High Voltage Metal Film Resistors Welwyn Components MH Series • BSEN 60065 Approval for MH37 in value range 680K to 3M • • • • • High working voltage to 3.5KV Small size High pulse load capability Robust cement coating Value up to 10M Electrical Data MH25 MH37 Power rating at 70°C max watts 0.25 0.5 Resistance range ohms 100K - 10M 100K - 3M Limiting element voltage volts dc or ac peak Isolation voltage 1,600 3,500 volts TCR 700 ppm/°C Resistance tolerance 100 % 1, 2, 5 Standard values E24 and E96 preferred Thermal impedance °C/watt Ambient temperature range 140 112 °C - 55 to 155 Physical Data Dimensions (mm) and Weight (g) L max D max f min d nom PCB mounting centres MH25 6.2 2.5 21.0 0.6 10.2 0.6 0.3 MH37 9.0 3.7 19.6 0.8 12.7 1.2 0.5 Type Min Bend Radius Wt.nom d D L f Construction Terminations Thin film material is sputtered on to high grade ceramic rods. Nickel plated steel caps are force fitted and the termination wires are welded to the caps. The value is obtained by a helical cut in the film and finally the resistor body is protected by a cement protection applied so that the terminations remain completely clear. Material Solder-coated copper wire. Strength The terminations satisfy the requirements of IEC 68.2.21. Marking Solvent resistance 1% tolerance resistors are colour coded with 5 bands. 2% and 5% tolerance have 4. Band IEC 62 colours are used. The body protection and marking are resistant to all normal industrial cleaning fluids suitable for printed boards. Solderability The terminations meet the requirements of IEC 115-1, Clause 4.17.3.2 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 E · 10.05 191 High Voltage Metal Film Resistors Welwyn Components MH Series Performance Data Maximum ∆ R% Load at rated voltage : 1000 hrs at 70°C Typical 1.5 0.4 Derating from rated power at 70°C Zero at 155°C Overload ∆ R% 1.0 0.25 56 days at DHSS ∆ R% 1.5 0.2 Climatic ∆ R% 1.5 0.2 Climatic category 55/155/56 Temperature rapid change ∆ R% 0.5 0.05 Resistance to solder heat ∆ R% 0.5 0.05 Vibration and bump ∆ R% 0.5 Voltage proof 0.05 volts 700 min Application Notes To ensure reliable performance at high voltages care should be taken to avoid potential sources of ionic contamination contacting the resistor body, for example, flux applied by spraying, encapsulation materials or contaminants from the environment of use. Standard Quantities Per Package Packaging All MH series resistors are supplied tape packed ready for loading on automatic sequencing and insertion machines. Component wires will not protrude beyond the outside edge of the tape. Type MH25 MH37 Ammo pack 5000 2500 6 6 52 Alternative packing available by request. 5 Lead Formed Resistors can also be supplied. Standard options of Lancet, Radial and Goal Post forming are shown in the Lead Form information sheet. f1 f2 Body Location f1 – f2 ≤ 1.4 mm Ordering Procedure Specify type reference, value and tolerance as shown in this example of MH25 10MR 1%: Type MH25 10MO F Resistance value (IEC62 code) Tolerance (IEC62 code) F 1% G 2% J 5% © 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 192 Issue E · 10.05