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MALVERN, PA. — Jan. 24, 2011 —Vishay Precision Group , Inc. (NYSE: VPG) is now offering a wide variety of resistors built on Bulk Metal® Foil technology with new techniques and materials that improve reliability and stability for demanding military, avionics and space applications. These products include the VSMP, VCS1625Z, VCS1625, VCS1610, CSM2512, CSM3637, Z201, S102C, DSMZ and SMNZ.
These new-generation precision resistors are virtually insensitive to destabilizing factors. Their resistive elements are made of a solid alloy that displays the desirable bulk properties of its parent material, thus it is inherently stable, noise-free and immune to ESD to 25 kV and beyond. The resistive element and matched substrate form a single entity with balanced temperature characteristics for an unusually low and predictable TCR over a wide temperature range from -55°C to more than +200°C. Resistance patterns are photo-etched to permit trimming of resistance values to very tight tolerances.
Several factors need to be considered when choosing a resistor for space and military applications, including TCR (ambient temperature), power TCR (self heating), load-life stability, end-of-life tolerance, thermal EMF, thermal stabilization, and ESD. These Bulk Metal Foil resistors, based on a new generation technology and improved production methods starting in December 2010, offer designers the complete set of top performance characteristics to simplify circuitry and lower overall system costs by reducing the number of required parts while assuring a better end product.
Vishay foil resistors feature a long-term load-life stability within 0.005% after 2000 hours and 0.015% after 10,000 hours under full rated power at +70°C. In addition to their low absolute TCR, the devices offer power TCR (“∆R due to self heating”) to ±5 ppm at rated power, tight tolerances from 0.01% -- or even 0.001% (10 ppm) in hermetically sealed packages -- and thermal EMF of 0.05 µV/°C.
Often designers over-specify resistors to allow for an expected tolerance degradation during service. Vishay foil resistors allow designers whose end of life tolerance is 0.05% or less to avoid this approach with cost-effective commercial-off-the-shelf (COTS) devices that provide all the long-term reliability and stability they need for the most demanding applications.
The resistors feature a non-inductive (<0.08 μH), non-capacitive (<0.5 pF) design and are available with a 4-Kelvin connection for increased accuracy. Devices with wraparound terminations and flexible terminations (SMR1DZ and SMR3DZ series) are available to ensure minimal stress transference from the PCB due to differentials in coefficient of thermal expansion (CTE).
While other resistor technologies can take several seconds or even minutes to achieve a steady-state thermal stabilization, Vishay foil resistors feature an almost instantaneous thermal stabilization time, and a nearly immeasurable 1 ns rise time, effectively with no ringing. The devices are offered with a variety of high reliability options that are suitable for military avionics and space applications according to EEE-INST-002, DSCC, EPPL, QPL and MIL-PRF 55342/55182/49465, and are built to handle unconventional environmental conditions with minimal drift.
Offering high ESD immunity, Bulk Metal Foil resistors withstand electrostatic discharges at least to 25 kV for increased reliability. With resistance ratings as low as 1 mΩ, Vishay foil resistors are manufactured with any required resistance value (e.g. 1 kΩ or 1.1234 kΩ) at no additional cost or lead time. The devices have been radiation tested, and include short-time overload and thermal cycling testing as part of the standard production process.
Vishay Foil will be demonstrating its new resistors for aviation, military, and space (AMS) applications at the 15th annual CMSE Conference being held Monday Feb. 7, in Los Angeles, where Kip Reiner and Aaron Ram from the Vishay Foil Resistors applications engineering team will give a technical seminar on “Selecting Precision Resistors To Withstand Unforeseen Stress Factors,” with an emphasis on ESD issues. Complete information about the conference is available at http://www.cti-us.com/cmsemain.htm
Samples and production quantities of the new Bulk Metal Foil resistors for hi-rel applications are available now, with lead times of 5 working days for samples, and 8 weeks for orders with additional tests.
About Vishay Foil Resistors
Vishay Foil Resistors is a division of Vishay Precision Group, producing the most precise and stable type of resistors available. The portfolio comprises products in a variety of resistor configurations and package types to meet the needs of a wide range of applications: discrete resistors and resistor networks in surface mount and through-hole (leaded) 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 and aerospace
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 foil precision 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