■Characteristics of aluminum electrolytic capacitors

Wet type aluminum electrolytic capacitors are widely used because they offer high capacitance and are inexpensive. However, compared to other capacitor types, they have the following characteristics which need to be carefully considered when designing applications.

● Limited service life

Drying (evaporation) of the electrolyte causes a drop in capacitance, also known as capacitance loss. The service life is commonly considered to be about 10 years. Electrolyte leaks can also cause a drop in circuit insulation and other problems.

Arrhenius law (doubling for every 10ºC)

The degree of loss in electrolyte is related to the temperature, roughly in accordance with the so-called Arrhenius law or equation for the temperature dependent speed of chemical reactions. This states that for every rise in usage temperature by 10 degrees centigrade, the service life is shortened to one half, and conversely it is doubled for every 10 degree drop.