The effect of droplet ejection frequency on the dimensions of inkjet-etched micro-via holes in poly4(-vinyl phenol) thin films

The relationship between the size of inkjet-etched via-holes produced in poly4(-vinyl phenol) thin films and the number of ethanol drops dispensed was established for a range of droplet ejection frequencies. The physical mechanism underlying this relationship is proposed and the dependence of the development of via-hole dimensions on the droplet ejection frequency is believed to be attributable to the extent of evaporation of the solvent between two consecutive drop dispenses. The results indicate complete penetration of the via-holes through the polymer layer when produced at low droplet ejection frequencies. Electroplating was used to deposit Cu into the created holes to further confirm the absence of polymer residue at low frequencies. A threshold frequency, under which no via-hole enlargement occurs, has been found. The study systematically focuses on the influence of droplet ejection frequency on the size of the inkjet-etched via-holes versus the number of droplets used in poly4(-vinyl phenol) dielectric thin films for printed electronics application.