OARS Open Air Sense Resistors Metal Alloy Strip • • • • • • Greater than 1 Watt rating for 2512 pad design Zero ohm jumper available Economical low value SMT Resistance values 2mΩ to 50mΩ ±1% or ±5% tolerance (0.002Ω 5% only) Open air design provides cooler operation Electrical Data IRC Type Power Rating (watts) Available Resistance (ohms) OARS-1 3W @ 70°C .002, .003, .004, .005, .010, .015 .020, .022, .025, .030, .040, .050 *Contact factory for unlisted resistance values between 0.002 & 0.050 ohms. Features: Applications: • Superior thermal expansion cycling • Current sensing • Flameproof • Feedback • Inductance less than 10 nanohenries • Low inductance • Lead flexible for thermal expansion • Surge and pulse • AC applications (please contact the factory) Physical Data Recommended Landing Pad Size L 0.369 W 0.121 0.127 0.121 0.126 D T H Dimensions (Inches and (mm)) IRC Type L H T D W 0.440 ±0.015 0.120 ±0.030 0.093 ±0.010 0.190 ±0.030 0.125 ±0.015 (11.18 ±0.381) (3.05 ±0.762) (2.36 ±0.254) (4.83 ±0.762) (3.175 ±0.381) OARS-1 0.002Ω 0.455 ±.015 0.150 ±0.030 0.093 ±0.010 0.185 ±0.030 0.140 ±0.015 (11.56 ±.381 ) (3.51 ±0.762) (2.36 ±0.254) (4.70 ±0.762) (3.56 ±0.381) OARS-1 0.003Ω 0.440 ±.015 0.138 ±0.030 0.093 ±0.010 0.190 ±0.030 0.125 ±0.015 (11.18 ±.381 ) (3.51 ±0.762) (2.36 ±0.254) (4.83 ±0.762) (3.175 ±0.381) OARS-1 General Note IRC reserves the right to make changes in product specification without notice or liability. All information is subject to IRC’s own data and is considered accurate at time of going to print. Wire and Film Technologies Division • 4222 South Staples Street • Corpus Christi Texas 78411 USA Telephone: 361 992 7900 • Facsimile: 361 992 3377 • Website: www.irctt.com A Subsidiary of TT electronics plc June 2009 Issue Page 1 of 4 OARS Open Air Sense Resistors Metal Alloy Strip Environmental Data Test Spec: AEC Q200 2m - 3m 4m - 15m >15m TCR +125 to -55°C 240ppm 40ppm 40ppm Thermal Shock <0.75% <0.75% <0.75% High Temperature Exposure 125°C <1.75% <0.5% <1.0% Temperature Cycling: -40 to +125°C <1.0% <1.0% <0.75% Operational Life <2.0% <1.0% <1.0% Baised Humidity <0.75% <0.5% <0.5% Mechanical Shock <1.5% <1.0% <1.0% Vibration <1.0% <1.0% <1.0% <1.0 <2.5% <2.0 Moisture Resistance Terminal Strength Meets JIS-C-6429 Solvent Resistance Meets MIL-STD-202 Method 215 Solderability Meets J-STD-002 Method B Power Derating Curve 3.5 Note: The power derating curve is a guidance based on a conservative design model. The OARS is a solid metal alloy construction that can withstand significantly greater operating temperatures than conservative design models permit. The resistive alloys can withstand temperatures in exess of 350°C. Therefore, the system thermal design is a more significant design parameter due to the heat limitations of solder joints and/or circuit board substrate materials. Refer to additional information below. Power Rating (watts) 3.0 2.5 2.0 1.0 0.0 25 60 95 130 165 195 225 Ambient Temperature (°C) The thermal image (not a simulation) to the left is of an OARS 10 mΩ running at 2 Watts, which exceeds the 1 Watt conservative model. Notice the hotpsot is nearly 200°C, but the solder joint is approximately 65°C (FR4 is rated for 130°C). The unique construction of the OARS isolates the hotspot from the circuit board material preventing damage. Additionally, the thermal energy is dissipated to the air instead of being conducted into the circuit board potentially causing a nearby power component to exceed its rating. The standard test circuit board consists of a four layer FR4 material with 2 ounce outer layers and 1 ounce inner layers, which is typical of many industry designs. Contact IRC for more details or for other thermal image test data for specific resistance values and power levels. Wire and Film Technologies Division • 4222 South Staples Street • Corpus Christi Texas 78411 USA Telephone: 361 992 7900 • Facsimile: 361 992 3377 • Website: www.irctt.com June 2009 Issue Page 2 of 4 OARS Open Air Sense Resistors Metal Alloy Strip Pulse/Surge Chart 70 Note: The high pulse surge capability of the OARS parts is attributed to the solid metal alloy construction. In many applications the cross-section of the OARS is greater than the cross-section of the board traces connecting the parts to the circuit board. Joules (watts-second) 60 50 40 Cross-Sectional area ranges from approximately 650 mils to 3600 mils. 30 20 10 0 0 10 20 30 40 50 60 Resistance (milli ohms) Tape Specifications G E D C B F A Dimensions (Inches and (mm)) IRC Type OARS A B C D E F G 0.17 ±0.003 0.461 ±0.003 0.945 ±0.010 0.453 ±0.004 0.069 ±0.004 0.315 ±0.004 0.157 ±0.004 (4.32 ±0.08) (11.7 ±0.08) (24.0 ±0.30) (11.5 ±0.10) (1.75 ±0.10) (8.0 ±0.10) (4.0 ±0.1) Ordering Data Sample Part No. OARS1 R005 J LF IRC Type OARS1 Power Rating in Watts Resistance Range (ohms) Tolerance F = ±1%, G = ±2%, J = ±5% RoHS Indicator LF indicates RoHS compliance Wire and Film Technologies Division • 4222 South Staples Street • Corpus Christi Texas 78411 USA Telephone: 361 992 7900 • Facsimile: 361 992 3377 • Website: www.irctt.com June 2009 Issue Page 3 of 4 OARS Open Air Sense Resistors Metal Alloy Strip IRC Solder Reflow Recommendations Sn-Pb Eutectic and Pb-Free Reflow Profiles tP TP Ramp-up Critical Zone TL to TP TL tL Temperature Tsmax Tsmin ts Preheat 25 Ramp-down t 25°C to Peak Time * Based on Industry Standards and IPC recommendations Profile Feature Sn-Pb Eutectic Assembly Pb-Free Assembly 3°C / second max. 3°C / second max. Preheat - Temperature Min (Tsmin) - Temperature Max (Tsmax) - Time (Tsmin to Tsmax) (ts) 100°C 150°C 60 -120 seconds 150°C 200°C 60 -180 seconds Time maintained above - Temperature (TL) - Time (tL) 183°C 60 - 150 seconds 217°C 60 - 150 seconds Peak Temperature (TP) See Table 1 See Table 2 Average Ramp-up rate (Tsmax to Tp) Time within 5°C of actual Peak Temperature (tp)2 Ramp-down Rate Time 25°C to Peak Temperature 10 - 30 seconds 20 - 40 seconds 6°C / second max. 6°C / second max. 6 minutes max. 8 minutes max. Note 1: All temperatures refer to topside of the package, measured on the package body surface. Note 2: Time within 5 °C of actual peak temperature (tp) specified for the reflow profiles is a “supplier” minimum and a “user” maximum. Note 1: Package volume excludes external terminals (balls, bumps, lands, leads) and/or non-integral heat sinks. Tabel 1: SnPb Eutectic Process Package Peak Reflow Temperatures Package Thickness Volume mm3 < 350 Volume mm3 ≥ 350 < 2.5 mm 240 +0/-5°C 225 +0/-5°C ≥ 2.5 mm 225 +0/-5°C 225 +0/-5°C Tabel 2: Pb-free Process Package Peak Reflow Temperatures Package Thickness Volume mm3 < 350 Volume mm3 350 - 2000 Volume mm3 > 2000 < 1.6 mm 260°C * 260°C * 260°C * 1.6 mm - 2.5 mm 260°C * 250°C * 245°C * ≥ 2.5 mm 250°C * 245°C * 245°C * Note 2: The maximum component temperature reached during reflow depends on package thickness and volume. The use of convection reflow processess reduces the thermal gradients between packages. However, thermal gradients due to differences in thermal mass of SMD packages may still exist. Note 3: Components intended for use in “leadfree” assembly process shall be evaluated using the “lead-free” peak temperature and profiles defined in Table 1, 2 and reflow profile whether or not lead-free. * Tolerance: The device manufacturer/supplier shall assure process compatibility up to and including the stated classification temperature at the rated MSL level. Wire and Film Technologies Division • 4222 South Staples Street • Corpus Christi Texas 78411 USA Telephone: 361 992 7900 • Facsimile: 361 992 3377 • Website: www.irctt.com June 2009 Issue Page 4 of 4