Fan Out Wafer Level Packaging – Towards a European Manufacturing Supply Chain

Fan Out Wafer Level Packaging Towards a European Manufacturing SupplyChain Fan-Out Wafer Level Packaging (FOWLP) has emerged as a critical technology for advanced, low-cost miniaturized packages in the last decade. Now it is a preferred solution for advanced electronic applications, which require small footprints, thin packages and enhanced RF- and thermal performance, featuring multi-die and multi-layer RDL configurations. Despite its proven potential, FOWLP remains largely inaccessible for smaller volumes in the European market, as well known OSATs target large volumes (>several mio. packages p.a.). Herein, we present FOWLP manufacturing based on the ‘Mold First’ variant. A single-die package with one redistribution layer is manufactured, using a RF-Die, operating in the lower two-digit GHz range. Challenges like warpage and thermomechanical shifts during the molding process ('Die Shift') are addressed. This shift needs to be compensated in order to enable adequate RF-performance, especially towards higher frequencies, which typically feature smaller RF-pads and stricter requirements of via positioning on die pads. After thin film Cu-redistribution layer (RDL) manufacturing and backgrinding, solder-ball attach and package singulation complete package manufacturing. Results regarding <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$R F$</tex>-performance, in terms of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$S$</tex> parameters, are promising and on par with results from a comparable package. This highlights that - for ‘core Fan-Out’ packages - realizing a European manufacturing chain is within reach in order to lower entry barriers into FOWLP for smaller and medium volumes.