The sensor measures the ambient humidity and temperature in 15-minute intervals. Afterwards, it forwards the information to a cloud where it’s stored. The wireless humidity sensors are produced by Disruptive Technologies and the circuit boards embedded in them by Zollner Elektronik AG.

Membranes in industrial applications work in ways comparable to those known from breathable functional clothing in the outdoor sector. They’re air-permeable toward the outside while protecting the interior against water ingress. This applies to humidity sensors as well. The circuit board in the enclosure has to be protected against water ingress and to ensure such protection, the board must be positioned precisely above the hole in the housing.

Commissioned by Zollner Elektronik AG, Schreiner ProTech developed an innovative solution for this purpose: a steam-permeable adhesive pad located inside the sensor. Embedded in the adhesive pad is a membrane. The integrated, non-adhesive area enables fully automatic SMD (surface-mounted device) processing. In addition, the double-sided adhesive die-cut part creates the necessary connection between the sensor housing and the board.

“The adhesive pad provides optimum control because the embedded membrane enables moisture wicking toward the sensor while preventing water ingress. For this purpose, there’s a hole on both sides of the pad that ensures the necessary breathability,” explains Michael Drollmann, Business Development Manager ETech bei Schreiner ProTech.