Innovative Fabrication of Polymer-Based Sensor Systems by Flip-Chip Integration of Ultrathin Chips Using Nanowires for Medical Applications

Inhalt:
Polymer-based,miniaturized,intelligent sensor systems have experienced significant growth in recent years, especially in the healthcare sector for monitoring vital parameters with surface systems or short-term implants. Sensor systems on the market are only partially flexible and miniaturized because the electronic components are routed through printed circuit boards, making the overall system more rigid and bulky. In this work, a new concept is presented in which ultrathin chipsare connected to a 16 µm thick polymer-based sensor film usingnanocontacts to realize a flexible miniaturized sensor platform. The polymer film is made of PI-2611 polyimide and contains 300 nm strain gauges made of gold. The associated conductors are routed to 46 µm x 53 µm docking pads, on which copper nanowires are galvanically grown to connect the small chips to the film. The flip-chip joining process was studied in more detail, varyingthe joining force from 1 N to 10 N while keeping other parameters, such as the temperature and time, constant. Infrared microscopy and electrical four-point measurements were used to verify the results of the flip chip joining process. Initial measurements demonstrated a reliable electrical connection between the polymer film and the chips. The manufactured polymer-based sensor system is a key part of a sensor platform and is intended to be used in vivo to measure strain changes to support catheter navigation.