Design and characterization of fully Embedded Passive components on multilayer organic-based substrate for highly compact SOP applications

Embedded Passive device (EPD) technology is increasingly drawing attention because of its potentials in addressing system cost reduction by offering smaller size form factor with high level of integration in RF packaging. In a typical RF system block, many passive elements, capacitors in particular, are required for filtering and impedance matching therefore wide efforts has been given to integrate such passives in the package substrate not only because of their important functions in affecting the performance of RF circuits and subsystems but also they occupy significant area of a package substrate in their discrete forms. In this paper, various sets of embedded capacitor structures were designed and fabricated based on organic substrate packaging technology using a novel process. These capacitors are parallel plated structures embedded in a substrate with composite-type epoxy material having high Dk, low Df properties at microwave frequencies. In order to further validate their applicability in RF SOP applications, such capacitors where implemented in the design of a fully embedded BPF as test vehicle which is intended for Wimax FEM application. Physical design details along with characterization methods and measurement results are discussed. These embedded capacitors and BPF were designed and tuned using 3D EM simulation tools and compared against measurements from a well calibrated 2-port VNA. From the achieved data and results, it can be established that various fully embedded capacitance values with narrow tolerances are achieved thru this novel process in organic substrate fabrication. Designed BPFs have also been realized in a small form factor that exhibited an insertion loss of about -2 dB at the target in-band frequencies and between 15-30 dB attenuation at the out-band frequency ranges. These BPFs can be utilized as a commercial diplexer for Wimax dual-band applications.