Development of thermoplastic films for ultrasonic manufacturing of printed circuit boards

Conventional production processes of PCB involve a high amount of complex production steps and the use of hazardous chemicals. Furthermore, a great effort is required for their recycling. Ultrasonic hot embossing of coextruded films, filled with electrical conductive fillers, could be an economic and ecological alternative for the production of PCB. This study focuses on the identification of suitable filler–matrix combinations for the isotropic and anisotropic conductive film layers. Hence, monolayer films with different fillers and filler contents are extruded. Conductivities of 8.31 and 12 S/m were measured in cross and machine direction, respectively, for a polypropylene‐film with 10 wt.‐% of CNT. This is two magnitudes below the required 535 S/m. With 70 mS/m, the conductivity in thickness direction is 115–170 times lower. This is caused by process‐related surface layers with low filler content. For steel fibers, no electrical conductivity can be measured.