Multilayer ceramic electronic component

Abstract

To provide a multilayer ceramic electronic component capable of improving an insulation characteristic.SOLUTION: A multilayer ceramic electronic component includes: a substantially cuboid-shaped lamination body in which a dielectric layer and an internal electrode layer are alternately laminated; and an external electrode that is provided to an end surface of the lamination body that is directed in a substantially orthogonal direction to a lamination direction of the lamination body. One end of the internal electrode layer is drawn out to the end surface, and the external electrode is connected to the one end of the internal electrode layer drawn out to the end surface. The lamination body comprises: a metal film that is provided between the internal electrode layer and the dielectric layer; and a dielectric body part hat is provided between the metal film and the internal electrode layer, and contains a plurality of dielectric body particles that are different from a main component of the dielectric layer. An oxygen defect amount of the dielectric body part is smaller than an oxygen defect amount of the dielectric layer.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a multilayer ceramic electronic component. [Background technology]

[0002] For example, Patent Document 1 describes how a donor element is added to the main component ceramic of the dielectric layers of a multilayer ceramic capacitor to suppress the migration of oxygen defects and ensure insulation resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-133501 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the addition of a donor element to the dielectric layer may affect the capacitance, the amount of the donor element that can be added is limited, and there is a risk that the insulating properties cannot be effectively ensured.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a multilayer ceramic electronic component capable of improving insulation characteristics. [Means for solving the problem]

[0006] The multilayer ceramic electronic component of the present invention comprises a laminate having a substantially rectangular parallelepiped shape in which dielectric layers and internal electrode layers are alternately stacked, and an external electrode provided on an end face of the laminate facing a direction substantially perpendicular to the stacking direction of the laminate, one end of the internal electrode layer being extended to the end face, and the external electrode being connected to one end of the internal electrode layer extended to the end face, the laminate comprising a metal film provided between the internal electrode layer and the dielectric layer, and a dielectric portion provided between the metal film and the internal electrode layer and containing a plurality of dielectric particles different from a main component of the dielectric layer, and an amount of oxygen defects in the dielectric portion is smaller than the amount of oxygen defects in the dielectric layer.

[0007] In the above-described multilayer ceramic electronic component, the dielectric layer may have a ceramic material that is a main component thereof having a higher dielectric constant than the dielectric particles.

[0008] In the above-mentioned monolithic ceramic electronic component, the average grain size of the ceramic material that is a main component of the dielectric layers may be equal to or larger than the average grain size of the dielectric grains.

[0009] In the above-mentioned laminated ceramic electronic component, the main component of the metal film may be any one of nickel, tin, gold, and copper.

[0010] In the above-described multilayer ceramic electronic component, the metal film may be provided only on a surface of the dielectric layer in a region sandwiched between two of the internal electrode layers adjacent to the dielectric layer. Effect of the Invention

[0011] According to the present invention, the insulating properties of a multilayer ceramic electronic component can be improved. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing an example of a multilayer ceramic capacitor. [Diagram 2] FIG. 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line AA in FIG. [Diagram 3] FIG. 3 is a cross-sectional view of the multilayer ceramic capacitor taken along line BB in FIG. [Figure 4] FIG. 4 is a cross-sectional view of the multilayer ceramic capacitor taken along line CC in FIG. [Diagram 5] FIG. 5 is an enlarged view showing a part of a cross section of the laminate taken along the lamination direction. [Figure 6] FIG. 6 is a flowchart showing an example of a manufacturing process for a multilayer ceramic capacitor. [Figure 7] FIG. 7 is a cross-sectional view showing the process from the green sheet formation step to the metal film formation step. [Figure 8] FIG. 8 is a cross-sectional view showing an example of the lamination and compression bonding step. [Figure 9] FIG. 9 is a cross-sectional view showing an example of the movement of dielectric particles of a common material in an internal electrode pattern during a firing process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Embodiment] (Structure of multilayer ceramic capacitors) Fig. 1 is a perspective view showing an example of a multilayer ceramic capacitor 1. Fig. 2 is a cross-sectional view of the multilayer ceramic capacitor 1 taken along line AA in Fig. 1. Fig. 3 is a cross-sectional view of the multilayer ceramic capacitor 1 taken along line BB in Fig. 2. Fig. 4 is a cross-sectional view of the multilayer ceramic capacitor 1 taken along line CC in Fig. 2.

[0014] The multilayer ceramic capacitor 1 has a laminate 2 having a substantially rectangular parallelepiped shape, and external electrodes 3a, 3b provided on a pair of opposing end faces 2A, 2B of the laminate 2. The multilayer ceramic capacitor 1 is an example of a multilayer ceramic electronic component. Other examples of multilayer ceramic electronic components include a multilayer ceramic varistor and a multilayer ceramic thermistor, and in this embodiment, the multilayer ceramic capacitor 1 is used as a representative example of these.

[0015] 1 to 4 show mutually orthogonal X, Y, and Z directions. The X direction is the length (L) direction of the multilayer ceramic capacitor 1, and coincides with the direction in which a pair of end faces 2A, 2B of the laminate 2 face each other. The Y direction is the width (W) direction of the multilayer ceramic capacitor 1, and coincides with the direction in which a pair of side faces 2E, 2F of the laminate 2 face each other. The Z direction is the height (T) direction of the multilayer ceramic capacitor 1, and coincides with the direction in which the upper face 2C and the lower face 2D of the laminate 2 face each other and the lamination direction of the laminate 2. The length direction is an example of a direction approximately orthogonal to the lamination direction of the laminate 2, and the end faces 2A, 2B face the length direction.

[0016] The laminate 2 has an upper surface 2C, a lower surface 2D, a pair of end surfaces 2A, 2B, and a pair of side surfaces 2E, 2F. The upper surface 2C and the lower surface 2D are approximately flat surfaces facing each other in the stacking direction, the pair of end surfaces 2A, 2B are approximately flat surfaces facing each other in the length direction, and the pair of side surfaces 2E, 2F are approximately flat surfaces facing each other in the width direction.

[0017] The laminate 2 has a laminated structure in which dielectric layers 22, mainly composed of a ceramic material that functions as a dielectric, and internal electrode layers 23 are alternately laminated, and further a pair of cover layers 20, 21 are laminated so as to sandwich the dielectric layers 22 and the internal electrode layers 23 from both sides in the lamination direction. In the laminate 2, the portion sandwiched between a pair of internal electrode layers 23 adjacent to each dielectric layer 22 contributes to the electrostatic capacitance of the multilayer ceramic capacitor 1, and is sometimes called a "capacitive layer."

[0018] The cover layers 20 and 21 sandwich the capacitive layer from both sides in the stacking direction. Edge portions 200 and 210 having curved surfaces are formed on both ends of the cover layers 20 and 21 in the longitudinal direction, respectively.

[0019] The laminate 2 is also provided with side margins 40, 41 which form the respective side surfaces 2E, 2F. The side margins 40, 41 extend along the length direction and sandwich the laminated region of the internal electrode layers 23 and the dielectric layers 22, i.e., the capacitive layers, from both sides in the width direction. The side margins 40, 41 are mainly composed of the same ceramic material as the dielectric layers 22.

[0020] The internal electrode layers 23 have a generally rectangular shape when viewed from the front in the stacking direction, and face each other in the stacking direction across the dielectric layer 22. One end of the internal electrode layers 23 is alternately extended to the end faces 2A, 2B along the stacking direction and connected to the external electrodes 3a, 3b.

[0021] The dielectric layer 22 has a main phase made of a ceramic material having a perovskite structure represented by the general formula ABO3. 3-α (α indicates a small number.) For example, the ceramic material includes BaTiO3 (barium titanate), CaZrO3 (calcium zirconate), CaTiO3 (calcium titanate), SrTiO3 (strontium titanate), MgTiO3 (magnesium titanate), BaTiO3 (barium titanate) which forms a perovskite structure, 1-x-y Ca x Sr y Ti 1-z Zr z O3 (0≦x≦1, 0≦y≦1, 0≦z≦1), etc. 1-x-y Ca x Sr y Ti 1-z Zr z O3 is barium strontium titanate, barium calcium titanate, barium zirconate, barium titanate zirconate, calcium titanate zirconate, barium calcium titanate zirconate, etc. The thickness of the dielectric layer 22 is, for example, 0.4 to 7.0 (μm) or less.

[0022] The internal electrode layer 23 is mainly composed of a base metal such as Ni (nickel), Cu (copper), or Sn (tin). Noble metals such as Pt (platinum), Pd (palladium), Ag (silver), or Au (gold), or alloys containing these metals, may be used as the internal electrode layer 23. The thickness of the internal electrode layer 23 is, for example, 0.05 to 0.6 (μm) or less.

[0023] The external electrodes 3a, 3b cover the end faces 2A, 2B of the laminate 2 that face each other in the longitudinal direction of the multilayer ceramic capacitor 1. The external electrodes 3a, 3b extend onto the upper face 2C, the lower face 2D, and the side faces 2E, 2F. However, the external electrodes 3a, 3b are spaced apart from each other on the surfaces of the upper face 2C, the lower face 2D, and the side faces 2E, 2F.

[0024] The main components of the external electrodes 3a, 3b include metals such as Ni (nickel) and Cu (copper), etc. The external electrodes 3a, 3b may include a plurality of plating layers having different main components.

[0025] 5 is an enlarged view showing a part of a cross section along the lamination direction of the laminate 2. The laminate 2 includes a metal film 24 provided along the boundary S between the dielectric layer 22 and the internal electrode layer 23, and a shield portion 25 provided between the metal film 24 and the internal electrode layer 23. The shield portion 25 is an example of a dielectric portion, and includes a plurality of dielectric particles 250 that are different from the ceramic material that is the main component of the dielectric layer 22.

[0026] In the manufacturing process of the multilayer ceramic capacitor 1, the dielectric particles 250 are added as a co-material to the conductive paste that forms the internal electrode layer 23. When the laminate 2 is fired, the dielectric particles 250 are pushed out toward the boundary S as the metal particles, which are the main component of the conductive paste, grow, but cannot diffuse beyond the metal film 24 on the boundary S into the dielectric layer 22. At this time, the metal film 24 functions as a partition wall that separates the dielectric particles 250 from the dielectric layer 22. For this reason, the dielectric particles 250 are segregated on the surface of the internal electrode layer 23 on the boundary S side to form the shield portion 25. Since the dielectric particles 250 do not diffuse into the dielectric layer 22, a decrease in the dielectric constant of the dielectric layer 22 is also suppressed.

[0027] The metal films 24 are formed so as to sandwich each internal electrode layer 23 from above and below in the stacking direction. As shown in Figs. 2 to 4, the metal film 24 is provided so as to cover a region R of the surface of the dielectric layer 22 that is sandwiched between two internal electrode layers 23 adjacent to the dielectric layer 22 in the length direction and width direction, but not to cover other regions. In other words, the metal film 24 is provided only in the region R that corresponds to the capacitance portion, and the metal film 24 is not provided on the lead-out portion 23e of the internal electrode layer 23 that is connected to the external electrodes 3a and 3b. For this reason, the metal film 24 can be omitted from the region in the laminate 2 where no capacitance is generated.

[0028] Furthermore, when the laminate 2 is fired in a reducing atmosphere, oxygen defects 220 are generated by a reduction reaction in the perovskite structure constituting the ceramic material of the dielectric layers 22. When the external electrodes 3a, 3b are energized and an electric field is applied to the laminate 2, the oxygen defects 220 move toward the negative internal electrode layer 23 in the direction of the applied electric field, as shown by the arrow. If the oxygen defects 220 reach the internal electrode layer 23, the electrical resistance in the region near the boundary S decreases, and the insulating properties of the laminated ceramic capacitor 1 deteriorate.

[0029] However, since the shielding portion 25 is provided between the internal electrode layer 23 and the metal film 24, the oxygen defects 220 cannot reach the internal electrode layer 23. Here, as the dielectric particles 250 constituting the shielding portion 25, a material that is unlikely to cause oxygen defects, such as a paraelectric zirconium-based ceramic material or a ferroelectric ceramic material in which molybdenum and manganese are solid-solved, is used.

[0030] As a result, the amount of oxygen defects in the shield portion 25 is smaller than the amount of oxygen defects in the dielectric layer 22. Even if the oxygen defects 220 in the dielectric layer 22 move through the metal film 24, they cannot move through the shield portion 25. In this way, the shield portion 25 functions as a barrier against the oxygen defects 220, thereby suppressing the movement of the oxygen defects 220, thereby improving the insulation characteristics of the multilayer ceramic capacitor 1. The amount of oxygen defects is defined as, for example, the number of oxygen defects per unit volume.

[0031] In order to more effectively improve the insulating characteristics, the dielectric constant of the ceramic material that is the main component of the dielectric layer 22 is preferably larger than the dielectric constant of the dielectric particles 250 of the shield portion 25. In addition, the average grain size of the ceramic material that is the main component of the dielectric layer 22 is preferably equal to or larger than the average grain size of the dielectric particles 250 of the shield portion 25.

[0032] Moreover, the main component of the metal film 24 is preferably any one of nickel, tin, gold, and copper. This makes it possible to more effectively suppress the diffusion of the dielectric particles 250 into the dielectric layer 22, compared to when the main component of the metal film 24 is another metal.

[0033] (Manufacturing process of multilayer ceramic capacitors) 6 is a flow chart showing an example of a manufacturing process for the multilayer ceramic capacitor 1. This manufacturing process is an example of a method for manufacturing a multilayer ceramic electronic component.

[0034] 7 is a cross-sectional view showing the process from the green sheet forming step St1 to the metal film forming step St4. FIG 7 shows a cross section of the multilayer ceramic capacitor 1 along the lamination direction and the length direction.

[0035] (Green sheet formation process) First, a green sheet forming step St1 is performed. In the green sheet forming step St1, a ceramic slurry is applied onto a substrate (not shown) to form a green sheet 7a. The ceramic slurry is obtained by adding various additive compounds (such as sintering aids) to ceramic powder, for example, to a dielectric material, and then wet-mixing the dielectric material with a binder such as polyvinyl butyral (PVB) resin, an organic solvent such as ethanol or toluene, and a plasticizer. The ceramic slurry is applied onto the substrate by, for example, a die coater method or a doctor blade method, and then dried. The substrate is, for example, a PET (polyethylene terephthalate) film.

[0036] As additive compounds for the ceramic powder, oxides of Mg (magnesium), Mn (manganese), V (vanadium), Cr (chromium), rare earth elements (Y (yttrium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium) and Yb (ytterbium)), as well as oxides or glasses of Co (cobalt), Ni, Li (lithium), B (boron), Na (sodium), K (potassium) and Si (silicon) are used.

[0037] (Metal film formation process) Next, a metal film forming step St2 is performed. In the metal film forming step St2, a metal film 80a is formed on the green sheet 7a by using a vacuum deposition method such as sputtering. The metal film 80a becomes the metal film 24 after firing.

[0038] (Internal electrode pattern formation process) Next, the internal electrode pattern forming process St3 is performed. In the internal electrode pattern forming process St3, the conductive paste containing the dielectric particles 250 described above is applied onto the metal film 80a and onto the green sheet 7a between the two adjacent metal films 80a to form the internal electrode pattern 6a. The internal electrode pattern 6a becomes the internal electrode layer 23 after firing.

[0039] In the internal electrode pattern forming process St3, a metal conductive paste for forming internal electrodes containing an organic binder is printed on the green sheet 7a by gravure printing or the like to form a plurality of internal electrode patterns 6a spaced apart from one another. Dielectric particles 250 are added to the conductive paste as a co-material. The main component of the dielectric particles 250 is different from the main component of the green sheet 7a. The internal electrode patterns 6a may be formed by a vacuum deposition method such as sputtering, without being limited to printing.

[0040] (Metal film formation process) Next, a metal film forming step St4 is performed. In the metal film forming step St4, a metal film 81a is formed on the internal electrode pattern 6a by using a vacuum deposition method such as sputtering. The metal film 81a becomes the metal film 24 after firing. The metal film 81a is formed at substantially the same position as the metal film 80a in the length direction and width direction and with the same size. Note that, in the internal electrode pattern 6a, a region where the metal films 80a, 81a are not provided becomes the lead portion 23e after firing.

[0041] Furthermore, by the same process as above, an internal electrode pattern 6b and metal films 80b, 81b shifted in the length direction by half a pitch from the internal electrode pattern 6a and the metal films 80a, 81a are formed on another green sheet 7b.

[0042] (Lamination and bonding process) Next, a lamination and compression bonding step St5 is performed. In the lamination and compression bonding step St5, a plurality of green sheets 7a, 7b are alternately laminated and compressed.

[0043] Fig. 8 is a cross-sectional view showing an example of the lamination and compression bonding step St5 Fig. 8 shows a cross section along the length direction and lamination direction.

[0044] The green sheets 7a and 7b are sandwiched and pressed from above and below in the stacking direction by other green sheets 7c and 7d that will become cover layers 20 and 21 after firing. An internal electrode pattern 6b is formed on the surface of the bottommost green sheet 7d by a method similar to that of the internal electrode pattern forming step St3, and metal films 80b and 81b are formed by a method similar to that of the metal film forming steps St2 and St4. Examples of pressing means include, but are not limited to, a hydrostatic press.

[0045] (cutting process) Next, a cutting step St6 is performed. In the cutting step St6, the compressed green sheets 7a-7d are cut, for example, by a blade along a plurality of cutting lines LW extending lengthwise and widthwise at regular intervals. As a result, the green sheets 7a-7d are divided into a plurality of pre-fired laminates 2. FIG. 8 shows the cutting lines LW extending along the width direction of the laminate 2. Ends of the internal electrode patterns 6a, 6b are exposed on the end faces 2A, 2B, which are the cut surfaces of the laminate 2.

[0046] (polishing process) Next, a polishing step St7 is performed. In the polishing step St7, the laminate 2 is polished by a method such as barrel polishing. As a result, the corners of the laminate 2 are rounded to form edge portions 200, 210.

[0047] (Firing process) Next, a firing step St8 is performed. In the firing step St8, the laminate 2 before firing is subjected to a binder removal process in an N2 atmosphere at 250 to 500°C, and then fired at a firing temperature of 1200°C or higher for about 1 hour in a reducing atmosphere with an oxygen partial pressure of 0.003 (Pa), thereby sintering each particle in the laminate 2. As a result, in the laminate 2, the green sheets 7a to 7d become the dielectric layer 22 and the cover layers 20 and 21, and the internal electrode patterns 6a and 6b become the internal electrode layer 23.

[0048] Fig. 9 is a cross-sectional view showing an example of the movement of dielectric particles 250 of a common material in the internal electrode pattern 6a in the firing step St8. Fig. 9 shows an enlarged view of a region P of the cross section shown in Fig. 8. In Fig. 9, the same components as those in Fig. 8 are denoted by the same reference numerals, and the description thereof will be omitted.

[0049] In the internal electrode pattern 6a, dielectric particles 250 of the common material are distributed around the metal particles 60 of the main component. When the firing step St8 is started, the metal particles 60 grow, and the dielectric particles 250 are pushed out toward the metal films 80b and 81a adjacent above and below in the stacking direction, as shown by the arrows. This forms the shield section 25 as shown in FIG. 5. The dielectric particles 250 of the common material in the internal electrode pattern 6b are also pushed out toward the metal films 81b and 80a in the same manner as above, forming the shield section 25.

[0050] (External electrode formation process) Next, an external electrode forming step St9 is performed. In the external electrode forming step St9, a conductive paste containing, for example, metal powder, glass frit, binder, and solvent is applied to each end face 2A, 2B, upper face 2C, lower face 2D, and each side face 2E, 2F of the laminate 2. After the conductive paste is applied, it is dried to form the external electrodes 3a, 3b. The binder and the solvent are evaporated by baking. Examples of the method for applying the conductive paste include a sputtering method and a dipping method. In this manner, the multilayer ceramic capacitor 1 is manufactured.

[0051] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0052] 1. Multilayer ceramic capacitors 2. Laminate 3a,3b External electrode 6a, 6b Internal electrode pattern 7a~7d Green sheets 22 Dielectric layer 23 Internal electrode layer 24 Metal Film 250 Dielectric Particles

Claims

1. a laminate having a substantially rectangular parallelepiped shape in which dielectric layers and internal electrode layers are alternately laminated; an external electrode provided on an end surface of the laminate facing in a direction substantially perpendicular to the lamination direction of the laminate; One end of the internal electrode layer is extended to the end surface, the external electrode is connected to one end of the internal electrode layer that is extended to the end surface, the laminate comprises a metal film provided between the internal electrode layer and the dielectric layer, and a dielectric portion provided between the metal film and the internal electrode layer and containing a plurality of dielectric particles different from a main component of the dielectric layer, a dielectric portion having an oxygen defect amount smaller than that of the dielectric layer;

2. 2. The multilayer ceramic electronic component according to claim 1, wherein the dielectric constant of the ceramic material that is the main component of the dielectric layers is greater than the dielectric constant of the dielectric particles.

3. 3. The multilayer ceramic electronic component according to claim 1, wherein the average grain size of the ceramic material that is the main component of the dielectric layers is equal to or larger than the average grain size of the dielectric grains.

4. 3. The multilayer ceramic electronic component according to claim 1, wherein a main component of said metal film is any one of nickel, tin, gold, and copper.

5. 3. The multilayer ceramic electronic component according to claim 1, wherein the metal film is provided only on a surface of the dielectric layer in an area sandwiched between two of the internal electrode layers adjacent to the dielectric layer.

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