Flameproof Power
Metal Film Resistors
MFP Series
Welwyn Components
•
•
•
Smallest size for power rating
Resistance range 0.1 ohms to 1M ohms
Flameproof protection
Electrical Data
MFP1
Power rating at 70°C
Resistance range
Limiting element voltage
TCR
Resistance tolerance
Standard values
Thermal impedance
Ambient temperature range
°C/watt
°C
120
-55 to 155
watts
ohms
volts
ppm/°C
%
< 1
Ω:
300
1
Ω
- 9.1
Ω:
200
≥10 Ω:
50
1, 2, 5
E24 preferred
82
<1
Ω:
0.7
>=1
Ω:
1.0
350
100
0R1 – 1M
MFP2
2
1R0 – 1M
Physical Data
Dimensions (mm) & Weight (g)
PCB
Type
MFP1
MFP2
L Max
6.2
10.0
D Max
2.5
4.0
f min
21.0
27.0
d nom
0.6
0.8
mounting
centres
10.2
18.4
Min.
bend
radius
0.6
1.2
Wt.nom
0.3
0.55
d
D
L
f
Construction
The resistance element is a precisely controlled thin film of
metal alloy on a high purity ceramic core, protected by a
cement coating applied so that terminations remain
completely clear. This permits a well defined body length
(clean lead to clean lead dimension L).
Marking
Resistors are colour coded with 4 or 5 bands depending on
value and tolerance. IEC 62 colours are used.
Solvent Resistance
The body protection and marking are resistant to all normal
industrial cleaning solvents suitable for printed circuits.
Terminations
Material
Strength
Solder-coated copper wire.
The terminations meet the requirements of
IEC 68.2.21
Flammability
The resistor coating will not burn or emit incandescent
particles under any condition of applied temperature or
power overload.
Solderability
The terminations meet the requirements of
IEC 115-1, Clause 4.17.3.2
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
Issue D · 03.06
© 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
143
Flameproof Power
Metal Film Resistors
MFP Series
Welwyn Components
Performance Data
Maximum
Load at rated power : 1000 hours at 70°C
Shelf life : 12 months at room temperature
Derating from rated power at 70°C
Climatic
Climatic category
Temperature rapid change
Resistance to solder heat
Voltage proof
∆
R %
∆
R %
volts
∆
R %
∆
R %
∆
R %
∆
R %
5
2
zero at 155°C
3
50/155/56
0.5
0.5
500 min
Application Notes
1. If the resistors are to dissipate full rated power, it is
recommended that the terminations should not be
soldered closer than 4mm from the body.
2. Due to operating temperature limitations imposed by some
pcb materials, derating may be necessary. An estimate of
the temperature rise to be expected can be calculated
using the thermal impedance figures given under Electrical
Data.
3. MFP resistors an also be supplied pre-formed.
Packaging
MFP resistors are normally supplied tape packed ready for
loading onto automatic sequencing and insertion machines.
The standard taping method and critical dimensions are
shown in Figure 1.
Component wires will not protrude beyond the outside edge
of the tapes.
Alternative packaging available by request.
Lead Formed resistors can also be supplied. Standard options
of Lancet, Radial and Goalpost forming are shown in lead
Form Information section.
Figure 1
Type
b
(mm)
MFP1
52
MFP2
68
5
f
1
6
b
f
2
6
Ordering Procedure
Type
Value (use IEC62 code)
Tolerance (use IEC62 code)
F
G
J
1%
2%
5%
Body location f
1
– f
2
≤
1.4 mm
Example: MFP2 at 4.7 kilohms and 1% tolerance in ammo pack box of 2000 pieces
–
MFP2
–
4K7F
I
Packing
I
Ammo
MFP1
MFP2
5000/box
2000/box
Standard
© 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 D · 03.06
144
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