JP2007287974A - Manufacturing method of circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a circuit board capable of appropriately suppressing the disconnection and/or the short circuit in an electrode pattern even when the cross-section or the pitch of the electrode pattern formed in a ceramic green sheet is made small. <P>SOLUTION: As a first organic binder contained in the ceramic green sheet 3 and a second organic binder contained in the electrode pattern 2, organic binders different from each other are selected from ethyl cellulose, butyral resin, and acrylic resin. Thus, the diffusion of the electrode pattern 2 into the ceramic green sheet 3 can appropriately be suppressed. Therefore, the circuit board excellent in electrical characteristics wherein the disconnection and/or the short circuit will not occur can be manufactured even when the cross-section and the pitch of the electrode pattern 2 are made small and the circuit board is miniaturized. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In particular, the present invention provides a circuit board manufacturing method capable of appropriately suppressing disconnection and short-circuiting of the electrode pattern even when the cross-section of the electrode pattern formed on the ceramic green sheet is reduced or the pitch is reduced. About.

  The following Patent Documents 1 and 2 each disclose an invention relating to a multilayer ceramic circuit board.

  The multilayer ceramic circuit board is formed by forming an electrode pattern on a ceramic green sheet, laminating a plurality of the ceramic green sheets, and firing the ceramic green sheet and the electrode pattern.

  The ceramic green sheet and the electrode pattern each contain an organic binder.

The following Patent Document 1 discloses a specific material of the organic binder contained in the ceramic green sheet. On the other hand, Patent Document 2 discloses a specific material of an organic binder contained in the electrode pattern. As described above, Patent Documents 1 and 2 describe only one organic binder of the ceramic green sheet and the electrode pattern, but usually the same organic binder is used for the ceramic green sheet and the electrode pattern. It had been.
Japanese Unexamined Patent Publication No. 5-55755 JP 2004-186339 A

  However, when the same organic binder is used for the ceramic green sheet and the electrode pattern, the electrode pattern diffuses into the ceramic green sheet and the electrode pattern is disconnected.

  The above problem can be alleviated to some extent by increasing the width and thickness of the electrode pattern to increase the cross section of the electrode pattern. However, when the pitch between the electrode patterns is narrowed, the electrode patterns are easily short-circuited due to the diffusion phenomenon described above.

  Therefore, conventionally, it has been required to increase the pitch between the electrode patterns while enlarging the cross section of the electrode patterns, which hinders the miniaturization of the multilayer ceramic circuit board.

  Therefore, the present invention is to solve the above-described conventional problems, and in particular, even if the cross-section of the electrode pattern formed on the ceramic green sheet is reduced or the pitch is reduced, the electrode pattern is disconnected or short-circuited. It aims at providing the manufacturing method of the circuit board which can be suppressed appropriately.

The present invention relates to a method of manufacturing a circuit board formed by firing an electrode pattern on a ceramic green sheet,
The first organic binder contained in the ceramic green sheet and the second organic binder contained in the electrode pattern are selected from different organic binders from ethyl cellulose, butyral resin, and acrylic resin. To do.

  Thereby, it can suppress appropriately that the said electrode pattern diffuses in the said ceramic green sheet. Therefore, even if the cross section of the electrode pattern is small and the circuit board is downsized by narrowing the pitch between the electrode patterns, the circuit board having excellent electrical characteristics that does not cause disconnection or short circuit can be manufactured.

  In the present invention, it is preferable to select a butyral resin as the first organic binder and select ethyl cellulose as the second organic binder. Alternatively, in the present invention, it is preferable to select an acrylic resin as the first organic binder and select ethyl cellulose as the second organic binder. According to an experiment described later, it has been proved that the disconnection can be more appropriately suppressed by selecting the material described above even if the width of the electrode pattern is reduced.

In the present invention,
(A) forming the electrode pattern on a transfer plate having a planarized surface;
(B) forming the ceramic green sheet on the electrode pattern and the transfer plate;
(C) peeling the transfer plate and transferring the electrode pattern to the ceramic green sheet;
(D) a step of laminating a plurality of ceramic green sheets formed by the steps (a) to (c);
It is preferable to have. As a result, the electrode pattern and the ceramic green sheet can be formed on the same flat surface, and the flatness of the circuit board surface can be improved even if a plurality of ceramic green sheets from which the transfer plate has been peeled are laminated.

  In the present invention, it is preferable that the ceramic green sheet is formed by a doctor blade method in the step (b). As a result, the surface of the ceramic green sheet opposite to the surface on which the electrode pattern is exposed can be appropriately flattened. That is, according to the present invention, both sides of the ceramic green sheet can be appropriately flattened, and therefore the flatness degree of the circuit board surface can be appropriately improved.

  In the present invention, the transfer plate is preferably formed of any one of polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyethylene naphthalate (PEN), and fluororesin. Thereby, the mechanical strength and weather resistance of the transfer plate can be improved.

  In the present invention, it is preferable to perform the step (a) after coating the surface of the transfer plate with a wet tension of 20 to 50 mN / m. Thereby, the wettability between the transfer plate and the electrode pattern and between the transfer plate and the ceramic green sheet can be improved, and the electrode pattern can be formed in a predetermined pattern with high accuracy. The ceramic green sheet can be appropriately formed on the entire surface of the transfer plate. Moreover, peeling in a post process can be performed easily.

  In the present invention, the electrode pattern is preferably formed by any one of screen printing, plating, or ink jet drawing. The electrode pattern can be formed in a predetermined shape appropriately and inexpensively.

  In the present invention, different organic binders are selected from ethyl cellulose, butyral resin, and acrylic resin for the first organic binder contained in the ceramic green sheet and the second organic binder contained in the electrode pattern.

  Thereby, it can suppress appropriately that the said electrode pattern diffuses in the said ceramic green sheet. Therefore, even if the cross section of the electrode pattern is small and the circuit board is downsized by narrowing the pitch between the electrode patterns, the circuit board having excellent electrical characteristics that does not cause disconnection or short circuit can be manufactured.

  FIG. 1 to FIG. 6 are process diagrams (partial cross-sectional views) showing a method of manufacturing a low temperature co-fired ceramic substrate (LTCC) in the present embodiment.

  In the process shown in FIG. 1, an electrode pattern 2 is formed on a transfer plate 1 having a flat surface. It is preferable that the transfer plate 1 is a flexible film because the transfer plate 1 is easily peeled off in a subsequent step.

  In the present embodiment, the transfer plate 1 is preferably formed of any one of polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyethylene naphthalate (PEN), and fluororesin. Thereby, the mechanical strength and weather resistance of the transfer plate 1 can be improved. The transfer plate 1 is preferably formed of a PET film because the transfer plate 1 can be manufactured at low cost.

  In the step shown in FIG. 1, before forming the electrode pattern 2 on the transfer plate 1, it is preferable to apply a coating having a wetting tension of 20 to 50 mN / m on the surface of the transfer plate 1 with silicon or the like. As a result, the wettability of the surface of the transfer plate 1 can be improved, the electrode pattern 2 can be formed in a predetermined shape with high accuracy, and the ceramic green sheet 3 formed in a subsequent process can be formed on the entire surface of the transfer plate 1. It can be formed appropriately. Moreover, peeling in a later process can be easily performed.

  The electrode pattern 2 shown in FIG. 1 is formed of a conductive paste having conductive particles, a glass composition, and an organic vehicle. The conductive particles are preferably selected from at least one of Ag particles, Ag—Pt alloy particles, and Ag—Pd alloy particles.

It is preferable to use a B ₂ O ₃ —CaO—SiO ₂ —Al ₂ O ₃ system for the glass composition because it is suitable for high-temperature firing. The composition ratio a of B ₂ O ₃ is 20 to 30% by mass, the composition ratio b of CaO is 10 to 55% by mass, the composition ratio c of SiO ₂ is 35 to 70% by mass, and the composition ratio of Al ₂ O ₃ d is preferably 5 to 30% by mass (provided that the compositional ratio a + b + c + d ≦ 100% by mass is satisfied). The glass composition may include at least one of Na ₂ O, K ₂ O, MgO, and ZnO as an excess composition, and the composition ratio e of the excess composition is in the range of 0 to 10% by mass. However, it is preferable that the composition ratio a + b + c + d + e = 100 mass% is satisfied.

  The organic vehicle includes a second organic binder and an organic solvent. As the organic solvent, at least one selected from terpineol, ethanol, butyl carbitol acetate and the like is selected.

  In the present embodiment, the second organic binder is selected from ethyl cellulose, butyral resin, and acrylic resin.

  An example of the content of each component contained in the electrode pattern 2 is shown. For example, in the total solid component, the content X of the second organic binder is 0.5 to 4% by mass, the content Y of the glass composition is 0.5 to 4% by mass, and the rest (100% by mass) -XY) is defined as the content of the conductive particles. Moreover, when the said electroconductive particle is Ag- (alpha) ((alpha) is Pt, Pd, etc.), content (alpha) of alpha shall be 0.1-0.5 mass% in a total solid component. Therefore, in such a case, the content of Ag is 100-XYZ (mass%).

  Further, a dispersant, a surfactant, a plasticizer, or the like may be added as appropriate to the electrode pattern 2.

  In the present embodiment, the electrode pattern 2 is preferably formed on the transfer plate 1 by any one of screen printing, plating, or ink jet drawing. The electrode pattern 2 can be formed in a predetermined shape appropriately and inexpensively. Of these, it is particularly preferable to form the electrode pattern 2 by screen printing because it can be more easily formed.

  After the electrode pattern 2 is formed, a drying process is performed on the electrode pattern 2. At least a part of the organic solvent is removed by this drying step.

  Next, in the step shown in FIG. 2, a ceramic green sheet 3 is formed on the electrode pattern 2 and the transfer plate 1.

  In the present embodiment, the ceramic green sheet 3 includes a glass composition, a ceramic powder, and an organic vehicle.

For the glass composition, a B ₂ O ₃ —CaO—SiO ₂ —Al ₂ O ₃ system is preferably used in the same manner as the electrode pattern 2. The composition ratio of each component in the glass composition is also as described above.

Al ₂ O ₃ is used for the ceramic powder. Also, TiO ₂ powder and Ba-Nd-TiO based powder, may be a high dielectric constant ceramic, such as Na-La-TiO based powder.

  The organic vehicle includes a first organic binder and an organic solvent. The organic solvent is at least one selected from terpineol, ethanol, butyl carbitol acetate and the like.

  The first organic binder is selected from ethyl cellulose, butyral resin, and acrylic resin as in the case of the second organic binder contained in the electrode pattern 2, and at this time, the first organic binder is selected. Different materials are selected for the second organic binder. That is, for example, ethyl cellulose is not selected for both the first organic binder and the second organic binder.

  As described above, the characteristic part of this embodiment is that different materials are selected from ethyl cellulose, butyral resin, and acrylic resin for the first organic binder and the second organic binder.

  Accordingly, when the electrode pattern 2 and the ceramic green sheet 3 are formed on the transfer plate 1 in the steps of FIGS. 1 and 2, it is appropriate that the electrode pattern 2 diffuses into the ceramic green sheet 3. Can be prevented.

  According to the experimental results described later, it is preferable to select butyral resin as the first organic binder and ethyl cellulose as the second organic binder. Alternatively, it is preferable that an acrylic resin is selected as the first organic binder and ethyl cellulose is selected as the second organic binder. Thereby, the diffusion of the electrode pattern 2 into the ceramic green sheet 3 can be prevented more appropriately.

  Therefore, even if the width of the electrode pattern 2 is narrowed or the thickness of the electrode pattern 2 is reduced to reduce the cross section of the electrode pattern 2, the disconnection of the electrode pattern 2 can be effectively prevented. Moreover, even if the pitch between the electrode patterns 2 is reduced, a short circuit between the electrode patterns 2 can be effectively prevented.

  As described above, in this embodiment, even if the electrode pattern 2 is thinned or the pitch is narrowed as described above, the low temperature fired multilayer ceramic substrate is miniaturized, and thus the low temperature excellent in electrical characteristics that does not cause disconnection or short circuit. A fired multilayer ceramic substrate can be manufactured.

  In the present embodiment, it is preferable to form the ceramic green sheet 3 by a doctor blade method as shown in FIG. As shown in FIG. 2, since there is a step between the transfer plate 1 and the electrode pattern 2, there are irregularities on the formation surface of the ceramic green sheet 3. However, in the doctor blade method used in the present embodiment, the ceramic green sheet 3 can be formed while maintaining a constant distance between the transfer plate 1 and the blade 4 as shown in FIG. Even if the formation surface of the sheet 3 is uneven, the surface 3a of the ceramic green sheet 3 can be formed on a flattened surface as shown in FIG.

  After the ceramic green sheet 3 is formed, the ceramic green sheet 3 is subjected to a drying process. Thereby, at least a part of the organic solvent contained in the ceramic green sheet 3 is removed.

  Next, if necessary, a via hole (not shown) is formed in the ceramic green sheet 3, and a conductive paste is filled in the via hole and dried. Here, an organic binder is also contained in the conductor paste filled in the via hole. The organic binder contained in the conductor paste includes ethyl cellulose, butyral resin, and acrylic resin, and the ceramic green sheet 3 includes the first binder. It is preferable to use a material different from the organic binder of 1.

Further, if necessary, a resistor pattern (not shown) is formed by screen printing or the like during the process of FIG. In such a case, the organic binder contained in the resistor pattern may be made of a material different from that of the first organic binder contained in the ceramic green sheet 3 from ethyl cellulose, butyral resin, and acrylic resin. preferable. The resistor pattern includes resistor particles, a glass composition, and an organic vehicle. The glass composition and the organic solvent contained in the organic vehicle are selected from the materials used for the electrode pattern 2. For example, RuO ₂ and Ru ₂ Nd ₂ O ₇ are used as the resistance particles.

  Next, in the step shown in FIG. 4, the ceramic green sheet 3 is cut into a predetermined size. The cutting process to the predetermined size may be performed before forming the via hole.

  A plurality of ceramic green sheets 3 with transfer plates 1 having predetermined electrode patterns 2 and the like are formed by the steps shown in FIGS.

  Next, in the step shown in FIG. 5, the transfer plate 1 is peeled from the ceramic green sheet 3. At this time, the electrode pattern 2 is not peeled off together with the transfer plate 1 but transferred to the ceramic green sheet 3. When the resistor pattern is provided, the resistor pattern is not peeled off together with the transfer plate 1 and is transferred to the ceramic green sheet 3.

  In the present embodiment, as described with reference to FIG. 1, the surface of the transfer plate 1 is a flattened surface, so that the contact surface 2 a of the electrode pattern 2 in contact with the transfer plate 1 and the contact of the ceramic green sheet 3. The surface 3b is formed of the same flat surface, and when the transfer plate 1 is peeled off, the contact surface (exposed surface) 2a of the electrode pattern 2 and the contact surface 3b of the ceramic green sheet 3 are the same flat. Appears as a chemical surface.

  Then, as shown in FIG. 5, for example, a flattened surface 3 a (expressed as “surface 3 a” in FIG. 3) on the side where the electrode pattern 2 of the ceramic green sheet 3 is not formed is placed on the support 5. .

  It should be noted that which surface 3a, 3b of the ceramic green sheet 3 is set on the support 5 is arbitrary.

  Alternatively, the ceramic green sheet 3 may be placed on the support 5 with the transfer plate 1 attached, and then the transfer plate 1 may be peeled off.

  A plurality of ceramic green sheets 3 from which the transfer plate 1 is peeled and the electrode pattern 2 is transferred are laminated on the support 5 to form a laminate 6 as shown in FIG. Bake. As a result, the electrode pattern 2 (in FIG. 6, only some of the electrode patterns 2 are labeled), the ceramic green sheet 3 (and the resistor pattern and via-hole conductor portion 7 (see FIG. 6). 6))) can be fired simultaneously. The firing temperature is, for example, 800 to 1000 ° C.

  In the present embodiment, when the ceramic green sheets 3 are stacked, the both surfaces 3a and 3b of the ceramic green sheets 3 are flat surfaces, so that a plurality of ceramic green sheets 3 can be stacked without any gaps. It is possible to appropriately improve the flatness of the surface of the low-temperature fired ceramic substrate obtained by laminating and firing.

  In addition, this embodiment may be used for the manufacturing method of a high temperature firing ceramic substrate (High Temperature Co-fired Ceramic substrate) and others.

  Each sample shown in Table 1 was formed during the experiment.

  The contents in each sample are shown below. In addition, content is the quantity which occupies in all the solid components in each of an electrode pattern and a ceramic green sheet.

Example 1
Content of ethyl cellulose in electrode pattern; 2% by mass
Content of Ag powder in the electrode pattern; 96% by mass
Content of the glass composition which occupies in an electrode pattern; 2 mass%
Content of butyral resin in the ceramic green sheet: 12% by mass
Content of Al ₂ O _{3 in} the ceramic green sheet; 42% by mass
Content of glass composition in ceramic green sheet; 46% by mass

(Example 2)
Content of ethyl cellulose in electrode pattern; 2% by mass
Content of Ag powder in the electrode pattern; 96% by mass
Content of the glass composition which occupies in an electrode pattern; 2 mass%
Content of acrylic resin in the ceramic green sheet: 12% by mass
Content of Al ₂ O _{3 in} the ceramic green sheet; 42% by mass
Content of glass composition in ceramic green sheet; 46% by mass

(Example 3)
Content of butyral resin in the electrode pattern; 2% by mass
Content of Ag powder in the electrode pattern; 96% by mass
Content of the glass composition which occupies in an electrode pattern; 2 mass%
Content of acrylic resin in the ceramic green sheet: 12% by mass
Content of Al ₂ O _{3 in} the ceramic green sheet; 42% by mass
Content of glass composition in ceramic green sheet; 46% by mass

Example 4
Content of acrylic resin in electrode pattern; 2% by mass
Content of Ag powder in the electrode pattern; 96% by mass
Content of the glass composition which occupies in an electrode pattern; 2 mass%
Content of butyral resin in the ceramic green sheet: 12% by mass
Content of Al ₂ O _{3 in} the ceramic green sheet; 42% by mass
Content of glass composition in ceramic green sheet; 46% by mass

(Comparative Example 1)
Content of ethyl cellulose in electrode pattern; 2% by mass
Content of Ag powder in the electrode pattern; 96% by mass
Content of the glass composition which occupies in an electrode pattern; 2 mass%
Content of ethyl cellulose in the ceramic green sheet: 12% by mass
Content of Al ₂ O _{3 in} the ceramic green sheet; 42% by mass
Content of glass composition in ceramic green sheet; 46% by mass

(Comparative Example 2)
Content of butyral resin in the electrode pattern; 2% by mass
Content of Ag powder in the electrode pattern; 96% by mass
Content of the glass composition which occupies in an electrode pattern; 2 mass%
Content of butyral resin in the ceramic green sheet: 12% by mass
Content of Al ₂ O _{3 in} the ceramic green sheet; 42% by mass
Content of glass composition in ceramic green sheet; 46% by mass

(Comparative Example 3)
Content of acrylic resin in electrode pattern; 2% by mass
Content of Ag powder in the electrode pattern; 96% by mass
Content of the glass composition which occupies in an electrode pattern; 2 mass%
Content of acrylic resin in the ceramic green sheet: 12% by mass
Content of Al ₂ O _{3 in} the ceramic green sheet; 42% by mass
Content of glass composition in ceramic green sheet; 46% by mass

  In the experiment, a plurality of electrode patterns having a width of 60 μm, 50 μm, 40 μm, and 30 μm were formed on a PET film (transfer plate) by screen printing on each sample, and then ceramic green sheets of each sample were formed by a doctor blade method. Formed and fired at 860 ° C. And the said PET film was peeled, the exposed surface of the said electrode pattern exposed by it was observed with the optical microscope, and the disconnection rate was measured.

  As shown in Table 1, in Examples 1 to 4 in which the organic binder is different between the electrode pattern and the ceramic green sheet, the non-disconnection rate is 100% (that is, all the samples are disconnected) when the electrode pattern width is 50 μm or more. I couldn't do it.

  On the other hand, in Comparative Examples 1 to 3 in which the organic binder was the same between the electrode pattern and the ceramic green sheet, it was found that the disconnection rate was lower than in Examples 1 to 4.

  As shown in Table 1, ethyl cellulose is used as the organic binder (second organic binder) used in the electrode pattern, and butyral resin is used as the organic binder (first organic binder) used in the ceramic green sheet. Example 1 Using ethyl cellulose as the organic binder (second organic binder) used in the electrode pattern and using an acrylic resin as the organic binder (first organic binder) used in the ceramic green sheet Example 2 showed a higher non-breaking rate than both Examples 3 and 4 (a very high unbroken rate was obtained even when the electrode pattern width was 30 μm), and was found to be more suitable. .

One process drawing (partial sectional view) showing a method for producing a low-temperature fired ceramic substrate in the present embodiment, 1 process drawing (partial sectional view) performed after FIG. One process diagram (partial sectional view) performed after FIG. One process diagram (partial sectional view) performed after FIG. One process diagram (partial sectional view) performed after FIG. One process diagram (partial sectional view) performed after FIG.

Explanation of symbols

1 Transfer Plate 2 Electrode Pattern 3 Ceramic Green Sheet 4 Blade 5 Support 6 Laminate

Claims (8)

In the manufacturing method of the circuit board formed by firing after forming the electrode pattern on the ceramic green sheet,
The first organic binder contained in the ceramic green sheet and the second organic binder contained in the electrode pattern are selected from different organic binders from ethyl cellulose, butyral resin, and acrylic resin. Circuit board manufacturing method.   The circuit board manufacturing method according to claim 1, wherein a butyral resin is selected as the first organic binder, and ethyl cellulose is selected as the second organic binder.   2. The method of manufacturing a circuit board according to claim 1, wherein an acrylic resin is selected as the first organic binder, and ethyl cellulose is selected as the second organic binder. (A) forming the electrode pattern on a transfer plate having a planarized surface;
(B) forming the ceramic green sheet on the electrode pattern and the transfer plate;
(C) peeling the transfer plate and transferring the electrode pattern to the ceramic green sheet;
(D) a step of laminating a plurality of the ceramic green sheets formed by the steps (a) to (c);
The method for manufacturing a circuit board according to claim 1, comprising:   The method for manufacturing a circuit board according to claim 4, wherein in the step (b), the ceramic green sheet is formed by a doctor blade method.   6. The method for manufacturing a circuit board according to claim 4, wherein the transfer plate is formed of any one of polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyethylene naphthalate (PEN), and fluororesin.   The method for manufacturing a circuit board according to any one of claims 4 to 6, wherein the step (a) is performed after coating the surface of the transfer plate with a wet tension of 20 to 50 mN / m.   The method for manufacturing a circuit board according to claim 1, wherein the electrode pattern is formed by any one of screen printing, plating, and an ink jet drawing method.

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