JPH0760778B2 - Method for manufacturing solid electrolytic capacitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a solid electrolytic capacitor, and more specifically to a means for protecting the anode lead thereof.

[Conventional technology]

FIG. 2 (a) shows a capacitor element 1 as a typical conventional example forming the core of a solid electrolytic capacitor.
That is, the capacitor element 1 is made of, for example, a sintered body of metal powder such as Ta or Nb having a valve action, and the anode lead 2 is implanted at one end thereof. The anode lead 2 is embedded at one end before sintering or is attached after sintering, for example, by welding. An oxide film is formed on the surface of the capacitor element 1 by electrolytic oxidation, and then a semiconductor electrolyte (solid electrolyte) is formed thereon. For example, by repeating impregnation and pyrolysis of manganese nitrate a plurality of times, an MnO ₂ layer as a semiconductor electrolyte is formed, but at that time, a phenomenon in which MnO ₂ crawls onto the anode lead 2 occurs.

In order to prevent this, conventionally, as shown in FIG. 2 (b), for example, a fluorine resin plate 3 is attached to the lead-out portion of the anode lead 2.
Alternatively, the lead-out portion of the anode lead 2 is coated with, for example, a silicon-based resin 4 as shown in FIG.

[Problems to be Solved by the Invention]

However, in the method shown in FIG. 2 (b), when the fitting with the anode lead 2 is loose, the resin plate 3 floats up and the Mn
Not only does it not have the effect of preventing O ₂ from creeping up,
Problems occur when welding external lead wires to. That is, since the connection between the sintered body and the anode lead is not protected at all, it is susceptible to mechanical stress when welding the external lead wire to the anode lead 2 or heat shrinkage stress of the exterior resin, resulting in characteristic deterioration. This leads to an increase in leakage current.

On the other hand, in the case of applying the resin 4 shown in FIG. 7C, the connection between the sintered body and the anode lead is protected by it, but workability such as the dropping position or dropping amount of the resin is improved. I have a problem.

The present invention has been made to solve the above-mentioned conventional drawbacks, and an object thereof is to provide a solid electrolytic capacitor capable of effectively protecting a connecting portion between a capacitor element and an anode lead without impairing productivity. It is to provide a manufacturing method.

[Means for Solving the Problems]

In order to achieve the above object, in the present invention, Ta, Nb
Polyetheretherketone (PE) is formed on the anode lead lead-out portion of the capacitor element, which is made of a sintered body of metal powder having a valve action such as
EK), polyether sulfone (PES), or thermoplastic polyimide (TPI) is inserted, and then the washer is heated and melted so as to be in close contact with the anode lead lead portion.

Of the above washers, when heating and melting a washer with a relatively high melting point, the capacitor element
If formed of Ta powder, if kept at high temperature under normal pressure, the metal surface will oxidize and there is a danger of burning eventually. Therefore, it is preferable that the above-mentioned washer is heated and melted by spraying a heated inert gas such as N ₂ or Ar or by melting it in the inert gas atmosphere.

The washer is heated and melted before forming an oxide film by electrolytic oxidation of the capacitor element, after forming an oxide film by electrolytic oxidation on the surface of the capacitor element, and forming a solid electrolyte on the capacitor element. It is preferable to carry out at the same time.

As the material of the washer, any one of PEEK (polyether ether ketone; melting point 340 ° C.), PES (polyether sulfone; no melting point because it is amorphous), TPI (thermoplastic polyimide; melting point 382 ° C.) is used. .

Here, the method of manufacturing the solid electrolytic capacitor according to the present invention will be described more specifically with reference to FIG. First, as shown in FIG. 3A, a washer 5 made of a film or sheet selected from the above materials was cut into a size corresponding to the capacitor element 1, and the washer 5 was inserted into the anode lead 2. After that, the anode lead 2 is welded to an appropriate hoop material 6. When the washer 5 is attached to the hoop material 6 and conveyed to the next step, the washer 5 is applied to the lead-out portion of the anode lead 2 by a guide member (not shown) as shown in FIG. Is positioned as.
Next, high temperature N ₂ gas, for example, is blown by a dryer (not shown). As a result, the washer 5 melts and comes into close contact with the lead-out portion of the anode lead 2 as shown in FIG. Reference numeral 5a indicates the close contact.

[Action]

Since the above heating and melting can be performed in a series of flow steps, the anode lead connecting portion can be strongly protected without lowering the production capacity.

<< Example 1 >> Polyketone-based film PEEK “Stay bar K200” (trade name; IC Japan Co., Ltd.) is used for the anode lead of a tantalum capacitor element having an outer dimension of 0.94 × 1.95 × 1.0 mm.
0.1 mm thick washer made of (made by Hakukou Metal Co., Ltd.) was passed through, and the washer was melted while supplying N ₂ gas with a heat gun (Hakuko Metal Co., Ltd.). Next, an oxide film is applied to the surface of the capacitor element by electrolytic oxidation, an MnO ₂ layer, a carbon layer, and a silver layer are sequentially formed, and after connecting the external terminals, it is covered with an exterior resin (epoxy) and the rated voltage is 4V Capacitance 10μ
A solid electrolytic capacitor of F was manufactured.

<< Example 2 >> The same positive electrode lead of the capacitor element as in Example 1 was formed with a polyketone film PEEK "Stay bar XK300" (trade name; ICI Japan Co., Ltd.) and a thickness of 0.07.
A 5 mm washer was inserted, and then electrolytic oxidation was performed to form an oxide film on the surface of the capacitor element (first chemical conversion).
Then, the inside of the electric furnace was heated to melt the washer. After the second chemical conversion is performed to form a desired oxide film, MnO ₂ layer, carbon layer, and
A silver layer was sequentially formed, external terminals were connected, and then coated with an exterior resin (epoxy) to manufacture a solid electrolytic capacitor having a rated voltage of 4 V and a capacitance of 10 μF.

<< Example 3 >> Polyimide film "NEW-TPI" (trade name; Mitsui Toatsu Co., Ltd.) was used for the same anode lead of the capacitor element as in Example 1.
0.1 mm thick washer was inserted through the washer, and the washer was melted while supplying N ₂ gas with a heat gun (manufactured by Hakuko Metal Co., Ltd.) as in Example 1. Next, an oxide film is applied to the surface of the capacitor element by electrolytic oxidation, and Mn
O ₂ layer, carbon layer, silver layer are formed in order, external terminals are connected, then coated with exterior resin (epoxy), rated voltage 4
A solid electrolytic capacitor with V and capacitance of 10 μF was manufactured.

[Comparative Example 1] A 0.2 mm-thick washer made of TFE (tetrafluoroethylene) was inserted into the anode lead of the same capacitor element as in Example 1, electrolytic oxidation was performed to form an oxide film on the surface, and then MnO ₂ A layer, a carbon layer, and a silver layer were sequentially formed, external terminals were connected, and then coated with an exterior resin (epoxy) to fabricate a solid electrolytic capacitor having a rated voltage of 4 V and a capacitance of 10 μF.

«Example 4» Anode lead of the same capacitor element as in Example 1 was made of an amorphous film PES “Stay bar S100” (trade name; ICI Japan Co., Ltd.) with a thickness of 0.1 mm. The washer was inserted, and an oxide film was formed on the surface of the capacitor element by electrolytic oxidation. Next, manganese nitrate (specific gravity
1.3) Impregnated with aqueous solution and heated at high temperature (300
It decomposed at ~ 350 ° C) and melted the washer at the same time when MnO _{2 was} produced. Then, pyrolysis of manganese nitrate was repeated a predetermined number of times to form an MnO ₂ layer. After that, form a carbon layer and a silver layer in order, connect external terminals, and then coat with external resin (epoxy), rated voltage 16V, capacitance 3.3μF
The solid electrolytic capacitor was manufactured.

Comparative Example 2 In the same manner as in Comparative Example 1, a solid electrolytic capacitor having a rated voltage of 16 V and a capacitance of 3.3 μF was manufactured.

Each of the above-mentioned examples and comparative examples was prepared in 10,000 units, and their capacitance Cap (μF), loss angle tangent tan δ, leakage current L
The following table shows the results (average values) of C (μA), characteristic defect rate (%) as a product, and MnO ₂ creeping rate (%).

As is clear from this table, the characteristic defective rate of each example is improved to 1/2 to 1/3 of the conventional example. Further, the MnO ₂ creeping rate is 0% in each of the examples. Further, from the value of the leakage current, a remarkable relaxing effect on the stress at the time of welding the external terminal of the anode and the stress of the exterior resin is recognized.

〔The invention's effect〕

As described above, according to the present invention, the washer made of any one of polyether ether ketone (PEEK), polyether sulfone (PES) or thermoplastic polyimide (TPI) is inserted into the anode lead lead portion of the capacitor element. Then, the washer is heated and melted to be brought into close contact with the anode lead lead-out portion, whereby the anode lead connecting portion can be strongly protected in the series of flow steps without lowering the production capacity. Further, since the film used for the washer has an appropriate strength, it is possible to reduce the film thickness to, for example, about 0.075 to 0.1 mm, and thus the coating height dimension of the molten film can be small, and further the film can be used. It is possible to reduce the cost.

[Brief description of drawings]

1 (a) to 1 (c) are explanatory views showing a process of manufacturing a solid electrolytic capacitor according to the present invention, and FIGS. 2 (a) to 2 (c).
[Fig. 3] is an explanatory diagram showing a conventional example. In the figure, 1 is a capacitor element, 2 is an anode lead, 5 is a washer made of a thermoplastic high heat resistant resin, and 6 is a hoop material.

Claims (4)

[Claims] 1. A capacitor element comprising a sintered body of metal powder such as Ta or Nb having a valve action, and an anode lead being implanted at one end thereof, wherein the polyether lead ketone (PEEK ), Polyether sulfone (PE
A method for producing a solid electrolytic capacitor, characterized in that a washer made of either S) or a thermoplastic polyimide (TPI) is inserted, and then the washer is heated and melted and brought into close contact with the anode lead lead-out portion. 2. The method for producing a solid electrolytic capacitor according to claim 1, wherein the heating and melting of the washer is performed in a high temperature inert gas atmosphere. 3. The method for producing a solid electrolytic capacitor according to claim 1, wherein the washer is heated and melted after an oxide film is formed on the surface of the capacitor element by electrolytic oxidation. 4. The method of manufacturing a solid electrolytic capacitor according to claim 1, wherein the heating and melting of the washer are performed at the same time when the solid electrolyte is formed on the capacitor element.