Feasibility Study on the Recycling Method for Material Preparation for the In-Situ 3D Printing of Electronics

The proposed research aims to continue the technology partnerships between Alabama A&M University (AAMU) and NASA Marshall Space Flight Center (MSFC) to jointly investigate the feasibility of the recycling method for material preparation for the in-situ 3D printing of electronics. This proposed 12 month research project will focus on the feasibility study of the recycling method for semiconductor material preparation. The proposed research involves the 3D printing of a diode using semiconductor filaments, the grinding processing of the 3D diode component into powder, the separation of semiconductor materials from the powder mixture, the re-print of the diode using first generation recycled semiconductor materials, and the property comparison between the 3D printed diode using the original and first generation recycled materials. AAMU will contribute more than 50 percent of the total resources necessary to accomplish the effort. The feasibility study, testing and evaluation of the recycling method will be conducted at AAMU and MSFC facilities. MSFC’s strategic focus is to effectively collaborate with AAMU and help facilitate the further development of unique additive manufacturing technique that can then be applied in MSFC’s various printing processes to create the next generation of fully printed electronic components to be used in space.

The In-Situ Resource Utilization (ISRU): In-Space ISRU harness and utilize space resources to create products and services which enable and significantly reduce the mass, cost, and risk of near- term and long-term space exploration. The in-space additive manufacturing technology for printing electronics would use materials found in space such as dust or rocks on Mars and Moon. NASA is exploring various forms of additive manufacturing for designing, constructing, and operating individual components, subsystems, and entire systems for a wide range of autonomous space systems. NASA Marshall Space Flight Center (MSFC) is developing technology for in- space advanced manufacturing and repair, including printed electronics. For long duration space transportation, the on-demand 3D printing of electronics became extremely important when electronic components failed working properly and need to be replaced during flight. In addition, additive manufacturing applications may influence and benefit human-related systems or facilities operated temporarily or permanently in space such as Mars.

In-space 3D printing of electronics requires the access to both the N-type and the P-type semiconductor materials because semiconductor is the key materials necessary for the generation of electronic device. However, the natural resources available in Mars and Moon’s surface does not provide this vital elements. The surface of the Mars is made of a thick layer of oxidized iron dust and rocks of the same color. Magnesium, Aluminum, Titanium, Iron, and Chromium are relatively common elements on Mars. According to the measurement of the chemical composition of six soils and five rocks at the Ares Vallis landing site, obtained from the alpha proton x-ray spectrometer (APXS) on board the rover of the Mars Pathfinder, the weight percentage of SiO2 found in the dust or rocks is between 48 to 62%, and the weight percentage of the FeO in the dust or rock is between 12 to 17%. There are very small weight percentage of TiO2 found between 0 to 1.2%. This discovery post a great challenge to the In-Situ manufacturing technology: where do we get the required semiconductor N-type or P-type elements from the natural resources in space for printing electronics?

Waste electronic components is the fastest growing waste stream in the ground and even in space. There are two main parts of a waste electronic components: the printed circuit board (PCB) and the polymer and/or metal portion that covers the PCB. PCBs contain a lot of components like resistors, conductor, capacitor, semiconductor, transistors, microcontrollers, integrated circuits etc. Once an electronic component becomes obsolete, these electronic components can be recycled. It is obvious that recycling of the waste electronic components containing semiconductor may provide a cost-effective way for in-space ISRU additive manufacturing of functional electronics.

Questions remains: 1) Is it possible to recycle the waste electronic components and to re-generate the semiconductor materials suitable for 3D printing electronics, 2) If the recycle technology exists, and if we can use the identical 3D printing technique to generate the electronic component using the recycled semiconductor materials, what will be the electric property change in the printed component?

The Semiconductor Materials Preparation for 3D Printing of Electronics: Additive Manufacturing Technology (3D Printing) is primarily based on layer-by-layer deposition of materials. There are two types of widely used direct printing technologies: Embedded printing and Aerosol Jet direct printing (ink-jet printing). The embedded 3D printing of electronic components combined the traditional layer-by-layer printing technology with embedded interconnected and pre-fabricated electronic components to create cost-efficient manufacturing of electronic devices. The direct 3D printing of electronic circuits including resistors, capacitors and semiconductors presents a great fundamental challenge to the technology innovator. Most printed electronics are made with two and half dimensions inkjet screen printers that print specialized ink or bonded powders on a planar surface with adjustable third direction. For example, the Aerosol Jet printing print specialized ink or bonded powders. The ink printing material is generally comprised of conducting metal powder, a binding agent and a mixture of solvents. When combined at proper ratio, one can produce liquid or powder form of ink that can be printed from existing 3D printers.

MSFC has been developing versatile and unique approaches to additively manufacture electronics utilizing a variety of printing technologies available today. Many of these approaches and capabilities have been targeted for their effective use on the ground and eventual use in space and on the International Space Station (ISS). Each printing methodology leverages Marshall’s nano- electronic materials development capabilities to take virtually any raw material and convert it into a range of electronic inks to be deposited by various printing processes. The driving variable in how these inks are then deposited is determined by their intended application and fluid viscosity ranges. MSFC has gained a significant advantage in applying thick film material development processes to manufacture a variety of electronic thick film devices by employing the practice of screen printing. Although the conductor and capacitor can be directly 3D printed, the direct 3D printing of semiconductors still presents great fundamental challenges to the technology innovator. Additionally, the ink storage, transportation and operation in microgravity environment present great challenges. The multi-materials 3D printing of electronics in space can be achieved through filament-based deposition techniques because it is relatively easy to store and transport. However, the semiconductor filament-based materials are proprietary materials. Currently, there is a limited supply of commercial semiconductor ink or filament materials.

Under the support of NASA CAN program, AAMU in collaboration with MSFC, started the 3D printing electronics research in 2016. In 2017, AAMU developed semiconductor filaments for direct 3D print an electronic device using semiconductor powders, ABS and PLA. A unique 3D printing technique was also developed to 3D print using the semiconductor filament. This unique additive manufacturing technique provides a platform to conduct printing, testing and property characterization of the filament materials for the direct 3D printing of functional electronics. Table 1 listed the source powder materials for the creation of the filaments, based on the unique AAMU additive manufacturing technique. Six fundamental components have been analyzed for the 3D printing of electronics: conductor, capacitor, resistor, N-type semiconductor, P-type semiconductor, and insulator.

The semiconductor filaments are made of commercially available semiconductor wafers or powders with PLA or ABS. To expand the ability of semiconductor materials preparation, we would like to produce the electronic component using semiconductor materials recycled from the waste electronic component. This recycling method has the potential to lift our ability of semiconductor materials preparation to a new level to meet ISRU requirements. Although the re- fabrication technology exists for carbon-based materials, the recycling technology for semiconductor materials does not exist.

This is early/mid-stage (TRL 1) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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