I made a QFN footprint, and put the zero on Pin 1. The layout is finished, and Gerbers submitted, but I realized later that the center of the part (for pick-and-place) is not correct.
I could fix the footprint (and will, in the future), but I get the distinct feeling that if I move the footprint in the editor so that the center is now centered, it will mess up my layout when I update the PCB.
Is there any way to leave everything exactly where it is, but move the little magenta “+” to the center of the part on the PCB?
I can’t find an easy way. Updating, changing and editing the footprint all move the footprint from its current position.
All I can suggest is:
Change pads to outline mode
Place Grid Origin exactly over magenta +
Open symbol in footprint editor
Change pads to outline mode
Using graphic lines, draw a + over the magenta + (you will need to edit the width of the graphic + lines to approx. 1/10 mil )
Change anchor
Change footprint on PCB to new one in Footprint editor.
Move new footprint in such a way as to place the graphic cross (in pin 1) exactly over the the grid origin
Remove the graphic + and the Grid origin.
Very messy, but can’t think of anything else.
Others may have really cool and clever ideas, I hope.
BTW, what I ended up doing was:
Measure the x,y offsets from pin 1 to the center of a nearby footprint…
Edit the footprint in the library.
Updated the footprint in the layout from the library.
Use the “Move with Reference” function to move pin1 on the updated footprint with the offsets I wrote down earlier, referenced to the same nearby footprint.
This worked perfectly, and no traces had to be changed.