Aging behavior, mechanism and lifetime prediction of liquid crystal polymer films under thermal and oxidative conditions for 5G communication applications

Abstract

Liquid crystal polymer (LCP) materials have emerged as a promising solution for 5G communication applications owing to their exceptional properties and suitability for high-frequency applications. However, the utilization of LCP materials is accompanied by challenges related to aging-induced quality, necessitating extensive research on aging mechanisms and mitigation strategies to ensure sustained reliability and performance in the face of harsh operating conditions and prolonged service life. To address this issue, LCP films were successfully prepared using the blow molding technique. Subsequently, a comprehensive investigation was conducted to explore the aging behavior, predict the lifetime, and understand the underlying aging mechanism of these films under thermal and oxidative conditions. The results indicate that the LCP film maintains a high level of functionality for up to 36 years at 100 °C, 11 years at 120 °C, and 2 years at 150 °C, based on the failure criterion of the dielectric loss factor (Df). The simultaneous occurrence of physics aging and chemical aging, including the relaxation process of main chains, thermal decomposition, Fries rearrangement reactions, and cross-linking reactions, contribute to the aging of the LCP film. Moreover, a specific fluorescence recognition strategy was used to monitor the aging state, providing a promising approach to elucidate the aging behavior of LCP films. These findings offer valuable insights into the development of flexible printed circuit (FPC) material, which are of utmost importance in realizing low-loss and high-speed 5G communication technology.