Interfacing standard optical fibers with high index-contrast photonic waveguides remains a substantial challenge restricting the cost-efficiency and scalability of silicon photonic devices. To address this, we have proposed a mechanically compliant polymer interface, formed of a standard fiber connection and a flexible ribbon with lithographically defined polymer waveguides. Self-aligned mechanical assembly and optical mode evolution designs are employed for low cost and large spectral bandwidth. In this paper, we review our progress leading to the full demonstration of this concept with -1.8 dB peak transmission from a plugged-in standard fiber connector to Si wire waveguides. This with 0.7 dB roll-off on a 100 nm bandwidth and all polarization. We present a comprehensive analysis of loss sources and discuss intermediate results, self-alignment accuracy, and reliability.