JP2006013315A - Ceramic electronic component manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic electronic component manufacturing method whereby a ceramic electronic component having compact external electrodes formed on both end faces of its ceramic element is manufactured. <P>SOLUTION: One end face of a ceramic element 12 is immersed in a conductive paste 22 spread on a bed 20 for the application of the conductive paste 22. The ceramic element 12 is then placed in a drying atmosphere to dry the conductive paste 22. The ceramic element 12 is then reversed and again immersed in the conductive paste 22 for the application of the conductive paste 22. The ceramic element 12 is placed in a drying atmosphere for the conductive paste 22 to dry. After the conductive paste 22 on both side faces of the ceramic element 12 is dried, the ceramic element 12 is placed in a drying atmosphere for further drying the conductive paste 22. The dried conductive paste 22 is baked for the formation of external electrodes on both end faces of the ceramic element 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a ceramic electronic component, and more particularly to a method for manufacturing a ceramic electronic component for obtaining a ceramic electronic component in which external electrodes are formed on both end surfaces of a ceramic body such as a multilayer ceramic capacitor.

  For example, a multilayer ceramic capacitor includes a ceramic body having a plurality of internal electrodes that are stacked to face each other. Adjacent internal electrodes are alternately drawn on both end faces of the ceramic body. External electrodes are formed on both end faces of the ceramic body from which the internal electrodes are drawn. Thereby, adjacent internal electrodes are alternately connected to the two external electrodes, and a capacitance is formed between these external electrodes.

  In order to produce a multilayer ceramic capacitor, a ceramic body 1 having internal electrodes is prepared as shown in FIG. The ceramic body 1 is formed by laminating and firing ceramic green sheets having internal electrode patterns formed of a conductive paste. In order to form external electrodes on both end faces of the ceramic body 1, the conductive paste 3 is spread on the base 2. The conductive paste 3 is applied to one end surface of the ceramic body 1 by immersing one end surface of the ceramic body 1 in the conductive paste 3. Further, as shown in FIG. 7, the conductive paste 3 is applied to the other end surface of the ceramic body 1 by immersing the other end surface of the ceramic body 1 in the conductive paste 3. Then, these conductive pastes 3 are baked to form external electrodes. Furthermore, a Ni plating film, a Sn plating film, or the like is formed on the external electrode obtained by firing, if necessary. In the manufacturing process of such a multilayer ceramic capacitor, the conductive paste 3 can be simultaneously applied to many ceramic bodies 1 by holding many ceramic bodies 1 using a jig (for example, patents). Reference 1).

JP-A-5-136010

  After immersing one end face of the ceramic element body in the conductive paste, it is necessary to reverse the ceramic element body in order to immerse the other end face of the ceramic element element in the conductive paste. However, when the ceramic body is reversed, in order to prevent deformation of the conductive paste, it is necessary to dry the conductive paste applied to one end surface of the ceramic body and reduce the fluidity. Furthermore, after applying the conductive paste to the other end of the ceramic body, it is necessary to dry the conductive paste again in order to prevent the conductive paste from being deformed when transported to the baking process of the conductive paste. is there.

  As described above, there are two drying processes between the application of the conductive paste to the ceramic body and the baking process. In these drying processes, the ceramic paste is applied to one end surface of the ceramic body. In contrast, the conductive paste has undergone two drying steps, whereas the conductive paste applied to the other end face of the ceramic body has undergone only one drying step. Therefore, a difference occurs in the dry state (solvent content) of the conductive paste on both end faces of the ceramic body. Thus, if the conductive paste applied to both end faces of the ceramic body is different in drying state, for example, if the sintering conditions are set based on the conductive paste applied first, the conductive paste applied later is Sintering is insufficient. Conversely, if the sintering conditions are set based on the conductive paste applied later, the conductive paste applied first will be oversintered and pores will be generated in the external electrodes.

  In such a state, when a plating film is formed on the sintered electrode, the plating solution penetrates and remains in the external electrode, and the plating solution remaining when the ceramic electronic component is soldered expands and the external electrode May cause defects such as cracks. Further, if the external electrode is insufficiently dense, the moisture resistance is inferior and moisture may enter.

  Therefore, a main object of the present invention is to provide a method of manufacturing a ceramic electronic component that can obtain a ceramic electronic component in which dense external electrodes are formed on both end faces of the ceramic body.

The present invention includes a step of preparing a ceramic body, a step of applying a conductive paste to one end surface of the ceramic body, and a ceramic body placed on one end surface of the ceramic body under dry conditions. A step of drying the conductive paste, a step of applying the conductive paste to the other end face of the ceramic body, and a conductive paste applied to the other end face of the ceramic body under a dry condition. The step of drying and the step of placing the ceramic body again under drying conditions to bring the dried state of the conductive paste applied to one end face of the ceramic body closer to the dried state of the conductive paste applied to the other end face And a process for firing a conductive paste.
The present invention also includes a step of preparing a ceramic body, a step of applying a conductive paste to one end face of the ceramic body, and placing the ceramic body under dry conditions on one end face of the ceramic body. The step of drying the applied conductive paste, the step of applying the conductive paste to the other end face of the ceramic body, and the ceramic body was applied to the other end face of the ceramic body under dry conditions. The ceramic body is placed under a drying condition in which drying is promoted more than a drying condition of the step of drying the conductive paste and the step of drying the conductive paste applied to one end surface of the ceramic body. The process of approximating the dry state of the conductive paste applied to one end face of the electrode and the dry state of the conductive paste applied to the other end face, and firing the conductive paste And a that step is a method for producing a ceramic electronic component.
In such a method of manufacturing a ceramic electronic component, the drying condition that promotes drying is higher than the drying condition in the step of drying the conductive paste applied to one end face of the ceramic body. This can be achieved by increasing the drying temperature or extending the drying time as compared with the step of drying the applied conductive paste.

By applying a conductive paste on one end face of the ceramic body and drying it, and further applying a conductive paste on the other end face and drying it, the ceramic body is placed again in a dry atmosphere, and then the ceramic body is placed in a dry atmosphere. The dry state of the conductive paste applied to both end faces of the element body can be approximated.
In addition, by placing a ceramic body coated with a conductive paste on the other end surface under conditions that facilitate drying compared to the drying conditions when a conductive paste is coated on one end surface of the ceramic body, The dry state of the conductive paste applied to both end faces of the body can be approximated.
By drying the conductive paste applied to both end faces of the ceramic body under such drying conditions, the dry state of the conductive paste applied to both end faces of the ceramic body can be approximated. Therefore, when the conductive paste is baked to form the external electrodes, dense external electrodes can be formed on both end faces of the ceramic body.
For example, the drying temperature may be increased in order to improve the drying conditions when the conductive paste is applied to the ceramic body later than the drying conditions when the conductive paste is applied to the ceramic body first. However, the drying time may be lengthened.

  According to the present invention, the dry state of the conductive paste on both end faces of the ceramic body can be made closer, so that it is possible to prevent the occurrence of defects in the ceramic electronic component due to an imbalance in the denseness of the external electrodes.

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

  FIG. 1 is a perspective view showing a multilayer ceramic capacitor as an example of a ceramic electronic component manufactured by the manufacturing method of the present invention. The multilayer ceramic capacitor 10 includes a ceramic body 12. As shown in FIG. 2, the ceramic body 12 has a configuration in which a plurality of dielectric ceramic layers 14 and internal electrodes 16 are alternately stacked. Adjacent internal electrodes 16 are alternately drawn to opposing end surfaces of the ceramic body 12. External electrodes 18 are formed on the end surfaces of the ceramic body 12 from which the internal electrodes 16 are drawn. Adjacent internal electrodes 16 are alternately connected to these external electrodes 18, and a capacitance is formed between the two external electrodes 18.

  In order to obtain the ceramic body 12, a ceramic green sheet is formed using a ceramic slurry whose main component is a dielectric material. A plurality of internal electrode patterns are printed on the ceramic green sheet using a conductive paste. A plurality of ceramic green sheets on which internal electrode patterns are formed are stacked, and further, ceramic green sheets on which no internal electrode patterns are formed are stacked above and below them. Then, the multilayer body is cut into a predetermined size, and the obtained multilayer chip is fired to form the ceramic body 12.

  One end face of the ceramic body 12 thus manufactured is immersed in a conductive paste 22 spread on the table 20 as shown in FIG. Here, as the conductive paste 22, a paste composed of metal powder such as copper powder, glass frit, resin, solvent or the like is used. By immersing the ceramic body 12 in such a conductive paste 22, the conductive paste 22 is applied to one end surface of the ceramic body 12. FIG. 3 shows one ceramic body 12, but when actually manufacturing the multilayer ceramic capacitor 10, a large number of ceramic bodies 12 are held by a jig or the like, and these ceramic bodies 12 are shown. The element body 12 is simultaneously immersed in the conductive paste 22.

  The ceramic body 12 to which the conductive paste 22 is applied is passed through a fluidized drying furnace that moves in a drying furnace using a moving medium such as a conveyor, and the conductive paste 22 is dried. After that, as shown in FIG. 4, the ceramic body 12 is reversed and the other end surface of the ceramic body 12 is immersed in the conductive paste 22. The ceramic body 12 is passed through a fluidized drying furnace, and the conductive paste 22 applied to the other end surface of the ceramic body 12 is dried.

  After the conductive paste 22 applied to the other end surface of the ceramic body 12 was dried, the ceramic body 12 was placed in an oven and applied to one end surface and the other end surface of the ceramic body 12. The conductive paste 22 is dried again. Thereafter, the conductive paste 22 is fired, and external electrodes 18 are formed on both end faces of the ceramic body 12. Furthermore, if necessary, a Ni plating film, a Sn plating film, or the like is formed on the external electrode 18 to form the multilayer ceramic capacitor 10.

  In the oven, the ceramic body 12 is moved by vibrating the container on which the ceramic body 12 is placed in order to dry the conductive paste 22 on one end face and the other end face to an extent that approximates the dry state. May be. Further, by circulating the atmosphere in the oven to make the temperature in the oven uniform, a dry state that more closely approximates the conductive paste 22 applied to one end face and the other end face of the ceramic body 12 and Can be dried. Further, when a plurality of containers on which the ceramic body 12 is placed in an oven, the containers are applied to one end surface and the other end surface of the ceramic body 12 by moving the containers clockwise or counterclockwise in the oven. The conductive paste 22 can be dried to a more approximate dry state.

  In this multilayer ceramic capacitor 10, since the conductive paste 22 is applied to the ceramic body 12 and then passed through the fluidized drying furnace, the conductive paste 22 applied to one end surface of the ceramic body 12 is The conductive paste 22 that has been dried twice and applied to the other end face of the ceramic body 12 is dried once. Therefore, a difference occurs in the dry state of these conductive pastes 22, but the dry state (solvent content) of these conductive pastes 22 can be brought closer by drying the conductive paste 22 again with an oven.

  Moreover, instead of drying again the conductive paste 22 applied to one end surface and the other end surface of the ceramic body 12 by the oven as described above, the conductive material applied to one end surface of the ceramic body 12. By performing the drying condition for drying the conductive paste 22 applied to the other end face of the ceramic body 12 under the condition that the dry state promotes more than the drying condition for drying the conductive paste 22, the ceramic body 12. It is possible to approximate the dry state of the conductive paste 22 applied to one end face and the other end face. The conditions that promote the drying state are drying conditions such as the drying time and the drying temperature, and the ceramic body is more than when the conductive paste 22 applied to one end face of the ceramic body 12 is dried. The conductive paste 22 applied to the other end surface of the ceramic body 12 is dried by increasing the drying time when the conductive paste 22 is dried, or by increasing the drying temperature. The dry state of the conductive paste 22 can be approximated.

  Thus, by approximating the dry state of the conductive paste 22 on both end faces of the ceramic body 12, the sintering conditions of the conductive paste 22 become equal, and the conductive paste 22 can be sintered under the optimum conditions. The coating strength of the external electrode 18 is increased, defects such as peeling of the external electrode are reduced, and moisture resistance can be improved. Therefore, it is possible to approximate the denseness of the external electrode 18 obtained and the bonding property with the internal electrode 16, and to prevent the plating solution or moisture from entering the external electrode 18. This external electrode forming method is applicable not only to the multilayer ceramic capacitor but also to forming external electrodes on both end faces of all chip-type ceramic electronic components.

  A ceramic body for a multilayer ceramic capacitor was prepared. One end face where the internal electrode of the ceramic body was exposed was immersed in a conductive paste, and the conductive paste was applied. This ceramic body was passed through a fluidized drying oven, and the conductive paste was dried at a temperature of 150 ° C. for 10 minutes. Next, the other end face where the internal electrode of the ceramic body was exposed was immersed in a conductive paste, and the conductive paste was applied. This ceramic body was passed through a fluidized drying oven, and the conductive paste was dried at a temperature of 150 ° C. for 10 minutes.

  When the ceramic body was put in a fixed oven and dried again and when it was not dried, the bondability between the internal electrode and the external electrode after the external electrode was baked was investigated. In the oven drying, the bonding property was investigated by changing the drying temperature and the drying time. In order to investigate the bondability, the conductive paste was dried, and external electrodes were baked and plated. And about the obtained multilayer ceramic capacitor, the dispersion | variation in an electrostatic capacitance and the minimum value of Q value were investigated, and also the number of defects which generate | occur | produced in the moisture-proof load test was investigated. Here, the variation in capacitance and the minimum value of Q were performed for 30 samples, and the number of defective moisture load resistance was performed for 100 samples. The results of this investigation are shown in Table 1.

  As can be seen from Sample No. 1 in Table 1, those that were not dried by the oven had large variations in capacitance, and the minimum Q value was small, and defective products were recognized in the moisture resistance load test. It was. When this multilayer ceramic capacitor was polished in cross section and the sintered state of the external electrode was confirmed, pores were generated on the surface of the external electrode or in the external electrode, and cracks thought to have occurred due to the ingress of moisture occurred. It was confirmed that As can be seen from Sample No. 2 and Sample No. 3 in Table 1, even when the drying temperature is 50 ° C., the variation in capacitance is large and the minimum Q value is small. Defective products were also recognized.

  On the other hand, as can be seen from Sample No. 4 to Sample No. 9, when the drying temperature is 100 ° C. or higher, the variation in capacitance is small, the minimum Q value is large, and defective products in the moisture resistance load test are recognized. I couldn't. Thus, by drying again the ceramic body from which the conductive paste has been dried in a fluidized drying oven at 100 ° C. or higher, the external electrode can be made dense, and the bondability between the internal electrode and the external electrode is also improved. Can be improved.

  A ceramic body of 1608 chip size and a conductive paste were prepared. The conductive paste consists of 70% copper powder (spherical powder + flat powder), 3% glass frit, 7% acrylic resin, and 20% solvent (turbineol + turpentine oil mixture). It will be.

  The conductive paste was spread on a table, and one end face of the ceramic body was immersed in the conductive paste and dried by a hot air circulation method. As shown in FIG. 5, the drying temperature profile was raised to 200 ° C. at 50 ° C./min, held at 200 ° C. for 3 minutes, and then lowered at 50 ° C./min. Next, the other end face of the ceramic body was immersed in a conductive paste, and the conductive paste was dried with a drying temperature profile shown in FIG. Therefore, the conductive paste on one side of the ceramic body has undergone two drying steps, and the conductive paste on the other side of the ceramic body has undergone one drying step.

  When the solvent content of the conductive paste on both end faces of this ceramic body was examined, the content of the conductive paste on one side of the ceramic body was 3% by mass, and the conductive paste on the other side of the ceramic body was Then, the content was 5.3% by mass.

  Further, after applying the conductive paste to one end face of the ceramic body, the conductive paste was dried with a drying temperature profile shown in FIG. Furthermore, after applying the conductive paste to the other end face of the ceramic body, the conductive paste was dried with the keeping time at 200 ° C. of the drying profile shown in FIG. 5 as 10 minutes. Therefore, the conductive paste on one side of the ceramic body has undergone two drying steps, and the conductive paste on the other side of the ceramic body has undergone one drying step, but the conductive paste is first applied. The drying time when the conductive paste is applied later is longer than the drying time when the conductive paste is applied.

  When the content of the solvent in the conductive paste thus dried was examined, the content of the conductive paste on one side of the ceramic body was 0.5% by mass, and the content on the other side of the ceramic body was The content of the functional paste was 0.6% by mass. Thus, by increasing the drying time when the conductive paste is applied later than the drying time when the conductive paste is first applied, the solvent content of the conductive paste on both end faces of the ceramic body is reduced. It was possible to make it uniform.

It is a perspective view which shows the multilayer ceramic capacitor as an example of the ceramic electronic component manufactured by the manufacturing method of this invention. FIG. 2 is an illustrative view showing the inside of the multilayer ceramic capacitor shown in FIG. 1. FIG. 2 is an illustrative view showing a step of applying a conductive paste to one end face of a ceramic body in order to produce the multilayer ceramic capacitor shown in FIG. 1. FIG. 4 is an illustrative view showing a step of applying a conductive paste to the other end face of the ceramic body shown in FIG. 3. It is a figure which shows the drying temperature profile of the drying process in Example 2. FIG. It is an illustration figure which shows the process of apply | coating an electrically conductive paste to one end surface of a ceramic element | base_body in order to produce the conventional ceramic electronic component. FIG. 7 is an illustrative view showing a step of applying a conductive paste to the other end face of the ceramic body shown in FIG. 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Multilayer ceramic capacitor 12 Ceramic body 14 Dielectric ceramic layer 16 Internal electrode 18 External electrode 20 units 22 Conductive paste

Claims (3)

Preparing a ceramic body,
Applying a conductive paste to one end face of the ceramic body;
Drying the conductive paste applied to one end surface of the ceramic body by placing the ceramic body under dry conditions;
Applying a conductive paste to the other end face of the ceramic body;
Drying the conductive paste applied to the other end face of the ceramic body under dry conditions of the ceramic body;
Placing the ceramic body again under dry conditions to bring the dry state of the conductive paste applied to one end face of the ceramic body close to the dry state of the conductive paste applied to the other end face; And a method for producing a ceramic electronic component, comprising firing the conductive paste. Preparing a ceramic body,
Applying a conductive paste to one end face of the ceramic body;
Drying the conductive paste applied to one end surface of the ceramic body by placing the ceramic body under dry conditions;
Applying a conductive paste to the other end face of the ceramic body;
Drying the conductive paste applied to the other end surface of the ceramic body by placing the ceramic body under dry conditions;
The ceramic body is placed on one end surface of the ceramic body by placing the ceramic body under a drying condition that promotes drying rather than a drying condition of the step of drying the conductive paste applied to one end face of the ceramic body. A method of manufacturing a ceramic electronic component, comprising: approximating a dry state of the applied conductive paste and a dry state of the conductive paste applied to the other end surface; and firing the conductive paste.   The drying condition that the drying is accelerated than the drying condition of the step of drying the conductive paste applied to one end surface of the ceramic body is the conductive paste applied to one end surface of the ceramic body. The method for producing a ceramic electronic component according to claim 2, wherein the drying temperature is increased or the drying time is made longer than the drying step.

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