Recent Progress in Modification of Polyphenylene Oxide for Application in High-Frequency Communication

With the rapid development of highly integrated electronic devices and high-frequency microwave communication technology, the parasitic resistance-capacitance (RC) delay and propagation loss severely restrict the development of a high-frequency communication system. Benefiting from its low dielectric constants (D_k) and low dielectric loss factor (D_f), polyphenylene oxide (PPO) has attracted widespread attention for its application in the dielectric layers of integrated circuits. However, PPO suffers from a very high melting viscosity, a larger coefficient of thermal expansion than copper wire and poor solvent resistance. Recently, many efforts have focused on the modification of PPO by various means for communication applications. However, review articles focusing on PPO are unexpectedly limited. In this article, the research progress concerning PPO materials in view of the modification of PPO has been summarized. The following aspects are covered: polymerization and design of special chemical structure, low molecular weight PPO and blending with thermosetting resin, hyperbranched PPO, thermosetting PPO and incorporating with fillers. In addition, the advantages and disadvantages of various types of modification methods and their applications are compared, and the possible future development directions are also proposed. It is believed that this review will arouse the interest of the electronics industry because of the detailed summary of the cutting-edge modification technology for PPO.