PTCR_C.qxd 8/9/04 4:00 PM Page 1 Surface Mounted Thermistors Welwyn Components PTCR Series • TCR’s up to +3500 ppm • Custom designs available • Solder terminations have a nickel barrier layer • Resistance range 10 ohms to 800 ohms • Tolerances down to 2% • Available in 0805 and 1206 sizes Electrical Data Commercial PTCR 0805 PTCR 1206 Power rating at 70°C watts 0.1 0.25 Resistance range ohms 10R to 400R 10R to 800R volts 100 200 Limiting element voltage TCR -55°C to 155°C Notes ppm/°C Resistance tolerance at 20°C See table below % Ambient temperature range 2, 5, 10 °C Values -55 to 155 ohms Thermal impedance E24 & E96 preferred °C/watt 360 Any value to order 200 For 10 devices mounted on a 50 x 25mm p.c.b. area Variation of TCR within Value Range TCR (ppm/°C) 10 to <25 3500 ± 10% 25 to <50 3100 ± 10% 50 to <100 2900 ± 10% 10 to <200 2700 ± 15% 200 to <400 2400 ± 15% 400 to <800 2200 ± 15% 10000 Resistance (ohms) Value range (ohms) 1000 800R 100 10R 10 1 -55 -15 25 65 105 Temperature °C 145 Physical Data Dimensions (mm) and weight (g) Style 0805 L W 2.0 ± 0.3 1.25 ± 0.2 T max 0.6 A B* 0.3 ± 0.15 0.9 min Wrap-around terminations (3 faces) Wt nom T 0.009 A 1206 3.2 ± 0.4 1.6 ± 0.2 0.7 0.4 ± 0.2 1.7 min 0.0090 B L A W *This dimension determines the number of conductors which may pass under the surface mounted device. 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 C · 08.04 37 PTCR_C.qxd 8/9/04 4:00 PM Page 2 Surface Mounted Thermistors Welwyn Components PTCR Series Construction Marking Thick film resistor material, overglaze and organic protection are screen printed on a 96% alumina substrate. All relevant information recorded on the primary package or reel. Terminations Solvent Resistance Wrap-around terminations are suitable for soldering. The chips are resistant to all normal industrial cleaning fluids suitable for printed circuits. Solderability Wrap-around terminations have an electroplated nickel barrier and solder coating. This ensures excellent leach resistance properties and solderability. They will withstand immersion in solder at 260°C for 10 seconds. Performance Data Maximum Typical Load at rated power: 1000 hours at 70°C ∆R% 5 1 Shelf life: 12 months at room temperature ∆R% 3 0.5 Derating from rated power at 70°C Dry heat: 1000 hours at 155°C Zero at 155°C ∆R% 2.5 Climatic category 1 55 / 155 / 56 Long term damp heat ∆R% 3 1 Temperature rapid change ∆R% 2 0.5 Resistance to solder heat ∆R% 2 0.5 Voltage proof volts 500 Application Notes Operating Temperature Range Packing The chips themselves can operate at a maximum temperature of 155°C (see performance claims above). For soldered chips, the joint temperature should not exceed 110°C. This condition is met when the stated power levels at 70°C are used. As standard 3000 chips are supplied taped and reeled on 8mm tape to IEC 286-3. Mounting This chips resistor is ideally suited for handling by automatic methods due to its rectangular shape and small dimensional tolerances. Electrical connection to a ceramic substrate or to a printed circuit board can be made by flow or reflow soldering of wraparound terminations. The terminations provide good ‘leach’ properties and ensure reliable contact. Due to the robust construction the resistor chip can be immersed in a solder bath for 10 seconds at 260°C. This enables the resistor to be mounted on one side of a printed circuit board and wire-leaded components on the other side. Ordering Procedure Specify type reference, value and tolerance as shown in this example of PTCR1206 400R 2%: Type 1206 G 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 38 400R Issue C · 08.04