JPS5915487Y2 - solid electrolytic capacitor - Google Patents

Description

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

In general, solid electrolytic capacitors have a capacitor element A that has a valve action in advance, as shown in Fig. 1, which is made by press-molding metal powder such as tantalum, niobium, aluminum, etc., into a cylindrical shape and sintering it. A metal wire is planted as an anode lead B, a first external lead member C bent in an L shape is welded to the protruding part of this anode lead B, and a second external lead member is attached around the capacitor element A. It is constructed by soldering to an electrode lead-out layer E formed on the surface via an oxide layer and a semiconductor layer, and then covering the entire circumferential surface of the capacitor A with a resin material F.

By the way, this container is a container element)
Despite the fact that the entire circumference of A is simply covered with resin material F, characteristics such as capacitance, impedance, dielectric loss, and leakage current tend to deteriorate after long-term use. .

The cause of this is that the first and second external lead members C and D
Moisture that enters through the contact boundary between the resin material F and the resin material F, or that enters directly through the resin material F, or that is previously adsorbed on the resin material F, may cause an oxidation layer in the condenser element A. .

It is known that this is because it acts on semiconductor layers and the like.

In particular, moisture that directly passes through the resin material F and enters is considered to have a large influence on the moisture resistance.

Therefore, in the past, attempts have been made to mix a large amount of moisture-absorbing material into the resin material F, or to apply a moisture-proof material to the surface of the capacitor element (A) or the outer circumferential surface of the resin material F. Not enough effect has been obtained.

In view of these points, this proposal provides a solid electrolytic capacitor that can effectively improve moisture resistance with a simple configuration.
Examples will be described below.

In FIG. 2, reference numeral 1 denotes a condenser element made by press-molding metal powder having a valve action into a cylindrical shape and sintering it; for example, depending on the desired characteristics, the sintering operation may be omitted.

Reference numeral 2 denotes an anode lead made of a metal wire having a valve action and led out from the condenser element 1. In the illustrated example, it is installed at the center of the condenser element 1, but it can also be welded to the circumferential surface of the anode lead. .

Reference numeral 3 denotes an electrode extraction layer formed on the circumferential surface of the capacitor element 10 via an oxide layer and a semiconductor layer. In the illustrated example, the layer is composed of a graphite layer and a silver paste layer, but it can also be composed of other conductive materials. You can also do that.

4 is an airtight terminal placed on the top surface 1a of the anode lead 2 of the condenser element 1 on the outlet side; 5 is a ring-shaped metal member whose surface has been treated to be solderable;
7 is an insulating member such as glass that is airtightly filled inside the metal member 5, and 7 is a hole formed in the center of the insulating material 6 so that the anode lead 2 can pass therethrough.

Reference numeral 8 denotes a first external lead member bent into an L shape, the bent portion of which is welded to cross the tip of the anode lead 2 that protrudes through the hole 7 of the hermetic terminal 4.

Reference numeral 9 denotes a second external lead member, the inner end of which is connected, for example, to the periphery of the metal member 5 of the hermetic terminal 4.

Reference numeral 10 denotes a solder member that is adhered to the metal member 5 of the electrode lead layer 3 and the airtight terminal 4. In the illustrated example, the solder member is applied over the side peripheral surface of the metal member 5, but it is simply a metal member. 5 can also be integrally connected to the electrode lead layer 3 by a solder member 10.

Reference numeral 11 denotes a filling member for closing the space between the anode lead 2 and the hole 7 of the airtight terminal 4, such as glass, solder, or rubber.

Resin etc. can be used.

Reference numeral 12 denotes a resin material that covers the entire circumferential surface of the capacitor element 1, and in addition to the illustrated molding method, it can also be covered by a dipping method, a plasma spraying method, or the like.

Next, the manufacturing method will be explained with reference to FIG.

First, as shown in FIG. 1A, the condenser element 1 is immersed in a chemical solution to form an oxide layer on its surface by chemical conversion treatment.

After this capacitor element 1 is immersed in the semiconductor mother liquor and sufficiently impregnated, it is thermally decomposed in a high temperature atmosphere to form a semiconductor layer on the oxide layer.

Thereafter, a graphite layer and a silver paste layer are polymerized on the semiconductor layer to form the electrode lead layer 3.

Next, as shown in the figure, an airtight terminal 4 having a second external lead member 9 is attached to the top surface 1a of the anode lead 2 of the capacitor element 1 on the outlet side, and the anode lead is inserted into the hole 7 of the insulating member 6 of the airtight terminal 4. Place it so that 2 is inserted through it.

The outer diameter of the airtight terminal 4 is set to be almost flush with the circumferential surface of the electrode lead layer 3 of the capacitor element 1 in the mounted state.

Next, as shown in FIG.
A solder member 10 is integrally attached to the side peripheral surface of the metal member 5 at.

Note that since the solder member 10 in a molten state has a certain degree of viscosity, it does not penetrate between the lower surface of the airtight terminal 4 and the top surface 1a of the capacitor element 1 and come into contact with the anode lead 2 when immersed. .

Next, the space formed between the anode electrode 2 and the hole 7 of the airtight terminal 4 is closed with a filling member 11.

In particular, when glass is used as the filling member 11, the hermetic terminal 4 and the anode lead 2 can be hermetically bonded by applying a member made of glass powder, a binder, and a solvent to the same space and heating it.

After that, the anode lead 2 is cut from the XX portion.

Next, as shown in FIG. 4D, the first external lead member 8 is welded to the protrusion 2a of the anode lead 2 so that its bent portion intersects with the protrusion 2a.

Thereafter, as shown in FIG. 5E, the entire circumferential surface of the capacitor element 1 is covered with a resin material 12 to obtain a solid electrolytic capacitor.

In addition, solder member 10. Filling member 11. The order of processing operations for the first external lead member 8 and the anode lead 2 can be changed as appropriate.

In this way, the top surface 1a of the capacitor element 1 is covered with the airtight terminal 4, and the side peripheral surface of the metal member 5 in the electrode lead layer 3 and the airtight terminal 4 is covered with the solder member 10.
Since the exterior of the capacitor element 1 is integrally airtight, not only moisture that enters through the resin material 12 but also moisture that has been adsorbed in advance on the resin material 12 acts on the oxidized layer and the semiconductor layer in the capacitor element 1. can be reduced.

Therefore, the moisture resistance caused by moisture caused by long-term use can be significantly improved.

In particular, good moisture resistance can be achieved by minimizing the space formed between the hole 7 of the hermetic terminal 4 and the anode lead 2; The work of placing it on the top surface 1a of 1 becomes extremely troublesome.

Therefore, if such a space is hermetically sealed with the filling member 11, the work of mounting the airtight terminal 4 on the capacitor element 1 can be improved since there is enough room in the hole 7, and at least the moisture resistance caused by moisture can be improved. You can completely eliminate the drop.

Furthermore, sparks generated when welding the first external shield member 8 to the protrusion 2a of the anode lead 2 deteriorate the semiconductor layer and oxide layer on the top surface 1a of the capacitor element 1, impairing leakage current characteristics. There is a tendency to

However, in the above structure, the oxide layer and semiconductor layer exposed on the top surface 1a are completely protected by the airtight terminal 4 placed on the top surface 1a, so such troubles during welding can be eliminated.

Furthermore, if the space between the anode lead 2 and the hole 7 of the airtight terminal 4 is sealed before welding the first external lead member 8 to the protrusion 2a of the anode lead 2, the lateral direction of the anode lead 2 can be sealed. Even if the pressing force acts on the contact boundary between the capacitor element 1 and the capacitor element 1, the pressing force does not act on the contact boundary between the capacitor element 1 and the capacitor element 1.

Therefore, since no cracks occur in the oxide layer and semiconductor layer in the same portion, there is no deterioration in leakage current characteristics, and high reliability can be maintained for a long period of time.

FIG. 4 shows another embodiment of the present invention, in which the first external lead member 8 is constructed by extending the anode lead 2. As shown in FIG.

The tip of the first external lead member 8 is formed by, for example, being chemically or mechanically polished, and then formed by polymerizing a graphite layer and a silver paste layer, and further forming a solder layer on the silver paste layer to form an external circuit. Designed to make soldering easier.

In addition, after polishing, we plate metals that can be soldered,
It can also be vapor-deposited.

FIG. 5 shows another embodiment of the present invention, in which the second external lead member 9 is immersed in a molten solder bath while in contact with the electrode lead layer 3 and then pulled up, so that the second external lead member 9 is directly connected to the electrode lead layer 3. is soldered to.

By providing the second external lead member 9 separately from the airtight terminal 4 in this way, the occurrence of lead bending, etc. can be reduced, and work efficiency in the inspection process can be improved.

FIG. 6 shows another embodiment of the present invention, in which the exterior resin material 12 in the embodiment shown in FIG. 4 is omitted.

According to this embodiment, since the entire circumferential surface of the capacitor element 1 is simply covered with the airtight terminal 4 and the solder member 10, sufficient moisture resistance can be obtained even by omitting the resin material 12. However, due to its miniaturization, it can be easily incorporated into small products such as electronic wristwatches.

FIG. 7 shows another embodiment of the present invention, in which the metal member 5 in the airtight terminal 4 has a peripheral edge bent downward in an L shape, and the inner diameter of the bent portion is the same as that of the capacitor element 1. The diameter is set to be slightly larger than the outer diameter of the electrode extraction layer 3.

According to this embodiment, when the capacitor element 1 is immersed in the molten solder bath, it is possible to effectively prevent solder from going around and adhering to the top surface 2a of the capacitor element 1.

Note that in this embodiment, the filling member 11. The resin material 12 can also be omitted.

FIG. 8 shows another embodiment of the present invention,
A metal pipe 13 is connected to an insulating member 6 at the center of the airtight terminal 4.
The outer end of the pipe 13 is sealed.

The protruding portion of the anode electrode 2 is inserted into this pipe 13 and then welded.

Further, the first external lead member 8 is welded to the outer surface of the pipe 13.

Note that this pipe 13 has its upper and lower ends open, and the anode lead 2
Alternatively, the first external lead member 8 may be sealed when welding.

According to this embodiment, even if the resin material 12 is omitted, the capacitor element 1 is kept completely airtight from the outside world, so that the moisture resistance can be sufficiently improved.

In this case, the metal member of the airtight terminal can be constructed by attaching a metal that can be soldered to the outer periphery of the insulating member, or the metal member can be omitted and the outer periphery of the insulating member can be soldered. Attachment can also be made possible.

As described above, according to the present invention, moisture resistance can be significantly improved by a simple structure in which the anode lead lead-out surface of the capacitor element is protected by an airtight terminal, and high reliability can be maintained over a long period of time. I can do it.

[Brief explanation of the drawing]

Figure 1 is a front sectional view of the conventional example, Figure 2 is a front sectional view showing an embodiment of the present invention, Figure 3 is a front sectional view for explaining the manufacturing method, and Figures 4 to 8 are the present invention. FIG. 3 is a front sectional view showing different embodiments of the invention. In the figure, 1 is a capacitor element, 2 is an anode lead, 3
4 is an electrode lead layer, 4 is an airtight terminal, 5 is a metal member, 6 is an insulating member, 8 is a first external lead member, 9 is a second external lead member, and 10 is a solder member.

Claims (1)

[Scope of utility model registration request] A capacitor element formed by molding metal powder with a valve action into a desired shape and forming an electrode lead layer on its circumferential surface, an anode lead made of a metal wire with a valve action derived from the capacitor element, and an outer periphery of an insulating member. An airtight terminal that has been treated to allow soldering, a solder member that is integrally attached to the outer periphery of the airtight terminal placed on the anode lead lead-out surface of the capacitor element and the electrode lead-out layer of the capacitor element, and an anode lead. A solid electrolytic capacitor comprising: a first external lead member that extends further; and a second external lead member that extends from an electrode extraction layer of a capacitor element.