I am making a board for ATmega324PB which is in TQFP lead package. Due to shortages and stuff I want to make sure that my PCB design can take ATmega324PB in other package too (QFN/VQFN) with minimal changes (Like I just have to change the footprint).
I have many vias underneath the chip for TQFP package for routing and stuff, but unsure about the other packages(VQFN/QFN), does it have a bottom pad? So if there is a bottom pad then it won't work with underneath vias, (it might but I am not comfortable doing it). Then I will be stuck with only TQFP package.
On mouser there two images for it.
One without the pad.
and one with the pad.
In datasheet I do see something underneath but I am unsure.
- If it is pad, is it connected to ground?