Witcom Engineering Plastics, part of Wittenburg Group, worked closely with injection moulder Miki-Plastik in a project to make new PCB magazines, which house and transport PCBs during their automated assembly process. For its high temperature magazine, Witcom needed an electrically conductive high temperature plastic.
Marcus Weiland, Managing Director at Miki-Plastik, says: “The vertical guide rack is a large, flat part that needs to be moulded within tight tolerances without any warpage. It also needs to be electrically conductive for ESD protection, and withstand impact loads, and, for our high temperature range, temperatures in excess of 130°C. We consulted with a large number of suppliers for a suitable raw material; Witcom Engineering Plastics was the only one to pick up this challenge.”
Witcom selected PES as the base polymer, as it can withstand temperatures of up 180°C, is inherently flame retardant and can be moulded within tight tolerances. Piotr Zgnilec, Lead Engineer in conductive thermoplastics at Witcom, says: “To achieve the conductivity needed for the ESD protection and some reinforcement, we could not use carbon fibre, because that would cause the parts to warp. Using conductive carbon black however, causes PES to become rather brittle. In close co-operation with Miki-Plastik we developed a new formulation based on a unique conductive carbon black, which did not show brittleness and had enough flow to fill these large tools. Witcom PES-EC is a multi-purpose grade which can be injection moulded as well as extruded.” Christine Van Bellingen, Business Development Manager for conductive applications, adds: “Other potential market areas we are looking at include conductive high temperature sheet and other components for electronics manufacturing.”