Construction
The resistor element is an etched bulk metal foil, bonded to
an alumina substrate. Connections to the foil are made by
copper wires welded to the foil to minimise thermal e.m.f.
Before encapsulation, the resistor element is coated with
silicone rubber to isolate the element from mechanical stress
which would adversely affect the carefully balanced
construction and result in poor resistance/temperature
characteristics.
Ultra Precision Bulk Metal
Film Resistors
4800 series
© 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
187
Dimensions (mm) & Weight (g)
Type L max H max W max T min d nom S nom Wt. nom
4802 8.9 10.2 3.8 30 0.6 5.1 1
4812 7.5 8 2.5 30 0.6 5.1 0.6
4804 15.2 13.2 3.8 30 0.6 10.2 1.5
4805 22.6 13.2 3.8 30 0.6 17.8 2
4832 9.7 5.4 9.7 30 0.6 1.5 1.1
Physical Data
L
4802/12/04/05
4832
W
S
H
T
d dia
L
H
T
d
W
S
Issue B · 03.02
Welwyn Components
Actual
Maximum Typical
Load at commercial rating: 1000 hours at 70°C ∆R% 0.05 0.02
Dry heat: 1000 hours at 155°C ∆R% 0.05 0.02
Shelf life: 12 months at room temperature ∆R% 0.0025
Derating from rated power at 70°C Zero at 155°C
Short term overload ∆R% 0.01 0.005
Climatic category 55/155/56
Climatic ∆R% 0.05 0.03
Long term damp heat ∆R% 0.05 0.03
Temperature rapid change ∆R% 0.01 0.005
Resistance to solder heat ∆R% 0.01 0.005
Vibration and bump ∆R% 0.01 0.005
Noise. (in a decade of frequency) µV/V Below level of
Voltage coefficient of resistance ppm/V practicable measurement
Insulation Resistance ohms >1000M
Inductance µH 0.2 0.08
Capacitance pF 1 0.5
Terminations
Material Solder coated copper wire
Strength The terminations meet the requirements of
IEC 68.2.21.
Solderability The terminations meet the requirements of
IEC 115-1, Clause 4.17.3.2.
Marking
Type reference, resistance value, tolerance and date code are
legend marked. The resistance value conforms to IEC 62.
Solvent Resistance
The protection will withstand all normal industrial solvents
suitable for cleaning printed circuit boards.
Packaging
All components are supplied loose packed in either plastic bags
or panel boxes. Quantity per box will depend on resistor size.
Performance Data
