WF12G, WF08G, WF06G, WF04G
±
1%,
±
5%,
11M ~100M
High ohmic chip resistors
Size 1206, 0805, 0603, 0402
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FEATURE
1. Small size and light weight
2. High reliability and stability
3. Reduced size of final equipment
4. High precision
5. Higher component and equipment reliability
6. 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. Consctruction of Chip-R
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QUICK REFERENCE DATA
Item
Series No.
Size code
Resistance Tolerance
Resistance Range
TCR (ppm/°C)
Max. dissipation at T
amb
=70°C
Max. Operation Voltage (DC or RMS)
Climatic category (IEC 60068)
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
1/4 W
200V
WF12G
1206 ( 3216 )
General Specification
WF08G
0805 ( 2125 )
±1%, ±5%
10MΩ < R
≤
100MΩ
≤ ±
200 ppm/°C
1/8 W
150V
55/155/56
1/10 W
50V
WF06G
0603 ( 1608 )
WF04G
0402 ( 1005 )
±5%
10MΩ < R
≤
30MΩ
( E24 series)
≤ ±
300 ppm/°C
1/16W
50V
RCWV
=
Rated Power
×
Resistance Value
or Max. RCWV listed above, whichever is lower.
DIMENSIONS(unit : mm)
series
L
W
Tt
Tb
T
WF12G
3.10
±
0.15
1.60
±
0.15
0.50
±0.25
0.50
±
0.25
0.55
±
0.10
WF08G
2.00
±
0.10
1.25
±
0.10
0.40
±
0.20
0.40
±
0.20
0.50
±
0.15
WF06G
1.60
±
0.10
0.80
±
0.10
0.30
±
0.10
0.30
±
0.15
0.45
±
0.15
WF04G
1.00
±
0.05
0.50
±
0.05
0.20
±
0.10
0.25
±
0.10
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 M
186
=
18 M
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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
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. 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
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CATALOGUE NUMBERS
The resistors have a catalogue number starting with :
WF06
Size code
WF12
WF08
WF06
WF04
: 1206
: 0805
: 0603
: 0402
Type code
G : High ohmic >10MΩ
1206 size=0.25W
0805 size=0.125W
0603 size=0.10W
G
226_
Resistance code
5% E24:
2 significant digits
followed by no. of zeros
and a blank
11MΩ
22MΩ
30MΩ
=116_
=226_
=306_
J
Tolerance
J :
±5%
F :
±1%
T
Packaging code
T
B
: 7” Reeled taping
: Bulk
L
Termination code
L
=
Sn base (lead
free)
(“_” means a blank)
1%, E24+E96:
3 significant
digits followed by no. of
zeros
100Ω
37.4KΩ
=1000
=3742
1.
2.
Reeled tape packaging
Bulk packaging
: 8mm width paper taping 5000pcs per 7” reel for 1206, 0805, 0603 ( 10,000pcs for 0402 )
: 5000pcs per polybag
TEST AND REQUIREMENTS(JIS C 5201-1 : 1998)
TEST
Temperature
Coefficient of
Resistance (T.C.R)
Clause 4.8
PROCEDURE
Natural resistance change per change in degree centigrade.
REQUIREMENT
Refer to quick reference data for
T.C.R specification.
R
2
−
R
1
×
10
6
R
1
(
t
2
−
t
1
)
(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.
Short time overload
(S.T.O.L)
Clause 4.13
Solderability
Clause 4.17
Resistance to
soldering
heat(R.S.H)
Clause 4.18
Permanent resistance change after a 5 second application of a No visible damage.
voltage 2.5xU
R
or max. Overload voltage, whichever is less.
∆R/R
max. J:≦
±(2%+0.1Ω)
F:≦
±(1%+0.05Ω)
Un-mounted chips completely immersed for 2±0.5 second in a SAC good tinning (>95% covered)
solder bath at 235℃±5℃.
no visible damage
Un-mounted chips completely immersed for 10±1second in a SAC No visible damage.
solder bath at 260℃±5ºC
∆R/R
max. J:≦
±(1%+0.1Ω)
F:≦
±(0.5%+0.05Ω)
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