Reliability investigations on LIFT-printed isotropic conductive adhesive joints for system-in-foil applications

The reliability of a commercially available isotropic conductive adhesive (ICA) deposited via laser induced forward transfer (LIFT) printing is reported. ICAs are particularly important for surfacemount device (SMD) integration onto low-cost, large-area system-in-foil (SiF) applications such as radio frequency identification (RFID) transponder tags. For such tags, and for SiF in general, the reliability of the printed interconnects under harsh circumstances is critical. In this study, the reliability of surface mounted resistors bonded onto screen-printed conductive circuitry on polymer foil was assessed. The prepared samples were subjected to thermal shock testing (TST), accelerated humidity testing (AHT) and flexural testing, while electrical measurements were conducted at regular intervals. Die shear testingwas performed to evaluate the bond strength. The reliability characteristics of the LIFT-printed sampleswere benchmarked against current industry standard stencil printing process. Finally, the applicability of the LIFT–ICA process for practical applications is demonstrated using RFID transponder integration and testing

High resolution iridocorneal angle imaging system by axicon lens assisted gonioscopy

10.1038/srep30844Scientific Reports63084

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

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 248nm KrF-excimer laser was used to print the epoxy-based conductive adhesives containing silver flakes down to 75μm 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. cop. 2014 Astro Ltd