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MALVERN, PENNSYLVANIA — Nov. 21, 2011 — Vishay Precision Group, Inc. (NYSE: VPG) today announced that its Vishay Foil Resistors division (VFR) has introduced a new series of ultra-high-precision Bulk Metal® Z1-Foil hybrid chip resistors designed for demanding high-temperature applications to +240°C. The devices are designed for hybrid circuits with aluminum wire bonding technology.
The HTHA series is based on VFR’s next-generation Z1-Foil technology, which provides an order of magnitude reduction in the Bulk Metal Foil element’s sensitivity to temperature changes – both external and internal – while providing long-term stability in high-temperature environments. HTHA devices offer TCR of ±1 ppm/°C from -55°C to +125°C and ±2.5 ppm/°C from -55°C to +220°C, +25°C ref. The resistors feature exceptional load-life stability to ±0.05% at +220°C for 2,000 hours at working power, long-term stability to ±0.05% at +240°C for 2,000 hours (no power), and tight tolerances to ±0.02%. The devices are capable of withstanding electrostatic discharges at least to 25 kV without degradation.
The HTHA series is offered in six case sizes ranging from 0603 to 2512 and features working power to 150 mW at +220°C. The devices provide a wide resistance range from 5 Ω to 125 kΩ, with any resistance value within this range available at any tolerance with no additional cost or lead time effect. The resistors feature a rise time of 1.0 ns, with effectively no ringing, a thermal stabilization time of < 1 s (nominal value achieved within 10 ppm of steady state value), current noise of 0.010 µVrms per volt of applied voltage (< -40 dB), and a voltage coefficient of < 0.1 ppm/V.
The HTHA series is optimized for a wide variety of high-temperature applications, including geothermal measuring equipment, turbine engine control, and environmental test chambers in military, industrial, automotive, and down-hole drilling systems. Many analog circuits in these applications require passive components such as resistors to have a minimal drift from their initial values when operating above +175°C and in humid environments. In high-temperature applications, the most important factor is the end-of-life tolerance, and to a lesser extent, the initial tolerance. HTHA resistors provide stabilities well under the maximum allowable drift required by customers’ specifications through thousands of hours of operation under harsh conditions.
The Z1-Foil technology allows VFR to produce customer-oriented products designed to satisfy unique and specific technical requirements. In addition to the special chip stabilization under extreme environment conditions in the production line, additional specially oriented post manufacturing operations (PMO) are offered for high-temperature applications that require an even higher degree of reliability and stability.
“Resistors are the passive building blocks of an electrical circuit. They may be used for dropping the voltage, buffering the surge when the circuit is turned on, providing feedback in a monitoring loop, sensing current flow, and more,” said Yuval Hernik, senior director of application engineering for Vishay Foil Resistors. “When their application requires stability over time and load, initial accuracy, minimal change with temperatures higher than +200°C, resistance to moisture, and a number of other characteristics, only the new generation of VFR resistors has the attributes required.
“Compared to Bulk Metal Foil, thick and thin film resistor elements are produced with a non-controllable material,” Hernik added. “Heat or mechanical stresses on the resistive element cause the particles forming the film to expand. However, after these stresses are alleviated, the particles in the film don’t return to their exact original position, which reduces their overall stability. For high-temperature applications where stability is a main concern, Vishay Foil resistors offer the best resilience against time at elevated temperature.”
Samples and production quantities of the HTHA series are available now, with lead times of five weeks for samples, and eight weeks for standard orders.
About Vishay Foil Resistors
Vishay Foil Resistors is a division of Vishay Precision Group, producing the most precise and stable resistors available. The portfolio comprises products in a variety of resistor and package configurations to meet the needs of a wide range of applications: discrete resistors and resistor networks in surface mount and through-hole (fixed-lead) configurations; customized chip resistor networks; precision trimming potentiometers; and discrete chips for use in hybrid circuits. The foil resistors and current sensors are used in applications requiring a high degree of precision and stability, such as in medical testing equipment, high performance audio equipment, precision measuring instruments, aerospace, and military applications.
About Vishay Precision Group
Vishay Precision Group (VPG) produces sensors based on precision resistive foil technology, and sensor-based systems. It provides vertically integrated products and solutions for multiple growing markets in the areas of stress, force, weight, pressure and current measurements. As a spin-off from Vishay Intertechnology, VPG’s decades-long track record encompasses innovations in precision foil resistors, current sensors, and strain gages, which have served as a foundation for VPG’s more recent expansion into strain gage instrumentation, load cells and transducers, weighing modules and complete systems for process control and on-board weighing. Vishay Precision Group may be found on the Internet at www.vishaypg.com.