WW25C WALSIN | Alldatasheet
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Technical content
Page 1 of 7 ASC_WW25C_V02 Feb.-2012 WW25C Thick Film Power Low Ohm Chip Resistors Size 2512, 1W *Contents in this sheet are subject to change without prior notice.
Page 2 of 7 ASC_WW25C_V02 Feb.-2012 FEATURE 1. High power rating and low range 2. High reliability and stability 3. Suitable for current sensing of small mobile devices 4. RoHS compliant & Lead free 5. Up side down mounting to minimize resistance drift after soldering APPLICATION
- Game equipment
- Mobile phone
- Battery pack
- Power supply
- DSC
- HDD
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 Tin (lead free) alloy. Fig 1. Construction of Chip-R
Page 3 of 7 ASC_WW25C_V02 Feb.-2012 QUICK REFERENCE DATA Item General Specification Series No. WW25C Size code 2512 ( 6332 ) Resistance Range 0.020 ΩΩ ΩΩ ~ 0.100 ΩΩ ΩΩ ( E24 +E96 ) TCR (ppm/ °° °°C) 0.020ΩΩ ΩΩ ~ 0.100 ΩΩ ΩΩ ±± ±±100 ppm Max. dissipation at T amb =70 °° °°C 1 W Max. Operation Current (DC or RMS) 3.1A ~ 7 A Operation temperature -55 ~ +125’C Note : 1. This is the maximum current that may be continuously supplied to the resistor element, see “IEC publication 60115-8” 2. Max. Operation current : So called RCWC (Rated Conti nuous Working Current) is determined by Value Resistance Power / Rated RCWC = MECHANICAL DATA(unit: mm) Symbol WW25C L 6.30 ±± ±± 0.20 W 3.20 ±± ±± 0.15 H 0.60 ±± ±± 0.15 c 1.10 ±± ±± 0.20 d 1.10 ±± ±± 0.20 L c c
Page 4 of 7 ASC_WW25C_V02 Feb.-2012 MARKING Each resistor is marked with a three-digit code on the substrate to designate the nominal resistance value. Example: R10 = 0.100 Ω 050 = 0.050 Ω 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”. De-rating 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. Resistive layer is on the bottom side as below !
Page 5 of 7 ASC_WW25C_V02 Feb.-2012 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 within lead-free solder bath. 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 resistor CATALOGUE NUMBERS The resistors have a catalogue number starting with . WW25 C R050 F T L Size code WW25 : 2512 Type code 2512, 1W Resistance code E96 +E24: R is first digit followed by 3 significant digits. 0.020 Ω = R020 0.100Ω = R100 0.025 Ω = R025 Tolerance J : ±5% F : ±1% Packaging code T : 7” Reel taping Termination code L = Sn base (lead free) /circle4 Reeled tape packaging WW25C: 12mm width embossed ta ping , 4,000pcs per reel.
Page 6 of 7 ASC_WW25C_V02 Feb.-2012 TEST AND REQUIREMENTS TEST PROCEDURE REQUIREMENT Temperature Coefficient of Resistance ( TCR ) Natural resistance change per change in degree centigrade. ( ) 121 12 10 ×− ttR RR (ppm/ °C) R 1 : Resistance at reference temperature R 2 : Resistance at test temperature t1 : 25 °C t2 : 125 °C Test temperature –55 ~ +125°C As defined in P.3 Short time overload ( STOL ) Sub-clause 4.13 Permanent resistance change after 2 second application of a current 2.5 times RCWC specified. ΔR/R max. ±1% no visible damage Resistance to soldering heat Sub-clause 4.18 Unmounted chips 10 ±0.5 seconds, 260 ±5ºC no visible damage Δ R/R max. ±1% Solderability Sub-clause 4.17 Termination Sn base (lead free) : Unmounted chip completely immersed in a lead free solder bath, good tinning (>95% covered) no visible damage Temperature cycling Sub-clause 4.19 1. 30 minutes at -55 °C ±3°C, 2. 2~3 minutes at room temperature, 3. 30 minutes at +125°±3°C, 4. 2~3 minutes at room temperature, Total 5 continuous cycles no visible damage ΔR/R max. ±1% Load life (endurance) Sub-clause 4.25.1 70 ±2ºC, 1000 hours, loaded with rated current, 1.5 hours on and 0.5 hours off ΔR/R max. ±5% no visible damage Steady state in Humidity sub-clause 4.24 1000hrs without current applied in humidity chamber controller at 40 °C ±2°C and 90~95% relative humidity ΔR/R max. ±5% no visible damage Bending strength Sub-clause 4.33 Resistors mounted on a 90mm glass epoxy resin PCB(FR4); bending : 1 mm, once for 10 seconds ΔR/R max. ±1% no visible damage Adhesion Sub-clause 4.32 Clause 4.32 5N, 10s No visible damage High temperature exposure Sub-clause 4.25.3 125’C no load, 1000hrs No visible damage ΔR/R max. ±5%
Page 7 of 7 ASC_WW25C_V02 Feb.-2012 PACKAGING Paper Tape specifications (unit :mm) Series No. A B W F E Series No. P1 P0 Φ D T 0 . 050 . 1+ Φ 1.10 ±0.15 Reel dimensions Symbol A B C D