Laminate Based Fan-Out Embedded Die Packaging Using Polyimide Multilayer Wiring Boards
Authors: Kazuhisa Itoi, Masahiro Okamoto, Yoshinori Sano, Nobuki Ueta, Satoshi Okude, and Osamu Nakao, Theodore (Ted) G. Tessier, Senthil Sivaswamy, and Gene Stout Company: Fujikura Ltd. and FlipChip International, LLC Date Published: 10/3/2011
IWLPC (Wafer-Level Packaging)
Abstract: A novel flex board based fan-out embedded die and system in package technology has been developed. The features of this package include a flex based multilayer substrate utilizing polyimide film to reduce its total thickness, thin embedded die with redistributed layers for pitch conversion by wafer level chip scale packaging processing and a cost-effective co-lamination process with conductive paste filled vias for z-axis electrical interlayer connections. The fabricated package is composed of 4 polyimide flex layers and 1 embedded die having a 100 I/O, 4 mm x 4 mm daisy chain device. The body profile without bump and footprint includes a 220 ?m package thickness and 5.25 x 5.25 mm body size, respectively. The resultant multilayer flex package showed high reliability. Thermal performance of the package was simulated with and without thermal vias on the backside of the embedded die for both face up and face down configurations of the die. The simulated results showed that the thermal via on the backside of the embedded die reduced thermal resistance parameters, ?ja and ?jc. The face down embedded die with thermal via was particularly effective in reducing ?jc to 5.9 oC/W, compared to that without thermal via was 20.4 oC/W. This technology provides ultra-thin Fan-Out embedded packages with cost-effective panel sized fabrication processing.