JP2013051377A - Chip type solid electrolytic capacitor and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heat resistance and the reliability of a chip type solid electrolytic capacitor.SOLUTION: In a chip type solid electrolytic capacitor 100, a capacitor element 110 is formed by sequentially forming a porous sintered body 111, a dielectric layer 112, a solid electrolytic layer 113, and a cathode lead-out layer 114, and an electrode substrate 130 is formed by a laminated body of dissimilar metal materials. The laminated body of the dissimilar metal materials has, for example, a double layer structure composed of nickel or nickel alloy and copper or tin. Thus, heat stress in the electrode substrate 130 is relaxed during solder mounting and the leak current rise and the occurrence of mold cracks are reduced.

Description

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

For electronic devices that require large capacity and downsizing, solid electrolytic capacitors using tantalum, niobium or the like as a valve metal, particularly surface-mounted chip-shaped solid electrolytic capacitors are used.

Patent Document 1 discloses a chip-shaped solid electrolytic capacitor using manganese dioxide as a solid electrolyte layer. For the electrode substrate portion, for example, nickel, 42 alloy (42% nickel, 58% iron), nickel alloy such as iron and white is used as a base material, copper undercoating is performed thereon, and then tin plating is further performed. Or what gave solder plating is indicated.

The reasons for using the above materials as plating materials include the connection stability between the capacitor element and the conductive adhesive used for the electrical connection between the electrode substrate and the solderability when mounting the chip components, that is, the solder wettability. This is a result of considering the above.

In addition, in the type using a conductive polymer for the solid electrolyte layer, a frame base material using a copper-based metal, silver plating, gold plating, or Palladium plating may be used.

More specifically, in the conductive polymer type chip-shaped chip-shaped solid electrolytic capacitor, as described above, high conductivity is regarded as important, and a three-layer structure of nickel / palladium / gold plating is often used.

Patent Document 2 discloses a conductive polymer type that suppresses degradation of ESR (Equivalent Series Resistance) characteristics without using expensive metals such as gold and palladium, mainly for the purpose of reducing manufacturing costs. A chip-shaped solid electrolytic capacitor is disclosed.

However, in Patent Document 2, for example, in the solder mounting process, that is, the reflow process, heat is transferred from the electrode substrate to the capacitor element, and there is a problem that the element is damaged. In order to solve this problem, it is conceivable to use a metal having a low thermal conductivity. However, the materials that can be selected are limited because of compatibility with the material that comes into contact with the metal material or the problem of conductivity.

FIG. 7 shows a conventional chip-shaped solid electrolytic capacitor. The chip-shaped solid electrolytic capacitor has a structure in which a capacitor element 11, a metal strip 12, and an electrode substrate 13 are combined. The capacitor element 11 includes a porous sintered body 14, a dielectric layer 15, a solid electrolyte layer 16, and a cathode lead. The layers 17 are sequentially formed and have an anode lead 18.

The chip-shaped solid electrolytic capacitor is roughly divided into a capacitor element 11 and an electrode substrate 13 as a part responsible for an electrical function. The base material constituting the electrode substrate 13 is required to have characteristics such as mechanical strength, heat resistance (heat peelability), thermal conductivity, and solder wettability.

Patent Document 3 discloses an invention in which, in a resin-encapsulated semiconductor device, a die pad on which a semiconductor chip is loaded is formed in a multilayer structure having a higher thermal expansion coefficient in the lower layer portion, and stress distortion due to thermal stress is alleviated. Yes.

JP-A-6-196349 JP 2008-135460 A JP-A-7-249727

In view of the above problems, the present invention has a laminated structure of a metal material made of a metal or an alloy, and the laminated structure is further processed such as a notch portion and a concavo-convex structure so that the element portion and the resin material The object is to improve the heat resistance and reliability of the solid electrolytic capacitor in a chip form by providing the contact with an optimally designed structure.

A chip-shaped solid electrolytic capacitor according to the present invention includes a porous sintered body made of a valve metal, a dielectric layer covering at least a part of the porous sintered body, and covering at least a part of the dielectric layer. A chip-shaped solid electrolytic capacitor comprising: a solid electrolyte layer; a conductive adhesive that covers at least a portion of the solid electrolyte layer; and an electrode substrate that is at least partially covered by the conductive adhesive, the electrode The substrate is a stacked structure of a plurality of metal materials.

  Furthermore, the porous sintered body, the dielectric layer, the solid electrolyte layer, and the conductive adhesive are completely embedded in a sealing resin, and a part of the electrode substrate is exposed from the sealing resin. Yes.

  In a preferred embodiment, the laminated structure of the electrode substrate is formed such that each metal material constituting the electrode substrate has a higher thermal expansion coefficient of the metal at the lower part of the element.

  In another preferred embodiment, the laminated structure of the electrode substrate is formed such that each metal material constituting the electrode substrate has a higher thermal conductivity of the metal at a lower portion of the element.

  In a more preferred embodiment, the laminated structure of the electrode substrate includes two layers of nickel or a nickel alloy and copper or tin.

  In another preferred embodiment, the laminated structure of the electrode substrate includes three layers of a nickel alloy, nickel, and copper or tin.

  In another preferred embodiment, a notch portion is present on one main surface of the electrode substrate that is not covered with the conductive adhesive, and the notch portion is at least partially covered with the sealing resin. Yes.

  In another preferred embodiment, a surface of at least a part of the electrode substrate covered with the conductive adhesive has a concavo-convex structure, and the concavo-convex structure is at least one of the laminated structures of the metal materials. Formed in the metal material layer.

  In another preferred embodiment, the concavo-convex structure is a satin finish, and the satin finish is formed in one metal material layer of the laminated structure of the metal materials.

  In a preferred method for manufacturing a chip-shaped solid electrolytic capacitor, the notch and the fine structure of the laminated structure of the electrode substrate are produced by half etching or deep etching.

According to said structure, since the heat resistance of a chip-shaped solid electrolytic capacitor improves, it can suppress the defect generation | occurrence | production of the capacitor | condenser element resulting from thermal stress, such as the increase in a leakage current, and generation | occurrence | production of a mold crack.

It is sectional drawing of the chip-shaped solid electrolytic capacitor concerning Embodiment 1 of this invention. It is the figure which expanded the principal part of FIG. 1A concerning Embodiment 1 of this invention. It is sectional drawing of the chip-shaped solid electrolytic capacitor concerning Embodiment 2 of this invention. It is sectional drawing of the chip-shaped solid electrolytic capacitor concerning Embodiment 3 of this invention. It is sectional drawing of the chip-shaped solid electrolytic capacitor concerning Embodiment 4 of this invention. It is a conceptual diagram which shows the manufacturing method of the cathode terminal concerning Embodiment 4 of this invention. It is a figure which shows desirable conditions as an electrode substrate of the chip-shaped solid electrolytic capacitor concerning this invention. It is sectional drawing of the conventional chip-shaped solid electrolytic capacitor.

<Embodiment 1>
1A and 1B show a chip-shaped solid electrolytic capacitor according to Embodiment 1 of the present invention.

FIG. 1A shows a chip-shaped solid electrolytic capacitor 100 according to this embodiment. The chip-shaped solid electrolytic capacitor 100 has a structure in which a capacitor element 110, a metal strip 120, and an electrode substrate 130 are combined.

FIG. 1B is an enlarged conceptual view of the details 110X of the capacitor element 110 shown in FIG. 1A. Hereinafter, the chip-shaped solid electrolytic capacitor 100 will be described with reference to FIGS. 1A and 1B.

The capacitor element 110 is formed by sequentially forming a porous sintered body 111, a dielectric layer 112, a solid electrolyte layer 113, and a cathode lead layer 114, and has an anode lead 115. Further, the capacitor element 110 is provided with a spill prevention means 116 made of, for example, a fluororesin. The spread prevention means 116 faces one surface of the porous sintered body 111 and covers a region around the root of the anode lead lead 115.

The porous sintered body 111 is made of a valve metal such as tantalum or niobium. The porous sintered body 111 is obtained by pressure-molding the fine powder of the valve action metal together with the anode lead 115 and subsequently performing the sintering treatment. As shown in FIG. The structure has 111X.

The dielectric layer 112 is obtained, for example, by subjecting the porous sintered body 111 to immersion in a phosphoric acid aqueous solution and performing an anodic oxidation treatment. The dielectric layer 112 is formed on the surface of the porous sintered body 111 and is made of a valve metal oxide such as niobium pentoxide or tantalum pentoxide.

The solid electrolyte layer 113 is formed so as to fill the pores 111X of the porous sintered body 111 generated by the fine powder sintering process, and is formed so as to cover at least a part of the surface of the capacitor element 110. Has been. The solid electrolyte layer 113 is sequentially formed after the dielectric layer 112 is formed on the porous sintered body 111.

The solid electrolyte layer 113 includes, for example, a type made of manganese dioxide and a type made of a conductive polymer.

  The process of forming the solid electrolyte layer 113 with manganese dioxide will be outlined. The formation of the solid electrolyte layer 113 is performed, for example, by immersing the porous sintered body 111 in a manganese sulfate solution and thermally decomposing the manganese sulfate solution. In this process, the spread preventing means 116 previously installed suppresses the spread of the manganese sulfate solution to the anode lead out 115. By thermally decomposing the manganese sulfate solution, manganese dioxide that is an oxide semiconductor, that is, a solid electrolyte layer 113 is formed so as to cover the pores 111X of the porous sintered body 111.

  The process of forming the solid electrolyte layer 113 with a conductive polymer will be outlined. An aqueous solution containing a transition metal salt such as ferric sulfate or ferric nitrate as an oxidant is impregnated with the porous sintered body 111 of the capacitor element 110 and dried. By this operation, the oxidizing agent penetrates into the pores 111X of the porous sintered body 111 and adheres thereto. Subsequently, the porous sintered body 111 is impregnated with a solution containing a monomer that forms the conductive polymer and a dopant that imparts conductivity to the conductive polymer. By this operation, the solid electrolyte layer 113 made of a conductive polymer is formed so as to cover the entire porous sintered body 111 and at least a part of the pores 111X at the same time as oxidative polymerization. Further, the solid electrolyte layer 113 is formed through the washing and drying operations.

As shown in FIG. 1B, the cathode lead layer 114 is formed by laminating, for example, a graphite layer 114a and a silver layer 114b, and covers the solid electrolyte layer 113. That is, as shown to FIG. 1A, it forms so that at least one part of the surface of the capacitor | condenser element 110 may be covered.

The cathode lead layer 114 is bonded to one main surface of the cathode terminal 132 via a conductive adhesive 140 made of, for example, silver paste, so that the solid electrolyte layer 113 and the cathode terminal 132 are electrically connected.

  The anode lead 115 is made of, for example, a metal such as tantalum or niobium, and is made of the same kind of metal as the valve action metal fine powder forming the porous sintered body 111. Further, as shown in FIG. 1A, a part thereof has entered the porous sintered body 111.

The spread prevention means 116 covers a region around the base of the anode lead 115 on one main surface of the porous sintered body 111. The one main surface refers to a surface from which the anode lead-out lead 115 protrudes from the porous sintered body 111 molded into a substantially rectangular parallelepiped. The spread prevention means 116 is made of, for example, a hydrophobic fluororesin, and is formed in an annular shape toward the one main surface. The spread prevention means 116 is in contact with the exposed portion of the anode lead 140 and the one main surface of the porous sintered body 111. As described above, the spread prevention means 116 exhibits a function when the capacitor element 110 is manufactured.

One main surface of the metal strip 120 is electrically joined to the anode lead 115 for example by laser welding, and the other main surface is electrically joined to the anode terminal 131 for example by resistance welding.

The electrode substrate 130 is a plate-like member obtained by plating, for example, copper on a base material made of a metal material, and includes an anode terminal 131 and a cathode substrate 132. One main surface of the anode substrate 131 is electrically connected to the anode lead 115 through the metal strip 120. The other main surface of the anode substrate 131 is exposed from the sealing resin 150 and functions as a mounting surface of the chip-shaped solid electrolytic capacitor 100. One main surface of the cathode terminal 132 is bonded to the cathode lead layer 114 via the conductive adhesive 140 as described above. Further, the other main surface of the cathode terminal 132 is exposed from a sealing resin 150 described later, and functions as a mounting surface of the chip-shaped solid electrolytic capacitor 100.

  The sealing resin 150 is made of, for example, an epoxy resin and completely surrounds the capacitor element 110. This prevents the porous sintered body 111, the dielectric layer 112, the solid electrolyte layer 113, the cathode lead layer 114, the anode lead 115, the metal strip 120, and the conductive adhesive 140 from being exposed from the sealing resin 150. ing. The sealing resin 150 covers at least one main surface of the electrode substrate 130 and protects it. The other main surface of the electrode substrate 130 that is not covered with the sealing resin 150 is used for surface mounting the chip-shaped solid electrolytic capacitor 100.

The manufacturing process of the chip-shaped solid electrolytic capacitor 100 will be outlined with reference to FIGS. 1A and 1B. Note that basically the same steps are used for chip-shaped solid electrolytic capacitors 200, 300, and 400 described later.

In the manufacturing process, the anode terminal 131 and the cathode terminal 132 forming the electrode substrate 130 are continuously formed as a lead frame (not shown). When manufacturing the solid capacitor 100, first, the metal strip 120 is fixed to the portion to be the anode terminal 131 of the lead frame by, for example, resistance welding, and the conductive adhesive 140 is applied to the portion to be the cathode terminal 132. Thereafter, the capacitor element 110 in which the porous sintered body 111, the dielectric layer 112, the solid dielectric layer 113, and the cathode lead layer 114 are sequentially formed is installed on the anode lead 115, and then the anode lead 115 is formed. For example, operations such as laser welding to the metal strip 120 and curing for curing the conductive adhesive 140 are performed. Next, a packaging operation is performed using the sealing resin 150. Finally, the electrode substrate 130, that is, the anode terminal 131 and the cathode terminal 132 are separated from the lead frame (not shown), and the remaining anode terminal 131 and exposed portion of the cathode terminal 132 are exposed. On the other hand, Pb-free solder plating for solder mounting (not shown) is performed, and the chip-shaped solid electrolytic capacitor 100 is completed.

In Embodiment 1 of the present invention, the electrode substrate 130 has a laminated structure of different metal materials. The electrode substrate 130 of the chip-shaped solid electrolytic capacitor 100 disclosed in FIG. 1 includes an anode terminal first layer 131a and a cathode terminal first layer 132a made of a first metal material layer, and an upper surface of the first metal material layer. The anode terminal first layer 131b and the cathode terminal first layer 132b made of the second metal material layer. The first metal material layer is the upper surface of the device, that is, the capacitor element 110 side, and the second metal material layer is the lower surface of the device, that is, the mounting surface side of the chip-shaped solid electrolytic capacitor 100.

In the first embodiment, the first metal material layer, that is, the anode terminal first layer 131a and the cathode terminal first layer 132a are made of 42 alloy, for example, nickel or nickel alloy, and the second metal material layer, that is, the anode terminal. The first layer 131b and the cathode terminal first layer 132b may be made of copper. By forming the first metal material layer with 42 alloy which is nickel or nickel alloy, heat resistance and corrosion resistance are improved. By forming the second metal material with copper, it is possible to provide higher conductivity as compared with nickel or a nickel alloy alone. Furthermore, nickel and copper are widely used in alloys and cladding materials and are known to be compatible. Note that tin may be used for the second metal material layer because of solder wettability.

  The thickness of each of the first metal material layer, that is, the anode terminal first layer 131a and the cathode terminal first layer 132a is preferably 10 μm to 100 μm, and the second metal material layer, that is, the anode terminal first layer 131b and the cathode terminal first layer. The thickness of each 132b is desirably 10 μm to 100 μm. The thickness of the metal substrate 130 made of the first metal material layer and the second metal material layer is preferably 0.05 mm to 1.0 mm. In this embodiment, the sum of the thicknesses of the first metal material layer and the second metal material layer, that is, the total thickness of the electrode substrate 130 is set to a standard value of 0.15 mm, and an allowable error is ± 0.006 mm.

Furthermore, the electrode substrate 130 can be appropriately subjected to copper plating or tin plating on the outermost layer. The thickness of the outer plating layer is preferably 1 μm to 20 μm. The copper outer layer plating can improve conductivity and improve solder wettability.

In the present invention, it is more preferable that the dissimilar metals applied to the electrode substrate 130 are separated and formed as a layered structure rather than a mixture, that is, an alloy. By using a so-called alloy as a mixture, a neutral property is generally generated with respect to the properties of each mixed component metal. However, since the present invention has a laminated structure of dissimilar metals, physical properties such as thermal conductivity and thermal expansion coefficient can be arranged in a gradient according to the purpose of the device. Note that the metal material forming each layer is not limited to a pure metal as in the above configuration example, and an alloy can be selected in order to obtain a desired physical property.

A lead frame (not shown) that serves as a base material of the electrode substrate 130 having the above-described configuration may be formed by, for example, a rolling method, or an additional layer may be formed on a base material made of the first metal material or the second metal material. Although it may be formed by using a technique such as plating, vacuum deposition, sputtering, etc., considering that the effect of the present invention is manifested by a laminated structure made of the above-mentioned dissimilar metals, each layer has a considerable thickness. The rolling method is particularly desirable because it is necessary to select a method that can be provided.

<Embodiment 2>
FIG. 2 shows a chip-shaped solid electrolytic capacitor 200 according to Embodiment 2 of the present invention. The second embodiment shows an example in which a three-layer structure of different metal materials is used for the electrode substrate 230 in particular. In addition, as described in the first embodiment, the electrode substrate 230 according to the present embodiment is formed on a lead frame (not shown) serving as a base material in the manufacturing stage. Here, the three-layer structure of different metal materials in the present invention is the first metal material layer, that is, the anode terminal first layer 231a and the cathode terminal first layer 232a, and the first metal material layer disposed on the first metal material layer. Two metal material layers, that is, the anode terminal second layer 231b and the cathode terminal second layer 232b, and a third metal material layer, that is, the anode terminal third layer 231c and the cathode terminal disposed on the second metal material layer. It is composed of a third layer 232c. That is, in the three-layer structure of dissimilar metal materials in the present invention, the first metal material layer is disposed on one main surface of the second metal material layer, and the third metal material layer is the second metal material layer. It is installed on the other main surface.

In the chip-shaped solid electrolytic capacitor 200 of the present invention, the anode terminal first layer 231a and the cathode terminal first layer 232a are formed of the first metal material layer, and the anode terminal first layer 231a is electrically connected to the metal strip 120 and the electric wire. The cathode terminal first layer 232a is electrically connected to the capacitor element 110 through the conductive adhesive 140.

In this configuration example, for example, the first metal material layer, that is, the anode terminal first layer 231a and the cathode terminal first layer 232a is 42 alloy, and the second metal material layer, that is, the anode terminal second layer 231b and the cathode terminal second layer. Nickel may be used as the layer 232b, and copper may be used as the third metal material layer, that is, the anode terminal third layer 231c and the cathode terminal third layer 232c.

The thermal expansion coefficients of the metals and alloys of this structural example are as follows: 42 alloy is 45 [10 ⁻⁷ / ° C.] to 65 [10 ⁻⁷ / ° C.] at 30 ° C. to 330 ° C., and nickel is 133 [10 ^{− at} 20 ° C. ⁷ / ° C.] and copper is 168 [10 ⁻⁷ / ° C.] at 20 ° C. The epoxy resin constituting the sealing resin 150 is assumed to have a value of 200 [10 ⁻⁷ / ° C.] to 500 [10 ⁻⁷ / ° C.].

  According to the electrode substrate 230 disclosed in the above configuration example, the coefficient of thermal expansion is sequentially increased from the upper layer of the chip-shaped solid electrolytic capacitor 200, that is, from the capacitor element 110 side to the lower layer, that is, from the mounting surface, that is, from the first layer to the third layer. In order to increase, that is, (thermal expansion coefficient of the first metal material layer) <(thermal expansion coefficient of the second metal material layer) <(thermal expansion coefficient of the third metal material layer) Because it is set and thermal expansion can be distributed between each metal layer, it has the effect of dispersing thermal stress from, for example, the thermal load during reflow, which reduces device performance such as increased leakage current and increased ESR. Can be prevented.

Further, the thermal conductivity of each layer of the electrode substrate 230 is 14.6 W / (m · K) at 42 alloy, 113 W / (m · K) for nickel, and 397 W / (m · K) for copper. From this surface, the heat conductivity is gradually lowered toward the upper layer of the chip-shaped solid electrolytic capacitor 200, that is, the side closer to the surface in contact with the capacitor element 110. That is, the thermal conductivity of each layer is (thermal conductivity of the first metal material layer) <(thermal conductivity of the second metal material layer) <(thermal conductivity of the third metal material layer). Yes. Therefore, the structure is such that reflow heat from the lower surface direction of the element, that is, the mounting surface, for example, when the element is mounted, is not easily transmitted to the capacitor element 110. At the same time, the laminated structure is designed so that the thermal conductivity is sequentially increased from the outside of the device, specifically toward the mounting surface, so that the heat generated in the capacitor element 110 is the first metal material layer, that is, When transmitted to the cathode terminal first layer 232a, an effect of efficiently radiating heat to the outside of the element, that is, the element mounting surface side can be expected.

  For example, the first metal material layer, ie, the anode terminal first layer 231a and the cathode terminal first layer 232a, has a thickness of 10 μm to 100 μm, and the second metal material layer, ie, the anode terminal first The thickness of the second layer 231b and the cathode terminal second layer 232b is 10 μm to 100 μm, the thickness of the third metal material layer, that is, the anode terminal third layer 231c and the cathode terminal third layer 232c is 10 μm to 100 μm, and the first metal The thickness of the metal substrate 230, which is a substrate composed of the material layer, the second metal material layer, and the third metal material layer, is preferably 0.05 mm to 1.0 mm. In the present embodiment, the sum of the thicknesses of the first metal material layer, the second metal material layer, and the third metal material layer, that is, the total thickness of the electrode substrate 230 is 0.15 mm as a standard value, and the tolerance is ± It was set to 0.006 mm.

For example, a rolling method may be used as a method for producing the metal layer having the structure of the present embodiment. For example, a nickel layer as a second metal material layer is plated on a base material substrate of 42 alloy, vacuum deposition, It is formed by suitably using a technique such as sputtering, and the copper layer as the third metal material layer is also formed by the same method as that for the second metal material layer, or by a method such that it is sequentially formed by other methods. it can. Note that the manufacturing method is not limited to these, and any method can be used as long as a three-layer structure is provided.

Furthermore, the lead frame (not shown) which becomes the base material of the electrode substrate 230 can be appropriately subjected to copper plating or tin plating on the outermost layer. The thickness of the outermost plating layer is preferably 1 μm to 20 μm.

<Embodiment 3>
FIG. 3 shows a chip-shaped solid electrolytic capacitor 300 according to Embodiment 3 of the present invention. The cathode terminal 332, which is a feature of the chip-shaped solid electrolytic capacitor 300, is obtained by forming a notch X in a part of the cathode terminal 332. Similar to the first and second embodiments, this structure is manufactured by processing a lead frame (not shown) to form the electrode substrate 330. The “notch” in the present invention indicates a state in which the thickness of the electrode substrate 330 is different in a stepped manner or an inclined manner.

  The notch portion X is formed, for example, on the side used for surface mounting of the cathode terminal 332, that is, on the side of the cathode terminal third layer 332c, whereby the surface used for surface mounting is notched portion X as shown in FIG. And the remaining part X2. Due to the cutout portion X, the thickness of that portion of the cathode terminal 332 is thinner than the thickness of the portion of the remaining portion X2. Note that the thickness of the portion of the cathode terminal 332 in which the notch X is formed is preferably 20% to 80% of the thickness of the electrode substrate 330 in order to maintain the structural strength.

The notch portion X is covered and protected by the sealing resin 150, and a part of the remaining portion X2 other than the notch portion X is exposed from the sealing resin 150 and used for surface mounting of the chip-shaped solid electrolytic capacitor 300. .

One main surface of the remaining portion X2 functions as a mounting surface used for surface mounting of the capacitor element 300, and this corresponds to one main surface of the cathode terminal third layer 332c. The other main surface not used for mounting is joined to the cathode terminal second layer 332b. The area of the surface used for surface mounting of the cathode terminal third layer 332c is desirably the same area as the surface used for surface mounting of the anode terminal third layer 331c. This is desirable as an electrode specification at the time of surface mounting, and also effective in preventing the so-called Manhattan effect that occurs at the time of mounting.

By forming the notch portion X, the sealing resin 150 can be cured by entering the notch portion X at the time of sealing with resin, that is, at the time of molding, thereby improving the adhesion between the sealing resin 150 and the cathode terminal 332. To do. For this purpose, the cutout portion X is preferably completely embedded in the sealing resin 150 as shown in FIG. Furthermore, by providing the notch portion X, the area that is electrically connected to the capacitor element 110 via the conductive adhesive 140 can be increased without increasing the area of the mounting surface, that is, the cathode terminal 332 exposed from the sealing resin 150. It becomes possible. Accordingly, it is possible to meet the above-described specification requirements on the surface mounting while maintaining good conductivity between the cathode terminal 332 and the capacitor element 110.

In the third embodiment, the cross section of the cutout portion X is preferably provided in the vicinity of the boundary between the second metal material layer, that is, the cathode terminal second layer 332b, and the third metal material layer, that is, the cathode terminal third layer 332c. As described in the second embodiment, the metal laminated structure of the electrode substrate 330 used in the present embodiment is formed so as to use a metal material having a larger thermal expansion coefficient as it approaches the mounting surface side from the capacitor element side. Has been. That is, in the present embodiment, the lower surface of the device, that is, the cathode terminal second layer 332b and the cathode terminal third layer 332c is configured so that the thermal expansion coefficient gradually increases. This means that the difference in thermal expansion coefficient with the metal material forming the terminal 332 is small. With such a configuration, since the notch portion X is provided, it is possible to obtain an effect of particularly dispersing thermal stress on the lower surface of the structurally weak device. Therefore, the chip-shaped solid electrolytic capacitor 300 is resistant to thermal stress. Will improve.

The electrode substrate 330 having the notch X can be obtained by, for example, half-etching the substrate having the three-layer structure shown in the second embodiment, that is, the electrode substrate 230. Half-etching can be stopped in the middle of each metal layer, but it is easier to stop at the boundary of the metal layer because the etching rate differs between metals. In order to remove only the cathode terminal third layer 332c made of, for example, copper in the structure as shown in FIG. 3, that is, the formation of the notch portion X, for example, a selective etching technique for a laminated substrate of nickel and copper is often used. An etchant containing hydrogen peroxide solution, sulfuric acid, and water may be used. By using such a method, only the layer made of copper is selectively dissolved from the electrode substrate 230 having the three-layer structure shown in the second embodiment, and an electrode substrate 330 having a notch X is prepared. Can do.

  The metal laminated structure used in Embodiment 3 is, for example, a first metal material layer, that is, an anode terminal first layer 331a and a cathode terminal first layer 332a of 10 μm to 100 μm, and a second metal material layer, that is, an anode terminal second layer 331b. And the cathode terminal second layer 332b is 10 μm to 100 μm, the third metal material layer, that is, the anode terminal third layer 431c and the cathode terminal third layer 432c is 10 μm to 100 μm in thickness, and the first metal material layer, The metal substrate 330, which is a substrate composed of the second metal material layer and the third metal material layer, is preferably 0.05 mm to 1.0 mm. In the present embodiment, the sum of the thicknesses of the first metal material layer, the second metal material layer, and the third metal material layer, that is, the total thickness of the electrode substrate 330 is 0.15 mm as a standard value, and an allowable error is ± It was set to 0.006 mm.

Furthermore, a lead frame (not shown) which becomes a base material of the electrode substrate 330 can be appropriately subjected to copper plating or tin plating (not shown) on the outermost layer. The thickness of the outermost plating layer is preferably 1 μm to 20 μm, and this may be after the notch portion X is provided.

<Embodiment 4>
FIG. 4 shows a chip-shaped solid electrolytic capacitor 400 according to Embodiment 4 of the present invention. In the structure shown in FIG. 4, the anode terminal 431 is the same as that of the third embodiment, but the upper surface of the cathode terminal 432, that is, the cathode terminal first layer 432 a that is in contact with the capacitor element 110 via the conductive adhesive 140 is provided. The feature is that it has an uneven structure. The uneven structure may be formed not only in the cathode terminal first layer 432a but also in the cathode terminal second layer 432b and the cathode terminal third layer 432c. For example, the concavo-convex structure portion may be formed on the surface where the cathode terminal second layer 432b and the cathode terminal third layer 432c are in contact with each other so that these concavo-convex structures are engaged with each other. Such a structure can further improve the mechanical strength of the cathode terminal 432. Further, such an uneven structure may be formed not only on the cathode terminal 432 side but also on the anode terminal 431 side. By making both the anode terminal 431 and the cathode terminal 432 have a concavo-convex structure, the mechanical strength of the chip-shaped solid electrolytic capacitor 400 can be further improved.

In the concavo-convex structure disclosed in the present invention, 42 alloy was used as the metal material constituting the uppermost surface, that is, the cathode electrode terminal 432a. The thermal expansion coefficient of 42 alloy is 45 [10 ⁻⁷ / ° C.] to 65 [10 ⁻⁷ / ° C.] at 30 ° C. to 330 ° C., which is small compared to other metal materials. Furthermore, in the present invention, the conductive adhesive 140 and the cathode electrode terminal 432a are joined to the layer made of 42 alloy via the concavo-convex structure, so that the contact area between the cathode electrode terminal 432a and the conductive adhesive 140 is small. It has increased significantly. As a result, the adhesiveness between the conductive adhesive 140 and the cathode electrode terminal 432a can be improved, and the thermal stress resistance when a thermal stress is applied can be improved. Furthermore, since the uneven structure increases the surface area of the cathode electrode terminal 432a, the electrical resistance between the cathode electrode terminal 432a and the capacitor element 110 via the conductive adhesive 140 is reduced, thereby reducing ESR. Reduction effect can be expected.

The cathode terminal 432 can be formed with a notch X similar to that shown in the third embodiment. By forming the notch X, the adhesion between the sealing resin 150 and the cathode terminal 432 is improved. Furthermore, it is possible to increase the area that is electrically connected to the capacitor element 110 via the conductive adhesive 140 without extremely increasing the area of the mounting surface, that is, the cathode terminal 432 exposed from the sealing resin 150. The characteristics regarding these notches X are the same as those in the third embodiment. In order to manufacture the cathode terminal 432 having both the concavo-convex structure and the notch portion X, that is, the structure as shown in FIG. 4, the base material of the electrode substrate having the notch portion X shown in the third embodiment is used. A lead frame (not shown) may be sequentially processed by the above method to newly add a concavo-convex structure.

  The structure of the present embodiment can be formed by sequentially processing the two-layer structure or the three-layer laminated substrate of the metal material shown in the first and second embodiments. For example, the two-layer structure can be formed by adding a concavo-convex structure by performing sputtering, vacuum deposition, etc. Further, for example, half etching using photolithography for the three-layer stacked structure It can be produced by performing deep etching.

  FIG. 5 is a conceptual diagram for explaining a method of manufacturing the cathode terminal 432 of the electrode substrate 430 shown in FIG. For example, the lead frame L can be manufactured at low cost by using the lead frame used in Embodiment 3 to sequentially form the concavo-convex structure using a technique such as half etching or deep etching. In the structure shown in FIG. 5, for example, the lead frame L is manufactured using the three-layer laminated substrate of the metal material having the notch portion X shown in the third embodiment. This may be applied to the two-layer laminated substrate.

First, for example, a photosensitive polyimide resin is applied as a photosensitive resist to the cathode terminal 432 portion of the electrode substrate 430 and the upper surface thereof, that is, the cathode terminal first layer 432a by, for example, a dipping method. Next, as shown in FIG. 5, a mask M for transferring a pattern is prepared. The mask M is brought into close contact with the surface coated with the photosensitive resist, and an exposure operation is performed with ultraviolet rays. Thereafter, by treating with a predetermined chemical solution, the uneven structure as shown in FIG. 5 can be formed in the cathode terminal first layer 432a.

  The metal laminated structure used in Embodiment 4 is, for example, the first metal material layer, that is, the anode terminal first layer 431a and the cathode terminal first layer 432a, 10 μm to 100 μm, and the second metal material layer, that is, the anode terminal second layer 431b. And the cathode terminal second layer 432b is 10 μm to 100 μm, the third metal material layer, that is, the anode terminal third layer 431c and the cathode terminal third layer 432c is 10 μm to 100 μm in thickness, and the first metal material layer, The metal substrate 430, which is a substrate composed of the second metal material layer and the third metal material layer, is preferably 0.05 mm to 1.0 mm. In the present embodiment, the sum of the thicknesses of the first metal material layer, the second metal material layer, and the third metal material layer, that is, the total thickness of the electrode substrate 430 is set to a standard value of 0.15 mm, and the tolerance is ± It was set to 0.006 mm.

When producing the concavo-convex structure, it is preferable that the etching depth does not penetrate the cathode first layer 432a. That is, the height of the convex portion Y of the concavo-convex structure is preferably 10% to 90% of the thickness of the cathode first layer 432a.

  The concavo-convex structure can be a so-called pear texture that is rough like the surface of a pear. For the production of satin, for example, air blasting method, shot blasting method, sand blasting method, wet blasting method can be suitably used, but from the viewpoint of uniformity of roughened surface, controllability, cleanability, etc. Wet blasting is particularly desirable. Thereby, like the above-mentioned concavo-convex structure, effects, such as improvement in adhesion and reduction in electric resistance, can be acquired.

The lead frame L can be subjected to copper plating or tin plating (not shown) on the outermost layer. The thickness of the outermost plating layer is preferably 1 μm to 20 μm, and this may be after the notch portion X and the above-described uneven structure are provided.

  FIG. 6 is a table showing preferred combinations of the characteristics of the electrode substrates 230, 330, and 430 described in Embodiments 2 to 4 of the present invention with respect to the three-layer structure of metal used. The thicknesses of the first layer, the second layer, and the third layer constituting the laminated structure according to the present invention are each suitably adjusted as 10 μm to 100 μm, and the thermal expansion coefficient and thermal conductivity of the metal constituting each layer are as follows: It is desirable to form the first layer, the second layer, and the third layer so that their absolute values increase in this order. In FIG. 6, the first layer corresponds to, for example, the cathode terminal first layer 232a in FIG. 2 used in the description of Embodiment 2, and the second layer and the third layer are the cathode terminal second layer 232b and the cathode, respectively. This corresponds to the terminal third layer 232c. As mentioned above, this is mainly aimed at the effect of efficiently dispersing thermal stress, and within the range not impairing the effects of the present invention, in addition to the metal combinations described in Embodiments 1 to 4, A metal group satisfying the relationship in this table can be used.

  Since the chip-shaped solid electrolytic capacitor of the present invention uses a laminated structure of metal material made of metal or alloy for the electrode substrate, it has high heat resistance and can suppress the occurrence rate of defects. It ’s big.

110 Capacitor element 110X Details 111 Porous sintered body 111X Pore 112 Dielectric layer 113 Solid electrolyte layer 114 Cathode extraction layer 114a Graphite layer 114b Silver layer 115 Anode lead-out lead 116 Swelling prevention means 120 Metal strips 130, 230, 330 430 Anode terminal 131a, 231a, 331a, 431a Anode terminal first layer 131b, 231b, 331b, 432b Anode terminal second layer 231c, 331c, 431c Anode terminal third layer 132, 232 332, 432 Cathode terminal 132a, 232a, 332a, 432a Cathode terminal first layer 132b, 232b, 332b, 432b Cathode terminal second layer 232c, 332c, 432c Cathode terminal third layer 140 Conductive adhesive 150 Sealing resin L Reed Over arm M mask X notch X2 remaining portion Y projecting portion

Claims (11)

A porous sintered body made of a valve metal,
A dielectric layer covering at least a part of the porous sintered body;
A solid electrolyte layer covering at least a part of the dielectric layer;
A conductive adhesive covering at least a part of the solid electrolyte layer;
An electrode substrate covered at least in part by the conductive adhesive;
A chip-shaped solid electrolytic capacitor comprising:
A chip-shaped solid electrolytic capacitor, wherein the electrode substrate is a laminated structure of a plurality of metal materials.   The porous sintered body, the dielectric layer, the solid electrolyte layer, and the conductive adhesive are completely embedded in a sealing resin, and a part of the electrode substrate is exposed from the sealing resin. The chip-shaped solid electrolytic capacitor according to claim 1.   3. The laminated structure of the electrode substrate according to claim 1, wherein each metal material constituting the electrode substrate is formed so that a thermal expansion coefficient of the metal increases toward a lower portion of the element. Chip-shaped solid electrolytic capacitor.   4. The laminated structure of the electrode substrate according to claim 1, wherein each metal material constituting the electrode substrate is formed such that the lower the element, the higher the thermal conductivity of the metal. The chip-shaped solid electrolytic capacitor according to claim 1.   5. The chip-shaped solid electrolytic capacitor according to claim 1, wherein the laminated structure of the electrode substrate is made of two layers of nickel or a nickel alloy and copper or tin.   5. The chip-shaped solid electrolytic capacitor according to claim 1, wherein the laminated structure of the electrode substrate is composed of three layers of a nickel alloy, nickel, and copper or tin. One main surface that is not covered with the conductive adhesive of the electrode substrate has a notch,
The chip-shaped solid electrolytic capacitor according to any one of claims 1 to 6, wherein at least a part of the notch is covered with the sealing resin.   The chip-shaped solid electrolytic capacitor according to any one of claims 1 to 7, wherein a surface of at least a part of the electrode substrate covered with a conductive adhesive has a concavo-convex structure.   9. The chip-shaped solid electrolytic capacitor according to claim 8, wherein the concavo-convex structure is formed in at least one metal material layer of the laminated structure of the metal materials.   9. The chip-shaped solid electrolytic capacitor according to claim 8, wherein the uneven structure is a satin finish, and the satin finish is formed in one metal material layer of the laminated structure of the metal materials.   11. The chip-shaped solid electrolytic capacitor according to claim 7, wherein the notch and the fine structure of the laminated structure of the electrode substrate are produced by half etching or deep etching. Production method.

Images