Thermal Resistance Network Calculator
Calculate junction, case, and heatsink temperatures through a series thermal resistance network (θJC + θCS + θSA) for component thermal management
Formula
T_J = T_A + P_D × (θ_JC + θ_CS + θ_SA)
How It Works
Thermal resistance networks are mathematical models used to analyze heat transfer through complex systems by representing thermal paths as electrical-like resistance networks. Just as electrical circuits use resistors to model current flow, thermal resistance networks use thermal resistance components to model heat flow between different temperatures. Each thermal resistance represents the temperature difference per unit of heat transfer, analogous to electrical resistance representing voltage difference per unit of current.
Worked Example
Consider a multi-layer heat sink with three materials: aluminum (5mm thick), copper (2mm thick), and ceramic (3mm thick). Calculate the total thermal resistance: 1. Calculate individual layer resistances: R1 = thickness / (thermal conductivity * area) 2. Aluminum: R1 = 0.005m / (237 W/mK * 0.01m²) = 2.11 K/W 3. Copper: R2 = 0.002m / (401 W/mK * 0.01m²) = 0.50 K/W 4. Ceramic: R3 = 0.003m / (30 W/mK * 0.01m²) = 10.00 K/W 5. Total thermal resistance: Rtotal = R1 + R2 + R3 = 12.61 K/W
Practical Tips
- ✓Always use consistent units throughout calculations
- ✓Consider contact thermal resistance at interfaces between materials
- ✓Use actual material thermal conductivity values from reliable sources
- ✓Account for geometric factors like surface area and material thickness
Common Mistakes
- ✗Neglecting contact thermal resistance between layers
- ✗Using incorrect thermal conductivity values
- ✗Forgetting to convert units properly
- ✗Assuming uniform heat distribution across complex geometries
Frequently Asked Questions
What is thermal resistance?
Thermal resistance measures a material's resistance to heat flow, similar to electrical resistance. It's calculated as temperature difference divided by heat transfer rate.
How do thermal resistance networks relate to electrical circuits?
They use analogous principles: temperature difference is like voltage, heat flow is like current, and thermal resistance is like electrical resistance.
What factors affect thermal resistance?
Material thickness, thermal conductivity, cross-sectional area, and interface conditions all impact thermal resistance.
Shop Components
Affiliate links — we may earn a commission at no cost to you.
Related Calculators
PCB
Via Thermal Resistance
Calculate PCB via thermal resistance, array thermal resistance, thermal conductance, and current-carrying capacity for thermal via design
Power
LDO Dropout
Calculate LDO regulator power dissipation, junction temperature rise, minimum input voltage, efficiency, and headroom for linear regulator design
Power
MOSFET Power Loss
Calculate MOSFET conduction loss, switching loss, total power dissipation, junction temperature, and efficiency for power electronics design
Thermal
Heatsink
Calculate required heatsink thermal resistance and junction temperature for power devices
Thermal
Trace Temp
Calculate PCB copper trace temperature rise under load current using IPC-2152
Thermal
Junction Temperature
Calculate semiconductor junction temperature from power dissipation and thermal resistance chain (θJC + θCS + θSA). Essential for transistor, MOSFET, and IC thermal design.