JP4548612B2 - Manufacturing method of multilayer ceramic electronic component - Google Patents

Description

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

  A multilayer ceramic capacitor, which is one of the multilayer ceramic electronic components, is composed of an inner layer portion and outer layer portions provided above and below the inner layer portion. The inner layer portion is a functional region as a capacitor, and has a ceramic substrate and a plurality of internal electrodes embedded therein. The outer layer portion is a protective region for protecting the functional region, and has a ceramic base.

  A multilayer ceramic capacitor is usually manufactured as follows. A ceramic green sheet is formed from a dielectric paste, and a conductor paste for forming an internal electrode is further applied to the inner layer portion. And what constitutes the inner layer portion is a laminate of ceramic green sheets coated with a conductive paste, and what constitutes the outer layer portion is a laminate of ceramic green sheets as they are, and is a green sheet laminate corresponding to the structure of the capacitor. make. And after pressing a green sheet laminated body, it cuts and obtains a some rectangular parallelepiped green chip from the green sheet laminated body. Then, the green chip is subjected to a polishing process for rounding corners or a baking process, and a terminal electrode is formed to obtain a multilayer ceramic capacitor (see Patent Document 1).

However, as in the multilayer ceramic capacitor described above, in the multilayer ceramic electronic component manufactured by firing after laminating ceramic green sheets and internal electrodes, burn unevenness according to the difference in shrinkage ratio in firing occurs, There is a problem that cracks occur in the vicinity of the boundary between the inner layer portion and the outer layer portion.
JP-A-9-129486

  The present invention has been made in view of the above-described problems, and is a method for manufacturing a multilayer ceramic electronic component that involves firing, and provides a method for manufacturing a multilayer ceramic electronic component that can reduce burn unevenness during firing. The purpose is to do.

  In order to solve the above-described problem, the present invention is such that at least one outer layer portion that is a protective region is laminated on an inner layer portion that is a functional region, and the inner layer portion includes an inner layer ceramic substrate and an inner layer conductive layer, The outer layer portion is a method of manufacturing a multilayer ceramic electronic component having an outer layer ceramic substrate, wherein a paste containing a first ceramic powder is prepared as a paste for forming the inner layer ceramic substrate; Preparing a paste containing a conductor powder and a second ceramic powder as a paste for forming an inner conductive layer; and a third ceramic powder and a second ceramic powder as a paste for forming the outer ceramic base. And a step of preparing a paste including the inner layer portion and the outer layer portion respectively formed by the paste. In a state where there, and performing a firing.

  Preferably, the first ceramic powder is used as the third ceramic powder.

  The particle size of the second ceramic powder is preferably smaller than the particle size of the first ceramic powder and the particle size of the third ceramic powder.

  According to the present invention described above, uneven burning during firing is reduced, and generation of cracks can be reduced.

  When the first ceramic powder is used as the third ceramic powder, manufacturing and management can be easily performed.

  When the particle size of the second ceramic powder is smaller than the particle size of the first ceramic powder and the particle size of the third ceramic powder, the difference in shrinkage between the inner layer portion and the outer layer portion may be further reduced. it can.

  The other features of the present invention and the operational effects thereof will be described in more detail with reference to the accompanying drawings.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which a method for producing a multilayer ceramic electronic component according to the present invention is implemented as a method for producing a multilayer ceramic capacitor will be described with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

  FIG. 1 is a cross-sectional view showing an example of a multilayer ceramic capacitor to which the manufacturing method according to the present embodiment is applied. In the illustrated multilayer ceramic capacitor 1, a plurality of internal electrodes (inner conductive layers) 5 and 7 are embedded in a ceramic base 3 made of ceramic. The ceramic substrate 3 is configured by laminating a plurality of ceramic green sheets as will be described later.

  The internal electrodes 5, 7 that are adjacent to each other in the vertical direction in the figure are arranged so that their positions are alternated, and face each other through a ceramic layer constituting the ceramic substrate 3. The number of layers of the internal electrodes 5 and 7 is determined according to the required capacitance.

  The ceramic substrate 3 is constituted by an inner layer portion 9 and outer layer portions 11 and 13. That is, the portion constituting the inner layer portion 9 is the inner layer ceramic substrate 3a, and the portions constituting the outer layer portions 11 and 13 are the outer layer ceramic substrate 3b. Strictly speaking, the internal electrodes 5 and 7 were embedded in the inner layer ceramic base 3 a of the ceramic base 3. A pair of upper and lower outer layer portions 11 and 13 are provided, that is, an upper outer layer portion 11 is laminated above the inner layer portion 9, and a lower outer layer portion 13 is laminated below the inner layer portion 9. The inner layer portion 9 is a functional region of a capacitor having a plurality of internal electrodes (inner layer conductive layers), and the outer layer portions 11 and 13 each function as a protection region.

  Terminal electrodes 15 and 17 as external electrodes are provided on the opposing side surfaces of the ceramic substrate 3. The internal electrode 5 is electrically connected to the terminal electrode 15, and the internal electrode 7 is electrically connected to the terminal electrode 17.

  Next, a method for manufacturing the multilayer ceramic capacitor according to the present embodiment will be described. The outline of the manufacturing method of the present invention is that a plurality of ceramic green sheets provided with internal electrodes 5 and 7 are laminated to form an inner layer portion 9, and a plurality of ceramic green sheets are laminated to form outer layer portions 11, 13 is fired in a state where the inner layer portion 9 and the outer layer portions 11 and 13 are laminated in a block shape.

  First, with reference to FIG. 2, formation of the sheet | seat which comprises the inner layer part 9 is demonstrated. As shown in FIG. 2, a ceramic green sheet 23 is formed on the upper surface of the flexible PET film 21. The ceramic green sheet 23 is formed by preparing a dielectric paste containing a first ceramic powder, a binder, a solvent, a plasticizer, and the like as needed as a paste for forming the inner layer ceramic substrate 3a. By applying to the top surface of 21 and drying. In applying the dielectric paste, for example, a doctor blade or an extrusion head can be used. The ceramic green sheet 23 finally becomes a ceramic layer constituting the inner layer ceramic substrate 3a.

  Subsequently, on the upper surface of the dried ceramic green sheet 23, a conductive powder containing a conductive powder, a second ceramic powder that is a co-material, a binder, a solvent, and the like as necessary is formed as a paste for forming the internal electrodes 5 and 7. Paste 25 is applied. The conductive paste 25 is disposed so as to be separated into a plurality of portions on the upper surface of the ceramic green sheet 23 corresponding to the shape and position of the internal electrodes 5 and 7 to be formed. Moreover, although the arrangement | positioning of the electrically conductive paste 25 can be performed by the screen printing method or the gravure printing method, for example, the screen printing method is shown in FIG.

  That is, printing is performed by moving the squeegee 29 in the direction of arrow F on the surface of the screen 27 and extruding the conductive paste 25 onto the surface of the ceramic green sheet 23. Further, the printed conductive paste is dried to obtain the internal electrodes 5 and 7.

  On the other hand, ceramic green sheets 11a and 13a (see FIG. 3) constituting the outer layer portions 11 and 13 are produced in a process different from the production of the ceramic green sheet 23 constituting the inner layer portion 9 described above. Also in the formation of the ceramic green sheets 11a and 13a constituting the outer layer portions 11 and 13, a dielectric paste is applied and dried to obtain a ceramic green sheet. The paste for forming the outer layer ceramic substrate 3b includes a third ceramic powder, a binder, a solvent, a plasticizer, and the like as necessary, and is used as a co-material for the paste for forming the internal electrodes 5 and 7. Further, the one containing the second ceramic powder is also used. In applying the dielectric paste, for example, a doctor blade or an extrusion head can be used. The ceramic green sheets 11a and 13a finally become ceramic layers constituting the outer ceramic base 3b.

  Then, the ceramic green sheets prepared in this way are laminated as shown in FIG. First, the ceramic green sheets 13a for the lower outer layer portion 13 having the required number of layers are sequentially stacked on the receiving base 31, and then the ceramic green sheets 23 for the inner layer portion 9 having the required number of layers are sequentially formed thereon. Laminate to. The number of ceramic green sheets to be used is determined by the required capacity value and may be several hundred layers in total. Further, ceramic green sheets 11 a for the upper outer layer portion 11 are sequentially laminated on the inner layer portion 9.

  In addition, there can exist various aspects in the lamination | stacking method of a ceramic green sheet. For example, the required number of layers of ceramic green sheets for the inner layer portion are laminated to form a ceramic green sheet laminate for the inner layer portion. On the other hand, the required number of ceramic green sheets for the outer layer portion are laminated, and then You may superimpose both. Alternatively, instead of dividing the inner layer portion and the outer layer portion, it is possible to form a ceramic green sheet laminate that has been dried several times at once, and then laminate them sequentially. Further, it is possible to repeat the formation, drying, and lamination for each ceramic green sheet.

  In stacking the ceramic green sheets 23 for the inner layer portion, in the two adjacent ceramic green sheets 23 for the inner layer portion, the internal electrodes 5 and 7 on one ceramic green sheet 23 are connected to the other ceramic green sheet 23. The layers are sequentially stacked so as to overlap a part of the internal electrodes 5 and 7 and the gap between the internal electrodes 5 and 7.

  Thereafter, the green sheet laminate is pressed and then cut to obtain a plurality of rectangular green chips from the green sheet laminate. Further, the binder removal treatment is performed on the green chip, and the binder component is burned out from the green chip, followed by firing to form the terminal electrodes 15 and 17, thereby obtaining the multilayer ceramic capacitor 1 shown in FIG. It is done.

  In a multilayer ceramic capacitor, the occurrence of cracks due to firing becomes a problem. Looking at the inner layer portion, the conductor powder itself included in the conductive paste is easier to burn than the ceramic powder included in the ceramic paste forming the ceramic green sheet. Therefore, as a general trend, it can be said that the internal electrode is more easily burned than the inner layer ceramic substrate.

  For this reason, in the present invention, the ceramic paste is also mixed with the conductive paste 25 to make it difficult to burn, and the internal electrodes 5 and 7 and the inner layer are formed so that the contraction ratio of the internal electrodes 5 and 7 is close to the contraction ratio of the inner layer ceramic substrate 3a. The generation of cracks with the ceramic substrate 3a is suppressed. The ceramic powder mixed in the conductive paste 25 in this way is the second ceramic powder as the above-mentioned common material.

  In the present embodiment, as a specific example, Ni powder is used as the conductor powder, and additive-coated barium titanate powder is used as the first ceramic powder. As the ceramic powder, barium titanate powder containing no additive is used. Moreover, the barium titanate powder which is the first ceramic powder is one having an average particle diameter of 0.5 μm, and the barium titanate powder which is the second ceramic powder is one having an average particle diameter of 0.1 μm, Ni powder, which is a conductor powder, has an average particle size of 0.5 μm.

  Furthermore, according to the experience of the present inventor, cracks due to firing have also occurred near the boundary between the inner layer portion and the outer layer portion. Therefore, the present inventor has further studied, and in the conductive paste, the ceramic powder contained as a co-material diffuses as it is fired, and flows into the ceramic paste forming the surrounding inner layer ceramic substrate. It can be considered that this causes a shift, and this causes a crack.

  In other words, the ceramic powder as a co-material having a particle size smaller than that of the original ceramic powder for forming the inner layer ceramic base flows into the paste for forming the inner layer ceramic base, so that the inner layer ceramic base is easier to burn than the original. Become. In other words, the common material that causes difficulty in burning in relation to the conductor powder provides ease of burning in the relationship with the ceramic powder of the inner layer ceramic substrate forming paste that is the diffusion destination. Due to such circumstances, there is a difference in burnability during firing between the outer layer ceramic base and the inner layer ceramic base, which contributes to the vicinity of the boundary between the inner layer portion and the outer layer portion. It is considered that cracks occur in the case.

  Therefore, in the present invention, in anticipation of the diffusion of the second ceramic powder, which is the co-material of the conductive paste 25, into the paste for forming the inner layer ceramic base 3a, the original first paste for forming the outer layer ceramic base 3b is used. In addition to the ceramic powder of 3, the second ceramic powder was mixed in advance. This takes into account the diffusion of the common material of the conductive paste 25 during firing, and brings the shrinkage ratio between the outer layer ceramic substrate and the inner layer ceramic substrate closer. Accordingly, uneven burning during firing is reduced, occurrence of cracks can be reduced near the boundary between the inner layer portion and the outer layer portion, and the strength of the body after firing can be improved.

  Although the contents of the present invention have been specifically described with reference to the preferred embodiments, various modifications can be made by those skilled in the art based on the basic technical idea and teachings of the present invention. It is self-explanatory.

  First, in the above-described embodiment, as the third ceramic powder constituting the paste for forming the outer layer ceramic base 3b, the first ceramic powder constituting the paste for forming the inner layer ceramic base 3a can be used. . That is, as a specific example, barium titanate powder having an average particle size of 0.5 μm is used as the first ceramic powder and the third ceramic powder. According to such an aspect, manufacture and management are facilitated, and design and control can be more reliably performed regarding the reduction ratio adjustment between the inner layer portion and the outer layer portion.

  Moreover, you may make it make the particle size of 2nd ceramic powder smaller than the particle size of each of 1st ceramic powder and 3rd ceramic powder. To give a specific example, as the second ceramic powder, barium titanate powder having an average particle diameter of 0.1 μm is used, and both the first ceramic powder and the third ceramic powder have an average particle diameter of 0.5 μm. Barium titanate powder is used. According to such an aspect, the shrinkage difference between the inner layer portion and the outer layer portion can be further reduced.

  In addition, in all the ceramic powder and conductor powder which have been mentioned above, the material and the particle size are merely examples, and the present invention is not limited thereto.

  Furthermore, the multilayer ceramic electronic component to which the present invention is applied is not limited to the multilayer ceramic capacitor. That is, for a structure in which a layer portion as a functional region having a conductive layer that functions as an electronic component and a layer portion as a protective region are laminated and fired in the laminated state. Can be widely applied. Therefore, it can also be applied to, for example, inductors, LC filters, array components, and the like. Further, the protective region (outer layer portion) does not necessarily mean that it does not include any layer made of a conductive material. In short, by firing in a laminated state, it can be widely applied to a laminated structure in which a difference in shrinkage substantially appears.

It is sectional drawing of the multilayer ceramic capacitor to which the manufacturing method which concerns on embodiment of this invention is applied. It is a figure explaining the formation aspect of the sheet | seat in this Embodiment. It is a figure explaining the lamination | stacking aspect of the sheet | seat in this Embodiment.

Explanation of symbols

1 Multilayer ceramic capacitor 5, 7 Internal electrode (inner conductive layer)
9 Inner layer part 11, 13 Outer layer part

Claims (3)

At least one outer layer portion that is a protective region is laminated on the inner layer portion that is a functional region, the inner layer portion has an inner layer ceramic base and an inner layer conductive layer, and the outer layer portion has an outer layer ceramic base. A method of manufacturing a multilayer ceramic electronic component, comprising:
As paste for forming the inner layer ceramic substrate comprising the steps of providing a paste powder component consists of a first ceramic powder,
As paste for forming the inner layer conductive layer, the steps of the powder component, prepared a conductor powder, a paste having an average particle diameter made of the average particle diameter is smaller than the second ceramic powder of the first ceramic powder,
As paste for forming the outer layer ceramic substrate, the powder component, to prepare a paste having an average particle diameter of the average particle diameter is larger than the third ceramic powder in the second ceramic powder and the second ceramic powder Steps,
And a step of firing in a state in which the inner layer portion and the outer layer portion respectively formed by the paste are laminated.   The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the first ceramic powder is used as the third ceramic powder.   The method for producing a multilayer ceramic electronic component according to claim 1, wherein the second ceramic powder does not contain an additive.

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