Thermal Management Calculators
6 free calculators with formulas and worked examples.
Heatsink selection, junction temperature, PCB trace temperature rise, thermal via arrays, and thermal resistance network calculators for component and board-level cooling.
Heatsink
Calculate required heatsink thermal resistance and junction temperature for power devices
Trace Temp
Calculate PCB copper trace temperature rise under load current using IPC-2152
Thermal Resistance Network
Calculate junction, case, and heatsink temperatures through a series thermal resistance network (θJC + θCS + θSA) for component thermal management
Junction Temperature
Calculate semiconductor junction temperature from power dissipation and thermal resistance chain (θJC + θCS + θSA). Essential for transistor, MOSFET, and IC thermal design.
Heatsink Selection
Calculate the required heatsink thermal resistance (θSA) to keep a device junction below its maximum temperature. Use this to select an appropriate heatsink.
Thermal Via Array
Calculate thermal resistance of a PCB thermal via array for heat spreading from SMD packages to inner copper planes or heatsinks.
About Thermal Management Calculators
Thermal management determines whether a component reaches its maximum junction temperature under worst-case operating conditions. Semiconductor reliability degrades exponentially with temperature — a 10°C increase roughly halves MTBF for many devices — making thermal design a reliability discipline, not just a comfort margin.
The thermal resistance network models heat flow by analogy with Ohm's law: power (current) flows through a series of resistances from junction to ambient. Junction-to-case resistance (θ_jc) is specified by the IC manufacturer; case-to-heatsink (θ_cs) depends on interface material and mounting pressure; heatsink-to-ambient (θ_sa) is the heatsink datasheet value at the operating airflow. Total junction temperature: T_j = T_ambient + P × (θ_jc + θ_cs + θ_sa).
Heatsink selection requires knowing the power dissipated, ambient temperature, and allowable junction temperature. For forced-air cooling, thermal resistance drops dramatically with airflow velocity; natural convection heatsinks must be sized conservatively. Thermal interface materials (TIMs) — thermal paste, pads, or phase-change materials — fill microscopic air gaps at the contact surfaces, reducing θ_cs from ~1°C/W (dry contact) to 0.1-0.3°C/W.
PCB trace temperature rise under current load follows IPC-2152 models that distinguish between internal and external layers. Via thermal resistance arrays provide low-resistance thermal paths through the PCB to heat spreader planes or bottom-side heatsinks — common in LED drivers and power modules. The thermal via calculator determines the number and arrangement of vias needed to meet a temperature rise target.