Breaking Away from the Tantalum Trap
In today’s market there is an increasing need for stable voltage in countless applications but especially for the computers and digital equipment that use powerful microprocessors, such as CPU, ASIC and LSI. These processors deal with massive volumes of data and require large scale integration and faster clock speeds which call for more load current and in turn, lower operating voltages. Additionally, the market is seeing current ramp at the start of LSI operations (di/dt) becoming faster and faster.
The components industry is under pressure to provide solutions that manage the risk of unstable power. Various capacitor technologies are employed in voltage regulators such as tantalum capacitors, aluminum capacitors, and for low ESR (equivalent series resistance), polymer capacitors and multi-layer ceramic capacitors (MLCC).
The Unstable Supply of Rare Tantalum Ore
The first technology mentioned, Tantalum capacitors, uses a rare metal (tantalum) as its primary material and because of its scarcity it suffers from cyclical shortages. Our industry has seen such shortages in 1997, 2000, and 2008. To solve this cyclical shortage of material, other types of capacitors found their way into applications which typically used Tantalums, for instance, MLCC’s replaced the smaller capacitance tantalums, larger capacitance tantalums were replaced by aluminum capacitors and, in the low ESR arena, polymer aluminum capacitors are regarded as an excellent substitute. Looking ahead it appears that another shortage is coming due to the instable supply of tantalum ore, according to industry sources. This will inevitably lead to a shortage in supply and an increase in the cost of tantalum capacitors.
Conflict Minerals
"The Wall Street Reform and Consumer Protection Act," which became effective on July 21, 2010 discourages the use of conflict minerals including gold (Au), tantalum (Ta), tungsten (W) and tin (Sn). These metals were produced from the mines in the Eastern region of the Democratic Republic of Congo (DRC) and surrounding countries which are controlled by non-government military groups, or unlawful military factions. Illegal mining profits by local military groups in the Eastern DRC leads to human rights abuses, environmental travesties, and theft from the Country’s citizens. This is another consideration for increased on tantalum capacitors.
Breaking Away from Tantalum Capacitors
Tantalum capacitors have a strong foothold in the North American market, especially when compared to their use throughout the rest of the world. In the past, tantalums were chosen because there was a lack of other options available and the industry’s complacency despite its notable weakness of mandatory voltage derating (in order to prevent failures). With the potential shortage and inevitable price increase; now is the time to contemplate how to break away from the tantalum trap. With an abundant supply of material, Aluminum Capacitors are one viable option; with products that include aluminum polymer capacitors and surface mount aluminum capacitors. Polymer aluminum capacitors use polymer as a solid electrolyte. They boast ESR values as low as 3mohm (@100KHz). This is because polymer offers 10,000 times better conductivity than the electrolyte found in wet aluminum technology, and 1,000 times more than MnO2 used in tantalum technology. Polymer Aluminum Capacitors have available capacitance ranges from a few microfarads to 560uF. In addition, they also offer stable capacitance against frequency and temperature changes.
Surface Mount Aluminum Capacitors cover an extensive CV range from 6.3V to 450V / 0.1uF to 6800uF, and are available for general purpose to low impedance. State-of-the-art SMT aluminum capacitors use high-conductivity electrolyte, achieving 60mohm (100KHz) ESR which surpasses regular tantalums. If we can rethink the entrenched use of tantalum capacitors and view capacitor selection from a new perspective, we will be able to achieve better designs and reduce costs at the same time.
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