Quote Originally Posted by zalbard View Post
I wonder if Liquid Ultra is just about as good of an option for IB die as Liquid Pro is.
The reason being that its structure resembles paste and, thus, is more likely to work better in cases with uneven surfaces and poor contact, while Liquid Pro makes a very thin layer.
Or am I wrong in this assumption?
No. As far as an IB die is concerned, Pro will be better (if properly applied). The die surface and underside of the IHS are flat, and after removing the black adhesive, you will find that the IHS will rest on the die without touching the PCB - so you know there is no gap between the 2 flat surfaces. Just apply a very thin layer to each (use a very small drop, smoothed out to a mirror finish on both) and you will have the very thin layer that makes Pro so effective. Ultra, which has less than half the thermal conductivity of Pro, won't be as effective. Pro is pure liquid with no bulk. Ultra uses a graphite copper matrix (small particles of graphite and copper mixed together) to add bulk to fill in gaps. Pro works best on flat, even surfaces, Ultra best on uneven surfaces. Regarding safety, they both contain gallium and are harmful to Aluminum, so I don't consider Ultra any safer than Pro.