Tantalum Caps: Compelling for Designers

Tantalum capacitors tick design engineers' boxes; they offer high values of capacitance within small dimensions, which is a frequent requirement in equipment from smartphones to supercomputers. They are also chosen for their low noise, high temperature capability, self-healing, and excellent stability over time. Manganese dioxide (MnO2 ) types can operate up to 175°C or 200°C, while the alternative organic polymer devices have low internal resistance and a benign failure mode.

Is there nothing else coming close? It can depend on the application, of course, but a designer will specify a tantalum capacitor for compelling technical reasons. If a tantalum capacitor has been specified, a non-tantalum replacement usually will not be satisfactory. In these instances, a well-planned supply chain is critical.

There are a number of threats to the stable supply of tantalum capacitors. These extend throughout the supply chain, as far back as the supply of raw tantalum itself. A large proportion of the world's tantalum is mined in the Democratic Republic of Congo (DRC). New legislation in the US requires companies to verify that any tantalum is sourced from conflict-free mines, and a similar directive is being readied in the European Union (EU). Companies can struggle to comply, since tantalum products may enter the supply chain at several points, either as raw tantalum ore (coltan), or as refined powders, pure tantalum wires, or electrodes.

A closed-pipe supply chain ensures that materials are genuinely conflict free, and helps stabilize supply and prices. Kemet “closes the pipe” by owning the factories that supply tantalum powders, wire and electrodes for capacitor production, and by maintaining close links with a certified conflict-free mine in the DRC that supplies these factories. This control over all materials-production processes also helps accelerate the pace of new-product development, because advanced powder formulas can be created quickly and easily in-house for evaluation.

Kemet automotive polymer capacitors

Kemet automotive polymer capacitors

Currently, the automotive market is demanding rapid progress. High reliability at high operating temperature is a key strength of tantalum technology, but as more and more electronics are crammed on-board today's vehicles, its high volumetric efficiency is being pushed to the limit. In addition, generally intense focus on fuel economy and driving range makes the low internal resistance of polymer tantalum capacitors increasingly attractive.

As far as solid tantalum capacitors are concerned, contamination of the tantalum-based dielectric during manufacturing is known to be the main cause of early device failures. Kemet developed its F-Tech technology to prevent such contamination. In addition, Simulated Breakdown Screening (SBDS) eliminates the excessive stresses imposed by conventional breakdown-voltage screening.

Tantalum capacitors also meet the specific needs of equipment users, without really being acknowledged. The components help considerably towards improving miniaturization, functionality, and reliability to satisfy market demands all the way from industrial and medical to consumer, automotive and aerospace. It may seem insignificant, but that one word – tantalum – means a capacitor that's a different breed.

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