Electrically Conductive Thermoplastic/Metal Hybrid Materials for Direct Manufacturing of Electronic Components

摘要

The work presents a novel polymer/metal hybrid material consisting of a thermoplastic polymer, copper fibers, and a low melting metal alloy, which is molten during processing. The material allows for electrical conductivities comparable to those of steel and still offers a good processability by injection molding. Still, the material's high metal content influences the filling and freezing behavior and therewith the part properties significantly. Injection molding trials were performed to characterize the filler distribution and the resulting electrical conductivity in dependence on the processing conditions and the matrix polymer choice. The metal alloy allows a homogeneous filler distribution within the part, which results in a high surface conductivity. Still, due to fiber-poor shear zones the electrical conductivity measured over the part thickness is decreased in comparison to the passage conductivity. A more homogeneous conductivity distribution can be achieved when the metal alloy has a higher melting point than the chosen polymer matrix. The high metal content and therewith the increased thermal conductivity of the material limits the realizable flow lengths. Here, adjustments to the mold temperature control allow a significant increase of the material processability and flowability for an optimized production of conducting Structures.