Societe Lignes Telegraphiques Et Telephoniques

Lignes Telegraphiques Et Telephoniques

Societe Lignes Telegraphics Et Telephoniques

Balint Escher

Dominique Prince

Jean Vasseux

Gilbert Frade

Jean-Claude Moulin

Michele Moulin

Rene' Romanet

Rene Romanet

An improved solid-electrolyte tantalum capacitor for decreasing the danger of tantalum capacitors fires. An opening is provided in the external protection of the capacitor to allow the evacuation of the solder providing the contact between the cathode lead and the cathode when molten.

Tantalum capacitors with internal current-limiting means

Accelerated ageing of solid electrolyte tantalum capacitors in batches by immersion of the capacitors in a semiconducting powder contained in a conductive receptacle connected to one terminal of a d.c. voltage source, the other terminal of which is connected to the anode leads of the capacitors. The voltage of the source is between 1.2 and 1.8 the capacitor rated voltage. The receptacle is maintained between 25.degree. C. and 180.degree. C. Ageing lasts for at least two hours.

Process for the manufacture of tantalum solid electrolyte capacitors

Powdered plastic encapsulation of solid tantalum capacitors is achieved through coating the capacitors between 150.degree. C. and 250.degree. C. while biasing the capacitors at direct voltage between 0.2 and 1 times the rated voltage. The plastic is cured in about 3 minutes. The capacity temperature derating and the reverse current temperature derating are reduced with respect to capacitors encapsulated unbiased at the same temperature.

Encapsulating solid tantalum capacitors

The anodization of sintered anodes for tantalum capacitors is carried out in two successive steps separated by a cleaning step in an acid bath. In a preferred variant of the process both the first anodization and the cleaning are performed on batches of anodes which are individually sorted and mounted on current carrying bars before the second anodization step. The direct leakage current of capacitors made from anodes anodized according to the invention is substantially lower than that of capacitors with prior art anodes. The capacitors are also less sensitive to temperature.

Surface treatment of the anodes for tantalum capacitors

In solid electrolytic tantalum capacitors, the dielectric consisting mainly of tantalum pentoxide contains two different ionized additions the valences of which are respectively higher and lower than 5.

Solid electrolyte tantalum capacitors

In solid tantalum electrolytic capacitors, an additive is introduced in the oxide dielectric layer consisting of an ion with a valency different from 5 in a concentration variable across the thickness of the layer. The nature of the additive is selected according to the characteristic to be improved.

Solid electrolytic capacitor

Improved anodes for solid electrolytic capacitors are produced by introducing in the anode body made of a film forming sintered metal powder one of the following additives : tungsten, molybdenum, vanadium and hafnium, at the most suitable step of the manufacturing process previous to sintering under one of the following forms : pure metal, oxide, sulphide. In a preferred embodiment the additive is introduced in the binder used for pelletizing. In another embodiment the additive is introduced by dipping the presintered anodes in a solution containing said additive.

Production of improved anodes for solid electrolyte capacitors

Improved sintered anodes for solid electrolytic capacitors are produced from a mixture of at least two powders the first being of pure film forming metal and the second of a film forming metal with addition of at least one of the elements : nitrogen, tungsten, molybdenum, vanadium and hafnium. The relative concentration of the added element is between 100 and 20,000 ppm. by weight.

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Paris, France

Balint Escher