I have some equipment which uses a power amplifier (15 lead TO-220) mounted on one of these on a PCB...
No problems until now, it runs cool because the duty cycle is low, in fact it would be fine without a heat sink, I just need the power for a few percent of the time.
However, a new customer wants to use the equipment in an unusual manner such that the duty cycle for the amplifier is high, above 50%. Consequently, it gets hot and goes in and out of thermal limit. It's not far off working and takes several minutes or tens of minutes to manifest the problem.
I can't spare much extra height, don't want to change the board, fans are ugly.
So I'm thinking a right angle of aluminium with a large horizontal surface area and a thick vertical tab for the amplifier. Or copper. Or maybe leaving the heat sink as it is and screwing a large flat plate on top (the heatsink is the highest thing on the PCB). Heat pipe?
Just casting around for ideas.