Dielectric compositions and dielectric components
A dielectric composition with controlled sintering aids and limited Si content forms a high-density dielectric layer in MLCCs, addressing grain growth issues to achieve thinner, reliable layers with maintained performance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- K C M
- Filing Date
- 2024-11-11
- Publication Date
- 2026-05-21
AI Technical Summary
Conventional dielectric compositions face challenges in thinning high-density dielectric layers of multilayer ceramic capacitors (MLCCs) due to sintering aids promoting grain growth, leading to reduced reliability and increased particle coarseness, which affects the integrity and performance of the dielectric layer.
A dielectric composition comprising dielectric particles with specific ratios of Mn, Al, Ca, and rare earth elements, along with limited Si content, to control sintering behavior and suppress grain growth, ensuring high density and small particle sizes, thereby maintaining relative permittivity and reliability.
The composition enables the formation of a high-density dielectric layer with suppressed particle coarsening, allowing for thinner dielectric layers in MLCCs while maintaining high reliability and permittivity.
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Abstract
Description
[Technical Field]
[0001] The technologies disclosed herein relate to dielectric compositions and dielectric components manufactured using said dielectric compositions. [Background technology]
[0002] Multilayer ceramic capacitors (MLCCs) are widely used in various electronic devices due to their small size and high capacitance. MLCCs have a structure in which multiple dielectric layers containing insulating ceramic material (dielectric) and internal electrode layers containing conductive metal are stacked. The dielectric layers of an MLCC are formed by firing a dielectric composition mainly composed of dielectric particles. Furthermore, the dielectric composition contains various by-components that contribute to improving the performance of the dielectric layer after firing.
[0003] For example, the dielectric composition described in Patent Document 1 contains a large amount of liquid elements such as SiO2 as a minor component. This induces simultaneous and multiple abnormal grain growth of dielectric particles during firing. Patent Document 1 claims that this simultaneous and multiple abnormal grain growth forms a dielectric layer with a uniform microstructure. Patent Document 2 also discloses a technique for improving the density of a dielectric layer (sintered body) by filling the spaces between dielectric particles (main phase particles) with a segregation phase containing multiple components. [Prior art documents] [Patent Documents]
[0004] [Patent Document 1] Japanese Patent Publication No. 2022-101430 [Patent Document 2] Patent No. 7327065 [Overview of the project] [Problems that the invention aims to solve]
[0005] By the way, in recent years, with the miniaturization of MLCCs, further thinning of the dielectric layer has been studied. However, with conventional technologies, it has been difficult to thin the high-density dielectric layer. Specifically, the dielectric layer for MLCCs needs to be made denser in order to ensure the desired relative permittivity. For this reason, in conventional dielectric compositions, sintering aids such as SiO2 have been used to promote the sintering of dielectric particles. However, this type of sintering aid also promotes the grain growth of dielectric particles. Here, when the dielectric particles coarsen during firing, the number of dielectric particles stacked in the thickness direction of the fired dielectric layer decreases. If an attempt is made to thin the dielectric layer in this case, points where no dielectric particles exist in the thickness direction of the dielectric layer will occur, and the reliability of the dielectric layer will decrease.
[0006] The technology disclosed herein has been made to solve the above problems, and an object thereof is to provide a dielectric composition capable of forming a high-density dielectric layer while suppressing the coarsening of dielectric particles.
Means for Solving the Problems
[0007] The dielectric composition disclosed herein includes a main component composed of dielectric particles and a sub-component. And the sub-component is the following elements when the total number of moles of the main component is 100 mol%: Mn 0.8 mol% to 2.5 mol%; Al 0.3 mol% to 0.9 mol%; Ca 0.1 mol% to 0.4 mol%; rare earth elements 0.7 mol% to 2.5 mol% and the Si content is 0.2 mol% or less.
[0008] As a result of various experiments and studies, the inventors have discovered that when using a dielectric composition having the above composition, it is possible to form a high-density dielectric layer while suppressing coarsening of the dielectric particles. Although not intended to limit the technology disclosed herein, it is presumed that the coexistence of this coarsening suppression effect and density improvement effect is caused by the following actions. First, among the sub-components of the above composition, Mn and Al function as sintering aids. By these, the density of the dielectric layer after firing can be improved. On the other hand, Ca has a function of reducing the particle diameter of the dielectric particles after firing. Also, the rare earth element has a function of slowing down the sintering rate of the dielectric particles. Thereby, since the sintering unevenness of the dielectric particles is suppressed, generation of local coarse particles can be prevented. It has been experimentally confirmed that the sub-components containing the above elements in a predetermined ratio can form a high-density dielectric layer while suppressing coarsening of the dielectric particles. Further, in the dielectric composition disclosed herein, the content of Si that promotes coarsening of the dielectric particles is limited to 0.2 mol% or less. Therefore, according to the dielectric composition disclosed herein, it is possible to realize thinning of the dielectric layer while maintaining a sufficient relative permittivity.
[0009] Also, as another aspect of the technology disclosed herein, a dielectric component is provided. The dielectric component disclosed herein includes a main component composed of dielectric particles and a sub-component. This sub-component is the following element when the total number of moles of the main component is 100 mol%: Mn 0.8 mol% to 2.5 mol%; Al 0.3 mol% to 0.9 mol%; Ca 0.1 mol% to 0.4 mol%; rare earth element 0.7 mol% to 2.5 mol% is included. And in this dielectric component, in the particle size distribution based on the number of dielectric particles by SEM observation, the ratio of dielectric particles having a particle diameter of 1 μm or more is 20% or less in terms of the number, and D 50 the particle diameter is 1 μm or less.
[0010] As described above, according to the dielectric composition disclosed herein, coarsening of the dielectric particles can be suppressed. As a result, D50 Dielectric components can be manufactured in which the particle diameter is 1 μm or less, and the proportion of coarse particles larger than 1 μm is 20 percent or less. Since defects such as a decrease in the number of dielectric particles stacked in the thickness direction are suppressed, thinning can be achieved while maintaining high reliability. In this specification, "dielectric component" refers to a plate-shaped component used in the dielectric layer of an MLCC. [Brief explanation of the drawing]
[0011] [Figure 1] This graph illustrates the effect of rare earth elements on the firing behavior of dielectric particles. [Figure 2] This is an SEM image (20,000x magnification) of Sample 1 after firing. [Figure 3] This is an SEM image (20,000x magnification) of sample 3 after firing. [Modes for carrying out the invention]
[0012] Preferred embodiments of the technology disclosed herein will be described below. Matters other than those specifically mentioned herein that are necessary for carrying out the technology disclosed herein (such as detailed methods for preparing dielectric compositions) can be carried out based on the common technical knowledge of those skilled in the art to which the technology disclosed herein belongs.
[0013] [Dielectric composition] First, the dielectric compositions disclosed herein will be described. The term "dielectric composition" as used herein is not limited to any particular embodiment. For example, the dielectric compositions disclosed herein include granulated powders, pastes, green sheets, and the like.
[0014] The dielectric composition disclosed herein comprises a main component composed of dielectric particles and a secondary component. The secondary component comprises the following elements, with the total moles of the main component being 100 mol%: Mn 0.8 mol%~2.5 mol%; Al 0.3 mol%~0.9 mol%; Ca 0.1 mol%~0.4 mol%; Rare earth elements 0.7mol%~2.5mol% It contains the following, and the Si content is 0.2 mol% or less. The components within the dielectric composition will be described in detail below.
[0015] 1. Main component The main component of the dielectric composition is dielectric particles. Conventional insulating materials that can be used in the dielectric layer of MLCCs can be used without particular limitation as dielectric particles. An example of such dielectric particles is a perovskite-type metal oxide. Examples of these perovskite-type metal oxides include BaTiO3, (CaSr)(TiZr)O3, (BaCaSr)(TiZr)O3, (BaSr)(TiZr)O3, SrTiO3, CaTiO3, CaZrO3, and Ba(ZrTi)O3.
[0016] Among the perovskite-type metal oxides mentioned above, (CaSr)(TiZr)O3(CSTZ) is particularly suitable as a main component of dielectric compositions because it exhibits small changes in capacitance with temperature and possesses the C0G characteristics defined by the EIA (Electronic Industries Alliance Standard). The compositional formula for CSTZ is ((Ca x Sr 1-x ) m (Ti y Zr 1-y)In (O3), the ratio x of Ca to Sr is preferably 0.5 or more, more preferably 0.55 or more, still more preferably 0.6 or more, and particularly preferably 0.65 or more. On the other hand, the upper limit value of the ratio x of Ca to Sr is preferably 1 or less, more preferably less than 1, still more preferably 0.95 or less, and particularly preferably 0.9 or less. Further, the ratio y of Ti to Zr is preferably 0 or more, more preferably 0.01 or more, still more preferably 0.02 or more, and particularly preferably 0.03 or more. On the other hand, the upper limit value of the ratio y of Ti to Zr is preferably 0.1 or less, more preferably 0.09 or less, still more preferably 0.08 or less, and particularly preferably 0.07 or less. Also, m in the formula is preferably 0.8 or more, more preferably 0.9 or more, and preferably 1 or more. On the other hand, the upper limit value of m in the formula is preferably 1.3 or less, more preferably 1.2 or less, still more preferably 1.1 or less, and particularly preferably 1.05 or less. CSTZ of the above composition is particularly suitable as the main component of the dielectric composition from the viewpoint of C0G characteristics.
[0017] Also, the D of the dielectric particles in the dielectric composition 50 The particle size is preferably 1.0 μm or less, more preferably 0.8 μm or less, and particularly preferably 0.7 μm or less. Thereby, it can contribute to the miniaturization of the dielectric particles after firing. However, if the dielectric particles before firing are made too small, there is also a risk that the coarsening of the dielectric particles after firing will be promoted due to the aggregation of the particles. From such a viewpoint, the lower limit value of the D 50 The particle size of the dielectric particles is preferably 0.05 μm or more, more preferably 0.1 μm or more, and particularly preferably 0.2 μm or more. In addition, the "D 50 Particle size" in this specification is the integrated 50% particle size in the number-based particle size distribution of the equivalent circle area diameter (Heywood diameter) obtained from the image taken using a scanning electron microscope (SEM: Scanning Electron Microscope).
[0018] 2. Sub-components The auxiliary components of the dielectric composition disclosed herein contain at least Mn, Al, Ca, and rare earth elements. These auxiliary components can control the sintering behavior of the dielectric particles (main components). The auxiliary components of the dielectric composition disclosed herein will be described below.
[0019] (1) Manganese (Mn) Mn functions as a sintering aid to improve the density of the dielectric layer after firing by promoting the sintering of dielectric particles during firing. Mn also has the effect of imparting reduction resistance to the dielectric layer after firing. The state of Mn within the dielectric composition is not particularly limited. For example, Mn can be used in the form of metallic compounds such as oxides (MnO, Mn3O4, MnO2, etc.), hydroxides (Mn(OH)2), and carbonates (MnCO3). Furthermore, the minor components of the dielectric composition disclosed herein may be composite materials (composite oxides, etc.) containing Mn, Al, Ca, and rare earth elements. Of the above states, Mn oxide is particularly preferred considering stability during firing.
[0020] The Mn content is set to 0.8 mol% or more (preferably 0.9 mol% or more, more preferably 1 mol% or more, even more preferably 1.1 mol% or more, and especially preferably 1.2 mol% or more). This sufficiently improves the density and reduction resistance of the dielectric layer after firing. On the other hand, if the Mn content is too high, there is a risk that the grain growth of the dielectric particles will be excessively promoted. From this viewpoint, the Mn content is set to 2.5 mol% or less (preferably 2.4 mol% or less, more preferably 2.3 mol% or less, even more preferably 2.2 mol% or less, and especially preferably 2 mol% or less). In this specification, "content of minor components" refers to the molar ratio of the total number of moles of the main component (dielectric particles) to 100 mol%.
[0021] (2) Aluminum (Al) Al functions as a sintering aid with a superior density-enhancing effect compared to Mn, as described above. In other words, by adding both Mn and Al as sintering aids, a dielectric layer with an excellent balance of density and reduction resistance can be formed. The state of Al within the dielectric composition is not particularly limited. For example, Al can be used in the form of metallic compounds such as oxides (Al2O3, etc.), hydroxides (Al(OH)3), and carbonates (Al2(CO3)3). Of the above states, Al oxide is particularly preferred considering stability during firing.
[0022] The Al content is set to 0.3 mol% or more (preferably 0.32 mol% or more, and particularly preferably 0.4 mol% or more). This allows for a more favorable improvement in the density of the dielectric layer after firing. On the other hand, the upper limit of the Al content is set to 0.9 mol% or less (preferably 0.8 mol% or less, more preferably 0.7 mol% or less, even more preferably 0.6 mol% or less, and particularly preferably 0.5 mol% or less). This suppresses excessive grain growth of dielectric particles and contributes to the miniaturization of dielectric particles after firing.
[0023] (3) Calcium (Ca) Ca functions as a sintering inhibitor, suppressing grain growth of dielectric particles. In other words, by adding Ca, the particle size of dielectric particles after firing can be reduced. The state of Ca within the dielectric composition is not particularly limited. For example, Ca can be used in the form of metallic compounds such as Ca oxides (CaO, etc.), hydroxides (Ca(OH)2), and carbonates (CaCO3). Of the above states, Ca oxide is particularly preferred considering stability during firing.
[0024] The Ca content is set to 0.1 mol% or more (preferably 0.11 mol% or more, more preferably 0.12 mol% or more, even more preferably 0.15 mol% or more, and especially preferably 0.16 mol% or more). This allows the particle size of the dielectric particles after firing to be sufficiently small. On the other hand, if a large amount of Ca is present during firing, there is a risk of density reduction due to sintering defects. From this viewpoint, the Ca content is set to 0.4 mol% or less (preferably 0.38 mol% or less, more preferably 0.36 mol% or less, even more preferably 0.35 mol% or less, and especially preferably 0.33 mol% or less).
[0025] (4) Rare earth elements The inventors have discovered that rare earth elements have the function of slowing down the sintering rate of dielectric particles (see Figure 1). This function of rare earth elements makes it possible to suppress uneven sintering of dielectric particles. In other words, by adding both Ca and rare earth elements as sintering inhibitors, the particle size of multiple dielectric particles can be made smaller overall, while preventing the generation of locally coarse particles. As a result, the coarsening of dielectric particles can be sufficiently suppressed. The specific rare earth elements are not particularly limited and can be selected without restriction from among scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Among these, Y is particularly suitable for preventing uneven sintering of dielectric particles. The state of the rare earth elements within the dielectric composition is also not particularly limited. For example, rare earth elements can be used in the form of metal compounds such as oxides, hydroxides, and carbonates. Considering stability during firing, among the above states, Y oxide is particularly preferred.
[0026] Furthermore, the content of rare earth elements is set to 0.7 mol% or more (preferably 0.71 mol% or more, more preferably 0.8 mol% or more, even more preferably 0.9 mol% or more, and especially preferably 1 mol% or more). This appropriately suppresses uneven sintering of dielectric particles. On the other hand, if the content of rare earth elements becomes too high, there is a risk of sintering defects in the dielectric particles. From this viewpoint, the content of rare earth elements is set to 2.5 mol% or less (preferably 2.4 mol% or less, more preferably 2.3 mol% or less, even more preferably 2.2 mol% or less, and especially preferably 2.14 mol% or less).
[0027] (5) Silicon (Si) Furthermore, in the dielectric compositions disclosed herein, the Si content is limited to 0.2 mol% or less. This is because if a large amount of Si oxide (SiO2) is present in the dielectric composition during firing, abnormal grain growth of dielectric particles is promoted, and the miniaturization of dielectric particles is significantly inhibited. From the viewpoint of more reliably suppressing abnormal grain growth, the Si content relative to the main component is preferably 0.15 mol% or less, more preferably 0.1 mol% or less, even more preferably 0.05 mol% or less, and particularly preferably 0.01 mol% or less. On the other hand, the lower limit of the Si content is not particularly limited and may be 0 mol% (i.e., no Si). Also, as mentioned above, if a large amount of SiO2 is generated during firing, abnormal grain growth of dielectric particles is promoted. For this reason, the state of Si in the dielectric composition before firing is not particularly limited, as long as it is oxidized to SiO2 during firing. That is, in the dielectric compositions disclosed herein, the Si element content is limited to 0.2 mol% or less, regardless of whether it is in the state of elemental metal, oxide, hydroxide, or carbonate.
[0028] (6) Other elements The auxiliary components of the dielectric composition may include inorganic elements other than the four elements described herein, as long as they do not significantly impede the effects of the techniques disclosed herein. Examples of these other elements include Mg, Sr, V, B, and Li. The molar ratio of other elements to the total number of moles of the main components is preferably 2.0 mol% or less, more preferably 1.0 mol% or less, and particularly preferably 0.5 mol% or less. This prevents the functions of the four elements described above from being impaired. The molar ratio of other elements may also be 0 mol% (i.e., no other elements are included). This reliably prevents the functions of the four elements described above from being impaired.
[0029] Furthermore, the dielectric compositions disclosed herein preferably have a Ba content limited to a certain level or less. For example, the Ba content relative to the main component is preferably 0.5 mol% or less (preferably 0.4 mol% or less, more preferably 0.3 mol% or less, even more preferably 0.2 mol% or less, and particularly preferably 0.1 mol% or less). On the other hand, the lower limit of the Ba content is not particularly limited and may be 0 mol% (i.e., no Ba).
[0030] 3. Other additives As described above, the dielectric compositions disclosed herein encompass various forms such as granulated powder, paste, and green sheet. Therefore, the dielectric compositions disclosed herein can be appropriately modified to include necessary additives depending on the form of use. For example, the dielectric composition may contain a dispersion medium for dispersing the main component and minor components, and a binder resin soluble in the dispersion medium. This allows for the preparation of a paste-like dielectric composition. Furthermore, solid dielectric compositions such as green sheets and granulated powder can be molded using this paste-like dielectric composition. The dielectric composition may also contain other optional components as needed. Examples of such optional components include plasticizers, dispersants, defoamers, and wetting agents. Note that other additives can be conventionally known materials that can be used in dielectric compositions without particular limitation, and do not limit the technology disclosed herein, so a detailed explanation is omitted.
[0031] 4.Applications The dielectric composition disclosed herein has been described above. This dielectric composition is formed into a plate-like body of a predetermined thickness and then fired. The dielectric composition disclosed herein contains Mn and Al as minor components, so that a dielectric layer with an excellent balance of density and reduction resistance can be formed. On the other hand, Mn and Al may promote grain growth of dielectric particles. In contrast, the dielectric composition disclosed herein contains an appropriate amount of Ca as a minor component. This makes it possible to suppress the particle size of the dielectric particles after firing to a certain level or less. In addition, the dielectric composition disclosed herein contains rare earth elements as minor components. This slows down the sintering rate of the dielectric particles, so that the generation of localized coarse particles due to uneven firing can be prevented. Furthermore, in the dielectric composition disclosed herein, the content of Si, which promotes abnormal grain growth of dielectric particles, is limited to 0.2 mol% or less. As described above, the dielectric composition disclosed herein makes it possible to form a high-density dielectric layer while suppressing the coarsening of dielectric particles. As a result, it is possible to thin the dielectric layer while maintaining a sufficient relative permittivity.
[0032] [Dielectric components] Next, the dielectric component after firing will be described. The dielectric component disclosed herein includes a main component composed of dielectric particles and a secondary component. The secondary component, when the total number of moles of the main component is 100 mol%, contains the following elements: Mn 0.8 mol%~2.5 mol%; Al 0.3 mol%~0.9 mol%; Ca 0.1 mol%~0.4 mol%; Rare earth elements 0.7mol%~2.5mol% It includes these components. Since these components have already been explained, we will omit further explanation.
[0033] As described above, using the dielectric composition disclosed herein can suppress excessive particle growth of dielectric particles during firing. As a result, the content of coarse particles (dielectric particles with a particle diameter of 1 μm or more) in the dielectric component after firing is reduced. Specifically, in the particle size distribution based on the number of particles observed by SEM, when the total number of dielectric particles is set to 100 percent, the number of dielectric particles of 1 μm or more is 20 percent or less (preferably 18 percent or less, more preferably 17 percent or less, and especially preferably 15 percent or less). Dielectric components with a small amount of coarse particles have a sufficient number of dielectric particles in the thickness direction, and therefore can maintain high reliability even when thinned. The lower limit of the coarse particle content is not particularly limited and may be 0 percent or more (i.e., no dielectric particles of 1 μm or more exist), 1 percent or more, 2 percent or more, or 4 percent or more.
[0034] Next, in the dielectric composition disclosed herein, the D of the dielectric particles after firing 50 The particle size is 1.0 μm or less (preferably 0.8 μm or less, more preferably 0.7 μm or less). This enables thinning of dielectric components while maintaining more favorable reliability. Furthermore, the D of the dielectric particles after firing... 50 The lower limit of particle size is not particularly limited and may be 0.1 μm or larger, 0.2 μm or larger, or 0.5 μm or larger.
[0035] Furthermore, the D of the dielectric particles after firing 90 The particle size is preferably 1.2 μm or less (more preferably 1.15 μm or less, and particularly preferably 1.1 μm or less). This allows for thinner dielectric components while maintaining even better reliability. Also, the D of the dielectric particles 90 The lower limit of particle size is not particularly limited and may be 0.8 μm or larger, 0.9 μm or larger, or 0.95 μm or larger. 90 "Particle size" refers to the 90% cumulative particle size based on the number of particles in the particle size distribution observed by SEM.
[0036] Furthermore, the D of the dielectric particles after firing 10The particle size is preferably 0.4 μm or less (more preferably 0.35 μm or less). This allows for thinner dielectric components while maintaining even better reliability. Also, the D of the dielectric particles 10 The lower limit of particle size is not particularly limited and may be 0.05 μm or larger, 0.1 μm or larger, or 0.2 μm or larger. Note that "D" in this specification refers to 10 "Particle size" refers to the cumulative 10% particle size based on the number of particles in the particle size distribution observed by SEM.
[0037] In addition, the dielectric component disclosed herein preferably has a density above a certain level. This allows it to exhibit excellent relative permittivity. Specifically, the density of the dielectric component is 4.8 g / cm³. 3 The above is preferable, 4.81 g / cm³ 3 The above is more preferable, 4.82 g / cm³ 3 The above is even more preferable, 4.83 g / cm³ 3 The above is particularly preferable. By using these high-density dielectric components, MLCCs with excellent dielectric constant can be constructed. On the other hand, the upper limit of the density of the dielectric components is not particularly limited, and is 6 g / cm³. 3 The following is also acceptable: 5.5 g / cm³ 3 The following is also acceptable: 5 g / cm³ 3 The following is also acceptable.
[0038] Furthermore, the open porosity of the dielectric component disclosed herein is preferably 20% or less, more preferably 15% or less, even more preferably 10% or less, and particularly preferably 9.5% or less. This further improves the relative permittivity of the MLCC. On the other hand, the lower limit of the open porosity of the dielectric component is not particularly limited and may be 0.1% or more, 1% or more, 2% or more, or 3% or more. Note that "open porosity" in this specification is measured in accordance with JIS R 1634.
[0039] Furthermore, the hardness of the dielectric components disclosed herein is preferably 800 Hv or higher, more preferably 820 Hv or higher, even more preferably 840 Hv or higher, and particularly preferably 850 Hv or higher. When dielectric components are manufactured using the dielectric composition disclosed herein, the grain boundaries of the dielectric particles after firing increase, which suppresses minute chipping and cracking. As a result, high-strength dielectric components of 800 Hv or higher can be realized. The upper limit of the hardness of the dielectric components is not particularly limited and may be 1000 Hv or lower, 950 Hv or lower, or 900 Hv or lower. In this specification, "hardness" refers to Vickers hardness.
[0040] The dielectric component disclosed herein has been described above. This dielectric component can be used as a dielectric layer in an MLCC. Specifically, an MLCC can be manufactured by alternately stacking the dielectric component and an internal electrode layer. Here, because the coarsening of dielectric particles is suppressed in this dielectric component, a sufficient number of dielectric particles exist in the thickness direction even when the layer is thinned. Therefore, according to the technology disclosed herein, it is possible to further thin the dielectric layer while maintaining high reliability. More specifically, according to the technology disclosed herein, it is possible to construct an MLCC having an extremely thin dielectric layer of 5.0 μm or less (preferably 4.0 μm or less, more preferably 3.0 μm or less, even more preferably 2.5 μm or less, and particularly preferably 2.0 μm or less).
[0041] [Example Test] The following describes test examples relating to the technology disclosed herein. However, the following description is not intended to limit the technology disclosed herein to those shown in the test examples.
[0042] 1. Preparation of dielectric composition In this test, first, the dielectric particles ((Ca), which are the main components of the dielectric composition, are tested. 0.7 Sr 0.3 )(Zr 0.97 Ti 0.03A dielectric material (O3) was prepared. Specifically, strontium carbonate (SrCO3), calcium carbonate (CaCO3), zirconium oxide (ZrO2), and titanium oxide (TiO2) were mixed in a ratio that yielded dielectric particles of the above composition. Dielectric particles were then obtained by calcining this mixed material after drying. A wet method using a ball mill was employed for mixing each raw material. The calcination conditions were adjusted so that the average particle size of the dielectric particles after preparation was in the range of 0.2 to 0.5 μm.
[0043] Next, in this experiment, twelve types of auxiliary components were prepared by combining Y, Al, Ca, Mn, and Si. Specifically, each oxide (Y2O3, Al2O3, CaCO3, Mn3O4, SiO2) was prepared and mixed in the proportions shown in Table 1 to generate the auxiliary components. Then, twelve types of dielectric compositions (Samples 1-12) were prepared by mixing the above-mentioned main components and auxiliary components and drying them.
[0044] 2. Evaluation Test (1) Preparation of evaluation samples Granulated powder was obtained by mixing the dielectric composition of each sample with a dispersion (10 wt% polyvinyl alcohol aqueous solution) in a mortar. The mixing ratio of the dispersion to the dielectric composition was set to 20:100. The resulting granulated powder was sized by passing it through a 250 μm sieve. Next, the granulated powder was filled into a disc-shaped mold and press-molded at a pressure of approximately 0.80 MPa to obtain a molded body. Then, a disc-shaped dielectric component was obtained by firing this molded body in a reducing atmosphere. The heating rate during firing was set to 300 °C / h, the holding temperature to 1260 °C, and the holding time to 2 hours.
[0045] (2) Density For density measurement, a 20 mm diameter disc-shaped dielectric component was fabricated according to the procedure described above. The density of the dielectric component (g / cm³) was then measured based on the Archimedes method. 3 The following measurements were taken. The measurement results are shown in Table 1.
[0046] (3) Open porosity Similar to the "density" measurement described above, a 20 mm diameter disc-shaped dielectric component was fabricated. The open porosity of this dielectric component was then measured according to JIS R 1634. The measurement results are shown in Table 1.
[0047] (4)Hardness In this test, a 20mm diameter disc-shaped dielectric component was fabricated. The surface of the dielectric component was polished, and its hardness was measured using a Vickers hardness tester. The measurement conditions were a load of 1kgf and a holding time of 15s. The measurement results are shown in Table 1.
[0048] (5) Relative permittivity In this test, a 7mm diameter disc-shaped dielectric component was fabricated. Test samples were then prepared by coating both sides of the dielectric component with silver (Ag) to form a pair of electrodes. The capacitance of the test samples was measured using an LCR meter. The frequency for capacitance measurement was set to 1MHz, the voltage to 1V, and the room temperature to 25°C. The relative permittivity of each sample was calculated based on the capacitance measurement results, the thickness of the dielectric component, and the effective electrode area. The calculation results are shown in Table 1.
[0049] (6) Particle size distribution of dielectric particles Similar to the measurement of "relative permittivity" described above, a disc-shaped dielectric component with a diameter of 7 mm was fabricated. The surface of the dielectric component was then observed using a scanning electron microscope. As an example of the observation results, an SEM image of sample 1 (20,000x magnification) is shown in Figure 2, and an SEM image of sample 3 (20,000x magnification) is shown in Figure 3. Next, the SEM images of each sample were analyzed using image analysis particle size distribution software (Mac-view, manufactured by Mounttech) to create the particle size distribution of the dielectric particles after firing. In this analysis of the SEM images, the particle size distribution based on the number of particles in the circle area equivalent diameter (Heywood diameter) was obtained by tracing the contour of all particles present in the image from the edge in order and counting them. Based on this particle size distribution, the "percentage of particles less than 0.4 μm", "percentage of particles between 0.4 μm and 0.6 μm", "percentage of particles between 0.6 μm and 1.0 μm", "percentage of particles larger than 1.0 μm", and "D 10 "Particle size" and "D50 "Particle size" and "D 90 The particle size was calculated. The calculation results are shown in Table 1.
[0050] [Table 1]
[0051] First, as shown in Table 1, samples 3-5, 9, and 12 had a concentration of 4.8 g / cm³. 3 Maintaining a high density of above, D 50 Miniaturization of dielectric particles to a particle size of 1.0 μm or less was achieved (see Figure 3).
[0052] On the other hand, in samples 1 and 2, the dielectric particles became extremely large (see Figure 2). This is thought to be because they contained a large amount of Si, which promotes abnormal grain growth of dielectric particles. Coarsening of dielectric particles was also observed in samples 6, 7, 10, and 11. In sample 6, where the amount of rare earth element (Y) added was insufficient, it is presumed that localized grain growth occurred due to uneven sintering. In sample 7, where Al was added in excess, it is presumed that overall grain growth was promoted. In sample 10, it is presumed that the amount of Ca added was insufficient, resulting in insufficient suppression of grain growth. In sample 11, where Mn was added in excess, it is presumed that overall grain growth was promoted. Finally, in sample 8, a firing defect occurred as a result of insufficient Al addition.
[0053] From these results, it was found that by mixing Mn, Al, Ca, and rare earth elements in appropriate ratios, as in samples 3-5, 9, and 12, it is possible to suppress the coarsening of dielectric particles after sintering while maintaining high density.
[0054] The technologies disclosed herein have been described in detail above, but these are merely illustrative examples and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. Furthermore, the technologies disclosed herein encompass the forms described in the following sections.
[0055] <Item 1> It comprises a main component composed of dielectric particles and a secondary component, The aforementioned minor components, when the total number of moles of the aforementioned major components is 100 mol%, consist of the following elements: Mn 0.8 mol%~2.5 mol%; Al 0.3 mol%~0.9 mol%; Ca 0.1 mol%~0.4 mol%; Rare earth elements 0.7mol%~2.5mol% A dielectric composition comprising the above, wherein the Si content is 0.2 mol% or less.
[0056] <Item 2> The dielectric particles are (Ca x Sr 1-x ) m (Ti y Zr 1-y )O3 The dielectric composition described in item 1, which is a metal oxide having a perovskite structure represented by (wherein x in the above formula is between 0.5 and 1, y is between 0 and 0.1, and m is between 1.0 and 1.05).
[0057] <Item 3> D of the dielectric particles based on SEM observation 50 A dielectric composition according to item 1 or 2, wherein the particle size is 0.05 μm or more and 0.5 μm or less.
[0058] <Item 4> It comprises a main component composed of dielectric particles and a secondary component, The aforementioned minor components, when the total number of moles of the aforementioned major components is 100 mol%, consist of the following elements: Mn 0.8 mol%~2.5 mol%; Al 0.3 mol%~0.9 mol%; Ca 0.1 mol%~0.4 mol%; Rare earth elements 0.7mol%~2.5mol% including, and, In the particle size distribution based on the number of dielectric particles observed by SEM, the proportion of dielectric particles with a particle diameter of 1 μm or more is 20 percent or less, and D 50 Dielectric components with a particle size of 1 μm or less.
[0059] <Item 5> Density is 4.8 g / cm³ 3 More than 6g / cm 3 The dielectric components listed in item 4 are as follows:
[0060] <Item 6> A dielectric component as described in item 4 or 5, having an open porosity of 10% or less according to JIS R 1634.
[0061] <Item 7> A dielectric component as described in any one of items 4 to 6, having a Vickers hardness of 800 Hv or higher.
Claims
1. It comprises a main component composed of dielectric particles and a secondary component, The aforementioned minor components, when the total number of moles of the aforementioned major components is 100 mol%, consist of the following elements: Mn 0.8 mol% to 2.5 mol%; Al 0.3 mol% to 0.9 mol%; Ca 0.1 mol% to 0.4 mol%; Rare earth elements 0.7 mol% to 2.5 mol% A dielectric composition comprising the above, wherein the Si content is 0.2 mol% or less.
2. The dielectric particles are (Ca ｘ Sr １－ｘ ) ｍ (Ti ｙ Zr １－ｙ )O ３ The dielectric composition according to claim 1, wherein the metal oxide has a perovskite structure represented by the formula above (wherein x is 0.5 or more and 1 or less, y is 0 or more and 0.1 or less, and m is 1.0 or more and 1.05 or less).
3. D of the dielectric particles based on SEM observation ５０ The dielectric composition according to claim 1 or 2, wherein the particle size is 0.05 μm or more and 0.5 μm or less.
4. It comprises a main component composed of dielectric particles and a secondary component, The aforementioned minor components, when the total number of moles of the aforementioned major components is 100 mol%, consist of the following elements: Mn 0.8 mol% to 2.5 mol%; Al 0.3 mol% to 0.9 mol%; Ca 0.1 mol% to 0.4 mol%; Rare earth elements 0.7 mol% to 2.5 mol% including, and, In the particle size distribution based on the number of dielectric particles observed by SEM, the proportion of dielectric particles with a particle diameter of 1 μm or more is 20 percent or less, and D ５０ Dielectric components with a particle size of 1 μm or less.
5. A density of 4.8 g / cm ３ or more and 6 g / cm ３ or less. The dielectric component according to claim 4.
6. A dielectric component according to claim 4 or 5, wherein the open porosity is 10% or less in accordance with JIS R 1634.
7. A dielectric component according to claim 4 or 5, having a Vickers hardness of 800 Hv or more.