JP2002299177A - Multiple terminal solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic capacitor having low-ESR and low- impedance characteristics in the high-frequency range of 100 kHz or higher. SOLUTION: A multiple terminal solid electrolytic capacitor unit comprises a first electrode foil, a second electrode foil laminated on the first electrode foil via a first separator in-between, and a third electrode foil laminated on the second electrode foil via a second separator in-between. The electrolytic capacitor unit is formed by polymerizing a polymerable monomer by oxidizer to form a conductive polymer on the first separator and the second separator, forming a first electrode lead-out means at the upper part or lower part of a side portion of the first electrode foil, forming a second electrode lead-out means on the second electrode foil, and forming a third electrode lead-out means at the upper part or lower part of the third electrode foil on the side opposite the side, where the first electrode lead-out means of the first electrode foil is formed. The third electrode lead-out means is selected according to the vertical positional relation to the first electrode lead-out means, and a diagonal line connecting the first electrode lead-out means and the third electrode lead-out means crosses the second electrode foil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor using a conductive organic solid electrolyte, and more particularly to a solid electrolytic capacitor having low ESR and low impedance characteristics.

[0002]

2. Description of the Related Art Hitherto, a multilayer capacitor has been proposed as a solid electrolytic capacitor using a conductive organic solid electrolyte. In the structure of these capacitors, the arrangement and number of terminals are often arbitrary. On the other hand, in recent years, the frequency of electronic devices such as CPUs using capacitors has been increased, and accordingly, low ESR has been achieved in a high frequency region of 100 kHz or more.
The demand for electrolytic capacitors having low impedance characteristics is increasing.

[0003]

FIG. 5 shows an example of a conventional solid electrolytic capacitor using a conductive organic solid electrolyte.
The solid electrolytic capacitor comprises a cathode foil 1, an anode foil 3 and a cathode foil 2.
Are laminated via the separators 4 and 6, respectively.

The cathode foil 1 has a cathode lead wire 11 projecting from the lower left end, the anode foil 3 has an anode lead wire 18 projecting from the upper left end, and the cathode foil 2 has a cathode lead wire 8 extending to the right. It protrudes from the lower end.

[0005] Separators 4 and 6 are impregnated with 3,4-ethylenedioxythiophene and an oxidizing agent to form poly-3,4-
Ethylenedioxythiophene is formed by polymerization.

Table 1 shows the frequency characteristics of the impedance of the solid electrolytic capacitor having the above configuration. It can be seen that the impedance increases as the frequency increases. This impedance is not a sufficiently low value as the impedance required in recent years, and it is necessary to further reduce the impedance.

Therefore, an object of the present invention is to provide a 100 kHz
An object of the present invention is to provide an electrolytic capacitor having low ESR and low impedance characteristics in the above high frequency region.

[0008]

In order to achieve the above object, a multi-terminal solid electrolytic capacitor according to the present invention comprises:
An electrode foil, a second electrode foil laminated on the first electrode foil via a first separator, and a third electrode foil laminated on the second electrode foil via a second separator; A polymerizable monomer is polymerized with an oxidizing agent on the second electrode foil to form a conductive polymer, and a first electrode lead means is provided on an upper or lower side of the first electrode foil, and a second electrode foil is provided on the second electrode foil. Providing a two-electrode withdrawing means, further providing third electrode withdrawing means on the third electrode foil on the upper or lower side of the first electrode foil on the side facing the mounting side of the first electrode withdrawing means, The means is selected in a vertical positional relationship with the first electrode extraction means, and a hatched line connecting the first electrode extraction means and the third electrode extraction means is a second line.
It is characterized by including a multi-terminal solid electrolytic capacitor unit that traverses the electrode foil.

That is, a line segment obtained by projecting a line segment connecting the cathode extraction means provided on the cathode foil and the cathode extraction means provided on another cathode foil to the anode foil obliquely crosses the anode foil. Also, if the shape of the electrode foil is other than circular or square,
It is divided vertically and horizontally by a line passing through the central axis to determine the vertical position and the horizontal position.

A fourth electrode foil is further laminated on the third electrode foil with a third separator interposed therebetween, and a fourth electrode foil is provided on the upper or lower portion of the second electrode foil on the side facing the mounting side of the electrode lead-out means. Four-electrode extraction means is provided, and the fourth electrode extraction means is selected in a vertical positional relationship with the second electrode, and a hatched line connecting the fourth electrode extraction means and the second electrode extraction means indicates a third electrode foil. You can also cross.

[0011] Fifth electrode extraction means is provided on the upper or lower side of the second electrode foil on the side facing the mounting side of the electrode extraction means, and the fifth electrode extraction means is provided in a vertical positional relationship with the second electrode. It is desirable that the oblique line connecting the first electrode extracting means and the third electrode extracting means intersects with the oblique line connecting the second electrode extracting means and the fifth electrode extracting means.

A sixth electrode lead means is provided on the upper or lower side of the first electrode foil on the side facing the mounting side of the electrode lead means, and the sixth electrode lead means is provided in a vertical positional relationship with the first electrode. A seventh electrode extracting means provided on an upper portion or a lower portion of the second electrode foil on a side opposite to the mounting side of the electrode extracting means, wherein the seventh electrode extracting means is provided in a vertical positional relationship with the second electrode; Eighth electrode extraction means is provided on the upper or lower side of the three-electrode foil on the side facing the mounting side of the electrode extraction means, and the eighth electrode extraction means is provided in a vertical positional relationship with the third electrode. A ninth electrode withdrawing means is provided on the upper or lower side of the foil opposite to the side where the electrode withdrawing means is attached, and the ninth electrode withdrawing means is provided in a vertical relationship with the fourth electrode, and the sixth electrode withdrawal is provided. Means and eighth electrode extraction hand Can be shaded connecting bets across the second electrode foils, diagonal line connecting the said seventh electrode lead-out means and the ninth electrode lead-out means for reducing the impedance to cross the third electrode foil.

[0013] The polymerizable monomer can be a thiophene derivative. Also, the conductive polymer can be a polymer of a thiophene dielectric. Further, the thiophene derivative is
It can be 3,4-ethylenedioxythiophene (EDT). The chemical formula of the thiophene dielectric is shown below.

[0014]

Embedded image

In the above formula, X is O or S. X
A is alkylene or polyoxyalkylene when is O. When at least one of X is S,
A is alkylene, polyoxyalkylene, substituted alkylene, substituted polyoxyalkylene. Here, the substituent is an alkyl group, an alkenyl group, or an alkoxy group. And, the polymer of the thiophene dielectric can be poly 3,4-ethylenedioxythiophene (PEDT).

The plurality of solid electrolytic capacitor units may be included in one solid electrolytic capacitor and may be overlapped.

[0017]

Next, a method for manufacturing a solid electrolytic capacitor according to the present invention and a solid electrolytic capacitor obtained by the method will be specifically described with reference to the drawings.

FIG. 1A shows a three-terminal solid electrolytic capacitor according to the present invention. The solid electrolytic capacitor shown in FIG. 1A has a cathode foil 1, a cathode foil 2 laminated on the cathode foil 1 via the separator 4, and an anode foil 3 laminated on the cathode foil 2 via the separator 6. And The separator 4 and the separator 6 impregnate a polymerizable monomer and an oxidizing agent and polymerize the monomer to form a conductive polymer. The cathode foil 1 has a cathode lead 11 projecting from the lower left, and the cathode foil 2 has a cathode lead 8 projecting from the upper right. An anode lead wire 18 is protruded from the anode foil 3 at the upper left. Oblique line 2 connecting cathode lead 8 and anode lead 18
3 crosses the anode foil 3. There are three lead terminals.

Here, an oblique line 23 connecting the cathode lead wire 11 and the cathode lead wire 8 is indicated by a dotted line. FIG. 1B shows FIG. 1 as viewed from the direction A. As shown in FIG. 1B, a cathode lead wire 11 protrudes from the lower left portion of the cathode foil 1, and a cathode lead wire 8 protrudes from the upper right portion of the cathode foil 1. In addition, it is indicated by a diagonal line 23 connecting the cathode lead wire 11 and the cathode lead wire 8. That is, the oblique line 23 crosses the anode foil 3. In the transverse direction, when the electrode foil is rectangular as in this example, it is desirable that diagonal lines be connected diagonally. When the electrode foil has a shape other than a circle or other quadrangular shape, for example, it is preferable that the electrode foil is inclined with respect to the center axis direction of the electrode foil.

A broken line 23 indicates that the impedance and the like of the anode foil 3 are reduced by obliquely crossing the anode foil 3 in a diagonal direction.

The surface of the anode electrode foil 1 was subjected to a chemical conversion treatment to form an oxide film layer made of aluminum oxide on the surface. The surface of the cathode electrode foil 2 was subjected to the same chemical conversion treatment as that of the anode electrode foil 1, and then a titanium nitride film was formed by a cathode arc plasma deposition method. In order to repair the damaged portion or cut surface of the bipolar foil received in the processing step, the oxide film is formed again by performing repair formation in an aqueous solution of ammonium phosphate, and further boric acid for stabilizing the oxide film. Immersion in an aqueous solution.

The capacitor element 12 having the above configuration was impregnated with 3,4-ethylenedioxythiophene and an oxidizing agent. The oxidizing agent was p-
These mixed solutions were prepared using ferric toluenesulfonate.

The impregnation was performed by a method in which the capacitor element 12 was immersed in an impregnation tank containing a fixed amount of the mixed solution. Next, the capacitor element 12 impregnated with the mixed solution was pulled up from the impregnation tank, and was pressed under a pressure of 400 kg / cm ² for 1 hour.
A polymer by a polymerization reaction, that is, a solid electrolyte layer was formed under heating at 50 ° C. for 2 hours.

Further, when the oxidizing agent was left at room temperature, the oxidizing agent remaining in the solid electrolyte layer after the polymerization absorbed moisture in the air, and the repair of the anodic oxide film, that is, re-chemical formation proceeded by the moisture. Through this step, a series of solid electrolyte layer generation steps was completed.

As the anode electrode foil, any valve metal such as aluminum and tantalum may be used, but aluminum is usually used. On the surface of the anode electrode foil, a voltage is applied in an aqueous solution of ammonium borate or the like to form an oxide film layer serving as a dielectric.

The cathode electrode foil may be any material as long as it can electrically connect the lead wire and the electrolyte. In one embodiment of the present invention, aluminum or the like is used. It is preferable to form a titanium nitride film on the surface of the cathode electrode foil because the capacitance increases.

Lead wires for connecting the respective electrodes to the outside are connected to the anode electrode foil and the cathode electrode foil by known means such as stitching and ultrasonic welding. The lead wire is made of aluminum or the like, and is composed of a connection portion with the anode electrode foil and the cathode electrode foil and an external connection portion that performs an electrical connection with the outside, and is led out from an end of the laminated capacitor element.

The anode electrode foil and the cathode electrode foil are subjected to repair formation in a chemical conversion solution and then immersed in a boric acid aqueous solution in order to repair a damaged portion or a cut surface of the film received in the processing step. This stabilizes the oxide film and increases the high withstand voltage.

Although a glass separator is usually used as the separator, as another embodiment, electrolytic paper used for a general electrolytic capacitor can be used. In other words, synthetic fibers, those made by mixing these,
Further, a nonwoven fabric obtained by mixing synthetic fibers and fibers for electrolytic paper or glass fibers can be used. Examples of the synthetic fiber include vinylon fiber, polyester fiber, nylon fiber, rayon fiber and the like. Furthermore, a synthetic resin porous separator can be used. Examples of these synthetic resins include polyamide, polyimide, and aramid. In addition, the said separator is 10-300.
The thickness is 0 μm, preferably 20 to 1500 μm. When a thickness in this range is used, a stable equivalent series resistance can be obtained.

The dimensions of the cathode electrode foil and the anode electrode foil are arbitrary depending on the specifications of the solid electrolytic capacitor to be manufactured. However, the dimensions are such that 3,4-ethylenedioxythiophene and the oxidizing agent penetrate into the center of the lamination. I just need. The separator may have a slightly larger width depending on the dimensions of the cathode electrode foil and the anode electrode foil. In order to obtain a capacitor having the performance of the present invention, the vertical and horizontal dimensions of the cathode electrode foil and the anode electrode foil are usually 10 mm or more, preferably 20 mm or more, and typically 25 to 50 mm.

The capacitor element is preferably formed by laminating a separator between the cathode electrode foil and the anode electrode foil.

By impregnating the capacitor element with 3,4-ethylenedioxythiophene and an oxidizing agent, the 3,4-ethylenedioxythiophene and the oxidizing agent penetrate into the inside of the capacitor element, and Process and mild chemical polymerization reaction that occurs appropriately after infiltration
A polymer of ethylenedioxythiophene, that is, a solid electrolyte layer is formed inside a capacitor element while being held by a separator.

3,4-ethylenedioxythiophene is
It can be obtained by a known production method disclosed in JP-A-2-15611 and the like. Further, the above-mentioned polymer of 3,4-ethylenedioxythiophene is poly3,4-ethylenedioxythiophene polymerized to an extent that it becomes a solid at normal temperature.

As the oxidizing agent, a solution obtained by dissolving ferric p-toluenesulfonate, which is an iron salt of aromatic sulfonic acid, in a butanol solvent is used. As the solvent in the oxidizing agent, a normal organic solvent such as alcohols such as ethanol and butanol can be used.

As a method of impregnating the capacitor element with 3,4-ethylenedioxythiophene and an oxidizing agent, not only a method of immersing the capacitor element in a liquid in which 3,4-ethylenedioxythiophene and the oxidizing agent are mixed in advance, but also
As another embodiment, a method of immersing a capacitor element immersed in 3,4-ethylenedioxythiophene in an oxidizing agent, and a method of immersing a capacitor element immersed in an oxidizing agent in 3,4-ethylenedioxythiophene, Moreover,
A method is also possible in which the immersion operation is replaced by ejection of a solution from a syringe.

The temperature condition during the polymerization is preferably from 20 to 180 ° C. When the polymerization temperature is 20 ° C. or lower, the formation of 3,4-ethylenedioxythiophene does not proceed well, and the capacitance decreases and the equivalent series resistance increases. At a temperature higher than 180 ° C., the decomposition of 3,4-ethylenedioxythiophene occurs, the capacitance decreases, and the equivalent series resistance increases. That is, excellent high-frequency characteristics cannot be obtained.

The pressure condition during polymerization is 30 to 1000 kg /
cm ² , particularly preferably 100 to 600 kg / cm ² .
When the pressure is less than 30 kg / cm ² , the bonding between the polymer and the electrode foil does not proceed well, so that the capacitance is reduced and the equivalent series resistance is increased. Further 1000kg / c
In the case of pressurization higher than m ² , the amount of the polymer and the amount of the produced oxidant are reduced because the amount of the monomer and the oxidizing agent between the electrode foils is reduced, and the equivalent series resistance is increased. That is, excellent high-frequency characteristics cannot be obtained.

Under the above polymerization conditions, a solid electrolyte layer is obtained by advancing the polymerization reaction for 30 minutes or more. The reaction time of this polymerization reaction is preferably 30 minutes or more at which the polymerization reaction can be completely completed.

After the formation of the solid electrolyte layer by the polymerization reaction, the oxide film is repaired, that is, reformed. This step is carried out by applying a formation voltage in the presence of moisture absorbed from the air by the oxidizing agent remaining after the polymerization. At this time, even if an anode foil formed at a high voltage is used, the anode foil can be re-formed at a high voltage, so that a high withstand voltage can be achieved.

FIG. 2 shows a four-terminal solid electrolytic capacitor in which an anode foil 15 is further disposed outside the embodiment of FIG. The steps for the polymerization are the same as those in FIG. 1, and therefore only the differences will be described. The anode foil 15 has an anode lead 16 protruding from the lower right portion. The solid electrolytic capacitor shown in FIG. 2 is obtained by adding an anode foil to the solid electrolytic capacitor shown in FIG. 1, and a hatched line 23 connects the cathode lead 11 and the cathode lead 8.
On the other hand, there is a new oblique line 17 connecting the anode lead 18 and the anode lead 16. The oblique line 23 and the new oblique line 17 are arranged to cross in the same manner as in FIG. That is, it crosses the anode foil 3. On the other hand, the oblique line 17 crosses the cathode foil 2.

As shown in FIG. 2, a solid electrolytic capacitor having a plurality of capacitor unit configurations shown in FIG. 1 is preferable because the capacitance is increased.

FIG. 3 shows a four-terminal solid electrolytic capacitor according to the present invention having two anode foil leads. The steps for the polymerization are the same as those in FIG. 1, and therefore only the differences will be described.

The difference from FIG. 1 is that an anode lead wire 20 protrudes from the anode foil 3.

The solid electrolytic capacitor of FIG. 3 is obtained by projecting an anode lead wire 20 on the anode foil 3 of the solid electrolytic capacitor of FIG. Here, the anode lead wire 20 protrudes from the anode lead wire 18 at a center axis symmetry point of the anode foil 3. That is, in a square as shown in FIG. 3, the impedance is further reduced by providing diagonal leads at both ends of the electrode foil.

FIG. 4 shows a solid electrolytic capacitor having eight terminals with two lead wires projecting from each electrode foil. Since the configuration of the polymerization is the same as that of FIG. 1, only different points will be described. The cathode foil 1 has a cathode lead 11 protruding at the lower left and a cathode lead 12 protruding at the upper right.

Further, the anode foil 3 is laminated via the separator 4. The anode foil 3 has an anode lead 18 projecting from the upper left and an anode lead 20 projecting from the lower right.

Further, the cathode foil 2 is laminated via the separator 6. The cathode foil 2 has a cathode lead 28 projecting from the lower left and a cathode lead 8 projecting from the upper right. Here, the oblique line 2 connecting the cathode lead wire 11 and the cathode lead wire 8
4 crosses the anode foil 3 in the vicinity of the central axis of the anode foil 3. In addition, since the anode foil 3 has the diagonal anode lead 18 and the anode lead 20, the impedance is further reduced. On the other hand, the oblique line 26 connecting the cathode lead wire 12 and the cathode lead wire 28 crosses the anode foil 3.

The anode foil 15 is laminated on the cathode foil 2 via the separator 14. The anode foil 15 has an anode lead 16 projecting from the upper left and an anode lead 32 projecting from the lower right. Here, the anode lead 16 and the anode lead 2
The oblique line 30 connecting 0 crosses the cathode foil 2. Further, an oblique line 27 connecting the anode lead wire 18 and the anode lead wire 32 obliquely intersects near the center axis of the cathode foil 2 and the cathode foil 2. In addition, the cathode lead wire 8 and the lead wire 2
8 are arranged symmetrically with respect to the central axis, the impedance is further reduced.

As shown in FIG. 4, a solid electrolytic capacitor having a plurality of the configuration of the capacitor unit shown in FIG. 3 is preferable because the capacitance is increased.

Test Example Next, the solid electrolytic capacitor according to the present invention shown in FIG. 1, the solid electrolytic capacitor according to the present invention shown in FIG. 3, and the conventional solid electrolytic capacitor shown in FIG. The frequency characteristics of impedance were measured, and the average value was determined. Table 1 shows the results.

[0051]

[Table 1]

The solid electrolytic capacitor according to the present invention shown in FIG. 1 has improved impedance characteristics at 100 kHz or less as compared with the comparative example.

Further, the minimum value of the impedance characteristic at a high frequency is from 500 kHz in the comparative example to 500 kHz in the embodiment.
Hz, and the ESR in this region is also at 0.
It has decreased from 07Ω to 0.03 to 0.06Ω.

That is, it is understood that high-frequency impedance can be reduced by using the multi-terminal solid electrolytic capacitor according to the present invention.

Also, by using PEDT, E
It is possible to realize a solid electrolytic capacitor having a specific property of reducing SR and impedance.

[0056]

As described above, by practicing the present invention, it is possible to provide an electrolytic capacitor having low ESR and low impedance characteristics in a high frequency range of 100 kHz or more.

That is, a first electrode foil, a second electrode foil laminated on the first electrode foil via a first separator, and a third electrode foil laminated on the second electrode foil via a second separator.
An electrode foil, wherein the first separator and the second separator are formed by polymerizing a polymerizable monomer with an oxidizing agent to form a conductive polymer, and a first electrode is formed on an upper or lower side of the first electrode foil. A lead-out means, and a second electrode foil is provided on the second electrode foil.
An electrode lead-out means is provided, and a third electrode lead-out means is further provided on the third electrode foil on an upper or lower side of the first electrode foil on a side opposite to a mounting side of the electrode take-out means, and the third electrode lead-out means comprises: The oblique line connecting the first electrode extraction means and the third electrode extraction means, which is selected in a vertical positional relationship with the first electrode extraction means, traverses the second electrode foil,
First, a low E by impregnating a polymerizable monomer and an oxidizing agent to polymerize the monomer and use a conductive polymer.
Second, a low ESR and low impedance characteristic according to the present configuration can be obtained as well as an SR and low impedance characteristic.

Further, a fifth electrode lead means is provided on the upper or lower side of the second electrode foil on the side opposite to the mounting side of the electrode lead means, and the fifth electrode lead means is vertically positioned with respect to the second electrode. Since the oblique line connecting the first electrode extracting means and the third electrode extracting means and the oblique line connecting the second electrode extracting means and the fifth electrode extracting means intersect with each other, a lower ES is provided.
The effect of R and low impedance characteristics is enhanced.

[Brief description of the drawings]

FIG. 1A is a configuration diagram of a three-terminal solid electrolytic capacitor according to the present invention, and FIG. 1B is a side view of the three-terminal solid electrolytic capacitor according to the present invention as viewed from a direction A. .

FIG. 2 shows another configuration diagram of a four-terminal solid electrolytic capacitor according to the present invention.

FIG. 3 shows another configuration diagram of a four-terminal solid electrolytic capacitor according to the present invention.

FIG. 4 shows another configuration diagram of an eight-terminal solid electrolytic capacitor according to the present invention.

FIG. 5 shows a configuration diagram of a conventional solid electrolytic capacitor.

[Explanation of symbols]

1, 2 Cathode foil 3, 15 Anode foil 8, 11, 12, 28 Cathode lead 18, 20, 16, 32 Anode lead 4, 6, 14, 22 Separator 10, 17, 21, 24, 26, 27, 30, 34 diagonal lines

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01G 9/04 H01G 9/04 328 9/14 9/05 MH

Claims (6)

[Claims] 1. A first electrode foil, a second electrode foil laminated on the first electrode foil via a first separator, and a third electrode laminated on the second electrode foil via a second separator. A conductive polymer is formed by polymerizing a polymerizable monomer with an oxidizing agent on the first separator and the second separator to form a conductive polymer, and a first electrode drawing means is provided on an upper or lower side of the first electrode foil, The second electrode foil is provided with a second electrode extraction means, and the third electrode foil is further provided with a third electrode extraction means on the upper or lower side of the first electrode foil on the side facing the mounting side of the first electrode extraction means. The third electrode lead-out means is selected in a vertical positional relationship with the first electrode lead-out means, and an oblique line connecting the first electrode lead-out means and the third electrode lead-out means crosses the second electrode foil. Multi-terminal solid electrolytic capacitor unit A multi-terminal solid electrolytic capacitor characterized by including: 2. A fifth electrode extraction means is provided on the upper or lower side of the second electrode foil on the side facing the mounting side of the electrode extraction means, and the fifth electrode extraction means is arranged in a vertical positional relationship with the second electrode. 2. The multi-terminal solid electrolytic device according to claim 1, wherein a diagonal line provided between the first electrode extraction unit and the third electrode extraction unit intersects with a diagonal line connecting the second electrode extraction unit and the fifth electrode extraction unit. Capacitors. 3. The multiple terminal solid electrolytic capacitor according to claim 1, wherein the polymerizable monomer is a thiophene derivative. 4. The multi-terminal solid electrolytic capacitor according to claim 3, wherein the conductive polymer is a polymer of a thiophene dielectric. 5. The multi-terminal solid electrolytic capacitor according to claim 3, wherein the thiophene derivative is 3,4-ethylenedioxythiophene (EDT). 6. The polymer of the thiophene dielectric is poly3,
The multi-terminal solid electrolytic capacitor according to claim 5, wherein the capacitor is 4-ethylenedioxythiophene (PEDT).