Hyun-Seop Leea, Yong Suna, Changsu Kima, and Bongtae Hana
a CALCE, Center for Advanced Life Cycle Engineering, Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20740, USA
The linear viscoelastic properties of epoxy molding compound (EMC) are measured by an
embedded fiber Bragg grating (FBG) sensor. A single cylindrical EMC specimen is fabricated,
and it is subjected to constant uniaxial compression and hydrostatic pressure at various
temperatures. The FBG embedded in the specimen records strain histories as a function of time.
Two linear viscoelastic properties (Young’s modulus and bulk modulus) are determined from the
strain histories. The master curves of two properties are produced, and the corresponding shift
factors are determined using a piecewise function. Validity of three major assumptions associated
with the linear viscoelasticity - thermorheological simplicity, Boltzmann superposition and
linearity - are verified by supplementary experiments. The accuracy of the measured properties is
corroborated by the warpage measurement of a bi-material specimen subjected to a temperature
cycle. The effect of the time-dependent bulk modulus on the warpage is also discussed.
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