Approval sheet
WK12L, WK20L, WK25L
1%, 5%
Thick Film Power Chip Resistor
Wide Termination
RoHS compliant and Halogen free
Size 0612, 1020, 1225
Automotive AEC Q200 Compliant
ASTM B-809-95 Compliant
*Contents in this sheet are subject to change without prior notice.
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WK12-20-25L_V_AUTO_V01
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Approval sheet
FEATURE
1.
2.
3.
4.
5.
6.
High power rating and compact size
High reliability and stability
Reduced size of final equipment
RoHS compliant and Halogen free products
AEC Q200 Compliant
ASTM B-809-95 60’C 1000hrs compliant
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 at
longer sides. For ease of soldering the outer layer of these end terminations is Tin (lead free) alloy.
Fig 2. Construction of Chip-R
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QUICK REFERENCE DATA
Item
Series No.
Size code
Resistance Tolerance
Resistance Range
TCR (ppm/C) :
Max. dissipation at T
amb
=70C
Max. Operation Voltage (DC or RMS)
Max. Overload Voltage (DC or RMS)
Climatic category (IEC 60068)
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
200 ppm/C
3/4W
200V
400V
WK12L
0612(1632)
General Specification
WK20L
1020 ( 2550 ),
5%
(E24);
1%
(E24+E96)
1 ~ 1M,
200 ppm/C
1W
200V
400V
55/155/56
200 ppm/C
2W
200V
400V
WK25L
1225(3264)
RCWV
½
RatedPower
Resistance Value
or Max. RCWV listed above, whichever is lower.
MECHANICAL DATA (unit : mm)
TYPE
W
L
H
c
d
WK12L
3.200.20
1.600.20
0.550.10
0.500.25
0.500.25
WK20L
5.000.20
2.500.15
0.550.10
0.600.20
0.600.20
WK25L
6.300.20
3.200.20
0.550.10
0.600.20
0.600.20
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MARKING
Each resistor is marked with
value.
Example:
1R00
3901
1101
a four-digit code on the protective coating to designate the nominal resistance
=
=
=
1
3900
1100
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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SOLDERING CONDITION
The robust construction of chip resistors allows
them to be completely immersed in a solder
bath of 260C 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 235C during 2 seconds. The
test condition for no leaching is 260C for 30
seconds. Typical examples of soldering
processes that provide reliable joints without
any damage are given in Fig 4.
Fig 4. Infrared soldering profile for Chip Resistors
CATALOGUE NUMBERS
The resistors have a catalogue number starting with .
WK12
Size code
WK25 : 1225
WK20 : 1020
WK12: 0612
L
Type code
L : wide
termination
472_
Resistance code
5%
E24 : 2 significant
digits followed by no.
of zeros and a blank
4.7
10
=4R7_
=100_
J
Tolerance
J :
5%
F :
1%
P : Jumper
T
Packaging code
T : 7” Reel
taping
L
Termination
code
L
=
Sn base
(lead free)
V
Special code
V =
AEC Q200
Compliant +
ASTM B-809-
95 Compliant
1% E24+E96:
3 significant
digits followed by no.
of zeros
102
37.4K
=1020
=3742
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