Inkjet Printing of Electrical Connections in Electronic Packaging

Two aspects were evaluated of an approach to produce inkjet printed electrical connections in a roll-to-roll application. In the first part it was demonstrated that inkjet printing with silver nanoparticles allows to connect LED dies embedded in a flexible polymeric substrate by way of electrical via connections and to operate the LED dies at their nominal 20 mA and 3 V driving conditions. A standard convection oven process was used to sinter the inkjet printed tracks. The second part of the work focused on identifying sinter technologies that provide the required fast processing times needed for roll-to-roll applications. IR irradiation, Rapid Electrical Sintering, and Broadband Photonic Curing were evaluated and compared with Convective Oven Sintering as benchmark technique. All these techniques produced similar track conductivities. Fastest operation was obtained with Broadband Photonic Curing, which enabled a total process time of three seconds as compared with 150°C and 30 min in the convection oven.