Micro-scale Cu metallization on polyimide substrate for high-speed interconnects

The present study can be applicable to fine wire interconnections, particularly for high-speed solutions in 3D packaging. The fine traces with 50 micron pitch (25 ¼m line/space) built on a flexible 50 micron thick polyimide film using wet fabrication process are reported in this paper. The thick copper (Cu) layer was obtained from the Cu plating process using evaporated ultra-thin layer of Cu as the adhesion layer between Cu and a Polyimide (PI). The fabricated fine-pitch pattern is inspected for further failure analysis using scanning electron microscope (SEM) and energy-dispersive spectrometry (EDS) technologies. The experiment is conducted to study the effect of the process parameters on the Cu film surface properties. The results obtained in this work can be applied to the fabrication of flexible high-speed interconnection devices.