High Density Interconnections
Multichip assemblies will be made by bonding ~five readout chips (the number of chips in a module will depend on the final readout chip size) to a single sensor. Each multichip assembly will have a multilayer kapton "high density interconnect" (HDI) mounted on it. The HDI will provide connections to bias the sensor, control the readout chips, and receive output data.
One edge of each readout chip will have wire-bond pads for connection to the HDI. We have demonstrated this capability with FPIX1 chips and a prototype five-chip HDI made by Fujitsu. Electrical tests of the five-chip assemblies have demonstrated that the prototype five-chip module performs at least as well as our previous single chip assemblies.
In our baseline design, the HDI will carry signals between the FPIX2's and the control and readout circuitry located at one end of the HDI. This circuitry will include a radiation hard data serializer, a VCSEL optical driver, a PIN diode optical receiver, and a control, monitoring, and timing ASIC. We are also pursuing the possibility that the FPIX2 chips can drive data directly (using high speed LVDS over copper) to commercial FPGA's located far enough from the beamline so that they need not to be radation hard. In this scenario, the control and monitoring functions would also be performed by commercial devices located outside the high radiation area.
|5-chip module assembled on a PCB
with the laminated flex-cable.
|Picture showing the 5-chip module |