Optical packaging is one of the key challenges of silicon nanophotonics. Most of the existing optical packaging techniques, however, have scalability limitations in chip size, channel count of manufacturing cost. As the solution, we demonstrated a new method of low-cost, mechanically compliant polymer interface between standard single mode fibers and nanophotonic waveguides. This method gives better mechanical reliability and better optical performance than existing methods. To achieve the high precision assembly to meet with the single mode optics alignment accuracy, we used the self-alignment features to bridge the gap between the accuracy required by single-mode optics (1-2 um) and the capability of high-throughput microelectronic assembly equipment (∼10 um). Although the self-alignment method was effective for lateral positioning, a precise thickness control of the polymer layer was necessary to achieve the positioning in the height direction. Since the tight thickness control of the polymer waveguide is sometimes difficult to realize, we have improved the precision alignment method without requiring tight thickness control of the polymer film. The new method has been confirmed in the passive assembly of polymer waveguide ribbon with the connector ferrule designed for this method.