Disclosed are pressure sensors including a die and an application-specific integrated circuit (ASIC) mounted on a top surface of a substrate. The pressure sensor can define an inner volume and a bottom opening configured to abut the substrate. The die and ASIC are mounted on the top surface of the substrate within the inner volume. The substrate defines a first aperture therethrough and the die defines a second aperture therethrough in a direction along an axis perpendicular to the substrate, the first aperture and the second aperture being aligned. Metallic barrier(s) disposed on a bottom surface of the substrate, circumferentially about the first aperture, can be at least partially coated with solder mask to reduce or prevent flow of unwanted materials past the metallic barriers and through the first aperture. The substrate can include electrical connection pads on the bottom surface configured to be in communication with a daughter board.