Approval sheet
Page 1 of 7 ASC_WFxxG_V12 Apr.2011
WF12G, WF08G, WF06G, WF04G
±
±±
±1%, ±
±±
±5%,
11MΩ~100MΩ
High ohmic 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_WFxxG_V12 Apr.2011
FEATURE
1. Small size and light weight
2. High reliability and stability
3. Reduced size of final equipment
4. Higher component and equipment reliability
5. RoHS compliant and lead free products.
APPLICATION
• Power supply
• PDA
• Digital meter
• Computer
• Palmtop computers
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 paste that is applied to the top surface of the substrate. The
composition of the paste 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
ease of soldering the outer layer of these end terminations is Tin (lead free) alloy.
Fig 1. Construction of Chip-R
Approval sheet
Page 3 of 7 ASC_WFxxG_V12 Apr.2011
QUICK REFERENCE DATA
Item General Specification
Series No. WF12G WF08G WF06G WF04G
Size code 1206 ( 3216 ) 0805 ( 2125 ) 0603 ( 1608 ) 0402 ( 1005 )
Resistance Tolerance ±1%, ±5% ±5%
Resistance Range 10MΩ < R ≤ 100MΩ 10MΩ < R ≤ 30MΩ
( E24 series)
TCR (ppm/°C) ≤ ± 200 ppm/°C ≤ ± 300 ppm/°C
Max. dissipation at T
amb
=70°C 1/4 W 1/8 W 1/10 W 1/16W
Max. Operation Voltage (DC or RMS) 200V 150V 50V 50V
Climatic category (IEC 60068) 55/155/56
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)
series
WF12G WF08G WF06G WF04G
L
3.10 ± 0.15
2.00 ± 0.10
1.60 ± 0.10
1.00 ± 0.05
W
1.60 ± 0.15
1.25 ± 0.10
0.80 ± 0.10
0.50 ± 0.05
Tt
0.50 ±0.25
0.40 ± 0.20
0.30 ± 0.10
0.20 ± 0.10
Tb
0.50 ± 0.25
0.40 ± 0.20
0.30 ± 0.15
0.25 ± 0.10
T
0.55 ± 0.10
0.50 ± 0.15
0.45 ± 0.15
0.35 ± 0.05
MARKING
3-digits marking
Each resistor is marked with a three digits code on the protective coating to designate the nominal resistance
value. For values up to 9.1 the R is used as a decimal point. For values of 10.0 or greater the first 2 digits
apply to the resistance value and third indicate the number of zeros to follow.
Example
306 = 30 MΩ
186 = 18 MΩ
Approval sheet
Page 4 of 7 ASC_WFxxG_V12 Apr.2011
FUNCTIONAL DESCRIPTION
Product characterization
Standard values of nominal resistance are taken from the E96 & E24 series for resistors with a tolerance of
±5%. 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
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. 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 below. WF04G is not guaranteed with wave soldering process due to its 0402 size.
Approval sheet
Page 5 of 7 ASC_WFxxG_V12 Apr.2011
CATALOGUE NUMBERS
The resistors have a catalogue number starting with :
WF06 G 226_ J T L
Size code
WF12 : 1206
WF08 : 0805
WF06 : 0603
WF04 : 0402
Type code
G : High ohmic >10MΩ
1206 size=0.25W
0805 size=0.125W
0603 size=0.10W
Resistance code
5% E24: 2 significant digits
followed by no. of zeros
and a blank
11MΩ =116_
22MΩ =226_
30MΩ =306_
(“_” means a blank)
1%, E24+E96: 3 significant
digits followed by no. of
zeros
100Ω =1000
37.4KΩ =3742
Tolerance
J : ±5%
F : ±1%
Packaging code
T : 7” Reeled taping
B : Bulk
Termination code
L = Sn base (lead
free)
1. Reeled tape packaging : 8mm width paper taping 5000pcs per 7” reel for 1206, 0805, 0603 ( 10,000pcs for 0402 )
2. Bulk packaging : 5000pcs per polybag
TEST AND REQUIREMENTS(JIS C 5201-1 : 1998)
TEST PROCEDURE REQUIREMENT
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
t
2
: Test temperature.
Refer to quick reference data for
T.C.R specification.
Short time overload
(S.T.O.L)
Clause 4.13
Permanent resistance change after a 5 second application of a
voltage 2.5xU
R
or max. Overload voltage, whichever is less. No visible damage.
∆R/R max. J:≦ ±(2%+0.1Ω)
F:≦ ±(1%+0.05Ω)
Solderability
Clause 4.17
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
Resistance to
soldering
heat(R.S.H)
Clause 4.18
Un-mounted chips completely immersed for 10±1second in a SAC
solder bath at 260℃±5ºC No visible damage.
∆R/R max. J:≦ ±(1%+0.1Ω)
F:≦ ±(0.5%+0.05Ω)
Approval sheet
Page 6 of 7 ASC_WFxxG_V12 Apr.2011
TEST PROCEDURE REQUIREMENT
Temperature cycling
Clause 4.19
1. 30 minutes at -55°C±3°C,
2. 2~3 minutes at 20°C+5°C-1°C,
3. 30 minutes at +155°±3°C,
4. 2~3 minutes at 20°C+5°C-1°C,
Total 5 continuous cycles.
No visible damage.
∆R/R max. J≦ ±(1%+0.1Ω)
F≦ ±(0.5%+0.05Ω)
Load life
(endurance)
Clause 4.25
1000 +48/-0 hours, loaded with RCWV or Vmax in chamber
controller 70±2ºC, 1.5 hours on and 0.5 hours off No visible damage.
∆R/R max. J≦ ±(3%+0.1Ω)
F≦ ±(1%+0.05Ω)
Load life in Humidity
Clause 4.24
1000 +48/-0 hours, loaded with RCWV or Vmax in humidity chamber
controller at 40°C±2°C and 90~95% relative humidity, 1.5hours on
and 0.5 hours off
No visible damage.
∆R/R max. J≦ ±(3%+0.1Ω)
F≦ ±(1%+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. ±(1%+0.10Ω)
Adhesion
Clause 4.32
Pressurizing force: 5N, Test time: 10±1sec. No remarkable damage or
removal of the terminations.
Insulation Resistance
Clause 4.6
Apply the maximum overload voltage (DC) for 1minute R≧10GΩ
Dielectric Withstand
Voltage
Clause 4.7
Apply the maximum overload voltage (AC) for 1 minute No breakdown or flashover
Approval sheet
Page 7 of 7 ASC_WFxxG_V12 Apr.2011
PACKAGING
Paper Tape specifications (unit :mm)
Series No. A B W F E
WF12G 3.60±0.20 2.00±0.20 8.00±0.30 3.50±0.2 1.75±0.10
WF08G 2.40±0.20 1.65±0.20 8.00±0.30 3.50±0.2 1.75±0.10
WF06G 1.90±0.20 1.10±0.20 8.00±0.30 3.50±0.2 1.75±0.10
WF04G 1.20±0.10 0.70±0.10 8.00±0.30 3.50±0.2 1.75±0.10
Series No. P1 P0 ΦD T
WF12G 4.00±0.10 4.00±0.10
WF08G 4.00±0.10 4.00±0.10 Max. 1.0
WF06G 4.00±0.10 4.00±0.10 0.65±0.1
WF04G 2.00±0.10 4.00±0.10
1.0 0.0
50.1
+
−
Φ
0.40±0.05
Reel dimensions
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/reel for 1206, 0805, 0603 ( 10,000 pcs/reel for 0402 )
