I am trying to create a padstack for an LGA package, and the manufacturer suggests an offset solder mask relative to the PCB land - in this particular case they recommend a solder mask opening equal to the PCB land length + .3mm, with the solder mask extending .05mm beyond the land on the inner edge, and .25mm beyond the land on the outer edge.
I don't see an obvious way to do this when I create the padstack (the padstack editor centers the solder mask on the pin), and I'm not aware of any way I can select and move only the solder mask part of the padstack when I'm editing the component footprint. I thought perhaps I could create two padstacks - one with only copper/paste mask, one with only solder mask, but I'm guessing I'll have twice as many pins as I need if I do that. Any thoughts on how to accomplish this the "right" way?
I'm using PCB Editor 16.5.
Thanks in advance for any help!