Sintering Process Conditions for Additive Printing of Multi-Layer Circuitry Aerosol-Jet Process in Conjunction with Nanoparticle Ink

Flexible electronics has emerged as a new form-factor in the consumer and defense applications. Aerosol-Jet Printing technology has shown potential for additive printing of flexible electronics on both planar and non-planar surfaces. The width of the needed lines can varied through control of the process parameters allowing the printing of very narrow traces of the order of 5-10μm in width. Reported research till date primarily concentrates on the single-layer printing with consideration of various parameters like humidity, temperature and strain rate. However, conventional PCBs are multi-layered and for the flexible PCB to be used in real-world it is important to have multi-layer stacking of interconnects and establish z-axis interconnections through vias as currently in the conventional PCBs. Use of additive methods such as aerosol printing method provides a great amount of design freedom without the need for specialized masks to establish the interconnects for different inks available like silver, copper, and carbon. In this paper, the objective is to establish z-axis interconnections with the help of Aerosol printable silver ink and dielectric polyimide ink. The silver ink would be using the ultrasonic atomizer to print, and the pneumatic atomizer has to be used for the polyimide ink. The printed conductive lines have been subjected to different sintering conditions and then tested for the parameters like resistance across the interconnects and shear load to failure.