This article presents an experimental demonstration of coplanar waveguide (CPW) transmission lines fabricated using aerosol jet printing (AJP) on high-purity fused silica (HPFS) glass substrates. The work addresses the growing need for low-loss, high-frequency interconnects compatible with additive manufacturing. The fabrication process is outlined, emphasizing key technical aspects and challenges of printing on glass. Two commercial silver nanoparticle inks, Dowa and NovaCentrix, were evaluated. CPW structures with 20 & micro;m trace-to-ground spacing were successfully printed and characterized up to 30 GHz. Measured insertion losses were 0.11 dB/mm for Dowa ink and 0.15 dB/mm for NovaCentrix ink. These results demonstrate the feasibility of combining aerosol jet printing (AJP) with HPFS substrates for high-resolution, high-frequency applications. Overall, this approach shows strong potential for developing low-loss radio frequency (RF) interconnects on advanced glass platforms, enabling integration into next-generation electronic and communication systems, such as radio-on-glass front-end modules, transparent and phased-array antennas, and high-speed optical transceivers.

Printed electronics techniques are increasingly utilized for device fabrication, particularly in flexible electronics. This study investigates the performance trade-offs associated with additive printed electronics methods and materials, focusing on antenna gain. A dual-band dipole antenna, operating at 2.4 GHz and 4.6 GHz, was designed using the ANSYS High-Frequency Structure Simulator (HFSS), with printed silver as the conductive material and 5mil (125 μm) Kapton as the substrate. Three sets of antennas, each with different conductive materials and printing techniques, were fabricated while maintaining a consistent substrate and antenna design. The fabrication techniques include dispensing and aerosol jet printing, with the conductive materials varying in particle size. Results show that resistance primarily affects antenna gain at 2.4 GHz, while the microstructure of the conductive material plays a more significant role at 4.6 GHz.

Additive manufacturing of conductive interconnects has become essential in the electronic industry due to the requirements of having smaller electronic components with high performance and producing functional electronics that meet the applications demand. Thus, fabricating conductive lines and patches is key to reduce the challenges of mechanical and thermal reliability associated with advanced electronic technologies. In this work, high-resolution conductive interconnects were fabricated by aerosol jet printing (AJP) across different substrates using a novel particle-free silver ink. The conductivity of the metallic ink was assessed after post-processing at various curing conditions and methods. The printing process parameters of the particle-free ink were optimized to yield high-quality printed features and to investigate the printed film’s continuity on a non-flat surface, including printing from the top of a silicon die to a flexible substrate. The current carrying capacity of the printed particle-free silver ink on NEA 123 material was evaluated and compared against a commonly used nanoflake-based silver ink by performing a current sweep increasing the current by 5mA every 10 seconds until failure. In this research, conductive interconnects with sub-micron thickness have been obtained. Photonic curing using PulseForge system was found to improve the conductivity at energy density of 3.22 J/cm2 to four times the conductivity of a conventional convection oven curing. The enhancement in conductivity appears to be due to the changes in the film’s microstructure, forming metallic connections between the needle-shaped crystallized grains as revealed by X-ray microtomography. The particle-free ink can be used for irregular surfaces with smooth transitions between the electronic components. Furthermore, the current carrying capacity tests show the printed interconnect’s resistivity increased and then reduced during the test before failure; the failure of the particle-free ink occurred at 2.022 x 105 ± 0.2 A/cm2 compared to 0.99 x 105 ± 0.18 A/cm2 for the nanoflake-based silver ink which makes the particle-free ink an attractive material for high-power electronics applications. Our findings assist the application of flexible hybrid electronics and electronic packaging by providing significant guidelines for electronics manufacturers.

The demand for cost-effective and advanced electronic systems is quickly growing for a wide range of applications. Additive manufacturing (AM) techniques allow fabrication of not only complex structures and objects but also functional electrical components. Printed electronics enable the creation of lightweight components, better flexibility in design, lower cost, less material waste, more reliable device performance and a simplified assembly process compared to conventional electronics. In this work, aerosol jet printing (AJP) was used to fully additively manufacture passive electronic components, including resistors, capacitors, inductors and circuits made from these components directly on alumina ceramic substrates. A regression model was used to estimate the resistor lengths for three various resistivities; 100 Omega, 1 k Omega and 10 k Omega. Three printed planer inductors; 0.1 mu H, 0.3 mu H and 1 mu H were designed in a spiral pattern to achieve target inductance through optimizing the spiral inner and outer diameters. Three values of printed metal insulation metal (MIM) capacitors; 100 pF, 300 pF and 1000 pF were designed and fabricated on ceramic substrates. The optimized process obtained from printing the individual passive components were used to fabricate RLC circuits consisting of a resistor, inductor and capacitor connected in series with high tolerance. Various environmental tests, including thermal cycling and constant acceleration, were performed to evaluate the printed component and circuit performance and robustness under extreme environmental conditions. The passive component materials exhibited acceptable outgassing with appropriate postbake conditions, making them suitable for spaceborne applications. Resistors were printed with carbon nanostructure-based ink that has a sheet resistance of 15 Omega/square. 100 Omega resistors were achieved by printing 0.5 mm length and 0.5 mm width traces, 1 kO and 10 kO were obtained by printing 5 mm and 55 mm length traces, respectively. The capacitors were designed by having two conductors (top and bottom) separated by a dielectric layer with a dielectric constant of 4.04. All inductors (0.1 mu H, 0.3 mu H and 1 mu H) were designed and printed to have a footprint area of less than 1 cm(2). The resistance, capacitance and inductance of the printed passive components were measured at various temperatures: -55 degrees C, -40 degrees C, 25 degrees C, 75 degrees C and 125 degrees C using a thermal forcing machine. The unit-to-unit variance of the printed passive electronic components was less than +/- 10% for resistors and inductors and less than +/- 20% for capacitors. This reproducibility indicates a good uniformity of the printing process and the selection of materials. The effect of temperature variation in the printed passive electronic components was investigated between -65 degrees C and 150 degrees C for 10 cycles for the resistors and inductors and 20 cycles for the capacitors. This thermal cycling test was followed directly by a constant acceleration test. The change of resistance, inductance and capacitance was less than 2% for individual components and the RLC circuits exhibited a change in resonant frequency of less than 5% at 100 KHz. Therefore, the printed components have good thermal stability, reliability and interaction between the ceramic substrate and printed inks with no change in the electrical properties.

The demand for high performance electronics is growing in advanced radio frequency (RF) systems. Additive manufacturing has become essential for developing high-density embedded electronics, enabling the integration of small components into a complex RF module and solving the space and interconnect constraints. This work focuses on developing and demonstrating additive manufacturing capabilities and processes that can be used to fabricate high-frequency RF multi-chip module (MCM) with embedded dies and low loss interconnects for weight, cost and size improvement. Firstly, alumina matrix was 3D printed to produce vias and a matrix of pockets for RF chips embedding. The aerosol jet-printed silver interconnects printability, stability and continuity on irregular surfaces were assessed and passed the thermal tests without losing its conductivity. The low noise amplifier (LNA) unit cell was fabricated, including vias filling, dielectric and coplanar waveguide line printing, obtaining RF gain of 10 dB and matching the simulation data. No physical or RF performance changes were observed on the LNA cells after aging at 70 degrees C/80 % relative humidity for 192 h, demonstrating excellent reproducibility of the additive manufacturing process. The MCM demonstrator including antenna board, 4 x 4 array of embedded LNA dies in alumina plate and control board was successfully assembled using lowtemperature 52In48Sn solders. Over-the-air (OTA) test of the demonstrator showed RF gain of 18 dB at 29-30 GHz compared to the case with the amplifier powered off, and it closely aligned with simulation results. This study demonstrates the capability of AM in advancing complex RF module packaging as an alternative to conventional methods.

There is a rapidly growing interest in the development of electronic microsystems that can maintain functionality in high temperature environments, particularly in power generation and aircraft engines where the operating temperatures can exceed 500 degrees C. The current work presents a major advancement toward development of additively printed electronics made for high temperature applications. Here, the electronic system is represented by gold-based electrical structures that have been printed on 3D printed ceramic substrates. The substrate is alumina-based with a purity level of 99.8% and was fabricated through photopolymerization digital light processing (DLP). An aerosol jet printing technique that can deposit an ink stream down to 10 mu m was utilized to fabricate gold-based electronic structures. The gold ink printability and its adhesion to the ceramic substrate were assessed. Furthermore, the microwave dielectric constant and loss tangent of the alumina substrate were extracted through measurements of the scattering parameters of transmission lines up to 750 degrees C. A 3D printed conformal broadband antenna was successfully fabricated and tested at temperatures up to 850 degrees C. The printed gold structures showed excellent stability and adhesion after aging at temperatures up to 750 degrees C. The substrate dielectric constant slightly increased for temperatures up to 450 degrees C and significantly increased for temperatures between 450 degrees C and 750 degrees C. It was found that the dielectric loss increased as the temperature increased. This work presents an entirely additive manufacturing-based approach to fabricate electronic components including substrates, interconnects, and RF elements for high temperature applications.