Thermal Design and Heat Dissipation Guide
This technical reference document provides detailed information about aipu product specifications, characteristics, and performance parameters. Use this information to support your design and analysis activities.
Electrical characteristics are specified over the operating temperature range unless otherwise noted. Parameters are guaranteed by design, testing, or statistical analysis. Typical values is the most likely parametric norm at 25°C.
Thermal characteristics require careful attention during system design. The junction-to-ambient thermal resistance depends on the mounting configuration, PCB copper area, and airflow conditions. Use thermal simulation tools to predict operating temperatures under actual conditions.
Reliability data is based on accelerated life testing and field failure analysis. Mean time between failures (MTBF) calculations follow industry-standard methodologies. Contact BeiLuo for detailed reliability reports and qualification data.
💡 FAE Insights
⚠️ Common Pitfalls
- ✗ Ignoring thermal constraints in enclosure design
- ✗ Operating at maximum rating continuously
- ✗ Inadequate clearance for air flow
- ✗ Poor thermal interface material selection
📋 Customer Cases
Industrial Control Systems
Industrial
Challenge
Power modules overheating in outdoor cabinet during summer (ambient >60°C)
Solution
Redesigned with heatsinks and forced air cooling, implemented temperature monitoring
Customer Feedback
"Module temperatures reduced by 25°C, reliable operation maintained even at 70°C ambient"
Frequently Asked Questions
1. How to calculate power module temperature rise?
Calculate temperature rise: 1) Determine power loss: P_loss = P_out × (1-η)/η, where η is efficiency; 2) Find thermal resistance: Rth_ja (junction to ambient) from datasheet; 3) Calculate temperature rise: ΔT = P_loss × Rth_ja; 4) Find junction temperature: Tj = Ta + ΔT; 5) Verify Tj < Tj_max (typically 125°C or 150°C). Example: 2W module at 84% efficiency, P_loss = 0.38W, Rth_ja = 60°C/W, ΔT = 22.8°C, Tj = 25°C + 22.8°C = 47.8°C (well below limit). For high ambient temperatures, apply derating.
2. When is heat sinking required for power modules?
Heat sinking is required when: 1) Power level is high (>5W for natural convection); 2) Ambient temperature is elevated (>50°C); 3) Enclosed space with limited air flow; 4) Continuous operation at full load; 5) Reliability is critical (lower temperature = longer life). Calculate required thermal resistance: Rth_required = (Tj_max - Ta)/P_loss - Rth_jc - Rth_cs. If Rth_required is less than natural convection can provide, add heatsink. Example: For Tj_max=125°C, Ta=70°C, P_loss=1W, Rth_jc=10°C/W, Rth_cs=1°C/W: Rth_required = (125-70)/1 - 10 - 1 = 44°C/W. Natural convection Rth is about 60°C/W, so heatsink with Rth < 44°C/W is needed.
3. What thermal interface material should I use for heat sinks?
Thermal interface materials (TIM) reduce thermal resistance between module and heatsink: 1) Thermal grease: Best performance (0.1-0.5°C·cm²/W), requires careful application; 2) Thermal pads: Easy to use, consistent thickness (0.5-3°C·cm²/W), good for production; 3) Phase change materials: Solid at room temperature, flow at operating temperature, excellent contact; 4) Thermally conductive adhesive: Permanent attachment, moderate performance. Selection guidelines: For high-power applications (>10W), use thermal grease for best performance. For production environments, use thermal pads for consistency and ease of assembly. Apply thin, even layer - excess material increases thermal resistance. Typical thickness should be 0.1-0.2mm after compression.
4. How to implement temperature monitoring for power modules?
Temperature monitoring methods for power modules: 1) Internal temperature sensing: Some modules have built-in thermal shutdown, but no external monitoring; 2) External thermistor: Place NTC thermistor near module case, monitor with ADC; 3) Thermocouple: For accurate temperature measurement during testing; 4) IR thermal sensor: Non-contact monitoring for critical systems; 5) Module case temperature: Measure case temperature and estimate junction temperature using Tj = Tcase + P_loss × Rth_jc. Implementation guidelines: Place sensor close to module (within 5mm), ensure good thermal contact, use appropriate alarm thresholds (typically 10-20°C below maximum), implement graceful shutdown or load reduction when overheating. For critical applications, use redundant temperature monitoring.
5. How to select the right heat sink for my power module?
Heat sink selection process: 1) Calculate required thermal resistance: Rth_required = (Tj_max - Ta)/P_loss - Rth_jc - Rth_cs; 2) Determine available space: Length, width, and height constraints; 3) Consider mounting options: Through-hole, surface mount, or adhesive attachment; 4) Evaluate airflow: Natural convection vs forced air cooling; 5) Select material: Aluminum (cost-effective) or copper (better performance). Heat sink sizing guidelines: For natural convection, allow 30-50 cm² surface area per watt. For forced air (1-2 m/s), allow 10-20 cm² per watt. Fin density should match airflow - dense fins for forced air, sparse fins for natural convection. Always verify actual temperatures in final application.