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RTD's with metallized backside

In definition, response time refers to the interval in time a system needs to react to a given input. Decreasing response time while maintaining a high quality and accuracy is an issue which many suppliers are facing on a daily basis.

Temperature

In definition, response time refers to the interval in time a system needs to react to a given input. Decreasing response time while maintaining a high quality and accuracy is an issue which many suppliers are facing on a daily basis.

Temperature sensors are mostly used in assembly constructions in order to protect the sensor element from process media or an aggressive atmosphere. Implementing sensors in end applications, sensor elements are often assembled into housings surrounded by epoxies, polyurethane or other polymer-based materials.

In many cases, the sensor is placed in metal tubes surrounded by a thermal heat conducting paste in order to improve the response time characteristics. However, the thermal heat transfer of thermal conductive pastes is very limited due to their polymer based nature.

To meet the ever increasing demands in faster response time and high accuracy, Innovative Sensor Technology IST AG developed a solution based on a standard RTD element. The element has been applied with a metallized backside, which allows the element to be soldered onto a metallic surface and thereby to increase the thermal coupling. This results in a faster response time while maintaining a high accuracy.

Spoken in values, solder with a thermal heat coefficient of around 67 W/m*K is at least factor 3 better than typical heat conductor pastes with 10 to 20 W/m*K. This yields in superior response times compared to conventional assemblies.

In other cases, sensors are placed into a process only some millimeters from the outside or – if pipe diameters are very low – placed on the outside of a tube.

These constructions lead, if the surrounding and process temperature differentiates substantially, to incorrect measurements which often can be observed due to heat transfer from the surroundings to the sensor. Using soldered sensors, this influence can be significantly be reduced (graph 1 and 2).

By using the soldered metallized solution from IST AG, the needed immersion depth is much lower compared to a standard assembly.

The soldering process can in some cases lead to changes in values or affect the accuracy due to mechanical stress during the soldering process.

Therefore, Innovative Sensor Technology IST AG is not only offering sensors with metallized backside for soldering but also constructions like soldered elements to tubes, in caps or on metal discs on different metals and in elements with individual tolerance classes can be provided in order to compensate for reproducible offset shift while soldering the elements to the different metallic surfaces.