Multilayer ceramic electronic component and dielectric ceramic composition

Abstract

To provide a multilayer ceramic electronic component and a dielectric ceramic composition capable of suppressing the rate of short circuits and reducing deterioration in reliability.SOLUTION: A multilayer ceramic electronic component includes a main phase having a perovskite structure represented by the general formula ABO3, and a segregation phase containing barium, chromium, and a transition metal element other than chromium, and the molar ratio of the sum of the chromium and the transition metal element other than chromium to barium in the segregation phase is 7.0 or more, a plurality of internal electrode layers opposed to each other and sandwiched between the dielectric layer, and external electrodes electrically connected to the plurality of internal electrode layers.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a multilayer ceramic electronic component and a dielectric ceramic composition.

Background Art

[0002] In high-frequency communication systems typified by mobile phones, multilayer ceramic electronic components such as multilayer ceramic capacitors (MLCC: Multi-Layer ceramic capacitor) are used for the purpose of removing noise and the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, for the purpose of miniaturization and high capacitance of multilayer ceramic capacitors, thinning and high stacking of dielectric layers have been carried out. However, when the dielectric layer is thinned, structural defects are likely to occur due to sintering and grain growth of dielectric particles in the dielectric layer and metal particles in the internal electrode layer, which may cause an increase in the short circuit rate and deterioration of reliability due to a decrease in life.

[0005]

[0006] However, there is no description about the detailed composition of the segregation particles containing chromium, and depending on the composition of the above segregation particles, the reliability may be significantly deteriorated.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a multilayer ceramic electronic component and a dielectric ceramic composition capable of suppressing the shorting rate and suppressing deterioration of reliability.

Means for Solving the Problems

[0008] The multilayer ceramic electronic component according to the present invention has a main phase having a perovskite structure represented by the general formula ABO 3 and a segregation phase containing barium, chromium, and a transition metal element other than chromium, and a dielectric layer in which a molar ratio of the sum of the chromium and the transition metal element other than chromium to barium in the segregation phase is 7.0 or more, and a plurality of internal electrode layers provided with the dielectric layer interposed therebetween and facing each other, and an external electrode electrically connected to the plurality of internal electrode layers.

[0009] In the above multilayer ceramic electronic component, the molar ratio of chromium to barium in the segregation phase may be 2.0 or more.

[0010] In the above multilayer ceramic electronic component, the crystal system of the segregation phase may be orthorhombic.

[0011] In the above multilayer ceramic electronic component, the space group of the segregation phase may be Cmce.

[0012] In the above multilayer ceramic electronic component, the transition metal element other than chromium may be at least one of titanium, vanadium, manganese, iron, or nickel.

[0013] In the above multilayer ceramic electronic component, the transition metal element other than chromium may be titanium and nickel.

[0014] In the above multilayer ceramic electronic component, the main phase may contain at least one of barium or calcium at the A site and at least one of titanium or zirconium at the B site.

[0015] The dielectric ceramic composition according to the present invention has a main phase having a perovskite structure represented by the general formula ABO 3 and a segregated phase having barium, chromium, and a transition metal element other than chromium, and a molar ratio of the sum of the chromium and the transition metal element other than chromium to the barium in the segregated phase is 7.0 or more.

[0016] In the above dielectric ceramic composition, the molar ratio of chromium to barium in the segregated phase may be 2.0 or more.

Advantages of the Invention

[0017] According to the present invention, it is possible to provide a multilayer ceramic electronic component and a dielectric ceramic composition that can suppress the short rate and suppress the deterioration of reliability.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments will be described with reference to the drawings.

[0020] (First Embodiment) The dielectric ceramic composition according to the first embodiment is a polycrystalline ceramic including crystal particles having a perovskite structure represented by the general formula ABO 3 . These polycrystalline ceramics include one or more main-phase crystal particles 40, as illustrated in FIG. 1.

[0021] The main-phase crystal particles 40 have a perovskite structure represented by the general formula ABO 3 . The main-phase crystal particles 40 have, for example, a core-shell structure. When the main-phase crystal particles 40 have a core-shell structure, the main-phase crystal particles 40 include a substantially spherical core portion 411 and a shell portion 412 that covers and surrounds the core portion 411, as illustrated in FIG. 1. The core portion 411 is a crystal portion in which the additive compound is not solid-solved or the solid-solution amount of the additive compound is small. The shell portion 412 is a crystal portion in which the additive compound is solid-solved and has an additive compound concentration higher than the additive compound concentration of the core portion 411.

[0022] The crystal particles of barium titanate having a perovskite-type structure, which are the main components of the main-phase crystal particles 40, have a unit cell as illustrated in FIG. 2. In this unit cell, there are an A site located at the vertex of the lattice, an O site located at the face center of the lattice, and a B site located within an octahedron having the O site as a vertex, respectively. In the perovskite structure, alkaline earth metals capable of taking divalent cations such as barium (Ba), strontium (Sr), and calcium (Ca) are coordinated at the A site, and metal atoms capable of taking tetravalent cations such as hafnium (Hf), zirconium (Zr), and titanium (Ti) are coordinated at the B site.

[0023] The perovskite structure also allows a composition formula deviated from the stoichiometric composition. That is, the ratio of the A-site element to the B-site element does not necessarily have to be 1:1, and defects may be generated within a range capable of maintaining the perovskite structure. Also, defects may be generated in oxygen. For example, the composition formula A α BO 3-βWhen it is, a composition in the range of 0.98 ≤ α ≤ 1.01 and 0 ≤ β ≤ 0.05 can be tolerated.

[0024] However, for example, when oxygen defects are generated, the resistivity decreases, or ionic conductivity is exhibited, the electrical life when used as a multilayer ceramic capacitor decreases, the dielectric loss increases, and it may not be practical to use. Therefore, for the main-phase crystal particles 40 having a perovskite structure, at least one of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba), which are alkaline earth elements, may be included as necessary. Thereby, it is possible to improve the resistivity, increase the electrical long life, and reduce the dielectric loss with respect to the capacitance.

[0025] Also, as necessary, the main-phase crystal particles 40 may contain at least one of scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), and zinc (Zn), which are first transition elements. Thereby, it is possible to improve the resistivity, increase the electrical long life, and reduce the dielectric loss with respect to the capacitance.

[0026] Also, the main-phase crystal particles 40 may contain at least one of yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag), which are second transition elements, as necessary. Thereby, it is possible to improve the resistivity, increase the electrical long life, and reduce the dielectric loss with respect to the capacitance.

[0027] In addition, the main-phase crystal particles 40 may contain at least one of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au), which are third transition elements, as required. By doing so, it is possible to improve the resistivity, enhance the electrical long life, and reduce the dielectric loss with respect to the capacitance.

[0028] By using at least one of the above-described alkaline earth element, first transition metal element, second transition metal element, and third transition metal element as an additive, at least one of the alkaline earth element, first transition metal element, second transition metal element, and third transition metal element is dissolved from the interface to the inside of the main-phase crystal particles 40 in the firing temperature range of 1000°C to 1400°C for obtaining the dielectric ceramic composition, and the above-described core portion 411 and shell portion 412 can be formed in the main-phase crystal particles 40.

[0029] Incidentally, in the core-shell structure, generally, as the firing temperature increases, more various additives are dissolved in the crystal particles made of barium titanate, the shell portion 412 becomes thicker, and the particle size of the core portion 411 tends to become smaller. In the shell portion 412, for example, an acceptor element having a valence smaller than that of titanium, such as magnesium or nickel, is dissolved as a B-site element, so that the reduction of titanium during reduction firing can be suppressed and the insulation resistance can be improved. Therefore, as an example, in order to ensure a high insulation resistance of the multilayer ceramic capacitor, it is necessary to dissolve the acceptor element in the shell portion 412.

[0030] However, excessive solid solution of acceptor elements in the shell portion 412 may promote grain growth of the primary phase crystal particles 40 and increase the shorting rate. Therefore, in order to ensure a high yield, it is necessary to precisely control the amount of solid solution of acceptor elements in the shell portion 412, but such precise control has been difficult.

[0031] Therefore, the inventor of the present invention has conducted intensive research and found that by segregating the first crystal particles 41 exemplified in FIG. 1, the shorting rate can be suppressed and deterioration of reliability can be suppressed. Specifically, the inventor has found that by segregating the first crystal particles 41 containing barium, chromium, and transition metal elements other than chromium, and having a molar ratio of the sum of chromium and transition metal elements other than chromium to barium of 7.0 or more, the shorting rate can be suppressed and deterioration of reliability can be suppressed.

[0032] In addition, segregation of an oxide containing chromium suppresses abnormal grain growth during firing, thereby suppressing the shorting rate, and sufficiently promotes diffusion of oxide ions during re-oxidation treatment, so that a sufficient life can be obtained. Furthermore, in addition to chromium, the presence of transition metals with different ionic radii from chromium and transition metals with different valences from chromium sufficiently promotes diffusion of oxide ions during re-oxidation treatment, so that a sufficient life can be obtained.

[0033] From the viewpoint of sufficiently suppressing deterioration of reliability, in the first crystal particles 41, the molar ratio of the sum of chromium and transition metal elements other than chromium to barium is preferably 7.2 or more, and more preferably 7.5 or more.

[0034] On the one hand, in the first crystal particles 41, if the molar ratio of the sum of chromium and transition metal elements other than chromium to barium is too large, the lifespan may decrease. Therefore, it is preferable to set an upper limit for the molar ratio of the sum of chromium and transition metal elements other than chromium to barium. In the present embodiment, in the first crystal particles 41, the molar ratio of the sum of chromium and transition metal elements other than chromium to barium is preferably 9.0 or less, more preferably 8.8 or less, and even more preferably 8.5 or less.

[0035] In the first crystal particles 41, if the amount of chromium is small, the diffusion of oxide ions during the reoxidation treatment may not be sufficiently promoted, and there is a risk that a sufficient lifespan cannot be obtained. Therefore, it is preferable to set a lower limit for the amount of chromium in the first crystal particles 41. In the present embodiment, in the first crystal particles 41, the molar ratio of chromium to barium is preferably 2.0 or more, more preferably 2.3 or more, and even more preferably 2.6 or more.

[0036] On the other hand, in the first crystal particles 41, if the amount of chromium is large, the lifespan may decrease. Therefore, it is preferable to set an upper limit for the amount of chromium in the first crystal particles 41. In the present embodiment, in the first crystal particles 41, the molar ratio of chromium to barium is preferably 6.0 or less, more preferably 5.5 or less, and even more preferably 5.0 or less.

[0037] The crystal system of the first crystal particles 41 is preferably orthorhombic. When the crystal system of the first crystal particles 41 is orthorhombic, excessive diffusion of additive elements to the main phase crystal particles 40 through the first crystal particles 41 during firing can be suppressed, and an increase in the short circuit rate can be suppressed.

[0038] The space group of the first crystal particles 41 is preferably Cmce. When the space group of the first crystal particles 41 is Cmce, excessive diffusion of additive elements to the main phase crystal particles 40 through the first crystal particles 41 during firing can be suppressed, and an increase in the short circuit rate can be suppressed.

[0039] In the first crystal particles 41, the transition metal element other than chromium is preferably an element located near chromium in the periodic table. For example, in the first crystal particles 41, the transition metal element other than chromium is preferably at least one of titanium, vanadium, manganese, iron, or nickel. For example, as the transition metal element other than chromium, two or more elements may be used in combination. For example, titanium and nickel may be used in combination as the transition metal element other than chromium.

[0040] The inclusion of the first crystal particles 41 in the dielectric ceramic composition can be confirmed by the following procedure.

[0041] First, expose the surface of the dielectric ceramic composition. This exposure method is not particularly limited, and methods such as cutting or polishing the element can be adopted. At this time, in order to sufficiently observe the internal ceramic structure, it is preferable to finally obtain a smoothness that can be judged as a mirror surface with a diamond paste of 2 microns or less. The above method of cutting or polishing the element is suitable for observation by SEM. Furthermore, a thin slice with a thickness of 100 nm or less can also be obtained from the surface of the dielectric ceramic composition having the above-mentioned smoothness that can be judged as a mirror surface using an ion beam or the like. The above thin slice is suitable for observation by STEM.

[0042] Next, the composition of the first crystal particles 41 is identified by an energy dispersive X-ray spectrometer (EDS) or wavelength dispersive X-ray spectrometer (WDS) attached to a scanning electron microscope (SEM) or scanning transmission electron microscope (STEM), an electron probe micro analyzer (EPMA), laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), or the like.

[0043] For example, in EDS measurement, it is simply specified by the K-line intensity of chromium with respect to the K-line or L-line of barium, and the K-line intensities of titanium, vanadium, manganese, iron, and nickel. More specifically, from these intensities, correction (ZAF correction) considering the atomic number effect, absorption effect, and fluorescence excitation effect is performed, and the ratio of each to the elemental content of barium is calculated to obtain the ratio of each element.

[0044] When the sample thickness is sufficiently thin, for example, 10 nm or less, correction by the proportionality coefficient (K factor) used in the Cliff-Lorimer method may be performed to obtain the ratio of each element. In addition to the correction using the Cliff-Lorimer method, correction considering the absorption effect of the sample may be performed to obtain the ratio of each element. The absorption effect of the sample can be corrected by determining the thickness and density of the sample. The thickness of the sample can be determined, for example, by obtaining a convergent-beam electron diffraction (CBED) pattern under two-wave excitation conditions and analyzing the rocking curve observed in the diffraction disk. As the particles for obtaining the CBED pattern, matrix crystal particles 40 or the like can be used. As the density of the sample, a value such as 6.02 g / cm3, which is the density of barium titanate, can be used.

[0045] When performing EDS measurement, especially in the measurement using the Lα line of barium and the Kα line of titanium, since their energy peaks are close to each other, it may be difficult to compare the sufficient element contents. Therefore, during the measurement, it is desirable that the Lβ2 line and the LIIIab line of barium, which do not overlap the peaks, are obtained with sufficient intensity. Specifically, it is desirable that the intensity at the peak is 10,000 counts or more. At this time, since the intensity of the characteristic X-ray by barium can be specified and the element content can be calculated, even if the Lα line of barium and the Kα line of titanium overlap, the intensity of the Kα line of titanium can be specified and the element content can be accurately evaluated.

[0046] It is determined that the crystal particles having a molar ratio of chromium and transition metals other than chromium (any one or more of titanium, vanadium, manganese, iron, and nickel) to barium of 7.0 or more obtained by the above method are the first crystal particles 41. That is, compared with the main-phase crystal particles 40 made of barium titanate existing around, when a segregation phase with a large elemental ratio of chromium and transition metals other than chromium (any one or more of titanium, vanadium, manganese, iron, and nickel) to barium is detected, it is determined that the first crystal particles 41 are present. At this time, when SEM is used during the observation, in the observation by a backscattered electron image (BSE image), the first crystal particles 41 are characterized by being observed darker with relatively lower brightness compared to the main-phase crystal particles 40. Also, when STEM is used during the observation, in the observation by a high-angle annular dark-field scanning transmission electron microscopy image (HAADF-STEM image), the first crystal particles 41 are characterized by being observed darker with relatively lower brightness compared to the main-phase crystal particles 40.

[0047] In addition, when the particle diameter of the first crystal particle 41 is smaller than the spatial resolution in the EDS analysis by SEM, it is desirable to identify the composition of the first crystal particle 41 by a scanning transmission electron microscope (STEM).

[0048] In addition, when confirming the crystal structure of the first crystal particle 41, it is desirable to perform selected area electron diffraction (SAED) on the first crystal particle 41 by a transmission electron microscope (TEM) and analyze the obtained electron diffraction pattern. It is further desirable to confirm that the electron diffraction pattern can be obtained at a plurality of zone axes and indexed with a crystal structure having the same crystal system, space group, and lattice constant.

[0049] In addition, there is no particular limitation on the method for calculating the cross-sectional areas of the main phase crystal particle 40 and the first crystal particle 41. For example, for any main phase crystal particle 40 and the first crystal particle 41, image processing is performed on the BSE image obtained by SEM, and the number of pixels in the region occupied by each of the main phase crystal particle 40 and the first crystal particle 41 in the above image is counted, whereby the cross-sectional areas of the main phase crystal particle 40 and the first crystal particle 41 can be calculated. When the total cross-sectional areas of the main phase crystal particle 40 and the first crystal particle 41 are calculated by the above method, for example, the ratio of the first crystal particle 41 is preferably 0.050% to 45.0%, more preferably 0.50% to 25.0%, and still more preferably 1.0% to 15.0%.

[0050] As illustrated in FIG. 1, in addition to the main-phase crystal particles 40 and the first crystal particles 41, the dielectric porcelain composition preferably contains second crystal particles or glass particles 43 that are different from the main-phase crystal particles 40 and the first crystal particles 41 in composition or crystal structure and contain silicon. By containing at least one of the second crystal particles 42 and the glass particles 43 in the dielectric porcelain composition, it becomes possible to sinter the dielectric porcelain composition at 1300° C. or lower to be sufficiently densified. As the second crystal particles 42, crystal particles such as silicate (SiO 2 ), enstatite (MgSiO 3 ), barium magnesium silicate (BaMgSiO 4 ), and fresnoite (Ba 2 TiSi 2 O 8 ) can be used. As the glass particles 43, glass particles such as silicate (SiO 2 ), enstatite (MgSiO 3 ), barium magnesium silicate (BaMgSiO 4 ), and fresnoite (Ba 2 TiSi 2 O 8 ) can be used.

[0051] In addition, the dielectric porcelain composition may contain by-products derived from added substances such as geikielite (MgTiO 3 ), manganese nickel oxide ((Mn,Ni)O), and pyrophanite (MnTiO 3 ), or by-products generated from electrodes.

[0052] As illustrated in FIG. 1, the first crystal particles 41 and the second crystal particles 42 are preferably located at the grain boundaries of the main-phase crystal particles 40. This is because it can suppress a decrease in the resistivity of the dielectric porcelain composition.

[0053] The first crystal particles 41 and the second crystal particles 42 are preferably located at the grain boundary triple points of the main-phase crystal particles 40. This is because it can suppress a decrease in the resistivity of the dielectric porcelain composition. Note that the grain boundary triple point refers to the boundary of three crystal grain boundaries.

[0054] The glass particles 43 are preferably located at the grain boundaries of the main-phase crystal particles 40. This is because it can suppress a decrease in the relative permittivity of the dielectric ceramic composition.

[0055] The glass particles 43 are preferably located at the grain boundary triple points of the main-phase crystal particles 40. This is because it can suppress a decrease in the relative permittivity of the dielectric ceramic composition.

[0056] It is preferable that the shell portion 412 of the main-phase crystal particles 40 contains a rare earth element. This is because the lifetime of the dielectric ceramic composition is improved.

[0057] (Second Embodiment) In the second embodiment, the multilayer ceramic capacitor 100 using the dielectric ceramic composition according to the first embodiment will be described.

[0058] FIG. 3 is a partial cross-sectional perspective view of the multilayer ceramic capacitor 100. FIG. 4 is a cross-sectional view taken along line A-A of FIG. 3. FIG. 5 is a cross-sectional view taken along line B-B of FIG. 3. As illustrated in FIGS. 3 to 5, the multilayer ceramic capacitor 100 includes a multilayer chip 10 having a substantially rectangular parallelepiped shape, and external electrodes 20a and 20b provided on two opposing end faces of the multilayer chip 10. Of the four surfaces of the multilayer chip 10 other than the two end faces, the two surfaces other than the upper and lower surfaces in the stacking direction are referred to as side surfaces. The external electrodes 20a and 20b extend over the upper surface, lower surface, and two side surfaces of the multilayer chip 10 in the stacking direction. However, the external electrodes 20a and 20b are spaced apart from each other.

[0059] The multilayer chip 10 has a structure in which a dielectric layer 11 containing a dielectric ceramic composition and an internal electrode layer 12 containing a base metal material are alternately laminated. The edges of each internal electrode layer 12 are alternately exposed on the end face where the external electrode 20a of the multilayer chip 10 is provided and the end face where the external electrode 20b is provided. Thereby, each internal electrode layer 12 is alternately electrically connected to the external electrode 20a and the external electrode 20b. As a result, the multilayer ceramic capacitor 100 has a structure in which a plurality of dielectric layers 11 are laminated via the internal electrode layer 12. Further, in the laminate of the dielectric layer 11 and the internal electrode layer 12, an internal electrode layer 12 is disposed in the outermost layer in the lamination direction, and the upper and lower surfaces of the laminate are covered with a cover layer 13. The cover layer 13 is mainly composed of a ceramic material. For example, the material of the cover layer 13 has the same main component of the ceramic material as the dielectric layer 11.

[0060] The size of the multilayer ceramic capacitor 100 is, for example, a length of 0.25 mm, a width of 0.125 mm, a height of 0.125 mm, or a length of 0.4 mm, a width of 0.2 mm, a height of 0.2 mm, or a length of 0.6 mm, a width of 0.3 mm, a height of 0.3 mm, or a length of 1.0 mm, a width of 0.5 mm, a height of 0.5 mm, or a length of 3.2 mm, a width of 1.6 mm, a height of 1.6 mm, or a length of 4.5 mm, a width of 3.2 mm, a height of 2.5 mm, but is not limited to these sizes.

[0061] The internal electrode layer 12 is mainly composed of a base metal such as Ni (nickel), Cu (copper), Sn (tin). As the internal electrode layer 12, a noble metal such as Pt (platinum), Pd (palladium), Ag (silver), Au (gold) or an alloy containing these may be used.

[0062] As illustrated in FIG. 4, the region where the internal electrode layer 12 connected to the external electrode 20a and the internal electrode layer 12 connected to the external electrode 20b face each other is the region where capacitance is generated in the multilayer ceramic capacitor 100. Therefore, the region where the capacitance is generated is referred to as a capacitance region 14. That is, the capacitance region 14 is a region where adjacent internal electrode layers 12 connected to different external electrodes face each other.

[0063] A region where the internal electrode layers 12 connected to the external electrode 20a face each other without passing through the internal electrode layer 12 connected to the external electrode 20b is referred to as an end margin 15. Also, a region where the internal electrode layers 12 connected to the external electrode 20b face each other without passing through the internal electrode layer 12 connected to the external electrode 20a is also the end margin 15. That is, the end margin 15 is a region where the internal electrode layers 12 connected to the same external electrode face each other without passing through the internal electrode layer 12 connected to a different external electrode. The end margin 15 is a region where no capacitance is generated.

[0064] As illustrated in FIG. 5, in the multilayer chip 10, a region from the two side surfaces of the multilayer chip 10 to the internal electrode layer 12 is referred to as a side margin 16. That is, the side margin 16 is a region provided so as to cover the ends where the plurality of internal electrode layers 12 laminated in the above-described laminated structure extend to the two side surfaces. The side margin 16 is also a region where no capacitance is generated.

[0065] In the multilayer ceramic capacitor 100 according to the present embodiment, the main phase crystal particles 40 and the first crystal particles 41 illustrated in FIG. 1 are included in at least a part of the dielectric layer 11 of the capacitance region 14. Thereby, high reliability can be realized and high insulation resistance can be realized.

[0066] The thickness of the dielectric layer 11 in the stacking direction is, for example, 0.50 μm or less, 0.40 μm or less, and 0.30 μm or less. The thickness of the dielectric layer 11 can be measured by observing a cross section of the multilayer ceramic capacitor 100 with an SEM (scanning electron microscope), measuring the thickness of 10 points each for 10 different dielectric layers 11, and deriving the average value of all the measurement points.

[0067] The average thickness per layer of the internal electrode layer 12 in the stacking direction is, for example, 0.50 μm or less, 0.40 μm or less, and 0.30 μm or less. The thickness of the internal electrode layer 12 can be measured by observing a cross section of the multilayer ceramic capacitor 100 with an SEM (scanning electron microscope), measuring the thickness at 10 points each for 10 different internal electrode layers, and deriving the average value of all the measurement points.

[0068] Subsequently, a method for manufacturing the multilayer ceramic capacitor 100 will be described. FIG. 6 is a diagram illustrating the flow of a method for manufacturing the multilayer ceramic capacitor 100.

[0069] (Raw material powder production process) First, a dielectric ceramic composition for forming the dielectric layer 11 is prepared. The A-site element and the B-site element contained in the dielectric layer 11 are usually contained in the dielectric layer 11 in the form of a sintered body of ABO 3 particles. For example, barium titanate is a compound belonging to the tetragonal system near room temperature having a perovskite structure and exhibits a high relative dielectric constant. This barium titanate can generally be synthesized by reacting a titanium raw material such as titanium dioxide with a barium raw material such as barium carbonate. As methods for synthesizing barium titanate, which is the main component of the dielectric layer 11, various conventional methods are known, such as the solid-phase method, the sol-gel method, the hydrothermal method, and the like. In the present embodiment, any of these can be employed.

[0070] To the barium titanate powder obtained by the above method, a predetermined additive is added. As an example, the additives within the range shown in the example of the dielectric ceramic composition according to the first embodiment are used. If necessary, oxides or glasses containing Zr (zirconium), V (vanadium), Cr (chromium), Co (cobalt), Ni (nickel), Li (lithium), B (boron), Na (sodium), K (potassium) may also be used. Further, if necessary, as rare earth elements, oxides of Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium) and Lu (lutetium) may be added.

[0071] Note that, in order to produce the first crystal particles 41, for example, barium titanate powder with an average particle size of 100 nm is prepared, and a predetermined amount of BaCr 10 O 15 , Ho 2 O 3 , NiO, TiO 2 , MgO, SiO 2 is added. Note that BaCr 10 O 15 powder is obtained by preparing barium carbonate (BaCO 3 ) powder and chromium oxide (Cr 2 O 3 ) powder, wet-mixing 5 moles of chromium oxide powder with respect to 1 mole of barium carbonate powder, drying, and then firing the obtained mixed powder in a reducing atmosphere with an oxygen partial pressure of 10 -13 ~10 -9 atm at 1100 to 1300 °C for 1 to 3 hours. For example, for the ceramic material obtained as described above, the particle size may be adjusted by performing a pulverization treatment as necessary, or may be adjusted by combining with a classification treatment. Through the above steps, BaCr 10 O 15 powder is obtained.

[0072] For example, a compound containing an additive compound is wet-mixed with barium titanate powder, dried, and pulverized to prepare a ceramic material in which the barium titanate powder and the additive compound are mixed. For example, for the ceramic material obtained as described above, the particle size may be adjusted by pulverization treatment as necessary, or the particle size may be adjusted by combining with a classification treatment. Through the above steps, a dielectric ceramic composition is obtained.

[0073] (Coating process) Next, a binder such as polyvinyl butyral (PVB) resin, an organic solvent such as ethanol or toluene, and a plasticizer are added to the obtained dielectric ceramic composition and wet-mixed. Using the obtained slurry, a ceramic green sheet 51 is coated on a substrate by, for example, the die coater method or the doctor blade method and dried. The substrate is, for example, a polyethylene terephthalate (PET) film. The figure illustrating the coating process is omitted.

[0074] (Internal electrode formation process) Next, as illustrated in FIG. 7(a), an internal electrode pattern 52 that is alternately led out to a pair of external electrodes with different polarities is arranged by printing a metal conductive paste for forming an internal electrode containing an organic binder on the surface of the ceramic green sheet 51 by screen printing, gravure printing, or the like. Ceramic particles are added to the metal conductive paste as a co-material. The main component of the ceramic particles is not particularly limited, but it is preferably the same as the ceramic that is the main component of the dielectric layer 11. For example, barium titanate with an average particle diameter of 50 nm or less may be uniformly dispersed.

[0075] Next, a binder such as ethyl cellulose and an organic solvent such as terpineol are added to the dielectric ceramic composition obtained in the raw material powder production process, and kneaded with a roll mill to obtain a dielectric pattern paste for the reverse pattern layer. As illustrated in Fig. 7(a), on the ceramic green sheet 51, the dielectric pattern paste is printed in the peripheral area where the internal electrode pattern 52 is not printed to arrange the dielectric pattern 53 and fill the step with the internal electrode pattern 52. The ceramic green sheet 51 on which the internal electrode pattern 52 and the dielectric pattern 53 are printed is referred to as a lamination unit.

[0076] Thereafter, as illustrated in Fig. 7(b), the lamination units are laminated such that the internal electrode layer 12 and the dielectric layer 11 are staggered, and the internal electrode layer 12 has edges alternately exposed at both end faces in the length direction of the dielectric layer 11 and is alternately drawn out to a pair of external electrodes 20a and 20b with different polarities. For example, the number of laminated internal electrode patterns 52 is set to 100 to 1000 layers.

[0077] (Pressing process) As illustrated in Fig. 8, a cover sheet 54 is laminated on the top and bottom of the laminate in which the lamination units are laminated by a predetermined number (for example, 2 to 10 layers) and thermocompression bonded. As an example of the ceramic material of the cover sheet 54, the above-described dielectric ceramic composition can be used. Thereafter, it is cut into a predetermined chip size (for example, 1.0 mm × 0.5 mm).

[0078] (Firing process) The ceramic laminate thus obtained is subjected to a debinding treatment in an N 2 atmosphere, an air atmosphere, etc., and then a metal paste serving as an underlayer for the external electrodes 20a and 20b is applied by a dipping method, and the oxygen partial pressure is 10 -12 ~10 -9Firing is performed at 1100 to 1300 °C for 10 minutes to 2 hours in a reducing atmosphere of atm. In this way, the multilayer ceramic capacitor 100 is obtained. In the firing process, rapid heating is performed. The heating rate in the firing process is, for example, 6000 °C / h. Thereby, the substantial time in firing can be shortened, and higher mass productivity can be obtained. In this way, at least a part of the dielectric layer 11 in the capacitance region 14 can form the main phase crystal particles 40 illustrated in FIG. 1, and the first crystal particles 41 can be formed.

[0079] (Annealing process) Thereafter, if necessary, annealing is performed at 900 to 1150 °C for 30 minutes to 2 hours in a reducing atmosphere with an oxygen partial pressure of 10 -12 ~10 -9 atm, and slow cooling may be performed. The cooling rate may be, for example, a rate of 200 °C / h for cooling.

[0080] (Re-oxidation treatment process) Thereafter, re-oxidation treatment may be performed at 600 °C to 1000 °C in an N 2 gas atmosphere.

[0081] (Plating process) Thereafter, metal coatings such as Cu, Ni, and Sn are applied by plating on the base layers of the external electrodes 20a and 20b. Through the above processes, the multilayer ceramic capacitor 100 is completed.

[0082] The side margin portion may be attached or applied to the side surface of the above-described laminated portion. Specifically, as illustrated in FIG. 9, a laminated portion is obtained by alternately laminating a ceramic green sheet 51 and an internal electrode pattern 52 having the same width as the ceramic green sheet 51. Next, a sheet formed of a dielectric pattern paste may be attached as the side margin portion 55 to the side surface of the laminated portion.

[0083] According to the manufacturing method according to this embodiment, the main-phase crystal particles 40 illustrated in FIG. 1 can be formed in at least a part of the dielectric layer 11 of the capacitance region 14, and the first crystal particles 41 can be formed. Thereby, the short circuit rate can be suppressed and the reliability degradation can be suppressed.

[0084] In addition, in each of the above embodiments, a multilayer ceramic capacitor has been described as an example of a multilayer ceramic electronic component, but the present invention is not limited thereto. For example, other multilayer ceramic electronic components such as varistors and thermistors may be used.

Example

[0085] (Example 1) Barium titanate powder with an average particle size of 100 nm was prepared. For 100 moles of barium titanate powder, Ho 2 O 3 was added in an amount of 0.8 mol, BaCr 10 O 15 was added in an amount of 0.2 mol, NiO was added in an amount of 0.5 mol, TiO 2 was added in an amount of 0.5 mol, MgO was added in an amount of 0.5 mol, and SiO 2 was added in an amount of 1.0 mol.

[0086] The dielectric ceramic composition was mixed with ethanol, toluene, and PVB (polyvinyl butyral) resin to prepare a dielectric slurry. This slurry was formed into a ceramic green sheet using a die coater and dried. A metal conductive paste containing the main component metal of the internal electrode layer 12, a co-material, a binder (ethyl cellulose), a solvent, and other auxiliary agents as necessary was prepared using a planetary ball mill and screen-printed on the ceramic green sheet. Eleven laminated units with the metal conductive paste printed on the ceramic green sheet were stacked, and cover sheets were stacked on the top and bottom thereof, respectively. Thereafter, a laminate was obtained by thermocompression bonding and cut into a predetermined shape. The obtained laminate was N 2After debinding in an atmosphere, a metal conductive paste containing a metal filler mainly composed of nickel, a co-material, a binder, a solvent, etc. was applied to the base layer from both end faces to each side face of the laminate and dried. Then, in a reducing atmosphere, the metal conductive paste for the base layer was fired simultaneously with the laminate at 1300 °C to obtain a sintered body. The heating rate was 6000 °C / h. The shape dimensions of the obtained sintered body were 0.6 mm in length, 0.3 mm in width, and 0.3 mm in height. Then, an annealing treatment was performed at 900 to 1150 °C for 1 hour. Then, a reoxidation treatment was performed at 950 °C. Then, plating was performed to form a Cu plating layer, a Ni plating layer, and a Sn plating layer on the surface of the base layer, and a multilayer ceramic capacitor 100 was obtained. The average thickness of the dielectric layer 11 was 0.5 μm.

[0087] (Example 2) In Example 2, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.2 mol of BaCr 10 O 15 was added, 0.5 mol of Fe 2 O 3 was added, 0.15 mol of V 2 O 5 was added, 0.5 mol of MgO was added, and 1.0 mol of SiO 2 was added. Other conditions were the same as in Example 1.

[0088] (Example 3) In Example 3, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.2 mol of BaCr 10 O 15 was added, 0.5 mol of TiO 2 was added, 0.25 mol of Fe 2 O 3 was added, 0.5 mol of MgO was added, and 1.0 mol of SiO 2 was added. Other conditions were the same as in Example 1.

[0089] (Example 4) In Example 4, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.2 mol of BaCr 10 O 15 was added, 0.5 mol of NiO was added, 0.5 mol of TiO 2 was added, 0.5 mol of MgO was added, and 1.0 mol of SiO 2 was added. Other conditions were the same as in Example 1.

[0090] (Example 5) In Example 5, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.2 mol of BaCr 10 O 15 was added, 0.5 mol of NiO was added, 0.5 mol of MgO was added, and 1.0 mol of SiO 2 was added. Other conditions were the same as in Example 1.

[0091] (Example 6) In Example 6, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.15 mol of BaCr 10 O 15 was added, 0.5 mol of NiO was added, 0.5 mol of TiO 2 was added, 0.5 mol of MgO was added, and 1.0 mol of SiO 2 was added. Other conditions were the same as in Example 1.

[0092] (Example 7) In Example 7, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.1 mol of BaCr 10 O 15 was added, 0.5 mol of NiO was added, 0.5 mol of TiO 2 was added, 0.5 mol of MgO was added, and 1.0 mol of SiO 2 was added. Other conditions were the same as in Example 1.

[0093] (Example 8) In Example 8, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.2 mol of BaCr 2 O 3 was added, 0.5 mol of NiO was added, 0.5 mol of TiO 2 was added, 0.5 mol of MnCO 3 was added, 0.5 mol of MgO was added, and 1.0 mol of SiO 2 was added. Other conditions were the same as in Example 1.

[0094] (Example 9) In Example 9, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.2 mol of BaCr 10 O 15 was added, 0.5 mol of NiO was added, 0.25 mol of Fe 2 O 3 was added, 0.15 mol of V 2 O 5 was added, 0.5 mol of MgO was added, and 1.0 mol of SiO 2 was added. Other conditions were the same as in Example 1.

[0095] (Example 10) In Example 10, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.2 mol of BaCr 10 O 15 was added, 0.5 mol of TiO 2 was added, 0.25 mol of Fe 2 O 3 was added, 0.5 mol of MgO was added, and 1.0 mol of SiO 2 was added. Other conditions were the same as in Example 1.

[0096] (Example 11) In Example 11, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, BaCr10 O 15 0.2 mol of O was added, 0.5 mol of NiO was added, and MnCO 3 0.5 mol of was added, and V 2 O 5 0.15 mol of O was added, 0.5 mol of MgO was added, and SiO 2 1.0 mol of was added. Other conditions were the same as in Example 1.

[0097] (Example 12) In Example 12, with respect to 100 mol of barium titanate powder, Ho 2 O 3 0.8 mol of O was added, 0.1 mol of BaCr 10 O 15 was added, 1.5 mol of NiO was added, and TiO 2 0.5 mol of was added, 0.5 mol of MgO was added, and SiO 2 1.0 mol of was added. Other conditions were the same as in Example 1.

[0098] (Example 13) In Example 13, with respect to 100 mol of barium titanate powder, Ho 2 O 3 0.8 mol of O was added, 0.1 mol of BaCr 10 O 15 was added, 1.0 mol of NiO was added, and TiO 2 0.5 mol of was added, 0.5 mol of MgO was added, and SiO 2 1.0 mol of was added. Other conditions were the same as in Example 1.

[0099] (Example 14) In Example 14, with respect to 100 mol of barium titanate powder, Ho 2 O 3 0.8 mol of O was added, 0.1 mol of BaCr 10 O 15 was added, 1.0 mol of NiO was added, and MnCO 3 0.5 mol of was added, 0.5 mol of MgO was added, and SiO 2 1.0 mol of was added. Other conditions were the same as in Example 1.

[0100] (Example 15) In Example 15, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.1 mol of BaCr 10 O 15 was added, 1.0 mol of NiO was added, 0.25 mol of Fe 2 O 3 was added, 0.5 mol of MgO was added, and 1.0 mol of SiO 2 was added. Other conditions were the same as in Example 1.

[0101] (Example 16) In Example 16, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.2 mol of BaCr 10 O 15 was added, 0.5 mol of MnCO 3 was added, 0.15 mol of V 2 O 5 was added, 0.5 mol of MgO was added, and 1.0 mol of SiO 2 was added. Other conditions were the same as in Example 1.

[0102] (Comparative Example 1) In Comparative Example 1, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.5 mol of Cr 2 O 3 was added, 0.5 mol of Fe 2 O 3 was added, 0.5 mol of V 2 O 5 was added, 0.5 mol of MgO was added, and 1.0 mol of SiO 2 was added. Other conditions were the same as in Example 1.

[0103] (Comparative Example 2) In Comparative Example 2, 0.8 mol of Ho 2 O 3 was added to 100 mol of barium titanate powder, 0.5 mol of MgO was added, and 0.5 mol of MnCO 30.5 mol was added, and V 2 O 5 0.15 mol was added, and SiO 2 1.0 mol was added. Other conditions were the same as those in Example 1.

[0104] For Examples 1 to 16 and Comparative Examples 1 and 2, in addition to the main-phase barium titanate particles, it was confirmed whether segregation particles were formed. As a result, in any of Examples 1 to 16 and Comparative Examples 1 and 2, it was confirmed that segregation particles were formed in addition to the main-phase barium titanate particles.

[0105] Next, it was confirmed whether the confirmed segregation particles were a Ba-M-O phase. Here, M is any one or more elements of chromium, nickel, titanium, iron, and manganese. As a result, in Examples 1 to 16 and Comparative Example 1, it was confirmed that the segregation particles were a Ba-M-O phase.

[0106] Next, the molar ratio of M / Ba in the confirmed Ba-M-O phase was measured. As a result, the M / Ba ratio was 7.9 in Example 1, 7.1 in Example 2, 8.4 in Example 3, 7.6 in Example 4, 7.8 in Example 5, 8.2 in Example 6, 8.6 in Example 7, 8.9 in Example 8, 9.4 in Example 9, 8.8 in Example 10, 8.8 in Example 11, 8.6 in Example 12, 7.7 in Example 13, 7.2 in Example 14, 7.3 in Example 15, 7.9 in Example 16, and 6.5 in Comparative Example 1.

[0107] Next, the molar ratio of Cr / Ba in the confirmed Ba-M-O phase was measured. As a result, the Cr / Ba ratio was 3.5 in Example 1, 2.2 in Example 2, 2.1 in Example 3, 3.6 in Example 4, 4.8 in Example 5, 3.2 in Example 6, 2.9 in Example 7, 2.3 in Example 8, 2.7 in Example 9, 3.9 in Example 10, 4.6 in Example 11, 2.4 in Example 12, 2.6 in Example 13, 2.8 in Example 14, 3.6 in Example 15, 2.2 in Example 16, and 2.2 in Comparative Example 1.

[0108] Next, the element of M in the confirmed Ba-M-O phase was specified. The element of M was chromium, nickel, and titanium in Example 1, chromium, iron, and vanadium in Example 2, chromium, titanium, and iron in Example 3, chromium, nickel, and titanium in Example 4, chromium and nickel in Example 5, chromium, nickel, and titanium in Example 6, chromium, nickel, and titanium in Example 7, chromium, nickel, titanium, and manganese in Example 8, chromium, nickel, iron, and vanadium in Example 9, chromium, titanium, and iron in Example 10, chromium, nickel, manganese, and vanadium in Example 11, chromium, nickel, and titanium in Example 12, chromium, nickel, and titanium in Example 13, chromium, nickel, and manganese in Example 14, chromium, nickel, and iron in Example 15, chromium, manganese, and vanadium in Example 16, and chromium, iron, and vanadium in Comparative Example 1.

[0109] Next, the crystal system of the confirmed Ba-M-O phase was examined. The crystal system of the Ba-M-O phase was orthorhombic in Examples 1 to 16 and monoclinic in Comparative Example 1.

[0110] Next, the space group of the confirmed Ba-M-O phase was examined. The space group of the Ba-M-O phase was Cmce in Examples 1 to 16 and C2 / m in Comparative Example 1.

[0111] (Short ratio measurement) Next, the short-circuit rates of Examples 1 to 16 and Comparative Examples 1 and 2 were measured. Using an LCR meter, the short-circuit rate was evaluated under the condition of applying a voltage with an Osc (Oscillation level) of 0.5 V and a frequency of 1 kHz. For each of Examples 1 to 16 and Comparative Examples 1 and 2, 200 samples were evaluated, and the ratio of the number of samples in which a short circuit occurred among the 200 samples was defined as the short-circuit rate (%).

[0112] (Reliability test) Next, the lifetimes of Examples 1 to 16 and Comparative Examples 1 and 2 were measured. For the cross-sections taken along the A-A line and the B-B line shown in FIGS. 4 and 5, the capacitance region 14 was exposed by cutting or polishing, and finally, for each thickness t of the dielectric layer 11, a smoothness that could be judged as a mirror surface was obtained using a diamond paste of 2 microns or less. The reliability test was conducted by continuously applying a DC voltage in an environment of 150° C. so that the electric field strength V / t applied to the dielectric layer was 30 V / μm, and measuring the change over time in the DC current value flowing through the multilayer ceramic capacitor. The lifetime of the multilayer ceramic capacitor was defined as the time from when the DC voltage was applied until the resistance value of the multilayer ceramic capacitor deteriorated and fell below 100 Ω. For each of Examples 1 to 16 and Comparative Examples 1 and 2, the lifetimes of 20 samples were measured, and the average lifetime was calculated.

[0113] When the short-circuit rate was 25% or less and the average lifetime exceeded 3000 min, the comprehensive judgment was determined to be very good "◎", when the average lifetime exceeded 1000 min, the comprehensive judgment was determined to be good "〇", and otherwise the comprehensive judgment was determined to be unqualified "×". The results are shown in Table 1. All of Examples 1 to 16 were determined to have a very good "◎" or good "〇" comprehensive judgment, and both of Comparative Examples 1 and 2 were determined to have an unqualified "×" comprehensive judgment.

Table 1

[0114] In Comparative Example 2, the short circuit rate was 100%, and no acceptable products were obtained, so the reliability test could not be conducted. This is presumably because the Ba-M-O phase was not formed in Comparative Example 2, and abnormal grain growth was not suppressed. In contrast, in Examples 1 to 16 and Comparative Example 1, the short circuit rate was suppressed to 25% or less. This is presumably because the Ba-M-O phase was formed and abnormal grain growth was suppressed.

[0115] In Examples 1 to 16, the average life exceeded 1000 min in each case. This is presumably because in the Ba-M-O phase, the molar ratio of M / Ba was 7.0 or more. In Comparative Example 1, the average life was less than 1000 min. This is presumably because the molar ratio of M / Ba was less than 7.0.

[0116] As described above in detail with respect to the embodiments of the present invention, the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of Reference Numerals

[0117] 10 Multilayer chip 11 Dielectric layer 12 Internal electrode layer 13 Cover layer 14 Capacitance region 15 End margin 16 Side margin 20a, 20b External electrode 40 Main phase crystal particles 41 First crystal particles 42 Second crystal particles 43 Glass particles 51 Ceramic green sheet 52 Internal electrode pattern 53 Dielectric pattern 54 Cover sheet 55 Side margin portion 100 Multilayer ceramic capacitor

Claims

1. General formula ABO ３ It has a main phase having a perovskite structure represented by the formula, and a segregated phase containing barium, chromium, and a transition metal element other than chromium, and a dielectric layer in which the molar ratio of the sum of the chromium and the transition metal element other than chromium to barium in the segregated phase is 7.0 or more. A multilayer ceramic electronic component having a plurality of internal electrode layers provided with the dielectric layer therebetween and facing each other, and an external electrode electrically connected to the plurality of internal electrode layers.

2. The multilayer ceramic electronic component according to Claim 1, wherein a molar ratio of chromium to barium in the segregation phase is 2.0 or more.

3. The multilayer ceramic electronic component according to Claim 1, wherein a crystal system of the segregation phase is orthorhombic.

4. The multilayer ceramic electronic component according to Claim 1, wherein a space group of the segregation phase is Cmce.

5. The multilayer ceramic electronic component according to Claim 1, wherein the transition metal element other than chromium is at least one of titanium, vanadium, manganese, iron, or nickel.

6. The multilayer ceramic electronic component according to Claim 1, wherein the transition metal element other than chromium is titanium and nickel.

7. The multilayer ceramic electronic component according to Claim 1, wherein the main phase contains at least one of barium or calcium at an A site and at least one of titanium or zirconium at a B site.

8. General formula ABO ３ A dielectric ceramic composition having a main phase with a perovskite structure represented by the formula, and a segregated phase containing barium, chromium, and a transition metal element other than chromium, wherein the molar ratio of the sum of chromium and the transition metal element other than chromium to barium in the segregated phase is 7.0 or more.

9. The dielectric ceramic composition according to Claim 8, wherein a molar ratio of chromium to barium in the segregation phase is 2.0 or more.

Images