topic Re: How to create MCPCB in CFD Forum

How to create MCPCB

Anonymous — Fri, 24 Apr 2015 10:08:54 GMT

Hello!

I need in modeling LED Lamp in Autodesk Simulation CFD.

LEDs are located on MCPCB (metalcore PCB).

Tell me, please, how to properly create MCPCB?

The MCPCB consists of a metal base (Aluminum) 1.5 mm thick and a single layer of copper with dielectric (FR4) 0.07 mm thick.

Please, help deal with the problem.

Re: How to create MCPCB

Jon.Wilde — Fri, 24 Apr 2015 14:31:12 GMT

Hi,

If you wish to capture the Junction Temps then you will need to have the LED placed on a PCB part.

I think my approach would be to model a PCB part as we would with other LED's and amalgamate the layers into it?. Have you seen the PCB calculator within CFD?

Kind regards,

Jon

Re: How to create MCPCB

Anonymous — Tue, 28 Apr 2015 06:32:30 GMT

Thanks for your advice!

if I understood correctly, that i can model LED-module as shown in picture. It is right?

Yes, i know the PCB calculator, but there is no example MCPCB. And one more question: whether the sum of the thicknesses of layers in traces and planes to be equal to total thickness?

Re: How to create MCPCB

Jon.Wilde — Tue, 28 Apr 2015 06:47:23 GMT

Yes, you can do that.

No, the layers don't have to equal the total thickness. The remaining material will be assigned the 'dielectric' property.

Re: How to create MCPCB

Anonymous — Thu, 30 Apr 2015 09:26:45 GMT

Hi!

I tried to make a calculation in Simulation CFD, but solver exited due to divergence.

See my model, please. Maybe I'm doing something wrong?

How can I send support-file for you?

Re: How to create MCPCB

Jon.Wilde — Thu, 30 Apr 2015 09:39:13 GMT

Hi,

If you can't attach it here, maybe use Dropbox/Autodesk360/Wetransfer etc.

Did you follow the guidelines here? Lighting Guide

Thanks,

Jon

Re: How to create MCPCB

Anonymous — Tue, 05 May 2015 06:33:58 GMT

Hi.

I put the support-file at - https://yadi.sk/d/iTttH12vgRj7Q.

Please see, somewhere may have errors?!

Re: How to create MCPCB

Jon.Wilde — Tue, 05 May 2015 08:16:17 GMT

Hi,

There does not seem to be a file in that location?

Thanks,

Jon

Re: How to create MCPCB

Anonymous — Tue, 05 May 2015 10:18:03 GMT

Try again, please, via this link - https://yadi.sk/d/kvgpsFl_gS3u3

Re: How to create MCPCB

Jon.Wilde — Tue, 05 May 2015 12:44:53 GMT

Hi,

What makes you think you have errors? Was there an error message?

Without running it, the setup here looks pretty good to me. A few comments:

You might like to extend the air domain further above the unit - to capture the plume
More mesh will likely help, again to capture the plume and the airflow around the unit - see how it goes with the current mesh first

Thanks,

Jon

Re: How to create MCPCB

Anonymous — Wed, 06 May 2015 05:47:37 GMT

Hi,

yes, i run solver and the program generated an error:

Re: How to create MCPCB

Jon.Wilde — Wed, 06 May 2015 09:00:32 GMT

Hi,

Could you share an image of the convergence plot? How long did it run for?

You do need a taller domain to properly capture the plume - look at hte guide again. The images there should give you a decent idea.

In addition to my other comments I would also suggest you run with the mixing length turbulence model (as per the lighting guide).

I would also leave the minimum refinement length as the default and use mesh refinement (maybe with a region to capture the plume) to refine the mesh where you choose to.

The Surface Refinement option is a useful tool also - use it here 🙂

With these changes and what I said before, this ought to be OK.

Even without the geometry change, this seems to run fine here.

Here is my mesh (default everything and a region where you can see it with the mesh refined to 0.7 of it's orginal value). This gave 2.1m elements, which seems about right and should certainly run OK.

Results so far (I am going to stop it now):

Thanks,

Jon

Re: How to create MCPCB

Anonymous — Wed, 06 May 2015 10:37:22 GMT

Thanks a lot for your comments!

I will try running again with changed settings today.

My previous calculation stopped at 68 itaration:

Re: How to create MCPCB

Anonymous — Fri, 22 May 2015 08:09:35 GMT

Hi.

I have successfully carried out my calculation.

Thank you very much for your help.