Broadband, quad flat no-lead (QFN) package developed using standard overmold leadframe technology

Abstract

We present design and development of a low-cost, quad flat no-lead (QFN) package that operates over DC to 40 GHz frequencies and is fully compatible with existing leadframe processes. Further, we discuss a novel technique to characterize the package interconnect that first involves removal of plastic from the package. Once the die-paddle is exposed, a probe-ready alumina substrate adapter is inserted and wire bound to allow for GSG probing. This places the internal reference plane where the package would encounter the chip. Plastic is then selectively back-filled in order to maintain dielectric effects in measurement. Insertion loss through a single transition is measured to be less than 0.4 dB across the entire band up through 40 GHz. Return losses are measured to be better than 18 dB over the same band. A bare die broadband voltage-variable attenuator (VVA) is packaged for demonstration. The packaged VVA demonstrates excellent matching with less than 1.7 dB added attenuation due to packaging effects and excellent broadband match over DC-40 GHz. Dynamic range for the VVA QFN is maintained to be greater than 27 dB at 40 GHz.