Embedded passives technology for Bluetooth application in multi-layer printed wiring board (PWB)

This study was to investigate the use of a special high dielectric constant (Hi-DK) material for embedded passives in a Bluetooth system module. The stack structure of the module substrate was comprised of three kinds of material; Hi-DK, low loss-tangent and general organic material. Both experimental circuit and embedded passives can be implemented in this substrate for normal printed wiring board (PWB) lamination processing. The embedded capacitor electrode area can be reduced considerably by taking advantage of the Hi-DK material. After consideration of carefully simulated electrical characteristics, SMT matching network inductors could be replaced with a solenoid or spiral embedded layout structure. With embedded passives built into a Bluetooth substrate, this design can shrink the area by at least 14%, 38%. Area reduction was also realized by a double-side package layout design.