JP2005174698A - Conductive paste and its utilization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide conductive paste for baked conductive film formation capable of forming a conductor line (fine line) having thick film thickness (for example 25 μm or more) and high shape-accuracy, even by one printing. <P>SOLUTION: This conductive paste contains silver powder of 80 mass% or more per 100 mass% corresponding to the whole of the paste, wherein the particle size of the silver powder is 1.2-1.5 μm, carbon black of 0.1-1. 0 pts. mass per the silver powder of 100 pts.mass, resin component (mixture of ethyl cellulose and maleic resin mixed in the mass ratio of 87.5:12.5) of the remaining portion, plasticizer (dioctyl phthalate) , and an organic solvent (butyl carbitol acetate), and has a viscosity of 500 Pa s or more which is measured by a rotational viscometer. The average particle size of the carbon black is preferably 20-50 nm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a conductor paste used for forming a fired film conductor (hereinafter referred to as “conductor film”) such as an electrode or a circuit on a ceramic substrate or other substrate. Specifically, the present invention relates to a conductor paste capable of forming a fired conductor film having high accuracy and a high film thickness by a single printing, and use thereof.

  Conductive paste is used as a material for forming a predetermined pattern of a fired conductive film (wiring, electrodes, etc.) on a wiring board or other electronic components used to construct a hybrid IC, a multichip module, or the like. In this conductive paste, metal powder as a main component forming a conductor and various additives (inorganic binder, glass frit, filler, etc.) added as necessary are dispersed in a predetermined organic medium (vehicle). Is a conductor forming material prepared by Such a conductor paste is printed (or applied) on a ceramic substrate or the like by a general method such as screen printing. Next, the coated material (coating film) is fired (baked) at an appropriate temperature, whereby a conductor film (hereinafter also referred to as a conductor line) having a predetermined pattern is formed on the ceramic electronic component such as the ceramic substrate. The

  In recent years, with the miniaturization and high precision of electronic components, it is desired to further improve the shape accuracy of conductor lines. However, it is difficult to accurately print (or apply) a conductor paste to a ceramic substrate or the like in a desired width, and the paste protrudes with a certain “sag width” from the desired print (or application) width. . For this reason, a conductor paste capable of forming a conductor line (also referred to as a fine line) with a small sagging width, that is, a high precision has been developed (see, for example, Patent Documents 1 to 6).

Japanese Patent Laid-Open No. 9-231834 JP 2002-42551 A JP 2002-194259 A JP 2002-197922 A JP 2002-216538 A JP 2003-223812 A

However, the conventional conductor paste as described in the above publication can reduce the sagging width, but it has been difficult to obtain a sufficient thickness by a single printing. If the film thickness is small, the strength may be reduced. For example, when a soldering electrode or the like is formed, there is a risk of solder erosion failure. In particular, in a conductor paste based on Ag (Ag paste), when a fine line having a line width of 100 μm or less is formed, a film thickness of about 25 μm is the limit. In order to increase the film thickness, printing (or application) is performed a plurality of times. In this case, however, the shape accuracy tends to decrease. This tendency is particularly remarkable when an Ag-based conductor paste is used. For this reason, a conductor paste capable of forming a highly accurate conductor line (fine line) with a thick film (for example, 25 μm or more, preferably 30 μm or more) is desired even with a single printing.
Accordingly, the present invention has been developed to solve such conventional problems, and is a conductor line that is thick (for example, 25 μm or more, preferably 30 μm or more) and has high shape accuracy even by single printing (or coating). It aims at providing the conductor paste for baking conductor film formation which can form (fine line). Another object of the present invention is to provide a method for forming a highly accurate fired conductor film (fine line) using such a conductor paste and a circuit board or other electronic material having a fine line obtained by the method. To do.

  The conductor paste according to the present invention is a conductor paste (Ag paste) containing Ag powder and an organic vehicle, and has the following conditions: (1) Ag powder having an average particle size of 1.2 to 1.5 μm as a main component And the content of the Ag powder in the whole paste is 80% by mass or more; (2) 0.1 to 1.0 part by mass of carbon black is included with respect to 100 parts by mass of the Ag powder; and (3) The viscosity measured by a rotary viscometer is at least 500 Pa · s (for example, 500 to 1500 Pa · s).

  In the conductor paste having such a configuration, a relatively thick and high-density film (line) can be formed on the substrate by setting the average particle diameter of the Ag powder as the conductor component within the above range. For this reason, a thick film conductor (for example, thickness of 25 μm or more) having sufficient strength can be obtained by one printing (or application). Therefore, it is not necessary to print (or apply) a plurality of times in order to improve the film thickness, and a reduction in shape accuracy can be prevented. Further, when the content of the Ag powder is in the above range, when printing (or coating) on a ceramic base material or the like, the “sag width”, that is, the paste from the preset printing (or coating) width is used. It is possible to reduce the width of the excess portion formed by protruding and further increase the printing (or coating) thickness.

Moreover, in the conductor paste having such a configuration, the sagging width can be extremely reduced by means of containing carbon black. In particular, when the amount of carbon black added is within the above range, the effect of reducing the sag width during printing (or application) is high, and a good fine line can be formed. In particular, the average particle size of carbon black added to the conductor paste is preferably in the range of 20 to 50 nm. When the average particle diameter of carbon black is within this range, the effect of reducing the sagging width at the time of printing (or coating) is particularly high, and a good fine line can be formed. Since carbon black is burned off by firing, it does not substantially affect the properties of the film-like conductor formed on the substrate, for example, conductivity and subsequent solder adhesion.
Furthermore, in the conductor paste having such a configuration, the viscosity (when measured) is within the above range. By being in this viscosity range, the fine line thickness can be increased, and the effect of reducing the sagging width can be further enhanced.
Therefore, by using a conductor paste that satisfies all of these conditions, even with a single printing (or application), it has a sufficient film thickness (for example, 25 μm or more, particularly 30 μm or more) A conductor line having a very small width (for example, 30 μm or less) and excellent shape accuracy can be formed.

  That is, according to the present invention, by using any of the conductor pastes disclosed herein, a line having a predetermined pattern is printed on the base material, and the film is baked to thereby form a film thickness on the base material. There is provided a method of forming a fired conductor film (conductor line) having at least 25 μm and a sagging width of 30 μm or less. The printing is easily performed by screen printing.

  Hereinafter, preferred embodiments of the present invention will be described. It should be noted that matters other than matters specifically mentioned in the present specification (for example, Ag powder, carbon black, paste viscosity, etc.) and matters necessary for carrying out the present invention (for example, various paste printing methods, The baking method of the paste print product) can be grasped as a design matter of those skilled in the art based on the prior art in the field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  The “Ag powder” constituting the conductor paste of the present invention is typically composed of Ag (silver) alone, but may be an Ag-based alloy. Ag powder is available at low cost and has low electrical resistance as compared with gold powder, platinum powder and the like. For this reason, it can use suitably as an electroconductive powder in a conductor paste. The Ag paste disclosed here is particularly suitable for use in forming a direct soldering electrode (required to be a thick film) of an electronic component such as a multilayer ceramic substrate (LTCC or the like).

  As the Ag powder, those having an average particle diameter of 1.2 to 1.5 μm are particularly preferably used. If the average particle size of the Ag powder is smaller than this range, the thickness of the formed conductor pattern tends to be thin. On the other hand, if the average particle size is larger than this range, the fine line forming ability decreases, that is, the sagging width increases. Tend to. The shape of the powder constituting the Ag powder is not particularly limited, and a spherical shape, a flake shape, a conical shape, a rod shape, or the like can be used. Spherical and / or flake-like particles are preferably used for reasons such as easy filling and good formation of a dense conductor film.

In the present specification, the “average particle diameter” refers to D ₅₀ (median diameter) in the particle size distribution of the powder. Such D ₅₀ is, for example, can be easily measured by a conventionally known laser diffraction method, the particle size distribution measurement apparatus based on light scattering method or the like.

  The method for producing Ag powder having such an average particle size is not particularly limited. For example, Ag powder (typically a powder consisting of Ag alone) produced by a known wet reduction method, gas phase reaction method, gas reduction method or the like can be classified and used as necessary. Such classification can be performed using, for example, a classification device using a centrifugal separation method.

  In the practice of the present invention, the content of the Ag powder is such that the content of the whole paste is approximately 80% by mass or more, particularly about 80 to 98% by mass, more preferably about 83 to 98% by mass, for example about 83 to 95% by mass. Or it is preferable to adjust so that it may become about 85-90 mass%. When the Ag powder content in the manufactured conductor paste is as described above, the denseness of the obtained film is further improved, the printing (or coating) thickness is increased, and the sagging width can be reduced.

  As the “carbon black” constituting the conductor paste of the present invention, any available carbon black can be used, and there are no particular restrictions on the raw materials and the means for obtaining the carbon black. For example, any of furnace black, lamp black, thermal black, channel black, roll black, disk black, and the like can be used without particular limitation. Of these, furnace black, such as ketjen black, is preferred. The average particle size is not particularly limited as long as the fine line forming ability is not impaired, but is preferably 1 to 500 nm, more preferably 5 to 100 nm, and particularly 20 to 50 nm.

  In carrying out the present invention, the Ag powder is taken as 100 parts by mass, 0.1 to 1.0 part by mass, particularly 0.3 to 1.0 part by mass, and further 0.3 to 0.8 part by mass, for example 0 It is preferable to adjust the content (composition ratio) of carbon black so that 5 to 0.8 parts by mass is carbon black. When the carbon black content in the produced conductor paste is as described above, the effect of reducing the sagging width is particularly excellent. That is, when the carbon black content is less than this range, the sagging width reduction effect tends to decrease, whereas when the carbon black content is greater than this range, the conductor paste after firing The denseness of the conductor pattern tends to decrease and the properties such as conductivity tend to decrease.

  Next, the “organic vehicle” constituting the conductor paste of the present invention is not particularly limited as long as it can disperse the Ag powder well, and those used in conventional conductor pastes can be used without any particular limitation. . For example, petroleum hydrocarbons (particularly aliphatic hydrocarbons) such as butyl carbitol acetate (BCA), butyl carbitol (BC), terpineol and mineral spirits, cellulose polymers such as ethyl cellulose, ethylene glycol and diethylene glycol derivatives, toluene A high boiling point organic solvent such as xylene can be used singly or in combination. Of these, butyl carbitol acetate, terpineol, and a mixed solution of terpineol and butyl carbitol (for example, a molar ratio of 1: 1) are preferable, and butyl carbitol acetate is particularly preferable in order to reduce the sagging width. Although not particularly limited, the content of the organic vehicle is preferably about 20% by mass or less of the entire paste, for example, about 2 to 20% by mass, particularly about 2 to 17% by mass, for example about 5 to 17% by mass or An amount of about 7-15% by weight is preferred.

In addition to the solvent, the organic vehicle can contain various “resin components” for the purpose of adjusting the viscosity of the paste. In the practice of the present invention, it is preferable that the resin component is capable of imparting coating film (adhesive film to the base material) forming ability to the conductive paste, and those used in the conventional conductive paste for such purposes are particularly preferred. Can be used without restriction. Examples thereof include those mainly composed of a cellulose polymer, a maleic acid resin, an acrylic resin, an epoxy resin, a phenol resin, an alkyd resin, a polyvinyl alcohol, a rosin resin, and the like. Of these, cellulosic polymers (for example, ethyl cellulose), maleic resin, or a combination of two or more of these are preferred, and are particularly determined by the loss of paste (for example, the frequency of line loss caused by mask removal during printing). A combination of a cellulosic polymer (such as ethyl cellulose) and a maleic acid resin is preferable. Although there is no particular limitation, the content of the resin component is suitably about 0.1 to 5 parts by mass, preferably 0.5 to 2 parts by mass, particularly preferably 1 with respect to 100 parts by mass of the Ag powder. ˜2 parts by mass. When the content of the resin component is within this range, the effect of reducing the sagging width during printing (or application) is further improved.
The numerical ranges relating to the content of each component should not be strictly interpreted, and allow a slight deviation from such ranges as long as the object of the present invention can be achieved.

  Further, the conductor paste can contain various additives as subcomponents as long as the original conductivity of the conductor film formed from the paste and the effect of the present invention, that is, the shape accuracy of the conductor line are not significantly impaired. . For example, the viscosity of the conductor paste can be adjusted using a viscosity modifier such as a plasticizer or a thickener as such an additive. As such a viscosity modifier, for example, plasticizers well known in the field of conductor pastes such as dioctyl phthalate (DOP), dioctyl adipate (DOA), dibutyl phthalate (DBP) can be used. Among these, dioctyl phthalate (DOP) which improves printability (for example, drying property and leveling property) is particularly preferable. Such a viscosity modifier is preferably contained in the conductor paste at a rate of approximately 5 parts by mass or less (typically approximately 0.1 to 5 parts by mass), with the Ag powder being 100 parts by mass, More preferably, it is 3 parts by mass or less (typically about 0.5 to 3 parts by mass), and further preferably 2 parts by mass or less (typically about 1 to 2 parts by mass).

  In addition, the conductor paste of the present invention can contain various inorganic additives and / or organic additives as long as the object of the present invention can be achieved. Examples of the inorganic additive include glassy and other ceramic powders and other various fillers. Moreover, as an example of an organic additive, various coupling agents, such as a silicon type, a titanate type, and an aluminum type, aiming at the adhesive improvement with a ceramic base material are mentioned. Further, when it is desired to impart photocurability (photosensitivity) to the conductor paste of the present invention, various photopolymerizable compounds and photopolymerization initiators may be appropriately added.

  In addition to the above, the conductor paste of the present invention can appropriately contain additives such as a surfactant, an antifoaming agent, an antioxidant, a dispersing agent, and a polymerization inhibitor as necessary. These additives only need to be used for the preparation of conventional conductor pastes, and detailed description thereof is omitted.

  Further, the viscosity of the conductor paste of the present invention is 500 Pa · s or more (for example, 500 to 1500 Pa · s), preferably 750 Pa · s or more (for example, 750 to 1500 Pa · s), particularly 800 Pa · s, under the above measurement conditions. It can be set above (for example, 800 to 1200 Pa · s). The viscosity of the conductor paste can be changed as desired by appropriately selecting the molecular weight of the organic vehicle, the type and content of the viscosity modifier, and the like.

  The conductor paste of the present invention can be easily prepared typically by mixing the Ag powder, the organic solvent (vehicle), and the carbon black, similarly to the conventional conductor paste. At this time, it is preferable to add and mix the above-described additives (resin component, plasticizer, etc.) as necessary. For example, using a three-roll mill or other kneader, the Ag powder, the carbon black, and various additives are directly mixed and stirred together with an organic solvent (vehicle) at a predetermined blending ratio, and then kneaded together. Inventive conductor pastes can be prepared.

  Next, the suitable example which concerns on conductor film (conductor line) formation using the conductor paste of this invention is demonstrated. The conductor paste of the present invention is the same as the conductor paste conventionally used for forming conductor films such as wiring and electrodes on ceramic base materials (fired alumina substrate, fired zirconia substrate, etc.) and other base materials. It can be handled and a conventionally known method can be employed without any particular limitation. Typically, the conductor paste is applied (attached) to the base material by a screen printing method, a dispenser coating method, a dip coating method or the like (particularly preferably a screen printing method) so as to have a desired shape and thickness. Next, preferably after drying, the coating is performed by heating for a predetermined time in a heater under appropriate heating conditions (when a ceramic substrate is used, the maximum firing temperature is approximately 500 to 1000 ° C., preferably 600 to 900 ° C.). The paste component obtained is fired (baked) and cured. By performing this series of processes, a ceramic electronic component {for example, an electronic component such as a low-temperature fired multilayer substrate (LTCC)} on which a target conductor film (wiring, electrode, etc.) is formed is obtained. Furthermore, a more advanced ceramic electronic component can be obtained by applying a conventionally known construction method while using the ceramic electronic component as an assembly material. Note that the construction method itself does not particularly characterize the present invention, and a detailed description thereof will be omitted.

  The conductor paste of the present invention is excellent in the performance of forming a conductive pattern having a thick film and excellent shape accuracy. For this reason, for example, it has a portion in which a plurality of linear conductor films are formed substantially in parallel, and the width (line width) of these linear conductor films is approximately 200 μm or less (typically about 30 to 200 μm). The linear conductor film has an interval (line interval) of about 200 μm or less (typically about 30 to 200 μm), and is suitable for use in forming a fired conductor pattern. It is also suitable for use in forming a conductor pattern having a line width of about 30 to 150 μm (more preferably about 50 to 100 μm) and a line interval of about 30 to 150 μm (more preferably about 50 to 100 μm). .

  Moreover, the conductor paste of this invention can make the thickness by one printing (or application | coating) especially 25 micrometers or more, for example, 30 micrometers or more in a preferable aspect. Further, the sagging width can be suppressed to 30 μm or less, preferably 20 μm or less, particularly 10 μm or less. For this reason, it is possible to obtain a conductor line with a small sagging width while having a sufficient thickness even if printing (or application) is performed once.

<Examples and Comparative Examples>
Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples.
[Manufacture of conductor paste]
Each component used in the following Example 1 and Comparative Examples 1-3 is listed below.
(1) Ag powder Silver powder A: Average particle diameter (D ₅₀ ) is 0.4 μm.
Silver powder B: An average particle size (D ₅₀ ) of 1.2 μm.
In addition, all of these silver powders can be obtained by classifying what was produced by the general wet reduction method with a centrifuge. These silver powders have a substantially spherical shape. The value of the average particle diameter (D ₅₀ ) of each silver powder was measured using a laser diffraction / scattering particle size distribution measuring device manufactured by Horiba, Ltd., model name “LA-920”.
(2) Organic solvent ・ Butyl carbitol acetate (BCA)
(3) Resin component-87.5: 12.5 mass ratio mixture of ethyl cellulose and maleic resin (4) Plasticizer-Dioctyl phthalate (DOP)
(5) Additives • Carbon black {furnace black (conductive furnace, specifically ketjen black), average particle size: about 30 nm}
·graphite

(Example 1)
In a total of 100% by mass of the paste, 1.5 parts by mass of a resin component (ethyl cellulose and maleic resin) with respect to 85% by mass of silver powder B having an average particle diameter (D ₅₀ ) of 1.2 μm and 100 parts by mass of silver powder B Mixture), 1.5 parts by mass of plasticizer (DOP), 0.5 parts by mass of carbon black, and the balance (about 12% by mass of the total paste) of BCA. BCA was added to silver powder B and kneaded using a three-roll mill. Furthermore, a resin component (mixture of ethyl cellulose and maleic acid resin), DOP, and carbon black were added and kneaded. Thereby, the conductor paste which concerns on a present Example was prepared.

(Comparative Example 1)
In Example 1, a conductor paste was produced in the same manner as in Example 1 except that 0.5 parts by mass of graphite was added to 100 parts by mass of silver powder B instead of carbon black.

(Comparative Example 2)
3 parts by mass of a resin component (mixture of ethyl cellulose and maleic resin) with respect to 85 parts by mass of silver powder A having an average particle diameter (D ₅₀ ) of 0.4 μm and 100 parts by mass of silver powder A in a total of 100% by mass of the paste ), 1.5 parts by mass of plasticizer (DOP), 0.5 parts by mass of carbon black, and the balance (about 11% by mass of the entire paste) of BCA. BCA was added to silver powder A and kneaded using a three-roll mill. Furthermore, a resin component (mixture of ethyl cellulose and maleic acid resin), DOP, and carbon black were added and kneaded. Thereby, the conductor paste which concerns on this comparative example was prepared.
(Comparative Example 3)
A conductor paste was produced in the same manner as in Comparative Example 2 except that no carbon black was added in Comparative Example 2.

[Performance evaluation of conductor paste]
The performance of the conductor paste obtained in Example 1 and Comparative Examples 1 to 3 was tested. For the following (1), (2), (4) to (8), a conductor film obtained by printing a conductor paste on a ceramic (alumina) substrate by a general screen printing method and then drying it. It is performance evaluation about. The test method is as follows.
(1) Sag width (μm)
The printing line is 100 μm, and as shown in FIG. 1, the sagging width Ld (μm) is calculated from the measured line width Lr (μm) of the outer edge 10 of the formed conductor film with respect to the opening diameter Lo (μm) of the mask used. Is obtained by the following equation.
Ld = (Lr−Lo) / 2
(2) Printing thickness (μm)
The thickness of the obtained conductor film was measured with an electron microscope with a printing line of 100 μm.
(3) Viscosity (Pa · s)
The viscosity of the conductor paste was measured at 25 ° C. using a No. 4 spindle (spindle 4-14) with a Brookfield rotary viscometer (model name “HBT type DV III +”) under a measurement condition of 10 rpm. .
(4) Printability The shape of the line when the printing line was 100 μm and the space was 100 μm was visually observed. The case where there was no undulation (that is, the irregularities on the outer edge of the line) was evaluated as ◎, the case where the undulation was in a very small part, ○, the case where there was a small amount of undulation, and the case where many undulations were observed.

(5) Detachability Line defects were visually observed when the printing line was 100 μm and the space was 100 μm. The case where there was no chipping on the line was evaluated as ◎, the case where there was a chipping in a very small part, the case where there was a small amount of chipping, Δ, and the case where many chippings were observed was evaluated as x.
(6) Solder wettability After applying rosin flux to the conductor film portion of each ceramic substrate, the substrate was soldered at a predetermined temperature (here, Sn / Pb = 60/40 (mass ratio)). The same effect can be obtained even if solder is applied). Here, the solder temperature condition and the immersion time were set to 230 ° C. × 3 seconds. The solder wettability was evaluated by the area ratio of the conductor film remaining on the ceramic substrate after the immersion as compared with that before the immersion.
(7) Solder erosion Solder temperature conditions and immersion time: 230 ° C. × 3 seconds were repeated three times by the same means as the solder wettability. The solder erosion property was evaluated by the area ratio of the “solder erosion” portion, that is, the conductor film, which decreased from the ceramic substrate after the immersion, compared with that before the immersion.
(8) Adhesive strength (N / 2mm)
As shown in FIG. 2, after applying a rosin flux to the conductor film portion 23 of each ceramic substrate 21 and sandwiching a lead wire 25 having a diameter of about 0.6 mm, the substrate 21 is soldered to a solder 27 (in this case, Sn). / Pb = 60/40 (mass ratio) was used, but the same effect can be obtained by applying so-called Pb-free solder). After the immersion, the lead wire 25 was pulled, and the force N necessary for peeling the ceramic substrate 21 and the conductor film (2 mm) 23 was measured.

  The evaluation results of Example 1 and Comparative Examples 1 to 3 are shown in Table 1.

From the results in Table 1, the following can be understood. That is, when Example 1 and Comparative Example 1 were compared, the effect of reducing the sagging width was not observed when graphite was used instead of carbon black. It can also be seen that the printability and detachability are reduced. For this reason, it turns out that carbon black is excellent in the sagging width reduction effect. That is, it can be seen that the sagging width during printing is significantly reduced by including carbon black in Example 1. Also, printability is improved.
Further, when Example 1 and Comparative Example 2 are compared, in Comparative Example 2, since the average particle diameter of the silver powder is 0.4 μm, the sagging width is very good at 0, but the printing thickness is 17 μm. Thus, a sufficient film thickness is not obtained. On the other hand, in Example 1, the average particle diameter of the silver powder is 1.2 μm, and the content of the resin component is 1.5 parts by mass with respect to 100 parts by mass of the silver powder. It turns out that it is improving. For this reason, it is possible to form a thick and highly accurate conductor line by a single screen printing.
Furthermore, in Comparative Example 3, since the average particle diameter of the Ag powder was 0.4 μm and no carbon black was contained, a satisfactory film thickness could not be obtained.
It should be noted that there was no particular change in other characteristics, that is, solder wettability, solder erosion property, and adhesive strength due to containing Ag powder or carbon black having an average particle diameter in a predetermined range.

(Example 2)
A conductor paste was prepared in the same manner as in Example 1 except that the amount of carbon black to be added was changed to 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the silver powder.
(Example 3)
A conductor paste was prepared in the same manner as in Example 1 except that the average particle size of the carbon black to be added was changed to 30 to 1000 nm.
Table 2 shows the results of Example 2 and Table 3 shows the results of Example 3 with respect to the sagging width and printing thickness.

  As is apparent from Table 2, when the amount of carbon black added exceeds 1.0 part by mass with respect to 100 parts by mass of the silver powder, the conductor line is inferior in density and therefore inferior in conductivity and cannot be used. It was. On the other hand, when the addition amount of carbon black is 0.1 to 1.0 part by mass with respect to 100 parts by mass of the silver powder, the compactness of the conductor line is good and the sagging width reduction effect. It can be seen that it is excellent, particularly 20 μm or less. Further, as apparent from Table 3, when the average particle size of the carbon black is 50 μm or less (here, 30 to 50 nm), the sagging width reduction effect is remarkably excellent, and is particularly suppressed to 10 μm or less. I understand that.

  The preferred embodiments of the present invention have been described in detail above, but these are only examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the above-described embodiments. In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

  The conductor paste according to the present invention can be used without particular limitation in order to form a conductor film such as a wiring or an electrode on a ceramic substrate (alumina substrate, zirconia substrate, etc.) or other substrate. That is, it is suitable for use in manufacturing an electronic component having such a conductor pattern. For example, it can be suitably used for external electrodes and terminal electrodes that are suitable for thick film formation, particularly external electrodes.

Explanatory drawing of the droop width | variety measuring method of the conductor film obtained in the Example. Explanatory drawing of the adhesive strength measuring method of the conductor film obtained in the Example.

Explanation of symbols

21 ... Ceramic substrate 23 ... Conductor film part 25 ... Lead wire 27 ... Solder

Claims (4)

A conductor paste for forming a fired conductor film comprising Ag powder and an organic vehicle, the following conditions:
(1) Average particle diameter: Ag powder of 1.2 to 1.5 μm as a main component, and the content of Ag powder in the whole paste is 80% by mass or more;
(2) 0.1 to 1.0 part by mass of carbon black is included with respect to 100 parts by mass of Ag powder; and (3) the viscosity measured by a rotary viscometer is at least 500 Pa · s;
A conductor paste comprising any of the above. The conductor paste according to claim 1, wherein the carbon black has an average particle size in a range of 20 to 50 nm. The conductor paste according to claim 1 or 2 is used to print a line having a predetermined pattern on the base material and to fire it, whereby the film thickness is at least 30 μm and the sagging width is 30 μm or less. A method of forming a fired conductor film. The method according to claim 3, wherein the printing is performed by screen printing.

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