Approval sheet
Page 1 of 7 ASC_WFxxW_V06 Nov.2011
WF12W, WF08W, WF06W, WF04W
±
±±
±0.5%, ±
±±
±0.25%, ±
±±
±0.1%, ±
±±
±0.05%
TC10
High Precision Thin Film chip resistors
Size 1206, 0805, 0603, 0402
*Contents in this sheet are subject to change without prior notice.
Approval sheet
Page 2 of 7 ASC_WFxxW_V06 Nov.2011
FEATURE
1. SMD metal film resistor
2. High reliability and stability of 0.25% and below per customer request
3. High performance of TCR: 10 ppm/K and below per customer request
4. Low current noise
5. RoHS compliant and lead free
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. Construction of Chip-R WFxxW
Approval sheet
Page 3 of 7 ASC_WFxxW_V06 Nov.2011
QUICK REFERENCE DATA
Item General Specification
Series No. WF12W WF08W WF06W WF04W
Size code 1206 ( 3216 ) 0805 ( 2012 ) 0603 ( 1608 ) 0402 ( 1005 )
Resistance Tolerance ±0.5%, ±0.25%, ±0.1%, ±0.05% *
Resistance Range 25Ω ~ 300KΩ
( E24 +E192 )
25Ω ~ 200KΩ
( E24 +E192 )
25Ω ~ 100KΩ
( E24 +E192 )
25Ω ~ 20KΩ
( E24 +E192 )
TCR (ppm/°C) ±10 ppm/°C
Max. dissipation at T
amb
=70°C 1/8W 1/8W 1/10W 1/16W
Max. Operation Voltage (DC or RMS) 150V 100V 50V 25V
Max. Overload Voltage (DC or RMS) 300V 200V 100V 50V
Operation temperature - 55~ +155’C
Note :
1. This is the maximum voltage that may be continuously supplied to the resistor element, see “IEC publication
60115-8”
2. Max. Operation Voltage : So called RCWV (Rated Continuous Working Voltage) is determined by
ValueResistancePower RatedRCWV ×=
or Max. RCWV listed above, whichever is lower.
3. Tolerance
±0.05% is upon requested
DIMENSIONS:(unit:mm)
Type
WF12W WF08W WF06W WF04W
L
3.05 ±
±±
± 0.15 2.00 ±
±±
± 0.10 1.55 ±
±±
± 0.10 1.00 ±
±±
± 0.10
W
1.55 ±
±±
± 0.15 1.25 ±
±±
± 0.10 0.80 ±
±±
± 0.10 0.50 ±
±±
± 0.05
A
0.40 ±
±±
± 0.20 0.25 ±
±±
± 0.20 0.25 ±
±±
± 0.15 0.15 ±
±±
± 0.10
B
0.40 ±
±±
± 0.20 0.40 ±
±±
± 0.20 0.30 ±
±±
± 0.15 0.25 ±
±±
± 0.10
t
0.55 ±
±±
± 0.15 0.50 ±
±±
± 0.15 0.45 ±
±±
± 0.15 0.30 ±
±±
± 0.05
Protective coat
Resistive layer
End termination
Ceramic Substrate
t
B
A
T
W
L
1001
Approval sheet
Page 4 of 7 ASC_WFxxW_V06 Nov.2011
MARKING
3-digits marking for 0603 size
WFxxW has same marking rule as WRxx ±1%.
4-digits marking for 1206, 0805 size
For E24+E96, each resistor is marked with a four digits code on the protective coating to designate the
nominal resistance value. For values below 97Ω6 the R is used as a digit. For values of 100Ω or greater, the
first 3 digits are significant, the fourth digit indicates the number of multiple to follow.
Example
RESISTANCE 100Ω 6800Ω 47000Ω
4-digits marking 1000 6801 4702
No marking code for 0402 size
FUNCTIONAL DESCRIPTION
Product characterization
Standard values of nominal resistance are taken from the E192 & E24 series for resistors with a tolerance of
±0.5%, ±0.25%, ±0.1%. The values of the E24/E192 series are in accordance with “IEC publication 60063”.
Derating
The power that the resistor can dissipate depends on the operating temperature; see Fig.2
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.
Approval sheet
Page 5 of 7 ASC_WFxxW_V06 Nov.2011
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 within lead-free solder bath. 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 Fig 3.
CATALOGUE NUMBERS
The resistors have a catalogue number starting with .
WF06 W xxxx B T L
Size code
WF12: 1206
WF08: 0805
WF06: 0603
WF04: 0402
Type code
W: TCR 10ppm
Resistance code
E192+E24:
R is first code followed by
3 significant digits.
100Ω =1000
37.4KΩ =3742
Tolerance
A : ±0.05%
B : ±0.10%
C : ±0.25%
D : ±0.50%
Packaging code
T : Reeled
Termination code
L = lead free
1. Reeled tape packaging: 8mm width paper taping.
5,000pcs/reel for WF12W, WF08W, WF06W;
10,000pcs/reel for WF04W.
Approval sheet
Page 6 of 7 ASC_WFxxW_V06 Nov.2011
TEST AND REQUIREMENTS(JIS C 5201-1 : 1998)
REQUIREMENT
TEST PROCEDURE Resistor
DC resistance
Clause 4.5 DC resistance values measured
<10Ω@0.1V, <100Ω@0.3V, <1KΩ@1.0V,
<10KΩ@3V, <100KΩ@10V,<1MΩ@25V,
<10MΩ@30V
Within the specified tolerance
Temperature
Coefficient of
Resistance(T.C.
R)
Clause 4.8
Natural resistance change per change in degree
centigrade.
( )
6
121
12 10×
−
−
ttR RR
(ppm/°C)
R
1
: Resistance at reference temperature
R
2
: Resistance at test temperature
t
1
: 20°C+5°C-1°C
t2 : 125°C+5°C-1°C
Refer to
“ QUICK REFERENCE DATA “
Short time
overload
(S.T.O.L)
Clause 4.13
Permanent resistance change after a 5second
application of a voltage 2.5 times RCWV or the
maximum overload voltage specified in the
above list, whichever is less.
∆R/R max. ±(0.1%+0.05Ω)
Resistance to
soldering
heat(R.S.H)
IEC 60068-2-
58:2004
Un-mounted chips completely immersed for
10±1second in a SAC solder bath at 260℃
±5ºC
no visible damage
∆ R/R max. ±(0.1%+0.05Ω)
Solderability
IEC 60068-2-
58:2004
Un-mounted chips completely immersed for
2±0.5 second in a SAC solder bath at 235℃±5℃
good tinning (>95% covered)
no visible damage
Temperature
cycling
Clause 4.19
30 minutes at -55°C±3°C, 2~3 minutes at
20°C+5°C-1°C, 30 minutes at +155 °C±3°C,
2~3 minutes at 20°C+5°C-1°C, total 5
continuous cycles
no visible damage
∆R/R max. ±(0.25%+0.05Ω)
Load life
(endurance)
Clause 4.25
70±2ºC, 1000 hours, loaded with RCWV or
Vmax,1.5 hours on and 0.5 hours off ∆R/R max. ±(0.25%+0.05Ω)
Load life in
Humidity
Clause 4.24
1000 hours, at rated continuous working voltage
in humidity chamber controller at 40°C±2°C and
90~95% relative humidity, 1.5hours on and 0.5
hours off
∆R/R max. ±(0.25%+0.05Ω)
Bending strength
Clause 4.33 Resistors mounted on a 90mm glass epoxy resin
PCB(FR4); bending : 3 mm, once for 10
seconds.
∆R/R max. ±(0.1%+0.05Ω)
Adhesion
Clause 4.32 Pressurizing force: 5N, Test time: 10±1sec. No remarkable damage or removal of the
terminations.
Approval sheet
Page 7 of 7 ASC_WFxxW_V06 Nov.2011
PACKAGING
Paper Tape specifications (unit :mm)
FP0
D
Series No. A B W D E
WF12 3.60±0.20 2.00±0.20 8.00±0.30 3.50±0.20 1.75±0.10
WF08 2.40±0.20 1.65±0.20 8.00±0.30 3.50±0.20 1.75±0.10
WF06 1.90±0.20 1.10±0.20 8.00±0.30 3.50±0.20 1.75±0.10
WF04 1.20±0.10 0.7±0.10 8.00±0.20 3.50±0.05 1.75±0.10
Series No. F P0 ΦD T
WF12 4.00±0.10 4.00±0.10
1.0 0.0
50.1
+
−
Φ
Max. 1.0
WF08 4.00±0.10 4.00±0.10
1.0 0.0
50.1
+
−
Φ
Max. 1.0
WF06 4.00±0.10 4.00±0.10
1.0 0.0
50.1
+
−
Φ
0.65±0.05
WF04 2.00±0.10 4.00±0.10
1.0 0.0
50.1
+
−
Φ
0.40±0.05
Reel dimensions
A
B
C
D
Symbol A B C D
(unit : mm) Φ178.0±2.0 Φ60.0±1.0 13.0±0.2 9.0±0.5
Taping quantity
- Chip resistors 5,000 pcs per reel ( WF12W, WF08W, WF06W )
- Chip resistors 10,000 pcs per reel ( WF04W )
