Abstract: A method of manufacturing an electromagnetic wave shielding material using a perforated metal thin plate, the method including: forming a gel coat to a mold; forming a first metal layer on a first composite layer by arranging a perforated metal thin plate, after forming the first composite layer on the gel coat layer formed in the first step; forming a second metal layer by arranging a perforated metal thin plate and the first metal layer formed in the second step in such a way that positions of perforations are arranged in a staggered manner without overlapping, after forming a second composite layer on the first metal layer formed in the second step; and molding the electromagnetic wave shielding material by curing and demolding after forming a third composite material on the second metal layer formed in the third step.

Abstract: An exemplary composite filter medium is disclosed which can include a melt-blown nonwoven fabric layer having a weight of 5 gsm to 40 gsm and include a fiber with a fiber diameter of 1 ?m to 3 ?m and a wet-laid nonwoven fabric layer located on the melt-blown nonwoven fabric layer, the wet-laid nonwoven fabric layer having a weight of 40 gsm to 100 gsm and including 5 wt % to 30 wt % of a glass fiber with a fiber diameter of 0.1 ?m to 2 ?m.