MacFarlane Endowed Distinguished Professor and Director Auburn University, AL, United States
Traditional electronics employ stiff architectures that are implemented in planar format on glass-epoxy impregnated printed circuit boards. Flexible hybrid electronics allows for a closer integration of electronic function and structural form. The promise of additive-print methods is a faster time-to-market and a faster time from design to first prototype. The linkages between print methods, assembly conditions, and projected performance in the end application are required for realization of high-volume production. This study looks into the interaction of process parameters with the electrical, mechanical, and realized performance of ink-jet printed substrates and direct-write substrates. The frequency response of additively printed circuits have been compared to conventional circuits. The shear load to failure and resistivity of the printed lines were evaluated to quantify the performance of the printed lines. The process characteristics evaluated include droplet volume, on-off voltage, phase width, on-off duration, print speed, resolution, ink pressure, platen temperature, and standoff height. For signal processing applications, component attachment recipes have been devised for both ink-jet printed circuits and direct write printed circuits. Component attachment using both ECA and LTS has been demonstrated to provide low impedance interconnects with values of surface-mounted R, L, and C that are near to the component's rated value. The optimal sintering profiles for ECA attachment have been identified. The LC Filter with both an ECA and an LTS attachment was built using the found process recipes and process-property interactions. The frequency response of the additively produced LC-filter was compared to that of a typical subtractive filter to demonstrate equivalent performance.
