JPH10188669A - Conductive material and ceramic electronic part with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the occurrence of an oxide film between Ag and Ni when this ceramic electronic part is used for an external electrode, increase its heat shock resistance, and reduce the electrode forming process by mixing NiO powder and Ag powder having specific grain sizes in an organic solvent, and coating the NiO powder with the Ag powder. SOLUTION: Ag powder having the average grain size of 2-3μm and NiO powder having the average grain size of 3μm or below are mixed via an organic solvent in a ball mill at the mixing ratio that the effective surface area of the NiO powder is made larger than that of the Ag powder, and the periphery of the NiO powder is coated with the Ag powder. This conductive material is applied to the chip of a ceramic green sheet layered product, and it is reduction-baked in N2 gas containing H2 gas after it is dried to form a Ni-Ag external electrode. Coating and baking may be applied merely once during this electrode forming process. Since silicide powder is contained in the conductive material, the coefficient of thermal expansion near that obtained when a ceramic is sintered is attained, and the occurrence of cracks is further suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive material for an external electrode used in a multilayer ceramic capacitor, a multilayer ceramic varistor, and the like, and a ceramic electronic component using the same.

[0002]

2. Description of the Related Art In general, a multilayer ceramic capacitor or a multilayer ceramic varistor is formed by laminating a plurality of ceramic green sheets on which NiO internal electrodes are printed, applying a NiO conductive material as an external electrode to an end portion, and firing by reduction. It is manufactured by baking.

[0003]

The heating temperature when the above-mentioned double electrode of Ni and Ag is used can be set to a higher temperature than when only the Ni electrode is used. At the same time, the adhesiveness to the ceramic body is enhanced, and Ag partially dissolves in Ni to reduce its coefficient of thermal expansion, and has the effect of approaching the coefficient of thermal expansion of the ceramic body. Plays an important role in change. Ag also plays a role in reducing the surface resistance of the Ni external electrode.

However, when the Ni external electrode is left in the air, Ni changes to NiO, and N at the boundary between Ni and Ag.
An oxide film of i was formed, and the Ni oxide film was strengthened by heating at a high temperature, and the conductivity and the strength were significantly deteriorated.

The present invention has been made to eliminate the above-mentioned drawbacks of the prior art, and reduces the oxide film between Ni and Ag,
It is an object of the present invention to provide a conductive material capable of reducing the number of steps when forming an external electrode and a ceramic electronic component using the same.

[0006]

Means for Solving the Problems To solve the above problems, the conductive material of the present invention has an average particle diameter of 2 to 3 μm as a main component.
The structure is such that NiO powder having an average particle size of 3 μm or less is mixed with Ag powder of m through an organic solvent to coat the NiO powder with the Ag powder. With this configuration, when used as an external electrode, the oxide film between Ni and Ag is reduced, and the number of steps for forming the external electrode can be reduced.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is to mix NiO powder having an average particle size of 3 μm or less with Ag powder having an average particle size of 2 to 3 μm via an organic solvent. In this configuration, the NiO powder is coated with Ag powder to reduce the oxide film generated between Ni and Ag when used for an external electrode, thereby preventing deterioration in conductivity and strength. Man-hours can be reduced.

According to a second aspect of the present invention, the conductive material according to the first aspect contains a silicide powder, and when used as an external electrode of a ceramic electronic component, a coefficient of thermal expansion in sintering of the ceramic. And the occurrence of cracks can be prevented.

According to a third aspect of the present invention, the conductive material according to the second aspect is applied to an end of an electronic component element in which ceramic green sheets on which NiO internal electrodes are formed are laminated and reduced and fired to form a Ni-Ag exterior. With the configuration in which the electrodes are formed, a ceramic electronic component having excellent reliability can be obtained.

Hereinafter, embodiments of the present invention will be specifically described. That is, the present invention sets the effective surface area of NiO powder to A
When the mixing is performed by a ball mill with the effective surface area larger than the g powder, the periphery of the NiO powder is completely covered with the Ag powder.

When mixing in a ball mill, zirconia balls are used with great care so as not to mix impurities. At this time, in order to obtain a desired effect, it is necessary to appropriately select the powder particle diameters of the Ag powder and the NiO powder, but the particle diameter of the Ni powder is 3 μm, and the particle diameter of the Ag powder is 3 μm. Was used. These mixing ratios are
NiO: Ag = 4: 6.

[0012] Methyl ethyl ketone, ceramic material and silicide powder have an average particle size of 0.5 µm and a purity of 9 µm.
9.9% of those shown in (Table 1) were mixed in a ball mill for 24 hours to prepare a conductive material for an external electrode.

[0013]

[Table 1]

Next, a high dielectric constant ceramic paste containing SrTiO ₃ as a main raw material is prepared, and an organic binder is mixed therein to form a ceramic green sheet having a thickness of 10 μm. An internal electrode containing NiO powder is printed thereon and dried. did.

Next, a similar ceramic green sheet is laminated in a total of 30 layers so that the internal electrodes are alternately shifted with the printed surface of the ceramic green sheet facing upward, and a 10 μm thick layer is formed on both upper and lower surfaces of the laminate. After laminating 20 pieces of ceramic green sheets and pressing them together, they are cut into individual chips, and both ends of the electronic component elements of the laminated ceramic electronic component so that they can be connected alternately to two sets of internal electrodes. The conductive material for an external electrode was uniformly applied to a surface with a thickness of about 50 μm and dried.

Subsequently, the electronic component element was reduced and fired at 1250 ° C. for 4 hours in an N ₂ gas atmosphere containing 2% H gas.

The behavior of Ni and Ag in the external electrode at this time is as follows. Ni pushes Ag out and Ni
Is well bonded to Ni as an internal electrode, and Ni is bonded to the ceramic end portion around the Ni internal electrode portion and Ag is present on the ceramic side surface so as to cover the Ni internal electrode portion. Further, the silicide contributes to good bonding between the external electrode and the ceramic.

Thereafter, the electronic component element in the reduced state is fired at 900 ° C. in air. At this time, N in the external electrode
A large amount of NiO does not exist between i and Ag.

FIG. 1 shows the structure of the multilayer ceramic electronic component manufactured as described above. In FIG. 1, 1 is a ceramic body, 2 is an internal electrode made of Ni, 3 is an external electrode made of Ag, and 4 is an external electrode made of Ni.

The tan δ,
Table 2 shows a comparison between the conventional value in which the ESR was reduced and the value of the present invention.

[0021]

[Table 2]

Next, the strength of the external electrodes 3 and 4 and the ceramic body 1 in the multilayer ceramic electronic component will be described. As shown in FIG. 2, the measurement of the strength is performed by connecting Ni and solder (Sn: P) to the external electrodes 3 and 4 at both ends of the ceramic body 1.
b = 9: 1) Plating is performed by barrel plating so as to have a thickness of 3 μm each, metal wires 5 made of steel are connected to both end surfaces by soldering, and a load is applied to the metal wires 5 to form electrodes. The tensile strength (kg / cm ² ) was determined by actually measuring the force at that time and the electrode defect area. The results are shown in (Table 3).

[0023]

[Table 3]

[0024]

As described above, when the conductive material of the present invention is used for an external electrode of a ceramic electronic component, it does not cause cracks in the ceramic body and sufficiently withstands heat shock. This is Ni and Ag
This is because a large amount of an oxide film is not formed even when reduction baking is performed between the first and second steps, which is considered to be caused by coating the NiO powder with the Ag powder. In addition, by using such a conductive material, the step of forming the external electrodes of the ceramic electronic component is completed by one coating and firing, which contributes to a reduction in the number of steps. Further, when it is made into a ceramic electronic component, it can be made to be extremely excellent in characteristics.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a ceramic electronic component when a conductive material according to an embodiment of the present invention is used for an external electrode.

FIG. 2 is an explanatory view for measuring a tensile strength of the ceramic electronic component.

[Explanation of symbols]

 Reference Signs List 1 ceramic body 2 internal electrode 3, 4 external electrode

──────────────────────────────────────────────────の Continuing on the front page (51) Int.Cl. ⁶ Identification code FI H01G 4/30 301 H01G 1/14 F (72) Inventor Yasuo Wakahata 1006 Ojidoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. ( 72) Inventor Iwao Ueno 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Kimio Kobayashi 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] An Ag having an average particle diameter of 2 to 3 μm as a main component.
A conductive material in which NiO powder is coated with Ag powder by mixing the powder with NiO powder having an average particle size of 3 μm or less via an organic solvent. 2. The conductive material according to claim 1, further comprising a silicide powder. 3. An electronic component element having ceramic green sheets on which NiO internal electrodes are formed is laminated on an end portion of the electronic component element.
A ceramic electronic component having a Ni-Ag external electrode formed by applying the conductive material described in 1 above and reducing and firing it.