Fusible, Non-Flammable Resistors
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116 Revision: 02-Dec-05
NFR25/25H
Vishay BCcomponents
FEATURES
•Overload protection without risk of fire
•Wide range of overload currents
•Lead (Pb)-free solder contacts
•Pure tin plating provides compatibility with lead (Pb)-free
and lead containing soldering processes
•Compatible with "Restriction of the use of Hazardous
Substances" (RoHS) directive 2002/95/EC (issue 2004)
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 pro-
tection. 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 range1) 0.22 Ωto 15 kΩ
Resistance tolerance and series ± 5 %; E24 series
Maximum dissipation at Tamb =70°C0.33 W 0.5 W
Thermal resistance Rth 240 K/W 150 K/W
Temperature coefficient:
0.22 Ω≤R≤4.7 Ω≤ ± 200 ×10-6/K ≤ ± 200 ×10-6/K
4.7 Ω<R≤15 Ω≤ ± 200 ×10-6/K ≤ ± 100 ×10-6/K
15 Ω<R≤15 kΩ≤ ± 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 Ω
climatic tests ∆R/R max.: ± 1 % + 0.05 Ω
soldering ∆R/R max.: ± 0.25 % + 0.05 Ω
12NC INFORMATION
•The resistors have a 12-digit numeric code starting with 23
•The subsequent 7 digits indicate the resistor type and
packing
•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
12NC Example
The 12NC for a NFR25 resistor with value 750 Ω, supplied
on a bandolier of 1000 units in ammopack is:
2322 205 13751.
RESISTANCE DECADE LAST DIGIT
0.22 to 0.91 Ω7
1to9.1Ω8
10 to 91 Ω9
100 to 910 Ω1
1to9.1kΩ2
10 to 15 kΩ3
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Revision: 02-Dec-05 117
NFR25/25H
Fusible, Non-Flammable Resistors Vishay
12NC - resistor type and packing
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...
Note
Products can be ordered using either the 12NC or the PART NUMBER. The PART NUMBER is shown to facilitate the introduction of a unified
part numbering system. Currently, this PART NUMBER is applicable in the Americas only.
PART NUMBER
PART NUMBER: NFR2500002207JA100
MODEL/SIZE SPECIAL CHARACTER TC/MATERIAL VALUE TOLERANCE PAC K I N G 1) SPECIAL
NFR2500
NFR25H0
0 = neutral
Z = value overflow
(Special)
0 = standard 3 digit value
1 digit multiplier
Multiplier:
7 = *10-3
8 = *10-2
9 = *10-1
0 = *100
1 = *101
2 = *102
J = ± 5 % N4
A5
A1
R5
The 2 digits
are used for
all special
parts.
00 = standard
PRODUCT DESCRIPTION: NFR25 5 % A1 R22
NFR25 5 % A1 R22
MODEL/SIZE TOLERANCE PACKING1) RESISTANCE VALUE
NFR25
NFR25H
± 5 % A1
A5
47K = 47 KΩ
50R1 = 50.1 Ω
1) Please refer to table PACKING for details.
PACKING
CODE PIECES DESCRIPTION MODEL/SIZE
N4 4 000 Bandolier in ammopack radial taped
NFR25, NFR25H
A5 5 000 Bandolier in ammopack straight leads
A1 1 000 Bandolier in ammopack straight leads
R5 5 000 Bandolier on reel straight leads
25RFN00002207JA100
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118 Revision: 02-Dec-05
NFR25/25H
Vishay BCcomponents Fusible, Non-Flammable Resistors
DIMENSIONS
∅ D
L
1
L
2
∅ d
Outline
DIMENSIONS - resistor types and relevant physical dimensions
TYPE ∅ D
MAX.
L1
MAX.
L2
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 (L1) 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”).
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”.
MASS PER 100 UNITS
TYPE MASS
(g)
NFR25 20.1
NFR25H 20.1
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 VOLTAGE1)
(V)
LIMITING POWER
(W)
NFR25 250 0.33
NFR25H 350 0.5
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Revision: 02-Dec-05 119
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 10050
0
0
50
100
155
- 55
Tamb (°C)
Pmax
(%Prated)
Maximum dissipation (Pmax) in percentage of rated power as
a function of the ambient temperature (Tamb)
10
3
10
2
10
1
10
-1
12
40 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 Ω
103
102
10
1
1240 8
P
overload(W)
t
(s)
10-1
NFR25 This graph is based on measured data which may deviate
according to the application. Fusing Characteristics: 1 Ω ≤ R ≤ 15 Ω
10
3
10
2
10
1
1240 8
P
overload (W)
t
(s)
10
-1
NFR25 This graph is based on measured data which may deviate
according to the application. Fusing Characteristics: 15 Ω ≤ R ≤ 15 kΩ
Fusing Characteristic
10
3
10
2
10
1
10
-1
12
40 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 Ω
103
102
10
1
12
40 8
Poverload (W)
t
(s)
16 20 24
10-1
NFR25H This graph is based on measured data which may deviate
according to the application. Fusing Characteristic: 1 Ω ≤ R ≤ 15 kΩ
:
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120 Revision: 02-Dec-05
NFR25/25H
Vishay BCcomponents Fusible, Non-Flammable Resistors
Pulse Loading Capabilities
10
-1
10
-2
10
-3
10
-4
10
-5
10
-6
10
-1
10
2
10
3
1
1
10
Pmax
(W)
ti (s)
tp/ti = 1000500
200
100
50
20
10
5
2
NFR25 Pulse on a regular basis; maximum permissible peak pulse power as a function
of pulse duration (ti), 0.22 Ω≤R<15Ω
Pmax
()
10
-1
10
-2
10
-3
10
-4
10
-5
10
-6
10
-1
10
2
10
3
1
1
10
Pmax
(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 (ti), 15 Ω<R≤15 kΩ
Pmax
()
600
0
10 10 10
-6 -5 -4
10
-3
10
-2
10
-1
1
500
400
300
200
100
Vmax
(V)
ti(s)
NFR25 Pulse on a regular basis; maximum permissible peak pulse voltage as
a function of pulse duration (ti)
Vmax
()
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Revision: 02-Dec-05 121
NFR25/25H
Fusible, Non-Flammable Resistors Vishay BCcomponents
Pulse Loading Capabilities
10
-5
10
-4
10
-3
10
-2
10
-1
1
10
3
1
10
10
2
Pmax
(W)
ti(s)
10
-6
10
-1
2
5
10
20
50
100
200
500
pi
t /t = 1000
NFR25H Pulse on a regular basis; maximum permissible peak pulse
power as a function of pulse duration (ti)
Pmax
()
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 (ti)
Vmax
(
)
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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122 Revision: 02-Dec-05
NFR25/25H
Vishay BCcomponents Fusible, Non-Flammable Resistors
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
NFR25 Temperature rise (∆T) at the lead end
(soldering point) as a function of dissipated power at
various lead lengths after mounting
Minimum 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.
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
Minimum distance from resistor body to PCB = 1 mm
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Revision: 02-Dec-05 123
NFR25/25H
Fusible, Non-Flammable Resistors Vishay
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<10Ω: 0.1 V
10 Ω≤R<100 Ω:0.3V
100 Ω≤R<1kΩ:1V
1kΩ≤R<10 kΩ:3V
10 kΩ≤R≤15 kΩ:10V
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 Ω
4.29 45 (Xa) component solvent
resistance
isopropyl alcohol or H2O 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 Ω
4.20 29 (Eb) bump 3 ×1500 bumps in 3 directions; 40 g no damage
∆R/R max.: ± 0.25 % + 0.05 Ω
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 Ω
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 Ω
4.23 climatic sequence:
4.23.3 30 (Db) damp heat (accelerated)
1st cycle
4.23.6 30 (Db) damp heat (accelerated)
remaining cycles
6days;55°C; 95 to 98 % RH Rins min.: 103MΩ
∆R/R max.: ± 1 % + 0.05 Ω
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124 Revision: 02-Dec-05
NFR25/25H
Vishay BCcomponents Fusible, Non-Flammable Resistors
4.24.2 3 (Ca) damp heat
(steady state) (IEC)
56 days; 40 °C; 90 to 95 % RH; loaded
with 0.01 Pn
(IEC steps: 4 to 100 V)
Rins max.: 1000 MΩ
∆R/R max.: ± 1 % + 0.05 Ω
4.25.1 endurance (at 70 °C) 1000 hours;
loaded with Pn or Vmax;
1.5 hours on and 0.5 hours off
∆R/R max.: ± 1 % + 0.05 Ω
4.25.3 endurance at upper
category temperature
1000 hours;
no load
∆R/R max.: ± 1 % + 0.05 Ω
4.8.4.2 temperature coefficient at 20/LCT/20 °C and
20/UCT/20 °C (TC ×10−6/K):
0.22 Ω≤R≤4.7 Ω≤ ± 200 ×10-6/K ≤ ± 200 ×10-6/K
4.7 Ω<R≤15 Ω≤ ± 200 ×10-6/K ≤ ± 100 ×10-6/K
15 Ω<R≤15 kΩ≤ ± 100 ×10-6/K ≤ ± 100 ×10-6/K
4.12 noise “IEC publication 60195” < 0.1 µV/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
Rins min.: 104MΩ
see 2nd 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
Legal Disclaimer Notice
Vishay
Document Number: 91000 www.vishay.com
Revision: 08-Apr-05 1
Notice
Specifications of the products displayed herein are subject to change without notice. Vishay Intertechnology, Inc.,
or anyone on its behalf, assumes no responsibility or liability for any errors or inaccuracies.
Information contained herein is intended to provide a product description only. No license, express or implied, by
estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Vishay's
terms and conditions of sale for such products, Vishay assumes no liability whatsoever, and disclaims any express
or implied warranty, relating to sale and/or use of Vishay products including liability or warranties relating to fitness
for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right.
The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications.
Customers using or selling these products for use in such applications do so at their own risk and agree to fully
indemnify Vishay for any damages resulting from such improper use or sale.
