JP5077393B2 - Ceramic electronic component and manufacturing method thereof - Google Patents

Description

  The present invention relates to a ceramic electronic component and a manufacturing method thereof.

  Ceramic electronic components are widely used as small-sized, high-performance, and high-reliability electronic components, and the number of ceramic electronic components used in electrical and electronic devices is large. In recent years, along with the downsizing and high performance of such devices, the demand for further downsizing, high performance, and high reliability of ceramic electronic components has become increasingly severe.

  In addition, since such devices are used in various environments, ceramic electronic components are required to have, for example, good mechanical strength and moisture resistance. Furthermore, in the manufacturing process of the ceramic electronic component, it is necessary to increase the production efficiency and improve the yield.

Patent Document 1 discloses a multilayer ceramic electronic component having a ceramic laminate including a protective layer that constitutes part of the outer surface of the ceramic laminate and a main body portion other than the protective layer. The mole ratio (A / B ratio) between A and B in the compound represented by the general formula ABO ₃ contained in this laminate is higher in the protective layer than in the main body, thereby preventing cracks. It is described that it is planned.

  However, in Patent Document 1, since the A / B ratio in the protective layer is set higher than the A / B ratio in the main body, the sinterability of the protective layer is lower than the sinterability of the main body. As a result, when the sinterability of the protective layer is good, there is a problem that the main body is excessively fired and cracks are likely to occur. In addition, when the sinterability of the main body is good, the protective layer is not sufficiently sintered, so that there is a problem that the moisture resistance deteriorates.

  Moreover, in patent document 1, it is necessary to prepare separately the paste for forming the main-body part of a ceramic laminated body, and the paste for forming a protective layer, and a manufacturing process becomes complicated and production efficiency becomes efficient. There was a problem of lowering.

JP 2010-50263 A

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a ceramic electronic component in which the strength of the surface of the element body is increased to improve moisture resistance and structural defects are suppressed, and a method for manufacturing the same. .

In order to achieve the above object, a ceramic electronic component according to the present invention comprises:
A ceramic electronic component having an element body with a dielectric layer,
The dielectric layer has the general formula ABO ₃ (A is Ba alone or at least one selected from Ba and Ca and Sr, and B is Ti alone or at least one selected from Ti, Zr and Hf. And a dielectric ceramic composition containing a compound represented by
The element body is composed of an inside of the element body and a surface layer part covering the inside of the element body, and the surface layer part is a region having a depth of up to 10 μm from the surface of the element body.
When A / B indicating the molar ratio of A and B in the surface layer portion is AB1, and A / B indicating the molar ratio of A and B in the element body is AB2,
AB1 and AB2 satisfy the relationship of 0.992 ≦ AB1 / AB2 ≦ 0.998.

  In the present invention, the element body has a surface layer part and the inside of the element body, and the entire surface is covered with the surface layer part. That is, the outer surface of the element body is composed only of the surface layer portion, and the inside of the element body is not exposed on the outer surface of the element body. In addition, the A / B ratio (AB1) in the surface layer portion and the A / B ratio (AB2) in the interior have the above relationship.

  By doing in this way, the sintering state of a surface layer part and the sintering state inside can be controlled. As a result, it is possible to effectively prevent structural defects such as cracks and delamination while improving the hardness of the surface layer portion and improving the moisture resistance.

In addition, a method for manufacturing a ceramic electronic component according to the present invention includes:
A method of manufacturing a ceramic electronic component having an element body with a dielectric layer,
The dielectric layer has the general formula ABO ₃ (A is Ba alone or at least one selected from Ba and Ca and Sr, and B is Ti alone or at least one selected from Ti, Zr and Hf. And a dielectric ceramic composition containing a compound represented by
The element body is composed of an inside of the element body and a surface layer part covering the inside of the element body, and the surface layer part is a region having a depth of up to 10 μm from the surface of the element body.
When A / B indicating the molar ratio of A and B in the surface layer portion is AB1, and A / B indicating the molar ratio of A and B in the element body is AB2,
The AB1 and AB2 satisfy the relationship of 0.992 ≦ AB1 / AB2 ≦ 0.998,
Forming a pre-fired dielectric layer comprising a raw material of the compound and a binder resin to form a pre-fired element body;
The element body before firing is in contact with water;
Firing the element body before firing to obtain the element body,
The binder resin includes a water-soluble binder resin and a water-insoluble binder resin, and a ratio of the water-soluble binder resin to 100% by weight of the water-insoluble binder resin is 1 to 10% by weight.

  By using a water-soluble binder resin and a water-insoluble binder resin as the binder resin contained in the pre-firing dielectric layer, and setting the ratio of the water-soluble binder resin within the above range, the A / The B ratio and the internal A / B ratio can be controlled. As a result, the hardness of the surface of the element body after firing can be improved. Further, structural defects such as cracks and delamination can be effectively suppressed.

  Preferably, the water-soluble binder resin is at least one selected from polyvinyl alcohol and starch.

  Preferably, the water-insoluble binder resin is at least one selected from a butyral resin and an acrylic resin.

  By using the above binder resin as the water-soluble binder resin and the water-insoluble binder resin, the above-described effects can be further enhanced.

  Preferably, the pH of water used in the step of contacting the element body before firing with water is greater than 2. Examples of the step of bringing the element body before firing into contact with water include a step of wet cutting the assembly of the element bodies before firing to obtain the element body before firing, or a step of wet polishing the element body before firing.

  Preferably, the step in which the element body before firing contacts water is a wet barrel polishing step.

  Preferably, the pre-fired dielectric layer contains a plasticizer.

  By doing as described above, the above-described effects can be further enhanced.

FIG. 1 is a perspective view of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the multilayer ceramic capacitor shown in FIG. 1 cut along the line II-II. FIG. 3 is a cross-sectional view of the multilayer ceramic capacitor shown in FIG. 1 cut along the line III-III.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

Multilayer ceramic capacitor 1
As shown in FIG. 1, a multilayer ceramic capacitor 1 according to an embodiment of the present invention includes an element body 10 and a pair of external electrodes 4 formed at both ends of the element body 10.

Element body 10
As shown in FIG. 1, the element body 10 has a configuration in which dielectric layers 2 and internal electrode layers 3 are alternately stacked. The internal electrode layer 3 is laminated so that each end face is alternately exposed on the surface of the opposite end of the element body 10 and is connected to a pair of external electrodes 4 to constitute a capacitor circuit.

  Although there is no restriction | limiting in particular in the shape of the element main body 10, Usually, it is set as a rectangular parallelepiped shape as shown in FIG. Moreover, there is no restriction | limiting in particular also in the dimension, What is necessary is just to set it as a suitable dimension according to a use.

The dielectric layer 2 has the general formula ABO ₃ (A is Ba alone or at least one selected from Ba and Ca and Sr, and B is Ti alone or at least one selected from Ti, Zr and Hf. It is comprised from the dielectric ceramic composition containing the compound represented by this. This compound is a compound having a perovskite crystal structure, and includes at least Ba as an A site atom and at least Ti as a B site atom in the crystal structure.

  Further, the dielectric ceramic composition may contain other components in addition to the above-mentioned compound according to desired characteristics.

  Although the thickness of the dielectric material layer 2 is not specifically limited, It is preferable that it is 1-50 micrometers per layer.

  The upper limit of the number of stacked dielectric layers 2 is not particularly limited, but is about 1000, for example.

  The conductive material contained in the internal electrode layer 3 is not particularly limited, but a relatively inexpensive base metal can be used because the constituent material of the dielectric layer 2 has reduction resistance. As the base metal used as the conductive material, Ni or Ni alloy is preferable. The Ni alloy is preferably an alloy of Ni and one or more elements selected from Mn, Cr, Co and Al, and the Ni content in the alloy is preferably 95% by weight or more.

  The thickness of the internal electrode layer 3 may be appropriately determined according to the application and the like, but is usually about 0.1 to 3 μm, particularly preferably about 0.2 to 2.0 μm.

  Moreover, in this embodiment, the element main body 10 is comprised from the surface layer part 11 and the inside 12, as shown in FIG. The surface layer portion 11 is a region from the surface of the element body 10 to a depth of 10 μm and covers the inside 12 so as to surround it. Therefore, the interior 12 is not exposed on the surface of the element body 10.

In the present embodiment, the ratio (A / B ratio) of A and B in the compound represented by the general formula ABO ₃ is controlled in the dielectric ceramic composition constituting the dielectric layer. Specifically, when the molar ratio (A / B ratio) between A and B in the surface layer portion 11 is AB1, and the molar ratio (A / B ratio) between A and B in the interior 12 is AB2, AB1 and AB2 Satisfies the relationship 0.992 ≦ AB1 / AB2 ≦ 0.998, preferably 0.994 ≦ AB1 / AB2 ≦ 0.996.

The above relationship means that the A / B ratio (AB1) in the surface layer portion 11 is smaller than the A / B ratio (AB2) in the interior 12. Generally, in the compound ABO ₃ , when the A / B ratio is small, the sinterability of ABO ₃ is good (easy to sinter), and conversely, when the A / B ratio is large, the ABO ₃ is sintered. Tend to decrease (hard to sinter).

Therefore, if the firing temperature is the same, the smaller the A / B ratio, the easier it is to sinter. Therefore, by setting the value of AB1 / AB2 in the above range, the surface layer portion 11 has better sinterability than the element body interior 12. Accordingly, when the element body 10 is sufficiently sintered, the surface is baked and hardened, and the hardness of the surface is improved, so that the moisture resistance is improved. On the other hand, the internal sintered state is slightly lower than the surface layer portion and does not become an excessively sintered state. Therefore, cracks and delamination due to excessive firing do not occur.
The surface hardness can be evaluated by, for example, Vickers hardness.

  If the value AB1 / AB2 is too small, peeling tends to occur. Conversely, if the value AB1 / AB2 is too large, the surface hardness of the element body 10 is not sufficient and the moisture resistance tends to deteriorate. .

  The method for controlling AB1 / AB2 is not particularly limited. For example, the control may be performed by using a raw material having an A / B ratio of AB1 and a raw material having an A / B ratio of AB2. In the embodiment, as will be described later, the value of AB1 / AB2 is controlled by utilizing the fact that A-site atoms (particularly Ba) are easily eluted into water.

  In addition, since the surface layer portion does not include or hardly includes a portion that exhibits characteristics as a ceramic electronic component, even if the amount of A-site atoms is reduced, the property is not affected.

  In the present embodiment, the internal A / B ratio (AB2) is preferably 0.8 ≦ AB2 ≦ 1.4, and more preferably 0.95 ≦ AB2 ≦ 1.3. If AB2 is too small, abnormal grain growth occurs and the life and pressure resistance characteristics tend to deteriorate. If AB2 is too large, it is necessary to increase the sintering temperature, and thus structural defects occur in the firing process. There is a tendency.

External electrode 4
The conductive material contained in the external electrode 4 is not particularly limited, but in the present invention, inexpensive Ni, Cu, and alloys thereof can be used. The thickness of the external electrode 4 may be appropriately determined according to the application and the like, but is usually preferably about 10 to 50 μm.

Manufacturing Method of Multilayer Ceramic Capacitor 1 The method of manufacturing the multilayer ceramic capacitor 1 shown in FIG. 1 is not particularly limited, but in the present embodiment, a normal printing method using a paste, A green chip (element body before firing) is produced by a sheet method, fired, and then manufactured by printing or transferring external electrodes and firing. Hereinafter, the manufacturing method will be specifically described.

  First, a dielectric material for forming a dielectric layer is prepared, and this is made into a paint to prepare a dielectric layer paste.

  The dielectric layer paste is an organic paint obtained by kneading a dielectric material and an organic vehicle.

First, a raw material of ABO ₃ is prepared as a dielectric raw material. As the raw material, oxides of the above-described components, mixtures thereof, and composite oxides can be used. In addition, various compounds that become the above-described oxides or composite oxides by firing, such as carbonates and oxalates. , Nitrates, hydroxides, organometallic compounds, and the like may be selected as appropriate and used as a mixture.

In addition to the so-called solid phase method, the raw material of ABO ₃ can be produced by various methods such as those produced by various liquid phase methods (for example, oxalate method, hydrothermal synthesis method, alkoxide method, sol-gel method, etc.). What was manufactured can be used.

Furthermore, when a component other than ABO ₃ is contained in the dielectric layer, oxides of those components, a mixture thereof, or a composite oxide can be used as a raw material for the component, as described above. In addition, various compounds that become oxides or composite oxides by firing can be used.

  What is necessary is just to determine content of each raw material in a dielectric raw material so that it may become a desired composition after baking. In the state before forming a paint, the particle size of the dielectric material is usually about 0.1 to 1 μm in average particle size.

  An organic vehicle is obtained by dissolving a binder resin in an organic solvent. In the present embodiment, the binder resin includes a water-soluble binder resin and a water-insoluble binder resin.

  The water-soluble binder resin is not particularly limited as long as it is soluble in an organic solvent, but in the present embodiment, at least one selected from polyvinyl alcohol (PVA) and starch is preferable.

  The water-insoluble binder resin is not particularly limited, but is preferably at least one selected from a butyral resin and an acrylic resin in the present embodiment.

  The organic solvent is not particularly limited, and may be appropriately selected from various organic solvents such as acetone, toluene, alcohol, ethyl acetate, xylene, and methyl ethyl ketone.

  The contents of the binder resin, the solvent, etc. in the dielectric layer paste are not particularly limited. The usual contents, for example, the binder resin is about 1 to 10% by weight with respect to 100% by weight of the dielectric material, and the organic solvent is 10%. What is necessary is just about 50 weight%.

  The ratio of the water-soluble binder resin to 100% by weight of the water-insoluble binder resin is 1 to 10% by weight, preferably 1 to 8% by weight, and more preferably 2 to 7% by weight.

  The dielectric layer paste may contain additives selected from various dispersants, plasticizers, dielectrics, glass frit, insulators, antistatic agents and the like as required. In this embodiment, it is preferable that a plasticizer is included in order to improve the moldability and stackability of the green sheet. However, the total content of these is preferably 10% by weight or less.

  Examples of the plasticizer include phthalate esters such as dioctyl phthalate and benzylbutyl phthalate, adipic acid, phosphate esters, glycols, and the like. The plasticizer preferably has a content of 15 to 80% by weight with respect to 100% by weight of the binder resin. If the amount of the plasticizer is too small, the green sheet tends to be brittle. If the amount is too large, the plasticizer oozes out and is difficult to handle.

The internal electrode layer paste is obtained by kneading the above-mentioned organic vehicle with various conductive metals and alloys as described above, or various oxides, organometallic compounds, resinates, etc. that become the above-mentioned conductive materials after firing. Prepare. The internal electrode layer paste may contain a common material. Is not particularly restricted but includes the common material, it preferably has a composition similar to ABO _3.

  There is no restriction | limiting in particular in content of the organic vehicle in the paste for internal electrode layers, For example, binder resin should just be about 1 to 10 weight% and a solvent should be about 10 to 50 weight%. The paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators and the like as necessary. The total content of these is preferably 10% by weight or less.

  The external electrode paste may be prepared in the same manner as the internal electrode layer paste described above.

  Next, a green sheet is formed on the carrier sheet using the above-described dielectric layer paste. This green sheet forms a dielectric layer before firing in a green chip (element body before firing) described later. The green sheet is dried after being formed on the carrier sheet. The drying temperature of the green sheet is preferably 50 to 100 ° C., and the drying time is preferably 1 to 5 minutes.

  Next, an electrode pattern (pre-firing electrode layer) that forms the internal electrode layer 3 shown in FIG. 1 after firing is formed on one surface of the formed green sheet. The method for forming the electrode pattern is not particularly limited, and examples thereof include a printing method, a transfer method, and a thin film method. In the present embodiment, the internal electrode layer paste is applied in a predetermined pattern on the green sheet by screen printing. Thereafter, it is dried to form an electrode pattern.

  Further, a green sheet is further formed on the green sheet, and an exterior green sheet in which a plurality of green sheets are laminated is separately prepared.

  If the step between the green sheet and the electrode pattern adversely affects the laminating process, the green sheet on which the electrode pattern is not formed after or before the formation of the predetermined electrode pattern on the surface of the green sheet A blank pattern having substantially the same thickness as the electrode pattern may be formed on the surface. This blank pattern forms a pre-firing dielectric layer together with the green sheet.

  The blank paste for forming the blank pattern may be prepared in the same manner as the dielectric layer paste.

  Thereafter, the green sheet (interior green sheet) on which the electrode pattern is formed is peeled off from the carrier sheet, and the green sheet on which the electrode pattern is not formed is laminated on a laminate (green sheet for exterior). . Then, this operation was repeated, and the interior green sheets were alternately stacked up to the desired number of layers, and finally the exterior green sheets were stacked, and the interior green sheets were sandwiched between the exterior green sheets from both sides in the stacking direction. A green laminate having a configuration is prepared.

  Thereafter, the green laminate is finally pressurized. And this laminated body is cut | disconnected to predetermined size, and a green chip (element main body before baking) is obtained. At this time, the laminate may be cut wet. In this case, the green chip comes into contact with water.

Solidification drying In this embodiment, the obtained green chip is solidified and dried. The solidification drying process is a process for mainly removing components (solvent, plasticizer, etc.) other than the binder resin from the organic components contained in the green chip. As specific conditions, for example, the holding temperature is 80 to 190 ° C., the holding time is 1 to 30 hours, the atmosphere is air or nitrogen, and more preferably 0.5 atm or less.

  By performing solidification drying, components other than the binder resin are removed, so that fine pores are formed in portions where the components existed. For this reason, in the wet barrel polishing step described later, when the green chip and water come into contact with each other, water easily enters the fine pores formed.

Polishing In this embodiment, the green chip is polished after solidification and drying. The polishing method is not particularly limited, but is preferably wet. In this embodiment, wet barrel polishing is performed. In wet barrel polishing, green chips are put into a barrel container together with media and water, and polishing is performed for a predetermined time with a known barrel machine. As the medium, balls or beads such as alumina or zirconia may be used.

In wet barrel polishing, the green chip comes into contact with water. Since the dielectric layer before firing of the green chip contains a water-soluble binder resin, when water and the green chip come into contact with each other, the water-soluble binder resin in the vicinity of the surface of the green chip tends to be eluted. At this time, since the element (particularly Ba) constituting the A site atom in ABO ₃ is also easily eluted in water, these atoms are eluted in a trace amount together with the water-soluble binder resin. As a result, the A / B ratio in the region where the A site atoms are eluted is smaller than the internal A / B ratio. In this way, the value AB1 / AB2 can be controlled.

  In this embodiment, the value of AB1 / AB2 is controlled by changing the ratio of the water-soluble binder resin to 100% by weight of the water-insoluble binder resin. Moreover, it becomes easy to make the value of AB1 / AB2 within the range of this invention by making the ratio of water-soluble binder resin into the range mentioned above. When the ratio of the water-soluble binder resin is too small, it becomes difficult to set the value of AB1 / AB2 within the range of the present invention, and it tends to be inferior in cracking and moisture resistance. When the amount is too large, it is difficult to set the value of AB1 / AB2 within the range of the present invention, peeling occurs and the moisture resistance tends to be inferior.

  Moreover, even if the pH and water temperature of the water used in the wet barrel polishing step are changed, the value of AB1 / AB2 can be controlled. In addition, when making the value of AB1 / AB2 into the range of this invention, it is preferable to make pH larger than two. Moreover, it is preferable that water temperature shall be 10-20 degreeC.

  Even if the pre-firing dielectric layer is formed with one kind of paste including a water-soluble binder resin and a water-insoluble binder resin without using a plurality of raw materials having different A / B ratios, the above-described method can be used. , AB1 / AB2 can be controlled. Moreover, the value of AB1 / AB2 can be made within the scope of the present invention by appropriately changing the ratio of the water-soluble binder resin and the pH and water temperature of the water in the step of contacting the green chip with water.

A binder removal treatment is performed after polishing such as binder removal and firing . In this embodiment, since Ni is contained as a conductive material for forming the internal electrode layer 3, the atmosphere in the debinding process is preferably an air atmosphere or a nitrogen atmosphere. As other binder removal conditions, the rate of temperature rise is preferably 5 to 300 ° C./hour, the holding temperature is preferably 200 to 400 ° C., and the temperature holding time is preferably 0.5 to 20 hours.

  Subsequently, in the present embodiment, the green chip is preferably fired at a temperature of 1150 to 1300 ° C. In the wet barrel polishing step, A-site atoms are eluted on the surface of the green chip, so the A / B ratio in the surface portion of the green chip is smaller than the internal A / B ratio, and the surface portion is burned. The cohesion can be made better than the inside. As a result, even when the firing temperature is lowered, the surface hardness is sufficient, so that the moisture resistance can be improved.

  If the firing temperature is too low, densification of the dielectric layer 2 after sintering tends to be insufficient, and the capacitance tends to be insufficient, and if too high, the dielectric layer 2 becomes excessively fired, resulting in structural defects. Tend to increase.

In the present embodiment, the firing atmosphere is preferably a reducing atmosphere, and the green chip is preferably fired in an atmosphere having an oxygen partial pressure of 10 ⁻¹⁰ to 10 ⁻² Pa. If the oxygen partial pressure during firing is too low, the conductive material of the internal electrode layer 3 may abnormally sinter and break, and conversely if the oxygen partial pressure is too high, the internal electrode layer 3 tends to oxidize. There is. As the atmospheric gas, for example, a humidified mixed gas of N ₂ and H ₂ may be used.

In this embodiment, it is preferable to anneal the element body after firing. Annealing is a process for re-oxidizing the dielectric layer 2, whereby the accelerated life of the insulation resistance (IR) can be remarkably increased and the reliability is improved. The annealing is preferably performed under an oxygen partial pressure higher than the reducing atmosphere at the time of firing. Specifically, the annealing is preferably performed in an atmosphere having an oxygen partial pressure of preferably 10 ^{−2 to} 100 Pa. If the oxygen partial pressure during annealing is too low, it is difficult to re-oxidize the dielectric layer 2. Conversely, if it is too high, the internal electrode layer 3 tends to be oxidized and insulated.

  In the present embodiment, the holding temperature or maximum temperature during annealing is preferably set to a temperature of 1200 ° C. or lower. The holding time is preferably 0.5 to 4 hours. Note that annealing may be composed of only a temperature raising process and a temperature lowering process. That is, the temperature holding time may be zero. In this case, the holding temperature is synonymous with the maximum temperature.

  The capacitor element main body obtained as described above is subjected to end face polishing, for example, by barrel polishing or sand blasting, and the external electrode paste is applied and fired to form the external electrode 4. Then, if necessary, a coating layer is formed on the surface of the external electrode 4 by plating or the like.

  The multilayer ceramic capacitor of this embodiment manufactured in this way is mounted on a printed circuit board or the like by soldering or the like and used for various electronic devices.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the embodiment mentioned above at all, and can be variously modified within the range which does not deviate from the summary of this invention.

  In the above-described embodiment, the multilayer ceramic capacitor is exemplified as the electronic component according to the present invention. However, the electronic component according to the present invention is not limited to the multilayer ceramic capacitor, and any electronic component having the above configuration can be used. good.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

Example 1
BaTiO ₃ system powder as dielectric material: 100 parts by weight, butyral resin as water-insoluble binder resin: 5 parts by weight, methyl ethyl ketone as solvent: 40 parts by weight, modified methanol as solvent: 25 parts by weight , And 100% by weight of a water-insoluble binder resin, a polyvinyl alcohol as a water-soluble binder resin: 1 to 10% by weight and dioctyl phthalate as a plasticizer: 50% by weight are slurried with a ball mill. Thus, a dielectric layer paste was obtained.

  Three rolls of 100 parts by weight of Ni particles having an average particle size of 0.2 μm, 40 parts by weight of an organic vehicle (8 parts by weight of ethyl cellulose dissolved in 92 parts by weight of butyl carbitol), and 10 parts by weight of butyl carbitol. The mixture was kneaded and slurried to obtain an internal electrode layer paste.

Formation of Green Sheet and Green Laminate Using the above dielectric layer paste, a 1.0 μm thick green sheet (dielectric layer before firing) was formed on a PET film and dried. Next, an electrode pattern (pre-firing electrode layer) was formed to a thickness of 1.5 μm on the surface of the formed green sheet by a printing method using the above internal electrode layer paste. Subsequently, a green sheet (interior green sheet) on which an electrode pattern is formed is laminated on the exterior green sheet, and the exterior green sheet is laminated on the plurality of laminated interior green sheets. Thus, a green laminate was formed. This green laminate was cut into a predetermined size to obtain a green chip (element body before firing).

Solidification drying Next, the obtained green chip was solidified and dried. Solidification drying was performed at a holding temperature of 180 ° C. and a holding time of 20 hours. The atmosphere during solidification drying was an air atmosphere.

Wet barrel polishing Next, wet barrel polishing was performed on the solidified and dried green chip. The green chip was put into a barrel container together with media and water, and barrel-polished by a known barrel machine for 1 hour. The pH of water was 7, and the water temperature was 15 ° C. The green chip after barrel polishing was washed with water and dried. In wet barrel polishing, the element body before firing was in contact with water.

Binder removal, firing, annealing Next, the green chip after barrel polishing was subjected to binder removal treatment.
The binder removal was performed at a holding temperature: 250 ° C., a holding time: 8 hours, and an atmospheric gas: in the air.

Next, the green chip after the binder removal treatment was fired and annealed (heat treatment) to produce a chip-shaped element body. Firing was performed at a holding temperature of 1250 ° C., a holding time of 8 hours, and an atmosphere gas: a mixed gas of N ₂ and H ₂ (5%) humidified to a dew point of 20 ° C.

Annealing (reoxidation) was performed at a holding temperature of 1050 ° C., a holding time of 2 hours, and an atmosphere gas of N ₂ gas. The humidification of the atmospheric gas was performed using a wetter at a water temperature of 0 to 40 ° C.

  Next, after polishing the end face of the chip-shaped element body by barrel polishing, a Cu paste is applied to the end portion, and then a baking process is performed, followed by Ni plating and Sn plating processes to form terminal electrodes Thus, a sample of the multilayer ceramic capacitor shown in FIG. 1 was obtained. In addition, the size after baking of each chip | tip was 3.2 mm x 1.6 mm x 0.6 mm.

  The following evaluation was performed about the sample of the obtained multilayer ceramic capacitor.

About 1000 samples of cracks obtained multilayer ceramic capacitor, using an optical microscope, to observe the appearance of the samples were evaluated for the presence of cracks, the samples cracks were observed was poor. The results are shown in Table 1. Table 1 shows the number of defects per 1000 pieces.

For a sample 1000 interlayer peeling obtained multilayer ceramic capacitor, is defined as a crack between the exterior and the interior portions of the peeling layers, was evaluated by stereo microscope observation, the sample interlayer peeling was observed was poor. The results are shown in Table 1. Table 1 shows the number of defects per 1000 pieces.

Moisture resistance About 100 samples of the obtained multilayer ceramic capacitor, a PCBT test was conducted to evaluate the moisture resistance. The PCBT test was performed under the condition that the capacitor sample was held for 20 hours in an environment of a temperature of 121 ° C., a humidity of 95%, and 1 atm with a voltage of 50V applied. About the sample after a test, the insulation resistance was measured on the conditions of 50V-30 minutes, and the thing whose resistance fell 1 digit or more than before the test was made into the defect. The results are shown in Table 1. Table 1 shows the number of defects per 100 pieces.

  From Table 1, when the value of AB1 / AB2 is within the range of the present invention (sample numbers 3 to 7 and 9), it was confirmed that the moisture resistance was good and cracks and peeling were small.

Example 2
A multilayer ceramic capacitor sample was prepared in the same manner as Sample No. 5 in Example 1 except that the type of water-soluble binder resin and the ratio of the water-soluble binder resin to the water-insoluble binder resin were set to the values shown in Table 2. Then, the same characteristic evaluation as in Example 1 was performed. The results are shown in Table 2.

  For sample number 21, without using a water-soluble binder resin, the A / B of the interior portion is set to the value shown in “AB1” of Table 2, and the A / B of the exterior portion is shown in “AB2” of Table 2. Value.

  From Table 2, it was confirmed that the value of AB1 / AB2 can be controlled by changing the ratio of the water-soluble binder resin.

Example 3
A multilayer ceramic capacitor sample was prepared in the same manner as in Example 1 except that the pH of water during wet barrel polishing was changed to the value shown in Table 3, and the same characteristic evaluation as in Example 1 was performed. The results are shown in Table 3.

Example 4
A multilayer ceramic capacitor sample was prepared in the same manner as in Example 1 except that the water temperature during wet barrel polishing was changed to the values shown in Table 4, and the same characteristic evaluation as in Example 1 was performed. The results are shown in Table 4.

  From Table 3, it was confirmed that the value of AB1 / AB2 can be controlled by changing the pH of water used during wet barrel polishing.

  From Table 4, it was confirmed that the value of AB1 / AB2 could be controlled by changing the water temperature used during wet barrel polishing.

Comparative Example 5
A multilayer ceramic capacitor sample was prepared in the same manner as in Example 1 except that the water-soluble binder resin was not used and the A / B between the interior part and the exterior part was set to the values shown in Table 5. The same characteristic evaluation was performed. The results are shown in Table 5.

  The A / B ratio of the interior part is adjusted by setting the A / B ratio of the interior green sheet to the value shown in Table 5, and the A / B ratio of the exterior part is the A / B of the exterior green sheet. The ratio was adjusted to the value shown in Table 5.

  Since the interior part is not completely covered by the exterior part, and the interior part is exposed on the surface of the element body, from Table 5, the A / B ratio of the interior part and the A / B ratio of the exterior part It can be confirmed that the characteristics tend to deteriorate no matter how the relationship is changed. Specifically, in sample No. 61, it was confirmed that the moisture resistance deteriorated because the sintering of the element body surface did not proceed. On the other hand, in Sample No. 62, it was confirmed that structural defects such as cracks and peeling increased because the surface of the element main body was excessively sintered.

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 2 ... Dielectric layer 3 ... Internal electrode layer 4 ... External electrode 10 ... Element main body 11 ... Surface layer part 12 ... Inside

Claims (7)

A ceramic electronic component having an element body with a dielectric layer,
The dielectric layer has the general formula ABO ₃ (A is Ba alone or at least one selected from Ba and Ca and Sr, and B is Ti alone or at least one selected from Ti, Zr and Hf. And a dielectric ceramic composition containing a compound represented by
The element body is composed of an inside of the element body and a surface layer portion covering the element body so as to surround the inside of the element body, and the surface layer portion is a region having a depth of up to 10 μm from the surface of the element body.
When A / B indicating the molar ratio of A and B in the surface layer portion is AB1, and A / B indicating the molar ratio of A and B in the element body is AB2,
A ceramic electronic component characterized in that AB1 and AB2 satisfy a relationship of 0.992 ≦ AB1 / AB2 ≦ 0.998. A method of manufacturing a ceramic electronic component having an element body with a dielectric layer,
The dielectric layer has the general formula ABO ₃ (A is Ba alone or at least one selected from Ba and Ca and Sr, and B is Ti alone or at least one selected from Ti, Zr and Hf. And a dielectric ceramic composition containing a compound represented by
The element body is composed of an inside of the element body and a surface layer part covering the inside of the element body, and the surface layer part is a region having a depth of up to 10 μm from the surface of the element body.
When A / B indicating the molar ratio of A and B in the surface layer portion is AB1, and A / B indicating the molar ratio of A and B in the element body is AB2,
The AB1 and AB2 satisfy the relationship of 0.992 ≦ AB1 / AB2 ≦ 0.998,
Forming a pre-fired dielectric layer comprising a raw material of the compound and a binder resin to form a pre-fired element body;
The element body before firing is in contact with water;
Firing the element body before firing to obtain the element body,
The ceramic, wherein the binder resin includes a water-soluble binder resin and a water-insoluble binder resin, and a ratio of the water-soluble binder resin to 100% by weight of the water-insoluble binder resin is 1 to 10% by weight. Manufacturing method of electronic components.   The method for producing a ceramic electronic component according to claim 2, wherein the water-soluble binder resin is at least one selected from polyvinyl alcohol and starch.   The method for producing a ceramic electronic component according to claim 2 or 3, wherein the water-insoluble binder resin is at least one selected from a butyral resin and an acrylic resin.   The method for producing a ceramic electronic component according to any one of claims 2 to 4, wherein the pH of water used in the step of contacting the element body before firing with water is greater than 2.   The method for producing a ceramic electronic component according to any one of claims 2 to 5, wherein the step of contacting the element body before firing with water is a wet barrel polishing step.   The method for manufacturing a ceramic electronic component according to claim 2, wherein the pre-fired dielectric layer contains a plasticizer.

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