WPLGA: New package family for medium pin count with design flexibility

摘要

In this article we present a relatively new and innovative family of packages that is suitable for medium pin count needs and that locates itself between BGAs and “standard” QFN with single row of pads. It is characterized by the extreme design flexibility in term of I/Os size, location and shape, allowing a wide range of customization; only limited by PCB layout constraints. Nevertheless its structure looks like metal QFN, the pad-out is more similar to LGA array, being a multi-row design, with the possibility to have exposed partial/full ground and/or power rings. All this allows a relatively large footprint reduction compared with the same I/Os of a TQFP package, including a significant total package height reduction. Simplified assembly flow and easy handling leads to package total cost competitive respect to BGAs and TQFPs, allowing also testing on strip. Results from samples will be shown demonstrating good reliability characteristics, thermally in between QFNs and BGAs, and from electrical point of view good performances due to reduction of the overallsignal path length die-application board. Also solder joints show an improvement respect to standard QFNs. We will show the package structure and its design options, thermal and electrical modeling data and overall package performances and possible applications. The innovative nature of this new package along with its promising results data and cost structure is proving of great interest and this new package is not moving towards mass production.