Investigation of environmental reliability of optical polymer waveguides embedded on printed circuit boards

Purpose - To investigate the influences of environmental stresses on board-embedded polymeric waveguides. Design/methodology/approach - Optical multimode waveguides were embedded on printed circuit boards using commercial polymers. The optical - PCBs varying in board structure and in optical build-up materials were exposed to heat, moisture and ionic-contaminants in accelerated reliability tests. The influence of stress factors on the structural integrity and functional parameters, namely the refractive index and optical transmissivity, was investigated at the key communication wavelengths. Findings - Isothermal annealing reduced the refractive index to the greatest extent. The optical-PCB structure with an optical surface build-up layer was observed to be more vulnerable under temperature shock when compared with the optical-PCB with optical inner layer. The buffer layer beneath the optical build-up was found to improve the stability of the optical waveguides significantly. The results indicated of wavelength dependence to the aging factor with a failure mechanism. The factors affecting the performance and reliability of polymer-based optical waveguides on PCBs were discussed. Research limitations/implications - More experimental data and investigations of failure mechanisms are required to ultimately obtain sufficient reliability statistics for accurate life-time prediction models. Originality/value - Optical interconnects are seen as a promising solution to overcome performance limitations encountered with high-frequency electrical interconnections. As an emerging technology, only a limited amount of reliability data on optical/electrical packages is available. The paper investigates the influences of environmental stresses on board-embedded polymeric waveguides.