Method of forming silicate polishing pad

1. 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.

2. The method of claim 1 wherein the polymeric microelements include silicate fines and including the additional step of separating the polymeric microelements from the wall of the Coanda block.

3. The method of claim 2 wherein the separating of the silicate fines and coarse polymeric microelements occur in a single step.

4. The method of claim 1 including the additional step of directing two additional gas streams into the polymeric microelements to facilitate separating the polymeric microelements from the coarse polymeric microelements.

5. The method of claim 1 wherein the inserting the polymeric microelements into a polymeric matrix includes mixing the polymeric microelements into a liquid polymer matrix.

6. 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 less than 50 percent of the outer surface of the polymeric microelements; and being associated with greater than a 0.2 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.

7. The method of claim 6 wherein the polymeric microelements include silicate fines and including the additional step of separating the polymeric microelements from the wall of the Coanda block.

8. The method of claim 7 wherein the separating of the silicate fines and coarse polymeric microelements occur in a single step.

9. The method of claim 6 including the additional step of directing two additional gas streams into the polymeric microelements to facilitate separating the polymeric microelements from the coarse polymeric microelements.

10. The method of claim 6 wherein the inserting the polymeric microelements into a polymeric matrix includes mixing the polymeric microelements into a liquid polymer matrix.