TW201701299A - Cu paste composition for forming thick film conductor, and thick film conductor - Google Patents

Abstract

Provided is a Cu paste composition capable of improving the sulfidation resistance of a thick film conductor such as a thick film electrode or a thick film wire that is formed by being applied on a substrate of a substrate and fired, and capable of improving the reliability of electronic components or electronic circuits. A Cu powder, an Ni powder, and an organic vehicle are mixed so that the Ni powder is present in an amount of 0.7-20 mass parts and the organic vehicle is present in an amount of 5-40 mass parts with respect to a total of 100 mass parts of the Cu powder and Ni powder, to obtain a Cu paste composition. Alternatively, a Cu2O powder is admixed with the above composition in an amount of 1-15 mass parts to obtain a Cu paste composition.

Description

Copper paste composition for thick film conductor formation and thick film conductor

The present invention relates to a copper (Cu) paste composition for forming a thick film conductor such as a thick film electrode or a thick film wiring. Further, the present invention relates to a thick film conductor formed by the copper paste composition.

An electronic component such as a chip resistor, an integrated circuit (IC), a resistance network, a display device represented by a touch panel, a solar cell, and the like In the field of the electronic circuit of the electronic component, the paste (conductive paste) obtained by uniformly dispersing the conductive powder in an organic solvent or the like is applied to a glass substrate, an alumina substrate, a tantalum substrate, or the like. On the surface, calcination or thermal hardening is performed, thereby forming a thick film conductor such as a thick film electrode or a thick film wiring.

At this time, the application of the conductive paste is performed by screen printing, gravure printing, or drawing using a dispenser. Silver (Ag) powder having a low electrical resistance value and excellent oxidation resistance is widely used as the conductive powder used in the conductive paste. However, the use of a conductive paste containing Ag powder to form a thick film electrode or a thick film wiring on the surface thereof has a problem that if a voltage is applied in a high moisture environment, ionized silver (Ag ⁺ ) is generated. A phenomenon in which a short circuit occurs between the electrodes (ion migration). Further, there is also a problem that the Ag powder has a high unit price and it is difficult to achieve a reduction in manufacturing cost. Therefore, in recent years, as a conductive paste for forming a thick film conductor such as a thick film electrode or a thick film wiring, it has been studied to use a conductive paste which has a low resistance value and excellent migration resistance. A copper (Cu) powder or a powder containing Cu as a main component replaces the Ag powder.

For example, Japanese Laid-Open Patent Publication No. 2004-039355 proposes a conductive paste containing Cu powder and a glass powder containing crystal glass and having a difference between a softening point and a crystallization onset temperature of 100 ° C or higher. Such a conductive paste can form a conductive film which is excellent in sealing property and excellent in plating adhesion. However, since this electrically conductive paste is mainly aimed at the connection with the external electrode of the laminated ceramic capacitor, it is difficult to say that it has been sufficiently evaluated about the shrinkability, oxidation resistance, and sulfurization resistance at the time of baking.

On the other hand, Japanese Laid-Open Patent Publication No. 3237497 proposes a conductive paste which is a conductive paste for conducting a through-hole of a ceramic substrate, and includes Cu powder having an average particle diameter of about 1 μm to 5 μm and an average particle diameter. a nickel (Ni) powder, a glass frit, and an organic vehicle of about 3 μm, and the amount of Ni powder relative to the total amount of the Cu powder and the Ni powder is 1% by mass to 20% by mass, and The amount of the glass medium relative to the total amount of the Cu powder, the Ni powder, and the glass medium is 1% by mass to 40% by mass. It is considered that by using the conductive paste, it is possible to suppress shrinkage during firing by adding a certain amount of Ni powder to the Cu powder, and to prevent peeling between the conductor and the side wall of the through hole.

In addition, Japanese Patent No. 4,464,362 discloses a technique of containing Ni powder or nickel oxide (NiO) powder in a ratio of 1 part by mass to 10 parts by mass based on 100 parts by mass of Cu powder (in terms of NiO) And a conductive paste containing copper oxide (CuO) powder in a ratio of 0.1 part by mass to 3 parts by mass to form a metallization wiring layer on the surface and/or inside of the insulating substrate including the glass ceramic. The conductive paste is added with CuO powder in order to suppress alloying of Cu and Ni in the firing process and to ensure conductivity of the obtained metallized wiring layer.

In addition, in recent years, demands for miniaturization of electronic components, electronic circuits, and the like have increased the demand for miniaturization of thick film electrodes or thick film wirings, in other words, narrower widths and narrower intervals have been formed. The demand for conductive pastes for thick film conductors such as thick film electrodes or thick film wiring is increasing. Specifically, a thick film conductor having a required width of about 50 μm to 200 μm and a thickness of about 5 μm to 20 μm is required. On the other hand, with the miniaturization of a thick film conductor such as such a thick film electrode or a thick film wiring, there is a problem that hydrogen sulfide (H ₂ S) gas or sulfurous acid (H) in the atmosphere which is not problematic in the prior art arises. ₂ SO ₃ ) Vulcanization caused by gas or the like causes a gradual increase in the resistance value of the thick film conductor, which eventually leads to disconnection, which is a cause of lowering the reliability of the electronic component or electronic circuit. [Prior Art Document] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2004-039355 (Patent Document 2) Japanese Patent No. 3237497 (Patent Document 3) Japanese Patent No. 4,464,362

[Problem to be Solved by the Invention] An object of the present invention is to provide a copper paste composition for forming a thick film conductor and a thick film conductor, which can be coated on a surface of a substrate by a copper paste composition for forming a thick film conductor. The thick film conductor formed by the calcination and the thick film conductor formed by the thick film wiring are resistant to vulcanization, thereby improving the reliability of the electronic component or the electronic circuit. [Means for solving the problem]

The copper paste composition for forming a thick film conductor of the present invention contains Cu powder, Ni powder, and an organic carrier, and contains 0.7 parts by mass to 20 parts by mass based on 100 parts by mass of the total of Cu powder and Ni powder. Ni powder and 5 parts by mass to 40 parts by mass of an organic vehicle.

When the thick-film conductor-forming copper paste composition is fired at 550 ° C to 750 ° C in a non-oxidizing atmosphere to form a thick film conductor having a thickness of 10 μm, the area resistance of the thick film conductor can be obtained. Set to 50 mΩ/□ or less.

The copper paste composition for forming a thick film conductor preferably contains 1 part by mass to 15 parts by mass of Cu ₂ O powder based on 100 parts by mass of the total of the Cu powder and the Ni powder.

By adding the Cu ₂ O powder, the calcination temperature of the thick film conductor-forming copper paste composition can be lowered. In other words, when the copper paste composition for forming a thick film conductor containing the Cu ₂ O powder is fired at 500 to 750 ° C in a non-oxidizing atmosphere to form a thick film conductor having a thickness of 10 μm, The area resistance of the thick film conductor is set to 50 mΩ/□ or less.

The Cu ₂ O powder preferably has an average particle diameter of 0.5 μm to 5 μm.

In addition, the copper paste composition for forming a thick film conductor of the present invention may further contain 0.5 parts by mass to 5 parts by mass of the glass powder based on 100 parts by mass of the total of the Cu powder and the Ni powder.

The average particle diameter of the Cu powder and the Ni powder is preferably 0.2 μm to 0.7 μm.

Further, in the copper paste composition for forming a thick film conductor of the present invention, a thick film conductor (thick film wiring) is formed between a pair of gold (Au) electrodes, and an area resistance value of the initial state of the thick film conductor is set. When R _s0 and the thick film conductor are immersed in cutting oil containing 0.3% by mass of sulfur at 80 ° C for 6 hours, the area resistance value is R _s6 , and R _s6 can be relative to R _s0 . The resistance change rate defined by R _s6 /R _s0 is set to 20 or less.

The thick film conductor of the present invention can be formed by the copper paste composition for forming a thick film conductor as described above. [Effects of the Invention]

According to the copper paste composition for forming a thick film conductor and the thick film conductor of the present invention, it is possible to suppress an increase in resistance value due to vulcanization of a thick film conductor such as a thick film electrode or a thick film wiring formed on the surface of the substrate for a long period of time. Therefore, the reliability of electronic parts or electronic circuits can be improved. Further, the copper paste composition for forming a thick film conductor of the present invention can be easily mass-produced industrially. Therefore, the industrial significance of the present invention is enormous.

In view of the above problems, the inventors of the present invention repeatedly conducted the following tests: adding various elements to a copper paste composition for forming a thick film conductor such as a thick film electrode or a thick film wiring, and having an area resistance value and resistance to vulcanization Sexual evaluation. As a result, it was found that when a predetermined amount of Ni powder was added to the copper paste composition, when the copper paste composition was fired, Cu and Ni were alloyed, and the use of the copper paste composition was drastically improved. The sulphide resistance of the formed thick film conductor. The present invention has been completed based on this finding.

1. Composition

In the following, the copper paste composition for forming a thick film conductor of the present invention (hereinafter referred to as "copper paste composition") is divided into individual components and described in detail. Further, in the present invention, Cu powder and Ni powder which are more inexpensive than Ag powder are used as the conductive powder, so that the production cost can be greatly reduced. Further, the copper paste composition of the present invention is not limited as long as it can uniformly mix the following constituent components. For example, it can be produced by mixing and stirring by a known mechanism such as a three-roll mill or a mixer.

(1) Cu powder and Ni powder

The copper paste composition of the present invention is characterized in that a certain amount of Ni powder is added to the Cu powder. Thereby, the sulfidation resistance of the thick film conductor obtained by apply|coating the copper paste composition on the board|substrate, and baking, can be improved.

[Content of Ni powder]

The content of the Ni powder is set to 0.7 parts by mass to 20 parts by mass, preferably 0.7 parts by mass to 12 parts by mass, more preferably 1 part by mass, based on 100 parts by mass of the total of the Cu powder and the Ni powder. 3 parts by mass. When the content of Ni is less than 0.7 parts by mass, the sulfurization resistance of the thick film conductor cannot be sufficiently improved. On the other hand, when the content of Ni exceeds 20 parts by mass, the area resistance value of the thick film conductor becomes high, and it cannot be used as an electrode material or a wiring material.

[Average particle diameter of Cu powder and Ni powder]

Ni has a higher melting point and a slower diffusion rate than Cu. Therefore, the addition of Ni powder hinders the sintering of the copper paste composition. If it is not calcined at a high temperature of 550 ° C or higher, Cu and Ni cannot be appropriately formed. Alloying. On the other hand, it is generally known that sintering can be promoted by making the sintered material fine. Therefore, in the copper paste composition of the present invention, the average particle diameter of the Cu powder and the Ni powder is preferably 0.2 μm to 0.7 μm, more preferably 0.2 μm to 0.5 μm, and even more preferably 0.3 μm. ~0.5 μm. When the average particle diameter of the Cu powder and the Ni powder is within such a range, sintering of the Cu powder and the Ni powder can be promoted, even when the baking temperature is set to a relatively low temperature of about 550 ° C to 750 ° C. It is also possible to appropriately alloy Cu and Ni.

On the other hand, when the Cu powder and the Ni powder have an average particle diameter of less than 0.2 μm, they can be calcined at a lower temperature, but the oxygen content in the copper paste composition increases, which hinders the alloying of the Cu powder and the Ni powder. On the other hand, when the average particle diameter of the Cu powder and the Ni powder exceeds 0.7 μm, sintering may be inhibited, and the sintering promotion effect described above may not be obtained.

In the present invention, the average particle diameter refers to a volume-based average particle diameter (Mv) obtained by a laser diffraction scattering method, and can be measured by a laser diffraction scattering type particle size distribution measuring apparatus. In this respect, the cuprous oxide (Cu ₂ O) powder and the glass powder described later are also the same.

(2) Organic carrier

The organic carrier is necessary for the coating of the copper paste composition, but it is lost during calcination and does not contribute to the improvement of the sulfidation resistance of the thick film conductor. Therefore, in the copper paste composition of the present invention, the type of the organic vehicle is not limited, and a known organic carrier can be used. A typical organic carrier is an organic carrier obtained by dissolving ethyl cellulose, an acrylic resin, or a methacrylic resin in a solvent such as terpineol or a higher alcohol.

The content of the organic carrier is set to 5 parts by mass to 40 parts by mass, preferably 10 parts by mass to 35 parts by mass, more preferably 20 parts by mass, based on 100 parts by mass of the total of the Cu powder and the Ni powder. ~ 30 parts by mass. When the content of the organic vehicle is less than 5 parts by mass, the viscosity of the copper paste composition becomes high, and a uniform coating film cannot be formed. On the other hand, when the content of the organic carrier exceeds 40 parts by mass, not only the thick film electrode or the thick film wiring after the baking is too thin, but also the organic carrier cannot be completely burned off during the calcination, which hinders the Cu powder or Sintering of Ni powder.

(3) Glass powder

When the copper paste composition of the present invention is used to form a thick film conductor directly on a substrate, it is also possible to further add the above-described constituent components from the viewpoint of improving the adhesion between the copper paste composition and the substrate. Glass powder. However, in the case of wire bonding or welding, it is also preferred to add no glass powder. Therefore, the addition of the glass powder must be appropriately selected depending on the use or purpose of the copper paste composition.

The glass powder to be added to the copper paste composition is not particularly limited as long as the softening point is lower than the calcination temperature of the copper paste composition, and is preferably free of lead (Pb) or the like from the viewpoint of environmental protection and the like. Hazardous substances such as cadmium (Cd).

When the glass powder is added to the copper paste composition, the content of the glass powder is preferably set to 0.5 parts by mass to 5 parts by mass, more preferably set to 100 parts by mass of the total of the Cu powder and the Ni powder. It is 2 parts by mass to 3 parts by mass. When the content of the glass powder is less than 0.5 part by mass, the adhesion between the thick film conductor and the substrate may not be sufficiently improved after the firing. On the other hand, when the content of the glass powder exceeds 5 parts by mass, not only the resistance value of the thick film conductor is increased, but also the solder wettability or the plating adhesion of the thick film conductor is lowered.

In addition, the average particle diameter of the glass powder is not particularly limited, and is preferably 1 μm to 10 μm, more preferably 3 μm to 5 μm from the viewpoint of uniform mixing with Cu powder or Ni powder. .

(4) Cu ₂ O powder

As described above, when Ni powder is added to the copper paste composition, sintering may be prevented. Further, when a resin which is hard to be burned off during calcination in a non-oxidizing environment such as ethyl cellulose is used as the organic carrier, the sintering of the copper paste composition may be hindered depending on the amount of addition.

The inventors of the present invention conducted a repetitive study on this aspect, and as a result, found that a copper paste composition in which a glass powder, a Ni powder, an organic vehicle, or a glass powder are added in addition to the above components is added. Further, a certain amount of cuprous oxide (Cu ₂ O) powder is added to improve the sinterability, and the Cu and Ni may be appropriately alloyed even when calcined at a lower temperature of about 500 ° C to 750 ° C. Chemical.

Although the reason why such a sinterability improving effect can be obtained by adding a Cu ₂ O powder is not clear at this stage, the inventors of the present invention repeatedly performed copper in the same manner except that copper oxide (CuO) powder was added instead of Cu ₂ O powder. As a result of the measurement of the calcination temperature of the paste composition, it was confirmed that the copper paste composition could not obtain a sufficient sinterability improving effect. In the above-mentioned Japanese Patent No. 464362, the copper oxide powder is added to the copper paste composition. However, the copper oxide powder in this document is CuO powder, so the copper paste composition can be considered as a copper paste composition. The sinterability improvement effect is hardly obtained. Further, in this document, CuO powder is added in order to suppress alloying of Cu and Ni. Therefore, the copper paste composition described in the present invention and Japanese Patent No. 464362 can be said to be quite different in these respects.

Further, since the Cu ₂ O powder of the copper paste composition of the present invention is decomposed by calcination, it is considered that it is present in the thick film conductor in a state of being alloyed with Cu powder or Ni powder after calcination.

[Content of Cu ₂ O powder]

When the case where Cu ₂ O is added to the powder, relative to the total 100 parts by mass of Cu powder and Ni powder, Cu ₂ O content of the powder is set to 1 parts by mass to 15 parts by mass, preferably set to 5 parts by mass ~10 parts by mass. When the content of the Cu ₂ O powder is within such a range, the effect of improving the sinterability of the copper paste composition can be sufficiently obtained. Specifically, even when the copper paste composition is fired at a lower temperature of 500 ° C or higher, the Cu powder and the Ni powder can be sufficiently sintered to appropriately alloy Cu and Ni.

On the other hand, when the content of the Cu ₂ O powder is less than 1 part by mass, the effect of improving the sinterability cannot be sufficiently obtained. On the other hand, when the content of the Cu ₂ O powder exceeds 15 parts by mass, unreacted Cu ₂ O powder remains, thereby hindering the sintering or the deterioration of adhesion of solder or plating.

[Average particle diameter of Cu ₂ O powder]

The average particle diameter of the Cu ₂ O powder is preferably set to 0.5 μm to 5 μm, and more preferably set to 1 from the viewpoint of uniformly mixing Cu powder or Ni powder or the like and efficiently obtaining a sinterability improving effect. Mm ~ 2 μm.

(5) Other added ingredients

In the copper paste composition of the present invention, in view of lowering the calcination temperature, In, Sn, Zn, or the like may be added in addition to the above-described constituent components. In addition, a dispersing agent or a viscosity adjusting agent may also be added. However, the amount of addition of these other additional components must be limited to a range that does not hinder the effect obtained by adding the Ni powder or the Cu ₂ O powder described above.

2. Characteristics of copper paste composition

(1) Calcination temperature

The temperature (baking temperature) when the copper paste composition of the present invention is applied onto the surface of the substrate and fired is set to be 550 ° C to 750 ° C when the Cu ₂ O powder is not contained. On the other hand, in the case of containing a Cu ₂ O powder, it is set to 500 to 750 °C. By setting the calcination temperature of the copper paste composition within such a range, a thick film conductor can be formed also on a substrate having low temperature durability. Further, since multilayer wiring can be formed, the application range of the copper paste composition can be expanded.

On the other hand, when the baking temperature of the copper paste composition containing no Cu ₂ O powder is less than 550 ° C, or the baking temperature of the copper paste composition containing Cu ₂ O powder is less than 500 ° C, it cannot be made. Cu and Ni are suitably alloyed. On the other hand, no matter which copper paste composition, even if the calcination temperature exceeds 750 ° C, not only a higher effect cannot be obtained, but also an increase in production cost is caused.

(2) Area resistance value

The copper paste composition of the present invention is preferably coated on a substrate and calcined at the calcination temperature described above to form a thick film conductor having a width of 0.5 mm, a length of 50 mm, and a thickness of 10 μm. In order to set the area resistance value R _s to 50 mΩ/□ or less, it is more preferable to set it to 20 mΩ/□ or less, and it is preferable to set it to 10 mΩ/□ or less. Here, the area resistance value R _s is also referred to as a sheet resistance, and it is known that the resistance value R has the following relationship. R=ρ×L/A=ρ×L/(W×t)=ρ/t×L/W=R _s ×L/W ρ: Resistivity A: cross-sectional area of the sample L: length of the sample W : width of sample t: thickness of sample

Furthermore, the smaller the area resistance value of the thick film conductor described above, the better, and the lower limit is not limited. Further, the area resistance value can be measured by a known method.

(3) Sulfur resistance

Since the thick film conductor obtained by the copper paste composition of the present invention is excellent in sulfur resistance, the area resistance value can be maintained within the above range for a long period of time. The sulfidation resistance of such a thick film conductor can be evaluated by the following vulcanization test.

First, an Au paste composition was printed on a substrate so that the distance between electrodes became 50 mm, and calcination was performed, thereby forming a pair of Au electrodes. Then, a copper paste composition was applied between the Au electrodes, and calcined in an inert atmosphere at the calcination temperature described above, thereby forming a thick film conductor having a width of 0.5 mm and a thickness of 10 μm to 13 μm. In this state (initial state), the resistance value was measured at five or more positions between the Au electrodes, and the area resistance value R _{s0 of the} thick film conductor was calculated from the average value and the thickness of the resistance value of the thick film conductor.

Then, the thick film conductor was immersed in the cutting oil containing 0.3% by mass of sulfur (S) maintained at 80 ° C together with the substrate. After t elapsed, the thick film conductor was lifted up, and the area resistance value R _{st of the} thick film conductor was calculated in the same manner. The area thus obtained, and the resistance value R _s0 is calculated by the R _st R _st with respect to the resistance change ratio of R _s0 R _st / R _s0 defined, whereby the evaluation of the thick film conductor sulfidation resistance.

Further, the reason why the Au electrode is used as the electrode in the vulcanization test is that Au is not corroded by sulfur (S), so that the influence of the electrode can be ignored in the measurement of the area resistance value of the thick film conductor after the vulcanization test. .

In particular, when a thick film conductor is formed using the copper paste composition of the present invention, it is preferable to set the resistance change rate to 20 or less, more preferably 10 or less, and still more preferably 1.5 or less. The rate of change in resistance is defined by the ratio R _s6 /R _s0 of the area resistance value R _s6 after immersion in the cutting oil containing 0.3% by mass of sulfur at 80 ° C for 6 hours with respect to the area resistance value R _s0 of the initial state. .

3. Thick film conductor

The thick film conductor of the present invention can be formed by the copper paste composition described above. As described above, the thick film conductor has excellent sulfur resistance and is not corroded by hydrogen sulfide gas or sulfurous acid gas in the atmosphere. Therefore, even when the thickness of the thick film electrode or the thick film wiring including the thick film conductor is reduced to a size of about 50 μm to 200 μm and a thickness of about 5 μm to 20 μm, the electronic component or the electronic circuit can be miniaturized. It can also effectively suppress the disconnection or increase in resistance value. Therefore, by using the thick film conductor of the present invention, the reliability of an electronic component or an electronic circuit can be dramatically improved. [Examples]

Hereinafter, specific embodiments to which the present invention is applied will be described, but the present invention is not limited to the embodiments.

(Examples 1-1 to 1-9 and Comparative Examples 1-1 to 1-3)

[Production of copper paste composition]

As a component of the copper paste composition, Cu powder and Ni powder having an average particle diameter of 0.2 μm and 0.5 μm, and SiO ₂ -B ₂ O ₃ -ZnO-based glass powder having an average particle diameter of 3 μm and a softening point of 450 ° C were prepared. And an organic carrier obtained by dissolving an acrylic resin in terpineol. Further, the average particle diameter of the powders was measured by a laser diffraction scattering type particle size distribution measuring apparatus (Nikkiso Co., Ltd., Microtrac). These components were blended so as to have a composition ratio shown in Table 1, and kneaded by a three-roll mill to sufficiently disperse the respective constituent components, thereby obtaining Examples 1-1 to 1-9 and Comparative Examples. The copper paste composition of 1-1 to Comparative Example 1-3.

[Evaluation of area resistance value and sulfur resistance]

A pattern having a width W of 0.5 mm and an electrode spacing L of 50 mm was used on the surface of a 96% alumina substrate on which an Au paste was previously printed and calcined to form an Au electrode, and the film thickness t after calcination was 10 μm. The copper paste compositions of Examples 1-1 to 1-9 and Comparative Examples 1-1 to 1-3 were printed in a manner of ~13 μm, and calcined at 750 ° C or 550 ° C in an N ₂ atmosphere. In this case, samples for the vulcanization test were prepared separately.

The resistance measuring probe for a digital multimeter (manufactured by Advantest Co., Ltd.) was brought into contact with five points between the Au electrodes of the samples to measure the resistance of the thick film conductor. The value R[t]. Then, the resistance value R[t] is converted into the area resistance value R _s [t] (=R(t)×W/L), and the average value R _s0 [t] is obtained, thereby calculating the thick film conductor separately. The area resistance value R _s0 (=R _s [t] × t/10) when the thickness is 10 μm.

Then, the samples were immersed in a cutting oil containing 0.3% by mass of S which was maintained at 80° C. for evaluation of sulfidability, and similarly, after 1 hour, 2 hours, 3 hours, and 6 The area resistance value R _s1 , the area resistance value R _s2 , the area resistance value R _{S3 ,} and the area resistance value R _s6 after the hour. These results are shown in Table 2 and Figure 1.

[Table 1]

[Table 2]

(Example 2-1 to Example 2-13 and Comparative Example 2-1 to Comparative Example 2-3)

[Production of copper paste composition]

As a component of the copper paste composition, Cu powder and Ni powder having an average particle diameter of 0.2 μm and 0.3 μm, and SiO ₂ -B ₂ O ₃ -ZnO-based glass powder having an average particle diameter of 3 μm and a softening point of 450 ° C were prepared. Cu ₂ O powder having an average particle diameter of 0.5 μm, 1.0 μm, and 1.5 μm, and an organic vehicle obtained by dissolving ethyl cellulose in terpineol. These components were blended so as to have a composition ratio shown in Table 3, and kneaded by a three-roll mill to sufficiently disperse the respective constituent components, thereby obtaining Examples 2-1 to 2-13 and Comparative Examples. The copper paste composition of 2-1 to Comparative Example 2-3.

[Evaluation of area resistance value and sulfur resistance]

A pattern having a width of 0.5 mm and an electrode spacing of 50 mm was used on the surface of a 96% alumina substrate on which an Au paste was previously printed and fired to form an Au paste, and the film thickness after firing was 10 μm to 13 μm. The copper paste compositions of Examples 2-1 to 2-13 and Comparative Examples 2-1 to 2-3 were printed and calcined at 550 ° C or 500 ° C for 1 hour in an N ₂ atmosphere. This was separately prepared for the test for vulcanization test.

The area resistance value R _s0 , the area resistance value R _s1 , the area resistance value R _s2 , the area resistance value R _{s3 ,} and the area resistance value of the samples were calculated in the same manner as in the first to ninth embodiments and the first to third comparative examples. R _s6 . These results are shown in Table 4 and Figure 2.

[table 3]

[Table 4]

(Evaluation)

According to Tables 1 to 4, FIG. 1 and FIG. 2, it was confirmed that the copper paste compositions of Examples 1-1 to 1-9 and Examples 2-1 to 2-13 were coated and fired. The thick film conductors have an area resistance value R _s0 of 50 mΩ/□ or less in the initial state, and the resistance change rate R _s6 /R _s0 is 20 or less, and have excellent sulfur resistance.

Further, by analyzing the thick film conductor obtained by coating and printing the copper paste composition of Example 2-12 by X-ray diffraction, as in the other examples, no diffraction of Cu and Ni was observed. At the peak, only the diffraction peak of the Cu-Ni alloy was observed. Therefore, when the Cu ₂ O powder is added, even if the baking temperature is set to about 500 ° C, Cu and Ni can be appropriately alloyed, and the sulfurization resistance can be improved.

no

Fig. 1 is a graph showing the sulfidation resistance of the samples obtained in Examples 1-1 to 1-9 and Comparative Examples 1-1 to 1-3. 2 is a graph showing the sulfidation resistance of the samples obtained in Examples 2-1 to 2-13 and Comparative Examples 2-1 to 2-3.

Claims (10)

A copper paste composition for forming a thick film conductor, comprising Cu powder, Ni powder, and an organic carrier, and containing 0.7 parts by mass to 20 parts by mass of Ni powder and 5 masses based on 100 parts by mass of the total of Cu powder and Ni powder. Parts to 40 parts by mass of an organic vehicle. The copper paste composition for forming a thick film conductor according to the first aspect of the invention, wherein the Cu ₂ O powder is further contained in an amount of 1 part by mass to 15 parts by mass based on 100 parts by mass of the total of the Cu powder and the Ni powder. . The copper paste composition for forming a thick film conductor according to the first aspect of the invention, wherein the glass powder is further contained in an amount of 0.5 parts by mass to 5 parts by mass based on 100 parts by mass of the total of the Cu powder and the Ni powder. The copper paste composition for forming a thick film conductor according to the first aspect of the invention, wherein the Cu ₂ O powder is further contained in an amount of 1 part by mass to 15 parts by mass based on 100 parts by mass of the total of the Cu powder and the Ni powder. And 0.5 parts by mass to 5 parts by mass of the glass powder. The copper paste composition for forming a thick film conductor according to any one of claims 1 to 3, which is calcined at a temperature of 550 ° C to 750 ° C in a non-oxidizing atmosphere to form a thickness of 10 μm. In the case of a thick film conductor, the thick film conductor has an area resistance value of 50 mΩ/□ or less. The copper paste composition for forming a thick film conductor according to the second or fourth aspect of the invention, wherein the thick film conductor having a thickness of 10 μm is formed by firing at 500 ° C to 750 ° C in a non-oxidizing atmosphere. In the case of the thick film conductor, the area resistance value is 50 mΩ/□ or less. The copper paste composition for forming a thick film conductor according to the second or fourth aspect of the invention, wherein the Cu ₂ O powder has an average particle diameter of 0.5 μm to 5 μm. The copper paste composition for forming a thick film conductor according to any one of claims 1 to 4, wherein the Cu powder and the Ni powder have an average particle diameter of 0.2 μm to 0.7 μm. The copper paste composition for forming a thick film conductor according to any one of claims 1 to 4, wherein a thick film conductor is formed between a pair of Au electrodes and an initial state of the thick film conductor is formed. When the area resistance value is R _s0 and the thick film conductor is immersed in the cutting oil containing 0.3% by mass of sulfur at 80 ° C for 6 hours, the area resistance value is R _s6 , and R _{s6 is} relatively to R _s0 resistance change ratio R _s6 / R _s0 defined ratio of 20 or less. A thick film conductor formed by the copper paste composition for forming a thick film conductor according to any one of claims 1 to 4.