The thermoelastic properties of several common woven glass/epoxy substrate materials were characterized in both the warp and fill directions. Five common commercially pressed cores (1080, 2116, 2313, 3313, 7628) were obtained from Polyclad, Inc. The cores consisted of either one or two plies of C-staged woven glass epoxy substrate sandwiched between 1 ounce copper cladding. After the copper was removed from the cores, samples were cut for either mechanical property characterization or microstructural analysis with the test axis lying along either the warp or fill direction. The crimp angle and relative fiber volume fraction of each fabric was first determined from photomicrographs of polished cross-sections.Next, Young's modulus was measured via standard tension tests at room temperature. The storage and loss moduli were then measured as functions of temperature using dynamic mechanical analysis (DMA). Finally, the coefficients of thermal expansion were determined using constant force thermal mechanical analysis (TMA) measurements.All of the substrates showed significant differences in microstructure and material properties between the warp and fill directions. Most of the laminates had a much lower crimp angle in the warp direction which resulted in a higher modulus and lower coefficient of thermal expansion than the fill direction. Of the cores investigated, the properties of 3313 were the most balanced.
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