JP2005268204A - Conductive paste and ceramic electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the plating properties and the denseness of a conductive membrane serving as the external conductor, and enable easily mounting of ceramic electronic components on circuit board, moreover without causing bursting of the external conductor. <P>SOLUTION: This conductive paste contains conductive powders composed of mixed powders of spherical Ag powders, having 0.5 to 1.0 μm average particle diameter and flat shaped Ag powders, having 1.5 to 5.0 μm average particle diameter, 5 to 70 aspect ratio and 1/4 to 4 mixing ratio of weight, and glass powders, composed of borosilicate alkaline glass which are blended so that B<SB>2</SB>O<SB>3</SB>is 10 wt% or higher and 31 wt% or lower, SiO<SB>2</SB>is 65 wt% or higher and 86 wt% or lower, and M<SB>2</SB>O (here, M is an alkali metal element) is higher than 0.5 wt% and lower than 5 wt%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a conductive paste and a ceramic electronic component, and more particularly to a conductive paste used as an outer conductor of a ceramic electronic component, and a ceramic electronic component such as a multilayer ceramic capacitor manufactured using the conductive paste. .

  In a ceramic electronic component such as a multilayer ceramic capacitor, generally, a conductive paste for forming an external conductor is applied to both ends of a ceramic body, dried, and then fired. The outer conductor is plated with Ni, Sn, solder or the like for the purpose of improving solder wettability and solder heat resistance.

  As the conductive paste for forming the outer conductor, a paste obtained by dispersing conductive powder such as Ag, Ag-Pd, Cu and glass powder (glass frit) in an organic vehicle is used. A technique using zinc borosilicate glass as a glass powder has been proposed (for example, Patent Documents 1 and 2).

JP 59-184511 A JP-A-6-349313

  However, in Patent Documents 1 and 2, the outer conductor is formed using a conductive paste containing zinc borosilicate glass. However, zinc borosilicate glass generally has a low softening point and is subjected to a firing treatment. In this case, the glass component moves to the surface of the outer conductor or the interface between the outer conductor and the ceramic body, and therefore pores are easily formed inside the outer conductor. In addition, if the glass component moves to the surface of the outer conductor and the surface is covered with the glass component, the plating property to the outer conductor is deteriorated even if plating is performed in a later step, and the desired solder wettability. There is a problem that heat resistance cannot be ensured.

  In addition, if pores exist inside the outer conductor, the plating solution is likely to enter the outer conductor during the plating process, and the adhesive strength between the outer conductor and the ceramic body is reduced. there were.

  Ceramic electronic components are usually mounted on a circuit board and used. However, zinc borosilicate glass powder with a low softening point is easy to dissolve in the plating solution. There is a problem in that the moisture of the gas may vaporize and expand due to heating during component mounting, resulting in explosion of the outer conductor.

  The present invention has been made in view of such problems, and can improve the plating property and denseness of the conductor film serving as the outer conductor, and without causing explosion of the outer conductor, the ceramic electronic component It is an object to provide a conductive paste that can be easily mounted on a circuit board, and a ceramic electronic component manufactured using the conductive paste.

  The present inventor conducted intensive research to achieve the above object, and prepared a spherical powder having a specific average particle diameter and a flat powder having a specific average particle diameter / shape at a specific ratio. By using a conductive powder and forming an outer conductor of a ceramic electronic component using a conductive paste containing the conductive powder and an alkali borosilicate glass having a specific component composition, it is possible to obtain a high plating density and a high density. It has been found that a conductive paste capable of forming an outer conductor that does not explode even when heat-treated during mounting on a circuit board can be obtained.

The present invention has been made based on such knowledge, and the conductive paste according to the present invention is a conductive paste containing a conductive powder, a glass powder, and an organic vehicle. A spherical powder having a particle size of 0.5 to 1.0 μm and a ratio of a maximum diameter to an average thickness (hereinafter referred to as “aspect ratio”) of 5 to 70 with an average particle size of 1.5 to 5.0 μm. In addition, the glass powder is blended so that the ratio of the spherical powder to the flat powder is 1/4 to 4 by weight, and the glass powder is 10% by weight or more. 31 wt% or less of B ₂ O ₃ , 65 wt% or more and 86 wt% or less of SiO _2, and more than 0.5 wt% and less than 5 wt% of M ₂ O (where M is an alkali metal element) Made of contained borosilicate alkali glass It is characterized by that.

  The conductive paste of the present invention is characterized in that the conductive paste contains Ag as a main component.

  The ceramic electronic component according to the present invention is characterized in that the outer conductor formed on the surface of the ceramic body is made of a sintered body of the conductive paste.

  The ceramic electronic component according to the present invention is characterized in that an inner conductor is embedded in the ceramic body and the inner conductor is electrically connected to the outer conductor.

According to the conductive paste, the conductive powder includes a spherical powder having an average particle size of 0.5 to 1.0 μm, an average particle size of 1.5 to 5.0 μm, and an aspect ratio of 5 to 5. The mixture is composed of a mixed powder of 70 flat powders, and is blended so that the ratio of the spherical powder to the flat powder is 1/4 to 4 by weight, and the glass powder is 10% by weight. 31 wt% or less of _B 2 _{O 3} compound above, and SiO ₂ of 65 wt% or more 86 wt% or less, less than 5% by weight greater than 0.5 wt% _M 2 O (provided that, M an alkali metal element) As a result, it is possible to obtain a conductive film with good plating properties and fineness without forming pores inside the conductive film or intruding the plating solution into the conductive film. , A conductor with excellent solder wettability, heat resistance, and mechanical strength A film can be obtained.

  Moreover, according to the ceramic electronic component of the present invention, the outer conductor formed on the surface of the ceramic body is made of the sintered body of the conductive paste, so that an outer conductor having good plating property and denseness is obtained. Therefore, it is possible to easily form a plating film having a desired film thickness on the surface of the outer conductor and to provide a highly reliable ceramic electronic component in which the plating solution does not enter the outer conductor. Can be obtained.

  According to the ceramic electronic component of the present invention, the inner conductor is embedded in the ceramic body, and the inner conductor is electrically connected to the outer conductor. Therefore, it is possible to prevent the plating solution from entering the interface between the ceramic layer and the inner conductor, causing delamination at the interface between the ceramic layer and the inner conductor, and generating cracks in the ceramic body. Therefore, it is possible to obtain a ceramic electronic component such as a multilayer ceramic capacitor having excellent reliability.

  Next, an embodiment of the present invention will be described in detail.

  The conductive paste according to one embodiment of the present invention includes a conductive powder composed of a mixed powder of spherical Ag powder and flat Ag powder and a glass powder composed of alkali borosilicate glass dispersed in an organic vehicle. It becomes.

  The spherical Ag powder has an average particle size of 0.5 to 1.0 μm, the flat Ag powder has an average particle size of 1.5 to 5.0 μm, an aspect ratio of 5 to 70, and a flat shape. The mixing ratio of the spherical Ag powder to the Ag powder (spherical Ag powder / flat Ag powder) is blended so as to be 1/4 to 4 in weight ratio.

Further, the glass powder includes 10% by weight or more and 31% by weight or less B ₂ O ₃ , 65% by weight or more and 86% by weight or less SiO _2, and more than 0.5% by weight and less than 5% by weight M ₂ O. (M is an alkali metal element such as K, Li, Na, etc.).

That is, the glass powder is
10% by weight ≦ B ₂ O ₃ ≦ 31% by weight
65% by weight ≦ SiO ₂ ≦ 86% by weight
0.5 wt% _<M 2 O _<5 wt%
It is formulated to satisfy.

  Then, the conductive paste is applied to an object to be coated such as a ceramic body, dried, and then subjected to a firing treatment, whereby a conductor having excellent plating strength and denseness and excellent mechanical strength such as tensile stress. A membrane can be obtained.

  Hereinafter, the reason why the average particle diameter, the aspect ratio, the mixing ratio, and the component composition of the glass powder of the spherical Ag powder and the flat Ag powder are limited as described above will be described in detail.

Average particle diameter of spherical Ag powder and flat Ag powder When conductive paste containing Ag powder is applied to the surface of an object to be coated, such as a ceramic body, and then fired to produce a conductor film When the average particle size of the spherical Ag powder is less than 0.5 μm and the average particle size of the flat Ag powder is less than 1.5 μm, the average particle size becomes too small, so that the sinterability of the conductor film is reduced. As a result, the conductor film is cracked and the plating property is deteriorated. In addition, the denseness also decreases, and the plating solution may enter the conductor film, and the plating solution that has entered the conductor film due to the heat treatment during mounting on the circuit board may vaporize and expand and explode.

  On the other hand, when the average particle diameter of the spherical Ag powder is 1.0 μm and the average particle diameter of the flat Ag powder exceeds 5.0 μm, the average particle diameter becomes too large, and the conductor film is sintered. As described above, the plating solution penetrates into the conductor film, and enters the conductor film (external conductor) by heat treatment during mounting on the circuit board, as described above. May vaporize, expand, and explode.

  Therefore, in the present embodiment, powder particles having an average particle size of spherical Ag powder of 0.5 to 1.0 μm and an average particle size of flat Ag powder of 1.5 to 5.0 μm are used.

(2) Aspect ratio Conductive powder composed of a mixture of flat Ag powder and spherical Ag powder contributes to improving the plating properties and denseness of the conductor film, but the aspect ratio of the flat Ag powder is less than 5. Then, the maximum diameter of the flat Ag powder becomes relatively small, and the sinterability of the conductor film is excessively promoted. As a result, the conductor film is cracked and the plating property is lowered. In addition, since the denseness also decreases, the plating solution may enter the conductor film, and the plating solution that has entered the conductor film due to heat treatment during mounting on the circuit board may vaporize and expand and explode.

  On the other hand, when the aspect ratio of the flat Ag powder exceeds 70, the maximum diameter of the flat Ag powder becomes relatively large, so that the sinterability of the conductor film is deteriorated, so that the denseness is lowered and the plating solution is reduced. May penetrate into the conductor film, and the plating solution that has entered the conductor film (external conductor) may vaporize and expand and explode due to the heat treatment during mounting on the circuit board.

  Therefore, in this embodiment, the aspect ratio of the flat Ag powder is set to 5 to 70.

(3) Mixing ratio As described above, the conductive powder made of the mixed powder of the spherical Ag powder and the flat Ag powder contributes to improving the plating property and the denseness of the conductor film. If the mixing ratio of spherical Ag powder (spherical Ag powder / flat Ag powder) is less than ¼ by weight, the content of the flat Ag powder becomes relatively large, and the sinterability of the conductor film is reduced. As a result, the denseness decreases and the plating solution penetrates into the conductor film, and the plating solution that penetrates into the conductor film due to heat treatment during mounting on the circuit board may vaporize and expand and explode. is there.

  On the other hand, when the mixing ratio exceeds 4 by weight, the content of the flat Ag powder becomes too small, and therefore, the plating property and the denseness deteriorate, and the conductor film may explode when mounted on the circuit board. There is.

  Therefore, in the present embodiment, the mixing ratio is set to ¼ to 4 by weight.

(4) Component composition of glass powder By using alkali borosilicate glass as a glass powder material, it is possible to improve the plating property and denseness of the conductor film, but in the glass powder (alkali borosilicate glass) When the content of B ₂ O ₃ is less than 10% by weight and the content of SiO ₂ is more than 86% by weight, the denseness of the conductor film is deteriorated, and between the conductor film and an object to be coated such as a ceramic body. There is a risk that the conductive film will explode when mounted on a circuit board.

On the other hand, when the content of B ₂ O ₃ in the glass powder exceeds 31% by weight and the content of SiO ₂ is less than 65% by weight, the denseness of the conductive film is lowered and the plating property is also reduced. The adhesive strength between the ceramic body and other objects to be coated is lowered, and in this case, the conductor film may explode when mounted on the circuit board.

Further, when the content of M ₂ O in the glass powder is 0.5% by weight or less, the compactness of the conductor film is lowered, and the adhesive strength between the conductor film and the coated object such as the ceramic body is lowered. However, the conductor film may explode when mounted on the circuit board.

On the other hand, when the content of M ₂ O in the glass powder is 5.0% by weight or more, the denseness of the conductor film is deteriorated and the plating property is also reduced, and the gap between the conductor film and the coated object such as the ceramic body is reduced. In this case, the conductor film may explode when mounted on the circuit board.

Therefore, in the present embodiment, the component composition of the glass powder is
10% by weight ≦ B ₂ O ₃ ≦ 31% by weight
65% by weight ≦ SiO ₂ ≦ 86% by weight
0.5 wt% _<M 2 O _<5 wt%
The content is adjusted so that.

  And this electrically conductive paste is manufactured as follows.

That is, B ₂ O ₃ , SiO ₂ so that 10 wt% ≦ B ₂ O ₃ ≦ 31 wt%, 65 wt% ≦ SiO ₂ ≦ 86 wt%, 0.5 wt% <M ₂ O <5 wt%. , And M ₂ O, held at a temperature of 1000 to 1600 ° C. for a predetermined time and melted, and then the melt was poured into pure water, wet pulverized with a ball mill or the like, and then dried. Make it.

  Next, a spherical Ag powder having an average particle diameter of 0.5 to 1.0 μm and a flat Ag powder having an average particle diameter of 1.5 to 5.0 μm and an aspect ratio of 5 to 70 are mixed by weight. Weigh so that the ratio is 1/4 to 4, and prepare conductive powder.

  Next, this conductive powder and glass powder are mixed in an organic vehicle, and are kneaded and dispersed by a three-roll mill, thereby producing a conductive paste. In addition, as an organic vehicle, what disperse | distributed predetermined amount ethylcellulose resin in organic solvents, such as terpineol, can be used, for example.

The conductive paste thus produced has a spherical Ag powder having an average particle diameter of 0.5 to 1.0 μm, an average particle diameter of 1.5 to 5.0 μm, and an aspect ratio of 5 to 70. A conductive powder composed of a mixed powder of a flat Ag powder and a mixing ratio of 1/4 to 4 by weight, B ₂ O ₃ : 10 wt% or more and 31 wt% or less, SiO ₂ : 65 wt% % To 86% by weight or less, M ₂ O: glass powder made of alkali borosilicate glass prepared so as to be more than 5% by weight and less than 5% by weight. It is possible to improve the wettability and heat resistance, and to prevent the plating solution from entering the conductor film, and to form a conductor film with excellent mechanical strength. It becomes possible.

  Next, a multilayer ceramic capacitor as a ceramic electronic component manufactured using the conductive paste will be described in detail.

  FIG. 1 is a cross-sectional view schematically showing an embodiment of a multilayer ceramic capacitor.

  In the multilayer ceramic capacitor, the inner conductor 2 (2a to 2f) is embedded in the ceramic body 1, and outer conductors 3a and 3b are formed at both ends of the ceramic body 1, and the outer conductor 3a, First plating films 4a and 4b and second plating films 5a and 5b are formed on the surface of 3b.

  Specifically, the inner conductors 2a to 2f are arranged in parallel in the stacking direction, the inner conductors 2a, 2c, and 2e are electrically connected to the outer conductor 3a, and the inner conductors 2b, 2d, and 2f are the outer conductor 3b. And are electrically connected. And the electrostatic capacitance is acquired between the opposing surfaces of the internal conductors 2a, 2c, and 2e and the internal conductors 2b, 2d, and 2f.

  The multilayer ceramic capacitor is manufactured as follows.

  First, a ceramic green sheet mainly composed of a dielectric material such as barium titanate is prepared, and then a conductive paste for forming an inner conductor composed mainly of a noble metal material composed of at least one of Ag and Pd. Then, screen printing is performed on the ceramic green sheet to form a conductive pattern having a predetermined shape. As the metal for the inner conductor, a base metal such as Ni or Cu can be used, but a noble metal such as Ag or Pd is preferable because it is less likely to be oxidized.

  After that, a plurality of ceramic green sheets on which conductive patterns are formed are laminated in a predetermined direction, and are sandwiched and pressure-bonded with ceramic green sheets on which conductive patterns are not formed, and cut into predetermined dimensions to produce a ceramic laminate. . Thereafter, a binder removal process is performed at a temperature of about 500 ° C., and then a firing process is performed in an atmosphere at a temperature of 1000 to 1500 ° C. for a predetermined time, thereby producing a ceramic body 1 in which the internal conductor 2 is embedded.

  Next, the conductive paste described above is applied to both end faces of the ceramic body 1 and then dried and fired at a temperature in the atmosphere of 800 to 900 ° C. for a predetermined time to form the external conductors 3a and 3b.

  Next, electrolytic plating is performed to form first plating films 4a and 4b made of Ni, Cu or the like on the surfaces of the outer conductors 3a and 3b, and solder or Sn is further formed on the surfaces of the first plating films 4a and 4b. The second plating films 5a and 5b made of the like are formed, whereby a multilayer ceramic capacitor is manufactured.

  In this way, in the present multilayer ceramic capacitor, the outer conductors 3a and 3b are formed on both end faces of the ceramic body 1 using the conductive paste described above. 3b can be obtained, and a multilayer ceramic capacitor having the outer conductors 3a and 3b excellent in solder wettability and heat resistance can be obtained. Further, since the denseness of the outer conductors 3a and 3b is good, it is possible to prevent the plating solution from entering the inside of the outer conductors 3a and 3b and the inner conductor. A multilayer ceramic capacitor can be obtained in which the electrode does not explode.

  Moreover, since the outer conductor is dense, it is possible to avoid the penetration of the plating solution into the inner conductor, and therefore delamination occurs at the interface between the ceramic layer and the inner conductor, and cracks occur in the ceramic body. In addition, a multilayer ceramic capacitor having excellent reliability can be obtained with high efficiency.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, Ag powder is used as the conductive powder. However, the present invention is also applicable to simple metal powders other than Ag powder, such as Cu powder. Needless to say, the present invention can also be applied to alloy powders such as Ag-Pd powder.

  In the above embodiment, the case where the conductive paste is applied to a multilayer ceramic capacitor has been described. Needless to say, the present invention can also be applied to other ceramic electronic components.

  Next, examples of the present invention will be specifically described.

First, B ₂ O ₃ , SiO ₂ , and M ₂ O (K ₂ O, Li ₂ O, Na ₂ O) are weighed so as to have a composition as shown in Table 1, and placed in a platinum crucible at a temperature. After holding at 1000-1600 ° C. for 60 minutes and confirming that it has been completely melted, it is taken out from the crucible, poured into pure water, wet-ground with a ball mill and dried, whereby an average particle size of 0.5-2 Glass powders of Examples 1 to 8 and Comparative Examples 1 to 4 having a thickness of 0.0 μm were prepared.

  Next, the softening point of these glass powders was measured with a differential thermal analyzer. When the glass powder was analyzed by X-ray diffraction, it was confirmed to be amorphous.

次に、平均粒径が０．７μｍの球形状Ａｇ粉末：３５．５重量％、平均粒径が３．５μｍであってアスペクト比が３０の扁平状Ａｇ粉末：３５．５重量％、上記ガラス粉末：５．０重量％、有機ビヒクル：２４．０重量％となるように配合し、三本ロールミルで混練して外部電極形成用の導電性ペーストを作製した。尚、有機ビヒクルは、エチルセルロース樹脂が２０重量％となるように有機溶剤としてのテルピネオール中にエチルセルロース樹脂を溶解したものを使用した。 Table 1 shows the component composition and softening point of the glass powder in each Example and Comparative Example.

Next, spherical Ag powder having an average particle size of 0.7 μm: 35.5% by weight, flat Ag powder having an average particle size of 3.5 μm and an aspect ratio of 30: 35.5% by weight, the glass The mixture was blended so that the powder was 5.0% by weight and the organic vehicle was 24.0% by weight, and kneaded by a three-roll mill to prepare a conductive paste for forming an external electrode. In addition, the organic vehicle used what melt | dissolved ethyl cellulose resin in the terpineol as an organic solvent so that ethyl cellulose resin might be 20 weight%.

  Next, a ceramic green sheet containing barium titanate as a main component is prepared, and Ag is used as a main component on the surface of the ceramic green sheet so that one end edge is exposed on any end face of the ceramic green sheet. A conductive pattern to be an inner conductor was screen printed using a conductive paste. Next, a predetermined number of ceramic green sheets on which conductive patterns are formed are stacked, and then sandwiched between ceramic green sheets on which conductive patterns are not formed, followed by pressure bonding to produce a ceramic laminate, and then a temperature of about 500 ° C. After the binder removal treatment, firing treatment was performed in the air at a temperature of 1000 to 1500 ° C., thereby producing a ceramic sintered body and obtaining a ceramic body.

  Next, the conductive paste was applied to both ends of this ceramic body by a dipping method, dried, and then fired at a temperature of 850 ° C. for 20 minutes to form an external conductor.

  Next, an electrolytic Ni plating process and an electrolytic Sn plating process are sequentially performed on the ceramic body on which the outer conductor is formed, and a Ni film and an Sn film are formed on the surface of the outer conductor. The laminated ceramic capacitors of Examples 1 to 7 and Comparative Examples 1 to 4 having a thickness of 0.5 mm were obtained.

  Next, for each of the examples and comparative examples, the film thickness of the plating film and the adhesive strength of the external conductor were measured, and further, the presence / absence of explosion of the external conductor was evaluated by observing the presence / absence of solder scattering.

  Here, the film thickness of the plating film was measured with an X-ray film thickness meter for each of the five examples and comparative examples, and the average value was obtained.

  Regarding the adhesive strength, for each of the ten examples and comparative examples, lead wires were soldered to the outer conductor, the tensile strength was measured, and the average value was obtained.

  The presence or absence of solder scattering was applied twice to a reflow oven set at a maximum temperature of 250 ° C. after applying Sn-Pb eutectic cream solder to the surface of the outer conductor for each of 1000 examples and comparative examples. The number of solder splashes was measured.

この表２から明らかなように比較例１は、ガラス粉末中のＢ_２Ｏ_３の含有量が９．０重量％と少なく、ＳｉＯ_２の含有量が８８重量％と多いため、接着強度が２Ｎと低く、緻密性に欠け１０００個中１５０個の試料にはんだ飛散が認められた。 Table 2 shows the plating film, the measurement result of the adhesive strength, and the number of solder splashes in each example and comparative example.

Comparative As is clear from Table 2 Example 1, the content of _B 2 _{O 3} in the glass powder is as small as 9.0 wt%, since the content of SiO ₂ is large and 88% by weight, the adhesive strength is 2N As a result, solder scattering was observed in 150 samples out of 1,000 samples.

In Comparative Example 2, since the content of B ₂ O ₃ in the glass powder is as large as 32.0% by weight and the content of SiO ₂ is as small as 64% by weight, the Ni film thickness is as thin as 0.84 μm, Also, the Sn film thickness was as thin as 1.22 μm, inferior in plating property, and the adhesive strength was as low as 3N, lacking in denseness, and solder scattering was observed in 135 samples out of 1000 samples.

In Comparative Example 3, since the content of K ₂ O in the glass powder is too large at 5.0% by weight, the Ni film has a thin film thickness of 0.95 μm, and the Sn film has a thin film thickness of 1.35 μm. In addition, the adhesion with plating was inferior, and the adhesive strength was as low as 2N.

In Comparative Example 4, since the content of K ₂ O in the glass powder was as low as 0.5% by weight, the adhesive strength was as low as 2N, and it was not dense and solder scattering was observed in 168 samples out of 1000 samples. .

  On the other hand, since Examples 1-8 have formed the external conductor using the electrically conductive paste containing the electrically conductive powder and glass powder in the range of this invention, the film thickness of Ni membrane | film | coat is 2.07- An outer conductor having a thickness of 2.26 [mu] m and a Sn film thickness of 3.77 to 3.97 [mu] m, good plating properties and excellent heat resistance and solder wettability could be obtained. In addition, it has been found that the adhesive strength is as high as 10 to 14 N, the denseness is good, solder scattering does not occur even during mounting, and the external conductor can be prevented from exploding.

  Ag powder as a conductive powder was prepared so as to have an average particle size, an aspect ratio, and a mixing ratio (spherical Ag powder / flat Ag powder) as shown in Table 3.

  Next, Ag powder: 71% by weight, inventive glass powder prepared in Example 2 of Table 1: 5.0% by weight, organic vehicle: 24.0% by weight, and kneaded in a three-roll mill. Thus, a conductive paste for forming external electrodes was produced. In addition, the organic vehicle used what melt | dissolved ethylcellulose resin in the terpineol as an organic solvent so that ethylcellulose resin might be 20 weight% similarly to [Example 1].

  Then, using this conductive paste, multilayer ceramic capacitors of Examples 11 to 19 and Comparative Examples 11 to 18 were produced by the same method and procedure as in [Example 1].

  Next, the film thickness of the plating film, the adhesive strength, and the number of scattered solder were determined in the same manner as in [Example 1].

この表３から明らかなように比較例１１は、球形状Ａｇ粉末の平均粒径が０．４μｍと小さいため、Ｎｉ皮膜の膜厚が０．９７μｍと薄く、またＳｎ皮膜の膜厚も１．２５μｍと薄く、めっき付き性に劣り、さらに接着強度も５Ｎと低く、緻密性に欠け１０００個中３０個の試料にはんだ飛散が認められた。 Table 3 shows the results.

As apparent from Table 3, in Comparative Example 11, since the average particle diameter of the spherical Ag powder is as small as 0.4 μm, the Ni film thickness is as thin as 0.97 μm, and the Sn film thickness is 1. It was as thin as 25 μm, inferior in plating property, and the adhesive strength was as low as 5 N. It was not dense and solder scattering was observed in 30 samples out of 1000 samples.

  In Comparative Example 12, since the average particle diameter of the spherical Ag powder was as large as 1.1 μm, the adhesive strength was as low as 9 N, and the solder was scattered in 41 samples out of 1000 samples lacking denseness.

  In Comparative Example 13, since the average particle diameter of the flat Ag powder is as small as 1.3 μm, the Ni film thickness is as thin as 0.93 μm, and the Sn film thickness is as thin as 1.33 μm. It was inferior and the adhesive strength was as low as 5N, and it was not dense and solder scattering was observed in 35 samples out of 1000 samples.

  In Comparative Example 14, since the average particle diameter of the flat Ag powder was as large as 5.5 μm, the adhesive strength was as low as 8 N, and the solder was scattered in 66 samples out of 1,000 samples lacking denseness.

  In Comparative Example 15, since the aspect ratio of the flat Ag powder is as small as 4, the Ni film thickness is as thin as 0.88 μm, the Sn film thickness is as thin as 1.18 μm, and the inferior plating property is poor. Adhesive strength was as low as 4N, and solder scattering was observed in 28 samples out of 1000 samples.

  In Comparative Example 16, since the aspect ratio of the flat Ag powder was as high as 75, the adhesive strength was as low as 8N, and the solder was scattered in 58 samples out of 1000 samples lacking in denseness.

  In Comparative Example 17, since the mixing ratio of the spherical Ag powder to the flat Ag powder was as small as 1/9 by weight, the adhesive strength was as low as 7N, lacking denseness, and solder scattering occurred in 72 samples out of 1000 samples. Admitted.

  In Comparative Example 18, since the mixing ratio was as large as 9/1, the Ni film thickness was as thin as 0.98 μm, the Sn film thickness was as thin as 1.25 μm, and the plating property was inferior. Also, it was as low as 5N, lacking denseness, and solder scattering was observed in 42 samples out of 1000 samples.

  On the other hand, since Examples 11-19 use the conductive powder in which the average particle diameter, aspect ratio, and mixing ratio of the spherical Ag powder and the flat Ag powder are within the range of the present invention, the film of the Ni film is used. The thickness was 2.06 to 2.20 μm, the thickness of the Sn film was 3.77 to 3.97 μm, and an external conductor with good plating property and excellent heat resistance and solder wettability could be obtained.

  Moreover, it has been found that the adhesive strength is as large as 11 to 14N, the mechanical strength is strong and the denseness is good, and solder scattering does not occur even during mounting, and the external conductor can be prevented from exploding.

1 is a cross-sectional view schematically showing an embodiment of a multilayer ceramic capacitor as a ceramic electronic component according to the present invention.

Explanation of symbols

1 Ceramic body 2 Inner conductor 3a, 3b Outer conductor

Claims (4)

In the conductive paste containing conductive powder, glass powder and organic vehicle,
The conductive powder is a spherical powder having an average particle diameter of 0.5 to 1.0 μm and a flat powder having an average particle diameter of 1.5 to 5.0 μm and a ratio of the maximum diameter to the average thickness of 5 to 70. It is composed of a mixed powder with a powder and is blended so that the ratio of the spherical powder to the flat powder is 1/4 to 4 by weight ratio,
The glass powder comprises 10% by weight to 31% by weight B ₂ O ₃ , 65% by weight to 86% by weight SiO _2, and more than 0.5% by weight and less than 5% by weight M ₂ O (however, , M is an alkali metal borosilicate glass containing an alkali metal element).   The conductive paste according to claim 1, wherein the conductive powder contains Ag as a main component.   A ceramic electronic component, wherein the outer conductor formed on the surface of the ceramic body is made of a sintered body of the conductive paste according to claim 1 or 2.   4. The ceramic electronic component according to claim 3, wherein an inner conductor is embedded in the ceramic body, and the inner conductor is electrically connected to the outer conductor.

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