JPH0410510A - Laminated ceramic capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To make it possible to manufacture a laminated ceramic capacitor, as a smoothing capacitor, consisting of single element and having a high noise absorbing property by a method wherein the title capacitor is equipped with a laminated body, which is formed by laminating and sintering a plurality of ceramic green sheets into one body, and an external electrode, formed by connecting an internal electrode to the four-side faces, excluding a cutaway part, is provided on the four corners of the above-mentioned laminated body. CONSTITUTION:A continuous external electrode 6 is formed on the whole side face of a laminated body in advance by connecting the internal electrode exposed part 4, then the continuous external electrode 6 is divided by a cutaway part 7 by removing the four corners of a laminated body 5 including a part of the above-mentioned continuous external electrode part 6, by cutting or printing, and the external electrode 8, 9, 10 and 11, which are independent with each other, are formed on the four side faces of the laminated body 5. As a result, the desired external electrodes 8, 9, 10 and 11 can be formed easily in a precise manner, and this contributes greatly to the improvement of workability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a multilayer ceramic capacitor as a smoothing capacitor with excellent noise absorption properties and a method for manufacturing the same.

(Conventional technology) In recent years, switching power supplies have become smaller and lighter.

Switching frequencies are becoming increasingly high in order to improve efficiency, and this trend toward higher frequencies is accelerating.

Multilayer ceramic capacitors are small and non-polar.

Due to its features of high insulation resistance, low loss, and high reliability, it is attracting attention and being widely used as a smoothing capacitor on the output side or for noise absorption as the frequency becomes higher.

As shown in FIGS. 11 and 12, the general structure of the multilayer ceramic capacitor is to use a ceramic green sheet 22 on which an internal electrode 21 is provided with one side extending to the outer periphery. A plurality of ceramic green sheets 22 are stacked and sintered so that one side extending to the outer periphery of the ceramic green sheet 22 is alternately opposite to the other, and external electrodes 23 are formed on both sides where the internal electrodes 21 are exposed. ing.

However, such @layer ceramic capacitors have a self-resonant frequency due to their shape, and are ineffective against noise having components higher than that frequency, making it impossible to eliminate noise.

In other words, a capacitor is generally represented by an equivalent circuit in which C and R are connected in series, and its impedance Z
The absolute value I71 of is ω for frequencies higher than the self-resonant frequency.
L1, that is, the inductance component can no longer be ignored, and the impedance to high frequency noise increases.

The factors that determine the size of L are the length of the lead wire of the capacitor and the length between the electrode terminals. Regarding the lead wire length, which is a factor, two lead wires are drawn out from each terminal part of the capacitor, and the inductance component caused by the lead wire part can be canceled, and by making it leadless and making it a chip structure. You can also get the same effect.

However, the other factor, the inductance component due to the length between the electrode terminals, still remains.

However, the inductance component caused by the length between the electrode terminals cannot be ignored as the frequency becomes higher, and as the frequency of switching power supplies increases as described above, the multilayer ceramic capacitors having the above structure are Since it becomes difficult to absorb noise above the self-resonant frequency, this results in problems for capacitors used in such circuits.

Conventionally, noise absorption was improved by configuring L and C filters or connecting multiple capacitors in parallel, but this increased the number of components mounted on the circuit board, and the trend was toward smaller and lighter equipment. This went against the grain and impeded price reductions, and improvements were desired.

(Problems to be Solved by the Invention) As described above, conventional film-based multilayer ceramic capacitors have poor noise absorption properties above the self-resonant frequency, so it is necessary to configure a C filter when using these capacitors. However, it is necessary to take measures such as connecting multiple capacitors in parallel, making the equipment larger and more expensive, which cannot be solved in response to the recent demands for smaller and lighter equipment. The result was a problem that should have been avoided.

The present invention has been made in view of the above points, and aims to provide a multilayer ceramic capacitor as a smoothing capacitor capable of absorbing a wider range of noise using a single element, and a method for manufacturing the same. .

[Structure of the Invention] (Means for Solving the Problems) The multilayer ceramic capacitor according to the present invention has a multilayer ceramic capacitor in which a plurality of green sheets provided with internal electrodes are laminated and sintered into one piece, with the squares of the laminate being formed into a defective portion, and the defect is removed. The capacitor is characterized by having separate external electrodes connected to the internal electrodes on all four sides of the laminate except for the laminate. After forming the external electrode, the square part of the laminate is removed and a missing part is formed to divide the external electrode into four parts, or after the square part of the laminate is removed and a missing part is created, This is characterized in that external electrodes that are continuous with internal electrodes are formed on all four sides excluding the missing portion.

(Function) Since it is configured as described above, it is possible to use one pair of adjacent terminals as input terminals and the other pair of terminals as output terminals, making it possible to use a four-terminal filter circuit with distributed constants of C and R. is formed5, and high frequency components are less likely to appear in the output.
Since the L component is caused only by the internal electrode spacing on the order of microns, that is, the thickness of the dielectric, it does not change even if the capacitor's shape becomes larger as long as the dielectric has the same thickness, making it easy to reduce the inductance. Can absorb noise components higher than the resonant frequency.

In addition, as an external electrode forming means, unnecessary parts of external electrodes that have been continuously formed in advance can be removed and divided, or parts other than the external electrode forming part on the side surface of the laminate can be removed in advance to form squares as missing parts, and then external electrodes can be formed. Therefore, desired external electrodes can be easily formed with high precision.

(Example) Examples of the present invention will be described below.

As shown in FIG. 2, a ceramic green sheet 2 is used which extends from the supination periphery to the two opposing lateral peripheries and is provided with internal electrodes 1. A plurality of sheets are laminated so as to cross each other alternately, and cover sheets 3 are placed on each of the upper and lower sides as shown in Fig. 3.
After being laminated, pressure sintering is performed to form a laminate 5 having internal electrode exposed portions 4 on each of its four sides.

Next, as shown in FIG. 4, all sides of this laminate 5 are sequentially immersed in an external electrode paste, pulled up, and dried and baked, and continuous external electrodes 6 connected to the internal electrode exposed portions 4 are formed on all sides of the laminate 5. Then, as shown in FIG. 1, a square of the laminate 5 including a part of the continuous external electrode 6 is cut.

It is removed by cutting or polishing to provide a cutout 7, and the external electrodes 8, 9, 10, 11 are positioned independently on each of the four sides of the laminate 5.

When using a multilayer ceramic capacitor with the above configuration connected to a switching power supply circuit, a pair of adjacent external electrodes 8 and 9 should be connected to the output of the switching power supply as input terminals, as shown in Fig. 5. The noise voltage included in the output voltage taken out from the other pair of external electrodes 10.11 can be significantly reduced by 0.05, which formed the internal electrodes used in the inventor's experiments.
According to a multilayer ceramic capacitor with a capacitance of 10 μF obtained by laminating 45 m+ ceramic green sheets by the above-mentioned method, the noise voltage is approximately 1
A significant noise voltage reduction of /4 was confirmed.

This is due to the fact that the equivalent inductance of the capacitor becomes smaller and the CR filter is formed internally, which increases the noise absorption ability for high frequency components. As is clear from FIG. 7, it was confirmed that similar results were obtained.

Further, according to the manufacturing method of such a multilayer ceramic capacitor, a continuous external electrode 6 is formed by connecting the internal electrode exposed portion 4 on all sides of the multilayer body in advance, and then a part of the continuous external electrode 6 is formed. The continuous external electrode 6 is divided by the cutout part 7 by cutting, cutting, or polishing to remove a square of the laminate 5 including .10.11, the desired external electrode 8.9.10.11 can be formed with precision.
can be easily formed, greatly contributing to improved workability.

In the above embodiment, the shape of the cutout part 7 has been explained by exemplifying a shape in which the corners are cut off in a straight line, but as shown in FIG. In addition, any other suitable shape may be used.

Further, in the above embodiment, as a means for forming external electrodes 8, 9, 10° 11, continuous external electrodes 6 are formed in advance on all sides of the laminate 5, and the squares of the laminate 5 including a part of the continuous external electrodes 6 are formed in advance on all sides of the laminate 5. The explanation has been given by exemplifying the means for removing the laminate 13, but as shown in FIG. 9, the squares of the laminate 13 are removed in advance to provide the missing portions 14, and then, as shown in FIG. 10, the missing portions 14 are removed. External electrode 15°16.1'7.
The same effect can be achieved by providing the missing portion 18. In this case, the shape of the missing portion 14 may of course be as shown in FIG.

Furthermore, the shape of the internal electrodes is not limited to the above-mentioned embodiments, but may be any suitable shape as long as it has a portion extending to the two opposing outer peripheries in the outer periphery of the gate.

In each of the above embodiments, a leadless type has been described as an example, but a lead wire is connected to each external electrode, a variety of exteriors are provided, and a lead wire is passed through 7 Elide beads. etc. are also included in the present invention.

[Effects of the Invention] According to the present invention, an inductance component is reduced and a CR filter is formed inside the capacitor, so that an 8-layer ceramic capacitor and a highly practical value with excellent noise absorption effects against high frequency components can be manufactured. A manufacturing method thereof can be obtained.

[Brief explanation of the drawing]

Figures 1 to 5 relate to the present invention; Figure 1 is a plan view showing a multilayer ceramic capacitor, Figure 2 is a perspective view showing the configuration of ceramic green sheets and their laminated state, and Figure 3 is a laminate. 4 is a perspective view showing a state in which continuous external electrodes are formed on all sides of the laminate, FIG. 5 is a circuit diagram of a switching power supply using the capacitor shown in FIG. 1, and FIG. 6 is a diagram of the present invention. FIG. 7 is a frequency response curve diagram when a conventional multilayer ceramic capacitor is used, and FIGS. 8 to 10 relate to other embodiments of the present invention. Fig. 8 is a plan view showing a multilayer ceramic capacitor, Fig. 9 is a perspective view showing a multilayer body, Fig. 10 is a small plan view of the multilayer ceramic capacitor, and Fig. 1
1 and 12 relate to a conventional example, FIG. 11 is a perspective view showing a laminated state of ceramic green sheets, and FIG. 12 is a perspective view showing a multilayer ceramic capacitor. 1... Internal electrode 2... Ceramic green sheet 5...
・Laminated body 6...Continuous external electrode 7...Missing portions 8.9, 10.11...External electrode 12...
... Missing part 13 ... Laminate 14 ... Missing part 15, 16, 17, 18 ... External electrode patent applicant Marukon Electronics Co., Ltd. Flat surface of multi-flit ramic capacitor Figure 1: A perspective view of the laminated state of ceramic green sheets Figure 2:
Figure O Frequency (MHz) Frequency response curve diagram (Example) Figure 6 Frequency (MH2) Frequency response curve Figure 7 (Conventional example) Figure 10 Procedure amendment between planes of multilayer ceramic capacitors of other examples ( Spontaneous) Description of the case 1990 Patent Application No. 1 2246 2 Title of the invention Multilayer ceramic capacitor and its manufacturing method 3゜Relationship with the case

Claims (3)

[Claims] (1) Ceramic green sheets extending from the four outer peripheries to two opposing outer peripheries and provided with internal electrodes, and a laminate in which a plurality of ceramic green sheets are laminated and sintered so that the internal electrodes alternately intersect with each other. A multilayer ceramic comprising: a body, a cutout provided in a square of the laminate, and external electrodes connected to the internal electrode and provided on four sides of the laminate excluding the cutout. capacitor. (2) Forming internal electrodes extending from the four outer peripheries of the ceramic green sheets to two opposing outer peripheries, and laminating and sintering a plurality of ceramic green sheets so that the internal electrodes alternately intersect. a step of forming continuous external electrodes connected to the internal electrodes on all sides of the laminate; and a step of removing the square portions of the laminate by cutting, cutting or polishing to provide a missing portion. A method for manufacturing a multilayer ceramic capacitor, characterized by sequentially passing through the steps of dividing a continuous external electrode into four parts. (3) Forming internal electrodes extending from the four outer peripheries of the ceramic green sheets to two opposing outer peripheries, and stacking and sintering a plurality of ceramic green sheets so that the internal electrodes alternately intersect. a step of removing the square portions of the laminate by cutting, grinding or polishing to provide a missing portion; and providing external electrodes continuous with the internal electrodes on four sides of the laminate excluding the missing portions. 1. A method for manufacturing a multilayer ceramic capacitor, comprising sequentially forming steps.