Electrical characterization of embedded polymer/ceramic capacitors from 500 MHz to 12 GHz

The potential application of polymer/ceramic capacitors at a higher frequency range is explored through a detailed characterization of several form factors of embedded capacitors. S-parameters of embedded decoupling capacitors using two different types of embedded capacitance material were measured from 500 MHz to 12 GHz. The effect of different geometries, electrode sizes, and materials are demonstrated. Results from through-line traces above the embedded capacitors demonstrate the ability for signal lines to be routed above the capacitors with minimal effects on signal quality, and therefore, considerable savings in board real estate can be achieved by routing metal traces over the embedded capacitive layer. A circuit model was developed based on the measurements to determine the relevant parasitic elements and their effects on the performance of the capacitors. Reliability tests including reflow, thermal cycle, and humidity were performed with each test showing similar effects on capacitor performance. This is the first report to detail high frequency characterization of polymer/ceramic capacitors integrated onto a multilayer PCB product up to 12 GHz.