High frequency IC to IC signaling on rapidly prototyped flip chip MCM-D substrate

We previously reported a demonstration of rapid MCM prototyping technology. This first generation supported wire bond assembly. Now, we report on extending the technology to support flip-chip attachment. Maskless laser-based processes for rerouting from the MCM wiring grid to flip-chip landpads were developed. We functionally demonstrated this new technology by flip-chip attaching custom transceiver ICs to a rapidly-prototyped MCM, and operating it at the maximum chip-limited inter-chip signaling rate of 242 Mbits/s. MCC, with Hewlett-Packard's support, designed and fabricated a special IC for signal integrity evaluation in high-speed VLSI ICs and interconnect systems. Four of these ICs were flip-chip attached to a rapidly prototyped MCM, forming two transmit-receive pairs. A test fixture provided clocking and JTAG controls for programming tests and output of operating performance. Chip-to-chip signaling at 242 Mbits/s was reliably obtained for single channel operation, where reliable is defined as no errors during 1 s of operation. For 128 channels operating simultaneously, the maximum reliable data-rate was 220 Mbits/s. The results of SPICE simulations using a model of the IC driver, receiver, and MCM interconnect agreed extremely well with measurements made using a high-speed digital oscilloscope. In this implementation, the maximum frequency was set by IC capacitive parasitics, and not by limits in the MCM interconnect. We have shown that high frequency performance can be obtained in a rapidly-prototyped flip-chip MCM. Such MCMs are suitable for applications where quick turnaround is required.