Printed Circuit Boards (PCBs) are concerned as a special case of solid material having anisotropic thermal conductivity. The integral characteristics of a PCB, i.e. its effective density, specific heat, and components of thermal conductivity, are calculated on the basis of the PCB structure. You can either select a pre-defined PCB from the Engineering Database, or create a user-defined one by specifying its parameters. In the latter case, you must specify density (r), specific heat (C), and thermal conductivity (K) for both dielectric (denoted by ‘D’ index) and conductor (denoted by ‘C’ index) materials of the PCB, and describe its internal structure in one of the provided types:
Conductor Volume Fraction
The Conductor Volume Fraction type requires the specification of Percentage conductor in PCB volume (A), i.e. the volume fraction of conductor material in the PCB.
With the Board Mass type, the PCB total mass (M) and PCB total volume (V) are used to calculate the fraction of conductor material (A) in it.
The Layer Definition type implies that you must specify the PCB total thickness (t) and the Number of conducting layers (nC). Also for each conducting layer you must specify the Percentage Cover (Ai), i.e. the volume fraction of conductor material in the layer, and the Layer Thickness (tCi).
You may assign one of PCBs stored in the Engineering Database to a solid body. The body is considered as a solid with Axisymmetrical/Biaxial type of anisotropic thermal conductivity. The direction is determined automatically from the body geometry. The selected body should be a thin plate (one of the body’s dimensions is substantially smaller than two others) with two parallel surfaces and can be arbitrary aligned, not necessarily along global coordinate system axes.
To create a Printed Circuit Board (PCB):
- Click Printed Circuit Board on the Flow Simulation Features toolbar or Flow Simulation > Insert > Printed Circuit Board.
– or –
In the Flow Simulation analysis tree right-click the Printed Circuit Boards item and select Insert Printed Circuit Board.
- In the flyout FeatureManager design tree select a component which you want to consider as the PCB. You can also select a component in the graphics area. The selected components appear in the Components to Apply PCB list under Selection.
- Under Printed Circuit Board select a PCB from the list of those currently available in the Engineering Database.
If you want to add a new PCB to the Engineering Database or edit an existing one, click Create/Edit to open the Engineering Database.
- Click OK . The new PCB item appears in the Flow Simulation Analysis Tree.
To edit definition of a PCB, in the Flow Simulation analysis tree, double-click the PCB item, or right-click the item and select Edit Definition.
NOTE: This feature is available for Electronics Cooling module users only.