Aspects of using low layer count PCBs for embedded systems with FPGA devices in BGA packages

This paper shows part of the investigations conducted regarding the use of 2-layer printed circuit boards for embedded systems based on devices (microcontrollers or field programmable gate arrays) in BGA (Ball Grid Array) packages. Usually, the technical literature [1] recommends for applications involving programmable devices in BGA packages the use of multi-layer boards (4, 6 or more layers), but these boards are expensive for applications like educational kits or simple controls that runs at relatively low clock frequencies, around 1MHz. The paper analyzes the aspects of PCB design, manufacturing costs and technical limitations (maximum available I/O pins, signal integrity) of 2-layer printed circuit boards for a simple embedded system based on an FPGA device in 256-pin BGA package. Suitable PCB design techniques analyzed and layout recommendations are presented.