Bulk Metal Z-Foil Reliability Resistors from Vishay

28th January 2009

Vishay

ES Admin

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Vishay has announced that it has extended the resistance tolerance of the RNC90Z family of military-established, Bulk Metal Z-Foil reliability resistors down to ±0.005%. As R level established reliability resistors, RNC90Z devices are military-qualified to MIL PRF 55182/9, the standard for military and aerospace applications requiring long-term stability. The resistors' ability to retain their initial value through temperature change, load application, frequency shift, and short-time overload is unmatched in the industry. Designers can expect the RNC90Z devices to display parts-per-million changes in service, as opposed to percentage changes that occur with thick and thin film resistors.

The enhanced devices offer a broad resistance range of 30.1 Ω to 121 kΩ, very low TCR values of ±0.2 ppm/°C over an extended temperature range of 55°C to +175°C, and a load-life stability of ±0.005% for 2000 hours at +125°C. Vishay Foil resistors are not restricted to standard values, and Vishay can supply as required values (e.g., 100 kΩ vs. 100.123 kΩ) at no extra cost or delivery time. The resistors feature a power rating of 0.6 W at +70°C and 0.3 W at +125°C, with a maximum working voltage of 300 V. Each device measures 0.105 in. by 0.300 in. (2.67 mm by 7.62 mm), with a height of 0.326 in. (8.28 mm), and typically weighs 0.6 grams.

While other resistor technologies can take several seconds or even minutes to achieve a steady-state thermal stabilization, the RNC90Z devices have an almost instantaneous thermal stabilization time of < 1 second, and a nearly immeasurable 1.0-ns rise time, effectively without ringing. The ultimate resistors for analog applications, the devices are built to handle unconventional environmental conditions above and below the surface with minimal drift. Their construction guarantees a high level of reliability, and provides high resistance to thermal shock, moisture, mechanical shock, and vibrations.

With thick or thin film resistors, there is a continuous load life shift over time. Conversely, Vishay has products that have been in production for 45 years without showing any change in their characteristics after the initial run up. Where required, this run up can be removed by post-manufacturing conditioning, which renders the end value of the resistor virtually the same as the initial value when returned to room temperature. A short-time overload of 6.25 X rated power has no effect on the resistance of RNC90Z resistors once they normalize from the resultant temperature.

Offering the utmost in ESD immunity, the resistors withstand electrostatic discharges up to 25 kV, for increased reliability, and offer a non-inductive (< 0.08 μH), non-capacitive design. The RNC90Z devices are available only with tin/lead alloy terminations, and offer 0.15-in lead spacing, with a 0.2-in version available, the RNC90S.

Prototype samples and production orders of the RNC90Z resistors are available now, with lead times from eight weeks.