Package Geometry vs Board Geometry?

Fraser,

My recommendation is to always map to the Package Geometry when building library parts. However, Board Geometry would work too. The goal is to have your masks show up on your artwork files at the end of the day. The Board really should be used when you need to add mask pull backs to your board in selective areas.

Remember, you just have to make sure you have ether of these layers are turned on to output into our Gerber (artwork) files.

Also, depending how you toggle your layers on and off while your our designing my be a slight issue for you. Try both to see what works for you. For me I have programmed a key just to turn on both these layers to view solder masks anyway. but, that's just me.

Cheers

I suggest to always use the package geometry soldermask to draw soldermaks openings in library parts.

Shortly:
PGO soldermask to PGO soldermask items generate DRCs when placed too close to each other. (even shapes, so not only padstack masks)
BGO soldermask to BGO soldermaks or PGO soldermask does not generate any DRC.

So, package related masks always on the package geometry, this way you are sure you don't accidently place them too close.
If you want to place a large soldermask opening in the design (not library) and you don't want to get DRCs then you place it on the board geometry soldermask.

Bram