Stackpole Electronics has introduced the RNAN series of thin-film chip resistors on aluminium nitride (AlN) substrates for precision circuits that must dissipate significant continuous power.
The new family combines tight resistance tolerance and low TCR options with package-level power ratings up to 6 W at 70°C.
Key features and benefits
- Aluminium nitride substrate: Stackpole states that the AlN substrate supports heat spreading while maintaining electrical insulation. This addresses localized heating that can affect resistance stability and component lifetime in sustained-load applications.
- Thin-film precision: The RNAN series is available with resistance tolerance down to ±0.1% and TCR as low as 25 ppm/°C. These parameters are important in feedback, gain-setting, current-measurement, and voltage-divider circuits where temperature-related resistance change can directly affect circuit accuracy.
- High power in standard chip sizes: The range covers 0603, 0805, 1206, and 2512 packages, with rated power from 0.5 W to 6 W at 70°C. The 2512 option is rated at 6 W, subject to the manufacturer’s specified mounting and thermal conditions.
- Published environmental stability data: Stackpole specifies resistance change limits of ±1% after 1,000 hours endurance, ±0.4% after 1,000 hours damp heat with load, and ±0.2% after 100 thermal-shock cycles from -55°C to +150°C.
Technical highlights
| Parameter | RNAN series |
|---|---|
| Resistor technology | Thin-film chip resistor |
| Substrate | Aluminium nitride (AlN) |
| Package sizes | 0603, 0805, 1206, 2512 |
| Rated power at 70°C | 0.5 W to 6 W |
| Resistance range | 50 Ω to 30.1 kΩ |
| Resistance tolerance | Down to ±0.1% |
| TCR | As low as 25 ppm/°C |
| Operating temperature | -55°C to +155°C |
| Endurance stability | ±1% after 1,000 hours |
| Damp heat with load | ±0.4% after 1,000 hours |
| Thermal shock | ±0.2% after 100 cycles, -55°C to +150°C |
The published ratings indicate a component family intended for applications where electrical precision and thermal management must be considered together. A low TCR limits resistance variation with temperature, but it does not eliminate resistance shift caused by self-heating, mounting conditions, long-term load, or environmental exposure.
Application fit
Stackpole identifies precision industrial power supplies, converters, control systems, motor drives, robotics, factory automation, renewable-energy controls, test equipment, and semiconductor manufacturing equipment as target applications.
In a power converter, the RNAN series may be relevant for control-loop dividers, precision feedback paths, sensing networks, gate-drive support circuits, or discharge and bias functions where a conventional chip resistor’s temperature rise would compromise accuracy or available board area. The AlN substrate may help transfer heat away from the resistive element, but actual benefit depends on the PCB copper connected to the terminals and the complete thermal path into the board or enclosure.
For a broader explanation of the relationship between resistor temperature rise, stability, and board heat spreading, see Resistivity and Thermal Resistance.
Design-in notes for engineers
- Validate the actual PCB thermal path. Stackpole explicitly notes that usable power handling depends on mounting and thermal design. Confirm the recommended land pattern, copper areas, layer stack-up, airflow, board material, enclosure temperature, and nearby heat sources using the current datasheet.
- Apply temperature derating. The stated power values apply at 70°C. Verify the manufacturer’s derating curve for the selected package across the maximum ambient and local board temperature rather than treating the nominal rating as available under all operating conditions.
- Check resistance accuracy over the complete temperature range. The ±0.1% tolerance applies to the initial resistance value, while the 25 ppm/°C figure describes temperature-related change. Assess both parameters, together with self-heating and the allowed long-term drift, for error-sensitive dividers and control loops.
- Confirm working-voltage limits. The announcement does not specify continuous working voltage, overload voltage, or pulse-load capability. These must be confirmed in the current manufacturer datasheet for the exact resistance value and package before schematic or layout release.
- Assess pulse and fault conditions separately. A continuous power rating does not establish permissible surge energy, repetitive pulse capability, or fault endurance. Check startup, inrush, switching transients, discharge events, and abnormal operating modes against documented pulse-load data.
- Review solder-joint and board reliability. High local temperatures and repeated power cycling can stress solder joints, PCB laminate, and adjacent components. Thermal imaging or representative board testing is appropriate where the resistor operates under sustained load or frequent load cycling.
- Avoid assuming equivalence with other AlN families. Stackpole’s announcement positions RNAN as a thin-film precision series. Its ratings, resistance range, qualification data, and application limits should be evaluated independently rather than inferred from thick-film or competitor AlN resistor families.
Further reading
- Resistivity and Thermal Resistance
- Advances in Film Resistor Technology
- Resistor, What is it ? Types, Ratings, Applications and Selection
- Stackpole Expanded its AlN Thick Film Chip Resistors
Source
This article is based on Stackpole Electronics’ manufacturer press release and the RNAN series documentation. Engineers should consult the current manufacturer datasheet and applicable technical documentation for final component selection, qualification, thermal validation, and design release.
