Power Electronics

Wraparound Chip Resistors for High-Temperature Applications

Vishay Precision Group, Inc. announced that its Vishay Foil Resistors brand (VFR) has released a new series of ultra-high-precision Bulk Metal® Z1-Foil wraparound, surface-mount chip resistors for high-temperature applications up to +200°C. The FRST devices provide a high-temperature load-life stability of 0.02% ∆R after 2,000 hours of rated power at 175°C, 0.015% typical ∆R after 1,000 hours at 85°C/85% relative humidity, and low TCR of ±2.5 ppm/°C from -55°C to +175°C, 25°C ref. Rated power varies depending upon the chip size.

VFR's Bulk Metal Foil technology's principal advantage has long been its insensitivity to temperature changes, a benefit that has been further improved in VFR's next-generation Z1-Foil technology. The FRST series incorporates Z1-Foil technology to extend these critical performance features to higher-temperature and higher-humidity environments while maintaining the same low TCR. Each device's solid monolithic alloy element is matched to the substrate, forming a single interdependent structure with balanced temperature characteristics for an unusually low and predictable TCR over a wide range from -55°C to more than +175°C. Resistance patterns are photo-etched to permit trimming of resistance values to very tight tolerances of ±0.01%.

The resistors feature exceptional load-life stability to ±0.0025% at +70°C for 2,000 hours at rated power and can withstand electrostatic discharges at least to 25 kV without degradation. Offered in six chip sizes from 0603 to 2512, the FRST series features 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.

FRST devices offer a power coefficient (∆R due to self-heating) down to 5 ppm at rated power within ±25°C of room temperature, and power ratings for the devices range from 750 mW at +70°C to 150 mW at +175°C. 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 RoHS-compliant devices offer a non-inductive (<0.08 µH), non-capacitive design and are available in matched sets upon request.

The FRST series is optimized for a wide variety of industrial, military, aerospace, medical, down-hole, oil well, and automotive applications requiring resistors to have a minimal drift from their initial values when operating above +175°C and in humid environments. 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 environmental 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.

Samples and production quantities of the FRST series are available now, with lead times of five days for samples and eight weeks for standard orders. Pricing for U.S. delivery starts at $5.39.

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