June 29, 2023

How Kendeil Capacitors are built

It is within the framework of a privileged partnership that Kendeil’s capacitor products are marketed directly by Cougar.

Specialized in the design and manufacture of capacitors, Kendeil offers a wide range of new electrolytic capacitors.

We can note the following characteristics of electrolytic capacitors:

These aluminum electrolytic capacitors meet the detailed specifications of IEC 68-1.

They combine a low ESR with a compact screw capacitor size. The heat generation is also perfectly managed, with a proportionality between the temperature rise and the size of ESR used.

Good component selection was also necessary so that system cooling was less demanding, and capacitors could be deployed, worry about temperature. This is also a real plus, to avoid premature equipment failure.

Also, these capacitors are designed for professional and industrial applications. Their use is therefore foreseen for high ripple current converters in the power electronics sector, or for motor drives in the automotive or industrial sector.

Finally, the electrolytic capacitors are surge-proof, since they are placed in an aluminum case with an insulation sleeve and a safety vent integrated in a reinforced cover. The assembly is also very fast, with a system of clips or dowels.

As for the composition:

They are composed of an aluminum foil anode with dielectric oxidation on its surface, with semiconducting characteristics and another aluminum foil cathode.

 There is also a layer of electrolyte-impregnated paper placed between the anode and cathode to prevent short circuits.

 Both aluminum foils were etched to obtain active surfaces, thus increasing their effective area.

Aluminum tabs are then connected to both to act as terminals.

When used, the impregnated section is then enclosed in a suitable housing and sealed with a bridge. The combination of a thin dielectric and a large surface area creates capacitors with exceptionally high capacitance per volume.

The entire manufacturing process for Kendeil electrolytic capacitors can be reasonably divided into several phases:

– Etching / Forming

The electrochemical etching process is used to dissolve the metal and increase the surface area of the foil in the form of a dense network of microscopes.

This process consists of continuously passing an aluminum foil through a chloride solution, applying an alternating, continuous or alternating/continuous voltage between the etching solution and the aluminum foil.

The objective is to obtain the maximum capacity for a given electrode surface.

Forming is the process during which a thin layer of aluminum oxide is formed on the surface of the engraved aluminum sheet.

– Winding

This process corresponds to the assembly of the capacitors. Each capacitor contains two sheets, the positive sheet is called ANODE and the negative sheet is called CATHODE. The two sheets, as well as a separator paper, are wound in a cylinder.

The paper has several functions, one is to prevent the anode and cathode foils from contacting each other and shorting out, the other is to serve as a support for the foils.

Also, another function, is to serve as a container for the electrolyte; indeed, during the life of the capacitor, the liquid electrolyte is consumed by the reforming reactions.

Finally, the process is concluded by the fixation of 2 aluminum tabs on the anode and cathode.

The winding element is obtained.

Here is the diagram of the product at the time of winding:

Widing process for capacitors (assembly)

– Impregnation

The impregnation consists in immersing the winding element in the electrolyte either by a vacuum/pressure cycle with or without applied heat, or by simple absorption.

The electrolyte contains a solvent such as ethylene or glycol, but also a solute such as ammonium borate, which allows the capacitor to self-heal by forming more oxide in case the dielectric film is damaged.

Also, the choice of electrolytes, allows in some cases to modify the operating temperature range or to modify the frequency or to extend the life and shelf life. The characteristics can be improved significantly.

– Sealing

Following the impregnation phase, the element is sealed in an aluminum box. The sealing bridge materials can be rubber/bakelite or phenolic plastic.

– Aging

It consists of the application of a voltage higher than the nominal voltage at very high temperature. This is done to reform or repair any oxide film that may have been damaged during the etching, forming, winding and assembly processes, thereby reducing the leakage current to an acceptable low level.

– Production Inspections

Finally, product inspection is the last process in manufacturing.

After aging, the capacitors are 100% tested. All electrical requirements are verified using automated test equipment and any rejects are eliminated.

Capacitors are also visually inspected, and only those that pass both tests are accepted for packaging.

FOR MORE INFORMATION

Contact COUGAR ELECTRONICS for advice and availability of your Kendeil electrolytic capacitors.

OR go directly to the checkout: Kendeil – Cougar Electronics

Other links : BUILDING_AN_ELECTROLYTIC_CAPACITOR.pdf (kendeil.com)Microsoft Word – Newsletter K92 – K93 2022PROPOSTA_C_rev1 (kendeil.com)

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