHz were compared between the "AL_0.5 μm_double-sided" sample and the "AL_1.0 μm_single-sided" sample, the same results as above were obtained, that is, the "AL_0.5 μm_double-sided" The sample was found to perform better overall than the "AL_1.0 μm_single sided" sample. Incidentally, the electric field shielding performance of the "AL_0.5 μm_both sides" sample is about 50 dB to 70 dB better than that of the "blank" sample, and it can be said that it has the desired and sufficient electric field shielding performance in the above frequency range. It was something.

In addition, the measured value of the electric field shielding performance of the "AL_1.0 μm_double-sided" sample at 300 kHz to 1 GHz was even better than the measured value of "AL_0.5 μm_double-sided". Specifically, the measured value was about 80 dB to 90 dB better than that of "blank", which was extremely low value comparable to "ADC12", so it was found that good results were obtained.

[Example 2] Comparative test 2 in the case of using the same kind of metal (aluminum) for the layered portion 12
In Example 2, using the same test piece as in Example 1, a comparative test of magnetic field shielding performance was conducted by the KEC method. In the graph of FIG. 4, the horizontal axis indicates frequency (GHz), and the vertical axis indicates magnetic field shield performance (dB) measured by the KEC method using a magnetic field evaluation jig. The value of the magnetic field shield performance (dB) is measured every 100 kHz in the range from 200 kHz to 1 GHz, the measured values are plotted on a graph, and the results are shown by connecting each point with a line segment.

As shown in FIG. 4, "PPS" in which no aluminum layer is formed has almost the same measurement value as "blank". I found out.

A comparison of the magnetic field shielding performance values from 300 kHz to 1 GHz measured by the KEC method between the sample of "AL_0.1 μm_both sides" and the sample of "AL_0.2 μm_single side" shows "AL_0.1 μm_both sides" in the graph. The line segment was located entirely below the line segment indicating "AL_0.2 μm_one side". Therefore, it was found that the "AL_0.1 μm_both side" sample gave better overall results than the "AL_0.2 μm_single side" sample. Incidentally, the magnetic field shielding performance of the sample of "AL_0.1μm_both sides" is about 30 dB to 50 dB better than that of the "blank" sample, and it can be said that it has the desired and sufficient magnetic shielding performance in the above frequency range. It was something.

In addition, when the measured values of the magnetic shielding performance at 300 kHz to 1 GHz were compared between the "AL_0.5 μm_double-sided" sample and the "AL_1.0 μm_single-sided" sample, the same results as above were obtained, that is, the "AL_0.5 μm_double-sided" The sample was found to perform better overall than the "AL_1.0 μm_single sided" sample. By the way, the magnetic shielding performance of the "AL_0.5μm_both sides" sample is about 60 dB to 80 dB better than that of the "blank" sample, and it can be said that it has the desired and sufficient magnetic shielding performance in the above frequency range. It was something. Incidentally, the measured value of the "AL_0.5 μm_both sides" sample was extremely low, comparable to "ADC12". Similarly, it was found that the "AL_1.0 μm_both sides" sample also gave good results comparable to "ADC12".

[Example 3] Comparative test 3 in the case of using the same kind of metal (aluminum) for the layered portion 12
In Example 3, a test piece (30 mm square, 1.0 mm thick) made of the same resin as in Example 1 was used, and a comparison test of electromagnetic shielding performance was performed by the coaxial tube method. In the graph of FIG. 5, the horizontal axis indicates frequency (GHz), and the vertical axis indicates electromagnetic shielding performance (dB) measured by the coaxial tube method using a dedicated evaluation jig. The value of the electromagnetic shielding performance (dB) is measured every 0.5 GkHz in the range from 1 GHz to 6 GHz, the measured values are plotted on a graph, and the results are shown by connecting each point with a line segment.

As shown in FIG. 5, "PPS" in which no aluminum layer is formed has almost the same measurement value as "blank", and therefore, the base portion 11 made of PPS resin alone does not exhibit electromagnetic shielding performance. I found out.

When comparing the measured values of the electromagnetic shielding performance at 1 GHz to 6 GHz measured by the coaxial tube method for the sample of "AL_0.1 μm_both sides" and the sample of "AL_0.2 μm_single side", "AL_0.1 μm_both sides" in the graph was compared. The line segment indicating "AL_0.2 μm_single side" was located entirely below the line segment indicating "AL_0.2 μm_single side". Therefore, it was found that the "AL_0.1 μm_both side" sample gave better overall results than the "AL_0.2 μm_single side" sample. By the way, the electromagnetic shielding performance of the "AL_0.1μm_both sides" sample is about 70 dB to 80 dB better than that of the "blank" sample, and it can be said that it has the desired and sufficient electromagnetic shielding performance in the above frequency range. It was something.

In addition, when the measured values of the electromagnetic shielding performance at 1 GHz to 6 GHz were compared between the "AL_0.5 μm_double-sided" sample and the "AL_1.0 μm_single-sided" sample, the same results as above were obtained. The sample was found to perform better overall than the "AL_1.0 μm_single sided" sample. By the way, the electromagnetic shielding performance of the "AL_0.5μm_both sides" sample is about 90 dB to 110 dB better than that of the "blank" sample, and it can be said that it has the desired and sufficient electromagnetic shielding performance in the above frequency range. It was something. Incidentally, the measured value of the "AL_0.5 μm_both sides" sample was extremely low, comparable to "ADC12". Similarly, it was found that the "AL_1.0 μm_both sides" sample also gave good results comparable to "ADC12".

[Example 4] Comparative test 4 in the case of using the same kind of metal (stainless alloy) for the layered portion 12
In Test Example 4, a comparison was made basically based on Example 1 above, except that a stainless alloy layer (SUS310) was formed as the layered portion 12 instead of the aluminum layer.

In the graph of FIG. 6, "SUS310_0.1 μm_single side" means that a 0.1 μm stainless steel alloy layer (that is, a single layered portion 12) is formed on one side of the base portion 11. FIG.

"SUS310_0.1 μm_both sides" means that a 0.1 μm stainless steel alloy layer (that is, two layered portions 12) is formed on both surfaces of the base portion 11 made of PPS resin.

"SUS310_0.2 μm_one side" means that a 0.2 μm stainless steel alloy layer (that is, a single layered portion 12) is formed on one side of the base portion 11 made of PPS resin.

"SUS310_0.2 μm_both sides" means that a 0.2 μm stainless steel alloy layer (that is, two layered portions 12) is formed on both surfaces of the base portion 11 made of PPS resin.

"SUS310_0.5 μm_one side" means that a 0.5 μm stainless steel alloy layer (that is, a single layered portion 12) is formed on one side of the base portion 11 made of PPS resin.

"SUS310_0.5 μm_both sides" means that a 0.5 μm stainless steel alloy layer (that is, two layered portions 12) is formed on both surfaces of the base portion 11 made of PPS resin.

“SUS310 — 1.0 μm — one side” means that a 1.0 μm stainless steel alloy layer (that is, a single layered portion 12) is formed on one side of the base portion 11 made of PPS resin.

"SUS310_1.0 μm_both sides" means that a 1.0 μm stainless steel alloy layer (that is, two layered portions 12) is formed on both surfaces of the base portion 11 made of PPS resin.

Further, "PPS" means that the stainless alloy layer is not formed on either surface of the base portion 11 made of PPS resin.

"ADC12" means that an aluminum die-cast plate material is used as the base portion 11 instead of PPS resin, and a stainless alloy layer is not formed.

"Blank" means that the measurement was performed without placing anything on the evaluation jig.

In the graph of FIG. 6, the horizontal axis indicates frequency (GHz), and the vertical axis indicates electric field shield performance (dB) measured by the KEC method using an electric field evaluation jig. The value of the electric field shielding performance (dB) is measured every 100 kHz in the range from 200 kHz to 1 GHz, the measured values are plotted on a graph, and the results are shown by connecting each point with a line segment.

As shown in FIG. 6, the "PPS" in which no stainless alloy layer is formed has almost the same measurement value as the "blank", and therefore, the electric field shielding performance cannot be exhibited only by the base portion 11 made of PPS resin. I understood it.

For example, "SUS310_0.1 μm_both sides" can be grasped as a sample in which the total thickness of the two-layered layered portion 12 is T (that is, 0.1 μm+0.1 μm=0.2 μm). On the other hand, "SUS310_0.2 μm_single side" can be understood to be a sample having a common structure except that the layered portion 12 is a single layer and the thickness is T (that is, 0.2 μm). When comparing the electric field shielding performance values of these measured by the KEC method at 300 kHz to 1 GHz, the line segment indicating "SUS310_0.1 μm_both sides" in the graph is higher than the line segment indicating "SUS310_0.2 μm_single side". was also slightly lower. Therefore, it was found that the sample of "SUS310_0.1 μm_both sides" gave better results overall than the sample of "SUS310_0.2 μm_single side". Incidentally, the electric field shielding performance of the "SUS310_0.1 μm_both sides" sample was about 20 dB to 40 dB better than that of the "blank" sample.

In addition, when the measured values of the electric field shielding performance at 300 kHz to 1 GHz were compared between the "SUS310_0.5 μm_double-sided" sample and the "SUS310_1.0 μm_single-sided" sample, the same results as above were obtained, that is, the "AL_0.5 μm_double-sided" It was found that the sample gave better results overall than the "SUS310_1.0 μm_single-sided" sample. By the way, the electric field shield performance of the "SUS310_0.5 μm_both sides" sample is about 40 dB to 50 dB better than that of the "blank" sample, and it can be said that it has the desired and sufficient electric field shield performance in the above frequency range. It was something.

In addition, the measured value of the electric field shielding performance of the sample of "SUS310_1.0 μm_both sides" at 300 kHz to 1 GHz was even better than the measured value of "SUS310_0.5 μm_both sides". Specifically, the measured value is about 50 dB to 80 dB better than the "blank" value, and it can be said that the desired and sufficient electric field shielding performance is provided in the above frequency range.

[Example 5] Comparative test 5 in the case of using the same kind of metal (stainless alloy) for the layered portion 12
In Example 5, using the same test piece as in Example 4, a comparative test of magnetic field shielding performance was conducted by the KEC method. In the graph of FIG. 7, the horizontal axis indicates frequency (GHz), and the vertical axis indicates magnetic field shielding performance (dB) measured by the KEC method using a magnetic field evaluation jig. The value of the magnetic field shield performance (dB) is measured every 100 kHz in the range from 200 kHz to 1 GHz, the measured values are plotted on a graph, and the results are shown by connecting each point with a line segment.

As shown in FIG. 7, "PPS" in which no stainless alloy layer is formed has almost the same measurement value as "blank", and therefore, the magnetic field shielding performance cannot be exhibited only by the base portion 11 made of PPS resin. I understood it.

When comparing the measured values of the magnetic field shielding performance at 300 kHz to 1 GHz measured by the KEC method between the "SUS310_0.5 μm_double-sided" sample and the "SUS310_1.0 μm_single-sided" sample, the graph shows "SUS310_0.5 μm_double-sided". The line segment was located entirely below the line segment indicating "SUS310_1.0 μm_single side". Therefore, it was found that the sample of "SUS310_0.5 μm_both sides" is overall better than the sample of "SUS310_1.0 μm_single side". By the way, the magnetic shielding performance of the "SUS310_0.5μm_both sides" sample is about 20 dB to 40 dB better than that of the "blank" sample, and it can be said that it has the desired and sufficient magnetic shielding performance in the above frequency range. It was something. However, when the sample of "SUS310_0.1 μm_both sides" and the sample of "SUS310_0.2 μm_single side" were compared, the above relationship was not observed. Therefore, when a stainless alloy layer is selected as the layered portion 12, it is necessary to set at least the thickness of each stainless alloy layer slightly thicker (for example, 0.5 μm or more) in order to obtain the desired magnetic field shielding performance. thought to be one.

[Example 6] Comparative test 6 in the case of using the same kind of metal (stainless alloy) for the layered portion 12
In Example 6, a test piece (30 mm square, 1.0 mm thick) made of the same resin as in Example 4 was used, and a comparison test of electromagnetic shielding performance was conducted by the coaxial tube method. In the graph of FIG. 8, the horizontal axis indicates frequency (GHz), and the vertical axis indicates electromagnetic shielding performance (dB) measured by the coaxial tube method using a dedicated evaluation jig. The value of the shielding performance (dB) is measured every 0.5 GkHz in the range from 1 GHz to 6 GHz, the measured values are plotted on a graph, and the results are shown by connecting each point with a line segment.

As shown in FIG. 8, the "PPS" in which the stainless alloy is not formed has almost the same measurement value as the "blank", and therefore, the base portion 11 made of PPS resin alone does not exhibit the electromagnetic shielding performance. I found out.

When comparing the measured values of the electromagnetic shielding performance at 1 GHz to 6 GHz measured by the coaxial tube method for the "SUS310_0.1 μm_double-sided" sample and the "SUS310_0.2 μm_single-sided" sample, "SUS310_0.1 μm_double-sided" in the graph was compared. The line segment indicating "SUS310_0.2 μm_single side" was located entirely below the line segment indicating "SUS310_0.2 μm_single side". Therefore, it was found that the sample of "SUS310_0.1 μm_both sides" gave better results overall than the sample of "SUS310_0.2 μm_single side". By the way, the electromagnetic shield performance of the "SUS310_0.1 μm_both sides" sample is about 40 dB to 50 dB better than that of the "blank" sample, and it can be said that it has the desired and sufficient electromagnetic shield performance in the above frequency range. It was something.

In addition, when the measured values of the electromagnetic shielding performance at 1 GHz to 6 GHz were compared between the "SUS310_0.5 μm_double-sided" sample and the "SUS310_1.0 μm_single-sided" sample, the same results as above were obtained. It was found that the sample gave better results overall than the "SUS310_1.0 μm_single-sided" sample. By the way, the electromagnetic shielding performance of the "SUS310_0.5μm_both sides" sample is about 50 dB to 80 dB better than that of the "blank" sample, and it can be said that it has the desired and sufficient electromagnetic shielding performance in the above frequency range. It was something. It was found that the sample of "SUS310_1.0 μm_both sides" gave more favorable results.

[Example 7] Comparative test 1 when different metals are used for the layered portion 12

In Example 7, several test pieces shown below were produced in order to conduct a comparative test of electric field shielding performance by the KEC method. Here, a plate material (150 mm square, 3.0 mm thick) made of commercially available PPS resin was used as the base portion 11 . Then, a stainless alloy layer and a copper layer were respectively formed by sputtering as the layered portion 12 so as to cover the whole of one or both surfaces of the base portion 11 .

In the graph of FIG. 9, “SUS_0.5μ_Cu_0.5μ_layer” means that a 0.5 μm stainless steel alloy layer is formed on one surface of the base portion 11 and a 0.5 μm copper layer is formed on the other surface. means that the is formed. Although it has two layered portions 12 made of dissimilar metals, the base portion 11 is interposed between the two layered portions 12, which are spaced apart from each other.

"SUS_0.5μ_Cu_0.5μ_Lamination" means that a 0.5μm stainless steel alloy layer is formed on one side surface of the base portion 11, and a 0.5μm copper layer is laminated on the same side surface. It means something formed in a state. In this regard, the base portion 11 is not interposed between the two layered portions 12, and the two are arranged in contact with each other. Therefore, it is in a state that can be regarded as a single-layer layered portion 12 .

Further, "PPS" means that neither a stainless alloy layer nor a copper layer is formed on either side of the base portion 11 made of PPS resin.

"ADC12" means that an aluminum die-cast plate material is used as the base portion 11 instead of PPS resin, and that a stainless alloy layer and a copper layer are not formed. .

"Blank" means that the measurement was performed without placing anything on the evaluation jig.

In the graph of FIG. 9, the horizontal axis indicates the frequency (GHz), and the vertical axis indicates the electric field shield performance (dB) measured by the KEC method using the electric field evaluation jig. The value of the electric field shielding performance (dB) is measured every 100 kHz in the range from 200 kHz to 1 GHz, the measured values are plotted on a graph, and the results are shown by connecting each point with a line segment.

Here, it can be understood that "SUS_0.5μ_Cu_0.5μ_layer" is a sample in which the total thickness of the two layered portions 12 is T (that is, 0.5 μm+0.5 μm=1.0 μm). On the other hand, for the sample with "SUS_0.5μ_Cu_0.5μ_laminated", the stainless steel alloy layer and the copper layer are arranged in contact with each other. It can be regarded as a sample with a common structure. When comparing the electric field shielding performance values of these measured by the KEC method at 300 kHz to 1 GHz, the line segment indicating "SUS_0.5μ_Cu_0.5μ_ layer" in the graph indicates "SUS_0.5μ_Cu_0.5μ_laminate". It was located below the indicated line segment. Therefore, it was found that the sample of "SUS_0.5μ_Cu_0.5μ_layer" gave better results overall than the sample of "SUS_0.5μ_Cu_0.5μ_laminate". By the way, the electric field shielding performance of the sample of "SUS_0.5μ_Cu_0.5μ_ layer" is about 70 dB to 80 dB better than that of "blank", and although it is not as good as the electric field shielding performance of "ADC12", it is equivalent to it. was becoming

[Embodiment 8] Comparative test 2 in the case of using a dissimilar metal for the layered portion 12
In Example 8, using the same test piece as in Example 7, a comparative test of magnetic field shielding performance was conducted by the KEC method. In the graph of FIG. 10, the horizontal axis indicates frequency (GHz), and the vertical axis indicates magnetic field shielding performance (dB) measured by the KEC method using a magnetic field evaluation jig. The value of the magnetic field shield performance (dB) is measured every 100 kHz in the range from 200 kHz to 1 GHz, the measured values are plotted on a graph, and the results are shown by connecting each point with a line segment.

A sample of "SUS_0.5μ_Cu_0.5μ_layer" and a sample of "SUS_0.5μ_Cu_0.5μ_laminate" were compared in terms of the magnetic field shield performance measured by the KEC method at 300 kHz to 1 GHz. The line segment indicating "5μ_Cu_0.5μ_layer" was located below the line segment indicating "SUS_0.5μ_Cu_0.5μ_laminate". Therefore, it was found that the sample of "SUS_0.5μ_Cu_0.5μ_layer" gave better results overall than the sample of "SUS_0.5μ_Cu_0.5μ_laminate". By the way, the magnetic shielding performance of the sample of "SUS_0.5μ_Cu_0.5μ_ layer" is about 50dB to 60dB better than that of "blank", and although it does not reach the magnetic shielding performance of "ADC12", it is equivalent to it. was becoming

[Example 9] Comparative test 3 when a dissimilar metal is used for the layered portion 12
In Example 9, a test piece (30 mm square, 1.0 mm thick) made of the same resin as in Example 7 was used, and a comparison test of electromagnetic shielding performance was conducted by the coaxial tube method. In the graph of FIG. 11, the horizontal axis indicates frequency (GHz), and the vertical axis indicates electromagnetic shielding performance (dB) measured by the coaxial tube method using a dedicated evaluation jig. The value of the electromagnetic shielding performance (dB) is measured every 0.5 GkHz in the range from 1 GHz to 6 GHz, the measured values are plotted on a graph, and the results are shown by connecting each point with a line segment.

When comparing the measured values of the electromagnetic shielding performance at 1 GHz to 6 GHz measured by the coaxial tube method for the sample of "SUS_0.5μ_Cu_0.5μ_layer" and the sample of "SUS_0.5μ_Cu_0.5μ_laminate", the graph shows "SUS_0 The line segment indicating ".5μ_Cu_0.5μ_layer" was positioned lower than the line segment indicating "SUS_0.5μ_Cu_0.5μ_layer". Therefore, it was found that the sample of "SUS_0.5μ_Cu_0.5μ_layer" gave better results overall than the sample of "SUS_0.5μ_Cu_0.5μ_laminate". By the way, the electromagnetic shielding performance of the sample of "SUS_0.5μ_Cu_0.5μ_ layer" is about 90 dB to 110 dB better than that of "blank", and is comparable to the electromagnetic shielding performance of "ADC12".

[Conclusion]

Therefore, according to this embodiment, the following effects can be obtained.

(1) The electromagnetic wave shielding cover 3 of the present embodiment includes a base portion 11 and a plurality of layered portions 12, and is characterized in that the plurality of layered portions 12 are spaced apart from each other in the stacking direction. do. With such an arrangement, it is possible to impart a higher shielding performance (shielding performance in the plane direction) than when the layered portion 12 is a single layer, and effectively shield electromagnetic waves. Therefore, it is possible to provide desired electromagnetic shielding performance while suppressing the thickness of the layered portion 12 .

(2) In the present embodiment, when the total thickness of the layered portion 12 of the plurality of layers is T, the shielding performance measured using the evaluation jig is that the layered portion 12 is a single layer and has a thickness of T. The shielding performance is higher than that measured by the same method for samples having a common structure except for the above. Therefore, although the shielding performance is higher than when the layered portion is a single layer, the total thickness of the multiple layered portions can be reduced, and the cost and weight can be reduced.

(3) In the present embodiment, by covering the front surface 11a and the back surface 11b of the base portion 11 with the multiple layers of the layered portion 12, good shielding performance can be obtained regardless of the direction of electromagnetic waves. In addition, since the multiple layers of the layered portion 12 are formed not on the inner layer but on the surface layer of the base portion 11, the layered portion 12 can be formed relatively easily, and the separation distance between the two can be easily secured.

(4) In the present embodiment, since the base portion 11 is an injection-molded body made of a thermoplastic resin, the base portion 11 can be excellent in moldability, cost, lightness, workability, insulation, and the like. The electromagnetic wave shielding cover 3 can be applied to various uses.

(6) This embodiment is characterized in that the layered portion 12 of multiple layers is a sputtered layer. The sputtered layer has the advantage of having a smooth surface and of easily ensuring the adhesion of the layered portion 12 . In addition, since no burrs are generated, there is no risk of contamination by foreign matter. Therefore, even when the thickness is reduced, high shielding performance can be imparted.

(7) In the present embodiment, the base portion 11 is an injection-molded body made of PPS resin, and the layered portion 12 of multiple layers is made of aluminum. Since aluminum is a relatively inexpensive metal, it contributes to cost reduction, and since it is relatively lightweight, it also contributes to overall weight reduction. In addition, PPS resin is a general-purpose product that is relatively inexpensive, and has good compatibility with many metal materials such as aluminum, so that the adhesion of the layered portion 12 can be improved. In particular, in the present embodiment, the thickness of the aluminum layer, which is the layered portion 12 of multiple layers, can be 0.2 μm or less. In this case, since the layered portion is extremely thin, it is possible to effectively reduce the cost and weight.

Next, in addition to the technical ideas described in the claims, technical ideas grasped by each of the above-described embodiments are listed below.

(1) In any one of claims 1 to 8, the layered portion of multiple layers is thinner than the base portion.
(2) In any one of claims 1 to 8, the base portion is an insulator.
(3) In any one of claims 1 to 8, the base portion is made of PPS resin containing inorganic fibers.
(4) In any one of Claims 1 to 8, the thickness of each layer of the multiple layers of the layered portion is equal.
(5) In any one of claims 1 to 8, the thickness of each layer of the layered portion of the plurality of layers is different.
(6) In any one of claims 1 to 8, the plurality of layered portions are made of the same kind of metal material.
(7) In any one of claims 1 to 8, the layered portions of the plurality of layers are made of different kinds of metal materials.
(8) In any one of claims 1 to 8, the electromagnetic wave shield is exposed to electromagnetic waves of 1 GHz or higher.
(9) In any one of claims 1 to 8, the layered portion of the plurality of layers is made of a material having a higher electrical conductivity than the material forming the base portion.
(10) In any one of claims 1 to 8, the layered portion of the plurality of layers is made of a material having a higher magnetic permeability than the material forming the base portion.
(11) In any one of claims 1 to 8, when the total thickness of the layered portion of the plurality of layers is T, the KEC method for evaluating the electromagnetic shielding material using an electric field evaluation jig The electric field shielding performance at 300 kHz to 1 GHz measured by the above is compared to the electric field shielding performance at 300 kHz to 1 GHz measured by the same method for samples having a common structure except that the layered portion is a single layer and the thickness is T. and expensive.
(12) In the above idea 11, the electric field shielding performance at 300 kHz to 1 GHz measured by the KEC method for evaluating the electromagnetic shielding material using the electric field evaluation jig does not place the sample on the electric field evaluation jig. 60 dB or more of the electric field shielding performance when blank.
(13) In any one of claims 1 to 8, when the total thickness of the layered portion of the plurality of layers is T, the KEC method for evaluating the electromagnetic shielding material using a magnetic field evaluation jig Compared to the magnetic shielding performance at 300 kHz to 1 GHz measured by the same method for samples having a common structure except that the layered portion is a single layer and the thickness is T and expensive.
(14) In the above idea 13, the magnetic field shielding performance at 300 kHz to 1 GHz measured by the KEC method for evaluating the electromagnetic shielding material using the magnetic field evaluation jig does not place the sample on the magnetic field evaluation jig. 30 dB or more of magnetic field shielding performance when blank.
(15) In any one of claims 1 to 8, when the total thickness of the layered portions of the plurality of layers is T, the electromagnetic wave transmission attenuation of the electromagnetic wave shielding material is evaluated using an evaluation jig. The shielding performance (electromagnetic wave transmission attenuation) at 1 GHz to 6 GHz measured by the coaxial tube method was measured by the same method for samples having a common structure except that the layered portion was a single layer and the thickness was T. High compared to shielding performance at 1 GHz to 6 GHz.
(16) In the above idea 15, the electromagnetic shielding performance (electromagnetic wave transmission attenuation) at 1 GHz to 6 GHz measured by the coaxial tube method that evaluates the electromagnetic wave transmission attenuation of the electromagnetic shielding material using an evaluation jig is the above evaluation. 60 dB or more of the electromagnetic shielding performance when the jig is blank with no sample placed on it.

DESCRIPTION OF SYMBOLS 1... Electronic equipment housing for mounting in a vehicle 3... Electromagnetic wave shielding cover as an electromagnetic wave shielding body 11... Base part 11a... Front surface 11b... Back surface 12... Layered part T... Total thickness of a plurality of layered parts

Claims (3)

An electromagnetic wave shield exposed to electromagnetic waves of 1 GHz or higher ,
a base portion which is an injection-molded PPS resin body having a thickness of 1.0 mm or more and having a front surface and a back surface;
It is made of a material having conductivity different from that of the material forming the base portion, is formed along the surface direction of the base portion, and covers the front surface and the back surface on the front surface and the back surface of the base portion. A plurality of layered portions arranged with a thickness of 1.0 mm or more apart from each other in the stacking direction by being formed ,
The layered portions of the plurality of layers are all aluminum layers formed by sputtering, and each has an equal thickness of 0.1 μm or more and 1.0 μm or less,
Shield performance at 1 GHz to 6 GHz measured by the coaxial tube method for evaluating the electromagnetic wave transmission attenuation amount of the electromagnetic wave shielding material using an evaluation jig, where T is the total thickness of the layered portion of the plurality of layers. The electromagnetic wave transmission attenuation amount is high compared to the shielding performance at 1 GHz to 6 GHz measured by the same method for samples having a common structure except that the layered portion is a single layer and the thickness is T, and the evaluation It is 60 dB or more of the electromagnetic shielding performance when the jig is blank without a sample placed on it.
An electromagnetic wave shield characterized by: An electromagnetic wave shield exposed to electromagnetic waves of 1 GHz or higher,
a base portion which is an injection-molded PPS resin body having a thickness of 1.0 mm or more and having a front surface and a back surface;
It is made of a material having conductivity different from that of the material forming the base portion, is formed along the surface direction of the base portion, and covers the front surface and the back surface on the front surface and the back surface of the base portion. A plurality of layered parts arranged with a thickness of 1.0 mm or more apart from each other in the lamination direction by being formed
and
The layered portion of the plurality of layers includes a first stainless alloy layer of 0.2 μm or more and 1.0 μm or less formed by sputtering and a second stainless alloy layer of 0.2 μm or more and 1.0 μm or less formed by sputtering. or a copper layer of 0.5 μm, and the second stainless alloy layer or the copper layer has the same thickness as the first stainless alloy layer,
Shield performance at 1 GHz to 6 GHz measured by the coaxial tube method for evaluating the electromagnetic wave transmission attenuation amount of the electromagnetic wave shielding material using an evaluation jig, where T is the total thickness of the layered portion of the plurality of layers. The electromagnetic wave transmission attenuation amount is high compared to the shielding performance at 1 GHz to 6 GHz measured by the same method for samples having a common structure except that the layered portion is a single layer and the thickness is T, and the evaluation 50 dB or more of the electromagnetic shielding performance when the jig is blank with no sample placed on it
An electromagnetic wave shield characterized by: 3. The electromagnetic wave shield according to claim 1 , which forms a part of an electronic device housing for mounting on a vehicle.

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