Multilayer ceramic capacitor

#The present invention relates to a multilayer ceramic capacitor comprising a laminated body including internal electrodes and ceramic layers, and external electrodes disposed at end portions of the laminated body and connected to the internal electrodes; and, more particularly, to a multilayer ceramic capacitor comprising thin internal electrodes with thickness of less than or equal to 3 μm and being capable of preventing or reducing crack developments inside the laminated body during, e.g., sintering.

#A multilayer ceramic capacitor normally comprises a laminated body including ceramic layers made of a dielectric material and external electrodes, some of the ceramic layers having internal electrodes thereon. The ceramic layers are stacked together in a manner that the internal electrodes are alternately exposed at opposite sides of the laminated body. The external electrodes are disposed at the end portions including the opposite sides of the laminated body and are connected to respective sets of internal electrodes of the laminated body.

#FIG. 3 illustrates a typical arrangement of a laminated body 3 of such a multilayer ceramic capacitor. The laminated body 3 is formed by stacking ceramic layers 7 having internal electrodes 5 and 6 and made of a dielectric material, and a plurality of bare ceramic layers 7′ without any internal electrodes. The bare ceramic layers 7′ without any internal electrodes may be called dummy sheets. The ceramic layers 7 are stacked in a manner to have the internal electrodes 5 and 6 alternately exposed at opposite sides of the laminated body 3. A number of dummy sheets are disposed on top of the uppermost ceramic layer 7 as well as below the undermost ceramic layer 7. As shown in FIG. 1, a pair of external electrodes 2 are, respectively, disposed at the opposite end portions of the laminated body 3 and are connected to the internal electrodes 5 and 6.

#The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:

#FIG. 1 shows a partial cutaway perspective view of a typical multilayer ceramic capacitor including the inventive capacitor;

#FIG. 2 illustrates an expanded view of section A shown in FIG. 1;

#The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

#First, an amount of slurry is prepared by uniformly dispersing dielectric ceramic powder such as barium titanate into an organic binder dissolved in a solvent. The organic binder may be selected from the group consisting of abietic resin, polyvinyl butyral, ethyl cellulose, acrylic resin, and the like. The solvent may be selected from the group consisting of ethanol, terpineol, butyl carbitol, toluene, kerosene, and the like. The slurry is thinly and uniformly coated on a base film such as polyethylen terephthalate film of a predetermined thickness and then dried, to thereby form a ceramic green sheet. Thereafter, the ceramic green sheet is cut into a plurality of pieces of a predetermined size.

#Next, the conductive paste for the internal electrodes is obtained by mixing about 100 weight% of a conductive material, e.g., Ni powder, with about 3 to about 12 weight% of a binder, e.g., ethyl cellulose, and uniformly dispersing the mixture in about 80 to about 120 weight% of a solvent, e.g., terpineol. Also, an optional amount up to about 20 weight%, i.e., 0 to 20 weight%, of the dielectric ceramic powder, e.g., a barium-titanate may be included in the mixture. The weight percentages used herein are measured based on the total weight of the conductive material. The preferred composition of the mixture may vary with the thickness of the internal electrodes.