Patent ID: 8202334

Claim:
A method of preparing a silicate-containing polishing pad useful for polishing at least one of semiconductor, magnetic and optical substrates comprising: a. introducing a feed stream of gas-filled polymeric microelements into a gas jet, the polymeric microelements having varied densities, varied wall thickness and varied particle size, the polymeric microelements having silicate-containing regions distributed on an outer surface of the polymeric microelements, the silicate-containing regions being spaced to coat 1 to 40 percent of the outer surface of the polymeric microelements; and being associated with greater than a 0.1 weight percent total of the following: i) silicate particles having a particle size of greater than 5 μm; ii) silicate-containing regions covering greater than 50 percent of the outer surface of the polymeric microelements; and iii) polymeric microelements agglomerated with silicate particles to an average cluster size of greater than 120 μm; b. passing the gas-filled microelements in the gas jet adjacent a Coanda block, the Coanda block having a curved wall for separating the polymeric microelements with Coanda effect, inertia and gas flow resistance; c. separating coarse polymeric microelements from the curved wall of the Coanda block to clean the polymeric microelements; d. collecting the polymeric microelements with less than 0.1 weight percent total of the polymeric microelements being associated with i) silicate particles having a particle size of greater than 5 μm; ii) silicate-containing regions covering greater than 50 percent of the outer surface of the polymeric microelements; and iii) polymeric microelements agglomerated with silicate particles to an average cluster size of greater than 120 μm; and e. inserting the polymeric microelements into a polymeric matrix to form a polishing pad.