JP2010177367A - Electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic capacitor which has superior ESL without raising the ESR. <P>SOLUTION: In the electrolytic capacitor 1, a positive electrode foil, a negative electrode foil, and a separator paper are disposed in such a mode that one separator paper is pinched between the positive electrode foil and the negative electrode foil, and the positive electrode foil is pinched between one separator paper and the other separator paper, and a core is rotated to a predetermined direction while one end sides of the positive electrode foil, the negative electrode foil, and the separator paper are pinched into the core, thereby the positive electrode foil, the negative electrode foil, and the like are wound up from one end side to form a capacitor element 2, and then a winding end 2a comes to have a substantially elliptic shape. A positive electrode lead wire 8 and a negative electrode lead wire 9 are disposed substantially on a short axis 41 of the winding end 2a of the substantially elliptic shape. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrolytic capacitor, and more particularly to an electrolytic capacitor in which an anode foil and a cathode foil are wound.

  One form of electrolytic capacitor is an electrolytic capacitor formed by winding an anode foil and a cathode foil with a separator interposed therebetween. An aluminum foil with a dielectric oxide film is applied as the anode foil, and an aluminum foil is applied as the cathode foil.

  Here, how to wind up the anode foil and cathode foil of the conventional electrolytic capacitor will be described. As shown in FIG. 6, a strip-shaped anode foil 103, a cathode foil 104, and two separator papers 105, 106 each having a predetermined length are prepared, and one of these is provided between the anode foil 103 and the cathode foil 104. The separator paper 106 is sandwiched and the anode foil 103 is sandwiched between one separator paper 106 and the other separator paper 105. Anode lead wire 108 and cathode lead wire 109, which serve as an anode terminal and a cathode terminal in the completed electrolytic capacitor, are connected to anode foil 103 and cathode foil 104, respectively.

  Next, one end of each of the disposed anode foil 103, cathode foil 104, and separator papers 105 and 106 is sandwiched between the cores 131a and 131b, and the cores 131a and 131b are rotated in a predetermined direction in this state, thereby The anode foil 103, the cathode foil 104, and the like are wound from the side.

  Thus, the capacitor element 102 is formed as shown in FIG. Next, the capacitor element 102 is subjected to a predetermined treatment such as a chemical conversion treatment on the cut surface of the anode foil or the like, and then the capacitor element 102 is accommodated in an aluminum case 120 having a predetermined size. As shown in FIG. 8, the electrolytic capacitor 1 is completed. Note that there is Patent Document 1 as a document disclosing this type of electrolytic capacitor.

Japanese Patent Laid-Open No. 11-345749

  However, the conventional electrolytic capacitor has the following problems. In recent years, in information communication systems such as personal computers, the operating frequency tends to reach a high frequency range. All capacitors including electrolytic capacitors have an inductance component called Equivalent Series Inductance (ESL). This ESL increases as the frequency increases, and the capacitor cannot function as a capacitor. For this reason, lower ESL is calculated | required for the electrolytic capacitor used in a high frequency area | region. Further, the capacitor has a resistance component called Equivalent Series Resistance (ESR), and a lower ESR is required.

  The ESL in the electrolytic capacitor corresponds to an inductance component of the shortest distance in which current flows in the electrolytic capacitor, and is determined mainly by the interval (pitch P) between the anode lead wire and the cathode lead wire (see FIG. 8). This pitch depends on the distance (cutter distance) from the end of the positive (negative) foil to the crimping position (connection position) of the positive (negative) lead wire. In order to minimize the ESR value, the positive (negative) lead wire is usually connected to the center in the longitudinal direction with respect to the positive (negative) electrode foil.

  However, when the pitch is shortened and the cutter distance is shortened, there is a problem that the value of ESR becomes high or the capacitance decreases. Further, the external appearance of the electrolytic capacitor becomes a columnar shape in relation to the shape of the winding cores 131a and 131b used when winding the anode foil, the cathode foil, and the like. For this reason, it has been difficult to shorten the pitch in terms of design.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an electrolytic capacitor excellent in ESL without increasing ESR.

  The electrolytic capacitor according to the present invention is an electrolytic capacitor in which an anode foil and a cathode foil are wound, and an anode foil and a cathode lead wire connected to an anode lead wire and extending in a strip shape are connected to and extend in a strip shape. A capacitor element formed by winding a cathode foil is provided. The anode lead wire is connected to the center in the longitudinal direction of the anode foil. The cathode lead wire is connected to the center in the longitudinal direction of the cathode foil. In the winding end face of the wound anode foil and cathode foil in the capacitor element, the length in the first direction is shorter than the length in the second direction intersecting the first direction, and the anode lead wire and the cathode The lead wire is disposed in parallel with the first direction.

  According to the electrolytic capacitor of the present invention, the length of the first direction is shorter than the length of the second direction intersecting the first direction at the winding end surfaces of the wound anode foil and cathode foil. The anode lead wire and the cathode lead wire are arranged in parallel to the first direction, so that ESL can be reduced. And since the anode lead wire is connected to the center in the longitudinal direction of the anode foil and the cathode lead wire is connected to the center in the longitudinal direction of the cathode foil, an increase in ESR is also suppressed.

  More specifically, on the winding end surface, the short axis is arranged in the first direction and the long axis is arranged in the second direction, and the anode lead wire and the cathode lead wire are arranged on the short axis. It is preferable.

  The shape of such a winding end surface is preferably an elliptical shape or a track shape.

It is a perspective view for demonstrating the winding process of the electrolytic capacitor which concerns on embodiment of this invention. In the same embodiment, it is a top view which shows the winding-up process of the anode foil and cathode foil by a winding core. FIG. 5 is an exploded perspective view showing a wound capacitor element in the same embodiment. In the same embodiment, it is a top view which shows the winding end surface of the capacitor | condenser element in an electrolytic capacitor. In the same embodiment, it is a side view which shows the electrolytic capacitor for demonstrating ESL. In the conventional electrolytic capacitor, it is a top view which shows the winding-up process of the anode foil and cathode foil by a winding core. It is a disassembled perspective view which shows the capacitor | condenser element in the conventional electrolytic capacitor wound. It is a top view which shows the winding end surface of the capacitor | condenser element in the conventional electrolytic capacitor.

  An electrolytic capacitor according to an embodiment of the present invention will be described. First, the manufacturing process will be described.

  As shown in FIG. 1, a strip-shaped anode foil 3, a cathode foil 4, and two separator papers 5 and 6 each having a predetermined length are prepared, and one of these is provided between the anode foil 3 and the cathode foil 4. The separator paper 6 is sandwiched and the anode foil 3 is disposed between the one separator paper 6 and the other separator paper 5.

  An anode lead wire 8 is connected to the center of the anode foil 3 in the longitudinal direction via a lead tab terminal 7. A cathode lead wire 9 is connected to the center of the cathode foil 4 in the longitudinal direction via a lead tab terminal 7. An aluminum foil having a dielectric oxide film formed thereon is applied as the anode foil 3, and an aluminum foil is applied as the cathode foil.

  Next, as shown in FIG. 2, the one end side of the arranged anode foil 3, the cathode foil 4, and the separator papers 5 and 6 is sandwiched between the winding cores 31a and 31b. At this time, a winding core that is flatter than the conventional winding core is applied as the winding cores 31a and 31b. By rotating the winding cores 31a and 31b in a predetermined direction (arrow) with the anode foil 3 and the cathode foil 4 sandwiched between the winding cores 31a and 31b, the anode foil 3 and the cathode foil 4 and the like are formed from one end side. As a result, the capacitor element 2 is formed as shown in FIG.

  Next, the capacitor element 2 is subjected to a predetermined process such as a chemical conversion process on a cut surface such as an anode foil. Thereafter, the processed capacitor element is housed in an aluminum case 20 (see FIG. 5) having a predetermined size, and the electrolytic capacitor 1 is completed as shown in FIG.

  As shown in FIG. 4, in the electrolytic capacitor formed by applying a flat winding core, the winding end 2a has a substantially elliptical shape. The anode lead wire 8 and the cathode lead wire 9 are arranged on the substantially short axis 41 of the substantially elliptical winding end surface 2a, and the pitch P between the anode lead wire 8 and the cathode lead wire 9 has the same capacity. This is shorter than the pitch of a conventional electrolytic capacitor having a substantially circular winding end surface (see FIG. 8).

  ESL (ratio) was estimated about the electrolytic capacitor which concerns on the invention example. As shown in FIG. 5, the pitch of the anode lead wire 8 and the cathode lead wire 9 in the electrolytic capacitor 1 is P, and the thickness of the sealing rubber packing 21 (the length of the lead wire sealed in the sealing rubber packing). If L is L, the ESL ratio of the two electrolytic capacitors to be compared can be empirically estimated by the following equation.

ESL ratio (%) = ((L × 2 + P) / (L ₀ × 2 + P ₀ )) × 100
P ₀ and L ₀ indicate the pitch of the electrolytic capacitor as a reference and the thickness of the sealing rubber. Here, the pitch P of the electrolytic capacitor according to the example is 1.75 mm, the thickness L of the sealing rubber is 2.37 mm, the pitch P ₀ of the conventional electrolytic capacitor is 3.5 mm, and the thickness L of the sealing rubber. _{If 0} is 2.37 mm, the ESL ratio is estimated to be 79%.

  Therefore, in the electrolytic capacitor according to the embodiment, the winding end surface is substantially elliptical, and the anode lead wire 8 and the cathode lead wire 9 are arranged on the substantially minor axis of the substantially elliptical winding end surface. It has been found that it can be reduced to about 79% of the ESL of the conventional electrolytic capacitor.

  Further, the anode lead wire 8 is connected to the center of the anode foil 3 in the longitudinal direction, and the cathode lead wire 9 is connected to the center of the cathode foil 4 in the longitudinal direction. It can be suppressed.

  In the above-described embodiments and examples, an electrolytic capacitor in which a flat winding core is applied and the winding end surface is substantially elliptical has been described as an example. However, as the shape of the winding end surface, the first If the electrolytic capacitor is such that the length in the direction is shorter than the length in the second direction intersecting with the length and the anode lead wire and the cathode lead wire are arranged in parallel to the first direction, the above-mentioned It is not limited to the electrolytic capacitor formed by the method. Further, the shape of the winding end face is not limited to an elliptical shape, and may be a shape such as a field track, for example.

  DESCRIPTION OF SYMBOLS 1 Electrolytic capacitor, 2 Capacitor element, 2a Winding end surface, 3 Anode foil, 4 Cathode foil, 5 Separator paper, 6 Separator paper, 7 Lead tab terminal, 8 Anode lead wire, 9 Cathode lead wire, 20 Aluminum case, 21 Sealing Rubber packing, 31a core, 31b core, 41 short axis.

Claims (3)

An electrolytic capacitor in which an anode foil and a cathode foil are wound,
A capacitor element formed by winding an anode foil connected to the anode lead wire and extending in a strip shape and a cathode foil connected to the cathode lead wire and extending in a strip shape,
The anode lead wire is connected to the longitudinal center of the anode foil;
The cathode lead wire is connected to the longitudinal center of the cathode foil;
In the winding end face of the wound anode foil and cathode foil in the capacitor element, the length in the first direction is shorter than the length in the second direction intersecting the first direction,
The electrolytic capacitor in which the anode lead wire and the cathode lead wire are arranged in parallel to the first direction. In the winding end surface, a short axis is arranged in the first direction, and a long axis is arranged in the second direction,
The electrolytic capacitor according to claim 1, wherein the anode lead wire and the cathode lead wire are disposed on the minor axis.   3. The electrolytic capacitor according to claim 1, wherein the winding end surface has one of an elliptical shape and a track shape.

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