MELF resistors have been part of the passive component landscape for many decades because they offer a set of performance characteristics that set them apart from standard chip resistors.
MELF resistors are manufactured by depositing an homogenous film of metal alloy onto a high grade ceramic body. Nickel end caps are then pressed onto the metallised rods and and a helical groove laser-etched into the resistive layer to produce the required resistance value.
MELF resistors are able to provide better long term stability, moisture resistance, reliability and resistance to temperature cycling during the soldering process than conventional surface mount chip resistors.
While MELF resistors are more expensive than their conventional counterparts, their enhanced performance characteristics can make them a cost effective option in some applications.
TT Electronics produces a range of four series of MELF resistors for commercial, automotive and industrial grade applications.
TT Electronics WRM Series
The TT Electronics WRM Series is a high reliability, AEC-Q200 compliant device available in tolerances down to ±0.1%.
Available in 0102, 0204 and 0207 case sizes, overall resistance range is 0.22Ω to 5.1MΩ and power rating range @ 70°C is 0.2W to 0.4W.
TT Electronics WRM-HP Series
The TT Electronics WRM-HP Series is a higher power version of the WRM Series.
Available in 0204 and 0207 case sizes, overall resistance range is 0.1Ω to 10.MΩ and power rating range @ 70°C is 0.4W to 1.0W.
TT Electronics WRM-HV Series
The TT Electronics WRM-HV Series is a high voltage version of the WRM Series featuring a high limiting element voltage up to 1kV and a maximum overload voltage of 2kV.
Available in 0204 and 0207 case sizes, overall resistance range is 340kΩ to 3.4MΩ and power rating range @ 70°C is 0.4W to 1.0W.
TT Electronics WCM Series
The TT Electronics is a high pulse MELF resistor able to withstand a 1.2/50µs pulse up to 10kV, a peak power rating up to 800W for 1ms and 5s overload up to 700V
Available in 0204 and 0207 case sizes, overall resistance range is 7.5Ω to 10MΩ and power rating range @ 70°C is 0.25W to 1W.
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