Milling a One-Sided PCB in Etcheverry

Step 1: Creating the appropriate layout files

Once your board is in an acceptable form, you will want to create the Gerber files that the milling machine software uses. In Orcad,

Make sure settings are correct:

1. Go to Options/Gerber Settings.  Note the 3.4 designation.
2. Go to Options/Post Processing Settings.  You want to make sure that every layer you need is included here and listed as Extended Gerber.  These layers include TOP, BOT, BRD, DRD, etc. If not all are listed, the easiest thing to do is to import post processing settings from another layout. Go to the other layout that has been milled previously, right click in the post-processing settings screen and Save Post Process Setup.Pick whatever file name you please. Now go back to your layout and load these settings by right clicking and selecting Load Post Process Setup. Load the file that you just saved. The layers you need should be on there. If not, I would suggest the help menu. Make sure all are Extended Gerber.

Run the Post Processor to create GBD file.

1. Go to Auto/Run Post Processor. It should save a GBD file of the same name as your layout and a .tap file (usually thruhole.tap).

Now return to the main Orcad Layout screen to open the GerbTool. Select Tools/GerbTool/Open and select the file you have just created.

A small picture of your board layout should show up on the screen. You can zoom in on it by clicking and dragging a window around your board with the mouse. To the right of the layout picture are boxes of different colors that signify the different layers. Try unchecking and checking others (always followed by a click on the glasses to update) to view the different layers of your board. If something looks fishy or is missing, you probably need to go back to Post Processing Settings.

Now we need to tell the milling machine how to drill the board. We personally only have a few drill bits to choose from, so make sure the pads are large enough to accommodate these bits.

1. Go to Layers/Create to create a new layer. It means nothing yet, but you should be able to see it appear in the layer boxes.
2. Now go to File/Format/Drill and make sure the setting is the same as was set in the Gerber Settings (likely 3.4).
3. File/Import/Drill. Show all files and select the thruhole.tap file created earlier. This shows the milling software where to drill.
4. View the layer that was created. This should show small dots inside of the pads you want drilled. If not, find help.
5. Now we need to save this information in a format that the software can understand. Go to Tools/Drill/Save. The output file should be drill.nc and the report file drill.tol. If you click the NC format button, it should show the 3.4 resolution. If not, you will need to set this as instructed earlier before going further. OK.
6. Save this!

All of the appropriate GBX files and drill files (*.GBX, drill.nc and drill.tol) can be saved onto a floppy for transport to the milling machine! You may proceed to Step 2.