Fusible Nickel Film Resistors Welwyn Components FN Series • Predictable fusing characteristics • Constant current fusing • Flameproof Electrical Data FN4 Power rating at 70°C watts 0.4 Resistance range ohms 0R1 to 20R ppm/°C See Figure 1 TCR Resistance tolerance* % 5, 10, 20 Standard values E24 preferred Thermal impedance °C/watt Ambient temperature range 215 °C -55 to 155 * Below 1R, 10 and 20% only. Physical Data Dimensions (mm) & Weight (g) Type L Max D Max f min d nom PCB mounting centres FN4 6.2 2.5 21.0 0.6 10.2 Min. bend radius Wt. nom 0.6 0.3 d D L f Construction Marking The nickel film is deposited on a high purity ceramic rod. End caps are force fitted and termination wires welded to the caps. The resistive film is adjusted to the required value by a helical cut; finally the flame retardant lacquer protection is applied to the resistor body and the resistor is marked with an indelible ink. Resistors are colour coded with five bands. Four of the bands are used to indicate value and tolerance, with IEC 62 colours being used. A fifth black band denotes constant current fusibility. Terminations Material Solder-coated copper wire. Strength The terminations meet the requirements of IEC 68.2.21 Solderability The terminations meet the requirements of IEC 115-1, Clause 4.17.3.2 Solvent Resistance The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. Flammability The resistors will not burn or emit encandescent particles under any condition of applied temperature or power overload. 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 168 Issue B · 03.02 Fusible Nickel Film Resistors Welwyn Components FN Series Performance Data Maximum Load: 1000 hours at 70°C ∆R% 1 Shelf life: 12 months at room temperature ∆R% 0.5 Derating from rated power at 70°C zero at 155°C Long term damp heat ∆R% Resistance to solder heat ∆R% 1 0.5 Fusing characteristics See Figure 2 Packaging Fusing All FN resistors are supplied tape packed ready for loading on to automatic sequencing and insertion machines. After fusing the final resistance value will be ≥10 times the initial value. Component wires will not protrude beyond the outside edge of the tapes. Standard Quantities Per Package Alternative packaging available by request. Type FN4 Large ammo pack 5000 A detailed Packaging Data Sheet is available upon request. Lead Formed resistors can also be supplied. Standard options of Lancet, Radial and Goalpost forming are shown in Lead Form Information section 5 f1 6 f2 52 6 Body location f1 – f2 ≤ 1.4 mm © 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 B · 03.02 169