An Improved In-line Inkjet Printing Process for 3D Multilayer Passive Devices

This paper describes an in-line process for the realization of 3D electronic components on A4 format substrate by piezo inkjet printing. This process is developed within a semi-industrial prototype system named “JETPAC”. JETPAC includes an oxygen plasma torch for surface preparation and post-process modules as a variable frequency microwave oven and an UV lamp for metal selective sintering and dielectric ink curing, respectively. JETPAC is used to achieve passive components by chaining conductor and dielectric layers on kapton® substrate: silver nanoparticles based ink is used to print conductors. For multilayer component elaboration, the metal ink is deposited both on kapton® and on printed dielectric materials. Due to a low surface energy (S.E) of the printed dielectric, the realization of efficient silver tracks is compromised. A special process combines O2 plasma treatment and UV exposure before printing, allowing the reaching of S.E. value on dielectric near the optimum one (55mN/m). This pre-process allows printing of well-defined conductive structures on top of the dielectric. In-line sintering of printed structures is then performed using variable frequency microwave source. The process allows the elaboration of multilayer structures including stacked resistors and capacitors. These results make the developed process very promising for the realization by inkjet printing of passive devices for smart tag applications.