Industry compatible embossing process for the fabrication of waveguide-embedded optical printed circuit boards

We demonstrate a cost-effective embossing process for the fabrication of waveguide-embedded optical printed circuit boards (OPCBs). The process involves the application of a polydimethylsiloxane mold for the production of polymer waveguides on a copper-clad FR4 substrate followed by the conventional lamination process. The embossing process is carefully tailored for the commercial polymer materials that are developed specifically to withstand the high temperature and high pressure environment during lamination. With this process, we are able to produce high-quality waveguide-embedded OPCBs with good repeatability. Our typical OPCB samples, each of which consists of 12 130-mm long fully embedded channel waveguides with a core size of approximately 50 × 50 μm and a pitch of 250 μm, show an average optical loss in the range 0.16-0.22 dB/cm at the wavelength 850 nm. The OPCBs survive the reflow process at 245 °C with a small change in the optical loss. The embossing process can be readily integrated with the existing PCB manufacturing process and thus offers a practical solution to mass production of OPCBs.