I've had better (faster) luck using a more aggressive solvent than alcohol. Acetone, Methyl Ethyl Ketone, good ol' Gumout Carburetor Cleaner, TFE based Brake Cleaners, just about anything is better than Alcohol. I chase the residue off with Q-Tips. FWIW, the average "white" thermal compounds, like what R.S. sells are not-conductive.