JPH07135386A - Formation of pattern on ceramics green sheet - Google Patents

Abstract

PURPOSE:To enhance chemical resistance and dimensional accuracy on a green sheet by imparting photosensitivity to the green sheet itself, curing the green sheet by irradiating with ultraviolet rays, and then forming a pattern of photosensitive paste on the green sheet. CONSTITUTION:A sheet slurry composition containing a ceramic powder, a UV-curing resin composition, and an ultraviolet ray absorbent is applied onto a support and dried thus preparing a ceramics green sheet. The ceramics green sheet is then irradiated with ultraviolet rays and via holes are made therein. Subsequently, a photosensitive paste is applied on the ceramics green sheet and dries before it is selectively exposed and developed to form a pattern. Since the ultraviolet rays are absorbed up to the lower part of the ceramic green sheet, chemical resistance and dimensional accuracy are enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a pattern on a ceramic green sheet which is preferably used for forming a fired ceramic substrate or the like. A ceramics green sheet is a green sheet made of a ceramics that is suitable for use in high-density mounting, in which semiconductor elements are mounted and interconnected with each other, and particularly for a multilayer ceramics board. Further, it is a green sheet effective for forming a fine circuit pattern and a fine via hole of the electrode for the inner layer of the ceramic multilayer substrate.

[0002]

2. Description of the Related Art Multilayer ceramic substrates are mainly manufactured by a green sheet laminating method. The green sheet laminating method is a method of printing a conductor and laminating a large number of green sheets that have been subjected to via hole processing, thermocompression-bonding, and then simultaneously firing to form a multilayer substrate.

Conventional ceramics green sheets are
Japanese Unexamined Patent Publication No. 1-232797 and Japanese Unexamined Patent Publication No. 2-14145
As described in Japanese Patent Publication No. 8, usually, a ceramic powder, an organic binder, a plasticizer, a solvent, and a dispersant, if necessary, are appropriately blended and mixed to form a slurry, and the obtained slurry is a doctor blade method. The green sheet is formed by a known method such as. The obtained green sheet is processed into a desired shape by a cutter or a punching die, and then a via hole or through hole (hereinafter referred to as a via hole) is provided on the green sheet by a die or laser using a punch die. Drilling with. Then, the green sheet is filled with a conductive paste in the via holes by a normal screen printing method.

Further, in JP-A-63-64953 and JP-A-2-204356, a composition containing a ceramic raw material, an ultraviolet curable liquid compound and a photopolymerization initiator is irradiated with ultraviolet rays to be cured. Further, a green sheet containing a bisazide compound has been proposed as a ceramics green sheet or a glass ceramics green sheet.

On the other hand, in order to form a conductor pattern on a green sheet, a screen printing method using a conductive paste has been conventionally used. In this method, L (line width) / S is used.
It is difficult to form a fine pattern of (width interval) = 80 μm / 80 μm or less. Therefore, recently, a photosensitive conductive paste capable of forming a fine conductor pattern by using a photolithography method has been proposed. This photosensitive conductive paste is composed of a paste containing a conductive powder such as copper, gold or tungsten, a photosensitive resin, a photopolymerization initiator and a solvent. The film obtained by applying the paste to the ceramic substrate after firing the paste by the screen printing method is dried, and then the exposed portion is cured by irradiating with ultraviolet rays using a photomask having a circuit pattern. Next, a non-cured portion of the unexposed portion is removed using a developing solution to form a pattern. However, when attempting to form a conductive pattern using a photosensitive conductive paste on a green sheet that has not been fired, the organic solvent and green contained in the conductive paste are not suitable because the green sheet has poor chemical resistance and dissolution resistance. There is a problem that the unexposed portion is very difficult to remove during development because it reacts with the polymer binder in the sheet.

[0006]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for forming a good pattern on a ceramic green sheet by using a photosensitive paste by a photolithography method.

[0007]

The object of the present invention is as follows.
This is achieved by a method of forming a pattern on a ceramics green sheet, which comprises the following steps (1) to (3). (1) A step of applying a sheet slurry composition containing a ceramic powder, a photocurable resin composition, and an ultraviolet absorber on a support and drying it to produce a ceramic green sheet, (2) the ceramic green sheet UV irradiation, and the process of forming a via hole
(3) A step of forming a pattern by applying a photosensitive paste on a ceramic green sheet having a via hole, drying, selectively exposing and developing.

That is, in the present invention, it is important to impart photosensitivity to the green sheet itself made of ceramics. After the photosensitized green sheet is irradiated with ultraviolet rays to be photo-cured, the green sheet is placed on the green sheet. A pattern can be formed with a photosensitive paste.

The sheet slurry composition used in the step (1) of the present invention will be described. The sheet slurry composition contains a ceramic powder, a photocurable resin composition and an ultraviolet absorber.

The ceramic powder used in the present invention is not particularly limited, and any known ceramic insulating material for low temperature firing can be applied.

Examples of the ceramic powder used in the present invention include ceramic powder alone, glass-ceramic composite system, and crystallized glass.

Examples of the ceramic powder used alone include alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ).
₂ ), magnesia (MgO), beryllia (BeO), mullite (3Al ₂ O ₃ .2SiO ₂ ), cordierite (5SiO ₂ .2Al ₂ O ₃ .2MgO), spinel (MgO.Al ₂ O ₃ ), forsterite (2MgO
・ SiO ₂ ), anorthite (CaO ・ Al ₂ O ₃・ 2)
SiO ₂ ), Sergian (BaO ・ Al ₂ O ₃・ 2Si
Examples of the powder include O ₂ ), silica (SiO ₂ ), clinoenstatite (MgO · SiO ₂ ), aluminum nitride (AlN) and the like, or low temperature firing ceramic powder.

Examples of the glass-ceramics composite system include glass composition powder containing SiO ₂ , Al ₂ O ₃ , CaO, B ₂ O ₃ and optionally MgO and TiO ₂ , and alumina, zirconia, magnesia. , Beryllia, mullite, cordierite, spinel, forsterite, anorthite, cergian, silica, and at least one inorganic filler powder selected from the group consisting of aluminum nitride. SiO ₂ more preferably ceramic powder in terms of oxide title 30-70 wt% Al ₂ O ₃ 5~25 wt% CaO 5 to 25 wt% MgO 0 wt% B ₂ O ₃ 3~50 wt% TiO ₂ In the composition range of 0 to 15% by weight, 40 to 60% by weight of glass composition powder with a total amount of 95% by weight or more, and alumina, zirconia, magnesia, beryllia, mullite, cordierite, spinel, forsterite, anorthite, sergian. , A raw material mixture with 60 to 40% by weight of at least one inorganic filler powder selected from the group consisting of silica and aluminum nitride. That is, SiO ₂ , Al ₂ O ₃ , CaO, Mg
The composition range of O, B ₂ O ₃ and TiO ₂ is the ratio in the glass composition powder, and the total amount of these components is preferably 95% by weight or more in the glass composition powder. The remaining 5% by weight is Na ₂ O, K ₂ O, BaO, PbO, Fe ₂ O ₃ ,
It can contain Mn oxide, Cr oxide, NiO, Co oxide and the like.

Specific examples of the glass-ceramic composite system include SiO ₂ —B ₂ O ₃ system glass and PbO—SiO ₂
-Al ₂ O ₃ -B ₂ O ₃ based glass, CaO-SiO ₂ -
Etc. Al ₂ O ₃ -B ₂ O ₃ based glass, Al ₂ O _3, quartz (SiO _2), ZrO _2, is plus a ceramic component such as cordierite and the like.

SiO ₂ in the glass composition powder is 30 to 70.
The content is preferably in the range of wt%, and when it is less than 30 wt%, the strength and stability of the glass layer are lowered, and the dielectric constant and the thermal expansion coefficient are increased, so that the glass layer easily deviates from the desired value. Again 7
When it is more than 0% by weight, the coefficient of thermal expansion of the fired substrate becomes high, and firing at 1000 ° C or lower becomes difficult.

Al ₂ O ₃ is preferably blended in the range of 5 to 25% by weight. If it is less than 5% by weight, the strength in the glass phase is lowered, and the firing at 1000 ° C or lower becomes difficult. If it exceeds 25% by weight, the temperature for fritizing the glass composition becomes too high.

CaO is preferably added in the range of 5 to 25% by weight. If the amount is less than 5% by weight, the desired coefficient of thermal expansion cannot be obtained, and firing at 1000 ° C or lower becomes difficult. When it exceeds 25% by weight, the dielectric constant and the thermal expansion coefficient increase, which is not preferable. MgO is preferably added in the range of 0 to 10% by weight, which facilitates control of the melting temperature of the glass. If it exceeds 10% by weight, the coefficient of thermal expansion of the obtained substrate increases.

B ₂ O ₃ is a glass frit 1300 to 1
Because it melts at temperatures near 450 ° C, and Al ₂ O ₃
In order to control the ceramic firing temperature within the range of 800 to 1000 ° C so as not to impair the electrical, mechanical and thermal properties such as dielectric constant, strength, coefficient of thermal expansion, and sintered density, even if the amount is large. Is preferred, and the amount is preferably in the range of 3 to 50% by weight. If it is less than 3% by weight, the strength of the ceramics tends to decrease if the content of B ₂ O ₃ is too large, and if it exceeds 50% by weight, the stability of the glass tends to deteriorate, and the stability of the glass decreases due to the reaction between the inorganic filler (crystal) and the glass. Crystallization is accelerated, and when a multilayer substrate is formed, a phenomenon in which the glass phase oozes out is not preferable.

TiO ₂ is preferably blended in the range of 0 to 15% by weight. The low temperature fired ceramics substrate of the present invention is a mixture of amorphous glass and inorganic filler before firing, but depending on the kind of filler, it is partially crystallized ceramics of amorphous glass, ceramics and crystallized glass. It is estimated to be. TiO ₂ acts as an effective nucleating substance in the formation of crystallized glass, and is preferably in the above range.

The inorganic filler powder is effective for improving the mechanical strength of the substrate and controlling the thermal expansion coefficient, and particularly alumina, zirconia, mullite, cordierite and anorthite are excellent in the effect. If the proportion of the inorganic filler exceeds 60% by weight, it becomes difficult to sinter and the temperature rises to 1000 ° C.
It becomes difficult to sinter below. On the other hand, if it is less than 40% by weight, it becomes difficult to control the thermal expansion coefficient and obtain a substrate having a low dielectric constant. Therefore, by setting the inorganic filler powder in this range, the firing temperature of the ceramics is 800 to 100.
When the temperature is 0 ° C., strength, dielectric constant, thermal expansion coefficient, sintering density, volume resistivity, and shrinkage can be set to desired characteristics.

In the inorganic filler powder used in the present invention,
As impurities, 0 to 5% by weight of Na ₂ O, K ₂ O,
It may contain BaO, PbO, Fe ₂ O ₃ , Mn oxide, Cr oxide, NiO, Co oxide and the like.

As a method for producing the glass composition powder, for example, the raw materials SiO ₂ , Al ₂ O ₃ , CaO and Mg are used.
O, B ₂ O ₃ , TiO ₂ and the like are mixed so as to have a predetermined composition, melted at 1250 to 1450 ° C., and then rapidly cooled,
There is a method in which a glass frit is formed and then crushed to form a fine powder having a particle size of 0.5 to 3 μm. As the raw material, high-purity carbonate, oxide, hydroxide or the like can be used. Also, depending on the type and composition of glass powder, ultra-high purity alkoxide or organometallic raw material of 99.99% or more is used, and when a powder produced homogeneously by the sol-gel method is used, it has a low dielectric constant and is dense. This is preferable because a ceramic substrate having high strength can be obtained.

As a specific example of the crystallized glass, MgO--
Al ₂ O ₃ -SiO ₂ system and _{Li 2 O-Al 2 O 3} -Si
O ₂ type crystallized glass or the like is used. Crystallized glass is obtained by adding B ₂ O ₃ and a nucleating substance to MgO—Al ₂ O ₃ —SiO ₂ and firing at 900 to 1000 ° C. to precipitate cordierite crystals for high strength.
It is also possible to use Li ₂ O—Al ₂ O ₃ —SiO ₂ to which B ₂ O ₃ and a nucleating substance are added to precipitate spodumene so as to increase the strength.

The particle size and specific surface area of the ceramic powder used in the above are selected in consideration of the thickness of the green sheet to be produced and the shrinkage ratio after firing. In the case of powder, the particle size is 0.2 to 4 μm, Specific surface area ^{2 to} 30 m ²
/ G is preferably satisfied at the same time. A more preferable range is a particle size of 0.5 to 3 μm and a specific surface area of ^{2 to 20} m ² / g. Within this range, light is sufficiently transmitted during exposure to ultraviolet light, and uniform via holes with no difference in the upper and lower hole diameters can be obtained. When the powder particle size is less than 0.2 μm or the specific surface area exceeds 30 m ² / g, the powder becomes too fine and light is scattered during exposure to cure the unexposed portion. Therefore, a via hole having a roundness cannot be obtained during development. Further, the shrinkage rate after firing becomes large, and a highly accurate green sheet cannot be obtained. The shape of the powder is preferably spherical, and if the particle size distribution is sharp, it is possible to suppress the influence of scattering at the time of exposure to ultraviolet light, which is preferable.

As the photocurable resin used for forming the ceramics green sheet of the present invention, conventionally known photocurable resins can be applied. The photosensitive layer made of these photocurable resins is a layer which is insolubilized by irradiation with active light rays. Examples of the photocurable substance are (1) a mixture of a functional monomer or oligomer having one or more unsaturated groups in one molecule with a suitable polymer binder. (2) A mixture of a photosensitive compound such as an aromatic diazo compound, an aromatic azide compound or an organic halogen compound with a suitable polymer binder. (3) A photosensitive polymer obtained by pendant to an existing polymer with a photosensitive group, or a modified product thereof. (4) A so-called diazo resin such as a condensation product of a diazo amine and formaldehyde. And so on.

A particularly preferred photocurable resin composition contains an acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in its side chain, a photoreactive compound and a photopolymerization initiator. The polymer can be produced by adding an ethylenically unsaturated group to the side chain of an acrylic copolymer formed by copolymerizing an unsaturated carboxylic acid and an ethylenically unsaturated compound.

Specific examples of unsaturated carboxylic acids include:
Examples thereof include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetic acid, and acid anhydrides thereof. On the other hand, specific examples of the ethylenically unsaturated compound include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, and n-butyl acrylate. Butyl methacrylate, sec-butyl acrylate, sec-butyl methacrylate, iso-butyl acrylate, isobutyl methacrylate, tert-butyl acrylate,
tert-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, styrene, p-
Examples include, but are not limited to, methylstyrene, o-methylstyrene, m-methylstyrene, and the like. A copolymer having good thermal decomposability can be obtained by including at least methyl methacrylate from the above ethylenically unsaturated compounds as the main polymerization component of these acrylic main chain polymers.

Examples of the side chain ethylenically unsaturated group include vinyl group, allyl group, acryl group and methacryl group. As a method of adding such a side chain to the acrylic copolymer, there is a method of making an addition reaction of an ethylenically unsaturated compound having a glycidyl group and an acrylic acid chloride with a carboxyl group in the acrylic copolymer. .

Examples of the ethylenically unsaturated compound having a glycidyl group include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, glycidyl ethyl acrylate, crotonyl glycidyl ether, crotonic acid glycidyl ether, and isocrotonic acid glycidyl ether. . Examples of acrylic acid chloride compounds include acrylic acid chloride, methacrylic acid chloride, and allyl chloride. The amount of the ethylenically unsaturated compound or acrylic acid chloride added is preferably 0.05 to 1 molar equivalent with respect to the carboxyl group in the acrylic copolymer,
More preferably, it is 0.1 to 0.8 molar equivalent. If the addition amount is less than 0.05 molar equivalent, the photosensitive characteristics become poor and pattern formation becomes difficult, which is not preferable. On the other hand, when the addition amount is larger than 1 molar equivalent, the solubility of the developer in the unexposed area is lowered and the hardness of the coating film is lowered, which is not preferable.

The acid value of the acrylic polymer having a carboxyl group and an ethylenically unsaturated group on the side chain thus obtained (A
V) is preferably 50 to 180, more preferably 70 to
140. More preferably, it is in the range of 80 to 120. When the acid value is less than 50, the amount of ethylenically unsaturated groups increases, and the ratio of photosensitive carboxyl groups decreases, so that the development allowable range is narrow and the edge of the via hole becomes poor. On the other hand, if the acid value exceeds 180, the solubility of the unexposed area with respect to the developing solution will decrease, so if the concentration of the developing solution is increased, peeling will occur even in the exposed area, making it difficult to obtain a via hole with high accuracy. In addition, the hardness of the green sheet decreases. Further, the sharper the molecular weight distribution of the polymer in the polymer having the above-mentioned preferable acid value,
It is preferable because the developing characteristics are improved and fine via holes are obtained.

These photo-curable resins act as a polymer binder, but preferably contain a non-photosensitive polymer as a polymer binder component. It is preferable to contain a non-photosensitive polymer as the polymer binder component because the tensile strength and elongation of the green sheet before exposure can be increased. When the tensile strength is improved, the thickness of the green sheet can be reduced to 20-40 mμ. Specifically, as the non-photosensitive polymer, polyvinyl alcohol, polyvinyl butyral,
Examples thereof include methacrylic acid ester polymers, acrylic acid ester polymers, acrylic acid ester-methacrylic acid ester copolymers, -methylstyrene polymers, and butyl methacrylate resins. Further, when the photosensitive material contains only a photosensitive monomer, it is important to include such a non-photosensitive polymer binder in order to improve the mechanical strength. As a solvent for such a non-photosensitive polymer binder, alcohol, toluene, acetone, methyl ethyl ketone, butanol, methyl isobutyl ketone, isophorone, isopropyl alcohol, etc. are appropriately used. Further, the polymer binder may contain a plasticizer and a dispersant. As the plasticizer, dibutyl phthalate, dioctyl phthalate, polyethylene glycol, glycerin and the like are used. As the dispersant, sorbitan acid ester, alkylene glycol, polycarboxylic acids and the like are preferably used. The content of the non-photosensitive polymer is preferably 5 to 80% by weight of the photosensitive polymer binder. If it is less than 5% by weight, the effect of improving the elongation is low, and if it exceeds 80% by weight, the green sheet is not sufficiently cured even if it is irradiated with ultraviolet rays, so that the green sheet has chemical resistance, dissolution resistance and mechanical strength. Does not improve. When the subsequent via hole formation is not performed by the photolithography method, the content of the non-photosensitive polymer binder is 6 to 1
5% by weight is sufficient. Specific examples thereof include polyvinyl alcohol, polyvinyl butyral, methacrylic acid ester polymer, acrylic acid ester polymer, acrylic acid ester-methacrylic acid ester copolymer, -methylstyrene polymer, and butyl methacrylate resin.

The photoreactive compound used in the present invention is a compound having a carbon-carbon unsaturated bond having photoreactivity, and specific examples thereof include allyl acrylate, benzyl acrylate, butoxyethyl acrylate, Butoxytriethylene glycol acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, 2-ethylhexyl acrylate, glycerol acrylate, glycidyl acrylate, heptadecafluorodecyl acrylate, 2
-Hydroxyethyl acrylate, isobonyl acrylate, 2-hydroxypropyl acrylate, isodexyl acrylate, isooctyl acrylate, lauryl acrylate, 2-methoxyethyl acrylate, methoxyethylene glycol acrylate, methoxydiethylene glycol acrylate , Octafluoropentyl acrylate, phenoxyethyl acrylate, stearyl acrylate, trifluoroethyl acrylate, allylated cyclohexyl diacrylate, bisphenol A diacrylate, 1,4-butanediol diacrylate, 1,3-butylene glycol di Acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene Glycol diacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, ditrimethylol propane tetraacrylate, glycerol diacrylate, methoxylated cyclohexyl diacrylate, neopentyl glycol diacrylate, propylene glycol diacrylate Acrylate, polypropylene glycol diacrylate, triglycerol diacrylate,
Trimethylolpropane triacrylate and the above acrylates replaced by methacrylates, γ-methacryloxypropyltrimethoxysilane, 1-vinyl-
2-pyrrolidone and the like can be mentioned. In the present invention, these may be used alone or in combination of two or more. An acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in its side chain is usually used in a weight ratio of 0.
The amount used is 1 to 10 times, preferably 0.5 to 5 times. If the amount of the acrylic copolymer is too small, the viscosity of the slurry becomes small, and the uniformity of dispersion in the slurry may be deteriorated. On the other hand, if the amount of the acrylic copolymer is too large, the solubility of the unexposed area in the developer becomes poor.

Specific examples of the photopolymerization initiator used in the present invention include benzophenone, methyl o-benzoylbenzoate, 4,4-bis (dimethylamine) benzophenone, 4,4-bis (diethylamino) benzophenone,
4,4-dichlorobenzophenone, 4-benzoyl-4
-Methyldiphenylketone, dibenzylketone, fluorenone, 2,2-diethoxyacetophenone, 2,2-
Dimethoxy-2-phenyl-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, p
-T-butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, benzyl, benzyldimethylketanol,
Benzyl-methoxyethyl acetal, benzoin, benzoin methyl ether, benzoin butyl ether,
Anthraquinone, 2-t-butyl anthraquinone, 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
-Benzoyl) oxime, Michler-ketone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, naphthalenesulfonyl chloride,
Quinoline sulfonyl chloride, N-phenylthioacridone, 4,4-azobisisobutyronitrile, diphenyl disulfide, benzthiazole disulfide, triphenylphosphine, camphorquinone, carbon tetrabromide, tribromophenyl sulfone, benzoin peroxide And a combination of a photoreducing dye such as eosin and methylene blue and a reducing agent such as ascorbic acid and triethanolamine. In the present invention, these may be used alone or in combination of two or more.

The photopolymerization initiator is added in the range of 0.1 to 50% by weight based on the sum of the acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in the side chain and the photoreactive compound. More preferably, it is 2 to 25% by weight. If the amount of the polymerization initiator is too small, the photosensitivity becomes poor, and if the amount of the photopolymerization initiator is too large, the residual rate of the exposed area may be too small.

In the present invention, the sheet slurry composition is treated with ultraviolet rays (UV) to effectively cure the green sheet with ultraviolet rays or to form a via hole.
It is important to add a light absorber. High resolution can be obtained by adding a light absorber having a high ultraviolet absorption effect.

That is, with the ceramic powder alone, the ultraviolet rays are scattered by the ceramic powder, and the excess portion is photo-cured, and the via hole cannot be formed well even if developed. As a result of diligent investigations by the present inventors regarding this cause, it has been found that the cause is that scattered ultraviolet light is absorbed or weakened and reaches the light-shielding portion by the exposure mask. Therefore, by adding the ultraviolet absorber, the scattered light is prevented from wrapping around, the photosensitive resin in the mask portion is prevented from being hardened, and a pattern corresponding to the exposure mask is formed. In addition, light penetrates to the lower part of the green sheet without being absorbed, and the function of light curing is sufficiently satisfied, and a highly accurate via hole can be formed.

If there is no ultraviolet absorber, even if the sheet is irradiated with ultraviolet rays, it will be reflected by the ceramic powder,
The chemical resistance and mechanical strength of the green sheet are hardly improved because they are scattered and only a part of the surface of the sheet is hardened.Moreover, the green sheet is bent or warped after being irradiated with ultraviolet rays, and high dimensional accuracy is ensured. The required green sheet cannot be obtained, and the mechanical strength becomes low. However, when a light absorber is added, ultraviolet rays can be effectively absorbed and reach the bottom of the green sheet, so that the inside of the sheet is uniformly photo-cured and the chemical resistance of the green sheet,
The dimensional accuracy is improved and the mechanical strength is greatly improved.
In particular, the tensile strength usually increases by 2 to 5 times.

350 to 450 nm as an ultraviolet absorber
Organic dyes having a high UV absorbance in the wavelength range of are preferably used. As the organic dye, various dyes having high absorbance can be used, and azo dyes, aminoketone dyes, xanthene dyes, quinoline dyes, aminoketone dyes, anthraquinone dyes and the like can be used. Among these, azo dyes are particularly preferable. Organic dyes are
Even when it is added as a light absorber, it does not remain in the substrate after firing because it evaporates during firing, and therefore, there is no reduction in insulation resistance due to the light absorber, which is preferable.

Typical examples of azo dyes include:
Sudan Blue (C ₂₂ H ₁₈ N ₂ O
₂ = 342.4), Sudan R (C ₁₇ H ₁₄ N ₂ O ₂ = 27
8.31), Sudan _{II (C 18 H 14 N 2} O = 276.3
4), Sudan III (C ₂₂ H ₁₆ N ₄ O = 352.4), Sudan IV (C ₂₄ H ₂₀ N ₄ O = 380.45), Oil Orange SS (Oil Orange SS, CH ₃ C ₆ H)
₄ N: NC ₁₀ H ₆ OH = 262.31) Oil Violet (C ₂₄ H ₂₁ N ₅ = 379.
46), Oil Yellow OB (Oil Yellow)
_{OB, CH 3 C 4 H 4} N: NC 10 H 4 NH 2 = 261.
33) and the like, but a dye capable of absorbing at 250 to 520 nm can be used.

The amount of the organic dye added is such that the photo-curing of the green sheet is effectively performed to improve the mechanical strength and chemical resistance, and the roundness of the via hole is high, and the upper and lower portions after forming the via hole. Is a range that satisfies the conditions such as a small difference in via hole diameter with respect to ceramics, and does not deteriorate the bending strength, the insulation resistance, the dielectric constant, the thermal expansion characteristics, etc., which are the characteristics of the ceramic substrate after firing. 0.05 to 2% by weight is preferable. If it is less than 0.05% by weight, the effect of adding an ultraviolet absorber will decrease, and it will be 2% by weight.
If it exceeds the above range, the amount of the light absorber is too large, and when it is irradiated with ultraviolet rays, it is absorbed by the ceramic powder until it reaches the bottom, and the formation of via holes is poor and the green sheet is not evenly photo-cured to the inside. It is not preferable because the chemical resistance decreases. Further, the substrate characteristics after firing are also deteriorated, which is not preferable. More preferably 0.10
It is 0.7% by weight.

As a method of adding the ultraviolet light absorber composed of an organic dye, the following method is preferable. That is, a solution in which an organic dye is previously dissolved in an organic solvent is prepared. Next, the ceramic powder is mixed with the organic solvent and dried with stirring. By this method, a so-called capsule-like powder can be produced in which the surface of each ceramic powder is uniformly coated with an organic dye film.

In the present invention, there is a preferred range of integrated value of absorbance (350 to 450 nm). That is, the integrated value of the absorbance is measured in a powder state, and is measured for an organic dye or a powder obtained by coating the surface of an inorganic powder with an organic dye.

In the present invention, the absorbance is defined as follows. That is, using a commercially available spectrophotometer, light is applied to a measurement sample in an integrating sphere, and the light reflected there is collected and detected. Further, except for the light detected by the integrating sphere, all the light is regarded as absorbed light and is calculated from the following formula.

The light intensity of the control light was set to Ir (Ir is the BaSO ₃ of the same material as the material coated on the inner surface of the integrating sphere, was attached to the sample stage before measuring the absorbance of the sample, and the light intensity by reflection was measured. Data) If the light intensity of the light incident on the sample is I and the light intensity of the absorbed light after hitting the sample is Io, the light intensity of the reflected light from the sample is represented by (I-Io), and the absorbance is It is defined as the following formula (1). In the above, the unit of light intensity is W / cm ² .

Absorbance = −log ((I−I ₀ ) / Ir) (1) The absorbance is measured as follows. 1. 20mm diameter of powder with light absorber added,
Mold to a size of 4 mm. 2. Next, a spectrophotometer is used to attach a powder molding to the attachment port of the reflecting sample of the integrating sphere, and the absorbance due to the reflected light is measured in the wavelength range of 200 to 650 nm. A graph as shown in FIG. 1 is obtained. The vertical axis represents the absorbance of formula (1), and the horizontal axis represents the measurement wavelength. 3. Next, in FIG.
It is divided into 10 sections for each m, and the area for each section is obtained. The area is calculated as follows.

For example, the absorbance at 350 nm is 0.75, the absorbance at 360 nm is 0.80, the absorbance at 370 nm is 0.85, ... The absorbance at 440 nm is 0.60, the absorbance at 450 nm is 0. .55, assuming that the area of the 350-360 nm portion is A and assuming a trapezoid, A is calculated as follows. Area A = (0.75 + 0.80) × 10/2 = 7.75 Similarly, Area B is Area B = (0.80 + 0.85) × 10/2 = 8.25 .... Similarly, Area J is Area J = (0.60 + 0.55) × 10/2 = 5.75. The total area S of the 10 sections is calculated as follows. S = A + B + C + ... + J The area S was defined as the integrated value of the absorbance at 350 to 450 nm.

In the present invention, after the via hole is formed by the photolithography method, the integrated value of the absorbance in the case of forming a pattern with a photosensitive paste (photosensitive conductive paste, insulating paste, dielectric paste or resistor paste) A preferred range is 20 to 100, and a more preferred range is 30 to 70. If the integrated value of the absorbance is less than 20, the light will be scattered by the powder before it is sufficiently transmitted to the bottom of the green sheet during ultraviolet exposure, and the unexposed portion will be cured, thereby forming a via hole with a roundness. become unable. If the absorbance exceeds 100, the light will be absorbed by the powder before it reaches the lower part of the green sheet, and the light will not be transmitted to the lower part of the sheet, so that the photo-curing cannot be performed. As a result, peeling occurs during development, making it difficult to form via holes.

In the present invention, when a pattern is formed with a photosensitive conductive paste using a green sheet in which a via hole is formed by punching with a super hard drill, the integrated value of absorbance is preferably 10 to 150. It is sufficient that only the surface layer of the green sheet is photo-cured by the irradiation of ultraviolet rays, but if it is less than 10, the ultraviolet rays are reflected and scattered by the powder and the photo-curing is not sufficiently performed. Further, if it exceeds 150, ultraviolet rays are absorbed by a part of the surface and chemical resistance and mechanical strength are not improved, which is not preferable.

In the present invention, the metal such as Pb, Bi, Fe, Ni, Mn, Co and Mg contained in the ceramic powder and its oxide react with the carboxyl group of the photosensitive polymer contained in the paste to form the paste. It may gelate in a short time and become lumps, making it impossible to print as a paste. It is presumed that this is an ionic cross-linking reaction between the polymer and the above-mentioned metal or oxide powder. It is preferable to prevent gelation by adding a compound (stabilizer) that does not adversely affect the agent or the plasticizer. That is, the powder is surface-treated with a compound having an effect of complexing with a metal or an oxide powder that causes a gelation reaction, or forming a salt with an acid functional group to stabilize the photosensitive green sheet. A triazole compound can be preferably used as such a stabilizer. Among the triazole compounds, benzotriazole works particularly effectively. Hexamethylenetetramine and lithium naphthenate are also effective in suppressing gelation.

The method of surface-treating the ceramic powder using benzotriazole is as follows. That is, a predetermined amount of benzotriazole is added to the ceramic powder with methyl acetate, ethyl acetate, ethyl alcohol,
It is dissolved in an organic solvent such as methyl alcohol and soaked in the solution for 1 to 24 hours so that these powders can be sufficiently immersed. After the immersion, the powder is naturally dried at preferably 20 to 30 ° C. to evaporate the solvent to prepare a triazole-treated powder.

The proportion of the stabilizer used in the present invention (stabilizer / ceramic powder) is preferably 0.2 to 4% by weight, and more preferably 0.4 to 3% by weight. If it is less than 0.2% by weight, it is ineffective in preventing the crosslinking reaction of the polymer and gels in a short time. On the other hand, if it exceeds 4% by weight, the amount of the stabilizer becomes too large and it becomes difficult to remove the binder such as the polymer, the monomer and the stabilizer during the firing of the green sheet in the non-oxidizing atmosphere, and the characteristics of the substrate deteriorate. To do.

In the present invention, a sensitizer, a sensitization aid, a thermal polymerization inhibitor, a plasticizer, an antioxidant, a dispersant, an organic or inorganic precipitation preventive agent is added to the ceramic green sheet (in the sheet slurry composition). It is also preferable to add an agent or the like.

The sensitizer is added to improve the sensitivity. Specific examples of the sensitizer include 2,4-diethylthioxanthone, isopropylthioxanthone, 2,3-bis (4-diethylaminobenzal) cyclopentanone,
2,6-bis (4-dimethylaminibenzal) cyclohexanone, 2,6-bis (4-dimethylaminobenzal) -4-methylcyclohexanone, Michler-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-diethylaminobenzal) acetone,
3,3-carbonyl-bis (7-diethylaminocoumarin), N-phenyl-N-ethylethanolamine, N
-Phenylethanolamine, N-tolyldiethanolamine, N-phenylethanolamine, dimethylaminobenzoic acid isoamyl, diethylaminobenzoic acid isoamyl, 3-phenyl-5-benzoylthio-tetrazo-
Razole, 1-phenyl-5-ethoxycarbonylthio-tetrazole and the like can be mentioned. In the present invention, these may be used alone or in combination of two or more. Some sensitizers can also be used as photopolymerization initiators. When the sensitizer is added to the ceramic green sheet of the present invention, the addition amount is usually 0 with respect to the sum of the acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in the side chain and the photoreactive compound. 0.1 to 30% by weight, more preferably 0.5 to 15% by weight. If the amount of the sensitizer is too small, the effect of improving the photosensitivity is not exhibited, and if the amount of the sensitizer is too large, the residual ratio of the exposed area may be too small.

The thermal polymerization inhibitor is added to improve the thermal stability during storage. Specific examples of the thermal polymerization inhibitor include hydroquinone, N-nitrosodiphenylamine, phenothiazine, pt-butylcatechol, N-.
Phenylnaphthylamine, 2,6-di-t-butyl-p
-Methylphenol, chloranil, pyrogallol and the like. When the thermal polymerization inhibitor is added, the addition amount is relative to the sum of the acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in the side chain and the photoreactive compound,
Usually, 0.1 to 20% by weight, more preferably 0.5 to
It is 10% by weight. If the amount of thermal polymerization inhibitor is too small,
The effect of improving thermal stability during storage is not exhibited,
If the amount of the thermal polymerization inhibitor is too large, the residual ratio of the exposed area may be too small.

Specific examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, polyethylene glycol and glycerin.

The antioxidant is added to prevent oxidation of the acrylic copolymer during storage. Specific examples of the antioxidant include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-4-ethylphenol, 2,2-methylene-bis. -(4-methyl-6-t-butylphenol), 2,2
-Methylene-bis- (4-ethyl-6-t-butylphenol), 4,4-tibis- (3-methyl-6-t-butylphenol), 1,1,3-tris- (2-methyl-6-). t-butylphenol), 1,1,3-tris-
(2-methyl-4-hydroxy-t-butylphenyl)
Butane, bis [3,3-bis- (4-hydroxy-3-
t-Butylphenyl) butyric ascid] glycol ester, dilauryl thiodipropionate, triphenyl phosphite and the like. When an antioxidant is added, its amount is usually relative to the total amount of ceramic powder, an acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in the side chain, a photoreactive compound and a photopolymerization initiator. 0.01-5% by weight, more preferably 0.1.
It is 1 to 1% by weight. If the amount of the antioxidant is small, the effect of preventing the oxidation of the acrylic copolymer during storage cannot be obtained, and if the amount of the antioxidant is too large, the residual ratio of the exposed area may be too small.

The composition of the sheet slurry composition in the present invention is preferably selected within the following range.

(A) Ceramic powder; (a),
80 to 94% by weight based on the sum of (b) (b) Acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in the side chain and a photoreactive compound;
20 to 6% by weight based on the sum of (a) and (b) (c) Photopolymerization initiator; 2 to 25 based on (b)
Weight% (d) UV absorber; 0.05 relative to (a)
-4 wt% More preferably in the above, the composition of the components (a), (b) and (d) is 84-92 wt%, 16-
It is preferable to select in the range of 8% by weight and 0.1 to 1% by weight. When it is in this range, ultraviolet rays are well transmitted at the time of exposure, the function of photocuring is sufficiently exhibited, chemical resistance and dissolution resistance at the time of subsequent development are improved, and generation of a residual film in an unexposed portion is eliminated, L (line width) / S (width interval) = 20 μm / 2
It becomes possible to form a fine pattern of 0 μm. Further, particularly by setting the total amount of the acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in the side chain which is the component (b) and the photoreactive compound within this range, the sintered body after firing becomes dense. Therefore, there is an advantage that a high-strength ceramic substrate can be obtained.

A sheet slurry composition for a green sheet of the present invention is prepared by dissolving an acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in a side chain and a photopolymerization initiator in a photoreactive compound to prepare a solution. It can be manufactured by dispersing ceramic powder and an ultraviolet absorber in the above. When the acrylic copolymer having an ethylenically unsaturated group in the side chain and the photopolymerization initiator do not dissolve in the photoreactive compound or when it is desired to adjust the viscosity of the solution, the acrylic copolymer, the photopolymerization initiator Alternatively, an organic solvent that can dissolve the mixed solution of the photoreactive compound may be added. The organic solvent used at this time may be one that can dissolve the mixture of the acrylic copolymer having an ethylenically unsaturated group in the side chain, the photopolymerization initiator and the photoreactive compound. For example, methyl cellosolve, ethyl cellosolve, butyl cellosolve,
Methyl ethyl ketone, dioxane, acetone, cyclohexanone, cyclopentanone, isobutyl alcohol,
An organic solvent mixture containing isopropyl alcohol, tetrahydrofuran, dimethylsulfoxide, γ-butyrolactone, etc., or one or more of them is used.

Further, if necessary, an organic solvent, a stabilizer, a sensitizer, a thermal polymerization inhibitor, a plasticizer, an antioxidant, a dispersant, an organic or inorganic precipitation inhibitor, etc. are added, and a ball mill or an atto is added. Grind and mix with a lighter for, for example, 12 to 48 hours to prepare a slurry. Further, if air bubbles remain in the slurry, it becomes a defect after forming the sheet, so it is preferable to remove the air bubbles by using a defoaming machine.

Further, the above-mentioned solvent is added as necessary in order to adjust the viscosity of the slurry. Preferred viscosity is 1
000 to 5000 cps (centimeter poise)
Within this range, the film thickness of the sheet can be adjusted uniformly.
The slurry is continuously formed into a thickness of 10 μm to 600 μm on a polyester film using a doctor blade.
At this time, it is necessary to perform the powder blending and molding steps at a place where the ultraviolet rays can be blocked. Otherwise, the green sheet will be photo-cured by ultraviolet rays, and a sheet that can exert the effects of the present invention cannot be obtained. Then 80-120 ℃
Heat at the temperature to evaporate the solvents and form a sheet. This sheet is cut into a predetermined shape.

The thickness of the ceramic green sheet of the present invention is usually in the range of 10 to 600 μm, preferably 30 to 300 μm. If it exceeds 600 μm, it does not sufficiently transmit the exposure to ultraviolet rays, and the effect of photocuring is weakened. On the other hand, if it is less than 10 μm, the handling of the green sheet becomes difficult, and it becomes difficult to form a dense substrate after firing, which deteriorates the characteristics of the ceramic substrate, which is not preferable. Within this range, there is an advantage that a via hole or a through hole having a diameter of 0.01 to 0.2 mm can be formed without causing a difference in upper and lower hole diameters. Although the resolution of the via hole varies depending on the thickness of the green sheet, it is preferable that the aspect ratio is 1 or less because ultraviolet rays are sufficiently transmitted. When the thickness is 40 μm, it is preferable to form a via hole of 40 μm.

Subsequently, the ceramic green sheet is irradiated with ultraviolet rays and a via hole is formed. This step may be performed by a photolithography method in which a via hole is formed by selective irradiation with ultraviolet rays or development, or a via hole is formed by a punching method using a carbide drill,
Before or after the step, at least the surface of the ceramic green sheet may be photo-cured by irradiation with ultraviolet rays.

When a via hole is formed in the ceramic green sheet by the photolithography method,
As a light source of ultraviolet rays used for exposure, for example, a low pressure mercury lamp, a high pressure mercury lamp, a halogen lamp, a germicidal lamp or the like can be used. Of these, an ultra-high pressure mercury lamp is preferable. The exposure conditions vary depending on the thickness of the green sheet, but 5
Using an ultra-high pressure mercury lamp with an output of ~ 100 mW / cm ² 1
It is preferable to perform exposure for 30 minutes. The exposure method can be appropriately selected according to the thickness of the green sheet, but when the thickness exceeds 200 μm and the aspect ratio (sheet thickness / via hole diameter) is 0.2 to 1, there is no difference in the upper and lower hole diameters when both sides are exposed. It is preferable because a via hole can be formed. After exposure, development is performed using a developing solution. Development is
The immersion method or spray method is used. As the developing solution, an organic solvent capable of dissolving the mixture of the acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in the side chain, the photoreactive compound and the photopolymerization initiator can be used. Further, water may be added to the organic solvent within the range in which the dissolving power is not lost. When the side chain of the acrylic copolymer has a carboxyl group, it can be developed with an aqueous alkali solution. As the alkaline aqueous solution, a metallic alkaline aqueous solution such as sodium hydroxide or calcium hydroxide aqueous solution can be used,
It is preferable to use an organic alkaline aqueous solution because the alkaline component can be easily removed during firing. Specific examples of the organic alkali include tetramethylammonium hydroxide, trimethylbenzylammonium hydroxide, monoethanolamine, diethanolamine and the like. The concentration of the alkaline aqueous solution is usually 0.01 to 5% by weight,
It is more preferably 0.1 to 1% by weight. If the alkali concentration is too low, the unexposed area is not removed. If the alkali concentration is too high, the exposed area may be peeled off and corroded.

When the via hole is formed by the punching method using a super hard drill, the green sheet is photo-cured before or after the via-hole. In that case, the entire surface is exposed to ultraviolet rays and at least the surface is photo-cured. The thickness of the cured layer on the surface of the green sheet after light irradiation is at least 5 μm
The above is all you need. It is preferably 10 μm or more. 5μ
If it is less than m, the cured layer has a small thickness and the chemical resistance is lowered, resulting in poor development of the unexposed portion, which makes it difficult to form a fine conductor pattern. The exposure amount may be 20% or more of the case of forming a via hole by the photolithography method. The exposure amount varies depending on the thickness of the sheet and the content ratio of the ultraviolet light absorber, but is preferably in the range of ^{20 to} 1000 mJ / cm ² . In this range, the tensile strength after photocuring is 2 to 6
It is preferable because it doubles and the chemical resistance of the sheet is improved.

The diameter of the via hole is 0.005 to 0.2.
mm, and the via hole pitch is 0.01 to
It is about 5.0 mm.

The preparation, printing, exposure and development steps of the green sheet of the present invention need to be carried out at a place where ultraviolet rays can be blocked. Otherwise, the slurry or the green sheet will be photo-cured by ultraviolet rays, and the green sheet having the effect of the present invention cannot be obtained.

After irradiating the ultraviolet rays and forming the via holes in this way, printing, squeegee,
Copper, by embedding method such as dispenser or roller, or by photolithography method (in this case, it can also be performed at the same time as the subsequent conductor pattern formation)
A conductor paste such as silver, gold, silver-palladium, tungsten, or molybdenum is filled to form conductors for connecting the layer intervals of the wirings in the via holes.

Embedding of the conductive paste into the via holes of the green sheet is repeated for each number of layers.

The present invention is characterized in that a pattern is formed by using a photosensitive paste on the ceramic green sheet in which the via holes are formed in this way. As the photosensitive paste, a photosensitive conductive paste, a photosensitive resistor paste, a photosensitive dielectric paste, a photosensitive insulating paste or the like is used. These contain a conductor powder, a resistor powder, a dielectric powder, an insulator powder, and a photosensitive resin composition, respectively.

As the conductor powder, Cu, Au, Ag,
Examples include metals such as Pd, Pt, W, and Mo, or alloys containing these.

As the Cu-based conductor powder, Cu (97-
70) -Ag (30-30), Cu (95-60) -N
i (5-40), Cu (90-70) -Ag (5-2
0), Cr (3-15) (above () represents weight%.
The same applies hereinafter) and binary metal powders and ternary metal powders are preferably used. Among the above, Cu-Ag powder is preferable, and among them, a powder in which the surface of Cu is coated with 3 to 30% by weight of Ag is particularly preferable because it can suppress the oxidation of Cu.

As the Au, Ag, Pd, Pt-based conductor powder, Ag (30-80) -Pd (70-20), Ag
(40-70) -Pd (60-10) -Pt (5-2
0), Ag (30-80) -Pd (60-10) -Cr
(5-15), Pt (20-40) -Au (60-4
0) -Pd (20), Au (75-80) -Pt (25
-20), Au (60-80) -Pd (40-20),
Ag (40-95) -Pt (60-5), Pt (60-
90) -Rh (40-10) (the above () represents weight%) and the like, binary mixed ternary mixed noble metal powders are preferably used. Among the above, those to which Cr or Rh is added are particularly preferable because the high temperature characteristics can be improved.

As the W, Mo-based conductor powder, W, W
(92-98) -TiB ₂ (8-2), W (92-9)
8) -ZrB ₂ (2-8), W- (92-98) -Ti
_{B 2 (1-7) -ZrB 2 (} 1-7), W (95-6
0) -TiN (5-60), W (90-60) -TiN
(5-35) -TiO ₂ (2-10), W (90-6
0) -TiN (5-35) -TiO ₂ (2-10) -N
i (1-10), W (99.7-97) -AlN (0.
3-3), W (10-90) -Mo (90-10), W
(92-98) -Al ₂ Y ₂ O ₃ (8-2), Mo, M
o (92-98) -TiB ₂ (8-2), Mo (92-
98) -ZrB ₂ (8-2), Mo (92-8) -Ti
B ₂ (1-7) -ZrB ₂ (1-7), Mo-TiN,
Mo (90-60) -TiN (5-35) -TiO
₂ (2-10), Mo (90-60) -TiN (5-3
_{5) -TiO 2 (2-10) -Ni} (1-10), Mo
(99.7-97) -AlN (0.3-3), Mo (6
0-90) -Mn (40-10) -SiO ₂ (0-2
0), W (30-90) -Mo (30-70) -Mn
Binary and ternary mixed metal powders such as (3-30) are preferably used. Among the above, TiB ₂ , ZrB ₂ , T
Those to which iN, AlN, Ni, and TiO ₂ are added are particularly preferable because they have the effects of improving the adhesive strength between the conductor film and the alumina substrate and lowering the resistance of the conductor film.

As the resistor powder, RuO ₂ and RuO _{2 are used.}
System, glass powder containing Al powder and B ₂ O ₃ , A
1 powder, glass powder containing transition metal powder and B ₂ O ₃ , In ₂ O ₃ system-glass powder, RuO ₂ -glass powder, LaB ₆ -glass powder, SnO ₂ additive-glass powder, silicide-glass powder, NiO and Li ₂ O ₃ -B ₂ O
Examples thereof include glass powders composed of _3- SiO ₂ -RO (R is a kind selected from Mg, Ca, Sr, and Ba) and the like.

RuO ₂ is an amorphous or crystalline system, or CdBiRu called a pyrochlore compound.
₂ O ₇ , BiRu ₂ O ₇ , BaRuO ₅ , LaRu
It may be O ₃ , SrRuO ₃ , CaRuO ₃ , Ba ₂ RuO ₄ , or the like. The RuO ₂ system includes RuO ₂ —SiO ₂
Can be used.

The glass powder containing Al powder and B ₂ O ₃ is 4 to 15% by weight of Al and 96 to 85% by weight of the glass powder containing B ₂ O ₃ . The glass powder containing _{B 2 O 3, B 2 O} 3 -BaO-Si
_{O 2 -Ta 2 O 5 -Al 2} O 3 -CaO-MgO based and the like. MoSi ₂ , AlSi ₂ , WSi
₂ , a metal silicide such as TiSi ₂ may be included.

The Al powder, the transition metal powder and the glass powder containing B ₂ O ₃ include the above Al powder and B
_In addition to the glass powder containing ₂ O ₃ , Nb, V, W,
It contains a transition metal powder such as Mo, Zr, Ti and Ni.

In ₂ O ₃ system-glass powder is 30-80.
An example thereof is one composed of a wt% In ₂ O ₃ system and 70 to 20 wt% of glass powder. As an In ₂ O ₃ system,
ITO (In ₂ O ₃ doped with Sn), In ₂
O ₃ and Sb-doped SnO ₂ + SnO ₂ are included. Further, as the glass powder, SiO ₂ —Al ₂ O
_{3 -MgO-ZnO-B 2 O} 3 -BaO -based, and the like.
Of these, the SiO ₂ —B ₂ O ₃ system is preferable because it can be sintered at a low temperature.

RuO ₂ -Glass powder, LaB ₆ -Glass powder, SnO ₂ -added product-Glass powder or silicide-Glass powder used for the glass powder is 90 to 30 in total.
% By weight, the composition is 10 to 30% by weight of Al ₂ O ₃ , B
₂ O ₃ 6-30% by weight, SiO ₂ 10-45% by weight, C
aO 5 to 40% by weight, ZnO 15 to 50% by weight,
The balance is 10 to 70% by weight of RuO ₂ , LaB ₆ and SnO.
₂ Additives or silicides.

Examples of the dielectric powder include a lead-based powder and a barium titanate-based powder. Most of these except the TiO ₂ are of the ABO ₃ type called the perovskite structure. The characteristic is that the composition can be constantly controlled by the stoichiometric ratio.

[0082] As the powder relative to the lead, lead titanate PbTiO _3, lead tungstate PbWO _3, zinc, lead PbZnO _3, Tetsusan'namari PbFeO _3, magnesium lead PbMgO _3, lead niobate PbZbO _3, nickel Lead oxide PbNiO ₃ , lead zirconate PbZrO ₃ , composite perovskite-based dielectrics, titanium oxide TiO _{2 and the} like can be mentioned. Typical dielectric powders include Pb.
_{(Fe x W (1-x} )) O 3 -Pb (Fe y Nb (1-y)) O
_{3, PbTiO 3 -Pb (Mg x} Nb (1-x)) O 3, P
_{b (Zn x Nb (1 x} )) O 3 -BaTiO 3, Pb (Z
_{n x Nb (1-x)} ) O 3 -Pb (Fe y W (1-y)) O 3 -
_{Pb (Fe z Nb (1-} z)) O 3, Pb (Zn x Nb
_{(1-x)) O 3} -PbTiO 3 -BaTiO 3, Pb (M
_{g x W (1-x)} ) O 3 -PbTiO 3 -PbZrO 3, P
b (Mg _x Nb _(1-x) O ₃ -PbTiO ₃ -Pb (Mg
_{y W (1-y))} O 3, Pb (Mg x W (1-x)) O 3 -Pb
(Zr _y TiO _(1-y) ) O ₃ + ZnO, Pb (Mg _x N
_{b (1-x)) O} 3 -PbTiO 3 -PbO, Pb (Fe x
_{Nb (1-x)) O} 3 -Pb (Mg y Nb (1-y)) O 3,
Binary or ternary compound perovskite compounds such as (1-Z) PbTiO ₃ —Z (La ₂ O ₃ ) and (Pb _x
Ba _(1-x) ) ZrO ₃ , Sr _x Pb _(1-x) TiO ₃ , P
_{LZT {(Pb (1-x} ) La x) (Zr y Ti z)
Examples include compounds such as _{(1-x / 4)} O ₃ }.

Examples of the powder based on barium titanate include barium titanate BaTiO ₃ , strontium titanate SrTiO ₃ and calcium zirconate CaZ.
rO ₃ , calcium titanate CaTiO _{3 and the} like can be mentioned, but a typical dielectric powder is (Ba _x Sr
_{(1-X)) (Sn} y Ti (1-y)) O 3, Ba (Ti x Sn
_(1-x) ) O ₃ , Ba _x Sr _(1-x) TiO ₃ , BaTiO
_{3 -CaZrO 3, BaTiO 3 -Bi 4} Ti 3 O 12,
Examples thereof include binary compounds and ternary compounds such as (Ba _x Ca _(1-x) ) (Zr _y TiO _(1-y) ) O ₃ .

As the insulating powder, the same insulating powder as the ceramic powder used in the ceramic green sheet of the present invention is preferably used.

As the photosensitive resin composition, known ones can be used, but particularly preferred are acrylic copolymers having a carboxyl group and an ethylenically unsaturated group in the above side chain, a photoreactive compound. And a photopolymerization initiator. When a photosensitive paste containing the photosensitive resin composition of this composition is used, L
A fine pattern of (line width) / S (width interval) = 20 μm / 20 μm can be formed.

In order to form a pattern on the ceramic green sheet using the photosensitive paste, first, the photosensitive paste is applied to the green sheet by the usual screen printing method or spin coating method and dried. next,
Ultraviolet rays are selectively irradiated and exposed using a photomask having a circuit pattern, and the photosensitive paste is photocured.
Then, the unexposed portion is removed with a developing solution to obtain a fine pattern as the mask passes. The steps of exposure and development are performed in the same manner as in the case of the green sheet described above.

When a conductor is embedded in the via hole of the green sheet, an uncured sheet is used as the green sheet in which the via hole is formed by a cemented carbide drill, but the embedding method is as described above.

Thus, a predetermined conductor, resistor, dielectric or insulator pattern is printed on the surface of the sheet. Also, a guide hole is drilled in the same manner as forming a via hole. Next, the required number of sheets are stacked using the guide holes, and at a temperature of 90 to 130 ° C., 50 to 200 kg / cm ²
The sheets are bonded together under pressure to produce a sheet made of a multilayer substrate.

Next, the above-mentioned sheet is fired in a firing furnace to prepare a ceramic multilayer substrate having conductors and patterns of conductors and the like formed in via holes. The firing atmosphere and temperature differ depending on the type of ceramic substrate and conductor. In the case of a low-temperature firing multilayer substrate made of ceramics or glass / ceramics, the insulating layer is fired at a temperature of 850 to 1000 ° C. for several hours. Alumina, aluminum nitride, and mullite substrates are fired at a temperature of about 1600 ° C. for several hours. Conductors such as Cu, W, Mo and W-Mo are fired in a reducing atmosphere containing neutral or hydrogen such as nitrogen. Acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in the side chain contained in the green sheet during firing, a photoreactive polymerizable compound, an organic dye, a stabilizer, the oxidation of organic substances such as plasticizers or solvents, Any atmosphere may be used as long as it allows evaporation. As such, the conductor is C
u, W, Mo, and W-Mo contain oxygen in an amount of 3 to 100 ppm, and the rest can be fired in an atmosphere controlled by a neutral gas such as nitrogen or argon or steam. The baking temperature is 30 as the temperature for completely oxidizing and evaporating the organic binder.
After holding at 0 to 600 ° C for 5 minutes to several hours, 800 to 16
After holding at a temperature of 00 ° C. for several hours, a ceramic multilayer substrate is manufactured.

The amount of carbon remaining in the multilayer substrate after firing was 2
It is preferably 50 ppm or less. A large amount of carbon remaining causes problems such as a decrease in porosity of the multilayer substrate, a decrease in strength, an increase in dielectric constant, an increase in dielectric loss, an increase in leak current or a decrease in insulation resistance. The residual carbon amount is 1
It is at most 00 ppm, more preferably at most 50 ppm.

[0091]

EXAMPLES The present invention will be specifically described below with reference to examples. In the following description, all concentrations are expressed in wt% unless otherwise specified.

Examples 1-10 A. Ceramics component 99.5% pure alumina powder; average particle size 1.7μ
m, a spherical powder having a specific surface area of 1.1 m ² / g. Cordierite powder; spherical powder having an average particle diameter of 2.4 μm and a specific surface area of 5.0 m ² / g. Glass-ceramic powder; alumina (inorganic filler) powder 50%, glass powder 50%, (glass composition:
SiO ₂ ; 60, CaO; 20, Al ₂ O ₃ ; 20, M
_{gO; 5, B 2 O 3} ; a 3; 5, TiO _2. The glass powder was finely powdered in advance with an attritor, and a spherical powder having an average particle diameter of the powder of 2.2 μm and a specific surface area of 1.5 m ² / g was used. ) B. UV absorber Organic dye; Azo dye; Sudan IV Chemical formula; C ₂₄ H ₂₀ N ₄ O, molecular weight; 380.45 Organic dye; Azo dye; Oil yellow OB (Oil Ye
llow OB) _{formula; CH 3 C 4 H 4 N} : NC 10 H 4 NH 2, molecular weight; 261.33 C. Polymer binder 40% methacrylic acid (MAA), 30% methyl methacrylate (MMA) and 30% styrene (S
Polymer in which 0.4 equivalent (corresponding to 40%) of glycidyl methacrylate (GMA) is added to the carboxyl group (MAA) of the copolymer of t). The acid value of the polymer was 95.

D. Photoreactive compound (monomer) trimethylol / propane / triacrylate E.I. Solvent Mixed solvent of isopropyl alcohol (IPA), butyl alcohol (BA) and methyl ethyl ketone (MEK) (16: 2: 82) F.I. The photopolymerization initiator α-aminoacetophenone was added in an amount of 20% based on the total amount of the polymer and the monomer.

G. The sensitizer 2,4-diethylthioxanthone was added in an amount of 20% based on the total amount of the polymer and the monomer.

H. The plasticizer dibutyl phthalate (DBP) was added at 30% based on the sum of polymer and monomer.

I. Dispersant Cation or "Floren" (G-700, maleic acid partial ester type) is added to the ceramic powder at 1.5.
% Added.

<Production of Green Sheet> A. Preparation of organic vehicle Mix solvent and polymer binder and stir 1
All polymer binders were homogeneously dissolved by heating to 20 ° C. Then, the solution was cooled to room temperature, and a photopolymerization initiator was added and dissolved. Then, this solution was filtered using a 400-mesh filter to prepare an organic vehicle.

B. Preparation of powder with added light absorber Predetermined amount of organic dye (0.5 to ceramic powder)
%), Weighed and added a cation dispersant to the solution dissolved in isopropyl alcohol (IPA), and stirred homogeneously with a homogenizer. Next, a predetermined amount of ceramic powder is added to this solution, and while being uniformly dispersed and mixed, it is dried at a temperature of 150 to 200 ° C. using a rotary evaporator,
The IPA was evaporated. Thus, a powder in which the surface of the ceramic was uniformly coated with the film of the organic dye (so-called capsule treatment) was produced. The absorbance of the powder is shown in Table 1 and Table 2.

C. Slurry preparation The slurry is prepared by adding the photoreactive compound, light absorbent added powder (ceramic powder encapsulated with organic dye), fluorene dispersant, sensitizer, plasticizer and solvent to the above organic vehicle in a predetermined composition. Thus, the mixture was wet mixed with an attritor for 24 hours to prepare. Further, the mixture was defoamed with a vacuum stirrer for 24 hours to prepare a slurry. The viscosity of the prepared slurry is measured by a Brookfield viscometer (model;
RVDV-II +) measured at 50 rpm and 200
It was 0 cps.

The slurry compositions are shown in Tables 1 and 2.

D. Preparation of Green Sheet Molding was carried out by a doctor blade method at a molding speed of 20 cm / min with a gap of 0.7 mm between the polyester carrier film and the blade in a room shielded from ultraviolet rays. The thickness of the obtained green sheet is 145 to 155 μ.
It was m.

E. Exposure and development After cutting the green sheet produced above into a 130 mm square, it was heated at a temperature of 90 ° C. for 40 minutes to evaporate the solvent.
Next, a chromium mask having a diameter of 60 μm and having 3000 via holes was used, and ultraviolet exposure was performed from the upper surface using an ultrahigh pressure mercury lamp at an exposure dose of 250 mJ / cm ² . Next, it was immersed in a 0.5% by weight aqueous solution of monoethanolamine maintained at 25 ° C. for development, and then the photo-cured via holes were washed with water using a spray.

F. Conductor embedding in via hole Next, tungsten (when ceramic powder is used), silver-palladium alloy (when ceramic powder is used) or copper (when ceramic powder is used) is screen-printed in the via hole of the green sheet.
Of the thick film paste was embedded to form a conductor for interlayer connection of wiring.

G. Formation of Conductor Pattern A conductor pattern for signals was formed on the green sheet in which the conductor was embedded in the via hole in the above-mentioned E by using a photosensitive conductive paste. The production of the photosensitive conductive paste and the pattern formation by this paste were performed by the following method. The pattern formation for the power supply layer was performed by a screen printing method using commercially available non-photosensitive silver, copper and tungsten pastes. Photosensitive tungsten paste is used for the green sheet made of alumina powder among the above ceramic powder.
A photosensitive silver paste was used for the cordierite green sheet and a photosensitive copper paste was used for the glass-ceramic green sheet.

1. Preparation of Photosensitive Conductive Paste 1-1 Conductive powder Silver-palladium alloy powder (palladium 5%); A spherical powder having an average particle diameter of 1.5 μm and a specific surface area of 0.15 m ² / g was used.

Copper powder; polyhedral average particle size 3.0
A powder having a μm and a specific surface area of 0.32 m ² / g was used.

Tungsten powder: A powder having a polyhedral shape and an average particle diameter of 2.0 μm and a specific surface area of 0.2 m ² / g was used.

89% of each of the above conductive powders was added as a paste composition.

1-2 Polymer Binder 40% methacrylic acid (MAA), 30% methyl methacrylate (MMA) and 30% styrene (S).
Polymer in which 0.4 equivalent (corresponding to 40%) of glycidyl methacrylate (GMA) is added to the carboxyl group (MAA) of the copolymer of t). The acid value of the polymer was 100. 6% of polymer was added.

1-3 Monomer 4% of trimethylol propane triacrylate was added.

1-5 Glass Frit Calcium oxide (5.0), zinc oxide (28.1), boron oxide (25.0), silicon dioxide (22.8), sodium oxide (8.8), zirconium oxide (4.5)
And 1% of a glass frit having a composition containing alumina and (5.8).

1-4 Solvent γ-Butyrolactone 1-5 2% of photopolymerization initiator α-aminoacetophenone was added (20% based on the total amount of the polymer and the monomer).

1-6 0.6% of plasticizer dibutyl phthalate (DBP) was added (10% of polymer). 1-7 Sensitizer 2% of 2,4-diethylthioxanthone was added (the same ratio as the photopolymerization initiator).

1-8 Sensitization aid p-Dimethylaminobenzoic acid ethyl ester (EPA)
2% was added (the same ratio as the photopolymerization initiator).

1-9 Preparation of Organic Vehicle A solvent and a polymer binder are mixed and stirred for 8 hours.
All polymer binders were homogeneously dissolved by heating to 0 ° C. The solution was then cooled to room temperature and the initiator was added and dissolved. The solution was then filtered through a 400 mesh filter.

1-10 Preparation of Conductive Paste In the above organic vehicle, conductive powder, monomer, plasticizer,
A sensitizer, a sensitization aid, and a solvent were added so as to have a predetermined composition, and uniformly mixed and dispersed by a three-roller to prepare three kinds of pastes. The composition of the paste is shown in Table 2.

1-11 Printing The above paste was solidly printed on a green sheet using a 320-mesh polyester screen.
It was kept at 40 ° C. for 40 minutes to be dried. The thickness of the coating film after drying depends on the type of conductive powder, but is approximately 25 μm.
Met.

1-12 Exposure and Development Using a chrome mask having a fine circuit pattern of 30 to 50 μm formed on the coating film prepared above, ultraviolet exposure was performed from the upper surface at an exposure dose of 500 mJ / cm ² . Next 25 ° C
The film was immersed in a 0.5% by weight aqueous solution of monoethanolamine held in 1 to develop, and then the unexposed portion was washed with water using a spray.

H. Laminated 5 green sheets on which silver-palladium alloy and tungsten conductor and power circuit are formed are stacked by using guide holes and thermocompression bonded at 120 ° C. under a pressure of 150 kg / cm ² to form a multilayer ceramic green sheet consisting of 5 layers. Was produced.

I. Sintering For the obtained five-layer laminate, in the case of a silver conductor, 500
1 hour in air at ℃, in the case of a copper conductor, at 500 ℃ held in nitrogen gas containing 10 ppm of oxygen for 24 hours and baked to evaporate the binder, monomer, plasticizer and sensitizer, It sintered and the multilayer substrate was obtained. The sintering temperature was 950 ° C. for the cordierite sheet, and 900 ° C. for the glass-ceramic sheet for 1.5 hours.

The green sheet (alumina sheet) having tungsten as a conductor was fired at 500 ° C. for 24 hours in an atmosphere of H ₂ (hydrogen) gas and N ₂ (nitrogen) gas,
After removing the binder, it was held at 1600 ° C. for 1.5 hours for sintering to obtain a multilayer ceramic substrate.

J. Measurement of Strength of Green Sheet The three types of green sheets of alumina, cordierite and glass-ceramics prepared in the above C were exposed to ultraviolet rays at an exposure dose of 500 mJ / cm ² , and the tensile strength before and after the exposure of the green sheet was measured. The results are shown in Table 1.
It was shown to.

K. Evaluation Leakage current, presence / absence of disconnection failure from the via hole portion, rate of change in via hole resistance, and load in humidity (THB) test were conducted on the fired ceramic multilayer substrate.
The THB test examines the initial insulation resistance, and
After being kept in an environment of ° C and a humidity of 85% for 1500 hours, a DC voltage of 50 V was applied between the insulating layers to measure the insulation resistance.
The results are shown in Tables 1 and 2. The specific resistance of the conductor film was measured by the 4-terminal method.

Thus, the ceramic multilayer substrate produced by forming the via holes by the photolithography method using the green sheet containing the photo-curable resin and further forming the pattern with the photosensitive conductive paste has fine via holes. Since a fine conductor pattern can be formed, it is particularly advantageous for miniaturization and high density. A screen for forming a via hole is not required, and self-alignment is performed, eliminating the conventional positional deviation. Further, a uniform via hole can be formed by photo-curing, and since the via hole is fine, there is no generation of pores in the via formation portion and no disconnection was observed. As a result, high reliability could be obtained.

Further, the signal propagation speed was significantly reduced as compared with the conventional multilayer substrate having a via hole diameter of 2 to 3 times.

Further, since the cross-sectional shape of the conductor pattern formed by the photolithography method is substantially rectangular, CAD, CA
The pattern design by M becomes possible, and the current flow between the conductor circuits becomes smooth. Particularly when used in a high frequency region of 100 MHz or more, the risk of noise generation and crosstalk is greatly reduced. A reliable ceramic multilayer substrate can be obtained.

The photo-cured green sheet was 2.7 to 10.0 in comparison with 1.4 MPa of the conventional uncured sheet.
Greatly increased to MPa. Due to the improved strength, it becomes possible to perform via hole processing even on a thin sheet and the handling becomes easy, so miniaturization of the ceramic multilayer substrate can be expected.

[0128]

[Table 1]

[Table 2] Examples 11 to 16 Photosensitive green sheets were produced under the following conditions.

A. Cordierite powder A powder having an average particle diameter of 1.5 μm and a specific surface area of 8 m ² / g was used.

B UV Absorber Organic Dye; Azo Dye; Sudan IV, Chemical Formula; C ₂₄ H ₂₀ N ₄ O, Molecular Weight: 380.45.

C. Polymer Binder Non-photosensitive acrylic copolymer (methacrylic acid ester-acrylic acid ester copolymer) and photosensitive polymer. As the photosensitive polymer binder, the polymer described in C of Example 1 above was used.

D. Photoreactive compound (monomer) trimethylol / propane / triacrylate E.I. Solvent Mixed solvent of methyl ethyl ketone (MEK), isopropyl alcohol (IPA) and butanol (64: 5:
31).

F. The photopolymerization initiator α-amino acetophenone was added at 20% of the total amount of the photosensitive polymer and the monomer.

G. The plasticizer dibutyl phthalate (DBP) was added in an amount of 30% based on the total amount of the polymer (photosensitive and non-photosensitive) and the monomer.

H. Dispersant Cation or "Floren" (G-700) was added at 1.5% to the ceramic powder.

<Production of Green Sheet> A. Preparation of Organic Vehicle The solvent and the non-photosensitive and photosensitive polymer binders were mixed and heated to 120 ° C. with stirring to uniformly dissolve all the polymer binders. Then, the solution was cooled to room temperature, and a photopolymerization initiator was added and dissolved. Then the solution is filtered using a 400 mesh filter,
An organic vehicle was made.

B. Preparation of powder with added light absorber Predetermined amount of organic dye (0.5 to ceramic powder)
%), Weighed and added a cation dispersant to the solution dissolved in isopropyl alcohol (IPA), and stirred homogeneously with a homogenizer. Next, a predetermined amount of ceramic powder is added to this solution, and while being uniformly dispersed and mixed, it is dried at a temperature of 150 to 200 ° C. using a rotary evaporator,
The IPA was evaporated. Thus, a powder in which the surface of the ceramic was uniformly coated with the film of the organic dye was produced.
The absorbance of the powder is shown in Table 3.

C. Preparation of Slurry A slurry was prepared by adding a photoreactive compound, a powder having a light absorbing agent, a fluorene dispersant, and a plasticizer to the above-mentioned organic vehicle so as to have a predetermined composition.
Prepared by wet mixing for an hour. With a vacuum stirrer 24
The slurry was prepared by degassing for a period of time.

The viscosity of the prepared slurry was measured with a Brookfield viscometer (model: RVDV-II +) at a rotation speed of 50 r.
It was 2000 cps as measured in pm.

The slurry composition is shown in Table 3.

D. Fabrication of green sheet For molding, use a polyester carrier film in a room that is shielded from ultraviolet rays to create a gap of 0.7 mm with the blade.
And a doctor blade method at a molding speed of 20 cm / min. The thickness of the obtained green sheet is 150μ.
It was m. Then, 2000 green holes having a diameter of 100 μm were machined in a single green sheet having a size of 130 mm square by a punching press using a mold.

E. Filling Via Holes with Conductor Holes The above via holes were filled with a copper thick film paste by a screen printing method and kept at 80 ° C. for 40 minutes to dry the solvent.

F. Exposure Next, using a chrome mask, the exposure amount from the top is 200 mJ.
The green sheet was photo-cured by exposing it to ultraviolet rays with an ultra-high pressure mercury lamp at / cm ² .

G. Conductor pattern printing The exposed sheet was solid-printed with a photosensitive copper paste in the same manner as in Example 1F, held at 80 ° C for 40 minutes, and dried. The coating thickness after drying was 25 μm.

H. Exposure and Development Using a chrome mask in which a fine pattern with a 20 μm interval was formed in the range of 20 to 40 μm, the coating film prepared on the above sheet was exposed to ultraviolet rays at 800 mJ / cm ² from the upper surface. Next, it was immersed in a 0.5 wt% aqueous solution of monoethanolamine maintained at 25 ° C. for development, and the unexposed portion was washed with water using a spray.

I. The coating film with a fine pattern formed on the fired green sheet is kept at 500 ° C. for 30 minutes in nitrogen gas containing 10 ppm of oxygen to evaporate the polymer binder, the monomer, the sensitizer and the plasticizer, and then 900 ° C. Was sintered for 1 hour to prepare a copper conductor film. The sheet was baked by applying alumina spread powder to a high-purity alumina substrate whose surface was polished, and then lightly weighting the sheet.

J. Evaluation The film thickness, resolution, and specific resistance of the copper conductor film after firing were measured and evaluated. The film thickness was measured with a micrometer. The resolution was determined by observing the conductor film with a microscope and determining the line spacing at which lines of 20 to 40 μm do not overlap with each other in a straight line and reproducibility is obtained as the finest line spacing. The specific resistance was determined by measuring the electromotive force under a current of 30 mA by the 4-terminal method.
The results are shown in Table 3.

As described above, the line width / line width was determined by the photolithography method using the conductive paste containing the photocurable resin.
Since a fine pattern having a line spacing of 30 μm / 30 μm or less and a low resistance can be obtained, it can be particularly used as a conductor paste for an inner layer of a ceramic multilayer substrate. As a result, it is possible to further reduce the size and increase the density of the ceramic multilayer substrate.

[0149]

[Table 3] Comparative Example 1 A non-photosensitive green sheet was prepared under the following conditions. The slurry composition used is as follows.

A. Ceramic powder Cordierite powder; spherical powder having an average particle size of 2.4 μm and a specific surface area of 5.0 m ² / g.

B. Polymer binder Acrylate resin C.I. Plasticizer dibutyl phthalate D. Solvent Mixed solvent of methyl ethyl ketone, isopropyl alcohol and butanol (64: 5: 31) E. Dispersant Floren <Preparation of Green Sheet> A. Preparation of Slurry Using an organic vehicle in which a polymer binder was dissolved in a solvent, 62, 15, 1, 3 and 19% of cordierite powder, binder, dispersant and plasticizer and a solvent were respectively added as a final slurry composition, It was adjusted by wet mixing for 24 hours with an attritor. Further, defoaming was performed with a vacuum stirrer to prepare a sheet forming slurry.

B. Production of Green Sheet Using the above slurry, the gap between the polyester carrier film and the blade was 0.8 mm, and the molding speed was 20.
Molded by the doctor blade method under the condition of cm / min.
The thickness of the obtained green sheet was 150 μm.

Next, an attempt was made to form a conductor pattern by using the photosensitive copper paste of Example 1 on the green sheet. However, various post-exposure development conditions were examined, but the unexposed portion could not be removed, and pattern formation could not be performed.

Comparative Example 2 The following photosensitive green sheet was prepared. That is,
An alumina green sheet having a thickness of 160 μm was produced under the same conditions as in Example 2 except that no ultraviolet absorber was added. An exposure amount of 500 mJ / cm ² was applied to this green sheet.
It was exposed to ultraviolet light under the above conditions. Next, as in Comparative Example 1, an attempt was made to form a conductor pattern using a photosensitive copper paste, but the unexposed portion could not be developed and the pattern could not be formed. In addition, the exposed sheet is warped and warped,
Tensile strength was measured, but it was 0.8 MPa, which was low compared with the sheet to which the ultraviolet absorber was added.

[0155]

EFFECTS OF THE INVENTION Even if a pattern is formed on a conventional non-photosensitive ceramic green sheet by using a photosensitive paste, addition of an organic polymer, a plasticizer, a solvent or various kinds contained in a raw sheet before firing is added. The agent was reacted with the organic solvent contained in the photosensitive paste, and the unexposed portion could hardly be removed during development, so that pattern formation was difficult. In addition, even if an attempt is made to form a pattern on a conventional photosensitive ceramics green sheet by using a photosensitive paste, the UV curing of the green sheet is insufficient and the same problem as that of the non-photosensitive green sheet occurs, resulting in the pattern formation. Was difficult. In the present invention, ceramics
Since the green sheet contains an ultraviolet absorber, it is possible to form a good pattern on the sheet using the photosensitive paste. This is because the UV curing of the sheet is sufficient, resulting in improved chemical resistance and solvent resistance of the sheet,
It is based on the fact that the reaction with the organic solvent in the photosensitive paste hardly occurs and the unexposed portion is completely removed.
In addition to this, the ultraviolet curing gives an effect of improving the dimensional accuracy and mechanical strength of the sheet. In particular, the tensile strength is dramatically improved.

As described above, since a pattern can be formed on the ceramic green sheet by using the photosensitive paste, it becomes possible to form a fine conductor, resistor, dielectric or insulator pattern with L / S = 30 μm / 30 μm. Moreover, a conductor pattern having a low resistance can be obtained, and the conductor for the inner layer of the ceramic multilayer substrate can be formed. Further, the tensile strength of the sheet is greatly improved, which is effective for thinning the green sheet. As a result, it is possible to further reduce the size and increase the density of the ceramic multilayer substrate.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between measurement wavelength and absorbance.

Claims (18)

[Claims] 1. A method for forming a pattern on a ceramic green sheet, which comprises the following steps (1) to (3): (1) A step of applying a sheet slurry composition containing a ceramic powder, a photocurable resin composition, and an ultraviolet absorber on a support and drying it to produce a ceramic green sheet, (2) the ceramic green sheet UV irradiation, and the process of forming a via hole
(3) A step of forming a pattern by applying a photosensitive paste on a ceramic green sheet having a via hole, drying, selectively exposing and developing. 2. The method for forming a pattern on a ceramic green sheet according to claim 1, wherein in the step (2), the via hole is formed by selective irradiation of ultraviolet rays and development. 3. The ceramic green sheet according to claim 1, wherein in the step (2), a via hole is formed after at least the surface of the ceramic green sheet is photo-cured by irradiation with ultraviolet rays. Method to form a pattern on the. 4. The ceramic green sheet according to claim 1, wherein in the step (2), after the via hole is formed, at least the surface of the ceramic green sheet is photo-cured by irradiation with ultraviolet rays. A method of forming a pattern. 5. The ceramic according to claim 1, wherein the photosensitive paste is at least one selected from the group of photosensitive conductive paste, photosensitive resistor paste, photosensitive dielectric paste and photosensitive insulating paste. -A method of forming a pattern on a green sheet. 6. The method for forming a pattern on a ceramic green sheet according to claim 5, wherein the photosensitive conductive paste contains a conductor powder and a photosensitive resin composition. 7. The method for forming a pattern on a ceramic green sheet according to claim 5, wherein the photosensitive resistor paste contains a resistor powder and a photosensitive resin composition. 8. The method for forming a pattern on a ceramic green sheet according to claim 5, wherein the photosensitive dielectric paste contains a dielectric powder and a photosensitive resin composition. 9. The method for forming a pattern on a ceramic green sheet according to claim 5, wherein the photosensitive insulating paste contains an insulating powder and a photosensitive resin composition. 10. The method for forming a pattern on a ceramic green sheet according to claim 1, wherein the ultraviolet light absorber is an organic dye. 11. The method for forming a pattern on a ceramic green sheet according to claim 10, wherein the organic dye is an azo dye. 12. The method for forming a pattern on a ceramic green sheet according to claim 10, wherein the ceramic powder is coated with an ultraviolet absorber. 13. The method for forming a pattern on a ceramic green sheet according to claim 1, wherein the integrated value of the absorbance of the ultraviolet absorber at 350 to 450 nm is 10 to 150. 14. The method for forming a pattern on a ceramic green sheet according to claim 1, wherein the integrated value of the absorbance of the ultraviolet light absorber at 350 to 450 nm is 20 to 100. 15. A sheet slurry composition comprising ceramic powder, an acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in a side chain, a photoreactive compound, and a photopolymerization initiator. A method for forming a pattern on the ceramic green sheet according to claim 1. 16. The ceramic powder is at least one selected from the group consisting of alumina, zirconia, magnesia, beryllia, mullite, cordierite, spinel, forsterite, anorthite, cergian, silica and aluminum nitride. The method for forming a pattern on the ceramic green sheet according to claim 1. 17. The ceramic powder is, in oxide notation, SiO ₂ 30 to 70% by weight Al ₂ O ₃ 5 to 25% by weight CaO 5 to 25% by weight MgO 0 to 10% by weight B ₂ O _{3 3 to} 50% by weight. % TiO _{2 0 to} 15% by weight, 40 to 60% by weight of glass composition powder with a total amount of 95% by weight or more, and alumina, zirconia, magnesia, beryllia, mullite, cordierite, spinel, forsterite, and anod. A pattern is formed on the ceramic green sheet according to claim 1, which is a raw material mixture with 60 to 40% by weight of at least one kind of inorganic filler powder selected from the group consisting of site, Celsian, silica and aluminum nitride. how to. 18. The method for forming a pattern on a ceramic green sheet according to claim 1, wherein the sheet slurry composition contains a stabilizer.