Re-revolutionizing Hardware Prototyping TRAX: The Low-cost Circuit Printer

Abstract

In order for conductive ink technology to have a similar disruptive effect in hardware to that of 3D printing, it must become as financially accessible. TRAX, the low cost circuit board printer, achieves precise conductive ink printing with a minimalist design that can be put together for under $300 by combining existing elements in open source hardware and software with recent innovations in conductive ink printing. The body of the machine is modeled after open source 3-axis machines with an added automated syringe tip to dispense ink. Circuit layout designs up to 130mm x 180mm can be created in free vector drawing software which provides a minimalist, flexible schematic design platform. By removing the expensive elements in existing conductive ink circuit printer models that add convenience but are not essential, the majority of the body can be laser cut or 3D printed and the material costs of the entire device are lowered. With a 22.5ga TRAX syringe needle and silver conductive ink, the minimum trace width achieved was 0.5mm on FR4, a common PCB substrate. Smaller trace widths are possible with finer needles and adjustments to the dispensing pressure. The measured resisitivy of the traces after five minutes of drying at room temperature was 16.24 uOhm-m on the same substrate. Small surface mount devices adhere most easily to the PCBs with conductive ink; whereas larger components may require an additional adhesive to attach the body directly to the board for better stability. This successful first step in accessible circuit prototyping proves that there is a space for innovation in open source, conductive ink based electronics. Future optimization of the TRAX model can further democratize hardware for students and hobbyists.