Capacitors Blog

Suntan Technology Company Limited
---All Kinds of Capacitors

Aluminum electrolytic capacitors are comprised of anode and cathode plates separated by an absorbent spacer. As shown in Figure below, metal tabs are attached to the anode and cathode plates, and the assembly is wound into a cylindrical section. The tabs are welded to aluminum terminals installed in a header (top). The section-header assembly is immersed in a bath of hot capacitor electrolyte (significantly different from the formation process electrolyte). In what is called the impregnation process, a vacuum is applied to the electrolyte and sections, causing electrolyte to be drawn into the sections, thoroughly wetting the sections. The sections are placed in aluminum cans, and the headers are sealed to the cans. The capacitor units are slowly brought up to maximum rated voltage at maximum rated temperature during the aging process. The aging process grows oxide on areas on the anode foil which have an insufficient oxide barrier, such as slit edges and places which have been cracked during the winding operation. Inspections and tests occur at several stages of the production process.

For more details please check : http://www.capacitors.hk/Aluminum-Electrolytic-Capacitors/

Suntan Technology Company Limited
---All kinds of Capacitors

Aluminum is used for the electrodes by using a thin oxidization membrane.

Large values of capacitance can be obtained in comparison with the size of the capacitor, because the dielectric used is very thin.

The most important characteristic of electrolytic capacitors is that they have polarity. They have a positive and a negative electrode.[Polarised] This means that it is very important which way round they are connected. If the capacitor is subjected to voltage exceeding its working voltage, or if it is connected with incorrect polarity, it may burst. It is extremely dangerous, because it can quite literally explode. Make absolutely no mistakes.

Generally, in the circuit diagram, the positive side is indicated by a "+" (plus) symbol.

Electrolytic capacitors range in value from about 1µF to thousands of µF. Mainly this type of capacitor is used as a ripple filter in a power supply circuit, or as a filter to bypass low frequency signals, etc. Because this type of capacitor is comparatively similar to the nature of a coil in construction, it isn't possible to use for high-frequency circuits. (It is said that the frequency characteristic is bad.)

The photograph on the left is an example of the different values of electrolytic capacitors in which the capacitance and voltage differ.

From the left to right:

• 1µF (50V) [diameter 5 mm, high 12 mm]
• 47µF (16V) [diameter 6 mm, high 5 mm]
• 100µF (25V) [diameter 5 mm, high 11 mm]
• 220µF (25V) [diameter 8 mm, high 12 mm]
• 1000µF (50V) [diameter 18 mm, high 40 mm]

The size of the capacitor sometimes depends on the manufacturer. So the sizes shown here on this page are just examples.

In the photograph to the right, the mark indicating the negative lead of the component can be seen. You need to pay attention to the polarity indication so as not to make a mistake when you assemble the circuit.

Suntan Technology Company Limited
---All Kinds of Capacitors

Aluminum electrolytic capacitor maker Lelon Electronics has seen extra orders from China appliance makers due to the China government's program to promote sales of home appliances in rural areas. The extra orders have covered Lelon's reduced orders from the US and Europe, the company said.

The price of aluminum electrolytic capacitors has been stable since August 2008, while the price of aluminum foil continues to drop, lowering Lelon's cost pressure. However, order visibility for aluminum electrolytic capacitors is still low, the company noted.

Lelon has entered the wind power market with its large-size capacitors, and plans to apply the product to other applications. The company has already shipped a small volume of large-size capacitors to a motorcycle maker and expects to expand into the automotive segment.