JP2009065140A - Solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor with very low ESL required for an accelerating CPU and an electronic apparatus having ever improving performance. <P>SOLUTION: This solid electrolytic capacitor is provided with a capacitor element equipped with an anode part, a cathode part, and a dielectric coat disposed between the anode part and the cathode part, an anode lead frame, a cathode lead frame, and a wrapping resin to cover the capacitor element, at least a part of the anode lead frame, and at least a part of the cathode lead frame. The anode lead frame has a bent part, an anode part bonding part to bond the anode part, and an anode side bottom face part a part of which is exposed on the bottom face of the solid electrolytic capacitor, and the cathode lead frame has a bent part, a cathode part loading part to load the cathode part, a cathode side bottom face part a part of which is exposed on the bottom face of the solid electrolytic capacitor, and the thickness of the wrapping resin between the anode bonding part and the anode side bottom face part, and the thickness of the wrapping resin between the cathode loading part and the cathode side bottom face part are not more than 0.3 mm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solid electrolytic capacitor that requires and has a very low ESL (equivalent series inductance) in high-speed CPUs and high-performance electronic devices.

In order to achieve digitalization and high performance of electronic devices, CPUs and the like have become faster. For this reason, capacitors used in electronic devices are also required to have high performance, and even if the electrode structure is a lead frame type, a very low ESL (equivalent series inductance) of 1 nH or less, which is the same as the bottom electrode type, is required.

  A conventional solid electrolytic capacitor having an electrode structure of a lead frame type has the following shape. That is, as shown in FIG. 3, a dielectric film 11, a solid electrolyte layer 2, and a cathode lead layer 21 (including a carbon layer and a silver paste layer) are sequentially formed on the surface of an aluminum foil 1 which is a metal having a valve action. Thus, the capacitor element 30 having the anode lead portion 10 and the cathode portion 20 is manufactured. Next, as shown in FIG. 7, a plurality of capacitor elements 30 are laminated, and the anode lead portion 10 and the anode lead frame 12 are resistance welded. The cathode lead frame 24 is connected to the cathode lead portion 21 via the conductive adhesive 23, and finally covered with the exterior resin 4, and then the anode and cathode lead frames are arranged along the exterior resin. A solid electrolytic capacitor was produced by bending.

  Alternatively, as shown in FIG. 8, a capacitor element having a dielectric film 11, a solid electrolyte layer 2, and a cathode lead layer 21 (including a carbon layer and a silver paste layer) on the surface of a sintered body 13 to which the anode lead portion 10 is attached. The anode lead frame 12 is connected to the anode lead portion 10 of the capacitor element 30, and the cathode lead frame 24 is connected to the cathode lead portion 21 via the conductive adhesive 23. Finally, the outer lead resin 4 is coated. Then, the anode and cathode lead frames were bent along the exterior resin to produce a solid electrolytic capacitor.

Furthermore, a bottom electrode type electrode has been proposed as a low ESL type, and there is one as shown in FIG.
Japanese Patent Laid-Open No. 11-135367 JP-A-8-293436

  By the way, the lead frame type solid electrolytic capacitor of FIG. 7 is drawn from the center of the capacitor element in which the anode and cathode lead frames are laminated to the outside of the exterior resin, and is bent along the exterior resin to be the bottom surface of the solid electrolytic capacitor. It extends to.

  For this reason, the anode and cathode lead frames are long, and a very low ESL (equivalent series inductance) equivalent to that of the bottom electrode type of 1 nH or less required for speeding up of the CPU or the like cannot be achieved.

  Further, in order to shorten the anode and cathode lead frames, it has been considered to connect the lead frame to the bottom surface of the bottom side of the capacitor element 30 laminated as shown in FIG. 10, but the bent portions are raised because the bent portions are short. As a result, the shape did not conform to the exterior resin, the lead frame length was not shortened, and low ESL could not be achieved.

  Further, although the ESL value can be reduced to 1 nH or less for the lower surface electrode type as shown in FIG. 9, the cost increases because it is necessary to remove the surface of the exposed surface portion of the lower surface electrode, for example, the exterior resin is difficult to prevent the protrusion There was a big problem.

  A first invention includes a capacitor element including an anode part, a cathode part, and a dielectric film disposed between the anode part and the cathode part, an anode lead frame connected to the anode part, a cathode part, A solid electrolytic capacitor comprising: a cathode lead frame to be connected; and an exterior resin covering at least a part of the capacitor element and the anode lead frame and at least a part of the cathode lead frame. The anode lead frame has a bent part, an anode part joined part to be joined to the anode part, and an anode side bottom part that is partially exposed on the bottom face of the solid electrolytic capacitor, and the cathode lead frame is folded. A curved portion, a cathode portion mounting portion on which the cathode portion is mounted, and a cathode side bottom surface portion partially exposed on the bottom surface of the solid electrolytic capacitor, between the anode portion bonding portion and the anode side bottom surface portion The thickness of the exterior resin is 0.3 mm or less, and the thickness of the exterior resin between the cathode portion mounting portion and the cathode side bottom surface portion is 0.3 mm or less.

  The anode part may comprise a valve action metal foil, the dielectric film may be an oxide film of the valve action metal, and the cathode part may comprise a solid electrolyte layer and a cathode lead layer sequentially formed on the dielectric film.

  When the dimension A in FIG. 1 is 0.3 mm or less, the lead frame lead-out distance from the capacitor element can be shortened, so that a characteristic with an ESL of 1 nH or less can be realized. Therefore, an ESL value equivalent to that of the lower surface electrode type can be realized with the lead frame type.

Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated. In the drawing, the capacitor elements are laminated, but the present invention can be similarly applied without lamination.
Embodiment 1
Embodiments of the present invention will be described in detail below. FIG. 3 shows the structure of the capacitor element, and FIG. 1 shows the structure of the solid electrolytic capacitor of the present invention.

  First, an aluminum foil 1 which is a valve metal cut out into a plate shape is formed first, and then the aluminum foil 1 is subjected to electrolytic conversion treatment with a 0.01 to 2 wt% phosphoric acid aqueous solution or adipic acid aqueous solution, etc. A dielectric film 11 is formed.

  Next, the aluminum foil on which the dielectric film 11 is formed is immersed in a predetermined position in a chemical polymerization solution composed of 3,4-ethylenedioxythiophene, iron (III) P-toluenesulfonate, and 1-butanol. A solid electrolyte layer 2 made of 3,4-ethylenedioxythiophene, which is a conductive polymer, is formed on the dielectric film 11.

  Here, the solid electrolyte layer 2 may be a TCNQ complex salt, a conductive polymer such as polypyrrole, polyfuran, polyaniline, or a derivative thereof. Further, a part of the dielectric film 11 may be masked and the aluminum foil 1 may be immersed in the entire surface.

  Next, a carbon layer is formed on the solid electrolyte layer 2 by immersing or coating the aluminum foil 1 formed up to the solid electrolyte layer 2 as a cathode lead layer 21 in a solution obtained by diffusing carbon powder in an aqueous solution or an organic solvent. Then, a silver paste layer is formed on the carbon layer to produce the capacitor element 30.

  Here, as shown in FIG. 3, the portion where the dielectric film 11 is formed is the portion where the anode lead portion 10, the solid electrolyte layer 2, and the cathode lead layer 21 (including the carbon layer and the silver paint layer) are formed as the cathode. Part 20.

  Next, as shown in FIG. 1, a conductive adhesive 23 is applied on the cathode lead layer 21 and laminated so that the anode lead portion 10 and the cathode portion 20 of the capacitor element 30 face each other. Further, the cathode lead frame 24 in which the bending groove 5 is formed in advance is also connected.

  Further, the anode lead frames 12 having the bending grooves 5 formed beforehand are connected to each other by spot welding or laser welding.

Next, a part of the anode lead frame 12 and the cathode lead frame 24 is exposed and sealed with the exterior resin 4 using a mold, and then the anode lead frame 12 and the cathode lead frame along the exterior resin 4. 24 is bent and completed as an external terminal. Here, either one of the anode and the cathode lead frame is effective, but the most effective effect is obtained by inserting a bending groove in both.
[Embodiment 2]
In the second embodiment of the present invention, the anode lead frame 12 and the cathode lead frame 24 in the bending groove 5 of the first embodiment are the first fold in which the anode and cathode lead frame are exposed from the exterior resin 4. Forming one bending groove 5 in the extending portion extending from the bent portion toward the bottom surface of the solid electrolytic capacitor, applying heat-resistant tape to the anode and / or cathode lead frame, and then placing it in a mold This was prepared in the same manner as in Embodiment 1 except that the exterior resin was injected.

This is because the distance of A is set to zero so that the resin does not flow to the bottom surface side of the solid electrolytic capacitor of the anode and / or cathode lead frame. However, even if the resin wraps around a little, the lead frame is further bent from above, so that no problem occurs when soldering without removing the wrapping resin.
[Embodiment 3]
In the third embodiment of the present invention, the fixing agent 6 is applied between the exposed portion where the anode lead frame 12 and the cathode lead frame 24 of the first embodiment are exposed to the outside from the exterior resin 4 and the exterior resin. Except for the above, it was produced in the same manner as in Embodiment 1.

Example 1
The solid electrolytic capacitor of Example 1 was manufactured in the same manner as described in the first embodiment. The dimension A in FIG. 1 was 0.3 mm, and the bending groove 5 was formed by an anode lead. For each of the frame 12 and the cathode lead frame 24, one was formed in each of the first bent portion and the second bent portion. Here, the bending groove 5 can be similarly formed by etching or laser processing.

  Further, the anode lead frame 12 and the cathode lead frame 24 were both made of a copper-based material with a thickness of 0.11 mm. The following examples and conventional examples were used in the same manner.

  As shown in FIG. 4, when the bending fulcrum is provided in the bending groove by providing the bending groove 5, the bent part and the non-bent part do not press each other. It can be bent without. Furthermore, since the part removed by processing is added again by bending, ESR is unlikely to deteriorate.

(Example 2)
The solid electrolytic capacitor of Example 2 was manufactured in the same manner as described in the first embodiment. The A dimension was 0.2 mm, and the number of bending grooves 5 was the same as in Example 1.

(Example 3)
The solid electrolytic capacitor of Example 3 was manufactured in the same manner as described in the first embodiment. The A dimension was 0.1 mm, and the number of bending grooves 5 was the same as in Example 1. did.

Example 4
The solid electrolytic capacitor of Example 4 was manufactured in the same manner as described in the second embodiment. The dimension A was 0 mm (FIG. 2), and the bending groove 5 was formed of an anode lead frame 12 and a cathode. One piece was formed in each of the extended portions 25 of the lead frame 24, and as shown in FIG. 2 (c), a wedge shape was formed, and the tip angle was 90 degrees. In this case, the bent part and the non-bent part come into contact with each other, and the bent part and the non-bent part do not press each other, so that there is no floating.

  Here, the wedge shape and the tip angle are set to 90 degrees, but more preferably larger than 90 degrees. This is because there is a margin in the bent state as shown in FIGS.

(Example 5)
The solid electrolytic capacitor of Example 5 was manufactured in the same manner as described in Embodiment 3, and both lead frames were fixed to the exposed portions of the anode lead frame 12 and the cathode lead frame 24 from the exterior resin. For this purpose, an epoxy adhesive as the fixing agent 6 was applied between the exterior resin and the exterior resin. As a result, the ESL characteristics hardly change, and further, unnecessary force is not applied to the first and second bent portions of both lead frames, thereby improving the reliability.

(Conventional example 1)
The solid electrolytic capacitor of Conventional Example 1 is produced by bending the anode lead frame 12 and the cathode lead frame 24 without forming the bending groove 5 as shown in FIG. 7, and the dimension A is 0.46 mm. .

  In this case, the bent portion is wide so that it can be bent, but the length of the lead frame is long, so the ESL is large.

(Conventional example 2)
The solid electrolytic capacitor of Conventional Example 2 is produced by bending the anode lead frame 12 and the cathode lead frame 24 without forming the bending groove 5 as shown in FIG. 7, and the dimension A is 0.4 mm. .

  When the dimension A was made smaller than this, the bent portion was swollen and could not be bent along the exterior resin.

  Table 1 shows the measurement results of the ESL characteristics in the present invention and the conventional example.

  The sample is 2 WV-100 μF, and the measuring device is an ESL measurement value at 10 MHz and 40 MHz by Agilent Precision Impedance Analyzer 4294A.

  In the conventional example, the dimension A cannot be 1 nH for both 0.46 mm and 0.4 mm. If the dimension A is smaller than 0.4 mm, the anode lead frame 12 and the cathode lead frame 24 are both bent to cause floating and the like. And the ESL value could not be cut by 1 nH.

  According to the present invention, by forming the bending groove 5, even when the dimension A is 0.3 mm or less, it can be bent along the outer shape resin 4 without being lifted at the time of bending, and the value of ESL is 1 nH. The lead frame type solid electrolytic capacitor can achieve an ESL value equivalent to that of the bottom surface type solid electrolytic capacitor. Furthermore, the dimension A was zero.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiment but by the scope of claims for patent, and is intended to include all modifications without equivalent meaning and scope to the scope of claims for patent.

1A is a perspective view showing a solid electrolytic capacitor according to Example 1 of the present invention, FIG. 2B is a cross-sectional view taken along X-X ′, and FIG. 1A is a perspective view showing a solid electrolytic capacitor according to Example 1 of the present invention, FIG. 2B is a cross-sectional view taken along X-X ′, and FIG. It is sectional drawing which cut | disconnected and expanded the center of the foil-shaped capacitor | condenser element of this invention. (A) Enlarged view of the bending groove of the lead frame of the present invention, (b) The lead frame is bent 90 degrees. (A) The shape of the lead frame of the present invention is wedge-shaped and the leading end angle of the bending groove is 90 degrees and bent 90 degrees. (B) The lead frame of the present invention is wedge-shaped and bent. It is the figure bent at 90 degree | times, making the front-end | tip angle of a groove | channel 110 degree | times. It is sectional drawing of the solid electrolytic capacitor which apply | coated the fixing agent by Example 5 of this invention. It is sectional drawing of the conventional solid electrolytic capacitor. It is sectional drawing of the conventional solid electrolytic capacitor. It is sectional drawing of the conventional bottom electrode type solid electrolytic capacitor. It is sectional drawing of the conventional solid electrolytic capacitor.

Explanation of symbols

1 Aluminum foil, 10 anode lead part, 11 dielectric coating layer, 12 anode lead frame, 13 sintered body, 2 solid electrolyte layer, 20 cathode part, 21 cathode lead layer, 23 conductive adhesive, 24 cathode lead frame, 25 Extension, 30 Capacitor element, 4 Exterior resin, 5 Bending groove, 6 Fixing agent, 71 Bottom electrode type anode, 72 Bottom electrode type cathode

Claims (2)

A capacitor element comprising an anode part, a cathode part, and a dielectric film disposed between the anode part and the cathode part;
An anode lead frame connected to the anode part;
A cathode lead frame connected to the cathode portion;
A solid electrolytic capacitor comprising the capacitor element, an exterior resin covering at least a part of the anode lead frame and at least a part of the cathode lead frame,
The anode lead frame has a bent part, an anode part joining part joined to the anode part, and an anode side bottom part exposing a part thereof on the bottom surface of the solid electrolytic capacitor,
The cathode lead frame has a bent portion, a cathode portion mounting portion for mounting the cathode portion, and a cathode side bottom portion exposing a part thereof on the bottom surface of the solid electrolytic capacitor,
The thickness of the exterior resin between the anode part bonding part and the anode side bottom part is 0.3 mm or less, and the thickness of the exterior resin between the cathode part mounting part and the cathode side bottom part is 0.3 mm. Solid electrolytic capacitor that is:   The anode portion includes a valve action metal foil or a valve action metal sintered body, the dielectric film is an oxide film of the valve action metal, and the cathode portion is a solid electrolyte sequentially formed on the dielectric film. The solid electrolytic capacitor according to claim 1, further comprising a layer and a cathode lead layer.