JP2007288144A - Process for manfacturing multilayer ceramic electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the yield even in a case where thinning and multilayering of a dielectric layer have been progressed by suppressing occurrence of structural defect. <P>SOLUTION: A multilayer ceramic electronic component with a dielectric layer and an electrode layer laminated alternately is manufactured by laminating an interior green sheet containing dielectric powder, and an electrode precursor layer containing a conductive material alternately to form an interior. Then an exterior green sheet is laminated on the opposite sides of the interior in the laminating direction, they are burnt, and dielectric powder is added to the electrode precursor layer. It is assumed that the mean particle diameter of the dielectric powder contained in the interior green sheet is Ra, the mean particle diameter of the dielectric powder added to at least one of the electrode precursor layers arranged at the opposite ends of the interior portion in the laminating direction is Rc, and the mean particle diameter of the dielectric powder is Rb as added to the electrode precursor layer other than that to which the dielectric powder having the mean particle diameter Rc is added. Consequently, following relations are set; Rb/Ra≤1/2 and Rc/Rb>1.0. <P>COPYRIGHT: (C)2008,JPO&INPIT

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 arranged on both sides in the stacking direction, and a pair of conductive layers are connected to the electrode layers. The external electrode is provided. 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, an inner layer portion formed by laminating ceramic green sheets on which internal electrodes are formed, an outer layer portion formed of ceramic green sheets, and an internal electrode having a higher sintering temperature than the internal electrodes of the inner layer portion are formed. A multilayer ceramic electronic in which an intermediate layer part formed by laminating ceramic green sheets is laminated by placing the intermediate layer part between the inner layer part and the outer layer part, and the laminate is fired. A method for manufacturing a part is disclosed. Specifically, in order to make the sintering temperature of the internal electrode of the intermediate layer portion higher than the sintering temperature of the internal electrode of the internal layer portion, the internal electrode is formed of Ni powder, and Ni constituting the internal electrode of the intermediate layer portion The particle size of the powder is made larger than the particle size of the Ni powder constituting the internal electrode of the inner layer portion.
JP 2005-209721 A

  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 is thinned and multilayered, by adding a co-material to the electrode layer, as shown in the prior art A difference in sintering behavior larger than explained by the difference in sintering temperature between the simple internal electrode layer and the dielectric layer may occur, and structural defects such as delamination may occur near the corners of the interior part. I understood it. As the dielectric layer becomes thinner and multilayered, it is necessary to make the electrode layer thinner. In order to achieve a thinner electrode layer, the co-material added to the electrode layer must also be made finer. Since the sintering temperature of the miniaturized co-material is about the same as or lower than that of the conductive material (Ni) in the electrode layer, the electrode layer contracts at an early stage of firing, and the interior is affected by this effect. It is presumed that the structural defect occurs when the part shrinks before the exterior part.

  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. . For example, when the number of laminated dielectric layers is 150 or more and the thickness per layer is 3 μm or less, in order to reduce the influence of fine co-materials, the technique described in Patent Document 1 is described below. Not enough.

  The present invention has been proposed in view of such a conventional situation, and even when the dielectric layer is thinned and multilayered, the occurrence of structural defects is suppressed and the yield is improved. An object of the present invention is to provide a method for manufacturing a multilayer ceramic electronic component that can be achieved.

  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 the production of a multilayer ceramic electronic component in which dielectric layers and electrode layers are alternately laminated by laminating an exterior green sheet on both sides in the laminating direction of the interior portion, the electrode precursor Dielectric powder is added to the layer, and the average particle diameter of the dielectric powder contained in the interior green sheet and the exterior green sheet is Ra, and at least one electrode precursor layer is disposed at both ends in the stacking direction of the interior portion. The average particle size of the dielectric powder added to the electrode precursor layer other than the electrode precursor layer to which the dielectric powder of the average particle size Rc is added is Rc. When a, and sets such that the Rb / Ra ≦ 1/2, and setting so that Rc / Rb> 1.0.

  The dielectric powder (co-material) added to the electrode precursor layer has an effect of suppressing the sintering of the metal powder and delaying the sintering of the electrode layer in the firing process. However, when the dielectric powder added to the electrode precursor layer is miniaturized in order to make the dielectric layer thin and multilayer, that is, the average particle size of the dielectric powder contained in the interior green sheet and the exterior green sheet When the ratio Rb / Ra of the average particle diameter Rb of Ra and the dielectric powder added to the electrode precursor layer is set to be 1/2 or less, the dielectric powder added to the electrode precursor layer is baked on the contrary. It will act so as to speed up the bonding and increase the difference in sintering behavior between the interior part and the exterior part. As a result, stress due to the difference in the sintering behavior is concentrated at the interface between the interior portion and the exterior portion, and as a result, a structural defect such as delamination is generated near the corner portion of the interior portion.

  Therefore, in the present invention, the average particle diameter Rc of the dielectric powder added to the electrode precursor layer disposed at both ends of the interior portion in the stacking direction is the average particle diameter of the dielectric powder added to the electrode precursor layer disposed in the other part. By making it larger than the diameter Rb, the sintering of the electrode precursor layer to which the dielectric powder having the average particle diameter Rc is added is delayed. That is, a portion having a small difference in sintering behavior from the exterior portion is provided at both ends in the stacking direction of the interior portion. This reduces the stress concentration at the interface between the interior part and the exterior part because the sintering behavior in the interior part gradually changes so as to approach the sintering behavior of the exterior part as it goes outward in the stacking direction. As a result, the occurrence of structural defects is suppressed.

  Further, by adding a dielectric powder having an average particle size Rc satisfying the above conditions to the electrode precursor layers disposed at both ends in the stacking direction of the interior portion, the chip bending strength of the multilayer ceramic electronic component can be improved. . Therefore, the generation of cracks due to external stress when mounting the multilayer ceramic electronic component can be suppressed.

  In addition, if the particle size of the dielectric powder added in all the electrode precursor layers included in the interior portion is increased, the effect of suppressing the sintering of the electrode precursor layer is reduced. In ceramic electronic components, there are problems such as a decrease in capacity due to electrode layer breakage and an excess of product standard size due to spheroidization. The discontinuity or spheroidization of the electrode layer due to the increase in the particle size of the dielectric powder becomes more conspicuous toward the center in the stacking direction of the interior portion, but is relatively less likely to occur at both ends in the stacking direction. Therefore, by making the particle size of the dielectric powder added only to the electrode precursor layers arranged at both ends in the stacking direction relatively large, the occurrence of the structural defect can be suppressed while avoiding the above problem.

  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 improving effect can be obtained without causing a decrease in capacity or exceeding the product size standard.

  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 4 having a plurality of dielectric layers 2 and electrode layers 3. The electrode layer 3 is laminated on the two opposite end faces of the element body 4 so that the side end faces are alternately exposed, and is electrically connected to a pair of external electrodes 5 disposed on both side ends of the element body 4. Formed. In the element body 4, the exterior dielectric layer 6 is disposed outside both ends of the dielectric layer 2 and the electrode layer 3 in the stacking direction. An electrodeless region made of a dielectric layer is formed on an end surface of the element body 4 where the external electrode 5 is not formed, and an exterior portion made up of the exterior dielectric layer 6 and the electrodeless region is formed between the dielectric layer 2 and the electrode. The interior part formed by alternately laminating the layers 3 is protected.

  The shape of the element body 4 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 5 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 the external electrode 5 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. FIG. 2 is a cross-sectional view along the width direction of the multilayer body 11 that becomes the element body 4 after firing (a surface parallel to the end surface on which the external electrode 5 is formed).

  First, an interior green sheet 22 constituting the dielectric layer 2 after firing, an electrode precursor layer 21 constituting the electrode layer 3, and an exterior green sheet 23 constituting the exterior dielectric layer 4 are prepared. Next, the electrode precursor layer 21 is formed on the interior green sheet 22. Next, a plurality of the interior green sheets 22 are stacked, and the exterior green sheets 23 are stacked in a single layer or multiple layers on both sides in the stacking direction to form the stacked body 11.

  The laminate 11 includes an interior portion 12 including a plurality of electrode precursor layers 21 and an interior green sheet 22 sandwiched between the electrode precursor layers 21, and the electrode precursor layer 21 among the exterior green sheets 23 and the interior green sheets 22. It is comprised from the exterior part 13 which consists of an electrodeless area | region which is a part in which no is formed.

  The interior green sheet 22 is prepared by preparing a green sheet paint containing a dielectric powder as a raw material for the dielectric layer 2, applying the green sheet paint onto 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 22, 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 22, so that it is difficult to make the dielectric layer 2 thin. 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 Ra of the dielectric powder contained in the interior green sheet 22 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.

  On the other hand, an exterior green sheet 23 for forming the exterior dielectric layer 4 is prepared. A dielectric powder having the same average particle size Ra as the dielectric powder used for the interior green sheet 22 is used for the exterior green sheet 23. The exterior green sheet 23 can be formed by the same method as the interior green sheet 22.

  Next, the electrode precursor layer 21 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 22. The internal electrode paste for forming the electrode precursor layer 21 is prepared by kneading the conductive material described above, the dielectric powder as a co-material, and the organic vehicle described above.

  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 Correspondingly, for example, it must be thinned to 1.5 μm or less. In order to cope with the thinning of the electrode layer 3, the dielectric powder added to the electrode precursor layer 21 also needs to be miniaturized. The degree of refinement of the dielectric powder used as the co-material is determined based on the average particle size Rb of the dielectric powder added to the electrode precursor layer 21 and the average particle size of the dielectric powder contained in the interior green sheet 22 and the exterior green sheet 23. It can be expressed in relation to the diameter Ra. In the present embodiment, when the average particle size of the dielectric powder contained in the interior green sheet 22 and the exterior green sheet 23 is Ra, and the average particle size of the dielectric powder added to the electrode precursor layer 21 is Rb, Rb The dielectric powder added to the electrode precursor layer 21 is miniaturized so as to satisfy the relationship of / Ra ≦ 1/2.

  In the present embodiment, the average particle diameter of the dielectric powder added to at least one electrode precursor layer 21 disposed at both ends in the stacking direction of the interior portion 12 is Rc, and is added to the other electrode precursor layers 21. When the average particle size of the dielectric powder is Rb, Rc is relatively large. That is, it is set so as to satisfy the relationship of Rc / Rb> 1.0.

  Thus, the average particle diameter Rc of the dielectric powder added to the electrode precursor layer 21 near the exterior green sheet 23 and the average of the dielectric powder added to the electrode precursor layer 21 in the other part (for example, the central part). Even when the multilayer ceramic capacitor 1 is thinned and multilayered by setting the particle size Rb to be different and satisfying the relationship of Rc / Rb> 1.0, the electrode layer is formed at the center in the stacking direction. The occurrence of structural defects such as delamination during firing can be suppressed without causing interruption or spheroidization of 3. Moreover, since the bending strength of the multilayer ceramic capacitor is improved by adding dielectric powder having an average particle diameter Rc satisfying the above relationship to the electrode precursor layer 21 in the vicinity of the exterior green sheet 23, cracks are not generated. A multilayer ceramic capacitor can be mounted. The particle size of the dielectric powder is preferably set so that 1.2 ≦ Rc / Rb ≦ 3.0.

  The electrode precursor layer 21 to which the dielectric powder having the average particle diameter Rc is added may be present on both ends of the interior portion 12 in the stacking direction. In order to ensure both the anti-oxidation effect, when the number of laminated interior green sheets 22 is n, the mth layers (where m is 0.03 to 0.15 n) from both ends of the interior portion 12 in the stacking direction. It is preferable to add a dielectric powder having an average particle diameter Rc to the electrode precursor layer 21 and a dielectric powder having an average particle diameter Rb to the other electrode precursor layers 21. If m is less than 0.03n, the effect of the present invention may be insufficient, and if m exceeds 0.15n, the electrode layer 3 may be interrupted or spheroidized.

  As the dielectric powder added to the electrode precursor layer 21, 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.

  The thickness of the electrode precursor layer 21 is preferably changed according to the average particle diameter of the dielectric powder to be added. That is, Tc / Tb> 1 where Tc is the thickness of the electrode precursor layer to which the dielectric powder having the average particle diameter Rc is added and Tb is the thickness of the electrode precursor layer to which the dielectric powder having the average particle diameter Rb is added. It is preferable to set it to be 0.0. Thus, the electrode precursor layer can be reliably formed by relatively increasing the thickness of the electrode precursor layer to which the dielectric powder having a large particle size is added. A more preferable range of Tc / Tb is 1.0 to 1.5.

  After forming the laminated body 11, you may pressurize from the lamination direction both sides. When the laminate 11 is pressurized, the electrode precursor layer 21 located in the center of the stacking direction tends to be thinned and thinned due to the large pressure acting near the center of the stacking direction. Is likely to become a problem. Therefore, the present invention is extremely effective when applied to the case where pressure is applied to the laminate 11.

  There are optimum conditions for the pressurization. That is, as shown in FIG. 3, after pressing, when the laminate is cut along the width direction of the laminate 11 (a plane parallel to the end face on which the external electrodes are formed), the electrode located at the center in the lamination direction When the length of the precursor layer 21 is W1 and the length of the electrode precursor layer 21 located at the bottom in the stacking direction is W2, pressurization is performed so that W1 / W2 is 1.02-1.20. It is preferable. In addition, W1 / W2 before pressurization shall be 1.00. When pressurization is performed so that W1 / W2 is less than the above range, there is a fear that adhesion within the laminate 11 may not be obtained or the effects of the present invention may not be sufficiently obtained. When pressurization is performed so that W1 / W2 exceeds the above range, the pressurization is too strong and there is a possibility of short-circuiting between the electrode layers 3.

  After the pressurization, firing is performed to obtain a sintered body (element body). Prior to firing, it is preferable to perform a binder removal treatment. Moreover, it is preferable to perform a heat treatment for reoxidizing the dielectric layer 2 and the exterior dielectric layer 4 after firing. 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.

  In this embodiment, the average particle diameter Ra of the dielectric powder contained in the interior green sheet and the average particle diameter Rb of the dielectric powder added as a co-material to the electrode precursor layer are Rb / Ra ≦ 1/2. In such a case, the average particle size Rc of the dielectric powder added to at least one electrode precursor layer disposed at both ends in the stacking direction of the interior portion is set so that Rc / Rb> 1.0. Therefore, in the case of manufacturing a multilayer ceramic capacitor 1 that has been thinned and multilayered, it is possible to suppress the occurrence of structural defects without causing defects such as a decrease in capacity and an excess of dimensional standards, thereby improving yield. .

  Further, in the present invention, when the thickness of the dielectric layer in the fired multilayer ceramic capacitor is 3 μm or less, the thickness of the electrode layer is 1.5 μm or less, and the number of stacked dielectric layers is 150 or more, Especially effective. This is because as the dielectric layer of the multilayer ceramic capacitor becomes thinner and multilayered, the composition ratio of the electrode layer increases, and as a result, the yield decreases significantly due to the influence of the common material added to the electrode layer.

  In the above-described embodiment, the multilayer ceramic capacitor has been described as an example. Needless to say, the present invention can be applied to all multilayer ceramic electronic components other than the multilayer ceramic capacitor.

Experiment 1
<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 (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 added as 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.

  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 to obtain a stacked body.

  Moreover, the obtained laminated body was pressurized. The pressurizing condition is that the length of the electrode precursor layer at the central portion in the stacking direction when the stacked body after pressurization is cut along the width direction is W1, and the length of the electrode precursor layer at the bottom in the stacking direction is W2. In this case, the ratio W1 / W2 between W1 and W2 was set to be 1.10.

  The pressed 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.

  The dimensions of the obtained multilayer ceramic capacitor are 1.0 mm × 0.5 mm × 0.5 mm, the number n of dielectric layers constituting the interior portion is 160, and the number of dielectric layers per layer is 160. The thickness 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 2-8>
In Samples 2 to 8, dielectric powder having an average particle size Rc of 0.2 μm was added to the electrode precursor layers disposed at both ends of the interior portion in the stacking direction. That is, in samples 2 to 8, Rc / Rb was set to 2.0. As shown in Table 1, the number m of electrode precursor layers to which dielectric powder having an average particle diameter Rc was added was changed. For example, in sample 6, the average particle diameter of 0.2 μm (Rc / Rb = 2.2) from the electrode precursor layers at both ends in the stacking direction of the interior part to the 16th (ie, 0.10nth) electrode precursor layer. 0) Dielectric powder is added. In the table, in the item of the number of laminated sheets, the numbers after the decimal point are aligned to 2 digits by rounding off.

<Evaluation>
The number of defects when 100 samples were prepared was determined. Before firing external electrodes, the fired multilayer ceramic capacitor sample was cut along the width direction, the cut surface was polished, and when the polished surface was observed under a microscope, structural defects such as delamination were confirmed. There was a defect.

Moreover, the chip bending strength after baking was investigated. The bending strength was measured by performing a three-point bending test on the fired multilayer ceramic capacitor sample before forming the external electrode. Fifteen samples were tested, and the results obtained were subjected to Weibull analysis to determine the bending strength. Transverse strength is preferably 20 kgf / mm ² or more, more preferably 25 kgf / mm ² or more.

Each multilayer ceramic capacitor was examined for a decrease in capacitance. More specifically, “with reduced capacity” means that the electrostatic capacity of 1000 samples was measured with a digital LCR meter at 25 ° C. under the conditions of 1 kHz and 1.0 Vrms. An average of 1000 measurement results in 1 was defined as an average capacity, and a sample of a multilayer ceramic capacitor sample having a capacity of -10% or less with respect to the average capacity was regarded as having a decrease in capacity.
Furthermore, the presence or absence of short-circuit defects when 50 samples were prepared was examined. Specifically, a multilayer ceramic capacitor sample having a resistance value of 1 MΩ or less was regarded as a short circuit defect.

  From Table 1, in Sample 1 in which the average particle diameter of the dielectric powder as the co-material is the same in all the electrode precursor layers, many structural defects are generated, whereas Rc / Rb> 1. In the sample set to 0, it was confirmed that the number of occurrences of structural defects decreased. In addition, improvement in chip bending strength was also observed. In particular, by setting the number m of electrode precursor layers to 0.03 n layers or more, structural defects can be reliably suppressed, and sufficiently high bending strength can be obtained. However, when the number m of electrode precursor layers increased as in Sample 8, the capacity was reduced. Therefore, it can be seen that the number m of stacked electrode precursor layers is preferably 0.03n layer to 0.15n layer.

Experiment 2
<Samples 9 to 14>
In Samples 9-14, dielectrics having an average particle diameter Rc such that Rc / Rb satisfies the relationship shown in Table 2 from the electrode precursor layers at both ends in the stacking direction of the interior portion to the 0.10n-th electrode precursor layer. Body powder was added. Otherwise, a multilayer ceramic capacitor was prepared in the same manner as Sample 1, and the evaluation was performed for each multilayer ceramic capacitor. The results are shown in Table 2.

  When Rc / Rb is small as in sample 9, the occurrence of structural defects may not be reliably prevented. On the contrary, in the sample 14 having a large Rc / Rb, the electrode layer was interrupted or spheroidized, causing a decrease in capacity. In Sample 14, the metal in the electrode layer was spheroidized and the smoothness of the electrode layer was significantly deteriorated due to the large Rc, so that a short circuit defect occurred. Therefore, it has become clear that the particle size ratio Rc / Rb of the dielectric powder as the co-material is preferably 1.2 ≦ Rc / Rb ≦ 3.0.

Experiment 3
<Samples 15-20>
In Samples 15 to 20, by adjusting the pressurizing conditions when pressing the stacked body, in the stacked body after pressurization, the electrode at the central portion in the stacking direction when the stacked body is cut along the width direction The ratio W1 / W2 between the length W1 of the precursor layer and the length W2 of the lowermost electrode precursor layer in the stacking direction was set to the values shown in Table 3. However, in sample 11 where W1 / W2 is 1.00, the laminate is not pressurized. Otherwise, a multilayer ceramic capacitor was prepared in the same manner as Sample 1, and the evaluation was performed for each multilayer ceramic capacitor. The results are shown in Table 3.

  As is apparent from Table 3, the sample 15 in which the laminate was not pressurized caused structural defects due to insufficient sheet adhesion, while the sample 20 having a large W1 / W2 caused a short circuit due to a strong pressing force. Therefore, the ratio W1 / W2 of the width W1 of the electrode precursor layer at the center portion in the stacking direction and the width W2 of the electrode precursor layer at the bottom in the stacking direction in the stacked body after pressurization is 1.02-1.20. Thus, it has become clear that it is preferable to apply pressure.

Experiment 4
In this experiment, the ratio Rb / Ra between the average particle size Ra of the dielectric powder A used for the interior green sheet and the average particle size Rb of the dielectric powder B added as a co-material to the electrode precursor layer was examined.

<Samples 21 and 22>
In Samples 21 and 22, Rb / Ra was changed as shown in Table 4. Otherwise, a multilayer ceramic capacitor was produced in the same manner as in Sample 6, and the evaluation was performed. The results are shown in Table 4.

  As is clear from Table 4, good results were obtained by setting Rb / Ra to ½ or less. Although not shown in the data, in the multilayer ceramic capacitor set so that Rb / Ra> 1/2, even if Rc / Rb is outside the scope of the present invention, the frequency of occurrence of structural defects is Lower. 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 co-material in the electrode precursor layer so that Rb / Ra ≦ 1/2 and setting so that Rc / Rb> 1.0, the multilayer ceramic capacitor can be thinned. In addition, it is possible to achieve both a reduction in size and an increase in capacity by multilayering and suppression of the occurrence of structural defects.

It is principal part sectional drawing which shows the multilayer ceramic capacitor manufactured by this invention. It is principal part sectional drawing along the width direction of the laminated body before pressurization. It is principal part sectional drawing along the width direction of the laminated body after a pressurization.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor, 2 Dielectric layer, 3 Electrode layer, 4 Element main body, 5 External electrode, 6 Exterior dielectric layer, 11 Laminated body, 12 Interior part, 13 Exterior part, 21 Electrode precursor layer, 22 Interior green sheet , 23 Exterior green sheet

Claims (7)

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,
Dielectric powder is added to the electrode precursor layer, the average particle size of the dielectric powder contained in the interior green sheet and the exterior green sheet is Ra, and at least one layer disposed at both ends in the stacking direction of the interior portion. The average particle diameter of the dielectric powder added to the electrode precursor layer is Rc, and the average particle diameter of the dielectric powder added to the electrode precursor layer other than the electrode precursor layer to which the dielectric powder having the average particle diameter Rc is added When Rb is set to Rb, Rb / Ra ≦ 1/2 is set.
A method for producing a multilayer ceramic electronic component, wherein Rc / Rb> 1.0 is set.   When the number of laminated interior green sheets is n, dielectric added to the electrode precursor layers from the both ends of the interior portion in the stacking direction to the m-th layer (where m is 0.03 to 0.15n). 2. The method of manufacturing a multilayer ceramic electronic component according to claim 1, wherein the average particle size of the body powder is Rc, and the average particle size of the dielectric powder added to the other electrode precursor layers is Rb.   The method for producing a multilayer ceramic electronic component according to claim 1, wherein 1.2 ≦ Rc / Rb ≦ 3.0 is set.   The method for producing a multilayer ceramic electronic component according to any one of claims 1 to 3, wherein after the lamination is performed, the obtained multilayer body is pressurized from both sides in the lamination direction, and then the firing is performed.   When the laminated body is cut along a plane parallel to the end face on which the external electrode is formed after firing, the length of the electrode precursor layer located at the center in the laminating direction is W1, and the electrode precursor located at the bottom in the laminating direction 5. The method of manufacturing a multilayer ceramic electronic component according to claim 4, wherein the pressing is performed such that W1 / W2 is 1.02-1.20 when the length of the layer is W2.   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. The manufacturing method of the multilayer ceramic electronic component of any one of Claims 1-5.   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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