Quantitative evaluation of slurry flow behavior using digital image processing

Lapping is generally used in fabricating high-accuracy hard and brittle materials. In lapping, slurry mixed free abrasive grains and water or dispersion oil is used. It is well known that the lapping characteristics are affected by actual slurry flow in the contact surface between the workpiece and lapping platen. Therefore, stabilization of slurry flow is required to improve lapping characteristics. This paper presents both quantitative evaluation method and results of slurry flow behavior at lapping process, and investigates the movement direction and velocity of slurry flow behavior. Single wafer lapping method was used for our experiment. Furthermore, digital image correlation (DIC) method was used for quantification. As a result, the following points were observed. (1) DIC method can evaluate slurry flow behavior among full-field observed photographed area. (2) Slurry flow velocity has not correlation with relative lapping velocity between the workpiece and lapping platen. (3) Slurry flows much into contact surface along a turn of lapping platen.