Polymer optical interconnects for PCB

Fraunhofer IZM has developed a packaging concept, which is based on a hybrid carrier, containing both electrical and optical interconnects: the Electrical Optical Circuit Board (EOCB). The key element is an additional optical layer with multimode waveguide structures. This layer is handled by standard PCB technology. As a result, the waveguides are completely incorporated into the circuit board. We used the hot embossing process for the first test of effective foil-structuring. After filling the core of the waveguides and sealing them with an over-cladding, the optical layer is given into the PCB process. Furthermore, waveguide structuring by photolithographic patterning is also a promising way to incorporate waveguide structures into the circuit board and is currently under test. The choice of appropriate polymer materials is a key problem when applying these techniques. They have to be compatible with the structuring and laminating processes and display excellent optical properties. We focus on recent results showing the optical characteristics of laminated polymer waveguides made by hot embossing and of waveguides made by photolithography.