Midway through the process of adding the pattern layers to the surface of the wafers, the wafer goes through a process called chemical mechanical polishing or CMP. In chemical-mechanical polishing, chemical agents and abrasives work jointly on the wafer surface to produce a precise surface finish. Homo-polymer and co-polymer acetals, Ertalyte® PET-P Techtron®, PPS or Ketrontm PEEK are used as holding rings that retain wafers during polishing. Techtron® PPS and Ketrontm PEEK withstand the worst chemical and mechanical stresses present during polishing, and are therefore used when the demand is for high strength and wear resistance. The water-driven track system is manufactured from Ertalyte® PET-P, due to its high purity, low coefficient of friction, dimensional stability and non-staining characteristics.

Techtron® PPS

Advantages

• Excellent chemical resistance
• High strength and stiffness to 230°F (HDT)
• Dimensional stability (low water absorption and low CLTE)
• Easily machined

Limitations

• Low heat deflection

Ketron^TM PEEK

Advantages

• Excellent chemical resistance
• High strength and stiffness to 320°F (HDT)
• Thermal stability to 480°F (CUT)
• Good wear and abrasion resistance

Limitations

• Chemical resistance to halogens and their acids including bromine, chlorine, fluorine, HBr and HF

Acetron® GP-Acetal

Advantages

• Good impact and moderate chemical resistance
• Thermal stability to 200°F
• Good wear and abrasion resistance
• Low water absorption

Hydex 4101 comes in both a white (natural) color and black. It is a standard stock material in a wide range of diameters and thicknesses

Ertalyte® PET-P

Advantages

• Wear resistance of nylon dimensional stability greater than acetal
• High strength, rigidity and stiffness
• Ideal for close tolerance parts
• Excellent stain resistance
• Good chemical resistance to acids and bases
• Good for both wet and dry applications due to low moisture absorption