JPH03209709A - Laminated ceramic capacitor and circuit using this capacitor - Google Patents

Abstract

PURPOSE:To reduce impedance with respect to high frequency noises and to obtain a smoothing capacitor characterized by excellent noise absorbing effect by connecting the neighboring outer electrodes on one side among two pairs of outer electrodes to the input side, and connecting the outer electrode on the other side to the output side. CONSTITUTION:Inner electrodes 2a and 2b reaching the end face at one surface of a ceramic green sheet 1 are formed. The green sheets 1 are laminated so that the directions are alternately changed by 90 degrees. Cover sheets are laminated on the upper and lower sides of the green sheets. The sheets are compressed and baked. After the baking, outer electrodes 3a and 3b are formed at four places. The inner electrodes 2 are mutually connected. Thus a laminated ceramic capacitor 4 is fabricated. When the output of a switching power supply is connected to the neighboring outer electrodes 3a and 3b of the capacitor 4, the noise voltage contained in the output voltage is largely decreased.

Description

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

(Prior Art) Conventionally, as a means for removing or absorbing high frequency noise, a capacitor or a plurality of capacitors are connected in parallel in a circuit, or an inductance and a capacitor are combined.
It was used to form a C filter.

However, as shown in FIGS. 12 and 13, the capacitor used for the above-mentioned purpose has internal electrodes 32a and 32b formed on a ceramic green sheet 31, which are laminated, and then external electrodes 33a and 33b are formed. Although the multilayer ceramic capacitor 34 has a self-resonant frequency due to its shape, it is ineffective against noise having components higher than that frequency, and there is a problem in that noise cannot be removed.

In other words, it is generally expressed as an equivalent circuit in which capacitors C and R are connected in series, and the absolute value of the impedance 2 is 12+, and for frequencies higher than the self-resonant frequency, ω2
L2, 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 length of the lead wires, two lead wires can be drawn out from each terminal of the capacitor to cancel the inductance component caused by the lead wires, and it is also possible to use a leadless chip capacitor. A similar effect can also be achieved by However, the inductance component caused by the length between the electrode terminals has a problem in that the inductance has a constant value.

(Problems to be Solved by the Invention) As described above, capacitors having an inductance component that is generated in proportion to the length between the electrode terminals of the capacitor have a drawback of being inferior in absorbing noise above the self-resonant frequency. For this reason, noise has been absorbed by configuring L and C filters or connecting multiple capacitors in parallel, but mounting such composite elements on a circuit board goes against the trend of miniaturizing devices. However, since this hinders price reduction, there has been a demand for a simpler device to be put into practical use.

The present invention responds to these demands by providing a multilayer ceramic capacitor capable of wide-ranging smoothing and noise absorption with a single element, and a circuit using the same.

[Structure of the invention]

(Means for Solving the Problem) The present invention provides an internal electrode formed on one surface of a green sheet to reach an end surface thereof, and the internal electrodes are laminated so as to cross each other through the thickness of the green sheet. This is a multilayer ceramic capacitor having two pairs of external electrodes connected to internal electrodes in the multilayer body, and a circuit using the same.

(Function) In the multilayer ceramic capacitor having the above configuration and the circuit using the same, the equivalent circuit network seen from the input side becomes a distributed constant network of capacitors and resistors to form a high frequency blocking filter, so the frequency becomes high. As the voltage that appears between the output side electrodes decreases, the frequency range is higher than the resonant frequency found in the case of ordinary two-terminal capacitors.
That is, even in the MH2 band, no increase phenomenon of the noise output voltage is observed, and the noise output voltage attenuates as it is.

This was confirmed by applying a high-frequency signal to the input electrode pair and observing the voltage appearing across the output electrode pair. The circuit described above also has a smoothing effect in the MH2 band.

(Example) As shown in Fig. 1, internal electrodes 2a and 2b reaching up to the end surface are formed on one surface of a ceramic green sheet 1 of 15 mm x 1'5 mm x 805 mm, and the direction of this green sheet 1 is alternately changed by 90 degrees. It was 45 pieces. Five cover sheets were laminated on each of the upper and lower sides of this laminated product, and the laminated material was pressed and fired. After firing, as shown in a front cross-sectional view in Figure 2 of the cylinder 2 and in a perspective view in Figure 3, an external electrode 3a is formed.

3b were formed at four locations and the internal electrodes 2 were interconnected to produce a multilayer ceramic capacitor 4 having a capacitance of 10 μF.

It has been confirmed that when the output of a switching power supply is connected to the adjacent external electrodes 3a and 3b of this multilayer ceramic capacitor 4 as shown in FIG. 4, the noise voltage included in the output voltage is significantly reduced. Ta. According to the inventor's experiments, the noise voltage was significantly reduced to about 1/4 in the embodiment shown in FIG. 5 compared to the conventional example shown in FIG. 6. This is due to the fact that the capacitor's equivalent inductance is reduced, which increases its ability to absorb high frequency components, and similar results were obtained when measured using a spectrum analyzer, for example. Fig. 7 is a frequency response curve diagram of the embodiment, and Fig. 8 is a frequency response curve diagram of the conventional example.
An improvement of about 55 dB was observed in z.

As shown in FIG. 9, internal electrodes 12a and 12b are formed diagonally on the ceramic green sheet 11, and these are laminated to form external electrodes 13a and 1 as shown in FIG.
Exactly the same effect can be obtained with the [1 ceramic capacitor 14 having 3b.

In addition, as shown in Fig. 11, the ceramic green sheet 21
The same effect can be achieved by providing the internal electrodes 22a and 22b on the opposite sides and leading out the external electrodes on the opposite sides.Furthermore, in FIG. 11, the external electrode leading portions may be provided diagonally.

In addition, although the leadless type was described in the above embodiment,
The present invention also includes those in which lead wires are connected to the external electrodes, those in which external electrodes are provided, and those in which seven Elide beads are passed through the lead wires.

[Effect of the invention 1] The multilayer ceramic capacitor of the present invention and a circuit using the same have two pairs of external electrodes, one of which is adjacent to each other, connected to the input side, and the other external electrode connected to the output side. As a result, the impedance against frequency noise can be reduced, and the capacitor can be used as a smoothing capacitor with excellent noise absorption effect.

[Brief explanation of drawings]

1 to 5 show examples of the present invention, and FIG. 1 is a perspective view showing ceramic green sheets and a laminated state, and FIG.
The figure is a front cross-sectional view of a multilayer ceramic capacitor, Fig. 3 is a perspective view of a multilayer ceramic capacitor, and Fig. 4 is a circuit diagram of a switching power supply using a multilayer ceramic capacitor.
Fig. 5 is a characteristic diagram showing the noise voltage when using the capacitor according to the embodiment, Fig. 6 is a characteristic diagram showing the noise voltage when using the conventional capacitor, and Fig. 7 is the characteristic diagram showing the noise voltage when using the capacitor according to the embodiment. FIG. 8 is a frequency response curve diagram when using a conventional multilayer ceramic capacitor, FIG. 9 is a perspective view showing a ceramic green sheet of another example, and FIG. FIG. 9 is a perspective view of a multilayer ceramic capacitor using ceramic green sheets, FIG. 11 is a perspective view of another example of ceramic green sheets, and FIG. 12 is a perspective view of conventional ceramic green sheets stacked together. , FIG. 13 is a perspective view of the same multilayer ceramic capacitor. 1... Ceramic green sheets 2a, 2b... Internal electrodes 3a, 3b... External electrodes 4... Multilayer ceramic capacitor patent Applicant: Marcon Electronics Co., Ltd. Fig. 5 Circuit diagram of switching power supply Noise voltage characteristics (Example) Fig. 5 Noise voltage characteristics (Conventional example) Fig. 6 5 10 Frequency (MHz) Frequency response curve Fig. 7 (Example) 5 10 Frequency (MH2) Frequency response curve diagram (conventional example) Fig. 8 Ceramic green sheet of other embodiments Fig. 11 Perspective view of G Fig. 2 Fig. 3 Correction trend (spontaneous) 1. Indication of incident 1990 patent application No. 5296 No. 2, Name of the invention Multilayer ceramic capacitor and circuit using the same 3, Relationship with the case of the person making the amendment Patent applicant address: 993 1-1 Saiwai-cho, Nagai-shi, Yamagata Telephone: Nagai (0238) 84- 2131 (Major representative) Contents of the 6° correction (1) Statement M page 3, line 1 (2) Specification page 3, line 3 “...ω212... ...
Correct as ...ωL...J. that's all

Claims (3)

[Claims] (1) An internal electrode is provided on one surface of the green sheet and extends to the end surface of the green sheet, and the internal electrode is laminated so as to cross each other through the thickness of the green sheet, and the internal electrode within the laminated body is A multilayer ceramic capacitor with two pairs of external electrodes connected to. (2) Claim (1) in which the external electrodes are provided on four sides or four corners
) listed multilayer ceramic capacitors. (3) A circuit in which a pair of external electrodes of the multilayer ceramic capacitor according to claim (1) or (2) are connected to the output of a switching power supply.