JP4407781B2 - Manufacturing method of ceramic circuit board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a ceramic circuit board in which a wiring pattern is formed by a photolithography method.
[0002]
[Prior art]
Conventionally, the wiring pattern of a ceramic circuit board is often formed by a thick film method using a screen printing technique, but the thick film method has a limit in order to meet the demand for higher density wiring in recent years. In addition, it has been proposed to form a fine wiring pattern (fine pattern) using a photolithography method capable of forming a finer wiring. In this photolithography method, a wiring pattern is formed later on the surface of the fired ceramic circuit board for the reason described later.
[0003]
[Problems to be solved by the invention]
In the photolithography method, a photosensitive conductive paste is printed on a substrate surface and dried, and then a printed layer of the photosensitive conductive paste is exposed and developed to form a wiring pattern. If an attempt is made to form a wiring pattern on a ceramic raw substrate (ceramic green sheet) before firing by photolithography, the ceramic green sheet is porous, so the liquid in the photosensitive conductor paste printed on the ceramic green sheet. The photosensitive vehicle which is a component penetrates into the ceramic green sheet, and the photosensitive vehicle in the printed layer of the photosensitive conductor paste is reduced. As a result, the photosensitivity of the printed layer of the photosensitive conductor paste is lowered, and the portion to be cured is not sufficiently cured at the time of exposure, and a part of the portion necessary for forming the wiring pattern flows down during the development. As a result, disconnection of the wiring pattern and poor conduction occur.
[0004]
For this reason, in the conventional photolithography method, a wiring pattern cannot be formed on the ceramic green sheet, and the wiring pattern has to be formed later on the surface of the fired ceramic circuit board. For this reason, the conventional photolithography method cannot form the inner layer wiring pattern of the multilayer ceramic circuit board, and the ceramic circuit board and the wiring pattern cannot be simultaneously fired, resulting in an increase in the number of firings. There was also.
[0005]
By the way, the ceramic green sheet is obtained by tape-molding a mixture of ceramic powder, a binder component, a solvent, and the like. As the binder component increases, the ceramic green sheet is densified and voids decrease. Therefore, if the blending amount of the binder component of the ceramic green sheet is increased, even if the photosensitive conductor paste is printed on the ceramic green sheet, the amount of the photosensitive vehicle in the photosensitive conductor paste soaks into the ceramic green sheet is small. However, if the blending amount of the binder component of the ceramic green sheet is increased, the binder removal time required to scatter the binder component during firing becomes longer, and the firing time becomes longer and the productivity is lowered. For this reason, in order to shorten the firing time (binder removal time) of a normal ceramic green sheet, the amount of the binder component is minimized, and as a result, there are many voids in the ceramic green sheet. I can do it. For this reason, when the photosensitive conductive paste is printed on the ceramic green sheet, the photosensitive vehicle in the photosensitive conductive paste penetrates into the ceramic green sheet, and the photosensitivity of the printed layer of the photosensitive conductive paste decreases. , Wiring pattern formation defects occur.
[0006]
The present invention has been made in consideration of such circumstances, and therefore the object thereof is a ceramic circuit capable of forming a wiring pattern by photolithography on the surface of a ceramic green sheet (ceramic raw substrate) before firing. It is to provide a method for manufacturing a substrate.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to a method of manufacturing a ceramic circuit board according to claim 1 of the present invention, when a wiring pattern is formed by a photolithography method, first, a surface of a ceramic green sheet is coated with a photosensitive conductor paste. After forming a dense layer that prevents the penetration of the photosensitive vehicle, the photosensitive conductor paste is printed on the surface of the dense layer and dried, and then the printed layer of the photosensitive conductor paste is exposed and developed for wiring. A pattern is formed. In this method, since the dense layer is formed on the surface of the ceramic green sheet before printing the photosensitive conductor paste, the dense layer prevents the photosensitive vehicle in the photosensitive conductor paste from penetrating into the ceramic green sheet. Thus, the photosensitivity of the printed layer of the photosensitive conductor paste is prevented from being lowered. This makes it possible to form a fine wiring pattern on the surface of the ceramic green sheet by photolithography.
[0008]
In this case, as in the second aspect, when forming the dense layer, an organic vehicle containing a binder component may be applied to the surface of the ceramic green sheet to form the dense layer. As described above, when the organic vehicle containing the binder component is applied to the surface of the ceramic green sheet, the binder component of the organic vehicle soaks into the void in the surface layer of the ceramic green sheet, and the void is blocked by the binder component. There are very few voids in the layer. Thereby, a dense layer for preventing the penetration of the photosensitive vehicle in the photosensitive conductive paste is formed on the surface layer of the ceramic green sheet.
[0009]
Further, as in claim 3, the binder component of the organic vehicle used for forming the dense layer may be the same as the binder component in the ceramic green sheet. In this way, the organic vehicle (mixture of binder component and solvent) mixed with the ceramic green sheet forming raw material can be used for forming the dense layer, and it is necessary to develop a new material dedicated to the dense layer. There is no.
[0010]
According to the present invention, a single-layer ceramic circuit board may be manufactured by simultaneously firing the wiring pattern and the ceramic green sheet after the formation of the wiring pattern. As described above, after forming the wiring pattern on the surface of a plurality of ceramic green sheets, a plurality of ceramic green sheets may be laminated and fired simultaneously to produce a multilayer ceramic circuit board. . In other words, according to the present invention, since a wiring pattern can be formed on the surface of the ceramic green sheet by a photolithography method, an inner layer wiring pattern of a multilayer ceramic circuit board can also be formed by a photolithography method, and the ceramic circuit board and the wiring pattern are simultaneously fired. can do.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a method for manufacturing a multilayer ceramic circuit board according to an embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the following steps 1 to 8 are performed to manufacture a multilayer ceramic circuit board.
[0012]
[Step 1: Molding of ceramic green sheet]
First, a green sheet 11 of low-temperature fired ceramic is tape-molded by a doctor blade method or the like using a slurry of low-temperature fired ceramic. The low-temperature fired ceramic slurry used in this molding is a mixture of a low-temperature fired ceramic powder and a binder component, a solvent, a plasticizer, and the like. As the low-temperature fired ceramic, CaO—SiO ₂ —Al ₂ O ₃ —B ₂ O A mixture of 50 to 65% by weight (preferably 60% by weight) of ₃ series glass and 50 to 35% by weight (preferably 40% by weight) of alumina may be used. In addition, for example, a mixture of MgO—SiO ₂ —Al ₂ O ₃ —B ₂ O ₃ glass and alumina, a mixture of SiO ₂ —B ₂ O ₃ glass and alumina, PbO—SiO ₂ —B ₂ O ₃ A low-temperature fired ceramic that can be fired at 800 to 1000 ° C., such as a mixture of glass and alumina, or cordierite crystallized glass, may be used.
[0013]
The binder component may be a resin such as an acrylic resin (isobutyl methacrylate copolymer) or a butyral resin, and the solvent may be toluene, ethanol, xylene, or the like. In this case, in order to shorten the firing time (binder removal time) of the ceramic green sheet 11, the blending amount of the binder component is almost the minimum necessary, and the binder component is 2 to 30 with respect to 100 parts by weight of the ceramic powder. Part by weight, more preferably 5 to 20 parts by weight.
[0014]
[Process 2: Cutting and punching of ceramic green sheets]
In this step 2, the tape-shaped band-shaped ceramic green sheet 11 is cut into a square having a predetermined size to produce a plurality of ceramic green sheets 11 and the layers are electrically connected to predetermined positions of each ceramic green sheet 11. A via hole (not shown) for connecting to is punched.
[0015]
[Step 3: Filling via conductor]
In step 3, the via holes of the ceramic green sheets 11 of each layer are filled with a low melting point metal conductor paste such as Ag, Au, or Cu by screen printing to form via conductors.
[0016]
[Step 4: Formation of dense layer]
In this step 4, an organic vehicle having the same composition as that of the organic vehicle (mixture of binder component and solvent) used for producing the low-temperature fired ceramic slurry is used. Then, the organic vehicle is applied to the entire surface of the ceramic green sheet 11 by a coating method such as a roll coater method or a curtain coater method and dried to form the dense layer 12 on the surface layer of the ceramic green sheet 11.
[0017]
At this time, the binder component of the organic vehicle applied to the surface of the ceramic green sheet 11 penetrates into the voids in the surface layer of the ceramic green sheet 11 and the voids are blocked with the binder component, and the voids in the surface layer are extremely reduced. As a result, a dense layer 12 is formed on the surface layer of the ceramic green sheet 11 to prevent penetration of a photosensitive vehicle in a photosensitive conductor paste described later.
[0018]
The dense layer 12 may be formed by a dipping method instead of the coating method. In the dip method, the ceramic green sheet 11 is immersed in an organic vehicle solution, and the organic vehicle is attached to the entire surface of the ceramic green sheet 11.
[0019]
[Step 5: Printing and drying of photosensitive conductor paste]
In this step 5, the photosensitive conductor paste is printed on the surface of the dense layer 12 of the ceramic green sheet 11 and dried to form the printed layer 13 of the photosensitive conductor paste on the surface of the dense layer 12 of the ceramic green sheet 11. To do. The photosensitive conductor paste used in Step 5 is prepared by mixing a low melting point metal powder such as Ag, Au, or Cu and a photosensitive vehicle, and the photosensitive vehicle is a photosensitive material such as an acrylic oligomer. It is made by mixing a resin and a solvent.
[0020]
[Step 6: Exposure and development processing]
In this step 6, a mask (not shown) on which the negative pattern of the wiring pattern 13a to be formed on the ceramic green sheet 11 is placed on the printed layer 13 of the photosensitive conductor paste, and light from a mercury lamp or the like is used as a mask. Irradiate toward. Thereby, only the part used as the wiring pattern 13a of the printing layer 13 of the photosensitive conductor paste is irradiated with light, and is hardened. After the exposure, development processing is performed, and uncured portions (portions other than the wiring pattern 13a) of the printed layer 13 of the photosensitive conductive paste that have not been exposed to light are dissolved and removed with a developer, and the cured portions that have been exposed to light. The wiring pattern 13a is formed leaving only
[0021]
[Step 7: Lamination of ceramic green sheets]
After forming the wiring pattern 13a on the plurality of ceramic green sheets 11 by the photolithography method by the above steps, the plurality of ceramic green sheets 11 are laminated and laminated, and the laminated body is integrated by thermocompression bonding. To do.
[0022]
[Step 8: Firing]
In step 8, the laminated body of ceramic green sheets 11 is fired at 800 to 1000 ° C. During this firing process, the binder components in the ceramic green sheet 11, the dense layer 12, and the wiring pattern 13a are scattered, and the ceramic substrate and the wiring pattern 13a are simultaneously fired to produce a multilayer ceramic circuit board.
[0023]
According to the manufacturing method of the multilayer ceramic circuit board of the present embodiment described above, the dense layer 12 is formed between the ceramic green sheet 11 and the printed layer 13 of the photosensitive conductor paste. The dense layer 12 prevents the photosensitive vehicle in the printed layer 13 from penetrating into the ceramic green sheet 11, and prevents the photosensitive layer of the photosensitive conductive paste from deteriorating. Thereby, it becomes possible to form a fine wiring pattern 13a on the surface of the ceramic green sheet 11 by photolithography.
[0024]
According to the experiment results of the present inventor, when the multilayer ceramic circuit board is manufactured by the manufacturing method of the present embodiment, the wiring pattern 13a is not disconnected or defective in conduction, and the fine wiring pattern 13a is obtained with a high yield by photolithography. It was confirmed that it can be formed.
[0025]
As a comparative example, the inventor has omitted the step 4 (formation of the dense layer 12) and manufactured the multilayer ceramic circuit board by the other steps 1 to 3 and 5 to 8. A conduction failure occurred and a normal wiring pattern could not be formed.
[0026]
By the way, the ceramic green sheet 11 is densified and the space | gap decreases, so that there are many binder components. Therefore, when the blending amount of the binder component of the ceramic green sheet 11 is increased, even if the photosensitive conductor paste is printed on the ceramic green sheet 11, the photosensitive vehicle in the photosensitive conductor paste penetrates into the ceramic green sheet 11. If the amount of the binder component of the ceramic green sheet 11 is increased, the binder removal time required for scattering the binder component during firing becomes longer, the firing time becomes longer, and the productivity decreases.
[0027]
On the other hand, in the present embodiment, by applying an organic vehicle to the surface of the ceramic green sheet 11, the binder component of the organic vehicle is soaked into the voids in the surface layer of the ceramic green sheet 11, and only the surface layer is bonded to the binder. Since the components are densified and densified, the binder removal time required to scatter the binder components during firing is not so long, unlike the case where the amount of the binder component in the entire ceramic green sheet 11 is increased. It can be fired in a relatively short time. Moreover, unlike the conventional photolithography method (a wiring pattern is formed later after the substrate is fired), the ceramic circuit board and the wiring pattern 13a can be fired at the same time. Can be improved.
[0028]
The present invention is not limited to a multilayer ceramic circuit board, and may be applied when a single-layer ceramic circuit board is manufactured.
In the above embodiment, the dense layer 12 is formed using an organic vehicle having the same composition as that of the organic vehicle used when the low-temperature fired ceramic slurry is produced. Therefore, a new material dedicated to the dense layer 12 is used. There is no need for development, and material costs can be reduced accordingly.
[0029]
However, the blending ratio of the binder component of the organic vehicle used for forming the dense layer 12 may be larger than the blending ratio of the binder component of the organic vehicle used for the low-temperature fired ceramic slurry. As the binder component of the organic vehicle to be used, a resin different from the binder component of the ceramic green sheet 11 may be used.
[0030]
The present invention is not limited to a low-temperature fired ceramic circuit board, and may be applied to a ceramic circuit board fired at around 1600 ° C., such as an alumina circuit board or an AlN circuit board. In this case, the photosensitive conductor paste may be prepared by mixing a refractory metal such as W or Mo and a photosensitive vehicle.
[0031]
【The invention's effect】
As is clear from the above description, in claim 1 of the present invention, after forming a dense layer on the surface of the ceramic green sheet, a photosensitive conductor paste is printed on the surface of the dense layer and dried, Since the printed layer of the photosensitive conductive paste is exposed and developed to form a wiring pattern, a fine wiring pattern can be formed on the surface of the ceramic green sheet by photolithography, and the ceramic and the wiring pattern are simultaneously fired. And the number of firings can be reduced.
[0032]
Furthermore, in claim 2, since the organic vehicle containing the binder component is applied to the surface of the ceramic green sheet, and only the surface layer is densified by increasing the binder component, the binder component of the entire ceramic green sheet is reduced. Unlike the case where the blending amount is increased, the binder removal time does not have to be so long, and firing can be efficiently performed in a relatively short time.
[0033]
Moreover, since the binder component of the organic vehicle used for forming the dense layer is the same as the binder component in the ceramic green sheet, the organic vehicle mixed with the forming raw material of the ceramic green sheet is also used for forming the dense layer. The material cost can be reduced.
[0034]
According to the fourth aspect of the present invention, after the wiring pattern is formed, the wiring pattern and the ceramic green sheet are simultaneously fired to produce a single-layer ceramic circuit board. Therefore, a fine wiring pattern is formed by photolithography. Thus, the single-layer ceramic circuit board can be efficiently manufactured.
[0035]
According to the fifth aspect of the present invention, a plurality of ceramic green sheets each having a wiring pattern formed thereon by photolithography are laminated, and these are simultaneously fired to produce a multilayer ceramic circuit board. A multilayer ceramic circuit board on which a simple wiring pattern is formed can be efficiently manufactured.
[Brief description of the drawings]
FIG. 1 is a process flowchart showing a flow of a manufacturing process of a multilayer ceramic circuit board in an embodiment of the present invention. FIG. 2 is a cross-sectional view of a main part for explaining work contents of each process of manufacturing a multilayer ceramic circuit board. [Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Ceramic green sheet, 12 ... Dense layer, 13 ... Printed layer of photosensitive conductor paste, 13a ... Wiring pattern.

Claims (5)

A method for producing a ceramic circuit board, wherein a wiring pattern is formed by a photolithography method on a surface of a ceramic green sheet using a photosensitive conductor paste that can be fired simultaneously with the ceramic green sheet,
After forming a dense layer for preventing the penetration of the photosensitive vehicle in the photosensitive conductor paste on the surface of the ceramic green sheet, the photosensitive conductor paste is printed on the surface of the dense layer and dried, and then A method for producing a ceramic circuit board, comprising exposing and developing a printed layer of the photosensitive conductor paste to form a wiring pattern. When forming the dense layer, an organic vehicle containing a binder component is applied to the surface of the ceramic green sheet, and the binder component is impregnated into the voids in the surface layer of the ceramic green sheet, thereby the surface of the ceramic green sheet The method for producing a ceramic circuit board according to claim 1, wherein the dense layer is formed on a layer. 2. The method of manufacturing a ceramic circuit board according to claim 1, wherein the organic vehicle used for forming the dense layer includes the same binder component as the binder component in the ceramic green sheet. 4. The method for manufacturing a ceramic circuit board according to claim 1, wherein after the wiring pattern is formed, the wiring pattern and the ceramic green sheet are simultaneously fired to manufacture a ceramic circuit board. 2. A multilayer ceramic circuit board is manufactured by forming the wiring patterns on the surfaces of a plurality of ceramic green sheets, then laminating a plurality of ceramic green sheets and simultaneously firing them. A method for manufacturing a ceramic circuit board according to any one of claims 1 to 3.

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