Fine Pitch(40μm) Integration Platform for Flexible Hybrid Electronics using Fan-Out Wafer-level Packaging

A flexible fan-out wafer-level packaging (FOWLP) process for heterogeneous integration of high performance dies in a flexible and biocompatible elastomeric package (FlexTrate TM ) was used to assemble 625 dies with co-planarity and tilt <1µm, average die-shift of 3.28 µm with σ < 2.23 µm. Fine pitch interconnects (40μm pitch) were defined using a novel corrugated topography to mitigate the buckling phenomenon of metal films deposited on elastomeric substrates. Corrugated interconnects were then used to interconnect 200 dies, and then tested for cyclic mechanical bending reliability and have shown less than 7% change in resistance after bending down to 1 mm radius for 1,000 cycles.