JP2015060940A - Ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic electronic component having excellent deformation resistance and low ESR.SOLUTION: External electrodes 20, 22 are configured of: resin electrode layers 20a, 22a including thermosetting resin and conductive filler; Cu plating layers 20b, 22b formed on the resin electrode layers 20a, 22a; Ni plating layers 20c, 22c formed on the Cu plating layers 20b, 22b; and Sn plating layers 20d, 22d formed on the Ni plating layers 20c, 22c. The conductive filler is made of Ag powder or metal powder whose surface is coated with Ag powder. The external electrodes 20, 22 are formed on both sides of a ceramic element body 10 via foundation electrode layers 30, 32 containing conductive metal and glass component.

Description

  The present invention relates to a ceramic electronic component such as a multilayer ceramic capacitor, a multilayer ceramic inductor, a ceramic IC, or a ceramic piezoelectric component.

  In recent years, a ceramic electronic component represented by a multilayer ceramic capacitor has been used in a harsher environment as compared with the related art.

  For example, ceramic electronic components used in mobile devices such as mobile phones and portable music players are required to withstand impacts when dropped. Specifically, there is a demand for a ceramic electronic component that does not fall off the mounting substrate even when subjected to a drop impact, or a ceramic electronic component that does not crack.

  In addition, ceramic electronic components used in in-vehicle devices such as ECUs (engine control units) are required to withstand thermal cycle impacts. Specifically, there is a demand for a ceramic electronic component that does not crack even when subjected to a bending stress generated by thermal expansion and thermal contraction of the mounting substrate due to a thermal cycle.

  Thus, in order to satisfy these requirements, a multilayer ceramic capacitor described in Patent Document 1 has been proposed. This multilayer ceramic capacitor includes an external electrode in which a conductive thermosetting resin layer is formed between an Ag-containing electrode layer and a Ni plating layer. The thermosetting resin layer functions as a buffer material so that cracks do not occur in the multilayer ceramic capacitor body even under harsh environments, and improves the bending resistance of the multilayer ceramic capacitor.

Japanese Patent Application Laid-Open No. 11-162771

  However, since the multilayer ceramic capacitor of Patent Document 1 forms a thermosetting resin layer between the Ag-containing electrode layer and the Ni plating layer, even if the thermosetting resin layer is a conductive layer. There is a problem that the contact resistance between the thermosetting resin layer and the Ni plating layer increases, and the ESR (equivalent series resistance) increases.

  Therefore, an object of the present invention is to provide a ceramic electronic component having excellent deflection resistance and low ESR.

  The present invention includes a ceramic body in which a plurality of ceramic layers and a plurality of internal electrodes are alternately stacked, an external electrode formed on the outer surface of the ceramic body and electrically connected to the internal electrodes, The external electrode was formed on the Cu plating layer formed on the resin electrode layer including the thermosetting resin and the conductive filler, the Cu plating layer formed on the resin electrode layer, and the Cu plating layer. A ceramic characterized in that it is composed of a Ni plating layer and a Sn plating layer formed on the Ni plating layer, and the conductive filler is made of Ag powder or metal powder surface-coated with Ag. It is an electronic component. Here, the metal powder is preferably Cu powder.

  In the present invention, a Cu plating layer is formed between the resin electrode layer and the Ni plating layer. The Cu plating layer has good compatibility with Ag powder in the resin electrode layer and metal powder surface-coated with Ag, and the contact resistance between the Cu plating layer and the resin electrode layer is low. Furthermore, the Cu plating layer has good compatibility with Ni constituting the Ni plating layer, and the contact resistance between the Cu plating layer and the Ni plating layer is also low. Therefore, ESR reduction is achieved.

  Furthermore, since the thermosetting resin in the resin electrode layer functions as a buffering material so that cracks do not occur in the ceramic electronic component even under harsh environments, the bending resistance of the ceramic electronic component is improved.

  In the ceramic electronic component according to the present invention, it is preferable that the external electrode is formed on the outer surface of the ceramic body with a base electrode layer containing a conductive metal and a glass component interposed.

  The base electrode layer further strengthens the bonding strength between the internal electrode and the external electrode. Furthermore, the base electrode layer prevents moisture from entering the interface between the internal electrode and the ceramic layer.

  According to the present invention, a ceramic electronic component having excellent deflection resistance and low ESR can be obtained.

  The above-described object, other objects, features, and advantages of the present invention will become more apparent from the following description of embodiments for carrying out the invention with reference to the drawings.

1 is an external perspective view showing a first embodiment of a ceramic electronic component according to the present invention. It is AA vertical sectional drawing of FIG. It is a vertical sectional view showing a second embodiment of a ceramic electronic component according to the present invention.

  An embodiment of a ceramic electronic component according to the present invention will be described by taking a multilayer ceramic capacitor as an example.

1. First Embodiment FIG. 1 is an external perspective view showing a multilayer ceramic capacitor 1 according to a first embodiment, and FIG. 2 is a vertical sectional view thereof. The multilayer ceramic capacitor 1 includes a ceramic body 10, external electrodes 20 and 22 formed on the left and right ends of the ceramic body 10, and between the left and right ends of the ceramic body 10 and the external electrodes 20 and 22. The base electrode layers 30 and 32 are formed.

(1) Ceramic Element Body The ceramic element body 10 includes a plurality of inner layer ceramic layers 11, a plurality of inner electrodes 12, 13 disposed at the interfaces between the plurality of inner layer ceramic layers 11, and a plurality of inner layer ceramics. The outer ceramic layers 15 a and 15 b are arranged vertically so as to sandwich the layer 11. That is, the ceramic body 10 has a rectangular parallelepiped structure in which the ceramic layers 11, 15 a, 15 b and the internal electrodes 12, 13 are alternately stacked. The corners and ridges of the ceramic body 10 are preferably rounded.

The inner ceramic layer 11 is made of, for example, a dielectric ceramic material composed of main components such as BaTiO ₃ , CaTiO ₃ , SrTiO ₃ , and CaZrO ₃ . Moreover, you may use the dielectric ceramic material which added subcomponents, such as a Mn compound, Fe compound, Cr compound, Co compound, Ni compound, to these main components. The thickness of the inner layer ceramic layer 11 is preferably 0.5 to 10 μm.

  The same ceramic ceramic material as that for the inner ceramic layer 11 is used for the outer ceramic layers 15a and 15b disposed above and below. The outer ceramic layers 15 a and 15 b may be made of a dielectric ceramic material different from the inner ceramic layer 11.

  The internal electrode 12 and the internal electrode 13 are opposed to each other via the inner ceramic layer 11 in the thickness direction. Capacitance is formed in a portion where the internal electrode 12 and the internal electrode 13 are opposed to each other with the inner ceramic layer 11 interposed therebetween.

  The left end portion of the internal electrode 12 is drawn out to the left end surface of the ceramic body 10 and is electrically connected to the external electrode 20. The right end of the internal electrode 13 is drawn out to the right end face of the ceramic body 10 and is electrically connected to the external electrode 22.

  The internal electrodes 12 and 13 are made of, for example, Ni, Cu, Ag, Pd, an Ag—Pd alloy, Au, or the like. The thickness of the internal electrodes 12 and 13 is preferably 0.3 to 2.0 μm.

(2) External electrode The external electrodes 20 and 22 are formed on the resin electrode layers 20a and 22a, the Cu plating layers 20b and 22b formed on the resin electrode layers 20a and 22a, and the Cu plating layers 20b and 22b, respectively. The Ni plating layers 20c and 22c thus formed, and the Sn plating layers 20d and 22d formed on the Ni plating layers 20c and 22c.

(A) Resin Electrode Layer The resin electrode layers 20a and 22a are respectively formed on the left and right end surfaces of the ceramic body 10 and wrap around the front and back surfaces. The resin electrode layers 20 a and 22 a may be formed only on the left and right end faces of the ceramic body 10. The thickness of the resin electrode layers 20a and 22a is preferably 20 to 150 μm. The resin electrode layers 20a and 22a are made of a material containing a thermosetting resin and a conductive filler.

  The thermosetting resin mainly increases the elasticity of the resin electrode layers 20a and 22a. As the thermosetting resin, for example, an epoxy resin, a phenol resin, or the like is used.

  The conductive filler mainly bears the conductivity of the resin electrode layers 20a and 22a. Specifically, an energization path is formed inside the resin electrode layers 20a and 22a when adjacent conductive fillers come into contact with each other. The conductive filler is made of Ag powder or metal powder whose surface is coated with Ag. When the conductive filler is Ag powder, the resin electrode layers 20a and 22a have low specific resistance and are not oxidized. In the case where the conductive filler is a metal powder whose surface is coated with Ag, the resin powder layers 20a and 22a are inexpensive by making the metal powder of the base material inexpensive while maintaining the same characteristics as the above Ag powder. It becomes. The metal powder is preferably Cu powder.

  The content of the conductive filler in the cured resin electrode layers 20a and 22a is preferably 35% by volume to 55% by volume. The shape of the conductive filler is not particularly limited, and may be spherical or ellipsoidal. The average particle diameter of the conductive filler is, for example, about 1.0 μm to 10 μm and is not particularly limited.

(B) Cu plating layer / Ni plating layer / Sn plating layer The Cu plating layers 20b and 22b are formed to cover the resin electrode layers 20a and 22a, respectively. Ni plating layers 20c and 22c are formed on the Cu plating layers 20b and 22b, respectively. Sn plating layers 20d and 22d are formed on the Ni plating layers 20c and 22c, respectively. It is preferable that the thickness per one layer of each plating layer is 1-10 micrometers.

  The Ni plating layers 20c and 22c function as solder barrier layers. The Sn plating layers 20d and 22d improve solder wettability when the multilayer ceramic capacitor 1 is soldered and mounted on a mounting board.

  The external electrodes 20 and 22 are formed at both ends of the ceramic body 10 with the base electrode layers 30 and 32 interposed, respectively.

(3) Base Electrode Layer The base electrode layers 30 and 32 are formed so as to cover the end surfaces of the ceramic body 10 where the internal electrodes 12 and 13 are exposed. The resin electrode layers 20a and 22a are formed so as to cover the base electrode layers 30 and 32, respectively.

  The base electrode layers 30 and 32 contain a conductive metal and a glass component. As the conductive metal, for example, Cu, Ni, Ag, Pd, Ag—Pd alloy, Au, or the like is used. As the glass component, glass containing B, Si, Ba, Mg, Al, Li or the like is used. The base electrode layers 30 and 32 are alloyed with the internal electrodes 12 and 13 to ensure electrical connectivity with the internal electrodes 12 and 13. Accordingly, the base electrode layers 30 and 32 can ensure the bonding between the internal electrodes 12 and 13 and the external electrodes 20 and 22. The thickness of the base electrode layers 30 and 32 (thickness of the thickest part) is preferably relatively thick at 10 to 50 μm.

  In the multilayer ceramic capacitor 1 having the above configuration, Cu plating layers 20b and 22b are formed between the resin electrode layers 20a and 22a and the Ni plating layers 20c and 22c. The Cu plating layers 20b and 22b have good compatibility with Ag powder in the resin electrode layers 20a and 22a and metal powder surface-coated with Ag, and between the Cu plating layers 20b and 22b and the resin electrode layers 20a and 22a. Contact resistance can be lowered. Furthermore, the Cu plating layers 20b and 22b are compatible with Ni constituting the Ni plating layers 20c and 22c, and the contact resistance between the Cu plating layers 20b and 22b and the Ni plating layers 20c and 22c can be reduced. As a result, the total conductivity of the external electrodes 20 and 22 can be improved, and the ESR can be lowered.

  Furthermore, since the thermosetting resin in the resin electrode layers 20a and 22a functions as a buffer material so that cracks do not occur in the multilayer ceramic capacitor 1 body even under harsh environments, the bending resistance of the multilayer ceramic capacitor 1 is improved. Can be made. The resin electrode layers 20a and 22a are flexible because they contain a resin, can easily absorb the impact when stress is applied from the outside, and can prevent cracks occurring in the ceramic body 10 and the mounting solder.

  Further, the base electrode layers 30 and 32 make the bonding strength between the internal electrodes 12 and 13 and the external electrodes 20 and 22 even more firm. Furthermore, since the base electrode layers 30 and 32 cover the internal electrodes 12 and 13, moisture can be prevented from entering the interface between the internal electrodes 12 and 13 and the ceramic layer 11, and moisture resistance reliability can be ensured. . This is because the glass components contained in the base electrode layers 30 and 32 are melted and the exposed portions of the internal electrodes 12 and 13 can be sealed.

(4) Manufacturing method of multilayer ceramic capacitor Next, the manufacturing method of the multilayer ceramic capacitor 1 is demonstrated.

  First, the inner layer and outer layer ceramic green sheets and the inner electrode conductive paste are prepared. A known organic binder or organic solvent is used for the ceramic green sheet or the internal electrode conductive paste.

  Next, the internal electrode conductive paste is applied on the ceramic green sheet for the inner layer by, for example, screen printing or the like to form the internal electrodes 12 and 13 having a predetermined pattern. Thereafter, a predetermined number of outer layer ceramic green sheets are laminated. On top of that, the ceramic green sheets for the inner layer on which the internal electrodes 12 and 13 are formed are sequentially laminated. A predetermined number of ceramic green sheets for outer layers are laminated thereon. In this way, a mother ceramic body is produced.

  Next, the mother ceramic body is pressed in the stacking direction by means such as isostatic pressing. Thereafter, the mother ceramic body is cut into a predetermined product size, and the unfired ceramic body 10 is cut out. The ceramic body 10 is rounded at corners and ridges by barrel polishing or the like.

  Next, the unfired ceramic body 10 is fired. The firing temperature is preferably 900 to 1300 ° C. Thus, the inner layer ceramic green sheet is the inner layer ceramic layer 11 and the outer layer ceramic green sheet is the outer layer ceramic layers 15a and 15b.

  Next, a conductive paste containing a conductive metal and a glass component is applied and baked on both end faces of the fired ceramic body 10 to form the base electrode layers 30 and 32. The baking temperature is preferably 700 to 900 ° C. The base electrode layers 30 and 32 may be cofires that are fired simultaneously with the internal electrodes 12 and 13, or may be postfires that are fired simultaneously with the conductive paste for external electrodes. The base electrode layers 30 and 32 may be formed by plating, or may be formed by curing a conductive resin including a thermosetting resin.

Next, after the resin electrode layer paste is applied so as to cover the base electrode layers 30 and 32, heat treatment is performed at a temperature of 150 to 300 ° C. or higher in an N ₂ atmosphere. Heat cured. In order to prevent scattering of the resin and oxidation of various metal components, it is preferable to suppress the oxygen concentration in the heat treatment atmosphere to 100 ppm or less. Thus, the resin electrode layer paste is used as the resin electrode layers 20a and 22a.

  Next, Cu plating layers 20b and 22b, Ni plating layers 20c and 22c, and Sn plating layers 20d and 22d are formed on the resin electrode layers 20a and 22a in this order. In this way, the multilayer ceramic capacitor 1 is produced.

2. Second Embodiment FIG. 3 is a vertical cross-sectional view showing a monolithic ceramic capacitor 1A according to a second embodiment. The multilayer ceramic capacitor 1 </ b> A includes a ceramic body 10 and external electrodes 20 and 22 formed on left and right ends of the ceramic body 10. That is, in the monolithic ceramic capacitor 1 </ b> A, the base electrode layers 30 and 32 are not formed between the left and right ends of the ceramic body 10 and the external electrodes 20 and 22.

  When the base electrode layers 30 and 32 are not formed, the resin electrode layers 20a and 22a are made of a thermosetting resin, a first conductive filler made of Ag powder or metal powder surface-coated with Ag, Sn, In, and Bi. It is preferable to consist of the material containing the 2nd electroconductive filler of metal powder with comparatively low melting | fusing point. In particular, the second conductive filler is preferably Sn. The second conductive filler can improve the bonding strength between the resin electrode layers 20a and 22a and the internal electrodes 12 and 13.

1. Example and Comparative Example A sample of the example (multilayer ceramic capacitor 1) and a sample of the comparative example (capacitor without the Cu plating layers 20b and 22b in the multilayer ceramic capacitor 1) were produced with the following specifications, and ESR (equivalent series) Resistance) was measured. The sample of the comparative example was the same as the sample of the example except that the Cu plating layers 20b and 22b were not formed. The number of samples was 20 each.

(specification)
(1) Design value size (L × W × T): 3.3 mm × 2.6 mm × 2.6 mm
(2) Capacitance: 4.7 μF
(3) Rated voltage: 50V
(4) Material of ceramic layers 11, 15a, 15b: BaTi ₂ O ₃
(5) Material of the base electrode layers 30 and 32: Cu
Thickness of base electrode layers 30 and 32: 125 μm (design value at the center of the end face)
(6) Structure of external electrodes 20 and 22 (a) Conductive filler of resin electrode layers 20a and 22a: Ag
Thermosetting resin of resin electrode layers 20a and 22a: epoxy thermosetting resin
Thermosetting temperature of resin electrode layers 20a and 22a: 200 to 250 ° C
Resin electrode layers 20a, 22a thickness: 110 μm (design value at the center of the end face)
(B) Thickness of Cu plating layers 20b and 22b: 2 μm (design value at the center of the end face)
(C) Ni plating layers 20c, 22c thickness: 2.5 μm (design value at the center of the end face)
(D) Thickness of Sn plating layers 20d and 22d: 3.5 μm (design value at the center of the end face)
(7) Firing temperature of the unfired ceramic body 10: 1200 ° C. (2 hours)

2. Evaluation Methods and Evaluation Results of Examples and Comparative Examples ESR (equivalent series resistance) was measured under the conditions of a measurement frequency of 1 MHz and a measurement voltage of 500 mV using a precision LCR meter (manufactured by Agilent: E4980A).

  Table 1 shows the measurement results of ESR of the multilayer ceramic capacitor.

  From Table 1, the multilayer ceramic capacitor 1 of the example (the multilayer ceramic capacitor 1 in which the Cu plating layers 20b and 22b are formed between the resin electrode layers 20a and 22a and the Ni plating layers 20c and 22c) is the comparative example. It was recognized that the ESR value was smaller than that of a multilayer ceramic capacitor (a multilayer ceramic capacitor having no Cu plating layers 20b and 22b and Ni plating layers 20c and 22c formed directly on the resin electrode layers 20a and 22a). .

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is carried out within the range of the summary.

  In addition to the ceramic capacitor, the ceramic electronic component may be a ceramic inductor, a ceramic IC, a ceramic piezoelectric component, or the like. In the case of a multilayer ceramic capacitor, a magnetic ceramic material such as ferrite is used as the material of the ceramic layer. In the case of a ceramic IC, a semiconductor ceramic material such as a spinel ceramic is used as a material for the ceramic layer. In the case of a ceramic piezoelectric component, a piezoelectric ceramic material such as PZT ceramic is used as the material of the ceramic layer.

DESCRIPTION OF SYMBOLS 1,1A Multilayer ceramic capacitor 10 Ceramic body 11 Ceramic layer for inner layer 12, 13 Internal electrode 15a, 15b Ceramic layer for outer layer 20, 22 External electrode 20a, 22a Resin electrode layer 20b, 22b Cu plating layer 20c, 22c Ni plating layer 20d, 20d Sn plating layer 30, 32 Base electrode layer

Claims (3)

A ceramic body in which a plurality of ceramic layers and a plurality of internal electrodes are alternately laminated;
An external electrode formed on an outer surface of the ceramic body and electrically connected to the internal electrode, and a ceramic electronic component comprising:
The external electrode includes a resin electrode layer containing a thermosetting resin and a conductive filler, a Cu plating layer formed on the resin electrode layer, a Ni plating layer formed on the Cu plating layer, and the Ni An Sn plating layer formed on the plating layer, and
The conductive filler is made of Ag powder or metal powder surface-coated with Ag,
Features ceramic electronic parts.   The ceramic electronic component according to claim 1, wherein the metal powder is Cu powder.   3. The external electrode according to claim 1, wherein the external electrode is formed on an outer surface of the ceramic body with a base electrode layer containing a conductive metal and a glass component interposed therebetween. Ceramic electronic components.

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