IC Package Dual-Side Interconnects for High I/O Density

The patent utilizes both the top and bottom surfaces of the package substrate for making interconnects to the PCB. Specifically, a first set of interconnects are made through vias from the top surface, while a second set of interconnects are made through plated-through-holes from the bottom surface. This two-sided approach effectively doubles the available connection areas without increasing the substrate footprint, thereby resolving the contradiction between achieving high I/O density and maintaining compact substrate size.

The package substrate serves multiple functions simultaneously: it provides mechanical support for the IC die, establishes electrical connections through both top and bottom surfaces, and enables high I/O density without requiring miniaturized bond pads. By utilizing both surfaces of the substrate for interconnects, the design achieves high connection density while maintaining standard pad sizes and spacing, thereby avoiding the increased manufacturing costs associated with miniaturization.

The patent transitions from conventional single-sided interconnect packages to a two-sided interconnect architecture. The first set of interconnects are made from the top surface through vias, while the second set are made from the bottom surface through plated-through-holes. This dimensional expansion to utilize both surfaces of the substrate effectively doubles the I/O connection capacity while maintaining relatively simple package structure and fabrication processes.