JPS5915483Y2 - solid electrolytic capacitor - Google Patents

Description

[Detailed Description of the Invention] The present invention mainly relates to the improvement of a small solid electrolytic capacitor.

In general, this type of solid electrolytic capacitor has an anode lead extending from a capacitor element made by press-molding metal powder such as tantalum, niobium, or aluminum into a cylindrical shape and sintering it, as shown in Figure 1. A first external lead member C bent in an L shape is welded to B, and this capacitor element L-A is housed in a bottomed metal cylindrical case D, and the circumferential surface of capacitor element A is The electrode extraction layer E is electrically connected to the conductive adhesive F that has been injected into the case D in advance, and the opening of the case D is closed with the resin material G, and a second external lead is inserted from the bottom outer surface of the case D. It is constructed by deriving the member H.

By the way, before welding the first external lead member C to the anode lead B extending from the capacitor element A, an oxide layer is formed as a dielectric layer by chemical conversion treatment, and a semiconductor mother liquor is applied on this oxide layer. A semiconductor layer is formed by an impregnation-pyrolysis operation, and an electrode lead layer E is further formed on this semiconductor layer.

However, in the process of forming the semiconductor layer, the temperature of the capacitor element A that is inserted into the high-temperature atmosphere rises rapidly, and the semiconductor mother liquor impregnated inside undergoes a thermal decomposition reaction, causing water vapor to flow from inside. As decomposed gases such as nitrogen oxides blow out to the surface layer, bubbles are generated in the semiconductor mother liquid layer in the middle of thermal decomposition in the surface layer, and these bubbles adhere to the protruding part of the anode lead B, causing so-called creeping of the semiconductor layer forming member. It causes an upslope.

Normally, the impregnation-pyrolysis operation of the semiconductor mother liquor is repeated several times or more, and as the number of times of thermal decomposition increases, the creeping of the semiconductor forming member tends to progress further.

Therefore, when welding the first external lead member C to the protruding portion of the anode lead B, the first external lead member C and the semiconductor layer that has climbed up come into contact with each other, causing a short circuit between the cathode and the anode. There is a problem that the capacitor cannot function as a capacitor or leakage current increases.

Therefore, conventionally, a configuration has been adopted in which a Teflon washer is attached to the top surface of the capacitor element A, and the anode lead B is inserted through the center hole of the Teflon washer.

According to this method, the creeping-up phenomenon of the semiconductor layer at the protruding portion of the anode lead B can be effectively suppressed, but since the capacitor element itself is small, the Teflon washer is also small, which significantly reduces workability. It also has the disadvantage of poor mass production.

This project was proposed in view of these points, and consists of a capacitor element that uses a metal member that has a valve action as a material and has an electrode extraction layer formed on its circumferential surface, and a metal member that has a valve action that is derived from the capacitor element. a cylindrical case that houses the capacitor element and has the anode lead bent into an approximately L shape and electrically connected to its tip, and an external lead member led out from the electrode extraction layer of the capacitor element. , and a resin material filled to seal the opening of the case.

An embodiment of the present invention will be described with reference to FIG. 2. 1 is a capacitor element formed of a metal member having a valve action as a material, and the illustrated example is a capacitor element formed by pressure forming metal powder having a valve action into a cylindrical shape. Constructed by sintering.

Incidentally, as the metal member, a metal wire or a crushed metal wire may also be used.

Reference numeral 2 denotes an anode lead made of a metal member having a valve function and installed in advance on the capacitor element 1, and can also be led out by welding to the circumferential surface of the capacitor element 1, for example.

Reference numeral 3 denotes an electrode lead layer formed on the circumferential surface of the capacitor element 1 via an oxide layer and a semiconductor layer, and in the illustrated example, it is composed of a graphite layer and a silver paste layer deposited in this order, but it is simply a graphite layer. It can also be made of only one conductive material or other conductive members.

Reference numeral 4 denotes a cylindrical case made of a metal member, in which the capacitor element 1 is housed.

Furthermore, the anode lead 2 extending from the condenser element 1
The protruding portion is bent into a substantially single shape, and its tip 2a is connected to the inner surface (or outer surface) of the end portion of the case 4 by welding, conductive adhesive, or the like.

Reference numeral 5 denotes a resin material filled in one opening of the case 4, and the tip portion of the anode lead 2 is completely embedded therein.

Reference numeral 6 denotes a first external lead member, which is led out by welding to a protruding piece 4a extending from the case 4, for example.

Reference numeral 7 denotes a second external lead member, which is connected to the electrode lead layer 3 with a connecting member 8 such as solder.

Reference numeral 9 denotes a resin material filled in the outlet side opening of the second external lead member 7 of the case 4 .

In this way, the protrusion length of the anode lead 2 from the capacitor element 1 is set to be sufficiently longer than the creep height of the semiconductor layer to the anode lead 2, so when connecting the tip 2a to the case 4, Climbed semiconductor layer and case 4
It is possible to eliminate all short circuits.

Therefore, not only electrode short-circuit defects but also leakage current characteristics can be significantly improved.

Furthermore, although the extended length of the protruding portion of the anode lead 2 is set to be long, since it is bent into an approximately L shape within the case 4, there is no need to make the case length particularly long. By bringing the bending position closer to the top surface of the condenser element 1, the length of the case can be shortened and further miniaturization becomes possible.

In particular, when welding is used as the connection means between the tip 2a of the anode lead 2 and the case 4, the welding position of both is shifted from the top surface of the capacitor element 1, so welding sparks may cause damage to the top surface of the capacitor element 1. Damage to oxide and semiconductor layers is significantly reduced.

Therefore, the leakage current characteristics are improved and the quality of the container can be improved.

Furthermore, since both openings of the case 4 are closed by filling the resin materials 5 and 9, moisture resistance can be significantly improved, and the anode lead 2 and the second external lead member 7 are fixed by the filled resin material. Therefore, their mechanical strength can also be improved.

FIG. 3 shows another embodiment of the present invention, in which the tip 2a of the anode lead 2 bent into an L-shape is connected to a protruding piece 4a of the case 4.
It is juxtaposed with and simultaneously welded to the first external lead member 6 at the same time.

According to this embodiment, in particular, the inner diameter of the case 4 is 2 to 3 mm.
If the difference is small, the connectivity of the tip 2a to the case 4 is improved.

At this time, the first external lead member 6 can also be connected separately.

In this case, the case may have a metal connection part with the anode lead and an insulating material at the other end, or the first external lead member may be formed by extending a part of the case. It can also be omitted.

As described above, according to the present invention, by setting the protrusion length of the anode lead to be long, the electrode short circuit accident can be easily solved.
Moreover, excellent effects such as significantly improved workability can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front sectional view of a conventional example, and FIGS. 2 and 3 are front sectional views showing different embodiments of the present invention. 1... Capacitor element, 2...
Anode lead, 2a... Tip, 3... Electrode extraction layer, 4... Case, 5.9...
・Resin material, 7... External lead member.

Claims (1)

[Scope of utility model registration request] A capacitor element made of a metal member having a valve action as a material and having an electrode extraction layer formed on its circumferential surface, an anode lead made of a metal member having a valve action derived from the capacitor element, and an anode lead housing the capacitor element. A cylindrical case is formed by bending it into an approximately L shape and electrically connecting its tip, an external lead member led out from the electrode extraction layer of the capacitor element, and a cylindrical case filled to seal the opening of the case. A solid electrolytic capacitor characterized by comprising a resin material.