The 120-5. from Wakefield Solutions is a silicone oil-based thermal joint compound. This fills the minute air gap between mating surfaces with grease like material containing zinc oxide in a silicone oil carrier. It possesses an excellent thermal resistance of only 0.05�C/W for a 0.001inch film with an area of one square inch. There is no measurable increase in case temperature of a mounted semiconductor on a heat sink after the 6month stabilization period.