Thermal Design Parameters
Heat Sink Material
Cooling Method
Power Dissipation Q50.0 W
Ambient Temperature T_a25 °C
Fin Height H30 mm
Number of Fins N10
Fin Thickness t_f1.5 mm
Base Width W100 mm
Heat Transfer Coeff. h50 W/m²K
θ_j-c (Device Spec.)1.50 K/W
θ_c-s (Interface Resistance)0.20 K/W
—
T_j Junction Temp. [°C]
—
θ_total [K/W]
—
Fin Efficiency η [%]
—
θ_s-a [K/W]
Thermal Resistance Network
Resistance Breakdown
Number of Fins vs Junction Temperature
Heat Sink Thermal Design Theory
Fin efficiency (rectangular fin):
$$\eta_{fin} = \frac{\tanh(mH)}{mH}, \quad m = \sqrt{\frac{h \cdot P}{k \cdot A_c}}$$Overall fin array efficiency:
$$\eta_o = 1 - \frac{N \cdot A_{fin}}{A_{total}}(1 - \eta_{fin})$$Sink-to-air thermal resistance:
$$\theta_{s\text{-}a} = \frac{1}{\eta_o \cdot h \cdot A_{total}}$$Junction temperature:
$$T_j = T_a + Q \cdot (\theta_{j\text{-}c} + \theta_{c\text{-}s} + \theta_{s\text{-}a})$$
CFD Integration: This 1D thermal resistance model is used during pre-design stages before Icepak, FloTHERM, or similar CFD thermal analysis. For PCB-mounted devices, FEM analysis accounting for thermal spreading in the board is required. It is recommended to determine h from CFD analysis of the fin array airside, then verify using this tool.