In this investigation, the effects of N(2)/(Ar+N(2)) gas partial pressure on the structural, electrical, and thermal properties of AlN dielectric layers prepared on aluminum substrates using RF-magnetron sputtering method were analyzed. Among the films, the AlN dielectric film deposited under N(2)/(Ar+N(2)) gas partial pressure of 75% exhibit the highest AlN (002) preferred orientation, which was grain size of about 15.3(2) nm and very dense structure. We suggest the possibilities of it`s application as a dielectric layer for metal PCB because the AlN films prepared at optimized gas partial pressure can improving the insulating property, the thermal conductivity, and thermal diffusivity of the films.