JP3163515B2 - 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 green 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 preferably used for a ceramic substrate, and more particularly to a green sheet made of ceramics suitably used for a multilayer ceramic substrate.

[0002]

2. Description of the Related Art Multilayer ceramic substrates are roughly classified into a thick film printing lamination method and a green sheet method. Further, the green sheet method includes a lamination method and a printing method. The green sheet printing method is a method in which a conductive paste and an insulating paste are alternately printed and laminated on a green sheet to form a multilayer.
After repeating printing and drying, firing is completed once. The green sheet lamination method is almost the same as the green sheet printing method.However, when forming a multilayer, a conductor is printed, a large number of via-processed green sheets are laminated, thermocompression bonded, and then fired. This is a method of forming a multilayer substrate.

Conventional ceramic green sheets are:
As described in JP-A-51-19009, JP-B-3-5075, JP-B-3-53269, JP-A-2-141458, JP-A-1-201063 and JP-A-64-87549, ordinary After appropriately blending a ceramic powder, an organic binder, a plasticizer, a solvent, and a dispersant as necessary, mixing and forming a slurry, the obtained slurry is formed into a sheet by a known method such as a doctor blade method. It is made. In this case, as the organic binder, which will be described in detail later, polyvinyl butyral,
Butyl methacrylate resin, polymethyl methacrylate resin and the like are used.

In recent years, there has been a need for lowering the resistance of conductor circuits by high-frequency / high-speed signal processing (corresponding to the age of digitalization), high-density mounting of LSIs, and downsizing of AV (audio / video), personal computers, cellular phones, and the like. Is increasing.
In addition to the low resistance of the conductor circuit, conductors such as copper, tungsten and molybdenum migrate in addition to low resistance (electrode conductor reacts with a small amount of moisture, ionizes and moves to the opposing electrode, It has attracted attention as the most promising conductor because it has little occurrence of the phenomenon of lowering the insulation resistance. In the case of the green sheet laminating method or the printing method, the conductor such as copper is used for forming the circuit of the inner layer and the surface layer of the ceramic / green sheet multilayer board. It is necessary to simultaneously fire ceramic green sheets in a single operation. In addition, the number of layers of the green sheet is multi-layered to 5 to 150 layers due to the demand for miniaturization and high-density mounting of supercomputers, personal computers, AVs, mobile phones, and the like, and contains a large amount of an organic binder.

[0005] However, when a conductor such as copper is fired in an oxidizing atmosphere, copper and the like are oxidized, so it is necessary to fire in a non-oxidizing atmosphere. Therefore, it is necessary to fire the green sheet in a non-oxidizing atmosphere at the same time as the conductor such as copper.
For that purpose, the organic binder used in forming the green sheet must be removed by firing in a non-oxidizing atmosphere.

The acrylate-methacrylate copolymer disclosed in the above-mentioned JP-A-1-201063 and JP-A-51-201063 are disclosed.
Binders such as polyvinyl butyral resin described in JP 19009 are oxidized and removed when baked in an oxidizing atmosphere, but when baked in a non-oxidizing atmosphere, decomposition and scattering of the organic binder are insufficient. Therefore, there is a problem that a large amount of carbon remains in the fired ceramic multilayer substrate, which causes insulation failure of the substrate. In the case of a conventionally proposed green sheet containing an organic binder that can be fired in a non-oxidizing atmosphere, there are problems such as low strength of the green sheet and poor handling properties. It is also needed from raising. Furthermore, when a conventional green sheet is formed into a multi-layer green sheet, it takes 1 to 1 to remove the binder.
There was a disadvantage that the cost increased because it took three weeks.

On the other hand, alumina (Al ₂ O) is used as ceramic powder used for the ceramic green sheet.
₃ ), zirconia (ZrO ₂ ), magnesia (Mg
O), mullite _{(3Al 2 O 3 · 2SiO 2} ), anorthite _{(CaO · Al 2 O 3 ·} 2SiO 2), forsterite (2MgO · _SiO 2), celsian (BaO
.Al ₂ O ₃ .2SiO ₂ ), spinel (MgO.Al)
₂ O ₃ ), cordierite (5SiO ₂ .2Al ₂ O ₃₎
.2MgO), clinoenstatite (MgO.SiO)
₂ ), a powder such as silica (SiO ₂ ), or a low-temperature fired ceramic powder such as SiO ₂ —B ₂ O _{3
bO-SiO 2 -Al 2 O 3} -B 2 O 3 based glass, Ca
_{O-SiO 2 -Al 2 O 3} -B 2 O 3 system, such as a glass A
l ₂ O _3, quartz _{(SiO 2),} ZrO 2, glass was added ceramic component such as cordierite - ceramic composite system or _MgO-Al 2 O 3 -SiO ₂ system and _Li 2 O-
Such as Al ₂ O ₃ -SiO ₂ -based crystallized glass is used. The crystallized glass is, for example, MgO—Al ₂ O ₃ —Si
B ₂ O ₃ and a nucleating substance are added to O ₂ , and 900 ° to 10 °
It is baked at 00 ° C. to precipitate cordierite crystals to increase the strength, and to add Li ₂ O—Al ₂ O ₃ —SiO ₂ to B ₂
O ₃ and a nucleating substance are added thereto to precipitate spodumene, and a material having high strength is also used.

Conventional organic binders include polyvinyl alcohol, polyvinyl butyral, methacrylate polymer, acrylate polymer, acrylate-methacrylate copolymer, α-methylstyrene polymer, butyl methacrylate resin and the like. Is used, as a plasticizer, dibutyl phthalate, dioctyl phthalate, polyethylene glycol, glycerin and the like are used, and as a solvent, alcohol, toluene, acetone, methyl ethyl ketone, butanol, trichloroethylene, methyl isobutyl ketone, isophorone and the like are used. ing.

The obtained green sheet is processed into a desired shape by a cutter or a punching die, and then a via hole or a through hole (hereinafter, typically described as a via hole) is formed on the green sheet by a punch die to form a hole. Drilling with a mold or laser. 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 the carrier film is peeled off from the back surface of the green sheet and removed. Then, the green sheet is punched out to a required work size, and the green sheet is punched to form a via hole, and the green sheet is filled with a conductive paste by a normal screen printing method. If the thickness of the green sheet is less than 50 μm, it is perforated together with the carrier film,
A via hole was formed.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the drawbacks of ceramic green sheets which use a conductor such as copper for the inner layer of the green sheet and fire in a non-oxidizing atmosphere. An object of the present invention is to provide a ceramic green sheet containing a novel organic binder, while eliminating the drawbacks of the conventional ceramic green sheet.

[0011]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
The particle size is 0.05-4 μm and the specific surface area is 5-20 m ² /
g ceramic powder and butyl methacrylate, a methacrylate having 8 or more carbon atoms having an alkyl side chain at the β-position,
A methacrylate unit selected from the group consisting of a hydroxyl group-containing methacrylate and a cycloalkyl group-containing methacrylate occupies 80% by weight or more, and contains a methacrylate-based copolymer in which the content of the butyl methacrylate unit is 50% by weight or more. This is achieved by a ceramic green sheet.

In the above, the ceramic powder is alumina, zirconia, magnesia, beryllia, mullite,
It is more preferably achieved by a ceramic green sheet containing at least one selected from the group consisting of cordierite, spinel, forsterite, anorthite, serdian, clinoenstatite and silica.

[0013] SiO ₂ 30 to 70 weight ceramic powder in terms of oxide title% _Al 2 _O 3 6~25 wt% CaO 5 to 25 wt% MgO 1 to 10 wt% _B 2 _O 3 3~50 weight in the % TiO _{2 in} a composition range of 1 to 15% by weight, and 40 to 60% by weight of a glass composition powder having a total amount of 95% by weight or more, and alumina, zirconia, magnesia, beryllia, mullite, cordierite, forsterite, spinel, and Annault. This is more preferably achieved by a ceramic green sheet characterized by being a raw material mixture with 60 to 40% by weight of at least one inorganic filler powder selected from the group consisting of site, Celsian, clinoenstatite and silica.

The binder used in the ceramic green sheet of the present invention is easily decomposed and scattered under green sheet moldability, strength, and thermal decomposability, particularly under firing and sintering conditions in a non-oxidizing atmosphere. Methacrylate, butyl methacrylate, a methacrylate having 8 or more carbon atoms having an alkyl side chain at the β-position, which is less likely to remain as undecomposed carbide in the sheet,
A methacrylate unit selected from a hydroxyl group-containing methacrylate and a cycloalkyl group-containing methacrylate occupies 80% by weight or more, and a methacrylate-based copolymer in which the content of the butyl methacrylate unit is 50% by weight or more. I do. Needless to say, a copolymer is a polymer having two or more monomer components, not to mention a copolymer. Specifically, two or more butyl methacrylates are used as comonomer components, or at least one of butyl methacrylate and other than butyl methacrylate. The above methacrylate is contained as a comonomer component.

The reason why butyl methacrylate, methacrylate having 8 or more carbon atoms having an alkyl side chain at the β-position, methacrylate having a hydroxyl group and methacrylate having a cycloalkyl group were selected as the main monomer units of the methacrylate copolymer is as follows. The polymer contained as a unit easily undergoes depolymerization, and is easily depolymerized and decomposed and scattered even when heated in a non-oxidizing atmosphere. When these monomer units account for 80% by weight or more, green sheet moldability, This is because, when the content of the butyl methacrylate unit having excellent strength, handleability and thermal decomposability and excellent depolymerizability is 50% by weight or more, the thermal decomposability becomes particularly good.

In the present invention, the content of the monomer unit in the copolymer is shown in% by weight, but this is a% by weight in terms of the monomer used. The methacrylate copolymer of the present invention has a total content of butyl methacrylate, hydroxyl group-containing methacrylate, methacrylate having 8 or more carbon atoms having an alkyl side chain at the β-position and cycloalkyl group-containing methacrylate of 80% by weight or more, preferably 90
Weight% or more, and the total content of butyl methacrylate is 5
It is required to be 0% by weight or more, preferably 60% by weight or more, whereby the copolymer is liable to depolymerize and easily when heated not only in an oxidizing atmosphere but also in a non-oxidizing atmosphere. An effect is obtained in that it is depolymerized, decomposed and scattered, and hardly remains as a carbide.

Here, butyl methacrylate is n-
Butyl methacrylate, isobutyl methacrylate, s
Examples thereof include ec-butyl methacrylate and tert-butyl methacrylate. Among them, it is preferable that isobutyl methacrylate is excellent in thermal decomposability and contained at least 50% by weight as a butyl methacrylate monomer unit. Isobutyl methacrylate is 50% by weight as a monomer unit
If it is lower than the above value, good thermal decomposability cannot be obtained particularly under severe conditions of a non-oxidizing atmosphere.

Specific examples of the methacrylate having an alkyl side chain at the β-position and having 8 or more carbon atoms include 2-methylbutyl methacrylate, 2-methylpentyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, isodecyl methacrylate, and isodecyl methacrylate. Examples thereof include lauryl methacrylate and isostearyl methacrylate, and among them, 2-ethylhexyl methacrylate is particularly preferred.

Specific examples of the hydroxyl group-containing methacrylate include 2-hydroxyethyl methacrylate and 2-hydroxyethyl methacrylate.
Hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, glycerol monomethacrylate, trimethylolpropane monomethacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate and the like, among which particularly preferred are 2 -Hydroxyethyl methacrylate, 2
-Hydroxypropyl methacrylate. Specific examples of cycloalkyl group-containing methacrylate include cyclohexyl methacrylate, cycloheptyl methacrylate, cyclooctyl methacrylate, and the like.
Of these, cyclohexyl methacrylate is particularly preferred. The methacrylate copolymer of the present invention may also contain other monomer components. These other comonomer components other than the above include copolymerizable unsaturated carboxylic acids,
Acrylate-based monomers and / or styrene-based monomers are preferred in view of green sheet moldability, strength, and handleability.

The unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid,
Maleic acid half-esters such as monoisopropyl maleate and the like, acrylate monomers such as ethyl acrylate, butyl acrylate, 2-methoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate,
Examples include dimethylaminoacrylate and the like, and styrene-based monomers include styrene, α-methylstyrene, β-methylstyrene, α-ethylstyrene, β-ethylstyrene, vinylstyrene and the like. Comonomer components other than these may also be included. Examples of these include methacrylate, methacrylonitrile, acrylamide, vinyl acetate, and vinyl chloride other than those described above. Specific examples of the methacrylate other than the above, methyl methacrylate, ethyl methacrylate, propyl methacrylate,
Examples include 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, octyl methacrylate, lauryl methacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate and the like.

When a comonomer as an optional component is used, if the content in the methacrylate-based copolymer is 20% by weight or more, thermal decomposability or copolymerizability is hindered, so the content must be suppressed to less than 20% by weight. There is. Among these comonomer components, unsaturated carboxylic acids have the effect of imparting an appropriate acid value to the methacrylate-based copolymer to increase the dispersibility and dispersion stability of the ceramic powder, and improve green sheet moldability, strength, and handleability. For the purpose of the above, it is desirable to use 10% by weight or less, more preferably 0.1 to 5% by weight. Particularly preferred is methacrylic acid. Since the preferred acid value of the copolymer varies depending on the type, polarity, acidity, basicity, amount of acid, and the like of the ceramic powder used, it is desirable to select an optimum value according to them. If the acid value is too high, the decomposition / dispersibility at the time of debinding tends to deteriorate, so the acid value is preferably adjusted to 0.1 to 20, preferably 1 to 10. Styrene-based monomers have excellent depolymerizability and have the effect of lowering the decomposition temperature of the methacrylate-based copolymer composition.
It is also possible to add up to. Particularly preferred is α-
It is methylstyrene. Acrylate-based monomers such as propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate can be used in small amounts for the purpose of improving the green sheet moldability and handleability such as adjusting the glass transition temperature, but the copolymer of the acrylate-based monomer is methacrylate. Since the depolymerization property is inferior to that of the copolymer of the system monomer, it is desirable that the addition amount be 10% by weight or less, preferably 5% by weight or less.

The polymerization method for obtaining the methacrylate-based copolymer of the present invention is not limited at all, but the most common method is the method in the presence of a radical polymerization initiator such as peroxide, hydroperoxide or azoisobutyronitrile. This is a method in which a normal polymerization method such as suspension polymerization, solution polymerization, or emulsion polymerization is employed, and the reaction is usually performed at -10 to 150 ° C for several minutes to several hours. In this case, if necessary, a chain transfer agent can be further added during the polymerization reaction, and the molecular weight is preferably adjusted by the amount of the catalyst, the monomer concentration and the like.

The effect of the methacrylate copolymer used in the present invention differs depending on the molecular weight. Since the optimum molecular weight varies depending on the specific surface area, particle size, particle size distribution, etc. of the ceramic powder, it is desirable to select an appropriate molecular weight according to the specific surface area, particle size, particle size distribution, and the like. The content of the copolymer in the range occupies 80% or more, preferably 90% or more, more preferably 95% or more, and is lower than the optimal reference value of 50,000 to 200,000 in the molecular weight range. The content ratio of the copolymer having a molecular weight to the copolymer having a molecular weight exceeding the reference value falls within the range of 1/1 to 9/1, preferably 2/1 to 5/1. A preferred value selected as the reference molecular weight is 150,000. When the ratio of the low molecular weight compound and the high molecular weight compound outside the above-mentioned molecular weight range exceeds 10% by weight, if the low molecular weight compound is too large, the performance as a binder becomes insufficient and satisfactory green sheet moldability is obtained. On the other hand, when the amount of the high molecular weight substance is too large, the decomposition and burning properties at the time of debinding are deteriorated, and the amount of carbide remaining in the ceramic sheet becomes so large that it cannot be ignored. Further, even if the content ratio within the above preferable molecular weight range satisfies the above requirements, the content ratio with the low molecular weight side copolymer exceeds the above range with respect to the optimal reference molecular weight of 50,000 to 200,000. In this case, the green sheet moldability deteriorates, while when the content ratio with the high molecular weight copolymer exceeds the above range, the amount of carbide remaining in the ceramic sheet increases.

The methacrylate copolymer used in the present invention fulfills its purpose irrespective of other requirements as long as it satisfies the requirements of the above-mentioned selected monomer, monomer unit content, molecular weight and the like. However, in order to further improve the green sheet moldability, shape retention, handleability, and easy decomposability upon debinding, a number average molecular weight of 5 is required.
000 to 100,000, preferably 10,000 to 60,000,
And a glass transition temperature of 0 to 80C, preferably 20 to 6C.
Desirably, it is 0 ° C.

The chemical composition of the ceramic powder used in the present invention is not particularly limited, and a known ceramic insulating material such as for low-temperature firing can be used as appropriate. In the present invention, the more effective ceramic powder is alumina, zirconia, magnesia, or the like. , Beryllia, mullite, cordierite, spinel, forsterite, anorthite, Celsian, clinoenstatite and silica.

More preferred ceramic powders used in the present invention include, for example, SiO ₂ , Al
A glass composition powder containing ₂ O ₃ , CaO, B ₂ O ₃ and, if necessary, MgO and TiO ₂ , alumina, zirconia, magnesia, beryllia, mullite, cordierite, forsterite, spinel, anorthite, celzian and clino It is obtained by using a raw material mixture with at least one kind of inorganic filler powder selected from the group of enstatite silica. More preferably, the ceramic powder is expressed in terms of oxide as SiO ₂ 30 to 70% by weight Al ₂ O ₃ 6 to 25% by weight CaO 5 to 25% by weight MgO 1 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 1 to 15% by weight, alumina, zirconia, magnesia, beryllia, mullite, cordierite, forsterite, spinel, anorthite, and Celsian , A raw material mixture of at least one inorganic filler powder selected from the group consisting of silica, clinoenstatite and silica at 60 to 40% by weight.

The inorganic filler is effective for improving the mechanical strength of the substrate and for controlling the coefficient of thermal expansion. In particular, alumina, zirconia, mullite, cordierite and anorthite have excellent effects. The ratio of inorganic filler is 6
If it exceeds 0% by weight, sintering becomes difficult, and sintering at 1000 ° C. or lower becomes impossible. If it is less than 40% by weight, it becomes impossible to control the thermal expansion coefficient and obtain a substrate having a low dielectric constant. Further, the composition range of the glass is preferably such that SiO ₂ is in the range of 30 to 70% by weight. Deviates from a desired value. On the other hand, if it exceeds 70% by weight, the thermal expansion coefficient of the fired substrate becomes high, and it becomes difficult to fire at 1000 ° C. or lower. Furthermore, Al ₂ O
₃ is preferably blended in the range of 6 to 25% by weight.
If the content is less than 6% by weight, the strength in the glass phase decreases, and
Baking at 000 ° C. or lower becomes difficult. If it exceeds 25% by weight, the temperature at which the glass composition is fritted becomes too high. CaO is preferably blended in the range of 5 to 25% by weight. If it is less than 5% by weight, a desired coefficient of thermal expansion cannot be obtained, and firing at 1000 ° C. or less becomes difficult. If it exceeds 25% by weight, the dielectric constant and the coefficient of thermal expansion become large. MgO is preferably blended in the range of 1 to 10% by weight, which makes it easy to control 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 to 1
In order to melt at a temperature of around 450 ° C. and to set the firing temperature of the ceramics to a value higher than Al ₂ O ₃ , the electrical, mechanical and thermal properties such as the dielectric constant, strength, coefficient of thermal expansion and sintered density are not impaired. In order to control the sintering temperature in the range of 800 to 1000 ° C., it is preferable that the amount is 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%, the stability of the glass decreases, and the recrystallization due to the reaction between the inorganic filler (crystal) and the glass may occur. Be faster. If the content exceeds 50% by weight, the phenomenon of oozing out of the glass phase when a multilayer substrate is formed is likely to occur.

It is preferable that TiO ₂ is blended in a range of 1 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 the effect is particularly remarkable in the above range.

Alumina, zirconia, magnesia, beryllia, mullite,
At least one inorganic filler powder selected from cordierite, forsterite, spinel, anorthite, serdian, clinoenstatite and silica;
As described above, a raw material mixture added with 0 to 40% by weight is preferable. However, by setting the amount of the inorganic filler powder in this range, the firing temperature of the ceramic is set to 800 to 1000 ° C., and the strength, dielectric constant, coefficient of thermal expansion, It is possible to obtain desired characteristics such as a consolidated density, a volume specific resistance, and a shrinkage ratio.

The glass powder used in combination with the inorganic filler usually contains, 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 can be contained. Further, the inorganic filler powder used in combination with the glass powder may also contain up to 5% by weight of the same impurities as in the above glass powder. Typical examples of the method for producing glass are raw materials such as SiO ₂ , Al ₂ O ₃ and C
aO, MgO, B ₂ O ₃ , and TiO ₂ are mixed so as to have a predetermined composition, melted at 1250 to 1450 ° C., rapidly cooled, made into a glass frit, and then pulverized to 0.5 to 3 μm.
This is a method for making a fine powder of m. As a raw material, a high-purity carbonate, oxide, hydroxide, or the like can be used. Also, depending on the type and composition of the glass powder, a solution raw material of an ultra-high purity alkoxide or an organic metal of 99.99% or more is used.
Using a powder made homogeneously by the gel method results in a low dielectric constant,
It is preferable because a dense and high-strength ceramic substrate can be obtained.

The ceramic powder used in the present invention must have a particle size of 0.05 to 4 μm and a specific surface area of 5 to ²⁰ m ² / g . More preferred particles
The diameter range is from 0.5 to 2 μm. If it is too fine, the shrinkage after firing becomes large, and a high-precision green sheet cannot be obtained. When the specific surface area is in this range, the green sheet has good moldability and the shrinkage after firing is small, which is preferable.

The slurry for the green sheet of the present invention comprises:
Methacrylate copolymer, butyl methacrylate,
A methacrylate unit selected from a methacrylate having 8 or more carbon atoms having an alkyl side chain at the β-position, a hydroxyl group-containing methacrylate and a cycloalkyl group-containing methacrylate accounts for 80% by weight or more, and the content of the butyl methacrylate unit is 50% by weight. % Of the methacrylate-based copolymer is dissolved in a solvent as a binder, and a ceramic powder is dispersed in the solution. As the solvent, a water-soluble or organic solvent can be used. Depending on the binder, an organic solvent may be added to a water-soluble solution. The organic solvent used at this time may be any one in which the binder and the plasticizer can be dissolved. For example, methylcellosolve, ethylcellosolve, butylcellosolve, methylethylketone, dioxane, acetone, cyclohexanone, cyclopentanone, isobutyl alcohol, isopropyl alcohol, tetrahydrofuran, dimethyl sulfoxide, γ-butyrolactone, toluene, and one or more of these. An organic solvent mixture is used.

The composition of the slurry for forming a green sheet of the present invention is preferably selected in the following range. (A) ceramic powder; 70 to 96% by weight (b) methacrylate-based copolymer; 30 to 4% by weight (c) solvent: 30 to 90% based on the sum of the above-mentioned ceramic powder and methacrylate-based copolymer component
80% by weight.

In addition to the above, if necessary, a plasticizer, a dispersant,
An anti-settling agent, a sintering aid and the like may be contained. More preferably, the composition of the ceramic powder and the methacrylate-based copolymer is 75 to 85% by weight,
It is better to select in the range of 5% by weight. If the methacrylate-based copolymer component exceeds 30% by weight, warping and swelling and cracking occur during firing, circuit misalignment during green sheet lamination tends to occur, and binder removal during firing becomes difficult. If the content is less than 4% by weight, the bonding strength as a binder is weakened, so that the green sheet moldability is poor, and cracks and cracks are liable to occur. When the solvent is 80
If the amount is more than 10% by weight, the viscosity of the slurry is so low that molding on a polyester film becomes difficult and drying takes time. If it is less than 30% by weight, the slurry viscosity is so high that molding becomes difficult.

The mixture having the above composition is ground and mixed with a ball mill or an attritor for, for example, 20 to 48 hours to prepare a slurry. Further, the above-mentioned solvent is added as needed to adjust the viscosity of the slurry. Further, if necessary, sorbitan acid esters, alkylene glycols, polycarboxylic acids and the like can be added as dispersing agents such as dibutyl phthalate, dioctyl phthalate, polyethylene glycol and glycerin as plasticizers. The slurry thus obtained is continuously formed on a polymer film such as polyester using a doctor blade to a thickness of 0.01 mm to 0.5 mm. Then 80-1
The mixture is heated at a temperature of 20 ° C. to evaporate the solvents and form a ceramic green sheet.

The thickness of the ceramic green sheet of the present invention is in the range of 0.01 to 0.5 mm, preferably 0.05 to 0.2 mm. When the thickness exceeds 0.5 mm, the substrate becomes thick when green sheets are laminated to form a multilayer wiring board. On the other hand, when the thickness is less than 0.01 mm, there is a problem in handling, which is not preferable. The ceramic green sheet thus obtained varies depending on the powder used, the type and content of the methacrylate-based copolymer and the plasticizer as the binder, and the content is 5 to 50 k.
It has a tensile strength of g / cm ² and is sufficiently resistant to handling.

Subsequently, the obtained ceramic green sheet is coated with a conductive paste such as tungsten, molybdenum, copper, silver, silver-palladium or gold in the via hole by printing, squeegee, dispenser or roller. Filling is performed to form a conductor for connection between wiring layers in the via hole. By using the resin binder of the present invention, the binder can be easily removed in a short time when the conductor is fired, so that a conductor mainly composed of copper, tungsten, and molybdenum can be preferably used.

As required, a predetermined conductor, insulator or resistor pattern is printed on the sheet surface. Also, a guide hole is formed in the same manner as in forming a via hole. Next, the necessary number of sheets are stacked using the guide holes, and the temperature is set to 90 to 130 ° C. and 50 to 200 kg / cm ^2.
To produce a sheet composed of a multilayer substrate.
The firing atmosphere of the ceramic green sheet varies depending on the type of the conductor. In the case of metals such as copper, nickel, tungsten, and molybdenum, the binder is decomposed and evaporated in an inert atmosphere containing water vapor. Next, it can be fired in an atmosphere containing oxygen in the range of 3 to 100 ppm and the balance being controlled by a neutral gas such as nitrogen or argon or steam.

In particular, the firing is preferably performed by using a temperature of 300 to 500 ° C. as a temperature for evaporating the organic binder, maintaining the binder for 30 minutes to several hours to decompose and evaporate the binder. In particular, the sintering temperature in the case of a ceramic multilayer substrate for low-temperature firing is preferably 800 to 1000 ° C. Thus, a fired ceramic multilayer substrate is obtained. The amount of carbon remaining in the multilayer substrate after firing the ceramic green sheet should be 250 ppm or less. Otherwise, the strength of the substrate after firing decreases, the porosity increases, the dielectric constant increases, and the dielectric loss (tan) increases.
This causes problems such as an increase in δ) or a decrease in insulation resistance, which makes it impossible to use the multilayer substrate. The amount of residual carbon is 1
It is preferably at most 00 ppm, more preferably at most 50 ppm.

In the present invention, when the green sheets are laminated to form a multilayer, the number is typically 4 to 50, but the preferred number is 5 to 15. Within this range, the binder can be decomposed and evaporated in a short time, and the residual carbon content is 50 p.
pm or less. Although the decomposition mechanism of the methacrylate-based copolymer of the present invention is not clear, the methacrylate-based copolymer has no hydrogen at the α-position of the methylene group skeleton of the methacrylate unit. It is expected that this monomer unit will be gasified and scattered to cause the decomposition of the methacrylate copolymer.

When the methacrylate copolymer binder of the present invention is used, the decomposition of the binder starts to occur at a low temperature of about 300 ° C., and almost completes at a temperature of 500 ° C. Therefore, the green sheet using the glass-ceramic composition is used. In some cases, it is advantageous because the binder decomposes and evaporates at a temperature lower than 600 ° C., at which sintering of the glass begins.

[0042]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples. However, the present invention is not limited to the following examples, and may be modified and implemented in accordance with the spirit of the specification. All aspects are included in the present invention.

[0043]

[Reference example] In the following reference examples, the concentration and composition are all% by weight.
Expressed by The molecular weight was measured as follows. Measuring apparatus: Gel permeation chromatography "M-410" manufactured by WATERS Detector: Differential refractometer Column used: Ultra Styragel gel (7.8 mmφ × 300 mmL) manufactured by WATERS × 4 Standard substance: polystyrene Measurement conditions: Flow rate 1cc / min (THF) Temperature 40 ° C

<Synthesis of Binder> Reference Example 1 A separable flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a monomer dropping funnel and a polymerization initiator dropping funnel was charged with 80 parts by weight of toluene as a solvent. To replace the atmosphere in the flask with nitrogen. In addition, isobutyl methacrylate 90 is added to the monomer dropping funnel.
100 parts by weight of a monomer mixture consisting of 9 parts by weight of n-butyl methacrylate, 1 part by weight of methacrylic acid,
A solution prepared by dissolving 1.8 parts by weight of azobisisobutyronitrile in 30 parts by weight of toluene is charged into the polymerization initiator dropping funnel. Then, the temperature of the flask was raised to 60 ° C., and the monomer and the polymerization initiator were added dropwise over 2 hours while stirring at the same temperature. After continuing stirring at the same temperature for another 2 hours, the internal temperature was raised to 80 ° C. After further heating and stirring for 2 hours, the mixture was cooled and cooled to obtain a methacrylate copolymer (I). The molecular weight distribution of the obtained copolymer (I) was measured by the above-described method, and the number average molecular weight was determined, and the glass transition temperature (T
g) and acid value were determined, and a predetermined amount of the copolymer (I) was placed in a platinum crucible, heated to 600 ° C. in a nitrogen stream, and the amount of residual carbide was measured when the temperature was maintained at the same temperature for 2 hours.
As a result, it was found that the content was 91
%, Molecular weight of 1,000 to 150,000 / 150,000 to 1,000,000 (weight ratio) was 3/1, number average molecular weight was 20,000, Tg was 46 ° C., and residual carbon amount was 70 ppm.

REFERENCE EXAMPLE 2 A monomer was composed of 40 parts by weight of isobutyl methacrylate and n-
A methacrylate copolymer (V) was obtained in the same manner as in Reference Example 1, except that the composition was composed of 40 parts by weight of butyl methacrylate, 17.5 parts by weight of 2-ethylhexyl methacrylate, and 2.5 parts by weight of methacrylic acid. As a result of measurement in the same manner as in Reference Example 1, the content was 94% with a molecular weight of 1,000 to 1,000,000, the molecular weight was 1,000 to 150,000 / 150,000 to 1,000,000 (weight ratio) was 5/1, and the number average molecular weight was 45,000. Tg27
° C and the amount of residual carbide was 90 ppm.

Reference Examples 3 to 8 Hereinafter, methacrylate copolymers (II) to
(IV) and (VI) to (VIII) were obtained. All monomer composition concentrations are expressed in weight percent. A. Binder The following methacrylate copolymer was used as a binder. Methacrylate copolymer (I) Methacrylate component; isobutyl methacrylate 90% n-butyl methacrylate 9% Vinyl polymer component; methacrylic acid 1% Methacrylate copolymer (II) Methacrylate component; isobutyl methacrylate 81% n-butyl methacrylate 9% 2-hydroxyethyl methacrylate 9% vinyl polymer component; methacrylic acid 1% methacrylate-based copolymer (III) methacrylate component; isobutyl methacrylate 81% n-butyl methacrylate 9% 2-hydroxypropyl methacrylate 9% vinyl polymer component; methacrylic acid 1 % Methacrylate-based copolymer (IV) methacrylate component: isobutyl methacrylate 81% n-butyl methacrylate 9% cyclohexyl methacrylate 9% vinyl polymer component; methacrylic acid 1% methacrylate copolymer (V) methacrylate component; isobutyl methacrylate 40% n-butyl methacrylate 40% 2-ethylhexyl methacrylate 17.5% vinyl polymer component; methacrylic acid 2.5% methacrylate Methacrylate component; isobutyl methacrylate 40% n-butyl methacrylate 40% 2-hydroxyethyl methacrylate 17.5% vinyl polymer component; methacrylic acid 2.5% methacrylate copolymer (VII) methacrylate component; Isobutyl methacrylate 40% n-butyl methacrylate 40% 2-hydroxypropyl methacrylate 17.5% vinyl polymer component; methacrylic acid 2.5% methacrylate copolymer ( III) methacrylate component; isobutyl methacrylate 40% 40% n-butyl methacrylate polymer component; methacrylate 2.5 alpha-methylstyrene 17.5%

B. Solvent Mixed solvent of toluene and methyl ethyl ketone Plasticizer dioctyl phthalate E. Ceramic component Alumina powder Average particle diameter 0.8 μm Cordierite powder Average particle diameter 1.0 μm In glass-ceramic powder, 50% alumina (inorganic filler) powder, 50% glass powder, glass composition: SiO ₂ ; 60, CaO; , Al ₂ O ₃ ; 1
3, MgO; 5, B ₂ O ₃ ; 4, TiO ₂ ;
The glass powder was finely pulverized with an attritor in advance, and a powder having an average particle size of 2.2 μm and a specific surface area of 5.0 m ² / g was used. In the glass-ceramic powder, 50% of ceramic (inorganic filler) powder and 25% of mullite powder are used.
%, 5% spinel and 20% silica. Glass powder is 50%, glass composition is SiO ₂ ; 54, CaO; 2
0, Al ₂ O ₃ ; 13, MgO; 2, B ₂ O ₃ ; 8, T
iO ₂ ; The glass powder was finely pulverized with an attritor in advance, and the average particle size of the powder was 1.5 μm and the specific surface area was 5.2.
m ² / g was used.

[0048]

【Example】

Examples 1 to 12 <Production of Green Sheet> Preparation of Slurry 15% of the above methacrylate-based copolymer (I) to (VIII) as a binder in 85% of the above ceramic powder, and toluene / methyl ethyl ketone (1/1) as a dispersion medium with respect to the sum of these ceramic powder and the binder. 1) 40% of a mixed solvent and dioctyl phthalate as a plasticizer were mixed with an attritor to form a slurry.
Table 1 shows the prepared compositions. B. Preparation of Green Sheet Molding was performed by a doctor blade method. Table 1 shows the film thicknesses of the obtained green sheets (A to L). <Manufacture of multilayer substrate> Printing and Laminating The obtained green sheets (A to L) were punch-pressed with a mold to form 2,000 holes having a via hole diameter of 200 μm. And, for B, C, E and F by the screen printing method, a copper thick film paste (viscosity of 10,000 to 20,000 cp),
For A, D, and G to L, a thick film paste of tungsten (viscosity of 10,000 to 20,000 cp) is embedded to form a conductor for interlayer connection of wiring. Also, a predetermined circuit pattern is printed on the surface of the green sheet using a film thickness paste having the same metal composition as described above, but having a lower viscosity (5,000 to 15,000 cp). Six green sheets printed with copper or tungsten are stacked using guide holes, and 120
Thermocompression bonding was performed at 150 ° C. at a second pressure of 150 kg / cm ² to produce a multilayer ceramic green sheet composed of six layers. D. Debinding The resulting multilayer ceramic green sheet composed of six layers was heated to 550 ° C in a nitrogen stream containing 3 to 5 ppm of oxygen at 300 ° C / hour, and kept at the same temperature for 2 hours to remove binder. . E. FIG. Sintering Debinding green sheets A, D, GL are 16
The green sheets B and E were held at 1000 ° C. at 00 ° C., and the green sheets C and F were held at 900 ° C. for 0.5 hour and sintered, respectively, to obtain a ceramic multilayer substrate. Green sheets without printed circuit patterns were similarly laminated, debindered, and sintered to obtain sintered substrates. The characteristics of the substrates were shown in Table 1.

Examples 13 and 14 The cordierite powder and the glass-ceramic powder of the above-mentioned ceramic powders, and the methacrylate copolymer (I) as a binder were used.
A green sheet was produced under the same conditions as in Example 12. As for the conductor, a predetermined circuit was printed by using a thick film paste of a silver-palladium alloy instead of copper unlike the above-described embodiment. The obtained ten green sheets were stacked using guide holes and thermocompression-bonded at 120 ° C. and a pressure of 150 kg / cm ² to obtain a multilayer ceramic green sheet having ten layers. The resulting multilayer ceramic green sheet of 10 layers was heated at a temperature of 500 ° C./hour in the atmosphere in the air to remove the binder, and held at the same temperature for 1 hour to remove the binder. Further, the temperature is raised at the same rate, and 1000 ° C and 900 ° C,
Sintering was performed for 15 minutes to obtain a ceramic multilayer substrate. Green sheets on which no circuit pattern was printed were similarly laminated, escaped from the binder, and sintered to obtain a sintered substrate.

[0050]

[Comparative example]

Comparative Examples 1 to 3 above, and a green sheet was prepared under the same conditions as in the example except that a polymethyl methacrylate resin was used instead of the methacrylate copolymer as the binder, and the binder was removed and sintered. A ceramic substrate was obtained. The produced ceramic multilayer substrate has insufficient residual carbon content due to insufficient binder removal.
0, 2400, and 3100 ppm. In addition, the bending strength and the insulation resistance were each low and could not be used as a multilayer substrate. Table 2 shows the characteristics of the sintered substrate.

Comparative Example 4 A green sheet was prepared under the same conditions as in Examples 13 and 14 except that cordierite powder among the above ceramic powders and polymethyl methacrylate resin were used as the binder instead of the methacrylate copolymer. did. A predetermined circuit was prepared by a screen printing method using a silver-palladium alloy thick film paste. The obtained 10 green sheets are stacked using guide holes, and are stacked at 120 ° C. and 150 ° C.
Thermocompression bonding was performed at a pressure of kg / cm ² to obtain a multilayer ceramic green sheet including 10 layers. The resulting 10-layer ceramic green sheet was heated at a temperature of 500 ° C./hour in the air to remove the binder, and kept at the same temperature for 1 hour.
Sintering was performed at 00 ° C. for 15 minutes to obtain a ceramic multilayer substrate.
Since the produced ceramics substrate has insufficient binder removal, the residual carbon content is 300 ppm, especially 1000 pp inside.
m.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

The ceramic green sheet of the present invention is constituted as described above, and has excellent strength and handleability, as well as debinding in an oxidizing atmosphere,
Even when heated in a non-oxidizing atmosphere, the binder easily decomposes and scatters without carbonization.
In addition, the ceramic sheet after sintering does not have any warp or bend in appearance, does not have a black-gray appearance in which carbide remains, has a residual carbon content of 250 ppm or less, and has a volume resistivity of 10 ¹³ Ωcm. As described above, it has a sufficient insulating property.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akiko Yoshimura 1-1-1, Sonoyama, Otsu-shi, Shiga Toray Co., Ltd. Shiga Plant (72) Inventor Shigemi Osaka 992, Nishioki, Akihama-ku, Abashi-ku, Himeji-shi, Hyogo Nippon Shokubai Co., Ltd. (72) Inventor Kazuo Hata 992, Nishioki, Okihama-shi, Abashi-ku, Himeji, Hyogo Japan 1 Nippon Shokubai Co., Ltd. Catalyst Research Laboratory (56) References JP-A-5-213663 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/622-35/636

Claims (4)

(57) [Claims] (1) a particle diameter of 0.05 to 4 μm and a specific surface area of
A methacrylate unit selected from the group consisting of a ceramic powder of 5 to ²⁰ m ² / g, butyl methacrylate, a methacrylate having an alkyl side chain at the β-position and having 8 or more carbon atoms, a methacrylate having a hydroxyl group and a methacrylate having a cycloalkyl group has a weight of 80 wt. % Of the butyl methacrylate unit and 50% by weight or more of a methacrylate-based copolymer. 2. The ceramic material according to claim 1, wherein the methacrylate-based copolymer is a methacrylate-based copolymer containing a monomer unit selected from unsaturated carboxylic acids, acrylates and styrenes.
Green sheet. 3. The ceramic powder contains at least one selected from the group consisting of alumina, zirconia, magnesia, beryllia, mullite, cordierite, spinel, forsterite, anorthite, cellian, clinoenstatite and silica. 3. The ceramic green sheet according to 1 or 2. 4. The ceramic powder is expressed in terms of oxide as SiO ₂ 30 to 70% by weight Al ₂ O ₃ 6 to 25% by weight CaO 5 to 25% by weight MgO 1 to 10% by weight B ₂ O _{3 3 to} 50% by weight in the composition range of TiO ₂ 1 to 15% by weight, and 40 to 60% by weight glass composition powders total becomes 95 wt% or more of alumina, zirconia, magnesia, beryllia, mullite, cordierite, forsterite, spinel, anorthite , At least one inorganic filler powder selected from the group consisting of Celsian, clinoenstatite and silica, 60 to 40% by weight
4. A raw material mixture comprising:
The ceramic green sheet according to any one of the above.