Ansoft mesh generation

Wai Yeung Yip (wyip@lsil.com)
Fri, 8 Nov 96 17:52:11 PST

To the expert Ansoft users out there,

I am doing a lot of BGA modeling using the Ansoft Maxwell 3D and Quick 3D
software programs, and I routinely run into mesh generation problems. I am not
getting satisfactory support from Ansoft and so any tricks I can learn from you
would be very helpful. Usually the program fails to even generate the initial
mesh. With the Maxwell 3D program I cannot get into using seeded mesh without
first having the initial mesh generated. So I have to resort to putting dummy
objects in the solution space to help the meshing. Have you any suggestions as
to what objects to use? I usually enclose what I consider problematic part of
the conductors with boxes but this does not always work.

Even if I succeed in getting the initial mesh, the magnetic field solver may
still fail. In this case I have to do seeded mesh. Do you have suggestions as to
what seed values to use? Based on my experience, with too large seed values, the
mesh generator may fail, or even it does not, the magnetic field solver may
still fail. With too small seed values, I end up with too many elements and I
run out of memory before I can do enough passes to get a converged solution.

Another problem I run into is when I have extrusions and I need to compute a
port inductance matrix for de-embedding, the port inductance solver may fail.
This happens despite the fact that I have already got a converged 3D inductance
solution and so the mesh is supposedly adequately fine. Any workarounds?

Thank you very much in advance for your assistance.

Regards,
Wai-Yeung Yip
LSI Logic