Structuring of Laser Activated Polymers for Sensor Applications

Previous publications have shown that polymer based materials hold a great potential for the use as substrates for sensors, for example for AMR sensors. Polymers can substitute expensive substrates such as silicon, and pre structured substrates can eliminate substantial cleanroom and micro-technological processes, especially photolithography. Ultimately, process optimization can yield manufacturing processes without expensive procedures (through-silicon vias), guaranteeing a complete abandonment of processes such as photolithography, CMP and the like. At this point, injection molding with laser direct structuring (LDS) polymers offers distinct advantages, such as the electroless and selective deposition of metals, which can be used to implement through-vias. In this context, the LDS capable polymer polyetheretherketone (PEEK) is employed. The thermoplastic polymer features a high glass transition temperature and chemical resistances to many solvents. As a result, the substrate material can potentially cover a wide range of applications, especially due to the ease of integration into micro-technological processes. The presented sensor structures were produced by micro-technological processes and contacted using LDS-realized vias. The cost-effective polymer-based module, or rather the substrate, can be integrated directly into other processes and modules, such as a system on a chip system, without the need for costly processes for mounting the devices. To verify this, temperature and magnetic field sensors based on the AMR effect were manufactured and evaluated. This article demonstrates that approach using a process developed at the Institute of Micro Production Technology (IMPT).