JP6330484B2 - Ceramic electronic components - Google Patents

Description

  The present invention relates to a ceramic electronic component, and more particularly to a ceramic electronic component such as a multilayer ceramic capacitor or a multilayer ceramic inductor.

  An example of a multilayer ceramic capacitor as a conventional ceramic electronic component is described in, for example, Japanese Patent Application Laid-Open No. 2011-165935 (Patent Document 1). In such a multilayer ceramic capacitor, a plurality of internal electrodes are arranged in a ceramic body (ceramic sintered body) so as to overlap with each other via a ceramic layer, and external electrodes that are electrically connected to the internal electrodes are ceramic on both end surfaces of the ceramic body. It is formed on the end surface, both main surfaces and both side surfaces of the main body. In such a multilayer ceramic capacitor, the cross-sectional shape of the external electrode usually has one peak shape that swells outward due to the surface tension of the conductive paste constituting the external electrode on each surface of the ceramic body. ing. This mountain shape tends to occur as the area of the external electrode increases.

JP 2011-165935 A

In such a conventional multilayer ceramic capacitor, since the external electrode has a single crest shape, there is a problem that the resin and solvent contained in the conductive paste constituting the external electrode tend to stay in the external electrode. is there.
That is, in the degreasing process at the time of firing the external electrode, organic substances constituting the resin and the solvent are carbonized and then combined with oxygen to generate carbon dioxide gas. This carbon dioxide gas is normally discharged out of the external electrode from the thin part at the end of the external electrode. When the external electrode is formed in one ridge shape, the central part In the thickest part of the film, the carbon dioxide gas is not successfully discharged out of the external electrode, which may cause a problem of blistering of the external electrode, that is, a blister.
The problem that blisters are generated in this way occurs not only in the above-mentioned multilayer ceramic capacitors but also in other ceramic electronic components such as multilayer ceramic inductors having external electrodes having the same structure as the external electrodes of such multilayer ceramic capacitors. There are things to do.

  Therefore, a main object of the present invention is to provide a ceramic electronic component capable of suppressing the generation of blisters.

A ceramic electronic component according to the present invention includes a ceramic body having a pair of main surfaces facing each other, a pair of side surfaces facing each other, and a pair of end surfaces facing each other, and is disposed inside the ceramic body and exposed to the end surface of the ceramic body. An internal electrode having an exposed portion, and a pair of external electrodes formed so as to be electrically connected to the exposed portion of the internal electrode from the end surface to at least a pair of main surfaces on the pair of end surface sides of the ceramic body, A ceramic electronic component having a plating film formed on the external electrode, wherein the length in the direction connecting the pair of main surfaces of the ceramic body is the length of the external electrode formed on the main surface of the ceramic body It is formed shorter than the length in the direction connecting the pair of end faces of the ceramic body and formed on the main surface of the ceramic body. Together have a depression in the central portion of the external electrode that is characterized by not having a recess in the external electrode formed on the end surface of the ceramic body, a ceramic electronic component.
In the ceramic electronic component according to the present invention, for example, in the external electrode formed on the main surface of the ceramic body, the thickness of the recessed portion with respect to the thickest portion is 12% or more.
In the ceramic electronic component according to the present invention, for example, the cross-sectional shape of the external electrode formed on the main surface of the ceramic body is recessed at the center of the external electrode, and has two crests. Moreover, the cross-sectional shape of the external electrode formed on the end surface of the ceramic body does not have a depression.

  In the ceramic electronic component according to the present invention, the length in the direction connecting the pair of main surfaces of the ceramic body is the length of the external electrode formed on the main surface of the ceramic body, and the pair of end surfaces of the ceramic body The external electrode is formed in the degreasing step when baking the external electrode because the central portion of the external electrode formed on the main surface of the ceramic body has a recess. Carbon dioxide generated with carbonization of the resin and solvent in the conductive paste can be easily discharged, and the generation of blisters can be suppressed.

  As a blister suppression mechanism in the present invention, in the external electrode formed on the main surface of the ceramic body, the central portion of the external electrode is recessed, so that the escape path of carbon dioxide gas generated with the carbonization of the resin or solvent is By providing not only the thinnest part at the end of the electrode but also the central part of the external electrode, carbon dioxide gas is easily discharged out of the external electrode in the degreasing step when baking the external electrode. Therefore, the carbon dioxide gas generated with the carbonization of the resin or solvent contained in the conductive paste constituting the external electrode can be sufficiently discharged out of the external electrode. And since the carbon dioxide gas discharged | emitted out of an external electrode does not exist at the time of sintering of the external electrode after degreasing | defatting, generation | occurrence | production of a blister can be suppressed.

  In the ceramic electronic component according to the present invention, the end face of the ceramic body having the exposed portion of the internal electrode is made smaller by reducing the distance between the pair of main faces of the ceramic body, that is, by reducing the thickness dimension of the ceramic body. Because the distance from the thick part at the center of the external electrode to the thin part at the end of the external electrode is shorter than when the thickness of the ceramic body is thick, the external electrode at the center of the external electrode It becomes easy to discharge the carbon dioxide gas generated inside the outside electrode. Therefore, carbon dioxide in the external electrode can be exhausted sufficiently outside the external electrode, so there is no carbon dioxide exhausted outside the external electrode during sintering of the external electrode after degreasing, and blisters are generated. Can be suppressed.

  Furthermore, in the ceramic electronic component according to the present invention, even if the external electrode is formed on the side surface of the ceramic body, the thickness of the ceramic body is reduced as in the case of the external electrode on the end surface of the ceramic body. Since the distance from the thick part at the center of the external electrode to the thin part at the end of the external electrode is shorter than when the thickness is thick, carbon dioxide in the external electrode at the center of the external electrode Can be easily discharged out of the external electrode.

Further, according to the present invention, moisture resistance reliability can be maintained by not adopting the plurality of crest shapes of the external electrode on the end face of the ceramic body.
That is, also on the end face of the ceramic body having the exposed portion of the internal electrode, in the same manner as the external electrode on the main surface of the ceramic body, the cross-sectional shape of the external electrode is made into a plurality of mountain shapes, and a measure for increasing the escape route of carbon dioxide gas is taken. It is possible.
However, if the external electrode is made into a plurality of peaks on the end face of the ceramic body, the thickness of the external electrode is reduced at the center of the external electrode, so that plating solution and moisture in the atmosphere enter the internal electrode side from that part. There is a concern that moisture resistance may be reduced.
Therefore, in the present invention, the design as described above is adopted, and the generation of blisters is suppressed while maintaining the moisture resistance reliability. Therefore, in this invention, generation | occurrence | production of a blister can be suppressed, maintaining moisture resistance reliability.

  According to the present invention, a ceramic electronic component capable of suppressing the generation of blisters is 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.

It is a perspective view which shows an example of the multilayer ceramic capacitor concerning this invention. FIG. 2 is a side view of the multilayer ceramic capacitor shown in FIG. 1. It is sectional drawing in line III-III of FIG.

A monolithic ceramic capacitor 10 shown in FIG. 1 includes, for example, a rectangular parallelepiped thin ceramic body 12. The ceramic body 12 includes a plurality of laminated ceramic layers 14, and includes a pair of main surfaces 12a and 12b facing each other, a pair of side surfaces 12c and 12d facing each other, and a pair of end surfaces 12e and 12f facing each other. Have.
In the multilayer ceramic capacitor 10 of this embodiment, the ceramic body 12 is formed in a rectangular parallelepiped shape, but the shape of the ceramic body 12 is not particularly limited.
The ceramic body 12 is preferably rounded at the corner and ridge.

The ceramic main body 12 has a length (thickness dimension DT: see FIG. 1) in a direction in which the pair of main surfaces 12a and 12b of the ceramic main body 12 are connected to each other. The length of the external electrode 20a (20b) is shorter than the length in the direction connecting the pair of end faces 12e, 12f of the ceramic body 12 (electrode part dimension DE1 (electrode part dimension DE2): see FIG. 3). Has been.
The dimensions of the ceramic body 12 are not particularly limited. As shown in FIG. 1, the ceramic body 12 has a thickness DT, a length dimension DL, and a width dimension DW, where DT < It may be thin so that DW <DL, (1/5) DW ≦ DT ≦ (1/2) DW, or DT <0.3 mm. In particular, when DT <DW <DL, the thickness of the ceramic body 12 is thin and the length of the ceramic body 12 is longer than the width of the ceramic body 12. In the case of (1/5) DW ≦ DT ≦ (1/2) DW, the thickness of the ceramic body 12 is as thin as 1/5 to 1/2 of the width of the ceramic body 12. Specifically, it may be 0.05 mm ≦ DT <0.3 mm, 0.4 mm ≦ DL ≦ 1 mm, 0.3 mm ≦ DW ≦ 0.5 mm.

As the ceramic material of the ceramic layer 14 of the ceramic body 12, for example, a dielectric ceramic composed of main components such as BaTiO ₃ , CaTiO ₃ , SrTiO ₃ , 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.
The thickness of the ceramic layer 14 of the ceramic body 12 is preferably 0.5 μm to 10 μm.

  In this embodiment, in each effective portion of the ceramic body 12, internal electrodes 16a and 16b, which will be described later, face each other through a ceramic layer 14 made of a dielectric ceramic, thereby forming a capacitance. Thereby, this embodiment functions as a capacitor.

Inside the ceramic body 12, a plurality of first and second internal electrodes 16 a and 16 b having a substantially rectangular shape are alternately arranged at equal intervals along the thickness direction of the ceramic body 12.
The first and second internal electrodes 16a and 16b have exposed portions 18a and 18b exposed at the end surfaces 12e and 12f of the ceramic body 12 at one end portions. Specifically, the exposed portion 18 a at one end of the first internal electrode 16 a is exposed at the first end surface 12 e of the ceramic body 12. Further, the exposed portion 18 b at one end of the second internal electrode 16 b is exposed at the second end surface 12 f of the ceramic body 12.
Further, each of the first and second internal electrodes 16 a and 16 b is parallel to the first and second main surfaces 12 a and 12 b of the ceramic body 12. The first and second internal electrodes 16 a and 16 b face each other with the ceramic layer 14 in the thickness direction of the ceramic body 12.
Each thickness of the 1st and 2nd internal electrodes 16a and 16b can be 0.2 micrometer-2 micrometers, for example. However, the thickness of each of the first and second internal electrodes 16a and 16b is not particularly limited.
The first and second internal electrodes 16a and 16b can be made of an appropriate conductive material. The first and second internal electrodes 16a and 16b may be made of, for example, a metal such as Ni, Cu, Ag, Pd, or Au, or an alloy such as an Ag—Pd alloy containing one of these metals. it can.

First and second external electrodes 20a and 20b are formed on the end faces 12e and 12f of the ceramic body 12, respectively.
The first external electrode 20a is formed from the first end surface 12e of the ceramic body 12 to the pair of main surfaces 12a, 12b and the pair of side surfaces 12c, 12d. In this case, the first external electrode 20a is electrically connected to the exposed portion 18a of the first internal electrode 16a.
The second external electrode 20b is formed from the second end surface 12f of the ceramic body 12 to the pair of main surfaces 12a and 12b and the pair of side surfaces 12c and 12d. In this case, the second external electrode 20b is electrically connected to the exposed portion 18b of the second internal electrode 16b.

A length dimension DE (electrode part dimension DE1) in the direction of connecting the pair of end faces 12e, 12f of the ceramic body 12 to the length of the external electrode 20a (20b) formed on the main surfaces 12a, 12b of the ceramic body 12. (Electrode part dimension DE2)) is longer than the thickness dimension DT of the ceramic body 12.
The length dimension DE (electrode part dimension DE1 (electrode part dimension DE2)) of the external electrode 20a (20b) formed on the main surfaces 12a and 12b of the ceramic body 12 and the pair of main surfaces 12a and 12b of the ceramic body 12 As for the length dimension in the direction of connecting, that is, the thickness dimension DT of the ceramic body 12, the DE / DT value is preferably 1.5 to 3.5. If DE / DT is smaller than 1.5, blisters are likely to occur at the end face of the external electrode 20a (20b), and if DE / DT exceeds 3.5, the ceramic body 12 and the external electrode 20a (20b). This is because migration tends to occur between the two.

Further, in the central portion of the first external electrode 20a formed on the main surfaces 12a and 12b of the ceramic body 12, there are recessed portions 22a1 and 22a2 in order to suppress generation of blisters while maintaining moisture resistance reliability. Is formed. As a result, the cross-sectional shape of the first external electrode 20a formed on the main surface 12a (12b) of the ceramic body 12 is recessed at the center of the external electrode 20a. have.
Similarly, depressions 22b1 and 22b2 are also formed in the central portion of the second external electrode 20b formed on the main surfaces 12a and 12b of the ceramic body 12 in order to suppress generation of blisters while maintaining moisture resistance reliability. Each is formed. As a result, the cross-sectional shape of the second external electrode 20b formed on the main surface 12a (12b) of the ceramic body 12 is recessed at the center of the external electrode 20b. have.

  In the cross-sectional shape of the external electrode 20a (20b) formed on the main surfaces 12a and 12b of the ceramic body 12, the ratio of the depth of the recessed portion to the thickness of the highest portion of the portion having a mountain shape is 12%. The above is preferable. That is, in the external electrode 20a (20b) formed on the main surfaces 12a and 12b of the ceramic body 12, the thickness of the recessed portion with respect to the thickest portion is preferably 12% or more. This is because if the ratio is smaller than 12%, the depth of the recesses 22a1, 22a2 (22b1, 22b2) of the external electrode 20a (20b) is too shallow, and it is difficult to obtain the effect of suppressing blisters. .

  Moreover, it is preferable that the height difference of the recessed parts 22a1, 22a2, 22b1, 22b2 of the first and second external electrodes 20a, 20b is 1.5 μm or more, respectively. This is because when the height difference between the depressions 22a1, 22a2, 22b1, 22b2 of the external electrodes 20a, 20b is smaller than 1.5 μm, a sufficiently thin portion cannot be formed locally, and the external electrode 20a This is because the carbon dioxide gas generated from 20b cannot be sufficiently discharged from the external electrodes 20a and 20b, and the blister suppression effect may not be obtained. Further, the upper limit value of the height difference of the depressions 22a1, 22a2, 22b1, 22b2 of the external electrodes 20a, 20b may be within a range where the surface of the ceramic body 12 is not exposed.

  Furthermore, the positions of the recesses 22a1, 22a2, 22b1, 22b2 of the first and second external electrodes 20a, 20b formed on the main surfaces 12a, 12b of the ceramic body 12 are the center in the width direction and the length direction, respectively. It is preferable to form in the part. This is because, when the conductive paste is applied to the end of the ceramic body 12 by dipping the end of the ceramic body 12 in the conductive paste constituting the external electrode 20a (20b), the surface tension of the conductive paste This is because the coating thickness of the central portion of the external electrode 20a (20b) becomes the thickest, and a more remarkable effect can be exhibited by the presence of the recessed portion in the central portion.

In addition, the size of the recesses 22a1, 22a2, 22b1, 22b2 of the first and second external electrodes 20a, 20b formed on the main surfaces 12a, 12b of the ceramic body 12 is 10 μm to 100 μm in diameter, respectively. Is preferred. This is because, when the diameters of the recesses 22a1, 22a2, 22b1, and 22b2 are smaller than 10 mm, a sufficiently thin portion cannot be locally formed, and the carbon dioxide in the external electrodes 20a and 20b is sufficiently large. 20b cannot be discharged, and the blister suppression effect may not be obtained. Further, when the diameters of the recesses 22a1, 22a2, 22b1, 22b2 are larger than 100 mm, the depth of the recess increases as the recess diameter increases, so that the surface of the ceramic body 12 is exposed, and the external electrode 20a, This is because defects with plating of the plating films 24a and 24b formed on 20b may occur.
The diameters of the recesses 22a1, 22a2, 22b1, 22b2 of the external electrodes 20a, 20b show a two-dimensional uneven image on the surface of the external electrodes 20a, 20b with a surface roughness measuring machine, and the height difference is 1.5 μm. The above was judged as a hollow part, and the diameter was measured from the one-dimensional data.

The first and second external electrodes 20a and 20b include a glass component and a metal component.
As the metal of the first and second external electrodes 20a and 20b, for example, Cu, Ni, Ag, Pd, an Ag—Pd alloy, Au, or the like can be used.
The particle diameter of the metal powder constituting the metal component of the first and second external electrodes 20a, 20b is preferably 1 μm to 2.5 μm. In addition, in this application, the average particle diameter of metal powder means the particle diameter in the integrated value 50% in the particle size distribution calculated | required by the laser diffraction / scattering method.

In the embodiment according to the present invention, the average particle diameter of the metal powder in the external electrodes 20a and 20b is 1 μm to 2.5 μm, and the resin content in the external electrode paste is 40 to 55 vol%. When the external electrode paste is applied and then dried, the metal powder easily flows due to the drying and flow of the solvent and resin, and the central portions of the external electrodes 20a and 20b, which are the characteristics of the embodiment of the present invention, are depressed. When viewed as a whole, two mountain shapes are realized. Specifically, when the external electrode paste forming the external electrode 20a (20b) is dried, the solvent or resin in the external electrode paste has a smaller coating film thickness than the solvent or resin in the external electrode paste. It is easy to dry and the solvent and resin flow from a thick part to a thin part. In that case, since the average particle diameter of the metal powder which comprises a base electrode (external electrode) is made small, the flow of a metal powder will also occur easily with the flow of the solvent and resin. Therefore, the metal powder also moves from the thick central part to the end of the thin external electrode 20a (20b), and the central part of the external electrode 20a (20b) is depressed.
In this embodiment, since the thickness of the ceramic body 12 is thin, the external electrodes 20a and 20b cannot have depressions on the side surfaces and end surfaces of the ceramic body 12.

  Moreover, it is preferable that the metal powder which comprises the metal component of the 1st and 2nd external electrodes 20a and 20b has an aspect ratio of 8-15. This is because it is possible to increase the porosity in the external electrode paste by using a flat powder having an aspect ratio of 8 to 15, so that a resin or a solvent is used in the degreasing process during firing of the external electrodes 20a and 20b. This is to make it easier to discharge the carbon dioxide gas generated with the carbonization to the outside of the external electrode. Thus, when flattened powder is used, the porosity in the paste is increased, so that carbon dioxide gas is easily released during the degreasing process of the external electrodes 20a and 20b.

First and second plating films 24a and 24b are formed on the first and second external electrodes 20a and 20b, respectively. In this case, the first and second external electrodes 20a and 20b are covered with the first and second plating films 24a and 24b. The first and second plating films 24a, 24b are at least one metal selected from the group consisting of Cu, Ni, Sn, Pd, Au, Ag, Pt, Bi, and Zn, or at least one of these metals It is preferable that it is comprised with the alloy containing these metals.
Further, each of the first and second plating films 24a and 24b may be composed of only one layer of plating film, or may be composed of two or more layers of plating films. The plating film 24a (24b) preferably has a two-layer structure of a Ni plating film and a Sn plating film. In this case, the Ni plating film functions as a barrier layer, and the Sn plating film functions to improve solderability.
The thickness per one plating layer constituting the first and second plating films 24a and 24b is preferably, for example, about 1 μm to 15 μm.
In the plating films 24a and 24b, similar recesses 26a1, 26a2, 26b1, and 26b2 are formed corresponding to the recesses 22a1, 22a2, 22b1, and 22b2 of the external electrodes 20a and 20b. However, the depressions may not be formed in the plating films 24a and 24b.

  Next, an example of a method for manufacturing the above-described multilayer ceramic capacitor 10 will be described.

  First, a ceramic green sheet containing a ceramic material for constituting the ceramic body 12 (ceramic layer 14) is prepared.

Next, a conductive pattern is formed on the ceramic green sheet by applying a conductive paste. In addition, application | coating of an electrically conductive paste can be performed by various printing methods, such as a screen printing method, for example. Conductive paste, in addition to the conductive fine particles may include known bus Indah or solvents.

  A plurality of ceramic green sheets on which no conductive pattern is formed; a ceramic green sheet on which a conductive pattern having a shape corresponding to the first or second internal electrode is formed; and a plurality of ceramic green sheets on which no conductive pattern is formed. The ceramic green sheets are laminated in this order and pressed in the laminating direction to produce a mother laminated body.

  Then, by cutting the mother laminate along a virtual cut line on the mother laminate, a plurality of raw ceramic laminates are produced from the mother laminate. Note that the cutting of the mother laminate can be performed by dicing or pressing. The raw ceramic laminate may be subjected to barrel polishing or the like to round the ridge line portion or the corner portion.

  Then, the raw ceramic laminate is fired. In the firing step, the first and second internal electrodes are fired. The firing temperature can be appropriately set depending on the type of ceramic material and conductive paste used. The firing temperature can be, for example, 900 ° C. to 1300 ° C.

  Then, a conductive paste is applied to both ends of the fired ceramic laminate (ceramic body) by a method such as dipping.

  Next, the conductive paste applied to the ceramic laminate is dried with hot air at 60 ° C. to 180 ° C. for 10 minutes, for example.

  Thereafter, the dried conductive paste is baked to form external electrodes. The baking of the external electrode has a degreasing process for degreasing the resin component in the external electrode paste and a sintering process for sintering the metal powder by liquid crystal. The characteristics of the above-described embodiment are particularly effective in the degreasing process.

The conductive paste used for forming the external electrode contains glass powder, metal powder, a binder, a solvent, and the like. The aspect ratio of the metal powder in the conductive paste is preferably 8-15. This makes it possible to increase the porosity in the external electrode paste during the drying process of the external electrode, so that the resin and solvent components can be easily discharged as carbon dioxide in the degreasing process during firing of the external electrode. ing. In addition, the connectivity between the internal electrode and the external electrode is improved. The heat treatment temperature is preferably 780 ° C to 870 ° C, for example. This is because when the heat treatment temperature is lower than 780 ° C., the metal Cu of the external electrode is not sufficiently sintered and the denseness is lowered, so that the moisture resistance reliability may be lowered. On the other hand, when the heat treatment temperature exceeds 870 ° C., the flow of the glass in the external electrode becomes significant, and the glass may float on the surface of the external electrode. Because.
In addition, it is preferable that the temperature increase rate at the time of baking of an external electrode is 150-250 degreeC / min.

  The multilayer ceramic capacitor 10 can be manufactured by applying a plating film on the external electrode.

  In the multilayer ceramic capacitor 10, the ceramic body 12 has a length (thickness dimension DT) in a direction connecting the pair of main surfaces 12 a and 12 b of the ceramic body 12 on the main surfaces 12 a and 12 b of the ceramic body 12. The external electrode 20a (20b) has a length shorter than the length (electrode part dimension DE1 (electrode part dimension DE2)) in the direction connecting the pair of end faces 12e and 12f of the ceramic body 12. The cross-sectional shape of the external electrode 20a (20b) formed on the main surfaces 12a and 12b of the main body 12 is recessed at the center of the external electrode 20a (20b), and has two peaks when viewed as a whole. Therefore, in the degreasing process when baking the external electrode 20a (20b), the conductive paste constituting the external electrode 20a (20b) Of it with a resin or solvent carbon dioxide generated with the carbide easily discharged, it is possible to suppress the occurrence of blisters.

  As this blister suppression mechanism, in the external electrode 20a (20b) formed on the main surfaces 12a and 12b of the ceramic body 12, the central portion of the external electrode 20a (20b) is depressed, and the cross-sectional shape of the external electrode 20a (20b) is formed. Is formed into two crests, so that the escape path of carbon dioxide gas generated by carbonization of the resin or solvent is not limited to the portion where the film thickness is the thinnest at the end of the external electrode 20a (20b). By providing also in the center part of 20a (20b), a carbon dioxide gas becomes easy to be discharged | emitted out of the external electrode 20a (20b) in the degreasing process at the time of baking the external electrode 20a (20b). Therefore, the carbon dioxide gas generated with the carbonization of the resin or solvent contained in the conductive paste constituting the external electrode 20a (20b) can be sufficiently discharged out of the external electrode 20a (20b). And since the carbon dioxide gas discharged | emitted out of the external electrode 20a (20b) does not exist at the time of sintering of the external electrode 20a (20b) after degreasing | defatting, generation | occurrence | production of a blister can be suppressed.

  In the multilayer ceramic capacitor 10, the end surfaces 12e and 12f of the ceramic main body 12 having the exposed portions 18a and 18b of the internal electrodes 16a and 16b are made small by reducing the distance between the pair of main surfaces 12a and 12b of the ceramic main body 12. That is, by reducing the thickness dimension DT of the ceramic body 12, the external electrode 20 a (20 b) starts from the thicker portion at the center of the external electrode 20 a (20 b) than when the thickness dimension DT of the ceramic body 12 is thick. Since the distance to the thin film portion at the end portion is shortened, carbon dioxide gas generated in the external electrode 20a (20b) at the center of the external electrode 20a (20b) is discharged out of the external electrode 20a (20b). It becomes easy. Therefore, since the carbon dioxide gas in the external electrode 20a (20b) can be sufficiently discharged out of the external electrode 20a (20b), the external electrode 20a (20b) is sintered during the degreasing of the external electrode 20a (20b). There is no carbon dioxide gas discharged outside, and the generation of blisters can be suppressed.

  Furthermore, in the multilayer ceramic capacitor 10, the external electrodes 20a (20b) on the side surfaces 12c and 12d of the ceramic body 12 are also similar to the external electrodes 20a (20b) on the end surfaces 12e and 12f of the ceramic body 12 and By reducing the thickness dimension DT, the thickness of the end portion of the external electrode 20a (20b) from the thick part of the central portion of the external electrode 20a (20b) to the thickness of the ceramic body 12 is larger than when the thickness dimension DT of the ceramic body 12 is thick. Since the distance to the thin portion is shortened, the carbon dioxide gas in the external electrode 20a (20b) at the center of the external electrode 20a (20b) can be easily discharged out of the external electrode 20a (20b).

Further, in this multilayer ceramic capacitor 10, moisture resistance reliability can be maintained by not adopting the two crest shapes of the external electrode 20 a (20 b) on the end faces 12 e and 12 f of the ceramic body 12.
That is, in the end surfaces 12e and 12f of the ceramic main body 12 having the exposed portions 18a and 18b of the internal electrodes 16a and 16b, the external electrodes 20a (20b) are the same as the external electrodes 20a (20b) on the main surfaces 12a and 12b of the ceramic main body 12. It is conceivable to take a measure to increase the escape route of carbon dioxide gas by setting the cross-sectional shape of 20b) to two mountain shapes.
However, if the external electrode 20a (20b) is formed in two crests on the end faces 12e and 12f of the ceramic body 12, the thickness of the external electrode 20a (20b) is reduced at the center of the external electrode 20a (20b). From this portion, the plating solution and the moisture in the air easily enter the external electrode 20a (20b), and there is a concern that the moisture resistance is lowered.
Therefore, the multilayer ceramic capacitor 10 has the above-described design, and suppresses the generation of blisters while maintaining moisture resistance reliability. Therefore, in this multilayer ceramic capacitor 10, it is possible to suppress the generation of blisters while maintaining moisture resistance reliability.

  Furthermore, in this multilayer ceramic capacitor 10, since the external electrodes 20a (20b) are also formed on the side surfaces 12c and 12d of the ceramic body 12, there is an effect of improving moisture resistance reliability.

  Further, in this multilayer ceramic capacitor 10, since the recesses 22a1, 22a2, 22b1, 22b2 are formed in the external electrodes 20a, 20b, the plating films 24a, 24b on the external electrodes 20a, 20b are connected to the external electrodes 20a, 20b. In addition, the effect is that it is formed firmly and hardly peeled off from the external electrodes 20a and 20b.

(Experimental example)
First, as Example 1, Example 2, and Example 3, it becomes the following electronic component specifications in the above-mentioned multilayer ceramic capacitor 10, and the conductive paste constituting the external electrode is applied to both end faces of the ceramic body and dried. A shape whose shape after baking was within the scope of the present invention was prepared. In this case, in Example 1, the height difference of the recessed part of the external electrode is aimed at 1.5 μm, in Example 2, the height difference of the recessed part of the external electrode is aimed at 4 μm, and in Example 3, the height difference of the recessed part of the external electrode is aimed. Examples 1 to 3 were prepared aiming at the difference of 6 μm.

Specifications of electronic parts used in Examples 1 to 3 (number n = 20)
Chip size: DL x DW x DT = 1.0 mm x 0.5 mm x 0.15 mm
Dimension DE of external electrode folded part (electrode part dimension DE of external electrode formed on main surface and side surface of ceramic body): 200 μm to 400 μm (target value is 300 μm)
Metal in the conductive paste constituting the external electrode: Cu
Average particle diameter of Cu (Cu powder): Refer to the metal particle diameter in Table 1 Aspect ratio of Cu powder: 10 (This aspect ratio was obtained by hitting Cu powder having the above particle diameter)
Drying conditions of the conductive paste constituting the external electrode: hot air drying at 100 ° C. for 10 minutes External electrode baking conditions: temperature increase rate of 196 ° C./min and baking temperature of 835 ° C.
The thickness of the folded portion of the external electrode: 8 μm to 13 μm (thickest part) (target is 10 μm)
End face thickness of external electrode: 6 μm to 12 μm (thickest part) (target is 9 μm)
Plating film: Ni plating (target 3 μm) and Sn plating (target 4 μm)

  Furthermore, as Comparative Example 1, the chip in which the shape of the conductive paste constituting the external electrode after drying is a single crest shape, and as Comparative Example 2, the width dimension DW and the thickness dimension DT of the ceramic body are the same. Prepared with a regular quadrangular columnar chip (external electrode dimensions are longer on the external electrode formed on the end surface of the ceramic body than on the external electrode formed on the main surface of the ceramic body) did.

In Comparative Example 1, the average particle diameter of the metal powder in the conductive paste constituting the external electrode is 3.5 μm, and the aspect ratio of the metal powder is 1. In Comparative Example 2, the conditions were the same as in Example 3 except that the chip size was a regular quadrangular prism (ceramic body thickness dimension DT = width dimension DW = 0.5 mm).
Moreover, in Examples 1-3 of this invention, the value of the metal particle diameter was changed and the height difference of the hollow part was changed.

  And about the sample of Comparative Examples 1-2 and Examples 1-3, the height difference of a hollow part, height difference / external electrode film thickness, the number of crests of an electrode, metal particle diameter, generation | occurrence | production of a blister are performed as follows. The rate and IR deterioration rate were examined.

About the height difference of the dent part The method of measuring the height difference of the dent part is to first polish the side surface to a position where the width of the sample (multilayer ceramic capacitor) becomes 1/2, and then two peaks of the external electrode in the polished cross section. Connect vertices with a line. Thereafter, using the line as a reference line, a line passing through the lowest point of the recess of the external electrode is drawn so as to be parallel to the reference line. Finally, the distance from the reference line to the line passing through the lowest point of the depression is measured, and the difference in height of the depression or the difference in height of the depression is obtained. The measured value was an average value obtained by measuring four points of the first and second external electrodes. Moreover, the value of the height difference of the hollow part of Table 1 was made into the average value of 20 samples.

Height difference / external electrode film thickness First, as the external electrode film thickness, the side surface of the sample (multilayer ceramic capacitor) was polished along the length direction to the center position in the width direction of the sample, and the external electrode in the polished cross section The portion having the maximum thickness was measured with an optical microscope. In other words, the external electrode film thickness is the distance from the surface of the ceramic body to the farthest part of the external electrode (for example, the higher of the two peaks), that is, the thickness of the thickest part. And the height difference of the above-mentioned hollow part about an external electrode was divided by the measured value of the external electrode film thickness, and it was set as height difference / external electrode film thickness. The value of the height difference / external electrode film thickness in Table 1 was an average value of 20 samples.

Regarding the number of ridges of the electrode First, the surface of the external electrode was shown as a two-dimensional concavo-convex image with a surface roughness measuring machine, and the one having a height difference of 1.5 μm or more was judged as a depression. And the number of the crests of the electrode of Table 1 was set to 1 when there was no hollow part, and was set to 2 with one hollow part.

About metal particle diameter As a metal particle diameter, the average particle diameter of the metal powder in the electrically conductive paste which comprises an external electrode was measured. The average particle size of the metal powder refers to the particle size at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method.

About the incidence of blisters Using a stereomicroscope, the external electrodes on both main surfaces of the multilayer ceramic capacitor were observed at a magnification of 10 to confirm the presence or absence of blisters. The blister is defined as a blister having a diameter of 5 μm or more. The number of samples was 20, and the incidence of blisters about them was examined.

About the deterioration rate of IR The moisture resistance load test was done with the following method and the weather resistance was evaluated.
The sample was mounted on a glass epoxy substrate using eutectic solder. Thereafter, each sample was subjected to a moisture resistance acceleration test under a condition of DC 4 V, 500 hours in a high-temperature and high-humidity tank at 85 ° C. and a relative humidity of 85% RH, and those having an insulation resistance value (IR value) of Log IR <7, The IR or moisture resistance was judged to have deteriorated. The number of samples was 20, and the deterioration rate of IR was investigated.

  The above measurement results are shown in Table 1.

  From the results shown in Table 1, blisters are generated in Comparative Example 1. The reason for this is that in Comparative Example 1, the cross-sectional shape of the external electrode has a single crest shape, so that carbon dioxide generated by combining with oxygen after the resin or solvent in the conductive paste constituting the external electrode is carbonized. This is because the gas cannot be sufficiently discharged out of the external electrode, causing a blister.

  Further, in Comparative Example 2, IR deterioration occurs. The reason for this is that, in Comparative Example 2, the thickness dimension DT of the regular quadrangular prism-shaped ceramic body is the same as the width dimension DW, so that the main surface side of the ceramic body is also the lead-out surface side of the internal electrode on the end surface of the ceramic body. Similarly, the cross-sectional shape of the external electrode has two peaks. As described above, if the cross-sectional shape of the external electrode is also formed in two peaks on the end face side of the ceramic body, the thickness of the external electrode is reduced at the center of the external electrode. This is because sealing cannot be performed, and the plating solution or moisture in the air easily enters the internal electrode side from the portion.

On the other hand, in Examples 1 to 3 according to the present invention, it is possible to suppress the generation of blisters while maintaining IR or moisture resistance reliability.
It should be noted that the chip size is DL × DW × DT = 0.6 mm × 0.3 mm × 0.15 mm, and the dimension of the external electrode folded (the length of the external electrode formed on the main surface and side surface of the ceramic body) A similar experiment was performed on a sample within the range of the present invention in which (electrode part dimension DE) was 180 μm to 320 μm (target value was 250 μm), but similar effects could be obtained.

In the above-described embodiments and examples, the dielectric ceramic is used as the material of the ceramic body. However, in the present invention, depending on the type of the ceramic electronic component, the material of the ceramic body may be a piezoelectric ceramic such as a PZT-based ceramic, Semiconductor ceramics such as spinel ceramics and magnetic ceramics such as ferrite can also be used.
As a ceramic body of a ceramic electronic component, when a piezoelectric ceramic is used, it functions as a piezoelectric component, when a semiconductor ceramic is used, it functions as a thermistor, and when a magnetic ceramic is used, it functions as an inductor. However, when functioning as an inductor, the internal electrode becomes a coiled conductor.

  In the above-described embodiments and examples, the external electrode is also formed on the side surface of the ceramic body. However, the external electrode may not be formed on the side surface of the ceramic body.

  Furthermore, in the above-described embodiment and examples, one recess is formed in the center of the external electrode on each of the pair of main surfaces of the ceramic body. The recess is an end of the external electrode. It may be formed in an intermediate part other than the above, and two or more hollow parts may be formed. In this case, the cross-sectional shape of the external electrode may have three or more mountain shapes.

  The ceramic electronic component according to the present invention is particularly preferably used as, for example, a multilayer ceramic capacitor or a multilayer ceramic inductor.

DESCRIPTION OF SYMBOLS 10 Multilayer ceramic capacitor 12 Ceramic main body 12a, 12b Main surface 12c, 12d Side surface 12e, 12f End surface 14 Ceramic layer 16a, 16b Internal electrode 18a, 18b Exposed part 20a, 20b External electrode 22a1, 22a2, 22b1, 22b2 Recessed part 24a, 24b Plating film 26a1, 26a2, 26b1, 26b2 Recessed part

Claims (3)

A ceramic body having a pair of main surfaces facing each other, a pair of side surfaces facing each other, and a pair of end surfaces facing each other;
An internal electrode disposed inside the ceramic body and having an exposed portion exposed at the end face of the ceramic body;
A pair of external electrodes formed so as to be electrically connected to the exposed portions of the internal electrodes and extending from at least the pair of main surfaces from the end surfaces on the pair of end surfaces of the ceramic body;
A ceramic electronic component having a plating film formed on the external electrode,
The length in the direction connecting the pair of main surfaces of the ceramic body is the length of the external electrode formed on the main surface of the ceramic body, and connects the pair of end surfaces of the ceramic body. Formed shorter than the length in the
The external electrode formed on the main surface of the ceramic body has a recess in the central portion, and the external electrode formed on the end surface of the ceramic body has no recess. Ceramic electronic components.   2. The ceramic electronic component according to claim 1, wherein in the external electrode formed on the main surface of the ceramic body, a thickness of a recessed portion with respect to a thickest portion is 12% or more.   The cross-sectional shape of the external electrode formed on the main surface of the ceramic body is recessed at the center of the external electrode and has two ridges. The ceramic electronic component according to claim 2.

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