Novel substrate with combined embedded capacitance and resistance for better electrical performance and higher integration

Many articles have been published on the benefit of thin substrates for use as embedded capacitor layers as well as thin film resistive material for embedded resistors. Until now the utilization of both technologies within a printed circuit design required the use of separate cores within the PCB. This adds additional thickness to the PCB as well as cost. A new substrate has been developed to address these issues. Embedded technologies improve the electrical performance of high speed digital circuits as well as enabling the removal of SMT discrete components (the ratio of passives to active components is increasing while the available board surface area is decreasing). By combining capacitance and resistance on the same core, with the resistor foil being supplied on one or both sides of the capacitor dielectric, these benefits can be realized without increasing the overall number of layers or the substrate thickness. Also, some unique R-C circuit designs can be formed by utilizing this substrate. The process and design guidelines for using this substrate as well as some possible applications are discussed. Also, results from high frequency testing of PCB test vehicles are discussed. Future product developments will be shared. It is demonstrated that this new substrate has excellent electrical properties while being able to be readily manufactured using typical inner-layer processing.