Resistive Measurement
Temperature sensors that utilize a microscopic layer of platinum deposited onto a ceramic substrate provide high accuracy and stability for industrial applications. The thin film RTD operates on the principle that the electrical resistance of the metal increases in a predictable way as it gets hotter. This relationship allows a simple voltage measurement to be converted into a precise temperature reading.
Platinum is chosen because it resists corrosion and maintains a stable resistance over a wide range of operating conditions.
Manufacturing Process
Sputtering or evaporation techniques are used to apply the metal layer with a thickness of only a few microns. After deposition, a laser trims the path of the metal to reach a precise resistance value, such as 100 or 1000 ohms. This precise construction makes the thin film RTD more compact than wire-wound versions.
Thermal Response
The low mass of the sensing element allows it to react quickly to changes in the surrounding environment. Because a thin film RTD is mounted on a flat ceramic plate, it has a large surface area for heat transfer. This design minimizes the time delay between a temperature change and the corresponding electrical signal.
Application Range
These components are used in everything from household appliances to high-precision laboratory equipment. While they are very stable, a thin film RTD is more susceptible to strain-induced errors than a wire-wound type. Protective coatings are applied to the metal layer to prevent oxidation and chemical contamination at high temperatures.
