Direct laser write process for 3D conductive carbon circuits in polyimide

Direct laser writing (DLW) is a versatile materials processing technique often applied to device prototyping. However, a fast and cost effective DLW process for fabricating three-dimensional (3D) conductor–insulator composites has yet to be demonstrated. In this work, polyimide (PI) is established as a viable platform for creating 3D graphitic circuits through ultrafast DLW. Under optimized processing conditions, graphitic material with a resistivity of 6 Ω cm was formed in the laser irradiated regions. A thermal and microstructural material model is proposed for the non-linear DLW process and its graphitic products. The process is demonstrated to be an inexpensive and rapid technique for creating electrical contacts to nanoscale components. Future applications of the technique range from nanowire power generation to 3D integrated photonic and electronic devices.