In this article, the dimensional stability of epoxy- and cyanate-based laminates is discussed, focusing on the thermal deformation, moisture-induced deformation, and deformation induced by relaxation of thermal residual stress. Each of the deformations was calculated independently based on the laminate theory. The material properties of the unidirectional laminates were obtained by conducting thermal mechanical analysis, moisture absorption tests, and tensile creep tests. These material properties were adopted to the laminate theory to predict the deformation of quasi-isotropic laminate, and it was calculated that each type of deformation induced micron-level dimensional instability. The moisture-induced deformation was an order of magnitude larger than that caused by the other factors. The validity of the calculations was confirmed by comparing the calculated results with the experimental ones. It is important to control moisture absorption even if cyanate resin, which has high moisture resistance, is used.
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