JP2016025287A - Method for manufacturing multilayer ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a multilayer ceramic electronic component, capable of preventing cracks of an element body generated by cubical expansion due to vaporization of water in a process for drying the element body of a multilayer ceramic capacitor after barrel polishing.SOLUTION: A method for manufacturing a multilayer ceramic electronic component includes the steps of: laminating a plurality of ceramic layers having a plurality of internal electrodes and forming a mother laminate; dividing a mother laminate into a plurality of element bodies and exposing the end surface of the internal electrodes; and putting element bodies, water solution and media balls in a pot of a barrel polishing machine, agitating them and barrel-polishing the end surface of the element bodies. The water solution contains carbohydrate as a main component.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing a multilayer ceramic electronic component including a step of polishing an element body, water, and media ball of a multilayer ceramic electronic component by putting them in a pot of a barrel polishing machine.

  In Patent Document 1, in order to barrel polish the end face of the multilayer ceramic capacitor after firing, there is a step of polishing the multilayer ceramic capacitor body, water, and media (SiC) balls in a barrel polishing machine pot for a certain period of time. A method of manufacturing the provided multilayer ceramic electronic component is described.

  In this barrel polishing machine pot polishing process, as shown in FIG. 6, moisture enters from the gap between the boundary between the internal electrode 52 and the ceramic layer 54 exposed on the end face 50 a of the element body 50. It remains inside the body 50.

  The element body 50 taken out from the pot after polishing is cleaned with an ultrasonic cleaner and then dried in a vacuum state in a vacuum dryer. At this time, since the inside of the vacuum dryer is in a depressurized state, moisture that has entered through the gap between the internal electrode 52 and the ceramic layer 54 of the element body 50 is vaporized by heating by the dryer and goes out of the element body 50. It is discharged and effective drying is performed.

Japanese Patent Laid-Open No. 10-163062

  However, when water vaporizes, the volume expands. Therefore, in the process of drying the multilayer ceramic capacitor body 50, cracks may occur in the body 50 due to volume expansion due to vaporization of water. This phenomenon occurs without change even under reduced pressure. Therefore, even with the technique of Patent Document 1, the cracks of the element body 50 caused by volume expansion due to water vaporization have been insufficient.

  Therefore, an object of the present invention is to produce a multilayer ceramic electronic component capable of preventing cracks in the element body caused by volume expansion due to vaporization of water in the step of drying the element body of the multilayer ceramic capacitor after barrel polishing. Is to provide a method.

The present invention
A step of laminating a plurality of ceramic layers provided with a plurality of internal electrodes to form a mother laminate;
Dividing the mother laminate into a plurality of element bodies and exposing internal electrodes on end faces of the element bodies;
A step of putting the base body, the aqueous solution, and the media ball into a pot of a barrel polishing machine and stirring, and barrel-polishing the end face of the base body,
The aqueous solution is an aqueous solution mainly composed of carbohydrates,
A method for producing a multilayer ceramic electronic component characterized by the above.

  In addition, the present invention is a method for manufacturing a multilayer ceramic electronic component, further comprising a step of applying an external electrode paste to the end face of the element body after barrel polishing and baking it.

  In the present invention, by using an aqueous solution containing carbohydrate as a main component, an aqueous solution having viscosity becomes difficult to enter into the minute gaps on the end face where the internal electrode of the multilayer ceramic capacitor body is exposed, and moisture intrusion occurs. It is suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the crack of the element | base_body which generate | occur | produces by the volume expansion by water vaporization can be prevented in the process of drying the element | base_body of the multilayer ceramic capacitor after barrel polishing.

  The above-described object, other objects, features, and advantages of the present invention will become more apparent from the following description of embodiments for carrying out the invention with reference to the drawings.

1 is an external perspective view showing an embodiment of a multilayer ceramic electronic component. It is A-A 'sectional drawing of FIG. It is a flowchart which shows one Embodiment of the manufacturing method of the multilayer ceramic electronic component which concerns on this invention. It is a perspective view which shows the state by which the ceramic green sheet in which the internal electrode was formed was laminated | stacked. It is a schematic diagram which shows the state in the pot of a barrel polisher. It is a schematic cross section for demonstrating the problem of the manufacturing method of the conventional multilayer ceramic electronic component.

1. Ceramic electronic component In the present embodiment, a multilayer ceramic capacitor will be described as an example of a ceramic electronic component, but it goes without saying that a ceramic electronic component such as a varistor may be used.

  FIG. 1 is an external perspective view showing a multilayer ceramic capacitor 1. FIG. 2 is a cross-sectional view taken along line A-A ′ of FIG. 1. The multilayer ceramic capacitor 1 includes a ceramic body 10 and external electrodes 20 and 22 formed on left and right ends of the ceramic body 10.

  The ceramic body 10 sandwiches the plurality of inner layer ceramic layers 11, the plurality of inner electrodes 12 and 13 disposed at the interfaces between the plurality of inner layer ceramic layers 11, and the plurality of inner layer ceramic layers 11. The outer ceramic layers 15a and 15b are arranged vertically. That is, the ceramic body 10 has a rectangular parallelepiped structure in which the ceramic layers 11, 15 a, 15 b and the internal electrodes 12, 13 are alternately stacked. The thickness of the inner layer ceramic layer 11 is preferably 0.3 to 10.0 μm.

  The internal electrode 12 and the internal electrode 13 are opposed to each other via the inner ceramic layer 11 in the thickness direction. Capacitance is effectively formed in a portion where the internal electrode 12 and the internal electrode 13 are opposed to each other with the inner ceramic layer 11 interposed therebetween.

  The lead portion of the internal electrode 12 is drawn to the left end face of the ceramic body 10 and is electrically connected to the external electrode 20. The lead portion of the internal electrode 13 is drawn to the right end surface of the ceramic body 10 and is electrically connected to the external electrode 22.

  The internal electrodes 12 and 13 are made of, for example, Ni, Cu, Ag, Pd, an Ag—Pd alloy, Au, or the like. The thickness of the internal electrodes 12 and 13 is preferably 0.3 to 2.0 μm.

  The external electrodes 20 and 22 include, for example, a base electrode made of Ni, Cu, Ag, Pd, an Ag—Pd alloy, Au, or the like, and a Ni plating layer and a Sn plating layer formed on the surface of the base electrode.

2. Manufacturing Method of Multilayer Ceramic Capacitor Next, a manufacturing method of the multilayer ceramic capacitor 1 will be described with reference to a flowchart shown in FIG.

(1) Production of ceramic green sheet In step S1, a ceramic slurry is formed on a PET (polyethylene terephthalate) film as a support material using a doctor blade method so that the thickness after drying is 2.5 μm. The ceramic green sheet for the inner layer and the ceramic green sheet for the outer layer are used.

(2) Formation of Internal Electrode Next, in step S2, the above-described conductive paste containing Ni as a main component is applied on the ceramic green sheet for inner layer by screen printing or the like, and the internal electrode 12 having a predetermined pattern, 13 is formed. The film thicknesses of the internal electrodes 12 and 13 are set so that the Ni thickness before firing is 0.5 to 1.0 μm.

(3) Lamination Next, in step S3, after the ceramic green sheet for inner layer and the ceramic green sheet for outer layer are peeled off from the PET film as the support material, the ceramic green sheet for outer layer is the ceramic layer for outer layer after firing. A predetermined number of layers are laminated so that the thickness of 15b becomes a predetermined thickness.

  Further, as shown in FIG. 4, the inner layer ceramic green sheets on which the internal electrodes 12, 13 are formed are sequentially laminated so that the internal electrodes 12, 13 are alternated. The present invention is effectively exhibited when the number of inner layer ceramic green sheets is 200 to 800. On top of that, a predetermined number of outer ceramic green sheets are laminated so that the thickness of the fired outer ceramic layer 15a becomes a predetermined thickness. In this way, a mother ceramic laminate is produced.

  Next, the mother ceramic laminate is placed in a predetermined mold and pressed in the stacking direction by means such as isostatic pressing.

(4) Division Next, in step S4, the mother ceramic laminate is pressed by a cutting blade or cut by a dicing saw to be cut into a predetermined product size, and the unfired ceramic body 10 is cut out. . In addition, although water is used in the case of cutting with a dicing saw, water is not used in the case of press cutting with a cutting blade, so that pressing with a cutting blade is preferable. The internal electrode 12 is exposed on one end face of the cut ceramic body 10, and the internal electrode 13 is exposed on the other end face.

(5) Firing Next, in step S5, the unfired ceramic body 10 is fired. The firing temperature is preferably 900 to 1300 ° C. Here, the internal electrodes 12 and 13 and the ceramic green sheets for inner layers and outer layers have different shrinkage ratios during firing, and a gap is generated between the internal electrodes 12 and 13 and the ceramic green sheets for inner layers and outer layers. Thus, the inner layer ceramic green sheet is the inner layer ceramic layer 11 and the outer layer ceramic green sheet is the outer layer ceramic layers 15a and 15b.

(6) Barrel Polishing Next, in step S6, the ceramic body 10 is exposed to the end surfaces of the ceramic body 10 by the barrel polishing machine, and the corners and ridges are rounded. Is done. That is, as shown in FIG. 5, barrel polishing is performed in a polishing tank 30 having a volume of about 1.5 L of a barrel polishing machine, polishing stone (alumina) 32 that is a media ball, and polishing powder (alumina powder). A predetermined amount of the ceramic body 10 is put together with an aqueous solution containing a carbohydrate as a main component (for example, an aqueous solution in which starch is typified by 0.01 g to 20 g of starch starch) in water, and polishing is performed.

  At this time, the carbohydrate in the aqueous solution closes the gap at the interface between the internal electrodes 12, 13 exposed on the end face of the ceramic body 10 and the inner ceramic layer 11, and moisture enters the ceramic body 10 from the gap. To prevent.

(7) Formation of External Electrode Next, in step S7, a conductive paste containing Cu as a main component is applied to both end faces of the fired ceramic body 10 and baked to form a base electrode. When the base electrode is baked, moisture hardly penetrates into the ceramic body 10, so that appearance defects such as cracking of the ceramic body 10 due to repelling water in the ceramic body 10 do not occur. Further, the Ni—Sn plating layer is formed on the surface of the base electrode by wet plating, and the external electrodes 20 and 22 are formed.

  In this way, the multilayer ceramic capacitor 1 is produced. As for the external dimensions of the multilayer ceramic capacitor 1 (including the external electrodes 20 and 22), the length L is 0.4 to 3.2 mm, the width W is 0.2 to 2.5 mm, and the height T is 0.2 to 2. .5 mm.

(Experimental example)
In the experimental example, each evaluation sample of the multilayer ceramic capacitor was produced under different conditions in the barrel polishing step, and an appearance defect acceleration test was performed.

(1) Production of Evaluation Sample As for the outer dimensions of the multilayer ceramic capacitor 1 of the evaluation sample, the length L is 3.2 mm, the width W is 2.5 mm, and the height T is 2.5 mm. The total number of internal electrodes 12 and 13 is 580 layers, and the thickness of the internal electrodes 12 and 13 is 6 μm. 1000 evaluation samples were produced.

(A) Example In the case of the example, in the barrel polishing step, the polishing tank 30 is subjected to a grinding stone (alumina) 32, which is a media ball, an abrasive powder (alumina powder), an aqueous solution containing carbohydrate as a main component (into starch) A predetermined amount of the ceramic body 10 was put together with a representative starch solution in water, and polishing was performed.

(B) Comparative Example In the comparative example, a predetermined amount of the ceramic body 10 is put in the polishing tank 30 together with the polishing stone (alumina) 32 and the polishing powder (alumina powder) which are media balls in the barrel polishing step. Polishing was performed. That is, an aqueous solution containing carbohydrate as a main component was not used.

(2) Evaluation method After the barrel polishing step, the ceramic body 10 is not taken out of the polishing tank 30 as it is, and left for 20 hours to accelerate the penetration of moisture into the ceramic body 10 (acceleration of appearance failure) Test). As for the appearance defect, it was visually confirmed whether or not the ceramic body 10 was cracked with the internal electrodes 12 and 13 exposed.

(3) Evaluation Results Table 1 shows the evaluation results of the multilayer ceramic capacitor 1.

  From Table 1, the appearance defect inhibitory effect was confirmed by using the aqueous solution which has a carbohydrate as a main component. In the case of the examples, the number of appearance defects was 0 and sufficient effects were obtained without performing moisture removal.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is carried out within the range of the summary.

DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor 10 Ceramic body 11 Ceramic layer for inner layers 12, 13 Internal electrode 15a, 15b Ceramic layer for outer layers 20, 22 External electrode

Claims (2)

A step of laminating a plurality of ceramic layers provided with a plurality of internal electrodes to form a mother laminate;
Dividing the mother laminate into a plurality of element bodies and exposing the internal electrodes on end faces of the element bodies;
Placing the element body, the aqueous solution, and the media ball in a pot of a barrel polishing machine and stirring, and barrel-polishing the end face of the element body,
The aqueous solution is an aqueous solution mainly composed of carbohydrates;
A method for producing a multilayer ceramic electronic component characterized by the above.   The method for manufacturing a multilayer ceramic electronic component according to claim 1, further comprising a step of applying and baking an external electrode paste on the end face of the element body after barrel polishing.