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

# Example4Heat 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&apos;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].

 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.

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