Inkjet printing is the emerging technology for the deposition of a variety of particles. The reliable printing of nano-silver inks shows the possibilities of digital fabrication of microelectronic circuits and raises the question for further use with other particles. To compete with common thick-film screen printing as a production method it is consequential and necessary to investigate the inkjet printing of all passive electronic thick-film components. Inductors are frequently required in electronic circuits, yet they represent a main challenge for thick-film printing. With the development of new materials, which are suitable for low-temperature cofired ceramic processes, the integration of passive components promises new applications.
In a first step, different ferrite particle compositions are dispersed to stabilized inks that can be used with a commercial inkjet print head. The stability of the ink is fundamental for reliable drop formation. In addition, the viscosity must fit to the print heads' operational ranges and the magnetic properties must be taken into account. In a second step, the effect of substrate coating and drop volume variation toward the shape of the printed structures are defined and shown. The fundamental construction methods of inkjet-printed inductors on fired ceramic are investigated. First, silver coils are printed without ferrite to optimize the printing pattern. Subsequently, coils are embedded in inkjet printed ferrite layers.
Depending on the geometrical layout, several drying and firing steps are necessary, leading to a more complex production process and influencing the electrical properties. Finally, it is shown that inkjet printing is very effective for built-up of multilayer thick-film inductors, and the high accuracy of the printing process promises accurate electrical values.
Fabrication of a Mn-Zn Ferrite Particle/Polyimide Composite Thick Film for Transmission-Line Devices.