JPS6386414A - Laminated ceramic capacitor - Google Patents

Abstract

(57) [Abstract] 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 multilayer ceramic capacitor in which a ceramic and an external electrode are simultaneously fired.

(Prior Art) A conventional multilayer ceramic capacitor obtained by simultaneously firing a ceramic and an external electrode is manufactured according to the following manufacturing procedure.

First, a conductive paste containing conductive particles such as Cu is printed on the main surface of a plurality of long unfired dielectric ceramic sheets to form a plurality of conductive layers for internal electrodes. The sheets were stacked one on top of the other, shifted in the longitudinal direction every other time, and then crimped, and then cut at a position where the conductive layer of the shifted sheet was exposed to the cut surface, and at a location where the conductive Ti layer of the unshifted sheet was exposed to the cut surface. Create a chip piece as a capacitor body. Next, a conductive paste is applied to the end face of the chip piece where the conductive layer is exposed and the peripheral edge connected thereto to form a conductive layer for an external electrode, and then heated in a reducing atmosphere at a temperature of 900 to 1200°C. The electrodes of the ceramic body are fired at the same time. The outer electrode of the multilayer ceramic capacitor thus obtained is electrically connected to the inner electrode at the end face, and is directly in close contact with the end face and the peripheral edge of the capacitor element connected thereto.

(Problems to be solved by the invention) Figures 3 and 4 produced by the manufacturing procedure described above
When the multilayer ceramic capacitor shown in the figure is soldered to a printed circuit board, etc., cracks C appear in the ceramic b around the external electrode a formed at the peripheral edge of the capacitor body during a later temperature shock test. Insulation resistance value is 103MΩ
There was a problem that the following occurred. Furthermore, the fourth
In the figure, d is an internal electrode.

An object of the present invention is to provide a multilayer ceramic capacitor that can solve these conventional problems.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a capacitor body formed by laminating and press-bonding a plurality of unfired ceramic sheets on which conductive layers for internal electrodes are formed. In a multilayer ceramic capacitor formed by forming a conductive layer for an external electrode on a surface and a peripheral edge portion connected thereto and then firing it, the above ceramic and the conductive layer for an external electrode are provided between the peripheral edge portion of the ceramic body and the conductive layer for an external electrode. It is characterized by the presence of an intermediate layer consisting of ceramic and conductive particles of the same composition.

(Function) Because the shrinkage caused by firing the unfired ceramic and ramic and the shrinkage caused by the firing of the conductive layer for the external electrode are different, the shrinkage caused by the firing of the external electrode conductive layer formed on the peripheral edge of the capacitor body after firing is different. Distortion remains in the ceramic at the periphery. However, if an intermediate layer consisting of a ceramic having the same composition as the ceramic and conductive particles is interposed between the peripheral edge of the capacitor body and the external electrode, the contraction m of the intermediate layer will be reduced by the shrinkage rate of the ceramic. Since it is between the shrinkage m of the external electrode and the shrinkage m of the external electrode, the strain occurring in the ceramic becomes small. Thus, no cracks occur in the ceramic at the periphery of the external electrode during a temperature shock test or the like after the capacitor of the present invention is soldered to a printed circuit board or the like.

(Example) Embodiments of the present invention will be described with reference to the accompanying drawings.

Example 1 A plurality of unfired dielectric ceramic sheets having a thickness of 381 LI11 and containing BaTtO3 as a main component were prepared.

In addition, a conductive paste for internal electrodes was prepared by kneading 100 g of old powder with a purity of 99.9%, 15 g of ethyl cellulose, and butyl calpitol 941J, and a conductive paste with a purity of 99.9%.
% Ni powder, 50 g of unfired ceramic powder with the same composition as the ceramic sheet, and 20 g of ethyl cellulose.
An intermediate layer paste prepared by kneading and butyl calpitol 941J, and 99.9% pure Ni powder ioo
g and ethyl cellulose 20 (+ and butyl calpitol 9
An external electrode paste prepared by kneading 4CI and 4CI was prepared.

Using the above-mentioned unfired ceramic sheet and conductive paste for internal electrodes, an unfired capacitor body is created according to a conventional method, and one end of the internal electrode contained in the capacitor body is connected to the exposed end face. After applying the intermediate layer paste in a band shape to the peripheral edge and drying it at 150°C, apply the external electrode paste continuously on the intermediate layer and the end face of the capacitor body, and after drying, apply N2 A multilayer ceramic capacitor was produced by firing at 1180° C. for 2 hours in an N2 gas atmosphere containing 2%. A nickel plating film was formed on the external electrodes of these capacitors using a commercially available electroless nickel plating bath.

1 and 2 show a multilayer ceramic capacitor according to one embodiment of the present invention.

In the same figure, (1) is a capacitor body having internal electrodes laminated through ceramic layers and exposed on alternately opposing end faces, and (3) is a capacitor body (1) that is connected to the end faces. A band-shaped intermediate layer formed on the peripheral edge, (
4) is an external electrode continuously formed on the intermediate layer (3) and the end face.

This multilayer ceramic capacitor was soldered onto a glass epoxy wiring board, and the capacitance (C) and dielectric loss tangent ( tan δ) and insulation resistance (IR) were measured. Then, hold at -55°C for 30 minutes, move to +125°C within 2 seconds and hold for 30 minutes.1. ,
After conducting the thermal shock test 100 times, the capacitance ffi (C), dielectric loss tangent (tan δ), and insulation resistance (
The table below shows the maximum rate of change in capacitance, the maximum value of tan δ, the number of insulation resistances of 103 MΩ or less, and the number of cracks found visually.

Example 2 Old powder 50 in Example 1 was used as a paste for the intermediate layer.
It was produced in the same manner and under the same conditions as in Example 1 except that 50 g of unfired ceramic powder having the same composition as 35 CI ceramic was used instead of 650 g.

The measurement results are shown in the table below.

Example 3 Old powder 50 in Example 1 was used as a paste for the intermediate layer.
It was prepared in the same manner and under the same conditions as in Example 1, except that 80 g was used instead of 50 g of unfired ceramic powder having the same composition as the 20 (l) ceramic powder. The measurement results are shown in the table below.

Example 4 Created by the same method and under the same conditions as Example 1, except that Cu powder was used instead of N1 powder in Example 1 as the conductive particles of the internal electrode paste, intermediate layer paste, and external electrode paste. did. The measurement results are shown in the table below.

Comparative Example A comparative example was prepared in the same manner and under the same conditions as in Example 1, except that the intermediate layer was omitted.

table n -1000@ In addition, AQ is used as the conductive particles of each of the pastes.

^Q-Pd etc. can be used similarly.

(Effects of the Invention) As explained above, according to the present invention, when soldering to a printed circuit board or performing a temperature shock test, etc.
This also has the effect that cracks are less likely to occur in the ceramic around the outer electrode at the peripheral edge of the capacitor body, and there is less deterioration of insulation resistance.

[Brief explanation of the drawing]

FIG. 1 is an enlarged perspective view of one embodiment of the present invention, FIG. 2 is a sectional view thereof, FIG. 3 is an enlarged perspective view of a conventional example, and FIG. 4 is a sectional view thereof. (1)... Capacitor body (ri... internal electrodes)
3)...Intermediate layer (4)...Outer electrode

Claims (1)

[Claims] A laminated layer formed by laminating and press-bonding a plurality of unfired ceramic sheets on which conductive layers for internal electrodes are formed, forming a conductive layer for external electrodes on both end faces of the capacitor body and the peripheral edges connected thereto, and then firing the sheets. A laminated type ceramic capacitor, characterized in that an intermediate layer consisting of a ceramic having the same composition as the ceramic and conductive particles is interposed between the peripheral edge of the ceramic body and the conductive layer for external electrode. ceramic capacitor.