Approval sheet
WF12R, WF08R, WF06R
±
0.5%,
±
0.25%,
±
0.1%,
±
0.05%
TC25
High Precision Power Thin Film chip
resistors
Size 1206, 0805, 0603
*Contents in this sheet are subject to change without prior notice.
Page 1 of 8
ASC_WFxxR_V08
Mar.2012
Approval sheet
FEATURE
1. SMD metal film resistor
2. High reliability and stability of
±
0.5% and below per customer request
3. High performance of TCR: 25 ppm/K and below per customer request
4. High power rating
5. Low current noise
APPLICATION
1.
2.
3.
4.
5.
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 WFxxR
Page 2 of 8
ASC_WFxxR_V08
Mar.2012
Approval sheet
QUICK REFERENCE DATA
Item
Series No.
Size code
Resistance Tolerance
Resistance Range
4.7Ω ~ 1MΩ
( E24 +E192 )
TCR (ppm/°C)
Max. dissipation at T
amb
=70°C
Max. Operation Voltage (DC or RMS)
Max. Overload Voltage (DC or RMS)
Operation temperature
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
1/4W
200V
400V
WF12R
1206 ( 3216 )
General Specification
WF08R
0805 ( 2012 )
±0.5%, ±0.25%, ±0.1%, ±0.05%
4.7Ω ~ 1MΩ
( E24 +E192 )
+25 ~ -25 ppm/°C
1/8W
150V
300V
- 55~ +155’C
1/10W
75V
150V
4.7Ω ~ 680KΩ
( E24 +E192 )
WF06R
0603( 1608 )
RCWV
=
Rated Power
×
Resistance Value
or Max. RCWV listed above, whichever is lower.
3.
Tolerance
±0.05%
is upon requested
DIMENSIONS:(unit:mm)
Type
L
W
A
B
t
WF12R
3.05
±
0.15
1.55
±
0.15
0.40
±
0.20
0.40
±
0.20
0.55
±
0.15
WF08R
2.00
±
0.10
1.25
±
0.10
0.25
±
0.20
0.40
±
0.20
0.50
±
0.15
WF06R
1.55
±
0.10
0.80
±
0.10
0.25
±
0.15
0.30
±
0.15
0.45
±
0.15
Protective coat
t
B
A
End termination
Resistive layer
Ceramic Substrate
W T
1001
L
Page 3 of 8
ASC_WFxxR_V08
Mar.2012
Approval sheet
MARKING
3-digits marking for 0603 size
WFxxR has same marking rule as commodity ±1%.
3-digits marking（±1%
: 0603）
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 0805 size
Each resistor is marked with a four digits code on the protective coating to designate the nominal resistance
value of E24+E192. 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
4-digits marking
10Ω
10R0
12Ω
12R0
100Ω
1000
6800Ω
6801
47000Ω
4702
FUNCTIONAL DESCRIPTION
Product characterization
Standard values of nominal resistance are taken from the E24 & E192 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”.
Page 4 of 8
ASC_WFxxR_V08
Mar.2012
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.
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.
Fig 3. Infrared soldering profile for Chip Resistors
Page 5 of 8
ASC_WFxxR_V08
Mar.2012
Special Edition for Assessment Centres
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