Molded Surface Mount Wirewound Resistor WSM Series • • • • • Flexible Terminations All welded construction Ideal for automatic pick and place Lead free, RoHS compliant construction available Contact factory for ohmic values above published ranges Electrical Data IRC Type Power Rating Resistance Maximum Working Range @ 70°C Voltage (watts) (ohms) (volts) WSM-1 1W 0.01 to 1K WSM-2 2W 0.01 to 2K WSM-3 3W 0.01 to 3K √P x R TCR (ppm/°C) 0.1Ω - <10Ω: 100 ≥1Ω: 20 Resistance Standard Tolerance Values (%) *1, 2, 5, 10 E24 Preferred Ambient Temperature (°C) -55 to 155 *Note: 5% or 10% preferred below 0.1 ohms. CONSTRUCTION A high purity ceramic substrate is assembled with interference fit end caps to which are welded the terminations. The resistive element is wound on the substrate and welded to the caps. The unit is then molded. FLAMMABILITY The resistor coating is categorized as flame retardant epoxy under UL-94. SOLVENT RESISTANCE The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. MARKING WSM resistors are legend marked with type, value and tolerance. 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 WSM Series Issue December 2008 Sheet 1 of 3 Molded Surface Mount Wirewound Resistor Recommended Pad Sizes B C A B Dimensions (Inches & mm)) Type A B C D WSM-1 0.115 (2.9) 0.100 (2.6) 0.189 (2.9) 0.389 (9.9) WSM-2 0.134 (3.4) 0.158 (4.0) 0.237 (6.0) 0.552 (14.0) WSM-3 0.134 (3.4) 0.178 (4.5) 0.434 (11.0) 0.788 (20.0) Physical Data L L l l W W W W H H Dimensions (Inches & mm)) Type L l W w H WSM-1 0.310 max (7.9 max) 0.100 nom (2.54 nom) 0.275 max (7.0 max) 0.165 max (4.2 max) 0.155 max (3.94 max) WSM-2 0.473 max (12 max) 0.122 nom (3.1 nom) 0.413 max (10.5 max) 0.260 max (6.6 max) 0.217 max (5.5 max) WSM-3 0.709 max (18 max) 0.122 nom (3.1 nom) 0.630 max (16 max) 0.276 max (7 max) 0.256 max (6.5 max) 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 WSM Series Issue December 2008 Sheet 2 of 3 Molded Surface Mount Wirewound Resistor Environmental Data Characteristics WSM-1 WSM-2 WSM-1 Load at Rated Power: 1000 hours @ 70°C ∆R% 2 ± 0.001Ω 2 ± 0.001Ω 3 ± 0.001Ω Dry Heat: ∆R% 2 ± 0.001Ω 2 ± 0.001Ω 3 ± 0.001Ω 1000 hours @ 155°C ∆R% Short Term Overload 2 ± 0.001Ω Derating from Rated Power @ 70°C zero at 155°C Moisture ∆R% Temperature Cycling ∆R% 1 ± 0.001Ω Resistance to Solder Heat ∆R% 1 ± 0.001Ω Isolation Voltage volts 1,000 Insulation Resistance ohms >1000M Substrate Bend ∆R% 0.2 ± 0.001Ω 1 ± 0.001Ω 1 ± 0.001Ω 1.5 ± 0.001Ω *Note: The power ratings to be applied depend upon the board used and the ambient temperature. Standard Quantities Per Package Ordering Data Specify type, reference, etc. as indicated in this example of a WSM3 6801 F resistor with tape and reel packaging. Sample Part No. WSM3 6801 F LF TR IRC Type Type Code WSM1 WSM2 WSM3 13" Reel (330mm) R 1500 800 750 Packaging: (WSM1, WSM2, WSM3) Resistance Value WSM2 resistors are supplied on .945 (24mm) wide carrier tape. (100Ω and greater - First 3 significant digits plus 4th digit multiplier) Example: 100Ω = 1000, 1000Ω = 1001, 150,000Ω = 1503 (Less than 100Ω - "R" is used to designate decimal) Example: 51Ω = 51R0, 1Ω = 1R00, 0.25Ω = R250 WSM3 resistors are supplied on 1.26 (32mm) wide carrier tape. Tolerance (K = 10%, J = 5%, G = 2%, F = 1%) Both products are reeled onto 13.00 (330mm) diameter reels. Lead Free, RoHS Designator Packaging Code (TR = 13" Reel) *For packaging information, see Appendix "A". Dimensions (Inches and (mm)) Ao Bo Ko W P T WSM1 .165 (4.2) .300 (7.62) .165 (4.20) .630 (16.0) .315 (8.00) .014 (0.36) WSM2 .266 (6.75) .470 (11.95) .206 (5.22) .945 (24.0) .473 (12.0) .014 (0.36) WSM3 .288 (7.3) .721 (18.3) .264 (6.7) 1.26 (32.0) .473 (12.0) .016 (0.4) 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 A0 B0 K0 P W t WSM Series Issue December 2008 Sheet 3 of 3