JPH04286309A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To weld the metal terminal of an aluminum rod, which is exposed by cutting, to a substrate using metal-plate piece of three-layer structure copper substrate having a treated nickel-plated surface on one side of the copper substrate, such as phosphor bronze and the like used as terminal material, and also having a treated solder-plated surface on a part. CONSTITUTION:Outer connection terminals 28 and 28, consisting of copper material, are welded respectively to the metal terminals 24 and 24, which become both electrodes of a capacitor element, by laser welding 36 and 36. The outer connection terminals 28 and 28 have a three-layer structure formed by nickel-plating 34 on one side of a copper substrate 30 consisting of phosphor bronze and the like. The connection terminals 28 and 28 of three-layer structure are attached by laser welding 36 to the metal terminals 24 and 24, which are exposed by cutting, by projecting a laser beam on the nickel plated surface 32. Consequently, as an aluminum rod electrode terminal, which is exposed by cutting, and an alloy can be formed easily when a welding work is conducted, high welding strength can be maintained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor suitable for surface mounting on printed circuit boards used in small electronic devices.

0002

2. Description of the Related Art As electronic equipment becomes smaller and more portable, high-density packaging technology for electronic components constituting the equipment has become essential. For high-density packaging,
There is a strong demand for miniaturization of resistors, multilayer ceramic capacitors, etc., which are used in large numbers among electronic components.
parts) and ultra-small products of 1.0 mm x 0.5 mm (1005
Even parts) have been developed and are now in use. Under these circumstances where miniaturization is required, electrolytic capacitors with relatively large capacity characteristics are also being made smaller and surface-mounted instead of conventional ones with cylindrical lead terminals. Suitable leadless prismatic solid electrolytic capacitors have been developed.

[0003] Such a rectangular solid electrolytic capacitor is manufactured by attaching aluminum rod metal terminals to each metal foil for the positive and negative electrodes by stitching or ultrasonic welding, and then attaching each metal foil through a separator. winding,
A capacitor element is formed by impregnating it with an electrolytic solution, firing it, and performing a chemical conversion treatment. This capacitor element is then stored in a resin case together with a potting resin and sealed. After the potting resin has hardened, the metal terminal of the resin case is further sealed. It is manufactured by cutting the side surface at desired locations to expose the metal terminals and the potting resin, and then connecting aluminum external connection terminals to the exposed metal terminals by welding or the like. The welding part between the metal terminal of the aluminum rod exposed by the cutting and the external connection terminal requires sufficient welding strength with respect to the aluminum of the external connection terminal and the exposed metal terminal. Aluminum is used as the terminal material.

0004

[Problems to be Solved by the Invention] However, according to the solid electrolytic capacitor manufactured by the manufacturing method of welding the metal terminal of the aluminum rod exposed by cutting and the external connection terminal as described above, the external connection terminal Since aluminum is used as the terminal material, the welded part is a weld of the same type of metal, and although it has sufficiently high welding strength, there is a problem that it lacks the strength as a terminal material. In addition, since aluminum is used as the terminal material, it is difficult to perform solder plating, making it difficult to solder to a printed circuit board or the like.

[0005] Therefore, an object of the present invention is to use a terminal material as an external connection terminal that can be welded with sufficiently high welding strength to the metal terminal of the aluminum rod exposed by cutting, and is also easy to solder plate. To provide solid electrolytic capacitors.

[0006]

[Means for Solving the Problems] A solid electrolytic capacitor according to the present invention is provided by attaching a metal terminal of an aluminum rod to each metal foil for a positive electrode and a negative electrode by stitching or ultrasonic welding, and then attaching the metal terminal through a separator. A capacitor element is formed by winding each metal foil, impregnating it in an electrolytic solution, firing it, and performing a chemical conversion treatment.The capacitor element is then placed in a resin case and sealed with a potting resin such as epoxy resin. In a solid electrolytic capacitor configured by cutting the sealing side of the resin case and then connecting external connection terminals to each of the metal terminals exposed by the cutting by laser welding, phosphor bronze is used as the terminal material of the external connection terminals. A metal plate piece of a copper base material with a three-layer structure consisting of a copper base material such as, a nickel plated side treated on one side of the copper base material, and a solder plated side treated on a part of the nickel plated side. and the metal terminal side of the metal plate piece is a copper-based base material,
The device is characterized in that the laser irradiation surface is connected to the nickel-plated surface, and the surface mounting side to a printed circuit board or the like is the solder-plated surface.

[0007]

[Function] According to the solid electrolytic capacitor of the present invention, by using a copper-based base material such as phosphor bronze that easily forms an alloy with aluminum as the terminal material for the external connection terminal, the strength between the aluminum bar metal terminal and the aluminum bar metal terminal is high. Can weld. Furthermore, the nickel-plated surface on one side of this copper base material increases the absorption efficiency of laser light, and the solder-plated surface facilitates soldering to printed circuit boards and the like.

[0008]

Embodiments Next, embodiments of the solid electrolytic capacitor according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing the structure of an external connection terminal portion of a solid electrolytic capacitor according to an embodiment of the present invention, and (A) in FIG. 1 is an enlarged view of the thickness direction of the external connection terminal portion. The side view (B) of FIG. 1 is a plan view of the external connection terminal looking at the metal terminal side of the capacitor element. In FIG. 1B, reference numeral 22 indicates a resin case, and a capacitor element (not shown) is sealed in the resin case 22 with an epoxy resin 16, which is a potting resin for sealing. External connection terminals 28, 28 made of a copper-based base material are laser welded 3 to metal terminals 24, 24, which become both electrodes of the capacitor element, respectively.
Weld by 6,36. This external connection terminal 28 is
As shown in FIG. 1A, it has a three-layer structure in which nickel plating 32 is applied to one side of a copper base material 30 such as phosphor bronze, and further solder plating 34 is applied to a part of the nickel plated surface. .

FIGS. 2A to 2D are external perspective views schematically showing the main manufacturing steps of a solid electrolytic capacitor using the external connection terminal 28 according to the present invention in order of process. Hereinafter, the method for manufacturing a solid electrolytic capacitor according to the present invention will be explained in order of steps with reference to FIG.

In FIG. 2A, reference numeral 22 is a resin case whose inside is molded into a cylindrical recess, and the opening of the resin case 22 is conical and wider than the diameter of the cylindrical recess inside. It is tapered. The capacitor element 12 attached to the transport frame 10 by welding 26 or the like is inserted into the resin case 22 formed in this manner. At this time, the capacitor element 12 and the resin case 22
Since the opening has a taper, alignment with the holder does not require very strict alignment accuracy and can be easily inserted. Although not shown, if an epoxy resin 16, which is a potting resin, is injected into the bottom in advance, the airtightness of the bottom and the surrounding area will be improved. Moreover, this capacitor element 12
After attaching metal terminals 24, 24 made of aluminum rods with lead wires 14, 14 attached to each metal foil (not shown) for the positive electrode and negative electrode in advance by stitching or ultrasonic welding, etc., Each metal foil is wound through a separator, impregnated with an electrolytic solution, fired, and further subjected to a chemical conversion treatment.

FIG. 2B shows the transport frame 10.
The capacitor element 12 attached to the capacitor element 12 is housed in a resin case 22, and molten epoxy resin 16 is further injected into the capacitor element 12, and the epoxy resin 16 is hardened and sealed. The epoxy resin 16 injected into the resin case 22 forms unevenness due to surface tension in its molten state, but if the epoxy resin 16 is injected up to the taper part, even if the amount of resin varies slightly, the next part will be formed below the taper part. There is no problem because it is cut in the cutting process.

In FIG. 2C, the epoxy resin 1 is applied to a predetermined length below the tapered portion of the resin case 22.
6 and the metal terminals 24, 24 are cut together, leaving the metal terminals 24, 24 exposed as shown.

In FIG. 2(D), external connection terminals 28 and 28 having the three-layer structure shown in FIG. irradiation and attaching by laser welding 36. Thereafter, by printing rated values, electrode polarities, etc. on the surface of the resin case 22, a square solid electrolytic capacitor for surface mounting is completed.

[0014]

Effects of the Invention As is clear from the above embodiments, according to the present invention, since a copper base material such as phosphor bronze is used as the terminal material of the external connection terminal, it has the necessary strength as a terminal material. Moreover, during welding, it is easy to form an alloy with the aluminum rod electrode terminal exposed by cutting, so welding strength can be maintained high.

[0015] In addition, a copper base material with a three-layer structure consisting of an external connection terminal using a copper base material such as phosphor bronze, nickel plated on one side, and a solder plated surface on a part of the nickel plated surface. The terminal structure uses a piece of metal plate, with a nickel-plated surface that has a high absorption rate of laser light on the laser irradiation surface, and a solder-plated surface on the connection surface of the printed circuit board, etc., so laser welding is possible. can be done efficiently, and
Solder connection to a printed circuit board or the like is also facilitated.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and it goes without saying that various design changes can be made without departing from the spirit of the present invention. It is.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the structure of an external connection terminal portion of a solid electrolytic capacitor according to an embodiment of the present invention;
is a side view showing an enlarged view of the external connection terminal in the thickness direction;
(B) is a plan view of the external connection terminal when looking at the metal terminal side of the capacitor element.

FIG. 2 is an external perspective view showing the main manufacturing steps in the method for manufacturing a solid electrolytic capacitor according to the present invention in order of process.

[Explanation of symbols]

Claims (1)

[Claims] [Claim 1] After attaching metal terminals of aluminum rods to each metal foil for the positive and negative electrodes by stitching or ultrasonic welding, each metal foil is wound through a separator and impregnated with an electrolytic solution. A capacitor element is formed by firing and chemical conversion treatment, this capacitor element is housed in a resin case and sealed with a potting resin such as epoxy resin, and after cutting the sealing side of the resin case, In a solid electrolytic capacitor configured by connecting external connection terminals to each of the exposed metal terminals by laser welding, a copper base material such as phosphor bronze is used as the terminal material of the external connection terminals, A metal plate piece of a copper-based base material with a three-layer structure consisting of a nickel plated surface treated on one side and a solder plated side treated on a part of the nickel plated side is used, and the metal terminal side is copper-plated. A solid electrolytic capacitor characterized in that the connection structure is such that the base material and the laser irradiation surface are nickel-plated, and the surface mounting side to a printed circuit board or the like is a solder-plated surface.