The design of miniature 3D RF module

High-density packaging has become an important driver for new portable electronics. Miniature discrete components, flip-chip bonding of ICs and thin multilayer substrates are essentials for a small product. Further size reduction can be achieved with the integration of various passives, and modern covers with metal plated wiring can act as a substrate for the device. A 3D system-in-package (SiP) combines different chips and techniques into a single package without compromising individual semiconductor technologies. The driving force is the ability to construct complex, yet portable devices cost effectively and with high yield. A miniature 3D SiP short-range RF module operating in the unlicensed 2.4 GHz band was designed and manufactured. This paper introduces the module and discusses the steps required in designing, testing, and assembling of such complicated systems. Electrical design must meet the criteria set by system functionality, thermal behavior, testing environment, and manufacturing facilities. This work continues the research of the stacked 3D packaging technique developed in the Institute of Electronics at Tampere University of Technology. It utilizes thin high-density interconnect (HDI) printed wire board (PWB) interposers and flip-chip bonding of thinned chips. Interposers are stacked and bonded using solder plated polymer spheres.