Ceramic electronic components and methods for manufacturing the same

Abstract

To provide a ceramic electronic component capable of improving the moisture resistance reliability thereof, and a manufacturing method thereof.SOLUTION: A ceramic electronic component includes: an elementary body including a plurality of dielectric layers and a plurality of internal electrode layers laminated via the dielectric layers and provided to face each other while one end of each internal electrode is exposed; a ground layer that is provided on an end face of the elementary body, the end face being an end in a direction where the internal electrode layers are extended, and that comes into contact with the one end of each of the internal electrode layers, the ground layer containing Cu as main components; a Ni plating layer formed on the ground layer; and metal oxide particles disposed on a surface of the ground layer on a Ni plating layer side or on a surface of a metal layer disposed between the ground layer and the Ni plating layer on the Ni plating layer side. The metal oxide particles are an oxide of a metal other than Cu when being disposed on the surface of the ground layer, while the metal oxide particles are an oxide of a metal other than a main component metal of the metal layer when being disposed on the surface of the metal layer.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] In recent years, ceramic electronic components such as multilayer ceramic capacitors have expanded their applications to include automotive use, and there is a growing demand for even higher reliability levels. Therefore, highly moisture-resistant multilayer ceramic capacitors have been disclosed (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-72246 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, during the plating process to form a Ni plating layer on the underlayer, hydrogen may diffuse into the interior of the ceramic electronic component, potentially reducing its moisture resistance reliability.

[0005] This invention has been made in view of the above problems, and aims to provide a ceramic electronic component and a method for manufacturing the same that can improve moisture resistance reliability. [Means for solving the problem]

[0006] The ceramic electronic component according to the present invention comprises a base body having a plurality of dielectric layers and a plurality of internal electrode layers laminated via the plurality of dielectric layers and provided so that one end is exposed and facing each other; a base layer mainly composed of Cu provided on the end face of the base body which is the end in the direction in which the plurality of internal electrode layers are stretched, and in contact with each of the one ends of the plurality of internal electrode layers; a Ni plating layer formed on the base layer; and metal oxide particles disposed on the surface of the base layer on the Ni plating layer side, or on the surface of a metal layer disposed between the base layer and the Ni plating layer on the Ni plating layer side, wherein the metal oxide particles are an oxide of a metal other than Cu when disposed on the surface of the base layer, and are an oxide of a metal other than the main component metal of the metal layer when disposed on the surface of the metal layer.

[0007] In the above-described ceramic electronic component, the metal oxide particles may be alumina particles or zirconia particles.

[0008] Another ceramic electronic component according to the present invention comprises a base body having a plurality of dielectric layers and a plurality of internal electrode layers laminated via the plurality of dielectric layers and provided so that one end is exposed and facing each other; a base layer mainly composed of Cu provided on the end face of the base body which is the end in the direction in which the plurality of internal electrode layers are stretched, and in contact with each of the one ends of the plurality of internal electrode layers; a Ni plating layer formed on the base layer; and metal oxide particles disposed on the surface of the base layer on the Ni plating layer side, or on the surface of a metal layer disposed between the base layer and the Ni plating layer on the Ni plating layer side, wherein the metal oxide particles are alumina particles or zirconia particles.

[0009] In the above-mentioned ceramic electronic component, the average particle size of the metal oxide particles may be 0.1 μm or more and 8.0 μm or less.

[0010] In the above-described ceramic electronic component, the metal oxide particles may be arranged on the surface of the underlying layer on the Ni plating layer side.

[0011] Another ceramic electronic component according to the present invention comprises a base body having a plurality of dielectric layers and a plurality of internal electrode layers laminated via the plurality of dielectric layers and provided so that one end is exposed and facing each other; a base layer provided on the end face of the base body which is the end in the direction in which the plurality of internal electrode layers are stretched, and which is in contact with one end of each of the plurality of internal electrode layers; a Ni plating layer formed on the base layer; and metal oxide particles disposed on the surface of the base layer on the Ni plating layer side, or on the surface of a metal layer disposed between the base layer and the Ni plating layer on the Ni plating layer side, wherein the metal oxide particles are an oxide of a metal other than Cu when disposed on the surface of the base layer, and are an oxide of a metal other than the main component metal of the metal layer when disposed on the surface of the metal layer, and the average particle size of the metal oxide particles is 0.1 μm or more and 8.0 μm or less.

[0012] In the above-described ceramic electronic component, a Cu plating layer may be provided between the underlayer and the Ni plating layer, and the metal oxide particles may be arranged on the surface of the Cu plating layer on the Ni plating layer side.

[0013] In the above-described ceramic electronic component, the underlayer may be a sintered body of Ni.

[0014] In the above-described ceramic electronic component, the metal oxide particles may be alumina particles or zirconia particles.

[0015] In the above-described ceramic electronic component, a void is formed on the surface of the underlayer on the Ni plating layer side, or on the surface of the metal layer disposed between the underlayer and the Ni plating layer on the Ni plating layer side, and the metal oxide particles may be disposed in the void.

[0016] A method for manufacturing a ceramic electronic component according to the present invention includes the steps of: preparing a base body having a plurality of dielectric layers and a plurality of internal electrode layers laminated via the plurality of dielectric layers and provided so that one end is exposed and facing each other; baking a Cu-based underlayer on the end face of the base body, which is the end in the direction in which the plurality of internal electrode layers are stretched, so as to be in contact with one end of each of the plurality of internal electrode layers; and arranging metal oxide particles on the surface of the underlayer or on the surface of a metal layer formed on the underlayer, and then forming a Ni plating layer, wherein the metal oxide particles are an oxide of a metal other than Cu when arranged on the surface of the underlayer, and an oxide of a metal other than the main component metal of the metal layer when arranged on the surface of the metal layer.

[0017] Another method for manufacturing a ceramic electronic component according to the present invention includes the steps of: preparing a ceramic laminate having a plurality of dielectric green sheets and a plurality of internal electrode patterns laminated on the plurality of dielectric green sheets and arranged so that one end is exposed and facing each other; applying a conductive paste mainly composed of Cu to the end face of the ceramic laminate which is the end in the direction in which the plurality of internal electrode patterns are stretched, and which is in contact with one end of each of the plurality of internal electrode patterns; forming a base layer from the conductive paste by firing the ceramic laminate and the conductive paste simultaneously; and arranging metal oxide particles on the surface of the base layer or on the surface of a metal layer formed on the base layer, and then forming a Ni plating layer, wherein the metal oxide particles are an oxide of a metal other than Cu when arranged on the surface of the base layer, and an oxide of a metal other than the main component metal of the metal layer when arranged on the surface of the metal layer, and the average particle size of the metal oxide particles is 0.1 μm or more and 8.0 μm or less. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide ceramic electronic components and methods for manufacturing the same that can improve moisture resistance reliability. [Brief explanation of the drawing]

[0019] [Figure 1] It is a partial cross-sectional perspective view of a multilayer ceramic capacitor. [Figure 2] It is a cross-sectional view taken along line A-A of FIG. 1. [Figure 3] It is a cross-sectional view taken along line B-B of FIG. 1. [Figure 4] (a) and (b) are enlarged cross-sectional views near the external electrodes. [Figure 5] It is an enlarged cross-sectional view near the external electrodes. [Figure 6] It is a diagram illustrating the flow of a method for manufacturing a multilayer ceramic capacitor. [Figure 7] (a) and (b) are diagrams illustrating the lamination process. [Figure 8] (a) and (b) are enlarged cross-sectional views near the external electrodes. [Figure 9] It is an enlarged cross-sectional view near the external electrodes. [Figure 10] It is a diagram illustrating the flow of a method for manufacturing a multilayer ceramic capacitor.

BEST MODE FOR CARRYING OUT THE INVENTION

[0020] Hereinafter, each embodiment will be described with reference to the drawings.

[0021] (First Embodiment) First, an overview of a multilayer ceramic capacitor, which is an example of a ceramic electronic component, will be described. FIG. 1 is a partial cross-sectional perspective view of a multilayer ceramic capacitor 100 according to the first embodiment. As illustrated in FIG. 1, the multilayer ceramic capacitor 100 includes a rectangular parallelepiped-shaped element body 10 and external electrodes 20a and 20b provided on two opposing end faces of the element body 10. The two end faces are the end faces in the direction in which the internal electrode layer 12 extends. Among the four faces of the element body 10 other than the two end faces, the two faces other than the upper and lower faces in the lamination direction are referred to as side faces. The external electrodes 20a and 20b extend on the upper face, lower face, and two side faces of the element body 10 in the lamination direction. However, the external electrodes 20a and 20b are spaced apart from each other.

[0022] The base body 10 has a structure in which dielectric layers 11 containing a ceramic material that functions as a dielectric and internal electrode layers 12 containing a base metal material are alternately stacked. One end of each internal electrode layer 12 is alternately exposed to the end face of the base body 10 where the external electrode 20a is provided and the end face where the external electrode 20b is provided. As a result, each internal electrode layer 12 is alternately electrically connected to the external electrode 20a and the external electrode 20b. Consequently, the multilayer ceramic capacitor 100 has a structure in which multiple dielectric layers 11 are stacked via internal electrode layers 12. Furthermore, in the laminate of dielectric layers 11 and internal electrode layers 12, the outermost layer in the stacking direction is an internal electrode layer 12, and the top and bottom surfaces of the laminate are covered by a cover layer 13. The cover layer 13 is mainly composed of a ceramic material. For example, the main components of the cover layer 13 are the same as those of the dielectric layer 11 and the ceramic material.

[0023] The dimensions of the multilayer ceramic capacitor 100 are, for example, 0.25 mm in length, 0.125 mm in width, and 0.125 mm in height, or 0.4 mm in length, 0.2 mm in width, and 0.2 mm in height, or 0.6 mm in length, 0.3 mm in width, and 0.3 mm in height, or 1.0 mm in length, 0.5 mm in width, and 0.5 mm in height, or 1.6 mm in length, 0.8 mm in width, and 0.8 mm in height, or 3.2 mm in length, 1.6 mm in width, and 1.6 mm in height, or 4.5 mm in length, 3.2 mm in width, and 2.5 mm in height, but are not limited to these dimensions.

[0024] The internal electrode layer 12 mainly consists of base metals such as nickel (Ni), copper (Cu), and tin (Sn). Precious metals such as platinum (Pt), palladium (Pd), silver (Ag), and gold (Au), or alloys containing these, may also be used as the internal electrode layer 12. The internal electrode layer 12 may also contain ceramic particles as a co-material.

[0025] The dielectric layer 11 mainly consists of a ceramic material having a perovskite structure represented by the general formula ABO3. Note that this perovskite structure is an ABO3 structure that deviates from the stoichiometric composition. 3-αIt includes. For example, as the ceramic material, BaTiO3 (barium titanate), CaZrO3 (calcium zirconate), CaTiO3 (calcium titanate), SrTiO3 (strontium titanate), MgTiO3 (magnesium titanate), Ba that 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., can be selected and used from at least one of them. Ba 1-x-y Ca x Sr y Ti 1-z Zr z O3 includes strontium barium titanate, barium calcium titanate, barium zirconate, barium zirconium titanate, calcium zirconium titanate, and barium calcium zirconium titanate, etc.

[0026] An additive may be added to the dielectric layer 11. Examples of additives to the dielectric layer 11 include oxides of magnesium (Mg), manganese (Mn), molybdenum (Mo), vanadium (V), chromium (Cr), rare earth elements (yttrium (Y), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), and ytterbium (Yb)), or oxides containing cobalt (Co), nickel (Ni), lithium (Li), boron (B), sodium (Na), potassium (K), or silicon (Si), or glasses containing cobalt, nickel, lithium, boron, sodium, potassium, or silicon.

[0027] As illustrated in Figure 2, the region where the internal electrode layer 12 connected to the external electrode 20a and the internal electrode layer 12 connected to the external electrode 20b face each other is the region in the multilayer ceramic capacitor 100 where capacitance is generated. Therefore, this region where capacitance is generated is referred to as the capacitance section 14. In other words, the capacitance section 14 is the region where adjacent internal electrode layers 12 connected to different external electrodes face each other.

[0028] The region in which internal electrode layers 12 connected to external electrode 20a face each other without being connected to an internal electrode layer 12 connected to external electrode 20b is called the end margin 15. Similarly, the region in which internal electrode layers 12 connected to external electrode 20b face each other without being connected to an internal electrode layer 12 connected to external electrode 20a is also called the end margin 15. In other words, the end margin 15 is the region in which internal electrode layers 12 connected to the same external electrode face each other without being connected to an internal electrode layer 12 connected to a different external electrode. The end margin 15 is a region in which no capacitance is generated. The end margin 15 may have the same composition as the dielectric layer 11 of the capacitance portion 14, or it may have a different composition.

[0029] As illustrated in Figure 3, in the base body 10, the region extending from the two sides of the base body 10 to the internal electrode layer 12 is called the side margin 16. That is, the side margin 16 is a region provided so as to cover the ends of the multiple internal electrode layers 12 stacked in the above-described laminated structure that extend to the two sides. The side margin 16 is also a region that does not generate capacitance. The side margin 16 may have the same composition as the dielectric layer 11 of the capacitance portion 14, or it may have a different composition.

[0030] Figure 4(a) is an enlarged cross-sectional view of the vicinity of the external electrode 20a. Hatches are omitted in Figure 4(a). As illustrated in Figure 4(a), the external electrode 20a has a structure in which a plating layer 22 is provided on a base layer 21. The plating layer 22 mainly consists of metals such as Cu, Ni, Al, Zn, Sn, or two or more alloys thereof. The plating layer 22 may be a plating layer of a single metal component, or it may be multiple plating layers of different metal components. The plating layer 22 includes at least a Ni plating layer, and a metal layer mainly composed of a metal other than Ni may be formed between the Ni plating layer and the base layer 21. For example, the plating layer 22 has a structure in which a Ni plating layer 23 and a Sn plating layer 24 are formed in order from the base layer 21 side. Although Figure 4(a) illustrates the external electrode 20a, the external electrode 20b has a similar laminated structure.

[0031] The base layer 21 is a sintered body mainly composed of Cu, and is added to the base body 10 after firing by firing. The base layer 21 contains a glass component to lower the firing temperature. The glass component is, for example, an oxide of Ba, Ca, Zn, Al, Si, Mg, or B. Metal oxide particles 30 are dispersed on the surface of the base layer 21 on the Ni plating layer 23 side. The metal oxide particles 30 are oxides of a metal different from the main component metal of the base layer 21, and are crystalline ceramics. Therefore, the metal oxide particles 30 are different from the glass component. For example, the metal oxide particles 30 may be arranged on the smooth surface of the base layer 21 on the Ni plating layer 23 side, or they may be arranged in voids 40 formed by irregularities formed on the surface of the base layer 21 on the Ni plating layer 23 side, as illustrated in Figure 4(b). In this case, the metal oxide particles 30 may be arranged to fill the voids 40, or they may be arranged in part of the voids 40.

[0032] By arranging metal oxide particles 30 on the surface of the base layer 21 facing the Ni plating layer 23, hydrogen generated during the formation of the Ni plating layer 23 can be adsorbed onto the metal oxide particles 30. This suppresses hydrogen absorption into the substrate 10. As a result, the moisture resistance reliability of the multilayer ceramic capacitor 100 is improved. Furthermore, since the metal oxide particles 30 have higher chemical resistance than glass, they tend to remain without being etched even after the plating process is carried out.

[0033] Furthermore, since the metal oxide particles 30 are arranged on the surface of the underlayer 21, the restraint of the metal oxide particles 30 by the underlayer 21 is suppressed, and the metal oxide particles 30 exhibit a buffering effect against stress. By increasing the amount of metal oxide particles 30 at the corners, top surface, bottom surface, and two sides of the base body 10 compared to the end face of the base body 10, delamination between the underlayer 21 and the plating layer 22 becomes more likely at the corners, top surface, bottom surface, and two sides of the base body 10, thereby mitigating the stress applied to the base body 10 when the multilayer ceramic capacitor 100 is mounted on the substrate.

[0034] The metal oxide particles 30 are, for example, alumina particles, zirconia particles, etc., but are not particularly limited. The average particle size of the metal oxide particles 30 is, for example, 0.1 μm or more and 8.0 μm or less. When alumina particles are used as the metal oxide particles 30, for example, the average particle size of the metal oxide particles 30 is 0.1 μm or more and 8.0 μm or less, preferably 0.25 μm or more and 1.5 μm or less. Alumina particles can be selected from those that are generally available on the market and used within a given particle size range. When zirconia particles are used as the metal oxide particles 30, for example, the average particle size of the metal oxide particles 30 is 0.15 μm or more and 4.5 μm or less, preferably 0.20 μm or more and 4.0 μm or less.

[0035] In addition, in the multilayer ceramic capacitor 100, the average particle size of the metal oxide particles 30 can be measured by taking a cross-sectional SEM image at 5000 to 20000x magnification, measuring the directional diameter (Ferret diameter) of 30 oxide particles, and taking the average value.

[0036] The thickness of the underlayer 21 is, for example, 1 μm to 100 μm, 2.5 μm to 75 μm, and 5 μm to 50 μm. The thickness of the Ni plating layer 23 is, for example, 0.1 μm to 10 μm, 0.2 μm to 5 μm, and 0.5 μm to 2.5 μm. The thickness of the Sn plating layer 24 is, for example, 0.5 μm to 20 μm, 1 μm to 10 μm, and 0.5 μm to 5 μm.

[0037] Assuming the area of ​​the base layer 21 is 100%, the area ratio of the metal oxide particles 30 is between 0.01% and 20%, between 0.1% and 10%, and between 0.5% and 5%. The area ratio can be calculated, for example, by determining the area of ​​the base layer 21 and the metal oxide particles 30 from the cross-sectional photograph in Figure 4(a) using image processing software. When checking the area ratio for each end face or side surface of the base layer 21, the entire area of ​​the end face or side surface can be used as the denominator for the calculation.

[0038] In the example shown in Figure 4(a), a Ni plating layer 23 is formed on the underlayer 21, but the example is not limited to this. For example, as illustrated in Figure 5, another plating layer 25 may be formed on the underlayer 21. In this case, the metal oxide particles 30 may be arranged on the surface of the underlayer 21 on the Ni plating layer 23 side, or on the surface of the plating layer 25 on the Ni plating layer 23 side. For example, the plating layer 25 may be mainly composed of Cu, and the metal oxide particles 30 may be an oxide of a metal different from the main component metal of the plating layer 25. Also, for example, a conductive resin layer may be present on the underlayer 21 instead of a plating layer.

[0039] Next, the manufacturing method of the multilayer ceramic capacitor 100 will be described. Figure 6 is a diagram illustrating the flow of the manufacturing method of the multilayer ceramic capacitor 100.

[0040] (Process for producing raw material powder) First, a dielectric material for forming the dielectric layer 11 is prepared. The main component ceramic powder of the dielectric layer 11 can be obtained by synthesizing the constituent materials. Various methods for synthesizing the main component ceramic of the dielectric layer 11 are conventionally known, such as the solid-phase method, the sol-gel method, and the hydrothermal method. In this embodiment, any of these methods can be employed.

[0041] A predetermined additive compound is added to the obtained ceramic powder according to the purpose. Examples of additive compounds include oxides of magnesium (Mg), manganese (Mn), molybdenum (Mo), vanadium (V), chromium (Cr), rare earth elements (yttrium (Y), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holomium (Ho), erbium (Er), thulium (Tm), and ytterbium (Yb)), or oxides containing cobalt (Co), nickel (Ni), lithium (Li), boron (B), sodium (Na), potassium (K), or silicon (Si), or glass containing cobalt, nickel, lithium, boron, sodium, potassium, or silicon. Of these, SiO2 mainly functions as a sintering aid.

[0042] For example, a ceramic material can be prepared by wet-mixing a ceramic raw material powder with a compound containing an additive, followed by drying and pulverization. For example, the ceramic material obtained as described above may be subjected to pulverization as needed to adjust the particle size, or the particle size may be adjusted by combining this with a classification process. Through the above steps, a raw material powder can be obtained.

[0043] (Coating process) Next, a binder such as polyvinyl butyral (PVB) resin, an organic solvent such as ethanol or toluene, and a plasticizer are added to the obtained raw material powder and wet-mixed. Using the resulting slurry, a dielectric green sheet 52 is coated onto the substrate 51 by, for example, a die coater or doctor blade method and then dried. The substrate 51 is, for example, a PET (polyethylene terephthalate) film.

[0044] (Internal electrode formation process) Next, as illustrated in Figure 7(a), an internal electrode pattern 53 is deposited on the dielectric green sheet 52. In Figure 7(a), as an example, four layers of the internal electrode pattern 53 are deposited on the dielectric green sheet 52 at predetermined intervals. The dielectric green sheet 52 on which the internal electrode pattern 53 has been deposited is used as the stacking unit.

[0045] A metal paste of the main component metal of the internal electrode layer 12 is used for the internal electrode pattern 53. The film deposition method may be printing, sputtering, or vapor deposition.

[0046] (Crimping process) Next, the dielectric green sheet 52 is peeled off the substrate 51, and the laminate units are stacked as illustrated in Figure 7(b). Then, a predetermined number of cover sheets 54 (for example, 2 to 10 layers) are stacked on the top and bottom of the laminate obtained by stacking the laminate units, and then heat-pressed and cut to a predetermined chip size. In the example in Figure 7(b), the cutting is done along the dotted line. The cover sheets 54 may have the same composition as the dielectric green sheet 52, or they may have different additives.

[0047] (Firing process) The ceramic laminate obtained in this way is then subjected to a binder removal treatment in an N2 atmosphere, followed by an oxygen partial pressure of 10 -5 ~10 -8 The material is fired in an ATM reducing atmosphere at 1100°C to 1300°C for 10 minutes to 2 hours. In this way, the base material 10 can be fired.

[0048] (Re-oxidation process) Subsequently, a re-oxidation treatment may be performed in an N2 gas atmosphere at 600°C to 1000°C.

[0049] (Baking process) Next, a metal paste, which will form the base layer 21, is applied to both end faces of the base body 10 using a dipping method or the like. The metal paste contains glass. For example, the metal paste is applied to the base body 10 so that it extends to at least one of the four faces other than the two end faces where the internal electrode layer 12 is exposed. After that, the metal paste is baked at, for example, around 700°C to 900°C to form the base layer 21.

[0050] (Oxide particle placement process) Next, the substrate 10 on which the base layer 21 is formed is heated in a non-oxidizing atmosphere, then exposed to an oxidizing atmosphere while maintaining this temperature, and then cooled back to a non-oxidizing atmosphere. For example, the substrate is heated to about 500°C in an N2 atmosphere, and then the atmosphere is changed to air while maintaining this temperature. After maintaining this state for about 2 minutes, it is cooled back to an N2 atmosphere. Through this oxidation treatment, the surface of the base layer 21 is rapidly oxidized at a high temperature. Next, the surface is acid-treated with a dilute sulfuric acid solution to remove the oxides from the surface. Since the oxides are formed not only on the surface of the base layer 21 but also in the thickness direction, mixed with metallic copper, the areas where copper oxide is removed from these mixed areas of metallic copper and copper oxide become voids 40 when viewed in cross-section. Metal oxide particles 30 are placed in these voids 40 by sprinkling them.

[0051] Alternatively, the metal oxide particles 30 may be arranged without forming voids 40. In this case, the oxidation and acid treatments may be omitted, and the metal oxide particles 30 may be arranged by sprinkling them onto the surface of the substrate layer 21. (Plating process) Subsequently, a plating layer 22 is formed on the underlayer 21 by a plating process. In the configuration shown in Figure 4(a), a Ni plating layer 23 and a Sn plating layer 24 are formed sequentially by the plating process.

[0052] According to the manufacturing method of this embodiment, by arranging metal oxide particles 30 on the surface of the base layer 21 on the Ni plating layer 23 side, hydrogen generated during the formation of the Ni plating layer 23 can be adsorbed onto the metal oxide particles 30. This suppresses hydrogen absorption into the substrate 10. As a result, the moisture resistance reliability of the multilayer ceramic capacitor 100 is improved.

[0053] In the configuration shown in Figure 5, a plating layer 25 can be formed on the surface of the underlayer 21 by a plating treatment, and then the metal oxide particles 30 can be placed on the surface of the plating layer 25. Alternatively, voids 40 can be formed on the surface of the plating layer 25 by oxidation and acid treatment, and then the metal oxide particles 30 can be placed.

[0054] (Second Embodiment) Next, a second embodiment will be described. The differences from the first embodiment will be explained. Figure 8(a) is an enlarged cross-sectional view of the vicinity of the external electrode 20a. In Figure 8(a), the hatches have been omitted. As illustrated in Figure 8(a), the external electrode 20a has a structure in which a plating layer 22 is provided on a base layer 21a. The plating layer 22 mainly consists of metals such as Cu, Ni, Al, Zn, Sn, or two or more alloys thereof. The plating layer 22 may be a plating layer of a single metal component, or it may be multiple plating layers of different metal components. The plating layer 22 includes at least a Ni plating layer, and a metal layer mainly composed of a metal other than Ni may be formed between the Ni plating layer and the base layer 21a. For example, the plating layer 22 has a structure in which a Ni plating layer 23 and a Sn plating layer 24 are formed in order from the base layer 21a side. Although Figure 8(a) illustrates the external electrode 20a, the external electrode 20b has a similar laminated structure.

[0055] The base layer 21a is a sintered body mainly composed of Ni, and is fired simultaneously with the firing of the base body 10. The base layer 21a may contain ceramic particles as a co-material to minimize the difference in sintering behavior with that of the base body 10. The co-material has the same composition as, for example, the main component ceramic of the dielectric layer 11. The average particle size of the co-material is, for example, 0.5 μm to 8 μm. Metal oxide particles 30 are dispersed on the surface of the base layer 21a on the Ni plating layer 23 side. The metal oxide particles 30 are oxides of a metal different from the main component metal of the base layer 21a, and are crystalline ceramics. For example, the metal oxide particles 30 may be arranged on the smooth surface of the base layer 21a on the Ni plating layer 23 side, or, as illustrated in Figure 8(b), they may be arranged in voids 40 formed by irregularities formed on the surface of the base layer 21a on the Ni plating layer 23 side.

[0056] The metal oxide particles 30 have a different composition from the co-material. Furthermore, the metal oxide particles 30 have an average particle size between 0.1 μm and 8.0 μm. Therefore, the metal oxide particles 30 are distinct from the co-material. The average particle size of the co-material can be measured using the same method as the average particle size of the metal oxide particles 30.

[0057] By arranging metal oxide particles 30 on the surface of the base layer 21a facing the Ni plating layer 23, hydrogen generated during the formation of the Ni plating layer 23 can be adsorbed onto the metal oxide particles 30. This suppresses hydrogen absorption into the substrate 10. As a result, the moisture resistance reliability of the multilayer ceramic capacitor 100 is improved. Furthermore, since the metal oxide particles 30 have higher chemical resistance than glass, they tend to remain without being etched even after the plating process is carried out.

[0058] Furthermore, since the metal oxide particles 30 are arranged on the surface of the substrate layer 21a, the restraint of the metal oxide particles 30 by the substrate layer 21a is suppressed, and the metal oxide particles 30 exhibit a buffering effect against stress. By increasing the amount of metal oxide particles 30 at the corners, top surface, bottom surface, and two sides of the base body 10 compared to the end face of the base body 10, delamination between the substrate layer 21a and the plating layer 22 becomes more likely at the corners, top surface, bottom surface, and two sides of the base body 10, thereby mitigating the stress applied to the base body 10 when the multilayer ceramic capacitor 100 is mounted on the substrate.

[0059] The metal oxide particles 30 are, for example, alumina particles, zirconia particles, etc., but are not particularly limited. When alumina particles are used as the metal oxide particles 30, for example, the average particle size of the metal oxide particles 30 is 0.1 μm or more and 8.0 μm or less, preferably 0.25 μm or more and 1.5 μm or less. As alumina particles, for example, a particle size range can be selected from those that are generally available on the market. When zirconia particles are used as the metal oxide particles 30, for example, the average particle size of the metal oxide particles 30 is 0.15 μm or more and 4.5 μm or less, preferably 0.20 μm or more and 4.0 μm or less.

[0060] The thickness of the underlayer 21a is, for example, 1 μm to 100 μm, 2.5 μm to 75 μm, and 5 μm to 50 μm. The thickness of the Ni plating layer 23 is, for example, 0.1 μm to 10 μm, 0.2 μm to 5 μm, and 0.5 μm to 2.5 μm. The thickness of the Sn plating layer 24 is, for example, 0.5 μm to 20 μm, 1 μm to 10 μm, and 0.5 μm to 5 μm.

[0061] Assuming the area of ​​the base layer 21a is 100%, the area ratio of the metal oxide particles 30 is between 0.01% and 20%, between 0.1% and 10%, and between 0.5% and 5%.

[0062] In the example shown in Figure 8(a), a Ni plating layer 23 is formed on the underlayer 21a, but the example is not limited to this. For example, as illustrated in Figure 9, another plating layer 26 may be formed on the underlayer 21a. In this case, the metal oxide particles 30 may be arranged on the surface of the underlayer 21a on the Ni plating layer 23 side, or on the surface of the plating layer 26 on the Ni plating layer 23 side. For example, the plating layer 26 may be mainly composed of Cu, and the metal oxide particles 30 may be an oxide of a metal different from the main component metal of the plating layer 26.

[0063] Next, the manufacturing method according to this embodiment will be described. Figure 10 is a diagram illustrating the flow of the manufacturing method according to this embodiment. The process from the raw material powder preparation process to the coating process, internal electrode formation process, and crimping process is the same as in the first embodiment.

[0064] (Coating process) The ceramic laminate obtained in this manner is subjected to a binder removal treatment in an N2 atmosphere, after which an external electrode paste, which will become the base layer 21a, is applied by a dipping method or the like. The external electrode paste contains powder of the main component metal of the base layer 21a and a co-material. For example, the external electrode paste is applied to the two end faces of the laminate where the internal electrode pattern 53 is exposed. The external electrode paste may also extend to the top surface, bottom surface, and two side surfaces of the laminate.

[0065] (Firing process) The ceramic laminate obtained in this way is subjected to an oxygen partial pressure of 10 -5 ~10 -8 The material is fired in an atm reducing atmosphere at 1100°C to 1300°C for 10 minutes to 2 hours. In this way, the base material 10 and the underlayer 21a can be fired simultaneously.

[0066] (Re-oxidation process) Subsequently, a re-oxidation treatment may be performed in an N2 gas atmosphere at 600°C to 1000°C.

[0067] (Oxide particle placement process) Next, the substrate 10 on which the base layer 21a is formed is heated in a non-oxidizing atmosphere, then exposed to an oxidizing atmosphere while maintaining this temperature, and then cooled back to a non-oxidizing atmosphere. For example, the substrate is heated to about 500°C in an N2 atmosphere, and then the atmosphere is changed to air while maintaining this temperature. After maintaining this state for about 2 minutes, it is cooled back to an N2 atmosphere. Through this oxidation treatment, the surface of the base layer 21a is rapidly oxidized at a high temperature. Next, the surface is acid-treated with a dilute sulfuric acid solution to remove the oxides from the surface. Since the oxides are formed not only on the surface of the base layer 21a but also in the thickness direction, mixed with metallic copper, the areas where copper oxide is removed from these mixed areas of metallic copper and copper oxide become voids 40 when viewed in cross-section. Metal oxide particles 30 are placed in these voids 40 by sprinkling them.

[0068] Alternatively, the metal oxide particles 30 may be arranged without forming voids 40. In this case, the oxidation and acid treatments may be omitted, and the metal oxide particles 30 may be arranged by sprinkling them onto the surface of the substrate layer 21a. (Plating process) Subsequently, a plating layer 22 is formed on the underlayer 21a by a plating process. In the configuration shown in Figure 8, a Ni plating layer 23 and a Sn plating layer 24 are formed sequentially by the plating process.

[0069] According to the manufacturing method of this embodiment, by arranging metal oxide particles 30 on the surface of the base layer 21a on the Ni plating layer 23 side, hydrogen generated during the formation of the Ni plating layer 23 can be adsorbed onto the metal oxide particles 30. This suppresses hydrogen absorption into the substrate 10. As a result, the moisture resistance reliability of the multilayer ceramic capacitor 100 is improved.

[0070] In the configuration shown in Figure 9, a plating layer 26 can be formed on the surface of the underlayer 21a by a plating treatment, and then the metal oxide particles 30 can be placed on the surface of the plating layer 26. Alternatively, voids 40 can be formed on the surface of the plating layer 26 by oxidation and acid treatment, and then the metal oxide particles 30 can be placed.

[0071] Although the above embodiments describe multilayer ceramic capacitors as an example of ceramic electronic components, they are not limited to this. For example, the configurations of the above embodiments can also be applied to other multilayer ceramic electronic components such as varistors and thermistors. [Examples]

[0072] Below, a multilayer ceramic capacitor according to the embodiment was fabricated and its characteristics were investigated.

[0073] (Example 1) An internal electrode pattern was formed by printing Ni internal electrode paste onto a dielectric green sheet. The resulting laminated units were stacked and compressed. After compression, the laminate was cut into a predetermined shape to obtain a ceramic laminate. Ni metal paste was formed by dipping into two end faces of the ceramic laminate where the internal electrode pattern was exposed, and then fired in a reducing atmosphere. A Ni underlayer was obtained by firing the Ni metal paste. Barium titanate was included as a co-material in the underlayer. The average particle size of the co-material after firing was 3 μm.

[0074] A Cu plating layer was formed on a Ni underlayer. The sample was then heated to 500°C in an N2 atmosphere and maintained at 500°C while the atmosphere was changed to air. After holding this state for 2 minutes, it was returned to an N2 atmosphere and cooled. This treatment rapidly oxidized the surface of the Cu plating layer at high temperature. Next, the surface of the Cu plating layer was treated with a dilute sulfuric acid solution to remove oxides. Then, alumina particles were sprinkled onto the surface of the Cu plating layer. Alumina particles with an average particle size of 1.1 μm were used. Subsequently, Ni plating was performed, followed by Sn plating.

[0075] (Example 2) In Example 2, the oxidation treatment and treatment with dilute sulfuric acid solution on the surface of the Cu plating layer were omitted. Other conditions were the same as in Example 1.

[0076] (Example 3) In Example 3, the oxidation treatment and treatment with dilute sulfuric acid solution on the surface of the Cu plating layer were omitted. Zirconia particles were also sprinkled onto the surface of the Cu plating layer. In this case, zirconia particles with an average particle size of 30 μm were used. Other conditions were the same as in Example 1.

[0077] (Comparative example) In the comparative example, alumina particles were not attached to the surface of the Cu plating layer. Other conditions were the same as in Example 1.

[0078] (analysis) For each of Examples 1-3 and the Comparative Example, an accelerated life test (HALT) was performed at a high temperature and high electric field of 150°C and 40V / μm. The test was continued until all 100 samples failed, and the average time to failure was defined as the lifespan (MTTF). The results are shown in Table 1. As shown in Table 1, in Examples 1-3, the MTTF was 400 min or more, indicating improved humidity resistance reliability. This is thought to be because hydrogen was adsorbed onto the oxide particles formed on the surface of the Cu plating layer, suppressing hydrogen absorption into the substrate. In contrast, in the Comparative Example, the MTTF was less than 300 min, indicating that sufficient humidity resistance reliability was not obtained. This is thought to be because the absence of oxide particles on the surface of the Cu plating layer prevented the suppression of hydrogen absorption into the substrate. [Table 1]

[0079] Although embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0080] 10 Base Body 11 Dielectric layer 12 Internal electrode layer 13. Cover layer 14 Capacity part 15 End margin 16 Side margins 20a,20b external electrode 21,21a Base layer 22 Plating layer 23 Ni plating layer 24 Sn plating layer 25 Plating layer 26 Plating layer 30 Metal oxide particles 40 void 51 Base material 52 Dielectric Green Sheet 53 Internal electrode pattern 100 Multilayer Ceramic Capacitors

Claims

1. A substrate having a plurality of dielectric layers, and a plurality of internal electrode layers stacked via the plurality of dielectric layers, with one end exposed facing each other, A base layer is provided on the end face of the substrate, which is the end in the direction in which the plurality of internal electrode layers are extended, and is in contact with each of the ends of the plurality of internal electrode layers. A Ni plating layer formed on the aforementioned underlayer, A Cu plating layer formed between the aforementioned underlayer and the aforementioned Ni plating layer, The Cu plating layer comprises metal oxide particles arranged on the surface of the Cu plating layer on the Ni plating layer side, The aforementioned metal oxide particles are oxides of metals other than Cu. A ceramic electronic component in which the average particle size of the metal oxide particles is 0.1 μm or more and 8.0 μm or less.

2. The ceramic electronic component according to claim 1, wherein the aforementioned underlayer is a sintered body of Ni.

3. The ceramic electronic component according to claim 1 or claim 2, wherein the metal oxide particles are alumina particles or zirconia particles.

4. A void is formed on the surface of the Cu plating layer on the Ni plating layer side, The ceramic electronic component according to any one of claims 1 to 3, wherein the metal oxide particles are arranged in the void.

5. A substrate having a plurality of dielectric layers and a plurality of internal electrode layers stacked on the plurality of dielectric layers and provided so that one end is exposed and facing each other, A base layer, which is a sintered Ni body, is provided on the end face of the substrate, which is the end in the direction in which the plurality of internal electrode layers are stretched, and is in contact with one end of each of the plurality of internal electrode layers. A Ni plating layer formed on the aforementioned underlayer, The metal oxide particles are disposed on the surface of the underlayer on the Ni plating layer side, or on the surface of the metal layer disposed between the underlayer and the Ni plating layer, When the metal oxide particles are placed on the surface of the underlying layer, they are oxides of metals other than Cu, and when they are placed on the surface of the metal layer, they are oxides of metals other than the main component metal of the metal layer. A ceramic electronic component in which the average particle size of the metal oxide particles is 0.1 μm or more and 8.0 μm or less.

6. A Cu plating layer is provided between the aforementioned underlayer and the Ni plating layer. The ceramic electronic component according to claim 5, wherein the metal oxide particles are arranged on the surface of the Cu plating layer on the Ni plating layer side.

7. The ceramic electronic component according to claim 5 or 6, wherein the metal oxide particles are alumina particles or zirconia particles.

8. A void is formed on the surface of the underlayer on the Ni plating layer side, or on the surface of the metal layer disposed between the underlayer and the Ni plating layer on the Ni plating layer side. The ceramic electronic component according to any one of claims 5 to 7, wherein the metal oxide particles are arranged in the void.

9. A step of preparing a substrate having a plurality of dielectric layers and a plurality of internal electrode layers stacked via the plurality of dielectric layers and arranged so that one end is exposed and facing each other; A step of baking a Cu-based underlayer at the end face of the substrate, which is the end in the direction in which the plurality of internal electrode layers are stretched, in contact with each of the ends of the plurality of internal electrode layers, The process of forming a Cu plating layer on the aforementioned underlayer, The process includes arranging metal oxide particles on the surface of the Cu plating layer, and then forming a Ni plating layer. The aforementioned metal oxide particles are oxides of metals other than Cu. A method for manufacturing ceramic electronic components, wherein the average particle size of the metal oxide particles is 0.1 μm or more and 8.0 μm or less.

10. A step of preparing a ceramic laminate having a plurality of dielectric green sheets and a plurality of internal electrode patterns laminated on the plurality of dielectric green sheets, with one end facing each other and exposed; A step of applying a conductive paste mainly composed of Ni to the end face of the ceramic laminate, which is the end in the direction in which the plurality of internal electrode patterns are stretched, and which is in contact with one end of each of the plurality of internal electrode patterns. The process involves simultaneously firing the ceramic laminate and the conductive paste to form a base layer from the conductive paste, The process includes the steps of arranging metal oxide particles on the surface of the underlayer or on the surface of a metal layer formed on the underlayer, and then forming a Ni plating layer. When the metal oxide particles are placed on the surface of the underlying layer, they are oxides of metals other than Cu, and when they are placed on the surface of the metal layer, they are oxides of metals other than the main component metal of the metal layer. A method for manufacturing ceramic electronic components, wherein the average particle size of the metal oxide particles is 0.1 μm or more and 8.0 μm or less.

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