Analytical thermal resistances model for eccentric heat source on rectangular plate with convective cooling at upper and lower surfaces

► A simple method was used to build a thermal model of both surfaces cooling plate by using single surface cooling expression. ► Thicknesses of upper and lower spreading layers are determined by the heat transfer coefficients at upper and lower surfaces. ► The engineering thermal model was established, and the plate's thermal resistance was obtained as well. ► The network model is accurate to calculate the thermal resistance of discussed cases and the maximum relative error is 3.47%.