Dielectric composition, laminated electronic component and production method therefor

Abstract

To provide a dielectric composition with a low relative permittivity in a high-frequency band and a high Qf value that can be co-fired with a Cu-containing conductor.SOLUTION: The dielectric composition contains, in any cross-section, a glass-ceramic crystalline phase with an area fraction of 40% or more, and a carbon content of 500 ppm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a dielectric composition, a laminated electronic component, and a method for producing the same. [Background technology]

[0002] In the field of information and communications equipment, the increasing speed of information communication has created a demand for low-loss transmission of high-frequency signals. For this reason, metal materials with low electrical resistance, such as copper and silver, are used as conductor materials in the electronic components and multilayer electronic components (such as multilayer ceramic capacitors) included in information and communications equipment.

[0003] Furthermore, there is a demand for a dielectric material that can be sintered at a low enough temperature to be co-fired with the conductor when the conductor contains Cu, and that has a low dielectric constant to be able to sufficiently reduce transmission loss.

[0004] Furthermore, the miniaturization of laminated electronic components requires thinner dielectric layers. However, thinner layers result in reduced leakage characteristics and voltage resistance. Therefore, dielectric materials with high insulation resistance are required.

[0005] Patent Document 1 describes an invention related to a glass ceramic sintered body, etc. By containing a glass component with a specific composition, a ceramic filler, and a composite oxide within specific ranges, a glass ceramic sintered body with reduced dielectric loss in the high frequency range can be obtained.

[0006] Patent Document 2 describes an invention related to dielectric porcelain. By using a mixture containing crystallized glass powder with a specific composition and Al2O3 powder within specific ranges, a dielectric porcelain can be obtained in which the relative permittivity, Q value, and three-point bending strength are within specific ranges in the frequency range of 14 GHz to 16 GHz.

[0007] Patent Document 3 describes an invention related to a high-frequency ceramic composition. It is characterized by containing 60 to 85% by weight of a glass powder capable of precipitating a diopside-type oxide crystal phase and 15 to 40% by weight of a quartz powder. Furthermore, Patent Document 3 describes a method for producing high-frequency ceramic, characterized by molding a mixture containing these powders in the above-mentioned ratios and then firing it at a temperature of 800 to 975°C. The high-frequency ceramic produced by this method has a low dielectric constant and a thermal expansion coefficient similar to that of chip components such as GaAs and printed circuit boards, and exhibits low dielectric loss even in the high-frequency range of 1 GHz or higher. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 6293704 [Patent Document 2] Patent No. 5341301 [Patent Document 3] Patent No. 3085667 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in view of the above circumstances, and aims to provide a dielectric composition and the like that has a low relative permittivity and a high Qf value in the high frequency band and that can be co-fired with a conductor containing Cu. [Means for solving the problem]

[0010] In order to achieve the above object, the dielectric composition of the present invention comprises: In any cross section, the glass ceramic crystalline phase is contained in an area ratio of 40% or more, and the carbon content is 500 ppm or less.

[0011] The dielectric composition may contain the glass ceramic crystalline phase in an area ratio of 40% to 80%.

[0012] The dielectric composition may have an area ratio of the glass ceramic amorphous phase of 0% or more and 20% or less in any cross section.

[0013] The carbon content of the dielectric composition may be 300 ppm or less.

[0014] In the dielectric composition, the crystalline phase contained in the glass ceramic may be a diopside phase.

[0015] The laminated electronic component of the present invention has a laminated portion formed by alternately laminating dielectric layers and internal electrode layers, and the dielectric layers contain the above-described dielectric composition.

[0016] In the laminated electronic component of the present invention, the internal electrode layers may contain Cu.

[0017] The method for producing a laminated electronic component of the present invention is a method for producing the laminated electronic component, which comprises a step of performing a binder removal treatment in a reducing atmosphere having a temperature of 650°C or lower and a dew point of 70°C or higher. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic cross-sectional view of a laminated electronic component according to an embodiment of the present invention. [Figure 2] Figure 2 is an SEM image of a cross section of a multilayer ceramic capacitor. [Figure 3] Figure 3 is an SEM image of a cross section of a multilayer ceramic capacitor. [Figure 4] Figure 4 is an SEM image of a cross section of a multilayer ceramic capacitor. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the drawings, common components are designated by common reference numerals, and their description will be partially omitted. Furthermore, the present invention is not limited to the following embodiments, and can be carried out with appropriate modifications within the scope of the object of the present invention. Furthermore, where the description overlaps, the description may be omitted as appropriate, but this does not limit the spirit of the invention.

[0020] Hereinafter, an embodiment of the present invention will be described using a laminated electronic component and a method for manufacturing the same as an example.

[0021] The multilayer ceramic capacitor 1, which is one type of multilayer electronic component according to this embodiment, has a capacitor element body 10 configured with dielectric layers 2 and internal electrode layers 3 alternately stacked. A pair of external electrodes 4 is formed on both ends of this capacitor element body 10, and is electrically connected to the internal electrode layers 3 alternately arranged inside the capacitor element body 10. The capacitor element body 10 may have any shape, but is typically a rectangular parallelepiped. Its dimensions are also arbitrary and may be set to appropriate dimensions depending on the application. The portion where the dielectric layers 2 and internal electrode layers 3 are alternately stacked is referred to as the laminated portion.

[0022] The internal electrode layers 3 are laminated so that their ends are alternately exposed on the surfaces of two opposing end faces of the capacitor element body 10. A pair of external electrodes 4 are formed on both end faces of the capacitor element body 10 and connected to the exposed ends of the alternately arranged internal electrode layers 3 to form a capacitor circuit.

[0023] The thickness of the dielectric layer 2 is not particularly limited, but is preferably 50 μm or less per layer, and more preferably 30 μm or less. The lower limit of the thickness is not particularly limited, but is, for example, about 0.5 μm.

[0024] The number of laminated dielectric layers 2 is not particularly limited, but is preferably 20 or more, and more preferably 50 or more.

[0025] Any type of conductive material may be contained in the internal electrode layers 3. The internal electrode layers 3 may contain Cu. There is no particular limitation on the content of Cu. For example, the internal electrode layers 3 may contain 50 mass % or more of Cu.

[0026] The internal electrode layers 3 may be formed using commercially available electrode paste. The thickness of the internal electrode layers 3 may be determined appropriately depending on the application, etc. For example, the thickness may be 0.2 μm or more and 20.0 μm or less per layer.

[0027] Any conductive material may be contained in the external electrodes 4. In this embodiment, for example, inexpensive Ni or Cu, highly heat-resistant Au, Ag or Pd, or an alloy of Ni, Cu, Au, Ag and / or Pd can be used. The thickness of the external electrodes 4 may be determined appropriately depending on the application, etc., but is usually preferably about 10 to 50 μm.

[0028] Next, the dielectric composition that constitutes the dielectric layer 2 according to this embodiment will be described in detail.

[0029] There are no particular limitations on the type of dielectric composition according to this embodiment. The dielectric composition contains at least a glass-ceramic phase. At least a portion of the glass-ceramic phase is a crystalline phase. The glass-ceramic phase may be entirely crystalline, or may contain both a crystalline phase and an amorphous phase. Hereinafter, a phase that is both a glass-ceramic phase and a crystalline phase may be referred to as a glass-ceramic crystalline phase. A phase that is both a glass-ceramic phase and an amorphous phase may be referred to as a glass-ceramic amorphous phase.

[0030] Whether or not the glass ceramic phase is a glass ceramic crystalline phase is determined by whether or not at least a portion of the components contained therein are crystallized.

[0031] The type of glass ceramic phase is not particularly limited. Examples include a diopside phase containing diopside (CaMgSiO), a forsterite phase containing forsterite (MgSiO), and a steatite phase containing steatite (MgSiO). In particular, a multilayer ceramic capacitor having a dielectric composition containing a large amount of diopside phase is likely to have improved insulation resistance. Specifically, the area ratio of the diopside phase to the glass ceramic phase in any cross section may be 40.0% or more.

[0032] In the dielectric composition according to this embodiment, the area ratio of the glass ceramic crystal phase in any cross section is 40% or more, and may be 40% or more and 80% or less.

[0033] The area ratio of the glass ceramic crystalline phase refers to the value obtained by dividing the total area ratio of the glass ceramic crystalline phase by the area ratio of the dielectric composition. The area ratio of the dielectric composition does not include the area ratio of voids present in the dielectric composition. The same applies to the calculation of the area ratio of each phase shown below.

[0034] In the dielectric composition according to this embodiment, the area ratio of the glass ceramic amorphous phase in any cross section may be 0% or more and 20% or less, that is, the glass ceramic amorphous phase may not be contained in the dielectric composition.

[0035] Furthermore, the dielectric composition according to this embodiment may contain a ceramic phase other than the glass ceramic phase. Hereinafter, when simply referred to as a "ceramic phase" or "other ceramic phase", it refers to a ceramic phase other than the glass ceramic phase. There is no particular limitation on the type of ceramic phase. Examples of the ceramic phase include SrTiO3 phase, CaZrO3 phase, BaTiO3 phase, BaSrTa4O 12 phase, Ba6Zr2Ta8O 30The ceramic ceramic may contain a ceramic phase, an Al2O3 phase, an SrAl2Si2O8 phase, an SiO2 phase, an SrTiO3 phase, an Mg2SiO4 phase, and / or an SrCuO2 phase. These phases may be crystalline phases in which at least some of the components are crystallized, or amorphous phases in which the components are not crystallized. Hereinafter, a phase that is both a ceramic phase and a crystalline phase may be referred to as a ceramic crystalline phase. Furthermore, a phase that is both a ceramic phase and an amorphous phase may be referred to as a ceramic amorphous phase.

[0036] The case where the dielectric composition contains a large amount of a specific phase as the ceramic phase refers to the case where the mass ratio of the specific phase to the mass ratio of the ceramic phase in any cross section is 10 mass % or more.

[0037] When the dielectric composition contains a large amount of SrTiO3 phase as the ceramic phase, the QF value is relatively resistant to decrease. When the dielectric composition contains a large amount of BaTiO3 phase as the ceramic phase, the dielectric constant tends to be high. Furthermore, loss tends to increase in the high frequency band, and the Qf value tends to decrease.

[0038] There are no particular limitations on the area ratio of the ceramic phase in any cross section, and it may be 0% or more and 65% or less, or 5.0% or more and 40% or less.

[0039] There are no particular limitations on the method for confirming the microstructure of the dielectric composition, and examples include methods using devices such as SEM-EDS and STEM-EDS.

[0040] An observation range is set on an arbitrary cross section of the dielectric composition, and an elemental mapping image of the set observation range is created using the above-mentioned device. Specifically, elemental mapping images of Si, Mg, Al, Cu, Sr, and Ca are created. Then, the position and area of ​​each phase in the dielectric composition are identified from the elemental mapping image.

[0041] The area ratio of each phase and voids in the cross-sectional image of the dielectric composition can be determined, for example, using image analysis software. Furthermore, the area ratio of each phase to the area of ​​the dielectric composition excluding voids can also be determined.

[0042] Whether each phase is a crystalline phase or not can be determined by obtaining an electron diffraction image using a transmission microscope. If each phase is a crystalline phase, diffraction spots showing a complete crystal lattice image will be observed in the electron diffraction image. If each phase is an amorphous phase, either no diffraction spots will be observed in the electron diffraction image or only diffraction spots showing an incomplete crystal lattice image will be observed, and no diffraction spots showing a complete crystal lattice image will be observed.

[0043] There are no particular limitations on how the crystals are present in the glass-ceramic crystalline phase. For example, crystals may be precipitated in the amorphous glass-ceramic, resulting in the amorphous glass-ceramic being contained therein. The portion of the glass-ceramic where the crystals are precipitated and its vicinity may form the glass-ceramic crystalline phase. Alternatively, the amorphous glass-ceramic may be completely crystallized, resulting in a glass-ceramic crystalline phase that does not contain any amorphous glass-ceramic.

[0044] The carbon content of the dielectric composition according to this embodiment is 500 ppm or less by weight. It may be 300 ppm or less. If the carbon content is too high, the Qf value (the product of the Q value and frequency f) decreases. There is no particular lower limit for the carbon content. The carbon content may be, for example, 100 ppm or more.

[0045] Next, an example of a method for manufacturing a multilayer ceramic capacitor will be described.

[0046] The multilayer ceramic capacitor 1 of this embodiment is manufactured in the same manner as conventional multilayer ceramic capacitors by producing a green chip by a normal printing method or sheet method using a paste, firing the green chip, and then applying external electrodes and firing the chip.

[0047] Crystallized glass powder and various other powders are prepared as the raw material powders for the dielectric layer 2. The crystallized glass powder is a glass powder that crystallizes upon firing. The crystallized glass powder used as the raw material for the dielectric layer 2 of this embodiment is a glass powder that generates the desired glass-ceramic crystalline phase upon firing.

[0048] There is no particular limitation on the types of powders other than the crystallized glass powder used as raw material powder for the dielectric layer 2 of this embodiment. For example, SrTiO3 powder, BaTiO3 powder, CaZrO3 powder, BaSrTa4O4 powder, 12 Powder, Ba6Zr2Ta8O 30 Powders may also be used.

[0049] The raw material powder for the dielectric layer 2 of this embodiment may further include alumina powder, silica powder, etc. The alumina powder, silica powder, etc. are used, for example, as a filler. Furthermore, powders of high-dielectric materials such as titanium oxide, calcium titanate, perovskite-based oxides (e.g., CaTiO3-SrTiO3), and BaNdTiO-based oxides may also be used.

[0050] There is no particular limitation on the proportion of the crystallized glass powder relative to the total raw material powder of the dielectric layer 2, and it may be 51 mass % or more and 79 mass % or less. By changing the proportion of the crystallized glass powder, the area proportion of the glass ceramic phase and the area proportion of the ceramic phase can be controlled.

[0051] There is no particular limitation on the average particle size of the crystallized glass powder, and it may be 0.3 μm or more and 10 μm or less.

[0052] Separately, an organic vehicle is prepared. There are no particular limitations on the type of organic vehicle, and any organic vehicle commonly used in this technical field may be prepared.

[0053] Next, the raw material powders are appropriately weighed and blended with the prepared organic vehicle to prepare a dielectric layer paste for forming the dielectric layer 2.

[0054] The organic vehicle is a binder dissolved in an organic solvent. The type of binder used in the organic vehicle is arbitrary and may be appropriately selected from various binders commonly used in this technical field, such as ethyl cellulose and polyvinyl butyral. The type of organic solvent is also arbitrary. Depending on the method for manufacturing the multilayer ceramic capacitor (e.g., a printing method or a sheet method), the type of organic solvent may be appropriately selected from various organic solvents, such as terpineol, butyl carbitol, and acetone.

[0055] Alternatively, the dielectric layer paste may be prepared using an aqueous vehicle instead of an organic vehicle. An aqueous vehicle is a vehicle in which a water-soluble binder, dispersant, etc. are dissolved in water. Any type of water-soluble binder may be used in the aqueous vehicle. For example, polyvinyl alcohol, cellulose, water-soluble acrylic resin, etc. may be used.

[0056] Next, a paste for internal electrode layers is prepared separately from the paste for dielectric layers by kneading the conductive material described above, or various oxides, organometallic compounds, resinates, etc. that become the conductive material after firing, with the organic vehicle described above.

[0057] The external electrode paste may be prepared in the same manner as the internal electrode layer paste described above.

[0058] There are no particular restrictions on the content of the organic vehicle in each of the above pastes, and typical contents, such as about 1% to 5% by mass for the binder and about 10% to 50% by mass for the solvent, may be used. Furthermore, each paste may contain additives selected from various dispersants, plasticizers, dielectric materials, insulating materials, etc., as needed. The total content of these is preferably 10% by mass or less.

[0059] Any type of dispersant can be used. For example, surfactant-type dispersants and polymer-type dispersants can be used. Any type of plasticizer can be used. For example, dioctyl phthalate and dibutyl phthalate can be used. Any type of dielectric material can be used. For example, BaTiO3-based and CaZrO3-based dielectric materials can be used. Any type of insulator material can be used. For example, Al2O3 and SiO2 can be used.

[0060] When the printing method is used, the dielectric layer paste and the internal electrode layer paste are printed and laminated on a substrate such as PET, cut into a predetermined shape, and then peeled off from the substrate to form a green chip.

[0061] When the sheet method is used, a green sheet is formed using a dielectric layer paste, and then the internal electrode layer paste is printed on the green sheet, and these are then laminated to form a green chip.

[0062] Before firing, the green chip is subjected to a binder removal treatment. By subjecting the green chip to a binder removal treatment, the carbon content in the dielectric composition after firing, which will be described later, can be reduced to 500 ppm or less, or 300 ppm or less.

[0063] The binder removal treatment conditions are arbitrary. In particular, when the conductive material of the internal electrode layer contains a material that is easily oxidized, such as Cu, the holding temperature during the binder removal treatment may be 700°C or lower, or may be 650°C or lower. The holding temperature may also be 600°C or higher. The higher the holding temperature during the binder removal treatment, the lower the carbon content of the dielectric composition after the binder removal treatment. The holding time during the binder removal treatment may be 10 to 60 hours. The atmosphere is a reducing atmosphere. There are no particular restrictions on the type of reducing atmosphere. The dew point of the reducing atmosphere may be 50°C or higher, or may be 70°C or higher. The dew point may also be 100°C or lower. The higher the dew point of the reducing atmosphere, the lower the carbon content of the dielectric composition after the binder removal treatment. The reducing atmosphere may be a holding temperature of 700°C or lower and a dew point of 50°C or higher, or a holding temperature of 650°C or lower and a dew point of 70°C or higher. The method of humidifying the atmospheric gas to adjust the dew point is arbitrary. For example, a wetter or the like may be used.

[0064] There are no particular limitations on the amount of carbon contained in the dielectric composition after the binder removal treatment. For example, it may be 800 ppm or less, or 550 ppm or less. If the carbon amount at this point is within the above range, it is easy to reduce the amount of carbon contained in the dielectric composition after firing to 500 ppm or less, or 300 ppm or less.

[0065] If the atmosphere during the binder removal treatment is not a reducing atmosphere, for example, an air atmosphere, the internal electrode layers are likely to be oxidized. In particular, if the conductive material of the internal electrode layers contains a material that is easily oxidized, such as Cu, the internal electrode layers are likely to be oxidized, and the loss of the multilayer ceramic capacitor is likely to increase.

[0066] If the binder removal process is insufficient, the carbon content in the dielectric composition after firing exceeds 500 ppm. As a result, voids are likely to occur in the dielectric layers of the multilayer ceramic capacitor, as shown in Figure 2, which is an SEM image of a cross section parallel to the lamination direction. As a result, the Q value decreases and loss increases. Note that Figures 2 to 4 are drawings in which the lamination direction is horizontal, unlike Figure 1.

[0067] There is no particular limitation on the ratio of the total area of ​​voids to the area of ​​the dielectric layer 2. For example, in any cross section, the ratio of the total area of ​​voids to the area of ​​the dielectric layer 2 may be 0% or more. In other words, the dielectric layer 2 may not contain voids. The ratio of the total area of ​​voids to the area of ​​the dielectric layer 2 may be 1.0% or more.

[0068] In particular, if the conductive material of the internal electrode layer contains a material that easily sinters, such as Cu, the internal electrode will sinter if the binder removal temperature is too high. As a result, after firing (described later), delamination is likely to occur between the internal electrode layer and the dielectric layer (to the left of the third internal electrode layer from the left), as shown in Figure 3, which is an SEM image of a cross section parallel to the lamination direction of a multilayer ceramic capacitor. This reduces the Q value and increases loss.

[0069] For these reasons, it is important to appropriately control the binder removal process conditions, especially when the conductive material of the internal electrode layer contains a material that is easily sintered, such as Cu. The carbon content in the dielectric composition after firing can be reduced to 500 ppm or less. Furthermore, after firing, as described below, there are fewer voids and no delamination occurs in the multilayer ceramic capacitor, as shown in Figure 4, which is an SEM image of a cross section parallel to the lamination direction. This results in an improved Q value and reduced loss.

[0070] The firing conditions for the green chip are arbitrary. The temperature rise rate may be 2000°C / hour to 50000°C / hour, the holding temperature may be 800°C to 1050°C, the holding time may be 30 minutes to 600 minutes, and the temperature drop rate may be 2000°C / hour to 50000°C / hour. The firing atmosphere may be air or a reducing atmosphere.

[0071] In particular, when the conductive material of the internal electrode layer contains a material that is easily oxidized, such as Cu, a reducing atmosphere (dew point 10°C to 50°C) is preferable. In particular, when the conductive material of the internal electrode layer contains a material that is easily oxidized, such as Cu, if firing is performed in air, delamination is likely to occur between the internal electrode layer and the dielectric layer, and if delamination occurs, the Q value is likely to decrease. In addition, any method can be used to humidify the atmospheric gas to adjust the dew point during firing. For example, a wetter or the like can be used. In this case, the water temperature is preferably about 10°C to 70°C. In addition, there is no particular limitation on the oxygen partial pressure of the atmospheric gas, but it is preferable that the oxygen partial pressure is 2.9 x 10 -15 atm~7.2×10 -15 It can also be called ATM.

[0072] In the above firing, the longer the holding time, the more easily the crystallization of the glass ceramic in the dielectric composition progresses.

[0073] Furthermore, the temperature increase and decrease rates in the firing are significantly faster than those in conventional green chip firing, which facilitates an improvement in the Q value of the dielectric composition and an improvement in the Qf value.

[0074] Although a preferred embodiment of the laminated electronic component according to one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. [Example]

[0075] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0076] (Experimental Example 1) As the glass powder, a crystallized glass powder containing 40-50% by mass of SiO2, 10-30% by mass of CaO, 10-30% by mass of MgO, and 10-30% by mass of SrO was prepared. That is, the glass-ceramic phase was made to be mainly a diopside phase containing diopside. Separately from the crystallized glass powder, a ceramic powder was also prepared. Strontium titanate powder and alumina filler were prepared as the ceramic powder. The composition of the crystallized glass powder was controlled, and each powder was weighed, so that a dielectric layer having the composition shown in each table below could be obtained. The mixing ratio of the crystallized glass powder and the ceramic powder was controlled so that the area proportion of each phase shown in each table below would be the proportion shown in each table below.

[0077] Next, 19.4 parts by mass of acrylic resin, 59.1 parts by mass of toluene, 3 parts by mass of ethanol, and 6.5 parts by mass of a plasticizer (butylphthalyl butyl glycolate) were mixed together to prepare an organic vehicle.

[0078] Then, the weighed raw material powders were blended with the prepared organic vehicle and mixed for 24 hours using a ball mill to prepare a dielectric layer paste for forming the dielectric layer.

[0079] Separately from the dielectric layer paste, an internal electrode layer paste for forming the internal electrode layer was prepared. Specifically, copper powder, which is a conductive material, and the organic vehicle were mixed and mixed for 24 hours using a ball mill to prepare the internal electrode layer paste for forming the internal electrode layer.

[0080] The external electrode paste was prepared in the same manner as the internal electrode layer paste.

[0081] The prepared dielectric layer paste was then applied to a PET film to form a green sheet. At this time, the thickness of the dielectric layer in the multilayer ceramic capacitor obtained by firing was set to 20 μm. Next, a predetermined pattern of internal electrode layers was printed on the green sheet using the internal electrode layer paste. At this time, the thickness of the internal electrode layers in the multilayer ceramic capacitor obtained by firing was set to 2 μm. The green sheet was then peeled off from the PET film to produce a green sheet on which the internal electrode layers were printed in the predetermined pattern. Next, multiple green sheets on which the internal electrode layers were printed in the predetermined pattern were stacked and pressure-bonded to form a green laminate. Furthermore, the green laminate was cut into a predetermined shape to obtain a green chip. The number of dielectric layers stacked was 5.

[0082] The obtained green chip was subjected to a binder removal process. The temperature increase and decrease rates during the binder removal process were both 200°C / hour. The atmosphere during the binder removal process was a reducing atmosphere. The holding temperature during the binder removal process, the holding time during the binder removal process, and the dew point of the atmospheric gas during the binder removal process are shown in the tables below. The carbon amount, which will be described later, was measured twice, once after the binder removal process and once after firing, which will be described later.

[0083] After the binder removal process, the green chips were fired. The firing conditions for samples 2 to 5 and 7 to 12 were a temperature rise rate of 6000°C / hour, a holding temperature of 860°C, a holding time of 2 hours, and a temperature drop rate of 6000°C / hour. The dew point of the atmospheric gas in the reducing atmosphere during firing was 15°C. The oxygen partial pressure of the atmospheric gas was 7.2 x 10 -15 It was an ATM.

[0084] The firing conditions for sample number 6 were a temperature increase rate of 6000°C / hour, a holding temperature of 880°C, a holding time of 30 minutes, and a temperature decrease rate of 6000°C / hour.

[0085] Furthermore, external electrode paste was applied to two of the side surfaces of the green chip that faced each other and on which the internal electrode layers were exposed, and baked to form external electrodes, thereby producing a multilayer ceramic capacitor sample.

[0086] The composition of the dielectric layer of the multilayer ceramic capacitor sample was confirmed using a Hitachi High-Tech FESEM-EDS (S4800) to be the composition shown in Table 1. More specifically, the green chip after firing was cut along the lamination direction to obtain a cross section, and the approximate center of the dielectric layer (the part roughly equidistant from the upper and lower internal electrode layers) was observed at a magnification of 3000x, and composition analysis was performed to confirm this.

[0087] In addition, each of the tables described below, such as Table 1, shows values ​​obtained by averaging the results of composition analysis at three to five different locations.

[0088] The carbon content of the dielectric was measured using a carbon / sulfur analyzer (CS844) manufactured by LECO Japan LLC. The dielectric to be measured for carbon content was pulverized in an agate mortar to obtain dielectric powder, and the carbon content was measured using the above-mentioned device. Carbon content measurements were performed three times for each measurement level. The carbon content obtained from the three measurements was averaged to determine the carbon content for each measurement level.

[0089] The sintered dielectrics were each molded into rod-shaped samples (1 mm x 1 mm x 80 mm), and the relative permittivity (εr) was measured using the cavity resonator perturbation method. The measurement frequency was 4.7 GHz. The relative permittivity measurement was performed three times for each measurement level. The relative permittivity obtained from the three measurements was averaged to determine the relative permittivity for each measurement level. The results are shown in the tables. A relative permittivity of 20.0 or less was considered good, and a permittivity of 10.0 or less was considered even better.

[0090] The Q value of the sintered dielectric was measured under the same conditions as those for measuring the relative permittivity. The Q value was multiplied by the resonant frequency fr to determine the Qf value. The results are shown in the tables. A Qf value of 5500 GHz or higher was considered good, and a Qf value of 6500 GHz or higher was considered particularly good.

[0091] The crack occurrence rate was calculated by preparing 10 multilayer ceramic capacitor samples for each example / comparative example, and checking each multilayer ceramic capacitor sample for the presence or absence of cracks using a KEYENCE VHX-X1 digital microscope. The results are shown in the tables. A good rating was given when the rate of cracked multilayer ceramic capacitor samples was less than 20%, i.e., when there was one or fewer multilayer ceramic capacitor samples with cracks. An even better rating was given when the rate of cracked multilayer ceramic capacitor samples was less than 10%, i.e., when there were zero multilayer ceramic capacitor samples with cracks.

[0092] The microstructure of the dielectric layer of each sample was examined by using the above-mentioned FESEM-EDS to observe a cross section of the multilayer ceramic capacitor sample cut along the stacking direction. More specifically, in a cross section obtained by cutting the sintered green chip along the stacking direction, the approximate center of the dielectric layer (the part roughly equidistant from the upper and lower internal electrode layers) was observed at 3000x magnification, and an SEM-EDS mapping image was obtained. The positions of the glass-ceramic phase and other ceramic phases were identified from the mapping image.

[0093] Furthermore, it was confirmed whether each phase was crystallized. Specifically, each phase was identified by obtaining an electron diffraction image using a JEOL JSM-2200FS transmission microscope. If each phase is crystallized, a diffraction spot is observed in the electron diffraction image. If each phase is not crystallized, no diffraction spot is observed in the electron diffraction image. The electron diffraction image was used to confirm whether each glass-ceramic phase was a glass-ceramic crystalline phase or a glass-ceramic amorphous phase.

[0094] In this experimental example, the electron diffraction image confirmed that all of the other ceramic phases were ceramic crystalline phases. It was also confirmed that the SrTiO3 content in the entire other ceramic phases contained in the dielectric layer was 10 mass% or more. In other words, it was confirmed that the other ceramic phases contained in the dielectric layer contained a large amount of SrTiO3 phase.

[0095] Then, the area ratio of each phase was calculated from the element mapping image using image analysis software. The results are shown in the tables. The denominator of the area ratio of each phase does not include the area of ​​voids contained in the dielectric composition.

[0096] Each table described later, such as Table 1, shows values ​​obtained by averaging the area ratio of each phase in element mapping images at three to five different locations.

[0097] [Table 1]

[0098] [Table 2]

[0099] As can be seen from Tables 1 and 2, sample numbers 5 to 12, which have a carbon content of 500 ppm or less and a glass ceramic crystalline phase area ratio of 40% or more, all had good εr and Qf values ​​and low crack occurrence rates. In contrast, sample numbers 2 to 4, which have a carbon content of more than 500 ppm, all had low Qf values.

[0100] (Experimental Example 2) The binder removal conditions were standardized to those shown in Table 3, and the firing conditions and / or the mixing ratio of the crystallized glass powder and the ceramic powder were controlled, but the same procedures were carried out as in Experimental Example 1. The results are shown in Tables 3 and 4.

[0101] The firing conditions were as follows: temperature rise rate 2000-10000°C / hour, holding temperature 860-900°C, holding time 30-60 minutes, and temperature drop rate 2000-10000°C / hour. The firing atmosphere was a reducing atmosphere, and the dew point of the atmospheric gas during firing was controlled within the range of 10-25°C. The oxygen partial pressure of the atmospheric gas was 5.0 x 10 -15 ~9.0×10 -15 It was within the ATM range.

[0102] To further promote the crystallization of the glass ceramic (precipitation of crystals within the glass ceramic), the holding temperature during firing was increased, the holding time was extended, and the dew point of the atmospheric gas was set to approximately 15°C. In this case, the crystallization of the glass ceramic was more likely to proceed. In samples 14 and 19, the crystallization of the glass ceramic was allowed to proceed until the glass ceramic phase was entirely converted to a glass ceramic crystalline phase. In sample 18, no ceramic powder was used at all.

[0103] [Table 3]

[0104] [Table 4]

[0105] As can be seen from Tables 3 and 4, sample numbers 13 to 16, 19, and 20, which have carbon contents of 500 ppm or less and glass ceramic crystalline phase area ratios of 40% or more, all had good εr and Qf values ​​and low crack occurrence rates. In contrast, sample numbers 17 and 18, which have glass ceramic crystalline phase area ratios of less than 40%, both had low Qf values.

[0106] (Experimental Example 3) In Samples 21 to 24, the ceramic powder mainly contained the types of ceramic powder shown in Table 6 instead of SrTiO3 used in Experimental Example 1. The alumina filler was the same as in Experimental Example 1. In Experimental Example 25, a crystallized glass powder containing 15 to 35 mass% SiO2 and 30 to 60 mass% MgO was prepared as the glass powder. That is, the glass ceramic crystalline phase was mainly the forsterite phase. In Experimental Example 26, a crystallized glass powder containing 45 to 65 mass% SiO2 and 25 to 45 mass% MgO was prepared as the glass powder. That is, the glass ceramic crystalline phase was mainly the steatite phase.

[0107] The binder removal treatment conditions are shown in Table 5. Regarding the firing conditions, in accordance with the changes in the ceramic powder and crystallized glass powder, the temperature rise rate was controlled within the range of 20 to 300°C / hour, the holding temperature was 600 to 700°C, the holding time was 2 to 20 hours, and the temperature drop rate was controlled within the range of 100 to 300°C / hour. The firing atmosphere was a reducing atmosphere, and the dew point of the atmospheric gas during firing was controlled to 70 to 100°C. The oxygen partial pressure of the atmospheric gas was 2.5 x 10 -18 ~7.5×10 -13 It was within the ATM range.

[0108] [Table 5]

[0109] [Table 6]

[0110] From Tables 5 and 6, all of sample numbers 21 to 26, which had a carbon content of 500 ppm or less and an area ratio of the glass ceramic crystal phase of 40% or more, had good εr and Qf values ​​and a low crack occurrence rate. [Explanation of symbols]

[0111] 1. Multilayer ceramic capacitors 2. Dielectric layer 3 Internal electrode layer 4 External electrode 10 Capacitor element body

Claims

1. A dielectric composition comprising a glass ceramic crystalline phase in an area ratio of 40% or more in any cross section, and a carbon content of 500 ppm or less.

2. 2. The dielectric composition according to claim 1, wherein the glass ceramic crystalline phase is contained in an area ratio of 40% to 80%.

3. 3. The dielectric composition according to claim 1, wherein the area ratio of the glass ceramic amorphous phase in any cross section is 0% or more and 20% or less.

4. 3. The dielectric composition according to claim 1, wherein the carbon content is 300 ppm or less.

5. 3. The dielectric composition according to claim 1, wherein the glass-ceramic crystalline phase is a diopside phase.

6. A laminated electronic component having a laminated portion in which dielectric layers and internal electrode layers are alternately laminated, the dielectric layers comprising the dielectric composition according to claim 1 or 2.

7. The laminated electronic component according to claim 6, wherein the internal electrode layers contain Cu.

8. 7. The method for producing a laminated electronic component according to claim 6, further comprising a step of carrying out a binder removal treatment in a reducing atmosphere at a temperature of 650° C. or less and a dew point of 70° C. or more.

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