The following equation is used for determining the viscosity of these materials: where:
- is the viscosity (Pa. sec.)
- is the shear rate (1/sec.)
- is the temperature (deg K)
- is the degree of cure (0 - 1),
- , and
- , , , , , , , , and (gelation conversion) are data-fitted coefficients.
Note Use this model for thermoset materials that do not show yield behavior at low shear rates. For materials that do show yield behavior at low shear rates, use the Herschel-Bulkley-WLF viscosity model. For underfill encapsulants, use the viscosity model for Underfill Encapsulation.