Suggestions for Using Pro/ECAD files

For import into Pro/Engineer from OrCAD & Pro/ECAD

1. fix the file names; they arrive from OrCAD as file.brd & file.lib
   • rename file.brd to file.emn (contains board layout info, 2nd line says Board)
   • rename file.lib to file.emp (contains component info, 2nd line says Library)
2. grab ECAD license:
   • misc, float option, ECAD, done
3. import unpopulated circuit board as a Pro/E part:
   • part, import (name it what you like), ecad in, idf 2.0, board, file.emn
4. make the board the first component of an assembly
   • aa (mapkey for EDB start_assembly, which has a coord system; or you can create a new assembly & give it a coord system), component, assemble bare board
     (assembly by coordinate system works very well)
5. then import components:
   • interface, import, ECAD, IDF 2.0, default options, select assy coord system
   • when Pro/E asks for Neutral file name: file.emn
   • when Pro/E asks for Profiles file name: file.emp
   • import process takes off

potential problems (Robert Dillman, 757-864-7177, Robert.A.Dillman@nasa.gov):

1. tested w/ OrCAD-output IDF files; one has .brd extension, other .lib; if don't rename the file extensions, you need to type the full file name when Pro/E asks (file.brd, instead of ? and picking file)
2. Pro/E won't read input from files w/ capital letters in name; rename first or you'll get error "cannot open file"
3. Pro/ECAD reads in each component, gives it a default coord system named ECAD_DEFAULT, and asks which coord system to use to assemble the component; you can either click "ECAD_DEFAULT" once per component, or add "ECAD_COMP_CSYS_DEF_NAME ecad_default" to your config.pro (tells it to use the default coord system; I tried, but couldn't get it to change what name it uses)
4. Pro/ECAD doesn't like components used in library (.lib) file to have spaces in their names; if it yacks while reading file, look at the file, and if spaces are the problem get them renamed in OrCAD or use unix sed.
5. sometimes when trying to read components, Pro/E creates a file saying how to fix import problems, called ecad_hint.add; rename this file to ecad_hint.map, and re-run the import, some things (but not all) will work better.

For thermal analysis in PATRAN

• When done correctly, the parts of an assembly will come in with their group names defined by the part file names from Pro/E.
• In general, the board will come in as a trimmed solid.  Unless you specifically need the holes, it will be easier to handle as a (green) native PATRAN surface.  Just select the edges of one side of the solid to define it as a surface.  Also, at least in the one example I ran, the board came in with an incorrect thickness, so you may want to check the thickness before you use it for the plate property.  This is another reason to go with the plate instead of solid formulation.  If you need the holes, just define one side of the solid as a trimmed surface (then you will only be able to get a triangular mesh).
• WARNING: to save yourself time, you may not want to not post the group(s) that contain the board solid, or you might even have the designer suppress some layers in the Pro part before you pick it up, because for some reason the trimmed solid board will generally slow the display in PATRAN down immensely (it also makes the import take longer -- can be several hours).
• All chips will come in as trimmed solids, so you will only be able to get a tet mesh (with the current version of PATRAN).  If you have to have a solid brick mesh, you could select the bottom surfaces of all chips at once and do an extrude -- or select tops and bottoms to do a 2-Surface Solid Create.
• Don't use the properties of glass-filled epoxy from PATRAN -- the k is too low for most boards -- and the properties seem to be such that you can get instability in trying to solve with high-power chips.
• The simplest and most accurate way to attach the chips to the board is to use contact convection.  Since you won't want any of the nodes to be equivalenced together, the best way is to translate the chips off the board by some distance (greater than your tolerance) before you mesh them.  Then apply properties and mesh.  You can apply contact conduction between the geometries by picking the chip bases as region 1 (easy to do in a side view), and the board as region 2.  The h value you select will define the chip temperatures, so make sure you include the effect of epoxies, pin connections, air convection, etc.
• Layers in the board will have a large impact since the amount of copper in each region will vary for each layer.  You don't have to do separate layers to be accurate, just make sure that each region of the board has a Cp and k appropriate for the percentage of copper present.
• Heat sinks and bolts will have huge effects on chip temperatures and are sometimes not included in the Pro/ECAD file.  Make sure you find out about any extras of this type.

An example board in Pro/E and PATRAN: