JPS5813017B2 - condenser no seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a capacitor, and more particularly to an improvement in a method for reforming capacitor pellets.

In general, this type of capacitor is made by press-molding metal powder with valve action, such as tantalum or titanium, into a cylindrical shape and sintering it. An insulating layer as a dielectric layer is formed on the surface of the capacitor pellet by chemical conversion treatment. The semiconductor layer is then formed on the insulating layer by thermal decomposition, which is repeated several times.

However, during this decomposition process, the oxide film layer, which is an insulating layer, tends to deteriorate due to thermal stress and the like, resulting in a decrease in dielectric strength.

Therefore, re-forming is performed several times in order to repair the insulating layer after each decomposition process or after the decomposition process.

This regeneration is carried out as follows.

That is, for example, H3P04 or H used in chemical synthesis
The concentration of 2SO4 is made slightly lower than that at the time of chemical formation and used as an electrolytic solution.

Then, the capacitor pellets are immersed in the electrolytic solution tank filled with this during or after the decomposition process, and a direct current is passed through the capacitor pellets.

Conventionally, this reconstitution or reconstitution has been carried out by applying a constant voltage according to the expected withstand voltage of the capacitor to be reconstituted.

However, with this method, voltage is rapidly applied to the capacitor, so the insulating layer may not be repaired and may be destroyed all at once.

Therefore, a voltage application method is also used in which the voltage is gradually increased immediately after application.

However, even if it falls down, with this method of applying a constant voltage, if the set voltage is low, it can only be restored to a low withstand voltage.

On the other hand, if the set voltage was increased, a large current exceeding the repair current would flow in a capacitor that had not been sufficiently repaired, causing it to be destroyed.

Furthermore, even if it is possible to make a product with a higher withstand voltage by further increasing the voltage and supplying a repair current, because many capacitors with varying withstand voltages are being re-formed at the same time, those with low withstand voltages may be destroyed by re-forming. In order to prevent this, the reconversion voltage is set low to match the low withstand voltage.

For this reason, reconstituted capacitors remain at a specified low breakdown voltage.

In view of the above-mentioned drawbacks, the present invention is an improvement on this, and attempts to restore the withstand voltage of each capacitor to its upper limit without causing dielectric breakdown by devising a reformation method.

In other words, capacitors that could not withstand the specified withstand voltage and were destroyed are completed as low-voltage grade products, and capacitors that can be made to have a higher withstand voltage by applying a repair current are made to withstand up to the upper limit. The aim is to raise the level of pressure and create a product with high pressure resistance.

That is, in the re-forming method of the present invention, the re-forming current is applied by applying a constant current instead of the conventional constant voltage application.

Such a reconversion step of the present invention is carried out as follows.

In FIG. 1, reference numeral 1 indicates a re-forming liquid which is slightly diluted than the chemical liquid, and is filled in an electrolytic cell 2.

A constant current is caused to flow through the capacitor pellet 3 from a constant current source 4.

The magnitude of this constant current is selected to match or conform to the maximum allowable leakage current of the capacitor, and the reconstitution voltage is measured by a voltmeter 5.

For example, the voltage rise during re-formation is as shown in FIG.

Since constant current is applied, the voltage increases relatively linearly with respect to the application time in the initial stage.

As the voltage increases, the leakage current begins to increase and the current contributing to charging decreases, so the slope becomes flat.

Furthermore, the insulating layer is repaired by the reformation current, the dielectric strength is improved, and the leakage current is reduced, and during this time the voltage increases while the slope changes.

Finally, when this slope becomes flat and the leakage current becomes equal to the applied current, re-formation is stopped.

By measuring the voltage at this time, it is possible to accurately know the withstand voltages V1 and V2 with respect to the maximum allowable leakage current.

As explained above, the present invention involves forming a semiconductor layer on the insulating layer of a capacitor pellet made by molding metal powder having a valve action into a desired shape, and then regenerating it at a constant current that is less than the maximum allowable leakage current of the capacitor. Since we have provided a method for manufacturing capacitors that is characterized by chemical formation, it is possible to restore the withstand voltage of the capacitor to its upper limit without causing dielectric breakdown due to re-forming, and to accurately measure the withstand voltage. It can be completed efficiently.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the re-forming method of the present invention, and FIG. 2 is a diagram showing the relationship between the current application time and the voltage applied to the capacitor pellet during re-forming. 1... Reconversion liquid, 2... Electrolytic tank, 3.
... Capacitor pellet, 4 ... Constant current source, 5 ... Voltmeter, VL, V2 ... ... Capacitor after repair corresponding to the maximum allowable leakage current. Pressure resistant.

Claims (1)

[Claims] 1. After forming a semiconductor layer on the insulating layer of a capacitor pellet made by molding metal powder with valve action into a desired shape, reconstitution is performed at a constant current that is less than the maximum allowable leakage current of the capacitor. Method of manufacturing capacitors.