JPS6262446B2 - - 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.
Large capacity is required. The present invention provides a small-sized, large-capacity capacitor that can meet such demands, and a method for manufacturing the same.

In the ceramic capacitor of the present invention, a ceramic dielectric and a pair of electrodes facing each other sandwiching the ceramic dielectric form a spiral flat body, and one end of one of the electrodes is attached to one opposite side surface of the flat body. , one end of the other electrode is exposed on the other opposing side surface.

FIG. 1 shows an embodiment of the ceramic capacitor of the present invention, in which A is a perspective view, B is a sectional view taken on the B plane, and C is a sectional view taken on the C plane. In these figures, 1 is a ceramic dielectric, which is made of a titanate-based dielectric such as barium titanate, or a titanium oxide-based dielectric. Reference numerals 2 and 3 designate a pair of internal electrodes that face each other with the ceramic dielectric 1 in between, and are made of platinum, palladium, or the like. The thickness of the dielectric 1 can take any value from about 10μ to 100μ. Further, the electrodes 2 and 3 have a thickness of about 1μ to 5μ, and the dielectric 1 and the electrodes 2 and 3 are spirally wound to form a flat body as shown in Figure B, with parts 4 and 4 of each electrode on both sides. 5 is exposed, and the other parts are buried with ceramic dielectric 1. External electrodes such as silver, palladium or lead wires are connected to the exposed portions 4 and 5 for use.

The capacitor of the present invention configured in this way is
Since the pair of internal electrodes 2 and 3 are spiral-shaped and buried inside the ceramic dielectric material, reliability under various environments is excellent, and the drawn-out portion of the internal electrodes can be kept to a minimum. Expensive electrode paste can be reduced and the volumetric efficiency of capacitance can be increased.

Next, the method for manufacturing the capacitor of the present invention described above will be described with reference to examples.

Example 1 As shown in Fig. 2, a green sheet 1 made of barium titanate dielectric powder was cut into strips, and an electrode paste made of palladium as a conductive material was applied on the left and right edges and both ends. Two sheets with electrodes 2 and 3 formed thereon are created by printing, leaving an insulating margin in the area. The thickness of green sheet 1 is approximately 50μ,
The thickness of electrodes 2 and 3 is about 5μ. Next, as shown in FIG. 3, the two sheets described above are shifted in the longitudinal direction of the electrode and overlapped. Reference numeral 6 in FIG. B is the back side (the surface without electrodes) of the stacked sheets, and is the end opposite to the end where the tips 4 and 5 of the electrodes are exposed. Next, as shown in Fig. 4, a winding shaft 7 is attached to the end portion 6 of the two stacked sheets, and the winding shaft 7 is wound up in the longitudinal direction. A cylindrical body 8 is obtained. At this time,
The tips 4 and 5 of the electrodes 2 and 3 are exposed at opposing positions on both sides of the circumference. Next, as shown in FIG. 6, parallel forces are applied to the hollow cylindrical body 8 from both sides to crush the hollow portion into a flat body 9. At this time, the tips 4 and 5 of each electrode are exposed in the thinner direction of the flat body 9. Next, this flat body is fired at a ceramic firing temperature of 1400°C to obtain the capacitor body shown in FIG.

FIG. 1A is a perspective view of the flat capacitor body, in which the tip 4 of one internal electrode 2 is exposed on one side in the thin direction of the flat capacitor body, and the tip 5 of the other internal electrode 3 is exposed on the other side in the thin direction. is exposed, and the other electrode portions are buried inside the ceramic dielectric 1. This capacitor body is used by connecting an external electrode such as silver, palladium, or a lead wire to the exposed portion of the electrode.

Note that when changing the capacitance of the capacitor, the required capacitance can be easily obtained by changing the material and thickness of the dielectric, the width and length of the electrodes, etc.

Since the above manufacturing method involves winding and crushing extremely thin ceramic green sheets, it is possible to manufacture small-sized, large-capacity capacitors, and the manufacturing method is simple, making it suitable for mass production.

The capacitor of the present invention thus manufactured is used as a chip component by being soldered onto a printed circuit board or connected with a conductive adhesive or the like.
Alternatively, it can be used as a single component with lead wires attached.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the ceramic capacitor of the present invention, where A is a perspective view and B and C are a first embodiment of the ceramic capacitor of the present invention.
2 to 6 are diagrams showing the manufacturing process of the present invention, FIG. 2 is a plan view of a green sheet on which electrodes are printed, and FIG. 3 is a top view of the green sheet on which electrodes are printed. FIG. 4 is a perspective view of the step of winding the sheet, FIG. 5 is a perspective view of the hollow cylindrical body, and FIG. 6 is a perspective view of the flat body. 1...ceramic dielectric green sheet, 2,
3... Internal electrode, 4, 5... Electrode end, 6... Winding start position, 7... Winding shaft, 8... Hollow cylindrical body,
9... Flat body.

Claims (1)

[Claims] 1. A ceramic dielectric is sandwiched between a pair of electrodes arranged in a flat spiral shape, and the pair of electrodes are placed on two opposing surfaces of the flat body excluding both end surfaces. A ceramic capacitor characterized by being drawn out separately. 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 Two rectangular ceramic green sheets with a flat electrode printed on them with both edges and a portion of both ends left unturned, are stacked on top of each other, shifted in the longitudinal direction, and the stacked sheets are placed on the winding shaft. A process of winding in the longitudinal direction, a process of extracting the winding shaft to form a hollow cylinder, a process of crushing this hollow cylinder to form a flat body without a hollow part, and a process of rolling this flat body under ceramic firing conditions. A method for manufacturing a ceramic capacitor, which comprises a firing process.