JP2841655B2 - Green sheet for multilayer ceramic capacitor and method for manufacturing multilayer ceramic capacitor using the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated ceramic capacitor green sheet used for radios, microcassette recorders, electronic tuners, and the like, and a method for manufacturing a laminated ceramic capacitor using the same. .

2. Description of the Related Art Conventionally, a method of manufacturing a laminated ceramic capacitor is based on a method in which a slurry composed of a dielectric powder, a binder, a plasticizer, and an organic solvent is used by a doctor blade method, etc. Make a green sheet. Next, after stacking a plurality of sheets on which the internal electrodes are printed on this sheet, a laminated molded body is produced by pressure bonding,
Thereafter, it was common to cut and sinter into chips, and then form external electrodes to manufacture.

In addition, the demand for a multilayer ceramic capacitor having a smaller size and a larger capacity has recently become stronger, and for that purpose, it is indispensable to increase the number of layers and to make the dielectric layer thinner. However, as the dielectric layers become thinner, it is almost impossible from a handling point of view to separate and laminate the dielectric layers formed on the organic film one by one from the organic film as in the past. Become. Therefore, after the electrodes are printed and provided on the organic film as the base film so as to have a desired electrode arrangement, a dielectric layer composed of a dielectric powder, a binder, and a plasticizer is further formed so as to cover the electrodes. Get a green sheet,
A thermal transfer method has been proposed in which a dielectric layer and electrodes on a base film are transferred to and stacked on an object by thermocompression bonding from the base film side of the green sheet (Japanese Patent Application Laid-Open No. 1-226130). When laminated by this method, even if the dielectric layer is so thin that the peeling of the dielectric layer from the base film is impossible by handling, the dielectric layer and the electrode can be heat-pressed integrally with the base film as a support, Since the base film is peeled off after transferring the layer and the electrode to the object, handling becomes extremely easy.

Problems to be Solved by the Invention However, in the conventional green sheet, when the dielectric layer and the electrode are laminated by the heat transfer method, since the type of the binder used for forming the dielectric layer is a single component of butyral resin, When the laminated molded body using this sheet is fired, when the thermal decomposition temperature of the binder resin is reached, the thermal decomposition and gasification of the binder rapidly progresses, and a phenomenon of delamination between the dielectric layer and the electrode occurs. As a result, there is a problem that the production yield is remarkably reduced.

When performing heat transfer, it is desirable to lower the transfer temperature as much as possible to prevent deformation of the base film due to heat.However, in the conventional sheet of butyral resin single component, the softening point of butyral resin is as high as 130 to 150 ° C. There is a limit to the reduction of the transfer temperature, and for example, it is difficult to perform heat transfer at a deformation temperature of the polyester base film of 120 ° C. or less. Therefore, when heat transfer is performed at 120 ° C. or more, the polyester base film thermally shrinks, the positional accuracy of the electrodes is deteriorated, and the production yield is significantly reduced, which is a serious problem in practical use.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to reduce the transfer temperature by the thermal transfer method, prevent the occurrence of delamination, and improve the production yield.

Means for Solving the Problems In order to achieve the above object, the present invention comprises a base film, and a dielectric layer which is heated and transferred onto the base film, wherein the dielectric layer comprises a dielectric powder, a ketone resin and Any one or both of the carboxylate resin and a binder made of butyral resin, and made of a plasticizer, and after providing an electrode on the dielectric layer or between the base film and the dielectric layer, the dielectric layer is Lamination is performed by heat transfer from the opposite base film surface side.

According to the present invention, since the binder in the dielectric layer is made of a ketone resin having a low softening point or at least one of a carboxylate-based resin, the dielectric layer and the electrode are heated and transferred to an object to be transferred. The transfer temperature can be lowered, and the occurrence of delamination in the firing process of the laminated ceramic capacitor can be prevented, so that the production yield can be significantly improved.

Examples Hereinafter, examples of the present invention will be described.

First, a binder is blended with 100 parts by weight of a dielectric powder containing BaTiO ₃ as a main component so as to have a composition ratio as shown in Table 1 below. For comparison with the present invention, a butyral resin single component as a conventional composition was also prepared in a blending amount as shown in Table 1. Further, after blending 5 parts by weight of benzyl butyl phthalate as a plasticizer, the mixture is kneaded for 20 hours in a ball mill using -n-butyl acetate as a solvent to prepare a slurry.

Next, a commercially available Pd was placed on a 50 μm thick polyester film.
The electrode paste is printed in a predetermined shape by a screen printing method, and then dried to provide electrodes. This electrode was covered, and a dielectric layer having a thickness of 20 μm was formed on the polyester film by the reverse roll method using the above slurry to prepare a green sheet for a laminated ceramic capacitor. Next, the green sheet is laminated by a thermal transfer method at a temperature of 60 to 180 ° C. and a pressure of 50 kg / cm ² by a hot press from the side of the base film on which the dielectric layer and the electrode of the green sheet are not formed. A laminated molded body composed of several hundred layers was produced. Table 2 shows the results of the transferability of the green sheet at each hot pressing temperature.

As is clear from Table 2, the transfer temperature of the green sheet for the laminated ceramic capacitor of this embodiment (Sample Nos. 1 to 3) was significantly lower than that of the conventional green sheet (Sample No. 4). ing. This is because the softening point of the butyral resin varies considerably depending on the degree of butyralization and the degree of polymerization of the butyral resin.
Although the temperature is relatively high at 50 ° C., the softening points of the ketone resin and the phenolic resin used in this example are 80 to 80, respectively.
This is because 90 ° C and 75 to 85 ° C are considerably lower than the softening point of butyral resin. Therefore, when a butyral resin and a composite binder obtained by mixing one or both of a ketone resin and a carboxylate resin are used as in this embodiment, the binder having a low softening point is softened even if the thermal transfer temperature is greatly reduced. Heat transfer can be performed. That is, transfer can be performed at a deformation temperature of the polyester film of 120 ° C. or less, deformation of the polyester film due to heat shrinkage can be suppressed, the electrode accuracy of the laminated ceramic capacitor can be increased, and the production yield can be remarkably improved.

Next, the laminated molded article of the present example (sample Nos. 1 to 3: hot press temperature of 100 ° C.) and the laminated molded article of the conventional example (hot press temperature of 150 ° C.)
C.) into a chip shape and sintering at 1300 ° C. for 2 hours while sprinkling the chip compact into ZrO ₂ powder. The heating rate was 200 ° C / Hr.
Hold for hours. As a result of observing the microstructure inside the sintered body of the capacitor manufactured in this manner with an optical microscope, the conventional green sheet (sample N
In the case of using the green sheets of this example (samples Nos. 1 to 3), all samples were de-laminated, although 30% of the delamination occurred when o.4) was used. No lamination was observed.

FIG. 1 shows the green sheet (sample No.
3) shows the results of thermogravimetric analysis of a chip compact obtained by cutting a laminated compact produced using the conventional green sheet into chips. The solid line shows the change in weight of the molded body with respect to the temperature change in the present example, and the broken line shows the change in temperature in the conventional example. In the conventional example, a very large weight loss occurs at 300 to 400 ° C, that is, the thermal decomposition and gasification of the binder are rapidly progressing.
In this embodiment, the weight loss starts gradually from about 100 ° C., and does not show a sharp change as in the conventional example. Therefore, in the capacitor manufactured using the conventional green sheet, since the resin used at the time of removing the binder is a single component, thermal decomposition proceeds at once within a narrow temperature range, and rapid progress of gasification occurs. As a result, separation occurs between the internal electrode and the dielectric layer. On the other hand, in this embodiment, a butyral resin and a composite binder obtained by mixing one or both of a ketone resin and a carboxylate-based resin are used.
Gasification gradually progresses stepwise, and the occurrence of delamination can be suppressed.

The use of butyral resin in the present embodiment is that, among the thermoplastic resins, butyral resin is soluble in the n-butyl acetate solvent used when producing the green sheet and has good workability. Because. Further, the reason why ketone resin or carboxylate resin is selected is that, in addition to having a lower softening point than butyral resin, the workability is excellent even when a solvent is used. Further, in the present invention, the amount of the resin used for the binder is not limited, but when the total amount of the ketone resin and the carboxylate resin is larger than the amount of the butyral resin, the transferability during the heat transfer is improved. It is known to improve.

Effect of the Invention As described above, the green sheet for a laminated ceramic capacitor according to the present invention comprises a butyral resin as a binder contained in the dielectric layer, which is a ketone resin having a softening point lower than that of the butyral resin, or one or both of them. The use of a composite binder containing a mixture of the above makes it possible to lower the transfer temperature by the thermal transfer method. Further, since the thermal decomposition temperatures of the above resins are different from each other, the thermal decomposition and gasification of the binder gradually occur during firing in the laminated ceramic capacitor of the present invention, and no delamination occurs inside the manufactured sintered body. . Therefore, when a multilayer ceramic capacitor is manufactured using the green sheet for a multilayer ceramic capacitor of the present invention, the manufacturing yield is greatly improved.

[Brief description of the drawings]

 FIG. 1 is a diagram showing a change in thermogravimetry of a laminated molded product.

──────────────────────────────────────────────────の Continued on front page (72) Inventor Masahiro Kato 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Within the company (72) Inventor Satoshi Osan 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Field surveyed (Int.Cl. ⁶ , DB name) H01G 4/12

Claims (2)

(57) [Claims] 1. A base film, and a dielectric layer for heat transfer provided on the base film, wherein the dielectric layer comprises a dielectric powder, one or both of a ketone resin and a carboxylate resin. And a binder made of butyral resin and a plasticizer. 2. The laminated ceramic capacitor green sheet according to claim 1, wherein an electrode is provided on the dielectric layer or between the base film and the dielectric layer. A method for manufacturing a laminated ceramic capacitor, comprising laminating by heat transfer.