Walsin Technology Corporation
Walsin Technology Corporation
FEATURE
1. SMD metal film resistor
2. High reliability and stability of 0.1% and below per customer request
3. High performance of TCR: 25 ppm/K and below per customer request
4. Low current noise
APPLICATION
•
•
•
•
•
Medical equipment
Measuring instrument
Communication device
Computer
Printer
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 layer that is applied to the top surface of the substrate. The
composition of the resistive layer 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
environmental soldering issue, the outer layer of these end terminations is a Lead-free solder .
Fig 1. Consctruction of Chip-R WFxxU
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Walsin Technology Corporation
QUICK REFERENCE DATA
Item
Series No.
Size code
Resistance Tolerance
Resistance Range
TCR (ppm/°C)
Max. dissipation at T
amb
=70°C
Max. Operation 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
1/8W
150V
4.7Ω ~ 1MΩ
( E24 +E96 )
WF12U
1206 ( 3216 )
General Specification
WF08U
0805 ( 2012 )
WF06U
0603 ( 1608 )
WF04U
0402 ( 1005 )
±0.5%, ±0.1%
4.7Ω ~ 1MΩ
( E24 +E96 )
10Ω ~ 330KΩ
( E24 +E96 )
10Ω ~ 100KΩ
( E24 +E96 )
+25 ~ -25 ppm/°C
1/10W
100V
55/125/56
1/16W
50V
1/16W
25V
RCWV
=
Rated Power
×
Resistance Value
or Max. RCWV listed above, whichever is lower.
Dimensions:
Type
L
W
A
B
t
WF12U
3.10
±
0.10
1.60
±
0.10
0.45
±
0.20
0.45
±
0.20
0.60
±
0.15
WF08U
2.00
±
0.10
1.25
±
0.10
0.25
±
0.20
0.40
±
0.20
0.50
±
0.15
WF06U
1.60
±
0.10
0.80
±
0.10
0.25
±
0.15
0.30
±
0.15
0.45
±
0.15
WF04U
1.00
±
0.05
0.50
±
0.05
0.20
±
0.10
0.25
±
0.10
0.35
±
0.05
Protective coat
t
B
A
End termination
Resistive layer
Ceramic Substrate
W T
1001
L
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Marking
Each resistor is marked with a three digits code on the protective coating to designate the
nominal resistance value. WF04U has no marking!
Example:
E24 serious 1%
E96 serious 1%
39R0 => 390
820R =>821
17R8 =>25X， 178R => 25A
FUNCTIONAL DESCRIPTION
Product characterization
Standard values of nominal resistance are taken from the E96 & E24 series for resistors with a tolerance of
±0.5%, ±0.1%.
The values of the E24/E96 series are in accordance with “IEC publication 60063”.
Derating
The power that the resistor can dissipate depends on the operating temperature; see Fig.2
Figure 2. 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.
SOLDERING CONDITION
The robust construction of chip resistors allows them to be completely immersed in a solder bath of 260°C for
one minute. 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 within lead-free solder bath. The
test condition for no leaching is 260°C for 60 seconds. Typical examples of soldering processes that provide
reliable joints without any damage are given in Fig 3.
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Catalogue numbers
The resistors have a catalogue number starting with .
WF06
Size code
WF12: 1206
WF08: 0805
WF06: 0603
WF04: 0402
U
Type code
U: TCR 25ppm
xxx
Resistance code
E96 +E24:
R is first code followed by
3 significant digits.
E24: 39R0=>390
820R =>821
E96: 17R8 =>25X
178R =>25A
D
Tolerance
D :
±0.5%
C:
±0.25%
B :
±0.1%
T
Packaging code
T : Reeled
1. Reeled tape packaging: 8mm width paper taping.
5,000pcs/reel for WF12U, WF08U, WF06U;
10,000pcs/reel for WF04U.
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