Method for forming a porous reaction injection molded chemical mechanical polishing pad

The present invention provides a method of forming a chemical mechanical polishing pad comprising, providing a tank with polymeric materials, providing a storage silo with microspheres and providing an isocyanate storage tank with isocyanates. The invention further provides delivering the polymeric materials and the microspheres to a premix prep tank, forming a pre-mixture of the polymeric materials and the microspheres, delivering the pre-mixture to a premix run tank and forming a mixture of the pre-mixture and the isocyanates. Further the invention provides injecting the mixture into a closed mold, curing the polishing pad in the mold and degassing at least one of the tank, isocyanate storage tank and the mold.