JPH06120088A - Chip-type solid-state electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain a chip-type solid-state electrolytic capacitor excellent in high frequency characteristics and noise absorbing properties by a method wherein the electrolytic capacitor is formed in a four-terminal structure wherein anode leads are led out in the opposed lateral directions respectively, and cathode leads are led out in the opposed longitudinal directions making an angle of 90 deg. or so with the anode terminals. CONSTITUTION:Two elements 7 are made to overlap each other opposite in sense sandwiching cathode lead terminals 8 between them at a right angle with the terminals 8, and the cathode lead terminals are joined to the elements 7 with silver paste. The anode lead terminals 9 and the cathode lead terminals 8 are formed of a lead frame itself, cut into prescribed shapes and formed after the elements 7 are sealed up with resin 10 by transfer molding. By this setup, a chip-type solid-state electrolytic capacitor excellent, in high frequency characteristics and noise absorbing capacity can be obtained. A capacitor of this design is able to function as a single capacitor or two capacitors depending on the combination of circuits.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip-type solid electrolytic capacitor, and provides a solid electrolytic capacitor which has a low loss and an excellent noise absorbing ability, and can realize the functions of two capacitors by one chip by an embedded circuit. To do.

[0002]

2. Description of the Related Art Tantalum electrolytic capacitors have been widely put into practical use as chip type solid electrolytic capacitors.
The tantalum powder is sintered and lead wires are attached to form internal elements. Therefore, the structure of the chip type capacitor is also suitable for it, and its basic structure is as shown in FIG. 5, the anode inner lead 1 taken out from the tantalum sintered body.
8 and the external anode lead 19 are connected, the cathode is formed by forming the external cathode lead 20 along the element 17, connected via a silver paste, and molded with the exterior resin 21. . In the case of the aluminum solid electrolytic capacitor, the sintered body basically has a structure similar to that of the tantalum electrolytic capacitor. However, as for the aluminum solid electrolytic capacitor, almost no sintered type capacitor has been put into practical use at present.

In an aluminum solid electrolytic capacitor, an electrode area is enlarged by etching an aluminum foil, an anodic oxide film layer is formed, and a solid electrolyte layer and a cathode conductive layer are sequentially formed. This element structure includes a flat element and a wound element, but in the case of the wound element, an aluminum foil is often used for the cathode. This is a direct application of a conventional liquid electrolyte device. On the other hand, a typical chip capacitor in the case of a flat element is shown in FIG. According to this, the element 11 composed of a plurality of flat electrodes is welded to the anode structure at the electrode connection portion 13 of the plurality of flat elements, and then joined to the external anode lead 14 at its tip. As for the cathode structure, a plurality of flat elements are joined by silver paste or the like, and the connection with the external cathode lead 15 is performed by forming the external lead in a shape along the outer circumference of one of the upper and lower sides of the plurality of elements. It is connected via a silver paste and is molded with the exterior resin 16.

However, in the chip-type electrolytic capacitor having the structure described above, there is a structural limit to the reduction of the impedance in the high frequency circuit, and there is also a limit to the noise absorption capability. . That is, in the conventional structure, the anode terminal and the cathode terminal are opposed to each other by a single structure. Therefore, when the frequency becomes high, the current effectively flows through the land portion of the printed wiring to the inside of the capacitor. Therefore, the effect of the capacitor element (effect of reducing the inductance by utilizing the electrostatic capacity of the capacitor)
As the frequency becomes higher, the characteristics cannot be fully utilized. In recent years, solid electrolytes have progressed, the conductivity of solid electrolytes has improved, high frequency compatibility has progressed, and the electrode materials made of alloys of aluminum and zirconium have also advanced, making it possible to fabricate chip-type solid electrolytic capacitor elements with high capacitance. The high-frequency compatible chip structure has become an important consideration item more than ever before. Further, in the chip type solid electrolytic capacitor as described above, it is often seen that two or more are required on the circuit, but in reality, one solid electrolytic capacitor cannot cope with it.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems for high frequency and to realize a chip type solid electrolytic capacitor for high frequency. With the conventional chip structure, when the frequency becomes high, the current easily flows through the land part of the mounted printed circuit board due to the skin effect, the current to be passed to the capacitor element decreases, and the effect expected of the capacitor There is a problem that the effect of maximizing the capacitance and minimizing the inductance cannot be obtained. Further, depending on the circuit, a two-element capacitor that can realize a place where two capacitors were required until now with one chip is impossible with the conventional structure.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been found out from repeated examinations for solving the above-mentioned problems, and from the examination of a chip structure that maximizes the advantages of a capacitor element compatible with high frequencies. is there. The essence of the present invention is that at least two elements for anode are used, each element is arranged in the opposite direction, and external electrodes are also led out from the opposite directions, and the cathode external electrode is from the middle part of the two elements to the anode external electrode. A structure with a four-terminal structure that extends in two directions in the front-back direction of 90 degrees, eliminates the junction resistance between elements in the anode part, and suppresses the influence of the magnetic field generated by the elements by making the two elements in opposite directions. It is also becoming. Further, since the anode terminal is separately derived from each element, it is also possible to use the cathode as a common element for two elements by the circuit pattern. That is, a solid electrolytic capacitor element obtained by using an aluminum or aluminum alloy electrode plate, etching the electrode to increase the effective area, and then sequentially forming an anodic oxide film layer, a solid electrolyte layer and a cathode conductive layer is provided. A single piece was used, and the anode leads were led out in the opposite directions to the left and right, and the cathode leads were led out from the junction of the two elements before and after the element at an angle of about 90 degrees with respect to the anode lead. It is a characteristic chip type solid electrolytic capacitor,
The chip-type solid electrolytic capacitor is characterized in that the aluminum alloy electrode is an alloy of aluminum and one or more of titanium, zirconium, tantalum, niobium, and hafnium.

FIG. 1 shows a specific embodiment of the present invention. The capacitor element 7 is shown in detail in FIG. 1 is 90μ
This is a capacitor electrode in which a dielectric film is formed by a chemical conversion treatment after etching an aluminum foil having a thickness of m. 2 is a solid electrolyte layer using a conductive polymer, 3 is a cover
Bon layer 4 is a silver paste layer. Reference numeral 5 is a joint portion with the external electrode lead-out lead 9, and 6 is an insulating masking resin, which is intended to isolate the external electrode lead. This external electrode lead is the case where the lead frame is used as it is. However, in some cases, the capacitor electrode and the internal lead are used.
In some cases, a lead frame serving as an external electrode lead may be connected via a lead. Reference numeral 8 in FIG. 1 is a cathode lead terminal. The cathode lead terminal 8 is formed by stacking two elements 7 in directions opposite to each other, and is connected to the element 8 with a silver paste at a substantially central portion thereof so as to be orthogonal to the element 8. The anode electrode lead terminal 9 and the cathode electrode lead terminal 8 are formed by using a lead frame as it is, and applying a resin sheath 10 by a transfer mold, followed by cutting and forming into a predetermined shape. And as shown in FIG. FIG. 2 shows a completed perspective view of the product of the present invention.

[0008]

As described above, with the structure shown in FIG. 1, a chip-type solid electrolytic capacitor having excellent high-frequency characteristics and a four-terminal structure having excellent noise absorption capability can be realized. Depending on how the circuit is assembled, it can be applied as a capacitor for one element and a capacitor for two elements.
There are some of great practical value.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an internal structure of an embodiment of a chip type solid electrolytic capacitor of the present invention.

FIG. 2 is a perspective view of a chip type solid electrolytic capacitor of the present invention.

FIG. 3 is an explanatory view of a capacitor element used in one embodiment of the chip type solid electrolytic capacitor of the present invention.

FIG. 4 is a structural explanatory view of a conventional chip type solid electrolytic capacitor.

FIG. 5 is a structural explanatory view of a chip type solid electrolytic capacitor using a tantalum sintered body.

[Explanation of symbols]

 1: Capacitor Electrode 2: Solid Electrolyte Layer 3: Carbon Layer 4: Silver Paste Layer 5: Joint with External Electrode Lead 6: Masking Resin 7: Capacitor Element 8: Cathode Lead Terminal 9: Anode Lithium -Terminal 10: Resin exterior

Claims (2)

[Claims] 1. A solid electrolytic capacitor obtained by using an aluminum or aluminum alloy electrode plate, etching the electrode to increase the effective area, and then sequentially forming an anodized film layer, a solid electrolyte layer and a cathode conductive layer. Two elements are used, the anode leads are led out in the opposite directions to the left and the right, and the cathode leads are led out from the junction of the two elements before and after the element at an angle of about 90 degrees with respect to the anode lead. A chip-type solid electrolytic capacitor characterized in that 2. The chip-type solid electrolytic capacitor according to claim 1, wherein the aluminum alloy electrode is an alloy of aluminum and one or more of titanium, zirconium, tantalum, niobium, and hafnium.