Aerosol methods for making chemical mechanical planarization (cmp) polishing pads

Abstract

The present invention provides methods for making CMP polishing pads or layers therefore, the methods comprising introducing, separately, to a static mixer having a nozzle at its downstream end two solvent free and substantially water free components, a liquid polyol component having a temperature T 1 and a liquid isocyanate component having a temperature T 2 , each under a low gauge pressure of from 5 to 120 kPa (1 to 14 psi), the liquid polyol component comprising one or more polyol, an amine curative; and the liquid isocyanate component comprising one or more polyisocyanate or isocyanate-terminated urethane prepolymer; mixing the two components in the static mixer to form a reaction mixture, discharging a stream of the reaction mixture from the nozzle onto an open mold substrate having a urethane releasing surface, and curing to form a porous polyurethane reaction product.

We claim: 
     
         1 . A method of forming a chemical mechanical planarization (CMP) polishing pad comprising introducing, separately, to a static mixer having a nozzle at its downstream end two solvent free and substantially water free components, a liquid polyol component having a temperature T 1  and a liquid isocyanate component having a temperature T 2 , each under an absolute pressure of from 100 to 200 kPa, the liquid polyol component comprising one or more polyol, an amine curative; and the liquid isocyanate component comprising one or more polyisocyanate or isocyanate-terminated urethane prepolymer; at least one component, comprising a sufficient amount of up to 2.0 wt. %, based on the total solids weight of the reaction mixture of a nonionic surfactant to facilitate stabilization of pores, mixing the two components in the static mixer to form a reaction mixture, discharging a stream of the reaction mixture from the nozzle at ambient pressure onto a mold substrate having a urethane releasing surface, and curing at from ambient temperature to 130° C. to form a porous polyurethane reaction product having a density ranging from 0.6 gm/cc to 1 gm/cc. 
     
     
         2 . The method as claimed in  claim 1 , wherein the nozzle is equipped with an atomizing air inlet or air blast cap surrounding the outside of the nozzle whereby a stream of air flows past the tip of the nozzle and then axially along the discharged stream of the reaction mixture. 
     
     
         3 . The method as claimed in  claim 1 , wherein, the reaction mixture contains no added chemical or physical blowing agents. 
     
     
         4 . The method as claimed in  claim 1 , wherein the reaction mixture has a gel time of 2 to 300 seconds at the curing temperature. 
     
     
         5 . The method as claimed in  claim 1 , wherein upon introducing each of the liquid polyol component at temperature T 1  and the liquid isocyanate component at temperature T 2  to the static mixer, each has a viscosity of from 1 to 1000 cPs. 
     
     
         6 . The method as claimed in  claim 1 , wherein in the liquid polyol component, the amine curative is an aromatic diamine. 
     
     
         7 . The method as claimed in  claim 1 , wherein the liquid polyol component further comprises a plurality of microelements. 
     
     
         8 . The method as claimed in  claim 1 , wherein in the liquid isocyanate component, the isocyanate comprises an aromatic polyisocyanate or aromatic isocyanate-terminated urethane prepolymer. 
     
     
         9 . The method as claimed in  claim 1 , wherein the mold substrate comprises an open mold having a female topography that forms a desired groove pattern of a CMP polishing pad as the applied reaction mixture fills the mold. 
     
     
         10 . The method as claimed in  claim 1 , wherein curing the reaction mixture comprises initially curing at from ambient temperature to 130° C. for a period of from 1 to 30 minutes, removing the polyurethane reaction product from the mold, and then finally curing at a temperature from 60 to 130° C. for a period of 1 minutes to 16 hours to form a porous article.