Precise integration of flexo-printed optical waveguides into printed circuit boards via opto-electrical layout registration

Due to increasing integration density, optical data transmission is the solution for interference-free data transmission and galvanic isolation at circuit board level. To establish this on the market, the process must be cost-effective and suitable for mass production. In addition, photonic integration should be integrable into the conventional circuit board manufacturing process. The rotative flexo printing process can be used to print planar optical waveguides additively onto rigid and flexible substrates. It offers the potential for high throughput and is also a cost-effective process due to local application of conventional printing varnishes. To integrate the optical waveguides into printed circuit boards (PCBs), they must be able to withstand the PCB pressing process at temperatures of 180°C. The substrates that can be used for this purpose are not suitable for use as optical waveguide cladding. Therefore, optical waveguides require a suitable cladding to enable optical transmission functionality. In this study, optical waveguides were manufactured using a new machine with optical alignment capabilities. By coordinating targets in the optical printing process and PCB manufacturing, it was possible to register optical waveguides in the PCB for the first time. This paves the way for the practical use of flexo printed waveguides in PCBs.