Fabrication Process for PCBMEMS Capacitive Pressure Sensors Using the Cu Layer to Define the Gap

In this paper, a fabrication process for capacitive pressure sensor is reported. The process is based on using the printed circuit board (PCB) microelectromechanical systems techniques. The gap between the electrodes is defined as the thickness of the copper layer of the commercial PCBs. The main advantages of the proposed procedure is easy and inexpensive fabrication process, the high integrability with auxiliary electronics in a PCB, and its capability to be tailored to a specific application by modifying its geometry. A prototype is fabricated using the proposed method. This prototype is composed of a top PCB, which includes an SU-8 membrane with gold as movable electrode, and a bottom PCB to perform the gap and a gold fixed electrode. The fabricated capacitive pressure sensor has been characterized experimentally providing a sensitivity of 20.13 fF/mbar, and a calibration procedure is defined to overcome the inherent deviations of the manufacturing process.