Packaging methods for integrated thermal gas flow sensors

Two different packaging solutions for integrated thermal gas flow sensors are proposed. The sensors are based on the differential temperature configuration and are made up of two heaters placed between an upstream and a downstream temperature probe. The chip was designed using a commercial CMOS process and thermal insulation of heaters and temperature probes from the substrate was obtained by means of a post-processing technique. The two packaging solutions, corresponding to placing the whole chip inside the flow channel or adapting the pipe to a part of the chip itself, have been compared in terms of device sensitivity increase.