NIEDERHALL, GERMANY -- Würth Elektronik has introduced a circuit board that includes an integrated cantilever sensor. The fabrication process includes embedding screen-printed, polymer hybrid, passive components on the PCB innerlayers.

The cantilevers provide pure force measurement. By means of resistive strain gauges printed on the PCB and integrated sensor and electronics on board, the integrated cantilever provides improved robustness against environmental conditions. This robustness makes the integrated sensor design suitable for applications that are subject to special demands in terms of temperature, humidity and environmental conditions.
     
These cantilevers can be integrated into any PCB type including; double-sided, multilayer, HDI or flex-rigid and are commonly used as short stroke sensors and force indicating devices.
 
According to Würth, the level of integration that has been achieved is the result of an in-house developed conductive polymer with targeted electrical characteristics.

Frank Dietrich, head of the product division FLATcomp systems at Würth Elektronik and developer of the specific “smart conductive” polymer paste, points out, “The customer does not get the paste in the actual sense, but the cured thick film; therefore, we use the correct term PTF (Polymer Thick Film). We are tending more and more towards this variation of thick film due to the wide range of resistance it offers; in the future, we will have many passive components screen printed on the PCB.”
 
For polymer strain gauges, the thick coating creates an exceptionally stress-sensitive resistor, achieving output signals 50 times higher than a conventional strain gauge’s signal, requiring only a low level of amplification.
 
According to Würth, designers will need less time for development and with the sensor positioned close to the electronic evaluation unit, the PCB will be capable of taking over several functions.
 
The integration of sensor functions into printed circuit boards has passed the first practical tests. Field application tests and approvals for serial production of customer-specific solutions has already been carried out.