A subsidiary of
TT electronics plc
05 . 08
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.
© 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
Radial Ceramic Case Resistors
Wirewound / Metal Oxide
2 to 10 watts
Resistance 0R1 to 200K
High overload capability
Flameproof case
Small PCB footprint
RoHS compliant
SQM Series
Electrical Data
SQM2
SQM3
SQM5
SQM7
SQM10
Power rating at 70°C
watts
2
3
5
7
10
Resistance range ohms
Wirewound
0R1 - 27R
0R1 - 39R
0R1 - 47R
0R1 - 680R
0R1 - 910R
Metal Oxide
30R – 33K
43R – 56K
51R – 100K
750R - 200K
1K0 - 200K
Limiting element voltage
volts dc or ac rms
150
300
350
500
750
Thermal impedance
°C /watt
50
45
30
28
23
Isolation voltage
volts
TCR
ppm/°C
Resistance Tolerance
%
Standard Values
Ambient temperature range
°C
Physical Data
(all dimensions in mm, weights in g)
Type
L
± 1.0
W
± 1.0
D
± 1.0
P
± 1.0
d
± 0.05
Weight
Nom.
SQM2
20
11.5
7.5
5
0.7
4.3
SQM3
25
12.5
8.5
5
0.7
5.6
SQM5
25
12.5
9
5
0.8
6.3
SQM7
38
12.5
9
5
0.8
10.7
SQM10
50
12.5
9
5
0.8
13.4
Leads centered on SQM2, SQM3, SQM5
Leads offset as shown on SQM7, SQM10
Construction
A high purity ceramic rod, with force fit end caps onto which is wound a wire element: or a deposited metal oxide film
(depending on value). The element is fitted into a ceramic case with fireproof insulation cement.
5±1
D
L
P
d
W
5±1
Radial Ceramic Case Resistors
Wirewound / Metal Oxide
05 . 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
SQM Series
Termination Details:
Material The 100% Sn finish copper lead wires are internally welded to the resistance element end caps.
Solderability The terminations meet the requirements of IEC 115-1 Clause 4.17.3.2
Strength The terminations meet the requirements of IEC 86.2.21
Marking: Type reference, resistance value and tolerance are legend marked onto the upper surface.
Flammability: The resistor will not burn under any condition of applied temperature or overload.
Solvent resistance: The body protection and marking are resistant to all normal industrial solvents suitable for printed
circuits.
Performance Data
Maximum
Load at rated power (1000hrs at 70°C)
ΔR
<100K, 5%; ≥100K, 10%
Derating from rated power at 70°C
See Graph
Short term overload *
ΔR
5% +0.05Ώ
Damp heat steady state (56 days, 40°C, ≥90% RH)
ΔR
5% +0.05Ώ
Temperature rapid change (5 cycles -55ºC to +155ºC)
ΔR
2% +0.05Ώ
Resistance to solder heat
ΔR
1% +0.05Ώ
Voltage Proof (1kV for 60s)
No evidence of flashover, mechanical damage,
arcing or insulation breakdown
Solderability
Min. 95% coverage
* Wirewound: the lower of 5x rated power, or 2.5x LEV for 5s Metal Oxide: the lower of 6.25x rated power, or 2.5x LEV for 5s
Derating Curve
Ordering Procedure
Example: SQM3 at 1.2 kilohms and 5% tolerance bulk packed in a box of 3000 pieces –
S Q M 3 – 1 K 2 J B 3
Type
Value (use IEC62 code)
Tolerance (use IEC62 code)
J
5%
Packing
B3
Bulk
SQM2, 3
3000 / box
Standard
B2
SQM5
2000 / box
B1
SQM7, 10
1000 / box
0%
100%
T (°C)
70
155
275
60%
-55
P/Pr