| abstract |
A SHAPED COPOLYMER COMPRISED OF ETCHABLE POLYMER AND UNETCHABLE POLYMER CONTRIBUTING DESIRED PROPERTIES TO THE COPOLYMER IS BOMBARDED WITH CHARGED PARTICLES. AS THE PARTICLES PASS THROUGH THE SHAPED COPOLYMER. THEY FORM SUBSTANTIALLY STRAIGHT TRACKS OF DAMAGED COPOLYMER. THE BOMBARDMENT OF THE COPOLYMER WITH THE INDIVIDUAL CHARGED PARTICLES IS SO HIGHLY LOCALIZED THAT IT DAMAGES ONLY THE TRACK DEFINING PORTIONS OF THE COPOLYMER LEAVING THE REMAINDER OF THE COPOLYMER SUBSTANTIALLY INAFFECTED. THE COPOLYMER IS THEN CONTACTED WITH AN AGENT TO ETCH, I.E. EXTRACT, THE TRACKS OF DAMAGED COPOLYMER, AND ANY ADDITIONAL DESIRED PORTION OF ADJACENT UNDAMAGED COPOLYMER, LEAVING A SUBSTANTIAL NUMBER OF RECESSES OR APERTURES DEPENDING UPON THE PARTICULAR BOMBARDING PROCEDURE AND THE THICKNESS OF THE COPOLYMER. THE APERTURE-CONTAINING COPOLYMER PRODUCT OF THE PRESENT INVENTION INCLUDES PROPERTIES USUALLY ASSOCIATED WITH NONETHCABLE POLYMER. IT IS USEFUL AS A FILTER. |