JP2008053138A - Thick film conductor forming composition, method of forming thick film conductor using the same, and thick film conductor obtained - Google Patents

Abstract

Thick film conductor forming composition that prevents sintering adhesion between elements and does not impair element characteristics when forming a thick film conductor for a terminal electrode on an electronic component, and a thick film using the same A method for forming a conductor, and a thick film conductor obtained.
A conductive powder (A) comprising a conductive powder (a1) having a high conductivity and a conductive powder (a2) having a lower conductivity than the conductive powder (a1), an oxide powder (B), and an organic vehicle In the composition for forming a thick film conductor containing (C), the conductive powder (a2) has an average particle diameter of 7 μm or more, and the content of the conductive powder (a2) is 100 weights of the conductive powder (a1). Provided by the thick film conductor forming composition, etc., which is 4.0 to 8.0 parts by weight with respect to parts.
[Selection figure] None

Description

  The present invention relates to a composition for forming a thick film conductor, a method for forming a thick film conductor using the same, and a thick film conductor to be obtained. More specifically, when forming a thick film conductor for a terminal electrode on an electronic component, The present invention relates to a composition for forming a thick film conductor that prevents sintering adhesion between elements and does not impair the characteristics of the element, a method for forming a thick film conductor using the same, and a thick film conductor obtained.

When forming a conductor film using thick film technology, use a composition for forming a thick film conductor obtained by dispersing conductive powder with high conductivity in an organic vehicle using three rolls together with oxide powder, etc. To do. In general, this thick film conductor forming composition is applied to a ceramic substrate in a predetermined shape by screen printing, roller transfer, dipping or the like, and baked at 500 to 900 ° C. to form a conductive film on the ceramic substrate. Things have been done.
The composition for forming a thick film conductor is composed of a conductive powder, an oxide powder, and an organic vehicle. As the oxide powder, the softening point can be easily controlled, the chemical resistance to acid etc. is strong, and the softening point is an oxide having a softening point of 400 ° C. to 800 ° C., for example, lead borosilicate, lead aluminum borosilicate, borosilicate Zinc, bismuth borosilicate, etc. are used depending on the firing temperature when forming thick film conductors

  Recently, from the viewpoint of preventing environmental pollution, a composition for forming a thick film conductor not containing lead has been distributed. Therefore, as the conductive powder, metal powders such as Ag, Au, Pd, and Pt having a particle size of 10 μm or less and high conductivity are used, and in recent years, those containing Ag as a main component for the purpose of cost reduction, for example, Ag metal, Ag-Pd, Ag-Pt, etc. are generally used.

By the way, in electronic components such as prismatic elements, cylindrical elements, and disk elements, a thick film conductor is often formed as a conductive portion. For example, chip capacitors and chip varistors are manufactured by forming thick film conductors as external electrodes at both ends of a multilayer capacitor or varistor made of ceramic or the like.
As the composition for forming thick film conductors that do not contain lead becomes mainstream, components such as prismatic elements, cylindrical elements, disk-shaped capacitors, resistors, varistors, thermistors, inductors, etc. When the elements are arranged and fired at random, there is a problem in that the terminal electrode conductors of the elements are in contact with each other at the portion where they are in contact with each other. In the case of sintering bonding, a portion where the bonding is strong cannot be separated by a non-contact force such as an aligner but is separated by a mechanical force. However, when the separation is performed by mechanical force, a defect occurs in the peeled portion, which is a factor that deteriorates the yield.

  As one of the methods for preventing such adhesion between elements due to sintering, a method of aligning firing or coating with ceramic powder is employed. Although the alignment firing is performed by an automatic machine or manually, not only is misalignment easily caused, but also the processing amount is small and it takes time, and the yield is deteriorated. Also, the method of dusting with ceramic powder does not reduce the throughput and does not take time, so it does not deteriorate the yield, but it adheres to the conductor during the sintering process and cannot be separated, causing spots on the sintered surface It was also a factor.

  In order to solve this problem, it has been proposed to add a dendritic metal powder as a component of the conductive powder to roughen the surface of the electrode film and prevent the fired binding between the elements (for example, Patent Documents). 1). However, when the dendritic metal powder is added, the dispersibility of the metal powder is impaired in the thick film conductor forming composition, and when manufactured with a three-roll mill, the dendritic metal powder is rolled into a coarse flaky powder, such as screen clogging. It will cause problems.

Under such circumstances, there has been a strong demand for a practical thick film conductor forming composition that can easily prevent firing and bonding between elements without adding dendritic metal powder to the conductive powder.
JP 2005-197039

  In view of the above-mentioned problems of the prior art, the object of the present invention is to prevent the adhesion of elements to each other when forming a thick film conductor for terminal electrodes on an electronic component, and to prevent the element characteristics from being impaired. It is in providing the composition for membrane conductor formation, the formation method of a thick film conductor using the same, and the thick film conductor obtained.

  In order to solve the above-mentioned problems, the present inventor has conducted extensive research, and in a composition for forming a thick film conductor (hereinafter also referred to as a paste) obtained by mixing a conductive powder, an oxide powder, and an organic vehicle, the conductive powder As described above, by adding a specific amount of metal powder having a lower conductivity and a larger particle size to a conventionally used metal powder such as Ag, electronic components are randomly arranged and baked to form a terminal electrode on the device. When forming thick film conductors, it is possible to prevent sintering adhesion between elements while maintaining the characteristics of the fired film obtained, and even if elements are sintered to each other, the elements can be separated relatively easily The inventors have found that it is possible to complete the present invention.

  That is, according to the first invention of the present invention, a conductive powder (A) comprising a conductive powder (a1) having a high conductivity and a conductive powder (a2) having a conductivity lower than that of the conductive powder (a1). In the composition for forming a thick film conductor containing the product powder (B) and the organic vehicle (C), the conductive powder (a2) has an average particle size of 7 μm or more, and the content of the conductive powder (a2) However, it is 4.0-8.0 weight part with respect to 100 weight part of electrically conductive powder (a1), The composition for thick film conductor formation characterized by the above-mentioned is provided.

According to the second invention of the present invention, in the first invention, the conductive powder (a1) is at least one metal powder selected from Ag, Au, Cu, Pd, or Pt. A thick film conductor forming composition is provided.
According to a third aspect of the present invention, there is provided a thick film conductor-forming composition characterized in that, in the first or second aspect, the conductive powder (a1) has a melting point of 1100 ° C. or lower. The
Furthermore, according to the fourth invention of the present invention, in any one of the first to third inventions, the conductive powder (a1) has an average particle diameter of 1 to 7 μm. A composition is provided.

On the other hand, according to the fifth invention of the present invention, in the first invention, the conductive powder (a2) is at least one metal powder selected from Ni, W, or Mo. A conductor-forming composition is provided.
According to a sixth aspect of the present invention, there is provided the thick film conductor forming composition according to the fifth aspect, wherein the conductive powder (a2) has a melting point of 1300 ° C. or higher.
According to the seventh invention of the present invention, in the first, fifth or sixth invention, the conductive powder (a2) has an average particle size of 7 to 13 μm, and the thick film conductor forming composition is characterized in that Things are provided.
Furthermore, according to the eighth invention of the present invention, in the first invention, the content of each component is such that the conductive powder (A) is 45.0 to 100 parts by weight of the thick film conductor-forming composition. 90.0 parts by weight, 0.2 to 15.0 parts by weight of oxide powder (B), and 8.0 to 55.0 parts by weight of organic vehicle (C) A composition is provided.

  On the other hand, according to the ninth invention of the present invention, the composition for forming a thick film conductor according to any one of the first to eighth inventions is applied to an element of an electronic component, and then fired at 500 to 900 ° C. Thus, there is provided a method for forming a thick film conductor, wherein a conductive film for a terminal electrode is formed on an element.

On the other hand, according to the tenth aspect of the present invention, there is provided a thick film conductor obtained by the method according to the ninth aspect, wherein at least a part of the conductive powder (a2) protrudes from the surface of the conductive film for terminal electrodes. Is done.
According to an eleventh aspect of the present invention, there is provided the thick film conductor according to the tenth aspect, wherein the terminal electrode conductive film has a thickness of 10 to 20 μm.

  According to the composition for forming a thick film conductor of the present invention, it is possible not only to prevent sintering adhesion between conductors which are conductive films for terminal electrodes of an element, which has been difficult with the prior art, but also to have a sheet resistance and solder wettability. The adhesive strength can be maintained. As a result, the yield can be improved, the production cost can be reduced, and a product having excellent quality can be manufactured. Therefore, its industrial value is extremely large.

1. Thick film conductor forming composition The thick film conductor forming composition of the present invention comprises a conductive powder (a1) having a high conductivity and a conductive powder (a2) having a lower conductivity than the conductive powder (a1). In the composition for forming a thick film conductor containing the powder (A), the oxide powder (B), and the organic vehicle (C), the conductive powder (a2) has an average particle size of 7 μm or more, and the conductive powder The content of (a2) is 4.0 to 8.0 parts by weight with respect to 100 parts by weight of the conductive powder (a1).

A Conductive Powder In the present invention, the conductive powder (A) is composed of a conductive powder (a1) having a high conductivity and a conductive powder (a2) having an average particle size of 7 μm or more and a lower conductivity than the conductive powder (a1). A composite powder.

  The conductive powder (a1) is a metal powder having high dispersibility in the composition and having a high conductivity that becomes a dense film after paste firing. For example, it is at least one metal powder selected from Ag, Au, Cu, Pd, or Pt. Among these, Au powder or Ag powder, which is a noble metal material having a melting point of 1100 ° C. or lower, is preferable.

  The particle size of the conductive powder (a1) may be 10 μm or less, and the average particle size is preferably 1 to 7 μm, particularly preferably 1 to 5 μm. If the average particle size exceeds 7 μm, sintering adhesion may not be prevented. The shape may be granular or flaky, and is not particularly limited, but it is desirable to use a spherical or granular conductive powder which is a monodispersed system because the dispersibility is higher as it is closer to a sphere. The conductive powder (a1) can contain up to about 10 parts by weight of Ru, Sn, Zn or the like with respect to 100 parts by weight of the conductive powder (a1).

  On the other hand, the conductive powder (a2) is a metal powder having an average particle size of 7 μm or more and lower conductivity than the conductive powder (a1). Specifically, it is at least one metal powder selected from Ni, W, or Mo. The melting point of the conductive powder (a2) is more preferably 1300 ° C. or higher. The conductive powder (a2) has a relatively large average particle diameter of 7 μm or more, more preferably 7 to 13 μm.

  In the composition for forming a thick film conductor of the present invention, the conductive powder (a2) such as Ni having a large particle size is used in combination when a large number of elements are arranged and fired, and the surface of the film is substantially made of Ag powder. Although a flat surface is formed, if Ni powder or the like is present in the fired film, Ni itself does not sinter because of its high melting point, so a part of Ni powder or the like protrudes from the surface, and the element It is because it can prevent that the conductor used as the electrically conductive film for terminal electrodes adheres by sintering.

  If the melting point of the conductive powder (a2) is a metal having a temperature of 1300 ° C. or higher, the same result can be expected without being limited to Ni, W, and Mo. The average particle size must be 7 μm or more. When the average particle size is less than 7 μm, if the fired film thickness is greater than 10 μm, the film is easily buried and the effect of controlling the sintering adhesion is reduced. However, when the average particle size exceeds 13 μm, when applied by screen printing, the screen mesh is likely to be clogged, and the predetermined application shape may be damaged, or the thick film conductor forming composition may settle. Since the tendency to become easy is seen, it is not preferable.

  Moreover, content of electroconductive powder (a2) must be 4.0-8.0 weight part with respect to 100 weight part of electroconductive powder (a1). When the content of the conductive powder (a2) is less than 4 parts by weight, the amount of the conductive powder (a2) does not reach a sufficient amount for interspersing the surface of the fired film. On the other hand, if the amount is more than 8 parts by weight, the resistance value increases because the content of the conductive powder (a1) is small, the adhesive strength between the substrate and the conductor deteriorates, and the solder wettability deteriorates.

  The conductive powder (A) in the composition for forming a thick film conductor is desirably 45.0 to 90.0 parts by weight and preferably 45.0 to 85.0 parts by weight with respect to 100 parts by weight of the composition. When the conductive powder is less than 45.0 parts by weight, there is a problem that the state of the film after baking becomes porous, the film strength becomes brittle, and the resistance value becomes high. When the conductive powder exceeds 90.0 parts by weight, there is a problem in that the fluidity of the thick film conductor-forming composition is deteriorated and handling is deteriorated, and it is easy to dry and clogging of the printing screen.

B Oxide Powder In the present invention, the oxide powder is an inorganic oxide that imparts wettability to the coated surface.

  If it has such a function, a kind will not be specifically limited, The glass which has mainly used silicon oxide, aluminum oxide, lead oxide, calcium oxide, boron oxide etc. which are widely used for the thick film conductor conventionally. Frit can be used. In addition, magnesium oxide, barium oxide, strontium oxide, cadmium oxide, tin oxide, bismuth oxide, zirconium oxide, zinc oxide, or manganese oxide may be contained. However, in forming the conductor on the electronic component according to the present invention, since the thick film conductor is fired in the range of 500 to 900 ° C., it must be an oxide powder having a softening point in this temperature range.

Specifically, as the oxide, for example, SiO ₂ 25.0-35.0 parts by weight, Bi ₂ O ₃ 35.0-70.0 parts by weight, B ₂ O ₃ 3.0-13.0 parts by weight, Bismuth borosilicate glass in which Zn, alkali or alkaline earth is appropriately added to 0.1 to 10.0 parts by weight of Al ₂ O ₃ , or 4.0 to 20.0 parts by weight of SiO ₂ , PbO (30.0 to 70 0.0 part by weight), Al ₂ O ₃ 0.1 to 10.0 parts by weight, B ₂ O ₃ 10.0 to 52.0 parts by weight, Zn, alkali, and alkaline earth lead borosilicate glass appropriately added, etc. The oxide powder is mentioned. In order to improve solder wettability and adhesive strength, the amount of Bi ₂ O ₃ can be increased or CuO, ZnO, or MnO ₂ can be added to these. The average particle size of the oxide powder is desirably 10 μm or less. When the average particle diameter exceeds 10 μm, dispersibility and conductivity may be deteriorated.

  The oxide powder in the composition for forming a thick film conductor is desirably 0.2 to 15.0 parts by weight, and preferably 0.5 to 15.0 parts by weight with respect to 100 parts by weight of the composition. When oxide powder is less than 0.2 weight part, there exists a malfunction that the effect which increases adhesive strength is not acquired. When the oxide powder exceeds 15.0 parts by weight, there is a problem that the sintering of the conductive powder is hindered or excessively deposited on the film surface.

C Organic vehicle In the present invention, an organic vehicle comprising a resin component and a solvent component is a medium in which conductive powder and oxide powder are uniformly dissolved and dispersed, and is applied (printed) to an element of an electronic component, dried and fired. Sometimes, it has a function of separating the deposited oxide (slag).

  As the resin component, conventionally known ethyl cellulose, acrylic and the like can be used. The solvent component dissolves the resin component and has a function of stably dispersing the conductive powder and oxide powder in the paste. When applied (printed), the powder is uniformly spread and fired. By time, it must have the property of dissipating into the atmosphere. Terpineol, butyl carbitol acetate, etc. can be used.

  The organic vehicle in the composition for forming a thick film conductor is desirably 8.0 to 55.0 parts by weight and preferably 10.0 to 55.0 parts by weight with respect to 100 parts by weight of the composition. If the organic vehicle is less than 8.0 parts by weight, the particles of the conductive powder and oxide powder, which are inorganic components, cannot be encapsulated, and the fluidity of the composition is lacking, resulting in unstable quality and separation. There is a problem of doing. When the organic vehicle exceeds 55.0 parts by weight, there is a problem that it is separated from inorganic components after long-term storage.

2. Method for Forming Thick Film Conductor A method for forming a thick film conductor according to the present invention comprises applying the composition for forming a thick film conductor to an element of an electronic component, and then firing at 500 to 900 ° C. to form a terminal electrode on the element. A conductive film is formed.

That is, the above thick film conductor forming composition is applied or printed at a thickness of 10 to 50 μm, preferably 15 to 40 μm, on a portion to be a terminal electrode of an electronic component, dried at 100 to 150 ° C., and then fired. A thick film conductor is formed by heat treatment at 500 to 900 ° C. in a furnace. For example, the paste is screen-printed at the target location, dried with an infrared dryer at a peak temperature of 120 ° C. for 3 to 8 minutes, and heat-treated in a tunnel type belt firing furnace at a peak temperature of 800 to 900 ° C. for 5 to 15 minutes. do it.
When the firing temperature is less than 500 ° C., not only the organic vehicle is not sufficiently burned out, but also the conductive powder (a2) such as Ni may not protrude from the surface of the fired film. Since it may come out, it is not preferable.

3. Thick Film Conductor The thick film conductor of the present invention is a thick film conductor obtained by the above method, wherein at least a part of the conductive powder (a2) protrudes from the surface of the terminal electrode conductive film. The film thickness is preferably 10 to 20 μm.

  In the present invention, the conductive powder (A) comprises a conductive powder (a1) having a high conductivity and a conductive powder (a2) having an average particle diameter of 7 μm or more and a lower conductivity than the conductive powder (a1). Since the composition for forming a thick film conductor in which the content of the conductive powder (a2) is 4.0 to 8.0 parts by weight with respect to 100 parts by weight of the conductive powder (a1), the conductive powder (a2 ) Protrudes from the surface of the terminal electrode conductive film. As a result, when a large number of elements are baked side by side, even if they are in contact with each other and bonded, the conductive films (thick film conductors) of the elements become electronic parts that are point-contacted by the conductive powder (a2), so that they are easily separated .

Examples of the present invention and comparative examples are shown below, but the present invention is not limited to these examples.
The performance of the thick film conductor forming composition was measured and evaluated by the following method.

1) Adhesive strength measurement was carried out by adding 3.0 parts by weight of Ag-plated copper wire having a diameter of 0.65 mm on a 2.0 × 2.0 mm pad of a thick film conductor obtained by the composition for forming a thick film conductor. After soldering with a lead-free solder having a composition of 0.5 parts by weight of Cu-96.5 parts by weight of Sn, the tensile force at the time of pulling in the vertical direction and peeling was measured. If the measured adhesive strength is 50 N or more, it is judged that there is sufficient strength.
2) The area resistance value was converted by measuring the resistance value of a 0.6 × 60.0 mm line of the thick film conductor obtained by the thick film conductor forming composition. If the measured area resistance is 4.0 mΩ or less, it is judged to be good.
3) Solder wetting is 3.0 parts by weight Ag-0.5 part by weight Cu-96 in which a 10.0 × 10.0 mm pad of the thick film conductor obtained by the thick film conductor forming composition is held at 245 ° C. .5 parts by weight was immersed in a lead-free solder bath having a Sn composition for 5 seconds, and the appearance was observed.
4) Sintering adhesion of the conductor film is performed by stacking the 20.0 × 20.0 mm pads after drying, stacking four alumina substrates of the same shape on top of each other, applying a load of about 10 g and applying the peak temperature of 800 It was baked in a belt furnace for 9 minutes at 0 ° C. for a total of 30 minutes, and the presence or absence of sintered adhesion was confirmed.
5) Life confirmed the state 120 days after preparation of the composition for forming a thick film conductor from the viewpoints of separation, aggregation, and the like.
6) In order to confirm the particle size of the conductive powder, oxide powder, and inorganic oxide, a known particle size analyzer (for example, “Microtrack” registered trademark) was used. The average particle diameter indicates a D _50, which is the median value of the particle size in cumulative particle size distribution.

On the other hand, the following were used as components of the composition.
(A) Conductive powder Conductive powder (a1): Metal powder obtained by mixing granular Ag powder having an average particle diameter of 1.2 μm and flaky Ag powder having an average length in the flat direction of 5 μm at a ratio of 2: 1.
Conductive powder (a2): Ni powder having an average particle diameter of 5 μm, 10 μm, and 17 μm (referred to as Ni-a, Ni-b, and Ni-c, respectively), W powder having an average particle diameter of 10 μm (referred to as Wa), and average Each metal powder of Mo powder (referred to as Mo-a) having a particle size of 10 μm.
(B) oxide powder SiO ₂ 30.0 parts by _weight, Bi ₂ O 3 55.0 parts by _weight, B ₂ O 3 8.0 parts by _weight, Al ₂ O 3 4.0 parts by weight, CoO (1.0 wt Part), K ₂ O (1.0 part by weight), Li ₂ O (20 parts by weight) borosilicate having an average particle diameter of 3 μm and appropriately added Zn, alkali, and alkaline earth. Bismuth glass.
(C) Organic vehicle Resin component: A solution obtained by dissolving 3.0 parts by weight of ethyl cellulose having a molecular weight of 120,000 in 97.0 parts by weight of solvent component: terpineol.

[Example 1]
Conductive powder and oxide powder were added to an organic vehicle and dispersed and kneaded with a three-roll mill to produce the thick film conductor forming composition of the present invention. As shown in Table 1, 100.0 parts by weight of Ag powder, 1.0 part by weight of bismuth borosilicate glass, 8.0 parts by weight of Bi ₂ O ₃ and 4.0 parts by weight of Ni-b powder were blended. ing.
This thick film conductor forming composition was screen printed on a 96% alumina substrate and dried at 150 ° C. The dried substrate was baked in a belt furnace for 9 minutes at a peak temperature of 800 ° C. for a total of 30 minutes to form a thick film conductor film having a predetermined pattern, and a thick film conductor was obtained by the method described above. The resulting pattern is a 2.0 × 2.0 mm pad, 0.6 × 60.0 mm line, 10.0 × 10.0 mm pad, 20.0 × 20.0 mm pad.
Table 1 shows the results obtained for the film thickness, sheet resistance value, solder wettability, adhesive strength, and sintered adhesion between the conductors of this thick film conductor. The sheet resistance value was 4.0 mΩ or less, there was no sintered adhesion between the conductors, the solder wettability was good, and the adhesive strength was 50 N or more.

[Example 2]
A thick film conductor-forming composition was prepared in the same manner as in Example 1 except that the Ni-b powder content was 8.0 parts by weight, and a thick film conductor was obtained by the above method. The film thickness, sheet resistance value, solder wettability, adhesive strength, and sintered adhesion between conductors were measured and evaluated, and the results are shown in Table 1.
The sheet resistance value was 4.0 mΩ or less, there was no sintered adhesion between the conductors, the solder wettability was good, and the adhesive strength was 50 N or more.

[Example 3]
A thick film conductor forming composition was prepared in the same manner as in Example 1 except that 4.0 parts by weight of Wa powder was used instead of Ni-b powder, and a thick film conductor was obtained by the above method. . The film thickness, sheet resistance value, solder wettability, adhesive strength, and sintered adhesion between conductors were measured and evaluated, and the results are shown in Table 1.
The sheet resistance value was 4.0 mΩ or less, there was no sintered adhesion between the conductors, the solder wettability was good, and the adhesive strength was 50 N or more.

[Example 4]
A thick film conductor-forming composition was prepared in the same manner as in Example 1 except that 4.0 parts by weight of Mo-a powder was used instead of Ni-b powder, and a thick film conductor was obtained by the above method. . The film thickness, sheet resistance value, solder wettability, adhesive strength, and sintered adhesion between conductors were measured and evaluated, and the results are shown in Table 1.
The sheet resistance value was 4.0 mΩ or less, there was no sintered adhesion between the conductors, the solder wettability was good, and the adhesive strength was 50 N or more.

[Example 5]
A thick film conductor-forming composition was prepared in the same manner as in Example 1 except that 4.0 parts by weight of Ni-c powder having a large average particle size was used instead of Ni-b powder, and the thickness was increased by the above method. A membrane conductor was obtained. The film thickness, sheet resistance value, solder wettability, adhesive strength, and sintered adhesion between conductors were measured and evaluated, and the results are shown in Table 1. The sheet resistance value was 4.0 mΩ or more, and the solder wetting was not partially wet but at a level that would not cause a problem in practice. The adhesive strength was 25N or less. There was no sintered adhesion between the conductors.

[Comparative Example 1]
A thick film conductor-forming composition was prepared in the same manner as in Example 1 except that only the Ag powder was used as the conductive powder and no Ni-b powder was blended, and a thick film conductor was obtained by the above method. The film thickness, sheet resistance value, solder wettability, adhesive strength, and sintered adhesion between conductors were measured and evaluated, and the results are shown in Table 1.
The sheet resistance value was 4.0 mΩ or less, the solder wettability was good, and the adhesive strength was 50 N or more, but the sintered adhesion between the conductors was strong and could not be separated.

[Comparative Example 2]
A thick film conductor-forming composition was prepared in the same manner as in Example 1 except that 8.0 parts by weight of Ni-a powder having a small average particle size was used instead of Ni-b powder, and the thickness was increased by the above method. A membrane conductor was obtained. The film thickness, sheet resistance value, solder wettability, adhesive strength, and sintered adhesion between conductors were measured and evaluated, and the results are shown in Table 1. The sheet resistance value was 4.0 mΩ or more, and the solder wetting was not partially wet but at a level that would not cause a problem in practice. The adhesive strength was 50 N or less. The conductors were sinter-bonded and difficult to separate.

[Comparative Example 3]
A thick film conductor forming composition was prepared in the same manner as in Example 1 except that the blending amount of the Ni-b powder was reduced to 2.0 parts by weight, and a thick film conductor was obtained by the method described above. The film thickness, sheet resistance value, solder wettability, adhesive strength, and sintered adhesion between conductors were measured and evaluated, and the results are shown in Table 1.
The sheet resistance value was 4.0 mΩ or less, the solder wettability was good, and the adhesive strength was 50 N or more, but the sintered adhesion between the conductors was strong and could not be separated.

[Comparative Example 4]
A thick film conductor-forming composition was prepared in the same manner as in Example 1 except that the amount of Ni-b powder was increased to 10.0 parts by weight, and a thick film conductor was obtained by the method described above. The film thickness, sheet resistance value, solder wettability, adhesive strength, and sintered adhesion between conductors were measured and evaluated, and the results are shown in Table 1.
The sheet resistance value was 4.0 mΩ or more, the solder wettability was poor, and the adhesive strength was 25 N or less. There was no sintered adhesion between the conductors.

"Evaluation"
According to Examples 1 and 2, by adding Ni-b powder to Ag powder as conductive powder, sintering adhesion between conductors is prevented without degrading characteristics such as sheet resistance, solder wettability, and adhesive strength. It turns out that there is an effect. Although Example 3 and Example 4 were the cases where it replaced with W powder and Mo powder, maintaining the shape and content of Ni powder of Example 1, the equivalent effect was acquired. In Example 5, the particle size of the Ni powder that was effective in Example 1 was increased, but although there was an effect of preventing sintering adhesion between conductors, the sheet resistance value, solder wettability, and adhesive strength were slightly deteriorated. .

  Comparative Example 1 is a composition for forming a thick film conductor having a conventional composition and containing no conductive powder other than Ag. In Comparative Example 2, since Ni powder having a smaller particle diameter than that in Example 2 was used, the solder wettability and the adhesive strength were deteriorated, and there was no great effect on the sintering adhesion between the conductors. From Comparative Example 3, it can be seen that if the Ni-b powder is too small, no effect appears in the sintering adhesion between the conductors. It can be seen from Comparative Example 4 that if the Ni-b powder is too much, there is an effect of preventing the sintered adhesion between the conductors, but the sheet resistance value becomes large, the solder wettability is deteriorated, and the adhesive strength is also deteriorated.

Claims (11)

A conductive powder (A) comprising a conductive powder (a1) having a high conductivity and a conductive powder (a2) having a conductivity lower than that of the conductive powder (a1), an oxide powder (B), and an organic vehicle (C). In the composition for forming a thick film conductor,
The conductive powder (a2) has an average particle size of 7 μm or more, and the content of the conductive powder (a2) is 4.0 to 8.0 parts by weight with respect to 100 parts by weight of the conductive powder (a1). A composition for forming a thick film conductor.   The composition for forming a thick film conductor according to claim 1, wherein the conductive powder (a1) is at least one metal powder selected from Ag, Au, Cu, Pd, or Pt.   The composition for forming a thick film conductor according to claim 1 or 2, wherein the conductive powder (a1) has a melting point of 1100 ° C or lower.   The composition for forming a thick film conductor according to any one of claims 1 to 3, wherein the conductive powder (a1) has an average particle size of 1 to 7 µm.   The composition for forming a thick film conductor according to claim 1, wherein the conductive powder (a2) is at least one metal powder selected from Ni, W, or Mo. The melting point of conductive powder (a2) is 1300 degreeC or more, The composition for thick film conductor formation of Claim 5 characterized by the above-mentioned.
Item 2. The thick film conductor forming composition according to Item 1.   7. The thick film conductor-forming composition according to claim 1, wherein the conductive powder (a2) has an average particle size of 7 to 13 μm.   The content of each component is 45.0 to 90.0 parts by weight of the conductive powder (A) and 0.2 to 15% of the oxide powder (B) with respect to 100 parts by weight of the composition for forming a thick film conductor. The composition for forming a thick film conductor according to claim 1, wherein 0 part by weight and the organic vehicle (C) are 8.0 to 55.0 parts by weight.   The composition for forming a thick film conductor according to any one of claims 1 to 8 is applied to an element of an electronic component, and then fired at 500 to 900 ° C to form a conductive film for a terminal electrode on the element. A method of forming a thick film conductor.   A thick film conductor obtained by the method according to claim 9, wherein at least part of the conductive powder (a2) protrudes from the surface of the terminal electrode conductive film.   The film thickness of the conductive film for terminal electrodes is 10-20 micrometers, The thick film conductor of Claim 10 characterized by the above-mentioned.