JP2005242096A - Photosensitive ceramic composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive ceramic composition capable of forming a high-definition via hole having a high aspect ratio by a photolithographic method, and being used for a circuit material such as a ceramic multilayer substrate for high-frequency radio transmission. <P>SOLUTION: The photosensitive ceramic composition has an inorganic powder and a photosensitive organic component as essential components. The inorganic powder includes alumina powder whose average particle diameter is ≤500 nm, and the photosensitive organic component includes a polymer containing an ester of a polyhydric alcohol and an ethylenically unsaturated carboxylic acid as a copolymerized component and having an ethylenically unsaturated group in a side chain. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photosensitive ceramic composition. The photosensitive ceramic composition of the present invention is used for circuit materials such as a ceramic multilayer substrate for high frequency radio.

  The spread of wireless communication technology including mobile phones is remarkable. A conventional mobile phone uses a quasi-microwave band of 800 MHz to 1.5 GHz. However, as the amount of information increases, there is a wireless technology that changes a carrier frequency from a microwave band having a higher frequency to a millimeter wave band. Proposed and realized. These high-frequency radio circuits are expected to be used as mobile communications and network devices, and are becoming increasingly important technologies especially when used in Bluetooth and ITS (Intelligent Transport System). .

  In order to realize these high-frequency circuits, the substrate material used there must also have excellent high-frequency transmission characteristics in the wavelength band used, that is, 1 to 100 GHz. In order to realize excellent high-frequency transmission characteristics, it is necessary to have low dielectric constant and low dielectric loss, high processing accuracy, and good dimensional stability, and ceramic substrates are especially promising. It was.

  However, although the conventional ceramic substrate materials are excellent in dimensional stability, the fine processing degree is low, so that sufficient characteristics cannot be obtained particularly in a high frequency region. As a method for improving such a problem of fine processing accuracy, a via hole forming method using a photolithography technique using a green sheet formed from a photosensitive ceramic composition has been proposed (for example, see Patent Document 1). However, this method has a limit in forming a high aspect ratio via hole. The reason was that ultraviolet rays during photolithographic processing were diffusely reflected and did not reach the deep part.

  Therefore, as a method for solving these problems, it has been proposed to make the average particle diameter of ceramic particles contained in the sheet smaller than the wavelength of ultraviolet rays (see, for example, Patent Document 2). By this method, the ultraviolet transmittance is improved, and the ultraviolet rays reach the deep part of the sheet, whereby a high aspect ratio via hole can be formed.

In order to further improve the firing characteristics, there has been proposed a method of blending a binder resin selected from polyethers such as polyglycerin or polyester in the photosensitive ceramic composition (see, for example, Patent Document 3). By this method, deformation and peeling during lamination firing are reduced, leading to an improvement in yield. However, in such a blending method of the binder resin, the binder resin is eluted into the developer in the development process, and the sheet after pattern processing becomes rigid and brittle. Then, there is a problem that cracking and chipping occur in a process after pattern processing (sheet handling process such as conductor paste hole filling, conductor pattern processing, and multilayer lamination of sheets).
JP-A-6-202323 JP 2002-162735 A JP 2002-311583 A

  In order to enable high-aspect-ratio and high-definition via-hole formation using a photolithography method, it is necessary that fine ceramic particles are uniformly dispersed. Further, in order to be in a state suitable for the processing step after the via hole is formed, it is necessary to maintain the sheet flexibility after development. This invention makes it a subject to provide the photosensitive ceramic composition corresponding to them.

  That is, the present invention relates to a photosensitive ceramic composition comprising an inorganic powder and a photosensitive organic component as essential components, the inorganic powder containing an alumina powder having an average particle size of 500 nm or less, and the photosensitive organic component being a copolymer component. The problem is solved by a photosensitive ceramic composition comprising an ester of a monohydric alcohol and an ethylenically unsaturated carboxylic acid and containing a polymer having an ethylenically unsaturated group in the side chain.

  The photosensitive ceramic composition of the present invention can provide a sheet that is excellent in photolithography processability, retains sheet flexibility after development, and is effective in preventing cracks and chipping in subsequent processes.

   The photosensitive ceramic composition of the present invention comprises an inorganic powder and a photosensitive organic component as essential components, the inorganic powder contains an alumina powder having an average particle size of 500 nm or less, and the photosensitive organic component is a copolymer component. A photosensitive ceramic composition comprising a polymer containing an ester of a polyhydric alcohol and an ethylenically unsaturated carboxylic acid and having an ethylenically unsaturated group in the side chain.

  In the present invention, the photosensitive ceramic composition comprises an inorganic powder and a photosensitive organic component. The inorganic powder contains alumina powder as an essential component, and may contain glass powder and other inorganic powders. The average particle size of the alumina powder is 500 nm or less, preferably 300 nm or less, and more preferably 150 nm or less. By using alumina powder of such a size, low-temperature firing is possible, a sintered body with high sinterability and high density and high mechanical strength can be obtained, and light during exposure is scattered. Therefore, the exposure characteristics are not impaired. When the average particle diameter exceeds 500 nm, ultraviolet rays do not reach the deep part, and thus a high-definition pattern cannot be formed. The content of the alumina powder is preferably 5% by weight to 90% by weight, and more preferably 20% by weight to 80% by weight with respect to the photosensitive ceramic composition. By making the addition amount of the alumina powder within this range, the light transmittance of the sheet can be increased without deteriorating the sheet dielectric constant characteristics after firing, so that the photolithography processability is improved.

  The photosensitive ceramic composition of the present invention may contain at least one inorganic powder selected from the group consisting of silica, zirconia, titania, yttria, ceria and magnesia. Particularly preferred are silica, titania and the like, but a plurality of kinds of components can be mixed and used. Although glass powder can be contained as an inorganic component other than the above, since these transmit light such as an ultra-high pressure mercury lamp, the average particle diameter is not restricted. In addition, the inorganic powder contained in the ceramic composition of the present invention is sintered in the firing step, and firing at a temperature of 1000 ° C. or less, particularly 600 to 950 ° C. is preferable in the formation of the substrate intended by the present invention. Therefore, so-called low-temperature fired inorganic powder is preferable. Of course, since these inorganic powders determine basic physical properties such as electrical characteristics, strength, and thermal expansion coefficient of the substrate, they are selected according to the intended characteristics.

  The component useful as the inorganic powder used in the present invention includes four embodiments.

The first aspect of the the general formula _{R x O-Al 2 O 3} -SiO 2 aluminosilicate which (R is an alkali metal (x = 2) or alkaline earth metal (x = 1) shows a) represented by It is a salt compound. Although not particularly limited, inorganic powders used as a low-temperature sintered ceramic material, such as anorthite (CaO—Al ₂ O ₃ -2SiO ₂ ), Celsian (BaO—Al ₂ O ₃ -2SiO ₂ ), etc. is there.

  The inorganic powder of the second aspect is composed of 50 to 90% by weight of glass powder and 10 to 50% by weight of quartz powder and / or amorphous silica powder. The glass powder is borosilicate glass. At this time, it is preferable that high-purity silica (quartz) does not dissolve in borosilicate glass or cordierite. Further, spherical silica is preferable because the slurry can be filled more easily.

  Said third embodiment is selected from the group of borosilicate glass powder 30-60% by weight, quartz powder and / or amorphous silica powder 20-50% by weight and cordierite, spinel, forsterite, anorthite and serdian. And a mixture of 20 to 50% by weight of at least one ceramic powder.

A fourth aspect of the above, SiO on an oxide basis notation _2: 30-70 wt%, Al ₂ O _3: 5~40 wt%, CaO: 3 to 25 wt%, B ₂ O _3: 3~50 wt 30 to 60% by weight of a glass powder having a total amount of 85% by weight or more in a composition range of 50% by weight, alumina, zirconia, magnesia, beryllia, mullite, cordierite, spinel, forsterite, anorthite, serzian, silica and It is a mixture with at least one ceramic powder 70 to 40% by weight selected from the group of aluminum nitride.

  The inorganic powder can contain a filler component, and the ceramic powder is often used as the filler component as described above, which is effective in improving the mechanical strength of the substrate and controlling the thermal expansion coefficient. In particular, alumina, zirconia, mullite, cordierite, and anorthite have excellent effects. By mixing these ceramic powders, the firing temperature can be set to 800 to 900 ° C., and the strength, dielectric constant, thermal expansion coefficient, sintered density, volume resistivity, and shrinkage rate can be set as desired characteristics.

Components such as SiO ₂ , Al ₂ O ₃ , CaO and B ₂ O ₃ in the glass powder are preferably 85% by weight or more in the glass powder. The remaining 15% by weight or less can contain Na ₂ O, K ₂ O, BaO, PbO, Fe ₂ O ₃ , Mn oxide, Cr oxide, NiO, Co oxide and the like. 70 to 40% by weight of ceramic powder combined with 30 to 60% by weight of glass powder becomes a filler component. The SiO ₂ in the glass powder is preferably in the range of 30 to 70% by weight. Al ₂ O ₃ is preferably blended in the range of 5 to 40% by weight. CaO is preferably blended in the range of 3 to 25% by weight. By setting it as such a range, the sheet | seat suitable for baking at 1000 degrees C or less can be obtained, without impairing the intensity | strength and stability of a glass layer, a mechanical, and a thermal characteristic. B ₂ O ₃ melts the glass frit at a temperature around 1300 to 1450 ° C., and even when Al ₂ O ₃ is large, the dielectric constant, strength, thermal expansion coefficient, sintering temperature, etc. It is desirable to blend in order to control the firing temperature in the range of 800 to 900 ° C. so as not to impair the heat treatment, and the blending amount is preferably in the range of 3 to 50% by weight.

  In order to maintain the pattern forming property at a high level in the photosensitive ceramic composition, it is important to match the refractive indexes of the inorganic powder and the photosensitive organic component. The refractive index of the inorganic powder can be controlled by the blending ratio of the composition, and it is preferable to consider so as to match the average refractive index of the photosensitive organic component to be blended. In some cases, a means for increasing the refractive index of the photosensitive organic component may be used, in which case it is selected from the group consisting of a sulfur atom, a bromine atom, an iodine atom, a naphthalene ring, a biphenyl ring, an anthracene ring, and a carbazole ring. For example, a method of adding 20% by weight or more of a compound having a group may be applied.

  The inorganic powder of the present invention can be fired at 600 to 950 ° C. which can be multilayered using Cu, Ag, Au or the like as a wiring conductor, and approximates the thermal expansion coefficient of chip parts such as GaAs or printed circuit boards. It is preferable to provide a substrate having a thermal expansion coefficient, a low dielectric constant and a low dielectric loss even in a high frequency region.

  The photosensitive organic component contained in the photosensitive ceramic composition is a mixture of a photosensitive polymer, a monomer, and a photoinitiator, and includes an ultraviolet light absorber, a sensitizer, a polymerization inhibitor, a non-photosensitive polymer, a solvent, and the like. It can also be added. The photosensitive polymer is mainly photocurable, but may be a photosoluble polymer composition.

  In the present invention, the photosensitive organic component contains an ester of a polyhydric alcohol and an ethylenically unsaturated carboxylic acid as a copolymer component, and contains a polymer having an ethylenically unsaturated group in the side chain. Here, the polyhydric alcohol is, for example, glycerin, polyglycerin, 1,4-butanediol, 1,3-butylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, pentaerythritol, triglyceride. Mention may be made of methylolpropane, neopentyl glycol, propylene glycol, polypropylene glycol, hexylene glycol, methyl carbitol, butyl carbitol and the like. Examples of the ethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetic acid, and acid anhydrides thereof. Examples of copolymer components containing esters of these polyhydric alcohols and unsaturated carboxylic acids include glycerol acrylate, 1,4-butanediol diacrylate, 1,3-butylene glycol diacrylate, ethylene glycol diacrylate, and diethylene glycol. Diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, ditrimethylolpropane tetraacrylate, glycerol diacrylate, neopentyl glycol diacrylate, propylene glycol diacrylate, polypropylene Glycol diacrylate, triglycerol diacrylate, trimethylol group Bread triacrylate, and the like can be given those changed to methacrylates part or all of the acrylate of the above compounds. In the present invention, one or more of these can be used.

  In the present invention, an unsaturated acid such as an unsaturated carboxylic acid is added to these copolymer components in order to introduce an ethylenically unsaturated group into the side chain of the polymer. Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetic acid, and acid anhydrides thereof. The acid value of the acrylic copolymer obtained by polymerizing these components is preferably 100 to 200 (mgKOH / g). By adding a monomer having an ethylenically unsaturated group to the resulting acrylic copolymer, an ester of a polyhydric alcohol and an unsaturated carboxylic acid is included as a copolymer component, and the ethylenically unsaturated group is present in the side chain. Is obtained. Here, the acid value of the polymer is determined by the amount of monomer having an ethylenically unsaturated group. The acid value is preferably 50 to 150 (mgKOH / g). More preferably, it is 80-130 (mgKOH / g). By setting the acid value within this range, stable development with a wide development allowable range can be achieved. The monomer having an ethylenically unsaturated group referred to here is an epoxy acrylate, and examples thereof include glycidyl acrylate and glycidyl methacrylate.

  Examples of other copolymer components include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, sec-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n- Pentyl acrylate, allyl acrylate, benzyl acrylate, butoxyethyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, 2-ethylhexyl acrylate, glycidyl acrylate, heptadecafluorodecyl acrylate, 2-hydroxyethyl acrylate, isobornyl acrylate , 2-hydroxypropyl acrylate, isodexyl acrylate, iso Cutyl acrylate, lauryl acrylate, 2-methoxyethyl acrylate, octafluoropentyl acrylate, phenoxyethyl acrylate, stearyl acrylate, trifluoroethyl acrylate, allylated cyclohexyl diacrylate, methoxylated cyclohexyl diacrylate, acrylamide, aminoethyl acrylate, phenyl acrylate, Phenoxyethyl acrylate, benzyl acrylate, 1-naphthyl acrylate, 2-naphthyl acrylate, thiophenol acrylate, benzyl mercaptan acrylate, and monomers in which 1 to 5 hydrogen atoms of these aromatic rings are substituted with chlorine or bromine atoms Or styrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, Iodinated styrene, brominated styrene, α-methyl styrene, chlorinated α-methyl styrene, brominated α-methyl styrene, chloromethyl styrene, hydroxymethyl styrene, carboxymethyl styrene, vinyl naphthalene, vinyl anthracene, vinyl carbazole, and , Those obtained by changing some or all of the acrylates of the above compounds to methacrylates, γ-methacryloxypropyltrimethoxysilane, 1-vinyl-2-pyrrolidone, and the like. In the present invention, one or more of these can be used.

  Examples of the composition in which the photosensitive organic component has photocurability include a monomer having an ethylenically unsaturated group, a photoinitiator, and other additives in addition to the polymer. Examples of monomers having an ethylenically unsaturated group include monomers having one or more photopolymerizable unsaturated groups such as a (meth) acrylate group or an allyl group. Specific examples thereof include esters of alcohols (for example, ethanol, propanol, hexanol, octanol, cyclohexanol, glycerin, trimethylolpropane, pentaerythritol, etc.) with acrylic acid (or methacrylic acid), carboxylic acids (for example, acetic acid, Propionic acid, benzoic acid, acrylic acid, methacrylic acid, succinic acid, maleic acid, phthalic acid, tartaric acid, citric acid, etc.) and glycidyl acrylate (or glycidyl methacrylate, allyl glycidyl, or tetraglycidyl metaxylylenediamine) Reaction products, amide derivatives (eg, acrylamide, methacrylamide, N-methylolacrylamide, methylenebisacrylamide, etc.), reaction products of epoxy compounds and acrylic acid (or methacrylic acid). It can be mentioned. These monomers may be polyfunctional monomers. In that case, the unsaturated group may be a mixture of acrylic, methacrylic, vinyl, and allyl groups. These may be used alone or in combination. The monomer content is in the range of 2 to 40% by weight, preferably 5 to 20% by weight, based on the photosensitive ceramic composition. By setting the monomer content within this range, an appropriate crosslinking density can be obtained and sheet flexibility can be maintained.

  The photoinitiator is used alone or as a mixture of several kinds. Benzophenone, methyl o-benzoylbenzoate, 4,4-bis (dimethylamine) benzophenone, 4,4-bis (diethylamino) benzophenone, 4,4-dichloro Benzophenone, 4-benzoyl-4-methyldiphenyl ketone, dibenzyl ketone, fluorenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenyl-2-phenylacetophenone, 2-hydroxy-2-methylpropio Phenone, pt-butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, benzyl, benzyldimethylketanol, benzylmethoxyethyl acetal, Nzoin, benzoin methyl ether, benzoin butyl ether, anthraquinone, 2-t-butylanthraquinone, 2-amylanthraquinone, β-chloroanthraquinone, anthrone, benzanthrone, dibenzosuberone, methyleneanthrone, 4-azidobenzalacetophenone, 2,6 -Bis (p-azidobenzylidene) cyclohexanone, 2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2-phenyl-1,2-butadion-2- (o-methoxycarbonyl) oxime, 1-phenyl -Propanedione-2- (o-ethoxycarbonyl) oxime, 1,3-diphenyl-propanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propanetrione-2- (o-be Nzoyl) oxime, Michler's ketone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, naphthalenesulfonyl chloride, quinolinesulfonyl chloride, N-phenylthioacridone, 4,4-azobisisobuty Photoreductive dyes such as nitrile, diphenyl disulfide, benzthiazole disulfide, triphenylphosphine, camphorquinone, carbon tetrabromide, tribromophenylsulfone, benzoin peroxide and eosin, methylene blue and ascorbic acid, triethanolamine, etc. A combination of reducing agents is exemplified. The addition amount of the photoinitiator is added in the range of 0.05 to 10% by weight, more preferably 0.1 to 5% by weight, with respect to the reactive components such as the photosensitive polymer and the monomer. By setting the addition amount of the photoinitiator within this range, photocuring can be performed up to a deep portion.

  As other additives, it is also effective to add an ultraviolet light absorber composed of an organic dye. A high aspect ratio, high definition, and high resolution can be obtained by adding a light-absorbing agent having a high ultraviolet absorption effect. As the ultraviolet light absorber, an organic dye is used, and among them, an organic dye having a high UV absorption coefficient in a wavelength range of 300 to 450 nm is preferably used. Specifically, azo dyes, amino ketone dyes, xanthene dyes, quinoline dyes, amino ketone dyes, anthraquinone dyes, benzophenone dyes, diphenyl cyanoacrylate dyes, triazine dyes, p-aminobenzoic acid dyes, and the like can be used. . Even when an organic dye is added as a light-absorbing agent, since it does not remain in the insulating film after baking, the deterioration of the insulating film characteristics due to the light-absorbing agent can be reduced. Of these, azo dyes and benzophenone dyes are preferable. The addition amount of the organic dye is preferably 0.01 to 5% by weight with respect to the photosensitive ceramic composition. More preferably, it is 0.05 to 2% by weight. By making the addition amount of the organic dye within this range, it is possible to form a pattern with no fat. An example of a method for adding an ultraviolet light absorber composed of an organic dye is to prepare a solution in which an organic dye is dissolved in an organic solvent in advance, and then mix and dry the inorganic powder in the organic solvent. By this method, a so-called capsule-shaped powder in which an organic film is coated on the surface of each individual powder of inorganic powder can be produced.

  In the present invention, when the inorganic powder contains a metal such as Pb, Fe, Cd, Mn, Co, Mg and its oxide, the inorganic powder and the organic component react with the reactive component contained in the organic component. The mixture (sheet slurry) may gel in a short time, making it impossible to form a sheet. In order to prevent such a reaction, it is preferable to add a stabilizer to prevent gelation. As a stabilizer, a triazole compound is preferably used. Among the triazole compounds, benzotriazole works particularly effectively. As an example of the surface treatment of glass powder with benzotriazole used in the present invention, a predetermined amount of benzotriazole was dissolved in an organic solvent such as methyl acetate, ethyl acetate, ethyl alcohol, and methyl alcohol with respect to the glass powder. Then, it is immersed in the solution for 1 to 24 hours so that the glass powder can be sufficiently immersed. After soaking, it is preferably air-dried at 20 to 30 ° C. to evaporate the solvent and prepare a triazole-treated powder. The proportion of the stabilizer used (stabilizer / inorganic powder) is preferably 0.05 to 5% by weight.

  A sensitizer is added in order to improve sensitivity. Specific examples of the sensitizer include 2,4-diethylthioxanthone, isopropylthioxanthone, 2,3-bis (4-diethylaminobenzal) cyclopentanone, 2,6-bis (4-dimethylaminobenzal) cyclohexanone, 2,6-bis (4-dimethylaminobenzal) -4-methylcyclohexanone, Michler's ketone, 4,4-bis (diethylamino) -benzophenone, 4,4-bis (dimethylamino) chalcone, 4,4-bis (diethylamino) ) Chalcone, p-dimethylaminocinnamylidene indanone, p-dimethylaminobenzylidene indanone, 2- (p-dimethylaminophenylvinylene) -isonaphthothiazole, 1,3-bis (4-dimethylaminobenzal) acetone 1,3-carbonyl-bis (4-diethylamino) Benzal) acetone, 3,3-carbonyl-bis (7-diethylaminocoumarin), N-phenyl-N-ethylethanolamine, N-phenylethanolamine, N-tolyldiethanolamine, N-phenylethanolamine, isoamyl dimethylaminobenzoate , Isoamyl diethylaminobenzoate, 3-phenyl-5-benzoylthio-tetrazole, 1-phenyl-5-ethoxycarbonylthio-tetrazole and the like. In the present invention, one or more of these can be used. Some sensitizers can also be used as photoinitiators. When a sensitizer is added to the photosensitive ceramic composition of the present invention, the addition amount is usually 0.05 to 5% by weight, more preferably 0.1 to 0.1% by weight with respect to reactive components such as photosensitive polymer and monomer. 2% by weight. By setting the amount of the sensitizer within this range, a pattern having an optimum shape can be obtained.

  A polymerization inhibitor is added to improve the thermal stability during storage. Specific examples of the polymerization inhibitor include hydroquinone, monoester of hydroquinone, N-nitrosodiphenylamine, phenothiazine, pt-butylcatechol, N-phenylnaphthylamine, 2,6-di-tert-butyl-p- Examples include methylphenol, chloranil, and pyrogallol. When adding a polymerization inhibitor, the addition amount is 0.001 to 1 weight% normally in the photosensitive ceramic composition.

  The antioxidant is added to prevent oxidation of the acrylic copolymer during storage. Specific examples of antioxidants include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-4-ethylphenol, 2,2-methylene-bis- ( 4-methyl-6-tert-butylphenol), 2,2-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4-bis- (3-methyl-6-tert-butylphenol), 1 , 1,3-Tris- (2-methyl-6-tert-butylphenol), 1,1,3-tris- (2-methyl-4-hydroxy-tert-butylphenyl) butane, bis [3,3-bis -(4-Hydroxy-3-t-butylphenyl) butyric acid] glycol ester, dilauryl thiodipropionate, triphenyl phosphite and the like. When adding antioxidant, the addition amount is 0.001-1 weight% normally in the photosensitive ceramic composition.

  When adjusting the viscosity of the sheet slurry, a solvent may be added to the photosensitive ceramic composition of the present invention. The organic solvent used at this time is methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl ethyl ketone, dioxane, acetone, cyclohexanone, cyclopentanone, isobutyl alcohol, isopropyl alcohol, tetrahydrofuran, dimethyl sulfoxide, γ-butyrolactone, bromobenzene. , Chlorobenzene, dibromobenzene, dichlorobenzene, bromobenzoic acid, chlorobenzoic acid and the like, and organic solvent mixtures containing one or more of these.

The photosensitive ceramic composition of the present invention can be prepared and sheeted as follows. First, a polymer, monomer, and photoinitiator containing an ester of a polyhydric alcohol and an unsaturated carboxylic acid as a copolymerization component, which is a photosensitive organic component, and having an ethylenically unsaturated group in the side chain, and optionally a solvent. And various additives are mixed and then filtered to prepare an organic vehicle. To this, a pretreated inorganic powder is added if necessary, and homogeneously mixed and dispersed by a kneader such as a ball mill to produce a slurry or paste of the photosensitive ceramic composition. The viscosity of the slurry or paste is appropriately adjusted depending on the blending ratio of the inorganic powder and the photosensitive organic component, the amount of the solvent, and the addition ratio of other additives, but the range is preferably 1 to 5 Pa · s. The obtained paste is continuously formed to a thickness of 0.05 to 0.5 mm on a film of polyester or the like by a general method such as a doctor blade method or an extrusion molding method, and the solvent is removed by drying. A green sheet that is a functional ceramic composition is obtained. The via hole is formed by performing pattern exposure through a photomask having a via hole forming pattern on the green sheet, which is the photosensitive ceramic composition, and developing with an alkaline aqueous solution. The light source used for exposure is most preferably an ultra-high pressure mercury lamp, but is not necessarily limited thereto. Exposure conditions vary depending on the thickness of the green sheet, and exposure is performed for 2 to 100 seconds using an ultrahigh pressure mercury lamp having an output of 5 to 100 mW / cm ² . In addition, the alignment guide hole at the time of sheet | seat lamination | stacking can be formed with the same method as the via hole formation. Examples of the alkaline aqueous solution include inorganic alkaline aqueous solutions such as sodium carbonate, sodium hydroxide, and potassium hydroxide, and organic alkaline aqueous solutions such as tetramethylammonium hydroxide, trimethylbenzylammonium hydroxide, monoethanolamine, and diethanolamine. Generally, the concentration of the alkaline aqueous solution is usually 0.05 to 5% by weight, more preferably 0.1 to 3% by weight. By setting the concentration of the alkaline aqueous solution within this range, the allowable development range is widened, and optimal development is possible. The temperature during development is preferably 20 to 50 ° C. for process control. As a developing method, a general dipping method or spray method is used. There is also a method for shortening development time and reducing development unevenness by using ultrasonic waves together.

  In this manner, a sheet having a thickness before firing of 10 to 500 μm, a close-packed via hole pattern portion having a via hole diameter of 20 to 200 μm, and a via hole pitch of 30 to 250 μm can be produced. In the present invention, since the dispersed state of the alumina powder is good, the light transmittance is high, and a high-definition pattern can be formed. Further, the sheet after development is excellent in flexibility and can be prevented from being cracked or chipped in the subsequent process.

  When firing a green sheet formed from a photosensitive ceramic composition, a non-sinterable ceramic sheet may be laminated and fired on the upper and lower surfaces of the green sheet. Thereby, it is possible to shrink only in the thickness direction and almost no shrinkage in the XY plane, but the firing shrinkage rate in the XY plane direction is preferably 1% or less, more preferably 0.5. % Or less, more preferably 0.1% or less.

  The hardly sinterable ceramic is a ceramic powder that does not sinter at the substrate sintering temperature, and can be selected from amorphous silica, quartz, alumina, magnesia, hematite, barium titanate, boron nitride, and the like. Sheets obtained from these materials are referred to as dummy green sheets or restraint sheets. 1 to 5 weights of an oxide powder serving as an adhesion improver with an oxidizing agent such as lead oxide, bismuth oxide, zinc oxide, manganese oxide, barium oxide, calcium oxide, strontium oxide, or glass / ceramic green sheet. % Addition is preferable. As an example of such a hardly sinterable ceramic sheet, there can be mentioned a sheet formed by a doctor blade method by adding polyvinyl butyral, dioctyl phthalate, an appropriate oxide, a solvent or the like to alumina powder. .

  The shrinkage in the XY plane direction is limited by the firing process with the constraining sheets placed on the upper and lower surfaces of the green sheet, but there is inevitable shrinkage depending on the components of the composition, the composition of the composition, and various conditions during firing. To do. For this reason, if the shrinkage rate can be suppressed to 1% or less, it can be considered that almost no shrinkage has been achieved, but more preferably 0.5% or less, and even more preferably 0.1% or less. Such conditions are a coating film formed by screen printing or the like (a method of applying a paste of a photosensitive ceramic composition to a substrate made of ceramics, etc., and in general, the substrate remains as it is and a part of the finished product is left as it is. In the case of a coating film, since the substrate already exists on the lower surface of the film, it can be carried out with a restraint sheet disposed on the upper surface of the film. .

  Next, the sheets on which the necessary number of wiring patterns are formed are stacked using the guide holes, and bonded at a temperature of 80 to 150 ° C. and a pressure of 5 to 25 MPa, thereby producing a multilayer sheet. A constraining sheet composed mainly of an inorganic composition (eg, alumina or zirconia) that does not substantially exhibit sintering shrinkage at the sintering temperature of the green sheet is laminated on both sides of the green sheet laminate. The target multilayer board can be produced by firing the green sheet multilayer body and then performing non-shrink firing to remove the constraining sheet. Firing is performed in a firing furnace. The firing atmosphere and temperature vary depending on the type of inorganic powder and organic component in the photosensitive ceramic composition, but firing is performed in air, in a nitrogen atmosphere, or in a hydrogen reduction atmosphere. Firing of the photosensitive ceramic composition of the present invention is performed at a temperature of 600 to 950 ° C. The ceramic multilayer substrate thus obtained is used as a high-frequency circuit substrate.

  Hereinafter, the present invention will be specifically described with reference to examples. The concentration (%) is% by weight unless otherwise specified. The inorganic powder and photosensitive organic component used in the examples are as follows.

A. Inorganic powder Inorganic powder I:
Composite ceramics alumina: 50% alumina powder + 50% glass powder: average particle size 40 nm
Composition of glass powder: Al ₂ O ₃ (10.8%), SiO ₂ (51.5%), PbO (15.6%), CaO (7.1%), MgO (2.86%), Na ₂ O (3%), K ₂ O (2%), B ₂ O ₃ (5.3%)
Properties of glass powder: glass transition point 565 ° C., thermal expansion coefficient 60.5 × 10 ⁻⁷ / K, dielectric constant 8.0 (1 MHZ), average particle diameter 2 μm
Inorganic powder II: “NKX-592J” (manufactured by Nippon Fellow Co., Ltd.)
Composite ceramics alumina with 50% alumina powder + 50% glass powder: average particle size 2.5 μm
Glass powder: Average particle size 4.8 μm
Composition of glass powder: Al ₂ O ₃ —B ₂ O ₃ —SiO ₂ —CaO-based glass Photosensitive organic component polymer I:
This is an addition reaction of 0.4 equivalent of glycidyl methacrylate to the carboxyl group of a copolymer consisting of 20% ethyl acrylate, 15% methyl acrylate, 35% glyceryl acrylate, and 30% methacrylic acid. 000, acid value 105mgKOH / g
Polymer II:
This is an addition reaction of 0.4 equivalent of glycidyl methacrylate to the carboxyl group of a copolymer consisting of 35% 2-ethylhexyl acrylate, 35% polypropylene glycol methacrylate, and 30% acrylic acid, and has a weight average molecular weight of 16,000, Acid value 110mgKOH / g
Polymer III:
This is an addition reaction of 0.4 equivalent of glycidyl methacrylate to the carboxyl group of a copolymer consisting of 40% styrene, 30% methyl acrylate and 30% methacrylic acid, and has a weight average molecular weight of 13,000, an acid value of 100 mgKOH / g
Photoinitiator: 2-benzyl-dimethylamino-1- (4-monoforinophenyl) -butanone-1
C. Preparation of organic vehicle The solvent and polymer were mixed and heated to 60 ° C. with stirring to dissolve all the polymer. The solution was cooled to room temperature, and a monomer and a photoinitiator were added and dissolved to prepare an organic vehicle.

D. Paste preparation Inorganic powder was mixed with the above-mentioned organic vehicle, and a slurry or paste was obtained by passing three times with three rolls. The amount of the inorganic powder was 70 parts by weight with respect to 30 parts by weight of the photosensitive organic component in the organic vehicle.

E. Production of Green Sheet A green sheet was produced by a doctor blade method at a molding speed of 0.2 m / min, with the distance between the polyester carrier film and the blade set to 0.1 to 0.8 mm in a room where ultraviolet rays were blocked. The thickness of the sheet was 100 μm.

F. Formation of via hole The green sheet was cut into 100 mm square and then dried at a temperature of 80 ° C. for 1 hour to evaporate the solvent. Using a chromium mask with a via diameter of 30 to 100 μm and a via hole pitch of 500 μm, using a super high pressure mercury lamp with an output of 15 to 25 mW / cm ² from the top surface of the sheet, the pattern exposure is performed for 1 minute between the sheet and the mask. did. Next, development was performed with a 0.5 wt% monoethanolamine aqueous solution at 25 ° C., and then the via hole was washed with water using a spray.

G. Production of Restraint Sheet Used at Firing A sheet produced by a doctor blade method by adding polyvinyl butyral, dioctyl phthalate, an organic solvent, or the like to alumina powder, zirconia powder, or magnesia powder was used.

H. Fabrication of Multilayer Substrate Five to six green sheets made of the photosensitive ceramic composition of the present invention were laminated, constraining sheets for non-shrinkage firing were arranged above and below, and thermocompression bonded at 80 ° C. and a press pressure of 15 MPa. The obtained multilayer body was baked in air at a temperature of 900 ° C. for 30 minutes to produce a multilayer substrate.
I. Evaluation of cracks and chips The appearance of cracks and chips was evaluated in the process from development to baking.

Example 1
Inorganic powder I (70%) as the inorganic powder, Polymer I (15%), monomer (10%) (“Aronix M245” manufactured by Toagosei Co., Ltd.) and photoinitiator (0.5%) (“ IC819 “manufactured by Ciba Specialty Chemicals), dispersant (0.3%) (“ Nopcosper ”manufactured by San Nopco Corporation), solvent (4%) (manufactured by“ Solfit ”Kuraray), p-methoxyphenol (0 .2%) to obtain a green sheet having a thickness of 100 μm. When a via hole was formed by photolithography, a 100 μm via hole was formed. After drying, a lamination press was performed together with the alumina constraining sheet. Thereafter, the appearance of cracks was evaluated. As a result, it was good with no cracks.

Example 2
The same composition and trial operation were repeated except that the polymer I of Example 1 was changed to the polymer II. The result was the same as in Example 1 and was good with no cracks.

Comparative Example 1
Inorganic powder I (70%) as the inorganic powder, Polymer III (10%), Polyglycerin (5%) ("Polyglycerin PGL" manufactured by Daicel Chemical Industries, Ltd.), Monomer (10%) (" Aronix M245 (manufactured by Toagosei Co., Ltd.) and photoinitiator (0.5%) ("IC819" manufactured by Ciba Specialty Chemicals), dispersant (0.3%) ("Nopcospers" manufactured by San Nopco Corporation), solvent ( 4%) (manufactured by “Solfit” Kuraray) and p-methoxyphenol (0.2%) were used to obtain a green sheet having a thickness of 100 μm. When a via hole was formed by photolithography, a 100 μm via hole was formed. After drying, a lamination press was performed together with the alumina constraining sheet. After this, when appearance evaluation of cracks was performed, many cracks that were clearly confirmed were generated.
Comparative Example 2
A green sheet having a thickness of 100 μm was obtained by repeating the same composition and trial operation except that the inorganic powder I of Example 1 was changed to the inorganic powder II. A via hole of 100 μm could be formed from the obtained sheet. However, since the transmittance of the sheet is low, photocuring is insufficient and the shape of the via hole is lacking, which is bad.

Claims (3)

In a photosensitive ceramic composition having an inorganic powder and a photosensitive organic component as essential components, the inorganic powder contains an alumina powder having an average particle diameter of 500 nm or less, and the photosensitive organic component is a polyhydric alcohol and ethylenic as a copolymerization component. A photosensitive ceramic composition comprising an ester with an unsaturated carboxylic acid and a polymer having an ethylenically unsaturated group in a side chain. 2. A polymer containing an ester of a polyhydric alcohol and an ethylenically unsaturated carboxylic acid as a copolymerization component and containing 3% by weight to 30% by weight of a polymer having an ethylenically unsaturated group in the side chain. The photosensitive ceramic composition as described. 2. The photosensitive ceramic composition according to claim 1, comprising 5 to 90% by weight of alumina powder having an average particle diameter of 500 nm or less.