Processing and Characterization of Inkjet Printed BaTiO3/SU-8 Nanocomposite Dielectrics

Mustapha A. Muhammad, Wright State University

Abstract

The persistent demand for flexible and wearable electronic components in healthcare, aerospace, media, and transit applications has led to a significant shift from traditional electronics processes to printed electronics. Printed electronics are anticipated to establish itself as the industry's dominant force due to their enhanced flexibility, rapid prototyping capabilities, and seamless integration with everyday objects. They are cost-effective and have the scalable option for large-scale production because additive manufacturing techniques are used. Among the various printing methods available, inkjet printing has recently gained popularity for printing electronics, especially capacitors that require precise and complex structures on different substrates. Inkjet printing relies on micro dispensing additive technology, where liquid phase materials are dispensed using the drop on demand (DOD) technique with conductive nanoparticle inks. Researchers have made several attempts to fabricate fully inkjet-printed composite capacitors and have discovered that the permittivity value of the composite increases compared to a polymer. This suggests that using composites as the dielectric material in a capacitor can potentially increase the capacitance value. However, despite the discussion on various composite dielectric materials, there is a scarcity of information on the use of BaTiO3/SU-8 dielectric materials for capacitor applications. To address this gap, the objective of this study is to formulate BaTiO3/SU-8 ink suitable for inkjet printing and develop a printing process for layered metal insulator metal (MIM) structures. The formulated BaTiO3/SU-8 ink is employed to print the dielectric material, while nano silver ink is used for the two electrodes, enabling the fabrication of the capacitor in a single step. The study takes into account volume and speed jetting parameters as well as waveform to achieve optimal and uniform liquid phase material inkjet printing on the substrates. The thickness of the printed layers is measured using a profilometer, and the sheet resistance of the inkjet printed nano silver conductive ink is evaluated using a four-point probe. Furthermore, the dielectric properties of the printed composite are characterized by measuring the capacitance value. The main goal of this paper is to provide insights into the formulation of BaTiO3/SU-8 dielectric materials and understand the processes involved in the fabrication of a full inkjet printed composite MIM capacitor. Additionally, the experimental results will be compared with theoretical models of BaTiO3/SU-8 dielectric developed by our research group. The successful development of inkjet printed composite MIM capacitors using BaTiO3/SU-8 dielectric materials has the potential to revolutionize the field of printed electronics. The ability to print capacitors with higher capacitance values and complex structures on flexible substrates opens up new possibilities for the integration of electronics into various applications. This research makes a valuable contribution to the expanding knowledge base in the field of inkjet printing for electronics, laying the foundation for future advancements in flexible and wearable electronic devices.