The effect of droplet ejection frequency on inkjet-etched micro via holes

Inkjet etching has been identified as a potential route to formation of micro via holes in polymer dielectrics. Such vias could facilitate three-dimensional integration and sequential build-up fabrication in printed electronics. In the research reported in this paper, ethanol droplets were jetted onto a poly(4-vinyl phenol) (also known as PVP or PVPh) layer at different frequencies in order to observe the effect of droplet ejection frequency on the diameters of the via holes produced. The results demonstrate that via holes remain the same diameter at a low drop ejection frequency, while they enlarge at a relatively high frequency. A mechanism for this behaviour is proposed for which high speed photography provides evidence.