Ultra high I/O density package:: Sea of Leads (SoL)

Sea of Leads (SoL) is a novel ultra high input/output (I/O) density package (> 10(4) x-y-z compliant leads per cm(2)) that provides high bandwidth and high current distribution capacity for a system-on-a-chip (SoC). A prototype SoL with 12,000 leads per cm(2) has been designed and fabricated using our compliant wafer level packaging (CWLP) processing approach. The I/O density of the package is maximized by designing various lead lengths as a function of the necessary in-plane mechanical compliance, which increases linearly from the center. In addition, the leads are oriented along the die's local directions of expansion providing a higher degree of compliance. Two different lead lengths (53 mum leads on a 80 x 80 mum square lattice and 106 mum leads on a 80 x 160 mum rectangular lattice) totaling 12,000 leads per cm(2) are distributed across a 1 cm(2) die. SoL promises the capability of meeting high current (> 350 A) and high I/O bandwidth requirements as far ahead as the 35 nm generation node (year 2014) SoC. In essence, SoL extends wafer level batch processing of multilevel interconnects networks to include chip I/O leads.