Heat Radiation of IC by Forced Convection (Transient Analysis)examples|products|Murata Software Co., Ltd.

Example4 Heat Radiation of IC by Forced Convection (Transient Analysis)

General

  • Heat dissipation of an IC on the substrate by the forced convection is solved by the transient analysis.
     

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

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

  • Obtain this session's project file. (Save the project file before open)

 

Analysis Space

Item

Setting

Analysis Space

3D

Model Unit

mm

 

Show Results

Item

Setting

Solver

Fluid Analysis [Bernoulli]

Thermal analysis [Watt]

Analysis Type

Transient Analysis

Laminar Flow/Turbulent Flow

Select Turbulent Flow

Meshing Setup

General Mesh size: 5 [mm]

 

The Transient Analysis tab is set up as follows. The total number of steps is 20. The timestep is 60 seconds.

Therefore, the temperature distributions for 20 minutes are solved.

Tab

Setting Item

Setting

Transient Analysis

Table

Number

Calculation steps

Output steps

Timestep [s]

1

20

1

100

 

Initial Temperature

25[deg]

 

To shorten the calculation time, set the large value for convergence judgment. The settings on the high-level setting tab are as follows.

Tab

Setting Item

Setting

High-Level Setting

Nonlinear Analysis

Convergence Judgment (Heat): 1 x 10^-3

Model

The model is a box solid body. The material is Air (000_Air). The boundary conditions of inlet and outlet are set on the left edge and the right edge respectively.

The slip wall outer boundary condition is applied to the top and bottom edges where the boundary condition is not set.

The substrate (VOL1) and IC (VOL2) are solid bodies.

 

 

Setting of Body Attributes, Materials, and Mesh Sizes

Body Number/Type

Body Attribute Name

Material Name

Mesh Size

0/Solid

VOL1

006_Glass_epoxy *

0.2

1/Solid

VOL2

001_Alumina *

0.2

2/Solid

Air

000_Air(*)

* Available from the material DB

 

Specific heat is set as follows since it is not set in the material database.

Material Property Name

Tab

Setting

001_Alumina

Specific Heat

800 [J/kg/deg]

 

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

In/Edge

Thermal Fluid

Inlet

Forced Inflow
Specify fluid velocity
1[m/s]

Inflow Temperature : 25[deg]

Out/Face

Thermal Fluid

Outlet

Natural Outflow

Outer Boundary Condition

Thermal Fluid

Slip wall

 

Results

The figure below shows the temperature distribution after 1[min] = 60[s], 5[min] = 300[s], and 20[min] = 1200[s]

The maximum and minimum values of the temperature scale are 61[deg] and 25[deg] respectively.

For easy viewing of the temperature distributions of the substrate and the IC, the ambient air field is hidden by right-clicking the air body and selecting [Hide Body Field].

The temperature is rising gradually.

 

1[min]
5[min]
20[min]

 

The temperature change at the coordinates (0, 0, 3) which is above the IC is plotted as follow.

Again, it can be observed that the temperature is rising gradually.