Approval Sheet
WF25T/U, WF20T/U, WF10T/U, WF12T/U,
WF08T/U, WF06T/U, WF04T/U, WF02T/U.
1%, 0.5%, 0.25%, 0.1%, 0.05%, 0.01%
TC50 ,TC25
High Precision Thin Film Chip Resistors
Size 2512, 2010, 1210, 1206, 0805, 0603,
0402, 0201
*Contents in this sheet are subject to change without prior notice.
Page 1 of 10
ASC_WFxxT & U_V01
DEC - 2017
Approval Sheet
FEATURE
1. SMD metal film resistor
2. High reliability and stability of 0.25% and below per customer request
3. High performance of TCR: 50 & 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 WFxxT /U
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ASC_WFxxT & U_V01
DEC - 2017
Approval Sheet
Item
Series No.
WF25
T&U
Size Code
2512
(6432)
Resistance Tolerance
WF20
T&U
2010
(5025)
WF10
T&U
1210
(3225)
General Specification
WF12
T&U
1206
(3216)
WF08
T&U
0805
(2012)
WF06
T&U
0603
(1608)
WF04
T&U
0402
(1005)
WF02
T&U
0201
(0603)
1.0%,
0.5%,
0.1%
10 ~
255K
100 ~
12K
1.0%, 0.5%, 0.25%, 0.1%, 0.05%,0.02%, 0.01%
Resistance Range
TCR
Max. Dissipation at
T
amb
=70C
Max. Operation Voltage
Max. Overload Voltage
Operating Temperature
1 ~
3M
4.7 ~
3M
4.7 ~
2.49M
1 ~
2.49M
4.7 ~
2M
4.7 ~
1M
50 & 25 ppm/C
3/4W
200V
400V
1/2W
200V
400V
1/4W
200V
400V
1/8W
200V
400V
1/10W
100V
200V
1/16W
50V
100V
1/16W
50V
100V
1/32W
15V
30V
- 55~ +155’C
QUICK REFERENCE DATA
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
½
Rated Pow er
Resistance Value
or Max. RCWV listed above, whichever is lower.
DIMENSIONS:(unit: mm)
Type
L
W
A
B
T
WF25T&U
6.35
0.10
3.20
0.15
0.60
0.20
0.90
0.25
0.55
0.10
WF20T&U
5.00
0.10
2.50
0.15
0.60
0.20
0.60
0.25
0.55
0.10
WF10T&U
3.10
0.10
2.60
0.15
0.50
0.20
0.50
0.20
0.55
0.10
WF12T&U
3.05
0.15
1.55
0.15
0.40
0.20
0.40
0.20
0.55
0.15
WF08T&U
2.00
0.10
1.25
0.10
0.25
0.20
0.40
0.20
0.50
0.15
WF06T&U
1.55
0.10
0.80
0.10
0.25
0.15
0.30
0.15
0.45
0.15
WF04T&U
1.00
0.10
0.50
0.05
0.30
0.15
0.30
0.15
0.35
0.05
WF02T&U
0.6
0.03
0.3
0.03
0.10
0.05
0.15
0.05
0.23
0.03
Protective coat
t
B
A
End termination
Resistive layer
Ceramic Substrate
W T
1001
L
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ASC_WFxxT & U_V01
DEC - 2017
Approval Sheet
MARKING
3-digits marking for 0603 size
WFxx T/ U has same marking rule as WRxx ±1%.
Nominal resistance
1.E-24 series
2.E-96 series
As
0603 WR06X
5%.
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
CODE
R_value
CODE
R_value
Description
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
01
02
03
04
05
06
07
08
09
10
11
12
100
102
105
107
110
113
115
118
121
124
127
130
13
14
15
16
17
18
19
20
21
22
23
24
133
137
140
143
147
150
154
158
162
165
169
174
25
26
27
28
29
30
31
32
33
34
35
36
178
182
187
191
196
200
205
210
215
221
226
232
37
38
39
40
41
42
43
44
45
46
47
48
237
243
249
255
261
267
274
280
287
294
301
309
49
50
51
52
53
54
55
56
57
58
59
60
316
324
332
340
348
357
365
374
383
392
402
412
61
62
63
64
65
66
67
68
69
70
71
72
422
432
442
453
464
475
487
499
511
523
536
549
73
74
75
76
77
78
79
80
81
82
83
84
562
576
590
604
619
634
649
665
681
698
715
732
85
86
87
88
89
90
91
92
93
94
95
96
750
768
787
806
825
845
866
887
909
931
953
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 976 the R is used as a digit. For values of 100 or greater, the
first 3 digits are significant, the fourth digit indicates the number of multiple to follow.
Example
RESISTANCE
4-digits marking
100
1000
6800
6801
47000
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”.
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ASC_WFxxT & U_V01
DEC - 2017
Approval Sheet
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.
Page 5 of 10
ASC_WFxxT & U_V01
DEC - 2017
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