Aluminum polymer capacitors have significant advantages over ordinary (wet) aluminum electrolytic capacitors. Aluminum polymer capacitors last longer because there is no failure due to electrolyte drying. Solid electrolytes do not dry out as ordinary liquid electrolytes do. With no pressure build up inside the capacitor, they have a much safer failure mode (evaporation of electrolytes in ordinary electrolytic capacitors can lead to explosion). They have a higher maximum working temperature. Aluminum polymer capacitors have lower equivalent series resistance (ESR), which means that for the same working conditions (i.e. current level) they operate colder.

 

Disadvantages of aluminum polymer capacitors compared to ordinary aluminum electrolytic capacitors are higher cost, lower working voltage, and lower capacitance. They can’t always be used in place of ordinary aluminum electrolytic capacitors.

 

Aluminum polymer capacitors are mainly utilized where large current ripple exists. One example is switch mode power supplies that are used for supplying power in modern computers. They may be found on high-quality motherboards.

 

Aluminum polymer capacitors implement the basic three-layer capacitor structure, conductor–dielectric–conductor, in the form of the following: aluminum–aluminum oxide–polymer. Because they utilize electrolytes (the conductive polymer is solid, non-liquid, electrolyte) they are a subgroup of the electrolytic capacitors. They are polarized so they must be connected to positive voltage only. Application of negative voltage leads to the failure of the capacitor.