Conductive microstructures and connections for microelectronics made by ink-jet technology

Production of modern microelectronic devices needs printing technologies with the highest level of resolution and repeatability. Ink-jet technology with micro-dimensions nozzle is year by year wider used for this purpose. It makes possible to dispense small volumes of a material in the range of tens picolitres. As a result the printed matrix of dots, lines and more complicated shapes have tens to hundreds micrometers scale. The printing of electrically conductive microstructures requires dispensed materials containing conductive particles as filler. On the other hand, the nozzle diameter of a few tens micrometers and extremely high acceleration during "shots" needs liquid formulations with as low as possible viscosity and highly homogeneous structure. Such demands are fulfilled by ink containing silver particles with size dimensions less than 10 nm. Only this types of fluids work very stable during extremely long time. In the first part of the paper the background of nano silver production and its properties are presented Just after ink-jet printing process structures have the form of molecular fluid with no electrical conductivity. The main part of the paper is devoted to technologies which are necessary for obtaining the printed microstructures and connections with very high conductance. As a result it is possible to make lines and complicated shapes with resistivity in range 10-5 Omega cm.