Investigation of the effects of LIFT printing with a KrF-excimer laser on thermally sensitive electrically conductive adhesives

Abstract

Laser induced forward transfer is an emerging material deposition technology. We investigated the feasibility of this technique for printing thermally sensitive, electrically conductive adhesives with and without using an intermediate dynamic release layer. A 248 nm KrF-excimer laser was used to print the epoxy-based conductive adhesives containing silver flakes down to 75 μm dot size. The process is particularly relevant for realizing electrical connections to surface mount devices in the microelectronics industry. Characterization of the printed materials was analyzed by Fourier transform infrared spectroscopy, four-point electrical measurements, die-shear testing and temperature shock testing, to establish that the properties of the adhesive were not affected by direct or indirect laser irradiation. The lack of degradation by the laser onto the adhesives confirms the potential of this technique for interconnection applications.