Do you know the size of hole in stencil that have to be divided into smaller once?
I came to that doubt when modifying QFN-48-1EP_6x6mm_P0.4mm_EP4.3x4.3_ThermalVias footprint.
I replaced 0.2mm holes with 0.3mm.
I decided to reduce their number from 4x4 to 3x3 (to let VCC copper at inner layer to get between these vias).
My first idea was to have 4 octagonal holes in stencil. Like one on the right - it is 1.6x1.6mm.
But it looks huge compared to holes for 48 pads. I started to think if the tool (never seen it) used to spreading the paste isn’t too flexible and doesn’t take the paste from the inside of such a large hole.
So may be it should be done with smaller holes - I put some rectangles on the left to show that idea:
Do you know how it should be done?
Reading about how much paste at exposed pad I sow data from 25% till 80%.
As under QFN the paste has no place to run away than may be in this case it should be closer to 25% than 80%.
Is someone knowing it?