I've never seen it on large logic chips, but this is pretty common on power ICs. Look up TI's HotRod QFNs for a particularly well-marketed example. Of course, t

I've never seen it on large logic chips, but this is pretty common on power ICs. Look up TI's HotRod QFNs for a particularly well-marketed example. Of course, the fab processes here are basically stone-age (for example, 0.6um BCD is still very common), so such things are easier to do and more beneficial for high-power parts.