– Maximum value
ρ Board Volume . conductor
10
Flotherm 4.1 Lecture 4 << Index >>
Options for conductivity model
Layer Definition
– Set number of layers – Set thickness and
All require dielectric and conductor materials
All result in a single PCB with an othotropic conductivity
7
Flotherm 4.1 Lecture 4 << Index >>
Options for conductivity model
T0220 Component
Compact to Detailed
13
Flotherm 4.1 Lecture 4 << Index >>
Components
Increased detail means: Increased accuracy Increased realism But also: Solutions take longer Design changes take
Modeling PCBs II
Changing the Modeling level to Conducting
The size section now requires a thickness in the Z direction.
The Dielectric and Conductor Materials must be specified.
coverage for each layer
11
Flotherm 4.1 Lecture 4 << Index >>
Modeling PCBs II
The PCB SmartPart can always be overwritten with other cuboids lower in the project manager list to represent ground-planes, thermal vias etc.
Alternatively the PCB structure could be constructed in greater detail using individual cuboids to represent the layered structure.
Area of increased conductivity to account for thermal vias
6
Flotherm 4.1 Lecture 4 << Index >>
Modeling PCBs II
There are three choices for conductivity model
– Percentage Conductor by Volume – Board Mass – Layer definition
5
Normal Conductivity (W/mK)
Flotherm 4.1 Lecture 4 << Index >>
Modeling PCBs I
The PCB Smart Part will internally create a cuboid with Orthotropic Material Properties The Summary section details the computed values of In Plane and Normal Conductivity together with other useful information relating to the PCB SmartPart
Percentage conductor by volume
9
Flotherm 4.1 Lecture 4 << Index >>
Options for conductivity model
Board Mass
– Minimum value
ρ Board Volume . dielectric
<< Index >>
Lecture 4A
Further Refinement: Solid Temperatures
Review
Flotherm 4.1 Lecture 4 << Index >>
Started simply
– Base modeling Level
– Enclosure Walls Thin – PCB Conducting – Components as heat sources over whole PCB
Give more detailed results
– Accurate air flow and temperatures local to the components
– Solid temperature for components
4
Flotherm 4.1 Lecture 4 << Index >>
Only gives general results
– Air flow patterns – Air temperatures
2
Flotherm 4.1 Lecture 4 << Index >>
Refine the Model
Add detail to the PCB
– Options for conductivity model – Discrete components
Layered cuboids of FR4 Copper
Detailed PCB Structure
12
Flotherm 4.1 Lecture 4 << Index >>
Components
Components can be represented by: PCB Component Compact Component Cuboids & Thermals Sources