Influence of substrate structure on electromagnetic shielding effectiveness of copper film prepared by magnetron sputtering

Copper films,whose shielding effectiveness of electromagnetic wave were tested by frequency spectrum analyzer combining with special transmission line in the frequency extension of 100 MHz-1.5 GHz,were produced on the surfaces of PET woven,knitted and nonwoven fabrics by direct current(DC) magnetron sputtering,respectively.SEM was used to observe the surface morphology of the samples.Microscope was used to observe the pores of the substrates.The analysis revealed that the surface morphology and pores of the substrates had influences on their electromagnetic shielding effectiveness,but the former had a more significant role.In accordance with all of the continuity of the conductive network,the three-dimensional and the tightness of the geometry structure,and the non deposition surface of polyester blank sample geometry′s influence on the surface resistance,surface absorption loss and reflection loss of the electromagnetic,the difference of the shielding effectiveness curves between the face and back of the nonwoven fabric was analyzed.The face of the nonwoven fabric had better shielding effectiveness due to the tightly linked fibers and the continuous conductive network after deposition of copper;however,the shielding effectiveness of the face of the woven or knitted fabrics was worse.Apart from the tightness and flatness on the surface,the size and distribution of pores have impact on the shielding effectiveness and the shape of frequency curves.