Electronic components

Abstract

To provide an electronic component that can suppress the occurrence of cracks in high-temperature and high-humidity environments. [Solution] An electronic component having an element body containing an insulating layer and an electrode layer. The concentration of Mn in the central region of the electrode layer, located near the center of the element body, is higher than the concentration of Mn in the terminal region of the electrode layer, located near the end face of the element body.

Description

[Technical Field]

[0001] The present invention relates to an electronic component having an element body that contains an insulating layer and an electrode layer inside. [Background technology]

[0002] For example, electronic components such as multilayer ceramic capacitors have an element body containing an insulating layer such as a dielectric and an electrode layer. Along the stacking direction within the element body, stress acts on the central and peripheral areas due to differences in the coefficient of thermal expansion, which can cause cracks to occur at the interface between the insulating layer and the electrode layer.

[0003] In Patent Document 1 shown below, it is being investigated how to suppress the occurrence of thermal cracks while maintaining good temperature characteristics by controlling the Mn concentration along the stacking direction. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent application No. 2024-057740 [Overview of the project] [Problems that the invention aims to solve]

[0005] The objective of the present invention is to provide an electronic component that can suppress the occurrence of cracks in high-temperature and high-humidity environments. [Means for solving the problem]

[0006] The inventors diligently studied how to suppress crack formation in high-temperature and high-humidity environments and, as a result, discovered that controlling the Mn concentration from the edges of the electrode layer inside the element body toward the center of the element body is important, leading to the completion of the present invention.

[0007] An electronic component according to one aspect of the present invention is An electronic component having an element body that contains an insulating layer and an electrode layer inside, The concentration of Mn in the central region of the electrode layer, located near the center of the element body, is higher than the concentration of Mn in the terminal region of the electrode layer, located near the end face of the element body.

[0008] Generally, electrode layers containing metals such as Ni are difficult to bond with insulating layers such as dielectric layers, and cracks are likely to occur at the interface between the electrode layer and the insulating layer. According to the inventors' new findings, it is expected that including Mn in the electrode layer will make it easier for the electrode layer to bond with the insulating layer, thus effectively suppressing cracks. However, because Mn is easily oxidized, there is a risk that it may also oxidize the metal components of the electrode layer, especially at the edges of the electrode layer (near the end face of the device body).

[0009] In an electronic component according to one aspect of the present invention, the concentration of Mn in the center is higher than the concentration of Mn at the edges, which increases the bonding strength between the electrode layer and the insulating layer, suppresses oxidation at the electrode edges, and in particular suppresses cracking under high temperature and high humidity conditions.

[0010] The peripheral concentration of Mn, C1, may be 0.01 to 0.15 atm%, and more preferably 0.02 to 0.08 atm%. Furthermore, when the central concentration of Mn is C2, the ratio C2 / C1 may be 1.1 to 20.0, or 1.5 to 20.0, and preferably 3.0 to 15.0. The effect is particularly strong within this range.

[0011] Preferably, in the electrode layer, there is a steep region between the terminal region and the central region where the concentration of Mn increases rapidly and changes, and this steep region may be continuous with the terminal region. This concentration distribution is particularly effective.

[0012] Preferably, the steep region appears within a range of 400 μm from the end face of the element body. This effect is particularly significant when such a concentration distribution is present.

[0013] Preferably, in the steep region, the rate of change (slope) of the Mn concentration is 0.1 atm% / mm or more with respect to the distance (mm) from the end face of the element body along the electrode layer. When having such a concentration distribution, the effect is particularly large.

[0014] Preferably, in the electrode layer, between the terminal region and the central region, there is an equilibrium region where the change in the Mn concentration is small, and the equilibrium region is continuous with the central region. When having such a concentration distribution, the effect is particularly large.

[0015] Preferably, the equilibrium region is observed in a range exceeding 400 μm from the end face of the element body. When having such a concentration distribution, the effect is particularly large.

[0016] Preferably, in the equilibrium region, the rate of change of the Mn concentration with respect to the distance (mm) from the end face of the element body along the electrode layer is smaller than the rate of change (slope) of the Mn concentration in the steep portion.

[0017] The end-side concentration may be the average value of the Mn concentrations at three or more measurement points spaced apart from each other at a predetermined interval along the electrode layer within the terminal region.

[0018] The central-side concentration may be the average value of the Mn concentrations at three or more measurement points spaced apart from each other at a predetermined interval along the electrode layer within the central region.

[0019] Preferably, a two-dimensional coordinate system is set with the distance from the end face of the element body along the electrode layer as the x-axis and the Mn concentration in the electrode layer at each measurement point along the x-axis as the y-axis. When performing a linear approximation for y in the range where x is 20 μm to 100 μm, the slope of the approximate straight line in the two-dimensional coordinate system is 0.2 atm% / mm or more, and the coefficient of determination is 0.75 or more. When having such a concentration distribution, the effect is particularly large.

[0020] The main component of the conductive material contained in the electrode layer may be Ni and / or a Ni-based alloy. This configuration is particularly effective.

[0021] The insulating layer may also be a dielectric layer containing Ca and Zr. This configuration is particularly effective. [Brief explanation of the drawing]

[0022] [Figure 1A] Figure 1A is a schematic diagram showing a cross-section of a multilayer ceramic capacitor according to one embodiment of the present invention. [Figure 1B] Figure 1B is a schematic diagram showing a cross-section of a multilayer ceramic capacitor according to another embodiment of the present invention. [Figure 2] Figure 2 is a graph showing an approximate curve of the Mn ratio in the internal electrodes of a multilayer ceramic capacitor according to one embodiment of the present invention. [Modes for carrying out the invention]

[0023] The embodiments will be described below.

[0024] First Embodiment As shown in Figure 1A, a multilayer ceramic capacitor 1, an example of an electronic component according to this embodiment, has an element body 10 in which an internal dielectric layer 2 as an insulating layer and an internal electrode layer 3 are alternately stacked. External electrodes 4 are formed on each end face 10a along the X axis of this element body 10.

[0025] There are no particular restrictions on the shape of the element body 10, but it is usually rectangular. However, the shape of the element body 4 is not particularly restricted and may be elliptical, cylindrical, or other prismatic shapes. Furthermore, there are no particular restrictions on the dimensions of the element body 10, and it may be set to appropriate dimensions depending on the application. For example, the length in the X-axis direction can be 0.4 mm to 5.7 mm, the width in the Y-axis direction can be 0.2 mm to 5.0 mm, and the height T0 in the Z-axis direction can be 0.05 mm to 3.0 mm. In this embodiment, the X, Y, and Z axes are perpendicular to each other.

[0026] Of the numerous internal electrode layers 3, one of a pair of internal electrodes 3 facing each other in the stacking direction is connected to one external electrode 3 at one end face 10a of the element body 10, and the other of the pair of internal electrodes 3 is connected to the other external electrode 3 at the other end face 10a of the element body 10.

[0027] More specifically, the internal electrode layers 3 are stacked such that each end is exposed on the opposite end face 10a along the X-axis of the element body 10. The internal electrode layers 3 are stacked via the dielectric layer 2 such that one end of each internal electrode layer 3 alternately exposes two opposing end faces 10a of the element body 10 in the X-axis direction. A pair of external electrodes 4 are formed on one end face of the element body 10 and are electrically connected to the alternately arranged exposed ends of the internal electrode layers 3. By forming the internal electrode layers 3 and external electrodes 4 in this way, a capacitor circuit is constructed.

[0028] There are no particular restrictions on the composition of dielectric layer 2, but in this embodiment, it is preferable that the main component contains Ca and / or Sr and Zr, more preferably Ca and Zr, or preferably mainly Ca, Sr, Zr and Ti. For example, it may be a perovskite compound in which Ca alone or Ca and Sr are included as the A site element, and Zr alone or Zr and Ti are included as the B site element. A perovskite compound is a compound having a perovskite-type crystal structure represented by the general formula ABO3 (where A is the A site element and B is the B site element).

[0029] In a case where the dielectric layer 2 contains a perovskite compound containing Ca and Sr as A-site elements and Zr and Ti as B-site elements, the total content of Ca and Sr relative to the total A-site elements of the perovskite compound may be 50 at% or more. The total content of Zr and Ti relative to the total B-site elements of the perovskite compound may be 90 at% or more.

[0030] More specifically, the dielectric layer 2 has the composition formula (Ca 1-x Sr x ) m (Zr 1-y-z Ti y Hf z )This may be a compound that can be represented as O3 (hereinafter referred to as a CSZT compound).In the above compositional formula, the symbols x, y, z, and m each indicate the elemental ratio, and the ratio of each element is not particularly limited and can be set within a known range.

[0031] For example, m represents the elemental ratio of site A to site B, and can generally be in the range of 0.9 to 1.1. Also, x represents the elemental ratio of Sr in site A, and can be 0 ≤ x ≤ 1. In other words, the ratio of Ca to Sr is arbitrary, and it may contain only one of them.

[0032] y represents the elemental ratio of Ti in the B site, and z represents the elemental ratio of Hf in the B site. That is, 1-yz represents the elemental ratio of Zr in the B site. In this embodiment, it is preferable that 0.80 ≤ 1-yz ≤ 1.0. Note that the elemental ratio of oxygen (O) in the above compositional formula may be slightly deviated from the stoichiometric composition.

[0033] In addition to the perovskite compound, the dielectric layer 2 may also contain, for example, SiO2 and / or Al2O3. Specifically, it may contain 0 to 4.0 moles of Si per 100 moles of the B-site element of the perovskite compound. Furthermore, the dielectric layer 2 may contain 0 to 2.0 moles of Al per 100 moles of the B-site element of the perovskite compound.

[0034] The dielectric layer may also contain other minor components. Examples of other minor components include Mn compounds, Mg compounds, Ni compounds, Li compounds, and B compounds, and the type, combination, and amount of these minor components are not particularly limited.

[0035] The thickness of each layer of the internal dielectric layer 2 (interlayer thickness) is not particularly limited and can be arbitrarily set according to the desired characteristics and applications. For example, the interlayer thickness may be 0.5 μm or more and 20 μm or less, 1 μm or more and 20 μm or less, or 3.0 μm or more and 15 μm or less.

[0036] The conductive material contained in the external electrode 4 is not particularly limited. For example, known conductive materials such as Ni, Cu, Sn, Ag, Pd, Pt, Au, or alloys thereof, or conductive resins may be used. The thickness of the external electrode 4 may be determined appropriately depending on the application.

[0037] In this embodiment, the main component of the conductive material contained in the internal electrode layer 3 is a metal (including alloys). The metal is not particularly limited, and for example, Cu, Ni, Ag, Pd, Au, Pt, or an alloy containing at least one of these metallic elements can be used, preferably Ni and / or a Ni-based alloy.

[0038] "The main component of the conductive material contained in the internal electrode layer 3" refers to "the component in which, when the total amount of each element constituting the conductive material contained in the internal electrode layer 3 is set to 100 mole parts, the total amount of each element constituting the main component of the conductive material contained in the internal electrode layer 3 is 80 mole parts or more."

[0039] The internal electrode layer 3 may contain various trace components such as P in amounts of approximately 0.1% by mass or less. The thickness of the internal electrode layer 3 can be appropriately determined according to the application. There are no particular restrictions on the number of layers of the internal electrode layer 3. It may be 40 to 400, or 50 to 300.

[0040] In the multilayer ceramic capacitor of this embodiment, the internal electrode layer 3 contains Mn. In the internal electrode layer 3 containing Mn, the central concentration of Mn in the central region R2 of the internal electrode layer 3, located near the center of the element body 10, is higher than the central concentration C1 of Mn in the terminal region R1 of the internal electrode layer 3, located near the end face 10a of the element body 10.

[0041] The terminal region R1 of the internal electrode layer 3 is, when there are multiple internal electrode layers 3 arranged in the stacking direction (parallel to the Z-axis), a predetermined range (for example, 0 to 20 μm) along the internal electrode layer 3 from the end face 10a of the element body 10, for the internal electrode layer 3 closest to the center along the Z-axis. The Mn end-side concentration C1 is measured within the terminal region R1 for the internal electrode layer 3 as the average value of the Mn concentrations at three or more measurement points separated from each other at predetermined intervals along the internal electrode layer 3.

[0042] The central region R2 of the internal electrode layer 3 is a region within a predetermined range (e.g., 0 to 20 μm) along the internal electrode layer 3, including the center position along the X-axis (or Y-axis) of the cross-section of the element body 10, for the same internal electrode layer 3 from which the edge concentration was measured. The central concentration C2 of Mn is measured within the central region R2 for the internal electrode layer 3 as the average value of the Mn concentrations at three or more measurement points separated from each other at predetermined intervals along the internal electrode layer 3. The measurement method will be described later.

[0043] Generally, internal electrode layers containing metals such as Ni are difficult to bond with insulating layers such as dielectric layers, and cracks are likely to occur at the interface between the internal electrode layer and the internal dielectric layer. According to the inventors' new findings, it is expected that including Mn in the internal electrode layer 3 will make it easier for the internal electrode layer to bond with the dielectric layer, thereby effectively suppressing cracks. However, because Mn is easily oxidized, there is a risk that it may also oxidize the metallic components of the internal electrode layer, especially at the edges of the internal electrode layer (near the end face of the device body).

[0044] In the multilayer ceramic capacitor 1 according to this embodiment, the concentration of Mn in the center C2 is higher than the concentration of Mn in the edges C1. This increases the bonding strength between the internal electrode layer 3 and the internal dielectric layer 2, while suppressing oxidation at the edges of the internal electrode layer 3, and making it possible to suppress cracks, especially under high temperature and high humidity conditions.

[0045] The coverage rate is the ratio of the total length of the internal electrode layer 3 along the stacking interface to the total length of the dielectric layer 2 along the stacking interface, when observing a pair of contacting dielectric layers 2 and internal electrode layers 3 in a predetermined field of view (YZ plane or ZX plane) of a cross section parallel to the stacking direction (Z axis direction) of the element body 10. The length in the stacking direction of the predetermined field of view should be such that a pair of contacting dielectric layers 3 and internal electrode layers 2 can be observed. The length in the direction parallel to the stacking direction of the predetermined field of view should be approximately 10 μm to 500 μm. It is preferable to observe in approximately 5 fields of view that satisfy the predetermined field of view and calculate the average value of the internal electrode layer coverage rate.

[0046] The Mn end-side concentration C1 may be 0.01 to 0.15 atm%, and more preferably 0.02 to 0.08 atm%. The C2 / C1 ratio may be 1.1 to 20.0, or 1.5 to 20.0, and preferably 3.0 to 15.0. The effect is particularly strong within this range.

[0047] In this embodiment, as shown in Figure 2, in the internal electrode layer 3, there is a steep region R3 between the terminal region R1 and the central region R2 where the concentration of Mn increases and changes rapidly, and the steep region R3 may be continuous with the terminal region R1. The effect is particularly great when such a concentration distribution is present.

[0048] As shown in Figure 2, the steep region R3 appears within a range of 400 μm from the end face 10a of the element body 10 shown in Figure 1A toward the center, specifically in the ranges of 20-400 μm, 20-350 μm, 20-300 μm, 20-200 μm, and 20-100 μm. The effect is particularly large when such a concentration distribution is present.

[0049] In the steep region R3, it is preferable that the rate of change of Mn concentration (slope a1) with respect to the distance (mm) from the end face of the element body along the electrode layer is 0.1 atm% / mm or more, 0.2 atm% / mm or more, 0.3 atm% / mm or more, 0.5 atm% / mm or more, or 0.6 atm% / mm or more. The effect is particularly large when such a concentration distribution is present.

[0050] In this embodiment, in the internal electrode layer 3, an equilibrium region R4 exists between the terminal region R1 and the central region R2, where the change in Mn concentration is small, and the equilibrium region R4 may be continuous with the central region R2. This concentration distribution is particularly effective. The equilibrium region R4 is already observed in the range beyond 400 μm from the end face 10a of the element body 10 shown in Figure 1A, and the transition from the steep region R3 to the equilibrium region R4 may occur within the range from 100 μm to 400 μm inward from the end face 10a. This concentration distribution is particularly effective.

[0051] In the equilibrium region R4, the rate of change of Mn concentration (slope a2) with respect to the distance (mm) from the end face 10a of the element body 10 along the internal electrode layer 3 is smaller than the rate of change of Mn concentration (slope) in the steep region R3, and is preferably within ±0.08 atm% / mm, ±0.05 atm% / mm, or ±0.03 atm% / mm. The effect is particularly large when such a concentration distribution is present.

[0052] In this embodiment, a two-dimensional coordinate system is set up with the distance from the end face 10a of the element body along the internal electrode layer 3 as the x-axis, and the concentration of Mn in the electrode layer at each measurement point along the x-axis as the y-axis. When linear approximation is performed for y in the range of x from 20 μm to 100 μm, The slope of the approximate line in two-dimensional coordinates is 0.2 atm% / mm or greater, and the coefficient of determination is 0.75 or greater.

[0053] Specifically, as shown in Figure 2, the distance from the end face (exposed end of the internal electrode layer) 10a of the element body 4 is plotted on the x-axis (horizontal axis), and the concentration of Mn is plotted on the y-axis (vertical axis), and the concentration of Mn at the measurement point is plotted. For example, in the steep region R3, when linear approximation (straight line approximation) is performed using the least squares method based on data where x is in the range of 20 μm to 100 μm, such that y = a1·x + b1, it is preferable that the slope a1 is within the above range. It is also preferable that the coefficient of determination R2 is 0.75 or higher, or 0.8 or higher.

[0054] Furthermore, it is preferable that the Mn concentration is substantially constant in the equilibrium region R4 of the internal electrode layer 3. That is, in the two-dimensional coordinate system shown in Figure 2, when a linear approximation is performed based on data where x is 400 μm or more in the equilibrium region R4 of the internal electrode layer, i.e., y = a²·x + b², it is preferable that the slope a² is between -0.08 at% / mm and +0.08 at% / mm, as mentioned above.

[0055] In a preferred embodiment, the main component of the conductive material contained in the internal electrode layer 3 is Ni and / or a Ni-based alloy. This configuration is particularly effective. Furthermore, the internal dielectric layer 2 contains Ca and Zr. This configuration is also particularly effective.

[0056] There are no particular restrictions on the method for measuring the concentration of Mn along the longitudinal direction of the cross-section of the internal electrode layer 3, including the edge concentration C1 and the central concentration C2 of Mn. For example, one method is to measure the Mn concentration by measuring the intensity of characteristic X-rays of Mn using an electron beam microanalyzer (EPMA), SEM-EDS, or STEM-EDS.

[0057] The intensity of characteristic X-rays of Mn is proportional to the Mn concentration. Therefore, by performing line analysis of the intensity of characteristic X-rays of Mn along the thickness direction of the external electrode 4 (along the X-axis in Figure 1A) within the internal electrode layer 3, and averaging the measured values ​​of the number of bars within the region, the Mn concentration in each region can be calculated. If there are multiple layers of internal electrode layers 3, C1, C2, etc., may be calculated by averaging the Mn concentrations of each region of 2 to 5 internal electrode layers 3 near the center along the Z-axis.

[0058] In the line analysis described above, the spacing between characteristic X-ray measurement points along the X-axis (or Y-axis) can be made sufficiently short, specifically, it may be 2 μm or less. In this embodiment, the concentration of Mn is measured as the atom% of Mn when the sum of the main metal element component contained in the internal electrode layer 3, for example Ni, and Mn is 100 atm%.

[0059] Next, an example of a manufacturing method for the multilayer ceramic capacitor 2 shown in Figure 1A will be described.

[0060] First, let's explain the manufacturing process for the main body of the element 4. In the manufacturing process for the main body of the element 4, a dielectric paste that will become the internal dielectric layer 2 after firing and an internal electrode paste that will become the internal electrode layer 3 after firing are prepared.

[0061] Dielectric pastes are manufactured, for example, by the following method: First, dielectric raw materials are uniformly mixed by means of wet mixing or other means and dried. Then, calcined powder is obtained by heat treatment under predetermined conditions. Next, a known organic vehicle or a known aqueous vehicle is added to the obtained calcined powder and kneaded to prepare a dielectric paste.

[0062] The dielectric paste thus obtained is formed into a sheet using a method such as the doctor blade method to obtain a ceramic green sheet. The dielectric paste may contain additives selected from various dispersants, plasticizers, dielectrics, minor component compounds, glass frit, etc., as needed.

[0063] Next, an internal electrode paste is applied to the ceramic green sheet in a predetermined pattern using various printing or transfer methods such as screen printing to form the internal electrode pattern. The internal electrode paste is composed of a base containing conductive particles made of, for example, metal (including alloys) such as Ni, and can be formed by adding a known organic vehicle or a known aqueous vehicle to the conductive particles and kneading them together.

[0064] In this embodiment, the method for achieving the concentration pattern of Mn in the internal electrode layer 3 as shown in Figure 2 is not particularly limited, but two methods described below are examples.

[0065] One example of a manufacturing method is the sputtering method. Specifically, Mn is deposited on the surface of the pattern of the internal electrode paste by sputtering, from the edges to the center of a green sheet on which the pattern of the internal electrode paste is printed, so that, for example, after firing, there is a gradient of Mn concentration as shown in Figure 2.

[0066] A second method involves dividing the printing of the internal electrode paste. Specifically, internal electrode paste with varying Mn concentrations is printed separately from the center to the edges of the internal electrode paste pattern, while maintaining a continuous paste pattern.

[0067] In this manner, multiple layers of ceramic green sheets, each with a pattern for internal electrode paste, are stacked and then pressed in the stacking direction to obtain a mother stack. At this time, outer ceramic green sheets are stacked so that ceramic green sheets are positioned on the top and bottom surfaces of the mother stack in the stacking direction.

[0068] The mother laminate obtained through the above process is cut to predetermined dimensions by dicing or press cutting to obtain multiple green chips. The green chips may be solidified and dried as needed to remove plasticizers, etc., or they may be barrel polished using a horizontal centrifugal barrel machine or the like after solidification and drying. In barrel polishing, the green chips are placed in a barrel container along with media and polishing fluid, and unwanted parts such as burrs generated during cutting are polished by applying rotational motion or vibration to the barrel container. After barrel polishing, the green chips are washed with a cleaning solution such as water and dried.

[0069] Next, the green chip obtained above is subjected to a binder removal treatment and a firing treatment to obtain the element body 10. The conditions for the binder removal treatment can be appropriately determined according to the main component composition of the dielectric layer 2 and the main component composition of the internal electrode layer 3, and are not particularly limited. For example, the heating rate is preferably 5°C / hour to 300°C / hour, the holding temperature is preferably 180°C to 400°C, and the temperature holding time is preferably 0.5 hours to 24 hours. The binder removal atmosphere is air or a reducing atmosphere.

[0070] The firing conditions can be appropriately determined according to the main component composition of the dielectric layer 2 and the main component composition of the internal electrode layer 3, and are not particularly limited. For example, the holding temperature during firing is preferably 1100°C to 1400°C, more preferably 1220°C to 1300°C, the holding time is preferably 0.5 hours to 8 hours, more preferably 1 hour to 3 hours, and the heating rate and cooling rate (cooling rate) are preferably 50°C / hour to 500°C / hour. Furthermore, the firing atmosphere is preferably a reducing atmosphere, and as the atmosphere gas, for example, a humidified mixed gas of N2 and H2 can be used. In addition, when the internal electrode layer 3 is composed of a base metal such as Ni or a Ni-based alloy, the oxygen partial pressure in the firing atmosphere should be 2.0 × 10⁻⁶ -13 atm~1.0×10 -7 It is preferable to use ATM.

[0071] After firing, the obtained element body 10 may be subjected to re-oxidation treatment (annealing) as needed. The annealing conditions may be, for example, that the oxygen partial pressure during annealing is higher than the oxygen partial pressure during firing, and the holding temperature is 1150°C or lower.

[0072] In the debindering, firing, and annealing processes described above, a wetter or similar device can be used to humidify the N2 gas or mixed gas, and in this case, the water temperature is preferably around 5°C to 75°C. Furthermore, the debindering, firing, and annealing processes may be performed continuously or independently.

[0073] The element body 10 obtained as described above is subjected to end face polishing, and an external electrode paste is applied and baked to form the external electrode 4. Then, if necessary, a coating layer is formed on the surface of the external electrode 4 by plating or the like.

[0074] Through the above process, a multilayer ceramic capacitor 2 having external electrodes 4 is obtained.

[0075] The resulting multilayer ceramic capacitor 2 can be surface-mounted onto a substrate such as a printed circuit board using solder (including molten solder, solder cream, and solder paste) or a conductive adhesive, and can be used in various electronic devices. Alternatively, the multilayer ceramic capacitor 2 can also be mounted on a substrate via wire-shaped lead terminals or plate-shaped metal terminals.

[0076] In particular, when the internal electrode layer 3 contains Ni (including Ni-based alloys), the Mn contained on or inside the internal electrode layer 3 readily forms an alloy with the Ni contained in the internal electrode layer 3. This alloying of Mn and Ni is thought to increase the bonding strength between the internal electrode layer 3 and the internal dielectric layer 2, thereby suppressing the occurrence of cracks.

[0077] Furthermore, electronic components in which the internal dielectric layer 2 is composed of a CSZT-based compound tend to be used in high-frequency systems because their dielectric constant has a lower temperature change rate compared to electronic components in which the internal dielectric layer 2 is composed of barium titanate (hereinafter referred to as "BT-based compound").

[0078] Thus, in high-frequency systems, it is preferable to use an internal dielectric layer 2 composed of a CSZT compound. However, since the difference in the coefficient of linear expansion between the CSZT compound and Ni is greater than the difference between the coefficient of linear expansion between the BT compound and Ni, assuming that the main component of the conductive material contained in the internal electrode layer 3 is Ni and / or a Ni-based alloy, if the main component of the internal dielectric layer 2 is a CSZT compound, the likelihood of cracks occurring is higher than if the main component of the ceramic layer 12 were a BT compound.

[0079] Furthermore, if the main component of the internal dielectric layer 2 is a CSZT-based compound, the internal dielectric layer 2 may contain Mn, and in particular, Mn may be contained in solid solution in the main phase particles formed by the CSZT-based compound, and Mn may also be contained in the grain boundaries. In this embodiment, the Mn contained in the main phase and / or grain boundaries of the internal dielectric layer 2 and the Mn contained inside the internal electrode layer 3 mutually diffuse, thereby increasing the bonding strength between the internal dielectric layer 2 and the internal electrode layer 3. This makes it possible to further suppress the occurrence of cracks.

[0080] Furthermore, in this embodiment, since the concentration of Mn at the edges is lower than the concentration of Mn at the center, it is possible to increase the bonding strength between the internal electrode layer 3 and the internal dielectric layer 2 while suppressing oxidation at the edges of the internal electrode layer, and in particular suppressing cracks under high temperature and high humidity conditions.

[0081] Second Embodiment As shown in Figure 1B, the multilayer ceramic capacitor 1A, an example of an electronic component according to this embodiment, differs from the multilayer ceramic capacitor 1 of the embodiment shown in Figure 1A above only in the arrangement pattern of the internal electrodes 3a and 3b; other configurations and effects are the same. The following description will mainly focus on the differences from the first embodiment.

[0082] The capacitor 1A of this embodiment has an element body 10 in which two types of internal electrode layers 3a and 3b, each having a different pattern, are alternately stacked via an internal dielectric layer 2. The internal electrode layer 3a is connected to a pair of external electrodes 4 at both ends in the X-axis direction and has an insulated pattern in the middle of the X-axis direction.

[0083] Furthermore, the internal electrode layer 3b covers the insulating portion of the pattern that is insulated midway along the X-axis direction of the internal electrode layer 3a, and has a pattern that is not connected to any of the external electrodes 4 at both ends in the X-axis direction. In this capacitor 1A, the portion of the internal dielectric layer 2 where the internal electrode layer 3a and the internal electrode layer 3b overlap when viewed from the Z-axis direction contributes to the capacitance of the capacitor.

[0084] In this embodiment, the terminal region R1 of the internal electrode layer 3a located near the end face 10a of the element body 10 is identified, for example, with one or more internal electrode layers 3a located near the center along the Z-axis, among a plurality of internal electrode layers 3a stacked along the Z-axis. The central region R2 can be identified as the portion of the internal electrode layer 3a closest to the central position along the X-axis of the element body 10, in an internal electrode layer 3a having a defined Mn concentration and a terminal region R1.

[0085] In this embodiment, the internal electrode layer 3b is not exposed to the end face of the element body 10, so there is no need for a Mn concentration gradient, and a Mn concentration as high as that in the central region R2 may continue substantially uniformly along the X axis.

[0086] Furthermore, if the end of the internal electrode layer 3a or 3b along the Y-axis is exposed from the outer surface of the element body 10, it is preferable that a Mn concentration gradient, as shown in Figure 2, exists not only along the X-axis but also along the Y-axis. In this case, it is preferable that the end of the internal electrode layer 3a or 3b along the Y-axis in the element body 10 is covered with a side margin layer such as a glass film or a ceramic film. In this respect, the same applies to the element body 10 in the first embodiment, where if the end of the internal electrode layer 3 along the Y-axis is exposed from the outer surface of the element body 10, it is preferable that a Mn concentration gradient, as shown in Figure 2, exists not only along the X-axis but also along the Y-axis.

[0087] Although 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.

[0088] For example, in this embodiment, a multilayer ceramic capacitor 2 is exemplified as an electronic component, but the electronic component of the present invention may be, for example, a bandpass filter, a multilayer three-terminal filter, a piezoelectric element, a thermistor, a varistor, or the like.

[0089] In this embodiment, the internal dielectric layer 2 and the internal electrode layer 3 are laminated in the Z-axis direction. However, the lamination direction may be the X-axis direction or the Y-axis direction. In that case, the external electrode 4 may be formed in accordance with the exposed surface of the internal electrode layer 3. Further, the element body 4 does not necessarily have to be a laminate, and may be a single layer. Furthermore, the internal electrode layer 3 may be drawn out to the outer surface of the element body 4 via a through-hole electrode. In this case, the through-hole electrode and the external electrode 4 are electrically joined.

Example

[0090] Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples.

[0091] Example 1 First, raw material powders of perovskite compounds (hereinafter sometimes referred to as main component raw material powders) contained as the main components of the dielectric layer main phase particles were prepared. Specifically, raw material powders of Ca oxide, Sr oxide, Zr oxide, and Ti oxide were prepared and weighed so that a perovskite compound having a composition formula of (Ca 0.70 Sr 0.30 )(Zr 0.97 Ti 0.03 )O3 could be obtained. Then, each powder was dispersed in pure water, dried, and further heat-treated (holding temperature: 1200 to 1250 °C, holding time: 0.5 to 5 hours) to prepare main component raw material powders having a specific surface area measured by the BET method of about 5.0 m 2 / g. The holding temperature and holding time during the heat treatment were appropriately set according to each sample.

[0092] Separately, MnCO3 powder, SiO2 powder, and Al2O3 powder were prepared as sub-components. They were weighed so that the content of Si was larger than the content of Al on an atomic number basis. Also, MnCO3 powder was prepared and weighed so that the content of Mn was 1.5 to 3.0 mole parts.

[0093] Dielectric powder was obtained by dispersing the main component raw material powder and the oxide powder of the minor component elements in pure water, drying the mixture, and then heat-treating it. The holding temperature during heat treatment was 400°C, and the holding time was 0.5 to 5 hours. The holding time during heat treatment was set appropriately according to each sample.

[0094] Dielectric powders and organic vehicles were mixed to prepare various dielectric pastes. 100 parts by mass of dielectric powder, 10 parts by mass of polyvinyl butyral resin, 5 parts by mass of dioctyl phthalate (DOP) as a plasticizer, and 100 parts by mass of alcohol as a solvent were mixed in a ball mill to form a paste, which was used to obtain a dielectric layer paste.

[0095] Next, a paste for the internal electrode was prepared. The method for preparing the internal electrode paste is as follows: First, Ni powder, MnCO3 powder, terpineol, ethylcellulose, and benzotriazole were prepared. These were then kneaded together using a three-roll mixer to form a paste, thereby preparing the internal electrode paste.

[0096] Next, using the dielectric paste and internal electrode paste described above, the internal electrode paste was printed in a predetermined pattern onto the surface of the dielectric green sheet. At this time, Mn was deposited on the pattern surface of the internal electrode paste by sputtering, so that, for example, a gradient of Mn concentration as shown in Figure 2 was formed from the edges to the center of the green sheet on which the pattern of the internal electrode paste was printed (Manufacturing Method A). Green chips were manufactured by laminating green sheets on which the patterns of the internal electrode paste, with Mn deposited in a predetermined pattern, were formed in this manner.

[0097] Then, the green chip was subjected to a binder removal process, a firing process, and an annealing process to obtain a rectangular parallelepiped-shaped element body 10 with dimensions of 3.2 mm × 2.5 mm on the surface perpendicular to the stacking direction and a length of 2.5 mm in the stacking direction.

[0098] The holding temperature for the green chips during firing was 1250°C, the holding time was 2.0 hours, and the atmosphere during firing had an oxygen partial pressure of 2.0 × 10⁻⁶. -13 atm or more 1.0×10 -7 A reducing atmosphere below atm was used. In addition, the obtained device body 10 had 200 layers of internal dielectric layers, and the thickness of the dielectric layer between internal electrode layers was 8 μm.

[0099] Next, an external electrode 4 is formed on the outer surface of the element body 10 in the order described above by forming a Cu-containing baked electrode layer, a Ni-plated layer, and a Sn-plated layer, thereby obtaining a multilayer ceramic capacitor 1.

[0100] (Composition of dielectric ceramic composition) Regarding the composition of the dielectric ceramic composition, the composition of the internal dielectric layer was analyzed using ICP emission spectroscopy. It was confirmed that the composition of the perovskite compound contained in the internal dielectric layer was as described above, and that the content of the additive elements was the same as the content in the dielectric layer paste.

[0101] (Mn concentration) Regarding the Mn concentration in the internal electrode layer 3, the concentration of Mn (atom%) was measured by performing line analysis using STEM-EDS and EPMA mapping on a cross-section in the direction shown in Figure 1A, i.e., a cross-section parallel to the stacking direction and parallel to the thickness direction of the external electrode. This analysis covered a length of 1600 μm from the end of the internal electrode layer 3 in the X-axis direction toward the center of the device body 10 (the region including the terminal region R1, steep region R3, and equilibrium region R4 shown in Figure 2), and the region including the central region R2 shown in Figure 1A.

[0102] The average concentrations of Mn, C1 and C2, were measured in terminal region R1 and terminal region R2, respectively. A concentration difference was defined as "no concentration difference" if the ratio of these concentrations, C2 / C1, was less than 1.1, and a concentration difference was defined as "a concentration difference exists" if the ratio, C2 / C1, was 1.1 or greater. The results are shown in Table 1. Figure 2 shows an example of line analysis results in the region of the internal electrode layer 3, including terminal region R1, steep region R3, and equilibrium region R4.

[0103] Furthermore, from the two-dimensional coordinate graph shown in Figure 2 obtained from the measurement results, the slope a1 was calculated by performing a linear approximation (straight line approximation) using the least squares method based on data where x is in the range of 20 μm to 100 μm (including the steep region R2) such that y = a1·x + b1.

[0104] Similarly, based on data from the equilibrium region R4 of the internal electrode layer 3, i.e., where x is 400 μm or greater, a linear approximation was performed so that y = a2·x + b2, and the slope a2 was calculated. Furthermore, for the steep region R2 where slope a1 was obtained, the coefficient of determination R2 was also determined using statistical methods. These results are shown in Table 1A.

[0105] (Visual inspection and PCT testing) One hundred capacitor samples, manufactured under the same conditions, were visually inspected to check for cracks. The results are shown in Table 1A.

[0106] Furthermore, for 100 capacitor samples fabricated under the same conditions, the crack occurrence rate after a 24-hour PCT (Pressure Cooker Test) was calculated to evaluate the crack occurrence rate in a high-temperature, high-humidity environment.

[0107] In the PCT test, capacitor samples were mounted on an FR4 substrate (glass epoxy substrate) using Sn-Ag-Cu solder, placed in a pressure cooker bath, and subjected to an accelerated humidity resistance test for 24 hours under conditions of 121°C and 95% humidity. The test was performed on 100 capacitor samples. Table 1 shows the number of capacitor samples in which cracks occurred. In this example, the crack occurrence rate after 24 hours of PCT is preferably 10% or less, more preferably 3% or less, and particularly preferably 0%.

[0108] (Coverage) When observing a pair of contacting dielectric layers 2 and internal electrode layers 3 in a predetermined field of view of a cross-section (ZX plane shown in Figure 1A) parallel to the stacking direction (Z axis direction) of the element body 10, the ratio of the total length of the internal electrode layers 3 along the stacking interface to the total length of the dielectric layers 2 along the stacking interface was measured as the coverage rate. The results are shown in Table 1A.

[0109] The length of the stacking direction within a predetermined field of view was such that a pair of contacting dielectric layers 3 and internal electrode layers 2 could be observed. Observations were performed in approximately five fields of view that filled the predetermined field of view, and the average coverage of the internal electrode layers 3 was calculated. The results are shown in Table 1A.

[0110] Example 2 Capacitor samples were prepared in the same manner as in Example 1, except as described below, without using the sputtering method.

[0111] In this Example 2, several types of dielectric pastes with different Mn content were prepared, and the internal electrode pastes were printed separately from the center to the edges of the internal electrode paste pattern in order of increasing Mn concentration to form an internal electrode paste film pattern on a green sheet (Manufacturing Method B). In the paste film portion corresponding to the end region R1 of the internal electrode layer, an internal electrode paste without added Mn was used, while in the steep region R3, the equilibrium region R4, and the central region R2, an internal electrode paste with added Mn was used. Otherwise, a capacitor sample was prepared in the same manner as in Example 1, and the same evaluation was performed. The results are shown in Table 1A.

[0112] Comparative Example 1a Capacitor samples were prepared in the same manner as in Example 1, except as shown below.

[0113] In this Comparative Example 1a, capacitor samples were prepared in the same manner as in Example 1, except that the Mn sputtering process performed in Example 1 was omitted (manufacturing method X1), and the same evaluation was carried out. The results are shown in Table 1A.

[0114] Comparative example 1b Capacitor samples were prepared in the same manner as in Example 2, except as shown below.

[0115] In Comparative Example 1, b used only the internal electrode paste containing Mn, one of the two dielectric pastes with different Mn content used in Example 2, and formed a pattern of the internal electrode paste film on a green sheet (Manufacturing Method X2). Otherwise, the capacitor sample was prepared and evaluated in the same manner as in Example 2. The results are shown in Table 1A.

[0116] [Table 1A]

[0117] Rating 1 As shown in Table 1A, compared to Comparative Examples 1a and 1b, Examples 1 and 2 showed a lower rate of visible crack occurrence, and it was confirmed that cracks were particularly suppressed under high temperature and high humidity conditions.

[0118] Comparative Examples 2-4 Capacitor samples were prepared in the same manner as in Example 1, except that Al, Mg, and Si were used instead of Mn for sputtering, and evaluated in the same manner as in Example 1. The results are shown in Table 1B.

[0119] [Table 1B]

[0120] Rating 2 As shown in Table 1b, compared to Comparative Examples 2-4, Examples 1 and 2 showed a lower rate of visible crack occurrence, and it was confirmed that cracks were particularly suppressed under high temperature and high humidity conditions.

[0121] Examples 3 and 4 The main component is (Ca 0.70 Sr 0.30 )(Zr 0.97 Ti 0.03Capacitor samples were prepared in the same manner as in Example 1, except that CaZrO3 and BaTiO3 were used instead of O3, and evaluated in the same manner as in Example 1. The results are shown in Table 1C.

[0122] Comparative Examples 5 and 6 The main component is (Ca 0.70 Sr 0.30 )(Zr 0.97 Ti 0.03 Capacitor samples were prepared in the same manner as in Comparative Example 1, except that CaZrO3 and BaTiO3 were used instead of O3, and evaluated in the same manner as in Comparative Example 1. The results are shown in Table 1C.

[0123] [Table 1C]

[0124] Rating 3 As shown in Table 1C, compared to Comparative Examples 5 and 6, Examples 3 and 4 showed a lower rate of visible cracks, and it was confirmed that cracks were suppressed particularly well under high temperature and humidity conditions. However, compared to Example 4, Examples 1 and 3 showed a lower rate of visible cracks, and it was confirmed that cracks were suppressed particularly well under high temperature and humidity conditions.

[0125] Examples 5-12 Capacitor samples were prepared in the same manner as in Example 1, except that C1 and C2 / C1 were controlled by adjusting the amount of Mn sputtering, and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

[0126] Furthermore, the oxidation of the electrodes was observed using a metallurgical microscope in these examples. Specifically, the central part of the LT cross-section of the capacitor sample was exposed and mirror-polished, and the edges were photographed with a metallurgical microscope. From the photographs, it was confirmed whether there were any areas without metallic luster in at least 20 internal electrode layers. The distance from the end of the internal electrode layer in the X-axis direction to the nearest area without metallic luster was then calculated. If no area without metallic luster was found in the internal electrode layer, the distance was set to 0. This was done for 10 capacitors, and the median distance was determined as the edge oxidation distance. The results are shown in Table 2. In this example, an edge oxidation distance of 0.0 μm is preferable.

[0127] [Table 2]

[0128] Rating 4 As shown in Table 2, C1 may be 0.01 to 0.15 atm%, and it was confirmed that 0.02 to 0.08 atm% is more preferable. C2 / C1 may be 1.1 to 20.0, or 1.5 to 20.0, and it was confirmed that it is preferably 3.0 to 15.0.

[0129] Examples 13-17 Capacitor samples were prepared in the same manner as in Example 1, except that the amount of Mn sputtering was adjusted to control C2 / C1, the slope a1, and the coefficient of determination. The same evaluation as in Example 1 was performed. The results are shown in Table 3.

[0130] [Table 3]

[0131] Rating 5 As shown in Table 3, it was confirmed that C2 / C1 may be between 1.1 and 20.0, or between 1.5 and 20.0, and preferably between 3.0 and 15.0. Furthermore, it was confirmed that C1 may be between 0.01 and 0.15 atm%, and even more preferably between 0.02 and 0.08 atm%. In addition, it was confirmed that the slope a1 in the steep region is preferably 0.1 atm% / mm or more, 0.2 atm% / mm or more, 0.3 atm% / mm or more, 0.5 atm% / mm or more, or 0.6 atm% / mm or more. It was also confirmed that the coefficient of determination in the steep region is preferably 0.70 or more, or 0.75 or more.

[0132] Examples 18-21 Capacitor samples were prepared and evaluated in the same manner as in Example 1, except that the coefficient of determination in the steep region and the slope a2 in the equilibrium region were controlled by adjusting the amount of Mn sputtering. The results are shown in Table 4.

[0133] [Table 4]

[0134] Rating 6 As shown in Table 4, it was confirmed that the slope a1 in the steep region is preferably 0.85 to 0.92 atm% / mm. Furthermore, it was confirmed that the slope a2 in the equilibrium region is preferably within ±0.08 atm% / mm, within ±0.05 atm% / mm, or within ±0.03 atm% / mm.

[0135] Examples 22-25 Capacitor samples were prepared in the same manner as in Example 1, except that the coverage rate was controlled by controlling the amount of electrode deposition or the amount of co-material, and evaluated in the same manner as in Example 1. The results are shown in Table 5.

[0136] [Table 5]

[0137] Rating 7 As shown in Table 5, it was confirmed that a coverage rate of 70% or more, 80% or more, or 90% or more is preferable. [Explanation of Symbols]

[0138] 1.1A…Multilayer ceramic capacitor 2…Internal dielectric layer 3...Internal electrode layer 4…External electrode 10... Element body 10a...end face R1... Terminal area R2…Central area

Claims

1. An electronic component having an element body that contains an insulating layer and an electrode layer inside, An electronic component in which the central concentration of Mn in the central region of the electrode layer, located near the center of the element body, is higher than the central concentration of Mn in the terminal region of the electrode layer, located near the end face of the element body.

2. The electronic component according to claim 1, wherein the end-side concentration of Mn is 0.01 to 0.15 atm%.

3. Let C1 be the concentration of Mn at the end, and C2 be the concentration of Mn at the center. The electronic component according to claim 1 or 2, wherein C2 / C1 is 1.1 to 20.

0.

4. The electronic component according to claim 1 or 2, wherein in the electrode layer, there exists a steep region between the terminal region and the central region in which the concentration of Mn rapidly increases and changes, and the steep region is continuous with the terminal region.

5. The electronic component according to claim 4, wherein the steep region appears within a range of 400 μm from the end face of the element body.

6. The electronic component according to claim 4, wherein in the steep region, the rate of change of Mn concentration with respect to the distance (mm) from the end face of the element body along the electrode layer is 0.1 atm% / mm or more.

7. The electronic component according to claim 4, wherein in the electrode layer, there exists an equilibrium region between the terminal region and the central region in which the change in Mn concentration is small, and the equilibrium region is continuous with the central region.

8. The electronic component according to claim 7, wherein the equilibrium region is observed in a range exceeding 400 μm from the end face of the element body.

9. The electronic component according to claim 7, wherein in the equilibrium region, the rate of change of Mn concentration with respect to the distance (μm) from the end face of the element body along the electrode layer is smaller than the rate of change of Mn concentration in the steep portion.

10. The electronic component according to claim 1 or 2, wherein the terminal concentration is the average value of the concentrations of Mn at three or more measurement points separated from each other at predetermined intervals along the electrode layer within the terminal region.

11. The electronic component according to claim 1 or 2, wherein the central concentration is the average value of the concentrations of Mn at three or more measurement points separated from each other at predetermined intervals along the electrode layer within the central region.

12. When a two-dimensional coordinate system is set up with the distance from the end face of the element body along the electrode layer as the x-axis and the concentration of Mn in the electrode layer at each measurement point along the x-axis as the y-axis, and linear approximation is performed for y in the range of x from 20 μm to 100 μm, The electronic component according to claim 1 or 2, wherein the slope of the approximate straight line in two-dimensional coordinates is 0.2 atm% / mm or more, and the coefficient of determination is 0.75 or more.

13. The electronic component according to claim 1 or 2, wherein the main component of the conductive material contained in the electrode layer is Ni and / or a Ni-based alloy.

14. The electronic component according to claim 1 or 2, wherein the insulating layer is a dielectric layer containing Ca and Zr.

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