Approval sheet
Page 1 of 10 ASC_WFxxU_V22 Oct.2016
WF25U,WF20U,WF10U,WF12U,WF08U,
WF06U,WF04U, WF02U
±
±±
±1%, ±
±±
±0.5%, ±
±±
±0.25%, ±
±±
±0.1%,
±
±±
±0.05%, ±
±±
±0.01%
TC25
High Precision Thin Film chip resistors
(RoHS compliant 、Halogen Free)
Size 2512, 2010, 1210, 1206, 0805, 0603,
0402, 0201
*Contents in this sheet are subject to change without prior notice.
Approval sheet
Page 2 of 10 ASC_WFxxU_V22 Oct.2016
FEATURE
1. SMD metal film resistor
2. High reliability and stability of 0.25% and below per customer request
3. High performance of TCR: 25 ppm/
°C
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 WFxxU
Approval sheet
Page 3 of 10 ASC_WFxxU_V22 Oct.2016
QUICK REFERENCE DATA
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.
DIMENSIONS:(unit:mm)
Type
WF25U WF20U WF10U WF12U WF08U WF06U WF04U WF02U
L
6.35 ±
±±
± 0.10
5.00 ±
±±
± 0.10
3.10 ±
±±
± 0.10
3.05 ±
±±
± 0.15
2.00 ±
±±
± 0.10
1.55 ±
±±
± 0.10
1.00 ±
±±
± 0.10
0.6 ±
±±
± 0.03
W
3.20 ±
±±
± 0.15
2.50 ±
±±
± 0.15
2.60 ±
±±
± 0.15
1.55 ±
±±
± 0.15
1.25 ±
±±
± 0.10
0.80 ±
±±
± 0.10
0.50 ±
±±
± 0.05
0.3 ±
±±
± 0.03
A
0.60 ±
±±
± 0.20
0.60 ±
±±
± 0.20
0.50 ±
±±
± 0.20
0.40 ±
±±
± 0.20
0.25 ±
±±
± 0.20
0.25 ±
±±
± 0.15
0.15 ±
±±
± 0.10
0.10 ±
±±
± 0.05
B
0.90 ±
±±
± 0.25
0.60 ±
±±
± 0.25
0.50 ±
±±
± 0.20
0.40 ±
±±
± 0.20
0.40 ±
±±
± 0.20
0.30 ±
±±
± 0.15
0.25 ±
±±
± 0.10
0.15 ±
±±
± 0.05
t
0.55 ±
±±
± 0.10
0.55 ±
±±
± 0.10
0.55 ±
±±
± 0.10
0.55 ±
±±
± 0.15
0.50 ±
±±
± 0.15
0.45 ±
±±
± 0.15
0.30 ±
±±
± 0.05
0.23 ±
±±
± 0.03
Item General Specification
Series No. WF25U
WF20U
WF10U WF12U WF08U
WF06U
WF04U
WF02U
Size Code 2512
(6432)
2010
(5025)
1210
(3225)
1206
(3216)
0805
(2012)
0603
(1608)
0402
(1005)
0201
(0603)
Resistance Tolerance ±1.0%, ±0.5%, ±0.25%, ±0.1%, ±0.05%, ±0.01%
Resistance Range 4.7Ω ~
3MΩ 4.7Ω ~
3MΩ 4.7Ω ~
2.49MΩ 4.7Ω ~
2.49MΩ 4.7Ω ~
2MΩ 4.7Ω ~
1MΩ 10Ω ~
255KΩ
100Ω ~
12KΩ
TCR ±25 ppm/°C
Max. Dissipation at
T
amb
=70°C 3/4W 1/2W 1/4W 1/8W 1/10W 1/16W 1/16W 1/32W
Max. Operation Voltage 200V 200V 200V 200V 100V 50V 50V 15V
Max. Overload Voltage 400V 400V 400V 400V 200V 100V 100V 30V
Operation Temperature - 55~ +155’C
Protective coat
Resistive layer
End termination
Ceramic Substrate
t
B
A
T
W
L
1001
Approval sheet
Page 4 of 10 ASC_WFxxU_V22 Oct.2016
MARKING
3-digits marking for 0603 size
WFxxU has same marking rule as WRxx ±1%.
Nominal resistance Description
1.E-24 series As 0603 WR06X ±5%.
2.E-96 series The 1st two digit codes are referring to the CODE on the table, the 3rd code is the index of resistance
value :
Y=10
-2
，X=10
-1
，A=10
0
，B=10
1
，C=10
2
，D=10
3
，E=10
4
，F=10
5
EX : 17.8Ω=25X，178Ω=25A，1K78 =25B
17K8=25C， 178K=25D， 1M78=25E
3. Remark There is no marking for the items are not under E-24 and E-96 series
CODE
R_value
CODE
R_value
CODE
R_Value
CODE
R_value
CODE
R_value
CODE
R_value
CODE
R_value
CODE
R_value
01 100
13 133
25 178
37 237
49 316
61 422
73 562
85 750
02 102
14 137
26 182
38 243
50 324
62 432
74 576
86 768
03 105
15 140
27 187
39 249
51 332
63 442
75 590
87 787
04 107
16 143
28 191
40 255
52 340
64 453
76 604
88 806
05 110
17 147
29 196
41 261
53 348
65 464
77 619
89 825
06 113
18 150
30 200
42 267
54 357
66 475
78 634
90 845
07 115
19 154
31 205
43 274
55 365
67 487
79 649
91 866
08 118
20 158
32 210
44 280
56 374
68 499
80 665
92 887
09 121
21 162
33 215
45 287
57 383
69 511
81 681
93 909
10 124
22 165
34 221
46 294
58 392
70 523
82 698
94 931
11 127
23 169
35 226
47 301
59 402
71 536
83 715
95 953
12 130
24 174
36 232
48 309
60 412
72 549
84 732
96 976
4-digits marking for 2512, 2010, 1210, 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 and 0201 size
FUNCTIONAL DESCRIPTION
Product characterization
Standard values of nominal resistance are taken from the E192 & E24 series for resistors with a tolerance of
±1.0%, ±0.5%, ±0.25%, ±0.1%. The values of the E24/E192 series are in accordance with “IEC publication
60063”.
Approval sheet
Page 5 of 10 ASC_WFxxU_V22 Oct.2016
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 6 of 10 ASC_WFxxU_V22 Oct.2016
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 profile and condition that
provide reliable joints without any damage are given in Fig 3. and Table 1.
Fig. 3 Infrared soldering profile for Chip Resistors
Table 1. Infrared soldering condition for Chip Resistors
Temperature Condition Exposure Time
Average ramp-up rate (217°C to 260°C)
Less than 3°C/second
Between 150 and 200°C
Between 60-120 seconds
> 217°C
Between 60-150 seconds
Peak Temperature
260ºC +0/-5°C
Time within 245°C
Min. 30 seconds
Ramp-down rate (Peak to 217°C)
Less than 6°C/second
Time from 25°C to Peak
No greater than 480 seconds
Approval sheet
Page 7 of 10 ASC_WFxxU_V22 Oct.2016
CATALOGUE NUMBERS
The resistors have a catalogue number starting with .
WF06 U xxxx B T L
Size code
WF25: 2512
WF20: 2010
WF10: 1210
WF12: 1206
WF08: 0805
WF06: 0603
WF04: 0402
WF02: 0201
Type code
U: TCR = 25 ppm
Resistance code
R is first code followed by
3 significant digits.
100Ω =1000
37.4KΩ =3742
Tolerance
T : ±0.01%
A : ±0.05%
B : ±0.10%
C : ±0.25%
D : ±0.50%
F : ±1.00%
Packaging code
T : 7” Reel taping
A :7” Reel 15k pcs
Termination code
L = lead free
1. Reeled tape packaging: 8mm width paper taping.
5,000pcs/reel for WF10U, WF12U, WF08U, WF06U;
10,000pcs/reel for WF04U;
15,000pcs/real for WF02U.
2. Reeled tape packaging: 12mm width paper taping
4,000pcs/reel for WF25U, WF20U.
Approval sheet
Page 8 of 10 ASC_WFxxU_V22 Oct.2016
TEST AND REQUIREMENTS(JIS C 5201-1 : 1998)
REQUIREMENT
TEST PROCEDURE Resistor
DC resistance
Clause 4.5 DC resistance values measured
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 9 of 10 ASC_WFxxU_V22 Oct.2016
PACKAGING
Paper Tape specifications (unit :mm)
Series No. Tape A B W D E
WF25 Plastic 6.90±0.20 3.60±0.20 12.00±0.30 5.50±0.10 1.75±0.10
WF20 Plastic 5.50±0.20 2.80±0.20 12.00±0.30 5.50±0.10 1.75±0.10
WF12 Paper 3.60±0.20 2.00±0.20 8.00±0.30 3.50±0.20 1.75±0.10
WF10 Paper 3.60±0.20 3.00±0.20 8.00±0.30 3.50±0.20 1.75±0.10
WF08 Paper 2.40±0.20 1.65±0.20 8.00±0.30 3.50±0.20 1.75±0.10
WF06 Paper 1.90±0.20 1.10±0.20 8.00±0.30 3.50±0.20 1.75±0.10
WF04 Paper 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
WF25 4.00±0.10 4.00±0.10
1.0 0.0
50.1
+
−
Φ
Max 1.2
WF20 4.00±0.10 4.00±0.10
1.0 0.0
50.1
+
−
Φ
Max 1.2
WF12 4.00±0.10 4.00±0.10
1.0 0.0
50.1
+
−
Φ
Max. 1.0
WF10 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
Approval sheet
Page 10 of 10 ASC_WFxxU_V22 Oct.2016
Reel dimensions
A
B
C
D
WF25FU , WF20U
WF12FU , WF10U , WF08U , WF06U , WF04U
Taping quantity
- Chip resistors 4,000 pcs per reel ( WF25U, WF20U )
- Chip resistors 5,000 pcs per reel ( WF10U, WF12U, WF08U, WF06U )
- Chip resistors 10,000 pcs per reel ( WF04U )
- Chip resistors 15.000 pcs per reel ( WF02U )
Symbol A B C D
(unit : mm) Φ178.0±2.0 Φ60.0±1.0 13.0±0.2 14.0±0.5
Symbol A B C D
(unit : mm) Φ178.0±2.0 Φ60.0±1.0 13.0±0.2 9.0±0.5
