Tantalum capacitors are a class of electrolytic capacitors widely used in industries like communications, aerospace, submarine cables, military, electronics, civil appliances, etc. Tantalum capacitors are mainly made of tantalum metal which functions as its anode and is covered by a layer of metal oxide which serves as its dielectric material and is surrounded by a conductive cathode.
According to the different structures of an anode, the tantalum capacitors can be divided into foil tantalum capacitors, and tantalum powder sintered tantalum capacitors. The sintered tantalum can then further be divided into tantalum capacitors with solid electrolytes and non-solid electrolytes, which primarily depend upon their different working electrolytes. There is more market demand for solid tantalum electrolytic capacitors among all these types.
Construction of Tantalum Capacitors
Like the rest of the electrolytic capacitors, Tantalum capacitors consist of an anode, a cathode, and an electrolyte. The anode is separated from the cathode, so only a little DC may leak and flow through the capacitor. Pure tantalum metal is used in making the anode. The metal is then grounded into a powder form, and then it is arranged in a palate at high temperatures. This results in a porous anode that has a high surface area. A high surface area is an indication of increased capacitance values.
After this, the anode is covered with a layer of dielectric material called metal oxide. This process is commonly known as anodization. This step needs to be carefully handled to ensure correct capacitances and reduce tolerances, and as the oxide grows, it determines the dielectric thickness.
To add electrolyte to the solid tantalum capacitor, pyrolysis is used. The solid tantalum capacitors are then dipped into a special kind of solution and then baked in an oven so that they can create a manganese dioxide coat. This process will be repeated until a thick coating is formed on the outer and inner surfaces of the pellet. In the final step, the pellet of the solid tantalum capacitor is dipped into silver and graphite, which creates a good cathode connection. In contrast to solid tantalum capacitors, the wet tantalum capacitors utilize a liquid electrolyte. The cathode in the wet tantalum capacitor is served by the enclosure and the electrolyte together.
Applications of Tantalum Capacitors
Tantalum capacitors have a high capacity, low leakage current, long-term reliability, and stability, due to which they are used for many applications.
- Tantalum capacitors are used in sample and hold circuits that depend upon the low leakage current to achieve long hold durations.
- They also effectively perform power supply filtering for computer motherboards and mobile phones because these capacitors are small and have long-term stability, most commonly in SMT form.
- With stricter tolerances and a broader temperature range, you can also find tantalum capacitors in military specifications versions.
- Tantalum capacitors are very popular in military applications because they do not dry out or change capacitances over time; therefore, they are more effective.
- Tantalum capacitors are also widely used in medical electronics because of their high levels of stability.
- Audio amplifiers utilize tantalum capacitors where stability is a crucial factor.
When to Use a Tantalum Capacitor?
A tantalum capacitor is much needed in applications where maximum capacitance and narrow space like decoupling next to a microchip and excellent stability are required over temperatures. When you are aware of their properties so they can be appropriately designed and not lead to a system failure.
