Example11 Cooling of IC by Heat Sink

General

  • Using the heat sink, heat dissipation of the IC by the natural convection is solved by the steady-state analysis.
     

  • The temperature distribution and the heat flux vectors are solved.
     

  • Unless specified in the list below, the default conditions are applied.
     

 

Analysis Space

Item

Setting

Analysis Space

3D

Model Unit

mm

 

Analysis Condition

Item

Setting

Solver

Fluid analysis [Bernoulli]

Thermal analysis [Watt]

Analysis Type

Fluid analysis: Steady-state analysis

Thermal analysis: Steady-state analysis

Laminar Flow/Turbulent Flow

Select Turbulent Flow

Option

Select Take Buoyancy into Account (Natural Convection)

Layer Mesh Setting for Wall Surface (General Settings)

Parameters for Automatic Creation

Expected Temperature Difference: 50[deg]

Meshing Setup

General Mesh size: 10 [mm]

Detailed Setting

Relaxation Coefficient (Temperature)
0.99

 

The relaxation coefficient (temperature) is set at the large value as the default setting will take longer time for convergence.

Model

The substrate (VOL1) and the heat sink (HeatSink) are solid bodies.

The model is a box solid body. The material is Air (000_Air).

Set natural inflow/outflow to the outer boundary condition of Inlet/Outlet.

Setting of Body Attributes, Materials, and Mesh Sizes

Body Number/Type

Body Attribute Name

Material Name

Mesh Size

0/Solid

VOL1

006_Glass_epoxy *

2.0

1/Solid

VOL2

001_Alumina *

2.0

2/Solid

Air

000_Air(*)

14/Solid

HeatSink

001_Al *

2.0

* Available from the material DB

 

IC (VOL2) is set as follows on the Heat Source tab.

Body Attribute Name

Tab

Setting

VOL2

Heat Source

1W

Boundary Condition

Boundary Condition Name/Topology

Tab

Boundary Condition Type

Setting

Outer Boundary Condition

Fluid-Thermal

Inlet/Outlet

Natural Inflow/Outflow

Inflow temperature: Use ambient temperature (25[deg])

 

Results

The temperature distributions of the substrate, IC, and heat sink are shown below.

The air is hidden.

 

For the comparison purpose, the results of Example 6: Cooling of IC by Natural Convection], which is without a heat sink, are shown as well.

The maximum temperature without the heat sink is 105[deg] whereas it is 42[deg] with the heat sink.

The results confirms the effect of the heat sink.

By switching the solver type from thermal to fluid analysis, the flow velocity vectors are shown as below.

The cross section at x=0 is displayed.

In the graphics setup, the 3D vector is set OFF.

Ascending flows are generated between the walls of the heat sink.