US Patent 7897250 Polishing pad

The present invention provides a polishing pad whose unevenness in thickness hardly occurs and whose life can be improved. A polishing pad 1 is provided with a polyurethane sheet 2. Foams 3 having lengths of about ½ of the length of the polyurethane sheet 2 in its thickness direction and elongated foams 4 having lengths of at least 70% of the length of the polyurethane sheet 2 in the thickness direction are formed in the polyurethane sheet 2. The foams 3 and the elongated foams 4 are opened by buffing processing so that opened pores 5 and opened pores 6 are formed at a polishing face P, respectively. Regarding the opened pores 5, 6, the total number of opened pores having opened pore diameters falling in a range of from 30 to 50 μm occupies at least 50% of the number of all opened pores. The total number of the opened pores 5, 6 per 1 mm2 of the polishing face P is set in a range of from 50 to 100. An average value of ratio of an opened pore diameter D1 of the opened pore 6 of the elongated foam 4 to an opened pore diameter D2 of the opened pore 6 at a depth position of at least 200 μm from the polishing face P is set in a range of from 0.65 to 0.95.