- SMD aluminum electrolytic capacitors
- Radial aluminum electrolytic capacitors
- Snap-in aluminum electrolytic capacitors
- Aluminum electrolytic capacitors with screwed connection
An electrolytic capacitor also primarily consists of two opposing metal surfaces. In this case, the surfaces usually comprise ultra-fine aluminum films. The electrolyte or polymer is found between the two metal surfaces. One of the films is coated in an insulating (oxide) layer to prevent a short circuit in the capacitor. The oxidation on the surface creates a very rough structure, thus greatly increasing the surface area. Combined with the electrolyte or polymer, this produces very high capacities.
Electrolyte capacitors can be manufactured to provide high operating voltages (up to 700 V) with high capacities. The capacitor's service life is determined by the liquid electrolyte. The electrolyte will dry out over time and the capacity will decrease, internal resistance will increase and the capacitor will age. This process speeds up substantially if the capacitor's (ambient) temperature increases. If short circuits occur in the capacitor during operation, the conductive electrolyte evaporates and insulates the damaged point, producing a self-healing effect. This means that the capacitor loses a little capacity, but remains highly resistant even after a fault.
A polymer is added to the electrolyte in polymer capacitors. This reduces the internal resistance substantially, thus increasing the capacitor's current carrying capacity. The electrolyte contains hardly any liquid due to the high proportion of polymer, so it may not dry out. The capacitor temperature scarcely has any bearing on aging in these capacitors, meaning life expectancy is considerably higher than in other capacitors. The potential operating voltage decreases (max. 35 V) due to the added polymer. Permanent short circuits may occur in the capacitor if there are any faults.
What are known as hybrid capacitors combine the best of both worlds. They are available for operating voltages up to 63 V, have a very low internal resistance, a very long life expectancy and become highly resistant in the event of a fault.