Precision Dispensed Die Fillets as Nonconformal Surfaces for Printed Interconnects: Characterization, Optimization, and Mechanical Performance Assessment

The ability to fabricate smooth transitions between surfaces at different levels is critical for the establishment of robust printed interconnections in flexible hybrid electronics devices. In this article, precision dispensing of die fillets is proved to be a viable technology for that. A dispensing process is characterized and evaluated based, among others, on the principles of statistical design of experiments. The functionality of the fabricated fillets is evaluated through printing of conductive traces over them. Moreover, the performance of the printed conductive lines is assessed through tensile tests. Several solutions are engineered and tested to assure proper electrical behavior of the lines under fatigue cycling. Finally, it is shown that this process can be utilized to replace free-standing wire bonds.