METHOD OF SELECTING SHEET MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a selection method for selecting a sheet material suitable for a polishing liquid before polishing.SOLUTION: A polishing pad includes a urethane sheet fabricated by the wet coagulation method. The urethane sheet contains polypropylene oxide as a regulator. The urethane sheet having suitability for the polishing liquid which is supplied in polishing and contains abrasive grains is selected. The selection method includes: a preparation step of preparing a sample for immersion from the urethane sheet; an immersion step of soaking the sample in the polishing liquid with a weight of 25-35 times of the weight of the sample and leaving it at rest for at least 24 hours; a condition checking step of checking the presence of milky state in the polishing liquid after the sample immersion by comparing with the polishing liquid before the sample immersion; and a selection step of selecting the urethane sheet without opacity occurring as a sheet suitable for the polishing liquid.