Preliminary Study of Printing Optical-Based Materials using Aerosol Jet Deposition Process

This work examines the printing of optical-based materials using aerosol jet printing (AJP), an additive manufacturing process. Deposition of optical-based materials using the AJP process has potential to be applied in the fabrication of embedded fiber optic Bragg grating sensors. Made from silica (SiO2), fiber optic Bragg grating sensors are small, lightweight, and chemically inert, making them suitable for a variety of applications. This study examines the preparation and deposition of a newly developed silica-based printing ink. The results of the printing method, the impact of various printing and processing parameters on the deposition quality and microstructure, light reflectivity, scanning electron microscope (SEM) images, and content analyses of the deposited layers are presented. The results show uniform printed layers and demonstrate the capability of the AJP method as well as the newly developed silicabased ink to print high-quality commercial optical-based materials. The focus of this study is on the process/ optical material property interaction only; the printing of actual functional sensors on components and testing them will be discussed in later studies and is beyond the scope of this paper.

Aerosol Jet® Printer as an Alternative to Wire Bond and TSV Technology for 3D Interconnect Applications

Aerosol Jet deposition systems provide an evolutionary alternative to both wire bond and TSV technology. As part of the Vertical Interconnect Pillar (ViP™) process, the Aerosol Jet system prints high density three-dimensional (3D) interconnects enabling multi-function integrated circuits to be stacked and vertically interconnected in high performance System-in-Packages (SiP). The stacks can include two or more die, with a total height of ∼ 2 millimeters. The non-contact printing system has a working distance of several millimeters above the substrate allowing 3D interconnects to be printed with no Z-height adjustments. The Aerosol Jet printhead is configured with multiple nozzles and a closely coupled atomizer to achieve production throughput of greater than 19,000 interconnects per hour. The Aerosol Jet printer deposits silver fine particle ink to form connections on staggered die stacks. High aspect ratio interconnects, less than 30-microns wide and greater than 6-microns tall, are printed at sub 60-micron pitch. After isothermal sintering at 150° C to 200° C for 30 minutes, highly conductive interconnects near bulk resistivity are produced. Pre-production yields exceeding 80% have been realized. This paper will provide further details on the 3D printed interconnect process, current and planned production throughput levels, and process yield and device reliability status.

Investigation of Aerosol Jet Deposition Parameters for Printing SOFC Layers

This work entails an investigation of the Aerosol Jet® Printing (AJP) method for depositing dense and porous layers necessary for the fabrication of solid oxide fuel cells (SOFCs). Ink preparation, method of printing, and the impact of various printing and processing parameters on the microstructure of layers will be presented. In addition, the electrochemical performance of anode supported button cells produced via the AJP process will be discussed. Thin electrolyte and cathode layers were deposited onto a standard anode-supported substrate and consisted of a yttria stabilized zirconia (YSZ) electrolyte, a strontium doped lanthanum manganate (LSM)/YSZ cathode functional interlayer, and a neat LSM cathode current collection layer. Optimal printing parameters for depositing dense electrolyte layers with thickness ranging from a few microns to a few tens of microns (8–33 μm) were identified. Porous composite cathode interlayers were printed from mixtures of individually aerosolized components of YSZ and LSM. Button cells incorporating the electrolyte and cathode layers on a NiO/YSZ support substrate exhibited stable voltage of 1.16–1.20 V at open circuit at 700–850 °C for hydrogen and air as fuel and oxidant, respectively. The results demonstrate the capability and potential of AJP method for deposition of layers necessary for SOFC fabrication and suggest that the method is very viable for obtaining highly reproducible microstructures with potential for mass manufacturing.