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Assigning thermal conductivity to PCB components

Question asked by Laura Tripp on Aug 29, 2011
Latest reply on Aug 26, 2014 by Jared Conway

I am doing a thermal simulation of a pcb assembly and need to assign material properties to the components on the board.  I am having a difficult time determining the thermal conductivity. 

 

My models are simplified representations imported from Circuit Works and are basically extruded blocks that consist of one material.  In the SolidWorks tutorials all electrical components are assigned silicon, but I have a variety of components and need more detail than this.

 

Some vendors provide thermal resistance (K/W) for components, but Simulation Flow requires thermal conductivity - W/(m*K).  In order to convert to thermal conductivity I would need to know where the junction, board, & case temperatures were taken, correct?  Or is there a standard way to convert thermal resistance to conductivity if you know the outer package dimensions?

 

Another approach would be to give the components a little more detail.  For instance:  Model an inductor as an epoxy housing with a copper coil.  This way I can assign the basic material properties of copper and epoxy with known conductivity values.  The problem is that the more detail I add the slower my analysis becomes.  Also, it is sometimes difficult to get this information from vendors.  If this approach is used would I apply the heat source to all of the sub-components?

 

Does anyone have any advice on this topic?

 

Much appreciated,

Laura

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