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2D Heat Transfer question regarding temperature obtained in graph

Posted May 19, 2011, 10:29 a.m. EDT Heat Transfer & Phase Change, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 4.1 1 Reply

James Compagnoni
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Hi everyone,

I've created a 2D model of a device dissipating ~1.7e9 W of power per cubic meter which is embedded in FR4 material. I followed very closely the instructions of the model documentation on natural convection of a vertical circuit board, including keeping the buoyancy term which accounts for density fluctuation as the air heats up.

In addition to embedding the device in the substrate, I have also made the whole structure horizontal by rotating it (done easily) and then attaching a 50 micon thick copper plane on the whole top surface of the device and substrate to see how that affects the temperature distribution as well as max temperature.

What I don't understand is the lower bounded temperature that I am receiving in my results-- near -29.2 degC. I find this strange because my inlet temperature is room temperature for the air.

Any thoughts would be greatly appreciated! I have attached the file for convenience as well as in case I have not explained something well.

Regards,
James
1 Reply Last Post May 19, 2011, 10:47 a.m. EDT
James Compagnoni
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Posted: 1 decade ago May 19, 2011, 10:47 a.m. EDT
Also,

When I add copper vias under the power device as well as attached to the copper plane on the top surface, the default solver (I tried the direct solver as well) does not solve it. It returns with an error:

Failed to find a solution.
Maximum number of Newton iterations reached.
Returned solution has not converged.

Any advice as to how I can fix this? I presume my initial/boundary conditions are the culprit but I don't know what to do. The file is attached for convenience.

Thanks much!

James
Also, When I add copper vias under the power device as well as attached to the copper plane on the top surface, the default solver (I tried the direct solver as well) does not solve it. It returns with an error: Failed to find a solution. Maximum number of Newton iterations reached. Returned solution has not converged. Any advice as to how I can fix this? I presume my initial/boundary conditions are the culprit but I don't know what to do. The file is attached for convenience. Thanks much! James

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