Low Dk/Df Thermosetting Siloxane Hybrid Material for Microwave Communication Printed Circuit Board

Microwave telecommunication, adopting 1 GHz - 100 GHz frequency range for wireless communication is an irreplaceable to realize the hyper-connected society which can be realized by diverse electronic devices such as fifth generation (5G) cellular, internet of things (IoTs), virtual reality (VR), augmented reality (AR), and RADAR (Radio Detection And Ranging) system for autonomous automobile. To realize the advanced technologies, a dielectric constant (Dk) and a dissipation factor (Df) of dielectrics in PCB should be around or lower than 3.0 and 0.002 each at microwave frequency region. Many materials have been proposed as low Dk/Df dielectrics for microwave PCB such as liquid crystal polymer (LCP), modified polyimide (MPI), modified polyphenylene ether (MPPE), and polytetrafluoroethylene (PTFE), but significant issues are remained to utilized in real device. Here, we present thermosetting siloxane hybrid material with low Dk/Df in microwave frequency ranges (2.86/0.002, 10 GHz) with high dielectric stability in diverse humid condition. To achieve more improved properties, the siloxane hybrid material was laminated with glass cloth (quartz glass, NE glass) to form siloxane prepreg. Especially for the quartz glass siloxane prepreg, it shows Dk/Df of 3.2/0.0016 at 10 GHz which is highly proper for the dielectrics in microwave PCB. Dk/Df of the siloxane prepreg were also measured in wide range of frequency (1 - 50 GHz). Moreover, thermal, and mechanical properties of the siloxane prepreg were measured. Finally, the siloxane prepreg based double sides copper clad laminates (CCLs) was successfully demonstrated by laminating Cu foil.