New optical and electrical hybrid packaging techniques using optical waveguides for optoelectronic multichip modules

Abstract

An optoelectronic multichip module (OE-MCM) using fluorinated polyimide optical waveguides is proposed. This module can be produced with an optoelectrical substrate (OE-substrate), incorporating photodiode-to-waveguide coupling, and fiber-to-waveguide coupling. The OE-substrate is composed of fluorinated polyimide optical waveguides fabricated onto a copper-polyimide multilayer electrical substrate. Propagation loss of the optical waveguide is low at 0.4 dB/cm. There is no change in the optical characteristics of the waveguide after heat-treatment during the solder bonding process. The waveguide-to-photodiode coupling is achieved by deflecting the propagating light with a total internal reflection (TIR) mirror, and self-alignment of the photodiode is achieved using micro-solder bumps. The TIR mirror shows low reflection loss of less than 1.5 dB. The solder bumps can position the photodiode accurately within /spl plusmn/1 /spl mu/m. A fiber guiding groove is used for alignment-free coupling between inter-modules. The coupling loss between the fiber and the waveguide is estimated to be 3.2 db with the deviation of about 0.1 dB. These techniques make OE-MCM's attainable.