Liquid crystalline epoxy resin modified cyanate ester for high performance electronic packaging

A high performance modified cyanate ester (CE) resin system with significantly improved toughness, water resistance and dimensional stability was developed by copolymerizing CE resin with liquid crystalline epoxy resin (LCE) for electronic packaging. Four LCE/CE resins with different contents of LCE were prepared to systemically evaluate the effect of the content of LCE on the key properties of the modified system such as mechanical, dielectric and thermal properties as well as water resistance. Results reveal that the addition of LCE to CE can not only decrease the curing temperature of CE, but also significantly improve the integrated properties including mechanical and dielectric properties, thermal resistance as well as water resistance of cured resin. For example, compared with the whole exothermic peak of CE, that of LCE10/CE significantly shifts toward low temperature with a gap of about 15°C. On the other hand, the impact strength of cured LCE10/CE resin (22 kJ/m²) is about 2.1 times of that of CE resin; while the water absorption of the former is only 81.2% of that of the latter. In addition, cured LCE/CE resins also exhibit lower and more stable dielectric loss than CE resin over the whole frequency range from 10 to 10⁶ Hz. All these improvements in macro-performance by the addition of LCE to CE resin are not only ascribed to the cross-linked chemical structure, but also attributed to the rigid structure of liquid crystalline resin. The outstanding integrated properties of LCE/CE resins suggest great potential to be applied in the field of high performance electronic packaging.