JPS6262447B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small-sized, large-capacity ceramic capacitor and a method for manufacturing the same.

Recently, as electronic devices have become more complex, there has been a strong tendency for electronic circuits to become smaller and more dense, and capacitors are required to be extremely small and large in capacity due to the limits of permissible volume. It is an object of the present invention to provide a capacitor that is small, has a large capacity, and is stable in the surrounding environment, and a method for manufacturing the same, which can meet such demands.

In the capacitor of the present invention, a pair of electrodes sandwich a ceramic dielectric material in a spiral shape to form a columnar body, both end surfaces of the columnar body are covered with a glass insulator, and the columnar body excluding the both end surfaces is The pair of electrode ends are exposed on opposite sides of the body, and the other sides are covered with a dielectric material.

Examples of the present invention will be described below. FIG. 1 shows an embodiment of the ceramic capacitor of the present invention.
is a perspective view, and B and C are cross-sectional views of different cross sections. In these figures, 1 is a ceramic dielectric such as a titanate dielectric or a titanium oxide dielectric, and 2 and 3 are internal electrodes made of palladium or the like. 3 is spirally wound to form a flat columnar body, both end surfaces of which are coated with glass insulators 6, 7, and each tip 4, 5 of a pair of internal electrodes 2, 3 is connected to an opposite end of the flat body. It is drawn out on both sides, and the other outer side is covered with dielectric 1. External electrodes of silver, palladium, etc. are baked on the extraction electrode parts 4 and 5, and the chip parts are made into chip parts or lead wires are attached. used as a single component.

The capacitor of the present invention configured in this way is
Since the internal electrodes 2 and 3 are sealed with the ceramic dielectric 1 and the glass insulators 6 and 7, they are highly reliable under various environments, and the end faces, which are particularly vulnerable to electrical, mechanical, and airtightness, are protected. The effect is remarkable because it is covered with glass. Furthermore, since it has a structure in which a thin ceramic dielectric material is wound, it is possible to manufacture a small device with a large capacity. Furthermore, since the portion drawn out to the outside is the terminal portion of the electrode, it is possible not only to improve the volumetric efficiency of the capacitance, but also to reduce the amount of expensive internal electrodes used. In the above-described embodiments, the end faces of the columnar bodies are flat, but the same effect can be obtained even if the end faces are circular.

Next, a method for manufacturing the above-mentioned capacitor will be explained with reference to FIGS. 2 to 7. First, as shown in Figure 2, electrodes 2 and 3 were formed by printing palladium paste on a green sheet 1 made of barium titanate dielectric powder, leaving insulation margins at both ends (top and bottom in the figure). Create two sheets. The thickness of the green sheet is approximately 50μ, and the thickness of the electrode is approximately 5μ.
μ. Next, as shown in FIG. 3, the two sheets described above are stacked one on top of the other with their ends shifted. In the figure, A is a plan view, B is a cross-sectional view, and 8 is the back side of the stacked sheets (i.e., the surface without electrodes), and the end opposite to the side where the tips 4 and 5 of the electrodes are exposed. It is. Next, as shown in FIG. 4, the two superimposed sheets described above are wound around the winding shaft 9, and then the winding shaft 9 is removed and a hollow cylindrical body 10 is formed as shown in FIG. do. At this time, the tips 4 and 5 of the electrodes 2 and 3 are exposed at opposing positions on the circumference. Next, a force parallel to the axis is applied to the cylindrical body 10 to crush the hollow portion to form a rod-shaped flat body 11 as shown in FIG. At this time, the tips 4 and 5 of the electrodes are exposed at both ends in the thinner direction of the rod-shaped flat body. Next, the bar-shaped flat body 11 is cut to a predetermined length to produce a flat body chip 12 shown in FIG.
Next, this chip 12 is fired at 1400°C, and then a paste made of lead-based glass frit is applied to both end faces of the chip and fired at 800°C to obtain a capacitor as shown in FIG. As shown in the figure, one end 4, 5 of each of the pair of internal electrodes 2, 3 is exposed to the outside, and the other internal electrodes have a spiral shape, and the end surfaces are glassy 6, 7, excluding the exposed electrodes. A capacitor whose outer surface is sealed with ceramic is obtained. This capacitor has an exposed portion 4 of the electrodes 2, 3,
5 is used by connecting an external electrode such as silver, palladium, or a lead wire.

Note that the capacitance of the capacitor can be easily changed by changing the material and thickness of the dielectric, the length and cutting dimensions of the electrode, and the like. In addition to being flat, the end surface of the spiral may be circular.

According to the manufacturing method of the present invention described above, the opposing 1
The overlapping portions of the pair of electrodes do not shift in position during winding, so there are no variations in capacitance, and the manufacturing thereof is extremely easy.

[Brief explanation of the drawing]

FIG. 1 shows one embodiment of the ceramic capacitor of the present invention, A is a perspective view, B and C are sectional views taken in different planes, and FIGS. 2 to 7 show the manufacturing process of the present invention. The figure is a plan view of a ceramic sheet with electrodes printed on it, FIG. 3A is a plan view of two sheets stacked on top of each other, B is a cross-sectional view thereof, and FIG. 4 is a perspective view of the process of winding the sheet around a winding shaft. Fifth
The figure is a perspective view of a hollow cylindrical body, FIG. 6 is a perspective view of a rod-shaped flat body, and FIG. 7 is a perspective view of a flat chip. DESCRIPTION OF SYMBOLS 1... Ceramic dielectric, 2, 3... Internal electrode, 4, 5... Electrode exposed part, 6, 7... Glass insulator, 8... Winding start, 9... Winding shaft.

Claims (1)

[Scope of Claims] 1. A columnar body is formed by spirally winding a pair of electrodes with a ceramic dielectric sandwiched between them, and both end faces of the columnar body are covered with a glass insulator, and the other end faces are covered with a glass insulator. A ceramic capacitor comprising: exposing the pair of electrodes on opposing side surfaces of a columnar body, and covering the side surfaces other than the exposed electrodes with a ceramic dielectric. 2. The ceramic capacitor according to claim 1, wherein the ceramic dielectric is a titanate-based dielectric or a titanium oxide-based dielectric. 3. A ceramic capacitor according to claim 1, wherein the pair of electrodes is made of a conductive material that can be fired at the same time as the ceramic dielectric. 4. The ceramic capacitor according to claim 1, wherein the columnar bodies are flat. 5. The ceramic capacitor according to claim 1, wherein the columnar body is circular. 6. A step of stacking two ceramic dielectric green sheets with electrodes printed on them with insulating margins left at both ends, shifting them in the direction of the ends, and winding the stacked sheets around the winding shaft from one end. , a step of extracting the winding shaft to form a hollow columnar body, a step of crushing the hollow columnar body to form a solid columnar body, and a step of cutting the columnar body in the length direction to form a rod-shaped chip. and a step of firing the chip at a ceramic dielectric firing temperature, and applying a glass insulating material to both end faces of the fired chip and firing it at a temperature equal to or lower than the firing temperature.