Document Number: 28737
For technical questions contact: ff3dresistors@vishay.com
www.vishay.com
Revision: 24-Feb-04
1
NFR25/25H
Vishay BCcomponents
Fusible, Non-Flammable Resistors
FEATURES
Overload protection without risk of fire
Wide range of overload currents.
APPLICATIONS
Audio
Video.
A homogeneous film of metal alloy is deposited on a high
grade ceramic body. After a helical groove has been cut in
the resistive layer, tinned connecting wires of electrolytic
copper are welded to the end-caps. The resistors are coated
with a grey, flame retardant lacquer which provides
electrical, mechanical, and climatic protection. The
encapsulation is resistant to all cleaning solvents in
accordance with "MIL-STD-202E, method
215", and
"IEC 60068-2-45".
Note
1. Ohmic values (other than resistance range) are available on request.
TECHNICAL SPECIFICATIONS
DESCRIPTION
VALUE
NFR25
NFR25H
Resistance range
(1)
0.22
to 15 k
Resistance tolerance and series
5 %; E24 series
Maximum dissipation at T
amb
= 70
C
0.33 W
0.5 W
Thermal resistance R
th
240 K/W
150 K/W
Temperature coefficient:
0.22
R
4.7
200
10
-
6
/K
200
10
-
6
/K
4.7
<
R
15
200
10
-
6
/K
100
10
-
6
/K
15
<
R
15 k
100
10
-
6
/K
100
10
-
6
/K
Maximum permissible voltage (DC or RMS)
250 V
350 V
Basic specifications
IEC 60115-1 and 60115-2
Climatic category (IEC 60068)
55/155/56
Stability after:
load
R/R max.:
1 % + 0.05
climatic tests
R/R max.:
1 % + 0.05
soldering
R/R max.:
0.25 % + 0.05
12NC ORDERING CODE INDICATING RESISTOR TYPE AND PACKAGING
TYPE
ORDERING CODE 23.. ... .....
BANDOLIER IN AMMOPACK
BANDOLIER
ON REEL
RADIAL TAPED
STRAIGHT LEADS
STRAIGHT LEADS
4000
units
1000
units
5000
units
5000
units
NFR25
06 204 03...
22 205 13...
22 205 33...
22 205 23...
NFR25H
06 207 03...
22 207 13...
22 207 33...
22 207 23...
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Document Number: 28737
2
Revision: 24-Feb-04
NFR25/25H
Vishay BCcomponents
Fusible, Non-Flammable Resistors
ORDERING INFORMATION
Numeric Ordering Code (12NC)
The resistors have a 12-digit ordering code starting with 23
The subsequent 7 digits indicate the resistor type and
packaging.
The remaining 3 digits indicate the resistance values:
The first 2 digits indicate the resistance value.
The last digit indicates the resistance decade.
Last Digit of 12NC Indicating Resistance Decade
Ordering Example
The ordering code for a NFR25 resistor with value 750
,
supplied on a bandolier of 1000 units in ammopack is:
2322 205 13751.
RESISTANCE DECADE
LAST DIGIT
0.22 to 0.91
7
1 to 9.1
8
10 to 91
9
100 to 910
1
1 to 9.1 k
2
10 to 15 k
3
DIMENSIONS
D
L
1
L
2
d
Outline.
DIMENSIONS
- resistor types and relevant physical dimensions
TYPE
D
MAX.
L
1
MAX.
L
2
MAX.
d
NFR25
2.5
6.5
7.5
0.58
0.05
NFR25H
MARKING
The nominal resistance and tolerance are marked on the
resistor using four coloured bands in accordance with
IEC publication 60062 "Colour codes for fixed resistors".
For ease of recognition a fifth ring is added, which is violet
for type NFR25 and white for type NFR25H.
OUTLINES
The length of the body (L
1
) is measured by inserting the
leads into holes of two identical gauge plates and moving
these plates parallel to each other until the resistor body is
clamped without deformation ("IEC publication 60294").
MASS PER 100 UNITS
TYPE
MASS
(g)
NFR25
21
NFR25H
22
FUNCTIONAL PERFORMANCE
PRODUCT CHARACTERIZATION
Standard values of nominal resistance are taken from the E24 series for resistors with a tolerance of 5%.
The values of the E24 series are in accordance with "IEC publication 60063".
Note
1. The maximum voltage that may be continuously applied to the resistor element, see "IEC publication 60115-1".
The maximum permissible hot-spot temperature is 155 C.
LIMITING VALUES
TYPE
LIMITING VOLTAGE
(1)
(V)
LIMITING POWER
(W)
NFR25
250
0.33
NFR25H
350
0.5
Document Number: 28737
For technical questions contact: ff3dresistors@vishay.com
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Revision: 24-Feb-04
3
NFR25/25H
Fusible, Non-Flammable Resistors
Vishay BCcomponents
The power that the resistor can dissipate depends on the operating
temperature.
The resistors will fuse without the risk of fire and within an indicated
range of overload. Fusing means that the resistive value of the resistor
increases at least 100 times.
The fusing characteristic is measured under constant voltage.
Derating
70
100
50
0
0
50
100
155
-55
T
amb
(C)
P
max
(%P
rated
)
Maximum dissipation (P
max
) in percentage of rated power as
a function of the ambient temperature (T
amb
).
10
3
10
2
10
1
10
-1
12
4
0
8
P
overload
(W)
t
(s)
16
20
24
NFR25 This graph is based on measured data which may deviate
according to the application. Fusing Characteristics: 1 .
10
3
10
2
10
1
10
1
12
4
0
8
Poverload(W)
t
(s)
NFR25 This graph is based on measured data which may deviate
according to the application. Fusing Characteristics: 1 R 15 .
10
3
10
2
10
1
10
1
12
4
0
8
Poverload (W)
t
(s)
NFR25 This graph is based on measured data which may deviate
according to the application. Fusing Characteristics: 15 R 15 .
Fusing Characteristic
10
3
10
2
10
1
10
-1
12
4
0
8
P
overload
(W)
t
(s)
16
20
24
NFR25H This graph is based on measured data which may deviate
according to the application. Fusing Characteristics: 1 .
10
3
10
2
10
1
10
-1
12
4
0
8
P
overload
(W)
t
(s)
16
20
24
NFR25H This graph is based on measured data which may
deviate according to the application. Fusing Characteristic.
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Document Number: 28737
4
Revision: 24-Feb-04
NFR25/25H
Vishay BCcomponents
Fusible, Non-Flammable Resistors
10
-1
10
-2
10
-3
10
-4
10
-5
10
-6
10
-1
10
2
10
3
1
1
10
P max
(W)
ti (s)
tp/ti = 1000
500
200
100
50
20
10
5
2
NFR25 Pulse on a regular basis; maximum permissible peak pulse power
as a function
of pulse duration (t
i
), 0.22 R < 15 .
P
max
(
)
10
-1
10
-2
10
-3
10
-4
10
-5
10
-6
10
-1
10
2
10
3
1
1
10
P max
(W)
ti (s)
tp/ti = 1000
100
20
2
NFR25 Pulse on a regular basis; maximum permissible peak pulse power
as a function
of pulse duration (t
i
), 15 < R 15 k.
P
max
(
)
Pulse Loading Capabilities
600
0
10
6
10
5
10
4
10
3
10
2
10
1
1
500
400
300
200
100
V max
(V)
t i (s)
NFR25 Pulse on a regular basis; maximum permissible peak pulse voltage
as
a function of pulse duration (t
i
).
V
max
(
)
Document Number: 28737
For technical questions contact: ff3dresistors@vishay.com
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Revision: 24-Feb-04
5
NFR25/25H
Fusible, Non-Flammable Resistors
Vishay BCcomponents
10
5
10
4
10
3
10
2
10
1
1
10
3
1
10
10
2
P max
(W)
t i (s)
10
6
10
1
2
5
10
20
50
100
200
500
p
i
t /t = 1000
NFR25H Pulse on a regular basis; maximum permissible peak pulse power
as a function of pulse duration (t
i
).
P
max
(
)
Pulse Loading Capabilities
1200
0
400
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
1
800
Vmax
(V)
ti (s)
NFR25H Pulse on a regular basis; maximum permissible peak pulse
voltage
as a function of pulse duration (t
i
).
V
max
(
)
Application Information
100
0
0.2
0.6
0
0.4
20
40
60
80
P (W)
T
(K)
NFR25 Hot-spot temperature rise (T)
as a function of dissipated power.
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Document Number: 28737
6
Revision: 24-Feb-04
NFR25/25H
Vishay BCcomponents
Fusible, Non-Flammable Resistors
50
0
0.2
0.6
0
0.4
10
20
30
40
P (W)
T
(K)
15 mm
5 mm
10 mm
NFR25 Temperature rise (T) at the lead end
(soldering point) as a function of dissipated power
at various lead lengths after mounting.
Minimun distance from resistor body to PCB = 1 mm.
100
0
0.2
0.6
0
0.4
20
40
60
80
P (W)
T
(K)
NFR25H Hot-spot temperature rise (T) as a function
of dissipated power.
Application Information
50
0
0.2
0.6
0
0.4
10
20
30
40
P (W)
T
(K)
15 mm
5 mm
10 mm
NFR25H Temperature rise (T) at the lead end
(soldering point) as a function of dissipated power at
various lead lengths after mounting.
Minimun distance from resistor body to PCB = 1 mm.
Document Number: 28737
For technical questions contact: ff3dresistors@vishay.com
www.vishay.com
Revision: 24-Feb-04
7
NFR25/25H
Fusible, Non-Flammable Resistors
Vishay BCcomponents
TESTS AND REQUIREMENTS
Essentially all tests are carried out in accordance with the
schedule of "IEC publication 60115-1", category LCT/UCT/56
(rated temperature range: Lower Category Temperature,
Upper Category Temperature; damp heat, long term, 56 days).
The testing also covers the requirements specified by EIA and
EIAJ.
The tests are carried out in accordance with IEC publication
60068-2, "Recommended basic climatic and mechanical
robustness testing procedure for electronic components" and
under standard atmospheric conditions according to
"IEC 60068-1", subclause 5.3.
In the Test Procedures and Requirements table the tests and
requirements are listed with reference to the relevant clauses
of "IEC
publications 60115-1
and
60068-2"; a short
description of the test procedure is also given. In some
instances deviations from the IEC recommendations were
necessary for our method of specifying. For inflammability
requirements reference is made to "IEC 60115-1" and to
"EN 140000, appendix D".
All soldering tests are performed with mildly activated flux.
TEST PROCEDURES AND REQUIREMENTS
IEC 60115-1
CLAUSE
IEC
60068-2
TEST
METHOD
TEST
PROCEDURE
REQUIREMENTS
NFR25
NFR25H
TESTS IN ACCORDANCE WITH THE SCHEDULE OF IEC PUBLICATION 60115-8
4.4.1
visual examination
no holes; clean surface; no damage
4.4.2
dimensions (outline)
gauge (mm)
see Dimensions Table
4.5
resistance
applied voltage (+ 0/-10 %):
R - R
nom
: max. 5 %
R < 10 : 0.1 V
10 R < 100 : 0.3 V
100 R < 1 k: 1 V
1 k R < 10 k: 3 V
10 k R 15 k: 10 V
4.18
20 (Tb)
resistance to soldering
heat
thermal shock: 3 s; 350 C;
3 mm from body
R/R max.: 0.25 % + 0.05
4.29
45 (Xa)
component solvent
resistance
isopropyl alcohol or H
2
O followed by
brushing in accordance with "MIL 202 F"
no visual damage
4.17
20 (Ta)
solderability
2 s; 235 C
good tinning; no damage
4.7
voltage proof on
insulation
500 V (RMS) during
1 minute; metal block method
no breakdown or flashover
4.16
21 (U)
robustness of
terminations:
4.16.2
21 (Ua1)
tensile all samples
load 10 N; 10 s
number of failures < 10 10
-6
4.16.3
21 (Ub)
bending half number of samples
load 5 N; 4 90
number of failures < 10 10
-6
4.16.4
21 (Uc)
torsion other half of samples
3 360 in opposite directions
no damage
R/R max.: 0.25 % + 0.05
4.20
29 (Eb)
bump
3 1500 bumps in 3 directions; 40 g
no damage
R/R max.: 0.25 % + 0.05
4.22
6 (Fc)
vibration
frequency 10 to 500 Hz; displacement
1.5 mm or acceleration 10 g;
3 directions; total 6 hours (3 2 hours)
no damage
R/R max.: 0.25 % + 0.05
4.19
14 (Na)
rapid change of
temperature
30 minutes at LCT and
30 minutes at UCT; 5 cycles
no visual damage
R/R max.: 0.25 % + 0.05
4.23
climatic sequence:
4.23.3
30 (Db)
damp heat (accelerated)
1
st
cycle
4.23.6
30 (Db)
damp heat (accelerated)
remaining cycles
6 days; 55 C; 95 to 98 % RH
R
ins
min.: 10
3
M
R/R max.: 1 % + 0.05
Document Number: 28737
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Revision: 24-Feb-04
8
NFR25/25H
Fusible, Non-Flammable Resistors
Vishay BCcomponents
4.24.2
3 (Ca)
damp heat
(steady state) (IEC)
56 days; 40 C; 90 to 95% RH; loaded
with 0.01 P
n
(IEC steps: 4 to 100 V)
R
ins
max.: 1000 M
R/R max.: 1 % + 0.05
4.25.1
endurance (at 70 C)
1000 hours;
loaded with P
n
or V
max
;
1.5 hours on and 0.5 hours off
R/R max.: 1 % + 0.05
4.25.3
endurance at upper
category temperature
1000 hours;
no load
R/R max.: 1 % + 0.05
4.8.4.2
temperature coefficient
at 20/LCT/20 C and
20/UCT/20 C (TC 10
-6
/K):
0.22 R 4.7
200 10
-6
/K
200 10
-6
/K
4.7 < R 15
200 10
-6
/K
100 10
-6
/K
15 < R 15 k
100 10
-6
/K
100 10
-6
/K
4.12
noise
"IEC publication 60195"
< 0.1 V/V
4.26
accidental overload
cheese-cloth
nonflammable
OTHER TESTS IN ACCORDANCE WITH IEC 60115 CLAUSES AND IEC 60068 TEST METHOD
4.17
20 (Ta)
solderability
(after ageing)
8 hours steam or 16 hours 155 C;
leads immersed 6 mm for 2 0.5 s in a
solder bath at 235 5 C
good tinning ( 95 % covered);
no damage
4.6.1.1
insulation resistance
maximum voltage 500 V (DC) after
1 minute; metal block method
R
ins
min.: 10
4
M
see 2
nd
amendment
to "IEC 60115-1", Jan.'87
pulse load
see the Pulse Loading Capabilities
graphs
TEST PROCEDURES AND REQUIREMENTS
IEC 60115-1
CLAUSE
IEC
60068-2
TEST
METHOD
TEST
PROCEDURE
REQUIREMENTS
NFR25
NFR25H
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