Tony Gray from Dawar Technologies gave a wonderful presentation (5/24/2019) on how capacitive touch screens work. Click below to view his 45 minute presentation.
Tony is the author of a technical book called Projected Capacitive Touch: A Practical Guide for Engineers.
In summary, PCAP means Projected CAPacitive. Projective because it projects an electronics field. Capacitive because the field is created by forming a capacitor. The field extends into space and reacts when something (like your finger) comes into that field. There is a matrix or rows and columns of these capacitors and associated fields to detect specific location and movement of the touch. See the video for a very good introduction into the technology that makes phones and other smart devices work.
For assistance with anything regarding design or manufacturing services contact:
Gary Tanel at www.ElectronicsAlliance.net.