A pressure sensor that can be implemented simply by soldering on a membrane together with the electronics on a printed circuit board.

We manufacture pressure sensors for various application cost-efficiently, even for small quantities. Through the use of stainless steel membranes we also implement media-resistant pressure sensors. Pressure is measured capacitively and can be read out with a number of commercially available electronics solutions. Different housing solutions are used depending on the requirement – from simple aluminum or stainless steel housings with gaskets, to housings with pressure connections of highly resistant duromers.

Pressure sensors monitor leaks on compressed air equipment and are used in the chemicals industry and food industry, or they are used as fill level sensors in the application area of household appliances. Our pressure sensor concept is based on a printed circuit board on which a  pressure sensor membrane has been soldered. Since special processes are not necessary for the design and connection technology; the sensor design manages with SMT placement technologies, it is possible to manufacture sensors for customer-specific applications in low quantities at low costs. But the sensor can exploit its advantages relative to MEMS pressure sensors – even in the price-sensitive mass market – in applications where size plays a subordinate role.

A first electrode is located on the printed circuit board underneath the pressure sensor membrane. The soldered-on membrane itself forms the second electrode of a pressure-dependent capacitor. When charged with pressure, the membrane is deflected parallel to the surface of the printed circuit board and thus the relative distance of the two electrodes is minimized. Thus the capacitance of the capacitor increases, and this can be measured via analysis electronics. In the simplest case this is a Capacitance-to-Digital-Converter (CDC), which directly supplies digital values or a modern micro-controller that measures capacities via the function.

The membrane is configured for the respective pressure range through FEM-supported simulations (FEM: Finite-Element-Method Depending on the area of implementation, the membranes can consist of different materials, such as copper-beryllium, nickel-beryllium or stainless steel, and if necessary they can also be coated. Consequently, media-resistant pressure sensors for aggressive media can be implemented through the use of stainless steel membranes.

The superstructures of the pressure sensors in PCB and MID technology, populated on both sides, measure 13 mm in diameter and carry a membrane with a diameter of 9.2 mm. In the simplest case the capacitance of the sensor cell against a ceramic fixed capacitor is measured. In this manner a repeatability of 0.5 percent full-scale, in a range from 0 to 10 bar could be achieved for initial superstructures.
To compensate for environmental influences, such as temperature or humidity, a second membrane that is not charged with pressure can be used.

Likewise, a differential pressure sensor can be set up with a second membrane that is mounted on the underside of the printed circuit board and opposite to the first membrane.

Pressure sensors