JPS63148610A - Capacitor of four-terminal construction - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a capacitor used in an input filter, an output filter, etc. of a hybrid integrated switching power supply.
The present invention relates to a capacitor structure that is easy to mount and has excellent high-frequency noise suppression performance.

(Prior Art) A hybrid integrated switching power supply is mainly formed on a ceramic substrate, a glass epoxy substrate, or the like using components called surface mount components that can be easily mounted on the substrate surface. Regarding capacitor parts, parts called chip capacitors are often mounted directly on the board surface. However, capacitors with large capacitance such as input filters and output filters are relatively large in size and occupy a large area, and due to the difference in thermal expansion coefficient between the capacitor and the substrate, the mechanical Because of problems such as the tendency for damage to occur, a capacitor with a two-terminal structure was used.

Figure 2 shows a conventional two-terminal structure capacitor.

This capacitor 20 has terminals 21 and 22 connected to side electrodes 11 and 12 of the multilayer capacitor 10 with solder 23, respectively, and is covered with a resin 24 to prevent moisture and increase the mechanical strength of the terminals 21 and 22. The multilayer capacitor IO is a type of chip capacitor, and is configured such that a plurality of small capacitors formed by an electrode 13, an electrode 14, and a dielectric 15 are connected in parallel by side electrodes 11 and 12.

The terminals 21 and 22 of the capacitor 20 are usually cut to an appropriate length and bent, and then attached to the printed conductor 42 on the substrate 40, as in the example of mounting a low-pass filter shown in FIG.
．． 43. The capacitor 20 is a printed conductor 42.
Multilayer capacitor 1 from the connection between 43 and terminals 21 and 22
Since the terminal portion between 0 and 0 acts as a buffer material to absorb mechanical strain caused by the difference in coefficient of thermal expansion, it is possible to reduce mechanical damage factors during the power supply assembly process and operation.

(Problems to be Solved by the Invention) However, as seen in the frequency characteristics of the impedance IZ1 shown in FIG.
Capacitor 20 with two-terminal structure shown by individual characteristics and solid line
There is a clear difference between the characteristics of The reason for this difference in characteristics is that the terminal portions that functioned as buffer materials and the side electrodes 11, 12 of the multilayer capacitor 10 function as inductors proportional to their respective dimensions. That is, in the conventional two-terminal structure capacitor 10, the equivalent series inductance increases compared to the case of the multilayer capacitor 10 alone, which lowers the series resonance frequency and increases the impedance at frequencies higher than the series resonance frequency f. , there is a problem that the high frequency noise suppression performance deteriorates.

(Means for Solving the Problems) The present invention attempts to solve the above-mentioned problems by improving the terminal structure. To achieve this objective, the present invention provides a four-terminal structure for the terminal. That is, the four-terminal structure capacitor of the present invention includes at least one multilayer capacitor having a pair of side electrodes on opposing sides, and a capacitor that supports and fixes the multilayer capacitor and is electrically connected to each side electrode. The structure includes a pair of side conductors and lead terminal conductors integrally formed at both ends of the side conductors.

(Example) A first example of the present invention is shown in FIG. FIG. 1 is an example of the above-mentioned surface mounting component, in which a four-terminal structure capacitor 30 has conductors 35 and 36 connected to side electrodes 11 and 12 of a multilayer capacitor IO, and both end portions 31, 32, . 33 and 34 are formed as terminals. 1st
From the viewpoint of mass production, the conductors 35 and 36 in the figure are examples in which thin sheet metal conductors called lead frames formed by punching, corrosion processing, etc. are used.

This four-terminal structure capacitor 30 can be manufactured in a pre-controlled process, and as in the example of mounting a low-pass filter shown in FIG. and terminals 31.32°33, 34
Since the conductor portion between the connecting portion and the multilayer capacitor IO acts as a buffer against mechanical strain, it is possible to reduce mechanical damage factors as in the case of conventional capacitors.

A second embodiment of the invention is shown in FIG. The second embodiment is a four-terminal structure capacitor using two multilayer capacitors 10 and 10'.
The side electrodes 11.12 and 11', 12' are connected to conductors 35 and 36, respectively, and both end portions of the conductors 35 and 36 are formed as terminals 31.32.33.34.

This four-terminal structure capacitor can mount twice as much capacitance on the same area as the four-terminal structure capacitor of the first embodiment. The advantages regarding mechanical strength are the same as in the first embodiment. It is also possible to further increase the number of multilayer capacitors, and of course the capacitance per unit mounting area can be increased.

Regarding the four-terminal structure capacitor of the present invention, as a capacitor that originally has a two-terminal structure, for example, the electrical characteristics between the terminals 31 and 32 are such that the terminal portion and the side electrodes 11 and 12 portions of the multilayer capacitor 10 act as an inductor. Therefore, the performance is equivalent to that of conventional capacitors.

However, by setting the number of terminals to four, there are the following advantages.

FIG. 6 shows a configuration example of a low-pass filter used as an input filter and an output filter of a switching power supply. Here, 1 is a signal source corresponding to the noise voltage included in the output of the switching power supply, and one end of the signal source 1 is connected to one end of the inductor 2 via a printed conductor 51.
The other end of the inductor 2 is connected to the terminal 32 of the four-terminal structure capacitor 30 via the printed conductor 54, and the other end of the inductor 2 is connected to the terminal 31 of the four-terminal structure capacitor 30 via the printed conductor 52. 33 and 34 are connected to the resistor 3 corresponding to the load via printed conductors 53 and 55, respectively. In order to clarify the features of the four-terminal structure capacitor, FIG. 3 shows an example of a mounting configuration of a low-pass filter using a conventional structure capacitor 20. One end of the signal source 1 is connected to one end of the inductor 2 via a printed conductor 41, and the other end of the signal source 1 is connected to the terminal 21 of the capacitor 20 and one end of the resistor 3 via a printed conductor 43.
The other end is connected to the terminal 22 of the capacitor 20 and the other end of the resistor 3 via a printed conductor 42, respectively.

FIG. 7 shows the frequency attenuation rate characteristics of the low-pass filter shown in FIGS. 6 and 3. In Figure 7, the solid line represents the characteristics of the low-pass filter shown in Figure 6 using a four-terminal structure capacitor, and the broken line represents the characteristics of the low-pass filter shown in Figure 3 using a conventional capacitor. . The attenuation poles at frequencies f and f2 are due to the series resonance of the capacitors and correspond to the series resonance frequencies of the multilayer capacitor IO and the conventional capacitor 20, respectively.

Here, the attenuation rate approaches a constant value on the higher frequency side than the frequency of the attenuation pole. This is because at frequencies higher than the resonance frequency, the inductive reactance of the equal series inductors of the capacitor becomes larger than the capacitive reactance of the capacitor's capacitance, and the capacitor has mR characteristics, that is, acts as an inductor. The attenuation factor is the equal series inductance value of the capacitor and the inductor 2
The ratio of the inductance value to the inductance value becomes asymptotic.

Therefore, it can be seen that by making the capacitor have a four-terminal structure, the effective equivalent series inductance becomes smaller, which increases the attenuation factor in the high frequency range.

(Effects of the Invention) As explained above, the four-terminal structure capacitor of the present invention has the advantage that the equal series inductance can be made smaller than that of the conventional two-terminal structure capacitor, so that high frequency noise suppression performance is improved.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of the first embodiment of the present invention, Fig. 2 is a perspective view showing the structure of a conventional capacitor, and Fig. 3 is a low-frequency band using a conventional capacitor. Figure 4 is a diagram showing an example of implementation of a pass-through filter. Figure 4 is a diagram showing the impedance frequency characteristics of a conventional capacitor and a multilayer capacitor alone. Figure 5 is a diagram showing the impedance frequency characteristics of a conventional capacitor and a multilayer capacitor.
FIG. 6 is a diagram showing an implementation example of a low-pass filter using the four-terminal structure capacitor of the present invention, and FIG. 7 is a diagram showing the attenuation rate frequency characteristics of the low-pass filter. . 1... Signal source 2... Inductor 3 of low-pass filter... Resistor 10... Multilayer capacitors 11, 12... Side electrode 13 of multilayer capacitor 10,
14... Electrode of small capacitor 15... Inductor of small capacitor 20... Conventional two-terminal structure capacitor 21, 22.
・Terminal 23 of conventional capacitor 20 ・Solder 30 ・Capacitor 31, 32, 32, 32, 34, 34, 32, 32, 32, 32, 33, 34, 35, 36 of capacitor 30 with four-terminal structure... Solder 30... Terminal 35, 36 of capacitor 30 with four-terminal structure... To multilayer capacitor 10 Conductors 40, 50 for forming four terminals 31.32° 33, 34...Insulating substrate 41, 42.43.51.52.53.54.55 for configuring a low-pass filter・・・
・Printed conductor formed on an insulating substrate 40°50

Claims (1)

[Claims] 1. At least one multilayer capacitor having a pair of side electrodes on opposing sides, and a pair supporting and fixing the multilayer capacitor and electrically connected to each side electrode. A four-terminal structure capacitor comprising: a side conductor; and lead terminal conductors integrally formed at both ends of the side conductor. 2. The four-terminal structure capacitor according to claim 1, wherein the lead-out terminal conductor has a structure in which the lead-out terminal conductor is drawn out through bent portions in parallel and perpendicular directions to the side electrode surface of the multilayer capacitor. .