Patent attributes
Provided is a polishing pad which is capable of providing a high flatness to a polishing workpiece and suppressing the formation of scratches, and a method therefor. The polishing pad comprises a foamed urethane sheet on the surface which includes closed cells and open cells and which satisfies the following requirements: (1) an open cell ratio is 20-80 vol % where the total volume of closed cells and open cells is taken as 100 vol %, (2) the ratio [tan δ (wet/dry) ratio] of a loss factor tan δ in a water-absorption state to that in a dry state is 1.3-1.7, the loss factors being measured according to JIS K7244-4 with an initial load of 20 g at a measuring frequency of 1 Hz at a temperature of 26° C. in a tensile mode over a strain range from 0.01 to 0.1%, and (3) the Shore DO hardness according to ASTM D2240 is 60-80.
