Design and Evaluation of a Cyanate Ester Containing Oxaspirocyclic Structure for Electronic Packaging

Abstract

A type of pentaerythritol cinnamaldehyde bisphenol dicyanate ester (PCBDCy) containing oxaspirocyclic structure is well designed and synthesized in three steps from cinnamaldehyde, pentaerythritol, phenol, and cyanogen bromide. The products in each step are characterized by elemental analysis, Fourier transform infrared (FT-IR) spectroscopy, and 1H NMR spectroscopy. The mechanical properties, dielectric properties, thermostability, and water absorption of PCBDCy are investigated in detail. The results show that compared with bisphenol A dicyanate (BADCy), the PCBDCy possesses more excellent comprehensive properties. The bending strength and flexural strength are increased by 10.71% and 47.62%, respectively. The fracture toughness $K_{\text{IC}}$ and $G_{\text{IC}}$ are 1.5 times and 2 times of BADCy, respectively, indicating that its mechanical properties have been considerably improved. The dynamic mechanical curves indicates that the degree of phase separation is significantly reduced, the tan (δ) value representing the flexible phase is obviously shifted to the high temperature region, and the initial decomposition temperature was 12°C higher than that of BADCy, indicating that the material has excellent thermal stability. In addition, the dielectric constant and loss tangent are almost as same as those of BADCy, maintaining good dielectric properties. The water absorption rate has increased to $1.03\pm 0.03\%$ . Compared with BADCy, its comprehensive performance is more suitable for the field of microelectronic packaging.