Its special three-dimensional space channe l enables thousands of square meters of internal surface area per square meter of filtration area with high dirt holding capacity and filtration quality. After filtration, the turbidity is good, with three functions of sieving, depth, and electrostatic adsorption. The filtered liquid is accurately controlled through a large number of maze-like small three-dimensional spaces with different lengths. The volume of micropores accounts for more than 75%, which is even smaller. All the solids and microorganisms are retained under the positive charge adsorption of the cardboard, and the filtering effect is good. Our company's fine filter pad pioneered the filming technology of the filter sheet, and the double-folded part of the paperboard was reinforced. The compressive strength of the filter plate can be enhanced, that is, the service life of the filter plate is prolonged and it is more convenient for users to use.