Approval sheet
WR18X(W), WR20X(W), WR25X(W)
±
1%,
±
5%
Thick Film Power Chip Resistors
Size 1218,2010,2512
*Contents in this sheet are subject to change without prior notice.
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WR18-20-25X(W)_V17
DEC - 2016
Approval sheet
FEATURE
1.
2.
3.
4.
High power rating and compact size
High reliability and stability
Reduced size of final equipment
RoHS compliant and Lead free products
APPLICATION
•
•
•
•
•
•
•
Power supply
PDA
Digital meter
Computer
Automotives
Battery charger
DC-DC power converter
DESCRIPTION
The resistors are constructed in a high grade ceramic body (aluminum oxide). Internal metal electrodes are
added at each end and connected by a resistive paste that is applied to the top surface of the substrate. The
composition of the paste is adjusted to give the approximate resistance required and the value is trimmed to
nominated value within tolerance which controlled by laser trimming of this resistive layer.
The resistive layer is covered with a protective coat. Finally, the two external end terminations are added. For
ease of soldering the outer layer of these end terminations is Tin (lead free) alloy.
Fig 1. Construction of 2512, 2010 Chip-R
Fig 2. Construction of a 1218 Chip-R
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WR18-20-25X(W)_V17
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Approval sheet
QUICK REFERENCE DATA
Item
Series No.
Size code
Resistance Tolerance
Resistance Range
TCR (ppm/°C) :
10Ω< Rn
≤
10MΩ
1Ω≤ Rn
≤
10Ω
Max. dissipation at T
amb
=70°C
Max. Operation Voltage (DC or RMS)
Max. Overload Voltage (DC or RMS)
Operation temperature
Storage temperature
±
100 ppm/°C
±
200 ppm/°C
1W
200V
400V
WR18X(W)
1218(3248)
General Specification
WR20X(W)
2010 ( 5025 ),
±5%
(E24);
±1%
(E24+E96)
1Ω ~ 10MΩ, Jumper (0Ω)
±
100 ppm/°C
±
200 ppm/°C
0.75 W
200V
400V
-55 ~ +155’C
5 ~ 40’C
±
100 ppm/°C
±
200 ppm/°C
1W
250V
500V
WR25X(W)
2512(6432)
Test conditions for jumper ( 0 ohm )
Type
Power Rating At 70C
Resistance
Rated Current
Peak Current
Operating Temperature
WR18X(W)
1W
Max. 50mR
4.5 A
11 A
-55C ~ 155C
WR20X(W)
3/4 W
Max. 50mR
3.8 A
9A
-55C ~ 155C
WR25X(W)
1W
Max. 50mR
4.5 A
11 A
-55C ~ 155C
Note :
1.
2.
This is the maximum voltage that may be continuously supplied to the resistor element, see “IEC publication
60115-8”
Max. Operation Voltage : So called RCWV (Rated Continuous Working Voltage) is determined by
RCWV
=
Rated Power
×
Resistance Value
or Max. RCWV listed above, whichever is lower.
MECHANICAL DATA (unit : mm)
TYPE
L
W
T
Tt
Tb
WR18
3.05±0.15
4.60±0.20
0.55±0.10
0.45±0.25
0.50±0.25
WR20
5.00±0.20
2.50±0.20
0.55±0.10
0.65±0.25
0.60±0.25
WR25
6.40±0.20
3.20±0.20
0.60±0.10
0.65±0.25
0.90±0.25
Page 3 of 7
WR18-20-25X(W)_V17
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Approval sheet
MARKING
Each resistor is marked with
value.
Example:
1R00
1001
0000
a four-digit code on the protective coating to designate the nominal resistance
=
=
=
1Ω
1000Ω
0Ω
FUNCTIONAL DESCRIPTION
Product characterization
Standard values of nominal resistance are taken from the E96 & E24 series for resistors with a tolerance of
±5%
&
±1%.
The values of the E24/E96 series are in accordance with “IEC publication 60063”.
Derating curve
The power that the resistor can dissipate depends on the operating temperature; see Fig.3
Figure 3. Maximum dissipation in percentage of rated power
as a function of the ambient temperature.
MOUNTING
Due to their rectangular shapes and small tolerances, Surface Mountable Resistors are suitable for handling by
automatic placement systems.
Chip placement can be on ceramic substrates and printed-circuit boards (PCBs).
Electrical connection to the circuit is by individual soldering condition.
The end terminations guarantee a reliable contact.
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WR18-20-25X(W)_V17
DEC - 2016
Approval sheet
SOLDERING CONDITION
The robust construction of chip resistors allows them to be completely immersed in a solder bath of 260°C
for 10 seconds. Therefore, it is possible to mount Surface Mount Resistors on one side of a PCB and other
discrete components on the reverse (mixed PCBs).
Surface Mount Resistors are tested for solderability at 235°C during 2 seconds. The test condition for no
leaching is 260°C for 30 seconds. Typical examples of soldering processes that provide reliable joints
without any damage are given in below.
CATALOGUE NUMBERS
3-5 sec
The resistors have a catalogue number starting with .
WR20
Size code
WR25 : 2512
WR20 : 2010
WR18: 1218
X
Type code
X:
±5%:
1Ω-10MΩ
±1%:
10Ω-1MΩ
W:
1% : <10Ω or
>1MΩ
472_
Resistance code
5%
E24 : 2 significant digits
followed by no. of zeros and
a blank
4.7Ω
10Ω
=4R7_
=100_
J
Tolerance
J :
±5%
F :
±1%
P : Jumper
T
Packaging code
T : 7” Reel taping
(T:1218 10” Reel)
Q : 10” Reel taping
G : 13” Reel taping
L
Termination code
L
=
Sn base (lead
free)
1% E24+E96:
3 significant digits
followed by no. of zeros
102Ω
37.4KΩ
=1020
=3742
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WR18-20-25X(W)_V17
DEC - 2016
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