Power Metal Film Resistors Welwyn Components MF-S Series • • • Small size for power rating Range of 4 sizes: 0.5 watt to 3 watt at 70˚C Flameproof protection Electrical Data Power rating at 70˚ C watts Resistance range ohms Limiting element voltage MF1/2S MF1S MF2S MF3S 0.5 1.0 2.0 3.0 0R1 – 1M 0R1 – 470k volts TCR 350 ppm/˚ C Isolation voltage 150 < 10 :350 volts Resistance tolerance 10 :150 500 % 700 1 : 5, 10 Standard values >1 : 1, 2, 5 E24 preferred Thermal impedance ˚ C/watt Ambient temperature range 140 110 ˚C 80 60 -55 to 155 Physical Data Dimensions (mm) & Weight (g) L Max D Max f min d nom PCB mounting centres MF1/2S 6.2 2.5 21.0 0.6 10.2 1.02 0.6 0.3 MF1S 9.0 3.6 19.6 0.8 12.7 1.2 0.5 MF2S 12.5 4.2 17.8 0.8 18.4 1.2 0.9 MF3S 14.5 5.3 23.8 0.8 20.3 1.2 1.1 Type Min. bend radius Wt.nom d D L f General Note Welwyn Components reserves the right to make changes in product specification without notice or liability. All information is subject to Welwyn’s own data and is considered accurate at time of going to print. A subsidiary of TT electronics plc © Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com Issue Issue C D · 01.06 01.07 147 Flameproof Power Metal Film Resistors Welwyn Components MF-S Series Construction Marking The resistance element is a precisely controlled thin film of metal alloy on a high purity ceramic core, protected by a cement coating applied so that terminations remain completely clear. MF Series resistors are colour coded with 5 bands for 1% tolerance or 4 bands for other tolerances. IEC 62 colours are used. Solvent Resistance This permits a well defined body length, (clean lead to clean lead dimension L). The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. Terminations Flammability Material Solder-coated copper wire. Strength The terminations meet the requirements of IEC 68.2.21 The resistors will not burn or emit incandescent particles under any condition of applied temperature or power overload. Solderability The terminations meet the requirements of IEC 115-1, Clause 4.17.3.2 Performance Data Maximum Load: 1000 hours at 70˚C R% 5 Shelf life: 12 months at room temperature R% 1 Derating from rated power at 70˚C R% zero at 155˚ C Climatic R% 1 Climatic category 40/125/56 Temperature rapid change R% 0.5 Resistance to solder heat R% 0.5 Application Notes Packaging The preferred method of packaging is taped and ammo packed, see figure 1 for critical dimensions. 1. If the resistors are to dissipate full rate power, it is recommended that the terminations should not be soldered closer than 4mm from the body. Alternative packaging is available by special request. 2. Due to operating temperature limitations imposed by some pcb materials, derating may be necessary. An estimate of the temperature rise to be expected can be calculated using the thermal impedance figures given under Electrical Data. Figure 1 c 3. Lead Formed resistors can also be supplied. Standard options of Lancet, Radial and Goalpost forming are shown in lead Form Information section. f1 f2 b 6 Body location f1 – f2 6 1.4 mm Standard Quantities Per Package Type Large ammo pack MF1/2S MF1S MF2S MF3S Type b c 5000 2500 2500 1000 MF1/2S 52 5 MF1S 52 5 MF2S 52 5 MF3S 67 10 © Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com 148 Issue C D · 01.06 01.07 Issue