JPH097884A - Capacitor - Google Patents

Abstract

PURPOSE: To mount a capacitor on a board in a surface-mounting manner without deteriorating it in electrical capacity and providing a flat plate upright by a method wherein opposed electrodes are provided to the opposed surfaces of a capacitor extending up to the other opposed faces adjoining to the opposed surfaces so as to serve as terminal electrodes, and the vicinities of the lengthwise diagonal edges of the electrode forming surfaces of the capacitor are of insulating structure. CONSTITUTION: An opposed electrode 2 of Au is formed on each side of a ceramic board so as to provide a part R where no electrode is formed to each side of an element. A terminal electrode 3 of Ag is provided to each lengthwise end face of the unit element after the ceramic board is cut into elements. Therefore, a pair of opposed electrodes 2 of Au are electrically connected to the terminal electrodes 3 of Ag at the diagonal edges of the element respectively. By this setup, a capacitor of this constitution can be mounted on a circuit board low in mounting height in a surface-mounting manner without deteriorating in capacitance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectangular parallelepiped or flat plate type capacitor, and more particularly to the shape of the capacitor.

[0002]

2. Description of the Related Art A capacitor has a structure in which two electrodes are opposed to each other with a dielectric between them, and the electric capacity is proportional to the dielectric constant of the dielectric material and the electrode area, and inversely proportional to the distance between the electrodes. There are various types of capacitors depending on the purpose of use such as circuit design voltage, frequency, temperature, electric capacity and mounting method.Ceramic capacitors, aluminum electrolytic capacitors, organic film capacitors, mica capacitors, etc. There is. The flat plate type ceramic capacitor is a capacitor having a structure in which electrodes are arranged on the upper and lower surfaces of a plate-shaped dielectric ceramic.

[0003]

In the flat plate type ceramic capacitor, electrodes are attached to the upper and lower surfaces of a plate-shaped dielectric ceramic, and one of the electrode surfaces is used as an adhesive surface on a circuit board. At the time of mounting, it is necessary to connect the electrode surface on the upper side to the circuit board with a wire or the like, which makes it difficult to take out the electrode from the same surface, which makes it difficult to perform surface mounting.

Therefore, in order to take out the electrodes from the same plane without deteriorating the electric capacity of the capacitor, a method of mounting a flat plate is adopted. However, this mounting method has a problem in that a mounting failure occurs in which the flat plate falls down when soldering on the circuit board, and the circuit board becomes taller because the flat plate is erected.

A technical problem of the present invention is to provide a flat plate type ceramic capacitor which can be surface-mounted without raising a flat plate without impairing the electric capacity of the capacitor.

[0006]

According to the present invention, a counter electrode of a flat plate type capacitor having counter electrodes formed on two counter electrode surfaces facing each other on a flat dielectric ceramic surface is provided on each counter electrode surface. Adjacent to the opposing surface to extend to the terminal electrode, and the structure in which the vicinity of the ridges diagonally corresponding to each other on the side not extending to the adjacent surface of the opposing electrode is insulated, and, A flat-type capacitor characterized in that a groove-shaped concave portion is provided on a surface of a dielectric ceramic having an opposing electrode surface.

[0007]

According to the flat type capacitor of the present invention, the electrodes are present on the same surface as the circuit board faces each other, so that the surface mounting is possible without raising the flat plate. In addition, since there is a groove-shaped recess on the surface of the dielectric ceramic where the counter electrode surface is present, the distance between the electrodes becomes shorter, and even if the area of the counter electrode is reduced, compared to a flat-type capacitor of the same size. As a result, an electric capacity equal to or higher than that is secured.

[0008]

EXAMPLES Examples according to the present invention will be described below.

In this embodiment, a dielectric ceramic having a dielectric constant (ε) of 90 is used as a dielectric material, and a flat plate having a length of 1.6, a width of 0.8 and a thickness of 0.5 mm is used as a counter electrode. A flat plate type capacitor was manufactured by sputtering Au.

(Embodiment 1) As shown in FIG. 1, a groove-shaped recess 1 is formed in the center of each element in the longitudinal direction on a dielectric ceramic plate having a thickness of 0.5 mm as a base. After processing, as shown in FIG. 2, the counter electrodes 2 made of Au were formed on both surfaces of the ceramic plate by sputtering so that the individual element-less portions (width 0.25 mm) R could be taken. After the cutting process, as shown in FIG. 3, the Ag terminal electrode 3 was formed by dipping at the end in the length direction. In this way, each of the pair of Au counter electrodes 2 is electrically connected to each of the Ag terminal electrodes 3 at the diagonal ridge portions of the element. FIG. 4 shows the cross-sectional shape of the dielectric ceramic plate in the length direction, and the main parts are indicated by reference numerals. Table 1 shows the electric capacities of the manufactured capacitors for each shape.

[0011]

No. 1 has the same element shape as No. 5 (conventional type) and has no groove but has a terminal electrode.
However, since the insulating portion is provided, the area of the counter electrode is reduced, and the capacity is reduced as compared with No. 5. However, by providing a groove and choosing its dimensions,
Like No. 3 and No. 4, the capacity of No. 5 or more can be secured.

(Embodiment 2) An example of soldering the obtained capacitor on a circuit board is shown in FIG.

As shown in FIG. 4, it can be implemented with a low profile.

[0015]

As described above, by using the flat type capacitor according to the present invention, surface mounting on a circuit board, which cannot be achieved by the conventional electrode groove structure, does not reduce the capacity and the height is low. It becomes possible with.

[Brief description of drawings]

FIG. 1 is an external perspective view of a flat plate-shaped dielectric ceramics according to the present invention.

FIG. 2 is a perspective view in which electrodes are attached to upper and lower surfaces of a flat plate-shaped dielectric ceramics according to the present invention.

FIG. 3 is a perspective view in which electrodes are attached to the side surfaces of a flat plate-shaped dielectric ceramics according to the present invention.

FIG. 4 is a longitudinal sectional view of a flat plate-shaped dielectric ceramics according to the present invention.

FIG. 5 is an explanatory view showing a mounting example of a capacitor according to the present invention in a vertical section.

[Explanation of symbols]

 1 Groove (Concave) 2 Counter Electrode (Au) 3 Terminal Electrode (Ag) 4 Substrate 5 Circuit 6 Solder 7 Counter Electrode Surface R Part without Electrode (Insulation Part)

Claims (2)

[Claims] 1. A flat-plate capacitor having counter electrodes formed on two counter electrode surfaces facing each other on a flat dielectric ceramic surface, wherein the counter electrodes are surfaces facing each other and adjacent to the counter electrode surface. To form a terminal electrode, and the counter electrode is not provided in the vicinity of the facing surface on the non-extended side of the counter electrode surface. 2. The capacitor according to claim 1, wherein
A capacitor having a recess on one or both surfaces of a counter electrode.