SU1101913A2 - Process for manufacturing bulk-porous anodes - Google Patents

Abstract

WAY OF MANUFACTURING OF VOLUME-POROUS ANODES on the author. St. No. 883988, characterized in that, in order to increase the output of usable capacitors with a minimum deviation of the capacitance from nominal and increase productivity, before applying a stepped voltage pulse, the powder is pressed under a pressure of 1-10 MPa, and then applied after a stepped pulse, cooling is performed anodes by filling the chamber to form anodes with nitrogen gas.

Description

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The invention relates to electronic engineering and can be used in the manufacture of electrolytic capacitors.

According to the main author. St. No. 883988 discloses a method for manufacturing volume-porous anodes of electrolytic capacitors by applying an electric field to a valve metal powder. The electric field is applied by applying a voltage step pulse consisting of low voltage and high voltage parts, the amplitude and duration of which are respectively referred to as (10-40): and 1: (20-50) and are determined depending on dimensions and porosity of anodes 1.

The disadvantages are the low percentage of yield of capacitors with a minimum deviation of the capacitance from the nominal and low productivity of the method.

The purpose of the invention is to increase the yield of usable capacitors with a minimum deviation of the capacitance from the nominal and increase productivity.

This goal is achieved in that according to the method of manufacturing volumetric-porous anodes of electrolytic capacitors, which includes applying an electric field through the application of a stepped voltage pulse consisting of low voltage and high voltage parts, the amplitude and duration of which are respectively (10-40): 1 and 1 : (20-50) and are determined depending on the dimensions and porosity of the anodes, before applying a stepped voltage pulse, pressing the powder under pressure of 1-10 MPa, and then after applying a stepped pulse, the anodes are cooled by filling the chamber to form the anodes with nitrogen gas.

Pressing the impulse before applying a voltage pulse prevents the impulse from discharging from the metering volume, which reduces the capacitance variation of the finished capacitors, and also significantly reduces the amplitude of the high-voltage part of the voltage impulse due to local thinning under the mechanical load of the natural oxide oxide film between contacting poroshes. . The pressing pressure is chosen in the range of 1-10 MPa. The lower limit of this pressure (1 MPa) corresponds to the onset of deformation of mechanically compacted metal powders; at lower pressure values, the amplitude of the high voltage part of the voltage pulse cannot be reduced. The upper limit of the pressing pressure (10 MPa) corresponds to the beginning of the metal fluidity, which leads to a decrease in the porosity of the anodes and, consequently.

reducing the specific charge of capacitors.

The admission of nitrogen gas into the working chamber at the stage of cooling the anodes after sintering contributes to the reduction of this

stages due to increased heat transfer between the anodes, the form and the environment. In addition, this results in partial dissolution of nitrogen in the surface layer of the anode. Take certain positions in

the crystal lattice of the metal anode, nitrogen prevents the formation of an oxide and suboxide phases in the subsurface layer of the anode during its interaction with oxygen, which cause an increase in leakage current during the manufacture and operation of capacitors. Due to this, the maximum permissible temperature at which the anodes can be extracted into the air is increased, i.e. the cooling time is shortened and, consequently, the production of porous anodes is intensified.

Example. A niobium powder with a particle size of 20–40 µm is poured into the ceramic form of annealed pyrophyllite with two copper punches. A tantalum lead is then inserted into one of the punches.

5 in the form of a wire with a diameter of 0.5 mm and pressing is carried out at a pressure of 1.5-10 MPa. After that, a voltage pulse of a duration of 0.2 s is applied between the copper punches, consisting of a high-voltage section of a duration of 0.2 s and an amplitude

0 120 V and low voltage; with an amplitude of 10 V. Cooling the sintered anodes and form is produced by blowing the working chamber with nitrogen gas for 3 seconds, after which the anodes are removed from the chamber to form and fall into molds

5 new powder.

The table shows the average values of the percent yield of capacitors with a minimum (10%) deviation of the capacitance from the nominal, the specific charge of the condensers and the amplitude of the high-voltage portion of the voltage pulse with various methods of manufacture. The remaining parameters of the capacitors in the proposed and known methods remain unchanged, the weight of the anodes is 0.3 g, the operating voltage is 20 V.

5 The results in the table show that the introduction of the powder pressing operation before applying voltage in the proposed method will allow increasing the yield of capacitors with a minimum deviation of capacity from the current terminal and improve safety conditions by reducing the amplitude of the high-voltage portion of the voltage pulse. Cooling the anodes and the mold in a nitrogen atmosphere allows for a continuous anode fabrication process, at which the time to fabricate one anode is 6 seconds, whereas in a known method requiring the use of storage devices

for cooling the anodes, the average time to make one anode is 30 seconds. Thus, the analysis of the results of the manufacture of volume-porous anodes by the proposed method makes it possible to double the yield of capacitors with a minimum deviation of the capacitance from the nominal one and increase labor productivity fivefold due to a corresponding intensification of production.

The yield,% 23

Specific charge, µC / g

1300

Amplitude of the high-voltage part of the pulse, V 200

45 44 1360 1260

120

140

Claims (1)

METHOD FOR PRODUCING VOLUME-POROUS ANODES by ed. St. No. 883988, characterized in that, in order to increase the yield of suitable capacitors with a minimum deviation of the capacitance from the nominal one and increase productivity, before applying a step voltage pulse, the powder is pressed under pressure of 1-10 MPa, and then after application of a step pulse, the anodes are cooled by filling chambers for forming anodes with nitrogen gas.