JPH06333790A - Low impedance solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To provide a low impedance solid electrolytic capacitor capable of having impedance and equivalent series resistance of 10mOMEGA or less in a frequency area of 100kHz to 1MHz and effectively absorbing noises in a high frequency area of 1MHz or more. CONSTITUTION:Two capacitor parts 2, 3 are provided at specific intervals on a surface of a metallic substrate 1 and anode external terminal mounting parts 1-1, 1-2 are provided at both end parts of the metallic substrate 1, and also cathode external terminal mounting parts 2a, 3a are provided in the two capacitor parts 2, 3. Ferrite (magnetic substance) 8 is provided on the periphery of the metallic substrate between the two capacitor parts 2 and 3, and anode external electrode terminals 6, 7 are mounted to the anode external terminal mounting parts 1-1, 1-2, and also cathode external electrode terminals 4, 7 are mounted to the cathode external terminal mounting parts 2a, 3a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal substrate having a dielectric oxide film formed on the surface of aluminum or the like and a capacitor section having a functional polymer film having conductivity formed on the surface of the dielectric oxide film. The present invention relates to an impedance solid electrolytic capacitor, a low impedance solid electrolytic capacitor having low impedance and low equivalent series resistance (ESR) in a high frequency region of 100 KHz or more,
In particular, it relates to a low impedance type solid electrolytic capacitor having a low equivalent series inductance value.

[0002]

2. Description of the Related Art As electronic devices have become higher in performance, smaller in size and lighter in weight, downsizing and longer life of power supplies have been rapidly developed.
The miniaturization of the power source can be realized by increasing the operating frequency, but the operating frequency is 100 KHz → 200.
As the frequency becomes higher from KHz to 500 KHz to 1 MHz, the requirements for the performance of the components used in the power supply circuit, especially the capacitors, become strict, and the conventional existing capacitors cannot satisfy the requirements.

In response to the above-mentioned demand, functional polymers (polypyrrole, polythiophene, poly.
An aluminum solid electrolytic capacitor using a film (aniline, etc.) has been developed and put into practical use. The aluminum solid electrolytic capacitor has the same CV (product of capacitance and volume),
100KHz-1M, compared to conventional small aluminum
Equivalent series resistance (ESR) is 1/50 to 1 in the Hz region.
/ 100 is very low. Further, the equivalent series resistance of the tantalum solid electrolytic capacitor is as low as 1/10 to 1/20.

[0004]

However, even in the above aluminum solid electrolytic capacitor, development of a solid electrolytic capacitor having an even lower equivalent series resistance value (for example, 10 mΩ or less in the frequency region of 100 KHz to 1 MHz) is being demanded. is there. Also, in recent years, the switching frequency of the power supply has become close to 1 MHz, and 1M
There is a demand for the development of a capacitor that can effectively absorb noise in a high frequency region of Hz or higher.

The present invention has been made in view of the above points, and can effectively absorb noise in a high frequency region of 1 MHz or more with an impedance and an equivalent series resistance of 10 mΩ or less in the frequency region of 100 KHz to 1 MHz. An object is to provide a low impedance type solid electrolytic capacitor.

[0006]

In order to solve the above-mentioned problems, the present invention provides a functional polymer film having conductivity on the surface of a metal oxide substrate having a dielectric oxide film formed on the surface thereof. A solid electrolytic capacitor having a formed capacitor part, which includes a capacitor part 2, as shown in FIG.
Two metal plates 3 are provided on the surface of the metal substrate 1 at predetermined intervals, and the anode external terminal mounting portions 1- are provided at both ends of the metal substrate 1.
1, 1-2 are provided, and two capacitor sections 2, 3 are provided.
Cathode external terminal attachment portions 2a and 3a are provided on the outer periphery of the metal substrate 1-3 between the two capacitor portions 2 and 3 and a ferrite (magnetic material) 8 is provided on the anode external terminal attachment portion 1 The anode external electrode terminals 6 and 7 are attached to -1, 1-2, and the anode external electrode terminals 4 and 5 are attached to the cathode external terminal attachment portions 2a and 3a.

A solid electrolytic capacitor comprising a metal substrate having a dielectric oxide film formed on a surface thereof, and a capacitor portion having a functional polymer film having conductivity formed on the surface of the dielectric oxide film. As shown in FIG. 3, the capacitor part 2 is provided on the surface of the metal substrate 1 with a predetermined length, and the cathode external terminal mounting parts 2-1 and 2-2 are provided at both ends of the capacitor part 2.
2 and the anode external terminal mounting portions 1-1 and 1-2 are provided on both ends of the metal substrate 1, and the cathode external terminal mounting portion 2
Ferrite 8 is provided on the outer circumference of the capacitor part 2 between -1, 2-2, and the anode external electrode terminals 6 and 7 are attached to the anode external terminal attachment parts 1-1 and 1-2, and the cathode external terminal attachment part is provided. The cathode external electrode terminals are attached to 2-1 and 2-2.

[0008]

According to the present invention, by adopting the structure shown in FIG. 1, two capacitor portions 2 and 3 are provided on the surface of the metal substrate 1, and the input / output anode external electrode terminals 6 and 6 are provided at both ends of the metal substrate 1. 7 is provided, and two capacitor portions 2 and 3 are provided with input / output cathode external electrode terminals 4 and 5 to form a 4-terminal structure, and a ferrite 8 is provided on the outer periphery of the metal substrate 1 between the capacitor portions 2 and 3.
2 is provided, an equivalent circuit thereof becomes as shown in FIG. 2 and constitutes a filter circuit. As a result, as a whole, it functions as a filter device that is a combination of the capacitors C2 and C3 and the coil L8, and therefore functions as a noise absorbing device in the high frequency region. Further, the ferrite 8 multiplies the inductance by .mu.s, so that it can be used at low frequencies.

By adopting the configuration shown in FIG. 3, the equivalent circuit becomes that shown in FIG. 4, and the filter circuit is constructed. As a result, the capacitors C2-1, C2-2 and the coils L8-1, L
Since it acts as a filter device by the combination of 8-2, it acts as a noise absorbing device superior to the configuration of FIG. 1 in the high frequency region.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an external view showing the structure of a capacitor element of a low impedance solid electrolytic capacitor of the present invention according to claim 1. Reference numeral 1 is a metal substrate made of an aluminum substrate (or foil). The surface of the metal substrate 1 is roughened (etched), and an anodic oxide coating is further formed on the surface. Two capacitor portions 2 and 3 are formed on the surface of the metal substrate 1 at a predetermined interval. The condenser section 2, 3
In the formation of, the metal substrate 1 is covered with an insulating tape or a resin material such as polyvinyl alcohol at both end portions and the central portion and masked, and a conductive functional polymer film (for example, poly-pyrrole, poly・ Thiophene,
Then, a graphite layer and a silver paste layer are sequentially formed on the surface of the conductive functional polymer film.

Input / output anodes made of a solderable metal (for example, brass, solder-plated iron, etc.) are respectively attached to the anode external terminal mounting portions 1-1 and 1-2 at both ends of the metal substrate 1. The external electrode terminals 6 and 7 are attached by electric welding, ultrasonic welding, or the like. Also, the condenser section 2, 3
Cathode external terminal attachment part 2 on the surface of the silver paste layer outside the
Input / output cathode external electrode terminals 4 and 5 made of a solderable metal (for example, brass, solder-plated iron, or the like) are attached to a and 3a, respectively.

A ferrite (magnetic material) 8 is provided on the outer periphery of the metal substrate 1-3 between the capacitor portions 2 and 3. Since the ferrite 8 acts as an inductance, its shape and dimensions may be appropriately determined to obtain desired characteristics.

As described above, the input / output anode external electrode terminals 6,
7 and the input / output cathode external electrode terminals 4 and 5 are attached to a single plate of a solid electrolytic capacitor, which is fixed on a ceramic plate 9, and a low melting point glass or heat-resistant inorganic adhesive is applied around the single plate on the upper surface of the ceramic plate 9. After applying an agent (adhesive capable of adhering commercially available ceramics to each other), the other ceramic plate was placed on it (not shown), and the single plate was sandwiched between the ceramic plate 9 and the ceramic plate. After that, the two ceramic plates are bonded with the above-mentioned low melting glass or heat resistant inorganic adhesive.

FIG. 2 shows an equivalent circuit of the low impedance type solid electrolytic capacitor configured as described above. In the figure, C2 and C3 indicate the capacitances of the capacitors 2 and 3, and L8 indicates the inductance of the ferrite 8. Figure 2
As shown in FIG. 1, the solid electrolytic capacitor having the configuration of FIG. 1 constitutes a filter device as a whole by combining the capacitors C2 and C3 and the coil L8. Therefore, it acts as a noise absorbing device in the high frequency region. Also, the inductance is μs due to the ferrite 8.
It can be doubled and used from lower frequencies.

FIG. 3 is an external view showing the configuration of the capacitor element of the low impedance type solid electrolytic capacitor of the present invention according to claim 2. In FIG. 3, the same reference numerals as those in FIG. 1 indicate the same or corresponding portions. In the capacitor of this solid electrolytic capacitor, as shown in FIG. 3, a capacitor portion 2 is provided on the surface of a metal substrate 1 with a predetermined length, and cathode external terminal attachment portions 2-1 and 2-1 are provided at both ends of the capacitor portion 2. 2-
2 and the anode external terminal mounting portions 1-1 and 1-2 are provided on both ends of the metal substrate 1, and the cathode external terminal mounting portion 2
The ferrite 8 is provided on the outer circumference of the capacitor unit 2 between the −1 and the −2. Then, the anode external terminal mounting portion 1-
Anode external electrode terminals 6 and 7 are attached to terminals 1 and 1-2, and cathode external electrode terminals 4 and 5 are attached to cathode external terminal attachment portions 2-1 and 2-2.

As described above, the input / output anode external electrode terminals 6,
7 and the input / output cathode external electrode terminals 4 and 5 are attached to a single plate of a solid electrolytic capacitor, which is fixed on a ceramic plate 9, and a low melting point glass or heat-resistant inorganic adhesive is applied around the single plate on the upper surface of the ceramic plate 9. After applying an agent (adhesive capable of adhering commercially available ceramics to each other), the other ceramic plate was placed on it (not shown), and the single plate was sandwiched between the ceramic plate 9 and the ceramic plate. After that, the two ceramic plates are bonded with the above-mentioned low melting glass or heat resistant inorganic adhesive.

FIG. 4 is a diagram showing an equivalent circuit of the solid electrolytic capacitor having the structure shown in FIG. In FIG. 4, L8-
1, L8-2 shows the inductance of the ferrite 8,
C2-1 and C2-2 indicate the capacitance of the capacitor unit 2. As shown in the figure, by adopting the configuration of FIG. 3, the solid electrolytic capacitor as a whole has a capacitor C2-
1 and C2-2 and the coils L8-1 and L8-2 function as a filter device, and thus function as a noise absorbing device superior to the configuration of FIG. 1 in the high frequency region.

Although an aluminum plate (or foil) is used as the metal substrate 1 in the above embodiment, the metal substrate is not limited to this, and a metal plate (or foil) on the surface of which a dielectric oxide film can be formed. Of course, a tantalum sintered body formed in a flat plate shape may be used.

Further, in the above embodiment, the exterior is made of a dense ceramic plate, and the ceramic plate is sandwiched between the single plates of the solid electrolytic capacitor.
Needless to say, it may be a mold exterior made of a thermosetting epoxy resin or a thermoplastic polyphenylene sulfide resin, or a simple exterior made by powder coating of a thermosetting epoxy resin.

The low-melting glass or the heat-resistant inorganic adhesive for joining the ceramic plates is coated with the material so as to cover the whole single plate of the aluminum solid electrolytic capacitor, in addition to the purpose of joining the two ceramic plates. By doing so, the airtightness can be further maintained, and a solid electrolytic capacitor with less characteristic change can be obtained.

[0021]

As described above, according to the present invention as set forth in claim 1, two capacitor portions are provided on the surface of a metal substrate, and input / output anode external electrode terminals are provided at both ends of the metal substrate. A four-terminal structure in which the input and output cathode external electrode terminals are provided in two capacitor parts, and ferrite is provided on the outer circumference of the metal substrate between the capacitor part and the conde sensor part, so its equivalent circuit constitutes a filter circuit. Therefore, it exhibits an excellent noise absorbing function in the high frequency region. In particular, it can be expected to exert an excellent effect on noise absorption in a high frequency region where the power switch frequency is close to 1 MHz.

According to the second aspect of the invention, the capacitor portion is provided with one fixed capacitor portion on the surface of the metal substrate, and the input / output cathode external electrode terminals are attached to both ends of the capacitor portion, and the metal substrate is attached. Since a four-terminal structure in which input / output anode external electrode terminals are attached to both ends of the capacitor and ferrite is provided on the outer periphery of the capacitor part, the equivalent circuit thereof constitutes a filter circuit as in the present invention according to claim 1. Therefore, it exhibits an excellent noise absorbing function in the high frequency region. Especially the power switch frequency is 1MH
It can be expected to exhibit an excellent effect of absorbing noise in a high frequency region near z.

[Brief description of drawings]

FIG. 1 is an external view showing a configuration of a capacitor element of a low impedance type solid electrolytic capacitor of the present invention.

FIG. 2 is a diagram showing an equivalent circuit of the low impedance solid electrolytic capacitor shown in FIG.

FIG. 3 is an external view showing a configuration of a capacitor element of the low impedance solid electrolytic capacitor of the present invention.

FIG. 4 is a diagram showing an equivalent circuit of the low impedance solid electrolytic capacitor shown in FIG.

[Explanation of symbols]

 1 Metal Substrate 2 Capacitor Section 3 Capacitor Section 4 Input Cathode External Electrode Terminal 5 Output Cathode External Electrode Terminal 6 Input Anode External Electrode Terminal 7 Output Anode External Electrode Terminal 8 Ferrite 9 Ceramic Plate

Claims (2)

[Claims] 1. A solid electrolytic capacitor comprising a metal substrate having a dielectric oxide film formed on a surface thereof, and a capacitor portion having a functional polymer film having conductivity formed on the surface of the dielectric oxide film. Two capacitor portions are provided on the surface of the metal substrate at a predetermined interval, anode external terminal attachment portions are provided on both ends of the metal substrate, and cathode external terminal attachment portions are provided on the two capacitor portions, Ferrite is provided on the outer circumference of the metal substrate between the two capacitor parts, the anode external electrode terminal is attached to the anode external terminal attachment part, and the anode external electrode terminal is attached to the cathode external terminal attachment part. A low impedance type solid electrolytic capacitor characterized by being attached. 2. A solid electrolytic capacitor comprising a metal substrate having a dielectric oxide film formed on a surface thereof, and a capacitor section having a functional polymer film having conductivity formed on the surface of the dielectric oxide film. The capacitor portion is provided on the surface of the metal substrate with a predetermined length, cathode external terminal attachment portions are provided at both end portions of the capacitor portion, and anode external terminal attachment portions are provided at both end portions of the metal substrate, Ferrite is provided on the outer periphery of the capacitor portion between the external terminal attachment portions, and the anode external electrode terminal is attached to the anode external terminal attachment portion, and the cathode external electrode terminal is attached to the cathode external terminal attachment portion. Low impedance type solid electrolytic capacitor.