Hmm. No so sure of the router plan.
The real risk I see is the fact that you are cutting vertical to the heat sink fins.
It is pretty easy to safely route a flat piece.
But cutting a fin like that, the router bit will really be chattering against the end at times.
It would be real easy to move the bit in too fast, and the router blade could easily shatter.
Probably ok if you use a spiral up-cut bit though.
The real risk I see is the fact that you are cutting vertical to the heat sink fins.
It is pretty easy to safely route a flat piece.
But cutting a fin like that, the router bit will really be chattering against the end at times.
It would be real easy to move the bit in too fast, and the router blade could easily shatter.
Probably ok if you use a spiral up-cut bit though.