Approval sheet
Page 1 of 7 ASC_WW25P-20P-12P_V08 Sep.2010
WW25P, WW20P, WW12P
±
±±
±1%, ±
±±
±5% 47mΩ~976mΩ
High Power Low Ohm Chip Resistors
Size 2512 2W, 2010 1W, 1206 1/2W
*Contents in this sheet are subject to change without prior notice.
Approval sheet
Page 2 of 7 ASC_WW25P-20P-12P_V08 Sep.2010
FEATURE
1. High power rating and compact size
2. High reliability and stability
3. Reduced size of final equipment
4. RoHS compliant and lead free products.
APPLICATION
• Power supply
• PDA
• Digital meter
• Computer
• Automotives
• Battery charger
• DC-DC power converter
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
Approval sheet
Page 3 of 7 ASC_WW25P-20P-12P_V08 Sep.2010
QUICK REFERENCE DATA
Item General Specification
Series No. WW25P WW20P WW12P
Size code 2512 (6432) 2010 (5025) 1206 (3216)
Resistance Tolerance ±1%, ±5%
Resistance Range 0.047Ω ~ 0.976Ω
TCR (ppm/°C) 100mohm ~ 976mohm
47mohm ~ 97.6mohm ±100ppm
±150ppm ±100ppm
±150ppm ±100ppm
±200ppm
Max. dissipation at T
amb
=70°C 2 W 1 W 1/2 W
Max. Operation Voltage (DC or RMS) 300V 200V 200V
Max. Overload Voltage (DC or RMS) 500V 400V 400V
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.
3. 2W loading with total solder-pad and trace size of 300 mm
2
4. Resistance value will be changed by soldering condition and design of soldering pad, please design products in
consideration of this change of resistance value.
MECHANICAL DATA
Unit: mm
Symbol WW25P WW20P WW12P
L 6.30 ± 0.20
5.00 ± 0.20
3.10 ± 0.15
W 3.10 ± 0.20 2.50 ± 0.20 1.60 ± 0.15
T 0.60 ± 0.15 0.60 ± 0.10 0.55 ± 0.10
Tt 0.60 ± 0.25 0.60 ± 0.25 0.50 ± 0.25
Tb 1.80 ± 0.25 0.60 ± 0.25 0.50 ± 0.25
Approval sheet
Page 4 of 7 ASC_WW25P-20P-12P_V08 Sep.2010
Recommended Solder Pad Dimensions
D
W
L
MARKING
Each resistor is marked with a four-digit code on the protective coating to designate the nominal resistance
value.
Example:
R100 = 0.100Ω
R910 = 0.910Ω
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
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.
Type W D L
WW25P 3.7mm 2.45mm 7.6mm
Approval sheet
Page 5 of 7 ASC_WW25P-20P-12P_V08 Sep.2010
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.
WW25 P R100 J T L
Size code
WW25 : 2512
WW20 : 2010
WW12 : 1206
Type code
P :Power
2512 size=2 watt
2010 size=1 watt
1206 size=0.5 watt
Resistance code
E96 +E24:
“R” is first digit followed by 3
significant digits.
e.g.: 0.1ohm = R100
0.047ohm = R047
0.56ohm = R560
Tolerance
J : ±5%
F : ±1%
Packaging code
T : 7” Reel taping Termination code
L = Sn base (lead
free)
Tape packaging WW12 : 8mm width paper taping 5,000pcs per reel.
WW25；WW20
:
12mm width plastic taping 4,000pcs per reel.
Approval sheet
Page 6 of 7 ASC_WW25P-20P-12P_V08 Sep.2010
TEST AND REQUIREMENTS
Basic specification : JIS C 5201-1 : 1998
TEST PROCEDURE REQUIREMENT
Clause 4.8
Temperature
Coefficient of
Resistance (TCR )
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
Refer to quick reference data for T.C.R
specification
Clause 4.13
Short time
overload
Permanent resistance change after 5 second application
of a power 5.0 times of rated power or the maximum
overload voltage specified in the above list, whichever is
less.
∆R/R max. J:≦ ±(2%+0.5mΩ)
F:≦ ±(1%+0.5mΩ)
Clause 4.18
Resistance to
soldering
heat(R.S.H)
Un-mounted chips completely immersed for 10±1second
in a SAC solder bath at 260℃±5ºC No visible damage
∆R/R max. J:≦ ±(1%+0.5mΩ)
F:≦ ±(0.5%+0.5mΩ)
Clause 4.17
Solderability Un-mounted chips completely immersed for 2±0.5second
in a SAC solder bath at 235℃±5℃ Good tinning (>95% covered)
No visible damage
Clause 4.19
Temperature
cycling
30 minutes at -55°C±3°C, 2~3 minutes at 20°C+5°C-1°C,
30 minutes at +155°C±3°C, 2~3 minutes at
20°C+5°C-1°C, total 5 continuous cycles
No visible damage
∆R/R max. J≦ ±(1%+1mΩ)
F ≦±(0.5%+1mΩ)
Clause 4.25
Load life
(endurance)
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%+0.5mΩ)
F ≦±(1%+0.5mΩ)
Clause 4.24
Load life in
Humidity
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%+0.5mΩ)
F ≦±(1%+0.5mΩ)
Clause 4.33
Bending strength Resistors mounted on a 90mm glass epoxy resin
PCB(FR4); bending : 2 mm(2512;2010)
3mm(1206), once for 10 seconds
No visible damage
∆R/R max. J ≦±(1%+1mΩ)
F ≦±(0.5%+1mΩ)
Clause 4.32
Adhesion 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 1minutes R 10GΩ≧
Dielectric Withstand
Voltage
Clause 4.7
Apply the maximum overload voltage (AC) for 1 minutes
No breakdown or flashover
Approval sheet
Page 7 of 7 ASC_WW25P-20P-12P_V08 Sep.2010
PACKAGING
Paper Tape(WW12P) & Plastic Tape(WW25P;WW20P) specifications (unit :mm)
Series No. A B W F E
WW25P 6.90±0.20 3.60±0.20
WW20P 5.50±0.20 2.80±0.20 12.00±0.30 5.50±0.10
WW12P 3.60±0.20 2.00±0.20 8.00±0.30 3.50±0.20
1.75±0.10
Series No. P1 P0 ΦD T
WW25P
WW20P Max. 1.2
WW12P
4.00±0.10 4.00±0.10
1.0 0.0
50.1
+
−
Φ
Max. 1.0
Reel dimensions
(unit : mm)
Reel / Tape A B C D
7” reel for 12mm tape 9.00±0.50
7” reel for 8mm tape Φ178.0±2.0 Φ60.0±1.0 13.0±0.2 12.4±1.00
