[bsder]

Hmmm, never thought about that. I don't think I've noticed a different minimum web requirement based on color for 0402-class and QFN stuff, but I could certainly believe it for extremely small footprints and high-density BGAs.

Where I seem to see issues with green soldermask coverage are tented vias underneath components.

The canonical example is a non-GND via underneath a QFN component with a pad. However, I have also seen issues with vias next to large pads of power transistors where the transistor can "float" around on the solder.

This seems counterintuitive since I would expect the main soldermask color to be used for more BGA-type components where the breakout vias would need to be covered properly. Nevertheless, experience suggests otherwise.

I finally got fed up once and ordered the same PCB with green soldermask for one batch and blue for another. The green ones had some via coverage fails; the blue ones didn't have any. Since then, I've just avoided green soldermask unless I'm going for uber-volume levels of PCBs.