The development of printed circuit boards (PCB) with integrated layers for optical data transfer was pushed during the last few years. Solutions with optical fibers or planar waveguides fabricated from plastics or glass will soon be available on the market. Nevertheless the low loss coupling of functional optical components as connectors, transmitters and receivers to these new generations of PCBs still is open.
The packaging of otical transceivers or connectors actually is based mainly on single device solutions or active coupling concepts. On the other side the connectors of external optical data lines or of daughter cards to the main boards and the coupling of transmitter and receiver modules to optical PCBs do need linear array concepts. And the coupling efficiency should not decrease during reflow process.
Actual concepts using mulit-mode connectors or a direct waveguide coupling of receivers suffer under high optical losses. However the use of micro-optical functional elements allows the realization of coupling concepts with teh lowest losses possible. The total losses for optical lines from the transmitter to the waveguide and back to the receiver can be reduced below 4 dB. For cost reduction even symmetric optical set-up can be used. The transmission rate can be as high as 40 Gb/s. With this concept error tolerant systems for the optical interconnection are possible.
We report about the modeling, the design and the characterization of micro-optical interconnect modules for high efficient contacts to the optical layer in PCBs. For the assembly of the modules we use the new concept of a desk-top factory with miniaturized tools for handling, assembly, and inspection. This concept increases the flexibility and reduces the manufacturing costs.
Hybrid micro-integration of semiconductor devices, micro-optics, fiber-optics and micro-electronics is of growing interest for automotive, computer, telecommunication, business equipment and consumer applications. A large variety of the functions and components within these photonic devices and missing packaging standards make most of them not mass producible and therefore expensive. In addition most of them need reproducible and accurate alignment in the micron or even sub-micron range. Automated processes are necessary to get the accuracy and the reproducibility for high
Expensive production equipment is available mostly especially adapted to the specific product. The machines do need heavy granite bases and a temperature controlled fabrication environment to realize the requirements mentioned above. They appear as dinosaurs compared to the tiny products fabricated.
Cost reduction can be achieved by using only partly automated production sequences in a modular desk top factory. Consequently we have miniaturized the robots, the factory framework and the tools for handling, dispensing and inspection. For the first time an exchangeable tool assortment with a standardized mechanical, electrical and fluidic interface between the robot and the end-effector is available. The modularity allows a flexible and re-useable set-up of the production equipment. The fabrication process uses a new technology with a closed loop control of the robot directly
correlated to the assembly process to get sub-micron accuracy. The control signals are determined from the deviation of a component relative to the assembly position with miniaturized microscopes integrated to the tools.
Solutions with multiple fiber handling and automatic process control for the joining of fibers to micro-optics and microoptics to micro-benches, the assembly of silicon fiber-optical switches and of two-dimensional fiber arrays will be shown. Also a technology for the fabrication of fiber-optic collimator arrays with back reflection losses well above 70 dB will be presented.