CREEP AND RELAXATION BEHAVIOR OF WOVEN GLASS EPOXY SUBSTRATES FOR MULTILAYER CIRCUIT-BOARD APPLICATIONS/

The creep behavior of a common woven glass/epoxy composite substrate f or multilayer circuit board applications was characterized using dynam ic mechanical analysis (DMA). The creep compliance was measured in bot h the warp and fill directions of the composite over a temperature ran ge of 30 degrees C to 155 degrees C. The creep compliance of the neat FR-4 epoxy matrix was also characterized for comparison with the compo site response. Master creep curves were obtained for the neat resin an d the composite in the warp and fill directions assuming thermorheolog ically simple behavior and applying the time-temperature superposition principle. The creep data was fit to a Prony series and then converte d to relaxation data in the Laplace domain. Micromechanical models wer e developed to predict the relaxation behavior of the woven glass/epox y composite from the elastic properties and the geometry of the glass fabric and relaxation behavior of the neat resin, Model predictions we re compared with experimental data.