This Exploratory Report presents the results of the functional analysis of the 3D Touch sensor found inside the Apple iPhone 6S smartphone. The iPhone 6s was the first phone on the market to include a pressure sensor to complement the capacitive touchscreen. Although Apple had previously introduced a similar feature (branded Force Touch) in their first-generation Apple Watch, the 3D Touch sensing operation differs significantly from that of the Apple Watch. This report contains the following detailed information:

Selected teardown photographs, package photographs, package X-rays, die markings, and die photographs

Details regarding how the 3D Touch sensor is connected to the remainder of the iPhone

An examination of the bus traffic between the capacitive touchscreen controller and the 3D Touch sensor

An analysis of the correlation between sensor output and the location of touch events