Reliable and Automated Connection of Printed Electronics to the Aviation Electrical System

In recent years, numerous applications for printed electronics have been successfully implemented. Heating elements, sophisticated circuits, sensors, and antennas can be printed on a broad bandwidth of materials and three-dimensional surfaces. Several projects investigated the use of printed electronics in the aviation industry and demonstrated the applicability of printed structures on aerospace substrates. Printed systems were implemented to improve maintenance and passenger comfort and the automated repair of printed structures was proven. However, the reliability and contacting of the printed structures still is a major challenge. Especially for the use of printed electronics in the aviation industry, this research gap needs to be addressed. Therefore, a new research project investigates the reliable connection of printed electronics to the aviation electrical system. This research aims to find a solution that offers good electrical characteristics, is reliable, and can be manufactured in an automated way. To meet the requirements of the aviation industry, experts are consulted and a detailed catalog of requirements is drawn up. Preliminary tests were carried out in which connector elements were glued to the cabin linings and inserted into the substrate. The findings show that only concepts in which the connector is inserted into the substrate and glued, riveted, or screwed offer the necessary mechanical stability. Based on the experience from the preliminary tests and the catalog of requirements, a concept is developed that provides for the integration of a market-available and aviation-approved connector into the substrate of the cabin lining. To test the concept, a circuit is developed and implemented as a prototype. The most important electrical characteristic is the contact resistance of the connection. The goal is to produce a contact point with less than 1.0 Ω contact resistance. The measurement is conducted using the four-point method. The mechanical characterization of the prototypes is carried out using tensile tests and shear tests. The requirements for assessing the reliability are derived from the aviation requirements for mechatronic components. To meet the requirements, the demonstrator must withstand a temperature change from +80 °C to -40 °C in 10 cycles of 10 hours each and a load of 1000 mating cycles, with a change in contact resistance of a maximum of 5%. While the prototype is being characterized electrically and mechanically and its reliability is being tested, a concept for the automated integration of the connector into the aviation substrates must be developed. The printed circuit is produced in a five-axis CNC machine in which three-dimensional workpieces can be processed from almost all sides. The machine can also be flexibly equipped with numerous tools. In addition to systems for producing printed circuits such as piezo jet, aerosol jet, pick and place, and sintering systems, a milling machine can also be integrated. Therefore, the goal is to produce the printed circuit including the connection fully automatically in the five-axis CNC machine.