JP2017149630A - Composite material, ceramic substrate, and particles for forming cavity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite material which can easily form uniform cavities in a ceramic substrate; to provide a ceramic substrate that is formed of the composite material; to provide a method for producing a ceramic substrate; and to provide particles for forming a cavity.SOLUTION: The composite material includes organic-inorganic composite particles and ceramic particles. In the composite material, the organic-inorganic composite particles have a core-shell structure formed by a core including an organic resin and a shell including a metal oxide, a ceramic substrate includes, as a component, a sintered body of a layered body of a ceramic green sheet including the composite material, and cavities are formed in the sintered body. In the composite material, the organic resin has a thermal decomposition temperature of 270 to less than 500°C under nitrogen atmosphere, and the organic-inorganic composite particles have a number average particle diameter of 0.1-5.0 μm and have an aspect ratio of 1.10 or less after heat treatment at 500°C under nitrogen atmosphere.SELECTED DRAWING: None

Description

  The present invention relates to a composite material, a ceramic substrate and pore forming particles.

  Conventionally, it is known that a computer circuit board is made of a ceramic base material that can be sintered at low temperature called LTCC (Low Temperature Co-fired Ceramics). In recent years, various ceramic base material forming materials that can be sintered at 1000 ° C. or lower, particularly 500 to 600 ° C. have been proposed (see, for example, Patent Document 1). Such a ceramic substrate is required to have characteristics of a lower dielectric constant and a lower dielectric loss in accordance with the higher frequency of electronic devices.

  Various techniques for lowering the dielectric constant of a ceramic substrate have been proposed, and as one of them, a method of forming pores inside the ceramic substrate is known. For example, Patent Document 2 discloses a method of expecting void formation inside a ceramic substrate with a gap due to ceramic fragments, and Patent Document 3 forms voids inside the ceramic substrate by containing hollow silica glass. Is disclosed.

International Publication No. 2014/196348 JP 2004-296544 A Japanese Patent Laid-Open No. 05-067854

  However, as in the technique disclosed in Patent Document 2, when the formation of holes is expected in the gap due to ceramic fragments, it is difficult to control the size of the holes, and uniform holes can be obtained. However, there was a problem that the strength of the ceramic substrate was lowered. In this case, it is also difficult to adjust the formed pores to be spherical, and there is a concern that the strength of the ceramic base material may be lowered. Furthermore, as in the technique disclosed in Patent Document 3, the technique of forming pores using hollow silica particles may cause the hollow silica particles to be destroyed when a ceramic substrate is obtained by firing. For this reason, it is difficult to obtain uniform pores in the ceramic substrate, resulting in a problem that the strength of the ceramic substrate is lowered. On the other hand, as another technique, attempts have been made to form pores using resin particles, but in this case, since the resin particles contracted during sintering, uniform pores could not be obtained. . In addition, since carbon (soot, etc.) derived from the resin may remain after sintering, there has been a problem that a separate deashing step is required to avoid the development of the conductivity of the ceramic base material. . As described above, since the uniformity, shape, carbon remaining, and the like of the holes formed in the ceramic base material are likely to affect the performance of the ceramic base material, further improvement has been demanded.

  The present invention has been made in view of the above, and a composite material capable of easily forming uniform pores in a ceramic substrate, a ceramic substrate formed by the composite material, a method for producing the same, and a void An object is to provide pore-forming particles.

  As a result of intensive studies to achieve the above object, the present inventor has found that the above object can be achieved by forming pores with organic-inorganic composite particles having a so-called core-shell structure, and to complete the present invention. It came.

That is, the present invention includes, for example, the subject matters described in the following sections.
Item 1. Including organic-inorganic composite particles and ceramic particles,
The organic-inorganic composite particle is a composite material having a core-shell structure formed of a core containing an organic resin and a shell containing a metal oxide.
Item 2. Item 2. The composite material according to Item 1, wherein the organic resin has a thermal decomposition temperature in a nitrogen atmosphere of 270 ° C or higher and lower than 500 ° C.
Item 3. Item 3. The composite material according to Item 1 or 2, wherein the organic-inorganic composite particles have a number average particle size of 0.1 μm or more and 5.0 μm or less.
Item 4. Item 4. The composite material according to any one of Items 1 to 3, wherein the organic-inorganic composite particle has an aspect ratio of 1.10 or less after heat treatment at 500 ° C in an atmosphere of nitrogen.
Item 5. Item 5. The composite material according to any one of Items 1 to 4, wherein the metal oxide contains silica.
Item 6. The ceramic base material which contains the sintered compact of the laminated body of the ceramic sheet containing the composite material of any one of said claim | item 1-5 as a component, and the void | hole is formed inside the said sintered compact. .
Item 7. A method for producing a ceramic substrate, comprising: a step of forming a ceramic sheet from the composite material according to any one of items 1 to 5; and a step of firing a laminate obtained by laminating the ceramic sheets.
Item 8. Pore-forming particles for forming pores in a ceramic substrate,
A pore-forming particle comprising organic-inorganic composite particles having a core-shell structure formed of a core containing an organic resin and a shell containing a metal oxide.
Item 9. Item 9. The pore forming particle according to Item 8, wherein the organic resin has a thermal decomposition temperature in a nitrogen atmosphere of 270 ° C or higher and lower than 500 ° C.
Item 10. Item 10. The pore forming particle according to Item 8 or 9, wherein the organic-inorganic composite particle has a number average particle size of 0.1 μm or more and 5.0 μm or less.
Item 11. The pore-forming particle according to any one of the above items 8 to 10, wherein the organic-inorganic composite particle has an aspect ratio of 1.10 or less after being heat-treated at 500 ° C. in a nitrogen atmosphere. .
Item 12. Item 12. The void forming particle according to any one of Items 8 to 11, wherein the metal oxide is silica.

  The composite material which concerns on this invention can form a uniform void | hole in a ceramic base material easily by containing the organic inorganic composite particle which acts as a pore formation agent of a ceramic base material. Therefore, the composite material is suitable as a material for forming a ceramic substrate having a lower dielectric constant and excellent strength. In addition, since the carbonized layer formed after firing the organic-inorganic composite particles is unlikely to contribute to the conductivity imparting of the ceramic substrate, it is less necessary to carry out the deashing step after firing. A ceramic substrate can be manufactured by a simple method.

  Since the ceramic substrate according to the present invention has uniform pores, it can be a substrate having a lower dielectric constant and excellent strength.

  Since the pore-forming particles according to the present invention are organic-inorganic composite particles having a so-called core-shell structure, the particles are unlikely to collapse during mixing with the ceramic raw material and firing. For this reason, uniform pores can be easily formed in the ceramic substrate, and thus the pore-forming particles are suitable as a material for forming pores in the ceramic substrate.

  Hereinafter, embodiments of the present invention will be described in detail.

(Composite material)
The composite material of the present embodiment includes organic-inorganic composite particles and ceramic particles, and the organic-inorganic composite particles have a core-shell structure formed of a core containing an organic resin and a shell containing a metal oxide. The composite material can be used as a raw material for forming a ceramic substrate. When a ceramic substrate is produced from the composite material, uniform pores can be formed inside the obtained ceramic substrate. For this reason, the composite material is suitable as a material for forming a ceramic substrate having a lower dielectric constant.

  More specifically, a ceramic sheet is formed by using the composite material as a paste, and then fired to sinter the ceramic sheet to obtain a ceramic substrate. During the firing, the core containing the organic resin in the organic-inorganic composite particles is burned out, while the shell containing the metal oxide is not burned out. As a result, the portion where the core is burned out is formed as pores, so that the organic-inorganic composite particles are changed to particles having pores. The holes thus formed become the holes of the ceramic substrate. And the shell which remains after baking becomes a part of component of a ceramic base material, and exists in a ceramic base material so that a void | hole may be covered.

  Hereinafter, the configuration of the composite material will be described in detail.

  The type of the organic-inorganic composite particles is not particularly limited as long as it has a core-shell structure formed of a core containing an organic resin and a shell containing a metal oxide.

  The core containing the organic resin can be, for example, organic particles formed of the organic resin. Examples of the organic resin include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polypropylene, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polyalkylene terephthalate, polysulfone, Polymer obtained by polymerizing one or more kinds of polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, and various polymerizable monomers having an ethylenically unsaturated group Etc. By polymerizing one or more of various polymerizable monomers having an ethylenically unsaturated group, the degree of freedom in designing the organic-inorganic composite particles is increased, and the synthesis is facilitated.

  When the core containing the organic resin is obtained by polymerizing the monomer having the ethylenically unsaturated group, the monomer having the ethylenically unsaturated group includes a non-crosslinkable monomer and And a crosslinkable monomer.

  Examples of the non-crosslinkable monomer include styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl ( Alkyl (meth) acrylates such as meth) acrylate and isobornyl (meth) acrylate; oxygen such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate and glycidyl (meth) acrylate (Meth) acrylates; nitrile-containing monomers such as (meth) acrylonitrile; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether; vinyl acids such as vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate Esters; Unsaturated hydrocarbons such as ethylene, propylene, isoprene and butadiene; Halogen-containing monomers such as trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride and chlorostyrene Is mentioned.

  In this specification, a chemical substance including the term “(meth) acryl” means one or both of “acryl” and “methacryl”. For example, “(meth) acryl” means one or both of “acryl” and “methacryl”, and “(meth) acrylate” means one or both of “acrylate” and “methacrylate”.

  Examples of the crosslinkable monomer include tetramethylolmethane tetra (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipenta Erythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Polyfunctional (meth) acrylates such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanure And silane-containing monomers such as triallyl trimellitate, divinylbenzene, diallyl phthalate, diallylacrylamide, diallyl ether, γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane It is done.

The polymerizable monomer may be a non-crosslinkable monomer alone, may be a crosslinkable monomer alone, or may be a mixture thereof. By polymerizing a polymerizable monomer having an unsaturated group, a core containing the organic resin can be obtained. The method of polymerization is not particularly limited, for example, a method of suspension polymerization in the presence of a radical polymerization initiator, a method of polymerizing by swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles, etc. Is mentioned.

  The core containing the organic resin may be formed of only the organic resin, or may contain components other than the organic resin. Examples of components other than the organic resin include, but are not limited to, raw materials used during the production of the organic resin.

  In 100% by weight of the core containing the organic resin, the content of silicon atoms contained in the core containing the organic resin is preferably 10% by weight or less, more preferably 5% by weight or less. The core containing the organic resin may not contain silicon atoms. The core containing the organic resin preferably does not contain a silicon atom.

  The decomposition temperature of the organic resin is not particularly limited.

  For example, the organic resin preferably has a thermal decomposition temperature in a nitrogen atmosphere of 270 ° C. or higher and lower than 500 ° C. In this case, since the core containing the organic resin is difficult to be decomposed at the initial stage of sintering of the ceramic sheet described later, the organic-inorganic composite particles can easily maintain a spherical shape because the particle strength can be maintained. For this reason, a uniform void | hole can be formed with a ceramic base material, and also a ceramic base material can be manufactured more easily. The “thermal decomposition temperature” in the present specification particularly indicates a temperature at which thermal decomposition of an organic resin starts in a nitrogen atmosphere.

  The average particle diameter of the core containing the organic resin is not particularly limited. For example, the average particle diameter of the core containing the organic resin can be 0.1 μm or more, preferably 0.2 μm or more, more preferably 0.5 μm or more, still more preferably 1.0 μm or more, particularly preferably. It can be 1.5 μm or more. Moreover, the average particle diameter of the core containing the organic resin can be 500 μm or less, preferably 300 μm or less, more preferably 100 μm or less. The average particle size of the core containing the organic resin may be 50 μm or less, more preferably 30 μm or less, still more preferably 5 μm or less, and particularly preferably 3 μm or less.

  The particle diameter of the core containing the organic resin means the diameter when the core containing the organic resin is a true sphere, and the maximum when the core containing the organic resin is a shape other than a true sphere. Means diameter. The average particle diameter of the core containing the organic resin is measured by observing the core containing the organic resin using a scanning electron microscope and measuring the particle diameter of the core containing 50 arbitrarily selected organic resins with a caliper. Means the average value.

  The shell containing the metal oxide may be disposed on the surface of the core containing the organic resin. The shell containing the metal oxide preferably covers the surface of the core containing the organic resin.

  Although the said metal oxide is not specifically limited, For example, the said metal oxide can contain 50 weight% or more of silicon atoms. In this case, the shell containing the metal oxide is formed as a shell containing silicon atoms as a main component. Note that the shell containing the metal oxide may be formed of an oxide containing another metal element or may contain a carbon atom.

  In 100% by weight of the shell containing the metal oxide, the content of silicon atoms contained in the shell containing the metal oxide is preferably 50% by weight or more, more preferably 54% by weight or more, and still more preferably 56% by weight or more. It is. In 100% by weight of the shell containing the metal oxide, the content of carbon atoms contained in the shell containing the metal oxide is preferably 30% by weight or less, more preferably 20% by weight or less, still more preferably 10% by weight or less. It is. It is preferable that the shell containing the metal oxide does not contain a carbon atom. The higher the content of silicon atoms in the shell containing the metal oxide, and the lower the content of carbon atoms in the shell containing the metal oxide, the better the strength of the organic-inorganic composite particles. Therefore, uniform vacancies can be easily formed, and the formed vacancies are less likely to collapse.

  Especially, it is preferable that the said metal oxide contains a silica. In this case, uniform pores can be formed by the ceramic base material, and the characteristics of the ceramic base material itself may be impaired even if the shell remains on the ceramic base material due to the material being silica. small.

  The content of silicon atoms and carbon atoms in the core containing the organic resin and the shell containing the metal oxide in the organic-inorganic composite particles can be measured by line analysis using a TEM / EDS method.

  The shell containing the metal oxide can be formed, for example, by forming a metal alkoxide into a shell-like material by a sol-gel method on the surface of the core containing the organic resin and then firing the shell-like material. In the sol-gel method, it is easy to dispose a shell-like material on the surface of the core containing the organic resin. Even when the shell-like material is fired, the core containing the organic resin is not removed by volatilization or the like and remains in the organic-inorganic composite particles.

  As a specific method of the sol-gel method, an inorganic monomer such as tetraethoxysilane is allowed to coexist in a dispersion containing a core containing an organic resin, a solvent such as water or alcohol, a surfactant, and a catalyst such as an aqueous ammonia solution. The interfacial sol reaction is performed, and after the sol-gel reaction is performed with an inorganic monomer such as tetraethoxysilane coexisting with a solvent such as water or alcohol, and an aqueous ammonia solution, the sol-gel reaction product is heteroaggregated in a core containing an organic resin. And the like. In the sol-gel method, the metal alkoxide is preferably hydrolyzed and polycondensed.

  In the sol-gel method, it is preferable to use a surfactant. In the presence of a surfactant, the metal alkoxide is preferably made into a shell by a sol-gel method. The surfactant is not particularly limited. The surfactant is appropriately selected and used so as to form a good shell. Examples of the surfactant include a cationic surfactant, an anionic surfactant, and a nonionic surfactant. Among these, a cationic surfactant is preferable because a shell containing a good metal oxide can be formed.

  Examples of the cationic surfactant include quaternary ammonium salts and quaternary phosphonium salts. Specific examples of the cationic surfactant include hexadecyl ammonium bromide.

  In order to form a shell containing the metal oxide on the surface of the core containing the organic resin, the shell-like material is preferably fired. The degree of crosslinking in the shell containing the metal oxide can be adjusted by the firing conditions. Moreover, the intensity | strength of the organic-inorganic composite particle obtained can be improved by baking compared with the case where baking is not performed. In particular, the organic-inorganic composite particle strength can be sufficiently increased by increasing the degree of crosslinking of the shell containing the metal oxide. In addition, the particle | grain intensity | strength here can be evaluated by 10% K value (compression elastic modulus when a particle | grain is compressed 10%) by a micro compression tester.

  The shell containing the metal oxide is formed by forming a metal alkoxide into a shell-like material by a sol-gel method on the surface of the core containing the organic resin, and then firing the shell-like material at 100 ° C. or higher (firing temperature). Preferably it is formed. The firing temperature is more preferably 150 ° C. or higher, and further preferably 200 ° C. or higher. When the firing temperature is equal to or higher than the lower limit, the degree of cross-linking in the shell containing the metal oxide becomes more appropriate, and high particle strength can be easily maintained.

  On the surface of the core containing the organic resin, the shell containing the metal oxide is converted into a shell-like material by sol-gel method on the surface of the core containing the organic resin, and then the shell-like material is heated below the decomposition temperature of the core containing the organic resin ( It is preferably formed by firing at a firing temperature. The firing temperature is preferably 5 ° C. or more lower than the decomposition temperature of the core containing the organic resin, and more preferably 10 ° C. or more lower than the decomposition temperature of the core containing the organic resin. Moreover, the said calcination temperature becomes like this. Preferably it is 800 degrees C or less, More preferably, it is 600 degrees C or less, More preferably, it is 500 degrees C or less. When the firing temperature is not more than the above upper limit, it is possible to suppress thermal deterioration and deformation of the core containing the organic resin, and to easily form organic-inorganic composite particles having high particle strength.

  Examples of the metal alkoxide include silane alkoxide, titanium alkoxide, zirconium alkoxide, and aluminum alkoxide. From the viewpoint of forming a shell containing a good metal oxide, the metal alkoxide is preferably a silane alkoxide, a titanium alkoxide, a zirconium alkoxide, or an aluminum alkoxide, and more preferably a silane alkoxide, a titanium alkoxide, or a zirconium alkoxide. Preferably, it is a silane alkoxide. From the viewpoint of forming a shell containing a good metal oxide, the metal atom in the metal alkoxide is preferably a silicon atom, a titanium atom, a zirconium atom or an aluminum atom, and is a silicon atom, a titanium atom or a zirconium atom. It is more preferable that it is a silicon atom. As for the said metal alkoxide, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of forming a shell containing a good metal oxide, the metal alkoxide is preferably a metal alkoxide represented by the following formula (1).

M (R1) _n (OR2) _4-n (1)
In said formula (1), M is a silicon atom, a titanium atom, or a zirconium atom, R1 is a phenyl group, a C1-C30 alkyl group, a C1-C30 organic group which has a polymerizable double bond, or A C1-C30 organic group which has an epoxy group is represented, R2 represents a C1-C6 alkyl group, and n represents the integer of 0-2. When n is 2, the plurality of R1s may be the same or different. Several R2 may be the same and may differ.

  From the viewpoint of forming a shell containing a good metal oxide, the metal alkoxide is preferably a silane alkoxide represented by the following formula (1A).

Si (R1) _n (OR2) _4-n Formula (1A)
In the above formula (1A), R1 represents a phenyl group, an alkyl group having 1 to 30 carbon atoms, an organic group having 1 to 30 carbon atoms having a polymerizable double bond, or an organic group having 1 to 30 carbon atoms having an epoxy group. R2 represents an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 0 to 2. When n is 2, the plurality of R1s may be the same or different. Several R2 may be the same and may differ. In order to effectively increase the content of silicon atoms contained in the shell containing the metal oxide, n in the above formula (1A) preferably represents 0 or 1, and more preferably represents 0. When the content of silicon atoms contained in the shell containing the metal oxide is high, the effect of the present invention is further improved.

  When R1 is an alkyl group having 1 to 30 carbon atoms, specific examples of R1 include methyl group, ethyl group, propyl group, isopropyl group, isobutyl group, n-hexyl group, cyclohexyl group, n-octyl group, And n-decyl group. This alkyl group preferably has 10 or less carbon atoms, more preferably 6 or less. The alkyl group includes a cycloalkyl group.

  Examples of the polymerizable double bond include a carbon-carbon double bond. When R1 is an organic group having 1 to 30 carbon atoms having a polymerizable double bond, specific examples of R1 include a vinyl group, an allyl group, an isopropenyl group, and a 3- (meth) acryloxyalkyl group. Etc. Examples of the (meth) acryloxyalkyl group include a (meth) acryloxymethyl group, a (meth) acryloxyethyl group, and a (meth) acryloxypropyl group. The carbon number of the organic group having 1 to 30 carbon atoms having a polymerizable double bond is preferably 2 or more, preferably 30 or less, more preferably 10 or less. The above “(meth) acryloxy” means methacryloxy or acryloxy.

  When R1 is an organic group having 1 to 30 carbon atoms having an epoxy group, specific examples of R1 include 1,2-epoxyethyl group, 1,2-epoxypropyl group, 2,3-epoxypropyl group, Examples include 3,4-epoxybutyl group, 3-glycidoxypropyl group, and 2- (3,4-epoxycyclohexyl) ethyl group. Carbon number of the C1-C30 organic group which has the said epoxy group becomes like this. Preferably it is 8 or less, More preferably, it is 6 or less. In addition, the C1-C30 organic group which has the said epoxy group is group containing the oxygen atom derived from an epoxy group in addition to a carbon atom and a hydrogen atom.

  Specific examples of R2 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and an isobutyl group. In order to effectively increase the content of silicon atoms contained in the shell containing the metal oxide, R2 preferably represents a methyl group or an ethyl group.

  Specific examples of the silane alkoxide include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, isopropyltrimethoxysilane, isobutyltrimethoxysilane, cyclohexyltrimethoxy. Examples include silane, n-hexyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, and diisopropyldimethoxysilane. Silane alkoxides other than these may be used.

  In order to effectively increase the content of silicon atoms contained in the shell containing the metal oxide, it is preferable to use tetramethoxysilane or tetraethoxysilane as the material of the shell containing the metal oxide. In 100% by weight of the shell material containing the metal oxide, the total content of tetramethoxysilane and tetraethoxysilane is preferably 50% by weight or more (or the total amount may be sufficient). The total content of the skeleton derived from tetramethoxysilane and the skeleton derived from tetraethoxysilane is preferably 50% by weight or more (100% by weight) in 100% by weight of the shell containing the metal oxide.

  Specific examples of the titanium alkoxide include titanium tetramethoxide, titanium tetraethoxide, titanium tetraisopropoxide, titanium tetrabutoxide, and the like. Titanium alkoxides other than these may be used.

  Specific examples of the zirconium alkoxide include zirconium tetramethoxide, zirconium tetraethoxide, zirconium tetraisopropoxide, zirconium tetrabutoxide and the like. Other zirconium alkoxides may be used.

  The metal alkoxide preferably includes a metal alkoxide having a structure in which four oxygen atoms are directly bonded to a metal atom. The metal alkoxide preferably includes a metal alkoxide represented by the following formula (1a).

M (OR2) ₄ Formula (1a)
In said formula (1a), M is a silicon atom, a titanium atom, or a zirconium atom, R2 represents a C1-C6 alkyl group. Several R2 may be the same and may differ.

  The metal alkoxide preferably includes a silane alkoxide having a structure in which four oxygen atoms are directly bonded to a silicon atom. In this silane alkoxide, generally, four oxygen atoms are bonded to a silicon atom by a single bond. The metal alkoxide preferably includes a silane alkoxide represented by the following formula (1Aa).

Si (OR2) ₄ Formula (1Aa)
In said formula (1Aa), R2 represents a C1-C6 alkyl group. Several R2 may be the same and may differ. From the viewpoint of adjusting the particle strength of the organic-inorganic composite particles to an appropriate range, four oxygen atoms are directly bonded to the metal atom in 100 mol% of the metal alkoxide used for forming the shell containing the metal oxide. A metal alkoxide having a structure, a metal alkoxide represented by the above formula (1a), a silane alkoxide having a structure in which four oxygen atoms are directly bonded to the silicon atom, or a silane represented by the above formula (1Aa) The content of each alkoxide is preferably 20 mol% or more, more preferably 40 mol% or more, still more preferably 50 mol% or more, still more preferably 55 mol% or more, particularly preferably 60 mol% or more, 100 mol%. It is as follows. A metal alkoxide having a structure in which four oxygen atoms are directly bonded to the metal atom, wherein the metal alkoxide used for forming the shell containing the metal oxide is a metal alkoxide represented by the formula (1a); A silane alkoxide having a structure in which four oxygen atoms are directly bonded to the silicon atom, or a silane alkoxide represented by the formula (1Aa) may be used.

  From the viewpoint of adjusting the particle strength of the organic-inorganic composite particles to an appropriate range, four oxygen atoms are directly bonded in 100% of the total number of metal atoms derived from the metal alkoxide contained in the shell containing the metal oxide. The ratio of the number of metal atoms in which the four —O—Si groups are directly bonded, and the ratio of the number of silicon atoms in which the four oxygen atoms in the four —O—Si groups are directly bonded Is preferably 20% or more, more preferably 40% or more, still more preferably 50% or more, still more preferably 55 mol% or more, and particularly preferably 60% or more.

  Furthermore, from the viewpoint of setting the particle strength of the organic-inorganic composite particles to an appropriate range, four oxygen atoms are directly bonded in 100% of the total number of metal atoms contained in the shell containing the metal oxide. The ratio of the number of metal atoms is preferably 20% or more, more preferably 40% or more, still more preferably 50% or more, still more preferably 55 mol% or more, and particularly preferably 60% or more. From the viewpoint of adjusting the particle strength of the organic-inorganic composite particles to an appropriate range, the metal alkoxide is a silane alkoxide, and 4 out of 100% of the total number of silicon atoms contained in the shell containing the metal oxide. The ratio of the number of silicon atoms in which —O—Si groups are directly bonded and in which the four oxygen atoms in the four —O—Si groups are directly bonded is preferably 20% or more, more preferably 40%. Above, more preferably 50% or more, particularly preferably 60% or more.

  Note that a silicon atom in which four —O—Si groups are directly bonded and four oxygen atoms in the four —O—Si groups are directly bonded is represented by, for example, the following formula (11). It is a silicon atom in the structure. Specifically, it is a silicon atom indicated by an arrow A in the structure represented by the following formula (11X).

  The oxygen atom in the above formula (11) generally forms a siloxane bond with the adjacent silicon atom.

  The ratio of the number of silicon atoms in which the four —O—Si groups are directly bonded and the four oxygen atoms in the four —O—Si groups are directly bonded (the ratio of the number of Q4 (%)). As a measuring method, for example, using an NMR spectrum analyzer, Q4 (four —O—Si groups are directly bonded, and four oxygen atoms in the four —O—Si groups are directly bonded. Peak area of silicon atoms) and Q1 to Q3 (1 to 3 —O—Si groups are directly bonded, and 1 to 3 oxygens in 1 to 3 —O—Si groups) And a method of comparing the peak areas of silicon atoms to which atoms are directly bonded. By this method, in the total number of 100% of silicon atoms contained in the shell containing the metal oxide, four —O—Si groups are directly bonded, and four of the four —O—Si groups The ratio of the number of silicon atoms to which oxygen atoms are directly bonded (the ratio of the number of Q4) can be determined.

  The thickness of the shell containing the metal oxide is preferably 1 nm or more, more preferably 10 nm or more, still more preferably 50 nm or more, particularly preferably 100 nm or more, preferably 100,000 nm or less, more preferably 10,000 nm or less, still more preferably 2000 nm or less. It can be. When the thickness of the shell containing the metal oxide is not less than the above lower limit and not more than the above upper limit, the core containing the organic resin can be easily decomposed smoothly while maintaining the shape of the shell. Thereby, uniform voids can be stably formed in the ceramic substrate. Moreover, even after the holes are once formed in the ceramic base material, the holes are not easily collapsed. Further, as will be described later, the carbonized layer generated by burning out the core of the organic-inorganic composite particles is easily confined in the shell, and it is easy to prevent the ceramic substrate from becoming highly conductive.

  Here, the thickness of the shell containing the metal oxide is an average thickness per organic-inorganic composite particle. By controlling the sol-gel method, the thickness of the shell containing the metal oxide can be controlled.

  The value of the thickness of the shell containing the metal oxide is, for example, an average obtained by observing the organic / inorganic composite particles using a scanning electron microscope and measuring the particle size of 50 arbitrarily selected organic / inorganic composite particles with calipers. It can be determined from the difference between the value and the average particle size of the core containing the organic resin. The particle diameter of the organic-inorganic composite particle means a diameter when the organic-inorganic composite particle is a true sphere, and means a maximum diameter when the organic-inorganic composite particle is a shape other than a true sphere.

  In the organic-inorganic composite particles, the ratio of the thickness of the shell containing the metal oxide to the radius of the core containing the organic resin (the thickness of the shell containing the metal oxide / the radius of the core containing the organic resin) is 0.05. Above and below 0.70. When the ratio of the thickness of the shell containing the metal oxide to the radius of the core containing the organic resin is within the above range, the addition of the organic-inorganic composite particles to form uniform pores in the ceramic substrate Easy to minimize the amount. Thereby, it is easy to prevent the performance reduction of the ceramic base material.

  The aspect ratio of the organic-inorganic composite particles can be set to 2 or less, for example. The aspect ratio of the organic-inorganic composite particles can be preferably 1.5 or less, more preferably 1.2 or less. In addition, the said aspect ratio shows the value of the major axis / minor axis of the said organic inorganic composite particle.

  In particular, the organic-inorganic composite particles preferably have an aspect ratio of 1.10 or less after being heat-treated at 500 ° C. in a nitrogen atmosphere. In this case, since the pores formed in the ceramic base material are nearly spherical, the strength of the ceramic base material can be prevented from being lowered, and a ceramic base material having excellent strength is easily formed.

  The size of the organic-inorganic composite particles is not particularly limited. For example, the number average particle size of the organic-inorganic composite particles can be 0.1 μm or more and 5.0 μm or less. If the number average particle diameter of the organic-inorganic composite particles is within the above range, the ceramic substrate can sufficiently form pores, and can be a ceramic substrate having a lower dielectric constant, and has a high strength. Can be.

  The number average particle diameter of the organic-inorganic composite particles means the diameter when the organic-inorganic composite particles are spherical, and the maximum and minimum diameters when the organic-inorganic composite particles are other than spherical. Mean value. The average particle diameter of the organic-inorganic composite particles is the average value obtained by observing the organic-inorganic composite particles using a scanning electron microscope and measuring the particle diameters of 50 arbitrarily selected organic-inorganic composite particles with a caliper. means.

  In the organic-inorganic composite particles, it is preferable that no chemical bond is formed between the core containing the organic resin and the shell containing the metal oxide. If the core containing the organic resin and the shell containing the metal oxide are not chemically bonded, the shell containing the metal oxide is not easily cracked, and uniform pores are formed in the ceramic substrate. It becomes easy to do. In addition, you may chemically bond between the core containing the said organic resin, and the shell containing the said metal oxide. As a method of chemically bonding the two, a functional group capable of reacting with a functional group of a material constituting a shell containing a metal oxide is introduced on the surface of the core containing the organic resin, and then the surface of the core containing the organic resin is introduced. And a method of forming a shell containing a metal oxide with a material constituting the shell containing the metal oxide. Specifically, the surface of the core containing the organic resin is surface-treated with a coupling agent, and then the metal alkoxide is formed into a shell-like material by the sol-gel method on the surface of the core containing the organic resin.

Compression modulus when the organic-inorganic composite particles was 10% compressive deformation (10% K value) is preferably 2000N / mm ² or more, more preferably 2500N / mm ² or more, more preferably 3000N / mm ² or more, preferably is 10000 N / mm ² or less, more preferably 8500N / mm ^2, more preferably not more than 6000 N / mm ^2. The organic-inorganic composite particles having the 10% K value of not less than the above lower limit and not more than the above upper limit can easily prevent the shell containing the metal oxide from being broken even when mixed with ceramic particles.

  The compression elastic modulus (10% K value) in the organic-inorganic composite particles can be measured as follows.

  Using a micro-compression tester, the organic-inorganic composite particles are compressed under the conditions of 25 ° C., compression speed of 0.3 mN / second, and maximum test load of 20 mN on the end face of a cylindrical indenter (diameter: 100 μm, made of diamond). The load value (N) and compression displacement (mm) at this time are measured. From the measured value obtained, the compression elastic modulus can be obtained by the following formula. As the micro compression tester, for example, “Fischer Scope H-100” manufactured by Fischer is used.

K value (N / mm ² ) = (3/2 ^1/2 ) · F · S ⁻³ / ² · R ^−1/2
Here, F is a load value (N) when the organic-inorganic composite particles are 10% compressively deformed, S is a compression displacement (mm) when the organic-inorganic composite particles are 10% compressively deformed, and R is the organic-inorganic composite particles. Radius (mm).

  The compression elastic modulus universally and quantitatively represents the hardness of the organic-inorganic composite particles. By using the compression elastic modulus, the hardness of the organic-inorganic composite particles can be expressed quantitatively and uniquely.

  In addition, the form of the organic-inorganic composite particles described above is an example, and other organic-inorganic composite particles having a known core-shell structure, for example, can also be employed for the composite material of the present embodiment.

The ceramic particles are not particularly limited, and examples thereof include known ceramic raw materials used for forming a ceramic base material such as an LTCC substrate. Specific examples of ceramic raw materials include particles of alumina, silica, aluminum nitride, silicon nitride, magnesia, spinel, mullite, forsterite, steatite, cordierite, strontium feldspar, quartz, zinc silicate, zirconia, titania and the like. Is done. The ceramic particles may be a glass component containing two or more oxides (for example, SiO ₂ , BaO, B ₂ O ₃ , MgO, Al ₂ O ₃ , Y ₂ O _3, etc.).

  The ceramic particles may be other glass components. Examples of other glass components include borosilicate glass, borosilicate barium glass, strontium borosilicate glass, zinc borosilicate glass, and potassium borosilicate glass.

  The ceramic particles may be formed of only the ceramic raw material, may be formed of only the glass component, or may contain both the ceramic raw material and the glass component.

  The shape and size of the ceramic particles are not particularly limited.

  The composite material of this embodiment may further contain an organic binder, a sintering aid, a plasticizer, a solvent, and the like. Examples of the organic binder include acrylic resins, polyvinyl butyral resins, polyvinyl alcohol resins, acrylic-styrene resins, polypropylene carbonate resins, and cellulose derivatives such as ethyl cellulose. Examples of the plasticizer include dibutyl phthalate and dioctyl phthalate. Examples of the solvent include ketones such as acetone, methyl ethyl ketone, dipropyl ketone and diisobutyl ketone; alcohols such as methanol, ethanol, isopropanol and butanol; aromatic hydrocarbons such as toluene and xylene; methyl propionate and propionate. Ethyl acetate, butyl propionate, methyl butanoate, ethyl butanoate, butyl butanoate, methyl pentanoate, ethyl pentanoate, butyl pentanoate, methyl hexanoate, ethyl hexanoate, butyl hexanoate, 2-ethylhexyl acetate, butyric acid 2 -Esters such as ethyl hexyl; methyl cellosolve, ethyl cellosolve, butyl cellosolve, α-terpineol, terpinyl acetate, dihydroterpineol, dihydroterpineol acetate, butyl cellosolve Tate, butyl carbitol acetate.

  In the composite material of the present embodiment, the contents of the organic-inorganic composite particles and the ceramic particles are not particularly limited. For example, the organic-inorganic composite particles can be 1% by mass to 50% by mass with respect to the total mass of the organic-inorganic composite particles and ceramic particles. When the content ratio of the organic-inorganic composite particles is within the above range, the organic-inorganic composite particles and the ceramic particles are easily mixed uniformly, and the pores formed in the obtained ceramic base material can be formed more uniformly. As a result, a ceramic base material having a low dielectric constant and excellent strength can be obtained.

  The composite material of this embodiment can be prepared by an appropriate method, and the preparation method is not limited. For example, a composite material can be prepared by mixing a predetermined amount of organic-inorganic composite particles, ceramic particles, and other additives such as a solvent added as appropriate. The mixing method is not particularly limited, and for example, mixing may be performed using a commercially available ball mill, jet mill, bead mill, or other mixer or disperser.

  The composite material may be in the form of a paste, slurry, powder, or dispersion, but may be in the form of a slurry in that a ceramic green sheet to be described later is formed to produce a ceramic substrate. preferable.

(Ceramic substrate)
A ceramic substrate can be produced by using the composite material. The method for producing the ceramic substrate is not particularly limited.

  For example, a ceramic substrate can be produced by a method comprising a step of forming a ceramic sheet from the composite material and a step of firing a laminate obtained by laminating the ceramic sheets. Hereinafter, the former process is abbreviated as “process 1”, and the latter process is abbreviated as “process 2”.

  In step 1, the method for forming the ceramic sheet is not limited. For example, a method similar to the method for producing a known ceramic green sheet can be employed. For example, a slurry-like composite material can be formed on a sheet by a method using a conventionally known doctor blade or calendar roll, a rolling method, or a press molding method.

  The thickness of the ceramic sheet formed as described above is, for example, 1 to 500 μm, but is not limited thereto.

  The ceramic sheet obtained as described above is formed into a sheet shape. The type of the ceramic sheet is not particularly limited. For example, the ceramic sheet may have the same configuration as that of a known ceramic green sheet, or may have another configuration. In any case, the ceramic sheet contains organic-inorganic composite particles in a dispersed state.

  In step 2, the laminate obtained by laminating the ceramic sheets formed in step 1 is fired.

  The laminate can be obtained by laminating a plurality of ceramic sheets formed in step 1. The method for laminating the ceramic sheets is not particularly limited, and can be performed by an appropriate method. For example, a ceramic sheet can be formed by further forming a ceramic sheet on the surface of the first formed ceramic sheet, and repeating this to obtain a laminate of ceramic sheets. After lamination of the ceramic sheets, for example, thermocompression bonding may be performed at a predetermined temperature and pressure. The thickness of a laminated body can be 200-10000 micrometers, for example.

  In step 2, the laminate is further fired. The method for firing the laminate is not particularly limited, and can be the same as, for example, the conventional firing conditions for ceramic green sheets. For example, the laminate can be sintered using a commercially available sintering furnace or the like.

  The firing conditions can also be set as appropriate. For example, after the binder removal treatment at 400 to 600 ° C., the firing temperature is 650 to 1500 ° C., preferably 700 to 1100 ° C., and the firing time is 0.02 to 10 hours. can do. Firing may be performed in an air atmosphere or an inert gas atmosphere such as nitrogen. After sintering, a cooling process can be performed by an appropriate method.

  By the firing in the above step 2, the laminate is sintered to form a sintered body, thereby producing a ceramic substrate.

  While the sintering of the ceramic particles proceeds by the firing in step 2, the core containing the organic resin in the organic-inorganic composite particles contained in the composite material is burned out because it is an organic component. As described above, the core portion containing the organic resin in the organic-inorganic composite particles is burned out, and thus the organic-inorganic composite particles have pores formed therein after the firing. As a result, particles having pores are dispersed in the ceramic substrate obtained by firing in step 2. As a result, a ceramic substrate having pores therein is formed. That is, the ceramic base material obtained through the steps 1 and 2 includes a sintered body of a laminate of ceramic sheets including a composite material as a constituent element, and pores are formed inside the sintered body.

  As described above, the pores formed in the ceramic base are formed by organic-inorganic composite particles contained in the composite material. Since the organic-inorganic composite particles have a core-shell structure, the organic-inorganic composite particles are unlikely to break down from the preparation of the composite material to the firing of the ceramic sheet. Therefore, by firing the ceramic sheet, pores can be uniformly formed inside the obtained ceramic substrate. Conventionally, in hollow silica particles and the like that have been used for pore formation, there have been cases in which it is difficult to form uniform pores due to destruction or the like in the process until the ceramic paste is fired. Such a possibility is small when a void | hole is formed with an inorganic composite particle. Moreover, by adjusting the shape of the organic-inorganic composite particles, the pores can be easily controlled to be spherical or a shape close thereto. As described above, since uniform and spherical pores are easily formed, the obtained ceramic substrate has a lower dielectric constant than that of the conventional one, and also has excellent strength.

  In addition, when pores are formed using resin particles not covered with a shell as in the past, stable pores may not be formed due to problems such as shrinkage, but the organic-inorganic composite particles Then, since the core which is an organic resin is covered with the shell containing a metal oxide, such a possibility is small.

  The size of the pores formed in the ceramic substrate can be adjusted to a desired range by appropriately selecting the size of the organic-inorganic composite particles to be used, particularly the size of the core. In addition, the shape of the pores formed in the ceramic substrate depends on the shape of the organic-inorganic composite particles used, especially the shape of the core. Therefore, the shape of the pores can also be controlled by appropriately selecting the shape of the core Is possible. For example, the aspect ratio of the pores formed in the ceramic substrate can be 2 or less, preferably 1.7 or less, more preferably 1.5 or less. In addition, the number of pores formed in the ceramic substrate can be easily controlled by adjusting the amount of organic-inorganic composite particles used.

  The ratio of pores formed inside the ceramic substrate is not limited. For example, when a ceramic substrate is cut, the holes may be formed in a ratio that the cross-sectional area of the holes is 0.1 or more with respect to the cross-sectional area of the cut surface. It is preferable that the pores are formed at a ratio of the cross-sectional area of the pores of 0.15 or more with respect to the cross-sectional area of the ceramic substrate, and the pores are formed at a ratio of 0.2 or more. More preferably, pores are particularly preferably formed at a ratio of 0.25 or more. The upper limit of the cross-sectional area of the pores relative to the cross-sectional area of the ceramic substrate is not particularly limited, but is usually about 0.7.

  As described above, since the ceramic base material of the present embodiment has uniform pores, it can be a base material that has a lower dielectric constant and is excellent in strength, and thus is suitably used for applications such as LTCC substrates. obtain.

  Furthermore, when the core of the organic-inorganic composite particles is burned out by firing the ceramic sheet, a carbonized layer is generated due to the generation of soot or the like. This carbonized layer adheres to the inner surface of the shell, for example. That is, the carbonized layer generated by firing is confined in the shell. For this reason, even if a carbonized layer such as soot is generated, the carbonized layer hardly affects the conductivity of the ceramic base material itself, and there is little possibility that the characteristics of the ceramic base material are impaired by the core being burned out. In this way, the carbonized layer formed after firing the organic-inorganic composite particles is unlikely to contribute to imparting electrical conductivity to the ceramic substrate, so there is less need for a separate deashing step after firing, and a simpler process. Ceramic substrates can be manufactured.

  As described above in detail, if the composite material of the present embodiment is used, uniform voids can be easily formed in the ceramic substrate, and therefore, the ceramic substrate having a low dielectric constant and excellent strength. Suitable as a material (ceramic paste) for forming the material.

  The organic-inorganic composite particles contained in the composite material can easily form uniform pores in the ceramic base material. Therefore, a material for forming pores in the ceramic base material, so-called pore formation It is a material suitable as particles.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to the aspect of these Examples.

(Preparation Example 1)
The core containing the organic resin was prepared as follows. 950 parts by weight of 1,4-butanediol diacrylate and 50 parts by weight of ethylene glycol dimethacrylate were mixed to obtain a mixed solution. 20 parts by weight of benzoyl peroxide was added to the obtained mixed solution and stirred until it was uniformly dissolved to obtain a monomer mixed solution. 4000 parts by weight of a 2% by weight aqueous solution prepared by dissolving polyvinyl alcohol having a molecular weight of about 1700 in pure water was placed in a reaction kettle. The obtained monomer mixed solution was put into this, and stirred for 4 hours to adjust the particle size so that the monomer droplets had a predetermined particle size. Thereafter, the reaction was performed in a nitrogen atmosphere at 85 ° C. for 9 hours, and the polymerization reaction of the monomer droplets was performed to obtain particles. The obtained particles were washed several times with water and then classified to prepare a 2.75 μm core (a core containing an organic resin). 30 parts by weight of the core and 12 parts by weight of hexadecyltrimethylammonium bromide as a surfactant were dispersed in a mixed solvent of 540 parts by weight of isopropyl alcohol and 60 parts by weight of water, and placed in a separable flask. 24 parts by weight of 25% by weight aqueous ammonia solution was added and stirred while applying ultrasonic waves. 170 parts by weight of tetraethoxysilane was added, and the mixture was stirred at 25 ° C. for 12 hours while applying ultrasonic waves. The reaction solution was taken out, suction filtered through a membrane filter, and washed twice using ethanol, and then dried in a vacuum dryer at 50 ° C. for 24 hours to obtain organic-inorganic composite particles. The thermal decomposition starting temperature in the nitrogen atmosphere of the core containing the organic resin was 388 ° C.

(Preparation Example 2)
A core containing an organic resin was prepared as follows. To 1000 parts by weight of divinylbenzene (purity 96%), 40 parts by weight of benzoyl peroxide was added and stirred until evenly dissolved to obtain a monomer mixture. 4000 parts by weight of a 2% by weight aqueous solution prepared by dissolving polyvinyl alcohol having a molecular weight of about 1700 in pure water was placed in a reaction kettle. The obtained monomer mixed solution was put into this, and stirred for 4 hours to adjust the particle size so that the monomer droplets had a predetermined particle size. Thereafter, the reaction was performed in a nitrogen atmosphere at 85 ° C. for 9 hours, and the polymerization reaction of the monomer droplets was performed to obtain particles. The obtained particles were washed several times with water, and then classified to prepare a 2.78 μm resin core. The thermal decomposition starting temperature in the nitrogen atmosphere of the core containing the organic resin was 453 ° C. Organic-inorganic composite particles were obtained in the same manner as in Example 1 except that the core obtained as described above was used.

(Preparation Example 3)
A core containing an organic resin was prepared as follows. 600 parts by weight of divinylbenzene (purity 96%) and 40 parts by weight of isobornyl acrylate were mixed to obtain a mixed solution. 20 parts by weight of benzoyl peroxide was added to the obtained mixed solution and stirred until it was uniformly dissolved to obtain a monomer mixed solution. 4000 parts by weight of a 2% by weight aqueous solution prepared by dissolving polyvinyl alcohol having a molecular weight of about 1700 in pure water was placed in a reaction kettle. The obtained monomer mixed solution was put into this, and stirred for 4 hours to adjust the particle size so that the monomer droplets had a predetermined particle size. Thereafter, the reaction was performed in a nitrogen atmosphere at 85 ° C. for 9 hours, and the polymerization reaction of the monomer droplets was performed to obtain particles. The obtained particles were washed several times with water and then classified to prepare a 2.70 μm resin core. The thermal decomposition starting temperature in a nitrogen atmosphere was 330 ° C. Organic-inorganic composite particles were obtained in the same manner as in Example 1 except that the core obtained as described above was used.

(Preparation Example 4)
A core containing an organic resin was prepared as follows. 20 parts by weight of benzoyl peroxide was added to 1000 parts by weight of ethylene glycol dimethacrylate and stirred until it was uniformly dissolved to obtain a monomer mixture. 4000 parts by weight of a 2% by weight aqueous solution prepared by dissolving polyvinyl alcohol having a molecular weight of about 1700 in pure water was placed in a reaction kettle. The obtained monomer mixed solution was put into this, and stirred for 4 hours to adjust the particle size so that the monomer droplets had a predetermined particle size. Thereafter, the reaction was performed in a nitrogen atmosphere at 85 ° C. for 9 hours, and the polymerization reaction of the monomer droplets was performed to obtain particles. The obtained particles were washed several times with water and then classified to prepare a 2.68 μm resin core. The thermal decomposition starting temperature was 189 ° C. Organic-inorganic composite particles were obtained in the same manner as in Example 1 except that the core obtained as described above was used.

(Preparation Example 5)
30 parts by weight of the core containing the organic resin obtained in Example 1 was dispersed in a mixed solvent of 1100 parts by weight of isopropyl alcohol and 20 parts by weight of water, and stirred in a separable flask while applying ultrasonic waves. Thereto was added a mixed solution of 90 parts by weight of titanium (IV) tetrabutoxide monomer and 3000 parts by weight of isopropyl alcohol, and the mixture was stirred at 25 ° C. for 3 hours while applying ultrasonic waves. Thereafter, 90 parts by weight of titanium (IV) tetrabutoxide monomer was further added, and the mixture was stirred at 25 ° C. for 9 hours. The reaction solution was taken out, suction filtered through a membrane filter, and washed twice using ethanol, and then dried in a vacuum dryer at 50 ° C. for 24 hours to obtain organic-inorganic composite particles.

Example 1
As the ceramic composition, the average particle diameter having a composition of _{SiO 2 / BaO / B 2 O} 3 / MgO / Al 2 O 3 / Y 2 O 3 = 29/23/9/16/16/7 is 2μm in a weight ratio of Glass A was prepared. 20 parts by weight of the organic-inorganic composite particles obtained in Preparation Example 1 are blended with 100 parts by weight of a mixture of 75% by weight of this glass A and 25% by weight of alumina having an average particle diameter of 2 μm. A suitable amount of dioctyl phthalate (DOP) and toluene was added as an agent to form a slurry to obtain a composite material. A ceramic green sheet having a thickness of 100 μm was produced from this composite material by a doctor blade method. Further, a plurality of the ceramic green sheets were laminated so as to have a desired thickness, and thermocompression bonded by applying a pressure of 10 MPa at 60 ° C.

  Next, the binder was subjected to a binder removal step at 500 ° C., heated at 200 ° C./hour, then held at 900 ° C. for 1 hour and fired to form a sintered body to obtain a ceramic substrate. .

(Example 2)
A ceramic base material was obtained in the same manner as in Example 1 except that the organic-inorganic composite particles obtained in Preparation Example 1 were changed to the organic-inorganic composite particles obtained in Preparation Example 2.

(Example 3)
A ceramic base material was obtained in the same manner as in Example 1, except that the organic-inorganic composite particles obtained in Preparation Example 1 were changed to the organic-inorganic composite particles obtained in Preparation Example 3.

Example 4
A ceramic substrate was obtained in the same manner as in Example 1 except that the organic-inorganic composite particles obtained in Preparation Example 1 were changed to the organic-inorganic composite particles obtained in Preparation Example 4.

(Example 5)
A ceramic substrate was obtained in the same manner as in Example 1 except that the organic-inorganic composite particles obtained in Preparation Example 1 were changed to the organic-inorganic composite particles obtained in Preparation Example 5.

(Comparative Example 1)
In place of the organic-inorganic composite particles obtained in Preparation Example 1, a ceramic substrate was prepared in the same manner as in Example 1 except that the core was changed to a core containing an organic resin prepared in the production process of the organic-inorganic composite particles in Preparation Example 1. I got the material.

(Comparative Example 2)
A ceramic base material was obtained in the same manner as in Example 1 except that instead of the organic-inorganic composite particles obtained in Preparation Example 1, it was changed to commercially available hollow glass beads (average particle diameter: 3.79 μm). .

<Evaluation method>
(1) Average particle size of organic-inorganic composite particles, core particle size, and shell thickness The obtained organic-inorganic composite particles were 3000 times larger with a scanning electron microscope ("S-3500N" manufactured by Hitachi High-Technology Corporation). A particle image was taken, the particle size of 100 particles in the obtained image was measured with calipers, and the number average was determined to determine the particle size of the organic-inorganic composite particles. The particle size of the core used for producing the organic / inorganic composite particles was also measured by the same method as described above. From the difference between the particle size of the organic-inorganic composite particles and the particle size of the organic core, the thickness of the shell was determined. Regarding the shell thickness of the hollow particles, an image of the cross section of the particle was taken, and 100 shell thicknesses of the obtained image were measured with calipers, and the number average was obtained to obtain the shell thickness.

(2) Thermal decomposition temperature of core of organic / inorganic composite particles 10 mg of resin core particles were weighed with TG / DTA (TG / DTA7300, manufactured by Hitachi High-Tech Science Co., Ltd.), and the flow rate of nitrogen was 100 ml / min. Under an atmosphere, the temperature was raised to 550 ° C. at a starting temperature of 30 ° C. at 10 ° C./min and held for 5 minutes. The temperature at which weight reduction was confirmed was measured as the thermal decomposition temperature.

(3) Aspect ratio after heating The sample (organic-inorganic composite particles, core containing organic resin or hollow glass beads) is heated in a nitrogen gas atmosphere furnace at 500 ° C. for 1 hour, and then a scanning electron microscope (Hitachi High-Technology Corporation) (“S-3500N” manufactured by Kobayashi Co., Ltd.)) was photographed at a magnification of 3000 times, and the major axis and minor axis of 100 particles in the obtained image were measured with a caliper, and the major axis / minor axis was obtained to obtain the The aspect ratio was measured.

(4) Area ratio of pores and aspect ratio of ceramic base material Cross section image of ceramic base material obtained by scanning electron microscope ("S-3500N" manufactured by Hitachi High-Technology Corporation) with a magnification of 3000 times. The obtained image was photographed, and all cross-sectional areas of the hole portions on one image were measured, and the area ratio of the hole portions in the ceramic substrate was obtained. In addition, the radius of the hole for calculating the cross-sectional area is based on the inner diameter of the shell, and when the hole has a major axis and a minor axis, it is based on the major axis of the shell. Further, the aspect ratio of the pores was measured by determining the major axis / minor axis.

(5) Strength of Ceramic Base Material The obtained ceramic base material was processed into 3 mm × 4 mm × 50 mm, and a three-point bending strength based on JIS R-1601 was measured using an autograph. For the base material strength, a sample base material prepared without putting organic-inorganic composite particles in Example 1 was prepared separately, and relative evaluation was performed with this sample base material as 1.

(6) Dielectric constant of ceramic substrate The obtained ceramic substrate was processed into a size of 50 mm x 50 mm x 1 mm, and the dielectric constant at 2 GHz was measured by a dielectric-filled cavity resonator method. The measured dielectric constant was evaluated relative to the sample substrate as 1.

  Table 1 shows the average particle diameter of the organic-inorganic composite particles obtained in Preparation Examples 1 to 5, the shell thickness, the shell thickness / core radius value, the decomposition start temperature of the organic resin core, and the organic-inorganic composite after heating. The aspect ratio of the particles is shown. In addition, in Table 1, the average particle diameter of the core containing the organic resin of Example 1, the decomposition start temperature of the organic resin core and the aspect ratio after heating, the average particle diameter of the hollow glass beads, the thickness of the shell, and The aspect ratio after heating is shown.

  Table 2 shows the evaluation results of the ceramic substrates obtained in each of the examples and comparative examples. Specifically, the area ratio of the pores, the aspect ratio of the pores, the strength of the ceramic substrate, and the ceramic The dielectric constant of the substrate is shown.

  As in Examples 1 to 5, in the ceramic substrate formed using the organic-inorganic composite particles having the core-shell structure formed of the core and the shell, Comparative Example 1 (core only), Comparative Example 2 (hollow glass) It can be seen that the area ratio of the vacancies is high and the vacancies are effectively formed. Moreover, since the pores of the ceramic substrates of Examples 1 to 5 formed in this way have a small aspect ratio, it can be seen that they are formed in a shape close to a true sphere. Thereby, the ceramic base material obtained in Examples 1-5 has high base-material intensity | strength.

  In Comparative Example 1, the dielectric constant is increased due to the influence of the carbon layer formed by burning the core containing the organic resin, whereas in Examples 1 to 5, the core containing the organic resin is inside the shell. It can be said that the influence of the carbon layer formed by burning out the core containing the organic resin is small.

Claims (12)

Including organic-inorganic composite particles and ceramic particles,
The organic-inorganic composite particle is a composite material having a core-shell structure formed of a core containing an organic resin and a shell containing a metal oxide.   2. The composite material according to claim 1, wherein the organic resin has a thermal decomposition temperature in a nitrogen atmosphere of 270 ° C. or higher and lower than 500 ° C. 3.   The composite material according to claim 1 or 2, wherein the organic-inorganic composite particles have a number average particle diameter of 0.1 µm or more and 5.0 µm or less.   The composite material according to any one of claims 1 to 3, wherein the organic-inorganic composite particles have an aspect ratio of 1.10 or less after being subjected to heat treatment at 500 ° C in an atmosphere of nitrogen.   The composite material according to claim 1, wherein the metal oxide includes silica.   A ceramic base material comprising a sintered body of a laminate of ceramic sheets containing the composite material according to any one of claims 1 to 5 as a constituent element, wherein pores are formed inside the sintered body. .   The manufacturing method of a ceramic base material provided with the process of forming a ceramic sheet with the composite material of any one of Claims 1-5, and the process of baking the laminated body obtained by laminating | stacking the said ceramic sheet. Pore-forming particles for forming pores in a ceramic substrate,
A pore-forming particle comprising organic-inorganic composite particles having a core-shell structure formed of a core containing an organic resin and a shell containing a metal oxide.   The hole forming particles according to claim 8, wherein the organic resin has a thermal decomposition temperature in a nitrogen atmosphere of 270 ° C or higher and lower than 500 ° C.   The hole forming particles according to claim 8 or 9, wherein the number average particle diameter of the organic-inorganic composite particles is 0.1 µm or more and 5.0 µm or less.   The pore-forming particles according to any one of claims 8 to 10, wherein the organic-inorganic composite particles have an aspect ratio of 1.10 or less after being heat-treated at 500 ° C in an atmosphere of nitrogen. .   The particle | grain for void | hole formation of any one of Claims 8-11 whose said metal oxide is a silica.