JP2000277915A - Manufacture of wiring substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a wiring substrate that can form at higher density a through-hole conductive layer and assures conductivity of wiring conductor layer having high mechanical strength of insulation base material. SOLUTION: A plurality of sheets of a photo-curing ceramic sheet 1a, having a through-hole 3 are formed, by irradiating the predetermined position of a photosensitive ceramic green sheet 1 with a light beam, a wiring conductive layer 4a is formed to at least one photo-curing ceramic sheet 1a, while the power supply conductive layer or grounding conductive layer 6 and auxiliary conductive layer 7 are formed to at least the other photo-curing ceramic sheet 1a, and thereafter these sheets are laminated in the vertical direction and are then baked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wiring board on which electronic components such as a semiconductor element, a capacitor, and a resistor are mounted.

[0002]

2. Description of the Related Art Conventionally, a wiring board on which electronic components such as a semiconductor element, a capacitance element and a resistor are mounted has a high melting point metal such as tungsten, molybdenum or the like on and inside an insulating substrate made of an aluminum oxide sintered body. It has a structure in which a wiring conductor layer, a through-hole conductor layer, a power supply conductor layer, and a ground conductor layer made of materials are formed, and electronic components such as semiconductor elements, capacitance elements, and resistors are mounted on the surface of the insulating base. The electrodes of each electronic component are electrically connected to a wiring conductor layer or the like.

[0003] Such a wiring board is generally manufactured by employing a ceramic laminating technique and a thick film forming technique such as screen printing, and specifically manufactured by the following method.

[0004] (1) First, an organic solvent and a solvent are added to a ceramic raw material powder composed of aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), magnesium oxide (MgO), calcium oxide (CaO) and the like. The mixture is mixed to form a slurry, which is then formed into a sheet by a well-known doctor blade method, calender roll method, or the like to obtain a plurality of ceramic green sheets (ceramic green sheets). Then, a metal punching pin is pressed from the upper surface side to the lower surface side of each ceramic green sheet to form a through hole penetrating in a thickness direction at a predetermined position of each ceramic green sheet.

(2) Next, a conductive paste obtained by adding an organic solvent and a solvent to a tungsten or molybdenum powder is mixed into at least one surface of the ceramic green sheet and in the through hole into a predetermined pattern by a screen printing method. Print and apply.

(3) Next, a conductive paste to be a power supply conductor layer or a ground conductor layer is printed and applied on almost the entire surface of at least one of the ceramic green sheets by a screen printing method.

When the conductive paste for forming the power supply conductor layer or the ground conductor layer is printed and applied to the outer peripheral edge of the ceramic green sheet, when a plurality of ceramic green sheets are vertically stacked in a later step, the upper and lower ceramic green sheets are stacked. Since the adhesion of the green sheet becomes weak, the ceramic green sheet is usually printed and applied except for an area of at least 0.1 mm from the outer edge.

(4) Finally, the ceramic green sheets on which the conductive paste is applied by printing are stacked one above the other with the surface on which the conductive paste serving as the power supply conductor layer or the ground conductor layer is printed interposed therebetween, and a reducing atmosphere is provided. Medium, about 1
By firing at a temperature of 600 ° C. to vaporize and remove the organic solvent and the solvent, and sintering and integrating the ceramic green sheet and the conductive paste, a predetermined pattern of wiring conductor layers and through-hole conductors are formed inside and on the surface of the insulating base. The wiring board having the layers, the power supply conductor layer and the ground conductor layer is completed.

However, in this conventional wiring board, through holes for forming through-hole conductor layers are formed by pressing metal punching pins from the upper surface to the lower surface of the ceramic green sheet. The diameter of the punched pin cannot be less than 80 μm due to the mechanical strength. As a result, the diameter of the through-hole formed by using the punched pin and the diameter of the through-hole conductor layer formed in the through-hole are reduced. 80
μm or more, and the through-hole conductor layer cannot be formed with high density.

In order to solve the above-mentioned drawbacks, the ceramic green sheet is made photosensitive by irradiating a predetermined area with light to cure the light and to remove the uncured area by development. Has been proposed to form a fine through hole of about 60 μm (Japanese Patent Laid-Open No. 6-30581).
No. 4).

[0011]

However, when a wiring board is manufactured using a photosensitive ceramic green sheet, the photocured ceramic sheet contains an organic resin having a mesh-like structure inside and on the surface. The mesh-shaped organic resin is formed by vertically laminating a photo-cured ceramic sheet on which a conductive paste to be a wiring conductor layer, a through-hole conductor layer, a power supply conductor layer, and a ground conductor layer is printed and applied to prevent movement of organic substances. When baked, the organic solvent vaporized and discharged from the conductive paste, the gaseous organic matter such as the solvent cannot be efficiently moved and released to the outside, and stays between the upper and lower light-cured ceramic sheets, and as a result, Peeling occurs between the upper and lower light-cured ceramic sheets, which causes blisters and the like on the insulating substrate obtained after firing, resulting in poor appearance and poor insulation substrate quality. And lead to decrease in 械的 strength, induced the disadvantage to generate disconnection or the like at the same time the insulating substrate in the wiring conductor layer and through-hole conductor layer.

In particular, the conductive paste serving as the power supply conductor layer and the grounding conductor layer is printed and applied over substantially the entire surface of the ceramic green sheet, and is vaporized and discharged from the conductive paste serving as the power supply conductor layer and the grounding conductor layer. Since the amount of gaseous organic matter is large, occurrence of blisters and the like becomes remarkable in portions of the insulating base located above and below the ceramic green sheet on which the conductive paste to be the power supply conductor layer and the ground conductor layer is printed and applied. Had disadvantages.

The present invention has been devised in view of the above-mentioned drawbacks, and has as its object to form a through-hole conductor layer at a high density and to have a high mechanical strength of an insulating base.
It is an object of the present invention to provide a method of manufacturing a wiring board in which conduction of a wiring conductor layer or the like is ensured.

[0014]

According to the present invention, there is provided a method for manufacturing a wiring board, comprising: (1) a plurality of photosensitive ceramic green sheets in which ceramic powder is dispersed in a photosensitive resin composition;
(2) forming a conductive paste obtained by adding an organic solvent to a metal powder having an average particle diameter of 5 μm or less and an organic solvent added to a metal powder having an average particle diameter of 6 to 20 μm; A step of irradiating a predetermined area of the ceramic green sheet with light and photo-curing and developing the photosensitive resin composition in the predetermined area to form a plurality of photo-cured ceramic sheets having through holes penetrating in the thickness direction; 3) using the conductive paste to form a wiring conductor layer and a through-hole conductor layer in a predetermined pattern on at least one surface and in the through-hole of the photocurable ceramic sheet; and (4) removing the conductive paste. Using at least one of said light-cured ceramic sheets
A power supply conductor layer or a grounding conductor layer is formed on all surfaces except the width of 1 mm or more from the outer peripheral edge on one surface,
1 mm from the outer peripheral edge using the auxiliary conductive paste
Forming a plurality of auxiliary conductor layers radially extending toward the outer peripheral end in the area having the above width; and (5) the wiring conductor layer, the through-hole conductor layer, the power supply conductor layer or the grounding conductor. A plurality of photo-cured ceramic sheets each having a layer and an auxiliary conductor layer are laminated one above the other with a power supply conductor layer or a grounding conductor layer and an auxiliary conductor layer interposed therebetween and fired to form an insulating base made of ceramic. Forming a wiring conductor layer, a through-hole conductor layer, and a power supply conductor layer or a ground conductor layer on the inside and on the surface.

Further, in the method of manufacturing a wiring board according to the present invention, the auxiliary conductor layer has a line width of 0.1 mm to 1 mm and an adjacent distance of 0.1 mm to 1 mm.

According to the method for manufacturing a wiring board of the present invention, a ceramic green sheet for forming an insulating base is provided by:
Since the photosensitive resin composition was made photosensitive by adding and dispersing the ceramic powder, a predetermined area of the ceramic green sheet was irradiated with light, and the photosensitive resin composition in a predetermined area was light-cured and the uncured area was cured. By removing by developing the photosensitive resin composition, the through-hole can be formed very easily and to a small diameter of 60 μm or less, whereby the through-hole conductor layer formed in the through-hole also has the diameter. It is possible to form the through-hole conductor layer at a high density as small as 60 μm or less.

Further, according to the method of manufacturing a wiring board of the present invention, the average particle size of the metal powder of the conductive paste for forming the wiring conductor layer, the through-hole conductor layer, the power supply conductor layer or the ground conductor layer is 5 μm or less. The electric resistance of the wiring conductor layer, the through-hole conductor layer, and the like obtained from the above becomes extremely small.

Further, according to the method of manufacturing a wiring board of the present invention, at least a region having a width of 1 mm or more from the outer peripheral edge of the photocurable ceramic sheet on which the conductive paste to be the power supply conductor layer and the ground conductor layer is printed and applied is provided. After forming a plurality of auxiliary conductor layers that spread radially toward the outer peripheral edge, after photo-curing, the conductive paste that will be the wiring conductor layer, through-hole conductor layer, power supply conductor layer, and ground conductor layer is printed and applied. When the ceramic sheets are laminated one above the other and fired, there is an organic resin having a mesh-like structure that prevents the movement of organic substances inside and on the surface of the photo-cured ceramic sheet, and the conductive material becomes a power supply conductor layer and a ground conductor layer. Even if a large amount of gaseous organic matter is discharged from the paste, such a large amount of gaseous organic matter is satisfactorily released to the outside via the auxiliary conductor layer. There is no stagnation between the upper and lower light-cured ceramic sheets, and as a result, the adhesion between the upper and lower light-cured ceramic sheets is improved, and the occurrence of blisters and the like on the insulating substrate obtained after firing is effectively prevented. As a result, it is possible to provide a wiring board in which the mechanical strength of the insulating base is increased and the conduction of the wiring conductive layer and the through-hole conductive layer inside the insulating base is ensured without causing appearance defects.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method of manufacturing a wiring board according to the present invention will be described with reference to FIGS. 1 (a) to 1 (f) and an embodiment shown in FIG.

First, as shown in FIG. 1A, a plurality of photosensitive ceramic green sheets 1 are formed.

The photosensitive ceramic green sheet 1 is prepared by adding a photosensitive resin composition comprising a photoreactive compound, a photopolymerization initiator and a photopolymerization accelerator, and, if necessary, an organic binder, an ultraviolet absorber, It is formed by mixing an inhibitor, a non-photosensitive polymer, etc. to form a photosensitive slurry, and forming the photosensitive slurry into a sheet by a doctor blade method, a calendar roll method, or the like.

As the ceramic powder used for forming the photosensitive ceramic green sheet 1, glass ceramic powder, alumina powder, mullite powder, aluminum nitride powder, crystallized glass powder and the like are used. If used,
10.8% by weight of magnesium oxide (MgO), 28.0% by weight of aluminum oxide (Al ₂ O ₃ ), silicon oxide (S
glass component 8 consisting of 43.8% by weight of iO ₂ ), 7.1% by weight of zinc oxide (ZnO) and the balance being boron (B ₂ O ₃ )
A material in which silicon oxide (SiO ₂ ) powder is 20% by weight with respect to 0% by weight is preferably used.

The photoreactive compound used for forming the photosensitive ceramic green sheet 1 is an acrylic or methacrylic monomer or oligomer having a photoreactive carbon-carbon unsaturated bond. By making the photosensitive ceramic green sheet 1 insoluble in a developing solution to be described later, the photosensitive ceramic green sheet 1 has an effect of forming a through hole by a photolithography method. For example, 1,6 hexanediol diacrylate, tripropylene glycol diacrylate , Trimethylolpropane triacrylate, 2- (2-ethoxyethoxy)
Ethyl acrylate, stearyl acrylate, tetrahydrfurfuryl acrylate, lauryl acrylate, 2-phenoxyethyl acrylate, isodecyl acrylate, isooctyl acrylate, tridecyl acrylate, caprolactone acrylate, ethoxylated nonylphenyl acrylate, zinc diacrylate, 1,3 butane Diol diacrylate, 1.4 butanediol diacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate,
Tetraethylene glycol diacrylate, triethylene glycol diacrylate, ethoxylated bisphenol A diacrylate, propicylated neopentyl glycol acrylate, tris (2-hydroxyethyl) isocyanurate triacrylate, ethoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate Acrylate, propoxylated trimethylolpropane triacrylate, proxied glyceryl triacrylate, ditrimethylolpropane tetraacrylate,
Dipentaeristol hydroxypentaacrylate,
There are ethoxylated pentaeristol tetraacrylate, pentaacrylate ester, and those in which the above acrylate is replaced with methacrylate, and one or a mixture of two or more of these can be used.

The photopolymerization initiator used for forming the photosensitive ceramic green sheet 1 generates radicals by light energy such as ultraviolet rays, and has a function of initiating a photocuring reaction of the photoreactive compound by the radicals. For example, benzophenone, methyl o-benzoylbenzoate, 4,4-bis (dimethylamine) benzophenone, 4,4bis (diethylamino) benzophenone,
4,4-dichlorobenzophenone, 4-benzoyl-4
-Methyldiphenyl ketone, dibenzyl ketone, fluorenone, 2,2-diethoxyacetophenone, 2,2 dimethoxy-2-phenyl-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, p
-T-butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, benzyl, benzyldimethylketanol,
Benzyl-methoxyethyl acetal, benzoin, benzoin methyl ether, benzoin butyl ether,
Anthraquinone, 2-t-butylanthraquinone, 2-
Amylanthraquinone, β-chloroanthraquinone, anthrone, benzantrone, 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-azobisisovitylonitrile, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-benzyl-2dimethylamino-1- (4-morpholinophenyl)- Butanone-1,2-4 diethylthioxanthone, 2,2 dimethoxy-1,2-diphenylethane-1
-One, diphenyl disulfide, benzothiazole disulfide, triphenylphorphine, camphorquinone, carbon tetrabromide, tribromophenyl sulfone, benzoin peroxide, and photoreducing dyes such as eosin, methylene blue and ascorbic acid, triethanol Examples thereof include a combination of reducing agents such as amines, and one or more of the above compounds can be used.

The photopolymerization accelerator used when forming the photosensitive ceramic green sheet 1 has an effect of accelerating the photocuring reaction of the photoreactive compound.
There are dimethylaminoisoamylbenzoate, 4-dimethylaminoethylbenzoate and the like, and one or more of these can be used.

The organic binder used for forming the photosensitive ceramic green sheet 1 has a function of binding to ceramic powder and dispersing the same in an organic solvent, and comprises isobutyl methacrylate (i-BMA) and acrylic acid. Alternatively, a copolymer with methacrylic acid can be used.

The ultraviolet absorber used for forming the photosensitive ceramic green sheet 1 is such that ultraviolet rays irradiated to cause a photocuring reaction are scattered by ceramic powder inside the photosensitive ceramic green sheet 1. One or two types of benzotriazole, benzophenone, and binderdamine compounds, which prevent photo-curing to unnecessary parts and reduce, for example, the deterioration of through hole formation accuracy. The above can be used.

The thermal polymerization inhibitor used to form the photosensitive ceramic green sheet 1 has a property of absorbing free radicals, and the photosensitive resin is exposed to weak thermal energy applied to the photosensitive ceramic green sheet 1 from the environment. A small amount of free radicals are generated from a part of the composition, and the free radicals partially polymerize the photoreactive compound, making it difficult to dissolve in a developer and making it difficult to form through holes by photolithography. Quinone, hydroquinone, methylhydroquinone, nitrosoaluminum salt, hydroquinone monomethyl ether, 2,6-t-butyl-p
-Cresol and 2,3-dimethyl-6-t-butylphenol, and one or more of these can be used.

The non-photosensitive polymer used in forming the photosensitive ceramic green sheet 1 complements the action of the photoreactive compound and assists in forming the ceramic powder into a sheet. Acrylic acid ester copolymer, methacrylic acid ester copolymer, resin such as acrylic acid ester-methacrylic acid ester copolymer, and a resin obtained by substituting a resin obtained by substituting a carboxylic acid, for example, methyl methacrylate, methacrylic acid Ethyl, n-butyl methacrylate, isobutyl methacrylate,
T-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate,
Stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, isobornyl methacrylate,
Glycidyl methacrylate, tetrahydrofurfuryl methacrylate, allyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, ethylene glycol dimethacrylate, triethylene dimethacrylate Glycol, dimethacrylic acid 1,3
Butylene glycol, 1,6-hexanediol dimethacrylate, polypropylene glycol dimethacrylate, trimethylolpropane trimethacrylate, succinic acid 2-
Methacryloyloxyethyl, 2-methacryloyloxyethyl maleate, 2-methacryloyloxyethyl phthalate, 2-methacryloyloxyethyl hexahydrophthalate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, trifluoroethyl methacrylate, heptamethacrylate Copolymers of decafluodecyl and those obtained by replacing these organic acids with acrylic acid are cited, and the carboxylic acids to be substituted are acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acid and these. Acid anhydrides are used.

Next, as shown in FIG. 1B, a photomask pattern 2 is formed on the upper surface of the photosensitive ceramic green sheet 1.

The photomask pattern 2 is formed on the upper surface of the photosensitive ceramic green sheet 1 by employing photolithography technology capable of fine processing, and its shape corresponds to the shape of the through hole to be formed. Has become.

Next, the photosensitive ceramic green sheet 1 on which the photomask pattern 2 is attached on the upper surface is, for example, about 300 mm from the photomask pattern 2 side.
Irradiation with ultraviolet light having an intensity of mj / cm ² is performed to irradiate an ultraviolet ray to a portion where the photomask pattern 2 is not present. A photo-cured ceramic in which a through-hole 3 is formed at a predetermined position as shown in FIG. 1C by removing the uncovered area covered with the mask pattern 2, that is, the uncured area by development, as shown in FIG. The sheet 1a is obtained.

When the photosensitive ceramic green sheet 1 is irradiated with light such as ultraviolet rays to form a photo-cured ceramic sheet 1a having through holes 3, a photolithography technique capable of finely processing the photomask pattern 2 is employed. Therefore, the diameter of the through hole 3 can be a small diameter of 60 μm or less,
At the same time, the formation of the through hole 3 can be performed by an extremely simple operation of irradiating light such as ultraviolet rays through a photomask pattern and removing the uncured region by development.

As a developer for removing the uncured photosensitive resin composition for forming the through holes 3, for example, an organic alkali solution such as triethanolamine is used. A solution consisting of an organic alkali of the formula (1) removes hydrogen ions from the carboxyl group of the organic binder in the uncured photosensitive ceramic green sheet 1 and ionizes this carboxyl group to make it water-soluble and dissolves in a developing solution or washing water. Let it.

When the photocurable ceramic sheet 1a having the through holes 3 is formed, the average particle size of the ceramic powder contained in the photosensitive ceramic green sheet 1 is set to about 2 μm (D50 by the microtrack method). In addition, UV light can be transmitted well and photocuring can be performed uniformly. Accordingly, the ceramic powder of the photosensitive ceramic green sheet 1 has an average particle size of about 2 μm.
It is preferable to keep

When the photoreactive compound contained in the photosensitive ceramic green sheet 1 is added in an amount of 5 to 12 parts by weight with respect to 100 parts by weight of the ceramic powder, the through holes 3 are formed in the photosensitive ceramic green sheet. It is easy to form the sheet 1 uniformly in the thickness direction.
Therefore, the amount of the photoreactive compound contained in the photosensitive ceramic green sheet 1 is preferably set to 5 to 12 parts by weight based on 100 parts by weight of the ceramic powder.

When the photopolymerization initiator contained in the photosensitive ceramic green sheet 1 is added in an amount of 0.5 to 5 parts by weight with respect to 100 parts by weight of the ceramic powder, the photocuring reaction is not sensitive. Can be uniformly started in the conductive ceramic green sheet 1. Therefore, the amount of the photopolymerization initiator contained in the photosensitive ceramic green sheet 1 is preferably set to 0.5 to 5 parts by weight based on 100 parts by weight of the ceramic powder.

If the photopolymerization accelerator contained in the photosensitive ceramic green sheet 1 is added in an amount of 2 to 5 parts by weight with respect to 100 parts by weight of the ceramic powder, the content of the photopolymerization accelerator in the photosensitive ceramic green sheet 1 is reduced. Photocuring reaction can be promoted uniformly. Therefore, it is preferable that the amount of the photopolymerization accelerator contained in the photosensitive ceramic green sheet 1 is 2 to 5 parts by weight based on 100 parts by weight of the ceramic powder.

When the amount of the organic binder contained in the photosensitive ceramic green sheet 1 is set to 10 to 25 parts by weight with respect to 100 parts by weight of the ceramic powder, the ceramic powder is uniformly dispersed in the organic solvent. It is easy to perform, and does not easily decompose during the subsequent firing and remains in the insulating substrate made of ceramic. Therefore, the organic binder contained in the photosensitive ceramic green sheet 1 is preferably added in an amount of 10 to 25 parts by weight based on 100 parts by weight of the ceramic powder.

When the ultraviolet absorber contained in the photosensitive ceramic green sheet 1 is added in an amount of 0.01 to 2 parts by weight with respect to 100 parts by weight of the ceramic powder, the ultraviolet absorber is not excessively absorbed. It absorbs effectively and can suppress photocuring of unnecessary parts. Therefore, the amount of the ultraviolet absorber contained in the photosensitive ceramic green sheet 1 is preferably set to 0.01 to 2 parts by weight based on 100 parts by weight of the ceramic powder.

When the amount of the thermal polymerization inhibitor contained in the photosensitive ceramic green sheet 1 is in the range of 0.1 to 5 parts by weight based on 100 parts by weight of the ceramic powder, a small amount of free radicals generated by heat energy can be obtained. Can be effectively absorbed, and the through-hole 3 can be accurately formed at any position without hindering the photocuring reaction. Therefore, it is preferable that the amount of the thermal polymerization inhibitor contained in the photosensitive ceramic green sheet 1 is in the range of 0.1 to 5 parts by weight based on 100 parts by weight of the ceramic powder.

When the thickness of the photosensitive ceramic green sheet 1 is less than 10 μm, the mechanical strength is weak, the sheet is easily broken, and handling becomes difficult.
If m is exceeded, it becomes difficult for light such as ultraviolet rays irradiated for photocuring to reach the lower surface side of the photosensitive ceramic green sheet 1, and the resolution of the formation of the through hole 3 may be reduced. Therefore, it is preferable that the photosensitive ceramic green sheet 1 has a thickness in the range of 10 to 60 μm. Next, as shown in FIG. 1D, at least one of the photocurable ceramic sheets 1 a having the through holes 3 is provided. One surface and the inside of the through-hole 3 are filled with a conductive paste to a predetermined thickness by a screen printing method, a spin coating method or the like to form the wiring conductor layer 4 and the through-hole conductor layer 5.

The conductive paste is made of a metal powder having an average particle size of 5 μm or less, such as gold, silver, platinum, palladium, copper, nickel, molybdenum, tungsten, or an alloy of these or an alloy containing these as a main component. It is formed by adding and kneading an organic solvent or a solvent such as an ester solvent such as dibutyl phthalate (DBP), an alcohol solvent such as α-terpineol, or an aromatic solvent such as toluene.

If the average particle size of the metal powder for producing the conductive paste is more than 5 μm, the metal powder cannot be filled at a high density, and is fired to form a wiring conductor layer or a through-hole conductor layer. When formed, the electrical resistance cannot be reduced. Therefore, the metal powder is specified to have an average particle size of 5 μm or less.

Next, as shown in FIG. 1E, the entire surface of at least one surface of the photo-cured ceramic sheet 1a having the through hole 3 except for the region around the through hole 3 and the width of 1 mm or more from the outer peripheral edge. Then, a conductive paste is adhered and filled in the through hole 3 to a predetermined thickness by a screen printing method, a spin coating method, or the like to form a power supply conductor layer or a grounding conductor layer 6 and a through hole conductor layer 5.

Further, an auxiliary conductive paste is applied to a region having a width of 1 mm or more from the outer peripheral edge of the photocurable ceramic sheet 1a on which the power supply or grounding conductor layer 6 and the through-hole conductor layer 5 are formed. A plurality of auxiliary conductor layers 7 are radially applied to the edges by a screen printing method, a spin coating method, or the like, and are spread radially toward the outer peripheral edge as shown in FIG.

The auxiliary conductive paste includes gold, silver, platinum,
Metal powder composed of palladium, copper, nickel, molybdenum, tungsten or alloys of these or alloys containing these as main components and having an average particle size of 6 to 20 μm, ester based on dibutyl phthalate (DBP), α-terpineol It is formed by adding and kneading an organic solvent such as an alcohol-based solvent such as toluene and an aromatic-based solvent such as toluene and kneading.

The auxiliary conductor layer 7 functions as a passage for releasing gaseous organic substances discharged from the power supply conductor layer or the grounding conductor layer 6 during firing, which will be described later.

Finally, a plurality of photo-cured ceramic sheets 1a having the wiring conductor layer 4, the through-hole conductor layer 5, the power supply or grounding conductor layer 6, and the auxiliary conductor layer 7 are separated by a power supply. Layered up and down with the conductive layer for grounding or the conductive layer for grounding 6 and the auxiliary conductive layer 7 interposed therebetween, and fired to cure the photosensitive resin composition in the photocurable ceramic sheet 1a and the organic solvent in the conductive paste. By releasing the solvent to the outside and simultaneously sintering the ceramic powder and the metal powder, as shown in FIG. 1 (f), the wiring conductor layer 4a and the through hole are formed inside and on the surface of the insulating base 1b made of ceramic. A wiring board as a product having the conductor layer 5a, the power supply conductor layer or the ground conductor layer 6a, and the auxiliary conductor layer 7a is completed.

In this case, there is an organic resin having a mesh-like structure in the inside and on the surface of the photocurable ceramic sheet 1a that prevents the movement of organic substances, and the power supply conductor layer or the grounding conductor layer 6 during firing. A large amount of gaseous organic matter is discharged from the substrate, and a large amount of gaseous organic matter discharged from the power supply conductor layer or the grounding conductor layer 6 is satisfactorily discharged to the outside via the auxiliary conductor layer 7. , Does not stay between the upper and lower light-cured ceramic sheets 1a,
As a result, the adhesion between the upper and lower light-cured ceramic sheets 1a is improved, and the occurrence of blisters and the like on the insulating substrate 1b obtained after firing is effectively prevented, and the appearance of the insulating substrate 1b is reduced without causing a poor appearance. Strength of the insulating substrate 1
The conduction of the wiring conductor layer 4a, the through-hole conductor layer 5a, and the like inside b can be ensured.

In particular, the auxiliary conductor layer 7 has a line width of 0.1 mm.
When the thickness is less than 1 mm, it is difficult to efficiently discharge gaseous organic substances discharged from the power supply conductor layer or the grounding conductor layer 6 to the outside during firing. There is a risk that the amount of gaseous organic matter released via the gas will be too large, and the gas pressure at the time of release will cause separation between the upper and lower photo-cured ceramic sheets 1a. Therefore, it is preferable to set the line width of the auxiliary conductor layer 7 to 0.1 mm to 1 mm.

When the distance between adjacent auxiliary conductor layers 7 is reduced to less than 0.1 mm, the gas pressure of the gaseous organic substance discharged through the auxiliary conductor layers 7 becomes smaller. When the layers 7 are joined together, a large pressure is applied, and peeling occurs between the upper and lower photocurable ceramic sheets 1a. If the thickness exceeds 1 mm, gaseous organic substances discharged from the power supply conductor layer or the grounding conductor layer 6 are removed. It is difficult to efficiently release the gas to the outside, and there is a danger that the gaseous organic material stays between the upper and lower photocurable ceramic sheets 1a and peels off between the photocurable ceramic sheets 1a. Therefore, it is preferable that the auxiliary conductor layer 7 has an adjacent space of 0.1 mm to 1 mm.

Further, when the distance between the outer peripheral position of the power supply conductor layer or the grounding conductor layer 6 and the outer peripheral end of the photocurable ceramic sheet 1a is less than 1 mm, the adhesion between the upper and lower photocurable ceramic sheets 1a is reduced. As a result, the gas pressure of the gaseous organic substance discharged through the auxiliary conductor layer causes peeling between the upper and lower photocurable ceramic sheets 1a. Therefore, the distance between the outer peripheral position of the power supply conductor layer or the grounding conductor layer 6 and the outer peripheral end of the photocurable ceramic sheet 1a is specified to be 1 mm or more.

The auxiliary conductor layer 7 has a length of one.
When the length is longer than 0 mm, the metal powder forming the metal powder has a relatively coarse particle diameter of 6 to 20 μm, and when the auxiliary conductor layer 7a is fired, a void portion exists inside. There is a possibility that the plating solution may be trapped when, for example, protective plating is performed on the exposed surface of the wiring conductor layer, causing stains or the like on the insulating substrate. Therefore, it is preferable that the length of the auxiliary conductor layer 7 be 10 mm or less. Accordingly, the outer peripheral position of the power supply conductor layer or the grounding conductor layer 6 and the photocurable ceramic sheet 1
It is also preferable that the distance from the outer peripheral end of a is 10 mm or less.

The wiring substrate thus obtained is the insulating substrate 1
b. Electronic components such as semiconductor elements, capacitance elements, resistors, etc. are mounted on the surface of b.
a, etc., so that each of the electronic components is electrically connected to each other via the wiring conductor layer 4a, etc., and to an external electric circuit.

The present invention is not limited to the above-described embodiment, and various changes can be made without departing from the gist of the present invention.

[0057]

According to the method of manufacturing a wiring board of the present invention,
The ceramic green sheet for forming the insulating substrate was made photosensitive by adding and dispersing ceramic powder to the photosensitive resin composition. By photo-curing the composition and removing the photosensitive resin composition in the uncured area by development, the through-hole can be formed very easily and with a small diameter of 60 μm or less. The through-hole conductor layer formed therein also has a small diameter of 60 μm or less, so that the through-hole conductor layer can be formed at a high density.

According to the method of manufacturing a wiring board of the present invention, the average particle size of the metal powder of the conductive paste for forming the wiring conductor layer, the through-hole conductor layer, the power supply conductor layer or the ground conductor layer is 5 μm or less. The electric resistance of the wiring conductor layer, the through-hole conductor layer, and the like obtained from the above becomes extremely small.

Further, according to the method of manufacturing a wiring board of the present invention, at least a region having a width of 1 mm or more from the outer peripheral edge of the photo-cured ceramic sheet on which the conductive paste to be the power supply conductor layer and the ground conductor layer is printed is applied. After forming a plurality of auxiliary conductor layers that spread radially toward the outer peripheral edge, after photo-curing, the conductive paste that will be the wiring conductor layer, through-hole conductor layer, power supply conductor layer, and ground conductor layer is printed and applied. When the ceramic sheets are laminated one above the other and fired, there is an organic resin having a mesh-like structure that prevents the movement of organic substances inside and on the surface of the photo-cured ceramic sheet, and the conductive material becomes a power supply conductor layer and a ground conductor layer. Even if a large amount of gaseous organic matter is discharged from the paste, such a large amount of gaseous organic matter is satisfactorily released to the outside via the auxiliary conductor layer. There is no stagnation between the upper and lower light-cured ceramic sheets, and as a result, the adhesion between the upper and lower light-cured ceramic sheets is improved, and the occurrence of blisters and the like on the insulating substrate obtained after firing is effectively prevented. As a result, it is possible to provide a wiring board in which the mechanical strength of the insulating base is increased and the conduction of the wiring conductive layer and the through-hole conductive layer inside the insulating base is ensured without causing appearance defects.

[Brief description of the drawings]

FIGS. 1A to 1F are cross-sectional views for explaining respective steps of a method for manufacturing a wiring board according to the present invention.

FIG. 2 is a plan view of FIG.

[Explanation of symbols]

 1... Photosensitive ceramic green sheet 1a... Photo-cured ceramic sheet 1b... Insulating substrate 3... Through hole 4... Wiring conductor layer 4a. Wiring conductor layer 5 ··· Through hole conductor layer 5a ··· Through hole conductor layer 6 ···· Power supply conductor layer or grounding conductor layer 6a ··· Power supply conductor layer or ground conductor layer 7 ... Auxiliary conductor layer 7a ... Auxiliary conductor layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/40 H05K 3/40 K F term (Reference) 5E317 AA24 BB04 BB11 CC22 CC25 GG14 5E338 AA02 AA03 AA18 BB02 BB13 BB25 BB28 BB75 CC01 CC04 CC06 CC09 CD12 EE21 EE22 5E346 AA12 AA15 AA42 AA43 BB01 BB03 BB04 BB15 CC17 CC31 DD34 EE24 EE29 FF18 GG02 GG03 GG06 GG09 HH07 HH11 HH25 HH26

Claims (2)

[Claims] (1) A plurality of photosensitive ceramic green sheets in which ceramic powder is dispersed in a photosensitive resin composition, a conductive paste obtained by adding an organic solvent to metal powder having an average particle diameter of 5 μm or less, A step of preparing an auxiliary conductive paste in which an organic solvent is added to metal powder having a particle size of 6 μm to 20 μm; and (2) irradiating a predetermined area of the photosensitive ceramic green sheet with light to form a predetermined area of the photosensitive resin composition. Photo-curing and developing to form a plurality of photo-curable ceramic sheets having through holes penetrating in the thickness direction; and (3) at least one surface of the photo-curable ceramic sheet using the conductive paste; Forming a wiring conductor layer and a through-hole conductor layer in a predetermined pattern in the through-hole; and (4) using the conductive paste to form To form a conductive layer or grounding conductor layer power on the entire surface except for 1mm or more the width from an outer peripheral end on at least one surface of the cured ceramic sheet, by using the auxiliary conductive paste, 1 from the outer peripheral edge
forming a plurality of auxiliary conductor layers radially extending toward the outer peripheral end in a region having a width of not less than mm, and (5) the wiring conductor layer, the through-hole conductor layer, the power supply conductor layer, or the grounding layer. A plurality of photo-cured ceramic sheets each having a conductor layer and an auxiliary conductor layer are vertically laminated with a power supply conductor layer or a grounding conductor layer and an auxiliary conductor layer interposed therebetween and fired to form an insulating base made of ceramic. Forming a wiring conductor layer, a through-hole conductor layer, a power supply conductor layer or a ground conductor layer inside and on the surface of the wiring board. 2. The method according to claim 1, wherein the auxiliary conductive layer has a line width of 0.1 mm to 1 mm and an adjacent distance of 0.1 mm to 1 mm.