JPH0620882A - Chip-type solid-state electrolytic capacitor - Google Patents

Abstract

PURPOSE:To enable a solid-state electrolytic capacitor to be lessened in size and enhanced in capacity and prevent a capacitor element and a cathode conductor layer from being exposed when sheathing resin is provided. CONSTITUTION:An anode metal layer 20 connected to an anode lead-out wire 12 is provided to the wire lead-out side of a sheathing resin 18, and an insulating resin layer 18a is provided around a cathode conductor layer 16 which is formed thicker than a cathode layer 15 on the side of a capacitor element 11a opposed to the wire lead-out side of the element 11a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip solid electrolytic capacitor.

[0002]

2. Description of the Related Art In recent years, the number of chip parts has been rapidly increasing with the progress of light and thin electronic devices and surface mounting technology. In the chip solid electrolytic capacitor, further miniaturization of the chip component itself is required as the size and capacity of the chip solid electrolytic capacitor are increasing.

A conventional chip-shaped solid electrolytic capacitor will be described below. FIG. 4 is a cross-sectional view of a conventional chip-shaped tantalum solid electrolytic capacitor. In FIG. 4, 1 is a capacitor element, and this capacitor element 1 is formed by sintering tantalum metal powder which is a valve metal. An anode lead wire 2 made of a tantalum wire is led out from the constructed porous anode body, and a dielectric oxide film is formed on a part of the anode lead wire 2 and the entire surface of the porous anode body by anodization. Furthermore, an electrolyte layer such as manganese dioxide on the surface,
It is configured by sequentially stacking the cathode layers 4. The cathode layer 4 is formed by sequentially stacking a carbon layer and a silver coating layer by the dipping method. Reference numeral 3 denotes a Teflon plate attached to the anode lead wire 2, and this Teflon plate 3 is an insulating plate for preventing manganese dioxide from creeping up and adhering to the anode lead wire 2 during the formation of the electrolyte layer. Reference numeral 5 denotes an anode terminal, which is connected to the anode lead wire 2 by welding, and is bent after molding the exterior resin. 6
Is a cathode terminal, and this cathode terminal 6 is the capacitor element 1
Is connected to the cathode layer 4 by a conductive adhesive 7 and is bent after the exterior resin is formed. Reference numeral 8 is an exterior resin that covers the entire capacitor element 1 by molding.

[0004]

However, in the conventional chip-shaped solid electrolytic capacitor configured as described above, an assembly process such as welding of the anode lead wire 2 and the anode terminal 5 led out from the capacitor element 1 and a resin In the molding process, mechanical and thermal stress is applied to deteriorate the characteristics such as increase of leakage current and increase the defective rate, and further, the space size of the welded portion and the connection between the capacitor element 1 and the cathode terminal 6 Since the size of the folding space including the lead-out portion is large, the size and shape of the capacitor element 1 are structurally limited. Also,
Since the effective use amount of the material of the anode terminal 5 and the cathode terminal 6 obtained by punching the plate material is extremely low, there is a problem in terms of volumetric efficiency and economical efficiency of the capacitor. Further, there is a problem that the appearance of the anode terminal 5 and the cathode terminal 6 is bent during the bending process, and stress is applied to the capacitor element 1 to deteriorate the characteristics.

The present invention solves the above-mentioned problems of the prior art, and it is possible to reduce the size and increase the capacity and prevent the exposure of the capacitor element and the cathode conductor layer when forming the exterior resin. An object of the present invention is to provide a solid electrolytic capacitor.

[0006]

To achieve the above object, a chip solid electrolytic capacitor of the present invention is an anode body made of a valve metal in which an anode lead wire is embedded so that one end of the anode lead wire is exposed. A capacitor element formed by providing a dielectric oxide film, an electrolyte layer, and a cathode layer on the surface of the capacitor element, and a cathode conductive layer formed on the surface of the capacitor element facing the lead-out surface of the anode lead-out line of the capacitor element at least thicker than the cathode layer. Body layer, an insulating resin layer provided around the cathode conductor layer, and an insulating resin layer around the capacitor element and the periphery so that at least a part of the anode lead wire and the cathode conductor layer is exposed. The exterior resin covering the cathode conductor layer provided with, the anode metal layer provided on the exposed side of the anode lead wire of the exterior resin and connected to the anode lead wire, and the cathode conductivity of the exterior resin. It provided exposed side of the layer, and is obtained by a cathode metal layer to be connected to the cathode conductor layer.

[0007]

According to the above construction, since the anode metal layer connected to the anode lead wire is provided on the exposed side of the anode lead wire of the exterior resin, the conventional external terminal can be taken out to the outside. Can be omitted, and the space for bending the external terminals can be saved, and the volumetric efficiency of the capacitor can be increased, so that the capacitor can be downsized and the capacity can be increased. Further, since an insulating resin layer is provided around the cathode conductor layer formed at least thicker than the cathode layer on the surface of the cathode layer of the capacitor element facing the lead-out surface of the anode lead-out wire, this insulating resin layer When present, the presence of the capacitor element and the cathode conductor layer can be prevented from being exposed when the exterior resin is formed.
It is possible to obtain a chip-shaped solid electrolytic capacitor excellent in yield and productivity.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross-sectional view of a chip-shaped tantalum solid electrolytic capacitor in one embodiment of the present invention, and FIG. 2 shows a state in which a cathode conductor layer and an insulating resin layer are formed on a capacitor element. In FIG. 1 and FIG. 2, 11 is a porous anode body formed by molding and sintering tantalum metal powder which is a valve metal, and a dielectric oxide film is formed on the surface of this anode body 11 by anodic oxidation. An electrolyte layer of manganese dioxide or the like is formed on the surface of this dielectric oxide film. The anode lead wire 12 is made of tantalum wire and is led out from the anode body 11. Then, a series of processing steps on the surface of the anode body 11 is performed in a state where the anode lead wire 12 is connected to the metal ribbon 13. Reference numeral 14 is a Teflon plate attached to the anode lead wire 12, and this Teflon plate 14 is an insulating plate that prevents manganese nitrate from crawling up and adhering to manganese dioxide to the anode lead wire 12 when an electrolyte is formed on the capacitor element 11. Is. Further, a cathode layer 15 composed of a carbon layer and a silver coating layer is sequentially laminated on the electrolyte layer of the anode body 11 by a dipping method to form a capacitor element 11a.

Reference numeral 16 is a cathode conductor layer, and this cathode conductor layer 16 is a cathode layer 1 provided around the capacitor element 11a.
5, facing surface 1 located on the side opposite to anode lead wire 12
7 and a part of the cathode layer 15 on the adjacent surface adjacent to the facing surface 17. In this case, the cathode conductor layer 16 is formed by immersing the capacitor element 11a in a viscous liquid of a conductive resin, or
Alternatively, using a dispenser, the capacitor element 11a
It is formed by applying an appropriate amount to, then drying and curing. 18a is an insulating resin layer, and this insulating resin layer 1
8a is formed by coating the periphery of the cathode conductor layer 16 with resin powder, or by immersing and adhering the cathode conductor layer 16 in a photocurable resin and then curing the resin. is doing.

18 is an exterior resin, and this exterior resin 18 is
The capacitor element 11a is set in a mold so that the anode lead wire 12 is drawn out to one side, and the entire capacitor element 11a including the cathode conductor layer 16 provided with the insulating resin layer 18a on the periphery is resin-coated. , A resin exterior is formed by a transfer molding method using an epoxy resin. The insulating resin layer 18a and the exterior resin 18
Preferably have the same color.

3 (a) (b) (c) (d) (e)
(F) and (g) show the manufacturing process of the chip-shaped tantalum solid electrolytic capacitor in one embodiment of the present invention. In FIG. 3 (a), 12a is the anode lead-out surface of the exterior resin 18, and this anode is The lead-out surface 12a is located in the vicinity of the anode lead-out wire 12 in the molded body of the exterior resin 18 and has a concave shape. Due to this concave shape, the anode lead-out line 12 protrudes from the outer dimensions of the molded body of the exterior resin 18. As a result, the exposed area can be increased. On the other hand, the facing surface 1 located on the opposite side of the anode lead wire 12
Since the cathode conductor layer 16 formed in 7 is longer than the external dimensions of the product, the molded body of the exterior resin 18 is long.

FIG. 3B shows a state in which the molded body of the exterior resin 18 in FIG. 3A is cut or ground to the external dimensions of the product. In FIG. 3B, reference numeral 16a denotes a cathode lead-out surface, and this cathode lead-out surface 16a is exposed as shown in FIG. 1 by cutting the exterior resin 18, the insulating resin layer 18a and the cathode conductor layer 16. And this figure 1
The surface of the anode lead wire 12, the cathode lead-out surface 16a, and the surface of the molded body of the exterior resin 18 exposed from the molded body of the exterior resin 18 in FIG. The dielectric oxide film on the anode lead wire 12 exposed from the body is removed.

FIG. 3 (c) shows a state in which the anode lead-out wire 12 is separated from the metal ribbon 13 and bent into an L-shape so that the anode lead-out wire 12 can be accommodated in the concave shape of the anode lead-out surface 12a. is there.

FIG. 3 (d) shows a state in which the anode lead-out wire 12 is separated from the metal ribbon 13 so that the anode lead-out wire 12 fits within the concave shape of the anode lead-out surface 12a.
Instead of bending it into an L-shape as shown in FIG. 3C, the shape shown in FIG.

FIG. 3 (e) shows a state in which the metal layer 19 is formed. As shown in FIG. 1, the metal layer 19 is a molded body of the anode lead wire 12, the anode lead surface 12a and the exterior resin 18. Anode metal layer 20 formed on the surface and cathode lead-out surface 1
6a and the cathode metal layer 21 formed on the surface of the molded body of the exterior resin 18, and the anode metal layer 20 and the cathode metal layer 21 firstly cover all of the anode lead wires 12 exposed from the exterior resin 18. The surface, the anode lead-out surface 12a, the cathode lead-out surface 16a, and the entire surface of the molded body of the exterior resin 18 are pre-treated by degreasing and applying a palladium catalyst, and then formed by electroless plating. The metal of the anode metal layer 20 and the cathode metal layer 21 formed by this electroless plating may be nickel or copper.

By using this electroless plating, it is possible to easily form a thin film uniformly and thinly on a complicated shape such as a concave shape regardless of a metal surface or a non-metal surface. In addition, since the variation in the outer dimensions can be reduced and the mechanical and thermal stresses are not applied, the increase in leakage current is small and the yield is very good. Further, by setting the thickness of the anode metal layer 20 and the cathode metal layer 21 formed by this electroless plating within the range of 0.5 to 5 μm, the adhesion to the base is excellent, and the amount of material used and the cost are reduced. Can be reduced as compared with the conventional manufacturing method. Further, the anode metal layer 20 formed by electroless plating
It is also possible to further form a metal layer by electroplating on the cathode metal layer 21 to improve the mechanical strength of the anode metal layer 20 and the cathode metal layer 21.

FIG. 3 (f) shows a state in which the anode metal layer 20 and the cathode metal layer 21 are formed. In this case, the metal layer formed by electroless plating is used as the anode metal layer 20 and the cathode metal layer 21. Remove so that it remains.

FIG. 3 (g) shows a state in which the anode metal layer 20 and the cathode metal layer 21 are covered with a solder metal layer.
Reference numeral 22 is a solder metal layer on the anode side, and 23 is a solder metal layer on the cathode side. These solder metal layers 22 and 23 are formed by solder coating with molten solder or electrolytic solder plating.

[0019]

As described above, according to the chip solid electrolytic capacitor of the present invention, the anode metal layer connected to the anode lead wire is provided on the exposed side of the anode lead wire of the exterior resin. A conventional space for taking out the external terminal to the outside and a space for bending the external terminal can be omitted, and thereby the volumetric efficiency of the capacitor can be increased, so that the capacitor can be downsized and the capacity can be increased. Further, since an insulating resin layer is provided around the cathode conductor layer formed at least thicker than the cathode layer on the surface of the cathode layer of the capacitor element facing the lead-out surface of the anode lead-out wire, this insulating resin layer The presence of the capacitor element and the cathode conductor layer prevents the exposure of the capacitor element and the cathode conductor layer when the exterior resin is formed, whereby a chip solid electrolytic capacitor excellent in quality, yield, and productivity can be obtained. .

[Brief description of drawings]

FIG. 1 is a sectional view of a chip-shaped tantalum solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state where a cathode conductor layer and an insulating resin layer are formed on a capacitor element in the solid electrolytic capacitor.

3A to 3G are perspective views showing manufacturing steps of the solid electrolytic capacitor.

FIG. 4 is a sectional view of a conventional chip-shaped tantalum solid electrolytic capacitor.

[Explanation of symbols]

 11 Anode body 11a Capacitor element 12 Anode lead wire 15 Cathode layer 16 Cathode conductor layer 18 Exterior resin 18a Insulating resin layer 20 Anode metal layer 21 Cathode metal layer

Claims (3)

[Claims] 1. A capacitor element comprising a dielectric oxide film, an electrolyte layer and a cathode layer provided on an anode body made of a valve metal in which an anode lead wire is embedded so that one end of the anode lead wire is exposed. A cathode conductor layer formed at least thicker than the cathode layer on a surface of the capacitor element facing the lead-out surface of the anode lead wire in the cathode layer, and an insulating resin layer provided around the cathode conductor layer, Exterior resin covering the capacitor element and the cathode conductor layer provided with an insulating resin layer on the periphery so that at least a part of the anode lead wire and the cathode conductor layer are exposed, and the anode lead wire of the exterior resin. An anode metal layer provided on the exposed side and connected to the anode lead wire, and a cathode metal layer provided on the exposed side of the cathode conductor layer of the exterior resin and connected to the cathode conductor layer. Chip with Solid electrolytic capacitor. 2. The chip solid electrolytic capacitor according to claim 1, wherein the insulating resin layer provided around the cathode conductor layer is provided by powder coating. 3. The chip solid electrolytic capacitor according to claim 1, wherein the insulating resin layer provided around the cathode conductor layer is a photocurable resin.