The effect of substrate surface roughness and sintering temperature on the adhesion strength of Ag-based thickfilm conductors formed on AlN substrates with excellent thermal conductivity was studied. The adhesion strength of thethick-film conductor manufactured using an AlN substrate having a surface roughness (Ra) of 0.5 was higher than that of athick-film conductor manufactured using a substrate having a surface roughness greater or smaller than this. In the case ofa substrate with a surface roughness of less than 0.5, the contact area between the Ag thick film conductor and the substratewas relatively smaller than that of a substrate with a surface roughness of 0.5, resulting in a lower adhesive strength. Onthe other hand, when a substrate having a surface roughness of more than 0.5 was used, it was found that the conductorfilm was not completely adhered to the substrate, and as a result, it was found that the adhesive strength was small. Inaddition, it was found that the surface smoothness of the Ag-based thick film conductor film obtained by sintering at 850oCwas the best compared to the smoothness of the conductor film obtained by sintering at different sintering temperatures,and as a result, it was found that the adhesive strength of the conductor film was the highest.