Stress relaxation describes how polymers relieve stress under constant strain. Because they are viscoelastic, polymers behave in a nonlinear, non-Hookean fashion. When a compressed load is applied to the TIM, there is an initial deflection followed by a slow relaxation process; the process continues till the compressive load is balanced by the cohesive strength of the material. The graph shown here shows that the stress relaxation occurs very quickly after peak stress is removed. It is important to note the stress relaxation in an application, to ensure that sufficient relax stress provides the cohesion contacts between the two surfaces and not overstressing the surfaces for long term reliability issue.