JP4953090B2 - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Description

Relationship with related applications

  This application is based on the provisions of the provisions of US Provisional Application No. 60 / 734,782 filed on November 9, 2005, in accordance with the provisions of 35 USC 35, 111 (b). ) Is an application based on the provisions of Article 111 (a) claimed in paragraph (1).

  The present invention relates to a capacitor and a manufacturing method thereof, and more particularly to a solid electrolytic capacitor and a manufacturing method thereof. More specifically, in a solid electrolytic capacitor formed by providing a lead wire (lead frame) on a capacitor element in which a solid electrolyte layer is provided on a valve action metal substrate having a dielectric film, a joint portion between the capacitor element and the lead frame. The present invention relates to a highly reliable solid electrolytic capacitor excellent in strength and heat resistance.

  Recent electronic devices have been digitized for downsizing and power saving, etc. With the speeding up of personal computers, small and large capacitors, high frequency, high frequency, low impedance, high capacity and high reliability The demand for highly efficient capacitors is increasing. Solid electrolytic capacitors have been put into practical use as capacitors that satisfy these requirements.

  In general, a solid electrolytic capacitor is provided with a dielectric oxide film on the surface of a valve action metal such as aluminum, tantalum, or titanium that has been subjected to etching, and an organic layer such as a conductive polymer or a metal oxide is formed on the dielectric oxide film. A single-plate capacitor element is formed by providing a solid electrolyte layer made of an inorganic material layer, and a plurality of single-plate capacitor elements are laminated, and an anode lead is formed on the anode terminal of the valve metal (the end surface portion where no solid electrolyte is provided). While the wires are connected, a cathode lead wire is connected to a conductive layer portion (cathode portion) made of a solid electrolyte, and the whole is sealed with an insulating resin such as an epoxy resin. As the anode lead portion and the cathode lead portion, a lead frame having a shape suitable for mounting a capacitor element or a laminate thereof can be used.

  In order to manufacture a highly reliable capacitor with a solid electrolytic capacitor having such a structure, it is necessary that the joint portion between the capacitor element and the lead frame has a high strength and is excellent in heat resistance. Therefore, in a conventional solid electrolytic capacitor, for example, when a lead frame made of copper or a copper alloy and the anode end of a capacitor element are joined, they are joined using a conductive adhesive or a terminal is bent and caulked. Therefore, they are joined mechanically or by welding using a lead solder material or laser welding.

  However, such a joining method using a conductive adhesive takes time and effort to apply the adhesive, and in particular, when a large number of single-plate capacitor elements are laminated and joined, the construction is complicated. Further, the method of caulking and joining the lead frame joints is not suitable for a joint having a small joint and the joining is unstable. Further, in welding using a lead-based solder material, there is a concern that excessive lead removed from the welded part may cause environmental pollution. Moreover, the joining method by laser welding has problems such as increased equipment costs.

  In addition to such a joining method, it is known that the terminals of the capacitor element are resistance-welded to the lead frame (Patent Document 1; Japanese Patent Laid-Open No. 3-188614). (42 alloy) is limited to resistance welding, and when aluminum foil is used as the valve action metal of the capacitor element, a lead frame made of copper or copper alloy or the like is directly subjected to simple resistance welding. Can not be joined. Resistance welding is a method in which the metal in the welded part is melted and joined by heat generation due to electric resistance (Joule heat), and heat is generated in highly conductive materials such as aluminum, copper, and copper alloys because this resistance is small. The bonding portion cannot be sufficiently melted due to the low thermal conductivity, and it is difficult to bond these materials.

  Furthermore, conventional solid electrolytic capacitors are known in which the entire lead frame is plated and the capacitor element is joined. However, when plating is performed on the entire lead frame, the capacitor element is overlaid on the lead frame and heat treated. In addition, there is a concern that the plating metal melts even in a portion coming out of the joint portion with the capacitor element and coming into contact with the mold resin, thereby causing a defect called a solder ball. To avoid such inconvenience, after plating the copper base on the entire lead frame, remove the plating on the resin-encapsulated portion where the mold resin contacts, and expose the copper base to roughen the surface. There is known a structure in which a capacitor element is mounted and bonded to a surfaced area (Patent Document 2; JP-A-5-21290). However, this method has a problem that the amount of plating at the joint portion of the capacitor element is insufficient and the joint strength is lowered.

  When the capacitor element and the lead frame are joined by welding with respect to the joining structure of the solid electrolytic capacitor, no plating is provided on the surface of the lead frame that contacts the mold resin in the resin sealing portion of the lead frame, and the lead frame is a capacitor. A low melting point metal plating is applied to the part in contact with the element so that the lead frame and the capacitor element are joined to each other, so that there is no defect such as a solder ball and the joining strength is high. Regarding a junction structure, a solid electrolytic capacitor is disclosed in which the anode end portion of the capacitor element and the lead frame can be joined by resistance welding, the work is easy, and the junction structure does not cause environmental pollution (patent) Reference 3: International Publication No. 00/74091 (US66616) 45 specification)). However, although the bonding strength is remarkably improved by partial plating of the lead frame here, the lead frame is usually continuously plated in a form in which the lead frame is wound in a coil shape, so that its industrial production is not always easy. Absent.

  The generation of solder balls is not limited to resin sealing. For example, when a chip-type electronic component is placed on a circuit board and subjected to heating such as reflow, the electronic component itself is also heated, the internal temperature of the electronic component rises, the solder plating layer on the surface of the lead terminal inside the component melts, and the solder ball It is known that the phenomenon of elution to the outside occurs (Patent Document 4; JP-A-8-153651). According to Patent Document 4, a solder plating layer having a thickness of 1 μm or less is formed on the surface of the lead terminal before molding resin coating, an electronic component element is connected to the lead terminal, and then molding resin coating is performed. The above-mentioned problem is solved by forming a solder plating layer thicker than the solder plating inside the mold resin only on the surface of the lead terminal derived from the above.

Japanese Patent Laid-Open No. 3-188614 JP-A-5-21290 International Publication No. 00/74091 Pamphlet JP-A-8-153651

  An object of the present invention is a solid electrolytic capacitor formed by providing a lead wire (lead frame) on a capacitor element provided with a solid electrolyte layer on a valve action metal substrate having a dielectric film, the capacitor element and the lead frame The present invention is to provide a solid electrolytic capacitor and a manufacturing method that are excellent in strength of the joining portion, that are easy to produce industrially without solder balls due to plating melting on a metal member even after heating such as sealing and reflow, and high reliability. .

  As a result of intensive studies in view of the above problems, the present inventors have provided a region including a low melting point metal plating layer and a region not including a low melting point metal plating layer by masking the lead frame in a strip shape such as taping, and heating. The present inventors have found that industrial production of a solid electrolytic capacitor having excellent moisture resistance and high reliability that does not cause a gap due to melting is easy, and has completed the present invention.

That is, this invention is invention of the patterning of the low melting point plating layer in the following solid electrolytic capacitor, its manufacturing method, and a lead frame.
1. The anode part of the capacitor having the anode part and the cathode part provided with the insulating layer interposed therebetween is joined to the first metal member, the cathode part is joined to the second metal member, and a part of each metal member is exposed. The first and / or second metal member is a solid having a region including a low melting point metal plating layer and a region not including a low melting point metal plating layer according to a predetermined pattern. Electrolytic capacitor.
2. One end portion of the base body (1) made of a valve metal having the dielectric coating layer (2) is used as an anode section (6), and an insulating layer having a predetermined width is formed on the base body (1) in contact with the anode section (6). (3) is provided as an insulating portion, and a solid electrolyte layer (4) and a conductor layer (5) are sequentially laminated on the dielectric coating layer in a range excluding the anode portion (6) and the insulating portion. Other than the lead frame (10) (11) portion (23) or (23) and (24) with which the single plate capacitor element (8) serving as the cathode part (7) or the capacitor element (15) formed by laminating the plurality of sheets is in contact The lead frame (10) (11) in contact with the resin (28) is not subjected to low melting point metal plating in the resin (28) sealing portion (20) by masking the lead frame in a strip shape. (23) or only in (23) and (24) The lead frame (10) (11) subjected to soldering is bonded to the anode part (6) and the cathode part (7) of the capacitor element (8) (15) and sealed with a resin (28). 2. The solid electrolytic capacitor as described in 1 above.
3. The anode part (6) of the capacitor element (8) (15) is overlapped on the low melting point metal plating part of the surface part (23) of the anode side lead frame (10), resistance welding is performed, and resistance heat generated by the dielectric film is used. 3. The solid electrolytic capacitor as described in 2 above.
4). When the capacitor elements (8) (15) and the lead frame (10) (11) portions (23) (24) are joined, the capacitor element is placed on the low melting point metal plating portion of the anode side lead frame (10) portion (23). (8) The anode part (6) of (15) is overlapped and joined by resistance welding, while the cathode side is the cathode side end part (3a) of the insulating layer (3) of the capacitor element (8) (15) and the cathode. 3. The solid electrolytic capacitor as described in 2 above, wherein the solid electrolytic capacitor is joined to the front end portion (11a) of the side lead frame with an interval (t).
5. One end portion of the base body (1) made of a valve metal having the dielectric coating layer (2) is used as an anode section (6), and an insulating layer having a predetermined width is formed on the base body (1) in contact with the anode section (6). (3) is provided as an insulating portion, and a solid electrolyte layer (4) and a conductor layer (5) are sequentially laminated on the dielectric coating layer in a range excluding the anode portion (6) and the insulating portion. A lead frame (10) (11) portion (23 ') or (23') including a contact surface of a single plate capacitor element (8) as a cathode part (7) or a capacitor element (15) in which a plurality of these are laminated. By masking the lead frame other than 24 ') in a strip shape, low melting point metal plating is applied to the lead frames (10) and (11) in contact with the resin (28) in the sealing portion (20) of the resin (28). Low melting point only in the part (23 ′) or (23 ′) and (24 ′) The lead frame (10) (11) subjected to metal plating is bonded to the anode part (6) and the cathode part (7) of the capacitor element (8) (15) and sealed with a resin (28). 2. The solid electrolytic capacitor as described in 1 above, which is included as a feature.
6). The anode part (6) of the capacitor element (8) (15) is overlapped on the low melting point metal plating part of the surface part (23 ') of the anode side lead frame (10), resistance welding is performed, and resistance heat generated by the dielectric film is used. 6. The solid electrolytic capacitor as described in 5 above.
7). When the capacitor elements (8) (15) and the lead frame (10) (11) portions (23 ') (24') are joined, the low melting point metal plating portion of the anode side lead frame (10) portion (23 ') The anode parts (6) of the capacitor elements (8) (15) are overlapped with each other and joined by resistance welding, while the cathode side is the cathode side end part (3a) of the insulating layer (3) of the capacitor elements (8) (15). 6) and the cathode side lead frame tip (11a) with a gap (t) between them and joined.
8). The anode part of the capacitor having the anode part and the cathode part provided with the insulating layer interposed therebetween is joined to the first metal member, the cathode part is joined to the second metal member, and a part of each metal member is exposed. In the capacitor formed by resin-sealing the whole, the joint portion of the second metal member with the cathode portion has a region including the low melting point metal plating layer and a region not including the low melting point metal plating layer, and has a low melting point. The solid electrolytic capacitor characterized in that the region not including the metal plating layer is a joint portion with the cathode portion in the vicinity of the position where the second metal member is led out from the sealing resin and exposed.
9. 9. The solid electrolytic capacitor as described in 8 above, wherein a part of the cathode part is superposed on the second metal member and joined so that both are electrically conducted.
10. The capacitor sequentially forms an insulating layer made of a metal oxide, a solid electrolyte layer, and a conductive paste layer on at least a part of the surface of the valve action metal having a porous layer on the surface, and the valve action metal exposed part is an anode part, 10. The solid electrolytic capacitor as described in 8 or 9 above, which is a solid electrolytic capacitor including a capacitor element having a conductive paste layer as a cathode portion.
11. 11. The solid electrolytic capacitor as described in 1 to 10 above, wherein the valve metal is selected from aluminum, tantalum, titanium, niobium or alloys thereof.
12 12. The solid electrolytic capacitor as described in 1 to 11 above, wherein the lead frame (10) (11) is made of copper or a copper alloy (copper-based material), or a material having a surface plated with a copper-based material or a zinc-based material.
13. 13. The solid electrolytic capacitor as described in 1 to 12 above, wherein the low melting point metal plating is a metal or alloy plating having a lower melting point than the valve action metal, and the thickness of the plating layer is in the range of 0.1 to 100 μm.
14 14. The solid electrolytic capacitor as described in 1 to 13 above, wherein the low melting point metal plating comprises nickel base plating and tin surface plating.
15. 15. The solid electrolytic capacitor as described in 1 to 14 above, wherein the lead frame (10) (11) is joined at the center portion or the outer peripheral side of the multilayer capacitor element.
16. One end portion of the base body (1) made of a valve metal having the dielectric coating layer (2) is used as an anode section (6), and an insulating layer having a predetermined width is formed on the base body (1) in contact with the anode section (6). (3) providing a solid electrolyte layer (4) on the dielectric film layer in a range excluding the anode part (6) and the insulating part, and providing a conductor layer ( 5) A step of forming a single plate capacitor element (8) in which the cathode portions (7) are laminated or a capacitor element (15) in which a plurality of these are laminated, a lead frame in contact with the capacitor elements (8) (15) (10) Lead that contacts the resin (28) in the sealing portion (20) of the resin (28) by masking the lead frame other than the portions (23) or (23) and (24) in a strip shape. Frame (10) (11) is not plated with low melting point metal Lead frames (10) and (11) in which low melting point metal plating is applied only to the portions (23) or (23) and (24) are connected to anode portions (6) and cathode portions (7) of capacitor elements (8) and (15). ) And a step of sealing with a resin.
17. One end of the base body (1) made of a valve metal having a dielectric coating layer (2) is used as an anode section (6), and an insulating layer (3) having a predetermined width is formed on the base body (1) in contact with the anode section. Is formed as an insulating portion, and a solid electrolyte layer (4) and a conductor layer (5) are sequentially laminated on the dielectric coating layer in a range excluding the anode portion (6) and the insulating portion, and the cathode portion ( 7) Lead frame (10) (11) portion (23) or lead other than (23) and (24) in contact with single plate capacitor element (8) or multilayer capacitor element (15) in which a plurality of these are laminated By masking the frame in a band shape, the lead frame (10) (11) in contact with the resin (28) in the resin (28) sealing portion (20) is not subjected to low melting point metal plating, and the portion (23 ) Or (23) and (24) only. A lead frame (10) (11) characterized by being bonded to the anode part (6) and the cathode part (7) of the capacitor element (8) (15) sealed with resin (28) .
18. The lead frame (10) (11) formed by bonding the anode part (6) and the cathode part (7) of the capacitor element (8) (15) sealed with the resin (28) is made of copper or a copper alloy (copper type). The lead frame (10) (11) according to the previous term 17 including a material) or a material plated with a copper-based material or a zinc-based material.
19. One end portion of the base body (1) made of a valve metal having the dielectric coating layer (2) is used as an anode section (6), and an insulating layer having a predetermined width is formed on the base body (1) in contact with the anode section (6). (3) providing a solid electrolyte layer (4) on the dielectric film layer in a range excluding the anode part (6) and the insulating part, and providing a conductor layer ( 5) A step of forming a single-plate capacitor element (8) in which the cathode part (7) is laminated or a capacitor element (15) in which a plurality of these are laminated, a lead including the contact surface of the capacitor elements (8) (15) By masking the lead frame other than the frame (10) (11) portion (23 ′) or (23 ′) and (24 ′) in a band shape, the resin (28) in the resin (28) sealing portion (20) Apply low melting point metal plating to the lead frame (10) (11) that contacts First, the lead frame (10) (11) in which the low melting point metal plating is applied only to the portions (23 ′) or (23 ′) and (24 ′) is used as the anode portion (6) of the capacitor elements (8) (15). And a step of bonding to the cathode portion (7) and a step of sealing with resin.
20. One end of the base body (1) made of a valve metal having a dielectric coating layer (2) is used as an anode section (6), and an insulating layer (3) having a predetermined width is formed on the base body (1) in contact with the anode section. Is formed as an insulating portion, and a solid electrolyte layer (4) and a conductor layer (5) are sequentially laminated on the dielectric coating layer in a range excluding the anode portion (6) and the insulating portion, and the cathode portion ( 7) a single-plate capacitor element (8) or a multilayer capacitor element (15) in which a plurality of these are laminated, and a lead frame (10) (11) portion (23 ') or (23') and (24 ' By masking the lead frame other than) in a strip shape, the low melting point metal plating is not applied to the lead frames (10) and (11) in contact with the resin (28) in the sealing portion (20 ′) of the resin (28). , Low melting point gold only in the part (23 ′) or (23 ′) and (24 ′) A lead frame (10) characterized by being joined to the anode part (6) and the cathode part (7) of the capacitor element (8) (15) sealed with resin (28) subjected to metal plating 11).
21. The lead frame (10) (11) formed by bonding the anode part (6) and the cathode part (7) of the capacitor element (8) (15) sealed with the resin (28) is made of copper or a copper alloy (copper type). 21. The lead frame (10) (11) according to the above 20, comprising a material), or a material having a surface plated with a copper-based material or a zinc-based material.
22. A lead frame that constitutes the first and second metal members is prepared, and at least in the vicinity of the position to be drawn from the sealing resin among the connection portions with the cathode portion corresponding to the second metal member, the lead frame is temporarily covered After performing the above, low melting point metal plating is performed, the temporary coating is removed, the anode part and the cathode part of the capacitor element are mounted and bonded to the first and second metal members, respectively, and then sealed with resin. The manufacturing method of the solid electrolytic capacitor characterized by including a process.
23. 23. The method for manufacturing a capacitor as described in 22 above, wherein the temporary coating is performed by strip masking.
24. The capacitor element sequentially forms an insulating layer made of a metal oxide, a solid electrolyte layer, and a conductive paste layer on at least a part of the surface of the valve action metal having a porous layer on the surface, and the exposed part of the valve action metal serves as an anode part. 24. The method for producing a solid electrolytic solid electrolytic capacitor as described in 22 or 23 above, which is a capacitor element having a conductive paste layer as a cathode portion.

When the low melting point metal plating is applied and the low melting point metal plating is melted by reflow, a gap is generated at the interface between the sealing resin and the lead frame, and this gap may cause the moisture resistance to deteriorate. The element can be securely bonded to the metal member, and solder balls can be prevented from being generated by plating and melting on the metal member even after heating such as sealing and reflow. Therefore, a solid electrolytic capacitor having excellent moisture resistance and high reliability can be obtained, and its industrial production is easy.
In addition, according to the present invention, the capacitor element and the lead frame can be joined by resistance welding, and the resin-encapsulated solid electrolytic capacitor is excellent in heat resistance, has high resin-sealing integrity, and excellent in moisture resistance.
Furthermore, according to the present invention, a lead frame subjected to low melting point metal plating can be used, so there is no need to increase the post plating step. In the case of resistance welding, anodic bonding in a laminate is easy.

  In the present invention, an anode part of a capacitor having an anode part and a cathode part provided with an insulating layer sandwiched is joined to a first metal member, a cathode part is joined to a second metal member, and a part of each metal member Any capacitor can be used as long as it is a resin-sealed capacitor so as to be exposed, but it is particularly suitable for a capacitor in which the cathode portion is placed on the second metal member and joined by heating or the like. Applicable. In a typical example of such a capacitor, an insulating layer made of a metal oxide, a solid electrolyte layer, and a conductive paste layer are sequentially formed on at least a part of the surface of a valve metal having a porous layer on the surface to expose the valve metal. It is a solid electrolytic capacitor including a capacitor element in which the part is an anode part and the conductive paste layer is a cathode part.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the present invention, first, one end of a base body (1) made of a valve metal having a dielectric coating layer (2) is used as an anode section (6), and is in contact with the anode section (6) on the base body (1). An insulating layer (3) having a predetermined width is formed around the insulating layer to form an insulating portion, and the solid electrolyte layer (4) and the conductor layer (5) are formed on the dielectric coating layer in a range excluding the anode portion (6) and the insulating portion. ) Are sequentially laminated to form a single plate capacitor element (8) as a cathode portion (7) or a capacitor element (15) in which a plurality of these are laminated.

  As shown in FIG. 1, the single-plate capacitor element (8) has an anode portion (6) at one end of a base body (1) made of a valve metal having a dielectric film layer (2) on the surface. An insulating layer (3) having a predetermined width is provided around the base (1) in contact with the portion (6) to form an insulating portion. A solid electrolyte layer (4) is coated on the dielectric film layer excluding the anode portion (6) and the insulating portion, and a conductor layer (5) is further provided thereon, whereby the cathode portion (7) is formed. In the capacitor element (8), the cathode / anode part is bonded to the metal member as it is, or the cathode part and the anode part are respectively connected to the metal member on one surface of the capacitor element laminate (15) formed by laminating the elements. Bonding is performed (FIG. 2A), or the metal member (10) is bonded to the center of the capacitor element laminate (15) (FIG. 6) and the whole is sealed.

[Capacitor element]
The substrate (1) may be any one selected from valve metals that can form an oxide film such as a single metal such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, or silicon, or an alloy thereof. The form of the substrate (1) may be any form as long as it is a form of a porous molded body such as an etched product of rolled foil or a fine powder sintered body. Although the thickness of a conductor changes with purposes of use, for example, a foil having a thickness of about 40 to 300 μm is used. Although the size and shape of the metal foil vary depending on the application, a rectangular element having a width of about 1 to 50 mm and a length of about 1 to 50 mm is preferable as a flat element unit, more preferably about 2 to 15 mm in width and about 2 in length. ~ 25 mm.

As the conductor, a porous sintered body of these metals, a plate (including a ribbon, a foil, etc.) surface-treated by etching or the like can be used, and preferably a flat plate or a foil. Furthermore, a known method can be used as a method of forming a dielectric oxide film on the surface of the porous metal body. For example, when an aluminum foil is used, an oxide film can be formed by anodizing in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or a sodium salt or an ammonium salt thereof. Moreover, when using the sintered compact of a tantalum powder, it can anodize in phosphoric acid aqueous solution and can form an oxide film in a sintered compact.
The metal used for the substrate (1) generally has a dielectric oxide film on the surface by air oxidation, but it is preferable to form the dielectric film surely by performing a chemical conversion treatment.

  The insulating layer (3) may be formed by applying an insulating resin, a composition comprising an inorganic fine powder and a cellulose resin (described in JP-A-11-80596), or may be formed by applying an insulating tape. . Although not limited to insulating materials, specific examples include polyphenylsulfone (PPS), polyethersulfone (PES), cyanate ester resin, fluororesin (tetrafluoroethylene, tetrafluoroethylene / perfluoroalkylvinylether). Polymer, etc.), low molecular weight polyimide and derivatives thereof and precursors thereof, and a composition comprising soluble polyimide siloxane and an epoxy resin (described in Japanese Patent Application Laid-Open No. 08-253676 (related application US5643986)). Particularly preferred are low molecular weight polyimides, polyethersulfones, fluororesins and their precursors. Any method may be used as long as an insulating material can be formed on the anode substrate (1) with a predetermined width.

  The solid electrolyte layer (4) may be formed of any one of a conductive polymer, a conductive organic material, a conductive inorganic oxide, and the like. In addition, a plurality of materials may be sequentially formed, or a composite material may be formed. Preferably, a known conductive polymer, for example, a conductive polymer containing at least one divalent group of pyrrole, thiophene, or aniline structure or a substituted derivative thereof as a repeating unit can be used. For example, a method in which a 3,4-ethylenedioxythiophene monomer and an oxidizing agent are preferably applied in the form of a solution, separately or together, and applied to an oxide film layer of a metal foil (JP-A-2-15611). Publications (US4910645 specification), JP-A-10-32145 (described in related application US6229689 specification) and the like can be used.

  In general, a dopant is used for the conductive polymer, and any dopant compound can be used as the dopant. For example, organic sulfonic acid, inorganic sulfonic acid, organic carboxylic acid and salts thereof can be used. In general, an aryl sulfonate dopant is used. For example, salts such as benzenesulfonic acid, toluenesulfonic acid, naphthalenesulfonic acid, anthracenesulfonic acid, anthraquinonesulfonic acid, or substituted derivatives thereof can be used. Further, as a compound that can bring out particularly excellent capacitor performance, a compound having one or more sulfonic acid groups and a quinone structure in the molecule, a heterocyclic sulfonic acid, an anthracene monosulfonic acid, or a salt thereof may be used. Good.

  The conductor layer (5) is generally formed by applying a carbon paste (5a) as a base and applying a silver paste (5b) thereon, but it may be formed only by applying a silver paste. The conductor layer may be formed by this method.

  The same effect can be obtained when the capacitor element is a single plate capacitor element (8) or a multilayer capacitor element (15). As shown in FIG. 2A, the multilayer capacitor element (15) is formed by laminating a plurality of single plate capacitor elements (8) (four in the illustrated example) and forming a cathode portion (7) between the capacitor elements (8). In between, they are integrally joined by a conductive paste (9) such as a silver paste.

[Cathode structure of cathode lead frame]
As shown in FIGS. 2A and 2B, the solid electrolytic capacitor of the present invention preferably has a cathode-side end portion and a cathode-side lead frame tip portion of the insulating layer of the capacitor element at the joint portion between the electrolytic capacitor element and the lead frame. And a bonding structure having a certain interval between them. That is, it has a structure in which the tip corner (11a) of the cathode side lead frame is separated from the insulating part (3) of the capacitor element and joined to a predetermined position of the cathode part (7) with a predetermined interval t. The position (the length of the interval t) of the cathode side lead frame tip corner portion (11a) is such that the tip corner portion (11a) is the length of the cathode portion (7) from the cathode side end portion (3a) of the insulating layer. It suffices that the distance is 1/40 or more and at most within a range of 1/2 or less of the length of the element cathode portion (7). If the distance t is maintained, the stress concentration of the element near the lead frame tip corner portion (11a) can be reduced at the cathode-side junction, and excessive silver paste can be applied from the vicinity of the insulating portion boundary to the dielectric layer. Therefore, it is possible to prevent the leakage current from increasing due to reflow soldering at a high yield. In order to prevent an increase in resistance of the cathode portion, the position of the lead frame tip corner portion (11a) is 1/20 or more of the length of the cathode portion (7) from the cathode side end (3a) of the insulating layer. / 3 or less is preferable. More preferably, it is 1/10 or more and 1/4 or less of the length of the cathode part (7). The length of the cathode portion (7) is the length from the cathode side end (3a) of the insulating layer (3) to the tip portion where the conductive layer (5) is formed.

  As described above, as a method of accurately placing the capacitor element on the lead frame, as shown in FIGS. 4A and 4B, the elements of the lead frames (10) and (11) can be confirmed so that the placement position of the element can be confirmed. A mark (12) indicating the bonding position may be attached to the surface on the mounting side by half etching or laser light. With this mark, the capacitor element can be easily positioned. Note that the shape of the mark is not limited, and any shape may be used as long as the position is known, whether linear or round.

  In the solid electrolytic capacitor of the present invention, preferably, as shown in FIG. 2B, the cathode side lead frame tip corner (11a) is chamfered in the plate thickness direction. In other words, the edge portion of the tip is slightly flattened or processed into a rounded shape. By processing the lead frame tip corner in this manner, the stress concentration of the element near the tip corner can be further alleviated.

  Further, as shown in FIG. 4B, as a method of reducing the resistance of the cathode and the lead frame joint portion of the anode, the window portion of the lead frame is not provided. As shown in FIG. 5, a lead frame having a window portion (13) provided in advance at a predetermined position is known. After the capacitor element and the lead frame are joined, the entire capacitor element is sealed with a mold resin. The window portion (13) protrudes from the resin when the lead is formed along the exterior resin (10 ) (11) is provided to facilitate the bending process, and the cross-sectional outer peripheral length of the lead led out from the exterior resin is reduced to reduce the amount of water entering through the interface between the lead and the resin. It is provided in order to prevent deterioration of the device by decreasing. However, by providing the window portion, the resistance increases because the cross-sectional area of this portion decreases. If the window is omitted, this resistance can be reduced. For example, by eliminating the window portion, the series resistance value of the capacitor element can be improved by about 5%. The lead frame window portion is devised by devising the plating layer on the surface of the lead frame, and further using water-repellent resin as a binder for the conductor layer forming the capacitor element to prevent moisture from entering the element. Can be omitted. Further, when the window portion is removed, it is not necessary to remove the extra exterior resin clogged in the window portion by shot blasting, and the manufacturing time can be shortened.

[Anode-side lead frame joint structure]
When the anode side lead frame (10) is joined to the anode part (6) of the capacitor element, the junction part of the anode side lead frame (10) is subjected to low melting point metal plating. The plated portion is overlaid with the anode portion (6) where the dielectric film (2) of the capacitor element is exposed, and resistance welding is performed thereon. In addition, iron-nickel alloys mainly composed of iron and nickel, zinc materials, copper materials, or copper alloys obtained by adding tin, nickel, iron, etc. to copper as lead frame materials are generally used in various electronic devices. However, the bonding method of the present invention can be widely applied to those formed of these general lead frame materials. Among these, it is particularly useful for a lead frame formed of a highly conductive material made of copper or a copper alloy.

  The lead frame material is not particularly limited as long as it is generally used. Preferably, copper-based (for example, Cu-Ni-based, Cu-Sn-based, Cu-Fe-based, Cu-Ni-Sn-based, Cu-Co-P-based, Cu-Zn-Mg-based, Cu-Sn-Ni-P-based) By using a material such as an alloy) or a material plated with copper or zinc on the surface, the lead frame shape can be devised to further reduce the resistance, and the lead frame tip corner The effect of improving the chamfering workability of (11a) is obtained.

  As the low melting point metal plating, a metal or alloy having a melting point lower than that of the valve action metal is used. In general, the plating material for the lead frame is mainly silver, and other than this, gold, nickel, copper, tin, solder (Sn-Pb alloy), etc. are used, but when using aluminum formed foil as a valve action metal , Tin (melting temperature 505K), lead (melting temperature 600K), zinc (melting temperature 693K), its alloy (solder: 6Sn-4Pb), or other low melting point alloys (melting temperature 933K), aluminum (melting temperature 933K) fusible alloy) and various solder materials are used. The thickness of the plating layer may be any thickness that can be melted so that the bonding between the valve metal substrate (1) of the anode portion (6) and the lead frame (10) has a sufficient bonding strength. A thickness of ˜100 μm, preferably about 1-50 μm, is appropriate. Moreover, the surface plating may be superimposed on the base plating.

  The plating metal preferably has a low content of lead or a lead compound that causes environmental pollution, and a suitable example thereof is a nickel base plating with a tin surface plating. This does not include lead, and by plating tin on the nickel base plating, not only the adhesion strength of the tin plating to the lead frame is increased, but also the single plate capacitor element, tin plating and lead frame are not welded. Adhesive strength increases.

  By superposing the anode end portion (6) of the capacitor element on the low melting point metal plating portion of the anode side lead frame (10) and performing resistance welding, the specific resistance of the dielectric film (2) of the anode end portion (6) is increased. The joining portion generates heat, the plated metal of the lead frame (10) is melted, and the lead frame (10) and the anode end (6) are joined together. When an aluminum conversion foil or the like is used as a substrate, the surface of the aluminum conversion foil is melted by the resistance heat generation of the dielectric film (2), and the surfaces of the aluminum conversion foil laminated on the anode portion are melted together and integrated. To be joined.

  2A, the lead frame is joined to the side surface (outer peripheral side) of the multilayer capacitor element 15 as shown in FIG. 2A, or the multilayer capacitor element 15 as shown in FIG. The present invention can be applied to any case where the lead frame (10) is joined to the central portion. In the junction structure shown in FIG. 6, the number of laminated single plate capacitor elements is arbitrary, and the number of capacitor elements stacked on the upper side and the lower side of the lead frame may be different.

  Resistance welding can be performed according to normal construction procedures. The welding conditions are appropriately determined according to the type of valve metal, the shape of the foil (thickness, dimensions, etc.), the number of layers, the material of the lead frame, the type of low melting point metal, and the like. As an example, when using a copper lead frame with nickel-tin plating and laminating 4 to 8 single plate capacitor elements made of aluminum conversion foil of about 100 μm, the pressure is about 3 to 5 kg. As shown in FIG. 7, the electrode is pressed against the joining portion, and welding is performed with an energy of about 6.5 to 11 W · s according to a peak current 2 to 5 kA, energization time 1 to 10 ms, and a middle pulse application pattern.

The pattern of the low melting-point plating layer of the lead frame of this invention is shown.
Plating pattern 1
Lead frame (10), (11) portion (23) or lead frame other than (23) and (24) in contact with a single plate capacitor element (8) or a capacitor element (15) laminated with a plurality of sheets is strip-shaped masked, For example, by taping, the lead frame (10) (11) in contact with the resin (28) in the sealing portion (20) of the resin (28) is not subjected to low melting point metal plating, and the portion (23) or ( 23) and (24) lead frame (10) (11) subjected to low melting point metal plating is bonded to the anode part (6) and cathode part (7) of the capacitor element (8) (15), and resin ( 28) to produce a solid electrolytic capacitor.

  The lead frame (10) (11) portion (23) or the lead frame other than (23) and (24) in contact with the capacitor elements (8) and (15) is masked in strips (which will be described in the following example of taping). As a result, in the resin (28) sealing portion (20), the lead frame (10) (11) in contact with the resin (28) is not subjected to low melting point metal plating, and the portion (23) or (23) It is only necessary to attach a tape so that the low melting point metal plating can be applied only to (24), and there is no particular limitation on the plating method for applying such a low melting point metal plating. Stripe plating in which partial melting point metal plating is partially applied is preferable. The joining of the lead frame and the capacitor element is not particularly limited, such as resistance welding, welding by spot welding, adhesion by a conductive paste or the like, but resistance welding is preferable in the anode part, and adhesion by conductive paste is preferable in the cathode part.

[Joint by partial plating]
As shown in FIG. 8, in the resin-sealed portion (20) of the lead frame, the lead frame portions (21) and (22) with which the mold resin (28) contacts are not plated, and the lead frame is connected to the capacitor element (26 The lead frames (10) (11) and the capacitor elements (8) (15) in which low melting point metal plating is applied to the parts (23) and (24) in contact with the metal parts (23), in particular (23) with which the anode part (6) contacts. Have a structure in which
In this plating process, the lead frame (10) (11) portion (23) or the lead frame other than (23) and (24) in contact with the capacitor elements (8) (15) is taped. Thus, in the taping, the lead frame (10) (11) in contact with the resin (28) is not subjected to low melting point metal plating in the sealing portion (20) of the resin (28). It is only necessary to attach a tape so that low melting point metal plating can be applied only to 23) and (24). Although there is no particular limitation on the plating method for performing such low melting point metal plating, stripe plating in which a taped lead frame is supplied to partially plate the low melting point metal plating necessary portion is preferable.

  When lead frames (10) and (11) made of a copper-based material are used, in the resin-encapsulated portion (20), for example, lead frame surface portions (21) and (22) with which the mold resin (28) contacts, and the lead frame (10) The back surface of (11) is in a state where the base surface of the copper-based material is exposed, while the surface portions (23) (24) where the lead frame (10) (11) contacts the capacitor element (26), In particular, low melting point metal plating is applied to (23) where the anode part (6) contacts. An example of this low melting point metal plating is a nickel base plating provided with tin plating. In the figure, portions (30) and (31) are window portions (punched portions), and as described above, these portions may not be provided. Further, the portion (32) of the lead frame (10) (11) coming off from the mold resin (28) may be plated. Accordingly, in the resin-encapsulated portion (20), the surface portions (23) and (24) where the lead frames (10) and (11) are in contact with the capacitor element (26), particularly the anode portion (6) are in contact with (23). Is plated, and the surface portions (21) and (22) in contact with the mold resin (28) are not plated. If necessary, stripe plating is also applied to the back side.

  As shown in FIG. 12, in the resin-encapsulated portion (20), low melting point metal plating is applied only to the lead frame surface of the portion (23) or (23) and (24) in close contact with the capacitor element (26). ing. A single plate capacitor element (8) is stacked on the plated part, and the cathode part is bonded between the cathode parts (7) and between the cathode part (7) and the lead frame (11) with a conductive paste (9). On the other hand, on the anode part side, the anode parts (6) of the capacitor elements (8) are brought into close contact with each other while being pressed, and the anode parts (6), the lower surface of the anode part (6) and the lead frame surface (23). Are joined by spot welding or the like to obtain a multilayer capacitor element (26). As shown in FIGS. 13 and 14, after the multilayer capacitor element (26) is molded with resin (28), the resin-molded capacitor element is cut off from the lead frame, and the leads (10) and (11) are bent to obtain solid electrolytic. A capacitor (29) is obtained. In FIG. 8, in the resin-encapsulated portion (20) of the lead frame, the lead frame portions (21) and (22) with which the mold resin (28) contacts are not plated, and the lead frame is the capacitor element (26). The lead frames (10) (11) and the capacitor elements (8) (15), which are subjected to low melting point metal plating, are joined to the portions (23) and (24) in contact with the capacitor elements. A structure may be adopted in which the lead frames (10), (11) and the capacitor elements (8), (15), which are subjected to low melting point metal plating only on the contact (23), are joined.

Plating pattern 2
As the metal member, for example, as shown in FIG. 10, a lead frame having a structure that is continuous from side to side is preferable. The lead frame is one in which a plurality of portions (20) to be sealed with resin are integrally held by frame portions (10), (11), and (32), and the portion (20) to be sealed with resin. Includes a junction portion (21) with the capacitor element anode portion and a junction portion (24 ') with the capacitor element cathode portion. As shown in FIGS. 3 and 6, the anode part (6) of the capacitor element is joined to the joining part (21), and the cathode part (7) is joined to the joining part (24 ′). In the structure of the present invention, as shown in FIG. 10, the region not including the low melting point metal plating layer is in the vicinity of the position where the junction (24 ′) with the capacitor element cathode portion is led out from the sealing resin and exposed. It is a junction part (25) with a cathode part, It is characterized by the above-mentioned. In FIG. 10, a region not including the low melting point metal plating layer is not provided on the anode side, but the plating structure of the anode part of the present invention is not particularly limited, and the anode part is similar to the anode part of FIG. 9. A portion not including the low melting point plating layer may be provided (see FIG. 11).

  The joint portion (25) with the cathode portion in the vicinity of the position where the joint portion (24 ′) with the capacitor element cathode portion is led out from the sealing resin and exposed is sealed as much as possible as a cathode / anode terminal after resin sealing. It is a joint part close to the part left outside the stop resin. As shown in FIG. 10, a lead frame is known in which windows (30) and (31) are previously provided at predetermined positions. After the capacitor element and the lead frame are joined, the entire capacitor element is sealed with a mold resin. The windows (30) and (31) are leads protruding from the resin when the leads are formed along the exterior resin. Water that is provided for facilitating bending of the frames (10) and (11), and that enters through the interface between the lead and the resin by reducing the outer peripheral length of the cross section of the lead derived from the exterior resin. It is provided to prevent the deterioration of the device by reducing the amount of. In the present invention, a region not including the low melting point metal plating layer is provided in the vicinity of the window portion (a position corresponding to the window portion when the window portion is not provided) and in a region bonded to the cathode portion of the capacitor element.

  Here, “near” depends on the overall size and shape of the capacitor element, but when the junction (24) with the capacitor element cathode is rectangular, the position exposed from the sealing resin is exposed. As a reference, it is an area within about 30% of the entire length of the junction with the cathode. The region that does not include the low melting point metal plating layer may be provided in any shape and size within this region (range indicated by t ′ in FIG. 10), but the entire junction with the cathode portion as shown in FIG. In the case of a rectangle, for example, a band-like region having a width of 0.5 mm or more is used. The region not including the low melting point metal plating layer is set so as to contact the position where the metal member is led out from the sealing resin and exposed.

  By designing the region not including the low melting point metal plating layer in this way, the generation of solder balls is suppressed even after heating such as sealing and reflow. The reason why solder balls do not occur is not simply because the low melting point metal plating layer does not exist in the vicinity of the lead part of the metal member (normally, the inner plating layer also melts during heating, so the vicinity of the lead part) For example, even if the low melting point plating layer is not provided, the inner plating layer melts and flows out to become solder balls), for example, a region where the low melting point metal plating layer does not exist becomes a recess (groove), and this is a capacitor element cathode It is conceivable that a part of the conductive paste bites in and forms a block layer that stops the outflow of hot-dip plating from the inside.

  The metal member that joins the capacitor element, typically a part of the lead frame, is formed with a different plating structure from the others. This can be achieved by applying any temporary covering means such as taping to a desired position. realizable. That is, a lead frame constituting the first and second metal members is prepared, and taping is performed at least in the vicinity of the position where the lead metal corresponding to the second metal member should be drawn from the sealing resin. After that, low melting point metal plating is performed to remove taping. Although there is no particular limitation on the plating method for performing such low melting point metal plating, stripe plating in which a taped lead frame is supplied to partially plate the low melting point metal plating necessary portion is preferable.

  Hereinafter, the present invention will be specifically described by way of examples. The scope of the present invention is not limited by the following examples.

Example 1
A single plate capacitor element (8) shown in FIG. 1 was produced (manufactured) as follows. An aluminum (valve action metal) etching foil having a thickness of 90 μm, a length of 5 mm, and a width of 3 mm having an alumina dielectric film on the surface is used as the substrate (1). The anode part (6) and the remaining 3 mm × 3 mm part are immersed in a 10% by weight ammonium adipate aqueous solution and formed under a voltage of 4 V to form a dielectric oxide film layer (2) at the cut edge. The body. The dielectric surface was impregnated with an aqueous solution prepared to 20% by mass of ammonium persulfate and 0.1% by mass of sodium anthraquinone-2-sulfonate, and then 1.2 mol / L in which 5 g of 3,4-ethylenedioxythiophene was dissolved. In an isopropanol solution. The substrate was taken out and left in an environment of 60 ° C. for 10 minutes to complete the oxidation polymerization and washed with water. This polymerization reaction treatment and the washing step were each repeated 10 times to form a conductive polymer solid electrolyte layer (4). Next, this is immersed in a carbon paste tank and solidified to form a conductor layer (5a), and further immersed in a silver paste tank and solidified to form a conductor layer (5b). The thickness of the layer (5) was gradually increased toward the tip to obtain a single plate capacitor element (8) having a slightly thick tip.
Next, a 0.1 mm-thick copper base material was punched into a lead frame shape by pressing as shown in FIG. 8, and the surface thereof was nickel-undercoated and tin-plated thereon. However, in the resin-encapsulated portion (20), the portions (21) and (22) that are in contact with the mold resin (28) are not subjected to tin plating, and a portion (23) of the portion that is in close contact with the capacitor element (lead frame) And (24) (island-like portion on the cathode side of the lead frame and having an interval between the anode-side ends) The above plating treatment was applied only to
In this plating process, the lead frame (10) and the lead frame other than the portions (23) and (24) of (11) in contact with the resin (28) encapsulated solid electrolytic capacitor element (26) are masked by taping, and striped. Plated.
Three sheets of single plate capacitor elements (8) are stacked on the plated portion of the resin-sealed portion (20), and the anode portions (6) are aligned to the left in the figure and the cathode portions (7) are aligned to the right. A single plate capacitor element (8) is spread out by adhering between the cathode part (7) and the cathode part (7) and between the cathode part (7) and the lead frame (11) with a conductive paste (9). It was set as the laminated body piled up on. While the anode part (6) of this multilayer body is bent, the anode parts, and one side surface (23) of the lead frame (10) and the lower surface of the anode part (6) are spot-welded, whereby the multilayer capacitor element shown in FIG. 26) was obtained. As shown in FIGS. 12 and 13, after the entire multilayer capacitor element (26) is molded with an epoxy resin (28), resin burrs at the time of molding are removed by a shot blast method of resin beads, and then the lead frame is formed. Then, the resin-encapsulated capacitor element was cut off, and the leads were bent into a predetermined shape as shown in FIG. 12 to obtain 50 solid electrolytic capacitors (29).

Example 2 and Comparative Examples 1 and 2
A capacitor element (8) was produced in the same manner as in Example 1. Similarly to Example 1, as shown in FIG. 9, a 0.1 mm-thick copper base material was punched into a lead frame shape by pressing, a nickel base plating (thickness 0.1 μm) on the surface, and tin plating ( Thickness 6 μm). However, in the resin-encapsulated portion (20), the portions (21 ′) and (25 ′) that are in contact with the mold resin (28) are not subjected to tin plating and include a surface in close contact with the capacitor element (23 ′) (anode side) The plating treatment was performed only on the cathode-side end portion and (24 ′). In this plating process, the lead frame other than the lead frames (10) (11) (23 ′) (24 ′) with which the resin (28) -encapsulated solid electrolytic capacitor element (26) comes into contact is taped and stripe-plated.
Using this lead frame, 50 solid electrolytic capacitors were obtained in the same manner as in Example 1.
15A and 15B show a comparative reference solid electrolytic capacitor (Comparative Example 1) provided with a lead frame (reference LF) obtained without taping, and a lead frame (striped plating) obtained by taping. (LF) Leakage resistance test results obtained by measuring the leakage current LC (μA), capacitance CAP (μF), dielectric loss DF (%), and equivalent series resistance ESR (mΩ) over time of the solid electrolytic capacitor of the present invention (LF) ( 60 ° C., 95% RH). In the result of no taping after 2000 hours, the capacitance CAP and the dielectric loss DF are increased, which indicates that moisture has entered the resin, and the leakage current LC is thereby increased. On the other hand, in the result of the striped striped product, the entry of moisture is suppressed, and the increase in the leakage current LC is only 1/10, indicating that there is an effect of moisture resistance.
Further, as Comparative Example 2, 20 capacitors similar to Example 1 were obtained using a lead frame (reference LF) obtained without taping. The capacitors of Example 2 and Comparative Example 2 were subjected to a moisture resistance test, and the leakage current LC after 1000 hours was measured. The number of defects was determined using a capacitor having a leakage current of 0.3 CV or more as a defective product. The results are shown in Table 1.

Example 3 and Comparative Example 3
Niobium powder (approx. 0.1 g) is placed in a tantalum element automatic molding machine (TAP-2R manufactured by Seken Co., Ltd.) hopper and automatically molded with a 0.28 mmφ niobium wire to form a molded body having a size of 4.4 mm × 3.0 mm × 1.8 mm. Created. The compact was left to stand at a voltage of 1250 for 30 minutes under a reduced pressure of 4 × 10 ⁻³ Pa to obtain a sintered body. A total of 60 sintered bodies were prepared and subjected to electrolytic conversion in a 10% by mass phosphoric acid aqueous solution at a voltage of 12 V for 360 minutes to form a dielectric oxide film on the surface. Next, after contacting an equal mixture of 12% by weight ammonium persulfate aqueous solution and 0.5% by weight aqueous solution of anthraquinone sulfonic acid on the dielectric oxide film, the operation of touching pyrrole vapor was performed 12 times from polypyrrole. A counter electrode (counter electrode) was formed. After 30 minutes of washing in deionized water, drying was performed at 105 ° C. for 30 minutes. Thereafter, re-chemical conversion was performed at 8 V for 30 minutes in a 1.0 mass% phosphoric acid aqueous solution.
After washing in deionized water for 30 minutes, it was dried at 105 ° C. for 30 minutes. After dipping the carbon paste, it was dried at 80 ° C. for 30 minutes and further at 150 ° C. for 30 minutes, then immersed in a silver paste, dried at 80 ° C. for 30 minutes, and further dried at 150 ° C. for 30 minutes to produce a capacitor element. The device was placed on the same stripe-plated lead frame as that prepared in Example 1 (where the cathode portion is bent) and the reference lead frame of Comparative Example 1 (where the cathode portion is bent), After bonding with silver paste and further anodic bonding, the entire device was sealed with an epoxy resin, a rated voltage was applied at 120 ° C., and aging was performed for 3 hours, and a total of 60 solid electrolytic capacitors were produced. Using this capacitor, a moisture resistance leaving test was conducted in the same manner as in Example 1. The leakage current after 500 hours was measured, and the leakage current value of 0.3 CV or more was regarded as defective as in Example 2 and the number was counted. The results are shown in Table 2.

Example 4 and Comparative Example 4
Sixty capacitor elements were produced in the same manner as in Example 3 to produce a capacitor. However, for the lead frame, the stripe plating LF (provided with cathode part bending) used in Example 2 and the reference LF (provided with cathode part bending) were used, and 30 capacitors were produced. In the same manner as in Example 3, a moisture resistance test was performed, the leakage current after 500 hours was measured, 0.3 CV or more was regarded as defective, and the number was counted. The results are shown in Table 3.

Comparative Example 5
Only the base nickel plating (thickness: 0.1 μm) was performed on the lead frame (23) in Example 1, and a lead frame without low melting point plating was produced. Although resistance welding was attempted on the anode part, traces of electrode contact were observed, but welding of the aluminum conversion foil was difficult.

Examples 5 and 6, Comparative Examples 6 and 7
A capacitor element was manufactured as follows.
Width by masking material (heat-resistant resin) on an aluminum chemical conversion foil (manufactured by Nippon Electric Power Industry Co., Ltd., foil type 110LJB22B11VF) (hereinafter referred to as chemical conversion foil) having a minor axis direction of 3 mm × major axis direction of 10 mm and a thickness of about 100 μm. A 1mm mask is formed in a circumferential shape, divided into a cathode part (7) and an anode part (6), and the cathode part (7), which is the tip side partition part of this chemical conversion foil, is used as an electrolyte with an aqueous solution of ammonium adipate Then it was formed and washed with water. Next, the cathode part (7) was immersed in 1 mol / l of an isopropyl alcohol solution of 3,4-ethylenedioxythiophene and allowed to stand for 2 minutes, and then an oxidizing agent (ammonium persulfate: 1.5 mol / l) and a dopant (naphthalene). 2-sodium sulfonate: 0.15 mol / l) was immersed in a mixed aqueous solution and left to stand at 45 ° C. for 5 minutes for oxidative polymerization. This impregnation step and the polymerization step were repeated 12 times in total to form a solid electrolyte layer containing a dopant in the micropores of the chemical conversion foil. The chemical conversion foil in which the solid electrolyte layer containing this dopant was formed was washed with 50 degreeC warm water, and the solid electrolyte layer was formed. After forming the solid electrolyte layer, it was washed with water and dried at 100 ° C. for 30 minutes. A carbon paste and a silver paste were coated thereon to form an element (8).

Four of these elements were stacked on a lead frame described below, and sealed with an epoxy resin (HENKEL MG33F-0593) to obtain a sample.
As shown in FIG. 10, except for the sample 1, the lead frame was subjected to Ni plating of 0.5 to 1.5 μm (per one side) on a 100-micron thick copper plate of the US copper extension standard CDA194000 on the entire surface (both sides), and then a predetermined Excluding the position, 5-7 μm (per one side) plated with Sn was used. The excluded area (25) is as follows.
Sample 1 (Comparative Example 6): All junctions with the capacitor element (with Cu base)
Sample 2 (Example 5): 1 mm (t ′) range from the lead-out part on the cathode side (band shape)
Sample 3 (Example 6): Range of 0.67 mm (t ′) from the lead-out portion on the cathode side (band shape)
Sample 4 (Comparative Example 7): No exclusion region (t ′ = 0)

Characteristic evaluation of each material was performed by imposing the condition of 262 ° C. × 10 seconds without forming, after passing through the screening process. As a result, in Sample 4, generation of solder balls was observed in 27 out of 32 samples (visual observation). On the other hand, in Samples 1 to 3, no solder balls were observed in any of the 32 samples.
Table 4 shows the measurement results of the electrical characteristics.

  As shown in the above table, in Examples 5 and 6 in which the low melting point exclusion region is provided in the vicinity of the conductor lead-out portion according to the present invention, no solder balls are observed, and the electrical characteristics are not significantly degraded even by reflow. I can't.

Examples 7 and 8 and Comparative Example 8
A capacitor was produced by the method shown in Example 5. However, as shown in FIG. 11, only the plating pattern on the anode side was changed as the lead frame. The lead frame is different from the fifth embodiment in that the resin-encapsulated portion (20) is not subjected to tin plating on the portion (21 ′) in contact with the mold resin (28). The areas excluding tin plating on the cathode side are as follows.
Sample 5 (Example 7): 1 mm from the lead-out part on the cathode side (band shape)
Sample 6 (Example 8): 0.67 mm range from the lead-out part on the cathode side (band shape)
Sample 7 (Comparative Example 8): No exclusion region The characteristics of each sample and the generation of solder balls were evaluated in the same manner as in Example 5.

Since the solid electrolytic capacitor of the present invention has the above structure, it has the following excellent effects.
(A) A highly reliable solid electrolytic capacitor excellent in moisture resistance can be obtained without generating a gap due to heat melting in the resin-sealed portion, and its industrial production is easy.
(B) The capacitor element and the lead frame can be joined by resistance welding, and then the resin-encapsulated solid electrolytic capacitor has excellent heat resistance, high resin-sealing integrity, and excellent moisture resistance.
(C) Since a lead frame subjected to low melting point metal plating can be used, there is no need to increase the post-plating step. In the case of resistance welding, anodic bonding in a laminate is easy.
(D) In the resin-encapsulated portion, the low melting point plating is applied only to the portion where the capacitor element contacts, thereby preventing the occurrence of bonding defects due to solder balls and the like. A solid electrolytic capacitor having good stability and high reliability can be obtained.
(E) The anode side lead frame and the valve action metal foil (plate) of the capacitor element can be easily and firmly joined using resistance welding. Therefore, the multilayer capacitor element and the solid electrolytic capacitor can be manufactured with good economic efficiency. In particular, since a lead frame made of a highly conductive material such as copper or a copper compound and a substrate such as an aluminum conversion foil can be bonded with high reliability, it is highly practical. Moreover, since a plating material containing no lead or lead compound can be used, there is no problem in environmental pollution.
(F) When the capacitor element is placed and bonded to the lead frame, the element is placed at a predetermined interval without approaching the tip corner of the cathode side lead frame in the vicinity of the insulating layer of the element. When the corners are chamfered, a capacitor with good yield and heat resistance can be obtained. Furthermore, when the lead frame is not provided with a window portion, a special effect of suppressing an increase in the resistance of the lead frame can be obtained, and when a lead frame in which the mark of the joint position is marked by half etching or the like is used, the lead frame is used. The element placed on the frame can be positioned accurately and easily.

1 is an example of a cross-sectional view showing a structure of a single plate capacitor element used in the present invention. FIG. 2A is an example of a cross-sectional view (FIG. 2A) of the multilayer capacitor element of the present invention and an enlarged view (FIG. 2B) in the vicinity of the tip corner of the cathode side lead frame (A). An example of a cross-sectional view of a capacitor element having a lead frame position of 0 mm (t = 0). The side view (FIG. 4A) of the lead frame of this invention, and an example of the top view (FIG. 4B). An example of the top view of a lead frame with a window part. An example of sectional drawing of the multilayer capacitor element of the present invention. An example of the graph which shows the pattern of the applied current of resistance welding in this invention. FIG. 3 is a partial plan view of a lead frame showing an example of partial plating according to the present invention (Example 1). FIG. 9 is a partial plan view of a lead frame showing an example of partial plating according to the present invention (Example 2). FIG. 9 is a partial plan view of a lead frame showing an example of partial plating according to the present invention (Example 5). FIG. 9 is a partial plan view of a lead frame showing an example of partial plating of the present invention (Example 7). An example of sectional drawing of the multilayer capacitor element of the present invention. An example of the partial top view of the resin-molded multilayer capacitor element of this invention. An example of sectional drawing of the multilayer type solid electrolytic capacitor of the present invention. An example of the graph (A) of the comparative moisture-resistant standing test result (reference) and the graph (B) of the present moisture-resistant standing test result (stripe plating LF).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Dielectric film layer 3 Insulating layer 3a Cathode side end 4 of insulating layer Solid electrolyte layer 5 Conductor layer 5a Carbon paste 5b Silver paste 6 Anode portion 7 Cathode portion 8 Capacitor element 9 Conductive paste 10 Lead frame 11 Lead Frame 11a Lead frame tip corner portion 12 Mark indicating joining position 13 Window portion 15 Capacitor element 20 Resin sealing portion 21 Lead frame surface (anode portion) in contact with mold resin
21 'low melting point plating exclusion part 22 lead frame surface (cathode part) in contact with mold resin
23 Lead frame portion 23 ′ in contact with the capacitor element Lead frame portion 24 including the surface in contact with the capacitor element Lead frame portion 24 ′ in contact with the capacitor element Lead frame portion 25 including the surface in contact with the capacitor element Low melting point plating exclusion portion 26 Capacitor Element 28 Mold Resin 29 Multilayer Solid Electrolytic Capacitor 30 Window 31 Window 32 Portion of Lead Frame Detached from Resin

Claims (12)

  In the solid electrolytic capacitor formed by joining the anode part and the cathode part of the solid electrolytic capacitor element to the lead frame and resin-sealing the whole so that a part of the lead frame is exposed,
  In the capacitor element, one end of a base body (1) made of a valve metal having a dielectric film layer (2) is used as an anode section (6), and is in contact with the anode section (6) on the base body (1). An insulating layer (3) having a predetermined width is provided as an insulating portion, and the solid electrolyte layer (4) and the conductor layer (5) are formed on the dielectric coating layer in a range excluding the anode portion (6) and the insulating portion. Is a single plate capacitor element (8) or a capacitor element (15) in which a plurality of these are laminated.
  As the lead frame, a low melting point metal plating is provided in a joint portion with an anode portion, and a low melting point metal plating region and a low melting point metal plating region are provided in a joint portion with a cathode portion, The region where the low melting point plating is not applied in the joint portion with the cathode portion is provided in a strip shape on the side where the cathode side lead frame is led out from the sealing resin, and the portion where the sealing resin contacts is low melting point A solid electrolytic capacitor characterized in that a lead frame not plated with metal is used and an anode part and a cathode part of a capacitor element are joined.   The lead frame region in contact with the cathode portion is rectangular, and the lead frame is formed from the sealing resin from the end of the region where the low melting point metal plating is applied to the lead frame on the cathode side in the anode bonding-cathode bonding direction of the lead frame. 2. The solid electrolytic capacitor according to claim 1, wherein a length to a position where the lead is led out and exposed is within 30% of a length of a joint portion with the cathode portion.   3. The solid electrolytic capacitor according to claim 2, wherein a width of a region where the low melting point plating provided in a strip shape is not applied is 0.5 mm or more in a joint portion with the cathode portion.   4. The solid electrolytic capacitor according to claim 1, wherein the solid electrolytic capacitor is formed by performing low-melting point metal plating after performing band-shaped masking on a portion not subjected to low-melting point metal plating. 5. 5. The solid electrolytic capacitor according to claim 1, wherein the anode part and the lead frame are joined by resistance welding using resistance heat by the dielectric film . 6. The joining of the cathode part and the lead frame is performed with a gap (t) provided between the cathode side end of the insulating layer of the capacitor element and the cathode side lead frame tip. The solid electrolytic capacitor according to item 1 . The solid electrolytic capacitor according to any one of claims 1 to 6, wherein the valve metal is selected from aluminum, tantalum, titanium, niobium, or an alloy thereof. The solid electrolytic capacitor according to any one of claims 1 to 7, wherein the lead frame is made of copper or a copper alloy (copper-based material), or a material having a surface plated with a copper-based material or a zinc-based material. The solid electrolytic capacitor according to any one of claims 1 to 8, wherein the low melting point metal plating is a metal or alloy plating having a lower melting point than the valve action metal, and the thickness of the plating layer is in the range of 0.1 to 100 µm. The solid electrolytic capacitor according to any one of claims 1 to 9, wherein the low melting point metal plating includes nickel base plating and tin surface plating. The solid electrolytic capacitor according to claim 1, wherein a multilayer capacitor element is provided on one side or both sides of the lead frame . It is a manufacturing method of the solid electrolytic capacitor according to claim 1,
One end portion of the base body (1) made of a valve metal having the dielectric coating layer (2) is used as an anode section (6), and an insulating layer having a predetermined width is formed on the base body (1) in contact with the anode section (6). (3) is provided around the insulating portion,
A solid electrolyte layer (4) is provided on the dielectric film layer in a range excluding the anode portion (6) and the insulating portion, and a conductor layer (5) is laminated thereon to form a cathode portion (7). A step of forming a plate capacitor element (8) or a capacitor element (15) in which a plurality of these are laminated,
In the lead frame, the low melting point metal plating is provided at the joint portion with the anode portion by performing band-shaped masking on the portion not subjected to the low melting point plating, followed by the low melting point metal plating. Has a region with low melting point metal plating and a region with no low melting point metal plating, and the cathode side lead frame is derived from the sealing resin in the region where the low melting point plating is not performed in the joint portion with the cathode part. A step of obtaining a lead frame which is provided in a band shape on the side where the sealing resin contacts and is not subjected to low melting point metal plating,
Joining the anode part and the cathode part of the capacitor element to each joint part of the lead frame, and
The manufacturing method of the solid electrolytic capacitor characterized by including the process of resin-sealing .

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