Transmission of data is a major driver in the electronics industry. Higher data volumes, high speed data transfer and short time signal transmission have to be realized to meet these requirements. To minimize losses, the Radio Frequency (RF) application and standard PCB requirements have to be realized on the same board. This additional technology puts additional demands on the PCB. To achieve these targets, the material, build up and design need to be adjusted to both requirements. Test procedures, focussed on particular RF properties have to be considered as well. This paper examines the development of mixed Microwave and Digital Multilayer printed circuit boards (PCB) for high density application. The major innovations include Radio Frequency (RF) functions, coupled with stacked copper filled Microvia and High Density Interconnection (HDI) technologies, made together into one multilayer construction. The aim of this study shows the development and validation of raw materials to meet dielectric, power and signal loss properties. From a manufacturing point of view, asymmetrical build up of raw materials with specific RF properties and other PCB raw materials will be investigated, to demonstrate the compatibility of mixed materials in a multilayer PCB's. This research was carried out by the company in cooperation with MIDIMU, a European Consortium Project.