Fabrication and characterization of ferrimagnetic film for RF/microwave crosstalk suppression

Graduation date: 2008The primary goal of this thesis is to fabricate a magnetic film between the coplanar transmitted stripline for crosstalk suppression. Crosstalk is caused from undesired inductive and capacitive coupling of signals between two conductors. The effective crosstalk suppression results from the inductive coupling of circuit elements through the lossy properties of magnetic material during ferromagnetic resonance (FMR). Several techniques were used to fabricate ferrite films, including ferrite plating, screen printing, and pressure die casting. Ferrite plating produce nanostructured zinc iron oxide (ZnFe₂O₄) films with lower crystallinity and do not exhibit cross talk suppression. Interesting, the films show a higher roughness with increasing film thickness. The contact angle measurement indicates the films changing from hydrophobic to hydrophilic with increasing film thickness. Screen printing was used to fabricate yttrium iron garnet (Y₃Fe₅O₁₂) films to replace ferrite plating zinc ferrite films, because of the magnetic properties\ud of yttrium iron garnet film. The results show that screen-printed films can achieve far-end crosstalk suppression by 10 ~ 12dB, however, no suppression effect for near-end crosstalk. It is believed that the polymeric binder caused the problem. A pressure die casting technique was used to fabricate the yttrium iron garnet films. These films achieve the far-end crosstalk by 22dB and the near-end crosstalk by 8dB at higher frequency 3.75GHz. For G-113 and TTVG-1600 screen-printed films, the resonant frequency occurs at about 0.75GHz. For TTVG-1850 screen-printed and pressure casting film, the resonant frequency occurs at about 1.7GHz and 1.25GHz respectively. Finally, a new fabrication technique that combines continuous flow reactor for the generation of nanoparticle precursors and pressure die casting were proposed for making denser ferrite thin films