JP3324259B2 - Ceramics green sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic grease sheet suitably used for forming a fired ceramic substrate and the like, and more particularly, to a high-density mounting in which semiconductor elements are mounted and they are interconnected. The present invention relates to a fired ceramic substrate suitably used for a ceramic substrate, and more particularly to a green sheet made of ceramic preferably used for a multilayer ceramic substrate.

[0002]

2. Description of the Related Art Multilayer ceramic substrates can be roughly classified into:
There are a thick film printing lamination method and a green sheet method.

The thick film printing and laminating method is a method of alternately printing and laminating a conductive paste and an insulating paste on a baked substrate to form a multilayer structure. After repeating printing and drying, the calcination is completed once. However, firing may be performed once each time the insulating paste is applied.

The green sheet method includes a printing method and a laminating method.

In the green sheet printing method, conductive paste and insulating paste are alternately printed and laminated on a green sheet to form a multilayer, and firing and printing are completed once after repeating printing and drying.

[0006] The green sheet laminating method is almost the same as the green sheet printing method.
This is a method of printing a conductor, laminating a large number of green sheets having been processed with via holes and through holes (hereinafter collectively referred to as via holes), thermocompression bonding, and simultaneously firing to form a multilayer substrate. This method will be described in detail later,
There are drawbacks such as that the hole diameter of the green sheet after forming the via hole cannot be reduced, and that many dies and jigs are required for processing the via hole.

[0007] Conventional ceramic green sheets are:
As described in JP-A-1-232797 and JP-A-2-141458, usually, a ceramic powder, an organic binder, a plasticizer, a solvent, a dispersant and the like are appropriately blended, and then mixed to form a slurry. Thereafter, a green sheet is formed from the obtained slurry by a known method such as a doctor blade method.

After processing these green sheets into a desired shape using a cutter or a punching die, the green sheets are punched with a die or a laser using a punch and a die to provide a via hole.

For example, in the production of a multilayer substrate by a green sheet multilayer laminating method, a slurry as a green sheet raw material is continuously thinly spread on a carrier film to form a green sheet, and then the carrier film is peeled from the back surface of the green sheet. Then, the green sheet is punched out to a required work size, and the green sheet is punched to form a via hole. The green sheet is filled with a conductive paste by a normal screen printing method. When the thickness of the green sheet is 50 μm or less, a hole is formed together with the carrier film to form a via hole.

[0010]

However, when a via hole is formed in a green sheet using a conventional punching die (punch) made of carbide, the strength of the carbide is low, so that the green sheet has a small diameter. The production of the punch is difficult, and the yield after processing with a small diameter punch is extremely low, so that a hole having a diameter of 0.2 mm or less can hardly be formed, and the practical value is extremely poor. Since the area occupied by the via hole on the substrate increases in proportion to the square of the via hole diameter, many advantages such as miniaturization of the wiring board can be expected if a fine via hole can be formed. It was impossible to expect such an advantage as far as the conventional technology was concerned.

[0011] If a superhard material is used, chips are mixed into the green sheet, which may cause insulation failure. When drilling with a carbide punch, the counterpart material is harder than the carbide, and the punch wears out, requiring frequent replacement, increasing the cost of drilling and occupying more than 50% of the substrate. is there.

[0012] Laser drilling is also used to make holes in green sheets and sintered ceramic substrates. However, it takes a lot of time to make many holes at once, and mass production is required. Not suitable. When a hole is formed by laser processing, a so-called "burr"
Therefore, there are disadvantages such as that a high-precision one cannot be obtained due to the occurrence of the problem and that it is necessary to polish the substrate after firing.

Conventionally, when a via hole is formed in a green sheet, when the thickness of the green sheet is 50 μm or less, particularly 20 μm or less, the strength of the green sheet is low. However, there have been problems such as processing debris adhering to the back side of the green sheet after the perforation, and deformation of the green sheet when the protective film is peeled off. Further, since the protective film is disposable, there is a problem that the cost for the green sheet is increased.

[0014] Advances in information processing technology have been remarkable due to the need to process a large amount of information promptly, and a semiconductor chip constituting a main part of an information processing apparatus is densely mounted on a ceramic circuit board for use. Since the number of terminals of a semiconductor chip is large, the number of wiring lengths for forming a pattern on a circuit board is enormous, and a multilayer wiring structure is inevitably required.
In this case, it is necessary to easily and quickly form a via hole for forming the via and to reduce the hole diameter.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and aims at solving the drawbacks of the conventional ceramic green sheet, making it extremely easy to form via holes and through holes. It is an object of the present invention to provide a ceramic green sheet which can be formed accurately and precisely and can form fine holes reliably.

[0016]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
A ceramic green sheet characterized by containing a ceramic powder, an ultraviolet light absorber and a photosensitive resin composition, preferably a ceramic powder, an ultraviolet light absorber, an acrylic resin having a carboxyl group and an ethylenically unsaturated group in a side chain. This is achieved by a ceramic green sheet characterized by containing a copolymer, a photoreactive compound and a photopolymerization initiator.

That is, the present invention provides a green sheet itself made of ceramics with photosensitivity,
When this is used, via holes can be formed easily and accurately using photolithography technology, and fine holes can be formed efficiently at low cost.

In the present invention, the ceramic green sheet is, in principle, a single layer sheet obtained by applying a slurry and removing a solvent in a production method described later, and is a sheet before exposure.

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

The ceramic powder used in the present invention includes ceramic powder alone, a glass-ceramic composite system, crystallized glass and the like.

Examples of using ceramic powder alone include alumina (Al ₂ O ₃ ) and zirconia (ZrO
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 ), Celsian (BaO.Al ₂ O ₃ .2Si)
Powders such as O ₂ ), silica (SiO ₂ ), clinoenstatite (MgO.SiO ₂ ), aluminum nitride (AlN), and low-temperature fired ceramic powders. The purity of these ceramic powders is preferably 90% by weight or more.

When aluminum nitride powder is used alone, a calcium-based compound (for example, CaC ₂ , CaVO ₃ ,
A powder to which 0.5 to 20% by weight of CaCN ₂ , CAF ₂ , CaO) or an yttrium compound (for example, Y ₂ O ₃ ) is added can be used. Additives such as Y, rare earth elements, alkaline earth elements, and carbon are added in amounts of 0.0
1-15% by weight of mixed powder, MgC ₂ , ZrC, V
Powder containing 1 to 5% by weight of a carbide such as C, NbC,
A mixed powder to which an oxide such as BeO is added can also be used. More preferred amount is, if the Y ₂ O ₃ and BeO, 1 to 10 wt%, in the case of calcium oxide, 1-5 wt%, in the case of carbon is less than 1 wt%. These additives can be used alone or in combination of two or more. By adding these additives, the sinterability of aluminum nitride is improved, and a dense sintered body having high thermal conductivity can be obtained.

Examples of the glass-ceramic composite system include a glass composition powder containing, for example, SiO ₂ , Al ₂ O ₃ , CaO, B ₂ O ₃ and, if necessary, MgO and TiO ₂ , alumina, zirconia, and magnesia. , Beryllia, mullite, cordierite, spinel, forsterite, anorthite, Celsian, silica, and at least one inorganic filler powder selected from the group consisting of aluminum nitride. More preferably, the ceramic powder is expressed in terms of oxide as 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 40 to 60% by weight of a glass composition powder having a total amount of 95% by weight or more in a composition range of 0 to 15% by weight, and alumina, zirconia, magnesia, beryllia, mullite, cordierite, spinel, forsterite, anorthite, and Celsian , 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 a ratio in the glass composition powder, and it is preferable that these components have a total amount of 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 ,
Mn oxide, Cr oxide, NiO, Co oxide and the like can be contained.

Specific examples of the glass-ceramic composite system include SiO ₂ —B ₂ O ₃ glass, PbO—SiO ₂
-Al ₂ O ₃ -B ₂ O ₃ based glass, CaO-SiO ₂ -
Examples thereof include those obtained by adding ceramic components such as Al ₂ O ₃ , quartz (SiO ₂ ), ZrO ₂ , and cordierite to Al ₂ O ₃ —B ₂ O ₃ -based glass and the like.

The SiO ₂ in the glass composition powder is 30 to 70
It is preferably in the range of 30% by weight. If the amount is less than 30% by weight, the strength and stability of the glass layer are reduced, and the dielectric constant and the coefficient of thermal expansion are increased, so that the glass layer tends to deviate from desired values. 7
If the content is more than 0% by weight, the thermal expansion coefficient of the fired substrate becomes high, and it becomes difficult to fire at 1000 ° C. or less.

It is preferable that Al ₂ O ₃ is blended in a range of 5 to 25% by weight. If it is less than 5% by weight, the strength in the glass phase is reduced, and baking at 1000 ° C. or lower becomes difficult. If it exceeds 25% by weight, the temperature at which the glass composition is fritted becomes too high.

It is preferable that CaO is blended in the range of 5 to 25% by weight. If the amount is less than 5% by weight, a desired coefficient of thermal expansion cannot be obtained, and baking at 1000 ° C. or lower becomes difficult. If it exceeds 25% by weight, the dielectric constant and the coefficient of thermal expansion increase, which is not preferable.

It is preferable that MgO is blended in the range of 0 to 10% by weight, thereby facilitating control of the melting temperature of the glass. If it exceeds 10% by weight, the obtained substrate has a high coefficient of thermal expansion.

B ₂ O ₃ has a glass frit of 1300-1.
For melting at a temperature around 450 ° C., and for Al ₂ O ₃
In order to control the ceramic firing temperature in the range of 800 to 1000 ° C so that the electrical, mechanical and thermal properties such as dielectric constant, strength, coefficient of thermal expansion, sintering density, etc. are not impaired even when the amount is large. Is preferable, and the amount is preferably in the range of 3 to 50% by weight. If the content is less than 3% by weight, the strength of the ceramic tends to decrease if the content of B ₂ O ₃ is too large, and if the content exceeds 50% by weight, the stability of the glass decreases, and the glass is regenerated by the reaction between the inorganic filler (crystal) and the glass. Crystallization is accelerated, and when a multi-layer substrate is formed, a phenomenon in which a glass phase oozes out is not preferable.

It is preferable that TiO ₂ is blended in the range of 0 to 15% by weight. The low-temperature fired ceramic substrate of the present invention is a mixture of amorphous glass and an inorganic filler before firing, but depending on the type of filler, is a partially crystallized ceramic of amorphous glass, ceramic, and crystallized glass. It is estimated to be. TiO ₂ acts as an effective nucleating substance in the production 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 coefficient of thermal expansion. In particular, alumina, zirconia, mullite, cordierite, and anorthite have excellent effects. If the proportion of the inorganic filler exceeds 60% by weight, sintering becomes difficult, and
It becomes difficult to sinter below. 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 ceramic is set to 800 to 100.
At 0 ° C., desired properties such as strength, dielectric constant, coefficient of thermal expansion, sintered density, volume resistivity, and shrinkage can be obtained.

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

As a method of producing the glass composition powder, for example, the raw materials SiO ₂ , Al ₂ O ₃ , CaO, Mg
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., quenched,
There is a method of forming a glass frit and then pulverizing it into a fine powder of 0.5 to 3 μm. As a raw material, a high-purity carbonate, oxide, hydroxide or the like can be used. In addition, depending on the type and composition of the glass powder, an ultra-high purity alkoxide or organometallic raw material of 99.99% or more is used. This is preferable because a high-strength ceramic substrate can be obtained.

As a specific example of the crystallized glass, MgO—
Al ₂ O ₃ —SiO ₂ or Li ₂ O—Al ₂ O ₃ —Si
O ₂ -based 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 to increase the strength,
B ₂ O ₃ and a nucleating substance are added to Li ₂ O—Al ₂ O ₃ —SiO ₂ to precipitate spodumene, which is also used to increase strength.

The particle diameter 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, but in the case of powder, the particle diameter is 0.8 to 6 μm. Specific surface area 0.4-14
It is preferable to satisfy m ² / g simultaneously. More preferred ranges are a particle diameter of 1.0 to 4.0 μm and a specific surface area of 0.5 to 1.
0 m ² / g. Within this range, light is sufficiently transmitted during exposure to ultraviolet light, and a uniform via hole without a difference in upper and lower hole diameters can be obtained. If the powder particle size is less than 0.8 μm, or if the specific surface area exceeds 14 m ² / g, the powder becomes too fine and light is scattered at the time of exposure to cure the unexposed portion. For this reason, via holes with roundness cannot be obtained during development, or light is absorbed during the exposure before the ultraviolet light reaches the bottom of the sheet sufficiently, and photocuring occurs evenly inside the holes. Because there is no via hole, a via hole (a beer barrel shape) or an overhang (a tapered shape of the hole) is generated on the inner surface of the via hole, so that a linear via hole cannot be obtained. Further, the shrinkage ratio after firing becomes large, and a high-precision green sheet cannot be obtained. On the other hand, when the particle diameter is 6 μm or when the specific surface area is less than 0.5 m ² / g, a dense sintered body cannot be obtained after firing. The shape of the powder is preferably spherical, and a sharp particle size distribution is preferable because the influence of scattering at the time of exposure to ultraviolet light can be suppressed low.

As the photosensitive resin used for forming the ceramic green sheet of the present invention, a conventionally known photosensitive resin can be used. The photosensitive layer made of such a photosensitive resin is a layer that is insolubilized or solubilized by irradiating an active light beam.

Examples of the photo-insolubilized photosensitive substance include:
(1) A mixture of a functional monomer or oligomer having one or more unsaturated groups or the like in one molecule with an appropriate polymer binder; (2) Photosensitivity of aromatic diazo compound, aromatic azide compound, organic halogen compound, etc. (3) a photosensitive polymer obtained by pending a photosensitive group to an existing polymer or a modified polymer thereof; (4) a diazo-based amine So-called diazo resins, such as condensates with formaldehyde, may be mentioned.

Examples of the photo-soluble photosensitive material include:
(1) a complex of an inorganic salt or an organic acid of a diazo compound, a quinonediazo compound mixed with an appropriate polymer binder, and (2) a quinonediazo compound combined with an appropriate polymer binder, for example, naphthoquinone of phenol or novolak resin 1,2-diazide-5-sulfonic acid ester, and the like.

A particularly preferred photosensitive resin is an acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in the side chain, and an acrylic copolymer formed by copolymerizing an unsaturated carboxylic acid and an ethylenically unsaturated compound. The copolymer can be produced by adding an ethylenically unsaturated group to a side chain.

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. By including at least methyl methacrylate among the above ethylenically unsaturated compounds as the main polymerization component of these acrylic main chain polymers, a copolymer having good thermal decomposability can be obtained.

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

Examples of the ethylenically unsaturated compound having a glycidyl group include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, glycidyl ethyl acrylate, crotonyl glycidyl ether, glycidyl ether crotonic acid and glycidyl ether isocrotonic acid. . In addition, examples of the acrylic chloride compound include acrylic chloride, methacrylic chloride, and allyl chloride. The addition amount of these ethylenically unsaturated compounds or acrylic acid chloride is preferably 0.05 to 1 molar equivalent based on the carboxyl group in the acrylic copolymer,
More preferably, it is 0.1 to 0.8 molar equivalent. If the added amount is less than 0.05 molar equivalent, the photosensitive characteristics become poor, and it becomes difficult to form a pattern. On the other hand, when the added amount is larger than 1 molar equivalent, the solubility of the developer in the unexposed portion is reduced, and the hardness of the coating film is undesirably reduced.

The acrylic polymer having a carboxyl group and an ethylenically unsaturated group in the side chain has an acid value (AV) of 50-18.
0, more preferably 70 to 160
It is. More preferably, it is 80 to 120. If the acid value is less than 50, the amount of ethylenically unsaturated groups increases, and the proportion of carboxyl groups having photosensitivity decreases, so that the allowable width for development is narrow and the cutting of via-hole edges is poor. Further, when the acid value exceeds 180, the solubility of the unexposed portion in the developing solution is reduced, so that when the developing solution concentration is increased, peeling occurs to the exposed portion, and it becomes difficult to obtain a via hole having high precision. . Also, the hardness of the green sheet decreases.

The molecular weight of the polymer includes a number average molecular weight (Mn), a weight average molecular weight (Mw), and a Z average molecular weight (M
z), but the preferred ranges are 10,000 to 20,000, respectively.
10,000 to 60,000 and 5000 to 200,000. Within this range, the developability is improved and fine via holes are easily obtained. Further, the ratio (Mw / Mn) representing the degree of dispersion is in the range of 2 to 4, and the sharper the molecular weight distribution is, the better the developing characteristics are, and the fine via holes are preferably obtained.

These photosensitive resins function as a polymer binder, and preferably contain a non-photosensitive polymer as a polymer binder component.
When a green sheet containing no non-photosensitive polymer is cured by irradiating it with ultraviolet rays, the tensile strength is improved twice or more, but the elongation is reduced. Here, the elongation is improved by containing the non-photosensitive polymer. The content of the non-photosensitive polymer is preferably 5 to 50% by weight of the photosensitive polymer. If the amount is less than 5% by weight, the effect of improving elongation is low. If the amount exceeds 50% by weight, the green sheet is not sufficiently cured even when irradiated with ultraviolet rays, so that the green sheet has poor chemical resistance, dissolution resistance and mechanical strength. Does not improve.
Specific examples include polyvinyl alcohol, polyvinyl butyral, methacrylate polymer, acrylate polymer, acrylate-methacrylate copolymer, α-methylstyrene polymer, and butyl methacrylate resin.

The photoreactive compound used in the present invention may be a photoreactive compound containing a carbon-carbon unsaturated bond, and specific examples thereof include allyl acrylate, benzyl acrylate and butoxy. Ethyl 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, allylcyclohexyl diacrylate,
Bisphenol A diacrylate, 1,4-butanediol-diacrylate, 1,3-butylene glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, Dipentaerythritol hexaacrylate,
Dipentaerythritol monohydroxypentaacrylate, ditrimethylolpropanetetraacrylate,
Glycerol diacrylate, methoxycyclohexyl diacrylate, neopentyl glycol diacrylate, propylene glycol diacrylate, polypropylene glycol diacrylate, triglycerol diacrylate, trimethylolpropane triacrylate and the above acrylates as methacrylates Changed, γ-methacryloxypropyltrimethoxysilane,
1-vinyl-2-pyrrolidone and the like. In the present invention, one or more of these photoreactive compounds can be used.

The acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in the side chain is usually used in an amount of 0.5 to 5 times the weight of the photoreactive compound. 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 reduced. On the other hand, if the amount of the acrylic copolymer is too large, the solubility of the unexposed portion 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
-Methyldiphenyl ketone, dibenzyl ketone, fluorenone, 2,2-diethoxyacetophenone, 2,2-
Dimethoxy-2-phenyl-2-phenylacetophenone, 2,4-diethylthioxanthone, 2-hydroxy-2-methylpropiophenone, pt-butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, -Isopropylthioxanthone, diethylthioxanthone, benzyl, benzyldimethylketanol, benzyl-methoxyethylacetal, benzoin, benzoinmethylether, benzoinbutylether, anthraquinone,
-T-butylanthraquinone, 2-amylanthraquinone, β-chloranthraquinone, anthrone, benzanthrone, dibenzosuberone, methyleneanthrone, 4
-Azidobenzalacetophenone, 2,6-bis (p-
(Azidobenzylidene) cyclohexanone, 2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2-phenyl-1,2-butadione-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's ketone, 2-methyl- [4- (Methylthio) phenyl] -2-morpholino-1-propanone,
Naphthalenesulfonyl chloride, quinoline sulfonyl chloride, N-phenylthioacridone, 4,4-azobisisobutyronitrile, diphenyl disulfide,
Combination of photoreducing dyes such as benzthiazol disulfide, triphenylphorphine, camphorquinone, carbon tetrabromide, tribromophenylsulfone, benzoin peroxide, eosin and methylene blue with reducing agents such as ascorbic acid and triethanolamine And so on. In the present invention, one or more of these can be used.

The photopolymerization initiator is added in an amount 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 photopolymerization initiator is too small, the photosensitivity becomes poor, and if the amount of the photopolymerization initiator is too large, the residual ratio of the exposed portion may be too small.

In the present invention, it is essential to add an ultraviolet (UV) light absorber to the photosensitive resin and the ceramic powder in order to form a via hole in the green sheet. High resolution can be obtained by adding a light absorbing agent having a high ultraviolet absorbing effect. That is, usually, the ceramic powder alone hardens to an unnecessary portion by photocuring and cannot form a via hole even if developed, or the roundness is greatly reduced. The present inventors have conducted intensive studies on this cause, and as a result, it has been found that the scattered ultraviolet light is absorbed or weakened and reaches the light-shielded portion by the exposure mask. Therefore, the addition of the ultraviolet light absorber substantially prevents the scattered light from wrapping around, and prevents the photosensitive resin in the mask portion from hardening.
A pattern corresponding to the exposure mask is formed.

In the absence of an ultraviolet absorber, even if the sheet is irradiated with ultraviolet light, the sheet is reflected by the ceramic powder,
Since only a part of the sheet surface is hardened due to scattering, little improvement in the chemical resistance and mechanical strength of the green sheet is observed, and the green sheet after UV irradiation is bent or warped, requiring high dimensional accuracy. A green sheet cannot be obtained, and the mechanical strength is low. However, when an ultraviolet absorber is added, ultraviolet rays can be effectively absorbed and reach the lower portion of the green sheet, so that the inside of the sheet is uniformly photo-cured, and the chemical resistance and dimensional accuracy of the green sheet are improved. In addition, the mechanical strength is greatly improved. In particular, the tensile strength increases 2-5 times.

350 to 450 nm as an ultraviolet absorber
Inorganic powders or organic dyes having a high UV absorption coefficient in the above wavelength range are preferably used. As the inorganic powder, cobalt oxide Co ₂ O ₃ , CoO, iron oxide Fe ₂ O
₃ , oxides such as chromium oxide Cr ₂ O ₃ , manganese oxide MnO ₂ , copper oxide Cu ₂ O, CuO, titanium oxide TiO ₂ , titanium carbide TiC, tungsten carbide WC, zirconium carbide ZrC, silicon carbide SiC, and niobium carbide NbC Such as carbide, titanium boride TiB ₂ , zirconium boride ZrB _2, etc., titanium nitride Ti
There are nitrides such as N, zircon nitride ZrN, and tantalum nitride TaN, and carbon (C). Among them, preferred are inorganic powders of carbon and carbide, which can form a sharp pattern without blurring, and can form via holes finely without a difference in upper and lower hole diameters. In particular, when carbon is fired in an oxygen-containing atmosphere, carbon is volatilized as carbon dioxide gas, so that deterioration of insulation and dielectric properties as a ceramic substrate can be minimized.

These inorganic powders can be used as two or more kinds of composite powders of oxides, nitrides and carbides, but they are selected as long as they do not deteriorate the insulation and dielectric properties of the ceramic substrate. Is preferred. The addition amount of the inorganic powder is preferably 0.1 to 5% by weight. If the amount is less than 0.1% by weight, the effect of adding the ultraviolet absorber is reduced, and if it exceeds 5% by weight, the substrate characteristics are undesirably deteriorated. More preferably, it is 0.25 to 1% by weight.

As the organic dye, various dyes having high absorbance can be used. As the organic dye, at least one selected from azo dyes, quinoline dyes, aminoketone dyes, anthraquinone dyes, benzophenone dyes, benzotriazole dyes, cyanoacrylate dyes, and xanthene dyes can be used. The organic dye is preferable because it does not remain in the fired substrate because it evaporates during firing even when added as a light absorbing agent, so that the insulation resistance does not decrease due to the light absorbing agent.

As representative azo dyes,
Sudan Blue _{(C 22 H 18 N 2 O} 2 = 342.4), Sudan _{R (C 17 H 14 N 2} O 2 = 278.31), Sudan II
(C ₁₈ H ₁₄ N ₂ O = 276.34), Sudan III (C ₂₂
H ₁₆ N ₄ O = 352.4), Sudan IV (C ₂₄ H ₂₀ N ₄₀₎
= 380.45), 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 AB, oil yellow OB (CH ₃ C ₄ H ₄ N: NC)
₁₀ H ₄ NH ₂ = 261.33), oil black 2H
B, naphthyl red, naphthylamine bordeaux, acid red 52, new coccin, azo blue, benzoperpurine 4B, chloratin fast red 5B and the like. Anthraquinone dye is Algold Red 5G
However, examples of the xanthene-based dye include acid rhodamine B.

Among these organic dyes, Sudan I, Sudan II, Sudan III, Sudan IV, Oil Orange SS, Oil Black 2HB, Acid Red 52, New Coksin, Oil Yellow AB, and Oil Yellow OB are 350 to 450 nm to ultraviolet rays. Is very high, ie, 150 or more, and is almost completely decomposed at a temperature of 600 to 800 ° C. in a neutral or reducing atmosphere, and no residue is left.

The amount of the organic dye to be added includes bending strength, insulation resistance, dielectric constant,
This is a range that does not lower the thermal expansion characteristics and the like, and is 0.1 to 2% by weight based on the ceramic powder.

It is preferable to add the organic dye by the following method. That is, a solution in which an organic dye is previously dissolved in an organic solvent or water is prepared. Next, a dispersant is added to the solution to form a uniform solution, which is then thoroughly stirred and mixed with an ultrasonic dispersion and a homogenizer, and then dried while evaporating and removing the organic solvent or water using a rotary evaporator. According to this method, it is possible to produce a so-called capsule-shaped ceramic powder in which individual surfaces of the ceramic powder are uniformly coated with a film of an organic dye. The film thickness of the organic dye when formed into a capsule is 10 to
The range of 150 nm is preferable, and more preferably, 20 to 1 nm.
00 nm. When the film thickness is less than 10 nm, the light is scattered by the powder before being sufficiently transmitted to the lower portion of the sheet during ultraviolet exposure, and the unexposed portion is cured,
A via hole with roundness cannot be obtained. If the thickness exceeds 150 nm, light is absorbed by the powder before reaching the lower part of the sheet. Since light does not penetrate to the lower sheet, light curing cannot be performed. As a result, the lower sheet comes off during development, making it difficult to form via holes. As the dispersant to be used, a cationic surfactant is preferable, and its amount is 0.1 to 3% by weight based on the ceramic powder.

In the present invention, the UV absorber 350
There is a preferred range for the integrated value of the absorbance at nm 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 ceramic powder whose surface is coated with an organic dye.

In the present invention, the absorbance is defined as follows. That is, light is applied to the measurement sample in an integrating sphere using a commercially available spectrophotometer, and the light reflected there is collected and detected. In addition, all the light except for the light detected by the integrating sphere is regarded as absorption light and can be obtained from the following equation.

[0061] The light intensity of the control light Ir (Ir before measuring the absorbance of the sample, and the BaSO ₃ of the same material as are applied to the integrating sphere inner surface material measured light intensity due to reflection is attached to the sample stage Data) Assuming that the light intensity of light incident on the sample is I and the light intensity of the absorbed light after irradiating 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 equation (1). The unit of the light intensity is W / cm ₂
Expressed by Absorbance = -log ((I-Io) / Ir) (1)

The absorbance is measured as follows. 1. The powder to which the light absorbing agent has been added is 20 mm in diameter by a press machine,
It is molded to a size of 4 mm in thickness. 2. Next, the molded body of the powder is attached to the mounting hole of the reflecting sample of the integrating sphere using a spectrophotometer, and the absorbance due to the reflected light is measured in a wavelength range of 200 to 650 nm, whereby a graph as shown in FIG. 1 is obtained. The vertical axis indicates the absorbance of equation (1), and the horizontal axis indicates the measurement wavelength. 3. Next, in FIG.
The range of nm is divided into 10 sections every 10 nm, and the area of each section is obtained. The area is determined 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, and the absorbance at 450 nm is 0.55. , 350-
If the area of the portion of 360 nm is assumed to be A and it is regarded as 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 integral value S of the area of ten sections is obtained as follows. S = A + B +... J The area S was defined as an integrated value of absorbance at 350 to 450 nm.

In the present invention, the preferable range of the integrated value of the absorbance is 30 to 150, and the more preferable range is 3 to 150.
0 to 70. If the absorbance is less than 30, the light is scattered by the powder before sufficiently transmitting to the bottom of the green sheet at the time of exposure to ultraviolet light, and the unexposed portion is hardened, so that it is not possible to form a viahole with roundness. If the absorbance exceeds 150, the light is absorbed by the powder before reaching the lower part of the green sheet, and the light cannot be cured because the light does not pass through to the lower sheet. As a result, they come off during development, making it difficult to form via holes.

In the present invention, Pb, Bi, Fe, Ni, M contained in the ceramic powder or the ultraviolet absorber are used.
Metals such as n, Co, and Mg and oxides thereof may react with carboxyl groups of the photosensitive polymer contained in the paste, causing the paste to gel in a short period of time, forming a lump and making it impossible to print as a paste. This is presumed to be an ionic crosslinking reaction between the photosensitive polymer and the above-mentioned metal or oxide powder. In order to prevent such a crosslinking reaction, not only the photosensitive polymer but also a photoreactive compound, It is preferable to add a compound (stabilizer) that does not adversely affect the polymerization initiator or the plasticizer to prevent gelation. That is, it is preferable to stabilize the photosensitive green sheet by subjecting the powder to a surface treatment with a compound having an effect of forming a complex with a metal or oxide powder causing a gelling reaction or forming a salt with an acid functional group.

As a stabilizer satisfying the above requirements, a triazole compound can be preferably used. Among the triazole compounds, benzotriazole works particularly effectively. Hexamethylenetetramine, lithium naphthenate (Li), and the like are also effective in suppressing gelation.

The method of surface-treating a metal powder and a metal oxide powder in a ceramic powder or an ultraviolet absorber using benzotriazole is as follows. That is, a predetermined amount of benzotriazole is dissolved in an organic solvent such as methyl acetate, ethyl acetate, ethyl alcohol, and methyl alcohol, and immersed in a solution for 1 to 24 hours so that these powders can be sufficiently immersed. Is preferred. After immersion, the powder is preferably air-dried, preferably at 20 to 30 ° C., and the solvent is evaporated to obtain a powder which has been subjected to a triazole treatment.

The ratio of the stabilizer used in the present invention (stabilizer / metal and metal oxide in the ceramic powder or ultraviolet absorber) is preferably 0.2 to 4% by weight, more preferably 0.4 to 3% by weight. More preferably, it is% by weight. 0.
If it is less than 2% by weight, there is no effect in preventing the cross-linking reaction of the polymer, and it is easy to gel in a short time. On the other hand, if the content exceeds 4% by weight, the amount of the stabilizer becomes too large, and it becomes difficult to remove the binder such as the polymer binder, the photoreactive compound and the stabilizer during the firing of the green sheet in a non-oxidizing atmosphere. Characteristics are degraded.

In the present invention, a sensitizer, a sensitization aid, a photopolymerization accelerator, a thermal polymerization inhibitor, a plasticizer, an antioxidant, a dispersant, an organic or inorganic precipitation inhibitor, etc. are contained in the ceramic green sheet. Is also preferably performed.

A sensitizer, a sensitization aid, and a photopolymerization accelerator are added to improve high sensitivity. Sensitizer, sensitization aid,
Specific examples of the photopolymerization accelerator 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-diethylaminobenzal) 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-tetrazolazole, 1-phenyl-5-ethoxycarbonylthio- And tetrazole. In the present invention, one or more of these can be used. Some sensitizers can also be used as photopolymerization initiators. When a sensitizer is added to the ceramic green sheet of the present invention, the addition amount is usually 0 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 portion 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 usually 0.1 to the sum of the acrylic copolymer having an ethylenically unsaturated group in the side chain and the photoreactive polymerizable compound.
1 to 20% by weight, more preferably 0.5 to 10% by weight
It is. If the amount of the thermal polymerization inhibitor is too small, the effect of improving the thermal stability during storage is not exhibited, and if the amount of the thermal polymerization inhibitor is too large, the residual ratio of the exposed portion may be too small. is there.

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

An antioxidant is added to prevent the acrylic copolymer from oxidizing during storage. Specific examples of the antioxidant include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-4-ethylphenol, and 2,2-methylene-bis. -(4-methyl-6-t-butylphenol), 2,2
-Methylene-bis- (4-ethyl-6-t-butylphenol), 4,4-thibis- (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 acid] glycol ester, dilaurylthiodipropionate, triphenylphosphite, and the like. When adding an antioxidant, the amount of addition is usually ceramic powder, acrylic copolymer having an ethylenically unsaturated group in the side chain,
It is 0.01 to 5% by weight, more preferably 0.1 to 1% by weight, based on the total of the photoreactive polymerizable compound, glass frit and photopolymerization initiator. If the amount of the antioxidant is small, the effect of preventing 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 portion may be too small.

The preferred composition of the slurry for forming a ceramic green sheet of the present invention is preferably selected in the following range.

(A) ceramic powder; (a),
(B) an acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in a side chain and a photoreactive compound;
18 to 6% by weight based on the sum of (a) and (b) (c) Photopolymerization initiator; 2 to 25% by weight based on (b) (d) Ultraviolet light absorber; 0 based on (a) .05-
More preferably, the composition of the ceramic powders (a), (b) and (d) is 85% by weight.
It should be selected in the range of -92% by weight, 15-8% by weight, and 0.1-1% by weight. When it is in this range, ultraviolet rays are well transmitted at the time of exposure, the function of photo-curing is sufficiently exhibited, and the occurrence of a residual film of the unexposed portion at the time of subsequent development can be almost eliminated, and a high roundness is obtained. Via holes can be formed. In particular, by setting the total amount of the acrylic copolymer and the photoreactive compound as the component (b) within this range, there is an advantage that the sintered body after firing becomes dense and a high-strength ceramic substrate can be obtained. .

The slurry for a ceramic 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. It can be produced by dispersing a ceramic powder and an ultraviolet absorber. 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 start An organic solvent in which the mixed solution of the agent and the photoreactive compound can be dissolved may be added. The organic solvent used at this time may be any solvent that can dissolve a mixture of an acrylic copolymer having an ethylenically unsaturated group in a side chain, a photopolymerization initiator, and a photoreactive compound. For example, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl ethyl ketone, dioxane, acetone, cyclohexanone, cyclopentanone, isobutyl alcohol, isopropyl alcohol, tetrahydrofuran, dimethyl sulfoxide, γ-butyrolactone,
Toluene, acetone, methyl ethyl ketone, trichlorethylene, methyl isobutyl ketone, isophorone, and the like, and an organic solvent mixture containing at least one of these are used.

If necessary, an organic solvent, a stabilizer, a sensitizer, a sensitizing aid, a photopolymerization accelerator, a thermal polymerization inhibitor,
A slurry is prepared by adding a plasticizer, an antioxidant, a dispersant, an organic or inorganic precipitation inhibitor and the like, and pulverizing and mixing with a ball mill or an attritor for, for example, 12 to 48 hours. Further, if air bubbles remain in the slurry, they become defects after sheet molding. Therefore, it is preferable to remove the air bubbles by using a defoaming machine.

The above-mentioned organic solvent is added as needed to adjust the viscosity of the slurry. The preferred viscosity is 1000-5000 cps (centipoise),
Within this range, the thickness of the sheet can be adjusted uniformly.
The obtained slurry is continuously coated on a film such as a polyester film using a doctor blade to a thickness of 10 to 60.
Mold to 0 μm. Then, at a temperature of 80 to 120 ° C, 10
Heat for a minute to one hour to evaporate the solvents to form a ceramic 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 500 μm, preferably 30 to 200 μm. If it exceeds 500 μm, it will not transmit sufficiently to exposure to ultraviolet light, and the effect of photocuring will be weakened. If the thickness is less than 10 μm, it becomes difficult to handle the green sheet. More preferred sheet thickness is 0.0
1 to 0.05 mm. Within this range, the diameter is 0.01
There is an advantage that a via hole having a thickness of up to 0.02 mm can be formed without a difference in upper and lower hole diameters. The resolution of the via hole varies depending on the thickness of the green sheet. However, the aspect ratio (sheet thickness / via hole diameter) is preferably 1 or less since the ultraviolet rays can be sufficiently transmitted. 40
In the case of a thickness of μm, formation of a via hole of 40 μm is preferred.

The ceramic green sheet is exposed using a usual photolithography method. The active light source used at this time is, for example, ultraviolet light, electron beam, X-ray.
Among them, ultraviolet rays are preferable, and as the light source, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a halogen lamp, a germicidal lamp and the like can be used. Among these, an ultra-high pressure mercury lamp is preferable. Exposure conditions vary depending on the thickness of the green sheet and the like.
Exposure is preferably performed for 1 to 30 minutes using an ultra-high pressure mercury lamp having an output of W / cm ² . The exposure method can be appropriately selected depending on the thickness of the green sheet.
When the aspect ratio is more than m and the aspect ratio is 0.2 to 1, it is preferable to perform double-sided exposure since via holes having no difference in upper and lower hole diameters can be formed.

After the exposure, development is performed using a developing solution to remove portions that have not been photocured, to form a so-called negative pattern, and to form via holes having a via hole diameter of 0.001 to 0.2 mm. The pitch is 0.02 to 0.5 mm. As a developing method, an immersion method or a spray method is used. As the developer, an organic solvent in which a mixture of the acrylic copolymer having an ethylenically unsaturated group in the side chain, a photoreactive compound, and a photopolymerization initiator can be used. Water may be added to the organic solvent as long as the solvent does not lose its solubility. When a carboxyl group is present in the side chain of the acrylic copolymer, development can be performed with an aqueous alkali solution. As the alkali aqueous solution, a metal alkali aqueous solution such as a sodium hydroxide or calcium hydroxide aqueous solution can be used, but it is preferable to use an organic alkali aqueous solution since the alkali component can be easily removed at the time of 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
It is 5% by weight, more preferably 0.1 to 1% by weight. If the alkali concentration is too low, the unexposed portion is not removed, and if the alkali concentration is too high, the exposed portion may be peeled off and corroded, which is not good.

The preparation, sheet molding, exposure and development steps of the green sheet of the present invention must be performed in a place where ultraviolet rays can be blocked. Otherwise, the slurry and the green sheet are photo-cured by ultraviolet rays, and a green sheet having the effects of the present invention cannot be obtained.

Next, a conductor for interlayer connection of wiring is formed on the signal layer or the power supply layer in the via hole using a conductor paste. Embedding of the conductor paste is the same as that used for forming the wiring pattern or another, using copper, silver, silver-palladium, tungsten, molybdenum or gold conductor paste, by screen printing, squeegee, dispenser or roller method Do. The embedding of the conductive paste into the via holes of the green sheet is repeatedly performed for each number of layers.

Further, a predetermined conductor, insulator or resistor pattern is printed on the sheet surface as required. Also, a guide hole is formed in the same manner as in 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.
Adhesion is performed at a pressure of ² to produce a sheet composed of a multilayer substrate.

Next, firing is performed in a firing furnace to form a multilayer ceramic green sheet having conductors formed in the via holes. The firing atmosphere and temperature vary depending on the type of ceramic substrate and conductor. In the case of a low-temperature multilayer substrate made of glass / ceramics, it is usually 850 to 1000 ° C.
The insulating layer is fired by holding at the temperature for several hours. In the case of an alumina or aluminum nitride substrate, baking is usually performed at a temperature of 1600 ° C. for several hours. A conductor such as Cu, W, Mo, or W-Mo is fired in a neutral atmosphere such as nitrogen or a reducing atmosphere containing hydrogen. Acrylic copolymer having an ethylenically unsaturated group in the side chain contained in the photosensitive green sheet during firing,
Any atmosphere may be used as long as it allows oxidation and evaporation of organic substances such as a photoreactive polymerizable compound, a stabilizer, and a solvent. For example, when the conductor is Cu, W, Mo, or W-Mo, firing can be performed in an atmosphere containing 3 to 100 ppm of oxygen and the balance controlled by a neutral gas such as nitrogen or argon or steam. As firing conditions, the organic binder may be completely oxidized and evaporated at a temperature of 300 to 600 ° C. for 5 minutes to several hours, and then at a temperature of 800 to 1600 ° C. for several hours, and then a ceramic multilayer substrate may be manufactured. .

The amount of carbon remaining in the fired multilayer substrate is 2
It is preferably at most 50 ppm. If the amount of residual carbon is large, problems such as a decrease in porosity, 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 of the multilayer substrate occur. More preferably, 1
It is at most 00 ppm, more preferably at most 50 ppm.

[0086]

The present invention will be described below in detail with reference to examples. In the following description, the amounts used and the proportions are all expressed by weight.

Example

A. Ceramics component 99.5% purity alumina powder; average particle size 2.8μ
m, spherical powder having a specific surface area of 0.7 m ² / g cordierite powder; spherical powder having an average particle diameter of 1.4 μm, specific surface area of 3.2 m ² / g glass-ceramic powder; 96% pure alumina powder 50%, silicic acid 50% salt glass composition powder (alumina powder is a spherical powder having an average particle size of 2.8 μm and a specific surface area of 0.7 m ² / g; glass composition is Si
O ₂ ; 70%, BaO; 3%, Al ₂ O ₃ ; 7%, B ₂
O ₃ ; 18%, Na ₂ O; 2%. After making into fine powder with an attritor in advance, it was subjected to spheroidizing treatment with a granulating dryer.
Average particle size of powder 2.2 μm, specific surface area 5.0 m ² /
g. )

B. Ultraviolet light absorber Organic dye; azo dye; Sudan IV, chemical formula; C ₂₄ H ₂₀ N ₄ O, molecular weight; 380.45 organic pigment; azo dye; oil yellow-OB (Oil)
Yellow OB), chemical 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
A polymer obtained by addition reaction of glycidyl acrylate (GMA) of 0.4 equivalent (corresponding to 40%) to the carboxyl group (MAA) of the copolymer comprising t). The acid value of the polymer was 95. The number average molecular weight (Mn) of the polymer is 12000, and the weight average molecular weight (Mw) is 33.
000, the Z-average molecular weight (Mz) was 65,000, and the ratio (Mw / Mz) representing the degree of dispersion was 2.75.

D. Photoreactive compound (monomer) Trimethylol, propane, triacrylate

E. Solvent Mixed solvent of isopropyl alcohol (IPA), butyl alcohol (BA) and methyl ethyl ketone (MEK) (16: 2: 82)

F. Photopolymerization initiator 2-methyl-1- [4- (methylthio) phenyl] -2
Morpholinopropanone-1 and 2,4-diethylthioxanthone were added to the sum of the
0% by weight was added.

G. Sensitization aid or photopolymerization accelerator P-dimethylaminobenzoic acid ethyl ester and 3,
3'-carbonylbis (7-diethylaminocoumarin)
Is 10% by weight based on the sum of the polymer and the monomer.
Was added.

H. Plasticizer dibutyl phthalate (DBP)

I. Dispersant Cation or "florene" (G-700, maleic acid partial ester) is added to ceramic powder in an amount of 1.5
% By weight.

<Preparation and Evaluation of Green Sheet> a. Preparation of Organic Vehicle Solvent and polymer binder are mixed and stirred
Heat to 20 ° C. to dissolve all polymer binders homogeneously. Then, the solution was cooled to room temperature, and a photopolymerization initiator was added and dissolved. Thereafter, this solution was filtered using a 400-mesh filter to produce an organic vehicle.

B. Stabilization treatment of glass-ceramics powder After dissolving 1.5% of benzotriazole with respect to the glass-ceramics powder in methyl acetate, the glass-ceramics powder was immersed in the solution for 12 hours. After immersion, 2
Drying was performed in a fume hood at 0 to 25 ° C., and the solvent was evaporated to produce a glass-ceramics powder which was subjected to a triazole treatment.

C. Preparation of light absorber-added powder Predetermined amount of ultraviolet light absorber (based on ceramic powder)
A 50% solution of a cationic dispersant in a solution weighed and dissolved in isopropyl alcohol (IPA) (solvent is IPA)
Was added and stirred homogeneously with a homogenizer. Next, a predetermined amount of ceramic powder is added to this solution and homogeneously dispersed.
While mixing, use a rotary evaporator to
Dry at a temperature of ~ 200 <0> C and evaporate the IPA. In this way, a powder in which the surface of the ceramic powder was uniformly coated (capsulated) with the organic dye film was produced.
Tables 1 and 2 show integral values of absorbance of the powder at 350 to 450 nm. What is the coating thickness? It was 5 nm.

D. Slurry preparation The slurry is prepared by adding a photoreactive compound, a ceramic powder coated with an ultraviolet absorber, a fluorene dispersant, a sensitizing aid or a photopolymerization accelerator, and a plasticizer to the above organic vehicle so as to have a predetermined composition. And 24 with an attritor
It was prepared by wet mixing and dispersion for hours. Further, the slurry was prepared by defoaming with a vacuum stirrer for 24 hours. The viscosity of the prepared slurry was measured using a Brookfield viscometer (model: RV
DV-II +) at 2000 rpm
Matched in ps. Tables 1 and 2 show the slurry compositions.

E. The green sheet is formed by molding the gap between the polyester carrier film and the blade in a room shielded from ultraviolet rays by 0.6 to 0.8 mm.
The molding was performed by a doctor blade method at a molding speed of 1 m / min. The thickness of the obtained green sheet is 105-
115 μm. Met.

F. Exposure and development The green sheet produced above was cut into a 120 mm square, and then heated at a temperature of 90 ° C. for 40 minutes to evaporate the solvent.
Next, using a chrome mask having a diameter of 60 μm and a number of 6000 via holes, 1
Ultraviolet exposure was performed using an ultra-high pressure mercury lamp having an output of 500 mJ / cm ² . Next, the substrate was immersed in a 0.5% by weight aqueous solution of monoethanolamine kept at 25 ° C. to develop, and then the via holes that had not been photocured were washed with water using a spray.

G. Embedding conductors in via holes, pattern formation and lamination Next, thick film paste of tungsten (when using ceramic powder) or silver-palladium alloy (when using ceramic powder or) in screen holes in green sheet via holes Was embedded to form a conductor for interlayer connection of wiring. A predetermined circuit pattern was printed on the surface of the green sheet using the same thick film paste as described above.

Six green sheets on which conductors are printed are stacked using guide holes, and at 120 ° C., 150 kg /
Thermocompression bonding was performed at a pressure of cm ² to produce a multilayer ceramic green sheet composed of six layers.

H. Green sheet using sintered silver-palladium alloy as conductor
After firing for 1 hour in air at 00 ° C. and evaporating the binder, sintering is performed at 900 to 1000 ° C. for 1.5 hours,
A multilayer ceramic substrate was obtained.

A green sheet using tungsten as a conductor is placed in an atmosphere of H ₂ (hydrogen) gas and N ₂ (nitrogen) gas.
After firing at 00 ° C. for 5 hours to evaporate the binder, sintering was performed at 1600 ° C. for 1.5 hours to obtain a multilayer ceramic substrate.

Tables 1 and 2 show the sintering temperatures.

I. Green Sheet Strength Measurement The tensile strength of the three types of green sheets prepared above before and after exposure to ultraviolet light was measured at an exposure of 1000 mJ / cm ² . The results are shown in Tables 1 and 2.

J. Evaluation The ceramic multilayer substrate after firing was subjected to a leak current, presence / absence of disconnection failure from a via-hole portion, a change rate of resistance of the via-hole, and a wet / medium load (THB) test. The THB test examines the initial insulation resistance,
After holding for 1500 hours in an environment of 5 ° C. and a humidity of 85%, 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.

[0110]

[Table 1]

[Table 2] In the obtained multilayer ceramic wiring board, fine via holes were uniformly formed. Since the via hole was fine, no generation of a pore or disconnection was observed at the via hole forming portion, and as a result, high reliability was obtained. Also, the signal propagation speed was greatly reduced as compared with a conventional multilayer substrate having a via hole diameter of 4 to 8 times. Furthermore, there is no need for a screen for forming via holes,
Self-alignment has been achieved, eliminating the conventional misalignment.

Further, the light-cured green sheet has a tensile strength of the conventional uncured sheet of 1.0 to 1.5 MPa.
Greatly increased to 2.7 to 8.0 MPa. The improved strength facilitates handling of thin sheets even in processes such as conductor embedding, press lamination, and peeling of the sheet from the film, so that miniaturization and higher density of the ceramic multilayer substrate can be expected.

Comparative Examples 1 and 2 Using alumina powder (Comparative Example 1) and cordierite powder (Comparative Example 2) among the above ceramic powders, powder composition 53%, acrylate resin 10%, toluene 24%, isopropyl 8% of alcohol and 5% of dibutyl phthalate were mixed with an attritor, and a green sheet having a thickness of 150 μm was produced by a doctor blade method under the same conditions as described above. Next, 2,000 holes having a via hole diameter of 80 μm were machined by a punch press using a mold, and a multilayer ceramic wiring board was obtained in the same manner as in the example.

The obtained multilayer ceramic wiring board has
Cracks, burrs, around conductor wiring and via holes
Many electrode peelings were observed.

[0114]

According to the green sheet of the present invention, via holes and through holes can be formed extremely easily and accurately, and fine holes can be reliably formed at low cost.

Further, the ceramic multilayer substrate formed by the ceramic green sheet of the present invention is extremely excellent in performance, and has a significantly reduced via hole and through hole, so that high reliability and high reliability can be obtained. Higher performance and higher density can be achieved. For example, the total number of via holes in a green sheet having a size of 120 mm square is 4000 to 15000, and among them, the number of signal holes is about 3000. According to the present invention, the via hole diameter is reduced and uniform. In addition, the high-precision via hole significantly improves the reliability of the conductor paste in addition to miniaturization and high density. That is, by setting the via hole diameter to 0.08 mm or less, preferably 0.05 mm or less, printing of the conductor paste in the via hole becomes easy, and insufficient filling or dropout is prevented. Further, when the conductive paste is fired, the shrinkage due to firing becomes smaller as the via hole diameter becomes finer, so that a remarkable practical effect is exhibited such that electrode cracking does not occur.

Further, when the conductive paste is baked, the shrinkage due to the calcination becomes smaller as the diameter of the via hole becomes smaller, so that a remarkable practical effect such as no electrode cracking is produced.

[Brief description of the drawings]

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

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C04B 35/622 H05K 3/00

Claims (9)

(57) [Claims] 1. A ceramic green sheet comprising a ceramic powder, an ultraviolet absorber and a photosensitive resin composition. 2. A ceramic comprising a ceramic powder, an ultraviolet absorber, an acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in a side chain, a photoreactive compound and a photopolymerization initiator. Green sheet. 3. The ceramic powder is at least one selected from the group consisting of alumina, zirconia, magnesia, beryllia, mullite, cordierite, spinel, forsterite, anorthite, cellian, silica and aluminum nitride. Claim 1 or 2
The described ceramic green sheet. Wherein the ceramic powder is oxide equivalent representation SiO ₂ 30 to 70 wt% Al ₂ O ₃ 5~25 wt% CaO 5 to 25 wt% MgO 0 wt% B ₂ O ₃ in 3-50 In a composition range of 0 to 15% by weight of TiO _2, 40 to 60% by weight of a glass composition powder having a total amount of 95% by weight or more, alumina, zirconia, magnesia, beryllia, mullite, cordierite, spinel, forsterite, The ceramic green sheet according to claim 1 or 2, wherein the raw material mixture is a raw material mixture with 60 to 40% by weight of at least one inorganic filler powder selected from the group consisting of anorthite, Celsian, silica, and aluminum nitride. 5. The ceramic green sheet according to claim 1, wherein the ultraviolet light absorbing agent is an organic dye. 6. The organic dye is at least one selected from the group consisting of azo dyes, quinoline dyes, aminoketone dyes, anthraquinone dyes, benzophenone dyes, benzotriazole dyes, cyanoacrylate dyes and xanthene dyes. The ceramic green sheet according to claim 5, which is a kind. 7. The ceramic green sheet according to claim 1, wherein the integrated value of the absorbance of the ultraviolet absorbent at 350 to 450 nm is 30 to 150. 8. The ceramic green sheet according to claim 1, wherein the ceramic powder is coated with the ultraviolet absorbent. 9. The ceramic green sheet according to claim 1, further comprising a stabilizer.