JP5899609B2 - Multilayer ceramic capacitor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a ceramic electronic component such as a multilayer ceramic capacitor and a manufacturing method thereof.

The external electrode of the ceramic electronic component is usually formed by dipping the end face of the ceramic body into the external electrode conductive paste. In this case, due to the influence of the rheology and the like of the conductive paste for external electrodes, the central portion of the e dimension portion of the external electrode (the portion that wraps around the main surface and the side surface of the ceramic body) is thickly raised.
When a thermal shock is applied to a ceramic electronic component having such an external electrode, the thermal contraction stress of the external electrode acts to peel the external electrode from the ceramic body, There is a risk that cracks will occur.

In order to solve the above problem, for example, in Patent Document 1, it is proposed to prevent the occurrence of cracks due to the stress by forming an external electrode only on the end face.
However, the structure of the ceramic electronic component disclosed in Patent Document 1 has a problem that solderability is deteriorated because the external electrode does not go around the mounting surface.
In order to solve this problem, as disclosed in Patent Document 2, a ceramic electronic component in which a plating film is formed so as to cover the thick film electrode on the end face has been proposed.

Japanese Patent Laid-Open No. 10-199752 JP-A-11-026284

  However, in the structure of the ceramic electronic component proposed in Patent Document 2, since the plating film that wraps around the e-dimension portion is formed with a certain thickness, when the thermal shock is applied to the ceramic electronic component, the e-dimension end The heat shrinkage stress was not reduced in the part, and there was a problem that cracks occurred again in the ceramic electronic component.

  SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a ceramic electronic component that prevents the occurrence of cracks during the manufacture of the ceramic electronic component and a method for manufacturing the same.

The multilayer ceramic capacitor according to the present invention is formed at least alternately so as to be sandwiched between a pair of main surfaces facing each other, a pair of side surfaces facing each other, a plurality of ceramic layers made of a dielectric, and a plurality of ceramic layers. A ceramic electronic component comprising: a ceramic body comprising a pair of internal electrodes; and a pair of external electrodes formed on the end face of the ceramic body so as to be connected to the internal electrodes, wherein at least a pair of internal electrodes Each pair is formed by extending one end of one internal electrode to one end surface of the ceramic body and extending one end of the other internal electrode to the other end surface of the ceramic body. The electrode is formed on the end surface and does not wrap around the main surface or the side surface, and the electrode covers the first conductive layer. And a second conductive layer formed on the main surface and on the side surface. The first conductive layer includes Ni sintered metal, and the second conductive layer includes Cu plated metal. The second conductive layer is formed on the main surface and the side surface so as to become thinner as the distance from the end surface increases, and is formed so as to be in contact with the main surface and the side surface. The length in the direction connecting the pair of end faces is longer than the thickness in the direction connecting the pair of end faces of the second conductive layer formed on the first conductive layer, and the ceramic body is viewed from the stacking direction. Sometimes, in the region where the second conductive layer and the internal electrode overlap, the second conductive layer and the ceramic body are in direct contact, and when the ceramic body is viewed from the stacking direction , end portions of the conductive layer is either rack to the internal electrode on the side not drawn to the end face Characterized in that it is formed as a ceramic electronic component.
In the multilayer ceramic capacitor according to the present invention, the sintered metal contained in the first conductive layer and the plating metal contained in the second conductive layer are preferably the same metal.
A method of manufacturing a multilayer ceramic capacitor according to the present invention includes a pair of main surfaces facing each other, a pair of side surfaces facing each other, a pair of end surfaces facing each other, a plurality of ceramic layers and a plurality of ceramic layers made of a dielectric. A step of preparing a ceramic body comprising at least a pair of internal electrodes alternately formed so as to be sandwiched between the inner surface and the internal electrode on the end surface so as not to wrap around the main surface and the side surface By applying and baking a conductive paste containing Ni so as to be connected, a process of forming the first conductive layer, and a plating process is performed on the ceramic body so as to cover the first conductive layer In addition, the second plating is performed by strike plating containing Cu so as to wrap around the main surface and the side surface and to become thinner as the distance from the end surface increases. Forming a conductive layer, and the step of forming the second conductive layer includes a length in a direction connecting a pair of end surfaces of the second conductive layer formed in contact with the main surface and the side surface. Is longer than the length in the direction connecting the pair of end faces from one end face of the ceramic element body to one end face of the internal electrode that is not drawn to the one end face of the ceramic element body , and the ceramic element body is viewed from the stacking direction. Sometimes, in the region where the second conductive layer and the internal electrode overlap, the second conductive layer and the ceramic body are in direct contact, and when the ceramic body is viewed from the stacking direction , An end portion of a conductive layer is formed so as to span an internal electrode on a side not drawn out on an end face.
In the method for manufacturing a multilayer ceramic capacitor according to the present invention, the first conductive layer includes a sintered metal, the second conductive layer includes a plated metal, and the sintered metal included in the first conductive layer; It is preferable that the plating metal contained in the second conductive layer is formed of the same metal and includes a step of heat-treating the second conductive layer.

According to the multilayer ceramic capacitor according to the present invention, the thickness of the second conductive layer formed on the main surface and the side surface decreases as the distance from the pair of end surfaces increases, so the tip of the second conductive layer is the thinnest. Therefore, even when a thermal shock is applied to the ceramic electronic component during the manufacture of the ceramic electronic component, the thermal contraction stress applied to the tip of the second conductive layer is reduced, and cracks are generated in the ceramic electronic component. Thus, a ceramic electronic component capable of preventing the above can be obtained.
In the multilayer ceramic capacitor according to the present invention, the sintered metal contained in the first conductive layer and the plated metal contained in the second conductive layer are made the same metal, and then the second conductive layer is formed. By applying the heat treatment, the metals diffuse between the layers, so that the adhesion between the first conductive layer and the second conductive layer can be increased.
Furthermore, according to the method for manufacturing a multilayer ceramic capacitor according to the present invention, the thickness of the second conductive layer formed on the main surface and the side surface is formed by strike plating so that the thickness decreases as the distance from the pair of end surfaces increases. Since the tip of the second conductive layer is formed to be the thinnest, even when a thermal shock is applied to the ceramic electronic component during the manufacture of the ceramic electronic component, the thermal contraction stress applied to the tip of the second conductive layer is Therefore, it is possible to manufacture a ceramic electronic component that can prevent generation of cracks in the ceramic electronic component.
According to the method for manufacturing a multilayer ceramic capacitor according to the present invention, the sintered metal contained in the first conductive layer and the plating metal contained in the second conductive layer are formed of the same metal, By including a heat treatment step after the formation of the conductive layer, the metals diffuse between the first conductive layer and the second conductive layer, so that the first conductive layer and the second conductive layer It is possible to manufacture a ceramic electronic component with increased adhesion.

  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.

It is the schematic perspective view which notched a part which shows an example of the external appearance of the ceramic electronic component concerning this invention. FIG. 2 is an illustrative sectional view showing a section taken along line AA of the ceramic electronic component shown in FIG. 1 according to the present invention. It is the elements on larger scale of the cross-section figure of FIG. 2 which shows an example of the ceramic electronic component concerning this invention.

  An embodiment of a ceramic electronic component according to the present invention will be described. FIG. 1 is a schematic perspective view showing an example of the appearance of a ceramic electronic component constituted by a ceramic element body that is an electronic component element body and external electrodes, and FIG. 2 is an A of the ceramic electronic component shown in FIG. The cross-section solution figure which shows the cross section in the -A line | wire is shown. Moreover, FIG. 3 shows the elements on larger scale of the cross-section figure of FIG. 2 of an example of the ceramic electronic component concerning this embodiment. In the schematic perspective view of the ceramic electronic component shown in FIG. 1, a part of the ceramic electronic component is notched, but the ceramic electronic component in the present embodiment is not actually cut away.

  A ceramic electronic component 10 according to this embodiment includes a ceramic body 12 (laminated body) of a multilayer ceramic capacitor, which is an electronic component body, and external electrodes 14 a and 14 b formed on the surface of the ceramic body 12.

  The ceramic body 12 used in the ceramic electronic component 10 according to this embodiment is formed in, for example, a substantially rectangular parallelepiped shape, and has one main surface 26a and the other main surface 26b facing each other, and one side surface 28a and the other side surface 28b facing each other. And one end face 30a and the other end face 30b facing each other. The ceramic body 12 preferably has rounded corners 32 and ridges 34.

The ceramic body 12 includes a number of ceramic layers 22 made of a dielectric.
For the ceramic layer 22, for example, a dielectric ceramic composed of main components such as BaTiO ₃ , CaTiO ₃ , SrTiO ₃ , and CaZrO ₃ can be used. Moreover, you may use what added subcomponents, such as a Mn compound, Fe compound, Cr compound, Co compound, Ni compound, to these main components. In addition, piezoelectric ceramics such as PZT ceramics, semiconductor ceramics such as spinel ceramics, and magnetic ceramics such as ferrite can also be used.

  Moreover, it is preferable that the thickness of the ceramic layer 22 after baking is 0.5-10 micrometers.

The ceramic body 12 has internal electrodes 24 a and 24 b so as to be sandwiched between a plurality of ceramic layers 22. The internal electrodes 24 a and 24 b are alternately formed so as to be sandwiched between the ceramic layers 22 constituting the ceramic body 12. In this case, the internal electrode 24 a is formed with one end extending to one end face 30 a of the ceramic body 12, and the internal electrode 24 b is formed with one end extending to the other end face 30 b of the ceramic body 12. The internal electrodes 24 a and 24 b are formed so that the intermediate portion and the other end portion overlap with each other with the ceramic layer 22 interposed therebetween. Therefore, the ceramic body 12 has a laminated structure in which a plurality of internal electrodes 24 a and 24 b are provided via the ceramic layer 22.
For the internal electrodes 24a and 24b, for example, Ni, Cu, Ag, Pd, an Ag—Pd alloy, Au, or the like can be used. The thickness of the internal electrodes 24a and 24b after firing is preferably 0.3 to 2.0 μm.

The external electrode 14a is formed on one end face 30a of the ceramic body 12 so as to be connected to the internal electrode 24a. Similarly, the external electrode 14b is formed on the other end surface 30b of the ceramic body 12 so as to be connected to the internal electrode 24b.
The external electrode 14a includes a first conductive layer 16a, a second conductive layer 18a, and a third conductive layer 20a, and the external electrode 14b includes a first conductive layer 16b, a second conductive layer 18b, and a third conductive layer. The conductive layer 20b is provided.

  The first conductive layer 16 a is formed on one end face 30 a of the ceramic body 12, and the first conductive layer 16 b is formed on the other end face 30 b of the ceramic body 12. As a result, the internal electrode 24a drawn to the one end face 30a and the first conductive layer 16a are electrically connected, and the internal electrode 24b drawn to the other end face 30b and the first conductive layer 16b are electrically connected. The first conductive layer 16a is formed so as not to wrap around the one main surface 26a and the one side surface 28a, and the first conductive layer 16b does not wrap around the other main surface 26b and the other side surface 28b. It is formed. The first conductive layer 16a may be formed only on the one end surface 30a, or may be formed so as to cover the corner portion 26 or the ridge portion 28 adjacent to the one end surface 30a. Similarly, the first conductive layer 16b may be formed only on the other end surface 30b, or may be formed so as to cover the corner portion 26 or the ridge portion 28 adjacent to the other end surface 30b.

The first conductive layers 16a and 16b include a sintered metal. As this sintered metal, Cu, Ni, Ag, Pd, Ag—Pd alloy, Au, or the like is used. The first conductive layers 16a and 16b preferably include glass.
The first conductive layers 16a and 16b may be formed by a cofire method in which the ceramic body 12 and the internal electrodes 24a and 24b are simultaneously fired, and a conductive paste is applied on the already fired ceramic body. It may be formed by a baked postfire method.
The thickness of the first conductive layers 16a and 16b is preferably 3 to 20 μm.

The second conductive layer 18a is formed on one end face 30a so as to cover the first conductive layer 16a, and the second conductive layer 18b is formed so as to cover the first conductive layer 16b. It is formed on the other end face 30b. The second conductive layer 18a is formed so as to wrap around the one main surface 26a and the one side surface 28a, and the second conductive layer 18b is formed so as to wrap around the other main surface 26b and the other side surface 28b. Is done.
Second conductive layer 18a is formed on one main surface 26a and one side surface 28a so as to become thinner as it goes away from one end surface 30a. Second conductive layer 18b is formed on the other main surface 26b and the other side surface 28b. On the upper side, it is formed so as to become thinner as it goes away from the other end face 30b.
As described above, the thickness of the second conductive layer 18a decreases as it moves away from the one end face 30a, and the thickness of the second conductive layer 18b decreases as it moves away from the other end face 30b. As shown in FIG. 3, the second conductive layers 18a and 18b can have a sharp cross-sectional shape at their tips.

The second conductive layers 18a and 18b include a plating metal. As the plating metal, Cu, Ni, Ag, Pd, an Ag—Pd alloy, Au, or the like is used.
The sintered metal contained in the first conductive layers 16a and 16b and the plated metal contained in the second conductive layers 18a and 18b are preferably the same metal. This is because it is better to be formed of the same metal. For example, when heat treatment is performed after the formation of the second conductive layers 18a and 18b, the first conductive layer 16a, the second conductive layer 18a, and the second conductive layer 18a Metals diffuse between each of the first conductive layer 16b and the second conductive layer 18b, the adhesion between the first conductive layer 16a and the second conductive layer 18a, and the first conductive layer This is because the adhesive force between 16b and the second conductive layer 18b is increased.
The thickness of the second conductive layers 18a and 18b is preferably 1 to 10 μm.

The third conductive layers 20a and 20b are preferably formed in consideration of the mountability of the ceramic electronic component 10 on the mounting substrate.
In this case, the third conductive layer 20a is formed on the one end face 30a so as to cover the second conductive layer 18a, and the third conductive layer 20b is covered with the second conductive layer 18b. Thus, it is formed on the other end face 30b. The third conductive layer 20a is formed so as to wrap around the one main surface 26a and the one side surface 28a, and the third conductive layer 20b is formed so as to wrap around the other main surface 26b and the other side surface 28b. Is done.

The third conductive layers 20a and 20b include a plated metal. As the plating metal, one kind of metal selected from the group consisting of Cu, Ni, Sn, Pb, Au, Ag, Pd, Bi, and Zn or an alloy containing the metal is used.
The third conductive layers 20a and 20b may be composed of a plurality of layers. For example, a two-layer structure in which the lower layer is Ni and the upper layer is Sn can be employed.

Then, one Embodiment of the manufacturing method of the ceramic electronic component 10 concerning this invention is described.
First, a ceramic green sheet, a conductive paste for internal electrodes, and a first conductive paste for external electrodes to be a first conductive layer are prepared. The ceramic green sheet and various conductive pastes include a binder resin and a solvent, and a known binder resin or organic solvent can be used. Further, the first external electrode conductive paste preferably contains a glass component.
Then, the internal electrode conductive paste is printed in a predetermined pattern on the ceramic green sheet by, for example, screen printing, and the internal electrode pattern is formed on the ceramic green sheet. Then, a predetermined number of ceramic green sheets for outer layers on which no internal electrode pattern is printed are stacked, and a predetermined number of ceramic green sheets on which the pattern of internal electrodes is printed are sequentially stacked. A predetermined number of unprinted outer layer ceramic green sheets are laminated to produce a raw mother laminate. This mother laminated body is pressure-bonded in the laminating direction by means such as an isostatic press as required.
Thereafter, the raw mother laminate is cut into a predetermined size, and the raw laminate is cut out. At this time, the corners and ridges of the laminate may be rounded by barrel polishing or the like.
Subsequently, the cut raw laminate is fired to produce a ceramic body that is a laminate. The firing temperature depends on the ceramic material and the internal electrode material, but is preferably 900 to 1300 ° C.
Then, a conductive paste for external electrodes is applied to both end faces of the ceramic body by a dip method, and baked to form a first conductive layer. At this time, the conductive paste applied to one end surface is applied so as not to wrap around the one main surface and one side surface of the ceramic body, and the conductive paste applied to the other end surface is the other main surface of the ceramic body. And it is applied so as not to wrap around the other side. The baking temperature is preferably 700 to 900 ° C.

Then, electrolytic plating is performed to form the second conductive layer so as to cover the first conductive layer. Plating grows using the first conductive layer as a nucleus, and the second conductive layer wraps around one main surface and the other main surface, one side surface and the other side surface.
Of the electrolytic plating, when strike plating is used, the growth of plating in the lateral direction (that is, the direction away from the one end face and the other end face) is easily promoted, and the thickness decreases as the distance from the one end face and the other end face increases.

  Here, Table 1 shows an example of the strike plating conditions in the present embodiment.

  In the present invention, electroless plating is not appropriate. This is because, in the case of electroless plating, the first main surface and the other main surface of the ceramic body and the plating are grown after applying a catalyst to the wraparound portion of the one side surface and the other side surface. This is because, since the plating grows with a uniform thickness from the side to the tip, it becomes difficult to realize a shape in which the thickness decreases as the distance from the one end surface and the other end surface increases.

Further, after the second conductive layer is formed, the second conductive layer may be heat-treated. By performing this heat treatment, the adhesion between the first conductive layer and the second conductive layer can be improved, and the adhesion between the second conductive layer and the ceramic body can be improved. Further, by performing this heat treatment, it is possible to remove the plating solution residue that has entered the ceramic body or remained at the interface between the second conductive layer and the ceramic body during the formation of the second conductive layer. it can. Thereby, the reliability of a ceramic electronic component can be improved. The temperature of this heat treatment is preferably 500 ° C. or higher. Further, the upper limit of the temperature of the heat treatment is selected as the lowest temperature among the temperatures at which the internal electrode, the first conductive layer, and the second conductive layer start to melt. For example, when Ni is used for the internal electrode and Cu is used for the first conductive layer and the second conductive layer, 1065 ° C. or the like is selected in consideration of the melting point of Cu (1083 ° C.).
And if necessary, a plating process is further performed to form a third conductive layer.

  According to the ceramic electronic component of the present invention, the thickness of the second conductive layer 18a formed on the one main surface 26a and the one side surface 28a is formed so as to become thinner as the distance from the one end surface 30a increases. Since the thickness of the second conductive layer 18b formed on the surface 26b and the other side surface 28b is formed so as to become thinner from the other end surface 30b, the ceramic electronic component 10 is manufactured at the time of manufacturing the ceramic electronic component 10. Even when a thermal shock is applied to the ceramic electronic component 10, the thermal contraction stress applied to the tip portions of the second conductive layers 18 a and 18 b is reduced, and a ceramic electronic component capable of preventing the occurrence of cracks in the ceramic electronic component 10 can be obtained. it can.

  According to the ceramic electronic component of the present invention, the sintered metal contained in the first conductive layers 16a and 16b and the plated metal contained in the second conductive layers 18a and 18b are formed of the same metal, and By applying a heat treatment after the formation of the second conductive layers 18a and 18b, the metals diffuse between each other, so that the adhesion between the first conductive layer 16a and the second conductive layer 18a, and the first The adhesion between the conductive layer 16b and the second conductive layer 18b can be increased.

  Furthermore, according to the method for manufacturing a ceramic electronic component according to the present invention, the thickness of the second conductive layer 18a formed on the one main surface 26a and the one side surface 28a is reduced as the distance from the one end surface 30a increases. The thickness of the second conductive layer 18b formed on the other main surface 26b and the other side surface 28b is formed so as to become thinner from the other end surface 30b. Therefore, the second conductive layer 18a and Since the tip portion of 18b is formed to be the thinnest, even when a thermal shock is applied to the ceramic electronic component 10 during the manufacture of the ceramic electronic component 10, the thermal contraction stress applied to the tip portions of the second conductive layers 18a and 18b. Therefore, the generation of cracks in the ceramic electronic component 10 can be prevented and the ceramic electronic component 10 can be manufactured. Kill.

  Although the third conductive layers 20a and 20b are formed so as to cover the second conductive layers 18a and 18b in the external electrodes 14a and 14b of the ceramic electronic component 10 according to the present invention, they are not necessarily formed. It does not have to be.

  In the embodiment according to the present invention, the multilayer ceramic capacitor is used as the ceramic electronic component. However, the present invention is not limited to this, and the ceramic electronic component according to the present invention can be used for an inductor, a multilayer ceramic LC filter, and a thermistor. Can also be used. That is, the ceramic body 12 functions as a capacitor when a dielectric ceramic is used, functions as a piezoelectric component when a piezoelectric ceramic is used, and functions as a thermistor when a semiconductor ceramic is used. When is used, it functions as an inductor.

  The ceramic electronic component and the manufacturing method thereof according to the present invention are suitably used when manufacturing a ceramic electronic component such as a multilayer ceramic capacitor.

DESCRIPTION OF SYMBOLS 10 Ceramic electronic component 12 Ceramic body 14a, 14b External electrode 16a, 16b 1st conductive layer 18a, 18b 2nd conductive layer 20a, 20b 3rd conductive layer 22 Ceramic layer 24a, 24b Internal electrode 26a One main surface 26b Other main surface 28a One side surface 28b The other side surface 30a One end surface 30b The other end surface 32 Corner portion 34 Ridge portion

Claims (4)

A pair of main surfaces facing each other, a pair of side surfaces facing each other, a pair of end surfaces facing each other, a plurality of ceramic layers made of a dielectric, and at least alternately formed between the plurality of ceramic layers A pair of internal electrodes; a ceramic body comprising: a pair of external electrodes formed on the end face of the ceramic body to be connected to the internal electrodes;
A ceramic electronic component comprising:
Each pair constituting the at least one pair of internal electrodes is formed such that one end portion of one internal electrode extends to one end surface of the ceramic body, and one end portion of the other internal electrode is the ceramic body. Extending to the other end surface of the
The external electrode is
A first conductive layer that is formed on the end surface and does not wrap around any of the main surface and the side surface;
A second conductive layer formed on the end surface so as to cover the first conductive layer and wrapping around the main surface and the side surface;
Have
The first conductive layer includes Ni sintered metal;
The second conductive layer includes a Cu-plated metal;
The second conductive layer is formed on the main surface and the side surface so as to become thinner as the distance from the end surface increases.
The length of the second conductive layer formed so as to contact the main surface and the side surface in the direction connecting the pair of end surfaces is the first length formed on the first conductive layer. Longer than the thickness in the direction connecting the pair of end faces of the two conductive layers,
When the ceramic body is viewed from the stacking direction, the second conductive layer and the ceramic body are in direct contact with each other in a region where the second conductive layer and the internal electrode overlap.
When viewed said ceramic body from said stacking direction, end of the second conductive layer, and characterized in that it is formed to span the internal electrodes on the side not is drawn to the end face Multilayer ceramic capacitor.   2. The multilayer ceramic capacitor according to claim 1, wherein the sintered metal contained in the first conductive layer and the plated metal contained in the second conductive layer are the same metal. A pair of main surfaces facing each other, a pair of side surfaces facing each other, a pair of end surfaces facing each other, a plurality of ceramic layers made of a dielectric, and at least alternately formed between the plurality of ceramic layers Preparing a ceramic body including a pair of internal electrodes;
A first conductive layer is formed by applying and baking a conductive paste containing Ni so as to be connected to the internal electrode on the end surface so as not to wrap around the main surface and the side surface. Forming a step;
The ceramic body is plated so as to cover the first conductive layer, to wrap around the main surface and the side surface, and to become thinner as the distance from the end surface increases. Forming a second conductive layer by strike plating containing Cu;
With
When the ceramic body is viewed from the stacking direction, the second conductive layer and the ceramic body are in direct contact with each other in a region where the second conductive layer and the internal electrode overlap, and the ceramic body when viewed the body from the stacking direction, end portions of the second conductive layer, characterized in that it is formed to span the inner electrode of said end not drawn to surface side, the laminated ceramic Capacitor manufacturing method. The first conductive layer includes a sintered metal;
The second conductive layer includes a plated metal;
The sintered metal contained in the first conductive layer and the plating metal contained in the second conductive layer are formed of the same metal,
The method for manufacturing a multilayer ceramic capacitor according to claim 3, comprising a step of heat-treating the second conductive layer.

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