Multichip module with free-space optical interconnects and VCSEL-solder-joints

The design of a multichip module with planar optical interconnects is presented. Electrical (local) interconnects for intra-chip communication and optical interconnects for chip-to-chip communication are implemented onto the same substrate of a planar-integrated free-space optical system. We suggest to integrate the optical emitter/detectors (VCSEL diodes) into solder balls; onto these solder balls IC carrying silicon chips can be flip-chip bonded like on a common ball grid array. With respect to the thermal load thermally conductive vias are incorporated into the package, too. We show that typical packaging errors can be tolerated by the optical system, which is designed for space variant interconnects and enables thin film replication techniques of temperature sensitive materials.