Flameproof Power
Metal Film Resistors
MFP Series
•Smallest size for power rating
•Resistance range 0.1 ohms to 1M ohms
•Flameproof protection
MFP1 MFP2
Power rating at 70°C watts <1 Ω: 0.7 >=1 Ω: 1.0 2
Resistance range ohms 0R1 – 1M 1R0 – 1M
Limiting element voltage volts 350
TCR ppm/°C < 1 Ω: 300 1 Ω- 9.1 Ω: 200 ≥10 Ω: 50 100
Resistance tolerance % 1, 2, 5
Standard values E24 preferred
Thermal impedance °C/watt 120 82
Ambient temperature range °C -55 to 155
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
Electrical Data
Issue D · 03.06
A subsidiary of
TT electronics plc
Welwyn Components
143
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.
Flammability
The resistor coating will not burn or emit incandescent
particles under any condition of applied temperature or
power overload.
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).
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
Dimensions (mm) & Weight (g)
PCB Min.
mounting
bend
Type L Max D Max f min d nom centres radius Wt.nom
MFP1 6.2 2.5 21.0 0.6 10.2 0.6 0.3
MFP2 10.0 4.0 27.0 0.8 18.4 1.2 0.55
Physical Data
L
Df
d
Flameproof Power
Metal Film Resistors
MFP 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 Issue D · 03.06
Welwyn Components
144
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.
b
f1f2
66
5
Body location f1 – f2≤ 1.4 mm
Figure 1
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.
Maximum
Load at rated power : 1000 hours at 70°C ∆5% R
Shelf life : 12 months at room temperature ∆2% R
Derating from rated power at 70°C ∆C°551 ta orez% R
Climatic ∆3% R
Climatic category 50/155/56
Temperature rapid change ∆5.0% R
Resistance to solder heat ∆5.0% R
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Performance Data
2PFM1PFMepyT
b8625)mm(
Ordering Procedure
Example: MFP2 at 4.7 kilohms and 1% tolerance in ammo pack box of 2000 pieces –
M F P 2 – 4 K 7 F I
Type
Value (use IEC62 code)
Tolerance (use IEC62 code)
F
1%
G
2%
J
5%
Packing
I
Ammo
MFP1
5000/box
Standard
MFP2
2000/box
