Electrical and thermal modelling of QFN packages

The quad flat no lead or QFN package, a near CSP leadframe, is a promising choice for portable wireless applications such as Bluetooth/sup TM/ and home RF. Attractive attributes of this advanced package include miniaturised footprint, good electrical performance and excellent thermal characteristics. The paper describes electrical and thermal modelling techniques as part of an integrated performance validation methodology for a typical 32 I/O (0.5 mm pitch) QFN package structure. It is shown how electromagnetic simulations can be used effectively to explore the design space during the QFN development cycle. Results from parametric studies on the impact of die shrink and bond wire profile are presented. A two-layer 48 I/O fine pitch (0.5 mm pitch) BGA package is also included to provide a comparison of electrical and thermal performance.