Multilayer ceramic electronic component

Abstract

To provide a multilayer ceramic electronic component that suppresses the occurrence of thermal cracks while maintaining good temperature characteristics.SOLUTION: A multilayer ceramic electronic component having laminated dielectric layers and internal electrode layers. The internal electrode layer that is outermost in the stacking direction among the internal electrode layers is designated as the first internal electrode layer, and the dielectric layer that is outside the first internal electrode layer in the stacking direction among the dielectric layers is designated as the exterior dielectric layer, and the exterior dielectric layer has a concentration gradient in which the Mn concentration increases from the vicinity of the first internal electrode layer toward the outside in the stacking direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a multilayer ceramic electronic component. [Background technology]

[0002] Patent Document 1 describes an invention related to a multilayer ceramic capacitor. Specifically, it describes that the penetration of moisture into the ceramic laminate can be suppressed or prevented by forming a boundary layer containing Mg and Mn at the boundary between the outermost internal electrode and the outermost dielectric ceramic layer located outside it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-232896 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a multilayer ceramic electronic component that suppresses the occurrence of thermal cracks while maintaining good temperature characteristics. [Means for solving the problem]

[0005] In order to achieve the above object, a multilayer ceramic electronic component according to the present invention comprises: A multilayer ceramic electronic component having laminated dielectric layers and internal electrode layers, Among the internal electrode layers, the internal electrode layer located outermost in the stacking direction is defined as a first internal electrode layer, Among the dielectric layers, a dielectric layer located outside the first internal electrode layer along the lamination direction is an exterior dielectric layer, The laminated ceramic electronic component has a concentration gradient in the exterior dielectric layers, where the Mn concentration increases from the vicinity of the first internal electrode layers toward the outside along the lamination direction.

[0006] The thickness of the outer dielectric layer may be 150 μm or more and 500 μm or less.

[0007] The concentration gradient may be present in a portion of the outer dielectric layer where the distance from the first internal electrode layer is 100 μm or less.

[0008] In the outer dielectric layer, the Mn concentration in a portion where the distance from the first internal electrode layer is 1 μm or more and 50 μm or less may be 80% or more and 90% or less, and the Mn concentration in a portion where the distance from the first internal electrode layer is 50 μm or more and 100 μm or less may be 90% or more and 100% or less, as compared with the Mn concentration in a portion where the distance from the first internal electrode layer is 100 μm or more.

[0009] The Mn concentration in the first internal electrode layer may be higher than the Mn concentration in other internal electrode layers.

[0010] Among the internal electrode layers, an internal electrode layer that is inside the first internal electrode layer and has a gap corresponding portion is defined as the second internal electrode layer. An internal electrode layer that is inside the second internal electrode layer and does not have a gap corresponding portion is defined as the third internal electrode layer. Let the Mn concentration in the first internal electrode layer be C1, the Mn concentration in the gap corresponding portion of the second internal electrode layer be C2A, and the Mn concentration in the third internal electrode layer be C3. C3 < C2A < C1 may be satisfied.

[0011] A multilayer ceramic electronic component in which C1 / C3 may be 2.5 or more and 4.0 or less.

[0012] Let the Mn concentration in a portion other than the gap corresponding portion of the second internal electrode layer be C2B, and C2A / C2B may be 1.5 or more and 3.0 or less.

[0013] C1 / C2A may be 1.2 or more and 2.0 or less.

[0014] Among the dielectric layers, a dielectric layer located inside the first internal electrode layer along the stacking direction may be referred to as an internal dielectric layer, and the thickness of the internal dielectric layer may be 3.0 μm or more and 15 μm or less.

[0015] The number of laminations of the internal electrode layers may be 50 or more and 300 or less.

[0016] The dielectric layer may contain Ca, Sr, Zr, Ti and O. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing a cross section of a multilayer ceramic capacitor according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing a cross section of a multilayer ceramic capacitor according to one embodiment of the present invention. [Figure 3] FIG. 3 is a schematic diagram showing a cross section of a multilayer ceramic capacitor according to one embodiment of the present invention. [Figure 4] FIG. 4 is a graph showing the relationship between the distance from the first internal electrode layer and the intensity of characteristic X-rays of Mn. [Figure 5] FIG. 5 is a graph showing the relationship between the distance from the first internal electrode layer and the intensity of characteristic X-rays of Mn. [Figure 6] FIG. 6 is a schematic diagram showing a part of a cross section of a multilayer ceramic capacitor according to one embodiment of the present invention. [Figure 7] FIG. 7 is a schematic diagram showing a part of a cross section of a multilayer ceramic capacitor according to one embodiment of the present invention. [Figure 8] FIG. 8 is a schematic diagram showing a part of a cross section of a multilayer ceramic capacitor according to one embodiment of the present invention. [Figure 9] FIG. 9 is a schematic diagram showing an example of the arrangement of the dielectric layer sheets. [Figure 10] FIG. 10 is a schematic diagram showing an example of the arrangement of the dielectric layer sheets. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described below based on specific embodiments.

[0019] A multilayer ceramic capacitor 1 as an example of a multilayer ceramic electronic component according to this embodiment is shown in Fig. 1. The multilayer ceramic capacitor 1 has an element body 10 configured by alternately stacking dielectric layers 2 and internal electrode layers 3. A pair of external electrodes 4 is formed on both ends of the element body 10.

[0020] A pair of internal electrode layers 3 electrically connected to different external electrodes 4 shown in FIG. 1 and an internal electrode layer 3 not electrically connected to any of the external electrodes 4 shown in FIG. 1 are alternately arranged in the stacking direction (the vertical direction in FIG. 1) within the element body 10.

[0021] There are no particular limitations on the shape of the element body 10, but it is usually a rectangular parallelepiped. There are also no particular limitations on the dimensions of the element body 10, and it may be of any appropriate size depending on the application.

[0022] The composition of the dielectric layer 2 is not particularly limited. For example, the dielectric layer 2 may be made of a dielectric ceramic composition. The composition of the dielectric layer 2 is not particularly limited. For example, the dielectric layer 2 may mainly contain Ca, Sr, Zr, Ti, and O, or may be a perovskite compound containing Ca and Sr as A-site elements and Zr and Ti as B-site elements. A perovskite compound is a compound having a perovskite-type crystal structure represented by the general formula ABO3 (A is an A-site element, B is a B-site element). When the dielectric layer 2 mainly contains Ca, Sr, Zr, Ti, and O, the effect of suppressing the occurrence of thermal cracks while maintaining favorable temperature characteristics can be enhanced by the technical techniques described below.

[0023] The dielectric layer 2 mainly containing Ca, Sr, Zr, Ti and O means that the total content of Ca, Sr, Zr, Ti and O in the dielectric layer 2 is 90 at % or more.

[0024] When the dielectric layer 2 contains a perovskite compound containing Ca and Sr as A-site elements and Zr and Ti as B-site elements, the total content of Ca and Sr relative to all A-site elements of the perovskite compound may be 50 at% or more, and the total content of Zr and Ti relative to all B-site elements of the perovskite compound may be 90 at% or more.

[0025] If the total content of Ca and Sr relative to all A-site elements in the perovskite compound is less than 50 at%, particularly if the compound contains a large amount of Ba as an A-site element, the effect of suppressing the occurrence of thermal cracks while maintaining favorable temperature characteristics using the technical techniques described below is likely to be reduced.

[0026] In addition to the perovskite compound, the dielectric layer 2 may contain, for example, SiO2 and / or Al2O3. Specifically, the dielectric layer 2 may contain 0 to 4.0 molar parts of Si and 0 to 2.0 molar parts of Al relative to 100 molar parts of the B-site elements of the perovskite compound.

[0027] Among the dielectric layers 2, the dielectric layer located outside the stacking direction from the first internal electrode layer 3a described later is referred to as the exterior dielectric layer 2a, and the dielectric layer located inside the stacking direction from the first internal electrode layer 3a described later is referred to as the internal dielectric layer 2b.

[0028] The exterior dielectric layer 2a contains Mn. A concentration gradient exists in the exterior dielectric layer 2, where the Mn concentration increases from the vicinity of the first internal electrode layer 3a toward the outside along the stacking direction. The existence of this concentration gradient makes it possible to suppress the occurrence of thermal cracks while maintaining good temperature characteristics.

[0029] There are no particular limitations on where in the exterior dielectric layer 2a the concentration gradient exists. For example, the concentration gradient may exist in a portion that is 100 μm or less away from the first internal electrode layer 2a.

[0030] More specifically, the above-mentioned concentration gradient may be considered to exist when the average Mn concentration in a portion that is 1 um or more and 50 um or less away from the first internal electrode layer 3a is lower than the average Mn concentration in a portion that is 50 um or more and 100 um or less away from the first internal electrode layer 3a.

[0031] In the exterior dielectric layer 2a, the average Mn concentration in a portion that is 1 um or more and 50 um or less away from the first internal electrode layer 3a may be 50% or more and 90% or less compared to the average Mn concentration in a portion that is 100 um or more away from the first internal electrode layer 3a, and the average Mn concentration in a portion that is 50 um or more and 100 um or less away from the first internal electrode layer 3a may be 80% or more and 110% or less.

[0032] In the exterior dielectric layer 2a, compared to the average Mn concentration in a portion that is 100 μm or more away from the first internal electrode layer 3a, the average Mn concentration in a portion that is 1 μm or more and 50 μm or less away from the first internal electrode layer 3a may be 80% or more and 90% or less, and the average Mn concentration in a portion that is 50 μm or more and 100 μm or less away from the first internal electrode layer 3a may be 90% or more and 100% or less.

[0033] When the Mn concentration distribution is within the above range, the occurrence of thermal cracks, particularly at the interface between the exterior dielectric layer 2a and the first internal electrode layer 3a and the interface between the exterior dielectric layer 2a and the external electrode 4, is easily suppressed.

[0034] The presence or absence of the concentration gradient and the distribution of the Mn concentration can be confirmed by measuring the intensity of the characteristic X-rays of Mn using SEM-EDS or STEM-EDS.

[0035] The intensity of the characteristic X-rays of Mn is proportional to the Mn concentration. Therefore, when the intensity of the characteristic X-rays of Mn is analyzed by line analysis along the stacking direction from the first internal electrode layer 3a to the exterior dielectric layer 2a, if there is a point where the intensity of the characteristic X-rays of Mn increases with increasing distance from the first internal electrode layer 3a, it can be said that the above concentration gradient exists.

[0036] In the above line analysis, the intervals between measurement points of characteristic X-rays should be sufficiently short, specifically, 2 μm or less.

[0037] In addition, the above concentration gradient may be considered to exist when the average intensity of the characteristic X-rays of Mn in a portion that is 1 um or more and 50 um or less away from the first internal electrode layer 3a is lower than the average intensity of the characteristic X-rays of Mn in a portion that is 50 um or more and 100 um or less away from the first internal electrode layer 3a.

[0038] Furthermore, the average intensity of the characteristic X-rays of Mn in the portions that are 1 um or more and 50 um or less from the first internal electrode layer 3a may be 80% or more and 90% or less, and the average intensity of the characteristic X-rays of Mn in the portions that are 50 um or more and 100 um or less from the first internal electrode layer 3a may be 90% or more and 100% or less, compared to the average intensity of the characteristic X-rays of Mn in the portions that are 100 um or more from the first internal electrode layer 3a. In this case, the Mn concentration in the portions that are 1 um or more and 50 um or less from the first internal electrode layer 3a is 80% or more and 90% or less, and the Mn concentration in the portions that are 50 um or more and 100 um or less from the first internal electrode layer 3a is 90% or more and 100% or less, compared to the average Mn concentration in the portions that are 100 um or more from the first internal electrode layer 3a.

[0039] When calculating the average intensity of the characteristic X-rays of Mn in the portion that is 100 μm or more away from the first internal electrode layer 3a, if the thickness of the exterior dielectric layer 2a is less than 200 μm, the average intensity of the characteristic X-rays of Mn is calculated for the entire portion that is 100 μm or more away from the first internal electrode layer 3a.

[0040] Furthermore, when the thickness of the exterior dielectric layer 2a is 200 μm or more, the average intensity of the characteristic X-rays of Mn in a portion that is 100 μm or more and 200 μm or less away from the first internal electrode layer 3a may be regarded as the average intensity of the characteristic X-rays of Mn in a portion that is 100 μm or more away from the first internal electrode layer 3a.

[0041] Graphs obtained by plotting the distance from the first internal electrode layer 3a on the horizontal axis and the intensity of the characteristic X-rays of Mn on the vertical axis are shown in Figures 4 and 5. Figure 4 shows a case where the average intensity of the characteristic X-rays of Mn in a portion at a distance of 1 um or more and 50 um or less from the first internal electrode layer 3a is lower than the average intensity of the characteristic X-rays of Mn in a portion at a distance of 50 um or more and 100 um or less from the first internal electrode layer 3a. Figure 5 shows a case where the average intensity of the characteristic X-rays of Mn in a portion at a distance of 1 um or more and 50 um or less from the first internal electrode layer 3a is the same as the average intensity of the characteristic X-rays of Mn in a portion at a distance of 50 um or more and 100 um or less from the first internal electrode layer 3a.

[0042] The presence of the above-mentioned concentration gradient in the exterior dielectric layer 2a is thought to be able to suppress the occurrence of thermal cracks because the presence of the above-mentioned concentration gradient suppresses sintering of the exterior dielectric layer 2a, thereby reducing the shrinkage rate of the exterior dielectric layer 2a due to sintering.

[0043] If there is a concentration gradient in which the Mn concentration decreases from the vicinity of the first internal electrode layer 3a toward the outside along the stacking direction, thermal cracks are more likely to occur.

[0044] The thickness of the exterior dielectric layer 2a is not particularly limited and can be set arbitrarily depending on the desired properties, application, etc. For example, it may be more than 50 μm and not more than 800 μm, or may be 150 μm or more and 500 μm or less. The thicker the exterior dielectric layer 2a, the more likely thermal cracks will occur. Conversely, the thinner the exterior dielectric layer 2a, the less likely the likelihood of thermal cracks occurring will depend on the presence or absence of the concentration gradient.

[0045] The thickness of each inner dielectric layer 2b (interlayer thickness) is not particularly limited and can be set arbitrarily depending on the desired characteristics, application, etc. For example, it may be 1.0 μm or more and 20 μm or less, or 3.0 μm or more and 15 μm or less. The thicker the inner dielectric layer 2b, the less the likelihood of thermal cracking depends on the presence or absence of the concentration gradient. The thinner the inner dielectric layer 2b, the more likely thermal cracking occurs.

[0046] The internal electrode layers 3 are laminated so that their end faces are exposed on the surfaces of two opposing end portions of the element body 10 .

[0047] The internal electrode layer 3 that is outermost in the stacking direction is referred to as the first internal electrode layer 3a. The internal electrode layer that is located more inward than the first internal electrode layer 3a and has a gap corresponding portion (described later) is referred to as the second internal electrode layer. The internal electrode layer that is located more inward than the second internal electrode layer and does not have a gap corresponding portion (described later) is referred to as the third internal electrode layer 3c.

[0048] The gap corresponding portion is a portion of the internal electrode layer 3 other than the first internal electrode layer 3a, on the outside of which no other internal electrode layer exists along the stacking direction.

[0049] The gap corresponding portion is defined as a portion having a length of 10 μm or more in the thickness direction (left-right direction in FIG. 1) of the external electrode 4. In other words, even if there is no other internal electrode layer on the outside in the stacking direction, a portion having a length of less than 10 μm in the thickness direction of the external electrode 4 is not considered to be a gap corresponding portion.

[0050] As shown in FIG. 1, the second internal electrode layer is made up of a gap corresponding portion 3b1 of the second internal electrode layer and a portion 3b2 of the second internal electrode layer other than the gap corresponding portion.

[0051] There is no particular limitation on the ratio of the length of the gap corresponding portion 3b1 to the length of the second internal electrode layer (the total length of the gap corresponding portion 3b1 and the portion other than the gap corresponding portion 3b2) in the left-right direction of Fig. 1. For example, it may be 2.5% or more and 20% or less.

[0052] The main component of the conductive material contained in the internal electrode layer 3 is a metal. The metal is not particularly limited, and for example, known conductive materials such as Pd, Pd-based alloys, Pt, Pt-based alloys, Ni, Ni-based alloys, Cu, Cu-based alloys, etc. may be used.

[0053] Some internal electrode layers 3 such as the first internal electrode layer 3a may contain Mn, and the Mn concentration in the first internal electrode layer 3a may be higher than the Mn concentration in other internal electrode layers.

[0054] Due to the high Mn concentration in the first internal electrode layer 3a, the linear expansion coefficient in the first internal electrode layer 3a tends to be small. And the difference in the linear expansion coefficient between the exterior dielectric layer 2a and the first internal electrode layer 3a tends to be small. Therefore, it is considered that thermal cracks are less likely to occur.

[0055] Also, compared with the case of uniformly increasing the Mn concentration in all internal electrode layers, the temperature characteristics of the multilayer ceramic capacitor 1 are more likely to be improved when the Mn concentration in the first internal electrode layer is relatively increased.

[0056] When the Mn concentration in all internal electrode layers is uniformly low, thermal cracks are likely to occur, and when the Mn concentration in all internal electrode layers is uniformly high, it is difficult to maintain good temperature characteristics.

[0057] There is no particular limitation on the Mn concentration in the first internal electrode layer 3a. For example, it may be 0.1 wt% or more and 3.0 wt% or less.

[0058] Let the Mn concentration in the first internal electrode layer 3a be C1, the Mn concentration in the gap corresponding portion 3b1 of the second internal electrode layer be C2A, the Mn concentration in the portion 3b2 other than the gap corresponding portion of the second internal electrode layer be C2B, and the Mn concentration in the third internal electrode layer 3c be C3. It may satisfy C3 < C2A < C1.

[0059] Furthermore, C1 / C3 may be 2.5 or more and 4.0 or less. C2A / C2B may be 1.5 or more and 3.0 or less. C1 / C2A may be 1.2 or more and 2.0 or less. There is no particular restriction on C2B / C3, but C2B / C3 may be 0.9 or more and 1.1 or less, or even 1.0. There is also no particular restriction on C2A / C3, but C2A / C3 may be 1.1 or more and less than 4.0.

[0060] When the Mn concentration in each internal electrode layer satisfies the above relationship, thermal cracks are less likely to occur and good temperature characteristics are more likely to be maintained. Note that when C1 / C3, C2A / C2B, and / or C1 / C2A are large, the temperature characteristics tend to be more likely to deteriorate.

[0061] 6 to 8 are schematic diagrams each showing a part of Fig. 1. As shown in Fig. 6 to 8, each internal electrode layer may contain Mn segregation 11 where the Mn concentration is higher than the surrounding area.

[0062] The presence of Mn segregation 11 in each internal electrode layer can be confirmed by creating an Mn element mapping image of a cross section of the multilayer ceramic capacitor 1 using SEM-EDS, STEM-EDS, or the like.

[0063] 6 is a schematic diagram of the first internal electrode layer 3a, the portion 3b2 of the second internal electrode layer other than the gap corresponding portion, and the portion including the third internal electrode layer 3c. It can be seen that the first internal electrode layer 3a contains a large amount of Mn segregation 11. It can also be seen that the content ratio of Mn segregation 11 is substantially equal between the portion 3b2 of the second internal electrode layer other than the gap corresponding portion and the third internal electrode layer 3c.

[0064] 7 is a schematic diagram of a portion including the gap corresponding portion 3b1 of the second internal electrode layer and the third internal electrode layer 3c. It can be seen that the Mn segregation 11 is contained in large amounts in the gap corresponding portion 3b1 of the second internal electrode layer.

[0065] As shown in FIGS. 6 and 7, it can be seen that the content ratio of Mn segregation 11 is higher in the first internal electrode layer 3a than in the gap corresponding part of the second internal electrode layer.

[0066] FIG. 8 is a schematic view of a portion including a large number of third internal electrode layers 3c. It can be seen that the content ratio of Mn segregation 11 is substantially equal among the third internal electrode layers 3c.

[0067] There is no particular limitation on the measurement methods of C1, C2A, C2B, and C3. For example, a method of measuring the intensity of characteristic X-rays of Mn using SEM-EDS or STEM-EDS can be mentioned.

[0068] The intensity of characteristic X-rays of Mn is proportional to the Mn concentration. Therefore, within each internal electrode layer, by performing line analysis and averaging the intensity of characteristic X-rays of Mn along the thickness direction (left-right direction in FIG. 1) of the external electrode 4, it can be confirmed that C3 < C2A < C1 is satisfied. Furthermore, C1 / C3, C2A / C2B, and C1 / C2A can be calculated.

[0069] The interval between the measurement positions of characteristic X-rays in the above line analysis is made sufficiently short. Specifically, it is set to 2 μm or less. Also, in order to confirm C1, C2A, C2B, and C3, line analysis is performed with a length of at least 30 μm or more.

[0070] In addition, the internal electrode layer 3 may contain various trace components such as P at about 0.1 mass% or less. The internal electrode layer 3 may be formed using a commercially available electrode paste. The thickness of the internal electrode layer 3 may be appropriately determined according to the application and the like.

[0071] There is no particular limitation on the number of stacked internal electrode layers 3. It may be 40 or more and 400 or less, or may be 50 or more and 300 or less. The more the number of stacked internal electrode layers 3, the more likely it is to generate thermal cracks. The fewer the number of stacked internal electrode layers 3, the less likely the occurrence of thermal cracks depends on the presence or absence of the above concentration gradient.

[0072] There are no particular restrictions on the conductive material contained in the external electrodes 4. For example, known conductive materials such as Ni, Cu, Sn, Ag, Pd, Pt, Au, alloys of these, conductive resins, etc. may be used. The thickness of the external electrodes 4 may be determined appropriately depending on the application, etc.

[0073] Next, an example of a method for manufacturing the multilayer ceramic capacitor 1 shown in FIG. 1 will be described.

[0074] First, a description will be given of the manufacturing process of the element body 10. In the manufacturing process of the element body 10, a dielectric paste that becomes the dielectric layer 2 after firing and an internal electrode paste that becomes the internal electrode layer 12 after firing are prepared.

[0075] The dielectric paste is manufactured, for example, by the following method. First, the dielectric raw materials are uniformly mixed by means of wet mixing or the like, and then dried. The dielectric raw materials may be oxides of metal elements, or may be compounds (e.g., carbonates) that become oxides of metal elements upon heat treatment. Then, calcined powder is obtained by heat treatment under specified conditions. Next, a known organic vehicle or a known aqueous vehicle is added to the calcined powder obtained and kneaded to prepare a dielectric paste. The dielectric paste may contain additives selected from various dispersants, plasticizers, dielectrics, secondary component compounds, glass frit, etc., as needed.

[0076] Here, in order to form a gradient of Mn concentration in the exterior dielectric layer 2a and, if necessary, to form Mn segregation in each internal electrode layer, multiple types of dielectric layer pastes with different Mn contents are prepared. Specifically, the Mn content is adjusted by controlling the amount of Mn oxide powder or powder of a compound that becomes Mn oxide by heat treatment.

[0077] On the other hand, the internal electrode paste is prepared by kneading conductive powder made of a conductive metal or its alloy (preferably Ni powder or Ni alloy powder). If necessary, in order to form Mn segregation in each internal electrode layer, Mn oxide powder or powder of a compound that becomes Mn oxide by heat treatment may be added as appropriate. Furthermore, multiple types of internal electrode layer pastes with different Mn contents may be prepared.

[0078] The internal electrode paste may contain ceramic powder as a co-material, if necessary, which has the effect of suppressing sintering of the conductive powder during the firing process.

[0079] Next, the dielectric paste is formed into a sheet by a method such as a doctor blade method to obtain a green sheet.

[0080] In the following description, a large amount of Mn-added sheet 21, an appropriate amount of Mn-added sheet 22, and a non-Mn-added sheet 23 are prepared using a plurality of types of dielectric layer paste and used as green sheets.

[0081] Then, the internal electrode paste is applied in a predetermined pattern onto each green sheet by various printing methods such as screen printing or transfer methods to form the internal electrode pattern 31. After the green sheets on which the internal electrode pattern 31 has been formed are stacked in multiple layers, they are pressed in the stacking direction to obtain a green chip.

[0082] At this time, the green sheets are laminated as shown in Fig. 9. Specifically, the large amount of Mn-added sheet 21 is arranged so as to be in contact with the internal electrode pattern 31 that will eventually become the first internal electrode layer 3a. Then, the appropriate amount of Mn-added sheet 22 is arranged in the portion that will finally become the internal dielectric layer 2b. Then, the appropriate amount of Mn-added sheet 22 and the Mn-free sheet 23 are appropriately arranged outside the large amount of Mn-added sheet 21.

[0083] 9, more Mn-free sheets 23 are placed in the areas closer to the internal electrode patterns 31. In this way, the above-mentioned Mn concentration gradient can be formed in the exterior dielectric layer 2a.

[0084] Furthermore, by placing the heavily Mn-added sheet 21 on the internal electrode pattern that will ultimately become the first internal electrode layer 3a, much of the Mn contained in the heavily Mn-added sheet diffuses into the dielectric. This causes Mn to be incorporated into the internal electrode, resulting in Mn segregation. As a result, a state can be created in which C1 is high, C2a is second highest, and C2b and C3 are low.

[0085] On the other hand, when a green chip is produced without using the Mn-free sheet 23 as shown in FIG. 10, the above-mentioned Mn concentration gradient is difficult to form in the exterior dielectric layer 2a.

[0086] The obtained green chip may be subjected to a binder removal process as needed. The binder removal process conditions may be well-known conditions, such as a holding temperature of 200°C or higher and 900°C or lower, and a holding time of 1 hour or higher and 48 hours or lower. There are also no particular limitations on the atmosphere during binder removal.

[0087] After the binder removal process, the green chip is fired to obtain the element body 10. In this embodiment, the firing atmosphere is an oxygen partial pressure of 2.0×10 -13 atm or more 1.0×10 -7 Other firing conditions may be well known, for example, the holding temperature may be 1100°C or higher and 1350°C or lower, and the holding time may be 0.5 hours or higher and 5 hours or lower.

[0088] After firing, an annealing treatment may be carried out as necessary. There are no particular restrictions on the conditions for the annealing treatment. For example, the holding temperature may be 500°C or higher and 1150°C or lower, and the holding time may be 0.5 hours or higher and 20 hours or lower. The oxygen partial pressure in the annealing atmosphere may be, for example, 1.0 x 10 -9 atm or more 3.0×10-5 atm or less.

[0089] The element body 10 obtained as described above is subjected to end polishing as necessary, and an external electrode paste is applied and baked to form the external electrodes 4. Then, as necessary, a coating layer is formed on the surface of the external electrodes 4 by plating or the like. There are no particular limitations on the method for preparing the external electrode paste, and it may be prepared by the same method as the internal electrode paste.

[0090] In this manner, the multilayer ceramic capacitor 1 according to this embodiment is manufactured.

[0091] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the present invention.

[0092] For example, as in a multilayer ceramic capacitor 1a shown in Fig. 2, a pair of external electrodes 4 may be formed on both ends of the element body 10, and each of the external electrodes 4 may be electrically connected to the internal electrode layers 3 arranged alternately inside the element body 10. Alternatively, as in a multilayer ceramic capacitor 1b shown in Fig. 3, the first internal electrode layer 3a may not be electrically connected to the external electrode 4.

[0093] In this embodiment, a multilayer ceramic capacitor 1, which is one type of multilayer ceramic electronic component, has been illustrated as an example, but the multilayer ceramic electronic component of the present invention is not limited to a multilayer ceramic capacitor. [Example]

[0094] The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

[0095] In this example, the multilayer ceramic capacitor 1 shown in FIG. 1 was fabricated in the following manner.

[0096] First, three types of dielectric pastes with different Mn contents were prepared, each prepared using a common method for producing the dielectric layer paste.

[0097] A raw material powder of a perovskite compound contained as the main component of the main phase particles (hereinafter, sometimes referred to as the main component raw material powder) was prepared. Specifically, the composition formula was (Ca 0.70 Sr 0.30 )(Zr 0.96 Ti 0.04 To obtain a perovskite compound (abbreviated as CSZT in Table 1) of γ-O3, raw powders of Ca oxide, Sr oxide, Zr oxide, and Ti oxide were prepared and weighed. Note that "γ-oxide raw powder" refers to γ-oxide powder and / or powder of a compound that will become γ-oxide powder upon heat treatment. Each powder was then dispersed in pure water, dried, and further heat-treated (holding temperature 1200-1250°C, holding time 0.5-5 hours) to obtain a perovskite compound with a specific surface area of ​​5.0 m as measured by the BET method. 2 The holding temperature and holding time during the heat treatment were set appropriately for each sample.

[0098] Separately, MnCO3 powder, SiO2 powder, and Al2O3 powder were prepared. They were weighed out so that the Si content was greater than the Al content on an atomic number basis. Furthermore, MnCO3 powder was prepared and weighed out so that the Mn content of the dielectric layer paste used to prepare the large-amount Mn-added sheet was 4.0 to 10.0 molar parts, and the Mn content of the dielectric layer paste used to prepare the appropriate-amount Mn-added sheet was 1.5 to 3.0 molar parts. Furthermore, the Mn content of the large-amount Mn-added sheet and the appropriate-amount Mn-added sheet was weighed out so that the Mn content was greater than the Si content on an atomic number basis.

[0099] The main component raw material powder and the powder of the oxide of the additive element were dispersed in pure water, dried, and then heat-treated to obtain the dielectric powder. The holding temperature was 400°C, and the holding time was 0.5 to 5 hours. The holding time during the heat treatment was set appropriately depending on each sample.

[0100] Each dielectric paste was prepared by mixing the dielectric powder with an organic vehicle. 100 parts by mass of the dielectric powder were mixed with 10 parts by mass of polyvinyl butyral resin, 5 parts by mass of dioctyl phthalate (DOP) as a plasticizer, and 100 parts by mass of alcohol as a solvent in a ball mill to form a paste, thereby obtaining a dielectric layer paste.

[0101] The method for preparing the internal electrode paste is as follows: First, Ni powder, terpineol, ethyl cellulose, and benzotriazole were prepared in a mass ratio of 44.6:52.0:3.0:0.4. These were then kneaded using a three-roll mill to form a paste, thereby preparing the internal electrode paste.

[0102] Next, green chips were manufactured by the sheet method using the above-mentioned dielectric pastes and internal electrode pastes. When forming a Mn concentration gradient in the exterior dielectric layers, the dielectric layer sheets were arranged as shown in Figure 9. When not forming a Mn concentration gradient in the exterior dielectric layers, all of the Mn-free sheets in Figure 9 were replaced with sheets containing an appropriate amount of Mn, as shown in Figure 10.

[0103] The green chip was then subjected to binder removal, firing, and annealing to obtain a rectangular parallelepiped element body 10 with dimensions of 3.2 mm x 2.5 mm on the surface perpendicular to the stacking direction. The dimensions are 3.2 mm in the horizontal direction in Figure 1. The length in the stacking direction varies depending on the number of internal dielectric layers, the average thickness of the internal dielectric layers, and the thickness of the exterior dielectric layers, as described below. The holding temperature during the firing process was 1200°C, the holding time was 2.0 hours, and the firing atmosphere was an oxygen partial pressure of 2.0 x 10 -13 atm or more 1.0×10 -7 The reducing atmosphere was at or below 1 atm. In the obtained element body 10, the number of stacked internal dielectric layers, the average thickness of the internal dielectric layers, and the thickness of the exterior dielectric layer were set to the values ​​shown in each table.

[0104] Next, a baked electrode layer containing Cu, a Ni plated layer, and a Sn plated layer were formed on the outer surface of the element body 10 in the order described above to form the external electrodes 4, and the multilayer ceramic capacitor 1 was obtained.

[0105] (Composition of dielectric ceramic composition) Regarding the composition of the dielectric ceramic composition, the composition of the internal dielectric layer was analyzed using ICP atomic emission spectroscopy, and it was confirmed that the composition of the perovskite compound contained in the internal dielectric layer was the above-mentioned composition, and that the content of the additive elements was the same as that of the dielectric layer paste used to prepare the Mn-appropriately added sheet.

[0106] (Mn concentration gradient) To check for the presence or absence of a Mn concentration gradient, the intensity of Mn characteristic X-rays was measured by performing line analysis using STEM-EDS on a cross section in the direction shown in Figure 1, i.e., a cross section parallel to the stacking direction and parallel to the thickness direction of the external electrodes, over a length of 200 μm from the first internal electrode layer outward along the stacking direction. The average intensity from 1 μm to 50 μm, the average intensity from 50 μm to 100 μm, and the average intensity from 100 μm to 200 μm were measured. Since the intensity of Mn characteristic X-rays and Mn concentration are proportional, the ratio of the average concentrations was calculated. The presence or absence of a Mn concentration gradient was also confirmed. The results are shown in the tables.

[0107] (Mn concentration in the internal electrode layer, presence or absence of Mn segregation) To determine the Mn concentration in the internal electrode layers, line analysis was performed on the inside of each internal electrode layer along a direction perpendicular to the lamination direction in the cross section shown in Figure 1, and the intensity of Mn characteristic X-rays was measured. The average intensity in the first internal electrode layer, the average intensity in the gap-corresponding portion of the second internal electrode layer, the average intensity in the portion other than the gap-corresponding portion of the second internal electrode layer, and the average intensity in the third internal electrode layer were measured. Since the Mn characteristic X-ray intensity and Mn concentration are proportional, C1 / C3, C2A / C2B, and C1 / C2A were calculated. Furthermore, a Mn mapping image including the internal dielectric layer was created using STEM-EDS, and the Mn segregation content was confirmed by observing the Mn mapping image. Regarding the Mn segregation content, Table 1 shows whether the Mn segregation content in the first internal electrode layer was higher or equal to the Mn segregation content in the third internal electrode layer.

[0108] (Thermal crack test) Sixty multilayer ceramic capacitors for each sample number were immersed in a solder bath at 400°C for three seconds and then removed. Each multilayer ceramic capacitor was then examined using an optical microscope at 10x magnification to determine whether or not thermal cracks had occurred, and the percentage of multilayer ceramic capacitors with thermal cracks was evaluated. The results are shown in the tables. A thermal crack occurrence rate of 10 / 60 or less was rated as good, 5 / 60 or less was rated as even better, and less than 1 / 60, i.e., 0 / 60 in this example, was rated as best.

[0109] (Temperature characteristics) The temperature characteristics of the multilayer ceramic capacitor 1 were evaluated by measuring the capacitance temperature coefficient τC (unit: ppm / °C). Specifically, a signal with a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms was input to the multilayer ceramic capacitor at 25°C and 125°C, and the capacitance was measured at each temperature range. The capacitance temperature coefficient τC was then calculated from the capacitance C25 at 25°C and the capacitance C125 at 125°C using the following formula. τC={(C125-C25) / C25}×{1 / (125-25)}

[0110] The capacitance temperature coefficient τC was measured for 10 multilayer ceramic capacitors 1 for each sample number and averaged. Temperature characteristics were rated as good when the average value of the capacitance temperature coefficient τC was between -15 ppm / °C and +15 ppm / °C, acceptable when the average value of the capacitance temperature coefficient τC was between -20 ppm / °C and -15 ppm / °C, or between +20 ppm / °C and +20 ppm / °C, and unacceptable when it was less than -20 ppm / °C or more than +20 ppm / °C. In this experimental example, there were no cases where the temperature characteristics were unacceptable.

[0111] [Table 1]

[0112] Examples 1 to 5 were carried out under the same conditions except that the amount of Mn added in the dielectric layer paste used to prepare the large amount of Mn added sheet was changed. Example 6 did not use a large amount of Mn added sheet, but instead used an appropriate amount of Mn added sheet.

[0113] In all of Examples 1 to 6, a concentration gradient existed in the exterior dielectric layer in which the Mn concentration increased from the vicinity of the first internal electrode layer toward the outside along the stacking direction. Furthermore, compared with the average intensity of the characteristic X-rays of Mn in a portion that was 100 μm or more and 200 μm or less away from the first internal electrode layer, the average intensity of the characteristic X-rays of Mn in a portion that was 1 μm or more and 50 μm or less away from the first internal electrode layer was 80% or more and 90% or less, and the average intensity of the characteristic X-rays of Mn in a portion that was 50 μm or more and 100 μm or less away from the first internal electrode layer was 90% or more and 100% or less.

[0114] In Examples 1 to 5, the Mn concentration in the first internal electrode layer was higher than the Mn concentration in the other internal electrode layers. In contrast, in Example 6, the Mn concentration in the first internal electrode layer was the same as the Mn concentration in the other internal electrode layers. Therefore, Examples 1 to 5 had better results in the thermal crack test than Example 6. Furthermore, in Examples 1 to 5 and other Examples described later, it was confirmed that Mn segregation was contained in each internal electrode layer, such as the first internal electrode layer, and that more Mn segregation was contained in the first internal electrode layer. In contrast, in Example 6, the content ratio of Mn segregation in all internal electrode layers was the same.

[0115] In particular, Examples 2 to 4 in which C1 / C3 was 2.5 or more and 4.0 or less, C1 / C2A was 1.2 or more and 2.0 or less, and C2A / C2B was 1.5 or more and 3.0 or less, showed even better results in the thermal crack test.

[0116] In Example 1, where C1 / C3, C2A / C2B and C1 / C2A were all high, the temperature characteristics were deteriorated compared to Examples 2-6.

[0117] Examples 7 to 9 were carried out under the same conditions as Example 3, except that the thickness of the exterior dielectric layer was changed and the size of the multilayer ceramic capacitor in the lamination direction was changed accordingly. Examples 3 and 7 to 9 all showed good results in the thermal crack test and good temperature characteristics.

[0118] In particular, Examples 3, 7, and 8, in which the thickness of the exterior dielectric layer was 150 μm or more and 500 μm or less, showed particularly good results in the thermal crack test compared to Example 9, in which the thickness of the exterior dielectric layer was 550 μm.

[0119] Examples 10 and 11 were carried out under the same conditions as Example 3, except that the thickness of the internal dielectric layer was changed and the size of the multilayer ceramic capacitor in the lamination direction was changed accordingly. Examples 3, 10, and 11 all showed good results in the thermal crack test and good temperature characteristics.

[0120] Examples 12 and 13 were carried out under the same conditions as Example 3, except that the number of stacked internal electrode layers was changed, and accordingly the number of stacked internal dielectric layers and the size of the multilayer ceramic capacitor in the stacking direction were changed. Examples 3, 12, and 13 all showed good results in the thermal crack test and good temperature characteristics.

[0121] Examples 14 to 17 were carried out under the same conditions as Example 3, except that the concentration gradient of Mn in the exterior dielectric layer was changed. Specifically, the Mn concentration gradient was changed by appropriately changing the arrangement of the Mn-free sheets.

[0122] The results of the thermal crack test and the temperature characteristics were good in all of Examples 3 and 14 to 17. However, compared to Example 3, thermal cracks were more likely to occur in Example 14, in which the average intensity of the characteristic X-rays of Mn was low in the portion at a distance of 1 um or more and 50 um or less from the first internal electrode layer, Example 15, in which the average intensity of the characteristic X-rays of Mn was high in the portion at a distance of 1 um or more and 50 um or less from the first internal electrode layer, Example 16, in which the average intensity of the characteristic X-rays of Mn was low in the portion at a distance of 50 um or more and 100 um or less from the first internal electrode layer, and Example 17, in which the average intensity of the characteristic X-rays of Mn was high in the portion at a distance of 50 um or more and 100 um or less from the first internal electrode layer.

[0123] Example 18 was carried out under the same conditions as Example 3, except that the perovskite compound was changed to BaTiO3 (abbreviated as BT in Table 1). Both Examples 3 and 18 showed good results in the thermal crack test and good temperature characteristics. [Explanation of symbols]

[0124] 1, 1a, 1b... Multilayer ceramic capacitor 2. Dielectric layer 2a...Outer dielectric layer 2b: Inner dielectric layer 3...Internal electrode layer 3a...first internal electrode layer 3b1: Gap-corresponding portion of the second internal electrode layer 3b2: Portions of the second internal electrode layer other than the gap-corresponding portions 3c...Third internal electrode layer 4...External electrode 10. Element body 11. Mn segregation 21. High-Mn-added sheet 22. Sheet with appropriate amount of Mn added 23 Mn-free sheet 31 Internal electrode pattern

Claims

1. A multilayer ceramic electronic component having laminated dielectric layers and internal electrode layers, Among the internal electrode layers, an internal electrode layer located outermost in the stacking direction is defined as a first internal electrode layer, a dielectric layer located outside the first internal electrode layer along the lamination direction among the dielectric layers is an exterior dielectric layer, The laminated ceramic electronic component has a concentration gradient in the exterior dielectric layer, where the Mn concentration increases from the vicinity of the first internal electrode layer toward the outside along the lamination direction.

2. 2. The multilayer ceramic electronic component according to claim 1, wherein the thickness of the exterior dielectric layer is 150 μm or more and 500 μm or less.

3. 3. The multilayer ceramic electronic component according to claim 2, wherein the concentration gradient exists in a portion of the exterior dielectric layer that is located at a distance of 100 μm or less from the first internal electrode layer.

4. 4. The multilayer ceramic electronic component according to claim 3, wherein, in the exterior dielectric layer, the Mn concentration in a portion that is 1 μm or more and 50 μm or less from the first internal electrode layer is 80% or more and 90% or less compared to the Mn concentration in a portion that is 100 μm or more away from the first internal electrode layer, and the Mn concentration in a portion that is 50 μm or more and 100 μm or less away from the first internal electrode layer is 90% or more and 100% or less.

5. 2. The multilayer ceramic electronic component according to claim 1, wherein the Mn concentration in the first internal electrode layer is higher than the Mn concentration in the other internal electrode layers.

6. Among the internal electrode layers, an internal electrode layer located inside the first internal electrode layer and having a gap corresponding portion is defined as a second internal electrode layer, an internal electrode layer located inside the second internal electrode layer and having no gap corresponding portion is defined as a third internal electrode layer; The Mn concentration in the first internal electrode layer is C1, the Mn concentration in the gap corresponding portion of the second internal electrode layer is C2A, and the Mn concentration in the third internal electrode layer is C3, 6. The multilayer ceramic electronic component according to claim 5, wherein C3<C2A<C1 is satisfied.

7. 7. The multilayer ceramic electronic component according to claim 6, wherein C1 / C3 is 2.5 or more and 4.0 or less.

8. 7. The multilayer ceramic electronic component according to claim 6, wherein C2A / C2B is 1.5 or more and 3.0 or less, where C2B is the Mn concentration in the portion other than the gap corresponding portion of the second internal electrode layer.

9. 7. The multilayer ceramic electronic component according to claim 6, wherein C1 / C2A is 1.2 or more and 2.0 or less.

10. 10. The multilayer ceramic electronic component according to claim 1, wherein a dielectric layer located on the inner side of the first internal electrode layer along the stacking direction among the dielectric layers is defined as an internal dielectric layer, and the thickness of the internal dielectric layer is 3.0 μm or more and 15 μm or less.

11. 10. The multilayer ceramic electronic component according to claim 1, wherein the number of laminations of the internal electrode layers is 50 or more and 300 or less.

12. 10. The multilayer ceramic electronic component according to claim 1, wherein the dielectric layers contain Ca, Sr, Zr, Ti and O.

Images