Patent ID: 7799254

Claim:
A method for treating a film, comprising: providing a web of polymeric film having a front face and a reverse face, providing a structure including a substrate and an array of upstanding projections having an average width dimension of less than 200 μm, each projection including multiple contact points that are positioned to produce a non-uniform pressure distribution when film is stretched between the contact points of a projection, providing a backing form made from a resilient material of appropriate stiffness to enable the projections to penetrate into or through the surface of the film, and pressing the film between the projection-bearing surface of the structure and the backing form a sufficient distance to fix the film against the contact points and creating a non-uniform pressure distribution across the film in the region between the separate contact points in a projection and causing rupture of the film between the separate contact points in the projection while the film is fixed without heating the structure or the film during the pressing step.