JP2001036206A - Wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board in which through hole conductor layers can be formed at a high density and the occurrence of peeling, swelling, etc., in its insulating substrate can be prevented effectively, and then, a wiring conductor layer, etc., can be conducted surely. SOLUTION: A wiring board is composed of an insulating substrate 1 made of an electric insulating material and having through hole conductor layers of <=60 μm in diameter; and a wiring conductor layer 2 having a two-layer structure of a conductor layer 2a formed in and/or on the substrate 1 and composed of metallic powder having a mean particle diameter of <=5 μm and an auxiliary conductor layer 2b composed of metallic powder having a mean particle diameter of 6-20 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to 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 made of a material and a through-hole conductor layer are formed, and electronic components such as semiconductor elements, capacitance elements, and resistors are mounted on the surface of the insulating base, and the electrodes of each electronic component are connected to the wiring conductor. It is electrically connected to a 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, and then formed into a sheet by a conventionally 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) Finally, the ceramic green sheets on which the conductive paste is applied by printing are laminated one above the other and fired at a temperature of about 1600 ° C. in a reducing atmosphere to evaporate and remove the organic solvent and the solvent. By sintering and integrating the green sheet and the conductive paste, a wiring substrate having a predetermined pattern of wiring conductor layers and through-hole conductor layers inside and on the surface of the insulating base 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 side to the lower surface side 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 harden the light and at the same time 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).

[0009]

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 hinders the movement of organic substances, the upper and lower layers of the photo-cured ceramic sheet on which a conductive paste to be a wiring conductor layer and a through-hole conductor layer is applied by printing,
When baked, gaseous organic substances such as organic solvents and solvents vaporized and discharged from the conductive paste cannot be efficiently moved and released to the outside, and remain between the upper and lower photo-cured ceramic sheets. Separation occurs between the photo-cured ceramic sheets, which causes blisters and the like on the insulating substrate obtained after firing, resulting in poor appearance and a decrease in mechanical strength of the insulating substrate, and at the same time, the wiring conductor layer inside the insulating substrate. And the like that a disconnection or the like occurs in the through-hole conductor layer.

In particular, in recent years, the wiring conductor layer has been significantly complicated in pattern and high in density. In this case, the amount of gaseous organic substances vaporized and discharged from the conductive paste serving as the wiring conductor layer is large, and the pattern is complicated. Since the gas is difficult to be discharged, there is a disadvantage that blisters and the like are remarkably generated in portions of the insulating base located above and below the ceramic green sheet on which the conductive paste to be the wiring conductor layer is printed and applied at a high density. I was

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to form a through-hole conductor layer at a high density and to effectively prevent peeling, blistering, and the like from occurring on an insulating substrate. It is another object of the present invention to provide a wiring board that ensures conduction of a wiring conductor layer and the like, and a method of manufacturing the wiring board.

[0012]

According to the present invention, there is provided a wiring board comprising an insulating base made of an electrically insulating material and having a through-hole conductor layer having a diameter of not more than 60 μm, and an average particle formed on the inside and / or surface of the insulating base. A wiring conductor layer having a two-layer structure of a conductor layer made of metal powder having a diameter of 5 μm or less and an auxiliary conductor layer made of metal powder having an average particle diameter of 6 μm to 20 μm.

Further, the method for manufacturing a wiring board according to the present invention comprises:
(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, and an average particle diameter of 6 μm to Producing an auxiliary conductive paste obtained by adding an organic solvent to 10 μm metal powder;
(2) A plurality of photo-cured ceramic sheets having through holes penetrating in a thickness direction by irradiating light to a predetermined area of the photosensitive ceramic green sheet and photo-curing and developing the photosensitive resin composition in the predetermined area. Forming; (3) forming a conductive layer for through holes in the through holes of the photocurable ceramic sheet using the conductive paste; and (4) using the conductive paste and auxiliary conductive paste. Forming a wiring conductor layer of a predetermined pattern having a two-layer structure of a conductor layer and an auxiliary conductor layer on the surface of the photocurable ceramic sheet; and (5) the wiring conductor layer and the through-hole conductor layer. A plurality of photo-cured ceramic sheets having Forming a wiring conductor layer having a two-layer structure of a conductor layer composed of metal particles having a particle diameter of 5 μm or less, an auxiliary conductor layer composed of metal particles having an average particle diameter of 6 μm to 10 μm, and a through-hole conductor layer. It is a feature.

According to the wiring board of the present invention, the insulating base on which the wiring conductor layer and the through-hole conductor layer are formed is formed by using a photosensitive ceramic green sheet in which ceramic powder is dispersed and mixed in a photosensitive resin, for example. Due to the production, the through holes are extremely reduced by irradiating a predetermined position of the ceramic green sheet with light and photo-curing the photosensitive resin composition in a predetermined area and removing the photosensitive resin composition in an uncured area by development. The diameter of the through-hole conductor layer formed in the through-hole can be easily reduced to a small diameter of 60 μm or less. Can be formed.

Further, according to the wiring board of the present invention, the wiring conductor layer is composed of a conductor layer made of metal particles having an average particle diameter of 5 μm or less and an auxiliary conductor layer made of metal powder having an average particle diameter of 6 μm to 20 μm. Since the layered structure, the conductive paste to be the wiring conductor layer and the through-hole conductor layer is printed and coated at a high density, and the photocured ceramic sheets are stacked one on top of the other, and when baked, the inside of the photocured ceramic sheet and Even if a large amount of gaseous organic matter is discharged from the conductive paste that becomes a high-density wiring conductor layer, even if a large amount of gaseous organic matter is discharged from the surface of the organic resin having a network-like structure that prevents movement of organic matter on the surface, The organic substance is well released to the outside through the auxiliary conductor layer having a coarse average particle diameter of 6 μm to 20 μm of the metal powder to be the auxiliary conductor layer, and stays between the upper and lower photo-cured ceramic sheets. As a result, the adhesion between the upper and lower photo-cured ceramic sheets is improved, and the occurrence of blisters and the like on the insulating substrate obtained after firing is effectively prevented, and the appearance is not deteriorated. It is possible to provide a wiring board in which the mechanical strength of the base is increased and the conduction of the wiring conductor layer and the through-hole conductor layer inside the insulating base is ensured.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a wiring board according to the present invention will be described based on an embodiment shown in FIG. FIG. 1 is a sectional view showing an embodiment of a wiring board according to the present invention, wherein 1 is an insulating base formed by laminating a plurality of insulating layers, 2 is a conductor layer 2a and an auxiliary conductor layer 2
and 3 is a through-hole conductor layer.

The insulating substrate 1 is made of a ceramic material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a glass ceramic sintered body, a crystallized glass sintered body, and the like. Active components such as semiconductor devices and passive components such as capacitance devices and resistors are mounted on the device.

A wiring conductor layer 2 having a predetermined pattern is formed inside and on the surface of the insulating base 1. Active components such as semiconductor elements mounted on the upper surface of the insulating base 1 and capacitive elements are formed on the wiring conductor layer 2. , Resistors and other passive components are electrically connected.

The wiring conductor layer 2 has a conductor layer 2a made of metal particles having an average particle diameter of 5 μm or less, and a conductor layer 2a having an average particle diameter of 6 μm or less.
It has a two-layer structure of an auxiliary conductor layer 2b composed of 20 μm metal particles. Examples of the metal powder include gold, silver, platinum, palladium, copper, nickel, molybdenum, tungsten, and alloys thereof. Metal powder composed of an alloy as a main component is used.

The conductor layer 2a is electrically connected to the electrodes of the active component and the passive component and functions as a main conductor layer for transmitting an electric signal, and the auxiliary conductor layer 2b is a conductive layer serving as the wiring conductor layer 2. When the paste is applied to a ceramic green sheet serving as the insulating substrate 1 by printing and baking, the paste serves as a discharge path for gaseous organic substances discharged from the conductive paste or the like to the outside.

When the average particle diameter of the metal powder forming the conductor layer 2a of the wiring conductor layer 2 exceeds 5 μm, the packing density of the metal powder becomes low and the electric resistance becomes high. Therefore, the conductor layer 2a of the wiring conductor layer 2 is specified so that the metal powder forming the conductor layer 2a has an average particle diameter of 5 μm or less.

The auxiliary conductor layer 2b of the wiring conductor layer 2
If the particle size of the metal powder forming the powder exceeds 20 μm, the gap between the metal powders is large, so that moisture or the like in the outside air easily penetrates, and the wiring conductor layer 2 is easily oxidized. When the thickness is less than that, the gap between the metal powders is reduced, and the conductive paste to be the wiring conductor layer 2 is stacked at a high density on the photo-cured ceramic sheet on which the conductive paste is printed and applied at high density, and is discharged from the conductive paste when firing. A large amount of gaseous organic matter cannot be effectively discharged to the outside. Therefore, the auxiliary conductor layer 2b of the wiring conductor layer 2 has a particle diameter of the metal powder forming the auxiliary conductor layer 2b specified in the range of 6 μm to 20 μm.

Further, the insulating base 1 has a plurality of through holes 4 having a diameter of 60 μm or less formed in the thickness direction thereof, and the through holes 4 are filled with the through hole conductor layers 3.

The through-hole conductor layer 3 extends the wiring conductor layer 2 formed on the inside and / or the surface of the insulating base 1 toward the lower surface side of the insulating base 1 so that the wiring conductor layer 2 on the upper surface of the insulating base 1 and the insulating base 1 1 has a function of connecting the wiring conductor layer 2 inside the wiring substrate 1 and electrically connecting the wiring conductor layer 2 on the upper surface of the insulating substrate 1 to an external electric circuit on the lower surface side of the insulating substrate 1.

The through holes 4 formed in the insulating substrate 1
Since the diameter of the through hole 4 is as small as 60 μm or less, the through holes 4 can be formed in the insulating base 1 at high density, and at the same time, the through hole conductor layers 3 formed in the through holes 4 are formed.
Can be formed at a very high density.

The through-hole conductor layer 3 is made of, for example, gold,
It is formed of silver, platinum, palladium, copper, nickel, molybdenum, tungsten or an alloy thereof, or an alloy containing these as a main component.

Next, a method for manufacturing the above-described wiring board will be described with reference to FIGS. FIG. 2 (a)
2A to 2F are cross-sectional views for explaining the method of manufacturing a wiring board according to the present invention in each step. First, as shown in FIG. 2A, a plurality of photosensitive ceramic green sheets 11 are formed.

The photosensitive ceramic green sheet 11
Is a ceramic powder, a photoreactive compound, a photopolymerization initiator,
A photosensitive resin composition comprising a photopolymerization accelerator and, if necessary, an organic binder, an ultraviolet absorber, a thermal polymerization inhibitor, a non-photosensitive polymer, etc. are mixed to form a photosensitive slurry, and the photosensitive slurry is prepared. It is formed by forming into a sheet by a doctor blade method, a calendar roll method, or the like.

The photosensitive ceramic green sheet 11
Glass ceramic powder, alumina powder, mullite powder, aluminum nitride powder, crystallized glass powder, etc. are used as ceramic powder used when forming
For example, when the glass ceramic powder is used, magnesium oxide (MgO) 10.8 wt%, aluminum oxide (Al ₂ O ₃₎ 28.0 wt%, silicon oxide (SiO ₂₎ 43.8% by weight, Zinc oxide (ZnO) 7.
Silicon oxide (SiO ₂ ) powder was added to 20% by weight of a glass component composed of boron (B ₂ O ₃ ) in an amount of 20% by weight.
What is set as the weight% is used suitably.

The photoreactive compound used for forming the photosensitive ceramic green sheet 11 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 in forming the photosensitive ceramic green sheet 11 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 for forming the photosensitive ceramic green sheet 11 has an effect of accelerating the photocuring reaction of the photoreactive compound.
-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 11 has a function of binding with 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 11 is such that ultraviolet rays irradiated to cause a photo-curing 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 11 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 photoreactive compounds are partially polymerized by the free radicals, so that it is difficult to dissolve in a developer, and it is difficult to form through holes by a photolithography method. Quinone, hydroquinone, methylhydroquinone, nitrosoaluminum salt, hydroquinone monomethyl ether, 2,6-t-
Butyl-p-cresol, 2,3-dimethyl-6-t-
Butylphenol may be mentioned, and one or more of these may be used.

The non-photosensitive polymer used in forming the photosensitive ceramic green sheet 11 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 12 is formed on the upper surface of the photosensitive ceramic green sheet 11.

The photomask pattern 12 is formed on the upper surface of the photosensitive ceramic green sheet 11 by employing a photolithography technique capable of fine processing, and the shape thereof corresponds to the shape of the through hole to be formed. Has become.

Next, a photomask pattern 12 is formed on the upper surface.
Ceramic green sheet 11 coated with
Then, ultraviolet rays having an intensity of, for example, about 300 mj / cm ² are irradiated from the side of the photomask pattern 12 to irradiate a portion where the photomask pattern 12 is not present, and the photosensitive resin composition in the region irradiated with the ultraviolet rays is irradiated. As shown in FIG. 1 (c), by subjecting the object to photo-polymerization and photo-curing, the region covered with the photomask pattern 12 and not irradiated with ultraviolet rays, that is, the uncured region is removed by development. A photo-cured ceramic sheet 11a having a through hole 13 formed at a predetermined position is obtained.

The photosensitive ceramic green sheet 11
When the photo-cured ceramic sheet 11a having the through holes 13 is formed by irradiating light such as ultraviolet rays to the substrate, the photo mask patterns 12 are formed by adopting a photolithography technique capable of fine processing, so that the through holes 13 are formed. Can be made as small as 60 μm or less. At the same time, the formation of the through-hole 13 is performed by irradiating light such as ultraviolet rays through a photomask pattern and removing the uncured area by development. It can be carried out.

As a developer for removing the uncured photosensitive resin composition for forming the through hole 13, for example, an organic alkali solution such as triethanolamine is used. Of the organic binder in the uncured photosensitive ceramic green sheet 11 removes hydrogen ions from the carboxyl group of the organic binder, 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 11a having the through holes 13 is formed, the average particle size of the ceramic powder contained in the photosensitive ceramic green sheet 11 is about 2 μm (D5 by the microtrack method).
When the value is set to 0), the ultraviolet light can be transmitted well and photocuring can be performed uniformly. Therefore, it is preferable that the average particle size of the ceramic powder of the photosensitive ceramic green sheet 11 is about 2 μm.

When the photoreactive compound contained in the photosensitive ceramic green sheet 11 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 13 are formed in the photosensitive ceramic green sheet. It becomes easy to form the sheet 11 uniformly in the thickness direction. Therefore, the photosensitive ceramic green sheet 1
It is preferable that the amount of the photoreactive compound contained in No. 1 is 5 to 12 parts by weight based on 100 parts by weight of the ceramic powder. The photopolymerization initiator contained in the photosensitive ceramic green sheet 11 is added in an amount of 0.5 to 5 based on 100 parts by weight of the ceramic powder.
By setting the amount by weight, the photo-curing reaction can be started uniformly in the photosensitive ceramic green sheet 11.
Therefore, the amount of the photopolymerization initiator contained in the photosensitive ceramic green sheet 11 is preferably set to 0.5 to 5 parts by weight based on 100 parts by weight of the ceramic powder.

When the photopolymerization accelerator contained in the photosensitive ceramic green sheet 11 is added in an amount of 2 to 5 parts by weight based on 100 parts by weight of the ceramic powder, Photocuring reaction can be promoted uniformly. Therefore, it is preferable that the amount of the photopolymerization accelerator contained in the photosensitive ceramic green sheet 11 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 11 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 photosensitive ceramic green sheet 11
The organic binder 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 11 is added in an amount of 0.01 to 2 parts by weight with respect to 100 parts by weight of the ceramic powder, it does not excessively absorb ultraviolet rays. It absorbs effectively and can suppress photocuring of unnecessary parts. Therefore, the amount of the ultraviolet absorber contained in the photosensitive ceramic green sheet 11 is limited to the ceramic powder 100.
It is preferable to set the amount to 0.01 to 2 parts by weight based on parts by weight.

The thermal polymerization inhibitor contained in the photosensitive ceramic green sheet 11 is ceramic powder 100.
When the content is in the range of 0.1 to 5 parts by weight with respect to parts by weight, a small amount of free radicals generated by thermal energy can be effectively absorbed, and the photocuring reaction is not hindered, and the through-hole is not hindered. 13 can be accurately formed at an arbitrary position. Therefore, the amount of the thermal polymerization inhibitor contained in the photosensitive ceramic green sheet 11 is 0.1 to 100 parts by weight of the ceramic powder.
It is preferable to set the range to 5 parts by weight.

When the thickness of the photosensitive ceramic green sheet 11 is less than 10 μm, the mechanical strength is weak, the sheet is easily broken, and handling becomes difficult.
If it exceeds μm, it is difficult for light such as ultraviolet rays irradiated for photocuring to reach the lower surface of the photosensitive ceramic green sheet 11, and the resolution of the formation of the through hole 13 may be reduced. Therefore, it is preferable that the thickness of the photosensitive ceramic green sheet 11 be in the range of 10 to 60 μm.

Then, as shown in FIG. 1D, the photocurable ceramic sheet 11a having the through holes 13 is formed.
A conductive paste is applied to the inside of the through hole 13 by screen printing or spin coating to form a through hole conductor layer 14, and as shown in FIG. An auxiliary conductive paste and a conductive paste are sequentially applied to the surface of the formed photocurable ceramic sheet 11a in a predetermined pattern and a predetermined thickness by a screen printing method, a spin coating method, or the like, and the conductive layer 15 and the auxiliary conductor are sequentially applied from the top. The wiring conductor layer 17 having a two-layer structure of the wiring layer 16 is formed.

The conductor layer 15 functions as a main conductor layer of a wiring conductor layer for transmitting an electric signal in a wiring board obtained after firing, and the auxiliary conductor layer 16 serves as a conductive paste and an auxiliary conductive paste during subsequent firing. It acts as a passage for releasing gaseous organic matter discharged from the outside.

The conductive paste forming the conductive layer 15 may be, for example, gold, silver, platinum, palladium, copper, nickel, molybdenum, tungsten, or an alloy thereof, or a metal powder containing these as a main component. It is formed by adding and mixing an organic solvent and a solvent. In this case, if the average particle size of the metal powder for producing the conductive paste exceeds 5 μm, the metal powder cannot be filled at a high density, and when baked to form a wiring conductor layer, the electric resistance is high. It will be something. Accordingly, the metal powder for producing the conductive paste has an average particle size of 5 μm.
m or less.

When the metal powder for producing the auxiliary conductive paste has a coarse particle having an average particle size exceeding 20 μm, it is printed and applied on the surface of the photo-cured ceramic sheet 11a to form the auxiliary conductor layer 16. At this time, since the gap between the metal powders is large, moisture and the like in the outside air easily penetrate, and the wiring conductor layer in the fired wiring board is easily oxidized. When the thickness is less than 6 μm, the metal powder becomes dense. When filled, it becomes difficult to release the gaseous organic substance to the outside during firing, the gaseous organic substance remains between the layers of the photocurable ceramic sheet, and blisters and the like are generated on the insulating substrate obtained after firing, This results in poor appearance and deterioration of the mechanical strength of the insulating base, and poor conduction of the wiring conductor layer and the through-hole conductor layer inside the insulating base. Therefore, the average particle diameter of the metal powder for producing the auxiliary conductive paste is specified in the range of 6 μm to 20 μm.

Finally, a plurality of photo-cured ceramic sheets 11a having the wiring conductor layer 17 and the through-hole conductor layer 14 are vertically stacked and fired, and the photo-cured ceramic sheet 11a is cured by light. By releasing the organic solvent and the solvent in the photosensitive resin composition and the conductive paste to the outside and simultaneously sintering the ceramic powder and the metal powder, as shown in FIG. A wiring board is completed as a product in which the through-hole conductor layer 14a and the wiring conductor layer 17a including the conductor layer 15a and the auxiliary conductor layer 16a are formed inside and on the surface.

In this case, there is an organic resin having a mesh-like structure in the inside and on the surface of the photo-cured ceramic sheet 11a that prevents movement of organic substances, and the wiring conductor layer formed at high density during firing. A large amount of gaseous organic matter is discharged from the wiring conductor layer 17, and a large amount of gaseous organic matter discharged from the wiring conductor layer 17 and the photocurable ceramic sheet 11 a is used as an auxiliary conductor layer constituting the wiring conductor layer 17. 16 and is not released between the upper and lower photocurable ceramic sheets 11a, and as a result, the adhesion between the upper and lower photocurable ceramic sheets 11a is improved, and the insulating base 11b obtained after firing is obtained. This effectively prevents the occurrence of blisters and the like, enhances the mechanical strength of the insulating base 11b without causing appearance defects, and improves the arrangement inside the insulating base 11b. The conduction of such conductive layers 17a and through-hole conductor layer 14a can be made with certainty.

In particular, when the auxiliary conductor layer 16 has a narrow cross-sectional area of less than 100 μm ² , the auxiliary conductor layer 16 is discharged from the wiring conductor layer 17 and the photocurable ceramic sheet 11a formed at high density during firing. It is difficult to efficiently discharge gaseous organic substances to the outside, and 1 m
If m ² is exceeded, the gap between the metal powders in the wiring conductor layer 17a increases in the fired wiring substrate, and in particular, the wiring substrate has a structure in which the cross section of the wiring conductor layer 17a is exposed on the side surface of the insulating base 11b. In this case, there is a possibility that the wiring conductor layer 17a is easily oxidized and corroded by adsorption of moisture or the like in the outside air. Therefore, the auxiliary conductor layer 16, it is preferable that the area of the cross section and ^{100μm 2 (0.0001mm 2) ~1mm 2} .

The wiring board thus obtained is the insulating substrate 1
1b, electronic components such as semiconductor elements, capacitance elements, resistors and the like are mounted on the surface and the electrodes of each electronic component are electrically connected to the wiring conductor layer 17a and the like. They are electrically connected to each other via the layer 17a and the like, and are also connected to an external electric circuit.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. A structure surrounded by the layer 15 or a structure in which a groove is provided on the bottom surface of the conductor layer and a part of the upper surface of the auxiliary conductor layer is protruded and fitted into the groove.

[0058]

According to the wiring board of the present invention, for the insulating base on which the wiring conductor layer and the through-hole conductor layer are formed, for example, a photosensitive ceramic green sheet in which ceramic powder is dispersed and mixed in a photosensitive resin is used. Because of this, through holes are formed by irradiating a predetermined position of the ceramic green sheet with light and photo-curing the photosensitive resin composition in a predetermined area and removing the photosensitive resin composition in an uncured area by development. Can be formed very easily and with a small diameter of 60 μm or less. As a result, the through-hole conductor layer formed in the through-hole also has a small diameter of 60 μm or less. It becomes possible to form it with high density.

According to the wiring board of the present invention, the wiring conductor layer is composed of a conductor layer composed of metal particles having an average particle diameter of 5 μm or less and an auxiliary conductor layer composed of metal powder having an average particle diameter of 6 μm to 20 μm. Since the layered structure, the conductive paste to be the wiring conductor layer and the through-hole conductor layer is printed and coated at a high density, and the photocured ceramic sheets are stacked one on top of the other, and when baked, the inside of the photocured ceramic sheet and Even if a large amount of gaseous organic matter is discharged from the conductive paste that becomes a high-density wiring conductor layer, even if a large amount of gaseous organic matter is discharged from the surface of the organic resin having a network-like structure that prevents movement of organic matter on the surface, The organic substance is well released to the outside through the auxiliary conductor layer having a coarse average particle diameter of 6 μm to 20 μm of the metal powder to be the auxiliary conductor layer, and stays between the upper and lower photo-cured ceramic sheets. As a result, the adhesion between the upper and lower photo-cured ceramic sheets is improved, and the occurrence of blisters and the like on the insulating substrate obtained after firing is effectively prevented, and the appearance is not deteriorated. It is possible to provide a wiring board in which the mechanical strength of the base is increased and the conduction of the wiring conductor layer and the through-hole conductor layer inside the insulating base is ensured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a wiring board of the present invention.

2 (a) to 2 (f) are cross-sectional views for respective steps for explaining a method of manufacturing the wiring board shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulating base 2 ... Wiring conductor layer 2a ... Conductor layer 2b ... Auxiliary conductor layer 3 ... Through hole conductor layer 4 ... Through hole 11 ... Photosensitivity Ceramic green sheet 12 Photomask pattern 13 Through hole 14 Conductor layer for through hole 15 Conductor layer 15 a Conductor layer 16 Auxiliary conductor layer 16 Auxiliary Conductive layer 17: Conductive layer for wiring 17a ... Wiring conductive layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H05K 3/46 H05K 3/46 SF term (Reference) 4E351 AA07 BB01 BB35 CC12 CC22 CC25 CC27 CC31 CC35 DD04 DD05 DD06 DD17 DD20 DD21 DD52 EE01 EE13 EE21 EE22 FF17 GG02 GG08 5E317 AA24 BB04 BB12 BB13 BB14 BB15 BB16 BB17 BB18 CC22 CC25 CC51 CD21 CD27 GG03 GG11 GG14 5E346 AA12 AA15 AA41 CC32 CC35 CC36 CC37 CC36 CC37 CC24

Claims (4)

[Claims] 1. An insulating substrate made of an electric insulating material and having a through-hole conductor layer having a diameter of 60 μm or less, and formed on the inside and / or surface of the insulating substrate and having an average particle size of 5 μm.
A conductor layer made of the following metal powder and having an average particle size of 6 μm to 2
A wiring conductor layer having a two-layer structure of an auxiliary conductor layer made of 0 μm metal powder. 2. The auxiliary conductor layer has a cross-sectional area of 100 μm ^2.
The wiring board according to claim 1, wherein the thickness is about 1 mm ² . (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 obtained by adding an organic solvent to metal powder having a particle size of 6 μm to 10 μm; and (2) irradiating a predetermined area of the photosensitive ceramic green sheet with light to form a photosensitive resin composition in a predetermined area. Forming a plurality of photo-cured ceramic sheets having through holes penetrating in the thickness direction by photo-curing and developing the photo-cured ceramic sheet; and (3) using the conductive paste to form a plurality of photo-cured ceramic sheets in the through holes of the photo-cured ceramic sheet. Forming a conductor layer for a through hole; and (4) using the conductive paste and the auxiliary conductive paste on the surface of the photocurable ceramic sheet; Forming a wiring conductor layer of a predetermined pattern having a two-layer structure of a body layer and an auxiliary conductor layer; and (5) a plurality of photocured ceramic sheets having the wiring conductor layer and the through-hole conductor layer. Are stacked and fired, and a conductor layer made of metal particles having an average particle size of 5 μm or less and an auxiliary conductor made of metal particles having an average particle size of 6 μm to 10 μm are formed on the inside and / or the surface of the insulating substrate made of ceramic. Forming a wiring conductor layer having a two-layer structure and a through-hole conductor layer. 4. A cross-sectional area of said auxiliary conductor layer is 100 μm.
^The method according to claim 3, wherein the thickness is ² to ¹ mm2.