Aluminum nitride (AlN) is widely used in the field of electronics because it has high thermal conductivity, good electric and mechanical properties. On the other hand it has a shortcoming of being difficult to wet metals. Therefore, various contrivances are needed to form a metal film with high adhesion strength on AlN surface. In this paper we will review the vacuum technology that has been used up to now, and mention the middle thickness film printing method that will be a key technology from now on. Adhesion mechanism in the interface between AlN and metal film will be also reported.