JPS59111319A - Method of producing laminated ceramic condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a high-strength multilayer ceramic capacitor that can be applied to fields where mechanical strength is required, particularly as a multilayer ceramic capacitor for automatic mounting.

Conventional Structure and Problems Multilayer ceramic capacitors having a parallel wiring structure of ceramic thin film dielectrics are well known for the purpose of achieving smaller size and larger capacity. The method for manufacturing this multilayer ceramic capacitor is generally as follows. First, several additives are added to oxides such as barium titanate and magnesium titanate and mixed, and then an organic binder is added to form a highly viscous slurry. A sheet with a thickness of 30 to 100 μm is produced by a general sheet molding method. Thereafter, a paste containing palladium or an alloy powder of platinum and palladium dispersed in an organic binder is screen printed onto the sheet. This process is repeated to produce a laminate of 2 to 40 layers. This laminate is cut into a suitable size and fired in an electric furnace at 1200 to 140Q°C to obtain sintered chips. As a terminal electrode on the end face of this chip,
A laminated ceramic capacitor is obtained by depositing a paste of silver and palladium alloy or silver powder and baking at 700 to 900°C.

In most cases, such multilayer ceramic capacitors are automatically mounted directly onto a printed circuit board. Printed wiring boards are made of engineered resin and tend to warp during use.
The soldered multilayer ceramic capacitor terminals have 1.
Tensile stress exceeding oKy is often applied, and the terminal electrodes cannot withstand this stress and may come off or cracks may occur in the element itself, causing problems in characteristics.

Purpose of the Invention The present invention has been made in view of the above-mentioned facts and as a result of repeated experiments, it has been found that it is possible to simultaneously improve the adhesive strength of terminal electrodes and the element strength, and that direct attachment to a printed circuit board can be achieved by automatic attachment. We were able to establish a manufacturing method for multilayer ceramic capacitors that solves these problems.

In other words, the method for manufacturing a multilayer ceramic capacitor of the present invention includes embedding a laminate in which ceramic dielectric layers and metal electrode layers are alternately stacked in a mixed powder of alumina and glass frit, and then subjecting the laminate to heat treatment. The method is characterized by comprising a step of diffusing the glass component into the inside of the laminate. In the multilayer ceramic capacitor obtained by the manufacturing method of the present invention, the glass component is diffused into the ceramic by heat treatment, so it is thought that the internal pores are strengthened by the glassy substance.

It is well known that silver paste used for terminal electrodes contains glass flint, but this silver paste has no affinity with elements based on the method of the present invention in which glass is diffused into the element body. It is thought that the adhesive strength will be high because of the good adhesive strength.

Description of examples Hereinafter, the present invention will be described in detail based on Examples.

Calcium titanate (Ca T 10 a −
) + niobium oxide (Nb2o5) respectively Q. Add 2 parts by weight and mix thoroughly. Thereafter, it is made into a slurry using an organic binder, and a sheet with a thickness of 80 μm is produced using a blade construction method. Palladium paste is screen printed on this sheet, and the sheets are stacked on top of it repeatedly. This laminate was cut and fired at 1300 to 1360°C. The shape of this sintered chip is 1.51+l+1
1 (width) xa, o body (length) x 0.65 depth (thickness).

Such sintered chips were mixed with 2 parts by weight of boron oxide.

After embedding a glass frit consisting of 5 parts by weight of silicon oxide and 1 part by weight of lead oxide in a mixture of 1 to 5 parts by weight added to 100 parts by weight of alumina powder, the mixture was heated to 800 to 850°C.
heat treated with

Silver electrodes were provided as terminal electrodes on the chip thus obtained. However, a mixture of 2 to 3 t/6 of the above glass frit in a silver paste for silver electrodes was used.

The figure shows a multilayer ceramic capacitor obtained by the manufacturing method of the present invention, in which 1 is a ceramic dielectric layer, 2 is a palladium electrode, 3 is a glass layer, and 4 is a silver electrode. The table below shows a comparison of the terminal electrode tensile strength, bending strength, and electrical properties of multilayer ceramic capacitors based on the conventional manufacturing method, that is, the method without glass diffusion, and the manufacturing method of the present invention. As is clear from this table, it is recognized that the mechanical strength of the multilayer ceramic capacitor obtained by the method of the present invention is significantly improved. Regarding the electrical characteristics of the capacitor, the capacitance is slightly
No abnormalities were observed except for J.

Effects of the Invention As mentioned above, the mechanical strength of the laminated ceramic condenser manufactured by the manufacturing method of the present invention is extremely excellent, and it can be soldered directly to a printed circuit board, and the terminal electrodes do not come off due to the deflection of the board. It is extremely effective in preventing cracks from occurring in the device and is of great significance.

In the examples, boron was used as the glass frit.

Silicon or lead oxides may be used, or oxides of zinc or aluminum may be used, and boron,
It is also possible to use a glass frit mainly composed of silicon or bismuth. In the examples, ceramic dielectrics made of barium titanate, calcium titanate, niobium oxide, and manganese dioxide were used, but any ceramic dielectric composition can be used. Furthermore, although silver was used as the terminal electrode in the embodiment, an alloy of silver and palladium may also be used.

[Brief explanation of the drawing]

The figure shows a multilayer ceramic capacitor based on the manufacturing method of the present invention. 1... Ceramic dielectric layer, 2... Metal electrode layer (palladium electrode), 3... Glass layer, 4... Silver electrode.

Claims (1)

[Claims] A process of embedding a laminate in which ceramic dielectric layers and metal electrode layers are alternately laminated in a mixed powder of alumina and glass frit, and then heat-treating the laminate to diffuse the glass component into the laminate. A method for manufacturing a multilayer ceramic capacitor, comprising: