JP2005093822A - Wiring board made of ceramics, and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic-made insulating substrate and a ceramic-made wiring board which has high reliability of junction to a conductor layer formed on its surface. <P>SOLUTION: The ceramic-made wiring board comprising the ceramic-made insulating substrate and the wiring conductor layer which is joined with at least one surface of the insulating substrate is characterized in that the mathematical mean roughness of the interface of the conductor layer which is joined with the insulating substrate is ≤1.0 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ceramic wiring board provided with a ceramic insulating substrate such as glass ceramic and a method for manufacturing the same.

  Recently, in order to obtain a wiring board with fine dimensions and high dimensional accuracy, a conductive layer in the form of a wiring pattern is formed on the surface of a low-temperature fired ceramic green sheet by photolithography using a metal foil. A method of manufacturing a multilayer wiring board by laminating and baking is developed. Electronic devices such as various devices and capacitors, or printed boards are bonded to the surface conductor layer of the wiring board (insulating board) using a brazing agent such as solder. Therefore, since a mechanical or thermal peeling load is applied to the surface conductor layer, if the bonding strength between the surface conductor layer and the insulating substrate is low, the substrate is broken from this portion, and the electrical Can't keep up the reliability.

As a method for maintaining the bonding strength between the surface conductor layer and the insulating substrate, a metal layer or particles containing at least one kind of Zn, Zr, and Sn is formed on the surface of the copper foil, and such a rough surface is a ceramic. It has been proposed that the copper foil is pressed against the ceramic green sheet in close contact with the green sheet and fired, whereby the anchor of the copper foil is maintained until after firing and is formed by the copper foil. It has been reported that the connection reliability between the surface conductor layer and the insulating substrate can be improved (see Patent Document 1).
Japanese Patent Laid-Open No. 2000-200909

  However, in the method described in Patent Document 1, the insulating layer component (for example, glass) does not sufficiently enter the rough surface of the copper foil, and after firing, voids remain at the joint between the surface conductor layer and the insulating layer, There is a problem that the bonding strength between the surface conductor layer and the insulating substrate cannot be kept sufficiently high.

  Accordingly, an object of the present invention is to provide a ceramic wiring board having high bonding reliability between a ceramic insulating substrate and a conductor layer formed on the surface thereof, and a method for manufacturing the same.

According to the present invention, in a ceramic wiring substrate comprising a ceramic insulating substrate and a wiring conductor layer bonded to at least one surface of the insulating substrate,
There is provided a ceramic wiring board characterized in that an arithmetic mean roughness at an interface of the conductor layer bonded to an insulating substrate is 1.0 μm or less.
The arithmetic average roughness at the interface of the conductor layer bonded to the insulating substrate is obtained by polishing the wiring substrate (insulating substrate) in the direction of the side cross section, and observing the side surface of the conductor layer and the insulating substrate exposed to the side under a microscope, It is calculated by measuring the height difference.

In the ceramic wiring board of the present invention,
(1) The insulating substrate has a surface roughness Ra (JIS B0601) of 0.9 μm or less,
(2) The insulating substrate is composed of glass and filler, and the ratio of the glass is 30% by mass or more.
(3) The insulating substrate has a multilayer structure composed of a plurality of insulating layers, and an internal wiring conductor layer is formed at an interface between adjacent insulating layers;
Is preferred.

Moreover, according to the present invention,
A metal foil having a smooth surface with a surface roughness Ra (JIS B0601) of 0.7 μm or less is pasted on a resin film so that the smooth surface is exposed on the surface, to produce a transfer film,
Processing the metal foil of the transfer film into a wiring pattern shape to form a wiring conductor layer,
The transfer film is bonded to the ceramic green sheet with the wiring conductor layer on the inner surface side, and then the resin film is peeled off to transfer the wiring conductor layer to the surface of the ceramic green sheet.
Next, firing the ceramic green sheet,
A method of manufacturing a ceramic wiring board is provided.

In the above manufacturing method,
(1) Prior to firing the ceramic green sheet, a non-sinterable sheet is laminated on the wiring conductor layer forming surface of the green sheet, and after firing the ceramic green sheet, the non-sinterable sheet is removed.
(2) using copper foil as the metal foil,
(3) Overlaying another ceramic green sheet on the ceramic green sheet having the wiring conductor layer transferred to the surface so that the wiring conductor layer is located on the surface, firing in this state;
(4) The other ceramic green sheet has an internal wiring conductor layer formed on the surface thereof,
Is preferred.

According to the invention,
A metal foil having a smooth surface with a surface roughness Ra (JIS B0601) of 0.7 μm or less is attached to the surface of the ceramic green sheet so that the smooth surface becomes the inner surface, and then the metal foil is wired. Processed into a pattern shape to form a wiring conductor layer,
There is provided a method for manufacturing a ceramic wiring board, wherein the ceramic green sheet is fired.

  According to the present invention, the interface between the wiring conductor layer formed on the surface of the ceramic insulating substrate and the insulating substrate is a smooth surface having an arithmetic average roughness of 1.0 μm or less. The bonding strength with the insulating substrate is remarkably improved, and the connection reliability with various devices, semiconductor elements, printed boards and the like connected via the conductor layer can be increased.

  Generally, in the wiring conductor layer bonded to the surface of the resin insulating substrate, the bonding strength can be increased by making the bonding interface rough. However, when the wiring conductor layer is provided on the ceramic insulating substrate, if the bonding interface of the wiring conductor layer is a rough surface, the bonding strength is remarkably lowered. That is, in the resin-made insulating substrate, the uncured resin with high fluidity adheres to the surface of the wiring conductor layer, so the anchor effect by the rough surface is extremely high, and the wiring conductor layer is insulated by resin by curing the uncured resin. The bonding strength with the substrate can be significantly increased. However, in the ceramic insulating substrate, when the bonding interface of the conductor wiring layer provided on the ceramic green sheet is a rough surface, when firing is performed, many voids are generated in the portion, and as a result, Bonding strength with the wiring conductor layer is reduced. In the present invention, in a wiring board using such a ceramic insulating substrate, the generation of voids at the bonding interface is effective by making the bonding interface of the conductor wiring layer with the insulating substrate smooth as described above. Therefore, the bonding strength between the conductor wiring layer and the ceramic insulating substrate can be remarkably improved.

Hereinafter, the present invention will be described based on specific examples shown in the accompanying drawings.
In FIG. 1 showing an example of the cross-sectional structure of the wiring board of the present invention, the wiring board indicated by 1 as a whole has a ceramic insulating substrate 2 and a wiring conductor layer 3 formed on the surface thereof.

  The insulating substrate 2 is composed of a laminate formed by laminating a plurality of ceramic insulating layers 2a to 2d, and an internal wiring conductor layer 6 is formed between the insulating layers 2a to 2d. In addition, via hole conductors 4 having a diameter of about 80 to 200 μm are formed in the ceramic insulating layers 2 a to 2 d so as to penetrate the thickness direction, whereby the wiring conductor layer 3 on the surface and the internal wiring conductor layers 6 are connected to each other. A network of electrical connections is formed.

  Each of the ceramic insulating layers 2a to 2d constituting the ceramic insulating substrate 2 is formed of a glass powder or glass in order to increase the bonding strength with the insulating substrate 2 by forming a smooth surface on the wiring conductor layer 3 on the surface described later. It is desirable that the powder and ceramic filler powder be formed of glass ceramics fired using a mixed powder obtained by mixing the powder and ceramic filler powder in a mass ratio of 30:70 to 70:30. Such a glass ceramic is advantageous in that the firing temperature is as low as 800 to 1050 ° C., so that it can be co-fired with a low-resistance conductor, which will be described later, and because the dielectric constant is generally low, There is also an advantage that transmission loss such as can be reduced.

The glass component contains at least SiO ₂ and further contains at least one of Al ₂ O ₃ , B ₂ O ₃ , ZnO, PbO, alkaline earth metal oxide and alkali metal oxide. For example, SiO ₂ —B ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ system—MO system (where M represents Ca, Sr, Mg, Ba or Zn), etc. Examples thereof include borosilicate glass, alkali silicate glass, Ba glass, Pb glass, and Bi glass.

  These glasses may be amorphous glass that remains amorphous by firing, or lithium silicate, quartz, cristobalite, cordierite, mullite, anorthite, serdian, spinel, Any crystallized glass that precipitates at least one kind of crystals of garnite, willemite, dolomite, petalite and substituted derivatives thereof can be used.

Examples of ceramic fillers include SiO ₂ such as quartz and cristobalite, Al ₂ O ₃ , ZrO ₂ , mullite, forsterite, enstatite, spinel, magnesia, calcium zirconate, strontium silicate, calcium titanate, barium titanate, etc. Are preferably used.

  The surface wiring conductor layer 3 and the internal wiring conductor layer 6 are formed of at least one type of conductor selected from the group of Cu, Ag, Al, Au, Ni, Pt, and Pd, for example, Cu, Ag, Au, etc. In particular, Cu is most preferable in consideration of the occurrence of migration. Also, when these wiring conductor layers 3 and 6 are formed by a photolithography method using a metal foil, Cu is most preferable because of the ease of pattern formation by etching and the like.

  The wiring conductor layer 3 on the surface is used as a pad for mounting various electronic components 5 such as an IC chip or a conductor film for shielding, and further as a terminal electrode connected to an external circuit such as a printed circuit board. The electronic component 5 or the like is joined via solder or a conductive adhesive.

  The via-hole conductor 4 is preferably formed by being filled with a conductor made of the same component as the above-mentioned surface or internal wiring conductor layers 3 and 6.

  Although not shown, a thick film resistor film such as tantalum silicide or molybdenum silicide, a wiring protective film, or the like may be further formed on the surface of the wiring board 1 as necessary.

  In the present invention, it is an important feature that the wiring conductor layer 3 on the surface is a smooth surface having an arithmetic average roughness of 1.0 μm or less at the bonding interface with the insulating substrate 2. That is, by forming such a smooth surface, no void is generated at the bonding interface during firing, and the surface wiring conductor layer 3 is effectively adhered to the surface of the insulating substrate 2, so that the bonding strength is remarkably increased. It is.

  In the present invention, in order to make the bonding interface between the surface wiring conductor layer 3 and the insulating substrate 2 a smooth surface as described above, and to effectively exhibit the effect of improving the bonding strength by such a smooth surface, insulation is performed. The surface of the substrate 2 is preferably a smooth surface having a surface roughness Ra (JIS B0601) of 0.9 μm or less. That is, when the surface of the insulating substrate 2 is a rough surface with Ra larger than 0.9 μm, the conditions for making the bonding interface of the surface wiring conductor layer 3 smooth as described above become severe. This is because voids are easily generated during firing, and the bonding strength may be reduced.

  In order to make the bonding interface of the surface wiring conductor layer 3 as a smooth surface as described above, for example, when the conductor layer 3 is formed by a photolithography method using a metal foil, the metal foil on the bonding interface side is used. The surface roughness Ra (JIS B0601) is preferably a smooth surface of 0.7 μm or less. That is, by using a metal foil having such a smooth surface, the bonding interface of the formed wiring conductor layer 3 can be made smooth as described above, and the bonding strength can be increased. Furthermore, a Ni plating film or an Au plating film can be formed on the surface wiring conductor layer 3.

(Manufacture of wiring boards)
The above-described method for manufacturing a ceramic wiring board according to the present invention will be described by taking as an example the case where the surface wiring conductor layer 3 is formed by a photolithography method using a transfer method.

  In FIG. 2 which shows an example of the manufacturing process of the ceramic wiring board of the present invention, first, the glass powder and the ceramic filler powder described above are mixed in the above-mentioned quantitative ratio, and this mixture powder is a per se known organic binder, A slurry for molding is prepared by adding a solvent and, if necessary, a plasticizer and the like, and a ceramic green sheet 11 having a thickness of about 50 to 500 μm is produced by using this molding slurry by a doctor blade method, a rolling method, a pressing method, or the like. (FIG. 2a).

  Then, a through-hole having a diameter of 80 to 200 μm is formed in the green sheet 11 by laser, micro drilling, punching, or the like, and a conductor paste is filled therein to form a via-hole conductor 12 (FIG. 2b). This conductor paste is formed by homogeneously mixing an organic binder such as an acrylic resin and an organic solvent such as toluene, isopropyl alcohol, or acetone with a metal component such as Cu or Ag. In general, the organic binder is mixed in an amount of 0.5 to 15.0 parts by mass with respect to 100 parts by mass of the metal component, and the organic solvent is mixed in a ratio of 5 to 100 parts by mass with respect to 100 parts by mass of the organic binder. Is desirable. In addition, you may add some glass components etc. in this conductor paste as needed.

  Next, a wiring conductor layer 13 made of high-purity metal is formed on the surface of the green sheet 11 by a transfer method using a metal foil (particularly Cu foil) (FIG. 2c).

  That is, a metal foil is bonded onto a transfer film made of a polymer material such as polyethylene terephthalate (PET) using an adhesive, and a resist is deposited on the surface of the metal foil in a circuit pattern, followed by an etching process. Then, the resist is removed to form the wiring conductor layer 13 having a predetermined wiring pattern shape. In this case, a metal foil having a surface roughness Ra of 0.7 μm or less is used and bonded so that the smooth surface is on the transfer film side.

  A transfer film having such a wiring conductor layer 13 on the surface thereof is aligned with the surface of the green sheet 11 on which the via-hole conductor 12 is formed, laminated and pressure-bonded, and then the transfer film is peeled off, whereby the wiring conductor layer 13 is green. It can be formed on the surface of the sheet 11. In this case, a smooth surface having a surface roughness Ra of 0.7 μm or less is on the side in close contact with the surface of the green sheet 11.

  Next, a plurality of green sheets produced in the same manner as described above are laminated and pressure-bonded to form a laminate 15 (FIG. 2d). In this case, wiring conductor layers may be formed on both sides of the uppermost or lowermost green sheet. For such lamination, a method in which heat and pressure are applied to the stacked green sheets by thermocompression, a method in which an adhesive composed of an organic binder, a plasticizer, a solvent, etc. is applied between the sheets and thermocompression bonding is adopted. Is possible.

  Furthermore, the non-sinterable sheet 16 is preferably laminated on the upper surface and the back surface of the green sheet laminate 15 (FIG. 2e). This non-sinterable sheet 16 is prepared by adding an organic binder, a plasticizer, a solvent and the like to the ceramic component whose main component is a non-sinterable ceramic material having a high sintering temperature, as in the case of the molding slurry described above. The obtained slurry is formed into a sheet shape.

The hardly sinterable ceramic material is specifically composed of a ceramic composition that does not become densified at a temperature of 1100 ° C. or lower, specifically, Al ₂ O ₃ , SiO ₂ , MgO, ZrO ₂ , BN, Examples thereof include powders of at least one TiO ₂ or a compound thereof (forsterite, enstatite, etc.). In addition, as the organic binder, the plasticizer, and the solvent, the same materials as used in the glass ceramic green sheet can be used. Further, in this non-sinterable sheet, by adding 0.5 to 15% by volume of a glass component, the adhesion to the green sheet 11 is increased, and the action of suppressing shrinkage is increased. It has the advantage that the generation of voids due to the diffusion of the glass component can be suppressed. Such a non-sinterable sheet 16 is laminated | stacked on the said laminated body 15 by the method similar to lamination | stacking of a green sheet. Of course, there is no problem even if the production of the laminate 15 by the lamination of the green sheets 11 and the lamination of the non-sinterable sheet 16 are performed simultaneously.

  Next, heat treatment is performed in a nitrogen atmosphere at 100 to 850 ° C., particularly 400 to 750 ° C. to decompose and remove the organic components in the green sheet and the via-hole conductor paste, followed by baking in a nitrogen atmosphere at 800 to 1100 ° C. When an Ag conductor is used as the conductor layer, the firing atmosphere can be performed in the air.

  Thereafter, the non-sinterable sheet is appropriately removed by ultrasonic cleaning, polishing, water jet, chemical blasting, sand blasting, wet blasting, etc., so that the wiring interface has a predetermined smooth surface on the surface. The ceramic wiring board of the present invention in which the conductor layer 3 is formed is obtained (FIG. 2f).

  In the above-described manufacturing method, the surface conductor layer 3 such as the wiring conductor layer 13 or the inner wiring layer 6 is manufactured by the transfer method, but the wiring conductor layer 13 is formed without using the transfer method. You can also. That is, the wiring conductor layer 13 can also be formed by bonding a metal foil directly to the surface of the ceramic green sheet 11 and photolithography. In this case, what is to be the surface conductor layer 3 may be bonded so that a smooth surface having a surface roughness Ra of 0.7 μm or less is located on the green sheet 11 side.

Moreover, if the surface (burned surface) of the insulating substrate 2 becomes a smooth surface of 0.9 μm or less by firing, the wiring conductor layer 13 can be formed by screen printing or the like. That is, a conductive paste formed by using a low resistance conductive powder such as Cu, Ag, Au or the like is applied to the surface of the ceramic green sheet in a predetermined wiring pattern by screen printing or the like to form the wiring conductor layer 13. can do. In this case, what corresponds to the wiring conductor layer 3 on the surface uses, for example, a fine powder having a volume average particle diameter (D ₅₀ ) of 2 μm or less as the low-resistance conductor powder, thereby forming the smooth joint interface described above. This is preferable.

Crystalline glass powder a having an average particle diameter of 3 μm having a composition of SiO ₂ : 37 mass%, Al ₂ O ₃ : 27 mass%, CaO: 11 mass%, ZnO: 12 mass%, B ₂ O ₃ : 13 mass% A glass ceramic raw material powder A was prepared by mixing 73% by mass (softening point 850 ° C.) and 27% by mass of silica (ceramic filler) having an average particle diameter of 2 μm. To 100 parts by mass of this glass ceramic raw material powder A, 11 parts by mass of isobutyl methacrylate resin as an organic binder is added in an amount of 11 parts by mass, and 5 parts by mass of dibutyl phthalate as a plasticizer. The slurry was adjusted. A green sheet having a thickness of 0.2 mm was prepared from the obtained slurry by a doctor blade method.

  Further, a glass ceramic raw material powder B was prepared in the same manner as described above except that silica having an average particle diameter of 2.5 μm was used as the ceramic filler, and this glass ceramic raw material powder B was used in exactly the same manner as described above. Thus, a green sheet having a thickness of 0.2 mm was produced.

  Further, a glass ceramic raw material powder C was prepared in the same manner as described above except that silica having an average particle size of 3 μm was used as the ceramic filler, and using this glass ceramic raw material powder C, exactly as described above, A green sheet having a thickness of 0.2 mm was produced.

  Further, 100 parts by mass of a glass ceramic raw material powder composed of 10% by mass of the crystalline glass powder a and 90% by mass of alumina powder having a diameter of 2 μm, 11 parts by mass of an isobutyl methacrylate resin as an organic binder, and phthalate as a plasticizer 5 parts by mass of dibutyl acid was added, and a non-sinterable sheet having a thickness of 0.4 mm was produced in the same manner as the previous green sheet.

  Next, a terminal connected to the external circuit having the shape shown in FIG. 3 by a photoetching method on a 0.02 mm thick copper foil (having a smooth surface with a surface roughness Ra shown in Table 1) formed on the PET film. A conductor layer 23 to be an electrode was produced. Each terminal had a diameter of 0.5 mm and an arrangement pitch of 1 mm. The copper foil was provided on the PET film so that the smooth surface side was exposed on the surface.

  Next, a through hole is formed in a portion corresponding to the terminal of the green sheet made of the ceramic raw material powders A, B, and C, and a via hole conductor is formed by filling the through hole with a copper paste. The conductor layer 23 formed on the film was heat-pressed, the PET film was peeled off, and the conductor layer was transferred to the green sheet surface. Further, on the opposite surface of the green sheet, a conductor layer electrically connecting adjacent vias was similarly processed and transferred. The copper paste was prepared by mixing an organic binder (5 parts by mass of polyacrylic acid with 100 parts by mass of copper powder and 15 parts by mass of a solvent (α-terpineol).

  Then, on the opposite side of the transfer green sheet to the conductor layer 23, the green sheet is overlaid so that the thickness after firing is 1.5 mm, and further, the non-sinterable sheet is overlaid on each side of the three sheets on one side. In addition, thermocompression bonding was performed at 80 ° C. and 10 MPa to obtain a laminate.

  Thereafter, in order to decompose and remove the organic components (binder, plasticizer, etc.) in the laminate, heat treatment was performed at 750 ° C. for 3 hours in a nitrogen atmosphere containing water vapor to reduce the residual carbon content to 300 ppm or less. Then, after baking at 930 degreeC for 1 hour, the blasting process by the alumina projection material was performed, and the wiring board which comprises the conductor layer 23 on the ceramic insulating substrate surface was produced. Further, a Ni plating layer having a thickness of 3 μm and an Au plating layer having a thickness of 1 μm were deposited on the conductor layer 23 on the surface of the wiring board by an electroless plating method.

  The terminal (conductor layer 23) on the surface of the ceramic wiring board formed as described above is mounted on a corresponding printed board with a high-temperature solder ball having a diameter of 0.7 mm, and a temperature cycle test of 0 to 100 ° C. is performed. The connection between the printed board and the conductor layer 23 on the surface of the insulating board was electrically confirmed. The temperature cycle test is conducted up to 4000 cycles, and the connection between the ceramic insulating substrate and the conductor layer 23 on the surface of the ceramic insulating substrate is judged as defective when the electrical resistance is increased by 20% or more from before the temperature cycling test, and the mode of the failure is confirmed. I did it.

Further, the surface roughness Ra of the insulating substrate and the copper foil was measured with a contact-type surface roughness meter.
Further, the roughness of the bonding interface between the surface conductor layer 23 and the insulating substrate was determined as an average value of the height difference by polishing the substrate in the cross-sectional direction and observing the side surface of the conductor portion with a microscope.

  According to the results in Table 1, in the sample (Nos. 1 to 3) using the copper foil with the surface roughness Ra = 0.3 to 1.0 μm, the roughness at the interface between the surface conductor layer 23 and the insulating substrate. (Hereinafter simply referred to as interface roughness) was 0.6 to 1.0 μm. When copper foils having a surface roughness Ra of 0.3 μm, 0.6 μm, and 1.0 μm were used, no increase in electrical resistance was observed up to 4000 cycles, 3000 cycles, and 2000 cycles, respectively. On the other hand, Sample No. using a copper foil having a surface roughness Ra of 1.5 μm. In No. 4, the interface roughness of the surface conductor layer 23 was 1.1 μm, and an increase in electric resistance value was observed at 1000 temperature cycles.

  Sample No. In No. 5, the surface roughness of the insulating substrate was Ra = 1.0 μm. At this time, the interface roughness of the surface conductor layer 23 was 1.0 μm, and no increase in electrical resistance was observed up to 2000 temperature cycles, but the sample No. 1 in which the surface roughness Ra of the insulating substrate was 1.0 μm was obtained. In No. 6, the interface roughness of the surface conductor layer 23 was 1.1 μm, and an increase in electrical resistance was observed even at a temperature cycle of 1000 cycles.

  From the above experimental results, in the present invention in which the surface roughness of the surface conductor layer 23 is 1.0 μm or less, the bonding strength between the printed board and the surface conductor layer 23 is improved, and the connection reliability is enhanced. I understand that.

It is a figure which shows an example of the cross-section of the ceramic wiring board of this invention. It is process drawing which shows an example of the manufacturing process of the ceramic wiring boards of this invention. It is a pattern figure of the wiring circuit for evaluation (surface conductor layer).

Explanation of symbols

1: Ceramic wiring board 2: Ceramic insulating boards 2a to 2d: Insulating layer 3: Surface wiring conductor layer 4: Via hole conductor 5: Semiconductor element 6: Internal wiring conductor layer

Claims (10)

In a ceramic wiring substrate comprising a ceramic insulating substrate and a wiring conductor layer bonded to at least one surface of the insulating substrate,
A ceramic wiring board having an arithmetic mean roughness of 1.0 μm or less at an interface between the conductor layer and the insulating substrate.   The ceramic wiring board according to claim 1, wherein the insulating substrate has a surface roughness Ra (JIS B0601) of 0.9 μm or less.   The ceramic wiring board according to claim 1 or 2, wherein the insulating substrate is made of glass and a ceramic filler, and the ratio of the glass is 30% by mass or more.   4. The ceramic product according to claim 1, wherein the insulating substrate has a multilayer structure including a plurality of insulating layers, and an internal wiring conductor layer is formed at an interface between adjacent insulating layers. Wiring board. A metal foil having a smooth surface with a surface roughness Ra (JIS B0601) of 0.7 μm or less is pasted on a resin film so that the smooth surface is exposed on the surface, to produce a transfer film,
Processing the metal foil of the transfer film into a wiring pattern shape to form a wiring conductor layer,
The transfer film is bonded to the ceramic green sheet with the wiring conductor layer on the inner surface side, and then the resin film is peeled off to transfer the wiring conductor layer to the surface of the ceramic green sheet.
Next, firing the ceramic green sheet,
A method of manufacturing a ceramic wiring board characterized by the above.   The non-sinterable sheet is laminated on the wiring conductor layer forming surface of the green sheet prior to firing the ceramic green sheet, and the non-sinterable sheet is removed after firing the ceramic green sheet. Manufacturing method.   The method for manufacturing a ceramic wiring board according to claim 5, wherein a copper foil is used as the metal foil.   The ceramic green sheet on which the wiring conductor layer is transferred is overlaid with another ceramic green sheet so that the wiring conductor layer is positioned on the surface, and firing is performed in this state. The manufacturing method of the ceramic wiring board as described.   The method for manufacturing a ceramic wiring board according to claim 8, wherein an inner wiring conductor layer is formed on a surface of the other ceramic green sheet. A metal foil having a smooth surface with a surface roughness Ra (JIS B0601) of 0.7 μm or less is attached to the surface of the ceramic green sheet so that the smooth surface becomes the inner surface, and then the metal foil is wired. Processed into a pattern shape to form a wiring conductor layer,
A method for producing a ceramic wiring board, comprising firing the ceramic green sheet.

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