Electrolytic capacitors and film capacitors Technologies and evolution

Capacitors are passive components used in all areas of electronics: telecommunications, computing, automotive, space, consumer electronics, etc. They enable the transient storage of an electrical charge between two electrodes separated by an insulating material called a dielectric. Their electrical performance depends on the nature of the dielectric and the electrode-insulator-electrode structure. Excluding emerging technologies, these considerations enable us to classify them into three main families:

• ceramic capacitors ;

• electrochemical capacitors ;

• film capacitors.

The choice of capacitor type depends on the constraints imposed by the intended application: not only is the value of the capacitance required taken into account, but also the behavior of the dielectric as a function of temperature, frequency, amplitude of the signal to be processed, polarization voltage, climatic constraints, etc. Finally, implementation and transfer technologies, as well as reliability and cost constraints, must be considered. Last but not least, implementation and transfer technologies, as well as reliability and cost constraints, must be taken into account.

The technological evolution of capacitors is linked to the twin demands of miniaturization and lower costs. In telecommunications and consumer applications, this trend has led to the exclusive use of surface-mounting techniques for components on printed circuit boards. As a result, capacitors designed for mass-market electronic circuits, which cannot keep up with this trend for economic or technical reasons, have disappeared or are set to disappear, while new technologies (such as "silicon" capacitors) are being developed.

Furthermore, the trend in electronics towards greater miniaturization means that there is a constant demand for ever-smaller components. As a result, these components naturally require higher volumetric heating. Current trends in professional power electronics for aeronautics, space, oil research and others, accentuate the need for capacitors capable of operating at high temperatures, which could be between 150°C and 200°C, or even higher. In the face of such constraints, new specific, high-performance and reliable materials and technological approaches are emerging.

This article presents electrochemical and film capacitors, while ceramic capacitors are the subject of