Originally Posted by Bman212121
Actually, the smoother the better. The only reason for needed TIM at all is because there are holes to fill so there isn't just air. (TIM conducts heat better than air) The ideal situation would be having both surfaces so flat that when you combine them together it makes both pieces of copper bond to each other making one solid piece of copper. Now I don't have physical data to back up that claim so maybe they know some special case where that may help, but from a science standpoint it makes a lot more sense to have one solid piece of copper for the best possible heat exchange. The only thing I could see changing that is if TIM conducts heat better than copper. Given that too much TIM makes it act like an insulator would make me think otherwise.
The flatter the better. If you finish it too smooth the TIM will just run off with high heat. I've had this happen. You dont want a mirror finish on the chip, trust me. Doesn't sound like you've been doing this too long, but you want a flat finish with 600 or 800 for the best results. I've tested with multiple water blocks and many many chips over the years.