Influence of environmental stresses on board-level integrated polymer optics

In this paper, the effects of environmental stresses on the properties of polymer optical waveguides were studied. Multimode step index waveguides were fabricated on printed wiring boards using commercial polymers. The stability of the optical properties of the guide systems was investigated in damp heat-high humidity, high temperature storage, thermal shock and in environmental flowing multigas tests. Aging at high temperature and temperature cycling reduced the refractive index to largest extent. The optical build-up (o-BU) structure in which the optical layer was fabricated on the board surface was observed to be vulnerable under temperature shock when compared with the structure where the optical layer was laminated inside the FR4/Cu boards. The buffer layer beneath the optical build-up was found to improve the stability of the optical waveguides significantly.