Deformable Interconnects with Embedded Devices in Flexible Fan-Out Packages

Abstract

A new class of interconnects that exhibit resilience to mechanical deformation are demonstrated with flexible fan-out or embedded-die packages. Active device embedding in flexible substrates is accomplished with direct printed interconnects onto die pads. Such a planar fan-out interconnect technology with a low-cost manufacturable process-flow results in the lowest electrical parasitics compared to flipchip with adhesives or printed-ramp interconnections with surface-assembled devices. The interconnects are made with conductive flexible silver-elastomer composites to sustain elastic deformation. The process is also modified to realize flexible backside-assembled fan-out interconnections where the backside of the die is accessible.

Miniaturized Fully-Passive Wireless Neural Recording with Heterogeneous Integration in Thin Packages

“…Additionally, thinner die is connected with copper traces and silver-elastomer interconnects, which barely adds any height to the package. More importantly, advanced packaging with embedding dies and thin-film passive components in flex will further reduce the size of neurosensor [14]. Such trends have been recently realized to further reduce the package form-factor.…”