US Patent 10259099 Tapering method for poromeric polishing pad

The method forms a porous polyurethane polishing pad by coagulating thermoplastic polyurethane to create a porous matrix having large pores extending upward from a base surface and open to an upper surface. The large pores are interconnected with small pores. Heating a press to temperature below or above the softening onset temperature of the thermoplastic polyurethane forms a series of pillows. Plastic deforming side walls of the pillow structures forms downwardly sloped side walls. The downwardly sloped side walls extend from all sides of the pillow structures. The large pores open to the downwardly sloped sidewalls are less vertical than the large pores open to the top polishing surface and are offset 10 to 60 degrees from the vertical direction.