High-Throughput Flexible Electrode Packaging for Brain-Computer Interface Chips

Brain-Computer Interface (BCI) technology enables direct interaction between the human brain and external devices through neural signal decoding. Implantable neural electrodes, characterized by their exceptional temporal and spatial resolution, represent a critical advancement in neural interface research. This study focuses on the integration of a high-throughput flexible electrode chip with an application-specific integrated circuit (ASIC). While wire bonding and flip-chip bonding were initially employed for integration, structural incompatibilities between the flexible electrode and the ASIC’s pad map layout hindered process compatibility. To resolve this, a three-dimensional trench structure was innovatively fabricated on the ASIC, enabling spatial reconfiguration of bonding pads along the X- and Z-axes. The trench fabrication process involved diamond dicing for precision micro-trench formation, dielectric layer deposition for insulation, redistribution layer (RDL) patterning for signal rerouting, and solder ball mounting for vertical interconnects. Subsequent integration by wire bonding and flip-chip processes achieved robust interconnection between the flexible electrode and ASIC chip. Post-assembly characterization demonstrated reliable electrical connectivity, validating the proposed methodology. This work provides a scalable solution for hybrid integration of heterogeneous neural interface components, advancing the development of next-generation BCI systems.