JP3152090B2 - Manufacturing method of ceramic wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic wiring board used as, for example, an electronic component.

[0002]

2. Description of the Related Art Generally, a ceramic wiring board (a printed wiring board using a ceramic substrate) has a strong adhesion between a ceramic substrate and a metallized layer (conductive layer) formed on the surface thereof, and has a low sheet resistance of the conductive layer. Is required.
In the case of a metallization method using a metal paste, in order to strengthen the adhesion of the conductor layer, it is common to include a glass that is melted at the firing temperature and fused to the ceramic substrate in the metal paste. In this case, there is a disadvantage that the sheet resistance becomes higher than that of the pure metal by the content of the glass component.

[0003] On the other hand, a conductor layer obtained by a vapor phase method such as a plating method, a sputtering method, or a vapor deposition method has a low impurity content, and thus has a sheet resistance substantially equal to that of a pure metal. However, the adhesion between the conductor layer and the ceramic substrate in this case is generally low. Therefore, conventionally, as a method of improving the adhesion of the conductor layer, before the metallizing treatment, the ceramic substrate is immersed in a high-temperature solution such as hydrofluoric acid, phosphoric acid, sodium hydroxide or the like by a chemical etching method or the like. In general, a method is used in which the surface is roughened to obtain an adhesive force with a ceramic substrate by a so-called anchor effect.

However, roughening the surface of such a ceramic substrate has the problem of deteriorating high-frequency characteristics. Therefore, the development of a metallization method capable of obtaining a metallized layer that adheres firmly to a ceramic substrate surface as smooth as possible. Is desired. Therefore, as a method of forming a conductor layer having excellent adhesion without roughening, various studies have been made on pretreatment of electroless copper plating, formation of an underlayer, and the like, for example, Japanese Patent Publication No. 63-4336. And Japanese Patent Publication No. 4-82043 and Japanese Patent Publication No. 3-69191.

Japanese Patent Publication No. 63-4336 discloses Cu, Z
A paste containing at least one component of a compound of n, Cd, Pb or Bi is applied to a ceramic substrate, and thereafter,
In a non-oxidizing atmosphere, heat treatment is performed at a temperature within the range of 350 to 900 ° C., and Cu, Zn, Cd, Pb, Bi
And then subjecting the surface of the metal or alloy metal to at least one of Pd or Pt in a solution containing at least one ion of Pd or Pt in a solution containing at least one ion of Pd or Pt. And a method of manufacturing a ceramic electronic component in which a nickel, cobalt or copper metal electrode is formed by electroless plating. However, in this case, a heat treatment in a non-oxidizing atmosphere is required, and therefore, there is a problem that a manufacturing apparatus and a manufacturing process are complicated, and further, by a substitution process of substituting at least one of Pd and Pt, It is estimated that the adhesion between the underlayer and the ceramic substrate is impaired,
As seen from the example of JP-B-63-4336, the maximum tensile strength is 2.75 kg / 5φ area (0.53
kg / 4 mm ² ), and in recent years, further improvement in adhesion has been demanded.

Japanese Patent Publication No. 4-82043 discloses that a metal thin film is formed on a ceramic surface by an electroless plating method.
Heat treatment at 200 ° C. to form a chemical bond between the ceramic and the metal thin film, then chemically remove the metal thin film, and then metallize the ceramic surface by electroless plating Is described. However, in the case of this method, the adhesion tends to largely depend on the thickness of the formed metal thin film, and there is a problem that it is difficult to obtain a stable adhesion.

In Japanese Patent Publication No. 3-69191, an alumina substrate is subjected to electroless copper plating.
A method is described in which a heat treatment is performed in an oxidizing atmosphere at a temperature of 200 ° C., a treatment is performed in a reducing atmosphere at a temperature of 200 to 900 ° C., an electroless copper plating is performed, and then an electrolytic copper plating is performed. However, in the case of this method, it is presumed that the process is performed in a reducing atmosphere, which complicates the manufacturing apparatus and the manufacturing process, and that the reduction process is performed at a high temperature of 200 to 900 ° C. In addition, there has been a problem that the adhesion between the underlayer after the reduction treatment and the electroless copper plating film formed thereon is insufficient.

[0008]

In view of the above circumstances,
An object of the present invention is to develop a method for manufacturing a ceramic wiring board which can form a conductor layer having strong adhesion on a smooth ceramic substrate surface without requiring a special atmosphere such as a reducing atmosphere.

[0009]

According to a first aspect of the present invention, there is provided a method of manufacturing a ceramic wiring board, comprising forming a base layer containing vanadium and copper on a surface of a ceramic substrate, and then forming an oxidizing atmosphere on the surface. Heat treatment at 450 to 620 ° C. in water, followed by reduction treatment by dipping in a reducing solution, and then copper metallization to form a copper film having a copper content of 99% by weight or more.

According to a second aspect of the present invention, in the method of the first aspect, the copper metallization method is an electroless plating method, an electrolytic plating method, or a sputtering method. It is characterized by.

According to a third aspect of the present invention, there is provided a method of manufacturing a ceramic wiring board according to the first or second aspect, wherein the surface of the ceramic substrate is coated with a material containing vanadium and copper. , A base layer containing vanadium and copper.

According to a fourth aspect of the present invention, in the method for manufacturing a ceramic wiring board according to the first or second aspect, a copper-containing layer is formed on a surface of the ceramic substrate, and then the copper-containing layer is formed. By forming a vanadium-containing layer on the containing layer, an underlayer containing vanadium and copper is formed.

According to a fifth aspect of the present invention, in the method for manufacturing a ceramic wiring board according to the first or second aspect, a vanadium-containing layer is formed on a surface of the ceramic substrate, and then the vanadium is formed. It is characterized in that an underlayer containing vanadium and copper is formed by forming a copper-containing layer on the containing layer.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a ceramic wiring board according to any one of the first to fifth aspects, wherein the underlayer containing vanadium and copper is formed. The copper component is a metal copper powder treated with a liquid containing an ethylenediamine-based chelating agent.

According to a seventh aspect of the invention, there is provided a method of manufacturing a ceramic wiring board according to any one of the first to fifth aspects, wherein the underlayer containing vanadium and copper is formed. The copper component to be formed is a metal copper powder precipitated from an electroless plating solution containing an ethylenediamine-based chelating agent.

Hereinafter, the present invention will be described in detail. Examples of the material of the ceramic substrate used in the present invention include, for example, oxide-based ceramics such as alumina, zirconia, cordierite, and barium titanate; nitride-based ceramics such as aluminum nitride and silicon nitride; and carbide-based materials such as silicon carbide. And the like are not particularly limited.

An underlayer containing vanadium and copper is formed on the surface of the above-mentioned ceramic substrate. For example, the following three types of methods can be used. For example, a method of coating a material containing vanadium and copper, such as a mixed resinate paste obtained by mixing vanadium resinate paste and copper resinate paste, to form a layer in which vanadium and copper are mixed in a single step. A method of forming an underlayer containing vanadium and copper by forming a copper-containing layer and then forming a vanadium-containing layer on the copper-containing layer. A method for forming an underlayer containing vanadium and copper by forming a vanadium-containing layer and then forming a copper-containing layer on the vanadium-containing layer.

The means for forming the copper-containing layer, the vanadium-containing layer, and the layer containing vanadium and copper for forming the underlayer containing vanadium and copper are not particularly limited. , A sputtering method, a metal paste method, an organic metal resinate (or a paste thereof) method, or the like.

The thicknesses of the copper-containing layer, the vanadium-containing layer, and the layer in which vanadium and copper are mixed are not particularly limited.
It is preferable that the thickness be in the range of 3.0 μm so that the conductor layer formed by the final metallization has a stable adhesion.

After forming an underlayer containing vanadium and copper on the surface of the ceramic substrate as described above, heat treatment is performed to oxidize vanadium and copper. In this step, vanadium oxide is diffused, so that copper oxide is generated on the surface of the underlayer containing vanadium and copper. It is important that this heat treatment is performed at a temperature of 450 to 620 ° C. in an oxidizing atmosphere such as the air.
At a temperature lower than 450 ° C., the adhesion of the copper film formed by the final metallization to the smooth ceramic substrate surface becomes insufficient. At a temperature higher than 620 ° C., vanadium oxide formed during the heat treatment is scattered, This is probably because the amount of vanadium contributing to the improvement of the adhesion cannot be ensured, but the adhesion is still insufficient.

After the heat treatment, the ceramic substrate is immersed in a reducing solution to perform a reduction treatment. By this step, the copper oxide present on the surface of the layer containing vanadium and copper is easily reduced to metallic copper. This copper metal becomes a catalyst core for electroless plating when the subsequent copper metallization method is an electroless plating method, and a desired electroless copper plating can be performed without a catalyst application step. The reducing solution is not particularly limited as long as it can reduce copper oxide, and for example, a borohydride salt solution, a hypophosphite solution, a dimethylamine borane solution, or the like may be used. it can. The temperature of the reducing solution is not particularly limited, but it is preferable to perform the reduction at a temperature higher than room temperature in order to shorten the time of the reduction treatment.

Next, the ceramic substrate that has been subjected to the above reduction treatment is subjected to copper metallization by a method such as electroless plating, electrolytic plating, or sputtering to form a copper film having a copper content of 99% by weight or more, thereby forming a conductor layer. Obtain a ceramic wiring board. Note that a conductor layer may be formed by further forming a metal layer on the copper film by a method such as electroplating.

Further, in the present invention, an electroless plating solution containing an ethylenediamine-based chelating agent or a metal copper powder treated with an ethylenediamine-based chelating agent as a copper component for forming the above-mentioned underlayer containing vanadium and copper. The use of metallic copper powder precipitated from the above is preferred because the adhesion of the finally obtained conductor layer is further increased. The ethylenediamine-based chelating agent in the present invention refers to an ethylenediamine-based chemical substance capable of forming a copper chelate compound. The ethylenediamine-based chelating agent is not particularly limited, but ethylenediaminetetraacetic acid (hereinafter, referred to as EDTA) Abbreviated), ethylenediamine-based chelate reagents such as ethylenediaminediacetate, and ethylenediamine-based chelate compounds such as disodium ethylenediaminetetraacetate. The method of treating with an ethylenediamine-based chelating agent is not particularly limited, and examples thereof include dipping, coating, and spraying.

[0024]

In the method of manufacturing a ceramic wiring board according to the present invention, an underlayer containing vanadium and copper is formed on the surface of a ceramic substrate, and then the substrate is formed in an oxidizing atmosphere at 450 to 620.
The heat treatment is carried out at a temperature of ° C. This heat treatment forms oxides of vanadium oxide and copper. Vanadium oxide has good wettability to a ceramic substrate and diffuses to act as an adhesive to the ceramic substrate. Further, since the oxides of vanadium oxide and copper form a compound, the adhesion between them becomes strong. Further, since the diffusion rate of vanadium oxide to the ceramic substrate side is higher than that of copper oxide, the underlayer containing vanadium and copper is formed by the above-described method.
Whichever method is used, a copper oxide layer appears on the surface of the layer containing vanadium and copper after the heat treatment.

In the present invention, after the heat treatment, the substrate is immersed in a reducing solution, subjected to a reduction treatment, and then subjected to copper metallization. Therefore, the copper which appears on the surface of the underlayer containing vanadium and copper after the heat treatment is formed. Is converted to metallic copper by the reduction treatment. This metallic copper firmly adheres to the copper film formed by the copper metallization in the next step. This metal copper can act as a plating catalyst in electroless copper plating when the copper metallization method is an electroless plating method.

Further, in the present invention, the copper component forming the underlayer containing vanadium and copper is deposited from metal copper powder treated with an ethylenediamine-based chelating agent or from an electroless plating solution containing an ethylenediamine-based chelating agent. Metal copper powder, because a copper chelate compound is formed on the surface of the metal copper powder, the copper oxide when heat-treated at 450 to 620 ° C. in an oxidizing atmosphere is unlikely to become complete CuO As a result, the copper oxide layer can be easily changed to metallic copper in the next reduction treatment. Therefore, the metal copper obtained by the reduction treatment can be firmly bonded to the copper film formed by the copper metallization in the next step, and the adhesion of the conductor layer can be improved.

[0027]

EXAMPLES Specific examples of the present invention and comparative examples are shown below.

(1) An embodiment in which a base layer is formed by coating using a material containing both vanadium and copper metal components. (Examples 1 to 5) Vanadium resinate paste (manufactured by NE Chemcat, # 51-F, vanadium content 3) was applied to various ceramic substrate surfaces shown in Table 1 which were not subjected to surface roughening treatment. 9.9%) and 5 parts by weight of a copper resinate paste (manufactured by NE Chemcat, # 29-B, Cu content 6.4%). Forming and then 125
The resultant was dried at a temperature of 10 ° C. for 10 minutes to form an underlayer containing vanadium and copper. After that, the substrate is
C. for 1 hour in the air, and then subjected to a reduction treatment by immersion in an aqueous solution of sodium borohydride (pH 12.5) at 80.degree. C. for 5 minutes.

The substrate after the reduction treatment was subjected to electroless copper plating, and a copper plating film having a thickness of about 10 μm was formed on the circuit pattern to form a conductor layer, thereby obtaining a ceramic wiring board. The copper content of the copper plating film formed by the electroless copper plating was 99% by weight or more. The adhesive strength between the ceramic substrate and the conductor layer (including the underlayer containing vanadium and copper) in the obtained ceramic wiring board was measured. As shown in FIG. 1, the measurement of the adhesion of the conductor layer
The test was performed using a test piece in which a tin-plated copper wire 4 of mφ was joined by solder 3. The arrows in FIG. 1 indicate the tensile direction in the tensile test. Table 1 shows the measurement results of the obtained adhesion. The formation of the 2 mm square conductor layer was performed by an etching method.

From the results shown in Table 1, it can be seen that in Examples 1 to 5, good adhesion was obtained.

[0031]

[Table 1]

(2) An embodiment in which a copper-containing layer is formed, then a vanadium-containing layer is formed on the copper-containing layer, and an underlayer is formed. (Examples 6 to 15) After sensitizing the surfaces of various ceramic substrates shown in Table 2 not subjected to the surface roughening treatment by Pd nucleation, electroless copper plating was performed, and the results are shown in Table 2. A thick copper-containing layer was formed on the entire surface of the ceramic substrate. Then, vanadium resinate paste (manufactured by NE Chemcat Corporation,
# 51-F, vanadium content: 3.9%) was applied to the entire surface of the substrate by a screen printing method, and dried at 125 ° C. for 10 minutes to form a vanadium-containing layer.

Thereafter, the substrate was heat-treated at 550 ° C. for 1 hour in the air, and then immersed in an aqueous solution of sodium borohydride (pH 12.5) at 80 ° C. for 5 minutes to perform a reduction treatment. The substrate after the reduction treatment was subjected to electroless copper plating, and a copper plating film having a thickness of about 10 μm was thickened to form a conductor layer. The copper content of the copper plating film formed by the electroless copper plating was 99% by weight or more. With respect to the obtained substrate, the adhesion between the ceramic substrate and the conductor layer (including the underlayer containing vanadium and copper) was measured in the same manner as in Examples 1 to 5 above, and obtained. Table 2 shows the measurement results. Note that a ceramic wiring board can be obtained by forming a circuit on the obtained substrate.

From the results shown in Table 2, it can be seen that in Examples 6 to 15, good adhesion was obtained.

[0035]

[Table 2]

(3) An embodiment in which a vanadium-containing layer is formed, a copper-containing layer is formed on the vanadium-containing layer, and an underlayer is formed. (Examples 16 to 20) A vanadium resinate paste (manufactured by NE Chemcat, # 51-F, containing vanadium) was applied to the entire surface of the various ceramic substrates shown in Table 3 which had not been subjected to surface roughening treatment. (3.9%) was applied by a screen printing method and dried at 125 ° C. for 10 minutes to form a vanadium-containing layer.

Subsequently, a copper resinate paste (manufactured by NE Chemcat, # 29-B, Cu content 6.4)
%) Was applied on the entire surface of the substrate obtained above by a screen printing method, and dried at 125 ° C. for 10 minutes to form a copper-containing layer.

Thereafter, the substrate obtained above was heated at 550 ° C.
Heat treatment was performed for 1 hour in the air, and then reduction treatment was performed by immersion in an aqueous solution of sodium borohydride (pH 12.5) at 80 ° C. for 5 minutes. The substrate after the reduction treatment was subjected to electroless copper plating, and a copper plating film having a thickness of about 10 μm was thickened to form a conductor layer. The copper content of the copper plating film formed by the electroless copper plating was 99% by weight or more. With respect to the obtained substrate, the adhesion between the ceramic substrate and the conductor layer (including the layer containing vanadium and copper) was measured in the same manner as in Examples 1 to 5, and the obtained measurement was obtained. Table 3 shows the results. Note that a ceramic wiring board can be obtained by forming a circuit on the obtained substrate.

From the results in Table 3, it can be seen that Examples 16 to 20 were used.
It can be seen that good adhesion was obtained.

[0040]

[Table 3]

(4) Example and Comparative Example (Example 2) in which the heat treatment temperature was changed under the manufacturing conditions of Example 16 described above.
Examples 1 and 22 and Comparative Examples 1 and 2) Example 16 (heat treatment temperature of 550) except that the temperature condition for heat treatment in the air was changed to the condition shown in Table 4.
C), a ceramic substrate having a conductor layer formed thereon was obtained. With respect to the obtained ceramic substrate, the adhesion between the ceramic substrate and the conductor layer (including the layer containing vanadium and copper) was measured in the same manner as in Examples 1 to 5 above, and obtained. Table 4 shows the measurement results including the values of Example 16.

From the results shown in Table 4, the heat treatment temperature was 450-6.
It can be seen that good adhesion can be obtained in the range of 20 ° C. In the present invention, it is desirable to set an appropriate heat treatment time for each heat treatment temperature to be set.

[0043]

[Table 4]

(5) In the manufacturing conditions of Example 16 described above,
Examples in which the copper metallization method for the substrate after the reduction treatment was changed (Examples 23 and 24) As shown in Table 5, the copper metallization method for the substrate after the reduction treatment was as follows. In Example 24, a copper film having a thickness of about 10 μm was formed in the same manner as in Example 16 (the copper metallization method was an electroless plating method) except for the conditions performed by using the sputtering method. A conductor layer was formed. Each of the thick copper films had a copper content of 99% by weight or more. Then, the adhesion strength between the ceramic substrate and the conductor layer (including the underlayer containing vanadium and copper) on the substrate on which the obtained conductor layer is formed is determined in the same manner as in Examples 1 to 5. The measurement was carried out by the method, and the obtained measurement results are shown in Table 5.

From the results shown in Table 5, it can be seen that good adhesion can be obtained even when the copper metallization method is the electrolytic plating method or the sputtering method.

[0046]

[Table 5]

(6) Example in which metallic copper powder treated with an ethylenediamine-based chelating agent is used as a copper component for forming an underlayer containing vanadium and copper (Example 2)
5. Example 26) In Example 25, an alkaline saturated aqueous solution of disodium ethylenediaminetetraacetate (abbreviated as EDTA · 2Na) was prepared, and a metal copper powder having an average particle diameter of 1 μm was prepared using this EDTA ·
After immersion in a 2Na solution, stirring, filtration, and drying, a metal copper powder treated with an ethylenediamine-based chelating agent was prepared. Subsequently, 3 parts by weight of the treated metal copper powder and a vanadium resinate paste (N.
(E-Chemcat, # 51-F, vanadium content: 3.9%) in an amount of 7 parts by weight to prepare a mixed paste. Then, a ceramic wiring board was obtained in the same manner as in Example 1 except that this mixed paste was used instead of the mixed resinate paste in Example 1. The adhesion of the conductor layer in the obtained ceramic wiring board was measured by the same method as in the above-described Examples 1 to 5, and the obtained measurement was performed.
Table 6 shows the results .

In Example 26, sodium borohydride was added to an electroless copper plating solution containing EDTA,
The electroless copper plating solution was decomposed to deposit metallic copper powder. Next, 3 parts by weight of the obtained metal copper powder and a vanadium resinate paste (manufactured by NE Chemcat Corporation,
# 51-F, vanadium content: 3.9%) and 7 parts by weight to prepare a mixed paste. Then, a ceramic wiring board was obtained in the same manner as in Example 1 except that this mixed paste was used instead of the mixed resinate paste in Example 1. The adhesion of the conductor layer in the obtained ceramic wiring board was measured in the same manner as in Examples 1 to 5 above, and the obtained measurement results are shown in Table 6.

From the results in Table 6, it can be seen from Examples 25 and 2 that
6, it can be seen that even better adhesion was obtained as compared to Example 1.

[0050]

[Table 6]

[0051]

In the method for manufacturing a ceramic wiring board according to the first to fifth aspects of the present invention, an underlayer containing vanadium and copper is formed on the surface of the ceramic substrate, and then the substrate is heated to 450 to 620 ° C. in an oxidizing atmosphere. Heat treatment, then immersion in a reducing solution for reduction treatment, and then copper metallization.Therefore, a special atmosphere such as a reducing atmosphere is not required. A conductive layer having a stable and strong adhesion can be formed.

In the method for manufacturing a ceramic wiring board according to the second aspect of the present invention, the copper metallizing method is an electroless plating method .
In this case , the metallic copper on the underlayer generated by the reduction treatment can be used as a plating catalyst in the electroless copper plating, so that the effect of omitting the step of applying the plating catalyst is achieved.

In the method for manufacturing a ceramic wiring board according to the present invention, the copper component forming the underlayer containing vanadium and copper is a metal copper powder or ethylenediamine treated with an ethylenediamine-based chelating agent. Since it is metallic copper powder precipitated from an electroless plating solution containing a system chelating agent, a conductor layer having a stronger adhesion can be formed in addition to the above-described effects.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a method for measuring the adhesion between a ceramic substrate and a conductor layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic substrate 2 Conductor layer 3 Solder 4 Tin plating copper wire

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-51-75972 (JP, A) JP-A-55-115392 (JP, A) JP-A-61-107607 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H05K 3/18 H05K 3/38

Claims (7)

(57) [Claims] An underlayer containing vanadium and copper is formed on the surface of a ceramic substrate, and then heat-treated at 450 to 620 ° C. in an oxidizing atmosphere, and then immersed in a reducing solution. A copper film having a copper content of 99% by weight or more. 2. The method of copper metallization is an electroless plating method,
2. The method according to claim 1, wherein the method is an electrolytic plating method or a sputtering method. 3. The method according to claim 1, wherein the surface of the ceramic substrate is coated with a material containing vanadium and copper to form an underlayer containing vanadium and copper.
A method for manufacturing a ceramic wiring board according to claim 2. 4. An underlayer containing vanadium and copper is formed by forming a copper-containing layer on the surface of a ceramic substrate and then forming a vanadium-containing layer on the copper-containing layer. 3. The method for manufacturing a ceramic wiring board according to claim 1 or 2. 5. An underlayer containing vanadium and copper is formed by forming a vanadium-containing layer on the surface of a ceramic substrate, and then forming a copper-containing layer on the vanadium-containing layer. 3. The method for manufacturing a ceramic wiring board according to claim 1 or 2. 6. The copper component forming a base layer containing vanadium and copper is metallic copper powder treated with a liquid containing an ethylenediamine-based chelating agent.
A method for producing a ceramic wiring board according to any one of claims 1 to 5. 7. The copper component forming the underlayer containing vanadium and copper is metallic copper powder precipitated from an electroless plating solution containing an ethylenediamine-based chelating agent. The method for manufacturing a ceramic wiring board according to any one of the above.