JP4596154B2 - Composite porous body and method for producing composite porous body - Google Patents

Description

  The present invention relates to a composite porous body comprising a porous body filled with a resin and a conductive metal substrate, and a method for producing the same.

  In recent years, electronic devices using high frequencies such as digital electronic devices have been widely used. In particular, mobile communication devices using a quasi-microwave band have been widely used. For example, mobile phones and the like have become smaller and lighter. The demand for is strong. As a result, electronic components are being developed in the direction of high-density mounting. However, under such high-density mounting, electromagnetic coupling between components and wiring often prevents normal operation of the device. In a personal computer or the like, radiation noise is likely to be generated due to the increase in the clock, and such noise is likely to have an adverse effect on peripheral parts and peripheral devices and needs to be dealt with.

In order to cope with these problems, a composite magnetic sheet in which magnetic powder is dispersed and mixed in rubber or resin has been put to practical use as a radio wave absorber. These composite magnetic sheets are known to have a high magnetic permeability in order to obtain high radio wave absorption performance.
As a magnetic material used for these composite magnetic sheets, a flattened metal magnetic powder is often used. The reason for using the flattened magnetic filler is that by arranging the fillers in a certain direction, it is considered that the magnetic permeability can be increased because the demagnetizing field coefficient in that direction can be reduced, This is because such a result is actually shown. The reason for the metal magnetic powder is that it can be flattened by an attritor or a ball mill. With ceramic powders such as ferrite, the particles are shattered and cannot be flattened.

  Among the above-mentioned radio wave absorbers, there are those using a magnetic material and those using a dielectric compounded with carbon. In radio wave absorbers, the permittivity as well as the permeability affects the reflection coefficient of the electromagnetic interface and the wavelength inside the absorber, so it is necessary to lower the dielectric constant of ferrite for the purpose of obtaining desired characteristics There is. In such a situation, as a method of lowering the apparent dielectric constant without relatively lowering the magnetic permeability, a porous magnetic material is used, or a material impregnated with resin or glass is used to improve strength. It has been proposed (for example, Patent Document 1). Patent Document 1 forms a blended magnetic material for a magnetic sintered body in which a magnetic material, a binder, and a burned-out material having a spherical or granular shape and having an adhesive property to the binder are formed. After firing the sinter to form a magnetic sintered body containing 10 to 80% by volume of pores, the pores of the magnetic sintered body are filled with resin or glass, thereby realizing a low dielectric constant and water absorption. Low and secures mechanical strength.

JP 2004-146801 A

The composite magnetic material disclosed in Patent Document 1 is exclusively assumed to be a radio wave absorber, and a ceramic green sheet with a thickness of about 100 μm produced by a doctor blade method is laminated to a thickness of about 2 mm and fired. ing. Such a thickness can be sufficiently fired, but there is a demand for a composite magnetic material having a thin thickness of, for example, 100 μm or less, and it is not easy to obtain a healthy porous material at such a thickness. . Moreover, even if it can be fired, the flexibility is insufficient and handling is not easy.
The present invention has been made based on such a technical problem, and provides a technique for easily producing a composite porous body having a thin thickness and excellent in flexibility composed of a porous body impregnated with a resin. The purpose is to do.

  In order to achieve the above-mentioned object, the present inventors examined the formation of a porous body on a metal foil. This is because the metal foil becomes a support and it is easy to obtain a porous body. In particular, if the porous body is bonded onto the metal foil, the flexibility of the metal foil and the porous body can be ensured by the flexibility of the metal foil. However, it was difficult to join the ferrite particles constituting the porous body and the metal foil, and it was confirmed that the porous body was easily peeled from the metal foil. Therefore, when the metal foil was oxidized so as to enable the joining of the ferrite particles and the metal foil, the metal foil and the porous body could be secured by undergoing a firing step for obtaining the porous body. . The present invention is based on the above findings, and includes a first conductive metal substrate and an oxide particle structure including a group of oxide particles and having pores communicating with the outside. The structure is a composite porous body that is bonded to the first conductive metal substrate through an oxide film formed on the surface of the first conductive metal substrate.

In the composite porous body of the present invention, the pores of the oxide particle structure are preferably filled with a resin. This is for improving the flexibility of the composite porous body.
Moreover, in the composite porous body of the present invention, the oxide particle structure preferably has a porosity of 20 to 80%. This is because the oxide particle structure has predetermined characteristics and has flexibility as a composite porous body.

In the composite porous body of the present invention, various materials can be used as the oxide particles, and not only a magnetic material but also a dielectric material can be used.
In the composite porous body of the present invention, the second conductive metal substrate can be bonded to the back side of the oxide particle structure to which the first conductive metal substrate is bonded. The first conductive metal substrate and / or the second conductive metal substrate can be composed of a base metal such as Ni or Cu. The base metal is preferably in the form of a foil. The composite porous body of the present invention preferably has a thickness of 0.2 mm or less, and a foil is preferably used for producing such a thin composite porous body.

  A preferred method for producing the composite porous body of the present invention includes a step (a) of laminating a raw material composition containing oxide particles and a binder resin on a conductive metal substrate to produce a laminate, and removing the binder resin. A step (b) of heat-treating the laminate in an oxidizing atmosphere, and a step of joining oxide particles by heating to obtain an oxide particle structure having pores communicating with the outside ( c) and a step (d) of filling the pores of the oxide particle structure with a resin.

The raw material composition of the present invention preferably contains a resin powder effective for forming pores. This resin powder is removed in the step (b).
In the present invention, the step (b) is preferably heated and maintained at 300 to 600 ° C, and the step (c) is preferably heated and maintained at 600 to 1200 ° C.
In step (d), the pores of the oxide particle structure can be filled with the resin by applying pressure while heating the resin particle structure in contact with the resin body.

  ADVANTAGE OF THE INVENTION According to this invention, the composite porous body excellent in flexibility which consists of a porous body with thin thickness and impregnated with resin can be manufactured easily.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
<Composition of composite porous body>
FIG. 1 is a cross-sectional view showing a schematic configuration of a composite porous body 10 in the present embodiment.
As shown in FIG. 1, the composite porous body 10 has a structure in which a metal foil 4 and a porous body 1 are laminated. The porous body 1 is composed of an oxide particle structure 2 and a resin phase 3.

  The oxide particle structure 2 has a structure in which a plurality of oxide particles OP are joined to each other. That is, the oxide particle structure 2 has a path in which the oxide particles OP are continuous. As will be described in detail later, the joining of the oxide particles OP can be obtained by heating and holding at a predetermined temperature. This heating and holding is performed under mild conditions as compared with the firing in which a dense sintered body is obtained from the oxide particles OP. Minor conditions include the case where the heating temperature is low or the holding time is short. The oxide particle structure 2 is a porous body having open pores communicating with the outside. However, when viewed microscopically, the existence of closed pores is not denied. The porosity of the oxide particle structure 2 is preferably 20 to 80 vol% (volume%). If the porosity is less than 20 vol%, the amount of resin filled in the pores is insufficient, and it becomes difficult to impart sufficient flexibility to the composite porous body 10. On the other hand, if the porosity exceeds 80 vol%, the amount of the oxide particles OP is insufficient, and it becomes difficult to obtain desired physical characteristics. A more preferable porosity is 25 to 70 vol%, and a further preferable porosity is 30 to 65 vol%.

  The resin phase 3 is composed of a resin material filled in the pores of the oxide particle structure 2. The resin material can be filled in the pores of the oxide particle structure 2 by impregnation. Since the pores of the oxide particle structure 2 are open pores, the resin material filled therein forms a continuous path within the oxide particle structure 2.

  By the way, as a composite material having flexibility, for example, a material in which high magnetic permeability oxide magnetic particles (filler) are dispersed in a resin is known. In this composite material, the magnetic oxide particles are dispersed in the resin, and the non-magnetic material resin is present between most of the oxide magnetic particles, so the magnetic permeability of the oxide magnetic particles cannot be utilized. Will have a low magnetic permeability. The same applies to a composite material in which oxide particles OP, which is a high dielectric material, are dispersed in a resin. In order to reduce the demagnetizing factor, it is conceivable to use metal magnetic particles having a high magnetic permeability, but the insulation in the composite material is lowered, which makes it difficult to use practically. Further, it is conceivable to increase the permeability of the composite material by increasing the filling amount of the oxide magnetic particles. However, the material itself becomes fragile, causing defects during the process due to cracks and the like. Therefore, there is a limit to increasing the filling amount.

On the other hand, the composite porous body 10 according to the present embodiment includes the oxide particle structure 2 in which the oxide particles OP are joined and have a continuous path. Permeability can be increased.
In addition, it is difficult to achieve flexibility only with the oxide particle structure 2, but it is possible to give a predetermined flexibility by filling the pores with resin. Forming the porous body 1 on the metal foil 4 as the first conductive metal substrate also contributes to the flexibility, particularly the flexibility required during the manufacturing process. This point will be further described in the description of the method for manufacturing the composite porous body 10 described later.

(Oxide particles OP)
The oxide particles OP can be composed of a magnetic material or a dielectric material.
Magnetic materials include Ni—Zn, Mg—Zn, Mn—Zn, Cu—Zn, Cu—Zn—Mg, Mn—Mg, Mn—Mg—Zn, and Ni—Cu—Zn. It can be made of a known ferrite material such as ferrite or hexagonal ferrite suitable for use at high frequencies.
As dielectrics, Al ₂ O ₃ , SiO ₂ , MgO, MgO · SiO ₂ , 2MgO · SiO ₂ , TiO ₂ , BaTiO ₃ , Ba _x Sr _1-x TiO ₃ , SrTiO ₃ , CaTiO ₃ , PbZr _x A composite oxide having a perovskite structure such as Ti _1-x , Pb _1-x La _y ZrTi _1-x O ₃ , SrBi ₂ TaO ₃ , or other ferroelectric materials can be used. Further, MgTiO ₃ , Ba (Mg _1/3 Ta _2/3 ) O ₃ , Ba (Zn _1/3 Ta _2/3 ) O ₃ , Ba (Ni _1/3 Ta _2/3 ), Ba (Co _{1 / 3 Ta 2/3), BaNd 2 Ti} 4 O 12, Ba 2 Ti 9 O 20, LaAlO 3, PrAlO 3, SmAlO 3, YAlO 3, GdAlO 3, DyAlO 3, ErAlO 3, Sr (Zn 1/3 Ta 2 _{/ 3} ) O ₃ , Sr (Ni _1/3 Ta _2/3 ) O ₃ , Sr (Co _1/3 Ta _2/3 ) O ₃ , Sr (Mg _1/3 Ta _2/3 ) O ₃ , Sr ( Ca _1/3 Ta _2/3 ) O ₃ , Ba ₂ Ti ₉ O ₂₀ , Ba (Co _1/3 Nb _2/3 ) O _3, or the like can be used.
The above oxide particles OP preferably have a particle size in the range of 0.1 to 10 μm, and more preferably in the range of 0.3 to 3 μm. The content of the oxide particles OP is preferably in the range of 20 to 80 vol%, more preferably 30 to 75 vol%, when the total of the filler resin and the oxide particles OP described later is 100 vol%. Preferably, it is 35 to 70 vol%.

(Filling resin)
As the resin filled in the pores of the oxide particle structure 2, both thermoplastic resin and thermosetting resin can be used. Specifically, epoxy resin, phenol resin, vinyl benzyl ether compound resin , Bismaleimide triazine resins, cyanate ester resins, polyimides, polyolefin resins, polyesters, polyphenylene oxides, liquid crystal polymers, silicone resins, fluorine resins, etc., as long as they are contained alone or at least one kind or more. . Moreover, it is needless to say that the above-mentioned materials can be used in the case of constituting a sheet or film as the form of the composite porous body 10, but other than that, a rubber material such as acrylic rubber or ethylene acrylic rubber or a rubber component is used. It may be a resin material that partially contains. The resin to be filled does not necessarily need to be liquid, and any resin that melts by heating can be used. Resins that are difficult to dissolve in solvents, such as high heat resistance resins called super engineering plastics, can also be used. As described above, according to the present invention, since there are a wide range of choices of the resin to be filled, various characteristics such as improvement in heat resistance can be dealt with.

(Metal foil 4)
As the metal foil 4 as the first conductive metal substrate, a copper foil, a nickel foil, an aluminum foil, a gold foil, an alloy foil containing a plurality of these metal elements, and a clad foil of these and other metals can be used. . Here, the clad foil is a foil in which a dissimilar material metal is bonded together, for example, a copper foil in which nickel is bonded. The clad foil may be combined with any metal as long as it can be bonded. Although the present invention can use a foil made of a noble metal such as gold, it is preferable to use a base metal in terms of cost. The foil may be produced by electrolysis or produced by rolling. The thickness of the metal foil 4 is generally 500 μm or less, but is preferably 100 μm or less, particularly 50 μm or less in order to obtain a thin composite porous body 10. Metal foil 4 according to the present embodiment has an oxide film formed on the surface thereof. Due to the presence of the oxide film, it is possible to ensure the bonding force with the porous body body 1 made of an oxide. The metal foil 4 can function as a conductive path when the composite porous body 10 is used as an electronic component.

  In the composite porous body 10, the second conductive metal substrate can be disposed on the surface of the oxide particle structure 2 where the metal foil 4 is not disposed. The second conductive metal substrate may be affixed with a metal foil 4 or may be a metal film formed by a thin film formation process such as plating, sputtering, or vapor deposition. As the metal film, the same film as the metal foil 4 can be used. As the metal film, a metal film formed by plating, sputtering, vapor deposition, CVD, firing with metal nano paste, or the like is used. Examples of the metal film formed by plating include copper, nickel, gold, silver, tin, and alloys containing them. Examples of the metal film formed by sputtering include copper, nickel, gold, silver, aluminum, tungsten, molybdenum, chromium, titanium, tin, and alloys containing them. Examples of the metal film formed by vapor deposition include copper, nickel, gold, silver, aluminum, tungsten, molybdenum, chromium, titanium, and tin. Examples of the metal film formed by CVD include copper, nickel, gold, and the like and alloys containing them. Examples of the metal film formed by firing with the metal nanopaste include silver, copper, and gold. This firing is preferably performed at a temperature at which the resin impregnated with highly active nanoparticles at a low temperature does not decompose (for example, about 200 ° C.).

<Method for producing composite porous body 10>
Next, the manufacturing method of the composite porous body 10 comprised as mentioned above is demonstrated. FIG. 2 is a diagram illustrating a manufacturing process of the composite porous body 10.
(Paint preparation)
First, the oxide particle structure 2, the binder resin, and the resin powder are dissolved and dispersed in a solvent to prepare a paint. Here, the resin powder is for forming pores in the oxide particle structure 2, as will be described later, and the addition amount and particle size are appropriately determined depending on the porosity to be produced. However, the resin powder is not an essential element in the present invention, and pores can be formed in the oxide particle structure 2 without the resin powder by appropriately controlling the heating conditions. A dispersant, a plasticizer, etc. may be added to the paint.

Here, the resin powder only needs to be decomposable at the time of firing described later, and is composed of, for example, crosslinked polystyrene, crosslinked acryl, crosslinked methyl methacrylate, nylon or the like. Moreover, the resin powder should just have solvent resistance of the grade which does not melt | dissolve in the solvent to be used in the coating-material raw material containing oxide particle OP and binder resin. Such resin powder may be hollow.
The method for producing the paint is the same as that for producing a paint for producing a green sheet used for producing a general ceramic substrate. The paint is produced using a paint producing apparatus. As the coating material preparation device, a general device such as a ball mill or a bead mill can be used.

(Coating)
Next, using a known method such as a doctor blade method, a gravure printing method, a screen printing method or the like, the prepared paint is applied and dried on the metal foil 4 to form a coating film 5 on the metal foil 4. To do.

(Binder removal)
Subsequently, a binder removal process is performed on the sheet on which the coating film 5 is formed on the metal foil 4. The binder removal is performed to remove the binder resin and resin powder contained in the coating film 5. The present embodiment is characterized in that this binder removal treatment is performed in an oxidizing atmosphere to oxidize the metal foil 4. This is to promote the bonding between the metal foil 4 and the oxide particle structure 2 in the particle bonding process as the next step. However, it is preferable that the oxidizing atmosphere has a degree that the surface layer portion of the metal foil 4 is oxidized. This is because the metal foil 4 is used as a conductive layer. Examples of the oxidizing atmosphere include air, an inert gas containing oxygen having a predetermined partial pressure, and the like. The binder removal may be maintained at a temperature of about 300 to 600 ° C. for a predetermined time. In addition, it is preferable to implement a binder removal in the temperature rising process of the particle joining process which is the next process. Further, by removing the binder resin and the resin powder, voids (open holes) are formed between the oxide particles OP.

(Particle bonding process)
After the binder removal, a process for bonding the oxide particles OP (particle bonding process) is performed. The temperature and atmosphere of the particle bonding process are performed under conditions suitable for the materials to be bonded. A general processing temperature is 600 to 1200 ° C. The atmosphere for the particle bonding treatment is preferably an atmosphere in which the metal foil 4 is not oxidized. For example, an inert gas atmosphere such as a nitrogen gas atmosphere or an argon gas atmosphere may be used.
In this particle bonding process, the oxide particle structure 2 is formed on the metal foil 4 when the oxide particles OP react with each other in the contact region. In this oxide particle structure 2, vacancies formed between the oxide particles OP by the binder removal remain.

As the particle bonding treatment conditions, it should be avoided that the oxide particles OP completely diffuse and react with each other, and it is sufficient that the reaction is such that the oxide particles OP can form a continuum. That is, the condition may be such that the growth of the neck between the oxide particles OP is started. Needless to say, a glass component may be added to promote the particle bonding process. By using the glass component, the temperature of the particle bonding process can be lowered or the processing time can be shortened. As the glass component, either a crystallized glass or an amorphous glass can be used as long as it is a general glass. Examples thereof include those containing SiO ₂ , Al ₂ O ₃ , RO (R is Mg, Ca, Sr, Ba), specifically, SiO ₂ —BaO series, SiO ₂ —Al ₂ O ₃ —BaO. , SiO ₂ —Al ₂ O ₃ —BaO—B ₂ O ₃ system, SiO ₂ —Al ₂ O ₃ —BaO—ZnO—B ₂ O ₃ system glass, Bi glass, and glass containing them as a main component Etc. are available.

By the way, in this Embodiment, a particle joining process is performed on the metal foil 4. FIG. The behavior of the oxide particles OP during the particle bonding process will be described with reference to FIG.
FIG. 3 schematically shows the state in the vicinity of the metal foil 4 before (upper stage) and after (lower stage) the particle bonding process. A large number of oxide particles OP are present on the metal foil 4. On the upper surface (front surface) of the metal foil 4, there is an oxide film OL formed by a binder removal process, and the lowermost oxide particle OP is in contact with the metal foil 4 through the oxide film OL. . In this state, when the particle bonding process, that is, heating and holding at a predetermined temperature, the oxide particles OP react with each other, so that the occupied volume decreases. This is so-called contraction. In normal firing, this shrinkage is isotropic. However, in the case of the present embodiment, the shrinkage in the direction parallel to the metal foil 4 (arrow X in the figure) is smaller than the shrinkage in the direction perpendicular to the metal foil 4 (arrow Z in the figure). This is because the oxide particles OP in contact with the metal foil 4 are bonded to the oxide film OL existing on the surface of the metal foil 4 by heating and holding at a predetermined temperature, and contract in a direction parallel to the metal foil 4. Is limited. When the temperature for heating and holding is increased, shrinkage proceeds in a direction parallel to the metal foil 4, so that the oxide particle structure 2 is cracked. In order to prevent this crack, as described above, the heating conditions in the particle bonding process are slight. Although it varies depending on the heating holding time, as one criterion, if the holding temperature for obtaining a dense sintered body is T ₁ (° C.) and the holding temperature in the particle bonding process is T ₂ (° C.), T ₂ = (0.7 to 0.9) T ₁ is preferable. Holding temperature _{T 2} in a further preferred particle bonding process _{is T 2 = (0.75~0.85) T 1} .

  In the present embodiment, as described above, the oxide particle structure 2 and the metal foil 4 are bonded via the oxide film OL formed on the surface of the metal foil 4 through the particle bonding process. The Therefore, the flexibility of the oxide particle structure 2 in the subsequent manufacturing process can be improved and the handling property can be ensured. In general, since cracks often occur during the firing process, it is difficult to produce a thin porous body by firing. However, in this embodiment, in order to form the oxide particle structure 2 using the metal foil 4 as a support and to bond the oxide particles OP under conditions that are lighter than normal firing, 0.2 mm or less. In particular, a thin composite porous body 10 having a thickness of 0.1 mm or less can be produced.

(Resin film lamination)
Next, the resin film 6 is laminated on the oxide particle structure 2. The resin film 6 only needs to be made of a resin that can be impregnated into the pores of the oxide particle structure 2. A thermoplastic resin is used. The resin film 6 may be a resin in which a small amount of thermoplastic resin is mixed with a thermosetting resin, and these resins are blended with various dispersants, plasticizers, flame retardants, additives and the like. There may be.

(Resin impregnation)
In a state where the resin film 6 is laminated on the oxide particle structure 2, the resin film 6 is pressurized while being heated. By this treatment, the resin film 6 is melted and the melted resin is impregnated in the pores of the oxide particle structure 2. This treatment can be performed by, for example, a heat press or a heat lamination. Although this treatment can be performed in the air, it is preferably performed in a vacuum in order to facilitate impregnation of the oxide particle structure 2 with a resin. As heating conditions, it is performed at a temperature at which the resin film 6 is cured or melted. As a temperature at which the resin film 6 is cured or melted, a condition of about 100 to 400 ° C. can be considered.

  The composite porous body 10 shown in FIG. 1 can be produced through the above steps. In the composite porous body 10 manufactured in this manner, since the oxide particles OP are continuous, there is no resin having a low magnetic permeability or a low dielectric constant between the oxide particles OP, and the magnetic permeability is increased or the dielectric is increased. Increase in efficiency.

  The manufacturing method of the composite porous body 10 is not limited to the above embodiment, and various methods can be applied. For example, in the above-described embodiment, the oxide particles OP, the binder resin, and the resin powder are dissolved and dispersed in a solvent to prepare a paint, but the resin powder may not be added.

  The composite porous body 10 has a form in which the metal foil 4 is disposed only on one surface side of the oxide particle structure 2, but as shown in FIG. A composite porous body 20 in which a metal foil 4 as a first conductive metal substrate and a metal foil 71 as a second conductive metal substrate are disposed on the mass surface can also be used. This composite porous body 20 is formed by laminating a resin film-bonded metal foil 7 in which a resin film 72 is bonded to a metal foil 71 instead of the resin film 6 shown in FIG. It can obtain by performing the resin impregnation process which heats and pressurizes similarly to.

  In addition, as shown in FIG. 5, two sheets prepared with the oxide particle structure 2 are prepared on the metal foil 4 shown in FIG. 2, and arranged so that the oxide particle structure 2 faces each other. Between the two, a B-stage state or impregnated resin film 6 before complete curing may be disposed and pressurized while being heated. In this case, as shown in FIG. 5, the composite porous body 30 in which the oxide particle structure 2 having a thickness of two layers is arranged can be produced.

When the oxide particles OP of the composite porous body 10 are made of magnetic ferrite, the dielectric constant can be lowered because the pores of the oxide particle structure 2 are filled with resin. Further, it is possible to increase the dielectric constant by dispersing particles made of a high dielectric material in the resin, and the dielectric characteristics can be controlled by the design of the filling resin. The dielectric filler added to the impregnating resin may be any particle size that is not more than the shape of the pores, and is selected according to the desired dielectric properties. For example, when the dielectric constant is increased, TiO ₂ , BaTiO ₃ , Ba _x Sr _1-x TiO ₃ , SrTiO ₃ , and CaTiO ₃ having a high dielectric constant and a dielectric constant of 100 or more are used alone or as a main component. And a composite oxide. In addition, the dielectric constant can be controlled by impregnating a dispersion and mixture of carbon.

Hereinafter, the present invention will be described based on specific examples.
<First embodiment>
Example 1
Polyvinyl resin (Sekisui Chemical Co., Ltd .: BH-S), cross-linked acrylic powder (manufactured by Soken Chemical Co., Ltd .: MX-150, average particle size 1.5 μm), magnetic ferrite particles (Fe ₂ O ₃ = 52) 0.6 mol%, MnO = 40.6 mol%, ZnO = 6.8 mol%) and glass powder (Asahi Glass Co., Ltd. product: LS-5, 2 parts by weight with respect to 100 parts by weight of the magnetic ferrite particles) were prepared. And it weighs and mixes so that the volume ratio of the crosslinked acrylic powder and the total of the magnetic ferrite particles and the glass powder is 50:50 (resin powder amount: 50 vol%), ethanol, toluene and DBP (phthalic acid). Dibutyl) and oleic acid were added to prepare a coating material as a raw material for the oxide particle structure. The magnetic ferrite particles used at this time were particles having an average particle diameter of 1.5 μm prepared by the spray pyrolysis method disclosed in Japanese Patent No. 3542319. Further, as a dispersion method at this time, a ball mill was used for dispersion for about 24 hours to obtain a paint.

  The coating material obtained above was applied and dried on an electrolytic nickel foil (Fukuda Metal Foil Powder Co., Ltd.) with a thickness of about 30 μm, and then cut into a 10 cm square sheet. The binder was removed from the sheet at 400 ° C. for 2 hours in the atmosphere. The surface of the electrolytic nickel foil is oxidized by the binder removal treatment in the atmosphere. Thereafter, the atmosphere was switched to a nitrogen atmosphere, and further a particle bonding treatment was performed by raising the temperature to 1050 ° C. at a rate of 200 ° C./h and holding for 1 hour. In FIG. 6, the image by the scanning electron microscope of the magnetic ferrite particle structure obtained by performing a particle joining process is shown. As shown in FIG. 6, it was confirmed that the magnetic ferrite particle structure has a path in which the magnetic ferrite particles are joined to each other and the magnetic ferrite particles are continuous. In addition, peeling between the electrolytic nickel foil and the magnetic ferrite particle structure was not observed (peeling: ◯).

  FIGS. 7 and 8 show images of the magnetic ferrite particle structure with a scanning electron microscope when the holding temperature of the particle bonding treatment is 1150 ° C. and 1200 ° C. FIG. As shown in FIG. 7A and FIG. 8A, it can be seen that cracks occur in the magnetic ferrite particle structure when the holding temperature increases. This is because, as described above, since the retention temperature was raised despite the contraction of the magnetic ferrite particles being constrained in the plane direction of the electrolytic nickel foil, the magnetic ferrite particles were separated from the plane of the electrolytic nickel foil. It is understood that the shrinkage progressed and the distortion occurred. Further, as can be seen by comparing FIG. 6B, FIG. 7B, and FIG. 8B, as the holding temperature increases, the reaction between the magnetic ferrite particles proceeds and the sintered state is obtained.

  B-stage vinylbenzyl resin membrane (Showa Polymer Co., Ltd .: ARS-068) is placed on an electrolytic copper foil (Furukawa Circuit Foil Co., Ltd .: F2-WS (thickness 18 μm)) with a thickness of 20 μm. A formed resin film-formed metal foil was prepared. This resin film-forming metal foil was laminated with the vinyl benzyl resin film facing the magnetic ferrite particle structure formed on the nickel foil. Subsequently, it heat-press-molded with the vacuum press machine. The pressing conditions are: pressure: 3 MPa, temperature: 195 ° C., pressurization time: 3 hours. By this heating press, the resin is impregnated into the magnetic ferrite particle structure and cured simultaneously. From the obtained composite porous body, a toroidal sample having an outer diameter of 7 mm and an inner diameter of 3 mm was punched, and after removing the metal foil by etching, the relative permeability μr (10 MHz) was measured by the coaxial tube method. The results are shown in Table 1. The volume occupied by the magnetic ferrite particles in this sample was measured and found to be 38 vol%. This suggests that the porosity of the magnetic ferrite particle structure is 62 vol%. Moreover, although flexibility was evaluated by fixing one end of the sample and bending the other end so that the deflection amount was 2 mm, the sample was not damaged (flexibility: ◯).

  FIG. 9 shows an image obtained by observing the laminated structure (cross section) of the obtained composite porous body with a scanning electron microscope. As shown in FIG. 9, in the composite porous body, the interface between the electrolytic nickel foil and the magnetic ferrite particle structure and the interface between the electrolytic copper foil and the magnetic ferrite particle structure have the same structure. Thus, the interface between the electrolytic nickel foil and the magnetic ferrite particle structure bonded before the particle bonding treatment and the interface between the electrolytic nickel foil and the magnetic ferrite particle structure bonded during the resin impregnation after the particle bonding treatment are both It was confirmed that the same level of adhesion was obtained.

(Example 2)
A sample was prepared in the same manner as in Example 1 except that the volume ratio of the crosslinked acrylic powder and the total of the magnetic ferrite particles and the glass powder was 30:70 (resin powder amount: 30 vol%). The relative magnetic permeability was measured in the same manner as in Example 1. The results are shown in Table 1. Further, in the same manner as in Example 1, peeling between the electrolytic nickel foil and the magnetic ferrite particle structure and evaluation of flexibility were performed. The results are also shown in Table 1.

(Example 3)
A sample was prepared in the same manner as in Example 2 except that the resin formed on the resin film-forming metal foil was a benzoxazine resin (manufactured by Shikoku Kasei Co., Ltd .: Fa type). Measurement was performed in the same manner as in Example 1. The results are shown in Table 1. Further, in the same manner as in Example 1, peeling between the electrolytic nickel foil and the magnetic ferrite particle structure and evaluation of flexibility were performed. The results are also shown in Table 1.

Example 4
The composition of the magnetic ferrite particles is Fe ₂ O ₃ = 48.7 mol%, MnO = 30.3 mol%, ZnO = 20 mol%, TiO ₂ = 1 mol%, and the cross-linked acrylic powder and magnetic properties are added without adding glass particles. A sample was prepared in the same manner as in Example 1 except that the volume ratio of the ferrite particles was 30:70 (resin powder amount: 30 vol%), and the relative permeability of the sample was measured in the same manner as in Example 1. The results are shown in Table 1. Further, in the same manner as in Example 1, peeling between the electrolytic nickel foil and the magnetic ferrite particle structure and evaluation of flexibility were performed. The results are also shown in Table 1. Furthermore, the image by the scanning electron microscope of the magnetic ferrite particle structure obtained by performing a particle joining process in FIG. 10 is shown. As shown in FIG. 10, it was confirmed that the magnetic ferrite particle structure has a path in which the magnetic ferrite particles are joined to each other and the magnetic ferrite particles are continuous.

(Comparative Example 1)
The magnetic ferrite particles (Fe ₂ O ₃ = 52.6 mol%, MnO = 40.6 mol%, ZnO = 6.8 mol) used in Example 1 were added to vinyl benzyl resin (manufactured by Showa Polymer Co., Ltd .: ARS-068). %) Was prepared so that the volume of the filler consisting of 38% by volume was the same as the volume occupied by the magnetic ferrite particles in Example 1. This slurry solution was mixed and dispersed in a ball mill for 48 hours. This slurry was applied on the copper foil used in Example 1 to a thickness of about 30 μm and dried. The obtained sheet with copper foil was laminated so that the roughened surfaces of the copper foil faced, and heated and pressed under the same conditions as in Example 1 with a vacuum press. From the obtained composite, a sample was prepared in the same manner as in Example 1, and the relative permeability μr (10 MHz) was measured. The results are shown in Table 1.

(Comparative Example 2)
The particle bonding process was performed in the same manner as in Example 2 except that the binder removal was performed in a nitrogen atmosphere. Separation of the metal foil, magnetic ferrite particle structure, and copper foil was observed. The results are shown in Table 1.

  As shown in Table 1, Example 1 according to the present invention has higher magnetic permeability than Comparative Example 1 even if the occupied volume of magnetic ferrite particles is equal. Further, when the binder is removed in a nitrogen atmosphere, an oxide film is not formed on the surface of the electrolytic nickel foil, so that the magnetic ferrite particle structure cannot be sufficiently bonded to the electrolytic nickel foil, and peeling occurs. Moreover, the composite porous body of Examples 1-4 by this invention has the flexibility more than a sintered compact.

<Second embodiment>
(Example 5)
Polyvinyl resin (manufactured by Sekisui Chemical Co., Ltd .: BH-S) and cross-linked acrylic powder (manufactured by Soken Chemical Co., Ltd .: MX-150), dielectric particles (manufactured by Kyoritsu Material Co., Ltd .: Y5V-F3, dielectric) The body particles A) are weighed so that the volume ratio of the resin powder to the dielectric particles is 60:40 (resin powder amount: 60 vol%), and ethanol, toluene, DBP (dibutyl phthalate) and oleic acid are added. A coating material was added to be a raw material for the oxide particle structure. As a dispersion method at this time, a ball mill was used and dispersed for about 24 hours to obtain a paint.

  The coating material obtained as described above was applied onto an electrolytic nickel foil (manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.) with a thickness of about 20 μm, and then cut into a 10 cm square sheet. The binder was removed from the sheet at 400 ° C. for 2 hours in the atmosphere. The surface of the electrolytic nickel foil is oxidized by the binder removal treatment in the atmosphere. Thereafter, the atmosphere was switched to a nitrogen atmosphere, and further a particle bonding treatment was performed in which the temperature was raised to 1100 ° C. at a rate of 200 ° C./h and held for 1 hour. FIG. 11 shows an image of a dielectric particle structure obtained by performing the particle bonding process, using a scanning electron microscope. As shown in FIG. 11, it was confirmed that the dielectric particle structure has a path in which the dielectric particles are joined to each other and the dielectric particles are continuous. Note that peeling between the electrolytic nickel foil and the dielectric particle structure was not observed (peeling: ◯).

  B-stage vinylbenzyl resin membrane (Showa Polymer Co., Ltd .: ARS-068) is placed on an electrolytic copper foil (Furukawa Circuit Foil Co., Ltd .: F2-WS (thickness 18 μm)) with a thickness of 20 μm. A formed resin film-formed metal foil was prepared. This resin film-forming metal foil was laminated so that the vinylbenzyl resin film was opposed to the dielectric particle structure formed on the nickel foil. Subsequently, it heat-press-molded with the vacuum press machine. The pressing conditions are: pressure: 3 MPa, temperature: 195 ° C., pressurization time: 3 hours. By this heating press, impregnation and curing of the resin particle structure are simultaneously performed. A single plate capacitor having a size of 5 mm square and a dielectric layer thickness of about 20 μm was prepared from the obtained composite porous body, the capacitance was measured by the capacitance method, and the dielectric constant was calculated from the thickness and area. The capacity measuring instrument was Agilent Technologies 4275A, and the measurement was performed at a measurement frequency of 1 MHz. The results are shown in Table 2. When the volume occupied by the dielectric particles in this sample was measured, it was 38 vol%. Moreover, although flexibility was evaluated by fixing one end of the sample and bending the other end so that the deflection amount was 2 mm, the sample was not damaged (flexibility: ◯).

(Example 6)
A sample was prepared in the same manner as in Example 4 except that the volume ratio of the crosslinked acrylic powder and dielectric particles was 40:60 (resin powder amount: 40 vol%), and the dielectric constant was the same as in Example 5. It was measured. The results are shown in Table 2. Further, in the same manner as in Example 4, peeling between the electrolytic nickel foil and the dielectric particle structure and evaluation of flexibility were performed. The results are also shown in Table 2.

(Example 7)
A sample was prepared in the same manner as in Example 5 except that the volume ratio of the crosslinked acrylic powder and dielectric particles was 20:80 (resin powder amount: 20 vol%), and the dielectric constant was the same as in Example 5. It was measured. The results are shown in Table 2. Further, in the same manner as in Example 5, peeling between the electrolytic nickel foil and the dielectric particle structure and evaluation of flexibility were performed. The results are also shown in Table 2.

(Example 8)
A sample was prepared in the same manner as in Example 5 except that the crosslinked acrylic powder was not added, and the dielectric constant was measured in the same manner as in Example 5. The results are shown in Table 2. Further, in the same manner as in Example 5, peeling between the electrolytic nickel foil and the dielectric particle structure and evaluation of flexibility were performed. The results are also shown in Table 2.

Example 9
The dielectric particles are barium titanate (average particle diameter D50 = 0.97 μm, dielectric particles B) prepared by the oxalate method, and the volume ratio of the resin powder to the dielectric particles is 50:50 (resin powder). A sample was prepared in the same manner as in Example 5 except that the body weight was 50 vol%), and the dielectric constant was measured in the same manner as in Example 5. The results are shown in Table 2. Further, in the same manner as in Example 5, peeling between the electrolytic nickel foil and the dielectric particle structure and evaluation of flexibility were performed. The results are also shown in Table 2.

(Example 10)
The dielectric particles are barium titanate (average particle diameter D50 = 0.97 μm, dielectric particles B) prepared by the oxalate method, and the volume ratio of the resin powder to the dielectric particles is 30:70 (resin powder). A sample was prepared in the same manner as in Example 5 except that the body weight was set to 30 vol%, and the dielectric constant was measured in the same manner as in Example 5. The results are shown in Table 2. Further, in the same manner as in Example 5, peeling between the electrolytic nickel foil and the dielectric particle structure and evaluation of flexibility were performed. The results are also shown in Table 2.

(Example 11)
A sample was prepared in the same manner as in Example 5 except that the dielectric particles were barium titanate (average particle diameter D50 = 2.64 μm, dielectric particles C) prepared by the oxalate method. Was measured in the same manner as in Example 5. The results are shown in Table 2. Further, in the same manner as in Example 5, peeling between the electrolytic nickel foil and the dielectric particle structure and evaluation of flexibility were performed. The results are also shown in Table 2.
In FIG. 12, the image by the scanning electron microscope of the dielectric material particle structure obtained by performing a particle joining process is shown. As shown in FIG. 12, it was confirmed that the dielectric particle structure has a path in which the dielectric particles are joined to each other and the dielectric particles are continuous.

(Comparative Example 3)
40 vol% (resin amount 60 vol) of the same dielectric particles A (made by Kyoritsu Material Co., Ltd .: Y5V-F3) used in Example 4 on vinylbenzyl resin (Showa High Polymer Co., Ltd .: ARS-068). %) Was prepared. This slurry solution was mixed with a ball mill (48 hours) and dispersed on a 18 μm thick copper foil (Furukawa Circuit Foil Co., Ltd .: F2-WS, 18 μm thickness) using a coating machine. Was coated to a thickness of about 20 μm, and a sheet with copper foil was prepared at a speed of 0.25 m / m and at a drying temperature of 120 ° C.
This sheet with copper foil was set so that the roughened surfaces of the copper foil (Furukawa Circuit Foil Co., Ltd .: F2-WS, 18 μm thick) face each other, pressure: 3 MPa, temperature: 195 ° C. by a vacuum press. Pressurization time: Heat pressing was performed under the condition of 3 hours, and a sample was prepared in the same manner as in Example 5. The dielectric constant was measured in the same manner as in Example 4. The results are shown in Table 2. Further, flexibility was evaluated in the same manner as in Example 5. The results are also shown in Table 2.

(Comparative Example 4)
A sample was prepared in the same manner as in Comparative Example 3 except that the amount of dielectric particles was 60 vol% (resin amount 40 vol%), and the dielectric constant was measured in the same manner as in Example 5. The results are shown in Table 2. Further, in the same manner as in Example 5, peeling between the electrolytic nickel foil and the dielectric particle structure and evaluation of flexibility were performed. The results are also shown in Table 2.
(Comparative Example 5)
A sample was prepared in the same manner as in Example 9 except that the binder removal treatment was performed in a nitrogen atmosphere. As shown in Table 2, since peeling from the metal foil occurred, measurement of the resin impregnation and dielectric constant was performed. Could not do.
(Comparative Example 6)
A sample was prepared in the same manner as in Example 10 except that the binder removal treatment was performed in a nitrogen atmosphere. As shown in Table 2, since peeling from the metal foil occurred, measurement of the resin impregnation and dielectric constant was performed. Could not do.

As shown in Table 2, it was confirmed that in any of Examples 5 to 11, a higher dielectric constant was obtained compared to the comparative example in which the same dielectric material was dispersed in the resin. Further, as shown in Examples 5 to 7, it was confirmed that the dielectric constant could be controlled by changing the amount of the resin powder. As shown in Example 8, it was confirmed that a high dielectric constant could be obtained without using resin powder.
Further, when the binder removal is performed in a nitrogen atmosphere, an oxide film is not formed on the surface of the electrolytic nickel foil, so that the magnetic ferrite particle structure cannot be sufficiently bonded to the electrolytic nickel foil, and peeling occurs. Moreover, the composite porous body of Examples 5-11 by this invention has flexibility more than a sintered compact.

  FIG. 13 shows images obtained by observing the surfaces of the composite porous bodies obtained in Examples 5 to 8 with a transmission electron microscope. FIG. 13 shows that the resin can be impregnated and filled in the oxide particle structure shown in white without adding resin powder. Further, FIG. 13 shows that as the amount of resin powder increases, the porosity increases and the amount of resin (gray) to be filled increases.

It is sectional drawing which shows schematic structure of the composite porous body in this Embodiment. It is a figure which shows the manufacturing process of the composite porous body in this Embodiment. It is a figure which shows typically the manufacturing process of the oxide particle structure in this Embodiment. It is sectional drawing which shows schematic structure of the other composite porous body in this Embodiment. It is sectional drawing which shows schematic structure of the other composite porous body in this Embodiment. In Example 1, it is a figure which shows the image by the scanning electron microscope of the magnetic ferrite particle structure which carried out the particle joining process at 1050 degreeC. In Example 1, it is a figure which shows the image by the scanning electron microscope of the magnetic ferrite particle structure which carried out the particle joining process at 1150 degreeC. In Example 1, it is a figure which shows the image by the scanning electron microscope of the magnetic ferrite particle structure which carried out the particle joining process at 1200 degreeC. 2 is a diagram showing an image of a cross section of a composite porous body obtained in Example 1 by a scanning electron microscope. FIG. It is a figure which shows the image by the scanning electron microscope of the magnetic ferrite particle structure obtained in Example 4. FIG. The image by the scanning electron microscope of the dielectric material particle structure obtained by performing a particle | grain joining process in Example 5 is shown. The image by the scanning electron microscope of the dielectric material particle structure obtained by performing a particle | grain joining process in Example 11 is shown. It is a figure which shows the image which observed the surface of the composite porous body obtained in Example 5-Example 8 with the transmission electron microscope.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Porous body main body, 2 ... Oxide particle structure, 3 ... Resin phase, 4 ... Metal foil, 5 ... Coating film, 6 ... Resin film, 7 ... Resin film joining metal foil, 10, 20, 30 ... Composite porous Body, OP ... Oxide particles

Claims (14)

A first conductive metal substrate;
An oxide particle structure composed of a group of oxide particles and having pores communicating with the outside,
The composite porous body, wherein the oxide particle structure is bonded to the first conductive metal substrate through an oxide film formed on the surface of the first conductive metal substrate.   The composite porous body according to claim 1, wherein the pores of the oxide particle structure are filled with a resin.   The composite porous body according to claim 1 or 2, wherein the oxide particle structure has a porosity of 20 to 80%.   The composite porous body according to claim 1, wherein the oxide particles are made of a magnetic material.   The composite porous body according to claim 1, wherein the oxide particles are made of a dielectric.   The composite porous body according to any one of claims 1 to 5, wherein a second conductive metal substrate is bonded to a back surface side of the oxide particle structure to which the first conductive metal substrate is bonded. body.   The composite porous body according to any one of claims 1 to 6, wherein the first conductive metal substrate and / or the second conductive metal substrate is made of a base metal.   The composite porous body according to any one of claims 1 to 7, wherein the first conductive metal substrate and / or the second conductive metal substrate is composed of a base metal foil.   The composite porous body according to any one of claims 1 to 8, wherein the thickness is 0.2 mm or less. A step (a) of stacking a raw material composition containing oxide particles and a binder resin on a conductive metal substrate to produce a laminate;
(B) heat-treating the laminate in an oxidizing atmosphere to remove the binder resin;
(C) a step of obtaining an oxide particle structure having pores communicating with the outside by joining the oxide particles by heating;
Filling the pores of the oxide particle structure with resin (d);
A method for producing a composite porous body comprising: The raw material composition includes a resin powder,
The method for producing a composite porous body according to claim 10, wherein the resin powder is also removed in the step (b).   The said process (b) heat-holds at 300-600 degreeC, The manufacturing method of the composite porous body of Claim 10 or 11 characterized by the above-mentioned.   The said process (c) heat-holds at 600-1200 degreeC, The manufacturing method of the composite porous body in any one of Claims 10-12 characterized by the above-mentioned.   The step (d) is characterized in that the pores of the oxide particle structure are filled with resin by applying pressure while heating in a state where the resin body is in contact with the oxide particle structure. The method for producing a composite porous body according to any one of claims 10 to 13.

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