The sensor assembly comprises a substrate (1), such as a flexible printed circuit board, and a sensor chip (2) flip-chip mounted to the substrate (1), with a first side (3) of the sensor chip (2) facing the substrate (1). A sensing area (4) and contact pads (5) are integrated on the first side (3) of the sensor chip (2) and located in a chamber (17) between the substrate (1) and the sensor chip (2). Chamber (17) is bordered along at least two sides by a dam (16). Underfill (18) and/or solder flux is arranged between the sensor chip (2) and the substrate (1), and the dam (16) prevents the underfill from entering the chamber (17). An opening (19) extends from the chamber to the environment and is located between the substrate (1) and the sensor chip (2) or extends through the sensor chip (2).