Researchers at the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research IFAM in Bremen, Germany, are working on a new printing technique for creating conductor paths in sensors.
"Up to now, contacting was usually done with wire bonds " thin wires, that is," explains IFAM project manager Christian Werner. "But wire bonds stick out, and thus impair the flow behaviour of the gases and liquids. That can affect high-precision measurements."
IFAM's researchers have therefore developed a technique called INKtelligent printing, whereby they print the conductor paths instead of wiring them.
The difference between IFAM and other contactless aerosol printing methods is the ink: "The suspension contains nano silver particles in a special solvent," says Werner. "This enables us to print extremely thin-layered conductor paths." Subsequent thermal treatment activates the electrical conductivity of the paths.
Colleagues from the Institute for Microsensors, actuators and systems (IMSAS) in Bremen helped the researchers test the conductor paths. The finding show that in contrast to wire bonds, which have an overall height of 1 to 1.5 micrometres, the printed conductor paths are between just 2 and 3 micrometres high, or almost five hundred times thinner than wire bonds, and thinner conductor paths mean less obtrusive connecting wires, leading to more accurate measurements. The results were first published in Fraunhofer-Gesellschaft, a Fraunhofer publication highlighting its applied research.