We need to understand the force-bearing characteristics of the asperity-rich pad surface. The scale of this perspective shrinks another order of magnitude from that used to examine the pad’s pore structures. As seen in Figure 6.16, the wafer compression action on the polymer material is likely to show a viscoelastic response (the compression span of the traveling wafer is sufﬁciently long for the polymer material to respond viscoelastically). The asperities in contact with the wafer surface will then suffer a viscoelastic modiﬁcation. The nature of this modiﬁcation will be deﬁned by the forces at work on the asperity proﬁles.