Characterization of Chip-to-Package Interconnects for Glass Panel Embedding (GPE) for Sub-THz Wireless Communications

This work presents characterization of microvia interconnects in D-band frequencies for use as chip-to-package interconnects in Glass Panel Embedded (GPE) packages. Antenna-in-Package based on wafer-level fanout technology have demonstrated superior performance along its small form factor by eliminating wire-bond, assembly, underfill and package substrates. However, epoxy mold compounds, which limit the use of fanout packages at sub-Thz frequencies, do not support the electrical performance, thermal and thermo-mechanical needs of such applications. Embedding chips in glass panels, on the other hand, leverages all benefits of glass substrates and low-loss polymer buildup dielectrics while also mitigating the effects of wire-bond and microbumps for chip-to-package interconnects. In this paper, the design, fabrication, and characterization of these all-copper microvia-like chip-to-package interconnects is presented. These interconnects achieve an average chip-to-package loss of 0.146 dB in D-band and 0.177 dB maximum loss at 170 GHz which is lower than current flip-chip approaches, and our objective is to incorporate such interconnects in the proposed GPE package.