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This BCcomponents product press release (excluding the datasheet links and paragraph on Vishay) originally appeared on the former BCcomponents Web site.
BCcomponents introduces the world's first range of ultra-precision MINI-MELF resistors
November 21, 2000 — BCcomponents today achieved a world-first in the passive component industry by announcing a new range of ultra-precision thin-film MINI-MELF resistors targeted for use in high-accuracy, high-performance applications such as test & measurement equipment, process control instrumentation and aerospace electronics.
Available with tolerance values as low as ±0.02% and temperature coefficients as small as 5 ppm/K, UMA 0204 MINI-MELF resistors bring all the advantages of space-saving surface-mount components to applications where accuracy, stability and lifetime are important design parameters.
"Precision resistors are critical to the performance of a wide range of transducers and measurement circuits," said Joachim von der Ohe, product manager at BCcomponents' Beyschlag division (Heide, Germany), where these new resistors were developed. "With the introduction of our ultra-precision UMA 0204 resistors, designers can replace existing metal-foil resistors with a smaller and lower-cost thin-film solution."
When determining the total error budget for precision resistors, their initial tolerance and temperature coefficient are only part of the story. Designers must also take into account the long-term drift in ohmic value due to ageing. This is particularly important in applications where a very long lifetime is required or where the component cannot easily be replaced, such as in space satellites. It is also an important factor in the automotive electronics industry, where there is an increasing need to build modules that are capable of withstanding ever higher ambient temperatures, but at the same time are required to stay within pre-determined stability and precision requirements. This is particularly true for sensors in the air supply and exhaust ducts near to the engine core.
For a continuous power dissipation of 0.07 W, UMA 0204 resistors are guaranteed to drift no more than 1200ppm (0.12%) during their minimum specified lifetime of 225 thousand hours (25 years). Even at their maximum rated power dissipation of 0.25 W, long term drift is guaranteed not to exceed 0.3%. The failure rate for UMA 0204 resistors is less than 0.7 x 10-9/hour. The UMA 0204 series has been released by ESA (European Space Agency) for use in the Columbus module of the International Space Station (ISS).
UMA 0204 resistors are available with initial tolerances of ±0.02%, ±0.05%, ±0.1% and ±0.25%, and temperature coefficients of 5 ppm/K, 10 ppm/K and 15 ppm/K. The standard range includes all E192 values between 22 ohm and 221 kohm, with other values available to special order. Quantity deliveries are available 12 weeks after receipt of order.
Vishay Intertechnology, Inc., a Fortune 1000 Company listed on the NYSE (VSH), is one of the world's largest manufacturers
of discrete semiconductors (diodes, MOSFETs, and infrared optoelectronics) and passive electronic components (resistors, inductors,
and capacitors). These components are used in virtually all types of electronic devices and equipment, in the industrial,
computing, automotive, consumer, telecommunications, military, aerospace, power supplies, and medical markets. Vishay’s product
innovations, successful acquisition strategy, and "one-stop shop" service have made it a global industry leader. Vishay can
be found on the Internet at www.vishay.com.