Method for manufacturing chemical mechanical polishing pad polishing layers having reduced gas inclusion defects
View Patent ↗A method for manufacturing chemical mechanical polishing pad polishing layers that minimizes entrained gas inclusion defects is provided. Also provided is a mix head assembly for use in the manufacture of chemical mechanical polishing pad polishing layers, wherein inclusions of entrained gas inclusion defects are minimized.
1. A method of forming a chemical mechanical polishing pad polishing layer, comprising:
providing a mold;
providing a liquid prepolymer material;
providing a plurality of microspheres in an inert carrier gas;
providing an inert purge gas;
providing a mix head assembly, having a housing with at least one housing inlet and a housing outlet; a seal interfaced with the housing; and a rotating mixer with a shaft; wherein the rotating mixer is disposed within the housing; wherein the shaft extends out of the housing through the seal; and wherein the shaft has a passage therethrough with a shaft passage inlet and a shaft passage outlet to facilitate venting of the inert carrier gas and the inert purge gas out of the housing through the shaft passage;
combining the liquid prepolymer material with the plurality of microspheres in the inert carrier gas in the housing, under the action of the rotating mixer, forming a mixture of liquid prepolymer and microspheres;
supplying the inert purge gas to the housing;
venting the inert carrier gas and the inert purge gas from the housing through the shaft passage;
transferring the mixture of liquid prepolymer and microspheres through the housing outlet to the mold;
allowing the mixture of liquid prepolymer and microspheres to solidify into a cake in the mold; and,
deriving a chemical mechanical polishing pad polishing layer from the cake.
2. The method of claim 1 , wherein the liquid prepolymer material comprises a polyisocyanate-containing material.
3. The method of claim 2 , wherein the liquid prepolymer material further comprises a curing agent.
4. The method of claim 1 , wherein the seal is a labyrinth seal; further comprising:
feeding the inert purge gas through the labyrinth seal into the housing.
5. The method of claim 4 , wherein the labyrinth seal is a radial labyrinth seal.
6. The method of claim 1 , further comprising:
slicing the cake into a plurality of chemical mechanical polishing pad polishing layers.
7. The method of claim 1 , wherein the cake contains fewer entrained gas inclusion defects compared to a cake manufactured by the same process without providing the inert purge gas.
8. The method of claim 1 , wherein the inert carrier gas is carbon dioxide.
9. The method of claim 1 , wherein the inert purge gas is carbon dioxide.