System integration for miniature node of wireless sensor network (WSN)

A type of 3D-SiP (System in Package) package for wireless sensor network (WSN) node was designed and developed based on an embedded FR-4 substrate using 3D technology (including, embedded way and stacked way) and SiP technology. The 3D-SiP package including sensor (sound or vibration) module, baseband ASIC chips, digital signal processor (DSP) chips, other chips and various passive components, was studied. FCOB (flip-chip on board), COB (chip on board), BGA technologies, wire bonding flip-chip bonding and surface mount (SMT) etc. interconnection technologies were combined together. Several kinds of solder materials with different melting points were used for initial and final vertical interconnections for the sake of compatibility of all levels interconnections by reflowing. High density WSN node with ASIC chip embedded in and sensor module stacked on high density multi-layer FR-4 substrate was designed and manufactured. The thermal management was conducted and the thermal related reliability of 3D-SiP were simulated and evaluated respectively.