The effect of electromigration on the lifetime and performance of flexible interconnections fabricated by laser printing and sintering

Abstract Laser Induced Forward Transfer (LIFT) combined with laser sintering of nanoinks, has been proven a key enabling technology for flexible electronics. In this paper we demonstrate how this technology can also be applied for achieving high-resolution flexible interconnections, with form factors tailored for high current density stress tests. To this end, we have employed different flexible substrates, such as Polyethylene Naphthalate (PEN) and SU-8, for the validation of the performance of these interconnections: an all-laser fabricated flexible platform comprising Ag nanoparticle microelectrodes has been developed for running stress tests for the investigation of electromigration (EM) of Ag, a phenomenon responsible for short lifetime of flexible circuits. In particular, we have studied the effect of grain size and substrate (joule heating) on the EM induced failure. Data extracted from these tests were fitted to the percolation theory model and a custom model suggested by the authors that achieved optimal fitting results and provided porosity factors of the printed patterns. On top of the porosity factor extraction, Scanning Electron Microscope (SEM) micrographs have confirmed that the porous morphology, the presence of voids and their evolution to cracks influence the rate and the intensity of failure mechanism.