Scaling Quad-flat no-leads package performance to E-band frequencies

mm-Wave applications such as 60GHz WiGig, 77GHz Car Radar and 71-86GHz point-to-point communications have assumed center stage in recent years. While die technologies and circuit design capabilities have progressed significantly, little progress has been achieved in respective packaging solutions. This paper describes a low-cost plastic MicroCoax enabled Quad-flat no-leads (QFN) based package capable of addressing increasing frequency needs. Presented package has excellent isolation between input-output signals, bias pins and controls as well as low insertion and return loss, which increases package bandwidth. The superior performance achieved with this package effectively maintains bare die performance at mm-wave frequencies. Furthermore, it simplifies mm-Wave chip design and integration with the printed circuit board (PCB), eliminating package-PCB 3D electro-magnetic interactions and thermal dissipation complications. The package leverages controlled impedance and well-isolated MicroCoax transmission lines, replacing traditional QFN wire bonds. QFN transitions to MicroCoax transmission lines are optimized for low mm-Wave discontinuities. Package performance results up to 65 GHz will be presented and scaling steps to enhance package frequency to 90GHz and beyond will be discussed. Testing QFN packages at mm-Wave frequencies poses a challenge and related test strategies will be reviewed. Since this package structure is broadband, it allows a variety of mm-Wave die and high speed analog chipsets to be assembled using the same process sequence and package configuration.