JP2010153720A - Method of manufacturing laminated ceramic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a laminated ceramic capacitor that obtains an objective capacitance and has no sintered compact structural defect and is superior in a reliable performance. <P>SOLUTION: The method of manufacturing the laminated ceramic capacitor includes a step of obtaining a laminated product by forming ceramic paste films 4, 5 for step absorption in a non-forming portion of metal paste films 3 on ceramic raw sheets 2, while alternately laminating the plural ceramic raw sheets 2 and the plural metal paste films 3. The ceramic paste films 4, 5 for step absorption consist of two sorts of formation patterns with different widths. Since an impact caused by an overlapping of the metal paste films 3 and the ceramic paste films 4, 5 for step absorption decreases by alternately forming in the laminating direction the two sorts in which a width of at least one forming pattern is made wider than a width of the non-forming portion of the metal paste films 3, the laminated ceramic capacitor superior in a reliability can be manufactured. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a multilayer ceramic capacitor used in various electronic devices.

  In recent years, miniaturization and increase in capacity of multilayer ceramic capacitors have been progressing rapidly. To achieve this, the dielectric layers and internal electrode layers per layer in multilayer ceramic capacitors have been thinned and these layers have been increased in thickness. The method of doing is taken.

  As the dielectric layer is made thinner and higher stacked, characteristic defects such as short-circuiting of the multilayer ceramic capacitor due to the close distance between the opposing internal electrodes increase. Further, the level difference due to the presence / absence of the internal electrode becomes large and structural defects of the sintered body are likely to occur, which greatly affects the reliability of the multilayer ceramic capacitor. As described above, quality assurance in the thinning and high stacking of dielectric layers has become extremely important.

For example, in Patent Document 1, in order to eliminate a step due to the presence / absence of an internal electrode, a plurality of ceramic raw sheets and a metal paste film are alternately laminated, and a non-formation portion of the metal paste film on the ceramic raw sheet A manufacturing method has been proposed in which a ceramic paste film formed in the above is laminated to obtain a laminate.
JP-A-11-26278

  However, in the method of Patent Document 1, when the step-absorbing ceramic paste film is formed, it is difficult to print and laminate the metal paste film and the step-absorbing ceramic paste film with high accuracy, and printing misalignment or When a portion where the overlap between the metal paste film generated due to stacking deviation and the ceramic paste film for level difference absorption is continuous over a plurality of portions, the pressure at the time of pressing the laminated body is concentrated on the overlapping portion. There was a problem that the ceramic ceramic capacitor was torn and discontinuous, and the capacity of the multilayer ceramic capacitor was reduced. In addition, when a portion without the step-absorbing ceramic paste film between the metal paste film and the step-absorbing ceramic paste film caused by printing misalignment or stacking misalignment is continuous over a plurality of layers, the portion becomes a cavity. There was a problem that reliability was lowered due to internal structural defects such as delamination and cracks in the sintered body.

  An object of the present invention is to solve the above-mentioned problems, and to provide a method for producing a multilayer ceramic capacitor that can obtain a target capacitance and that is excellent in reliability without a sintered body structural defect. To do.

  In order to achieve the above object, a method for manufacturing a multilayer ceramic capacitor according to the present invention includes alternately stacking a plurality of ceramic raw sheets and a plurality of metal paste films, and not forming the metal paste films on the ceramic raw sheets. A method of manufacturing a multilayer ceramic capacitor comprising a step of forming a step-absorbing ceramic paste film on a portion to obtain a laminate, wherein the step-absorbing ceramic paste film comprises two types having different formation patterns, In addition, two types in which the width of at least one of the formation patterns is larger than the width of the non-formation portion of the metal paste film are alternately formed in the stacking direction.

  According to the method for manufacturing a multilayer ceramic capacitor of the present invention, since two types of step-absorbing ceramic paste films having different widths are alternately stacked, a portion where the metal paste film and the step-absorbing ceramic paste film are largely overlapped Does not occur continuously over multiple layers, so the pressure concentration during pressing of the laminate due to the overlap between the metal paste film and the step-absorbing ceramic paste film is alleviated, and the metal paste film at the overlapping portion is prevented from being broken. Therefore, the target capacitance can be obtained.

  In addition, since the width of the formation pattern of at least one of the step-absorbing ceramic paste film is larger than the width of the non-formed portion of the metal paste film, a portion without the step-absorbing ceramic paste film is continuously generated across multiple layers. Therefore, the generation of cavities between the metal paste film and the step-absorbing ceramic paste film is suppressed, so that a multilayer ceramic capacitor having no sintered structure defects and excellent in reliability can be manufactured. .

(Embodiment)
Hereinafter, the manufacturing method of the multilayer ceramic capacitor of the present invention will be specifically described with reference to FIGS.

First, barium titanate as a main component and Mn ₃ O ₄ , Al ₂ O ₃ , SiO ₂ , Mg (OH) ₂ , and Dy ₂ O ₃ as weighed components are weighed to have a predetermined composition, and these weighed raw materials The powder was placed in a ball mill together with zirconia balls and pure water, wet mixed, and then dehydrated and dried. Next, this dry powder was put into a high-purity alumina crucible and calcined at 900 ° C. for 2 hours in air. Thereafter, the calcined powder was placed in a ball mill together with zirconia balls and pure water, wet-pulverized, and then dehydrated to produce a dielectric powder.

  Next, n-butyl acetate as an organic solvent, polyvinyl butyral resin as an organic binder, and BBP (butyl benzyl phthalate) as a plasticizer are added to the above dielectric powder, and mixed with a zirconia ball in a ball mill to form a first ceramic. A rally was made. The first ceramic slurry was applied and dried on a polyethylene terephthalate film by a doctor blade method to produce a raw ceramic sheet 2 having a thickness of 1.6 μm shown in FIGS.

  On the other hand, apart from the ceramic raw sheet 2, as shown in FIG. 2, a paste containing nickel as a main component is printed on the polyethylene terephthalate film 6 by a gravure printing method and dried to form an internal electrode having a thickness of 1.3 μm. A metal paste film 3 was produced. The size of the metal paste film 3 was 3.70 mm × 0.79 mm.

  On the other hand, in order to obtain the step absorbing ceramic paste films 4 and 5 of FIGS. 1 and 3, n-butyl acetate as an organic solvent, polyvinyl butyral resin as an organic binder, and BBP (butylbenzyl phthalate as a plasticizer). ) And mixed with a zirconia ball in a ball mill to prepare a second ceramic slurry. In addition, in order to make the 2nd ceramic slurry into a slurry suitable for gravure printing, the amount of plasticizers and the amount of organic solvents were changed compared with the 1st ceramic slurry.

  Using this second ceramic slurry, a gravure printing method is used so that the ceramic paste films 4 and 5 having different widths alternately on the ceramic raw sheet 2 have the same height as the metal paste film 3 as shown in FIG. Formed by. At this time, the step-absorbing ceramic paste films 4 and 5 having two types of widths were formed by changing the width of the pattern of the gravure plate on which the second ceramic slurry was printed. The specific width will be described later. Since FIG. 3 is shown as a model for explanation, it differs from the actual width dimension of the step-absorbing ceramic paste films 4 and 5.

  Next, the process of pressure transferring a ceramic raw sheet on which a step absorbing ceramic paste film is not formed on a metal plate as a support and removing the polyethylene terephthalate film is repeated a plurality of times to protect the lower side. A layer was formed.

  Subsequently, the metal paste film 3 serving as an internal electrode formed on the polyethylene terephthalate film 6 of FIG. 2 was pressure-transferred onto the protective layer, and the polyethylene terephthalate film 6 was removed.

  Further, the ceramic raw sheet 2 on which the step-absorbing ceramic paste films 4 and 5 of FIG. 3 are formed is pressure-transferred so as to have the positional relationship as shown in FIG. 4, and the polyethylene terephthalate film is removed. Thereafter, the metal paste film 3 serving as an internal electrode formed on the polyethylene terephthalate film 6 in FIG. 2 is pressure-transferred on the ceramic raw sheet while shifting by a certain dimension with respect to the metal paste film 3 previously pressure-transferred. The polyethylene terephthalate film 6 was removed.

  Furthermore, the ceramic raw sheet 2 on which the step-absorbing ceramic paste films 4 and 5 of FIG. 3 are formed is applied to the step-absorbing step having a width different from that of the step-absorbing ceramic paste films 4 and 5 previously formed in the stacking direction. The polyethylene terephthalate film was removed by pressure transfer while shifting a certain dimension so that the ceramic paste films 4 and 5 were formed. After the metal paste film 3 and the pressure transfer of the ceramic raw sheet 2 on which the step absorbing ceramic paste films 4 and 5 are formed are repeated a plurality of times, a step absorbing ceramic paste film is formed as an upper protective layer. The press transfer of the ceramic raw sheet without a plurality of times was repeated a plurality of times to obtain a laminated body 1 in which the step-absorbing ceramic paste films were alternately configured with different widths for each layer as shown in FIG. 1 and 4 are modeled for explanation, they are different from the actual width dimensions of the step-absorbing ceramic paste films 4 and 5.

  Here, the width of the step-absorbing ceramic paste films 4 and 5 formed above will be described. Sample No. 1, one step-absorbing ceramic paste film 4 is larger than the width of the non-formed portion of the metal paste film 3, and the other step-absorbing ceramic paste film 5 is wider than the width of the non-formed portion of the metal paste film 3. They were alternately formed so as to be larger and smaller than one of the step-absorbing ceramic paste films 4. Sample No. 2, one step absorbing ceramic paste film 4 is larger than the width of the non-formed portion of the metal paste film 3, and the other step absorbing ceramic paste film 5 is the same as the width of the non-formed portion of the metal paste film 3. Were formed alternately. Sample No. 3, one step absorbing ceramic paste film 4 is larger than the width of the non-formed portion of the metal paste film 3, and the other step absorbing ceramic paste film 5 is wider than the width of the non-formed portion of the metal paste film 3. It formed alternately so that it might become small. In this way, the ratio of the length of the overlapping portion of the metal paste film 3 and the step absorbing ceramic paste film 4 to the length in the short side direction of the metal paste film 3 is set to 5.1%. The length ratio of the overlapping portion of the metal paste film 3 and the step-absorbing ceramic paste film 5 with respect to the length in the short side direction is configured to be −2.5 to 2.5%.

  On the other hand, the laminated body of the multilayer ceramic capacitor of the comparative example was produced using the step absorbing ceramic paste film 4 formed with the same width. The step-absorbing ceramic paste film 4 was manufactured by the same manufacturing method as that of the laminate of the present invention except that the width of the ceramic paste film 4 was different from that of the present invention. Sample No. 4 is formed such that the width of the step-absorbing ceramic paste film 4 is larger than the width of the non-formed portion of the metal paste film 3. 5 is formed so that the width of the non-formed portion of the metal paste film 3 and the width of the step-absorbing ceramic paste film 4 are the same. 6 is formed such that the width of the step-absorbing ceramic paste film 4 is smaller than the width of the non-formation portion of the metal paste film 3, and absorbs the step difference between the metal paste film 3 and the length in the short side direction. The ratio of the length of the overlapping portion with the ceramic paste film 4 for use was -5.1 to 5.1%. In FIG. 5 shows the positional relationship between the metal paste film 3 and the step-absorbing ceramic paste film 4 during lamination by pressure transfer.

  Next, these six types of multilayer bodies were cut to a predetermined size to form individual multilayer ceramic capacitor green chips, and then six types of multilayer ceramic capacitors were produced as follows.

  First, the green chip was put into a zirconia-based sheath and treated for 2 hours at a maximum temperature of 450 ° C. in an industrial nitrogen gas atmosphere to remove the binder. Thereafter, the laminate after the binder removal treatment was treated at 1200 ° C. for 2 hours using a mixed gas of industrial nitrogen gas and nitrogen and hydrogen, and fired to obtain a sintered body.

  Next, a copper paste is applied to both end faces of the obtained sintered body, and baked at 900 ° C. in an industrial nitrogen atmosphere. Thereafter, Ni plating and Sn plating are performed to form external electrodes, Six types of multilayer ceramic capacitors having outer dimensions of 1.6 mm in length, 0.8 mm in width, 0.8 mm in thickness, and a target capacitance of 10 μF were produced.

The six types of multilayer ceramic capacitors produced as described above were evaluated for initial electrical characteristics, reliability, and presence or absence of sintered body structural defects. The initial electrical characteristics were evaluated by measuring the capacitance at 1 kHz and 1 Vrms, and calculating the average value of 50 samples. Moreover, what became 10 < ³ > ohm or less was evaluated as a short circuit. Reliability was evaluated for deterioration of insulation resistance after a high-temperature load test in which a DC voltage that was one time the rated voltage was applied at 85 ° C. for 1000 hours for each of 50 samples. When the insulation resistance value is less than 1 MΩ, the insulation resistance is deteriorated, and when there is no deterioration of the insulation resistance, it is evaluated as “◯”. The sintered body structural defect was examined for the presence or absence of delamination, cracks, etc. of the sintered body by appearance and cross-sectional observation for each of 100 samples. When there was no structural defect, it was marked with ◯, and when there was even one structural defect, it was marked with x. The evaluation results are shown in (Table 1). In Table 1, the overlapping portion A is an overlapping portion between the metal paste film and one step-absorbing ceramic paste film, and the overlapping portion B is an overlapping portion between the metal paste film and the other step-absorbing ceramic paste film. Part. Further, the ratio of (Table 1) is the ratio of the length of the overlapping portion to the length in the short side direction of the metal paste film.

  As shown in Table 1, Sample No. Nos. 4 to 6 are multilayer ceramic capacitors produced by a comparative manufacturing method in which the width of the step-absorbing ceramic paste film 4 is the same without changing the width. When the width of the step-absorbing ceramic paste film 4 becomes larger than the width of the non-formed portion of the metal paste film 3 as shown in FIG. Since the portion where the overlap between the metal paste film and the step-absorbing ceramic paste film generated due to the shift is continuous over a plurality, the pressure at the time of stack pressing concentrates on the overlapping portion, so the metal paste film at the overlapping portion is torn Then, it became discontinuous and the target capacitance could not be obtained. Sample No. When the width of the step-absorbing ceramic paste film 4 is reduced as in 5 and 6, the target capacitance can be obtained, but the gap between the metal paste film and the step-absorbing ceramic paste film caused by printing misalignment or stacking misalignment is obtained. Since the portion without the step-absorbing ceramic paste film is continuous over a plurality of layers, the portion becomes a cavity, resulting in internal structural defects such as delamination and cracks in the sintered body, and reliability is reduced.

  In contrast, sample no. Reference numerals 1 to 3 denote multilayer ceramic capacitors produced by the manufacturing method according to the embodiment of the present invention, wherein the step-absorbing ceramic paste films 4 and 5 are alternately formed with different widths for each layer.

  As apparent from the results shown in (Table 1), these sample Nos. Since the multilayer ceramic capacitors according to the manufacturing methods of the first to third embodiments of the present invention alternately laminate two types of step-absorbing ceramic paste films having different widths, a metal paste film and a step-absorbing ceramic paste film The part where the overlap is large does not occur continuously over multiple layers, so the pressure concentration during the pressing of the laminate due to the overlap between the metal paste film and the step-absorbing ceramic paste film is alleviated, and the metal paste in the overlap part Since tearing of the film is suppressed, a target capacitance can be obtained.

  In addition, since the width of the formation pattern of at least one of the step-absorbing ceramic paste film is larger than the width of the non-formed portion of the metal paste film, a portion without the step-absorbing ceramic paste film is continuously generated across multiple layers. For this reason, the generation of cavities between the metal paste film and the step-absorbing ceramic paste film is suppressed, so that a multilayer ceramic capacitor having no sintered structure defects and excellent in reliability can be obtained.

  Furthermore, sample no. In Nos. 2 and 3, by further reducing the width of one of the step-absorbing ceramic paste films 5, tearing of the metal paste film was further reduced, so that a higher capacitance could be obtained.

  As described above, in the method for manufacturing a multilayer ceramic capacitor according to the present invention, the step-absorbing ceramic paste film is composed of two types having different formation pattern widths, and at least one of the formation patterns has a width of the metal paste film. Since two types larger than the width of the non-formed part are alternately formed in the stacking direction, the target capacitance can be obtained, and there is no sintered body structural defect, and the stacking has excellent reliability. A ceramic capacitor can be obtained.

  In the present embodiment, printing patterns having different widths are formed on a gravure plate for producing a step-absorbing ceramic paste film, and a metal paste film 3 and a step-absorbing ceramic paste film are formed on one ceramic raw sheet 2. Although two types of step-absorbing ceramic paste films 4 and 5 are formed so that the overlap with 4 and 5 is different, two types of step-absorbing ceramic paste films 4 and 5 are used so that the overlap between the metal paste film and the step-absorbing ceramic paste film is different. Ceramic paste films may be produced and alternately laminated for each layer.

  Further, the printed body on which the metal paste film 3 and the step-absorbing ceramic paste films 4 and 5 are formed is rotated by 180 degrees for each layer and laminated, so that the step-absorbing ceramic is formed every other layer as in the present embodiment. The paste films 4 and 5 can be configured, and the same effect can be obtained.

  Moreover, in the said embodiment, although the metal paste film | membrane was formed on the polyethylene terephthalate film, the same effect is acquired even if it forms on a ceramic raw sheet.

  In this embodiment, the ceramic paste films 4 and 5 are formed in the non-formation portion of the metal paste film 3 in the width direction of the multilayer ceramic capacitor. However, the metal paste film in the longitudinal direction of the multilayer ceramic capacitor is not formed. Even if a ceramic paste film is formed in the portion, the same effect can be obtained.

  According to the method for manufacturing a multilayer ceramic capacitor according to the present invention, it is possible to obtain a target capacitance without causing a sintered body structural defect and a decrease in reliability. Is particularly useful in the production of small and high-capacity monolithic ceramic capacitors.

Schematic cross-sectional view of a laminate in an embodiment of the present invention The figure which shows the formation state of the metal paste film | membrane of the multilayer ceramic capacitor in embodiment of this invention The figure which shows the formation state of the ceramic paste film | membrane for level | step difference absorption of the multilayer ceramic capacitor in embodiment of this invention The figure which shows the relationship between the metal paste film of the multilayer ceramic capacitor in embodiment of this invention, and the ceramic paste film for level | step absorptions The figure which shows the relationship between the metal paste film of the multilayer ceramic capacitor of a comparative example, and the ceramic paste film for level | step difference absorption

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laminated body 2 Ceramic raw sheet 3 Metal paste film | membrane 4 Ceramic paste film | membrane for level | step difference absorption 5 Ceramic paste film | membrane for level | step difference absorption 6 Polyethylene terephthalate film

Claims (1)

A step of alternately laminating a plurality of ceramic raw sheets and a plurality of metal paste films, and forming a step absorption ceramic paste film on a non-formation portion of the metal paste film on the ceramic raw sheets to obtain a laminate. The step-absorbing ceramic paste film comprises two types having different formation pattern widths, and at least one of the formation pattern widths is a non-formation portion of the metal paste film. A method of manufacturing a multilayer ceramic capacitor, wherein two types larger than the width are alternately formed in the stacking direction.

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