WF20M / WF12M / WF08M / WF06M
0/-20% and 0/-30%
Trimmable chip resistors
Size 2010, 1206, 0805, 0603
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WFxxM Trimmable_V11
Apr.2010
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FEATURE
1. Reduced size of final equipment
2. Lower assembly costs
3. Higher component and equipment reliability
4. Improved performance at high frequency
5. Low noise, when not trimmed
6. RoHS compliant and Lead free products
APPLICATION
•
•
•
•
Consumer electrical equipment
Automotive application
EDP, Computer application
Telecom application
DESCRIPTION
The resistors are constructed on a high-grade ceramic body (aluminum oxide). Internal metal electrodes are
added at each and connected by a resistive paste, which is applied to the substrate. The composition of the
paste is adjusted to give the approximate resistance required.
The resistive layer is converted with a transparent protective coating. Finally the two external end terminations
are added. For case of soldering the outer of theses end terminations is Tin (lead free) alloy.
Fig 1. Consctruction of Trimmable Chip-R
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QUICK REFERENCE DATA
Item
Series No.
Size code
Resistance Range
TCR (ppm/°C)
≥10Ω
<10Ω
Max. dissipation at T
amb
=70°C
Max. Operation Voltage (DC or RMS)
Max. Over Load 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
1/2W
200V
400V
≤ ±
200 ppm/°C
-300~+500 ppm/°C
1/4 W
200V
400V
55/155/56
1/8W
100V
200V
1/10W
50V
100V
WF20M
2010 (5020)
General Specification
WF12M
1206 (3216)
WF08M
0805 (2012)
WF06M
0603 (1608)
1Ω ~ 10MΩ Tolerance 0/-10% and 0/-20% and 0/-30% (E24 series)
RCWV
=
Rated Power
×
Resistance Value
or Max. RCWV listed above, whichever is lower.
DIMENSIONS(unit : mm)
WF20M
L
W
T
Tb
Tt
5.00
±
0.20
2.50
±
0.20
0.55
±
0.15
0.65
±
0.25
0.60
±
0.25
WF12M
3.10
±
0.10
1.60
±
0.10
0.60
±
0.15
0.45
±
0.20
0.50
±
0.20
WF08M
L
W
T
Tb
Tt
2.00
±
0.10
1.25
±
0.10
0.50
±
0.15
0.40
±
0.20
0.40
±
0.20
WF06M
1.60
±
0.10
0.80
±
0.10
0.45
±
0.15
0.30
±
0.20
0.30
±
0.10
MARKING
No marking for Trimmable Chip Resistor
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WFxxM Trimmable_V11
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TRIMMING INTRODUCTIONS
Typical value for a YAG-laser;
cutting speed
laser power
bite size
: 10-200 mm/sec,
: 1-6 Watt,
: 3~10µm ( = speed / Q_rate , Bite Size is the distance each laser spot moving and
influence the trimming accuracy)
maximum trimming length : 60% of resistive film width, minimum distance from end termination to trimming
cut : 0.20mm, minimum distance between cuts (double-cut) : 0.5mm
Protection of the laser cut
by epoxy-fenol lacquers, epoxy resins or silicon alkyd-resins.
This is necessary for humidity test and stability under loaded.
FUNCTIONAL DESCRIPTION
Product characterization
Standard values of nominal resistance are taken from the E24 series for resistors with a tolerance of
±5%,
and E96 series for resistors with a tolerance of
±1%.
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.
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WFxxM Trimmable_V11
Apr.2010
00-S-R06-D
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
CATALOGUE NUMBERS
The resistors have a catalogue number starting with :
WF12
Size code
WF20
WF12
WF08
WF06
: 2010
: 1206
: 0805
: 0603
Type code
M : Trimmable
M
472_
Resistance code
E24 : 2 significant digits
followed by no. of
zeros and a blank
4.7Ω
10Ω
220Ω
=4R7_
=100_
=221_
M
Tolerance
X : 0/-30%
Y : 0/-20%
Z : 0/-10%
T
Packaging code
T
B
: 7” Reeled taping
: Bulk
L
Termination code
L
=
Sn base (lead
free)
(“_” means a blank)
1.
Reeled tape packaging : WF12M / WF08M / WF06M - 8mm width paper taping 5000pcs per reel.
: WF20M – 12mm width paper taping 4000pcs per reel.
2.
Bulk packaging
: WF12M / WF08M / WF06M - 5000pcs per polybag
: WF20M – 4000pcs per polybag
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WFxxM Trimmable_V11
Apr.2010
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