Frank Löffler

Functional metal-based coatings on ceramic substrates

For applications in the fields of metrology, e.g. the evaluation of calorimetric parameters or electrical measurements, the combination of a ceramic substrate with a metal-based coating is necessary. The applications require coatings with a good adhesion and a high purity which can withstand a corrosive medium at various temperatures. Typical coatings are copper, silver, gold and platinum. These coatings can be achieved up to 1 mm in thickness and with a homogeneous structure by electroplating of electrically conductive substrates. The paper describes different possibilities for the metallizing of insulating substrates or insulating layers prior to a precious metal coating.

Thin-film sensors with small structure size on flat and curved surfaces

We have developed a fabrication technology for thin-film sensors on metallic substrates with flat and curved surfaces. Physical vapour deposition by means of a magnetron sputtering system is used to deposit an insulating layer and a following functional layer. This layer is structured by distinct photolithographic steps utilizing a self-developed spray coating technique, four-axis robotics with micrometer precision and a UV laser with a spot size below 10 μm. This highly flexible technique allows a rapid change of design to produce various sensor layouts in a short time. Besides the fabrication technology, we present two realized applications for thin-film sensor technology in this paper. First, a tool wear sensor for rotating cutting tools, directly detecting the flank-wear land width, and second, sputtered resistance strain gauges for force measurement. Measurement results showing the potential of thin-film sensors are given briefly.