Composite particles and multilayer ceramic capacitors containing them

Abstract

The present invention provides composite particles with improved chemical and physical stability, and multilayer ceramic capacitors containing these particles. [Solution] The composite particle according to one embodiment comprises a core containing Ni, and a shell located on the core and containing a compound comprising at least one of Al and Zr, wherein the content of Al or Zr is 0.001 to 5.0 moles per 100 moles of Ni.

Description

Technical Field

[0001] The disclosure of the present application relates to composite particles and a multilayer ceramic capacitor containing the same.

Background Art

[0002] A multilayer ceramic capacitor (MLCC), which is one of capacitor components, is a chip-shaped capacitor mounted on a printed circuit board of various electronic products such as video devices like liquid crystal display (LCD) and plasma display panel (PDP), computers, smartphones, and mobile phones, and serves to charge or discharge electricity.

[0003] Such a multilayer ceramic capacitor is used as a component of various electronic devices due to its advantages of being small in size while ensuring high capacitance and being easy to mount.

[0004] The multilayer ceramic capacitor can include an internal electrode in a dielectric ceramic. Also, the multilayer ceramic capacitor can be manufactured by laminating a conductive paste containing an internal electrode material and a ceramic green sheet containing ceramic powder by a sheet method or a printing method, etc., and firing them simultaneously.

[0005] The sintering start temperatures of the internal electrode material and the dielectric ceramic powder are different, and a shrinkage mismatch between the internal electrode layer and the dielectric may occur during the firing of the ceramic green sheet. As a result, the stability of the multilayer ceramic capacitor may decrease and the resistance of the internal electrode may increase during the firing process.

[0006] Also, nickel powder must be fired in a reducing atmosphere, and in this case, the process cost and time may increase relatively.

Summary of the Invention

[0007] According to one aspect of this disclosure, it is possible to provide composite particles with improved chemical and physical stability.

[0008] Other aspects of this disclosure can provide a cost- and time-saving method for manufacturing composite particles with improved chemical and physical stability.

[0009] According to other aspects of this disclosure, it is possible to provide multilayer ceramic capacitors with improved structural stability, reliability, and capacitance characteristics.

[0010] However, the problems that the embodiments of the present invention aim to solve are not limited to those described above, and can be broadly extended within the scope of the technical ideas included in the present invention. [Means for solving the problem]

[0011] The composite particle according to one embodiment comprises a core containing Ni, and a shell located on the core and containing a compound comprising at least one of Al and Zr, wherein the content of Al or Zr is 0.001 to 5.0 moles per 100 moles of Ni.

[0012] The aforementioned compound may include at least one selected from the group consisting of Al oxides and Zr oxides.

[0013] The Al oxide may have an amorphous structure, and the Zr oxide may have a crystalline structure.

[0014] The compound is disposed on at least a portion of the surface of the core.

[0015] The core may contain Ni nanoparticles.

[0016] The core can be defined as a region in which the Ni content in the total amount of elements contained in the composite particle is 95 mol% or more. The shell can be defined as a region in which the Ni content in the total amount of elements contained in the composite particle is less than 5 mol% and contains Al or Zr.

[0017] The composite particle may further include an intermediate layer located between the core and the shell, which contains Ni oxide.

[0018] The aforementioned Ni oxide may contain NiO.

[0019] The intermediate layer can be defined as a region in which the Ni content in the total amount of elements contained in the composite particle is 5 mol% or more and less than 95 mol%.

[0020] A multilayer ceramic capacitor according to another embodiment includes a capacitor body comprising a dielectric layer and an internal electrode layer, and an external electrode located outside the capacitor body, wherein the internal electrode layer includes an interface region with the dielectric layer, and the interface region of the internal electrode layer comprises Ni and at least one of Al and Zr, and uses the aforementioned composite particles.

[0021] The interface region of the internal electrode layer can be defined as the region extending 1 μm inward from the interface between the dielectric layer and the internal electrode layer to the interior of the internal electrode layer.

[0022] The content of Al or Zr in the interface region of the internal electrode layer may be 0.1 to 1 atomic part per 100 atomic parts of Ni in the interface region of the internal electrode layer.

[0023] Al or Zr may diffuse from the composite particles and be present in the interface region of the internal electrode layer and the dielectric layer.

[0024] The content of Al or Zr contained in the interface region of the internal electrode layer may be greater than the content of Al or Zr contained in the dielectric layer.

[0025] The dielectric layer includes an interface region with the internal electrode layer. The interface region of the dielectric layer includes Ni and at least one of Al and Zr. The interface region of the dielectric layer can be defined as the region from the interface of the dielectric layer and the internal electrode layer to a depth of 1 μm in the internal direction of the dielectric layer.

[0026] The content of Al or Zr contained in the interface region of the dielectric layer may be 0.1 to 1 atomic parts with respect to 100 atomic parts of Ni contained in the interface region of the dielectric layer.

[0027] According to the method for manufacturing composite particles according to another embodiment, at least one selected from the group consisting of an Al precursor and a Zr precursor is introduced into a solvent to form a first solution. Ni powder is introduced into the first solution to form a second solution. The second solution is dispersed by an ultrasonic dispersion method to form a third solution. The third solution is dried to obtain composite particles. The composite particles include a core containing Ni and a shell containing a compound containing at least one of Al and Zr located on the core. The content of Al or Zr in the composite particles is 0.001 to 5.0 mole parts with respect to 100 mole parts of Ni.

[0028] The Al precursor may include an Al chloride, and the Zr precursor may include a Zr chloride.

[0029] The drying may include applying the third solution to a high-temperature plate to volatilize the solvent.

Advantages of the Invention

[0030] According to one example of this disclosure, if the composite particles contain Al or Zr, which have a relatively higher sintering start temperature than Ni, the sintering start temperature of the composite particles can be increased. This reduces the difference in sintering / shrinkage start temperatures between the electrode containing the composite particles and the dielectric material surrounding the electrode. Therefore, structural damage such as shrinkage mismatch and cracks in the electronic device containing the electrode and the dielectric material is suppressed.

[0031] According to one example of this disclosure, the difference in sintering / shrinkage initiation temperature between the dielectric layer and the internal electrode layer is reduced, mitigating shrinkage imbalance and improving the stability and drive reliability of the multilayer ceramic capacitor. [Brief explanation of the drawing]

[0032] [Figure 1] This is a cross-sectional view conceptually illustrating a composite particle as an example. [Figure 2] This is a cross-sectional view conceptually illustrating a composite particle using another example. [Figure 3] This is a flowchart illustrating a method for manufacturing composite particles, as an example. [Figure 4] This is a perspective view conceptually illustrating a multilayer ceramic capacitor as an example. [Figure 5] Figure 3 is a conceptual cross-sectional view of a multilayer ceramic capacitor cut along the line I-I'. [Figure 6] Figure 3 is a conceptual cross-sectional view of a multilayer ceramic capacitor cut along the line II-II'. [Figure 7] These are scanning electron microscope (SEM), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), and transmission electron microscope (TEM) analysis images of composite particles according to Example 1. [Figure 8]These are SEM, SEM-EDS, and TEM analysis images of the composite particles according to Example 2. [Figure 9] These are SEM and TEM analysis images of the composite particles according to Comparative Example 1. [Figure 10] This shows the results of inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis of composite particles according to Example 1. [Figure 11] This shows the ICP-AES analysis results of the composite particles according to Example 2. [Figure 12] These are thermomechanical analysis (TMA) graphs showing the volume change of composite particle pellets (pellets) with respect to sintering temperature in Examples 1 and 2, and Comparative Example 1. [Figure 13] This graph shows the density change of composite particle pellets with respect to sintering temperature in Examples 1 and 2, and Comparative Example 1. [Figure 14] These are X-ray diffraction (XRD) graphs of the composite particle pellets from Examples 1 and 2, and Comparative Example 1. [Figure 15] These are SEM analysis images of composite particle pellets at different sintering temperatures according to Examples 1 and 2, and Comparative Example 1. [Figure 16] This image shows TEM analysis results for composite particle pellets at different sintering temperatures according to Example 1. [Figure 17] This is a TEM analysis image of the composite particle pellets according to Example 2 at different sintering temperatures. [Figure 18] This is an image of a cross-section of a multilayer ceramic capacitor according to Example 1, analyzed by scanning transmission electron microscope-energy dispersive spectroscopy (STEM-EDS). [Figure 19] This is a STEM-EDS analysis image of the cross-section of the multilayer ceramic capacitor according to Example 2. [Figure 20]These are SEM analysis images showing the connectivity of multilayer ceramic capacitors according to Examples 1 and 2, and Comparative Example 1. [Modes for carrying out the invention]

[0033] Embodiments of the present invention will be described in detail below with reference to the attached drawings so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. In order to clearly illustrate the present invention, unnecessary parts have been omitted from the drawings, and the same or similar components are denoted by the same reference numerals throughout the specification. Furthermore, some components in the attached drawings are exaggerated, omitted, or shown conceptually, and the size of each component does not fully reflect its actual size.

[0034] The accompanying drawings are provided solely to facilitate understanding of the embodiments disclosed herein, and it should be understood that the accompanying drawings do not limit the technical ideas disclosed herein and include all modifications, equivalents, or substitutions that fall within the concept and scope of the invention.

[0035] Terms including ordinal numbers, such as "first," "second," etc., are used to describe a variety of components, but the components are not limited by such terms. The terms are used solely for the purpose of distinguishing one component from another.

[0036] Furthermore, when a part such as a layer, membrane, region, or plate is said to be "on top of" or "above" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is another part in between. Conversely, when a part is said to be "directly above" another part, it means that there is no other part in between. Also, being "on top of" or "above" a reference part means being located above or below the reference part, and does not necessarily mean being located "on top of" or "above" in the opposite direction to gravity.

[0037] Throughout the specification, terms such as “includes” or “have” are intended to indicate the presence of features, figures, stages, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preemptively exclude the presence or possibility of adding one or more other features, figures, stages, operations, components, parts, or combinations thereof. Therefore, when a part “includes” a component, this means that it may include other components rather than excluding them, unless otherwise stated.

[0038] Furthermore, throughout the specification, "on a plane" refers to the view of the subject from above, and "on a cross-section" refers to the view of a cross-section obtained by cutting the subject perpendicularly, viewed from the side.

[0039] Furthermore, throughout the specification, the term "connected" does not only mean that two or more components are directly connected, but can also mean that two or more components are indirectly connected through other components, that they are not only physically connected but also electrically connected, or that they are a single unit despite being referred to by different names depending on their location or function.

[0040] Figure 1 is a conceptual cross-sectional view showing an example of a composite particle. Figure 1 can show a cross-section obtained by cutting through the center point of the composite particle 50.

[0041] Referring to Figure 1, one example of a composite particle 50 may include a nickel (Ni) core 52 and a shell 54 located on the core 52.

[0042] The Ni contained in core 52 may be in the form of Ni nanoparticles. This improves the dispersibility of the composite particles 50. For example, the average particle size (D50) of core 52 may be approximately 50 nm to 100 nm.

[0043] The average particle size (D50) can represent the size (particle size) at the point where the cumulative percentage in the size cumulative distribution reaches 50%. For example, the size cumulative distribution can be obtained by measuring the longest major axis of at least 100 cores 52 in an SEM analysis image.

[0044] The shell 54 may include a compound containing at least one of aluminum (Al) and zirconium (Zr). In one example, the shell 54 may contain Al or Zr. In another example, the shell 54 may contain an Al compound or a Zr compound. The composite particle 50 may contain Al or Zr, which have a relatively higher sintering start temperature than Ni, thereby increasing the sintering start temperature of the composite particle 50. This reduces the sintering start temperature difference between the electrode containing the composite particle 50 and the dielectric material surrounding the electrode. Therefore, structural damage such as shrinkage mismatch and cracks in the electronic device containing the electrode and the dielectric material is suppressed.

[0045] Multiple composite particles 50 may exist.

[0046] The elemental content of the core 52 and shell 54 can be measured by performing inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis on the composite particles 50. A sample can be prepared by dissolving a predetermined weight of composite particles 50 in acid, then decomposing them using microwaves, diluting them with distilled water, and filtering the mixture. The sample can then be introduced into the ICP-AES apparatus using a nebulizer. The analysis can be performed while maintaining the plasma state by injecting argon (Ar) gas into the ICP-AES apparatus. Through this analysis, the types and content of elements contained in the composite particles 50 can be measured.

[0047] The compound of shell 54 may include at least one selected from the group consisting of Al oxides and Zr oxides. For example, the compound may be AlOx It can contain (0 < x < 2) or ZrO2.

[0048] The Al oxide (e.g., AlO x ) can contain an amorphous structure. Thereby, the Al oxide can surround the surface of the core 52 more uniformly. Therefore, the sintering start temperature of the composite particles 50 can be further increased.

[0049] The Zr oxide (e.g., ZrO2) can contain a crystalline structure. Thereby, crystalline particles having a size of several tens of nanometers of the Zr oxide suppress the grain boundary movement of Ni and further suppress the sintering of Ni.

[0050] As used herein, the term "shell" can include not only a structure that continuously and entirely surrounds the surface of the core 52 but also a structure that is discontinuously located on a part of the surface of the core 52.

[0051] The compound of the shell 54 is disposed on at least a part of the surface of the core 52. For example, the compound is discontinuously disposed only on a part of the core 52. For example, the compound can also entirely cover the surface of the core 52.

[0052] The structure of the aforementioned composite particles 50 can be measured through Scanning Electron Microscope (SEM), Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy (SEM-EDS), and Transmission Electron Microscope (TEM) analysis.

[0053] By compressing the composite particles 50, a cylindrical pellet with a diameter of approximately 0.5 mm and a height of approximately 2.0 mm to 2.5 mm can be prepared. SEM and TEM analysis images of a cross-section cut along the height direction, passing through the center point of the cylindrical pellet, can be obtained, respectively. The core 52 and shell 54 distribution of the composite particles 50 is shown in the SEM and TEM analysis images. The distribution of constituent elements contained in the composite particles 50 can be confirmed by performing EDS mapping (SEM-EDS analysis) on the obtained SEM analysis image. SEM, SEM-EDS, and TEM analysis can be performed at magnifications of 1K to 20K. When the TEM analysis image is observed with the naked eye, areas with relatively low brightness are judged to be the core 52, and areas with relatively high brightness are judged to be the shell 54 (see Figures 7, 8, 16, and 17 below). Brightness can refer to the degree of brightness when the TEM analysis image is set to black and white. Furthermore, by performing EDS analysis on the TEM analysis image, regions where the Ni content in the total amount of elements contained in the composite particle 50 is 95 mol% or more are determined to be the core 52, and regions where the Ni content is less than 5 mol% and contains Al or Zr are determined to be the shell 54.

[0054] For example, the Al or Zr content in the composite particles 50 may be 0.001 to 5.0 moles per 100 moles of Ni. Within this range, the sintering temperature of the composite particles 50 is sufficiently improved, and the chemical stability is enhanced. This sufficiently reduces the sintering start temperature difference between the electrode containing the composite particles 50 and the dielectric material surrounding the electrode. The total amount can be expressed as the total number of moles.

[0055] The shell 54 may contain Al or Zr. In this case, the content of Al or Zr per 100 mole parts of Ni may be between 0.001 mole parts and 5.000 mole parts.

[0056] Figure 2 is a conceptual cross-sectional view showing a composite particle according to another example. Figure 2 can also show a cross-section cut through the center point of the composite particle 50 according to another example.

[0057] Referring to Figure 2, in other examples, the composite particle 50 may further include an intermediate layer 56 located between the core 52 and the shell 54.

[0058] The intermediate layer 56 may contain Ni oxide. For example, a portion of the Ni contained in the core 52 is oxidized to form the intermediate layer 56 containing the Ni oxide.

[0059] The chemical stability of the core 52 can be further improved through the intermediate layer 56 containing Ni oxide.

[0060] When the aforementioned TEM analysis image is observed with the naked eye, the layer region having a brightness higher than that of the core 52 and lower than that of the shell 54 is determined to be the intermediate layer 56 (see Figures 7, 8, 16, and 17 below). Furthermore, by performing EDS analysis on the aforementioned TEM analysis image, the region where the Ni content relative to the total amount of elements contained in the composite particle 50 is 5 mol% or more and less than 95 mol% is determined to be the intermediate layer 56.

[0061] For example, the Ni oxide may contain NiO.

[0062] Figure 3 is a flowchart illustrating an example of a method for manufacturing composite particles.

[0063] Referring to Figure 3, in one example, a first solution can be formed by adding at least one selected from the group consisting of Al precursors and Zr precursors to a solvent (e.g., step S1).

[0064] The Al precursor may include Al chloride. For example, the Al precursor may include AlCl3·6H2O. The Zr precursor may include Zr chloride. For example, the Zr precursor may include at least one of ZrCl4 and ZrOCl2·8H2O.

[0065] Using the aforementioned chlorides as Al and Zr precursors, a shell 54 can be sufficiently formed on a Ni-containing core 52 through a simple process.

[0066] The solvent may be an aqueous solvent such as water; an alcoholic solvent such as ethanol, methanol, benzyl alcohol, or 2-methoxyethanol; a glycolic solvent such as ethylene glycol or diethylene glycol; a ketone solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone, or cyclohexanone; an esteric solvent such as butyl acetate, ethyl acetate, carbitol acetate, or butyl carbitol acetate; an etheric solvent such as methyl cellosolve, ethyl cellosolve, butyl ether, or tetrahydrofuran; or an aromatic solvent such as benzene, toluene, or xylene. The solvent may include an alcoholic solvent or an aromatic solvent, for example, considering the solubility and dispersibility of various additives contained in the dielectric slurry. As an example, the solvent may be an ethanol solvent.

[0067] For example, Ni powder can be added to the first solution to form a second solution (e.g., step S2). The Ni powder may include Ni nanoparticles.

[0068] For example, the second solution can be dispersed by sonication to form a third solution (e.g., step S3).

[0069] The aforementioned ultrasonic dispersion method can be performed using a bath sonicator, probe sonicator, tip sonicator, or the like.

[0070] The second solution, comprising Ni and at least one of Al and Zr, is ultrasonically dispersed to form a shell 54 containing Al or Zr more uniformly on the core 52 containing Ni. The term “uniform” as used herein does not refer only to mathematically precise uniformity, but also includes cases where the solution is substantially uniform.

[0071] For example, the third solution can be dried to obtain composite particles 50 (e.g., step S4).

[0072] The drying process may include applying the third solution to a hot plate and evaporating the solvent. This can reduce the process convenience and cost of the composite particles 50 containing the shell 54 containing Al or Zr.

[0073] The temperature of the high-temperature plate may be approximately 50°C to 200°C. Within this range, the solvent is sufficiently evaporated and the Al and Zr of the shell 54 are stably arranged on the core 52.

[0074] Figure 4 is a conceptual perspective view showing an example of a multilayer ceramic capacitor. Figure 5 is a conceptual cross-sectional view of a multilayer ceramic capacitor cut along the line I-I' in Figure 3. Figure 6 is a conceptual cross-sectional view of a multilayer ceramic capacitor cut along the line II-II' in Figure 3.

[0075] Referring to Figures 4 to 6, the multilayer ceramic capacitor 100 can include a capacitor body 110 and external electrodes 131 and 132 positioned outside the capacitor body 110. The external electrodes 131 and 132 can include a first external electrode 131 and a second external electrode 132 positioned at opposite ends of the capacitor body 110 in the longitudinal direction (L-axis direction).

[0076] The L-axis, W-axis, and T-axis shown in Figures 4-6 represent the length, width, and thickness directions of the capacitor body 110, respectively. Here, the thickness direction (T-axis direction) may be perpendicular to the broad surface (main surface) of the sheet-shaped component, and can be used as the same concept as the stacking direction in which the dielectric layer 111 is stacked, for example. The length direction (L-axis direction) extends parallel to the broad surface (main surface) of the sheet-shaped component and may be roughly perpendicular to the thickness direction (T-axis direction), for example, the direction in which the first external electrode 131 and the second external electrode 132 are located on both sides. The width direction (W-axis direction) extends parallel to the broad surface (main surface) of the sheet-shaped component and may be roughly perpendicular to the thickness direction (T-axis direction) and the length direction (L-axis direction), and the length in the length direction (L-axis direction) of the sheet-shaped component may be even greater than the length in the width direction (W-axis direction).

[0077] In one example, the capacitor body 110 may include a roughly hexahedral shape.

[0078] For the sake of explanation, in the following, we define the two surfaces of the capacitor body 110 that face each other in the thickness direction (T-axis direction) as the first and second surfaces, the two surfaces connected to the first and second surfaces that face each other in the length direction (L-axis direction) as the third and fourth surfaces, and the two surfaces connected to the first and second surfaces that face each other in the width direction (W-axis direction) as the fifth and sixth surfaces.

[0079] The first surface, which is the lower surface of the capacitor body 110, may be the surface facing the mounting direction of the multilayer ceramic capacitor 100. At least one of the first to sixth surfaces may be flat. Alternatively, at least one of the first to sixth surfaces may be a curved surface with a convex central portion, and the corners that form the boundaries of each surface may be rounded.

[0080] The shape, dimensions, and number of dielectric layers 111 of the capacitor body 110 are not limited to those shown in the drawings of this disclosure.

[0081] The capacitor body 110 may include a dielectric layer 111 and internal electrode layers 121, 122. The capacitor body 110 may include multiple dielectric layers 111.

[0082] The capacitor body 110 may include a plurality of dielectric layers 111, and first internal electrode layers 121 and second internal electrode layers 122 that are alternately arranged in the thickness direction (T-axis direction) with the dielectric layers 111 in between.

[0083] The boundaries between adjacent dielectric layers 111 can be integrated to such an extent that they are difficult to confirm without using a scanning electron microscope (SEM).

[0084] The capacitor body 110 may include an active region. The active region may be a part that contributes to the capacitance formation of the multilayer ceramic capacitor 100. For example, the active region may be a region where a first internal electrode layer 121 or a second internal electrode layer 122, which are stacked along the thickness direction (T-axis direction), are superimposed.

[0085] The capacitor body 110 may further include a cover area and a side margin area.

[0086] The cover region is a thickness-direction margin portion and is arranged adjacent to the first and second surfaces of the active region in the thickness direction (T-axis direction), respectively. For example, a single dielectric layer 111 or two or more dielectric layers 111 are laminated on the upper and lower surfaces of the active region, respectively, to provide the cover region.

[0087] The side margin region is a widthwise margin portion and is arranged adjacent to the fifth and sixth surfaces of the active region in the widthwise direction (W-axis direction), respectively. The side margin region can be formed by laminating dielectric green sheets in which a conductive paste layer is applied only to a portion of the dielectric green sheet surface, and dielectric green sheets without a conductive paste layer applied to both side surfaces of the dielectric green sheet surface, and then firing them.

[0088] For example, damage to the first internal electrode layer 121 and the second internal electrode layer 122 due to physical or chemical stress is prevented through the cover region and the side margin region.

[0089] The dielectric layer 111 may contain a barium titanate-based compound as its main component. For example, the dielectric properties of the multilayer ceramic capacitor 100 can be ensured by using the barium titanate-based compound as the dielectric base material.

[0090] The aforementioned barium titanate-based compounds may include BaTiO3, BaZrO3, BaSnO3, CaTiO3, CaZrO3, CaSnO3, SrTiO3, SrZrO3, SrSnO3, and the like. These can be used individually or in combination of two or more.

[0091] The dielectric layer 111 may further contain minor components. These minor components may include manganese (Mn), chromium (Cr), silicon (Si), aluminum (Al), magnesium (Mg), tin (Sn), antimony (Sb), germanium (Ge), gallium (Ga), indium (In), barium (Ba), lanthanum (La), yttrium (Y), actinium (Ac), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), hafnium (Hf), vanadium (V), and the like. These may be used individually or in combination of two or more.

[0092] For example, the average thickness (average length in the T-axis direction) of the dielectric layer 111 may be approximately 1.0 μm to 8.0 μm. In another example, the average thickness (average length in the T-axis direction) of the dielectric layer 111 may be 2 μm to 6 μm. Within this range, the reliability of the multilayer ceramic capacitor 100 can be further improved.

[0093] The average thickness of the dielectric layer 111 can be measured by performing SEM analysis on a cross-section (LT cross-section) obtained by cutting the multilayer ceramic capacitor 100 perpendicular to the width direction in the length direction (L direction) and the stacking direction (T direction) from the center in the width direction (W direction) of the capacitor. The average thickness of the dielectric layer 111 can be determined by using the center point in the length direction (L direction) or width direction (W direction) of the dielectric layer 111 as a reference point in the SEM analysis image, and measuring the dielectric layer 111 thickness at 10 points separated by a predetermined interval from the reference point. The interval of the 10 points can be adjusted by the scale of the scanning electron microscope (SEM) image, for example, the interval may be 1 μm to 100 μm, 1 μm to 50 μm, or 1 μm to 10 μm. In this case, all 10 points must be located within the dielectric layer 111, and if all 10 points are not located within the dielectric layer 111, the position of the reference point can be changed or the interval between the 10 points can be adjusted.

[0094] The first internal electrode layer 121 and the second internal electrode layer 122 of the internal electrode layers 121 and 122 can have different polarities. For example, the first internal electrode layer 121 and the second internal electrode layer 122 can be arranged alternately so as to face each other along the T-axis direction with the dielectric layer 111 in between. For example, one end of the first internal electrode layer 121 is exposed through the third surface of the capacitor body 110, and one end of the second internal electrode layer 122 is exposed through the fourth surface of the capacitor body 110.

[0095] The first internal electrode layer 121 and the second internal electrode layer 122 are electrically insulated by the dielectric layer 111 placed between them.

[0096] The end of the first internal electrode layer 121, exposed through the third surface of the capacitor body 110, can be electrically connected to the first external electrode 131. For example, the end of the second internal electrode layer 122, exposed through the fourth surface of the capacitor body 110, can be electrically connected to the second external electrode 132.

[0097] The first internal electrode layer 121 and the second internal electrode layer 122 may each contain a conductive metal. For example, the conductive metal may include metals such as Ni, Cu, Ag, Pd, Au, Al, Zr, or alloys thereof (e.g., Ag-Pd alloy).

[0098] The first internal electrode layer 121 and the second internal electrode layer 122 may also contain dielectric particles of the same composition as the ceramic material contained in the dielectric layer 111.

[0099] Generally, achieving a thin internal electrode layer may require the material contained in the internal electrode layers 121 and 122 to be micronized. The smaller the particle size of the material, the lower the melting point. A lower melting point allows for a reduction in the thermal shrinkage initiation temperature. The metal material of the internal electrode layer may experience an even greater decrease in melting point compared to the ceramic material of the dielectric layer. In this case, thinning the internal electrode layer may further increase the sintering mismatch between the internal electrode layer and the dielectric layer during firing of the multilayer ceramic capacitor. For example, at the point where the sintering mismatch is maximized, the difference in sintering initiation temperatures between the dielectric layer and the internal electrode layer may be approximately 500°C or more. The internal electrode layer may begin sintering earlier than the dielectric layer, causing nearby particles to aggregate and resulting in balling. In thinner sections, this can lead to premature breakage and deterioration of the connectivity of the internal electrode layer.

[0100] To solve these problems, one can utilize a method of adding a co-material such as barium titanate to the internal electrode layer. However, if the amount of co-material added increases, the film density of the internal electrode layer may decrease, and a side effect may occur where the co-material is squeezed out in the direction of the dielectric layer, increasing the thickness of the dielectric layer.

[0101] According to one example of this disclosure, the internal electrode layers 121 and 122 may include an interface region with the dielectric layer 111 (hereinafter referred to as the interface region of the internal electrode layers 121 and 122).

[0102] The interface region of the internal electrode layers 121 and 122 can be defined as the region extending 1 μm inward from the interface between the dielectric layer 111 and the internal electrode layers 121 and 122 towards the interior of the internal electrode layers 121 and 122.

[0103] The interface region of the internal electrode layers 121 and 122 can also be defined as the region in which Al or Zr is detected in the elemental concentration profile obtained by performing scanning transmission electron microscope-energy dispersive spectroscopy (STEM-EDS) analysis on the LT cross-section of the multilayer ceramic capacitor 100.

[0104] The interface region of the internal electrode layers 121 and 122 contains Ni and can also contain at least one of Al and Zr. This reduces the difference in sintering start temperatures between the dielectric layer 111 and the internal electrode layers 121 and 122, mitigating shrinkage imbalance and improving the stability and driving reliability of the multilayer ceramic capacitor 100.

[0105] For example, the internal electrode layers 121 and 122 may contain the aforementioned composite particles 50. This increases the sintering start temperature of the internal electrode layers 121 and 122, preventing cracks caused by differences in shrinkage between them and the dielectric layer 111. For example, the internal electrode layers 121 and 122 are formed by printing a conductive paste containing the composite particles 50.

[0106] For example, during the manufacturing of the multilayer ceramic capacitor 100, Ni and Al and / or Zr diffuse from the composite particles 50 of the internal electrode layers 121 and 122 during firing and are disposed in the interface region of the internal electrode layers 121 and 122 and the dielectric layer 111.

[0107] The Al or Zr content in the interface region of the internal electrode layers 121 and 122 may be greater than the Al or Zr content in the dielectric layer. This further reduces the sintering start temperature difference between the internal electrode layers 121 and 122 and the dielectric layer 111, thereby improving the structural stability and reliability of the multilayer ceramic capacitor 100. The Al or Zr content may refer to the Al or Zr atomic portion relative to the Ni 100 atomic portion.

[0108] The content of Al or Zr in the interface region of the internal electrode layers 121 and 122 may be 0.1 to 1 atomic part relative to 100 atomic parts of Ni in the interface region of the internal electrode layers 121 and 122. Within this range, the low resistance characteristics of the internal electrode layers 121 and 122 are maintained or improved while the aforementioned stability is sufficiently increased.

[0109] In one example, the dielectric layer 111 may include an interface region with the internal electrode layers 121 and 122 (hereinafter referred to as the interface region of the dielectric layer 111).

[0110] The interface region of the dielectric layer 111 can be defined as the region extending 1 μm inward from the interface between the dielectric layer 111 and the internal electrode layers 121 and 122 in the direction of the dielectric layer 111.

[0111] The interface region of the dielectric layer 111 contains Ni and can also contain at least one of Al and Zr. This reduces the difference in sintering start temperatures between the dielectric layer 111 and the internal electrode layers 121 and 122, mitigating shrinkage imbalance and improving the stability and driving reliability of the multilayer ceramic capacitor 100.

[0112] For example, during the manufacturing of the multilayer ceramic capacitor 100, Ni and Al and / or Zr diffuse from the composite particles 50 of the internal electrode layers 121 and 122 toward the interior of the dielectric layer 111 during firing and are arranged in the interface region of the dielectric layer 111.

[0113] The content of Al or Zr in the interface region of the dielectric layer 111 may be 0.1 to 1 atomic part relative to 100 atomic parts of Ni in the interface region of the dielectric layer 111. Within this range, the aforementioned stability is sufficiently increased while adequate insulation between the internal electrode layers 121 and 122 through the dielectric layer 111 is maintained.

[0114] Scanning transmission electron microscope-energy dispersive spectroscopy (STEM-EDS) can be used to confirm / measure the presence of the interface region and the presence and content of elements contained in the interface region.

[0115] The multilayer ceramic capacitor 100 can be fixed with epoxy resin and polished with a polishing machine so that the LT cross section is exposed. The polishing can be performed so that half of the length in the width direction (W-axis direction) is removed. The dielectric layer 111 and internal electrode layers 121, 122 can be seen in approximately 1 to 6 layers in the active region of the exposed LT cross section using STEM. For example, STEM imaging can be performed at a magnification (10k) where approximately 1 to 6 layers of the dielectric layer 111 and internal electrode layers 121, 122 are visible, under an acceleration voltage of 200kV. EDS mapping analysis can be performed on the acquired STEM image to obtain a STEM-EDS analysis image. Information on the interface region and Al or Zr contained in the interface region can be obtained through the STEM-EDS analysis image.

[0116] For example, the first internal electrode layer 121 and the second internal electrode layer 122 can be formed using a conductive paste containing a conductive metal. For example, the conductive paste may contain the aforementioned composite particles 50 and can be printed by screen printing or gravure printing.

[0117] For example, the average thickness of the first internal electrode layer 121 and the second internal electrode layer 122 may be 0.1 μm to 2 μm. Within this range, the multilayer ceramic capacitor 100 can be miniaturized and made thinner, further reducing its resistance.

[0118] For example, the average thickness of the first internal electrode layer 121 and the second internal electrode layer 122 can be measured by SEM analysis. The SEM analysis may be substantially the same as the method for measuring the average thickness of the dielectric layer 111 described above.

[0119] The capacitor body 110 can be formed by firing a laminate in which multiple dielectric layers 111 and internal electrode layers 121 and 122 are stacked.

[0120] Referring to Figure 5, the first external electrode 131 and the second external electrode 132 can have different polarities.

[0121] The first external electrode 131 is electrically connected to the portion of the first internal electrode layer 121 that is exposed. For example, the second external electrode 132 is electrically connected to the portion of the second internal electrode layer 122 that is exposed.

[0122] When a predetermined voltage is applied to the first external electrode 131 and the second external electrode 132, charge is accumulated between the opposing first internal electrode layer 121 and the second internal electrode layer 122. The capacitance of the multilayer ceramic capacitor 100 may be proportional to the area overlapped on the plane of the first internal electrode layer 121 and the second internal electrode layer 122, which are superimposed on each other in the stacking direction (T-axis direction) in the active region.

[0123] The first external electrode 131 and the second external electrode 132 may include first and second connection portions (not shown) which are arranged on the third and fourth surfaces of the capacitor body 110, respectively, and connected to the first internal electrode layer 121 and the second internal electrode layer 122, respectively. The first external electrode 131 and the second external electrode 132 may also include first and second band portions (not shown) which are arranged at the corners where the third and fourth surfaces, the first and second surfaces, or the fifth and sixth surfaces of the capacitor body 110 meet.

[0124] The first band portion and the second band portion extend from the first and second connection portions to a portion of the first and second surfaces or the fifth and sixth surfaces of the capacitor body 110, respectively. The fixing strength of the first external electrode 131 and the second external electrode 132 can be improved through the first and second band portions.

[0125] The first external electrode 131 and the second external electrode 132 may each include a sintered metal layer in contact with the capacitor body 110, a conductive resin layer disposed to cover the sintered metal layer, and a plating layer disposed to cover the conductive resin layer.

[0126] The sintered metal layer may include conductive metal and glass.

[0127] The conductive metal may include copper (Cu), nickel (Ni), silver (Ag), palladium (Pd), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), lead (Pb), alloys thereof, or combinations thereof. For example, copper (Cu) may include copper (Cu) alloys. If the conductive metal includes copper, the other metals are included in an amount of 5 moles or less per 100 moles of copper.

[0128] The glass may contain a composition of mixed oxides, and may include, for example, at least one selected from the group consisting of silicon oxide, boron oxide, aluminum oxide, transition metal oxide, alkali metal oxide, and alkaline earth metal oxide.

[0129] Transition metals may include at least one selected from the group consisting of zinc (Zn), titanium (Ti), copper (Cu), vanadium (V), manganese (Mn), iron (Fe), and nickel (Ni). Alkali metals may include at least one selected from the group consisting of lithium (Li), sodium (Na), and potassium (K). Alkaline earth metals may include at least one selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).

[0130] Selectively, the conductive resin layer is formed on the sintered metal layer, for example, in a form that completely covers the sintered metal layer. For example, the first external electrode 131 and the second external electrode 132 do not have to include the sintered metal layer. In this case, the conductive resin layer can be in direct contact with the capacitor body 110.

[0131] The conductive resin layer extends to the first and second surfaces or the fifth and sixth surfaces of the capacitor body 110, and the length of the region where the conductive resin layer extends to the first and second surfaces or the fifth and sixth surfaces of the capacitor body 110 (i.e., the band portion) may be greater than the length of the region where the sintered metal layer extends to the first and second surfaces or the fifth and sixth surfaces of the capacitor body 110 (i.e., the band portion). For example, the conductive resin layer can be formed on top of the sintered metal layer and can completely cover the sintered metal layer.

[0132] The conductive resin layer comprises a resin and a conductive metal.

[0133] The resin contained in the conductive resin layer is not particularly limited as long as it has bonding and shock-absorbing properties and can be mixed with conductive metal powder to form a paste, and may include, for example, phenolic resin, acrylic resin, silicone resin, epoxy resin, or polyimide resin.

[0134] The conductive metal contained in the conductive resin layer may be spherical, flake-shaped, or a combination thereof. For example, the conductive metal may consist only of flake-shaped metal, only of spherical metal, or a mixture of flake-shaped and spherical metal.

[0135] Here, spherical can include forms that are not perfectly spherical, for example, forms in which the ratio of the length of the major axis to the length of the minor axis (major axis / minor axis) is 1.45 or less. Flake powder means powder having a flat and elongated shape, and is not particularly limited, but for example, the ratio of the length of the major axis to the length of the minor axis (major axis / minor axis) may be 1.95 or more.

[0136] The first external electrode 131 and the second external electrode 132 may further include a plating layer disposed on the outside of the conductive resin layer.

[0137] The plating layer may include nickel (Ni), copper (Cu), tin (Sn), palladium (Pd), platinum (Pt), gold (Au), silver (Ag), tungsten (W), titanium (Ti), or lead (Pb), either alone or in alloys thereof. For example, the plating layer may be a nickel (Ni) plating layer or a tin (Sn) plating layer, or it may be a configuration in which a nickel (Ni) plating layer and a tin (Sn) plating layer are sequentially laminated, or it may be a configuration in which a tin (Sn) plating layer, a nickel (Ni) plating layer, and a tin (Sn) plating layer are sequentially laminated. Furthermore, the plating layer may include multiple nickel (Ni) plating layers and / or multiple tin (Sn) plating layers.

[0138] The plating layer improves the mountability, structural reliability, external durability, and heat resistance of the multilayer ceramic capacitor 100 on the substrate, and further reduces the equivalent series resistance (ESR).

[0139] The following describes a method for manufacturing a multilayer ceramic capacitor 100 as an example.

[0140] A method for manufacturing a multilayer ceramic capacitor 100 may include the steps of: manufacturing a capacitor body 110 including a dielectric layer 111 and internal electrode layers 121 and 122; and forming external electrodes 131 and 132 on the outside of the capacitor body 110.

[0141] In the manufacturing process of the capacitor body 110, a dielectric paste that will become the dielectric layer 111 after firing and a conductive paste that will become the internal electrode layers 121 and 122 after firing are prepared.

[0142] A plasticizer can be obtained by uniformly mixing and drying dielectric powder through wet mixing or the like, and then heat-treating it under predetermined conditions. A dielectric paste can be manufactured by adding an organic vehicle or an aqueous vehicle to the plasticizer powder, heating and mixing it.

[0143] The dielectric paste can be formed into a sheet using techniques such as the doctor blade method to obtain a dielectric green sheet. For example, the dielectric paste may contain additives selected from various dispersants, plasticizers, dielectrics, minor component compounds, and / or glass.

[0144] Conductive paste for internal electrodes can be prepared by kneading conductive powder, which consists of a conductive metal or an alloy thereof, with a binder and a solvent.

[0145] The conductive paste for the internal electrode may contain indium (In).

[0146] In one example of this disclosure, the conductive paste for the internal electrodes may include the composite particles 50 described above. This reduces the difference in sintering start temperatures between the internal electrode layers 121, 122 and the dielectric layer 111, thereby suppressing crack formation during the firing process of the multilayer ceramic capacitor 100 and improving stability and reliability.

[0147] In another example, the Ni and Al and / or Zr of the composite particles 50 contained in the conductive paste for the internal electrodes diffuse into the dielectric layer 111 by sintering and are positioned in the aforementioned interface region. This reduces the difference in shrinkage initiation temperatures between the internal electrode layers 121, 122 and the dielectric layer 111, thereby improving the structural reliability of the multilayer ceramic capacitor 100.

[0148] The conductive paste for the internal electrodes can be applied to the surface of a dielectric green sheet in a predetermined pattern using various printing methods such as screen printing or transfer methods. A dielectric green sheet laminate can be obtained by laminating multiple dielectric green sheets with the internal electrode pattern formed on them and applying pressure in the lamination direction. Dielectric green sheets and internal electrode patterns are laminated on the upper and lower surfaces of the dielectric green sheet laminate in the lamination direction such that dielectric green sheets are positioned on the upper and lower surfaces.

[0149] The dielectric green sheet laminate can be selectively cut to predetermined dimensions by dicing or the like.

[0150] The dielectric green sheet laminate can be solidified and dried to remove plasticizers and other substances as needed, and after solidification and drying, it can be barrel polished using a horizontal centrifugal barrel polishing machine or the like. In barrel polishing, the dielectric green sheet laminate is placed in a barrel container together with media and polishing fluid, and rotational motion or vibration is applied to the barrel container to polish away unnecessary parts such as burrs generated during cutting. For example, after barrel polishing, the dielectric green sheet laminate is washed with a cleaning solution such as water and dried.

[0151] The dielectric green sheet laminate can be subjected to a binder removal process and a firing process to obtain the capacitor body 110.

[0152] The conditions for the binder removal process can be appropriately adjusted depending on the main component composition of the dielectric layer and the main component composition of the internal electrodes. For example, the heating rate during the binder removal process may be 5°C / hour to 300°C / hour, the support temperature may be 180°C to 400°C, and the temperature maintenance time may be 0.5 hours to 24 hours. The binder removal atmosphere may be air or a reducing atmosphere.

[0153] The firing conditions can be appropriately adjusted depending on the main component composition of the dielectric layer and the main component composition of the internal electrodes. For example, the firing temperature may be 1200°C to 1350°C or 1220°C to 1300°C, and the firing time may be 0.5 hours to 8 hours or 1 hour to 3 hours. The firing atmosphere may be a reducing atmosphere, for example, a humidified atmosphere of a mixed gas of nitrogen gas (N2) and hydrogen gas (H2). If the internal electrode layers 121 and 122 contain nickel (Ni) or a nickel (Ni) alloy, the oxygen partial pressure in the firing atmosphere should be 1.0 × 10⁻⁶. -14 MPa ~ 1.0 × 10 -10 MPa is also acceptable.

[0154] After the firing process, annealing can be performed as needed. This annealing process is for re-oxidizing the dielectric layer and can be performed when the firing process is carried out in a reducing atmosphere. The conditions for the annealing process can also be appropriately adjusted depending on the main component composition of the dielectric layer. For example, the annealing temperature may be 950°C to 1150°C, the duration may be 0 to 20 hours, and the heating rate may be 50°C / hour to 500°C / hour. The annealing atmosphere may be a humidified nitrogen gas (N2) atmosphere, and the oxygen partial pressure may be 1.0 × 10⁻⁶. -9 MPa ~ 1.0 × 10 -5 MPa is also acceptable.

[0155] For debinding, calcination, or annealing processes, a wetter, for example, can be used to humidify nitrogen gas or a mixed gas, in which case the water temperature may be between 5°C and 75°C. Debinding, calcination, and annealing processes can be performed continuously or independently.

[0156] Selectively, surface treatments such as sandblasting, laser irradiation, or barrel polishing can be performed on the third and fourth surfaces of the obtained capacitor body 110. Through such surface treatments, the ends of the first internal electrode layer 121 and the second internal electrode layer 122 are exposed on the outermost surfaces of the third and fourth surfaces. This improves the electrical connection between the first external electrode 131 and the second external electrode 132 and the first internal electrode layer 121 and the second internal electrode layer 122, and makes it easier to form the alloy portion.

[0157] External electrodes 131 and 132 can be formed on one surface of the manufactured capacitor body 110.

[0158] For example, a sintered metal layer can be formed by applying a paste for forming a sintered metal layer and then sintering it.

[0159] The paste for forming a sintered metal layer may contain the aforementioned conductive metals and glass. Furthermore, the paste for forming a sintered metal layer may selectively contain a binder, solvent, dispersant, plasticizer, oxide powder, etc. The binder may include, for example, ethyl cellulose, acrylic, butyral, and the solvent may include, for example, organic solvents such as terpineol, butyl carbitol, alcohol, methyl ethyl ketone, acetone, toluene, or aqueous solvents.

[0160] As a method for applying the sintered metal layer forming paste to the outer surface of the capacitor body 110, various printing methods such as dipping and screen printing, application methods using dispensers, and spraying methods using sprays can be used.

[0161] The sintered metal layer forming paste is applied to at least the third and fourth surfaces of the capacitor body 110, and is also applied to a portion of the first, second, fifth, or sixth surfaces where the band portions of the first and second external electrodes are selectively formed.

[0162] Subsequently, the capacitor body 110 coated with the paste for forming the sintered metal layer is dried, and the sintered metal layer can be formed by sintering it at a temperature of 700°C to 1000°C for 0.1 to 3 hours.

[0163] Selectively, a conductive resin layer can be formed on the outer surface of the obtained capacitor body 110 by applying a paste for forming a conductive resin layer and then curing it.

[0164] The paste for forming a conductive resin layer may contain a resin and, selectively, a conductive metal or a non-conductive filler. The descriptions of conductive metals and resins are the same as those given above, so repeated explanations will be omitted. The paste for forming a conductive resin layer may also selectively contain a binder, solvent, dispersant, plasticizer, oxide powder, etc. The binder may be, for example, ethyl cellulose, acrylic, butyral, etc., and the solvent may be an organic solvent such as terpineol, butyl carbitol, alcohol, methyl ethyl ketone, acetone, toluene, or an aqueous solvent.

[0165] As an example, the conductive resin layer can be formed by dipping the capacitor body 110 into a conductive resin layer forming paste and then curing it, or by printing the conductive resin layer forming paste onto the surface of the capacitor body 110 using a screen printing method or gravure printing method, or by applying the conductive resin layer forming paste to the surface of the capacitor body 110 and then curing it.

[0166] A plating layer can be formed on the outside of the conductive resin layer.

[0167] For example, the plating layer can be formed by a plating method, and can also be formed by sputtering or electroplating (electric deposition).

[0168] The following provides specific examples of the present disclosure. However, the examples described below are for illustrative or illustrative purposes only. [Examples]

[0169] Example 1 (Manufacturing of composite particles) The first solution was prepared by adding and mixing 12.35 g of AlCl3·6H2O to ethanol solvent.

[0170] A second solution was formed by adding 100 g of Ni nanoparticles to the first solution. As a result, the composite particles contained 3 moles of Al for every 100 moles of Ni.

[0171] The second solution was dispersed using a bath sonicator and a tip sonicator to form a third solution. Tip sonication was performed at a frequency of 20 kHz and a power of 40 W for 2 hours.

[0172] The third solution was applied to a hot plate maintained at 160°C and dried until the ethanol solvent evaporated to produce composite particles containing a nickel core and an Al oxide shell.

[0173] (Pellet manufacturing) The composite particles produced by the aforementioned method were compressed to produce cylindrical pellets with a diameter of approximately 0.5 mm and a height of approximately 2.0 mm to 2.5 mm.

[0174] (Manufacturing of multilayer ceramic capacitors) After manufacturing a dielectric green sheet using barium titanate (BaTiO3) as the main component powder, a conductive paste layer containing the aforementioned composite particles was printed onto the surface of the dielectric green sheet. Dielectric green sheet laminates (width × length × height = 3.2 mm × 2.5 mm × 2.5 mm) with the conductive paste layer formed thereon were laminated and pressed together to produce a dielectric green sheet laminate. The dielectric green sheet laminate was fired in a nitrogen atmosphere at a temperature of 400°C or less, and then fired again at a temperature of 1300°C or less and a hydrogen concentration of 1.0% H2 or less to produce a capacitor body.

[0175] Next, the multilayer ceramic capacitor was manufactured through processes such as the addition of external electrodes and plating.

[0176] Example 2 Composite particles, pellets, and multilayer ceramic capacitors were manufactured in the same manner as in Example 1, except that 11.92 g of ZrCl4 was added to the ethanol solvent instead of AlCl3·6H2O (containing 3 moles of Zr per 100 moles of Ni).

[0177] Example 3 Composite particles, pellets, and multilayer ceramic capacitors were manufactured in the same manner as in Example 1, except that 0.0041 g of AlCl3·6H2O was added to the ethanol solvent.

[0178] Example 4 Composite particles, pellets, and multilayer ceramic capacitors were manufactured in the same manner as in Example 1, except that 20.58 g of AlCl3·6H2O was added to the ethanol solvent.

[0179] Comparative Example 1 Pellet and multilayer ceramic capacitors were manufactured in the same manner as in Example 1, except that Ni nanoparticles were used instead of the composite particles.

[0180] Comparative Example 2 Composite particles, pellets, and multilayer ceramic capacitors were manufactured in the same manner as in Example 1, except that 0.0021 g of AlCl3·6H2O was added to the ethanol solvent.

[0181] Comparative Example 3 Composite particles, pellets, and multilayer ceramic capacitors were manufactured in the same manner as in Example 1, except that 22.64 g (or wt%) of AlCl3·6H2O was added to the ethanol solvent.

[0182] Evaluation 1: Structural analysis of composite particles (SEM, SEM-EDS, TEM) SEM and TEM analysis images were obtained for the composite particles of Examples 1 and 2 described above, as well as for the Ni nanoparticles of Comparative Example 1.

[0183] The aforementioned SEM analysis was performed under accelerated voltage conditions ranging from 0.01 kV to 30 kV.

[0184] An EDS mapping analysis was performed on the aforementioned SEM analysis image to obtain an SEM-EDS analysis image.

[0185] The aforementioned TEM analysis was performed under a magnification of 10k and an accelerating voltage of 200kV.

[0186] Figure 7 shows SEM, SEM-EDS, and TEM analysis images of the composite particles according to Example 1. Figure 8 shows SEM, SEM-EDS, and TEM analysis images of the composite particles according to Example 2. Figure 9 shows SEM and TEM analysis images of the composite particles according to Comparative Example 1.

[0187] Referring to Figures 7 to 9, the composite particles of Examples 1 and 2 have shells containing Al and Zr compounds, respectively, located on a Ni core, but the composite particles of Comparative Example 1 did not show the aforementioned shell.

[0188] Evaluation 2: Compositional analysis of composite particles (ICP-AES) Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis was performed on the composite particles of Examples 1-4, Comparative Examples 2 and 3, and the Ni nanoparticles of Comparative Example 1.

[0189] Specifically, a predetermined weight of composite particles was dissolved in acid, then decomposed using microwaves, diluted with distilled water, and filtered to prepare the sample. The sample was then introduced into an ICP-AES apparatus using a nebulizer. Argon (Ar) gas was injected into the ICP-AES apparatus to maintain the plasma state, and the Al content relative to the number of moles of Ni in the composite particles (Example 1) and the Zr content relative to the number of moles of Ni in the composite particles (Example 2) were measured.

[0190] Figure 10 shows the ICP-AES analysis results of the composite particles according to Example 1. Figure 11 shows the ICP-AES analysis results of the composite particles according to Example 2.

[0191] Referring to Figures 10 and 11, the Al content of the composite particles in Example 1 is approximately 3 mol% relative to the number of moles of Ni, and the Zr content of the composite particles in Example 2 is approximately 3 mol% relative to the number of moles of Ni.

[0192] Evaluation 3: Thermomechanical Analysis (TMA) Thermomechanical analysis (TMA) was performed on the pellets of Examples 1 and 2, as well as Comparative Example 1.

[0193] Specifically, pellets were placed in a TMA apparatus, and the rate of change in pellet thickness was measured while heating them in an argon (Ar) atmosphere at a rate of 10°C / min in the range of 25°C to 1000°C. The load applied to the pellets was set to 0.2N.

[0194] Figure 12 is a thermomechanical analysis (TMA) graph showing the volume change of composite particle pellets with respect to sintering temperature for Examples 1 and 2, and Comparative Example 1. In Figure 12, L0 is the initial thickness of the pellet, and dL is the change in pellet thickness.

[0195] Referring to Figure 12, in Comparative Example 1, pellet shrinkage began at approximately 400°C, while in Example 1, it began at approximately 900°C, and in Example 2, it began at approximately 800°C. Therefore, in the composite particles of the examples containing a shell with Al or Zr, the sintering start temperature was delayed by approximately 400°C or more compared to Comparative Example 1.

[0196] Rating 4: Relative Density Analysis The pellets of Examples 1 and 2, and Comparative Example 1, were sintered at 600°C, 700°C, 800°C, 900°C, and 1000°C for 5 minutes each, and the relative density (density after sintering / density before sintering, %) at each temperature was measured. The relative density was measured using the Archimedes method.

[0197] Figure 13 is a graph showing the density change of composite particle pellets with respect to sintering temperature for Examples 1 and 2, and Comparative Example 1.

[0198] Referring to Figure 13, in Comparative Example 1, significant pellet shrinkage occurred at 600°C, while in Examples 1 and 2, pellet shrinkage (density increase) began at 900°C and 800°C, respectively. After sintering at 1000°C, the density of the pellets in Examples 1 and 2 was relatively lower than that of Comparative Example 1. Therefore, the pellets produced in Examples 1 and 2 showed relatively less shrinkage due to sintering compared to the pellets in Comparative Example 1.

[0199] Rating 5: XRD Analysis Phase behavior was observed by X-ray spectroscopy (XRD) analysis of the pellets from Examples 1 and 2, as well as Comparative Example 1.

[0200] XRD analysis was performed under the conditions of a K-Alpha wavelength of 1.540598 Å, a drive voltage of 45 kV, and a scan range of 10° to 120°.

[0201] Figure 14 shows the X-ray diffraction (XRD) graphs of the composite particle pellets for Examples 1 and 2, and Comparative Example 1.

[0202] Referring to Figure 14, in Comparative Example 1, NiO located on the core was reduced at temperatures above 600°C.

[0203] In Example 1, NiO was reduced at over 800°C, an increase of over 200°C compared to Comparative Example 1. As a result, the structure of the composite particle pellet was maintained more stably than in Comparative Example 1.

[0204] In Example 2, NiO was reduced at 500°C, but ZrO2 was formed on the core from 700°C onwards, suppressing pellet sintering.

[0205] Evaluation 6: SEM analysis based on sintering temperature For each of the pellets in Examples 1 and 2, and Comparative Example 1, sintering was performed at 600°C, 700°C, 800°C, 900°C, and 1000°C for 5 minutes each. After that, the pellets were cut lengthwise, passing through the center point, to expose the cross-section.

[0206] An SEM analysis image of the cross-section was obtained using the same method as the SEM analysis method in Evaluation 1, depending on the sintering temperature.

[0207] Figure 15 shows SEM analysis images of composite particle pellets at different sintering temperatures for Examples 1 and 2, and Comparative Example 1.

[0208] Referring to Figure 15, in Comparative Example 1, Ni nanoparticles aggregated from 600°C, particle coarsening and grain growth occurred at 700°C, and the particles became denser at 800°C.

[0209] In Example 1, the initial morphology of the composite particles was maintained up to 900°C, and aggregation of some particles was observed at 1000°C.

[0210] In Example 2, the initial morphology of the composite particles was maintained up to 800°C, and aggregation of some particles was observed above 900°C.

[0211] Rating 7: TEM analysis For each of the pellets in Examples 1 and 2, sintering was performed at 600°C and 800°C for 5 minutes each, and then the pellets were cut lengthwise, passing through their center point, to expose the cross-sections.

[0212] A TEM analysis image of the cross-section was obtained using the same method as the TEM analysis method in Evaluation 1, based on the sintering temperature.

[0213] Figure 16 shows TEM analysis images of composite particle pellets at different sintering temperatures according to Example 1.

[0214] Figure 17 shows TEM analysis images of composite particle pellets at different sintering temperatures according to Example 2.

[0215] Refer to Figure 16, AlO x The amorphous film was relatively uniformly shelled onto the Ni core, increasing the sintering temperature of the pellet.

[0216] Referring to Figure 17, ZrO2 is formed on the Ni core, and the Zener pinning effect of the ZrO2 suppresses the enlargement and densification of Ni particles. For example, ZrO2 particles of several tens of nanometers in size interfere with the interfacial movement of crystal grains of Ni nanoparticles, thereby suppressing particle enlargement and densification.

[0217] Evaluation 8: Analysis of the interface region (STEM-EDS analysis) The multilayer ceramic capacitors of Examples 1 and 2 were placed horizontally and fixed around the perimeter with epoxy resin.

[0218] The multilayer ceramic capacitor was polished using a polishing machine so that the cross-sections, cut perpendicular to the width direction (L-axis direction) and in the stacking direction (T-axis direction) from the center in the width direction (W-axis direction), were exposed.

[0219] The exposed cross-section was imaged using a scanning transmission electron microscope (STEM) to obtain a STEM image.

[0220] EDS mapping analysis was performed on the aforementioned STEM image to obtain a STEM-EDS analysis image.

[0221] STEM imaging was performed under 10k magnification and 200kV acceleration voltage conditions for regions where at least one dielectric layer and one internal electrode layer were visible.

[0222] Figure 18 shows a STEM-EDS analysis image of the cross-section of a multilayer ceramic capacitor according to Example 1. Figure 19 shows a STEM-EDS analysis image of the cross-section of a multilayer ceramic capacitor according to Example 2.

[0223] Referring to Figure 18, Ni and Al diffused into the interface region of the internal electrode layers 121 and 122. The Al content was measured to be 0.1 to 1 atomic part per 100 atomic parts of Ni.

[0224] Referring to Figure 19, Ni and Zr were diffused into the interface region of the dielectric layer 111. The Zr content was measured to be between 0.1 and 1 atomic part per 100 atomic parts of Ni.

[0225] Evaluation 9: Connectivity of the internal electrode layer (SEM analysis) The multilayer ceramic capacitors of Examples 1 and 2, and Comparative Example 1, were placed horizontally and fixed around the perimeter with epoxy resin.

[0226] The multilayer ceramic capacitor was polished using a polishing machine so that the cross-sections, cut perpendicular to the width direction (L-axis direction) and in the stacking direction (T-axis direction) from the center in the width direction (W-axis direction), were exposed.

[0227] For the exposed cross-section, an SEM analysis image was obtained using the same method as the SEM analysis method in Evaluation 1 for the region where eight or more internal electrode layers were present.

[0228] The connectivity of the internal electrode layer was calculated using the following formula 1 from the aforementioned SEM analysis image.

[0229] [Formula 1] Connectivity of internal electrode layers (%) = (Total length of internal electrode layers excluding breaks / Total length of internal electrode layers) × 100 Figure 20 is an SEM analysis image showing the connectivity of multilayer ceramic capacitors according to Examples 1 and 2, and Comparative Example 1.

[0230] Referring to Figure 20, Examples 1 and 2 showed relatively improved connectivity compared to Comparative Example 1.

[0231] Rating 10: Capacity The capacitance of the multilayer ceramic capacitors according to the examples and comparative examples was measured at a frequency of 1 kHz and a voltage of 0.5 V.

[0232] A predetermined reference volume was set, and the measured volume was divided by the reference volume and multiplied by 100 to evaluate it as a percentage.

[0233] Evaluation 11: MTTF measurement The Mean Time To Failure (MTTF) was measured for multilayer ceramic capacitors according to the examples and comparative examples. Specifically, the MTTF was measured for 48 hours under a temperature of 125°C and a voltage of 9.45V.

[0234] Table 1 below shows the elements contained in the shells of the examples and comparative examples, the content, volume, connectivity, and MTTF of Al or Zr relative to the number of moles of Ni.

[0235] [Table 1]

[0236] As shown in Table 1, in the examples where the Al or Zr content per 100 moles of Ni was 0.001 moles to 5.0 moles, the volume characteristics, connectivity, and reliability were improved compared to the comparative example.

[0237] While embodiments of this disclosure have been described above, the scope of this disclosure is not limited thereto. It is possible to implement the invention in various ways within the scope of the claims, description of the invention, and accompanying drawings, and these also naturally fall within the scope of this disclosure. [Explanation of symbols]

[0238] 50: Composite particles 52: Core 54: Shell 56: Middle Class 100: Multilayer ceramic capacitor 110: Capacitor body 111: Dielectric layer 121: 1st internal electrode 122:Second internal electrode 131: 1st external electrode 132:Second external electrode S1, S2, S3, S4: Stages

Claims

1. Cores containing Ni; and The core comprises a shell located on the core and containing a compound comprising at least one of Al and Zr, Composite particles in which the Al or Zr content is 0.001 to 5.0 moles per 100 moles of Ni.

2. The composite particle according to claim 1, wherein the compound comprises at least one selected from the group consisting of Al oxides and Zr oxides.

3. The composite particle according to claim 2, wherein the Al oxide includes an amorphous structure and the Zr oxide includes a crystalline structure.

4. The composite particle according to claim 1, wherein the compound is located on at least a portion of the surface of the core.

5. The composite particle according to claim 1, wherein the core comprises Ni nanoparticles.

6. The composite particle according to claim 1, wherein the core is defined as a region in which the Ni content in the total amount of elements contained in the composite particle is 95 mol% or more, and the shell is defined as a region in which the Ni content in the total amount of elements contained in the composite particle is less than 5 mol% and contains Al or Zr.

7. The composite particle according to claim 1, further comprising an intermediate layer containing Ni oxide, located between the core and the shell.

8. The composite particle according to claim 7, wherein the Ni oxide includes NiO.

9. The composite particle according to claim 7, wherein the intermediate layer is defined as a region in which the content of Ni in the total amount of elements contained in the composite particle is 5 mol% or more and less than 95 mol%.

10. A capacitor body including a dielectric layer and an internal electrode layer; Includes an external electrode located outside the capacitor body; The internal electrode layer includes an interface region with the dielectric layer. The interface region of the internal electrode layer comprises Ni and at least one of Al and Zr. A multilayer ceramic capacitor using the composite particles of claim 1.

11. The multilayer ceramic capacitor according to claim 10, wherein the interface region of the internal electrode layer is defined as a region extending 1 μm inward from the interface between the dielectric layer and the internal electrode layer to the interior of the internal electrode layer.

12. The multilayer ceramic capacitor according to claim 10, wherein the content of Al or Zr in the interface region of the internal electrode layer is 0.1 to 1 atomic part relative to 100 atomic parts of Ni in the interface region of the internal electrode layer.

13. The multilayer ceramic capacitor according to claim 10, wherein Al or Zr diffuses from the composite particles and is present in the interface region of the internal electrode layer and the dielectric layer.

14. The multilayer ceramic capacitor according to claim 13, wherein the content of Al or Zr contained in the interface region of the internal electrode layer is greater than the content of Al or Zr contained in the dielectric layer.

15. The dielectric layer includes an interface region with the internal electrode layer, and the interface region of the dielectric layer includes Ni and at least one of Al and Zr. The multilayer ceramic capacitor according to claim 10, wherein the interface region of the dielectric layer is defined as a region extending 1 μm inward from the interface between the dielectric layer and the internal electrode layer to a depth of 1 μm in the direction inward of the dielectric layer.

16. The multilayer ceramic capacitor according to claim 15, wherein the content of Al or Zr contained in the interface region of the dielectric layer is 0.1 to 1 atomic part relative to 100 atomic parts of Ni contained in the interface region of the dielectric layer.

17. The steps include: forming a first solution by adding at least one selected from the group consisting of Al precursors and Zr precursors to a solvent; The steps include: adding Ni powder to the first solution to form a second solution; The step of forming a third solution by dispersing the second solution using ultrasonic dispersion; The steps include: drying the third solution to obtain composite particles; The composite particle comprises a core containing Ni, and a shell located on the core and containing a compound comprising at least one of Al and Zr. A method for producing composite particles, wherein the Al or Zr content of the composite particles is 0.001 moles to 5.0 moles per 100 moles of Ni.

18. The method for producing composite particles according to claim 17, wherein the Al precursor contains Al chloride and the Zr precursor contains Zr chloride.

19. The method for producing composite particles according to claim 17, wherein the drying includes applying the third solution to a high-temperature plate and volatilizing the solvent.

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