Most of electronic parts generate heat during the operation, and so the heat removal therefrom is required for making them function properly. As to heat-reducing materials applicable to electronic parts, there are high expectations for aluminum nitride because of its high thermal conductivity and electric insulation. The aluminum nitride can be used in various forms, e.g., as a molding and a powder for the filler of grease or rubber.
For achieving high thermal conductivity by the use of aluminum nitride powder as the filler of grease or rubber, it is necessary to raise the filling rate of the aluminum nitride powder. In the case of grease, therefore, the use of a wetter or the art of using as a base oil a modified oil having good wettability has so far been proposed as a solution for raising the filling rate. However, both proposals have failed in achieving satisfactorily high filling rate of aluminum nitride to result in being unsuccessful at obtaining high thermal conductivity.