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We present here an investigation aimed at exploring the role of the microstructure on the magnetic properties of nanostructured cobalt ferrite. Bulk, almost fully dense, nanograined ferrites have been obtained starting from nanopowders prepared by a simple, inexpensive, water-based, modified Pechini method. This synthesis yielded largely aggregated, pure single-phase cobalt ferrite nanoparticles of ca. 35 nm average size, which have been then densified by high-pressure field-assisted sintering. Different sintering conditions (pressure up to 650 MPa and temperature up to 800 °C) and procedures have been used on both as-prepared and milled nanopowders in order to obtain materials with a spectrum of complex microstructures. In all cases, the sintering process did not produce any change in the phase composition. At the same time, using a high uniaxial pressure in combination with relatively low sintering temperatures and times, allowed for obtaining a high degree of densification while preserving the nanometric size of the crystallites. Moreover, we observed that in the densified materials the best magnetic properties are not necessarily associated with a more uniform microstructure, but rather arise from a delicate balance between moderate aggregation, grain size and high density.

Aerosol jet printing (AJP) is an emerging additive manufacturing technology that is gaining increasing attention in the electronic field. Several studies have been carried out on the AJP of conductive, semiconductive, and dielectric polymers for electronic applications. However, wafer bonding is an application that is still uncovered by literature. Therefore, in this work, the AJP of benzocyclobutene (BCB) as a polymeric adhesive for wafer bonding is presented for the first time. A thorough characterization of the processing parameters is carried out to identify the most ideal conditions for printing at a relatively high speed. Then, square patterns are printed, proving the versatility of the AJP technology in terms of the reachable thickness of the deposited BCB patterns. Complex patterns with a resolution of ≈60 µm are also printed. The bonding properties of the BCB are characterized from a morphological and mechanical point of view. In particular, the shear strength of the BCB coatings deposited with AJP is ≈39 MPa and it is comparable with the shear strength of BCB coating deposited by spin‐coating. Consequently, AJP represents a valid alternative for the deposition of polymeric adhesive for wafer bonding.