JPH0632358B2 - Method for manufacturing ceramic circuit board with resistor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic circuit board with a resistor, and a method for manufacturing a ceramic circuit board on which a resistor is formed together with a normal conductor circuit for wiring. It is a thing.

[Conventional technology]

Conventionally, as a method of manufacturing a ceramic circuit board including a resistor, a precious metal paste containing Ag / Pd or the like as a main component, which becomes a conductor circuit, is printed on a sintered ceramic substrate by screen printing or the like, and RuO _{2 is used.} It is a general method to form a conductor circuit and a resistor at the same time by printing a frit-containing resistor paste containing as a main component by screen printing and firing it in an oxidizing atmosphere.

However, in the above method, migration is likely to occur and the wiring resistance is as high as 10 to 30 mΩ / □. Therefore, recently, as a method of improving the above method to prevent migration and reduce the wiring resistance and reduce the cost of the paste material, a base metal paste containing Cu or the like as a main component and LaB ₆ , SnO ₂ or the like are mainly used. A method of forming a conductor circuit and a resistor at the same time by combining resistor paste containing frit as a component and firing both in a nitrogen atmosphere has become popular.

However, even in the above method, since the conductor metal paste is screen-printed, it is difficult to form fine wiring of 100 μm or less, and since the paste contains glass, the solder adhesion is poor and defective products are likely to be produced. There is a problem that it is easy to cause a failure during use. In addition, the resistor paste needs to be fired in a nitrogen atmosphere, and the degree of perfection of the paste material is low. Therefore, in comparison with the conventional resistor paste for air firing, the performance is sufficiently comparable in all aspects. I can't say that.

On the other hand, as a method of forming a fine wiring circuit, a method of forming a conductor metal layer not containing glass on the surface of a ceramic substrate by a metallizing method and forming the circuit by using a photoengraving technique has been proposed. There is. However, this method has a limitation that firing must be performed in an inert or reducing atmosphere in order to prevent the conductor metal layer from being oxidized at a high temperature when firing the resistor paste.

Therefore, after a resistor paste for air firing containing RuO ₂ as a main component is printed and fired to form a resistor layer, a protective layer is formed on the resistor layer, and the surface of the ceramic substrate and the resistor layer are formed. The entire exposed area is simultaneously roughened with a strong acid,
Then, after conducting a catalyst / activation treatment, chemical plating or chemical plating and electroplating are performed to form a conductor metal layer,
A method of pattern-etching this conductor metal to form a conductor circuit has been proposed, and is disclosed in JP-A-61-185995.
It is disclosed in the publication.

Further, each of the above-mentioned prior arts is disclosed in JP-A-61-27.
Japanese Patent Application No. 61-35767 and Japanese Patent Application No. 63-62347 disclose the same technique as disclosed in Japanese Patent Application Laid-Open No. 0885 and Japanese Patent Application Laid-Open No. 61-194794.
Patent application has been made.

[Problems to be Solved by the Invention]

However, in the prior art disclosed in Japanese Patent Laid-Open No. 61-185995 mentioned above, in order to enhance the adhesion between the ceramic substrate and the conductor circuit or the resistor layer and the conductor circuit, the exposed portions of the ceramic substrate and the resistor layer are Since it is roughened with a strong acid, this roughening treatment attacks the resistor layer,
There is a problem that the performance quality of the resistor layer is adversely affected. In order to prevent such a problem, the roughening treatment should be suppressed to such an extent that the performance quality of the resistor layer is not affected, but then the adhesion between the conductor circuit and the ceramic substrate and resistor layer will be poor. It becomes a thing.

Therefore, an object of the present invention is to provide a ceramic circuit board with a resistor in the above-mentioned prior art, which can enhance the adhesion between the conductor circuit and the ceramic substrate and the resistor layer without adversely affecting the performance quality of the resistor layer. It is to provide a manufacturing method of.

[Means for Solving the Problems]

Among the inventions for solving the above problems, the invention according to claim 1 includes the following steps (1) to (3) in the manufacturing process.

(1) A step of forming a resistor layer on a ceramic substrate and forming a protective layer on the resistor layer.

(2) A step of forming a conductor metal layer corresponding to a predetermined circuit pattern on the surface of the ceramic substrate and the exposed portion of the resistor layer by a thin film forming means.

(3) A step of heating the ceramic substrate on which the conductor circuit is formed within a temperature range of 200 to 800 ° C. in a nitrogen atmosphere.

[Action]

According to the invention described in claim 1, the ceramic substrate on which the conductor circuit is formed is heat-treated, whereby the adhesion between the conductor circuit and the ceramic substrate and the resistor layer can be increased.

In particular, a conductor metal layer to be a conductor circuit is formed by a thin film forming means, and heat treatment is performed in a nitrogen atmosphere for 20 minutes.
By performing the treatment within the temperature range of 0 to 800 ° C., the adhesion between the conductor circuit and the ceramic substrate and the contact between the conductor circuit and the resistor layer can be achieved without impairing the characteristics of the antibody layer and the protective layer covering the antibody layer. Adhesion can be sufficiently enhanced.

This is because when the heat treatment is performed at an appropriate temperature within the above temperature range depending on the combination of materials such as the conductor metal layer and the resistor layer, the residual stress in the thin film formation of the conductor metal layer and the joint surface It is considered that the adhesion can be improved by the action such as eliminating the nonuniformity of the tissue structure.

However, if the heat treatment is performed in the atmosphere or the heating temperature is raised, the characteristics of the resistor layer and the protective layer are adversely affected. Specifically, when the resistor layer or the protective layer is heated in the atmosphere and at a high temperature, the resistor layer or the protective layer may be oxidized and the characteristics may be greatly changed, or may be melted and deformed in some cases. With this, the original functions of the resistor layer and the protective layer cannot be sufficiently exhibited. Since the resistor layer and the protective layer are usually formed by firing, adverse effects are unlikely to occur at a relatively low temperature of about the same as or slightly higher than the firing temperature. The regulation of such temperature range is effective. Further, in a nitrogen atmosphere, there is no concern that the resistor layer and the protective layer will be oxidized.

〔Example〕

FIG. 1 shows an example of a method of manufacturing a ceramic circuit board with a resistor according to the present invention by a process flow chart, and the explanation will be sequentially added according to the flow chart. Also, in FIG.
The cross-sectional structure of the manufactured ceramic circuit board with a resistor is shown.

[Step] A sintered ceramic substrate 1 is prepared. The material of the ceramic substrate 1 is alumina, fosterite, steatite, zirconia, mullite, cordierite, zircon,
Mainly used oxide-based ceramic materials such as titania,
Any ceramic material such as a carbide type or a nitride type can be used.

[Step] The surface of the ceramic substrate 1 is roughened if necessary. By this roughening treatment, the conductor metal layer 2 formed in a later step
It is possible to improve the adhesion between the substrate and the substrate surface (so-called anchor effect). When the conductor metal layer 2 is formed by the vapor phase method, this roughening treatment need not be performed.
When the conductor metal layer 2 is formed by the chemical plating method, it is preferable to perform this roughening treatment. Examples of the roughening method include a method of immersing the ceramic substrate 1 in a solution of hot phosphoric acid, molten alkali, HF, etc., or a method of physically roughening it by polishing or sandblasting. The roughening treatment method of can also be adopted.

[Step] A resistor paste is applied and dried at a predetermined position on the ceramic substrate 1 by a means such as screen printing so as to form a predetermined pattern. Then, the resistor paste is fired together with the ceramic substrate 1 to form the resistor layer 3.

Resistor paste is PdO / Pd / Ag system or Ru
A usual resistor forming material is used, such as a mixture of an O ₂ -based resistance component with glass containing an oxide of Si, Ca, Al or the like, an organic vehicle, or the like to form a paste. When using the resistor paste, it is preferable to select and use one that is compatible with the material of the ceramic substrate,
Usually, the RuO ₂ type having the most stable characteristics is suitable.

The method for drying and forming the resistor paste is the same as the method for forming a resistor, but the following conditions are common, for example. That is, after the resistor paste printed on the ceramic substrate 1 by screen printing or the like is dried at 50 to 200 ° C., the temperature at which the glass frit in the components is melt-bonded, preferably 500 to
1100 degreeC, More preferably, it comprises in the range of 600-950 degreeC.

[Step] The protective layer 4 is formed so as to cover a part of the resistor layer 3. The protective layer 4 is formed to improve the heat resistance, moisture resistance, chemical resistance, etc. of the resistor layer 3 and reduce the drift of the resistance value. The protective layer 4 covers the entire resistor layer 3 except a portion for connecting the resistor layer 3 and the conductor metal layer 2 in a later step. As the protective layer 4, an ordinary overcoat glass, which is also used in the conventional manufacturing method, can be used. Instead of the overcoat glass, a photosensitive polyimide, a polyimide, an epoxy resin, a triazine-based material, or the like is used. It is also possible to use the protective layer 4 formed of an organic or inorganic substance that is formed and has resistance to the acid or the like used in the roughening treatment in the subsequent step.

The protective layer 4 can be formed by a usual method, but for example, the following conditions are common. That is, a protective layer is formed by printing an overcoat glass paste by printing using a screen printing method to cover the entire resistor layer 3 except a part thereof, and then firing the glass paste at 300 to 800 ° C. 4 is formed.

[Step] If necessary, the exposed portion of the resistor layer 3 which is not covered with the protective layer 4 is roughened. When the conductor metal layer 2 is formed on the exposed portion of the resistor layer 3 thus roughened, the adhesion between the resistor layer 3 and the conductor metal layer 2 is improved by the so-called anchor effect. The roughening treatment does not need to use the treatment method having a strong roughening action such as hot phosphoric acid described in the roughening treatment of the ceramic substrate 1 described above. The resistor layer 3 can be roughened. Specifically, as a treatment method, for example, a method using an acid such as phosphoric acid, hydrofluoric acid, chromic acid, sulfuric acid, or an alkaline solution such as NaOH can be applied. By this roughening treatment, the resistor layer 3
Although the surface of the protective layer 4 and the surface of the ceramic substrate 1 may be roughened to some extent at the same time as the exposed portion of the protective layer 4, the protective layer 4 does not adversely affect the protective effect of the resistive layer 3 and the performance of the resistive layer 3. The roughening treatment method of is applied.

[Step] The conductor metal layer 2 is formed on the surface of the ceramic substrate 1 and the entire sprayed portion of the resistor layer 3. As the conductor metal layer 2,
Various metal materials used as materials for ordinary conductor circuits are used, such as chemical plating, vapor deposition, sputtering,
Any method selected from ordinary thin film forming means such as ion plating can be applied.

In the case of chemical plating, a normal sensitizing-activation method is used to deposit metallic palladium on the surface of the ceramic substrate 1 to activate the surface. afterwards,
The activated ceramic substrate 1 is immersed in a chemical copper plating bath or a chemical nickel plating bath to form a conductor metal layer 2 of copper or nickel.

The conductor metal layer 2 can also be formed using a vapor phase method such as vapor deposition, sputtering, ion plating, or a CVD method. When using the vapor phase method, a method of forming a metal layer of Cr or Ti in the first step, and forming a metal layer of copper or nickel on the metal layer in the second step, or 400
On the roughened ceramic substrate 1 heated to about ℃,
By adopting the same method of sequentially forming the metal layer of Cr or Ti and the metal layer of copper or nickel similar to the above, the adhesion between the ceramic substrate 1 and the thin film metal layer 2 is increased.

[Step] If necessary, electrolytic plating is performed on the conductor metal layer 2.
In the chemical plating method or the vapor phase method in the above process, only a thin metal layer having a thickness of 1 to several μm can be formed. Therefore, in order to increase the thickness of the conductor metal layer 2 necessary for a conductor circuit, the metal layer should be thickened. It is preferable to use an electrolytic plating method that can be performed together.

[Step] The conductive metal layer 2 formed on the entire ceramic substrate 1 and the resistor layer 3 is formed into a predetermined circuit pattern by etching. The details of the circuit formation by etching are the same as those in the ordinary method for manufacturing a printed circuit board, and thus the description of the specific steps is omitted. When such a circuit is formed by etching, a base metal conductor such as copper having a small wiring resistance is used, and the line width and the line spacing are 30 μm.
It becomes possible to form a fine pattern of m.

As a conductor circuit forming means, as described above, in addition to the method of etching the conductor metal layer 2 formed on the entire ceramic substrate 1, a plating resist layer having a pattern corresponding to a circuit pattern is formed in advance. It is also possible to directly form the conductor circuit without etching such as a method of forming the conductor metal layer 2 by a plating method only on the portion corresponding to the circuit pattern. In addition, as the conductor circuit forming means, various conductor circuit forming means used in a usual method for manufacturing a printed circuit board can be applied.

[Step] Next, the ceramic substrate 1 on which the conductor metal layer 2 is formed
Is heat-treated in a nitrogen atmosphere. The processing temperature is 200
The temperature is preferably in the range of to 800 ° C, more preferably in the range of 400 to 700 ° C. By this heat treatment, the conductor circuit 2, the resistor layer 3, and the ceramic substrate 1 are firmly adhered. In particular, the adhesive force at the connection point between the resistor layer 3 and the conductor circuit 2 is significantly improved.

The processing time is appropriately set, but is, for example, about 1 to 100 minutes. The heating atmosphere is composed of only nitrogen or an atmosphere containing nitrogen as a main component and containing only a small amount of components other than nitrogen, that is, a heating atmosphere which can be said to be substantially a nitrogen atmosphere. If necessary, the heating atmosphere may contain a small amount of oxygen of about 2 to 200 ppm. However, it is preferable that the heat treatment is performed so as not to adversely affect the performance of the resistor layer 3, the conductor metal layer 2, the protective layer 4, etc. formed on the surface of the ceramic substrate 1.

[Step] If necessary, the resistor layer 3 is trimmed to adjust it to a desired resistance value. As the trimming method, the same method as that for a normal circuit board with a resistor is used, and for example, there are methods such as abrasive trimming and laser trimming. Among them, laser trimming, which is capable of high-speed processing and has high performance, is the most preferable for implementing the present invention.

Through the above steps, a ceramic circuit board with a resistor as shown in FIG. 2 is manufactured.

In the above embodiment, a base metal conductor such as copper or nickel, which has a low wiring resistance and is inexpensive, is used as the metal forming the conductor circuit including the thin-film metal layer 20 and the conductor metal layer 2. It is possible to inexpensively form a conductor circuit having a fine pattern. In addition, if gold is used, there is no fear of migration, and solderability and the like will be good.

If a resistor paste for air firing such as RuO ₂ system is used, it is possible to form the resistor layer 3 with higher accuracy and higher reliability as compared with the resistor paste for nitrogen firing. It is possible to manufacture a ceramic circuit board provided with the resistor layer 3 having extremely high accuracy, the characteristic being within ± 2%.

Next, specific examples in which the method for manufacturing a ceramic circuit board with a resistor according to the present invention is actually applied will be described.

—Example 1— A 96% alumina substrate (4 ″ × 4 ″ × 0.635 mm) was used as the sintered ceramic substrate 1, and the substrate 1 was immersed in hot phosphoric acid to uniformly roughen the substrate surface. . The roughening brought the surface roughness to a maximum roughness of 2-3 μm. After the roughening treatment, it was thoroughly washed and dried. After drying, a RuO ₂ -based resistor paste was screen-printed on the ceramic substrate 1. After drying, the resistor layer 3 was formed by firing in air at 850 ° C. After that, a glass paste for overcoat is screen-printed so as to cover the entire resistor layer 3 except for a part that is a connection portion with the conductor metal layer 2, and after drying, 600 ° C. in air. The protective layer 4 was formed by firing under the conditions described above. 5 for the exposed portion of the resistor layer 3.
Roughening treatment was carried out using a hydrofluoric acid solution of 1%, and then the resultant was thoroughly washed with water and dried.

A copper layer was formed on the ceramic substrate 1 by a chemical plating method, and a copper metal was further applied by an electrolytic plating method to form a conductor metal layer 2 having a total thickness of 10 μm.
Then, heat treatment was performed at 600 ° C. in a nitrogen atmosphere containing 50 ppm of oxygen. In this state, the exposed portion of the resistor layer 3 and the conductor metal layer 2 are firmly adhered, and the conductor metal layer 2 and the ceramic substrate 1 have an adhesive force of 2.0 to 3.
A very high value of 0 kg / mm ² was shown.

Next, the conductor metal layer 2 was subjected to pattern etching by using a photoengraving technique to form a conductor circuit having a line width and a line spacing of 50 μm. With respect to the ceramic circuit board with a resistor thus obtained, the resistance characteristic with respect to the circuit constant of the resistor layer 3 was measured, and a highly accurate value within ± 2% was shown. After that, trimming adjustment was performed with a laser trimmer so that the resistance value of the resistor layer 3 became a desired value, whereby a ceramic circuit board with a resistor as shown in FIG. 2 could be manufactured.

Example 2 A 92% alumina substrate was used as the sintered ceramic substrate 1, and the surface was roughened to a maximum roughness of about 2 to 3 μm by immersing it in a molten salt of NaOH, then thoroughly washed and dried. Let After drying, Ru on the ceramic substrate 1
An O ₂ -based resistor paste was screen-printed, dried, and then fired in air at 900 ° C. to form a resistor layer 3. After that, a glass paste for overcoating was screen-printed so as to cover a predetermined portion of the resistor layer 3, dried, and then baked in air at 580 ° C. to form a protective layer 4. Furthermore, the exposed portion of the resistor layer 3 is
The mixture was roughened with a 10% chromic acid solution, thoroughly washed with water and dried.

A conductor metal layer 2 made of a copper layer having a thickness of 5 μm was formed only on the surface of the ceramic substrate 1 and the sprayed portion of the resistor layer 3 by a chemical plating method. Then, in a nitrogen atmosphere, 65
Heat treatment was performed at 0 ° C.

In this state, the exposed portion of the resistor layer 3 and the conductor metal layer 2 are firmly adhered, and the adhesion force between the conductor metal layer 2 and the ceramic substrate 1 is 2.0 to 3.0 kg / mm ² . The value was extremely high.

Next, the conductor metal layer 2 was subjected to pattern etching by using a photoengraving technique to form a conductor circuit having a line width and a line spacing of 50 μm. With respect to the ceramic circuit board with a resistance pair thus obtained, the resistance characteristic with respect to the circuit constant of the resistor layer 3 was measured, and a highly accurate value within ± 2% was shown. Then, trimming was adjusted by a laser trimmer so that the resistance value of the resistance layer 3 was a desired value.

-Example 3-A 99% alumina substrate was used as the sintered ceramic substrate 1, and the surface of this substrate was hydrofluoric acid to have a maximum roughness of 1-2.
After roughening to μm, it was thoroughly washed and dried. A RuO ₂ -based resistor paste was screen-printed on the dried ceramic substrate 1 and dried, and then 850 in air.
The resistor layer 3 was formed by firing at ° C. The overcoat glass paste was screen-printed so as to cover a predetermined portion of the resistor layer 3, dried, and then baked in air at 600 ° C. to form the protective layer 4.

Next, the exposed portion of the resistor layer 3 is roughened by using a 10% sulfuric acid solution, sufficiently washed with water and dried, and then a copper tube is formed by a sputtering method, and further a copper metal is thickened by an electrolytic plating method. Then, a conductor metal layer 2 having a thickness of 12 μm was formed. Then, heat treatment was performed at 600 ° C. in a nitrogen atmosphere containing 70 ppm of oxygen.

In this state, the exposed portion of the resistor layer 3 and the conductor metal layer 2 are firmly adhered, and the adhesive force between the conductor metal layer 2 and the ceramic substrate 1 is 2.0 to 3.0 kg / mm ² . , Showed an extremely high value.

Next, the conductor metal layer 2 was subjected to pattern etching by using a photoengraving technique to form a conductor circuit having a line width and a line spacing of 50 μm. With respect to the ceramic circuit board with a resistor thus obtained, the resistance characteristic with respect to the circuit constant of the resistor layer 3 was measured, and a highly accurate value within ± 2% was shown. Then, trimming was adjusted by a laser trimmer so that the resistance value of the resistance layer 3 was a desired value.

—Example 4— A 96% alumina substrate was used as the ceramic substrate 1, and the resistor paste was directly drawn on the ceramic substrate 1 so as to have a predetermined shape. A ceramic circuit board with a body was manufactured. As a result, the variation in the resistance value of the resistor layer 3 of the obtained ceramic circuit board had the same excellent characteristics as in Example 2.

-Example 5-A 99% alumina substrate was used as the sintered ceramic substrate, and the copper layer to be the conductor metal layer 2 was not subjected to electrolytic plating.
A ceramic circuit board with a resistor was manufactured by the same steps as in Example 1 except that the thickness was 8 μm only by chemical plating. As a result, the variation in the resistance value of the resistor layer 3 of the obtained ceramic circuit board had the same excellent characteristics as in Example 1.

〔The invention's effect〕

According to the invention described in claim 1, among the methods for manufacturing a ceramic circuit board with a resistor according to the present invention described above,
After forming a conductor circuit on the surface of the ceramic substrate on which the resistor layer and the protective layer are formed and on the exposed portion of the resistor layer,
By performing the heat treatment, the adhesion between the conductor circuit and the resistor layer and the ceramic substrate could be significantly increased. Unlike the conventional roughening treatment, this heat treatment does not have a bad influence on the resistor layer, so that it is possible to manufacture a ceramic circuit board having a highly accurate and highly reliable low antibody layer.

Moreover, as compared with a method of manufacturing a conductor circuit by firing a conductor metal paste, a fine circuit can be formed, and a conductor metal having a low resistance can be used, so that the wiring resistance becomes low,
Since a high-performance resistor layer can be used, it is possible to provide a ceramic circuit board provided with a resistor layer having higher accuracy and higher reliability.

In particular, the conductor metal layer to be a conductor circuit is formed by the thin film forming means, and the heat treatment is performed within a temperature range of 200 to 800 ° C. in an atmosphere containing nitrogen as a main component, whereby the antibody body layer and the upper layer are formed. Since the adhesion between the conductor circuit made of a copper layer and the ceramic substrate and the resistor layer can be increased without impairing the characteristics of the protective layer that covers the resistor layer, the quality performance of the ceramic circuit board with a resistor can be improved. is there.

[Brief description of drawings]

FIG. 1 is a process flow chart showing an embodiment of the present invention, and FIG. 2 is a sectional view of a manufactured ceramic circuit board with a resistor. 1 ... Ceramic substrate, 2 ... Conductor metal layer, 3 ... Resistor layer, 4 ... Protective layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-55-95396 (JP, A) JP-A-61-185995 (JP, A) JP-A-61-194794 (JP, A) JP-A-58- 24464 (JP, A) JP 55-123196 (JP, A) JP 57-207395 (JP, A) JP 61-225047 (JP, A)

Claims (1)

[Claims] 1. A method of manufacturing a ceramic circuit board in which a resistor is formed on a ceramic substrate together with a conductor circuit, the method including the following steps (1) to (3): Board manufacturing method. (1) A step of forming a resistor layer on a ceramic substrate and forming a protective layer on the resistor layer. (2) A step of forming a conductor metal layer corresponding to a predetermined circuit pattern on the surface of the ceramic substrate and the exposed portion of the resistor layer by a thin film forming means. (3) A step of heating the ceramic substrate on which the conductor circuit is formed within a temperature range of 200 to 800 ° C. in a nitrogen atmosphere.