I don't use Pads, so I don't know the answer to this. Does the exported DXF file contain Z-Axis data? I export DXF out of Mentor Expedition all of the time, but I have only looked at the files in AutoCad LT, which is only 2-D
If Pads can export IDF and you have a tool that supports it (Pro-E, Solid Works), that would be the best solution.