As shown figure 1, the heat flow ∅_0 goes through the bottom of
heat sink and then goes into its root. In the root, the heat flow will be divided into two shares ∅_1and∅_2, and then through the root and environment air, start convection and heat exchange. Finally, the heat flow goes into the environment by heat exchange with fins. The heat resistance network model is shown in figure 1.
Fig 1. The heat flow schematic diagram of heat sink dissipation
Fig 2. The heat resistance network model of fins
As the lateral area of heat sink base is much smaller than the root cross-sectional area, the heat dissipated from side can be omitted. The whole heat flow enters the bottom and side of heat sink by heat conduction. The heat transfer thermal resistance
, the surface heat transfer coefficient
h and the cross section area A
c along the fin height are all constant.
According to the above simplification, the model established is a one-dimensional steady state heat conduction model and the equivalent thermal resistance of the rib fin is
Where, R
r— heat resistance of the heat dissipation part at the root, K / W;
R
f—heat resistance of the heat dissipation part in the side, K / W.
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