A printed circuit board (PCB) assembly provides a two layer capacitive
trackpad sensor in which an EMI ground grid is interposed among the
sensor's capacitive elements on each of its layers. The EMI grid on each
of the two layers is electrically coupled via, typically, vias. The
described arrangement of sensor elements (capacitor plates) and EMI
ground grid traces may be incorporated into a PCB having additional
layers (e.g., a four, six or eight layer PCB). If used in this manner,
additional vias are provided on the PCB which permit electrical coupling
between these "additional layers" and which are electrically isolated
from, and shielded by, the EMI ground grid.