Electromagnetic wave shielding material, coating material or exterior material, and electrical and electronic equipment

Abstract

Provided is an electromagnetic wave shielding material which has favorable shielding properties in a low-frequency range. The electromagnetic wave shielding material has a structure in which a ferromagnetic layer and a non-magnetic conductive metal layer are laminated, and further has, on at least one surface of the non-magnetic conductive metal layer, a treatment film which contains an alloy containing copper and nickel.

Description

Technical Field

[0001] The present invention relates to an electromagnetic wave shielding material, a coating material or an exterior material, and an electric / electronic device.

Background Art

[0002] In environment-friendly vehicles equipped with secondary batteries such as electric vehicles and hybrid vehicles, the DC current generated from the mounted secondary battery is converted into an AC current via an inverter, and then the necessary power is supplied to an AC motor to obtain a driving force. Many of them adopt this method, and electromagnetic waves are generated due to the switching operation of the inverter or the like.

[0003] Moreover, electromagnetic waves are radiated from many electric / electronic devices including communication devices, displays, and medical devices, not limited to automobiles. Electromagnetic waves may cause malfunction of precision devices, and furthermore, there are concerns about their effects on the human body.

[0004] Typically, in the high-frequency region (1 MHz or more), it is known that a conductive layer such as copper exhibits good shielding characteristics against electromagnetic waves. However, in the low-frequency region (less than 1 MHz), the shielding characteristics against electromagnetic waves are low only with a conductive layer such as copper, so an electromagnetic wave shielding material formed by alternately laminating a magnetic layer having excellent magnetic permeability and a conductive layer is known to exhibit good shielding characteristics against magnetic waves.

[0005] For example, the following technique is proposed in Patent Document 1. "A noise suppression sheet used for suppressing noise of 1 MHz or less, comprising an n-layer magnetic layer having a magnetic layer (A1) and a magnetic layer (A n ) and a noise suppression layer having at least (n - 1) conductive layers, wherein the magnetic layer and the conductive layer are alternately laminated, each of the magnetic layers satisfies X represented by the following formula (1) i is 1 or more, the sum of X of each of the magnetic layers i is 4 or more and 15 or less, Each of the conductive layers is a noise suppression sheet characterized in that, in the magnetic field shielding property measurement by the KEC method, the proportionality constant obtained when linearly approximating the shielding property in the range of 0.2 to 1 MHz is 4 or more. X i =√μ´ i ×√t i ···Equation (1) Here, n is an integer of 2 or more, i is an integer from 1 to n, and μ´ i is the relative permeability at 1 MHz of the magnetic layer (A i ), and t i is the film thickness [mm] of the magnetic layer (A i ). 」

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Regarding the noise suppression sheet described in Patent Document 1, high shielding performance is shown in the low frequency region. However, depending on the product field, high shielding performance may be required in the region around 100 kHz. On the other hand, regarding the noise suppression sheet described in Patent Document 1, although the shielding performance at 300 kHz is mentioned (see

[0110] and

[0111] of Patent Document 1), the shielding performance in a lower low frequency region is not mentioned. Therefore, it is unclear whether the shielding performance of the noise suppression sheet described in Patent Document 1 is sufficient in the low frequency region below 300 kHz, and there is still room for improvement in the technology of Patent Document 1.

[0008] Therefore, in one embodiment of the present invention, an object is to provide an electromagnetic wave shielding material having good shielding characteristics in the low frequency region.

Means for Solving the Problems

[0009] That is, in one aspect, the present invention is an electromagnetic wave shielding material having a structure in which a ferromagnetic layer and a nonmagnetic conductive metal layer are laminated, and further has a treatment film containing an alloy containing copper and nickel on at least one surface of the nonmagnetic conductive metal layer.

[0010] In one embodiment of the electromagnetic wave shielding material according to the present invention, the ferromagnetic layer is laminated via at least two nonmagnetic conductive metal layers.

[0011] In one embodiment of the electromagnetic wave shielding material according to the present invention, at least one outermost layer is a nonmagnetic conductive metal layer.

[0012] In one embodiment of the electromagnetic wave shielding material according to the present invention, the alloy contained in the treatment film further contains cobalt.

[0013] In one embodiment of the electromagnetic wave shielding material according to the present invention, when the mass ratio of nickel in each treatment film is set to 1, the mass ratio of cobalt in each treatment film is 1.50 to 4.50.

[0014] Also, in another aspect, the present invention is a coating material or an exterior material for electric and electronic devices provided with any of the above electromagnetic wave shielding materials.

[0015] Furthermore, in another aspect, the present invention is an electric and electronic device provided with the above coating material or exterior material.

Effects of the Invention

[0016] According to one embodiment of the present invention, it is possible to provide an electromagnetic wave shielding material having good shielding characteristics in the low frequency region.

Modes for Carrying Out the Invention

[0017] Hereinafter, the present invention is not limited to each embodiment, and components can be modified and embodied without departing from the gist thereof. Further, various inventions can be formed by appropriately combining a plurality of components disclosed in each embodiment.

[0018] [Electromagnetic shielding material] In one embodiment of the electromagnetic shielding material according to the present invention, it has a structure in which a ferromagnetic layer and a non-magnetic conductive metal layer are laminated. Among them, in one embodiment, from the viewpoint of shielding characteristics, it is preferable that the ferromagnetic layer is laminated via at least two non-magnetic conductive metal layers. Further, from the viewpoint of shielding characteristics, at least one of the outermost layers (the uppermost layer and / or the lowermost layer) of the electromagnetic shielding material is preferably a non-magnetic conductive metal layer, and it is more preferable that both of the outermost layers are non-magnetic conductive metal layers. And, on at least one surface of the non-magnetic conductive metal layer, it further has a treatment film of an alloy containing copper and nickel, but it is preferable that the treatment film is further provided on any of the surfaces of the non-magnetic conductive metal layer. At this time, from the viewpoint of efficiently causing electromagnetic wave absorption / attenuation in the ferromagnetic layer, the treatment film is preferably disposed via the ferromagnetic layer and the non-magnetic conductive metal layer. Further, from the viewpoint of shielding characteristics, it is preferable that at least one of the outermost films (the uppermost film and / or the lowermost film) of the electromagnetic shielding material is a treatment film formed on the non-magnetic conductive metal layer. Note that the treatment film disposed via the ferromagnetic layer and the non-magnetic conductive metal layer includes not only the mode formed on at least one surface of the non-magnetic conductive metal layer, but also the mode formed on the surface of the ferromagnetic layer adjacent to the non-magnetic conductive metal layer on the non-magnetic conductive metal layer side. Due to these configurations, the electromagnetic wave shielding material exhibits good shielding characteristics in the low-frequency range. Although the present invention is not intended to be limited by theory, this is considered to be due to the following reasons. When an electromagnetic wave irradiates the non-magnetic conductive metal layer, part of it passes through, while part of it is reflected. As an example, if a ferromagnetic layer is sandwiched between two non-magnetic conductive metal layers, the electromagnetic wave (multiple reflection) repeatedly reflected between the non-magnetic conductive metal layers is absorbed by the magnetic material, and a better shielding effect can be obtained compared to a single non-magnetic conductive metal layer or a single ferromagnetic material. In particular, by forming a treatment film containing an alloy containing Cu-Ni by subjecting at least one surface of the non-magnetic conductive metal layer to roughening plating treatment, it is possible to efficiently cause electromagnetic wave absorption and attenuation in the ferromagnetic layer by causing diffuse reflection instead of specular reflection that occurs in a non-magnetic conductive metal layer having a metallic luster.

[0019] <ferromagnetic layer> The ferromagnetic layer contains a material with a high magnetic permeability. Examples include a composite sheet in which a resin is mixed and dispersed, a metal foil, and a laminate having a high magnetic permeability while laminating a resin sheet on at least one surface of the metal foil. The relative magnetic permeability of the ferromagnetic layer is generally 10 to 100,000. Note that the relative magnetic permeability can be measured using a commercially available magnetic permeability measuring device.

[0020] Examples of the resin include natural resins and synthetic resins, and synthetic resins are preferred from the viewpoint of processability. It is also possible to mix fiber reinforcing materials such as carbon fiber, glass fiber, and aramid fiber into these materials. As synthetic resins, from the viewpoints of availability and processability, polyesters such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), and PBT (polybutylene terephthalate), olefin resins such as polyethylene and polypropylene, polyamides, polyimides, liquid crystal polymers, polyacetals, fluororesins, polyurethanes, acrylic resins, epoxy resins, silicone resins, phenolic resins, melamine resins, ABS resins, polyvinyl alcohol, urea resins, polyvinyl chloride, PC (polycarbonate), polystyrene, styrene-butadiene rubber, etc. can be mentioned. Among these, PET, PEN, polyamides, and polyimides are preferred due to processability and cost reasons. The synthetic resin can also be an elastomer such as urethane rubber, chloroprene rubber, silicone rubber, fluororubber, styrene-based, olefin-based, vinyl chloride-based, urethane-based, amide-based, etc. Furthermore, the synthetic resin itself may play the role of an adhesive. In this case, it has a structure in which a non-magnetic conductive metal layer with a treatment film formed on its surface is laminated via an adhesive. There are no particular restrictions on the adhesive, but examples include acrylic resin-based, epoxy resin-based, urethane-based, polyester-based, silicone resin-based, vinyl acetate-based, styrene-butadiene rubber-based, nitrile rubber-based, phenolic resin-based, cyanoacrylate-based, etc. Due to ease of production and cost reasons, urethane-based, polyester-based, and vinyl acetate-based are preferred. The composite sheet can be laminated in the form of a film or fiber. Also, a composite sheet may be formed by applying an uncured resin composition to the non-magnetic conductive metal layer or the treatment film and then curing it, but it is preferred to use a composite sheet that can be attached to the non-magnetic conductive metal layer or the treatment film for ease of production. In particular, a PET film can be preferably used. In particular, by using a biaxially stretched film as the PET film, the strength of the electromagnetic wave shielding material can be increased.

[0021] When the ferromagnetic layer is a metal foil, it is more preferable that the ferromagnetic layer is a metal foil containing at least one selected from nickel, iron, permalloy (Ni-Fe alloy), and sendust (Fe-Si-Al alloy). Since these materials have a relatively high magnetic permeability, it is possible to collect the magnetic flux components contained in the noise and reduce the spatial magnetic field.

[0022] <Non-magnetic conductive metal layer> The non-magnetic conductive metal layer is made of a conductive metal material showing diamagnetism or paramagnetism. In one embodiment, the material of the non-magnetic conductive metal layer to be used is not particularly limited, but from the viewpoint of enhancing the shielding characteristics against an alternating magnetic field and an alternating electric field, it is preferable to use a metal material having excellent conductivity. Specifically, it is preferably formed of a metal having a conductivity of 1.0×10 6 S / m (value at 20 °C. The same shall apply hereinafter) or more, more preferably the conductivity of the metal is 10.0×10 6 S / m or more, even more preferably 30.0×10 6 S / m or more, and most preferably 50.0×10 6 S / m or more. Such metals include aluminum with a conductivity of about 39.6×10 6 S / m, copper with a conductivity of about 58.0×10 6 S / m, and silver with a conductivity of about 61.4×10 6 S / m. That is, it is preferable that the non-magnetic conductive metal layer contains one selected from aluminum, copper, and silver, and considering both conductivity and cost, it is practically preferable to adopt aluminum or copper. All the non-magnetic conductive metal layers used in the electromagnetic wave shielding material according to the present invention may be the same metal, or different metals may be used for each layer. Also, alloys of the above-described metals can be used.

[0023] The non-magnetic conductive metal layer is not particularly limited in shape, and examples thereof include metal foils. When a copper foil is used as the non-magnetic conductive metal layer, since the shielding characteristics are improved, a high-purity one is preferable, and the purity is preferably 99.5% by mass or more, more preferably 99.8% by mass or more. As the copper foil, a rolled copper foil, an electrolytic copper foil, a copper foil by metallization, or the like can be used, but a rolled copper foil having excellent flexibility and formability is preferable. When alloy elements are added to the copper foil to form a copper alloy foil, the total content of these elements and inevitable impurities may be less than 0.5% by mass. In particular, when the copper foil contains at least one or more selected from tin, manganese, chromium, zinc, zirconium, magnesium, nickel, silicon, and silver in a total amount of 50 to 2000 ppm by mass and / or phosphorus in an amount of 10 to 50 ppm by mass, the elongation is improved compared to a pure copper foil of the same thickness, which is preferable.

[0024] <Treatment film> From the viewpoint of enhancing the shielding characteristics, the treatment film contains an alloy containing copper and nickel formed on at least one surface of the non-magnetic conductive metal layer. Further, the treatment film may contain an alloy further containing cobalt in addition to copper and nickel. As an example, the treatment film includes an electromagnetic wave absorption auxiliary film of an alloy containing at least copper and nickel, and may further include one or more selected from a heat-resistant film, a rust-proof film, and a weather-resistant film as long as the effects of the present invention are not impaired. At this time, the electromagnetic wave absorption auxiliary film may be an alloy further containing cobalt in addition to copper and nickel. Examples of the heat-treated heat-resistant film include a plating film and a vapor deposition film containing cobalt or nickel, examples of the rust-proof film subjected to rust-proof treatment include an inorganic plating film such as zinc or chromium, a vapor deposition film, an organic film such as benzotriazole, and examples of the weather-resistant film subjected to silane coupling treatment include an organic coating film containing a silane coupling agent. That is, the treatment film may further contain one or more metals selected from cobalt, zinc, molybdenum, tin, phosphorus, tungsten, chromium, and silicon in addition to copper and nickel. In addition, when the ferromagnetic layer is a composite sheet or a metal foil containing a resin, the treatment film interposed between the ferromagnetic layer and the non-magnetic conductive metal layer can also enhance the adhesion between the ferromagnetic layer and the non-magnetic conductive metal layer.

[0025] The electromagnetic wave absorption auxiliary film can be produced by known methods, such as plating, metal vapor deposition, and sputtering. Among them, as an example, a method of forming an electromagnetic wave absorption auxiliary film containing copper and nickel by performing a plating process on the surface of a non-magnetic conductive metal layer will be described below. In the plating process for forming the electromagnetic wave absorption auxiliary film, a particle film composed of copper and nickel is formed on at least one surface of the non-magnetic conductive metal layer. However, a particle film composed of copper, cobalt, and nickel may also be formed on at least one surface of the non-magnetic conductive metal layer.

[0026] (Plating process conditions (roughening plating) 1: Copper and nickel alloy plating) An example of the plating process conditions for copper and nickel is as follows. Liquid composition: Copper 10 - 20 g / L, Nickel 5 - 15 g / L pH: 2 - 3 Liquid temperature: 30 - 50 °C Current density: 10 - 65 A / dm 2 Coulomb amount: 10 - 50 As / dm 2

[0027] (Plating process conditions (roughening plating) 2: Copper, cobalt, and nickel alloy plating) An example of the plating process conditions for copper, cobalt, and nickel is as follows. Liquid composition: Copper 10 - 20 g / L, Cobalt 5 - 15 g / L, Nickel 5 - 15 g / L pH: 2 - 3 Liquid temperature: 30 - 50 °C Current density: 10 - 65 A / dm 2 Coulomb amount: 10 - 48 As / dm 2

[0028] At this time, under the above plating process conditions 1 and / or plating process conditions 2, the roughening plating process can also be carried out in multiple stages.

[0029] (Mass ratio, deposition amount) When each treatment film contains an alloy containing copper, cobalt, and nickel, when the mass ratio of nickel in each treatment film is set to 1, it is preferable that the mass ratio of cobalt in each treatment film is 1.50 to 4.50. The lower limit of the mass ratio of cobalt is, for example, 1.50, or for example, 1.80, or for example, 1.90. Also, the upper limit of the mass ratio of cobalt is, for example, 4.50, or for example, 4.20.

[0030] Regarding the mass ratio in the treatment film containing the alloy containing copper, cobalt, and nickel described above, it can be obtained based on the following formula (1). Mass ratio of cobalt in each treatment film when the mass ratio of nickel in each treatment film is set to 1 = [Co deposition amount of the treatment film (μg / dm 2 ) / Ni deposition amount of the treatment film (μg / dm 2 )] ··· (1)

[0031] In the heat treatment, at least one film of the following heat-resistant films 1 to 8 can be further formed on the electromagnetic wave absorption auxiliary film described above. Each plating condition and vapor deposition condition are shown below.

[0032] (Plating conditions for heat-resistant film 1) (Co-Ni plating: Cobalt-nickel alloy plating) Liquid composition: Nickel 5 to 20 g / L, Cobalt 1 to 8 g / L pH: 2 to 3 Liquid temperature: 40 to 60 °C Current density: 10 to 30 A / dm 2 Coulomb amount: 2 to 20 As / dm 2

[0033] (Plating conditions for heat-resistant film 2) (Ni-Zn plating: Nickel-zinc alloy plating) Liquid composition: Nickel 2 to 30 g / L, Zinc 2 to 30 g / L pH: 3 to 4 Liquid temperature: 30 to 50 °C Current density: 1~10 A / dm 2 Charge quantity: 0.5~2 As / dm 2

[0034] (Plating conditions for heat-resistant film 3) (Ni-Cu plating: Nickel-copper alloy plating) Liquid composition: Nickel 2~30 g / L, Copper 2~30 g / L pH: 3~4 Liquid temperature: 30~50 °C Current density: 1~2 A / dm 2 Charge quantity: 1~2 As / dm 2

[0035] (Plating conditions for heat-resistant film 4) (Ni-Mo plating: Nickel-molybdenum alloy plating) Liquid composition: Nickel sulfate hexahydrate: 45~55 g / dm 3 , Sodium molybdate dihydrate: 50~70 g / dm 3 , Sodium citrate: 80~100 g / dm 3 Liquid temperature: 20~40 °C pH: 1.5~4.5 Current density: 1~4 A / dm 2 Charge quantity: 1~2 As / dm 2

[0036] (Plating conditions for heat-resistant film 5) (Ni-Sn plating: Nickel-tin alloy plating) Liquid composition: Nickel 2~30 g / L, Tin 2~30 g / L pH: 1.5~4.5 Liquid temperature: 30~50 °C Current density: 1~2 A / dm 2 Charge quantity: 1~2 As / dm 2

[0037] (Plating conditions for heat-resistant film 6) (Ni-P plating: Nickel-phosphorus alloy plating) Liquid composition: Nickel 30~70 g / L, Phosphorus 0.2~1.2 g / L pH: 1.5~2.5 Liquid temperature: 30~40°C Current density: 1~2 A / dm 2 Charge amount: 1~2 As / dm 2

[0038] (Plating conditions for heat-resistant film 7) (Ni-W plating: Nickel-tungsten alloy plating) Liquid composition: Nickel 2~30 g / L, Tungsten 0.01~5 g / L pH: 3~4 Liquid temperature: 30~50°C Current density: 1~2 A / dm 2 Charge amount: 1~2 As / dm 2

[0039] (Deposition conditions for heat-resistant film 8) (Ni-Cr deposition: Nickel-chromium alloy deposition) A nickel-chromium alloy deposition film is formed using a sputtering target with a composition of 65~85 mass% nickel and 15~35 mass% chromium. Target: 65~85 mass% nickel, 15~35 mass% chromium Equipment: Sputtering equipment manufactured by ULVAC, Inc. Output: DC50 W Argon pressure: 0.2 Pa

[0040] In the rust prevention treatment, the following rust prevention film and / or weather resistance film can be further formed on the above-mentioned electromagnetic wave absorption auxiliary film or heat-resistant film. Each condition is shown below.

[0041] (Plating conditions for rust prevention film) Liquid composition: Potassium dichromate 1~10 g / L, Zinc 0.2~0.5 g / L pH: 3~4 Liquid temperature: 50~70°C Current density: 0~2 A / dm 2 (0 A / dm 2 is for immersion chromate treatment.) Charge amount: 0~2 As / dm 2 (0 As / dm2 This is the case of immersion chromate treatment.)

[0042] (Type of weather-resistant film (silane coupling film)) As an example, application of a diaminosilane aqueous solution or an epoxysilane aqueous solution can be mentioned.)

[0043] In addition, when a metal film such as a heat-resistant film or a plating film is provided by vapor deposition such as sputtering, and when a metal film such as a heat-resistant film or a plating film is provided by plating, and when the metal film such as a heat-resistant film or a plating film is normal plating (smooth plating, that is, plating performed at a current density less than the limiting current density), the metal film and the plating film do not affect the surface shape of the copper foil.) The limiting current density varies depending on the metal concentration, pH, supply rate of the plating solution, interelectrode distance, and plating solution temperature. In the present invention, the current density at the boundary between normal plating (the state where the plated metal is deposited in a film shape) and roughening plating (burning plating, the state where the plated metal is deposited in a crystalline shape (such as spherical, needle-like, or dendritic), with unevenness) is defined as the limiting current density, and the current density (visual judgment) at the limit (just before burning plating) where normal plating occurs in the Hull cell test is taken as the limiting current density.) Specifically, the metal concentration, pH, and plating solution temperature are set as the plating production conditions, and the Hull cell test is performed. Then, the state of metal layer formation (whether the plated metal is deposited in a layer or formed in a crystalline shape) in the plating solution composition and plating solution temperature is investigated. Then, based on the current density quick reference table manufactured by Yamamoto Plating Tester Co., Ltd., the current density at the boundary position is obtained from the position of the test piece at the boundary between normal plating and roughening plating of the test piece. And the current density at the boundary position is defined as the limiting current density. Thereby, the limiting current density at the plating solution composition and plating solution temperature can be known. Generally, when the interelectrode distance is short, the limiting current density tends to be high.) The method of the Hull cell test is described, for example, on pages 157 to 160 of "Practical Guide to Plating" by Kiyoshi Maruyama, published by Nikkan Kogyo Shimbun Ltd. on June 30, 1983.) In addition, when performing the plating process at a current density below the limiting current density, the current density during the plating process is preferably 20 A / dm 2 or less, more preferably 10 A / dm 2 or less, and even more preferably 8 A / dm 2 or less. Also, since the thicknesses of the rust preventive film and the weather resistance film are extremely thin, they do not affect the surface shape of the copper foil.

[0044] The average thickness (L1) of each treatment layer in the treatment film can be set as appropriate. However, each electromagnetic wave absorption auxiliary film is generally 0.001 μm to 0.8 μm, and other heat-resistant films and the like can have a thickness in the nanometer unit for each layer. The average thickness (L2) of each non-magnetic conductive metal layer is not particularly limited and can be set as appropriate. For example, it is in the range of 1.2 μm to 150 μm. The lower limit of the average thickness (L2) is, for example, 5.0 μm or more, and also, for example, 12 μm or more. Also, the upper limit of the average thickness (L2) is, for example, 75 μm or less, and also, for example, 50 μm or less. Also, the average thickness (L3) of each ferromagnetic layer is not particularly limited and can be set as appropriate. For example, it is in the range of 10 μm to 120 μm. The lower limit of the average thickness (L3) is, for example, 20 μm or more, and also, for example, 30 μm or more. Also, the upper limit of the average thickness (L3) is, for example, 100 μm or less, and also, for example, 60 μm or less. Regarding the method for calculating the average thickness, for example, for L1, a STEM image can be obtained using a transmission electron microscope, and for L2 and L3, the respective thicknesses can be measured using a thickness gauge.

[0045] Although increasing the number of laminations of the ferromagnetic layer and the non-magnetic conductive metal layer improves the shielding characteristics, increasing the number of laminations increases the lamination process, leading to an increase in manufacturing cost. Also, since the shielding improvement effect also tends to saturate, the non-magnetic conductive metal layer in the electromagnetic wave shielding material may be 5 layers or less, and the ferromagnetic layer may be 4 layers or less.

[0046] As a method for laminating a ferromagnetic layer and a nonmagnetic conductive metal layer, an adhesive may be used between the ferromagnetic layer and the nonmagnetic conductive metal layer, or the ferromagnetic layer may be thermocompression bonded to the nonmagnetic conductive metal layer without using an adhesive. A method of simply stacking without using an adhesive may also be used, but considering the integrity of the electromagnetic wave shielding material, at least the ends (for example, each side when the shielding material is square) are preferably joined by tape, an adhesive, or thermocompression bonding. However, from the viewpoint of not applying excessive heat to the ferromagnetic layer, it is preferable to use an adhesive. The adhesive is the same as those described above and is not particularly limited, but examples include acrylic resin-based, epoxy resin-based, urethane-based, polyester-based, silicone resin-based, vinyl acetate-based, styrene-butadiene rubber-based, nitrile rubber-based, phenol resin-based, cyanoacrylate-based, etc. For reasons of ease of manufacture and cost, urethane-based, polyester-based, and vinyl acetate-based are preferable.

[0047] The thickness of the adhesive layer is preferably 100 μm or less. When the thickness of the adhesive layer exceeds 100 μm, the stress on the nonmagnetic conductive metal layer or the ferromagnetic layer, which is the adherend layer, becomes large when bent, and it is likely to break. However, when the adhesive layer as described above also serves as the ferromagnetic layer, this is not the case, and the thickness described in the explanation of the ferromagnetic layer can be used.

[0048] According to one embodiment, it is possible to have magnetic field shielding characteristics (how much the signal is attenuated on the receiving side) of 15 dB or more at 100 kHz, preferably 18 dB or more, more preferably 20 dB or more, still more preferably 24 dB or more, and still more preferably 30 dB or more. In the present invention, the magnetic field shielding characteristics shall be measured by the KEC method. The KEC method refers to the "Electromagnetic Wave Shielding Characteristics Measurement Method" at the Kansai Electronic Industry Promotion Center.

[0049] (Use) In one embodiment, it can be used for various electromagnetic shielding applications, such as coating materials or exterior materials for electrical and electronic devices (e.g., inverters, communication devices, resonators, electron tubes / discharge lamps, electric heating devices, electric motors, generators, electronic components, printed circuits, medical devices, etc.), coating materials for harnesses and communication cables connected to electrical and electronic devices, electromagnetic shielding sheets, electromagnetic shielding panels, electromagnetic shielding bags, electromagnetic shielding boxes, and electromagnetic shielding rooms.

Examples

[0050] The present invention will be specifically described based on Examples, Comparative Examples, and Reference Examples. The descriptions of the following Examples, Comparative Examples, and Reference Examples are merely specific examples for facilitating the understanding of the technical content of the present invention, and the technical scope of the present invention is not limited by these specific examples. In Table 1 below, the "magnetic layer" means a ferromagnetic layer, and the "conductive layer" means a non-magnetic conductive metal layer.

[0051] [Preparation of Electromagnetic Wave Shielding Material] In Examples 1-1 to 6, Comparative Examples 1 to 8, and Reference Examples 1 and 2, as shown in Table 1, rolled copper foil TPC (tough pitch copper standardized in JIS H3100 C1100, manufactured by JX Metals), electrolytic copper foil STD (general electrolytic foil, manufactured by JX Metals), and electrolytic copper foil for rigid substrates (manufactured by JX Metals) were prepared as non-magnetic conductive metal layers, and commercially available permalloy foil and nickel foil were prepared as ferromagnetic layers, respectively.

[0052] Next, in Examples 1-1, 2 to 5, and Reference Example 2, Cu-Co-Ni alloy plating was formed on the rolled copper foil TPC within the following indicated condition ranges. As a result, electromagnetic wave absorption auxiliary films (plated films) composed of particle films of copper, cobalt, and nickel were respectively formed on both surfaces of the rolled copper foil TPC. In addition, heat-resistant films (plated films) composed of cobalt and nickel by heat-resistant plating treatment, heat-resistant films (plated films) composed of nickel and zinc by heat-resistant plating treatment, rust-preventive films (plated films) composed of chromic acid by rust-preventive treatment, and weather-resistant films (coated films) by silane coupling treatment were respectively formed. The film thicknesses of the treatment films are shown in the table assuming 0.5 μm. On the other hand, in Example 1-2, on one surface (upper surface) of the rolled copper foil TPC, an electromagnetic wave absorption auxiliary film (plated film) composed of a particle film of copper, cobalt, and nickel, a heat-resistant film (plated film) composed of cobalt and nickel by plating treatment, a heat-resistant film (plated film) composed of nickel and zinc by plating treatment, a rust-proof film (plated film) composed of chromic acid by rust-proof treatment, and a weather-resistant film (coated film) by silane coupling treatment were respectively formed. Assuming the film thickness of the treatment film is 0.5 μm, it is shown in the table. Also, on the other surface (lower surface) of the rolled copper foil TPC, a heat-resistant film (plated film) composed of nickel and zinc by plating treatment and a rust-proof film (plated film) composed of chromic acid by rust-proof treatment were respectively formed without applying an electromagnetic wave absorption auxiliary film (plated film). Since it is assumed that the film thickness of the treatment film of the heat-resistant film and the rust-proof film is less than 0.1 μm, the overall thickness of the electromagnetic wave shielding material in the table does not include the thickness of the treatment film. The bath compositions and plating conditions used for forming the electromagnetic wave absorption auxiliary film, heat-resistant plating film, rust-proof film, and weather-resistant film are as follows. The following conditions were appropriately adjusted in the order of (A) to (E) below. Note that the upper surface of the rolled copper foil flowing through the conveyor plating line is defined as the upper surface, and the lower surface is defined as the lower surface. Also, in Example 1-2, in order to form a treatment film on one surface of the rolled copper foil TPC, the current density and Coulomb amount of (A) to (D) below were appropriately adjusted under the conditions of the upper surface.

[0053] [Bath Composition and Plating Conditions] (A) Electromagnetic Wave Absorption Auxiliary Film (Cu-Co-Ni Alloy Plating Treatment (Roughening Plating Treatment)) Liquid Composition: Copper 15.5 g / L, Cobalt 7.0 g / L, Nickel 9.3 g / L pH: 2.3 Liquid Temperature: 36.0 °C Current Density: (Upper Surface) First Time: 21.3 A / dm 2 , Second Time: 29.9 A / dm 2 , Third Time: 56.8 A / dm 2 (Lower Surface) First Time: 14.9 A / dm 2 , Second Time: 26.1 A / dm 2, Third time: 56.8 dm 2 Amount of Coulomb: (Upper surface) First time: 15.3 As / dm 2 , Second time: 21.5 As / dm 2 , Third time: 20.5 As / dm 2 (Lower surface) First time: 10.7 As / dm 2 , Second time: 18.8 As / dm 2 , Third time: 27.4 As / dm 2 (B) Heat-resistant film (Co-Ni alloy plating treatment) Liquid composition: Nickel 12.5 g / L, Cobalt 3.1 g / L pH: 2.0 Liquid temperature: 50 °C Current density: (Upper surface) 17.5 A / dm 2 , (Lower surface) 19.3 A / dm 2 Amount of Coulomb: (Upper surface) 6.3 As / dm 2 , (Lower surface) 6.9 A / dm 2 (C) Heat-resistant film (Ni-Zn alloy plating treatment) Liquid composition: Nickel 23.5 g / L, Zinc 4.5 g / L pH: 3.7 Liquid temperature: 40 °C Current density: (Upper surface) 3.6 A / dm 2 , (Lower surface) 4.0 A / dm 2 Amount of Coulomb: (Upper surface) 1.5 As / dm 2 , (Lower surface) 1.6 As / dm 2 (D) Rust-proof film (Electrolytic chromate treatment) Liquid composition: Potassium dichromate 3.0 g / L, Zinc 0.33 g / L pH: 3.65 Liquid temperature: 55 °C Current density: (Upper surface) First time: 1.0 A / dm 2 , Second time: 1.0 A / dm 2 (Lower surface) 1.1 A / dm 2 Amount of Coulomb: (Upper) First time: 0.7 As / dm 2 , Second time: 0.7 As / dm 2 (Lower) 0.8 As / dm 2 (E) Weather-resistant film (silane coupling treatment) Silane coupling agent: glycidoxypropyltrimethoxysilane Silane coupling agent concentration: 0.1 vol% Treatment temperature: 20 °C (room temperature) Treatment time: 5 seconds

[0054] Next, in Example 6, Cu-Ni alloy plating was formed on the electrolytic copper foil within the following condition ranges. As a result, an electromagnetic wave absorption auxiliary film (plating film) composed of a particle film of copper and nickel was formed as a treatment film on one surface of the electrolytic copper foil. It is shown in the table assuming the film thickness of the treatment film is 0.5 μm. The bath composition and plating conditions used to form the electromagnetic wave absorption auxiliary film are as follows. The following conditions were appropriately adjusted according to (F) below. Note that the upper surface of the rolled copper foil flowing through the conveyor plating line is regarded as the upper surface.

[0055] [Bath composition and plating conditions] (F) Electromagnetic wave absorption auxiliary film (Cu-Ni alloy plating treatment (roughening plating treatment)) Liquid composition: copper 15.5 g / L, nickel 9.5 g / L pH: 2.4 Liquid temperature: 36 °C Current density: (Upper) First time: 44.7 A / dm 2 , Second time: 44.2 A / dm 2 , Third time: 63.2 A / dm 2 , Fourth time: 63.2 A / dm 2 Coulomb quantity: (Upper) First time: 17.4 As / dm 2 , Second time: 20.2 As / dm 2 , Third time: 19.3 As / dm 2 , Fourth time: 19.3 As / dm 2

[0056] Next, in Comparative Examples 1 to 5 and Reference Example 1, a rust preventive film was formed on both surfaces of the rolled copper foil TPC within the following indicated condition ranges. Also, in Comparative Example 8, a rust preventive film was formed on both surfaces of the electrolytic copper foil STD within the following indicated condition ranges. Since it is assumed that the film thickness of the treatment film, which is the rust preventive film, is less than 0.1 μm, the overall thickness of the electromagnetic wave shielding material in the table does not include the thickness of the treatment film. According to the following (G), the following conditions were appropriately adjusted.

[0057] (G) Rust preventive film (benzotriazole treatment) Liquid composition: 40 mg / L Liquid temperature: 20 °C (room temperature) pH: 3.0 Current density: 0 A / dm 2 (Shower spray treatment) Treatment time: 5 seconds

[0058] Next, in Comparative Example 6, a smooth Ni plating film was formed on one surface of the electrolytic copper foil within the following indicated condition ranges. Further, a rust preventive film was formed thereon within the following indicated condition ranges. Also, in Comparative Example 7, smooth Ni plating films were formed on both surfaces of the electrolytic copper foil STD within the following indicated condition ranges. Further, a rust preventive film was formed thereon within the following indicated condition ranges. The bath compositions and plating conditions used are as follows. According to the following (H) to (I) in order, the following conditions were appropriately adjusted. Note that the film thickness of the treatment film composed of the smooth Ni film and the rust preventive film is assumed to be 0.5 μm and is shown in the table.

[0059] [Bath compositions and plating conditions] (H) Smooth Ni film (Ni plating treatment) Liquid composition: Nickel 55 g / L, Sodium citrate 7.0 g / L pH: 4.0 Liquid temperature: 50 °C Current density: 4.0 A / dm 2 Coulomb amount: 350 As / dm 2 (I) Rust prevention film (benzotriazole treatment) Liquid composition: 40 mg / L Liquid temperature: 20 °C (room temperature) pH: 3.0 Current density: 0 A / dm 2 (Shower spray treatment) Treatment time: 5 seconds

[0060] Next, in Example 1-1, an electromagnetic shielding material was obtained by alternately laminating a permalloy foil and a rolled copper foil TPC on which a treatment film containing copper, cobalt, and nickel alloy plating was formed on both surfaces according to the configuration shown in Table 1. In Example 1-2, a rolled copper foil TPC on which a treatment film containing copper, cobalt, and nickel alloy plating was formed on one surface and a treatment film composed of a heat-resistant film and a rust prevention film was formed on the other surface was prepared according to the configuration shown in Table 1, and an electromagnetic shielding material was obtained by alternately laminating the permalloy foil and the rolled copper foil so that the permalloy foil was sandwiched between the treatment films (treatment films containing copper, cobalt, and nickel alloy plating) of the two rolled copper foils TPC. In Examples 2 to 5, an electromagnetic shielding material was obtained by alternately laminating a nickel foil and a rolled copper foil TPC on which a treatment film containing copper, cobalt, and nickel alloy plating was formed on both surfaces according to the configuration shown in Table 1. In Example 6, an electrolytic copper foil on which a treatment film containing copper and nickel alloy plating was formed on one surface was prepared according to the configuration shown in Table 1, and an electromagnetic shielding material was obtained by alternately laminating the permalloy foil and the electrolytic copper foil so that the permalloy foil was sandwiched between the treatment films of the two electrolytic copper foils. In Reference Example 2, an electromagnetic shielding material was obtained in which a treatment film containing copper, cobalt, and nickel alloy plating was formed on both surfaces of the rolled copper foil TPC according to the configuration shown in Table 1. On the one hand, in Comparative Examples 1 to 5, an electromagnetic shielding material was obtained in which a permalloy foil or a nickel foil and a rolled copper foil TPC with a rust preventive film formed on both surfaces were alternately laminated. Further, in Comparative Example 6, according to the configuration shown in Table 1, a permalloy foil and an electrolytic copper foil with a treatment film composed of a smooth Ni film and a rust preventive film formed on both surfaces were prepared, and the permalloy foil was sandwiched between the treatment films of the two electrolytic copper foils, and an electromagnetic shielding material in which the permalloy foil and the electrolytic copper foil were alternately laminated was obtained. Further, in Comparative Example 7, according to the configuration shown in Table 1, an electromagnetic shielding material was obtained in which a permalloy foil and an electrolytic copper foil STD with a treatment film composed of a smooth Ni film and a rust preventive film formed on both surfaces were alternately laminated. Further, in Comparative Example 8, according to the configuration shown in Table 1, an electromagnetic shielding material was obtained in which a permalloy foil and an electrolytic copper foil STD with a rust preventive film formed on both surfaces were alternately laminated. Further, in Reference Example 1, an electromagnetic shielding material with a rust preventive film formed on both surfaces of the rolled copper foil TPC was obtained. In Examples 1-1 to 6 and Comparative Examples 1 to 8, the ends of the obtained electromagnetic shielding materials were joined with a single-sided tape.

[0061] <Evaluation Method> (Shielding Property Evaluation) The upper and lower four corners of the jig for KEC were fixed so that the rolled copper foil TPC or the electrolytic copper foil and the permalloy foil or the nickel foil constituting the electromagnetic shielding material did not shift during measurement, and the electromagnetic shielding material was installed in a magnetic field shielding property evaluation apparatus (Techno Science Japan Co., Ltd., model T SES-KEC). Then, the electromagnetic shielding materials obtained in Examples 1-1 to 6, Comparative Examples 1 to 8, and Reference Examples 1 and 2 were evaluated for their magnetic field shielding properties at a frequency of 100 kHz by the KEC method under room temperature (25°C) conditions using the magnetic field shielding property evaluation apparatus. The results are shown in Table 1.

[0062] (Weather Resistance) The electromagnetic wave shielding material was left standing in a thermo-hygrostat at a temperature of 85°C and a humidity of 85% Rh, and the weather resistance was evaluated by checking the discoloration state of the surface of the electromagnetic wave shielding material after 200 hours (after standing). When no discoloration was confirmed on the surface of the electromagnetic wave shielding material before and after standing in the apparatus, it was judged as "〇", while when discoloration was confirmed on the surface of the electromagnetic wave shielding material before and after standing in the apparatus, it was judged as "×", and the results are shown in Table 1.

[0063] (Measurement of Adhesion Amount) Rolled copper foils TPC with treatment films formed under the same conditions as in Examples 1-1 to 5 and Comparative Example 2 were used as samples. Regarding the measurement of the adhesion amount of various metals other than copper in the treatment film, the film on the surface of a 50 mm × 50 mm copper foil was dissolved in an aqueous solution of HNO3 (30% by volume), and the metal concentration in a 10-fold diluted aqueous solution of the solution was quantified using an ICP emission spectroscopic analyzer (manufactured by SII NanoTechnology Inc., SFC-3100), and the metal amount per unit area (μg / dm 2 ) was calculated and derived. At this time, masking was performed as necessary so that the metal adhesion amount on the surface opposite to the surface to be measured was not mixed in, and the analysis was carried out. When the mass ratio of nickel in each treatment film was set to 1, the mass ratio of cobalt in each treatment film was 2.3 on the upper surface side of the rolled copper foil and 2.1 on the lower surface side. That is, in Examples 1-1, 2 to 5, and Comparative Example 2 in which treatment films containing copper, cobalt, and nickel alloy plating were formed on both surfaces, the mass ratio of cobalt in each treatment film was considered to be 2.3 on the upper surface of the rolled copper foil and 2.1 on the lower surface. Also, in Example 1-2 in which a treatment film containing copper, cobalt, and nickel alloy plating was formed on one surface (the upper surface of the rolled copper foil), the mass ratio of cobalt in the treatment film on the upper surface of the rolled copper foil was considered to be 2.3. Also, the mass ratio in the treatment film was calculated by the following formula (2). Mass ratio of cobalt in each treatment film when nickel in each treatment film is set to 1 = [Co adhesion amount of treatment film (μg / dm 2 ) / Ni adhesion amount of treatment film (μg / dm 2 )] ··· (2)

[0064]

Table 1

[0065] [Consideration according to Examples] When comparing Reference Example 1 and Reference Example 2, even if a treatment film containing an alloy containing copper and nickel was included on at least one surface of the non-magnetic conductive metal layer, the shielding characteristics in the low-frequency region deteriorated. That is, even if a treatment film containing an alloy containing copper and nickel was included on at least one surface of the non-magnetic conductive metal layer alone, it was difficult to improve the shielding characteristics in the low-frequency region. On the other hand, in Examples 1-1 to 6, compared with the corresponding Comparative Examples 1 to 6, by having a treatment film containing an alloy containing copper and nickel on at least one surface of the non-magnetic conductive metal layer, the shielding characteristics in the low-frequency region were good. In Examples 1-1 to 6, a ferromagnetic layer was present compared with Reference Example 2. From these points, it can be seen that an electromagnetic wave shielding material having a ferromagnetic layer and a non-magnetic conductive metal layer, and further having a treatment film containing an alloy containing copper and nickel on at least one surface of the non-magnetic conductive metal layer exhibits good shielding characteristics in the low-frequency region. Also, when comparing Comparative Example 7 and Comparative Example 8, it can be seen that it is difficult to improve the shielding characteristics if the treatment film on at least one surface of the non-magnetic conductive metal layer is not appropriate. In addition, in Examples 1-1 to 5, at least one outermost layer of the electromagnetic wave shielding material was a non-magnetic conductive metal layer, and by having a rust preventive film or a weather resistant film contained in the treatment film formed outside the surface of the non-magnetic conductive metal layer, the weather resistance was good.

Claims

1. An electromagnetic wave shielding material having a structure in which a ferromagnetic layer and a nonmagnetic conductive metal layer are laminated, further having a treatment film containing an alloy containing copper and nickel on at least one surface of the nonmagnetic conductive metal layer, The treatment film includes an electromagnetic wave absorption auxiliary film and one or more films selected from a heat-resistant film, a rust-proof film, and a weather-resistant film on the electromagnetic wave absorption auxiliary film, an electromagnetic wave shielding material.

2. The electromagnetic wave shielding material according to claim 1, wherein the ferromagnetic layer is laminated via at least two nonmagnetic conductive metal layers.

3. The electromagnetic wave shielding material according to claim 1, wherein at least one outermost layer is a nonmagnetic conductive metal layer.

4. The electromagnetic wave shielding material according to any one of claims 1 to 3, wherein the alloy contained in the treatment film further contains cobalt.

5. The electromagnetic wave shielding material according to claim 4, wherein when the mass ratio of nickel in each treatment film is 1, the mass ratio of cobalt in each treatment film is 1.50 to 4.

50.

6. A coating material or an exterior material for an electric / electronic device provided with the electromagnetic wave shielding material according to any one of claims 1 to 3.

7. A coating material or an exterior material for an electric / electronic device provided with the electromagnetic wave shielding material according to claim 4.

8. An electric / electronic device provided with the coating material or the exterior material according to claim 6.

9. An electric / electronic device provided with the coating material or the exterior material according to claim 7.

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