Image credit: RS Components | EEWeb
Tantalum capacitors are constructed using tantalum for at least the anode material.
Capacitors in general consist of two polarized conductors separated by an insulating dielectric material. When the component is connected to a voltage source, its negative conductor becomes saturated with electrons, therefore charging the capacitor and allowing it to store electricity.
Tantalum capacitors rely on a unique characteristic of tantalum: the element tends to naturally form a non-conductive oxide surface layer which functions as the capacitor's dielectric. Because this layer is thinner and lighter than dielectric materials such as paper and plastic, tantalum capacitors can be manufactured as very small components with excellent capacitance to size ratios. Solid tantalum capacitors are typically comprised of a pellet-shaped anode, formed from tantalum powder, and a cathode constructed of manganese dioxide.
The image below shows a cutaway view of a solid tantalum capacitor. Note that the coatings around the tantalum core (manganese dioxide cathode, carbon, silver paint) are very thin.
Image credit: ScienceDirect
Wet tantalum (electrolytic) capacitors contrast with the solid variety, in that they feature a semi-liquid electrolyte paste as a second electrode; these devices are similar to aluminum electrolytic capacitors, which have solid aluminum anodes. Electrolytic capacitors in general are capable of very high capacitance values, but are generally unsuited to AC power applications due to their necessary polarity, but they are very frequently used in DC power supplies. When compared to aluminum electrolytic devices, tantalum capacitors feature longer shelf life, improved temperature resistance, and higher capacitance values, but are also more easily damaged by constant voltages as low as 1.5 V. The diagram below shows a cutaway view of a wet tantalum capacitor.
Image credit: Basic Electricity and Electronics
For general information about capacitors, including construction, applications, capacitance rating, and general specifications, please visit the Capacitors Selection Guide.
Tantalum capacitors are generally available in two different forms: leaded (or through-hole) and surface mount (SMT).
Leaded capacitors feature long wire leads which are soldered onto a PCB in order to make an electrical connection. These devices use through-hole technology (THT), which allows for strong mechanical connections. THT capacitors must be relatively large by necessity and have generally been replaced by surface mount products.
Surface mount (or chip) capacitors are mounted directly to the top of a PCB using very short leads, flat contacts, or other termination types. SMT devices are smaller and cheaper to manufacture than their older THT counterparts.
A THT (left) and SMT capacitor. Image credit: GlobalSpec | West Florida Components
Tantalum capacitors may be manufactured to one or more various standards, including:
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Aluminum Electrolytic Capacitors
Aluminum electrolytic capacitors use an electrolytic process to form the dielectric. Wet electrolytic capacitors have a moist electrolyte. Dry or solid electrolytic capacitors do not.
Capacitors are electronic components used for storing charge and energy. In their simplest form, capacitors consist of two conducting plates separated by an insulating material called the dielectric.
Ceramic capacitors have a dielectric made of ceramic materials.
Chip capacitors or surface mount capacitors do not have leads.
Film capacitors are insulated with polyester, polycarbonate, polypropylene, polystyrene, or other dielectric materials.
High Voltage Capacitors
High voltage capacitors are used for storing charge and energy in high voltage applications.
Ultracapacitors store charges (energy) by physically separating positive and negative charges (unlike batteries which do so chemically). Very high power densities can be achieved by this method.