JP2005216927A - Electromagnetic noise suppressor, structure having electromagnetic noise suppression function, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic noise suppressor that improves electromagnetic noise suppression efficiency in a high frequency band, saves space, is light, and has sufficient flame resistance, to provide a structure, such as a printed-wiring board, in which electromagnetic noise is suppressed, and to provide a method for easily manufacturing them. <P>SOLUTION: The electromagnetic noise suppressor 1 has a substrate 2 for containing a binder and a non-halogen non-antimony-based flame retarder, and a compound layer 3 in which the binder of one portion of the substrate 2 and a magnetic body are integrated. The method for manufacturing the electromagnetic noise suppressor 1 forms the compound layer 3 on the surface of the substrate 2 by physically depositing the physical body on the substrate 2. In the structure having electromagnetic noise suppression functions, at least one portion of the structure surface is covered with the electromagnetic noise suppressor. In the manufacturing method of the structure having electromagnetic noise suppression functions, at least one portion of the surface of the structure is covered with the substrate, the magnetic body is physically deposited on the substrate, and the compound layer is formed on the substrate surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electromagnetic wave noise suppression body, a structure with an electromagnetic wave noise suppression function, and a method for manufacturing the same.

  Electromagnetic noise suppressors are covered by radiation noise by being covered on flat cables, semiconductor integrated circuits, printed wiring boards, liquid crystal displays, housing inner walls, etc. for various electric and electronic devices such as personal computers, digital cameras, and car navigation systems. Interference between the circuit and the electronic component, radiation noise to the outside of the device, and the like can be reduced.

Recently, electrical / electronic devices and electronic components have been required to have high performance, downsizing, and light weight. Similarly, the electromagnetic wave noise suppression body used in these devices has high electromagnetic wave noise suppression efficiency in a high frequency band. There is a need for space-saving and lightweight.
Also, electrical and electronic devices are strongly required to have flame retardancy (equivalent to UL94 V-0, V-1 or equivalent to VTM-0, VTM-1) in terms of safety, and electromagnetic waves used for these Similarly, flame retardance (equivalent to UL94 V-0, V-1 or equivalent to VTM-0, VTM-1) is also required for noise suppression bodies. Here, UL refers to US Underwriters Laboratories Inc. It is a safety standard for electrical equipment established and approved by the company, and UL94 is a flame retardant standard. Hereinafter, the flame retardancy corresponding to UL94 V-0, V-1, VTM-0, and VTM-1 is simply referred to as “flame retardancy”.

Patent Document 1 discloses an electromagnetic wave absorbing layer obtained by applying a coating containing a polymer binder, a soft magnetic powder, and a phosphorus-based flame retardant on a support as an electromagnetic wave absorber having flame retardancy. Yes.
However, when soft magnetic powder is used as an electromagnetic wave absorber, it is necessary to use a large amount in order to exhibit sufficient electromagnetic wave absorption, and the amount is specifically 5 to 12 parts by mass of the polymer binder. 100 parts by mass. When soft magnetic powder is used as an electromagnetic wave absorbing material, the electromagnetic wave absorbing layer must be thick in order to exhibit sufficient electromagnetic wave absorbing properties. Therefore, the electromagnetic wave absorbing layer has a high specific gravity and is thick, and there is a problem that the electromagnetic wave absorber becomes heavy.

In addition, since the electromagnetic wave absorbing layer is provided on the support, the electromagnetic wave absorbing body becomes thick and there is a problem that it is difficult to save space.
Furthermore, since the soft magnetic powder is a metal powder, it tends to generate heat and ignite. Therefore, in order for the electromagnetic wave absorber to exhibit sufficient flame retardancy, there is also a problem that a large amount of flame retardant must be added.
In addition, since most of the soft magnetic powders are present and the polymer binder is small, there is a problem that they are not flexible and are brittle.
JP 2000-196281 A

Accordingly, an object of the present invention is to provide an electromagnetic wave noise suppressing body that has high electromagnetic wave noise suppression efficiency in a high frequency band, is space-saving and lightweight, and has sufficient flame resistance; a printed wiring board and the like in which electromagnetic wave noise is suppressed A body; and a production method capable of easily producing them.
Another object of the present invention is to provide an electromagnetic noise suppressor that is flexible and has high strength.

That is, the electromagnetic wave noise suppressor of the present invention includes a substrate containing a binder and a non-halogen-based and non-antimony-based flame retardant (hereinafter referred to as a non-halogen non-antimony-based flame retardant); And a composite layer formed by integrating a binder and a magnetic material.
Here, the thickness of the composite layer is preferably 0.3 μm or less.
The composite layer is preferably a layer formed by physically depositing a magnetic material on the substrate.
Furthermore, the binder is preferably a resin or rubber, and more preferably a curable resin.

  The method for producing an electromagnetic wave noise suppressor according to the present invention has a vapor deposition step of physically depositing a magnetic substance on a substrate containing a binder and a non-halogen non-antimony flame retardant to form a composite layer on the substrate surface. It is characterized by.

The structure with an electromagnetic wave noise suppression function of the present invention is characterized in that at least a part of the surface of the structure is covered with the electromagnetic wave noise suppression body of the present invention.
Here, as the structure, a printed wiring board on which an electronic component is mounted is preferable.
The method for producing a structure with an electromagnetic wave noise suppression function according to the present invention includes a coating step in which at least a part of the surface of the structure is coated with a substrate containing a binder and a non-halogen non-antimony flame retardant, and the binder is magnetic. A vapor deposition step of physically depositing the body to form a composite layer on the binder surface.

  The electromagnetic wave noise suppression body of the present invention has a substrate containing a binder and a non-halogen non-antimony flame retardant, and a composite layer in which a part of the binder and the magnetic body are integrated. Therefore, electromagnetic wave noise suppression efficiency in a high frequency band is good, space-saving and lightweight, and sufficient flame retardancy.

Here, if the thickness of the composite layer is 0.3 μm or less, the electromagnetic wave noise suppression efficiency can be further improved, and further space saving and weight reduction can be achieved.
Further, if the composite layer is a layer obtained by physically depositing a magnetic material on a substrate, the magnetic material is dispersed in the binder, and the binder and the magnetic material are integrated. It can be a composite layer.
Furthermore, if the binder is a resin or rubber, the electromagnetic wave noise suppressor can be flexible and has high strength. If the binder is a curable resin, the magnetic substance is more concentrated in the uncured binder. After the dispersion is uniformly performed and the binder is cured, the magnetic material does not crystallize and grow into fine particles, and a composite layer in which the binder and the magnetic material are integrated in an atomic state can be obtained.

  The method for producing an electromagnetic wave noise suppressor according to the present invention is a method having a vapor deposition process in which a magnetic material is physically vapor-deposited on a substrate and a composite layer is formed on the surface of the binder. Therefore, the binder and the magnetic material are integrated. The electromagnetic wave noise suppression body of this invention which has the composite layer formed can be manufactured easily.

  In the structure with electromagnetic wave noise suppression function of the present invention, since at least a part of the surface of the structure is covered with the electromagnetic wave noise suppression body of the present invention, the electromagnetic wave noise suppression body is compact in the vicinity of the noise generation source. The electromagnetic wave noise in a high frequency band can be efficiently suppressed, and has sufficient flame retardancy.

  The method for producing a structure with an electromagnetic wave noise suppression function according to the present invention includes a coating step of coating at least a part of the surface of the structure with a substrate containing a binder and a non-halogen non-antimony flame retardant, and a magnetic material on the substrate. Since the method includes a vapor deposition step of physically vapor-depositing to form a composite layer on the surface of the substrate, electromagnetic noise in a high frequency band can be efficiently suppressed, and electromagnetic noise having sufficient flame retardancy A structure with a suppression function can be easily manufactured.

The present invention will be described in detail below.
<Electromagnetic wave noise suppressor>
The electromagnetic wave noise suppression body of the present invention has a substrate containing a binder and a non-halogen non-antimony flame retardant, and a composite layer in which a part of the binder and the magnetic body are integrated. .

  More specifically, as shown in FIG. 2, which is a schematic diagram of the high-resolution transmission electron microscope image of FIG. 1 and the electron microscope image, the electromagnetic wave noise suppressor 1 includes a binder and a non-halogen non-antimony flame retardant. And a composite layer 3 in which the magnetic substance is in an atomic form and mixed with a part of the binder molecules of the base 2.

(Composite layer)
The composite layer 3 is a layer formed by physically vapor-depositing a magnetic material on the surface of the substrate 2, and the physically vapor-deposited magnetic material is dispersed and integrated in the binder in an atomic state without forming a homogeneous film. It will be.

  The composite layer 3 includes a portion where a crystal lattice 4 in which magnetic atoms of several tens of intervals are arranged as very small crystals is observed, and a portion where only a binder 6 where no magnetic material exists in a very small range is observed. The magnetic material atoms 5 are not crystallized but are dispersed in the binder and observed. In other words, the grain boundary where the magnetic substance is present as a fine particle having a clear crystal structure is not observed, and it has a complex heterostructure (heterogeneous / asymmetric structure) in which the magnetic substance and the binder are integrated on the nano order. It is thought that.

The thickness of the composite layer is the depth of penetration of the magnetic atoms into the surface of the binder, and depends on the deposition mass of the magnetic material, the binder material, physical vapor deposition conditions, etc. 1.5 to 3 times as much. Here, the vapor deposition thickness of the magnetic material means the film thickness when the magnetic material atoms are physically vapor-deposited on a hard substrate where the magnetic material atoms do not enter.
By setting the thickness of the composite layer to 0.005 μm or more, it is possible to disperse and integrate with the binder of magnetic substance atoms and to have a large loss characteristic in the high frequency region derived from the shape anisotropy, A sufficient electromagnetic noise suppression effect can be exhibited. On the other hand, if the thickness of the composite layer exceeds 3 μm, a homogeneous magnetic film is formed through a clear crystal structure, which returns to the bulk magnetic body, reducing the shape anisotropy and reducing the noise suppression effect. Is not effective. Therefore, the thickness of the composite layer is more preferably 0.3 μm or less.

(Binder)
The binder is not particularly limited. For example, polyolefin resin, polyamide resin, polyester resin, polyether resin, polyketone resin, polyimide resin, polyurethane resin, polysiloxane resin, phenol resin, epoxy Resins such as acrylic resins, acrylic resins, polyacrylate resins, diene rubbers such as natural rubber, isoprene rubber, butadiene rubber and styrene butadiene rubber, non-diene rubbers such as butyl rubber, ethylene propylene rubber, urethane rubber and silicone rubber Organic substances such as These may be thermoplastic, may be thermosetting, or may be an uncured product thereof. Further, the above-described resins, modified products such as rubber, mixtures, and copolymers may be used.

  The binder may be an inorganic material having a low shear modulus, which will be described later, and can be used as long as it has a large void such as aerogel or foamed silica and has a hardness capable of capturing ultrafine particles. Further, it may be a composite with the organic material.

Among them, the binder preferably has a low shear modulus in physical vapor deposition of a magnetic substance described later in terms of ease of entry of magnetic atoms into the binder. The thing of 5 * 10 < ⁷ > Pa or less is preferable. In order to obtain a desired shear modulus, the binder can be heated to, for example, 100 to 300 ° C. as necessary, but it is necessary to heat to a temperature at which decomposition and evaporation do not occur. When physical vapor deposition is performed at normal temperature, the binder is preferably an elastic body having a rubber hardness of about 80 ° (JIS-A) or less.

Moreover, as a binder, the thing with a high shear elastic modulus is preferable after the physical vapor deposition of a magnetic body from the point which maintains the above-mentioned heterostructure. By increasing the shear modulus of the binder after physical vapor deposition of the magnetic material, it is possible to reliably prevent nano-order magnetic material atoms or clusters from aggregating and crystallizing and growing into fine particles. Specifically, the temperature range in which the noise suppressor is used is preferably 1 × 10 ⁷ Pa or more. In order to achieve the desired shear modulus, it is preferable to crosslink the binder after physical vapor deposition of the magnetic material.
In this respect, as the binder, a thermosetting resin or an energy ray (ultraviolet ray, electron beam) curable resin is preferable because it has a low elastic modulus at the time of vapor deposition and can be crosslinked to increase the elastic modulus after vapor deposition. It is.

  Furthermore, silane coupling agents, titanate coupling agents, nonionic surfactants, polar resin oligomers in the binder so that the plasma or ionized magnetic atoms partially react with the binder and stabilize. Etc. may be blended. By blending such an additive, in addition to preventing oxidation, formation of a homogeneous film due to atomic aggregation can be prevented, reflection of electromagnetic waves by the homogeneous film can be prevented, and absorption characteristics can be improved.

(Non-halogen non-antimony flame retardant)
As the flame retardant, one containing no halogen element or antimony element is essential. A compound containing a halogen element or an antimony element has been regarded as a problem as an environmentally hazardous substance. In recent years, halogen / antimony-free products that are environmentally friendly have become indispensable.

  Note that even a non-halogen material cannot be said to be completely zero in halogen elements. This is because chlorine exists in the natural environment, and since halogen compounds, such as epichlorohydrin, are used in the material synthesis process, there is a residual halogen level of impurities even when the material is purified. This is because it is very difficult to make this zero. Therefore, in the present invention, the chlorine content and bromine content specified by the JPCA standard halogen-free copper-clad laminate test method (JPCA-ES-01) are 0.09% or less. No ”(halogen free).

As the non-halogen non-antimony flame retardant, a known one can be used, and either a liquid or solid one may be used. The non-halogen non-antimony flame retardant is appropriately selected depending on the kind of resin, rubber, or the like as a binder.
Examples of non-halogen non-antimony flame retardants include phosphorus flame retardants, nitrogen flame retardants, metal hydroxides, metal oxides, silicone flame retardants, and platinum compounds.

  Examples of the phosphorus-based flame retardant include triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, triethyl phosphate, cresyl phenyl phosphate, xylenyl diphenyl phosphate, cresyl (di-2,6- Xylenyl) phosphate, 2-ethylhexyl diphenyl phosphate, dimethylmethyl phosphate, red phosphorus, yellow phosphorus and the like.

Examples of nitrogen flame retardants include guanidine flame retardants such as guanidine sulfamate and guanidine phosphate; guanyl urea flame retardants such as guanyl urea phosphate; melamine flame retardants such as melamine sulfate and melamine polyphosphate. It is done.
A phosphazene flame retardant, which is a compound having a double bond containing phosphorus and nitrogen as constituent elements, can also be used. Examples of the phosphazene flame retardant include phosphazene compounds such as propoxyphosphazene, phenoxyphosphazene, and aminophosphazene.

  Examples of the metal hydroxide include aluminum hydroxide, magnesium hydroxide, dolomite, hydrotalcite, calcium hydroxide, barium hydroxide, zirconium hydroxide, tin oxide hydrate, and the like. Other inorganic flame retardants include, for example, metal powders such as aluminum, iron, titanium, manganese, zinc, molybdenum, cobalt, bismuth, chromium, nickel, copper, tungsten, tin; silica, aluminum oxide, iron oxide, Metal oxides such as titanium oxide, manganese oxide, magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide, cobalt oxide, bismuth oxide, chromium oxide, tin oxide, nickel oxide, copper oxide, tungsten oxide; zinc borate, metaboric acid Examples include zinc, barium metaborate, zinc carbonate, magnesium carbonate, calcium carbonate, and barium carbonate.

Examples of the silicone flame retardant include silicone powder having an epoxy group or a methacryl group.
Examples of the platinum compound include hexachloroplatinic (IV) acid, dinitrodiamineplatinum (II), tetraaminedichloroplatinum (II), and the like.

  Also, various resin additives that do not inhibit the properties of the flame retardant can be added in appropriate combination. For example, coupling agents, dispersants, surfactants, anti-aging agents, lubricants, plasticizers, thixotropic improvers, antioxidants, colorants, fillers, antistatic agents, heat stabilizers, UV absorbers, etc. Can be mentioned. These additives may be used alone or in combination of two or more.

In addition, as a flame retardant, not only a so-called additive-type flame retardant that is simply added to the binder, but also a reaction that causes a molecular reaction with the skeleton of the binder and introduces a flame retardant element such as a compound containing nitrogen or phosphorus into the binder. A type flame retardant may be used.
There are types of flame retardants that are effective in framing and types that are effective in glowing. It is effective to use a combination of a plurality of types of flame retardants as required. In addition, flame retardant imparts flame retardancy to the electromagnetic wave noise suppressor, while other characteristics of the electromagnetic wave noise suppressor may be deteriorated. Therefore, considering the balance of characteristics, the type and amount of the flame retardant are appropriately selected. Must be set.

  The amount of non-halogen non-antimony flame retardant added varies depending on the type of binder and the type of flame retardant. For example, in the case of a phosphorus flame retardant, 0.5 to 20 parts by mass is preferable with respect to 100 parts by mass of the binder, and in the case of a metal hydroxide, 50 to 300 parts by mass with respect to 100 parts by mass of the binder is preferable. In the case of a platinum compound, 0.01-1 mass part is preferable with respect to 100 mass parts of binders. If the addition amount of the non-halogen non-antimony flame retardant is too small, the flame retardancy of the electromagnetic wave noise suppressor may be insufficient, and if the addition amount of the non-halogen non-antimony flame retardant is too large, the desired bond There is a possibility that the shear modulus of the agent cannot be obtained, or the mechanical strength of the binder itself, for example, the tear strength and the tensile strength are lowered.

  The electromagnetic noise suppressor of the present invention may have a planar shape such as a sheet shape or a three-dimensional structure. Further, as will be described later, when the structure is used for covering the surface of the structure, it may have a shape following the shape of the structure.

<Method for producing electromagnetic wave noise suppression body>
Hereinafter, the manufacturing method of an electromagnetic wave noise suppression body is demonstrated.
The electromagnetic wave noise suppression body of the present invention can be obtained, for example, by physically vapor-depositing a magnetic body on a substrate to form a composite layer on the substrate surface (deposition process).

(Deposition process)
In general, physical vapor deposition (PVD) is a method in which a vaporized material is vaporized by some method in a vacuumed container, and the vaporized vaporized material is deposited on a substrate placed nearby to form a thin film. Depending on the material vaporization method, it can be divided into an evaporation system and a sputtering system. Examples of the evaporation system include EB vapor deposition and ion plating. Examples of the sputtering system include high-frequency sputtering, magnetron sputtering, and counter target type magnetron sputtering.

EB deposition has a feature that since the energy of the evaporated particles is as small as 1 eV, the substrate is less damaged, the film tends to be porous, and the film strength tends to be insufficient, but the specific resistance of the film increases.
According to the ion plating, ions of argon gas and evaporated particles are accelerated and collide with the substrate. Therefore, the energy is larger than that of EB, the particle energy is about 1 KeV, and a film having strong adhesion can be obtained. The adhesion of micron-sized particles called droplets cannot be avoided, and there is a possibility that the discharge stops. In addition, an oxide film can be formed by introducing a reactive gas such as oxygen.

  Magnetron sputtering has a low utilization efficiency of the target (evaporation material), but has a high growth rate because a strong plasma is generated under the influence of a magnetic field and has a high particle energy of several tens eV. In the high frequency sputtering, an insulating target (evaporation material) can be used.

  Opposite target type magnetron sputtering is a method of generating a desired thin film without plasma damage by generating a plasma between opposing targets (evaporation material) and placing a substrate outside the opposing target. . Therefore, without re-sputtering the thin film on the substrate, the growth rate is further increased, and the sputtered atoms are not relieved by collision, and a dense target composition having the same composition can be generated.

  When the binder is made of a resin (or rubber), the covalent bond energy of the resin is about 4 eV. Specifically, for example, the bond energy of C—C, C—H, Si—O, and Si—C is 3 respectively. .6 eV, 4.3 eV, 4.6 eV, 3.3 eV. On the other hand, in ion plating, magnetron sputtering, or counter target type magnetron sputtering, since the evaporated particles have high energy, it is considered that some chemical bonds of the resin are cut and collide.

  Therefore, in the present invention, when the elastic modulus of the binder made of resin (or rubber) is sufficiently small, when the magnetic material is deposited, the resin molecules vibrate and move, and in some cases, the molecules are cut and magnetic atoms As a result of local mixing action between the resin and the resin, the magnetic atoms enter up to about 3 μm from the surface of the resin and interact with the resin. It is considered that a composite layer having a structure is formed.

  It is preferable to physically deposit magnetic substance atoms having a particle energy of 5 eV or more on the binder because a large amount of the magnetic substance can be dispersed in the binder at one time. That is, since the mass of the magnetic material can be increased by a single vapor deposition, an electromagnetic wave noise suppression body with a large noise suppression efficiency can be easily obtained. The deposition rate is preferably smaller so as to match the relaxation timing of the binder because the speed of vibration and movement of the binder is slower than the particle speed, and is preferably about 60 nm / min or less, although it varies depending on the magnetic substance.

  As the magnetic material used as the evaporation material (target) in the vapor deposition step, a metal-based soft magnetic material and / or an oxide-based soft magnetic material and / or a nitride-based soft magnetic material are mainly used. These may be used alone or in combination of two or more.

  As the metal-based soft magnetic material, iron and an iron alloy are generally used. Specific examples of iron alloys include Fe—Ni, Fe—Co, Fe—Cr, Fe—Si, Fe—Al, Fe—Cr—Si, Fe—Cr—Al, Fe—Al—Si, and Fe—Pt. Alloys can be used. These metallic soft magnetic materials may be used alone or in combination of two or more. In addition to iron and iron alloys, cobalt or nickel metals or alloys thereof may be used. Nickel is preferred because it is resistant to oxidation when used alone.

As the oxide soft magnetic material, ferrite is preferable. _{Specifically, MnFe 2 O 4, CoFe 2} O 4, NiFe 2 O 4, CuFe 2 O 4, ZnFe 2 O 4, MgFe 2 O 4, Fe 3 O 4, Cu-Zn- ferrite, Ni-Zn- ferrite, Mn-Zn- _{ferrite, Ba 2 Co 2 Fe 12 O} 22, Ba 2 Ni 2 Fe 12 O 22, Ba 2 Zn 2 Fe 12 O 22, Ba 2 Mn 2 Fe 12 O 22, Ba 2 Mg 2 Fe 12 O ₂₂ , Ba ₂ Cu ₂ Fe ₁₂ O ₂₂ , and Ba ₃ Co ₂ Fe ₂₄ O ₄₁ can be used. These ferrites may be used alone or in combination of two or more.

Known nitride-based soft magnetic materials include Fe ₂ N, Fe ₃ N, Fe ₄ N, and Fe ₁₆ N ₂ . These nitride-based soft magnetic materials are preferable because of their high magnetic permeability and high corrosion resistance.
When the magnetic substance is physically vapor-deposited on the binder, the magnetic substance enters the binder as plasma or ionized magnetic atoms, so the composition of the magnetic substance finely dispersed in the binder is: The composition of the magnetic material used as the evaporation material is not necessarily the same. Moreover, it may react with a part of the binder to cause a change such that the ferromagnetic material becomes a paramagnetic material or an antiferromagnetic material.

  The vapor deposition mass of the magnetic material by one physical vapor deposition operation is preferably 200 nm or less in terms of the thickness of the single magnetic material. If it is thicker than this, the ability of the binder to include the magnetic material is reached, and the magnetic material cannot be dispersed in the binder and is deposited on the surface, thereby producing a continuous bulk film having homogeneous conductivity. Therefore, the vapor deposition mass of the magnetic material is preferably 100 nm or less, and more preferably 50 nm or less. On the other hand, from the point of noise suppression effect, the vapor deposition mass of the magnetic material is preferably 0.5 nm or more.

  Since the effect of suppressing electromagnetic wave noise is reduced when the deposition mass is reduced, the total mass of the magnetic material can be increased by laminating a plurality of composite layers. Although this total mass depends on the required level of suppression of electromagnetic wave noise, it is preferably about 10 to 500 nm in terms of the total film thickness converted value of the magnetic material.

  The thickness of the binder used in the vapor deposition step is not particularly limited, but it is preferably thin for a thin and compact suppressor. Specifically, the thickness is preferably 50 μm or less, more preferably 10 μm or less.

<Structure with electromagnetic wave noise suppression function>
In the structure with electromagnetic wave noise suppression function of the present invention, at least a part of the surface of the structure is covered with the electromagnetic wave noise suppression body of the present invention.
Examples of the structure include a printed wiring board on which electronic components are mounted.
Hereinafter, the specific example of the structure with an electromagnetic wave noise suppression function of this invention is shown.

(The camera module)
3 and 4 are diagrams illustrating a camera module which is an example of a structure with an electromagnetic wave noise suppression function. This camera module includes a printed wiring board 12 having an image sensor 11 on the surface, a lens 13 corresponding to the image sensor 11, a camera holder 14 that holds the lens 13 and surrounds the image sensor 11 on the printed wiring board 12. The outer case 15 fitted to the outside of the camera holder 14 and the electromagnetic wave noise suppression body 1 covering the surface of the outer case 15 are roughly configured.

The outer case 15 is covered with the electromagnetic wave noise suppression body 1 as follows, for example.
The outer case 15 which is a resin structure molded by injection molding is immersed in a solution containing an epoxy resin as a binder and a non-halogen non-antimony flame retardant, and a B-stage epoxy resin having a thickness of 15 μm is provided on the surface. . Next, a magnetic material is vapor-deposited by 45 nm in terms of film thickness on the epoxy resin by a physical vapor deposition method to form a composite layer. By fitting the outer case 15 with the electromagnetic wave noise suppression function to the camera holder 14, noise countermeasures for the camera module are implemented.

(Printed wiring board)
FIG. 5 is a diagram illustrating a printed wiring board as an example of a structure with an electromagnetic wave noise suppression function. The printed wiring board includes a wiring circuit 22 formed on the substrate 21, a semiconductor package 23 and a chip component 24 connected to the wiring circuit 22, and the printed wiring board surface together with the wiring circuit 22, the semiconductor package 23, and the chip component 24. The electromagnetic wave noise suppression body 1 which covers is comprised roughly.

For example, the electromagnetic wave noise suppression body 1 is coated on the printed wiring board as follows.
A resin composition containing an insulating binder and a non-halogen non-antimony flame retardant is applied to the printed wiring board so as to cover the wiring circuit 22, the semiconductor package 23, and the chip component 24. A magnetic material is vapor-deposited thereon by a physical vapor deposition method to form a composite layer. Since it is not a wet process, a cleaning step for removing ions is unnecessary, and a noise suppression function can be easily provided.

<Action>
In the electromagnetic wave noise suppression body of the present invention described above, although theoretically not completely clarified, a composite layer in which a binder containing a flame retardant component and a magnetic body are integrated is formed. Therefore, even with a small amount of magnetic material, the effects of quantum effects derived from the nano-order heterostructure, material-specific magnetic anisotropy, shape magnetic anisotropy, or anisotropy due to an external magnetic field, etc. And has a high resonance frequency. Thereby, it is considered that excellent magnetic characteristics are exhibited, and even with a small amount of magnetic material, an electromagnetic noise suppression effect can be exhibited in a high frequency band.

Moreover, in the electromagnetic wave noise suppression body of this invention, even if it is few magnetic bodies, since the electromagnetic wave noise suppression effect can be exhibited, the quantity of a magnetic body can be reduced significantly and weight reduction can be achieved. .
Furthermore, in the electromagnetic wave noise suppression body of the present invention, a sufficient electromagnetic wave noise suppression effect can be exhibited when the composite layer thickness is 0.3 μm or less. Can be achieved.

  And since the electromagnetic wave noise suppression body of this invention contains the non-halogen non-antimony flame retardant, it exhibits sufficient flame retardance. Furthermore, in the composite layer, the magnetic substance is integrated with the binder in an atomic state, so that the catalytic action and thermal conductivity of the magnetic substance powder are reduced like an electromagnetic wave noise suppressor in which the conventional magnetic substance powder is dispersed in the binder. The improvement of combustibility promotes combustibility, and the phenomenon that the self-extinguishing property decreases can be suppressed. Therefore, the amount of the non-halogen non-antimony flame retardant can be greatly reduced as compared with the conventional electromagnetic noise suppressor.

  Further, if the composite layer is a layer formed by physically depositing a magnetic material on a substrate, the magnetic material is dispersed in an atomic state in the binder, and the binder and the magnetic material are integrated to reduce the amount. It can be set as the composite layer with a high electromagnetic wave noise suppression effect with the quantity of a magnetic body. Further, there are no impurity ions, and there is no risk of damage to the electronic circuit due to these impurity ions.

  In addition, since the amount of the magnetic material can be greatly reduced, when the binder is a resin or rubber, a decrease in flexibility or strength of the resin or rubber due to the magnetic material can be minimized, If it is a curable resin, the magnetic material is more uniformly dispersed in the binder, and after curing, the magnetic material does not crystallize and grow into fine particles. Can do.

Moreover, it is based on physical vapor deposition under high vacuum. Unlike wet plating, it is not necessary to remove impurity ions, and there is no fear of damage to the electronic circuit due to these impurity ions.
In addition, the structure with a noise suppression function (for example, a printed wiring board) according to the present invention can efficiently suppress electromagnetic wave noise in the quasi-microwave band by compactly arranging the noise suppression body in the vicinity of the noise generation source. .

Examples are shown below.
(Evaluation)
Cross-sectional observation:
A transmission electron microscope H9000NAR manufactured by Hitachi, Ltd. was used.

Electromagnetic wave absorption characteristics:
Using a near field electromagnetic wave absorbing material measuring device manufactured by Keycom, S ₁₁ (reflection attenuation) and S ₂₁ (transmission attenuation) by the S parameter method were measured. As the network analyzer, a vector network analyzer 37247C manufactured by Anritsu Corporation was used, and TF-3A manufactured by Keycom was used for a test fixture of a microstrip line having an impedance of 50Ω. Further, the electromagnetic noise suppression effect (P _loss / P _in ) is obtained from the change in transmission characteristics S ₁₁ and S _{21 by} the following equation.
P _loss / P _in = 1− (| S ₁₁ | ² + | S ₂₁ | ² )

P _loss / P _in is a comprehensive index of reflection / transmission characteristics, and it is necessary that the reflection attenuation amount and the transmission attenuation amount are effective values in actual use. Specifically, P _loss / P in It is preferable that _in = 0.4 to 0.7.

Combustion test:
The combustion test was performed in the vertical combustion test UL94 VTM. The sample dimensions were 200 mm in length, 50 mm in width, 0.1 mm in thickness, and the number of samples was 5. The judgment criteria are shown in Table 1.

(Example 1)
Polyacrylonitrile (hereinafter referred to as PAN) (room temperature shear modulus 1.7 × 10 ⁷ Pa) was dissolved in N, N-dimethylacrylamide (hereinafter referred to as DMAc), and a 25 mass% PAN DMAc solution was dissolved. Prepared. After adding 20 parts by mass of aromatic condensed phosphate ester (PX-200; manufactured by Daihachi Chemical Industry Co., Ltd.) as a flame retardant to 400 parts by mass of this solution, polyethylene terephthalate so that the dry film thickness is 0.1 mm. A PAN sheet was obtained by coating on a substrate (hereinafter referred to as PET), drying and forming a film. An Fe—Ni soft magnetic metal having a thickness of 20 nm in terms of film thickness was physically vapor-deposited on one side of the PAN sheet by an opposed target type magnetron sputtering method to form a composite layer, thereby obtaining an electromagnetic wave noise suppression body. At this time, the temperature of the PAN sheet was kept at room temperature, and a slight negative voltage was applied so that the evaporated particles had a particle energy of 8 eV, and sputtering was performed.

A part of the suppressor obtained was thinned with a microtome, an ion beam polisher was applied to the cross section, and the cross section of the composite layer was observed with a high resolution transmission electron microscope. A cross-sectional observation result is shown in FIG. The film thickness of the composite layer was 40 nm (0.040 μm).
In addition, measurement of electromagnetic wave absorption characteristics at 1 GHz and a combustion test were performed. The results are shown in Table 2.

(Example 2)
2-methylimidazole (manufactured by Shikoku Kasei Co., Ltd.) as a curing agent on 100 parts by mass of epoxy resin (shear elastic modulus at normal temperature before curing: 8.0 × 10 ⁶ Pa, shear elastic modulus at normal temperature after curing: 5 × 10 ⁹ Pa) ) 3 parts by mass, 20 parts by mass of triphenyl phosphate (hereinafter referred to as TPP) (made by Daihachi Chemical Industry Co., Ltd.) as a flame retardant, 50 parts by mass of aluminum hydroxide (hereinafter referred to as Al (OH) ₃ ), After adding 50 parts by mass of magnesium hydroxide (hereinafter referred to as Mg (OH) ₂ ), it was coated on PET to form a film thickness of 0.1 mm, and an epoxy resin sheet (B stage state) Got. On one side of the epoxy resin sheet, a Fe—Ni soft magnetic metal having a thickness of 15 nm in terms of film thickness was physically vapor-deposited by a counter target type magnetron sputtering method to form a composite layer. At this time, the temperature of the epoxy resin sheet was kept at room temperature, and a slight negative voltage was applied so that the evaporated particles had a particle energy of 8 eV, and sputtering was performed. Subsequently, it heated at 40 degreeC for 6 hours, and also heated at 120 degreeC for 2 hours, the epoxy resin was hardened, and the electromagnetic wave noise suppression body was obtained.

A part of the suppressor obtained was thinned with a microtome, an ion beam polisher was applied to the cross section, and the cross section of the composite layer was observed with a high resolution transmission electron microscope. The film thickness of the composite layer was 25 nm (0.025 μm).
In addition, measurement of electromagnetic wave absorption characteristics at 1 GHz and a combustion test were performed. The results are shown in Table 2.

(Example 3)
To 100 parts by weight of wet silica-containing silicone rubber (two-component type), 0.2 parts by weight of dinitrodiamine platinum (II) and 1.0 part by weight of acetylene black are added as flame retardants, and vulcanized at 150 ° C. for 1 hour. A 0.1 mm thick silicone sheet was obtained (room temperature shear modulus after vulcanization 1.5 × 10 ⁷ Pa). An Fe—Ni soft magnetic metal having a thickness of 15 nm in terms of film thickness was physically vapor-deposited on one side of the silicone sheet by a counter target magnetron sputtering method to form a composite layer, thereby obtaining an electromagnetic wave noise suppressor. At this time, the temperature of the silicone sheet was kept at room temperature, and a slight negative voltage was applied so that the evaporated particles had a particle energy of 8 eV to perform sputtering.

A part of the suppressor obtained was thinned with a microtome, an ion beam polisher was applied to the cross section, and the cross section of the composite layer was observed with a high resolution transmission electron microscope. The film thickness of the composite layer was 30 nm (0.030 μm).
In addition, measurement of electromagnetic wave absorption characteristics at 1 GHz and a combustion test were performed. The results are shown in Table 2.

(Comparative Example 1)
Containing binder prepared in 300 parts by weight of flat Fe-Ni soft magnetic metal powder (average particle size 15 μm, aspect ratio 65) having a nonconductive film formed by oxidizing the surface 100 parts by mass of solution A was added to form a paste, and a film was formed by applying a bar coating method so that the thickness after drying was 0.1 mm. After sufficiently drying, vacuum pressing was performed at 85 ° C. Was cured for 24 hours to obtain an electromagnetic wave noise suppression body. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.
Preparation of solution A: 60 parts by mass of a polyurethane resin, 20 parts by mass of an isocyanate compound as a curing agent, 20 parts by mass of an aromatic condensed phosphate ester (PX-200: manufactured by Daihachi Chemical Industry Co., Ltd.) as a flame retardant, and a solvent (with cyclohexanone) A 1: 1 mixture with toluene) was added to 400 parts by weight to prepare Solution A.

(Comparative Example 2)
Wet silica-containing silicone rubber (two-component type) 100 on 300 parts by mass of a flat Fe-Ni soft magnetic metal powder (average particle size 15 μm, aspect ratio 65) having a non-conductive film formed by oxidizing the surface As a flame retardant, 0.2 parts by mass of dinitrodiamine platinum (II) and 1.0 part by mass of acetylene black were added and mixed with a mixing roll to obtain a composite magnetic material. The composite magnetic material was rolled with two rolls to form a sheet having a thickness of 0.1 mm, and then vulcanized at 150 ° C. for 1 hour to obtain an electromagnetic wave noise suppression body. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 3)
An electromagnetic wave noise suppressor was prepared in the same manner as in Example 3 except that dinitrodiamine platinum (II) and acetylene black as flame retardants were not added, and evaluation was performed in the same manner as in Example 3. The results are shown in Table 2.

From the results shown in Table 2, P _loss / P _{in at} 1 GHz showed good numerical values in Examples 1 to 3 and Comparative Example 3, and it was confirmed that the electromagnetic wave noise suppression effect was excellent. In Comparative Examples 1 and 2, since the soft magnetic powder and the binder are simply mixed, when the thickness is as thin as 0.1 mm, P _loss / P _{in at} 1 GHz is 0.1 or less, The electromagnetic noise suppression effect was very low. In Comparative Example 1, it was difficult to reduce the thickness to about 0.1 mm, and the evaluation of flame retardancy was not achieved.
Regarding flame retardancy, in Examples 1 to 3, since sufficient flame retardant was added in the binder, VTM-1 in Examples 1 and 2 and VTM-0 in Example 3 using silicone rubber. The electromagnetic wave noise suppression body of Examples 1 to 3 had sufficient flame retardancy. On the other hand, in Comparative Example 2, the same flame retardant as in Example 3 was added, but since the soft magnetic powder was used, sufficient flame retardancy was not obtained. Since it was not added, the flame retardancy satisfying the UL standard could not be obtained.

  The electromagnetic wave noise suppression body of the present invention can be used for coating structures such as electronic devices and electronic components that require flame retardancy, and exhibits sufficient noise suppression effects in a high frequency band while Equipment and electronic components can be reduced in size and weight.

It is a high-resolution transmission electron microscope image of the composite layer in the electromagnetic wave noise suppression body of this invention. It is a schematic diagram which shows an example of the vicinity of a composite layer. It is a bird's-eye view of a camera module which is an example of a structure with an electromagnetic wave noise suppression function of the present invention. It is sectional drawing of the camera module which is an example of the structure with an electromagnetic wave noise suppression function of this invention. It is sectional drawing of the printed wiring board carrying the electronic component which is an example of the structure with an electromagnetic wave noise suppression function of this invention.

Explanation of symbols

1 Electromagnetic wave noise suppression body 2 Base 3 Composite layer

Claims (9)

A substrate containing a binder and a non-halogen and non-antimony flame retardant; and
An electromagnetic wave noise suppression body comprising a composite layer in which a part of the binder of the substrate and a magnetic body are integrated.   The electromagnetic wave noise suppressor according to claim 1, wherein the composite layer has a thickness of 0.3 μm or less.   The electromagnetic wave noise suppression body according to claim 1, wherein the composite layer is a layer formed by physically depositing a magnetic body on the base.   The electromagnetic wave noise suppressor according to any one of claims 1 to 3, wherein the binder is resin or rubber.   The electromagnetic wave noise suppressor according to claim 1, wherein the binder is a curable resin.   Electromagnetic noise characterized by having a deposition step of physically depositing a magnetic material on a substrate containing a binder and a non-halogen and non-antimony flame retardant to form a composite layer on the substrate surface The manufacturing method of a suppression body.   A structure with an electromagnetic wave noise suppression function, wherein at least a part of the surface of the structure is covered with the electromagnetic wave noise suppression body according to any one of claims 1 to 5.   The structure with electromagnetic wave noise suppression function according to claim 7, wherein the structure is a printed wiring board on which an electronic component is mounted. A coating step of coating at least a portion of the surface of the structure with a substrate containing a binder and a non-halogen and non-antimony flame retardant;
A method for producing a structure with a noise suppression function, comprising: a vapor deposition step of physically depositing a magnetic material on a substrate surface to form a composite layer on the substrate surface.

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