Pre-galvanized steel (ASTM 653A, G90 Coating) has proven to be the most cost effective tray material. Its flat, smooth surface is formable, weldable and conductive. It has excellent corrosion resistance. Coatings or painted surfaces are not conductive and work against shielding effectiveness.
Surprisingly the overall shielding effectiveness of RF Tray is determined more from the elimination of seams or gaps than from the mass or thickness of the materials used.