JP2010212600A - Solid electrolytic capacitor and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor having high volume efficiency, higher connection strength and stable connection with an anode lead part and being capable of being made compact, and to provide a method of manufacturing the same. <P>SOLUTION: A dielectric oxidized film 11 is formed by a chemical conversion treatment on the increased surface area of an aluminum anode body 9, and the aluminum anode body 9 is partitioned into two regions by an insulator 12. An aluminum base body 16 is exposed by peeling off the one of the regions of the dielectric oxide film 11. Next, a hole 17 is formed on the aluminum base body 16. Thereafter, a cathode part 20 is formed on the other region. Thereafter, a metal projection 19 is formed on an internal anode terminal 3; the hole 17 is passed therethrough, the cathode part 20 and the internal cathode terminal 4 of a substrate 2 for mounting are connected; then an anode lead part 18 is connected by ultrasonic vibration; and an exterior coating is applied. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid electrolytic capacitor and a method for manufacturing the same.

  In recent years, electronic devices have been reduced in size and thickness, but aluminum solid electrolytic capacitors are small and have a large capacity, and are thus widely used in such electronic devices. However, if further downsizing is required in the future, it is expected that it will be difficult to cope with the current manufacturing method. As one of the manufacturing methods, there is a method of connecting the anode lead portion and the internal anode terminal of the mounting substrate.

  An aluminum solid electrolytic capacitor includes a plate-like or foil-like aluminum anode body having an enlarged surface, and a capacitor element including a dielectric oxide film, an insulator, and a cathode layer. A part is electrically connected to a mounting substrate or the like, and the whole is covered with an exterior resin.

  A conventional method for producing an aluminum solid electrolytic capacitor will be described with reference to FIG. FIG. 2 is a diagram showing an example of the configuration of a conventional aluminum solid electrolytic capacitor, FIG. 2 (a) is a side sectional view of the configuration of the conventional aluminum solid electrolytic capacitor, and FIG. 2 (b) is a diagram of FIG. It is sectional drawing of the side surface direction of the capacitor | condenser element of 2 (a).

  As shown in FIG. 2, a dielectric oxide film 11 which is an insulating film is formed on the surface of an aluminum anode body 9 made of plate-like or foil-like aluminum having a surface-enlarging layer 10 on the surface by chemical conversion treatment (anodic oxidation treatment). Form. An insulator 12 is formed at a predetermined position of the dielectric oxide film 11 with an epoxy resin or the like, and the aluminum anode body 9 is divided into two regions, and a solid made of a conductive polymer is formed only in one of the regions. The electrolyte layer 13 is formed. Further, a graphite layer 14 is formed on the solid electrolyte layer 13 by screen printing or the like, and a metal electrode layer 15 made of silver paste or the like is formed on the graphite layer 14 to form a cathode portion 20.

  On the other hand, in the other region divided by the insulator 12, the surface enlargement layer 10 and the dielectric oxide film 11 of the aluminum anode body 9 are peeled off by a laser or the like to expose the aluminum base 16 and are made of a metal such as copper. The anode lead portion 18 is formed by ultrasonic bonding to the ultrasonic bonding portion 22 of the anode lead frame 21. The cathode portion 20 and the anode lead portion 18 are electrically connected to the internal cathode terminal 4 and the internal anode terminal 3 of the mounting substrate 2 such as an interposer substrate, respectively, by the conductive adhesive 7. Thereafter, the whole is covered with the insulating exterior resin 8 so that a part of the external anode terminal 5 and the external cathode terminal 6 of the mounting substrate 2 are exposed, and an aluminum solid electrolytic capacitor is obtained.

  The basic manufacturing method of the aluminum solid electrolytic capacitor is as described above. When the above manufacturing method is used, the anode lead frame 21 is ultrasonically welded to the aluminum base 16 and the anode lead portion 18 is formed. The process of electrically connecting the anode lead portion 18 to the mounting substrate 2 with the conductive adhesive 7 is necessary and complicated.

  In addition, a certain margin is required between the cathode portion 20 and the ultrasonic bonding portion 22 of the anode lead frame 21 so as not to damage the cathode portion 20 during ultrasonic bonding. This is because, when the capacitor element 1 is further reduced in size, the ratio of the margin portion in the capacitor element 1 is increased, and as a result, the ratio of the portion not contributing to the capacitance is increased, thereby further increasing the capacitance. It will decline. In general, such a structure is said to have low volumetric efficiency, and increasing this volumetric efficiency is important in the case of downsizing.

  As a method for solving such a problem, the connection between the aluminum base 16 and the internal anode terminal 3 of the mounting substrate 2 is not a method in which the anode lead frame 21 is ultrasonically bonded. A method of increasing volumetric efficiency by adopting a welding method has been proposed.

  The above-described method is disclosed in Patent Document 1, Patent Document 2, and the like. Patent Document 1 proposes a solid electrolytic capacitor in which each of a space between a cathode terminal film and an anode terminal portion in a capacitor element and each wiring pattern in a printed board is wire-bonded with a metal wire. Patent Document 2 also proposes a method in which a wire made of a metal such as 42 alloy or copper and the anode lead wire of the capacitor element are connected by resistance welding, and the wire and the anode terminal are connected by a conductive adhesive. By manufacturing in this way, an aluminum solid electrolytic capacitor that does not reduce volumetric efficiency is obtained because it is not welded with an anode lead frame made of a metal such as copper.

  However, since the solid electrolytic capacitor manufactured as described above forms the anode lead portion after the cathode portion is formed, in the structure in which the anode lead portion and the cathode portion of the capacitor element are close to each other when downsizing. When a metal wire is bonded to an aluminum substrate, the dielectric oxide film of the aluminum anode body in the region where the cathode portion is formed is destroyed, and the aluminum substrate is exposed. There is a concern that characteristic deterioration such as increase in leakage current may occur.

JP-A-9-283376 JP 2001-267181 A

  In order to solve this problem, the inventors previously formed a metal bump on one or both of the aluminum substrate and the internal anode terminal of the mounting substrate in Japanese Patent Application No. 2008-269580, A solid electrolytic capacitor ultrasonically bonded from above and a manufacturing method thereof are proposed.

  That is, when the aluminum substrate and the mounting substrate are connected, metal bumps are formed on one or both of the aluminum substrate and the internal anode terminal of the mounting substrate, and both are superposed to perform ultrasonic bonding. As a result, the anode lead frame made of metal such as copper is not ultrasonically bonded, so it is not necessary to secure a certain margin necessary for ultrasonic bonding of the anode lead frame, and aluminum that does not reduce volumetric efficiency. A solid electrolytic capacitor is obtained.

  However, in the solid electrolytic capacitor manufactured by the proposal of Japanese Patent Application No. 2008-269580, the metal bumps are completely covered with the aluminum base during ultrasonic bonding and cannot be confirmed from above, so the metal bumps It is difficult to reliably ultrasonically vibrate the upper part. Therefore, when the above method is used, there is room for improvement in visibility in order to obtain a stable and strong bond.

  As described above, the conventional solid electrolytic capacitor has problems such as an increase in work process, low volume efficiency, characteristic deterioration due to damage of the cathode part, and inability to obtain a stable connection of the anode lead part in downsizing. It was.

  The present invention has been made to solve the above-described conventional problems. The purpose of the present invention is to simplify the work process, to have high volumetric efficiency, and to reduce the burden on the cathode part at the time of production, and to make a higher connection to the anode lead part. To provide a solid electrolytic capacitor having strength and stable connection and capable of being downsized, and a method of manufacturing the same.

  In order to solve the above problems, in the present invention, first, a dielectric oxide film, which is an insulating film, is formed on the surface of an aluminum anode body made of plate-like or foil-like aluminum whose surface is enlarged by chemical conversion treatment. The aluminum plate or foil is cut and processed according to the target element shape to form an aluminum anode body, and further, an insulator is formed with epoxy resin or the like at a predetermined position to divide the aluminum anode body into two regions. A solid electrolyte layer made of a conductive polymer is formed in the region. Further, a graphite layer is formed on the solid electrolyte layer by screen printing or the like, and a metal electrode layer made of silver paste or the like is further formed on the solid electrolyte layer by the same method to form a cathode portion.

  Next, the dielectric oxide film in the other region divided by the insulator is peeled off with a laser or the like to expose the aluminum base portion. A plurality of holes are formed in the exposed aluminum substrate by a laser or the like, and these are used as anode lead portions.

  The cathode portion is electrically connected to the internal cathode terminal of the mounting substrate by a conductive adhesive. On the other hand, for the connection of the anode lead part, first, metal protrusions are formed by ball bonding of a metal wire such as gold to the internal anode terminal of a mounting substrate such as an interposer substrate. Thereafter, the metal protrusion is inserted into the hole formed in the anode lead portion, and connection is made by applying ultrasonic vibration from above. On the other hand, thereafter, as in the prior art, the external anode terminal and the external cathode terminal are packaged with an insulating resin so as to be exposed on the surface, thereby obtaining a solid electrolytic capacitor.

  That is, the solid electrolytic capacitor of the present invention includes an anode lead portion having a hole in an end portion of a plate-like or foil-like valve metal, and an anode body in a region divided by the anode lead portion and an insulator. A capacitor element having a dielectric oxide film, a solid electrolyte layer, a graphite layer, and a cathode part on which a metal electrode layer is formed in order on the surface of which the surface is enlarged, and an inner anode terminal and an inner cathode terminal are formed on the upper surface, and the lower surface An external anode terminal and an external cathode terminal are formed, arranged on a mounting substrate in which a metal protrusion is formed on the internal anode terminal, and the metal protrusion is inserted into a hole of the anode lead portion and connected, The external anode terminal and the external cathode terminal are covered with an exterior resin so as to be exposed.

  In the solid electrolytic capacitor of the present invention, the valve metal of the anode body is made of aluminum.

  In the solid electrolytic capacitor of the present invention, the hole of the anode lead portion is a through hole.

  The solid electrolytic capacitor of the present invention is characterized in that the metal protrusion is formed by wedge bonding or ball bonding of an aluminum wire or a gold wire.

  The solid electrolytic capacitor of the present invention is characterized in that the metal protrusion and the hole of the anode lead portion are connected by ultrasonic welding.

  In addition, the method for producing a solid electrolytic capacitor of the present invention is such that the inner anode terminal and the inner cathode terminal are formed on the upper surface, and the outer anode terminal and the outer cathode terminal are formed on the lower surface. Forming a metal protrusion by wedge bonding or ball bonding of a wire or a gold wire, an anode lead portion having a hole in an end portion of an anode body made of a plate-like or foil-like valve metal, and the anode lead portion, The anode lead portion of the capacitor element having a cathode portion in which a dielectric oxide film, a solid electrolyte layer, a graphite layer, and a metal electrode layer are sequentially formed on the enlarged surface of the anode body in a region divided by an insulator. A step of inserting the metal protrusion into the hole, a step of connecting the hole of the anode lead part and the metal protrusion by ultrasonic welding, and a part of the external anode terminal and the external cathode terminal. Characterized in that it comprises a step of coating the capacitor element with an exterior resin to exit.

  In the present invention, the diameter of the hole formed in the anode lead portion is the same as or slightly larger than the diameter of the metal protrusion inserted into the hole when connected to the internal anode terminal of the mounting substrate. In order to connect the holes and metal protrusions, the anode lead frame is necessary for ultrasonic bonding compared to a solid electrolytic capacitor in which an anode lead frame is formed by ultrasonic bonding of a conventional anode lead frame to an aluminum substrate. The margin required can be reduced to the margin necessary for forming the hole, and as a result, the cathode portion of the element can be increased, and the volume efficiency can be increased in downsizing.

  Also, after connecting the anode lead part and the internal anode terminal of the mounting substrate, the upper part of the metal protrusion inserted into the anode lead part is deformed by ultrasonic vibration, and the metal protrusion serves as a wedge. Solid electrolytic capacitor in which the connection strength of the anode lead portion is higher and the connection is stable than in the shape of merely forming metal bumps on either or both of the aluminum substrate and the mounting substrate of 2008-269580 Is obtained.

  In addition, since the anode lead portion is directly connected to the metal protrusion provided on the mounting substrate, the conventional process of welding the lead frame to the anode body, and the lead frame and the mounting substrate are made conductive. Since the process of bonding with an adhesive can be replaced with a single connection process, a method for manufacturing a solid electrolytic capacitor that can simplify the process is obtained.

FIG. 1A is a cross-sectional view in the side surface direction according to the embodiment, FIG. 1B is a cross-sectional view in the side surface direction of the capacitor element, and FIG. ) Is a plan view of the capacitor element, and FIG. 1D is a cross-sectional view in the side surface direction of the mounting substrate. FIG. 2A is a cross-sectional view of the configuration of a conventional aluminum solid electrolytic capacitor, and FIG. 2B is a diagram illustrating an example of the configuration of a conventional aluminum solid electrolytic capacitor. FIG. Sectional drawing of the side surface direction of an element. Sectional drawing of the side surface direction of the aluminum solid electrolytic capacitor of the comparative example 2. FIG.

  A solid electrolytic capacitor according to an embodiment of the present invention will be described using an aluminum solid electrolytic capacitor as an example with reference to the drawings.

  First, the capacitor element 1 of the solid electrolytic capacitor of the present invention will be described with reference to FIGS. 1 (b) and 1 (c). First, the aluminum anode body 9 is cut into a desired element shape. The aluminum anode body 9 is made of an aluminum foil, and a surface-enlarging layer 10 is formed on both surfaces by etching. Further, dielectric oxide films 11 are formed on both surfaces of the aluminum anode body 9 by chemical conversion treatment.

  An insulator 12 is formed of an insulating resin such as an epoxy resin at a predetermined position of the dielectric oxide film 11 of the aluminum anode body 9, and the aluminum anode body 9 is divided into two regions. For one of the divided regions, a solid electrolyte layer 13 made of a conductive polymer, a graphite layer 14, a metal electrode layer 15 made of a conductive paste, etc. are formed on the surface of the dielectric oxide film 11 of the aluminum anode body 9. The cathode part 20 is formed by sequentially laminating by screen printing. Subsequently, the dielectric oxide film 11 and the surface enlargement layer 10 in the other region divided by the insulator 12 are all peeled off by a laser or the like to expose the aluminum base 16. A hole 17 is formed in the exposed aluminum substrate 16 by a laser or the like, and this is used as an anode lead portion 18 to produce the capacitor element 1.

  Next, as shown in FIG. 1D, a metal projection 19 made of, for example, gold is formed on the internal anode terminal 3 of the mounting substrate 2 such as an interposer substrate by ball bonding or the like. This metal protrusion is not limited to gold, and aluminum often used in wire bonding may be formed by wedge bonding.

  Subsequently, as shown in FIG. 1A, the hole 17 of the anode lead portion 18 of the capacitor element 1 is aligned with the upper portion of the metal protrusion 19, and the metal protrusion 19 is inserted. Thereafter, the cathode portion 20 is electrically connected to the internal cathode terminal 4 of the mounting substrate 2 by the conductive adhesive 7. Thereafter, ultrasonic vibration is applied from above the metal protrusion 19 to connect the anode lead 18 and the internal anode terminal 3 of the mounting substrate 2. The hole 17 is preferably a through-hole, but is not necessarily a through-hole, and a metal protrusion may be inserted into and connected to the hole without passing through. By connecting the capacitor element 1 to the mounting substrate 2 as described above, the external anode terminal 5 and the external cathode terminal 6 of the solid electrolytic capacitor are taken out. Of course, it is assumed that the internal anode terminal 3 and the external anode terminal 5 and the internal cathode terminal 4 and the external cathode terminal 6 of the mounting substrate 2 are designed to be electrically connected to each other. Finally, the external anode terminal 5 and the external cathode terminal 6 are externally covered with an insulating external resin 8 so that parts of the external anode terminal 5 and the external cathode terminal 6 are exposed on the surface, thereby forming an aluminum solid electrolytic capacitor.

An embodiment of the present invention will be described with reference to FIG. First, an aluminum foil having a surface-enlarging layer 10 and having a dielectric oxide film 11 provided on the surface was used as the aluminum anode body 9. This is commercially available for an aluminum solid electrolytic capacitor. When the dielectric oxide film 11 is formed on the surface, the nominal formation voltage is 4 V, the capacitance per unit area (cm ² ) is 295 μF, the thickness Is 105 μm.

  This foil-like aluminum anode body 9 is cut into a rectangular shape having a width of 2.5 mm and a length of 5.0 mm, and a rectangular region having a length of 4.0 mm from one end in the length direction is formed into a cathode portion 20. A rectangular region of 0.5 mm in the length direction from the end portion in the length direction on the side where the cathode portion 20 is not formed was defined as a formation region of the anode lead portion 18. Further, in order to electrically insulate between the anode lead portion 18 and the cathode portion 20, an insulator 12 having a width of 0.5 mm and a thickness of 15 μm is formed between the anode lead portion 18 and the cathode portion 20 with an epoxy resin. Formed by screen printing.

  Next, with respect to the region for forming the cathode portion 20, on the surface of the dielectric oxide film 11 of the aluminum anode body 9, 3,4-ethylenedioxythiophene as a monomer, ammonium peroxodisulfate as an oxidizing agent, and paratoluene as a dopant. The sulfonic acid was reacted at a molar ratio of 6: 1: 2 to form a solid electrolyte layer 13 made of a conductive polymer so as to have a thickness of 10 μm. Further, a graphite layer 14 was formed on the surface so as to have a thickness of 15 μm by screen printing. Then, a conductive paste containing silver having a weight ratio of 80% or more is formed on the graphite layer 14 to a thickness of 30 μm, and left at 150 ° C. to volatilize the organic solvent in the conductive paste, and at the same time, is cured. As a result, the metal electrode layer 15 was formed. Thus, the cathode part 20 was formed. Next, the surface enlargement layer 10 and the dielectric oxide film 11 in the region on the anode lead portion 18 side were all peeled off by laser processing to expose the aluminum substrate 16. The laser power was set at 15W.

  A hole 17 was formed by laser processing at a position of 0.250 mm in the length direction and 0.156 mm in the width direction from the exposed end of the aluminum substrate 16. Eight holes 17 were formed at equal intervals in the width direction, and the diameter thereof was 60 μm. The laser power was set at 25W. The anode lead portion 18 was formed as described above.

  Subsequently, a conductive adhesive 7 was applied to the internal cathode terminal 4 of the mounting substrate 2 to a thickness of 40 μm. The internal cathode terminal 4 of the mounting substrate 2 was formed by forming a 3 μm nickel plating and a 0.1 μm gold plating on an 18 μm copper layer. The other terminals have the same structure.

  Thereafter, a metal protrusion 19 was formed on the internal anode terminal 3 of the mounting substrate 2 by ball bonding of a gold wire. The metal protrusion 19 was formed at a position directly below each of the eight holes 17 formed in the anode lead portion 18 when the capacitor element 1 was mounted. The diameter of the gold wire used for forming the metal protrusions 19 is 50 μm, and those commercially available for ball bonding are used. The height of the metal protrusion 19 was 30 μm for the ball-shaped portion, and 110 μm for the entire metal protrusion 19. The diameter of the ball-shaped portion of the metal protrusion 19 was 80 μm.

  Subsequently, the capacitor element 1 is laminated on the mounting substrate 2 so that the metal protrusion 19 formed on the internal anode terminal 3 of the mounting substrate 2 penetrates the hole 17 formed in the anode lead portion 18, and the cathode portion 20. And the conductive adhesive 7 directly thereunder were connected and cured. Furthermore, the anode lead 18 and the internal anode terminal 3 of the mounting substrate 2 were connected to the metal protrusion 19 by applying ultrasonic vibration from above. The load during ultrasonic bonding was 5 MPa and the power was 20 W. Thereafter, the external electrolytic terminal 5 and the external cathode terminal 6 of the mounting substrate 2 were molded and covered with an insulating exterior resin 8 made of an epoxy resin so that the solid electrolytic capacitor was completed. In this example, the number of solid electrolytic capacitors produced was 10.

  The electrical characteristics of the produced 10 solid electrolytic capacitors were measured. There are three measurement items: capacitance, equivalent series resistance (hereinafter referred to as ESR), and leakage current. Capacitance and ESR were both measured by the AC impedance bridge method. Among these, the measurement conditions of the capacitance were that the frequency of the applied reference signal was 120 Hz, the voltage was 1 Vrms, and the DC bias was 0V. On the other hand, in ESR, the frequency of the applied reference signal was 100 kHz, the voltage was 1 Vrms, and the DC bias was 0V. As for leakage current, a signal of 2.5 V, which is the rated voltage of the solid electrolytic capacitor, was applied, and the value after 1 minute was measured. The average value of each characteristic of the produced 10 solid electrolytic capacitors is shown in the examples in Table 1.

  After measuring the electrical characteristics as described above, a tensile test was performed to measure the tensile strength. The average value of the tensile strength is also shown in the examples in Table 1 as with the electrical characteristics.

(Comparative Example 1)
An aluminum solid electrolytic capacitor produced by a conventional method was produced as Comparative Example 1 in order to compare with the capacitor produced by the method shown in the above-mentioned Examples. An example of the configuration of the conventional aluminum solid electrolytic capacitor in FIG. 2 will be described with reference to the drawing.

  In this comparative example, a foil-like aluminum anode body 9 similar to that used in the example was used. This was cut into a rectangular shape having a width of 2.5 mm and a length of 5.0 mm. Here, if the cathode portion 20 is formed in the same manner as in the embodiment, a certain margin required for ultrasonic bonding of the anode lead frame 21 cannot be secured. A rectangular area of 3.5 mm in the vertical direction is defined as a formation area of the cathode part 20, and a rectangular area of 1.0 mm in the length direction from the end in the length direction on the side where the cathode part 20 is not formed, It was set as the formation area of the anode lead part 18. Next, in order to electrically insulate between the anode lead part 18 and the cathode part 20, the insulator 12 having a width of 0.5 mm and a thickness of 15 μm was formed by screen printing of an epoxy resin.

  Subsequently, the cathode part 20 was formed in the area | region for the above-mentioned cathode part 20 formation by the method similar to an Example. Thereafter, the surface expansion layer 10 and the dielectric oxide film 11 in the region of the anode lead portion 18 were all peeled off by laser processing to expose the aluminum substrate 16. The laser power was set at 15W. Thereafter, the anode lead 18 was formed by ultrasonic bonding to the ultrasonic bonding 22 of the anode lead frame 21 made of copper. During ultrasonic bonding, the load was 5 MPa and the power was 20 W. The thickness of the anode lead frame 21 used here is 50 μm. Next, the anode lead frame 21 and the internal anode terminal 3 of the mounting substrate 2 were bonded to each other, and the cathode portion 20 and the internal cathode terminal 4 of the mounting substrate 2 were bonded to each other with the conductive adhesive 7. Then, the exterior was carried out similarly to the Example of this invention, and the solid electrolytic capacitor was produced. Also in this comparative example, the number of solid electrolytic capacitors produced was 10, and the electrical characteristics and tensile strength of the 10 produced solid electrolytic capacitors were measured in the same manner as in the examples.

(Comparative Example 2)
Next, a solid electrolytic capacitor in which a metal bump was formed on the internal anode terminal and the aluminum base of the mounting substrate and the anode lead part was connected by ultrasonic bonding was produced as Comparative Example 2. This will be described with reference to FIG.

  Also in Comparative Example 2, the same foil-like aluminum anode body 9 as in the example was used. This foil-like aluminum anode body 9 is cut into a rectangular shape having a width of 2.5 mm and a length of 5.0 mm, and a rectangular region having a length of 4.0 mm from one end in the length direction is formed into a cathode portion 20. A rectangular region of 0.5 mm in the length direction from the end portion in the length direction on the side where the cathode portion 20 is not formed was defined as a formation region of the anode lead portion 18. Here, a dielectric oxide film was formed again on the cut surface of the aluminum anode body 9. Further, in order to electrically insulate between the anode lead portion 18 and the cathode portion 20, an insulator 12 having a width of 0.5 mm and a thickness of 15 μm is formed between the anode lead portion 18 and the cathode portion 20 with an epoxy resin. Formed by screen printing.

  Subsequently, the cathode part 20 was formed in the area | region for the above-mentioned cathode part 20 formation by the method similar to an Example. Thereafter, the surface expansion layer 10 and the dielectric oxide film 11 in the region of the anode lead portion 18 were all peeled off by laser processing to expose the aluminum substrate 16. The laser power was set at 15W.

  Thereafter, metal bumps 23 were formed on the internal anode terminals 3 of the mounting substrate 2 by ball bonding of gold wires. The gold wire used for forming the metal bump 23 was the same as that used in the example, and the metal bump 23 had a diameter of 80 μm and a height of 30 μm. Thereafter, similarly to the example of the present invention, the cathode portion 20 and the internal cathode terminal 4 of the mounting substrate 2 were connected, and the anode lead portion 18 and the metal bump 23 were ultrasonically bonded. The load during ultrasonic bonding was 20 MPa, and the power was 20 W. Then, the exterior was covered and the aluminum solid electrolytic capacitor was produced. Also in this comparative example, the number of solid electrolytic capacitors produced was 10, and the electrical characteristics of the 10 produced solid electrolytic capacitors were measured in the same manner as in the examples.

  Table 1 shows the measurement results and yield of the electrical characteristics, tensile strength, and effective area of the cathode portion for the example, comparative example 1, and comparative example 2.

  In Table 1, the solid electrolytic capacitor of the example of the present invention has a capacitance 10% or more higher than that of Comparative Example 1 in which the anode lead frame is formed by ultrasonically bonding the anode lead frame to the aluminum substrate. It turns out that ESR is also low. The improvement in capacitance and the reduction in ESR in the example are due to the fact that the effective area of the cathode part functioning as a capacitor can be made larger than in Comparative Example 1. Accordingly, it was confirmed that a solid electrolytic capacitor excellent in volume efficiency and capacitor characteristics can be obtained because the electrostatic capacity can be improved and the ESR can be reduced without increasing the exterior dimensions.

  Also, in Table 1, the solid electrolytic capacitor of the example of the present invention has a tensile strength of about that of Comparative Example 2 in which a metal bump is formed on the internal anode terminal of the mounting substrate and ultrasonically bonded to the anode lead portion. It is 2.5 times that it can be seen that a strong connection is maintained. The increase in tensile strength is due to the structure in which the metal protrusion is sandwiched from above and below the anode lead portion and serves as a wedge. In addition, the yield was greatly improved by increasing the tensile strength, and it was confirmed that a stable connection between the anode lead portion and the internal anode terminal of the mounting substrate was obtained.

  As described above, according to the present invention, it is possible to produce a solid electrolytic capacitor having high volumetric efficiency, less burden on the aluminum anode body during ultrasonic bonding, higher connection strength, and capable of being downsized.

1 Capacitor element
2 Mounting board
3 Internal anode terminal
4 Internal cathode terminal
5 External anode terminal
6 External cathode terminal
7 Conductive adhesive
8 Insulation exterior resin
9 Aluminum anode body
10 Expanded layer
11 Dielectric oxide film
12 Insulator
13 Solid electrolyte layer
14 Graphite layer
15 Metal electrode layer
16 Aluminum base
17 holes
18 Anode lead
19 Metal projection
20 Cathode part
21 Anode lead frame
22 Ultrasonic joint
23 Metal bump

Claims (6)

  An anode lead portion having a hole in the end portion of a plate-like or foil-like valve metal, and a dielectric on the surface of the anode body in a region divided by the anode lead portion and the insulator in order Capacitor element having an oxide film, a solid electrolyte layer, a graphite layer, and a cathode portion on which a metal electrode layer is formed, an internal anode terminal and an internal cathode terminal are formed on the upper surface, and an external anode terminal and an external cathode terminal are formed on the lower surface Arranged on a mounting substrate on which a metal protrusion is formed on the internal anode terminal, and the metal protrusion is inserted into and connected to a hole of the anode lead portion, and one of the external anode terminal and the external cathode terminal is connected. A solid electrolytic capacitor characterized in that it is coated with an exterior resin so that a portion is exposed.   The solid electrolytic capacitor according to claim 1, wherein the valve metal of the anode body is made of aluminum.   The solid electrolytic capacitor according to claim 1, wherein the hole of the anode lead portion is a through hole.   2. The solid electrolytic capacitor according to claim 1, wherein the metal protrusion is formed by ball bonding of a gold wire or wedge bonding of an aluminum wire.   The solid electrolytic capacitor according to claim 1, wherein the metal protrusion and the hole of the anode lead portion are connected by ultrasonic welding.   An aluminum wire or a gold wire is made of metal by wedge bonding or ball bonding on the internal anode terminal of the mounting substrate having an internal anode terminal and an internal cathode terminal formed on the upper surface and an external anode terminal and an external cathode terminal formed on the lower surface. A step of forming protrusions, an anode lead portion having a hole in an end portion of a plate-like or foil-like valve metal, and an enlarged surface of the anode body in a region divided by the anode lead portion and the insulator A step of inserting the metal protrusion into the hole of the anode lead portion of the capacitor element having a dielectric oxide film, a solid electrolyte layer, a graphite layer, and a cathode portion on which a metal electrode layer is formed in order on the converted surface and the anode A step of connecting the hole of the lead portion and the metal protrusion by ultrasonic welding, and covering the capacitor element with an exterior resin so that a part of the external anode terminal and the external cathode terminal are exposed. Method for producing a solid electrolytic capacitor which comprises a step of.

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