JPH0452981Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a multilayer ceramic capacitor, and particularly to the shape of internal electrodes and the laminated structure thereof.

[Conventional technology]

As shown in FIG. 2a, a conventional multilayer ceramic capacitor is constructed by laminating a plurality of ceramic dielectric sheets 2a with internal electrodes 1a formed thereon by rotating them by 180 degrees so that the orientation of the internal electrodes is alternate.
A plurality of ceramic dielectric sheets 21 serving as protective layers are laminated on the upper and lower surfaces, and the whole is bonded and integrated by thermocompression to form a ceramic capacitor body 3a.Then, the ceramic capacitor body 3a is fired, and both ends of the ceramic dielectric sheet 21 are stacked. An external electrode 4 was deposited and formed.

[Problem that the invention attempts to solve]

In the above-mentioned conventional technology, when designing a small-capacity multilayer ceramic capacitor, if the required effective number of internal electrodes 1a is small, from several to one or less, variations in the thickness of the ceramic dielectric sheet 2a or the ceramic dielectric sheet Due to stacking errors when a plurality of 2a layers are stacked, it becomes difficult to accurately realize the designed capacity.

In order to solve this problem, a measure is taken to simply reduce the area of the internal electrodes 1a, and since the required number of internal electrodes 1a increases, the influence of variations in the thickness of the ceramic dielectric sheets 2a is reduced. However, the effect of stacking errors when a plurality of ceramic dielectric sheets 2a are stacked becomes greater as the area of the internal electrodes 1a becomes smaller, and as a result, it remains difficult to accurately realize the designed capacitance.

An object of the present invention is to provide a multilayer ceramic capacitor having a structure that eliminates the effects of thickness variations in ceramic dielectric sheets and stacking errors, and greatly improves the design accuracy of small-capacity products.

[Means for solving problems]

In the multilayer ceramic capacitor according to the present invention, the internal electrodes are formed in a donut shape so that the central part of the internal electrodes is blank, and the internal electrodes directly above and below are laminated with alternating shifts at a constant ratio. It is characterized by the fact that the internal electrodes on the bottom surface overlap in two places.

The shape of the internal electrode and its laminated structure are the features of the present invention.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1a shows a ceramic dielectric sheet 2 on which internal electrodes 1 according to the present invention are formed. The internal electrode 1 is formed in a donut shape so that the center part is blank, and is formed offset from the center line A-A1.

When a plurality of ceramic dielectric sheets 2 are laminated by alternately rotating them by 180 degrees so that the directions of the internal electrodes 1 are reversed, the internal electrodes 1 formed on the two ceramic dielectric sheets 2 on the directly upper and lower surfaces overlap. Figure 1c shows a transparent view of the situation from the top of the sheet. Internal electrodes 1 and 11 on the upper and lower surfaces overlap at two locations B and C in FIG. 1c. The total area of the overlapping portions B and C determines the capacitance of the multilayer ceramic capacitor. That is, in the present invention, the internal electrode 1 is formed so that the internal electrodes on the upper and lower surfaces overlap at two places, as shown in FIG. 1c.

After laminating a plurality of ceramic dielectric sheets 2 shown in FIG. 1a by rotating them alternately by 180 degrees so that the internal electrodes 1 are in the opposite direction, a protective layer shown in FIG. A ceramic capacitor body 3 is obtained by laminating a plurality of ceramic dielectric sheets 21, and then thermocompression bonding and integrating the whole. Thereafter, this is fired and external electrodes 4 are formed on both ends thereof to obtain the multilayer ceramic capacitor of the present invention. FIG. 1d is a sectional view of the multilayer ceramic capacitor of the present invention taken along line A-A1 in FIG. 1a.

[Effects of the invention] From the above embodiments, the effects of the invention can be summarized as follows.

(1) The overlapping area of the internal electrodes on the top and bottom surfaces can be reduced, and especially when designing a small-capacity multilayer ceramic capacitor, the number of internal electrodes required can be increased, reducing the effect of thickness variations in the ceramic dielectric sheets. be done.

(2) Even if a lamination error occurs when laminating the ceramic dielectric sheets on which the internal electrodes are formed, the area of the overlapping portion of the internal electrodes directly above and below does not change, so the influence of the lamination error is eliminated.

As a result of the above effects (1) and (2), the multilayer ceramic capacitor of the present invention has improved design accuracy, especially for small-capacity products, compared to the conventional technology.

[Brief explanation of the drawing]

Fig. 1a is a top view of a ceramic dielectric sheet forming internal electrodes of the present invention, Fig. 1b is a top view of a ceramic dielectric sheet serving as a protective layer, and Fig. 1c
Figure 1 is a transparent view from above showing how the internal electrodes overlap when two ceramic dielectric sheets in Figure 1a are rotated 180 degrees so that the orientation of the internal electrodes is reversed and then stacked. d is a cross-sectional view of the multilayer ceramic capacitor of the present invention taken along line A-A1 in FIG. Top view of ceramic dielectric sheet serving as a protective layer, 2nd
FIG. c is a sectional view of a conventional multilayer ceramic capacitor taken along line A-A1 in FIG. 2a. 1, 11, 21...Internal electrode, 2, 21, 2a
. . . Ceramic dielectric sheet, 3, 3a . . . Ceramic capacitor body, 4 . . . External electrode.

Claims (1)

[Scope of utility model registration request] In multilayer ceramic capacitors, which are made by laminating alternately multiple dielectric sheets with conductive internal electrodes, and further laminating dielectric sheets that serve as protective layers on the top and bottom surfaces, the central part of the internal electrodes is blank. Form the internal electrode in a donut shape so that
A multilayer ceramic capacitor characterized in that the internal electrodes on the immediately upper and lower surfaces are stacked alternately at a constant ratio, thereby creating two overlapping portions of the internal electrodes on the immediately upper and lower surfaces.