JPS6116681Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a solid electrolytic capacitor, in particular,
This invention relates to a solid electrolytic capacitor with improved cathode terminal connection.

Generally, in solid electrolytic capacitors, an anode lead wire is provided in advance on a valve metal such as tantalum, aluminum, or niobium, an anodized film is formed on this metal, and then a manganese dioxide layer, a carbon layer, and a conductive layer are formed. The exterior is made of a metal case or resin. The cathode lead wire is then connected to the conductive layer and drawn out. For example, in the case of tantalum solid electrolytic capacitors, a conductive paint is applied on the carbon layer and cured, and then the cathode lead wire is soldered. .

By the way, when attaching a capacitor to a printed wiring board by soldering, the melting temperature of the solder is 30
~40°C higher heat is applied to the cathode lead. As a result, the solder connecting the cathode lead wire to the capacitor may melt, causing the solder to blow out of the casing, or the cathode lead wire may separate from the conductive layer, resulting in defects such as an open state.

Conventionally, in order to improve these drawbacks, capacitors have been developed in which instead of solder, the cathode lead wire is connected using a conductive adhesive that is made by mixing metal particles such as copper or silver with synthetic resin and has a higher melting point than solder. was also used. However, usually, the solder or metal plating such as tin melts on the lead wire so that it can be easily soldered to a printed wiring board, etc., and a gap is created between the lead wire and the conductive adhesive covering the cathode lead wire. The connection is bad,
There is a drawback that the equivalent series resistance increases and tan δ increases.

The object of the present invention is to provide a solid electrolytic capacitor that improves the above-mentioned drawbacks, has improved tanδ characteristics, and is highly reliable.

In order to achieve the above object, the present invention generates an anodized film on the surface of a valve metal provided with an anode lead wire, forms a semiconductor layer, a carbon layer and a conductive layer thereon. In a solid electrolytic capacitor in which a cathode lead wire is connected to a conductive layer with a conductive adhesive, a metal plating that can be soldered and has a melting point higher than that of solder is directly provided on at least the part of the cathode lead wire that comes into contact with the conductive adhesive. The present invention provides a solid electrolytic capacitor characterized by:

Hereinafter, embodiments of the present invention will be described based on the drawings.

1 is a sintered body of tantalum powder, from which an anode lead wire 2 is drawn out. An anode terminal 3 is connected to the anode lead wire 2 by welding or the like. An anodic oxide film 4 is formed on the sintered body 1 by oxidation treatment. The anodic oxide film 4 is formed with a manganese dioxide layer 5 and a carbon layer 6 as semiconductor layers, and a silver conductive paint layer 7 as a conductive layer. A cathode lead wire 8 is connected to this silver conductive paint layer 7 with a conductive adhesive 9 such as silver base. Cathode lead wire 8
In particular, a plating 10 of a metal such as nickel or gold that can be soldered and has a higher melting point than solder is provided. Reference numeral 11 is an exterior casing made of epoxy resin or the like.

Therefore, when soldering to a capacitor printed wiring board, even if the cathode lead wire 8 is heated, the plating 1
0 does not melt and the connection with the conductive adhesive 9 is securely maintained without creating a gap, tan δ
will also be improved.

Regarding tantalum solid electrolytic capacitors with a rating of 16 V and 10 μF, the example of the present invention in which the cathode lead wire is provided with nickel plating and the conventional example in which solder plating is provided, when the soldering time is 1 minute and the soldering temperature is changed. When the change in tan δ was investigated, the results shown in Figure 2 were obtained. In other words, as the soldering temperature increases, tan δ is improved in Example A of the present invention compared to Conventional Example B. For example, at 290°C, the former is approximately 1/2 of the latter, and the difference is small. Remarkable.

As described above, according to the present invention, it is possible to prevent poor connection of the cathode lead wire during soldering, and thus it is possible to obtain a highly reliable solid electrolytic capacitor with improved tan δ.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a graph of tan δ versus soldering temperature. DESCRIPTION OF SYMBOLS 1... Sintered body, 2... Anode lead wire, 3... Anode terminal, 4... Anodized film, 5... Manganese dioxide layer, 6... Carbon layer, 7... Silver conductive paint layer, 8 ... Anode lead wire, 9 ... Conductive adhesive,
10...Metsuki, 11...Exterior.

Claims (1)

[Scope of utility model registration request] An anodic oxide film is formed on the surface of a metal with a valve action provided with an anode lead wire, and a semiconductor layer is formed on the surface of the metal.
In a solid electrolytic capacitor in which a carbon layer and a conductive layer are formed, and a cathode lead wire is connected to the conductive layer with a conductive adhesive, at least the portion of the cathode lead wire that is connected to the conductive adhesive can be soldered, and it is easier than soldering. A solid electrolytic capacitor characterized by having a metal plating with a high melting point directly attached to it.