JPS6231483B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved method of manufacturing a multilayer ceramic capacitor. Conventionally, multilayer porcelain capacitors have mainly been produced using the doctor blade method, spray method, or
A dielectric layer 1 with a thickness of approximately 25 μm was formed by a printing method, and palladium or palladium-based internal electrodes 3 were further formed by a printing method so as to have an electrode margin 2 of approximately 0.3 mm on both sides, and these were laminated alternately. After that, it is fired, and then the external terminal electrodes 4 are baked. Furthermore, as shown in FIG. 2, a structure in which the internal electrode 3 does not have electrode margins 2 on both sides has also been tried and studied. However, the former has electrode margins 2 on both side surfaces, which limits the capacitance that can be obtained per unit volume, and also has the drawback that the capacitance varies due to pattern misalignment, bleeding, etc. during printing of internal electrodes. In the latter case, there is no misalignment of the internal electrode pattern, and therefore the capacitance accuracy is good, but the dielectric layer is thin, about 25μ thick, and when cutting both sides, the inner electrode is partially surrounded by the side dielectric. As a result, short circuits or edge discharges occur between opposing electrodes on both sides, resulting in poor reliability as a capacitor. The present invention improves the above-mentioned drawbacks and provides a method for manufacturing a multilayer ceramic capacitor that has a large acquired capacitance per unit volume, small variations in capacitance, and is highly reliable. That is, after dielectrics and internal electrodes are alternately laminated and fired, external terminal electrodes are applied to the exposed portions of the internal electrodes facing each other on the fired body, and fired, and then the fired body is laminated in multiple layers at right angles to the external terminal electrodes. In the process of cutting the laminated chip elements into pieces to obtain laminated chip elements, the laminated chip elements are arranged in a plate or rod shape so that both cut side parts are exposed to the outside, and are fixed with wax, resin, etc. This method chemically dissolves and removes a portion of the internal electrode and external terminal electrode to form an internal electrode margin on both side surfaces, and insulates the side surface as necessary to further improve reliability. It is characterized by being coated with synthetic glass or insulating resin. The present invention will be described below with reference to embodiments shown in FIGS. 3 to 7. As shown in FIG. 5, palladium electrode paste is screen printed on the entire surface of one side of the dielectric sheet 5 obtained by the doctor blade method except for one end to provide internal electrodes 6, and then the dielectric sheet 5 is alternately A predetermined number of sheets are stacked on top of each other and integrated by heat-pressing. Next, the dielectric sheet 5 is heated at a predetermined temperature.
Then, as shown in FIG. 6, silver-palladium electrodes are coated and baked to form external terminal electrodes 7. Thereafter, the laminated chip elements were cut into multiple pieces with a diamond cutter in the a-a' direction at right angles to the external terminal electrodes 7, and then arranged with both sides up and down as shown in FIG.
Fix it in a rod shape with Micro Crystal Wax 8. Next, the wax 8 adhering to both sides of the laminated chip element was removed by polishing with a flat lapping machine, and then immersed in the dilute acid solution shown in the table for 5 minutes, 10 minutes, 15 minutes, and 30 minutes, and washed with water. After thorough cleaning, the wax was finally removed by washing with triclon ethylene to obtain the multilayer ceramic capacitor shown in FIG.
Furthermore, in order to improve the reliability of the capacitor, a paste made of lead borosilicate glass powder was applied thinly to both side surfaces 9 of the multilayer ceramic capacitor shown in Fig. 3, and then heat treated at 600°C to remove the lead borosilicate glass powder. was melted to coat both side surfaces to obtain a multilayer ceramic capacitor shown in FIG. In FIG. 4, numeral 10 indicates lead borosilicate glass as a covering material. The internal electrode margin 11 formed by melting the internal electrode from the side surface of the laminated congonser element varies depending on the concentration of the solution, temperature, and immersion time, and the result is as shown in FIG. The degree of electrode margin can be set by the immersion time or solution concentration.

[Table] In the above example, the wax on both sides of the laminated chip element was completely removed and then immersed in a dilute acid solution. If the electrode is washed with a solvent such as chlorethylene and then immersed in a dilute acid solution, the solution will not become contaminated, leading to improved dissolving power and sustainability of the dissolving power of the internal electrode. Furthermore, in the above example, the dielectric sheet was produced by the doctor blade method, and the laminate was obtained by thermocompression bonding, but the laminate may be obtained by other methods such as screen printing or spraying. In addition, the internal electrodes are not limited to those provided on the entire surface of one side except for one end, but may be arranged in multiple rows, and the same applies when palladium silver other than palladium is used as the material. Similar effects can be obtained with , sulfuric acid or iron chloride solutions. In addition to borosilicate lead glass, the materials used to cover both sides of the laminated chip element include low-melting glass insulating materials with a temperature below 800°C, which is the baking temperature for external terminal electrodes, and organic insulating resins such as epoxy, phenol, and polyester. The same applies to the invention, and all of the above do not deviate from the spirit of the present invention. By the method of the present invention described above, it is possible to reduce the side electrode margin, obtain a large capacitance per unit volume, and obtain a small and large capacitor. Capacity variations due to internal electrode pattern misalignment, bleeding, etc. are reduced. Capacitance can be adjusted, improving capacitance yield during manufacturing. It has many effects such as the ability to obtain a highly reliable multilayer ceramic capacitor, and is useful industrially and practically.

[Brief explanation of the drawing]

FIGS. 1 and 2 are perspective views of main parts of a conventional multilayer ceramic capacitor, FIG. 3 is an embodiment of the multilayer ceramic capacitor of the present invention, and FIG. 4 is a cross-sectional view of a multilayer ceramic capacitor of the present invention. Other embodiments are shown in which A is a cutaway perspective view of essential parts of a multilayer ceramic capacitor, B is a sectional view taken along b-c of A, and FIGS. 5, 6, and 7 are multilayer ceramic capacitors of the present invention. FIG. 8 is a perspective view showing an example of the manufacturing process, and FIG. 8 is a correlation diagram between the type of dilute acid solution, concentration, immersion time, and internal electrode dissolution depth. 2, 11: internal electrode margin, 3, 6... internal electrode, 4, 7... external terminal electrode, 5... dielectric sheet,
9... Side part, 10... Lead borosilicate glass.

Claims (1)

[Claims] 1. After alternately laminating dielectrics and internal electrodes and firing them, external terminal electrodes are coated and baked on the exposed parts of the internal electrodes facing each other in the fired body, and the external terminal electrodes are formed almost at right angles to the external terminal electrodes. In the step of cutting the fired body to expose the internal electrodes to obtain a laminated chip element, the laminated chip elements are arranged in a plate or rod shape so that the cut internal electrodes are exposed to the outside, and wax, resin, etc. While the internal electrodes are fixed in place, a part of the internal electrodes is chemically dissolved and removed along both side surfaces to form internal electrode margins on both side surfaces, wax, resin, etc. are removed, and individual laminated porcelains are formed. A method for manufacturing a multilayer ceramic capacitor, characterized in that the capacitor is obtained. 2. The method of manufacturing a multilayer ceramic capacitor according to claim 1, characterized in that both side surfaces of the multilayer chip element on which internal electrode margins are formed are coated with insulating glass or insulating resin.