Multilayer ceramic electronic components and methods for manufacturing the same

Abstract

To provide multilayer ceramic electronic components that are highly reliable and have a suitable dielectric constant. [Solution] A multilayer ceramic electronic component having an element body in which a dielectric layer and an internal electrode layer are stacked. The dielectric layer is of general formula A 1 B 1 O3(A 1 is at least one selected from Ca and Sr and Ba, or Ba alone, and B 1 The material contains dielectric particles that have a main component represented by Ti and Zr, or Ti alone. In a cross-section parallel to the stacking direction, at least a portion of the dielectric particles are electrode contact particles that are in contact with the internal electrode layer, at least a portion of the dielectric particles are pore-containing particles that contain pores, and the number ratio of particles that are electrode contact particles and pore-containing particles to the electrode contact particles is 0.1% or more and 15.0% or less.

Description

[Technical Field]

[0001] This invention relates to multilayer ceramic electronic components and methods for manufacturing the same. [Background technology]

[0002] Patent Document 1 describes an invention relating to a multilayer ceramic capacitor. By having a dielectric layer composed of barium titanate-based crystalline particles having pores within the crystalline particles, it is possible to provide a multilayer ceramic capacitor that exhibits excellent reliability in high-temperature load tests even when the dielectric layer is thinned. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2007 / 074731 [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention aims to provide a multilayer ceramic electronic component with high reliability and a suitable dielectric constant, as well as a method for manufacturing the same. [Means for solving the problem]

[0005] To achieve the above objective, the multilayer ceramic electronic component according to the present invention is A multilayer ceramic electronic component having an element body in which a dielectric layer and an internal electrode layer are stacked, The dielectric layer is, General formula A 1 B 1 O3(A 1 is at least one selected from Ca and Sr and Ba, or Ba alone, and B 1 It contains dielectric particles that include the main components represented by Ti and Zr, or Ti alone. In a cross-section parallel to the lamination direction, at least a part of the dielectric particles is electrode-contact particles that contact the internal electrode layer, and at least a part of the dielectric particles is pore-containing particles that contain pores. The number ratio of the particles that are the electrode-contact particles and also the pore-containing particles with respect to the electrode-contact particles is 0.1% or more and 15.0% or less.

[0006] The thickness of the dielectric layer may be 1 μm or less, and the number of layers of the dielectric layer may be 100 layers or more.

[0007] In a cross-section parallel to the lamination direction, at least a part of the dielectric particles may be electrode-noncontact particles that do not contact the internal electrode layer. The number ratio of the particles that are the electrode-noncontact particles and also the pore-containing particles with respect to the electrode-noncontact particles may be 0.1% or more and 15% or less.

[0008] The internal electrode layer may contain a main component represented by the general formula A 2 B 2 O3 (A 2 is at least one selected from Ca and Sr and Ba, or Ba alone, and B 2 is Ti and Zr, or Ti alone).

[0009] A <00000 or more and 15% or less.

[0008] The internal electrode layer may contain a main component represented by the general formula A 2 B 2 O3 (A 2 is at least one selected from Ca and Sr and Ba, or Ba alone, and B 2 is Ti and Zr, or Ti alone). <00001 or more and 15% or less.

[0008] The internal electrode layer may contain a main component represented by the general formula A 2 B 2 O3 (A 2 is at least one selected from Ca and Sr and Ba, or Ba alone, and B 2 is Ti and Zr, or Ti alone).

[0009] A 2 B [[ID=The manufacturing method of the multilayer ceramic electronic component according to the present invention is a manufacturing method of a multilayer ceramic electronic component having a step of forming an internal electrode layer on a ceramic green sheet using a paste for the internal electrode layer, The paste for the internal electrode layer contains metal powder and a co-material. The aforementioned common material is General Formula A 2 B 2 O3(A 2 is at least one selected from Ca and Sr and Ba, or Ba alone, and B 2 These are dielectric particles represented by Ti and Zr, or Ti alone. At least a portion of the dielectric particles are pore-containing dielectric particles, and the number ratio of the pore-containing dielectric particles to the dielectric particles is 1.0% or more and 40% or less. The ratio of the common material to 100 parts by weight of the metal powder is 8 parts by weight or more and 20 parts by weight or less.

[0012] A 2 B 2 O3 may also be BaTiO3. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a cross-sectional view of a multilayer ceramic capacitor according to one embodiment of the present invention. [Figure 2] Figure 2 is an enlarged schematic cross-sectional view of the main part of Figure 1. [Modes for carrying out the invention]

[0014] The present invention will be described below based on the embodiments shown in the drawings.

[0015] Multilayer ceramic capacitor 1 As shown in Figure 1, a multilayer ceramic capacitor 1, which is a type of multilayer ceramic electronic component according to one embodiment of the present invention, has a capacitor element body 10 in which dielectric layers 2 and internal electrode layers 3 are alternately stacked. The internal electrode layers 3 are stacked so that each end face is alternately exposed on the surface of opposing ends of the capacitor element body 10. A pair of external electrodes 4 are formed at both ends of the capacitor element body 10 and are connected to the exposed end faces of the alternately arranged internal electrode layers 3 to form a capacitor circuit.

[0016] There are no particular restrictions on the shape of the capacitor element body 10, but as shown in Figure 1, it is usually rectangular. There are also no particular restrictions on its dimensions; it can be set to an appropriate size depending on the application.

[0017] Dielectric layer 2 The dielectric layer 2 is based on general formula A 1 B 1 O3(A 1 is at least one selected from Ca and Sr and Ba, or Ba alone, and B 1 The material contains dielectric particles that include main components represented by Ti and Zr, or Ti alone.

[0018] The dielectric particles may contain components other than the main component. Examples of components other than the main component include various oxides. The above-mentioned oxides may be simple oxides or composite oxides. There are no particular restrictions on the content ratio of components other than the main component in the dielectric particles, and it may be within a range that does not significantly affect the performance of the multilayer ceramic capacitor 1. For example, it may be between 0 wt% and 5 wt%.

[0019] The main component mentioned above may also be BaTiO3. That is, A 1 and B 1 This may be a combination of Ba alone or Ti alone. Note that BaTiO3 has the composition formula Ba m TiO 2+m This includes compounds represented by the formula, where m is 0.995 ≤ m ≤ 1.010.

[0020] There are no particular restrictions on the thickness of dielectric layer 2. The thickness (interlayer thickness) of dielectric layer 2 may be 1 μm or less, or it may be between 0.4 μm and 1 μm. There are no particular restrictions on the number of dielectric layers 2 stacked. It may be 100 layers or more, or it may be between 100 and 1000 layers.

[0021] Internal electrode layer 3 The conductive material contained in the internal electrode layer 3 is not particularly limited. Since the constituent material of the dielectric layer 2 is reduction-resistant, a relatively inexpensive base metal material can be used as the conductive material. The base metal material used as the conductive material may be Ni or a Ni alloy. The Ni alloy may be an alloy of Ni with one or more elements selected from Mn, Cr, Co, Cu, Sn, and Al. The Ni content in the Ni alloy may be 95% by weight or more. In addition, various trace components such as P may be contained in the base metal material in amounts of about 0.1% by weight or less each.

[0022] There are no particular restrictions on the thickness of the internal electrode layer 3. The thickness of the internal electrode layer 3 (interlayer thickness) may be 1.0 μm or less, or it may be between 0.4 μm and 0.8 μm.

[0023] Microstructure of dielectric layer 2 and internal electrode layer 3 Figure 2 is a schematic cross-sectional view of the main part, enlarged to show the dielectric particles and internal electrode particles 3a.

[0024] As shown in Figure 2, dielectric particles are classified into electrode contact particles 2a that are in contact with the internal electrode layer and electrode non-contact particles 2b that are not in contact with the internal electrode layer.

[0025] A dielectric particle is considered an electrode contact particle 2a that is in contact with the internal electrode layer 3 if the minimum distance between the dielectric particle and the internal electrode particle (described later) is between 0 and 2 nm.

[0026] Some of the dielectric particles contain pores within them, making them pore-containing particles. The electrode contact particles 2a are further classified into pore-free particles 2a1 and pore-containing particles 2a2. The electrode non-contact particles 2b are further classified into pore-free particles 2b1 and pore-containing particles 2b2.

[0027] Furthermore, the number ratio of particles that are both electrode contact particles and pore-containing particles to the total number of electrode contact particles is 0.1% or more and 15.0% or less. That is, the number ratio of pore-containing particles 2a2 to electrode contact particles 2a is 0.1% or more and 15.0% or less. The above number ratio may also be 0.2% or more and 14.7% or less. To put it another way, the number ratio of pore-containing particles 2a2 to the total number of pore-free particles 2a1 and pore-containing particles 2a2 is 0.1% or more and 15.0% or less.

[0028] A highly reliable multilayer ceramic capacitor 1 is obtained when the ratio of electrode contact particles, which are also pore-containing particles, to the total number of electrode contact particles is within a predetermined range. If the above ratio is too small or too large, the reliability of the multilayer ceramic capacitor 1 decreases. Reliability can be evaluated by the time it takes for the insulation resistance to decrease in accelerated testing and the high-temperature load life.

[0029] If the above ratio of elements is too large, the relative permittivity tends to decrease. Along with the decrease in relative permittivity, the capacitance also tends to decrease.

[0030] If the above ratio of elements is too small, the relative permittivity tends to increase. As the relative permittivity increases, the DC bias characteristics tend to deteriorate and the effective capacitance tends to decrease. Therefore, a multilayer ceramic capacitor 1 with an excessively high relative permittivity is unsuitable for applications that require a small, high-capacitance multilayer ceramic capacitor.

[0031] There are no particular restrictions on the number ratio of non-contact electrode particles and pore-containing particles to the total number of non-contact electrode particles. It may be between 0.1% and 15.0%. The above number ratio may also be between 0.1% and 14.8%. In other words, the number ratio of pore-containing particles 2b2 to the total number of pore-free particles 2b1 and pore-containing particles 2b2 may be between 0.1% and 15.0%.

[0032] When the number ratio of non-contacting electrode particles and pore-containing particles to the number of non-contacting electrode particles is within a predetermined range, a highly reliable multilayer ceramic capacitor 1 is likely to be obtained. However, the number ratio of electrode-contacting particles and pore-containing particles to the number of electrode-contacting particles is of greater importance.

[0033] Generally, it is known that a factor causing a decrease in the insulation resistance of a multilayer ceramic capacitor 1 is the migration of oxygen ion defects (oxygen vacancies) toward the cathode under a high-temperature DC electric field, concentrating near the electrodes. For this reason, especially in electrode contact particles, if the proportion of pore-containing particles, which are defects of various constituent elements within the particles, is high, the insulation resistance tends to decrease, and reliability tends to decline.

[0034] The conductive material contained in the internal electrode layer 3 includes internal electrode particles 3a. The internal electrode particles 3a include the base metal material described above.

[0035] The internal electrode layer 3 contains internal electrode particles 3a, as well as general formula A 2 B 2 O3(A 2 is at least one selected from Ca and Sr and Ba, or Ba alone, and B 2 The electrode may also contain dielectric particles 3b that contain the main components represented by Ti and Zr, or Ti alone. 2 B 2 O3 is A 1 B 1 It may be substantially the same as O3. That is, A 1 and A 2 The agreement rate with B is 99% or higher, and 1 and B 2 The agreement rate with A may be 99% or higher. 2 B 2 O3 may also be BaTiO3.

[0036] The dielectric particles 3b within the electrode having the above composition are dielectric particles that function as a co-material. The internal electrode layer 3 may also contain other particles as needed. Examples include particles containing oxides such as yttrium oxide, ytterbium oxide, calcium oxide, barium oxide, and magnesium oxide.

[0037] External electrode 4 There are no particular restrictions on the conductive material contained in the external electrode 4. For example, well-known conductive materials such as Ni, Cu, Ni alloy, or Cu alloy can be used as the conductive material contained in the external electrode 4. There are no particular restrictions on the thickness of the external electrode 4, and it can be determined appropriately depending on the application. The thickness of the external electrode 4 is usually preferably about 5 to 50 μm.

[0038] Manufacturing method of multilayer ceramic capacitor 1 The multilayer ceramic capacitor 1 of this embodiment is manufactured in the same manner as conventional multilayer ceramic capacitors, except for a few points described later. Specifically, first, a green chip is made using a paste, such as a conventional method like printing or sheeting. Next, the green chip is fired. Then, the external electrodes are printed or transferred onto the fired green chip, and the external electrodes are fired again to manufacture the capacitor. The manufacturing method will be described in detail below. The following description will focus on the case where the main component of the dielectric layer is BaTiO3, but the method described below is also applicable when the main component of the dielectric layer is something other than BaTiO3.

[0039] First, prepare a dielectric powder containing relatively large dielectric particles as a dielectric material to be included in the dielectric layer paste described later. Separately, prepare a dielectric powder containing relatively small dielectric particles as a dielectric material to be included as a co-material in the internal electrode layer paste described later.

[0040] There are no particular restrictions on the intragranular pore ratio of the dielectric powder contained in the dielectric layer paste. For example, it may be 1.0% to 30%, or 1.0% to 24%.

[0041] In order to control the number ratio of electrode contact particles that are also pore-containing particles to the total number of electrode contact particles to be between 0.1% and 15.0%, it is necessary to include a co-material with a controlled intragranular pore ratio in the paste for the internal electrode layer. Specifically, as the co-material, general formula A 2 B 2 A dielectric powder containing dielectric particles represented by O3 is used. The intragranular pore ratio of the dielectric powder included in the paste for the internal electrode layer as a co-material (hereinafter sometimes simply referred to as the intragranular pore ratio of the co-material) is set to 1.0% or more and 40% or less.

[0042] Generally, methods for synthesizing dielectrics whose main component is BaTiO3 include the solid-phase method, the oxalate method, and the liquid-phase method. This explanation will focus on the liquid-phase method for synthesizing dielectrics whose main component is BaTiO3.

[0043] First, Ba(OH)2 and TiCl4 are mixed to obtain a mixture. Next, a hydrothermal reaction is carried out on the mixture to synthesize a dielectric powder containing dielectric particles whose main component is BaTiO3. The obtained BaTiO3 is washed with water and dried.

[0044] The temperature during the hydrothermal reaction should preferably be higher as the particle size of the dielectric powder after drying increases. Therefore, the temperature at which the dielectric powder contained in the dielectric layer paste is prepared is higher than the temperature at which the dielectric powder contained in the internal electrode layer paste is prepared.

[0045] In the conventional liquid-phase method, dielectric powder is obtained by the drying process described above.

[0046] However, when obtaining dielectric powder with small particle sizes to be incorporated into the paste for the internal electrode layer, the low temperature of the hydrothermal reaction results in a high proportion of pore-containing dielectric particles (hereinafter sometimes referred to as the intragranular pore ratio). Specifically, it becomes about 60%. Even when such dielectric powder is incorporated into the paste for the internal electrode layer as a co-material to manufacture a multilayer ceramic capacitor, it is not possible to keep the proportion of electrode contact particles that are also pore-containing particles below 15.0% of the total electrode contact particles.

[0047] The inventors have discovered that the intragranular pore ratio of a dried dielectric powder used as a co-material in the paste for the internal electrode layer can be reduced by further calcination. By incorporating dielectric powder with a reduced intragranular pore ratio through calcination as a co-material into the paste for the internal electrode layer to manufacture a multilayer ceramic capacitor, the inventors have found that the number ratio of particles that are both electrode contact particles and pore-containing particles relative to the electrode contact particles can be set to 0.1% or more and 15.0% or less. Furthermore, the content ratio of the co-material to 100 parts by weight of metal powder in the paste for the internal electrode layer can be set to 8 parts by weight or more and 20 parts by weight or less.

[0048] By keeping the composition of the co-material included in the paste for the internal electrode layer, the pore ratio within the particles of the co-material, and the content ratio of the co-material all within the above range, the number ratio of particles that are electrode contact particles and pore-containing particles relative to the electrode contact particles can be set to 0.1% or more and 15.0% or less.

[0049] Common material is general formula A 2 B 2 Even with dielectric powder containing dielectric particles represented by O3, if the pore ratio within the particles of the co-material is too low, the electrode contact particles tend to grow abnormally when the co-material diffuses from the internal electrode layer to the dielectric layer. Abnormal particle growth of the electrode contact particles is a factor that causes structural defects. Therefore, the reliability of the final multilayer ceramic capacitor tends to decrease. If the content ratio of the co-material in the paste for the internal electrode layer is too high, the number ratio of particles that are electrode contact particles and pore-containing particles to the number of electrode contact particles tends to become too high. If the content ratio of the co-material in the paste for the internal electrode layer is too low, the number ratio of particles that are electrode contact particles and pore-containing particles to the number of electrode contact particles tends to become too low.

[0050] Because dielectric powders used as co-materials have small particle sizes, it has been difficult to use dielectric powders obtained by conventional solid-phase methods as co-materials. The inventors have found that dielectric powders that can be used as co-materials can be produced by changing some conditions from the conventional solid-phase method. Specifically, they found that dielectric powders that can be used as co-materials can be obtained by grinding powders synthesized by a normal solid-phase method, or powders synthesized under the same conditions as a normal solid-phase method except that the synthesis temperature is lowered, to a particle size that can be used as a co-material. There are no particular restrictions on the particle size that can be used as a co-material, but it is preferably 50 nm or less.

[0051] Because dielectric powders used as co-materials have small particle sizes, it has been difficult to use dielectric powders obtained by conventional oxalate methods as co-materials. The inventors have found that by changing some conditions from the conventional oxalate method, dielectric powders that can be used as co-materials can be produced. Specifically, they found that dielectric powders that can be used as co-materials can be obtained by grinding powders synthesized by the normal oxalate method, or powders synthesized under the same conditions except that they are calcined at a lower temperature than the normal oxalate method, to a particle size that can be used as a co-material. There are no particular restrictions on the particle size that can be used as a co-material, but it is preferably 50 nm or less.

[0052] There are no particular restrictions on the method for preparing the dielectric layer paste. For example, it can be prepared by turning the above-mentioned dielectric powder into a paint. The dielectric layer paste may be an organic paint or a water-based paint.

[0053] In this embodiment, there are no particular restrictions on the BET specific surface area of ​​the dielectric powder. To meet the requirement for thinning the dielectric layer 2, 6.0 m is used. 2 It may be more than / g.

[0054] If the dielectric layer 2 contains components other than the main components described above, raw materials for those components are prepared. As with the components described above, simple oxides of those components, complex oxides of those components, or mixtures thereof can be used as raw materials. In addition, various compounds that become the simple oxides or complex oxides described above by firing can be used.

[0055] There are no particular restrictions on the average particle size of the dielectric powder used to prepare the dielectric layer paste; it is typically around 0.05 μm to 0.20 μm.

[0056] When using an organic paint as the paste for the dielectric layer, the organic paint is prepared by kneading the dielectric raw material with an organic vehicle. The organic vehicle is a binder dissolved in an organic solvent. There are no particular limitations on the type of binder. For example, it can be appropriately selected from various binders commonly used in this field, such as ethylcellulose and polyvinyl butyral. There are no particular limitations on the type of organic solvent. For example, it can be appropriately selected from various organic solvents such as terpineol, butyl carbitol, acetone, and toluene, depending on the method of preparing the green chip.

[0057] When using a water-based paint as the paste for the dielectric layer, the water-based paint is prepared by mixing the dielectric raw materials with a water-based vehicle. The water-based vehicle is a solution of a water-soluble binder and dispersant dissolved in water. There are no particular restrictions on the type of water-soluble binder. For example, it can be appropriately selected from various water-soluble binders commonly used in this field, such as polyvinyl alcohol, cellulose, and water-soluble acrylic resins.

[0058] The following describes the case where the dielectric layer paste is an organic paint.

[0059] The paste for the internal electrode layer is prepared by kneading together the above-mentioned conductive materials, or the above-mentioned oxides, organometallic compounds, resinates, etc., which become the above-mentioned conductive materials after firing, the above-mentioned organic vehicle, and the above-mentioned co-material.

[0060] The paste for the external electrode can be prepared using the same method as the paste for the internal electrode layer described above. However, the aforementioned co-materials may or may not be included.

[0061] There are no particular restrictions on the content of organic vehicles in each of the pastes described above. The content should be the same as that commonly used in this art. For example, the binder content in each paste should be approximately 1-5% by weight, and the solvent content approximately 10-50% by weight. Furthermore, each paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, etc., as needed. The total content of these additives in each paste is preferably 10% by weight or less.

[0062] When using a printing method to produce green chips, the dielectric layer paste and the internal electrode layer paste are printed and laminated onto a substrate such as PET, cut into a predetermined shape, and then peeled off from the substrate to obtain the green chips.

[0063] When using the sheet method to produce green chips, first, a green sheet is formed using a dielectric layer paste, and then an internal electrode layer paste is printed on the green sheet. Next, the green sheets with the printed internal electrode layer paste are stacked and cut into a predetermined shape to obtain the green chips.

[0064] Before firing, as described later, the green chips are subjected to a binder removal treatment. There are no particular restrictions on the binder removal conditions. The heating rate is preferably 5 to 300°C / hour, the holding temperature is preferably 180 to 900°C, and the temperature holding time is preferably 0.5 to 48 hours. In addition, the atmosphere during binder removal is preferably air or a reducing atmosphere.

[0065] The atmosphere during firing of the green chips is preferably a reducing atmosphere. As an atmospheric gas to create a reducing atmosphere, for example, a humidified mixture of N2 and H2 can be used. The oxygen partial pressure during firing can be appropriately determined depending on the type of conductive material in the paste for the internal electrode layer. When a base metal such as Ni or Ni alloy is used as the conductive material in the paste for the internal electrode layer, the oxygen partial pressure is preferably set to 10 -11 ~10 -8 Use MPa.

[0066] The heating rate during firing is preferably 10 k°C / hour or more and 500 k°C / hour. The slower the heating rate, the higher the proportion of pore-containing particles in the dielectric layer of the final multilayer ceramic capacitor tends to be.

[0067] The holding temperature during firing may be 1300°C or lower, or 1000 to 1300°C. The holding time during firing is preferably 0.2 to 8 hours, more preferably 0.2 to 3 hours. In particular, by keeping the holding temperature during firing within the above range, it becomes easier to sufficiently densify the dielectric layer 2 while preventing electrode breakage due to abnormal sintering of the internal electrode layer 3 and deterioration of dielectric properties due to excessive grain growth of dielectric particles. The cooling rate after firing may be, for example, 50 to 8000°C / hour.

[0068] After firing in a reducing atmosphere, the capacitor element body 10 may be subjected to annealing. Annealing is a process to re-oxidize the dielectric layer 2. Annealing makes it easier to extend the high-temperature load life of the multilayer ceramic capacitor 1.

[0069] The partial pressure of oxygen in the atmosphere during annealing is 10 -9 ~10 -5 It may also be expressed as MPa. Keeping the oxygen partial pressure within the above range makes it easier to sufficiently promote the re-oxidation of the dielectric layer 2 while preventing oxidation of the internal electrode layer 3.

[0070] The holding temperature during annealing may be 1100°C or lower, or it may be between 900°C and 1100°C. By keeping the holding temperature during annealing within this range, it becomes easier to sufficiently promote the re-oxidation of the dielectric layer 2 while preventing oxidation of the internal electrode layer 3. As a result, the insulation resistance and high-temperature load life of the multilayer ceramic capacitor 1 can be optimized.

[0071] Normally, annealing consists of a heating process, a temperature holding process, and a cooling process, but it may also consist only of a heating process and a cooling process. In other words, the temperature holding time may be set to 0. In this case, the holding temperature is synonymous with the maximum temperature.

[0072] The conditions for annealing other than the holding temperature are as follows: The temperature holding time during annealing may be 0 to 30 hours or 1 to 25 hours. The cooling rate during annealing may be 50 to 500°C / hour or 100 to 300°C / hour. In addition, humidified N2 gas or the like may be used as the atmospheric gas for annealing.

[0073] In the debinder treatment, firing, and annealing described above, there are no particular restrictions on the method of humidifying N2 gas or mixed gas. For example, humidification can be done using a wetter. When using a wetter, the water temperature should preferably be around 5 to 75°C.

[0074] The debinding process, firing, and annealing may be performed consecutively or independently.

[0075] The capacitor element body 10 obtained as described above is subjected to end face polishing, and an external electrode paste is applied and fired to form the external electrode 4. There are no particular restrictions on the method of end face polishing. For example, barrel polishing or sandblasting can be used. Furthermore, if necessary, a coating layer may be formed on the surface of the external electrode 4 by plating or the like.

[0076] Generally, the dielectric powder included as a co-material in the internal electrode layer paste is a fine powder with a smaller particle size than the dielectric powder included in the dielectric layer paste. Improving the quality of such fine powder is difficult, and it tends to result in powder with a high intragranular pore ratio. Furthermore, the diffusion of relatively low-quality co-material into the dielectric layer tends to increase the proportion of pore-containing particles in the electrode contact particles, which can easily reduce the reliability of the multilayer ceramic capacitor.

[0077] By reducing the in-granular pore ratio of the dielectric powder included as a co-material in the paste for the internal electrode layer, the proportion of pore-containing particles in the electrode contact particles does not increase easily even if the co-material diffuses into the dielectric layer.

[0078] Furthermore, by reducing the amount of co-material in the paste for the internal electrode layer and increasing the heating rate during firing, the internal electrodes are sintered before the co-material diffuses into the dielectric layer, and the co-material remains in the internal electrode layer. As a result, the co-material is less likely to diffuse into the dielectric layer, and the proportion of pore-containing particles in the electrode contact particles does not increase easily. Also, when the internal electrodes are sintered before the co-material diffuses into the dielectric layer, the internal electrode particles 3a are more likely to contain dielectric particles 3b within the electrode, as shown in Figure 2.

[0079] Based on the above, the proportion of pore-containing particles in the electrode contact particles tends to decrease, which improves the reliability of the multilayer ceramic capacitor.

[0080] The multilayer ceramic capacitor 1 of this embodiment, manufactured in this manner, is mounted on a printed circuit board or the like by soldering and used in various electronic devices.

[0081] While embodiments of the present invention have been described above, the present invention is not limited in any way to the embodiments described above, and can be modified in various ways without departing from the spirit of the invention. [Examples]

[0082] The present invention will be described below based on more detailed examples, but the present invention is not limited to these examples.

[0083] (Example 1) Barium titanate powder (BaTiO3) was prepared as the main component using a liquid-phase method. The pore density of the barium titanate powder was 24%.

[0084] Next, a sintering aid, a binder, and an organic solvent were added to the BaTiO3 powder, which is the main component raw material. 100 parts by weight of BaTiO3 powder, 0.4 parts by weight of SiO2 powder as a sintering aid, 15 parts by weight of polyvinyl butyral resin as a binder, and 100 parts by weight of ethanol as an organic solvent were wet-mixed in a ball mill to form a paste, which was used to obtain a dielectric layer paste. The dielectric layer paste was then applied to a carrier film and dried to obtain a ceramic green sheet.

[0085] A separate material was prepared. First, barium titanate powder (BaTiO3) with an intragranular pore ratio of 60% was prepared by the liquid-phase method. Next, the barium titanate powder was heat-treated in an electric furnace. The heat treatment temperature was 900°C, and the holding time during heat treatment was 4 hours. After that, the material was wet-milled using a nylon pot mill with zirconia balls, followed by heat treatment to reduce the intragranular pore ratio. The heat treatment temperature after wet milling was 150°C, and the holding time during heat treatment was 10 hours. The material was then milled to obtain a material powder with an average particle size of 50 nm. The intragranular pore ratio of this material powder was 26%.

[0086] Next, 100 parts by weight of Ni powder with an average particle size of 100 nm, 3 parts by weight of ethyl cellulose as a binder, 100 parts by weight of terpineol acetate as a dispersion medium, and 20 parts by weight of the above-mentioned co-material powder were kneaded together to form a slurry and prepared a paste for the internal electrode layer.

[0087] Then, using a paste for the internal electrode layer, the electrode layer, which would ultimately become the internal electrode layer, was printed in a predetermined pattern onto the ceramic green sheet described above. After printing the electrode layer, the green sheet was peeled off the PET film to produce a green sheet with the electrode layer. Next, multiple green sheets with the electrode layer were stacked, pressed together, and cut to produce a laminate.

[0088] This document describes a method for determining the intragranular pore ratio of barium titanate powder. First, transmission electron microscope images were taken of the barium titanate powder at a magnification of 50,000 to 100,000 times. At least 300 powder particles contained in the images were observed. One image or two or more images may be used. The number of powder particles with voids (pores) among the observed powder particles was counted to calculate the intragranular pore ratio of each barium titanate powder. Pores appear black in transmission electron microscope images.

[0089] After binder removal, firing and annealing were performed under the following conditions to obtain the capacitor element body as a sintered body.

[0090] The debinder removal process conditions were: heating rate: 25°C / hour, holding temperature: 800°C, holding time: 8 hours, atmosphere: N2+H2 mixed gas (oxygen partial pressure: 10%). -12 (MPa)

[0091] The firing conditions were: holding temperature: 1100~1300°C, holding time: 0.5 hours. Cooling rate: 800°C / hour, ambient gas: humidified N2+H2 mixed gas (oxygen partial pressure: 10%). -10 The temperature was set to MPa. The heating rate is shown in Table 1.

[0092] The annealing conditions were: heating rate: 200°C / hour, holding temperature: 1000°C, holding time: 2 hours, cooling rate: 200°C / hour, ambient gas: humidified N2 gas (oxygen partial pressure: 10%). -7 (MPa)

[0093] A wetter was used to humidify the atmospheric gas during firing and annealing.

[0094] Next, the end faces of the obtained capacitor element bodies were polished by sandblasting, and then an external electrode paste containing glass frit and Cu was applied. The external electrodes were then formed by firing to obtain the multilayer ceramic capacitor sample shown in Figure 1.

[0095] The obtained capacitor sample had dimensions of 2.00 mm × 1.25 mm × 1.25 mm, with a dielectric layer thickness of 0.7 μm and an internal electrode layer thickness of 0.6 μm. The number of dielectric layers sandwiched between the internal electrode layers was 260.

[0096] This section describes the measurement methods for the relative permittivity of the obtained capacitor samples, including the proportion of pore-containing particles in the electrode contact particles, the proportion of pore-containing particles in the electrode non-contact particles, and the relative permittivity. Furthermore, it describes the evaluation method for accelerated testing and the measurement method for high-temperature load life.

[0097] Pore-containing particles First, the capacitor sample was polished so that a cross-section of the inner layer, that is, a cross-section parallel to the XY plane in Figure 1, and with equal distances from two surfaces perpendicular to the Z axis, could be observed.

[0098] Next, the two internal electrode layers 3 and the dielectric layer 2 sandwiched between them were extracted and thinned.

[0099] Next, the thin sections were observed using a STEM at magnifications between 500,000x and 1,000,000x to obtain STEM-HAADF images.

[0100] Each dielectric particle in dielectric layer 2 was identified as either an electrode contact particle or an electrode non-contact particle. Simultaneously, it was determined whether each dielectric particle contained a pore within the particle. In STEM-HAADF images, pores are observed as black dots. All black dots in the STEM-HAADF image are considered pores.

[0101] The above measurements were performed on observation areas containing at least 10 particles in contact with the electrodes and at least 40 particles not in contact with the electrodes. Multiple STEM-TAADF images were obtained where necessary. The proportion of pore-containing particles among the electrode-contact particles and the proportion of pore-containing particles among the electrode-non-contact particles were then calculated. The results are shown in Table 1.

[0102] Accelerated testing The obtained multilayer ceramic capacitor samples were subjected to accelerated testing at 180°C under an electric field of 20 V / μm. The time required for the insulation resistance to drop below 1000 Ω was calculated. A result of 15 hours or more was considered to be a good result for the accelerated testing.

[0103] Relative permittivity The capacitance of the obtained multilayer ceramic capacitor sample was measured at room temperature using a digital LCR meter (YHP 4284A) with a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms. The relative permittivity (unitless) was then calculated based on the thickness of the dielectric layer, the effective electrode area, and the capacitance obtained from the measurement. In this example, a relative permittivity of 2200 to 2500 was considered good.

[0104] High temperature load life For the 2000 obtained multilayer ceramic capacitor samples, a DC current was applied under a 10V / μm electric field at 125°C, and the change in the insulation resistance of the multilayer ceramic capacitor samples was observed. Multilayer ceramic capacitor samples in which the time until the insulation resistance dropped by an order of magnitude after the start of DC current application was 20 hours or more were considered to have good high-temperature load life. In this example, a good high-temperature load life was judged to be when the percentage of multilayer ceramic capacitor samples with poor high-temperature load life was less than 0.05% (less than 1 / 2000).

[0105] (Comparative Example 1) The procedure was carried out under the same conditions as in Example 1, except that no heat treatment was performed during the preparation of the materials.

[0106] (Examples 2-4) The experiment was conducted under the same conditions as Example 1, except that the heat treatment temperature during material preparation was changed to 950°C (Example 2), 1000°C (Example 3), and 1050°C (Example 4) to alter the pore ratio within the particles of the material, and the average particle size of the material was also altered.

[0107] (Example 5) The procedure was carried out under the same conditions as in Example 1, except that a solid-phase method was used instead of the liquid-phase method during the preparation of the material, which differed from conventional methods in the respects described above, and that no heat treatment was performed after grinding. The synthesis temperature in the solid-phase method was 1000°C, and the holding time at the synthesis temperature was 2 hours. The final obtained material had an intragranular pore ratio of 2%.

[0108] (Comparative Example 2) The procedure was carried out under the same conditions as in Example 1, except that a solid-phase method was used instead of the liquid-phase method during the preparation of the composite material, which differed from conventional methods in the respects described above, and that no heat treatment was performed after grinding. The synthesis temperature in the solid-phase method was 1100°C, and the holding time at the synthesis temperature was 2 hours. The final composite material had an intragranular pore ratio of 0.2%.

[0109] (Comparative Example 3) The procedure was carried out under the same conditions as in Example 1, except that the co-material was replaced with SiO2 powder that did not contain pores within the particles.

[0110] (Comparative Example 4) The procedure was carried out under the same conditions as in Example 1, except that no co-material was added.

[0111] The test results for Examples 1-5 and Comparative Examples 1-4 are shown in Table 1.

[0112] [Table 1]

[0113] Table 1 shows examples and comparative examples in which the number ratio of pore-containing particles was changed mainly by altering the intragranular pore ratio of the common material. Examples 1 to 5, in which the number ratio of pore-containing particles in the electrode contact particles was kept within a predetermined range mainly by altering the intragranular pore ratio of the common material, showed good characteristics.

[0114] In contrast, Comparative Example 1, in which the proportion of pore-containing particles in the electrode contact particles was too large, did not perform well in the accelerated test, resulting in an excessively low dielectric constant and a poor high-temperature load life. Comparative Example 2, in which the proportion of pore-containing particles in the electrode contact particles was too small, also did not perform well in the accelerated test, resulting in an excessively high dielectric constant and a poor high-temperature load life. Comparative Example 3, which used SiO2 powder as the co-material, did not contain any pore-containing particles in the electrode contact particles. The accelerated test results were also unsatisfactory, with an excessively low dielectric constant and a poor high-temperature load life. This is thought to be because the use of SiO2 powder as the co-material resulted in the formation of a different phase mainly containing Si near the internal electrode layer. Comparative Example 4, which did not use a co-material, suffered internal cracking, and its properties could not be measured.

[0115] (Examples 11-15, Comparative Examples 11, 12) In Examples 11-15, barium titanate powder (BaTiO3) was prepared as the main component using a solid-phase method. The pore density of the barium titanate powder used as the main component was 1%. Other than the main component, the tests were conducted under the same conditions as in Examples 1-5 and Comparative Examples 1 and 2. The test results for Examples 11-15 and Comparative Examples 11 and 12 are shown in Table 2.

[0116] [Table 2]

[0117] As shown in Table 2, even when the pore ratio within the grain of the barium titanate powder, the main raw material, was reduced compared to the examples and comparative examples shown in Table 1, and the proportion of pore-containing particles, mainly in the non-contacting electrode particles, was reduced, the same trend as in the examples and comparative examples shown in Table 1 was obtained.

[0118] In particular, with regard to accelerated testing, it was confirmed that the smaller the proportion of pore-containing particles in the non-contacting electrode particles, the better the results tend to be, and that the influence of the proportion of pore-containing particles in the contacting electrode particles is greater than the influence of the proportion of pore-containing particles in the non-contacting electrode particles.

[0119] (Examples 21-24, Comparative Examples 21-28) Examples 1, 5, Comparative Example 1, and Comparative Example 2 were carried out under the same conditions except for changes in the heating rate during firing and / or the mixing ratio of the common materials. The results are shown in Table 3.

[0120] [Table 3]

[0121] The faster the heating rate during firing, the smaller the proportion of pore-containing particles tended to be. Furthermore, good properties were obtained when the proportion of pore-containing particles in the electrode contact particles was within a predetermined range. In particular, the faster the heating rate during firing, the more favorable the results of the accelerated test tended to be.

[0122] In each comparative example with a heating rate of 0.2 k°C / hr, the co-material diffused more easily into the dielectric layer, and the co-material containing intragranular pores became the electrode contact particles, resulting in a higher proportion of pore-containing particles among the electrode contact particles.

[0123] (Examples 31-40) Examples 1 and 5 were carried out by mainly changing the composition of the common materials and main components. The results are shown in Table 4. In Examples 31 and 32, the atomic ratio of Ba:Sr was 97:3. In Examples 33 and 34, the atomic ratio of Ba:Ca was 97:3. In Examples 35 and 36, the atomic ratio of Ti:Zr was 95:5. In Examples 37 and 38, the atomic ratio of Ba:Sr was 97:3 and Ti:Zr was 95:5. In Examples 39 and 40, the atomic ratio of Ba:Ca was 97:3 and Ti:Zr was 95:5.

[0124] [Table 4]

[0125] Table 4 shows that even when the composition of the common materials and main components was changed, similar results were obtained as long as the other parameters remained the same. [Explanation of Symbols]

[0126] 1… Multilayer ceramic capacitor 2… Dielectric layer 2a… Electrode contact particles 2a1… (Particles in contact with electrodes and) pore-free particles 2a2… (Particles in contact with electrodes and) pore-containing particles 2b…electrode non-contact particles 2b1… (Electrode-non-contact particles and) pore-free particles 2b2… (Particles not in contact with electrodes and) pore-containing particles 3… Internal electrode layer 3a… Internal electrode particles 3b... Dielectric particles in the electrode 4... External electrode 10… Capacitor element body

Claims

1. A multilayer ceramic electronic component having an element body in which a dielectric layer and an internal electrode layer are stacked, The dielectric layer is, General formula A 1 B 1 O 3 (A 1 is at least one selected from Ca and Sr and Ba, or Ba alone, and B 1 It contains dielectric particles that include a main component represented by Ti and Zr, or Ti alone. In a cross-section parallel to the stacking direction, at least a portion of the dielectric particles are electrode contact particles that are in contact with the internal electrode layer, and at least a portion of the dielectric particles are pore-containing particles that contain pores. A multilayer ceramic electronic component in which the number ratio of the electrode contact particles, which are also pore-containing particles, to the electrode contact particles is 0.1% or more and 15.0% or less.

2. The multilayer ceramic electronic component according to claim 1, wherein the thickness of the dielectric layer is 1 μm or less, and the number of dielectric layers is 100 or more.

3. In a cross-section parallel to the stacking direction, at least a portion of the dielectric particles are electrode-non-contact particles that do not come into contact with the internal electrode layer. The multilayer ceramic electronic component according to claim 1 or 2, wherein the number ratio of the electrode non-contact particles, which are pore-containing particles, to the electrode non-contact particles is 0.1% or more and 15% or less.

4. The internal electrode layer is represented by the general formula A 2 B 2 O 3 (where A 2 is at least one selected from Ca and Sr and Ba, or Ba alone, and B 2 is Ti and Zr, or Ti alone). The multilayer ceramic electronic component according to claim 1 or 2, comprising electrode inner dielectric particles containing a main component represented by

5. A 2 B 2 O 3 A 1 B 1 O 3 A multilayer ceramic electronic component according to claim 4, which is substantially identical to the one described above.

6. A 2 B 2 O 3 ga BaTiO 3 The multilayer ceramic electronic component according to claim 4 or 5.

7. A method for manufacturing a multilayer ceramic electronic component, comprising the step of forming an internal electrode layer on a ceramic green sheet using an internal electrode layer paste, The paste for the internal electrode layer comprises metal powder and a co-material, The aforementioned common material is General Formula A 2 B 2 O 3 (A 2 is at least one selected from Ca and Sr and Ba, or Ba alone, and B 2 These are dielectric particles represented by Ti and Zr, or Ti alone. At least a portion of the dielectric particles are pore-containing dielectric particles, and the number ratio of the pore-containing dielectric particles to the dielectric particles is 1.0% or more and 40% or less. A method for manufacturing a multilayer ceramic electronic component, wherein the ratio of the co-material to 100 parts by weight of the metal powder is 8 parts by weight or more and 20 parts by weight or less.

8. A 2 B 2 O 3 ga BaTiO 3 The method for manufacturing a multilayer ceramic electronic component according to claim 7.

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