Technical Articles / Whitepapers

Voltage Derating Rules for Solid Tantalum and Niobium Capacitors Written By: Tomáš Zedníček | John Gill Abstract: For many years, whenever people have asked tantalum capacitor manufacturers for general recommendations on using their product, the consensus was “a minimum of 50% voltage derating should be applied”. This rule of thumb has since become the most prevalent design guideline for tantalum technology. This paper revisits this statement and explains, given an understanding of the application, why this is not necessarily the case. With the recent introduction of niobium and niobium oxide capacitor technologies, the derating discussion has been extended to these capacitor families also.

Ultrathin Discrete Capacitors for Emerging Embedded Technology Written By: Radim Uher | Tomas Zednicek Abstract: Passive components can represent as much as 70% of PCB footprint in today’s electronic systems. The development of a suitable technology whereby integrated passive components are embedded into the PCB body has been one of the key trends in downsizing for more than a decade. Latest achievements have allowed the implementation of this ‘embedding technology’ into pre-production and even mass production. The next step requires the involvement of the complete supply chain, including traditional passive component manufacturers. This paper will present the state of the art in the development of ultrathin discrete capacitor technology and discuss the challenges of overcoming mechanical, electrical and thermo-mechanical issues

Thermal Management of Surface Mounted Tantalum Capacitors Written By: Ian Salisbury Abstract: This paper covers thermal management of surface mounted tantalum capacitors, and explores the thermal characteristics and how these are modified by the thermal interconnection substrate. The paper explores the different methods of mounting to reduce the thermal resistance to the PCB, also the affect of the design of connection pads on the PCB to reduce the thermal stress on the capacitor.

Thermal and Electrical Breakdown Versus Reliability of Ta2O5 under Both – Bipolar Biasing Conditions Written By: P. Vašina | T. Zedníček | Z. Sita | J. Sikula | J. Pavelka Abstract: Our investigation of breakdown is mainly oriented to find a basic parameters describing the phenomena as well as its impact on reliability and quality of the final product that is “GOOD” tantalum capacitor. Basically, breakdown can be produced by a number of successive processes: thermal breakdown because of increasing conductance by Joule heating, avalanche and field emission break, an electromechanical collapse due to the attractive forces between electrodes electrochemical deterioration, dendrite formation and so on. Breakdown causes destruction in the insulator and across the electrodes mainly by melting and

Tantalum Capacitors Technology for Extended Operating Temperature Range Written By: T.Zedníček | Z.Sita | S.Pala Abstract: New materials, capable to operate at higher temperatures, new techniques of their processing and new procedures for increasing the stability have been implemented to AVX THJ series to extend the continuous operating temperature up to 175°C while maintaining twice better reliability specification compare to the standard range of tantalum capacitors.

Tantalum and Oxicap® Niobium Oxide Capacitors Deliver Enhanced Reliability, Wide Temperature Range & Low Leakage for Automotive Applications Written By: R. Faltus Abstract: In nowadays modern cars we can find many electronic systems controling engine, gear box, caring for passenger comfort, assuring safety and security, etc. Automotive applications are specific by their harsh electrical and environmental conditions together with requirements for high overall reliability and lifetime. Any electronic part used in such system play important role to assure reliability and functionality. Different capacitor technologies –tantalum, MLCC, NbO, aluminium are available but some of them meet the specific requirements better than others.

Tantalum and Niobium Technology Roadmap Written By: T. Zednicek | B. Vrana | W. A. Millman | J. Gill | Chris Reynolds Abstract: This paper presents an overview of the key features of emerging capacitor technologies – tantalum, niobium metal and niobium oxide in order to give designers a better understanding of the potential applications and to guide their choice of component solutions for their individual requirements. The second part of the paper is targeted to a new type of solid electrolyte capacitor that has been developed based on niobium oxide powder material. Capacitors made from niobium oxide powder offer the designer many interesting features such as significantly reduced ignition failure mode, better load resistance, reduced cost, etc. The paper

TA Capacitors With Conductive Polymer Robust to Lead Free Process Written By: Z. Sita | M. Biler Abstract: Tantalum capacitors with conductive polymer cathodes have found a place in the market as a low ESR component with reduced ignition. Conductive polymer cathodes however, suffer from instability during multiple high temperature thermal treatments such as lead free soldering due to its limited self healing ability and lower thermal and mechanical strength compared with manganese dioxide. This makes capacitors with conductive polymer cathode more sensitive to thermo-mechanical stresses, which appear during soldering and to negative influences of storage condition after removal from the protective packaging prior to soldering. This paper describes methods of improving the robustness of such capacitors with lead free

Storage Capacitor Properties and Their Effect on Energy Harvester Performance Written By: Radovan Faltus | Miroslav Jáně | Tomáš Zedníček Abstract: The development of energy harvesters has quickened up in the last few years mainly due to semiconductor improvements. But power sources for energy harvesters usually exhibit high internal impedance and can therefore only deliver low currents. The most important consideration for harvesting is that the power consumption of the controller circuitry must be less than the energy generated by the power source. Energy harvesters use a storage capacitor slowly charged from power source through the controller and the leakage current of this capacitor is wastes a certain percentage of the generated energy. This paper will evaluate this effects of

SMD Tantalum Capacitors Break Limit of 200degC for Continuous Operation Written By: R. Faltus | T. Zedníček Abstract: Capacitors are one of the key parts of any electronic device and system. The main functions of capacitors include power supply voltage smoothing, supporting energy sources when high current pulse is demanded, blocking a DC voltage in signal pathes, filtering, etc. To assure required functionality of a system we cannot omit capacitors and it is valid for high temperature applications as well. In oil and gas mining industry a high temperature capacitors are needed for DC/DC converter of drilling heads that are subjected to rising ambient temperature with depth. Thus the higher permitted operating temperature of used capacitor and other passive and

Smallest and Lowest Profile Tantalum Capacitors Written By: T. Zednicek | I. Paukert | I. Zednickova Abstract: Tantalum capacitor technology has been recognized for its parametric stability and long term reliability in the most demanding of applications. Unlike some other capacitor technologies, tantalum capacitors do not exhibit significant capacitance change over time and voltage. The other benefit is that due to its mechanical strength it is possible to manufacture flat & thin designs, so why these type of capacitors are the best fit for tasks such as “can you make higher capacitance in the lowest profile? “ The paper provides an overview of such tantalum capacitors suitable for most demanding sub millimeter size and low profile capacitors down to 0201

Selecting Back-Up Capacitors for Modern Solid State Drives Written By: Radovan Faltus Abstract: High speed cache memory greatly improves SSD performance. Providing a power backup for DRAM buffer memory assures no data loss on power switch off or failure, and also improves speed and reaction time after power on.

Ripple Rating of Tantalum Chip Capacitors Written By: R.W. Franklin Abstract: The ripple current and voltage limits of tantalum chip capacitors are discussed and limits are established for reliable operation.

Reverse Voltage Behavior of Solid Tantalum Capacitors Written By: Ian Bishop | John Gill Abstract: This paper is intended to give the design engineer an understanding of the effects of reverse voltage operation on the chemical structure and life reliability of a tantalum capacitor. It also aims to show a circuit design engineer about predicting the life performance of a circuit where a tantalum capacitor is subjected to negative voltages.

Reliability Management of Tantalum Capacitors Written By: Chris Reynolds Abstract: Tantalum capacitors can achieve high reliability in steady state applications. Tantalum capacitors have highly stable capacitance and frequency dependent characteristics. Short circuits are a low level, but not negligible, failure mode. Because of this, reliability management of tantalum chips means the effective control of the S/C failure mode, not least because this mode cannot be designed around by use of redundancy circuits, etc.

Reaching the Highest Reliability for Tantalum Capacitors Written By: James Bates | Marc Beaulieu | Michael Miller | Joseph Paulus Abstract: Weibull reliability assessment has been used for characterization of tantalum capacitors for many decades driven by MIL standards. Over time major improvements have been made in process, material, testing, equipment and other process control. Is Weibull still the best fit for today’s technology and Hi-Rel applications? A new approach is needed since the current Weibull grading to assure reliability has deficiencies, in particular, the need for early life failures and the potentially damaging application of excessive voltage during the burn-in in an effort to maximize the Weibull acceleration factor. This paper will discuss modifications to the existing burn-in process,