A filter support sheet extruded from a fluoroplastic material includes a base section having spaced-apart ribs extending outwardly from at least one surface thereof. Segments between spaced-apart ribs provide flow channels and apertures are punched through the sheet in a predetermined pattern unaffected by the structure of the support sheet. A method includes the steps of: (1) extruding a thermoplastic, fluoroplastic material to form of a sheet; (2) passing the sheet through a nip region provided by opposed rollers; at least one having an outer surface with counter-sunk grooves. Counter-sunk grooves in one roller are aligned with an outer surface or counter-sunk grooves of the other roller in the nip region to form a ribbed sheet having ribs upstanding from at least one surface of said sheet; (3) setting the ribbed sheet and (4) punching apertures through the ribbed sheet in a predetermined pattern.