Thermal Pad Issue

80% Paste Mask Reduction will provide a single paste mask aperture. 

70% is the highest Paste Mask Reduction to generate a Checker Board Pattern. 

You have a Minimum Paste Mask web set to 0.20 mm. 

You need to keep the Thermal Pad Paste Mask 0.10 mm indented from the pad edge. 

80% is doable however, you're not going to get a Checker Board Pattern. 

Many users set Thermal Pad Paste Mask to 100% and allow the Assembly Shop Stencil Mfr. design the paste mask reduction. 

All we're saying is that we found out that 70% is the highest you can go a still get a Checker Board Pattern. 

We're not going to limit the software program and not allow 80%. If you're not educated on the mathematics of paste mask reduction, and the consequences of your Option settings, that's not our responsibility. It's trial and error. 

Footprint Expert had the default Thermal Pad Paste Mask Reduction setting at 50% for many years from 2004 - 2016. We bumped it up to 60% default after helping IPC develop the IPC-7093A standard in 2017. 

For many years we set the Thermal Pad Paste Mask reduction should be between 40 - 60% with 70% being the limit to accommodate both the Thermal Pad Minimum Space (between checkerboard patterns) and the paste mask apertures. 

You have to understand the mathematics involved in paste mask reduction and the minimum aperture spacing rule. You do the math and you'll see that everything works accordingly. Take any pad and reduce the size by 80% and see the results.