Precision Metal
Film Resistors
RC series
Welwyn Components
CECC released products with low
TCRs over a wide resistance range
Resistance tolerance down to 0.05%
Express delivery available
Low noise and negligible voltage coefficient
Electrical Data
RC55
Commercial
Power rating at 70°C
Resistance range
Limiting element voltage
Isolation voltage
TCR (20 to +70°C) & codes
Resistance tolerance
Approved CECC 40101-004
Power rating at 70°C
Resistance range
Limiting element voltage
Isolation voltage
TCR & codes
Resistance tolerance (code)
Approved CECC 40101-804
Power rating at 70°C
Resistance range
Limiting element voltage
Isolation voltage
TCR & codes
Resistance tolerance (code)
Standard values
Thermal impedance
Ambient temperature range
°C/watt
°C
110
watts
ohms
volts
volts
ppm/°C
%
watts
volts
volts
ppm/°C
%
A
0.125
1R to 1M
200
280
B
0.25
1R to 1M
250
350
watts
ohms
volts
volts
ppm/°C
%
H
0.063
200
280
J
0.125
200
280
K
0.25
250
350
0.25
5R to 2M
350
500
0.5
5R to 2M
350
500
5(V), 10(T), 15(Y) & 25(D)
0.05(W), 0.1(B) & 0.25(C)
K
0.25
10R to 1M
250
350
15(Y) & 25(D)
0.05(W), 0.1(B) & 0.25(C)
B
0.25
10R to 1M
250
350
15(T) & 25(E)
0.05(W), 0.1(B) & 0.25(C)
E24, E96 preferred
70
-55 to +155
60
C
0.5
10R to 1M
350
500
See resistance
restrictions
Any value
to order
L
0.5
10R to 1M
350
500
See resistance
restrictions
1.0
10R to 5M
500
700
See resistance
restrictions
RC65
RC70
Notes
ohms 1R to 1M 1R to 1M 1R to 1M
General Note
Welwyn Components reserves the right to make changes in product specification without notice or liability.
All information is subject to Welwyn’s own data and is considered accurate at time of going to print.
A subsidiary of
TT electronics plc
02 . 08
© 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
173
Precision Metal
Film Resistors
RC series
Welwyn Components
Physical Data
Dimensions (mm) & Weight (g)
PCB
mounting
Type
RC55
RC65
RC70
L max
7.2
10.0
15.5
D max
2.5
3.7
5.5
f min
30
30
30
d nom
0.6
0.6
0.8
centres
10.2
12.7
18.4
Min.
Bend
Radius
0.6
0.6
1.2
Wt. nom
0.24
0.40
1.15
d
D
L
f
Construction
A metal film is deposited onto a high quality ceramic former.
Nickel-plated steel caps are force fitted to the former and
termination wires are welded to the caps.
The resistor is adjusted to value by a helical cut in the film
and the body is protected with a specially formulated epoxy
coating.
Marking
Type reference, TCR code, resistance value and
tolerance code.
The resistance values conform to IEC 62.
Solvent Resistance
The body protection and marking are resistant to all normal
industrial cleaning solvents suitable for printed circuits.
Terminations
Material
Strength
Solderability
Solder coated copper wire
The terminations meet the requirements of
IEC 68.2.21.
The terminations meet the requirements of
IEC 115-1, Clause 4.17.3.2.
Performance Data
CECC 40101-004 CECC 40101-804
Requirements
Load at commercial rating: 1000 hours at 70°C
Load at CECC rating: 1000 hours at 70°C
Dry heat: 1000 hours at 155°C
Shelf life: 12 months at room temperature
Derating from rated power at 70°C
Short term overload
Climatic
Climatic category
Long term damp heat
Temperature rapid change
Resistance to solder heat
Vibration and bump
Noise (in a decade of frequency)
Voltage coefficient of resistance
∆R%
∆R%
∆R%
∆R%
µV/V
ppm/V
∆R%
∆R%
∆R%
∆R%
∆R%
∆R%
0.5
0.5
Not specified
Zero at 155°C
0.1
0.5
55/155/56
0.5
0.1
0.1
0.1
Not specified
Not specified
0.5
0.5
Not specified
50% at 125°C
0.1
0.5
55/125/56
0.5
0.1
0.1
0.1
Not specified
Not specified
0.1
0.3
55/155/56
0.5
**0.2
0.06
0.06
1.0
0.1
0.05
0.03
0.02
0.1
<1
0.02
0.1
Requirements
*Actual Performance
Maximum
0.3
0.3
**1.0
0.1
Typical
0.1
0.05
0.15
0.03
Note:
*An 0.01 ohm addition to be added to the performance claims of all resistors <10R.
** All products within the specified approved range meet CECC requirements.
© 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 B · 03.02
174
Precision Metal
Film Resistors
RC series
Welwyn Components
Table of Resistance Restrictions
Tolerance
TCR
ppm/°C
5
10
15
25
0.05%
10 to 500k
10 to 1M
10 to 1M
10 to 1M
RC55
.1 – .25%
10 to 500k
10 to 1M
5 to 1M
5 to 2M
0.05%
10 to 500k
10 to 1M
10 to 1M
10 to 1M
RC65
.1 – .25%
10 to 500k
10 to 1M
5 to 1M
5 to 2M
0.05%
10 to 750k
10 to 1M
10 to 1M
10 to 1M
RC70
.1 – .25%
10 to 750k
10 to 1M
10 to 2M
10 to 5M
Application Notes
Matched Sets and Networks
Welwyn has many years experience in the supply of matched
set of precision resistors.
Resistors can be supplied matched for tolerance and TCR
down to ±0.02% and ±2ppm/°C, either as separate resistors
or pre-assembled and encapsulated within a plastic box.
The individual resistors within a set or module can be
manufactured with a tolerance of ±0.05% and TCR of
±5ppm/°C.
A low inductance version is available at 1% tolerance.
For low inductance version add suffix N.
Packaging
The standard method of packaging RC55 resistors is taped in
ammo packs. Taped resistors on reel or loose packed
components can also be supplied by special request. The
standard packaging for RC65 and RC70 resistors is loose in
boxes. By special request the RC65 components can also be
supplied taped on reel or in ammo pack. In the case of tape
packed components the usable lead length is reduced by the
width of the tape.
5
f
1
6
52
1
f
2
6
– f
2
≤
1.4 mm
Body location f
Ordering Procedure
Example: RC55 with TCR of 5ppm/ °C at 31.6 kilohms and 0.1% tolerance in an ammo pack box of up to 1000 pieces -
RC55 V
–
31K6B
I
Type
Trim option
N
V
T
Standard
Non-inductive
5 ppm/
°C
10 ppm/
°C
Y*
D*
All tolerances
1% only
15 ppm/
°C
25 ppm/
°C
TCR
* CECC40101-804 codes for 15 and 25ppm/°C
are T and E respectively.
Value (use IEC62 code)
Tolerance (use IEC62 code)
W
B
C
0.05%
0.1%
0.25%
Packing
I
Ammo
Bulk
RC55, RC65
RC70
Up to1000/box
250/box
Standard
For CECC released product state on order the CECC number and style. Example:
RC55Y-31K6BI CECC40101-004 J
For SnPb finish instead of Pb-free replace the packing suffix with
PB.
Example:
RC55V-31K6BPB
© 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 B · 03.02
175
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