System Design and Mechanics
For the realization of the wafer scale integration many components are necessary.
To test the interplay of these components a prototype system has been developed. The post processing is not only used for the interconnection between the reticles, but also for contact areas for the connection of the wafer to its peripheral electronics. The peripheral electronics are situated on a 9U board. The post processed contact areas are used as contact pads for flexible elastomeric connectors with a small pitch instead of using high numbers of bonding wires all over the wafer with the problems of handling and reliability. Each reticle will be provided by post processing with two rows of contacts in the described prototype system. On each row an elastomeric connector will beplaced to establish the connection to the board.
A 3D CAD program (Solid Works) was used to create a mechanical model of the system. This helps to identify problems in the early phase of development and finally the data can be used directly to create the needed parts.
The following figure shows an exploding view of the prototype system with all the necessary components.
The composition of the prototype system is the following (from bottom to up):
- Wafer bracket for mechanical fixation and cooling of the wafer
- Sealing rings to keep wafer under nitrogen atmosphere
- Test wafer with post processing
- Elastomeric connectors
- Fixation device for the elastomeric connectors
- Main board with plugged FPGA daughter boards
- Top cover