JP2023143031A - Ceramic electronic component and manufacturing method thereof - Google Patents

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

The present invention relates to a ceramic electronic component and a method for manufacturing the same.

In recent years, ceramic electronic components such as multilayer ceramic capacitors have expanded their use to include automotive applications, and are required to have even higher reliability levels. Therefore, a multilayer ceramic capacitor with high moisture resistance and reliability has been disclosed (see, for example, Patent Document 1).

JP2020-72246A

However, in the plating process for forming the Ni plating layer on the base layer, hydrogen may diffuse into the interior of the element body of the ceramic electronic component, leading to a risk of deterioration in moisture resistance reliability.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a ceramic electronic component that can improve moisture resistance reliability and a method for manufacturing the same.

A ceramic electronic component according to the present invention includes a plurality of dielectric layers and a plurality of internal electrode layers stacked through the plurality of dielectric layers and provided facing each other with one end exposed. a base layer mainly composed of Cu, which is provided on an end surface of the element body that is an end in the direction in which the plurality of internal electrode layers are extended, and is 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 a surface of the base layer on the Ni plating layer side, or a metal layer disposed between the base layer and the Ni plating layer on the Ni plating layer side. metal oxide particles disposed on the surface, the metal oxide particles being an oxide of a metal other than Cu when disposed on the surface of the underlayer, and disposed on the surface of the metal layer; In some cases, it is an oxide of a metal other than the main component metal of the metal layer.

In the above ceramic electronic component, the metal oxide particles may be alumina particles or zirconia particles.

Another ceramic electronic component according to the present invention includes a plurality of dielectric layers and a plurality of internal electrode layers that are laminated through the plurality of dielectric layers and are provided so as to face each other and have one end exposed. an underlayer containing Cu as a main component, provided on an end face of the element body that is an end in the direction in which the plurality of internal electrode layers are extended, and in contact with each of the one ends of the plurality of internal electrode layers; and a Ni plating layer formed on the base layer, and the Ni plating layer of a metal layer disposed on the surface of the base layer on the Ni plating layer side or between the base layer and the Ni plating layer. metal oxide particles disposed on the side surface, said metal oxide particles being alumina particles or zirconia particles.

In the ceramic electronic component, the metal oxide particles may have an average particle size of 0.1 μm or more and 8.0 μm or less.

In the above ceramic electronic component, the metal oxide particles may be arranged on a surface of the base layer on the Ni plating layer side.

Another ceramic electronic component according to the present invention includes a plurality of dielectric layers and a plurality of internal electrode layers that are laminated through the plurality of dielectric layers and are provided so as to face each other and have one end exposed. a base layer provided on an end surface of the base body that is an end in a direction in which the plurality of internal electrode layers are extended, and in contact with each of the ends of the plurality of internal electrode layers; The formed Ni plating layer and the surface of the base layer on the Ni plating layer side, or the surface of the metal layer disposed between the base 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 placed on the surface of the underlayer, and the metal oxide particles are an oxide of a metal other than Cu when placed on the surface of the metal layer. The metal oxide particles are oxides of metals other than the main component metal of the layer, and the average particle size of the metal oxide particles is 0.1 μm or more and 8.0 μm or less.

In the above ceramic electronic component, a Cu plating layer may be provided between the base layer and the Ni plating layer, and the metal oxide particles may be arranged on a surface of the Cu plating layer on the Ni plating layer side. .

In the above ceramic electronic component, the base layer may be a sintered body of Ni.

In the above ceramic electronic component, the metal oxide particles may be alumina particles or zirconia particles.

In the above ceramic electronic component, a void is formed on the surface of the base layer on the Ni plating layer side, or on the surface of the metal layer disposed between the base layer and the Ni plating layer on the Ni plating layer side. The metal oxide particles may be arranged in the voids.

A method for manufacturing a ceramic electronic component according to the present invention includes a plurality of dielectric layers, a plurality of internal electrode layers stacked through the plurality of dielectric layers, and provided facing each other so that one end thereof is exposed. a step of preparing an element body having Cu as a main component, the end face of the element body being the end in the direction in which the plurality of internal electrode layers are in contact with the one end of the plurality of internal electrode layers; a step of baking a base layer, and a step of arranging metal oxide particles on the surface of the base layer or the surface of a metal layer formed on the base layer, and then forming a Ni plating layer. , when the metal oxide particles are placed on the surface of the base layer, they are oxides of metals other than Cu, and when placed on the surface of the metal layer, they are oxides of metals other than the main component metal of the metal layer. It is an oxide of metal.

Another method of manufacturing a ceramic electronic component according to the present invention includes a plurality of dielectric green sheets, and a plurality of internal parts that are laminated through the plurality of dielectric green sheets and are provided so as to face each other and have one end exposed. an electrode pattern provided on an end surface of the ceramic laminate that is an end in the direction in which the plurality of internal electrode patterns are extended, and which is provided at the end face of the ceramic laminate that has the one end of the plurality of internal electrode patterns; a step of applying a conductive paste containing Cu as a main component that is in contact with each other; a step of forming a base layer from the conductive paste by simultaneously firing the ceramic laminate and the conductive paste; and a surface of the base layer. Alternatively, the method includes a step of disposing metal oxide particles on the surface of the metal layer formed on the base layer, and then forming a Ni plating layer, wherein the metal oxide particles are on the surface of the base layer. When placed on the surface of the metal layer, it is an oxide of a metal other than Cu, and when placed on the surface of the metal layer, it is an oxide of a metal other than the main component metal of the metal layer, and the metal oxide particles The average particle size of is 0.1 μm or more and 8.0 μm or less.

According to the present invention, it is possible to provide a ceramic electronic component that can improve moisture resistance reliability and a method for manufacturing the same.

FIG. 2 is a partial cross-sectional perspective view of a multilayer ceramic capacitor. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. 2 is a sectional view taken along line BB in FIG. 1. FIG. (a) and (b) are enlarged cross-sectional views of the vicinity of external electrodes. FIG. 3 is an enlarged cross-sectional view of the vicinity of an external electrode. FIG. 3 is a diagram illustrating a flow of a method for manufacturing a multilayer ceramic capacitor. (a) and (b) are diagrams illustrating a lamination process. (a) and (b) are enlarged cross-sectional views of the vicinity of external electrodes. FIG. 3 is an enlarged cross-sectional view of the vicinity of an external electrode. FIG. 3 is a diagram illustrating a flow of a method for manufacturing a multilayer ceramic capacitor.

Each embodiment will be described below with reference to the drawings.

(First embodiment)
First, an overview of a multilayer ceramic capacitor, which is an example of a ceramic electronic component, will be explained. FIG. 1 is a partially 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 an element body 10 having a rectangular parallelepiped shape, and external electrodes 20a and 20b provided on either two opposing end surfaces of the element body 10. The two end surfaces are end surfaces in the direction in which the internal electrode layer 12 is stretched. Note that, of the four surfaces of the element body 10 other than the two end surfaces, two surfaces other than the upper surface and the lower surface in the stacking direction are referred to as side surfaces. The external electrodes 20a and 20b extend on the top surface, bottom surface, and two side surfaces of the element body 10 in the stacking direction. However, the external electrodes 20a and 20b are spaced apart from each other.

The element body 10 has a structure in which dielectric layers 11 containing a ceramic material functioning as a dielectric and internal electrode layers 12 containing a base metal material are alternately laminated. One end of each internal electrode layer 12 is exposed alternately to an end surface of the element body 10 where the external electrode 20a is provided and an end surface where the external electrode 20b is provided. Thereby, each internal electrode layer 12 is alternately electrically connected to the external electrodes 20a and 20b. As a result, multilayer ceramic capacitor 100 has a structure in which a plurality of dielectric layers 11 are stacked with internal electrode layers 12 in between. Further, in the laminate of the dielectric layer 11 and the internal electrode layer 12, the internal electrode layer 12 is disposed as the outermost layer in the stacking direction, and the top and bottom surfaces of the laminate are covered with a cover layer 13. The cover layer 13 has a ceramic material as its main component. For example, the material of the cover layer 13 is the same as that of the dielectric layer 11 in the main component of ceramic material.

The size of the multilayer ceramic capacitor 100 is, for example, 0.25 mm long, 0.125 mm wide, and 0.125 mm high, or 0.4 mm long, 0.2 mm wide, 0.2 mm high, or long. 0.6mm, width 0.3mm, height 0.3mm, or length 1.0mm, width 0.5mm, height 0.5mm, or length 1.6mm, width 0.8mm, height The length is 0.8 mm, or the length is 3.2 mm, the width is 1.6 mm, and the height is 1.6 mm, or the length is 4.5 mm, the width is 3.2 mm, and the height is 2.5 mm. It is not limited to size.

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

The dielectric layer 11 has, for example, a ceramic material having a perovskite structure represented by the general formula _ABO3 as a main phase. Note that the perovskite structure includes ABO _3-α that deviates from the stoichiometric composition. For example, the ceramic materials include BaTiO ₃ (barium titanate), CaZrO ₃ (calcium zirconate), CaTiO ₃ (calcium titanate), SrTiO ₃ (strontium titanate), MgTiO ₃ (magnesium titanate), and perovskite structures. Select and use at least one of Ba _1-x-y Ca _x Sry _{Ti 1-z} Zr _z O ₃ (0≦x≦1, 0≦y≦1, 0≦z≦1) to form. be able to. Ba _1-x-y Ca _{x Sry} Ti _1-z Zr _z O ₃ is barium strontium titanate, barium calcium titanate, barium zirconate, barium zirconate titanate, calcium zirconate titanate, and zirconate titanate. Barium calcium, etc.

An additive may be added to the dielectric layer 11. As additives to the dielectric layer 11, magnesium (Mg), manganese (Mn), molybdenum (Mo), vanadium (V), chromium (Cr), rare earth elements (yttrium (Y), samarium (Sm), europium ( Cobalt (Co), nickel (Ni), lithium (Li), boron (B), sodium (Na), potassium (K) or silicon (Si), or containing cobalt, nickel, lithium, boron, sodium, potassium or silicon Glass is an example.

As illustrated in FIG. 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 a region where capacitance occurs in the multilayer ceramic capacitor 100. be. Therefore, the region where the capacitance occurs is referred to as a capacitor section 14. That is, the capacitive portion 14 is a region where adjacent internal electrode layers 12 connected to different external electrodes face each other.

The region where the internal electrode layers 12 connected to the external electrode 20a face each other without interposing the internal electrode layer 12 connected to the external electrode 20b is referred to as an end margin 15. Further, the end margin 15 is also a region where the internal electrode layers 12 connected to the external electrode 20b face each other without interposing the internal electrode layer 12 connected to the external electrode 20a. That is, the end margin 15 is a region where internal electrode layers 12 connected to the same external electrode face each other without interposing the internal electrode layers 12 connected to a different external electrode. The end margin 15 is an area where no capacitance occurs. The end margin 15 may have the same composition as the dielectric layer 11 of the capacitive section 14, or may have a different composition.

As illustrated in FIG. 3, in the element body 10, a region from two side surfaces of the element body 10 to the internal electrode layer 12 is referred to as a side margin 16. That is, the side margin 16 is a region provided so as to cover the ends of the plurality of stacked internal electrode layers 12 extending toward the two side surfaces in the stacked structure. The side margin 16 is also an area where no electrostatic capacitance occurs. The side margin 16 may have the same composition as the dielectric layer 11 of the capacitive portion 14, or may have a different composition.

FIG. 4A is an enlarged cross-sectional view of the vicinity of the external electrode 20a. In FIG. 4(a), hatches are omitted. As illustrated in FIG. 4A, 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 contains metals such as Cu, Ni, Al, Zn, and Sn, or alloys of two or more of these metals. The plating layer 22 may be a plating layer of a single metal component, or may be a plurality of plating layers of mutually different metal components. The plating layer 22 includes at least a Ni plating layer, and a metal layer containing a metal other than Ni as a main component 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. Note that although FIG. 4A illustrates the external electrode 20a, the external electrode 20b also has a similar laminated structure.

The base layer 21 is a sintered body containing Cu as a main component, and is later attached to the fired element body 10 by baking. The base layer 21 contains a glass component to lower the baking temperature. The glass component is, for example, an oxide of Ba, Ca, Zn, Al, Si, Mg, or B. Metal oxide particles 30 are dispersed and arranged on the surface of the base layer 21 on the Ni plating layer 23 side. The metal oxide particles 30 are an oxide 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, but as illustrated in FIG. It may be arranged within a gap 40 formed by unevenness formed on the side surface. At this time, the metal oxide particles 30 may be arranged so as to fill the void 40, or may be arranged in a part of the void 40.

By disposing the metal oxide particles 30 on the surface of the base layer 21 on the Ni plating layer 23 side, the metal oxide particles 30 can adsorb hydrogen generated when forming the Ni plating layer 23. Thereby, hydrogen storage in the element body 10 can be suppressed. As a result, the moisture resistance reliability of the multilayer ceramic capacitor 100 is improved. Note that 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 performed.

Moreover, since the metal oxide particles 30 are arranged on the surface of the base layer 21, the restraint of the metal oxide particles 30 by the base layer 21 is suppressed, and the metal oxide particles 30 exert a buffering effect against stress. By increasing the amount of metal oxide particles 30 at the corners, upper surface, lower surface, and 2 side surfaces of the element body 10 than at the end surfaces of the element body 10, the base layer is formed at the corners, upper surface, lower surface, and 2 side surfaces of the element body 10. Peeling easily occurs between the plating layer 21 and the plating layer 22, and the stress applied to the element body 10 when the multilayer ceramic capacitor 100 is mounted on a substrate can be alleviated.

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 using alumina particles 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 the alumina particles, a particle size range can be selected from those commonly available on the market. When using zirconia particles 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. .

In addition, in the multilayer ceramic capacitor 100, the average particle diameter of the metal oxide particles 30 is determined by measuring the directional diameter (Ferret diameter) of 30 oxide particles using a cross-sectional SEM photograph magnified 5,000 to 20,000 times, and calculating the average value. It can be measured by taking

The thickness of the base layer 21 is, for example, 1 μm or more and 100 μm or less, 2.5 μm or more and 75 μm or less, and 5 μm or more and 50 μm or less. The thickness of the Ni plating layer 23 is, for example, 0.1 μm or more and 10 μm or less, 0.2 μm or more and 5 μm or less, and 0.5 μm or more and 2.5 μm or less. The thickness of the Sn plating layer 24 is, for example, 0.5 μm or more and 20 μm or less, 1 μm or more and 10 μm or less, and 0.5 μm or more and 5 μm or less.

When the area of the base layer 21 is assumed to be 100%, the area ratio of the metal oxide particles 30 is 0.01% or more and 20% or less, 0.1% or more and 10% or less, and 0.5%. 5% or less. 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 of FIG. 4A using image processing software. Note that when confirming the area ratio for each end face or side face of the base layer 21, the area ratio can be calculated using the entire area of each end face or side face as the denominator.

In the example of FIG. 4A, the Ni plating layer 23 is formed on the base layer 21, but the present invention is not limited thereto. For example, as illustrated in FIG. 5, another plating layer 25 may be formed on the base layer 21. In this case, the metal oxide particles 30 may be arranged on the surface of the base layer 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 have Cu as its main component, and the metal oxide particles 30 may be an oxide of a metal different from the main component metal of the plating layer 25. Further, for example, a conductive resin layer may be present on the base layer 21 instead of a plating layer.

Next, a method for manufacturing the multilayer ceramic capacitor 100 will be described. FIG. 6 is a diagram illustrating a flow of a method for manufacturing the multilayer ceramic capacitor 100.

(Raw material powder production process)
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 are conventionally known for synthesizing the main component ceramic of the dielectric layer 11, such as a solid phase method, a sol-gel method, a hydrothermal method, and the like. In this embodiment, any of these can be adopted.

A predetermined additive compound is added to the obtained ceramic powder depending on the purpose. Additive compounds include magnesium (Mg), manganese (Mn), molybdenum (Mo), vanadium (V), chromium (Cr), rare earth elements (yttrium (Y), samarium (Sm), europium (Eu), gadolinium ( 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. Among these, SiO ₂ mainly functions as a sintering aid.

For example, a ceramic material is prepared by wet-mixing a compound containing an additive compound with a ceramic raw material powder, drying and pulverizing the mixture. For example, the ceramic material obtained as described above may be pulverized to adjust the particle size, if necessary, or may be combined with a classification process to adjust the particle size. Through the above steps, a raw material powder is obtained.

(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 obtained slurry, a dielectric green sheet 52 is coated on the base material 51 by, for example, a die coater method or a doctor blade method, and then dried. The base material 51 is, for example, a PET (polyethylene terephthalate) film.

(Internal electrode formation process)
Next, as illustrated in FIG. 7A, an internal electrode pattern 53 is formed on the dielectric green sheet 52. In FIG. 7A, as an example, four layers of internal electrode patterns 53 are formed on a dielectric green sheet 52 at predetermined intervals. The dielectric green sheet 52 on which the internal electrode pattern 53 is formed is a laminated unit.

For the internal electrode pattern 53, a metal paste of the main component metal of the internal electrode layer 12 is used. The film forming method may be printing, sputtering, vapor deposition, or the like.

(crimping process)
Next, while peeling the dielectric green sheet 52 from the base material 51, the laminated units are laminated as illustrated in FIG. 7(b). Thereafter, a predetermined number (for example, 2 to 10 layers) of cover sheets 54 are laminated on the upper and lower sides of the laminate obtained by laminating the laminate units, and the cover sheets 54 are bonded by thermocompression, and then cut into a predetermined chip size. In the example of FIG. 7(b), the cut is made along the dotted line. The cover sheet 54 may have the same components as the dielectric green sheet 52, or may have different additives.

(Firing process)
The ceramic laminate thus obtained was subjected to binder removal treatment in an N ₂ atmosphere, and then fired for 10 minutes to 2 hours at 1100°C to 1300°C in a reducing atmosphere with an oxygen partial pressure of 10 ^-5 to 10 ^-8 atm. do. In this way, the element body 10 can be fired.

(Re-oxidation treatment process)
Thereafter, reoxidation treatment may be performed at 600° C. to 1000° C. in an N ₂ gas atmosphere.

(Baking process)
Next, a metal paste that will become the base layer 21 is applied to both end faces of the element body 10 by a dipping method or the like. The metal paste contains glass. For example, the metal paste is applied to the element body 10 so as to extend to at least one of four sides other than the two end faces where the internal electrode layer 12 is exposed. Thereafter, the base layer 21 is formed by baking the metal paste at, for example, about 700° C. to 900° C.

(Oxide particle placement process)
Next, the element body 10 on which the base layer 21 has been formed is heated in a non-oxidizing atmosphere, exposed to an oxidizing atmosphere while maintaining this temperature, and then returned to the non-oxidizing atmosphere and cooled. For example, after raising the temperature to about 500° C. in an N ₂ atmosphere, the atmosphere is changed to air while maintaining this temperature. After maintaining this state for about 2 minutes, it is returned to the N ₂ atmosphere and cooled. Through such oxidation treatment, the surface of the base layer 21 is rapidly oxidized at high temperature. Next, the surface is acid-treated with a dilute sulfuric acid solution to remove oxides on the surface. Since the oxide is formed not only on the surface of the base layer 21 but also in the thickness direction in a mixed manner with metallic copper, the copper oxide is removed from such areas where metallic copper and copper oxide are mixed. The region becomes a void 40 when viewed from a cross section. The metal oxide particles 30 are placed in the void 40 by sprinkling them thereon.

Note that the metal oxide particles 30 may be arranged without forming the voids 40. In this case, the oxidation treatment and acid treatment may be omitted, and the metal oxide particles 30 may be sprinkled on the surface of the base layer 21 to be arranged.
(Plating process)
Thereafter, a plating layer 22 is formed on the base layer 21 by a plating process. In the case of the configuration shown in FIG. 4(a), a Ni plating layer 23 and a Sn plating layer 24 are sequentially formed by plating.

According to the manufacturing method according to the present embodiment, by disposing the metal oxide particles 30 on the surface of the base layer 21 on the Ni plating layer 23 side, hydrogen generated when forming the Ni plating layer 23 is removed by metal oxidation. It can be adsorbed onto the particles 30. Thereby, hydrogen storage in the element body 10 can be suppressed. As a result, the moisture resistance reliability of the multilayer ceramic capacitor 100 is improved.

In the case of the configuration shown in FIG. 5, the metal oxide particles 30 may be arranged on the surface of the plating layer 25 after forming the plating layer 25 on the surface of the base layer 21 by plating. In this case, the metal oxide particles 30 may be arranged after forming the voids 40 on the surface of the plating layer 25 by oxidation treatment and acid treatment.

(Second embodiment)
Next, a second embodiment will be described. Points different from the first embodiment will be explained. FIG. 8(a) is an enlarged cross-sectional view of the vicinity of the external electrode 20a. In FIG. 8(a), hatches are omitted. As illustrated in FIG. 8A, 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 contains metals such as Cu, Ni, Al, Zn, and Sn, or alloys of two or more of these metals. The plating layer 22 may be a plating layer of a single metal component, or may be a plurality of plating layers of mutually different metal components. The plating layer 22 includes at least a Ni plating layer, and a metal layer containing a metal other than Ni as a main component 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 FIG. 8A shows an example of the external electrode 20a, the external electrode 20b also has a similar laminated structure.

The base layer 21a is a sintered body mainly composed of Ni or the like, and is fired at the same time as the element body 10 is fired. The base layer 21a may contain ceramic particles as a co-material in order to reduce the difference in sintering behavior from the base body 10. The common material has, for example, the same composition as the main component ceramic of the dielectric layer 11. The average particle diameter of the co-material is, for example, 0.5 μm or more and 8 μm or less. Metal oxide particles 30 are dispersed and arranged on the surface of the base layer 21a on the Ni plating layer 23 side. The metal oxide particles 30 are an oxide 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, but as illustrated in FIG. It may be arranged within a gap 40 formed by unevenness formed on the side surface.

The metal oxide particles 30 have a composition different from that of the common material. Further, the metal oxide particles 30 have an average particle size of 0.1 μm or more and 8.0 μm or less. Therefore, the metal oxide particles 30 are distinguished from the common material. Note that the average particle size of the co-material can be measured by the same method as the average particle size of the metal oxide particles 30.

By arranging the metal oxide particles 30 on the surface of the base layer 21a on the Ni plating layer 23 side, hydrogen generated when forming the Ni plating layer 23 can be adsorbed onto the metal oxide particles 30. Thereby, hydrogen storage in the element body 10 can be suppressed. As a result, the moisture resistance reliability of the multilayer ceramic capacitor 100 is improved. Note that 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 performed.

Moreover, since the metal oxide particles 30 are arranged on the surface of the base layer 21a, the restraint of the metal oxide particles 30 by the base layer 21a is suppressed, and the metal oxide particles 30 exert a buffering effect against stress. By increasing the amount of metal oxide particles 30 at the corners, upper surface, lower surface, and 2 side surfaces of the element body 10 than at the end surfaces of the element body 10, the base layer is formed at the corners, upper surface, lower surface, and 2 side surfaces of the element body 10. Peeling easily occurs between the plating layer 21a and the plating layer 22, and the stress applied to the element body 10 when the multilayer ceramic capacitor 100 is mounted on a substrate can be alleviated.

The metal oxide particles 30 are, for example, alumina particles, zirconia particles, etc., but are not particularly limited. When using alumina particles 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 the alumina particles, for example, a particle size range can be selected from those commonly available on the market. When using zirconia particles 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. .

The thickness of the base layer 21a is, for example, 1 μm or more and 100 μm or less, 2.5 μm or more and 75 μm or less, and 5 μm or more and 50 μm or less. The thickness of the Ni plating layer 23 is, for example, 0.1 μm or more and 10 μm or less, 0.2 μm or more and 5 μm or less, and 0.5 μm or more and 2.5 μm or less. The thickness of the Sn plating layer 24 is, for example, 0.5 μm or more and 20 μm or less, 1 μm or more and 10 μm or less, and 0.5 μm or more and 5 μm or less.

When the area of the base layer 21a is assumed to be 100%, the area ratio of the metal oxide particles 30 is 0.01% or more and 20% or less, 0.1% or more and 10% or less, and 0.5%. 5% or less.

In the example of FIG. 8A, the Ni plating layer 23 is formed on the base layer 21a, but the present invention is not limited thereto. For example, as illustrated in FIG. 9, another plating layer 26 may be formed on the base layer 21a. In this case, the metal oxide particles 30 may be arranged on the surface of the base layer 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 have Cu as its main component, and the metal oxide particles 30 may be an oxide of a metal different from the main component metal of the plating layer 26.

Next, a manufacturing method according to this embodiment will be explained. FIG. 10 is a diagram illustrating the flow of the manufacturing method according to this embodiment. The raw material powder production process, coating process, internal electrode formation process, and compression bonding process are the same as in the first embodiment.

(Coating process)
After the thus obtained ceramic laminate is subjected to a binder removal treatment in an N ₂ atmosphere, 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 common material. For example, the external electrode paste is applied to two end surfaces of the laminate where the internal electrode patterns 53 are exposed. The external electrode paste may extend to the top surface, bottom surface, and two side surfaces of the laminate.

(Firing process)
The ceramic laminate thus obtained is fired at 1100° C. to 1300° C. for 10 minutes to 2 hours in a reducing atmosphere with an oxygen partial pressure of 10 ⁻⁵ to 10 ⁻⁸ atm. In this way, the element body 10 and the base layer 21a can be fired simultaneously.

(Re-oxidation treatment process)
Thereafter, reoxidation treatment may be performed at 600° C. to 1000° C. in an N ₂ gas atmosphere.

(Oxide particle placement process)
Next, the element body 10 on which the base layer 21a has been formed is heated in a non-oxidizing atmosphere, exposed to an oxidizing atmosphere while maintaining this temperature, and then returned to the non-oxidizing atmosphere and cooled. For example, after raising the temperature to about 500° C. in an N ₂ atmosphere, the atmosphere is changed to air while maintaining this temperature. After maintaining this state for about 2 minutes, it is returned to the N ₂ atmosphere and cooled. Through such oxidation treatment, the surface of the base layer 21a is rapidly oxidized at high temperature. Next, the surface is acid-treated with a dilute sulfuric acid solution to remove oxides on the surface. Since the oxide is formed not only on the surface of the base layer 21a but also in the thickness direction in a mixed manner with metallic copper, the copper oxide is removed from such a portion where metallic copper and copper oxide are mixed. The region becomes a void 40 when viewed from a cross section. The metal oxide particles 30 are placed in the void 40 by sprinkling them thereon.

Note that the metal oxide particles 30 may be arranged without forming the voids 40. In this case, the oxidation treatment and acid treatment may be omitted and the metal oxide particles 30 may be sprinkled on the surface of the base layer 21a.
(Plating process)
Thereafter, a plating layer 22 is formed on the base layer 21a by plating. In the case of the configuration shown in FIG. 8, a Ni plating layer 23 and a Sn plating layer 24 are sequentially formed by plating.

According to the manufacturing method according to the present embodiment, by disposing the metal oxide particles 30 on the surface of the base layer 21a on the Ni plating layer 23 side, hydrogen generated when forming the Ni plating layer 23 is removed by metal oxidation. It can be adsorbed onto the particles 30. Thereby, hydrogen storage in the element body 10 can be suppressed. As a result, the moisture resistance reliability of the multilayer ceramic capacitor 100 is improved.

In the case of the configuration shown in FIG. 9, the metal oxide particles 30 may be arranged on the surface of the plating layer 26 after forming the plating layer 26 on the surface of the base layer 21a by plating. In this case, the metal oxide particles 30 may be arranged after forming the voids 40 on the surface of the plating layer 26 by oxidation treatment and acid treatment.

Note that in each of the above embodiments, a multilayer ceramic capacitor has been described as an example of a ceramic electronic component, but the present invention is not limited thereto. For example, the configurations of the above embodiments can also be applied to other multilayer ceramic electronic components such as varistors and thermistors.

Hereinafter, a multilayer ceramic capacitor according to an embodiment was manufactured and its characteristics were investigated.

(Example 1)
An internal electrode pattern was formed by printing Ni internal electrode paste on the dielectric green sheet. The obtained laminated units were laminated and pressure bonded. After crimping, the ceramic laminate was cut into a predetermined shape to obtain a ceramic laminate. A Ni metal paste was formed by dipping on two end faces of the ceramic laminate where the internal electrode patterns were exposed, and then fired in a reducing atmosphere. A Ni underlayer was obtained by firing the Ni metal paste. Note that the base layer contained barium titanate as a co-material. The average particle size of the common material after firing was 3 μm.

A Cu plating layer was formed on the Ni underlayer. Thereafter, the temperature of the sample was raised to 500° C. under a N ₂ atmosphere, and the atmosphere was changed to air while maintaining the temperature at 500° C. After maintaining this state for 2 minutes, it was returned to the _N2 atmosphere and cooled. Due to this treatment, the surface side of the Cu plating layer was rapidly oxidized at high temperature. Next, the surface of the Cu plating layer was treated with a dilute sulfuric acid solution to remove oxides. Thereafter, alumina particles were sprinkled and adhered to the surface of the Cu plating layer. The alumina particles used in this case had an average particle size of 1.1 μm. After that, Ni plating was performed, and then Sn plating was performed.

(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.

(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. Further, zirconia particles were sprinkled and adhered to the surface of the Cu plating layer. The zirconia particles used in this case had an average particle size of 30 μm. Other conditions were the same as in Example 1.

(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.

(analysis)
For each of Examples 1 to 3 and Comparative Example, an accelerated life test (HALT) at a high temperature and high electric field of 40 V/μm at 150° C. was conducted. 100 samples were tested until all of them failed, and the average time was taken as the service life value (MTTF). The results are shown in Table 1. As shown in Table 1, in Examples 1 to 3, the MTTF was 400 min or more, indicating that the moisture resistance reliability was improved. This is thought to be because hydrogen was adsorbed to the oxide particles formed on the surface of the Cu plating layer, suppressing hydrogen absorption into the element body. On the other hand, in the comparative example, the MTTF was less than 300 min, indicating that sufficient moisture resistance reliability could not be obtained. This is considered to be because no oxide particles were formed on the surface of the Cu plating layer, so hydrogen storage in the element body could not be suppressed.

Although the 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 variations can be made within the scope of the gist of the present invention as described in the claims. Changes are possible.

10 Element body 11 Dielectric layer 12 Internal electrode layer 13 Cover layer 14 Capacitive part 15 End margin 16 Side margin 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 voids 51 base material 52 dielectric green sheet 53 internal electrode pattern 100 multilayer ceramic capacitor

Claims (12)

an element body having a plurality of dielectric layers and a plurality of internal electrode layers stacked through the plurality of dielectric layers and provided facing each other with one end exposed;
a base layer containing Cu as a main component, provided on an end surface of the element body that is an end in a 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;
comprising metal oxide particles arranged on the surface of the base layer on the Ni plating layer side, or on the surface of the metal layer disposed between the base layer and the Ni plating layer on the Ni plating layer side,
The metal oxide particles are oxides of metals other than Cu when placed on the surface of the base layer, and are oxides of metals other than Cu when placed on the surface of the metal layer. Ceramic electronic components are metal oxides. The ceramic electronic component according to claim 1, wherein the metal oxide particles are alumina particles or zirconia particles. an element body having a plurality of dielectric layers and a plurality of internal electrode layers stacked through the plurality of dielectric layers and provided facing each other with one end exposed;
a base layer containing Cu as a main component, provided on an end surface of the element body that is an end in a 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;
comprising metal oxide particles arranged on the surface of the base layer on the Ni plating layer side, or on the surface of the metal layer disposed between the base layer and the Ni plating layer on the Ni plating layer side,
A ceramic electronic component, wherein the metal oxide particles are alumina particles or zirconia particles. The ceramic electronic component according to any one of claims 1 to 3, wherein the metal oxide particles have an average particle size of 0.1 μm or more and 8.0 μm or less. The ceramic electronic component according to any one of claims 1 to 4, wherein the metal oxide particles are arranged on a surface of the base layer on the Ni plating layer side. an element body having a plurality of dielectric layers and a plurality of internal electrode layers stacked through the plurality of dielectric layers and provided facing each other with one end exposed;
a base layer provided on an end surface of the element body that is an end in a direction in which the plurality of internal electrode layers are extended, 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;
comprising metal oxide particles arranged on the surface of the base layer on the Ni plating layer side, or on the surface of the metal layer disposed between the base layer and the Ni plating layer on the Ni plating layer side,
The metal oxide particles are oxides of metals other than Cu when placed on the surface of the base layer, and are oxides of metals other than Cu when placed on the surface of the metal layer. It is a metal oxide,
A ceramic electronic component, wherein the metal oxide particles have an average particle size of 0.1 μm or more and 8.0 μm or less. A Cu plating layer is provided between the base layer and the Ni plating layer,
The ceramic electronic component according to claim 6, wherein the metal oxide particles are arranged on a surface of the Cu plating layer on the Ni plating layer side. The ceramic electronic component according to claim 6 or 7, wherein the base layer is a sintered body of Ni. The ceramic electronic component according to any one of claims 6 to 8, wherein the metal oxide particles are alumina particles or zirconia particles. A void is formed on the surface of the base layer on the Ni plating layer side, or on the surface of the metal layer disposed between the base layer and the Ni plating layer on the Ni plating layer side,
The ceramic electronic component according to any one of claims 1 to 9, wherein the metal oxide particles are arranged in the voids. preparing an element body having a plurality of dielectric layers and a plurality of internal electrode layers stacked through the plurality of dielectric layers and provided facing each other with one end exposed;
a step of baking a base layer containing Cu as a main component and in contact with each of the ends of the plurality of internal electrode layers on an end surface of the element body that is an end in a direction in which the plurality of internal electrode layers are stretched;
arranging metal oxide particles on the surface of the base layer or the surface of the metal layer formed on the base layer, and then forming a Ni plating layer,
The metal oxide particles are oxides of metals other than Cu when placed on the surface of the base layer, and are oxides of metals other than Cu when placed on the surface of the metal layer. A method for manufacturing ceramic electronic components made of metal oxides. A step of preparing a ceramic laminate having a plurality of dielectric green sheets and a plurality of internal electrode patterns stacked through the plurality of dielectric green sheets and provided facing each other so that one end thereof is exposed. ,
A step of applying a conductive paste containing Cu as a main component, which is provided on an end surface of the ceramic laminate that is an end in a direction in which the plurality of internal electrode patterns are extended, and is in contact with each of the one ends of the plurality of internal electrode patterns. and,
forming a base layer from the conductive paste by simultaneously firing the ceramic laminate and the conductive paste;
arranging metal oxide particles on the surface of the base layer or the surface of the metal layer formed on the base layer, and then forming a Ni plating layer,
The metal oxide particles are oxides of metals other than Cu when placed on the surface of the base layer, and are oxides of metals other than Cu when placed on the surface of the metal layer. It is a metal oxide,
The method for manufacturing a ceramic electronic component, wherein the metal oxide particles have an average particle size of 0.1 μm or more and 8.0 μm or less.

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