Metal Strip Current Sense
Resistors Surface Mount
ULR Series
Welwyn Components
Construction
Black type
A low TCR resistance alloy plate, with plated connection bands is
protectively coated and numerically marked with the resistance value.
This part has standard plated end connections and is suitable for wave
or IR reflow soldering.
Green type
A low TCR resistance alloy plate is grooved to set the final resistance,
the lower faces are solder plated for connections, and it is protectively
coated and numerically marked with the resistance value. This part is
ONLY suitable for IR reflow soldering.
Sn Plated Finish
Cn Plating
Protective Coating
Ally Plate
Black Type
Protective Coating
Metal Strip
Marking
For values which are integer numbers of milliohms, the marking is
4-character IEC62 code; e.g. “R002” for 2mΩ, “R010” for 10mΩ.
For values including fractions of a milliohm the marking is 3 or 4-
character code using “M” to indicate the decimal point, e.g. “M75”
for 0.75mΩ, “1M50” for 1.5mΩ.
Sn Plated Finish
Green Type
Termination Details:
Material
Matt tin plated finish over a barrier layer
Solderability
95% min coverage (MIL-STD 202F / 208H, 235ºC 2 secs)
Performance Data
Maximum
Load at rated power
(1000hrs cyclic load at 70°C)
De-rating from rated power at 80°C
Short term overload
(5 x rated power for 5s)
Dry heat
(96Hrs, no load, +155°C)
Temperature rapid change
(-55 / +150ºC, 100 cycles)
Resistance to solder heat
(260ºC for 10s)
∆R%
∆R%
∆R%
∆R%
∆R%
±1% + 0.5mΩ (Black): ±1% (Green)
See Graph
±0.5% + 0.5mΩ (Black): ±1% (Green)
±1% + 0.5mΩ (Black): ±1% (Green)
±0.5% + 0.5mΩ (Black): ±1% (Green)
±0.5% + 0.5mΩ (Black): ±1% (Green)
Power de-rating graph
P
100%
50%
T°C
0%
-55
0
80
170
© Welwyn Components Limited
Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
Issue A · 09.06
WELWYN [ WELWYN COMPONENTS LIMITED ]
