JP3962714B2 - Manufacturing method of ceramic electronic component - Google Patents

Description

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

  Conventionally, for the production of ceramic electronic components such as multilayer ceramic capacitors, a plurality of layers of ceramic dielectric powder constituting the dielectric layer and layers of internal electrode paste constituting the internal electrode layer are alternately stacked. A method is employed in which an external electrode is provided after the laminated body is formed and fired.

  Here, the dielectric layer is formed by mixing a ceramic dielectric powder, an organic binder, an organic solvent, etc. into a slurry by mixing it into a sheet by a method such as a doctor blade method and drying it appropriately. Ceramic compacts are used. The internal electrode paste used for forming the internal electrode layer is a paste obtained by dispersing a metal powder such as nickel in an organic binder and an organic solvent. In the above-described laminate, the internal electrode paste is usually screen-printed on the surface of the sheet-like ceramic molded body, the organic solvent contained in the internal electrode paste is dried, and then a plurality of the molded bodies are stacked and pressed. Is produced.

  This laminate is made into chips and fired to form ceramic elements. And an external electrode is provided in the end surface from which the internal electrode layer is exposed among the end surfaces of this ceramic element. For the formation of the external electrode, an external electrode paste is used in which a metal powder such as copper is dispersed in a binder, a solvent, or the like to form a paste. That is, after applying this external electrode paste to the end face of the ceramic element, firing the ceramic element coated with the external electrode paste and sintering the metal powder in the external electrode paste, a porous sintered body An external electrode is formed. Such external electrodes are disclosed, for example, in Patent Documents 1 to 5 listed below.

JP-A-5-275272 JP-A-8-306580 JP 2002-198253 A JP-A-7-335477 Japanese Patent Laid-Open No. 10-144559

  However, the above-described conventional ceramic electronic components have the following problems. That is, in the step of firing the ceramic element coated with the external electrode paste to form the external electrode, the external electrode pastes of the ceramic elements that are close to each other in the firing apparatus come into contact with each other, and the external electrode pastes firmly There was a case of fusing. When firing is performed in such a state, a plurality of ceramic electronic components are fused in the external electrode portion. In this case, since the ceramic electronic components are firmly bonded, it is very difficult to separate the ceramic electronic components into individual ceramic electronic components. There was a problem of detachment from the ceramic element. Therefore, if the ceramic electronic components are fused together when firing the external electrodes, the yield will be reduced.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for manufacturing a ceramic electronic component capable of significantly suppressing fusion between external electrodes during firing of the external electrodes. To do.

Method of manufacturing ceramic electronic components according to the present invention includes a first metal powder having a first particle size range is 0.3 to 1.0 [mu] m, which of 5.0~11.0μm and 30~50μm After the external electrode paste having the metal powder containing the second metal powder having the second particle size range is applied to the end face of the ceramic element, the arithmetic average roughness of the surface is 0 on the surface of the ceramic element. The ceramic element is fired so that an external electrode of .76 μm or more is formed.

The inventors have newly found that the fusion between the external electrodes is significantly suppressed when the arithmetic average roughness of the surface of the external electrode is set to 0.76 μm or more using the above manufacturing method. Specific examples of a method that preferably exhibits the above-described action include the following methods. That is, the first particle size range is Ri 0.3~1.0μm der, second particle size range is a method that is one either of 5.0~11.0μm and 30 to 50 [mu] m. Further, the metal powder may include a third metal powder having a third particle size range different from the first particle size range and the second particle size range. In that case, it is preferable that the 3rd particle size range is 30-50 micrometers. The third particle size range may be 20-30 μm.

  The arithmetic average roughness of the surface of the external electrode is preferably 0.95 μm or more. In this case, fusion between the external electrodes is further suppressed.

  In addition, the arithmetic average roughness of the surface of the external electrode is preferably 3 μm or less. In this case, the ceramic electronic component can be easily mounted on a substrate or the like.

The main component of the metal powder is preferably Cu. In this case, the external electrode has high conductivity.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the ceramic electronic component which can suppress significantly the fusion | melting of the external electrodes at the time of baking of an external electrode is provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments that are considered to be best for carrying out a ceramic electronic component according to the invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected about the same or equivalent element, and the description is abbreviate | omitted when description overlaps.

  FIG. 1 is a schematic cross-sectional view of a ceramic capacitor according to an embodiment of the present invention. As shown in FIG. 1, a ceramic capacitor 10 which is a kind of ceramic electronic component is arranged in two layers, an outermost layer 2 of a surface layer 11 and about 300 dielectric layers 12 sandwiched between the surface layer 11. In addition, a hexahedral capacitor body (ceramic element) 16 having internal electrode layers 14 interposed between the dielectric layers 12 is provided. That is, the capacitor body 16 has a laminated structure of about 600 layers, and the dielectric layers 12 and the internal electrode layers 14 are alternately laminated. Further, of the end faces of the capacitor body 16, a pair of end faces 16 a and 16 b that extend in the thickness direction of the capacitor body 16 and face each other so as to cover the entire area of the end faces 16 a and 16 b. External electrodes 18 and 18 are provided.

  Further, the internal electrode layers 14 arranged above and below are electrically insulated from each other by the dielectric layer 12 and are connected to one external electrode 18 different from each other. Therefore, when a predetermined voltage is applied between the pair of external electrodes 18, 18, electric charges are stored between the internal electrode layers 14 opposed vertically. The capacitance of the ceramic capacitor 10 is proportional to the size of the opposing areas of the internal electrode layers 14 that are opposed vertically.

Both the surface layer 11 and the dielectric layer 12 are layers mainly composed of BaTiO _3. The thickness of each surface layer 11 is approximately 50 μm, and the thickness of each dielectric layer 12 is approximately 1 to 4 μm. The surface layer 11 and the dielectric layer 12 are formed by firing a later-described green sheet (ceramic molded body). The internal electrode layer 14 is a metal layer containing Ni as a main component and has a thickness of about 1 μm. Each external electrode 18 is a porous body mainly composed of Cu having high conductivity among metals, and the arithmetic average roughness of the surface 18a is about 1 μm.

  Hereinafter, a method for manufacturing the above-described ceramic capacitor 10 will be described with reference to FIGS. Here, FIG. 2 is a partially enlarged view showing a printing pattern of a green sheet, and FIG. 3 is a view showing a procedure for producing a ceramic capacitor.

In producing the ceramic capacitor 10, as shown in FIG. 2, a BaTiO ₃ -based dielectric green sheet 20 is first prepared. The green sheet 20 is obtained by forming a dielectric paste obtained by mixing BaTiO ₃ powder and an organic binder into a slurry by a doctor blade method. Further, two green sheets 21 that are thicker than the green sheet 20 and become the surface layer 11 are prepared.

  Then, a predetermined pattern of the internal electrode paste 22 is applied to the surface 20a of the green sheet 20 by a screen printing method and dried. That is, the internal electrode paste 22 is applied to a region other than the edge region of the three sides in the rectangular region 24 corresponding to one capacitor on the green sheet surface 20a (see FIG. 2). The internal electrode paste 22 is a paste obtained by dispersing nickel powder in an organic binder and an organic solvent. Known organic binders can be used, such as cellulose resins, epoxy resins, aryl resins, acrylic resins, phenol-formaldehyde resins, unsaturated polyester resins, polycarbonate resins, polyamide resins, polyimide resins, alkyd resins, A binder such as rosin ester can be used. Moreover, a well-known thing can be utilized also for an organic solvent, For example, solvents, such as a butyl carbitol, a butyl carbitol acetate, a turpentine oil, (alpha) -TV neol, an ethyl cellosolve, and a butyl phthalate, can be used.

In addition, BaTiO ₃ powder is added to the internal electrode paste 22 as a co-material. BaTiO ₃ powder for the main component BaTiO ₃ dielectric layer 12 (and the green sheet 20) is the same, the addition of BaTiO ₃ powder to the internal electrode paste 22, and the internal electrode paste 22 and green sheet 20 The difference between the shrinkage ratio and the sintering start temperature is significantly reduced.

  Then, the green sheet 20 coated with the internal electrode paste 22 as described above is laminated on the green sheet 21 with the internal electrode paste 22 facing upward (see FIG. 3A). Further, about 300 green sheets 20 produced by the same manufacturing method are sequentially laminated so that the positions of the internal electrode pastes 22 are alternately changed (see FIG. 3B). Then, an uncoated green sheet 21 is placed on the stacked green sheets 20 and pressed from the stacking direction so that the adjacent green sheets 21, the green sheets 20, and the internal electrode paste 22 are pressed against each other. In this way, a laminate 26 in which the green sheets 20 and the internal electrode paste 22 are alternately laminated is produced.

  And this laminated body 26 is cut | disconnected for every rectangular area | region 24 corresponding to one capacitor | condenser (refer FIG.3 (c)). Thereafter, by firing the chip-formed laminate 26 at, for example, about 1200 ° C., the green sheet 21, the green sheet 20, and the internal electrode paste 22 become the surface layer 11, the dielectric layer 12, and the internal electrode layer 14, respectively. The laminated body 26 becomes a capacitor body 16 in which the dielectric layers 12 and the internal electrode layers 14 are alternately laminated. Further, the capacitor body 16 is processed in a barrel containing water and a polishing medium to perform surface polishing. This surface polishing may be performed at the stage of the laminated body 26.

  Finally, the external electrode 18 is formed so as to cover the pair of end faces 16a and 16b extending in the stacking direction and facing each other among the end faces of the capacitor body 16, and the ceramic capacitor 10 is completed (FIG. 3 ( d)). Hereinafter, a method for forming the external electrode 18 will be specifically described.

  First, a conductive paste for external electrodes (external electrode paste) containing a first Cu powder having an average particle diameter of less than 15 μm, a second Cu powder having an average particle diameter of about 15 to 100 μm, and an organic binder. Prepare. Then, this external electrode paste is applied to the end faces 16 a and 16 b of the capacitor body 16. Thereafter, the capacitor body 16 to which the external electrode paste is applied is subjected to heat treatment at about 800 ° C. in a neutral atmosphere or a reducing atmosphere to sinter the first and second Cu powders described above, so that the external electrode 18 is sintered. Form. The surface 18a of the external electrode 18 may be subjected to a barrel plating process or the like as necessary.

  The ceramic capacitor 10 manufactured as described above will be described.

  As described above, the arithmetic average roughness (Ra) of the surface 18a of the external electrode 18 of the ceramic capacitor 10 is about 1 μm, which is larger than 0.76 μm. When the arithmetic average roughness of the external electrode surface 18a is equal to or greater than this value (0.76 μm), the inventors have fused the external electrodes 18 of the adjacent ceramic capacitors 10 when firing the external electrodes 18. It was found to be significantly suppressed. That is, by forming the external electrode 18 of the ceramic capacitor 10 so that the surface roughness is 0.76 μm or more, the external electrode 18 is fused to form the external electrode 18 by baking the external electrode paste. Significantly suppressed. Here, as a method of adjusting the surface roughness of the external electrode 18 to 0.76 μm or more, there is a method of adjusting the average particle diameter of the Cu powder added to the external electrode paste.

  The arithmetic average roughness of the surface of the external electrode 18 is more preferably 0.95 μm or more from the viewpoint that the fusion between the electrodes is further improved. Further, from the viewpoint of facilitating mounting of the ceramic capacitor 10 on a mounting substrate or the like, the arithmetic average roughness of the external electrode surface 18a is preferably 3 μm or less.

  Hereinafter, the contents of the present invention will be specifically described with reference to examples.

  First, the external electrode paste used in Example 1 will be described. The external electrode paste used in this example is a 60:40 weight ratio of a first Cu powder having a particle size range of 0.3 to 1.0 μm and a second Cu powder of 5.0 to 11.0 μm. The Cu powder, the Ni powder, the organic binder, the dispersant, the organic solvent, and the like mixed in the above are mixed and dispersed in a ball mill or a roll mill to make a paste. And the external electrode of the ceramic capacitor was formed using this external electrode paste. That is, Cu powder was sintered at about 800 ° C. in a neutral atmosphere or a reducing atmosphere to form an external electrode, and a ceramic capacitor as a sample was obtained. And about this sample, it was 0.76 micrometer when the surface roughness (Ra) of the external electrode was measured with the stylus type surface roughness shape measuring device.

  In addition, seven kinds of samples were prepared in total by changing the particle size range of Cu powder added to the external electrode paste and the mixing ratio of Cu powder having different particle size ranges (see FIG. 4).

  Here, the “Example 2” sample was replaced with the Cu powder used in the “Example 1” sample, the first Cu powder having a particle size range of 0.3 to 1.0 μm, and 5.0 to 11. This sample employs a Cu powder obtained by mixing a second Cu powder of 0 μm and a third Cu powder having a particle size range of 20 to 30 μm in a weight ratio of 52:35:13. In the “Example 3” sample, instead of the Cu powder used in the “Example 1” sample, the first Cu powder having a particle size range of 0.3 to 1.0 μm and 5.0 to 11.0 μm This sample employs Cu powder obtained by mixing the second Cu powder and the third Cu powder having a particle size range of 30 to 50 μm in a weight ratio of 52:35:13, respectively. In the “Example 4” sample, instead of the Cu powder used in the “Example 1” sample, the first Cu powder having a particle size range of 0.3 to 1.0 μm and 5.0 to 11.0 μm This sample employs Cu powder obtained by mixing the second Cu powder and the third Cu powder having a particle size range of 30 to 50 μm in a weight ratio of 17:63:20, respectively. The “Example 5” sample has a first Cu powder having a particle size range of 0.3 to 1.0 μm and a particle size range of 30 to 50 μm instead of the Cu powder used in the “Example 1” sample. This sample employs Cu powder mixed with the second Cu powder having a weight ratio of 20:80. The arithmetic average roughness of the external electrode surfaces of the “Example 2” sample, the “Example 3” sample, the “Example 4” sample, and the “Example 5” sample were 0.95 μm, 1.04 μm, 1.16 μm and 1.65 μm.

  For comparison, as the “Comparative Example 1” sample, instead of the Cu powder used in the “Example 1” sample, the first Cu powder having a particle size range of 0.3 to 1.0 μm and 1 A sample employing Cu powder prepared by mixing 0.02-3.0 μm second Cu powder at a weight ratio of 60:40 was prepared. Similarly, a Cu powder in which a first Cu powder having a particle size range of 0.3 to 1.0 μm and a second Cu powder of 3.0 to 5.0 μm are mixed at a weight ratio of 60:40 is adopted. The “Comparative Example 2” sample was prepared. The arithmetic average roughness of the surface of the external electrode of the “Comparative Example 1” sample and the “Comparative Example 2” sample was 0.23 μm and 0.38 μm, respectively.

  With respect to the seven samples prepared as described above, it was measured whether or not the external electrodes were fused to each other during firing of the external electrode paste. Specifically, a plurality of samples (for example, 100) are prepared, and the number of occurrences of poor fusion is counted. If the number is 1% or less of the total, excellent (“◯”), When it was 1 to 5%, it was judged as good (“Δ”), and when it was 5% or more, it was judged as bad (“x”). As a result, almost no fusion between the external electrodes was found for the samples of Examples 1 to 5 in which the arithmetic average roughness of the electrode surface was 0.76 μm or more. On the other hand, for the samples of Comparative Example 1 and Comparative Example 2 in which the arithmetic average roughness of the electrode surface was less than 0.76 μm, a number of poor fusions between the external electrodes were found.

  The present invention is not limited to the above embodiment, and various modifications are possible. For example, the main component of the external electrode is not limited to Cu, but may be Ni, Sn, or the like. The ceramic electronic component is not limited to a ceramic capacitor, and may be various electronic components such as a piezoelectric chip component and a chip varistor component.

It is a schematic sectional drawing of the ceramic capacitor which concerns on embodiment of this invention. It is the elements on larger scale which showed the printing pattern of the green sheet. It is the figure which showed the procedure which produces a ceramic capacitor. It is the table | surface which showed the experimental result which concerns on the Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Ceramic capacitor, 11 ... Surface layer, 12 ... Dielectric layer, 14 ... Internal electrode layer, 16 ... Capacitor body, 18 ... External electrode, 18a ... External electrode surface, 20, 21 ... Green sheet, 20a ... Surface, 22 ... electrode paste, 26 ... laminate.

Claims (8)

Metal comprising a first metal powder having a first particle size range is 0.3 to 1.0 [mu] m, and a second metal powder having a second particle size range is 5.0~11.0μm After applying the external electrode paste having a powder to the end face of the ceramic element, the ceramic element is fired so that an external electrode having a surface arithmetic average roughness of 0.76 μm or more is formed on the surface of the ceramic element. Manufacturing method of ceramic electronic components. External having a metal powder comprising a first metal powder having a first particle size range of 0.3-1.0 μm and a second metal powder having a second particle size range of 30-50 μm An electrode paste is applied to an end face of a ceramic element, and then the ceramic element is fired so that an external electrode having a surface arithmetic average roughness of 0.76 μm or more is formed on the surface of the ceramic element. Production method. The ceramic electronic component according to claim 1 or 2 , wherein the metal powder includes a third metal powder having a third particle size range different from the first particle size range and the second particle size range. Manufacturing method. It said third particle size range is 30 to 50 [mu] m, a manufacturing method of a ceramic electronic component according to claim 3. It said third particle size range is 20 to 30 [mu] m, a manufacturing method of a ceramic electronic component according to claim 3. The arithmetic average roughness of the surface of the external electrode is 0. Is 95μm or more, a manufacturing method of a ceramic electronic component according to any one of claims 1-5. Said external arithmetic average roughness of the surface of the electrode is 3μm or less, the production method of a ceramic electronic component according to any one of claims 1-6. Wherein a main component Cu metal powder, a manufacturing method of a ceramic electronic component according to any one of claims 1-7.

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