WF25A WALSIN | Alldatasheet
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Page 1 of 7 ASC_WF25A_V02 APR - 2017 WF25A 1%, 5%, 3W Thick Film High Power Chip Resistors Size 2512 (6432) RoHS Compliant & Halogen free *Contents in this sheet are subject to change without prior notice.
Page 2 of 7 ASC_WF25A_V02 APR - 2017 FEATURE 1. Ultra high power rating and compact size 2. High reliability and stability 3. Reduced size of final equipment 4. RoHS compliant and Halogen free APPLICATION Power supply PDA Digital meter Computer Automotives Battery charger DC-DC power converter
DESCRIPTION
The resistors are constructed in a high grad e 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 an d 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. Construction of Chip-R
Page 3 of 7 ASC_WF25A_V02 APR - 2017 QUICK REFERENCE DATA Item General Specification Series No. WF25A Size code 2512 ( 6432 ) Resistance Tolerance & Range 5%: 1 - 1M ( E24 ), Jumper TCR (ppm/C) +25 ~ +155C 5%: ±200 ppm/C 1%: ±100 ppm/C Max. dissipation at Tamb=70C 3 W Operation temperature -55 ~ +155’C Note: Jumper is defined as max. 20mohm with rated current 12A! MECHANICAL DATA Symbol Dimensions (mm) L 6.400.20 W 3.100.20 T 1.100.20 Tt 0.450.25 Tb 1.800.25 1001
Page 4 of 7 ASC_WF25A_V02 APR - 2017 MARKING For 1%, e ach resistor is marked with a four -digit code on the protective coating to designate the nominal resistance value. For 5%, e ach resistor is marked with a three-digit code on the protective coating to designate the nominal resistance value. For Jumper, it is marked with a four-digit code 0000. FUNCTIONAL DESCRIPTION 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.
Page 5 of 7 ASC_WF25A_V02 APR - 2017 SOLDERING CONDITION The robust construction of chip resistors allows them to be completely immersed in a solder bath of 260C 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 235C 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 WF25A CATALOGUE NUMBERS The resistors have a catalogue number starting with . WF25 A 1001 F Z L Size code WF25 : 2512 Type code A : 3W Resistance code 5%, two digits followed by 3 significant digit 100 = 101 Jumper = 000 1%, three digits followed by 4 significant digit 100 = 1000 Tolerance J : 5% F : 1% P : Jumper Packaging code Z : 7” reel taped 3,000pcs! Termination code L = Sn base (lead free) Reeled tape packaging : 12mm width plastic emboss taping 3,000pcs per 7” reel.
Page 6 of 7 ASC_WF25A_V02 APR - 2017 TEST AND REQUIREMENTS(JIS C 5201-1 : 1998) Essentially all te sts 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. TEST PROCEDURE REQUIREMENT Temperature Coefficient of Resistance(T.C.R) Clause 4.8 Natural resistance change per change in degree centigrade. 121 12 10 ttR RR (ppm/C) t1 : 25°C R1 : Resistance at reference temperature 25°C R2 : Resistance at test temperature 155°C Refer to “QUICK REFERENCE DATA” Short time overload (S.T.O.L) Clause 4.13 Permanent resistance change after a 5second application of a 5 times rated power. J: R/R max. ±(2%+0.5m) F: R/R max. ±(1%+0.5m) Solderability Clause 4.17 Un-mounted chips completely immersed for 3±0.5 second in a SAC solder bath at 245℃±2℃ good tinning (>95% covered) no visible damage Resistance to soldering heat(R.S.H) Clause 4.18 Un-mounted chips completely immersed for 10±1 second in a SAC solder bath at 260℃±5ºC no visible damage J: R/R max. ±(1%+0.5m) F: R/R max. ±(0.5%+0.5m) Temperature cycling Clause 4.19 30 minutes at -55C3C, 2~3 minutes at 20°C+5°C-1°C, 30 minutes at +155C3C, 2~3 minutes at 20°C+5°C-1°C, total 5 continuous cycles no visible damage J: R/R max. ±(1%+0.5m) F: R/R max. ±(0.5%+0.5m) Load life (endurance) Clause 4.25 1000 +48/-0 hours, loaded with RCWV or Vmax in chamber controller 70±2ºC, 1.5 hours on and 0.5 hours off J: R/R max. ±(3%+0.5m) F: R/R max. ±(1%+0.5m) Load life in Humidity Clause 4.24 1000 +48/-0 hours, loaded with RCWV or Vmax in humidity chamber controller at 40 C2C and 90~95% relative humidity, 1.5hours on and 0.5 hours off J: R/R max. ±(3%+0.5m) F: R/R max. ±(1%+0.5m) Bending strength Clause 4.33 Resistors mounted on a 90mm glass epoxy resin PCB(FR4); bending : 2mm once for 10 seconds no visible damage J: R/R max. ±(1%+0.5m) F: R/R max. ±(0.5%+0.5m) Insulation Resistance Clause 4.6 Test voltage 100+/-15V between termination and overcoat Min 1000Mohm
Page 7 of 7 ASC_WF25A_V02 APR - 2017 PACKAGING Plastic Tape specifications (unit: mm) TYPE A B W F E TYPE P1 P0 D T WF25A 4.00±0.10 4.00±0.10 1.0 0.050.1 Max. 1.5 Reel dimensions Symbol A B C D Taping quantity - Chip resistors 3,000 pcs per reel.