JP4882778B2 - Manufacturing method of multilayer ceramic electronic component - Google Patents

Description

  The present invention relates to a method for manufacturing a multilayer ceramic electronic component in which dielectric layers and electrode layers are alternately stacked.

  For example, in a multilayer ceramic electronic component typified by a multilayer ceramic capacitor, a plurality of dielectric layers and electrode layers are usually stacked alternately, and an exterior dielectric layer is disposed on both sides in the stacking direction. The structure is provided with a pair of external electrodes. With the recent miniaturization of electronic devices, there has been a demand for miniaturization and large capacity in multilayer ceramic electronic components such as multilayer ceramic capacitors. Further thinning and multilayering of electrode layers are also required.

  The multilayer ceramic electronic component having such a structure is manufactured, for example, by the following method. That is, first, a paint containing a dielectric powder, a binder, an organic solvent, etc. is prepared, and this paint is applied onto a support such as a PET film using a doctor blade method and dried, and then the PET film is peeled off. To get an interior green sheet. Next, an electrode precursor layer containing a conductive material is formed on the interior green sheet. Next, the interior green sheet on which the electrode precursor layer is formed is laminated, and an exterior green sheet to be an exterior dielectric layer is laminated on both sides in the stacking direction, and cut into a chip shape to obtain a green chip. After the green chip is fired, a multilayer ceramic electronic component is manufactured by forming external electrodes. As the conductive material contained in the electrode layer, Pd or Pd alloy is generally used. However, since Pd is expensive, in recent years, relatively inexpensive base metals such as Ni and Ni alloy have been used. ing.

  However, since base metals such as Ni have the property of sintering at a lower temperature than the dielectric powder constituting the green sheet, the product yield decreases when used in the electrode layer for the following reasons. cause. That is, due to the influence of Ni contained in the electrode precursor layer, the sintering temperature of the portion where the electrode precursor layer and the interior green sheet are alternately laminated (interior portion) is formed in the surrounding electrode precursor layer. This is because it is lower than the unexposed area and the exterior green sheet (exterior part), which causes a difference in shrinkage behavior during firing between the interior part and the exterior part, resulting in structural defects such as delamination. is there.

  Therefore, a method for solving the problem caused by the difference in the contraction behavior has been proposed. For example, in Patent Document 1, a method for manufacturing a multilayer ceramic electronic component using a green sheet whose shrinkage start temperature by firing is lower than that of a green sheet for an internal ceramic layer as a green sheet for a pair of protective layers disposed in the outermost layer In order to lower the shrinkage start temperature due to firing of the green sheet for the protective layer, the green sheet for the protective layer contains a sintering aid or increases the density of the green sheet for the protective layer. Therefore, the pulverization time and mixing time of the slurry for producing the green sheet are lengthened.

  Further, in Patent Document 2, the temperature at which the rate of change in shrinkage rate during firing of the outer ceramic layer is maximized and the change in shrinkage rate during firing in the state in which the internal electrode of the ceramic layer of the internal electrode laminate portion is formed. A method for manufacturing a multilayer ceramic electronic component in which the difference from the temperature at which the rate is maximum is 60 ° C. or less is disclosed, and the molar concentration A of the A-site ions of the ceramic constituting the ceramic layer of the internal electrode multilayer portion It is disclosed that the molar ratio A / B in the outer ceramic layer is made lower than the ratio A / B between the molar concentration B of B and B site ions.

Further, Patent Document 3 discloses a multilayer ceramic electronic component in which ceramic particles that form a predetermined depth from the surface of a protective layer are smaller than ceramic particles that form an inner ceramic layer.
JP-A-9-97733 JP 2004-221268 A Japanese Patent Laid-Open No. 11-354370

  However, as in the invention described in Patent Document 1, when the pulverization time and mixing time of the slurry for producing the protective layer green sheet are increased, the production time is increased, and thus the production efficiency is lowered. In addition, when a sintering aid is included in the green sheet for the protective layer, the number of necessary materials increases, leading to an increase in material cost, and further, the sintering aid added to the green sheet for the protective layer is added. It may diffuse into the green sheet for the internal ceramic layer and reduce the characteristics and reliability.

  By the way, a technique for reducing the shrinkage difference by adding dielectric powder (co-material) to the electrode layer is known, and a certain effect can be obtained. However, as a result of the study by the present inventors, in a multilayer ceramic electronic component in which the dielectric layer has been made thinner and multilayered, a large difference in sintering behavior can be obtained by adding a fine co-material to the electrode layer. It was found that structural defects such as delamination occurred from the corner portion of the interior portion to the vicinity of the boundary between the exterior dielectric layer and the electrodeless region around the interior dielectric layer during the firing process. The reason for the difference in shrinkage behavior is that the sintering temperature of the miniaturized co-material is the same as or lower than that of the conductive material (Ni) in the electrode layer, so the electrode layer shrinks at an early stage of firing, This is because the interior part contracts before the exterior part under this influence.

  In particular, as the dielectric layer of a multilayer ceramic electronic component becomes thinner and multi-layered, the composition ratio of the electrode layer in the multilayer ceramic electronic component increases, so the influence of the co-material added to the electrode layer increases. . The technique described in Patent Document 2 is not sufficient to reduce the influence of the common material in the multilayer ceramic electronic component in which the dielectric layer is thinned and multilayered as described above.

  In addition, when the dielectric powder for the dielectric layer is miniaturized in order to reduce the thickness of the dielectric layer, as shown in Patent Document 3, the dielectric powder for the dielectric layer (forms an inner ceramic layer) If the particle size of the dielectric powder for the exterior dielectric layer (ceramic particles forming from the surface of the protective layer to a predetermined depth) is made smaller than that of the ceramic particles), the air permeability of the exterior green sheet is lowered and laminated. Body formation becomes difficult. In addition, if the exterior green sheet is made as thin as the interior green sheet to ensure air permeability, the number of exterior green sheets used will increase, resulting in lower yield and longer lamination process time. Cause a decline.

  Therefore, the present invention has been proposed in view of such a conventional situation, and even when the dielectric layer is thinned and multilayered, the material cost is increased, the production efficiency is decreased, and the characteristics are increased. It is an object of the present invention to provide a method for manufacturing a multilayer ceramic electronic component capable of improving the yield without causing a decrease in the above.

  In order to achieve the above-mentioned object, a method for manufacturing a multilayer ceramic electronic component according to the present invention forms an interior part by alternately laminating interior green sheets containing dielectric powder and electrode precursor layers containing a conductive material. In manufacturing the multilayer ceramic electronic component in which the dielectric layers and the electrode layers are alternately stacked by stacking the exterior green sheets on both sides in the stacking direction of the interior portion, the electrode precursor layer When the dielectric powder is added to the inner green sheet, the average particle size of the dielectric powder contained in the interior green sheet is Ra, and the average particle size of the dielectric powder added to the electrode precursor layer is Rb. It is set so that ≦ 1/2, and the same dielectric powder as that of the electrode precursor layer is added to the exterior green sheet.

  When a fine co-material (dielectric powder) is added to the electrode precursor layer to make the dielectric layer thin and multilayer, that is, the average particle diameter Ra of the dielectric powder contained in the interior green sheet and the electrode When the ratio Rb / Ra of the average particle diameter Rb of the dielectric powder added to the precursor layer is set to 1/2 or less, the interior portion and the exterior are affected by the influence of the dielectric powder added to the electrode precursor layer. The difference in sintering behavior with the green sheet increases. Therefore, in the above manufacturing method, the same dielectric powder as the co-material is also added to the exterior green sheet, so that the shrinkage start temperature of the exterior green sheet is lowered and the difference in sintering behavior from the interior portion is reduced. Reduce the occurrence of structural defects. Here, since the dielectric powder added to the exterior green sheet is the same as the co-material used for the electrode precursor layer, the number of necessary materials does not increase and the production efficiency does not decrease. Furthermore, since the dielectric powder is added to the exterior green sheet which is a region having a small influence on the characteristics, deterioration of the characteristics of the multilayer ceramic electronic component can be suppressed.

  According to the method for manufacturing a multilayer ceramic electronic component as described above, even when the dielectric layer is thinned and multilayered, the occurrence of structural defects that occur during the firing process is suppressed, and the yield is improved. be able to. Moreover, according to the manufacturing method of the multilayer ceramic electronic component as described above, the yield improvement effect can be obtained while suppressing an increase in manufacturing cost and manufacturing time and maintaining good characteristics.

  Hereinafter, a method for manufacturing a multilayer ceramic electronic component to which the present invention is applied will be described in detail with reference to the drawings.

  First, a multilayer ceramic electronic component to be manufactured will be described with reference to FIG. A multilayer ceramic capacitor 1 according to an embodiment of the present invention includes an element body having a plurality of dielectric layers 2 and electrode layers 3. The electrode layer 3 is laminated so that the side end faces are alternately exposed at the two opposing end faces of the element body, and a pair of external electrodes (not shown) disposed at both end portions of the element body. Each is formed to be conductive. In the element body, the exterior dielectric layer 4 is disposed at both outer ends of the dielectric layer 2 and the electrode layer 3 in the stacking direction. In the element body, an electrodeless region 5 made of a dielectric layer is formed on an end surface on which no external electrode is formed, and an exterior portion 6 made of the exterior dielectric layer 4 and the electrodeless region 5 is made of a dielectric. The interior portion 7 in which the layers 2 and the electrode layers 3 are alternately stacked is protected.

  The shape of the element body is not particularly limited, but is usually a rectangular parallelepiped shape. The dimensions are not particularly limited, and may be set to appropriate dimensions according to the application. For example, length 0.6 mm to 5.6 mm (preferably 0.6 mm to 3.2 mm) × width 0.3 mm to 5.0 mm (preferably 0.3 mm to 1.6 mm) × thickness 0.1 mm to 1.9 mm (Preferably about 0.3 mm to 1.6 mm).

The dielectric layer 2 and the exterior dielectric layer 4 are made of a dielectric ceramic composition. As the dielectric ceramic composition, a composition formula ABO ₃ (wherein the A site is composed of at least one element selected from Sr, Ca and Ba. The B site is at least 1 selected from Ti and Zr). It is preferable to contain as a main component a dielectric oxide having a perovskite crystal structure represented by: Here, the amount of oxygen (O) may be slightly deviated from the stoichiometric composition of the composition formula. Among the dielectric oxides, it is preferable that the A site is mainly composed of Ba and the B site is mainly composed of Ti to form barium titanate. More preferably, it is barium titanate represented by the composition formula Ba _m TiO _{2 + m} (where 0.995 ≦ m ≦ 1.010 and 0.995 ≦ Ba / Ti ≦ 1.010). .

  The dielectric ceramic composition may contain various subcomponents in addition to the main component. Subcomponents are selected from oxides of Sr, Zr, Y, Gd, Tb, Dy, V, Mo, Zn, Cd, Ti, Sn, W, Ba, Ca, Mn, Mg, Cr, Si and P. At least one is exemplified. By adding the subcomponent, low temperature firing is possible without deteriorating the dielectric properties of the main component. Further, the reliability failure when the dielectric layer 2 is thinned is reduced, and the lifetime can be extended.

  Various conditions such as the number of laminated layers and the thickness of the dielectric layer 2 constituting the interior portion may be appropriately determined according to the application. The thickness of the dielectric layer 2 is about 0.5 μm to 50 μm, preferably 5 μm or less. From the viewpoint of reducing the size and capacity of the multilayer ceramic capacitor, the thickness of the dielectric layer 2 is preferably 3 μm or less, and the number of stacked dielectric layers 2 is preferably 150 or more. What is necessary is just to determine the thickness of the exterior dielectric layer 4 suitably according to a use, for example, it is about 20 micrometers-several hundred micrometers.

  Although the conductive material contained in the electrode layer 3 is not particularly limited, for example, a base metal such as Ni, Cu, Ni alloy, or Cu alloy can be used. What is necessary is just to determine the thickness of the electrode layer 3 suitably according to a use etc., for example, it is about 0.5 micrometer-5 micrometers, Preferably it is 1.5 micrometers or less.

  The conductive material contained in the external electrode is not particularly limited, but usually Cu, Cu alloy, Ni, Ni alloy, Ag, Ag—Pd alloy or the like is used. Cu, Cu alloy, Ni and Ni alloy are advantageous because they are inexpensive materials. What is necessary is just to determine the thickness of an external electrode suitably according to a use etc., for example, it is about 10 micrometers-50 micrometers.

  Hereinafter, an example of a method for manufacturing a multilayer ceramic capacitor will be described with reference to FIG.

  First, as shown in FIG. 2A, an interior green sheet 11 constituting the dielectric layer 2 after firing, an electrode precursor layer 12 constituting the electrode layer 3, and an exterior green sheet constituting the exterior dielectric layer 4 13 is prepared. Next, a plurality of interior green sheets 11 are stacked, and exterior green sheets 13 are stacked in a single layer or multiple layers on both sides in the stacking direction, and cut as necessary to form a stacked body 14.

  As shown in FIG. 2B, the laminated body 14 includes an interior portion 15 including a plurality of electrode precursor layers 12 and an interior green sheet 11 sandwiched between the electrode precursor layers 12, an exterior green sheet 13, and an interior It is comprised from the exterior part 16 which consists of the non-electrode area | region which is a part in which the electrode precursor layer 12 is not formed among the green sheets 11. FIG. In this embodiment, dielectric powder used as a co-material for the electrode precursor layer 12 is added to the exterior green sheet 13 constituting the exterior portion 16.

  The interior green sheet 11 is prepared by preparing a green sheet paint containing dielectric powder as a raw material for the dielectric layer 2, applying the green sheet paint on a carrier sheet as a support by a doctor blade method or the like, and drying Is obtained. The green sheet coating material is prepared by kneading a dielectric powder as a raw material of the dielectric layer 2 and an organic vehicle or an aqueous vehicle.

  As the dielectric powder used for the interior green sheet 11, the above-mentioned main component and subcomponent oxides and composite oxides can be used. In addition, various compounds that become oxides or composite oxides upon firing, such as carbonates, nitrates, hydroxides, organometallic compounds, and the like, can be appropriately selected and used.

  If the average particle size of the dielectric powder is too large, it is difficult to form a thin film of the interior green sheet 11, so that it is difficult to reduce the thickness of the dielectric layer 2. Conversely, the average particle size of the dielectric powder is small. If it is too large, the specific surface area of the dielectric powder increases, and abnormal grains may grow during firing. Therefore, the average particle size of the dielectric powder included in the interior green sheet 11 is preferably 0.1 μm to 1.0 μm.

  An organic vehicle is obtained by dissolving a binder in an organic solvent. The binder used for the organic vehicle is not particularly limited, and may be appropriately selected from ordinary various binders such as ethyl cellulose and polyvinyl butyral. Moreover, the organic solvent used for the organic vehicle is not particularly limited, and may be appropriately selected from various organic solvents such as terpineol, butyl carbitol, acetone, and toluene. The water-based vehicle is obtained by dissolving a water-soluble binder or dispersant in water, and the water-soluble binder is not particularly limited. For example, polyvinyl alcohol, cellulose, water-soluble acrylic resin, or the like may be used.

  Moreover, the electrode precursor layer 12 is formed by printing the internal electrode paste containing the raw material of the electrode layer 3 in a predetermined region of the interior green sheet 11. The internal electrode paste is prepared by kneading the above-described conductive material, common material, and the above-described organic vehicle.

  Dielectric powder is added to the electrode precursor layer 12 as a co-material. When the dielectric layer 2 of the multilayer ceramic capacitor 1 is thinned and multilayered so that the thickness of the dielectric layer 2 is 3 μm or less and the number of laminated dielectric layers 2 is 150 or more, the thickness of the electrode layer 3 Corresponding to this, it is necessary to make the layer thinner to, for example, 1.5 μm or less. However, in order to cope with the thinning of the electrode layer 3, it is necessary to refine the co-material used for the electrode precursor layer 12. . The degree of miniaturization of the common material is expressed by the relationship between the average particle size Rb of the dielectric powder used as the common material and the average particle size Ra of the dielectric powder contained in the interior green sheet 11 to be the dielectric layer 2. Can do. In the present embodiment, when the average particle size of the dielectric powder contained in the interior green sheet 11 is Ra and the average particle size of the dielectric powder added to the electrode precursor layer 12 is Rb, Rb / Ra ≦ 1 / The dielectric powder added to the electrode precursor layer 12 is miniaturized so as to satisfy the relationship of 2.

  The addition amount of the dielectric powder in the electrode precursor layer 12 is preferably 5% by mass to 30% by mass. When it is less than the above range, the effect as a co-material becomes insufficient, and when it exceeds the above range, the difference in sintering behavior between the interior portion 15 and the exterior portion 16 becomes large, which may increase the structural defects.

  As the dielectric powder to be added to the electrode precursor layer 12, the above-mentioned main component, subcomponent oxide or composite oxide can be used. In addition, various compounds that become oxides or composite oxides upon firing, such as carbonates, nitrates, hydroxides, organometallic compounds, and the like, can be appropriately selected and used.

  On the other hand, an exterior green sheet 13 for forming the exterior dielectric layer 4 is prepared. The exterior green sheet 13 is prepared by preparing an exterior green sheet paint containing dielectric powder as a raw material for the exterior dielectric layer 4 and applying the exterior green sheet paint onto a carrier sheet as a support by a doctor blade method or the like. And dried. The coating material for the exterior green sheet is prepared by kneading a dielectric powder that is a raw material for the exterior dielectric layer 4 and an organic vehicle or an aqueous vehicle. As the organic vehicle or the water-based vehicle, those usable for forming the interior green sheet 11 can be used.

  In the present embodiment, a dielectric powder similar to the dielectric powder added to the electrode precursor layer 12 is also added to the exterior green sheet 13. By adding a fine dielectric powder to the exterior green sheet 13, the difference in sintering behavior between the exterior portion 16 and the interior portion 15 is reduced, so that the structure resulting from the dielectric powder added to the electrode precursor layer 12 The occurrence of defects can be suppressed and the yield can be improved.

  It is preferable to add 0.1 to 20% by mass of the dielectric powder to the exterior green sheet 13. When the addition amount of the dielectric powder is less than 0.1% by mass, the effect of the present invention may not be sufficiently obtained. When the addition amount exceeds 20% by mass, the outer green sheet 13 has air permeability. There is a possibility that it will deteriorate and peeling from the support will be difficult.

  The exterior green sheet 13 naturally includes dielectric powder other than the additive dielectric powder. In addition to the co-material, the dielectric powder contained in the exterior green sheet 13 includes the above-mentioned main component and subcomponent oxides and complex oxides, and various compounds that become oxides and complex oxides upon firing, such as carbonates. , Nitrates, hydroxides, organometallic compounds, and the like can be used. The particle size can be 0.1 μm to 1.0 μm, for example.

  After the laminated body 14 is formed, binder removal processing, firing, and heat treatment for reoxidizing the dielectric layer 2 and the exterior dielectric layer 4 are performed to obtain a sintered body (element body). The binder removal treatment, the heat treatment for firing and reoxidation may be performed continuously, or each may be performed independently.

The binder removal treatment may be performed under normal conditions, but when a base metal such as Ni or Ni alloy is used for the conductive material of the electrode layer 3, it is preferable to perform under the following conditions. That is, the temperature rising rate is 5 to 300 ° C./hour, particularly 10 to 50 ° C./hour, the holding temperature is 200 to 400 ° C., particularly 250 to 340 ° C., and the holding time is 0.5 to 20 hours, particularly 1 to The mixed gas of N ₂ and H ₂ is humidified for 10 hours.

Firing is preferably performed under the following conditions. That is, the temperature rising rate is 50 to 500 ° C./hour, particularly 200 to 300 ° C./hour, the holding temperature is 1100 to 1350 ° C., particularly 1150 to 1300 ° C., and the holding time is 0.5 to 8 hours, particularly 1 to 1. The mixed gas of N ₂ and H ₂ is humidified for 3 hours.

In firing, the oxygen partial pressure in the atmosphere is preferably 10 ⁻² Pa or less. If it exceeds the above range, the electrode layer 3 may be oxidized. However, if the oxygen partial pressure is too low, the electrode material causes abnormal sintering, and the electrode layer 3 tends to be interrupted. Therefore, the oxygen partial pressure in the firing atmosphere is preferably 10 ⁻² Pa to 10 ⁻⁸ Pa.

  The heat treatment after firing is performed at a holding temperature or maximum temperature of usually 1000 ° C. or higher, preferably 1000 ° C. to 1100 ° C. If it is less than the above range, the insulation resistance life tends to be short due to insufficient oxidation of the dielectric material. If it exceeds the above range, the conductive material (Ni) in the electrode layer 3 is oxidized, and the multilayer ceramic capacitor May adversely affect the capacity and life of the product.

The atmosphere of the heat treatment is an oxygen partial pressure higher than that of firing, and is preferably 10 ⁻³ Pa to 1 Pa, more preferably 10 ^{−2 to 1} Pa. If it is less than the above range, it is difficult to reoxidize the dielectric layer. Conversely, if it exceeds the above range, the electrode layer 3 may be oxidized. The heat treatment conditions are a holding time of 0 to 6 hours, particularly 2 to 5 hours, a cooling rate of 50 to 500 ° C./hour, particularly 100 to 300 ° C./hour, and a humidified N ₂ gas or the like. .

  Next, external electrodes are formed on the element body, which is the obtained sintered body, to obtain the multilayer ceramic capacitor 1 shown in FIG. The external electrode may be formed by subjecting the sintered body to end surface polishing by barrel polishing, sand blasting, or the like, and baking the external electrode paint.

  The average particle size Ra of the dielectric powder contained in the interior green sheet 11 and the average particle size Rb of the dielectric powder added as a co-material to the electrode precursor layer 12 are set to satisfy Rb / Ra ≦ 1/2. In such a case, the difference in sintering behavior between the interior portion and the exterior portion increases, and structural defects such as delamination occur during the firing process. When the area of the electrode precursor layer 12 is smaller than the area of the interior green sheet 11 and the electrodeless region 5 is formed around the sintered ceramic capacitor 1 after firing, the structural defect is caused by the interior portion 7. It frequently occurs along the boundary between the non-electrode region 5 and the exterior dielectric layer 4 from the corner portion of the above.

  Therefore, as described above, the same dielectric powder as the dielectric powder added as a co-material to the electrode precursor layer 12 is also added to the exterior green sheet 13, thereby eliminating the difference in sintering behavior and Defects can be reduced and yield can be improved. Here, since the same dielectric powder as the co-material used for the electrode precursor layer 12 is added to the exterior green sheet 13, it is not necessary to prepare a new material or add a special manufacturing process. Further, since the dielectric powder is added to the portion that becomes the exterior portion 16 after firing, the characteristics of the multilayer ceramic capacitor 1 are not affected. Therefore, the yield improvement effect can be obtained without causing an increase in material cost, a long manufacturing time, and a decrease in characteristics.

  In the present invention, the thickness of the dielectric layer 2 in the fired multilayer ceramic capacitor 1 is 3 μm or less, the thickness of the electrode layer 3 is 1.5 μm or less, and the number of stacked dielectric layers 2 is 150 or more. Is particularly effective. This is because, as the dielectric layer 2 of the multilayer ceramic capacitor 1 becomes thinner and multilayered, the composition ratio of the electrode layer 3 increases, and as a result, the yield decreases due to the influence of the common material used for the electrode layer 3. Because.

  In the above-described embodiment, the case where a dielectric powder similar to the dielectric powder added to the electrode precursor layer 12 is added to the exterior green sheet 13 has been described, but the present invention is not limited thereto. For example, when the area of the electrode precursor layer 12 is smaller than the area of the interior green sheet 11, the electrode precursor layer 12 of the interior green sheet 11 around the side of the electrode precursor layer 12 that is not connected to the external electrode. The dielectric powder may be added to both the non-electrode area and the exterior green sheet 13, that is, the entire exterior portion 16. A higher effect can be obtained by adding the dielectric powder added to the electrode precursor layer 12 to the entire exterior portion 16. However, in this case, from the viewpoint of avoiding the influence on the characteristics, in the interior green sheet 11, the dielectric powder is added only to the non-electrode area corresponding to the exterior part 16, and the electrode forming area corresponding to the interior part 15 is added. It is preferable not to add the dielectric powder.

  Needless to say, the present invention is applicable to all multilayer ceramic electronic components other than multilayer ceramic capacitors.

Experiment 1
In this experiment, the effect when a powder similar to the dielectric powder added as a co-material to the electrode precursor layer was added to the exterior green sheet was examined.
<Sample 1>
First, an interior green sheet paint was prepared. The raw material dielectric powder was mixed and pulverized using a ball mill to obtain an interior green sheet paint. Dielectric powder A, MgCO ₃ , MnCO ₃ , Y ₂ O ₃ , V ₂ O ₅ , and (Ba, Ca) SiO ₃ were used as the raw material dielectric powder. The dielectric powder A used here was a BaTiO ₃ powder, and the average particle size Ra thereof was 0.35 μm.

Next, an internal electrode paste was prepared. Ni powder having an average particle size of 0.20 μm, dielectric powder B (co-material), and an organic vehicle were kneaded with three rolls and slurried to obtain an internal electrode paste. The average particle diameter of the Ni powder was 0.20 μm. Here, the dielectric powder B used for the co-material was BaTiO ₃ powder, and the average particle size Rb was 0.1 μm.

  Using the interior green sheet paint, an interior green sheet was formed on a PET film so that the thickness after drying was 2.4 μm. The electrode precursor layer was printed on the predetermined area of the interior green sheet using the internal electrode paste, and then the sheet was peeled from the PET film.

Meanwhile, an exterior green sheet was prepared. The raw material dielectric powder was mixed and pulverized using a ball mill to obtain a coating for an exterior green sheet. As the raw material dielectric powder, BaTiO ₃ (average particle size 0.35 μm), MgCO ₃ , MnCO ₃ , Y ₂ O ₃ , V ₂ O ₅ , (Ba, Ca) SiO ₃ were used. Using the coating material for exterior green sheets, a film was formed on a PET film so that the thickness after drying was 8 μm, and then the sheet was peeled from the PET film to obtain an exterior green sheet. In Sample 1, the same dielectric powder as that used as the co-material for the electrode precursor layer, ie, dielectric powder B (BaTiO ₃ powder) was added to the exterior green sheet. The amount of the dielectric powder B added was 0.01% by mass. That is, 0.01 part by mass of dielectric powder B was added to 100 parts by mass of the raw material dielectric powder A (BaTiO ₃ (average particle size 0.35 μm)).

  Next, a plurality of interior green sheets on which the electrode precursor layer was formed were stacked, and a plurality of exterior green sheets were stacked on both sides in the stacking direction, and pressed to prepare a stack. The obtained laminate was cut into a predetermined size to obtain a green chip, and then a binder removal treatment, firing and annealing were performed to obtain a sintered body. After polishing the end surface of the obtained sintered body by sand blasting, external electrodes were formed on the end surface in the longitudinal direction of the sintered body to obtain a multilayer ceramic capacitor sample. In this example, a multilayer ceramic capacitor sample of Sample 1 was obtained by changing the type of the exterior green sheet.

  The dimensions of the obtained multilayer ceramic capacitor are 1.0 mm × 0.5 mm × 0.5 mm, the number of laminated dielectric layers constituting the interior portion is 160, and the thickness of the dielectric layer per layer is Was 1.6 μm, the thickness of the electrode layer was 1.0 μm, and the thickness of the exterior dielectric layer was 45 μm. The thickness of the dielectric layer in the interior portion was determined as follows. That is, after cutting the multilayer ceramic capacitor along the stacking direction and polishing the cut surface, the polished surface is observed with a metal microscope, and by performing digital processing on the observed image, the average thickness of the dielectric layer is obtained, This was taken as the thickness of the dielectric layer of the interior part.

<Samples 2 to 13>
In Samples 2 to 8, multilayer ceramic capacitors were produced in the same manner as Sample 1 except that the amount of common material (dielectric powder B) in the exterior green sheet was changed as shown in Table 1. In Sample 9 to Sample 11, Rb / Ra was changed as shown in Table 1, and the others were made in the same manner as Sample 1, and multilayer ceramic capacitors were produced. As a comparative example, a multilayer ceramic capacitor was prepared without adding the common material (dielectric powder B) to the exterior green sheet (Sample 12). Furthermore, as a comparative example, a multilayer ceramic capacitor was fabricated by setting so that Rb / Ra> 1/2 (Sample 13).

<Evaluation>
The number of defects when 100 samples were prepared was determined. When the sintered multilayer ceramic capacitor sample before forming the external electrode is cut in the direction as shown in FIG. 1, the cut surface is polished, and the polished surface is observed with a microscope, structural defects such as delamination are found. What was confirmed was considered to be defective.

  From Table 1, many structural defects occur in sample 12 using a normal exterior green sheet, whereas structural defects occur in a sample in which a common material (dielectric powder B) is added to the exterior green sheet. It was confirmed that the number decreased. In particular, structural defects could be reliably suppressed by setting the common material addition amount to 0.1% by mass or more. However, in Sample 8 in which the amount of added common material was increased, the air permeability of the exterior green sheet was lowered, and the exterior green sheet was damaged when peeled from the PET film, so that it was impossible to produce a laminate. Therefore, it can be seen that the addition amount of the common material to the exterior green sheet is preferably 0.1% by mass to 20% by mass.

  Further, as apparent from the results of Samples 9 to 11, the occurrence of structural defects is suppressed by setting Rb / Ra ≦ 1/2. On the other hand, from the results of Sample 13, in the multilayer ceramic capacitor set so as to satisfy Rb / Ra> 1/2, even when the exterior green sheet to which the dielectric powder B is not added is used, the structure The frequency of defects was low. However, under the condition that Rb / Ra> 1/2, the dielectric layer cannot be thinned and multilayered, and it is difficult to obtain a small and large capacity multilayer ceramic capacitor. Therefore, by reducing the size of the common material in the electrode precursor layer so that Rb / Ra ≦ 1/2 and adding the common material to the exterior green sheet, the multilayer ceramic capacitor can be made thinner and multilayered. It was confirmed that it was possible to achieve both a reduction in size and an increase in capacity and suppression of occurrence of structural defects.

Experiment 2
In this experiment, the effect of adding the common material (dielectric powder B) to the exterior green sheet was examined.

<Sample 14>
In sample 14, by setting the addition amount of the common material (dielectric powder B) to the exterior green sheet as shown in Table 2, the average particle size of the entire dielectric powder in the exterior green sheet was 0.30 μm. It adjusted so that it might become. That is, in Sample 14, two types of dielectric powders having the same composition but different particle size distribution were used for the exterior green sheet. Otherwise, a multilayer ceramic capacitor was produced in the same manner as Sample 1.

<Sample 15>
In Sample 15, an external green sheet was prepared using BaTiO ₃ powder having an average particle size of 0.30 μm in advance without adding the common material (dielectric powder B). Otherwise, a multilayer ceramic capacitor was produced in the same manner as Sample 1.
Said evaluation was performed about each multilayer ceramic capacitor. The results are shown in Table 2.

  From the above results, it was confirmed that the effect of the present invention can be obtained by adding fine dielectric powder to the exterior green sheet, rather than reducing the particle size of the entire dielectric powder in the exterior green sheet. It was.

It is principal part sectional drawing which shows an example of the multilayer ceramic capacitor manufactured by this invention. It is an example of the lamination | stacking state of the green sheet and exterior green sheet before baking, (a) is principal part sectional drawing which shows the state decomposed | disassembled partially, (b) is principal part sectional drawing which shows a laminated body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor, 2 Dielectric layer, 3 Electrode layer, 4 Exterior dielectric layer, 5 Electrodeless area, 6 Exterior part, 7 Interior part, 11 Green sheet, 12 Electrode precursor layer, 13 Exterior green sheet, 14 Lamination Body, 15 interior parts, 16 exterior parts

Claims (4)

An interior green sheet containing dielectric powder and an electrode precursor layer containing a conductive material are alternately laminated to form an interior part, and an exterior green sheet is laminated on both sides of the interior part in the stacking direction, and then fired. When manufacturing a multilayer ceramic electronic component in which dielectric layers and electrode layers are alternately stacked,
When dielectric powder is added to the electrode precursor layer, the average particle diameter of the dielectric powder contained in the interior green sheet is Ra, and the average particle diameter of the dielectric powder added to the electrode precursor layer is Rb. And Rb / Ra ≦ 1/2, and
A method for producing a multilayer ceramic electronic component, comprising adding a dielectric powder similar to that of the electrode precursor layer to the exterior green sheet.   The method for producing a multilayer ceramic electronic component according to claim 1, wherein 0.1 mass% to 20 mass% of a dielectric powder similar to the electrode precursor layer is added to the exterior green sheet.   In the fired multilayer ceramic electronic component, the number of stacked dielectric layers is 150 or more, the thickness of the dielectric layer is 3 μm or less, and the thickness of the electrode layer is 1.5 μm or less. A method for producing a multilayer ceramic electronic component according to claim 1 or 2. The area of the electrode precursor layer is made smaller than the area of the interior green sheet so that an electrodeless region is formed around the fired multilayer ceramic electronic component. The method for producing a multilayer ceramic electronic component according to any one of the above.

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