Walsin Technology Corporation
FEATURE
1. High power rating and compact size
2. High reliability and stability
3. Reduced size of final equipment
4. Lead free product is upon customer requested.
APPLICATION
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•
•
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Power supply
PDA
Digital meter
Computer
Automotives
Battery charger
DC-DC power converter
Telecom
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 a Lead-tin or Tin (Pb free) alloy.
Fig 1. Construction of a 1218 Chip-R
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QUICK REFERENCE DATA
Item
Series No.
Size code
Resistance Tolerance
Resistance Range
TCR (ppm/°C) :
10Ω≤ Rn < 1MΩ
General Specification
WR18
1218(3248)
±5%
(E24);
±1%
(E24+E96)
1Ω ~ 10MΩ, Jumper (0Ω)
±
100 ppm/°C
±
200 ppm/°C
1W
200V
400V
55/155/56
1Ω≤ Rn < 9.76Ω& 1MΩ≤ Rn < 10MΩ
Max. dissipation at T
amb
=70°C
Max. Operation Voltage (DC or RMS)
Max. Overload 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
RCWV
=
Rated Power
×
Resistance Value
or Max. RCWV listed above, whichever is lower.
Mechanical Data
Symbol
L
W
T
Tt
Tb
Dimensions (mm)
3.05±0.15
4.60±0.20
0.55±0.10
0.45±0.25
0.50±0.25
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Marking
Each resistor is marked with a four-digit code on the protective coating to designate the nominal
resistance value.
Example:
1R00 = 1Ω
1001 = 1000Ω
FUNCTIONAL DESCRIPTION
Product characterization
Standard values of nominal resistance are taken from the E96 & E24 series for resistors with a tolerance of
±5%
&
±1%.
The values of the E24/E96 series are in accordance with “IEC publication 60063”.
Derating curve
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.
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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 245°C during 3 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 .
WR18
Size code
WR18 : 1218
X
Type code
X : Normal
472_
Resistance code
E24 : 2 significant digits followed
by no. of zeros and a blank
4.7Ω
10Ω
220Ω
Jumper
=4R7_
=100_
=221_
=000_
J
Tolerance
J :
±5%
F :
±1%
P : Jumper
Q
Packaging code
Q : 10” Reel taping
L
Termination code
L
=
Sn base (lead
free)
(“_” means a blank)
E96 : 3 significant digits followed
by no. of zeros
102Ω
37.4KΩ
=1020
=3742
Reeled tape packaging
: 12mm width plastic tape taping 3,000pcs per reel.
TEST AND REQUIREMENTS(JIS C 5201-1 : 1998)
Essentially all tests are carried out according to the schedule of IEC publication 115-8, category
LCT/UCT/56
(rated
temperature range :
Lower Category Temperature, Upper Category Temperature;
damp heat, long term, 56 days). The
testing also meets the requirements specified by EIA, EIAJ and JIS.
The tests are carried out in accordance with IEC publication 68, "Recommended basic climatic and mechanical robustness
testing procedure for electronic components" and under standard atmospheric conditions according to IEC 60068-1,
subclause 5.3. Unless otherwise specified, the following value supplied :
Temperature: 15°C to 35°C.
Relative humidity: 45% to 75%.
Air pressure: 86kPa to 106 kPa (860 mbar to 1060 mbar).
All soldering tests are performed with midly activated flux.
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