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Low temperature copper inks for low-cost flexible hybrid electronics manufacturing

Description:

TECHNOLOGY AREA(S): Materials 

OBJECTIVE: Develop copper solutions/inks compatible with low-temperature manufacturing processes to enable improved conductive copper features for flexible hybrid electronics and conformal antennas 

DESCRIPTION: The electronics industry has been developed around the properties and integration capability of copper due to its relatively low cost and high conductivity. However, as the market moves toward new applications such as flexible hybrid electronics and conformal antennas based on additive manufacturing processes, printed metal conductors have been based primarily on silver inks, which typically require photonic or high-temperature curing. In addition to the higher costs imposed by silver inks, these post-processing steps require additional manufacturing tools, high-temperature processes, and limited and higher-cost substrate materials. By producing a low-temperature, air-stable copper solution, high performance and lower-cost metallization on substrates such fabric, cellulose, and plastics could be enabled. These inks could lead to applications such as low-cost wearable human performance monitors for health/wellness and medical uses as well as high-performance conformal antennas for both aircraft integration and body-wearable concepts. Copper inks that are compatible with traditional electronics manufacturing services (EMS) deposition processes such as screen printing, ink jet printing, etc. could deliver these capabilities at significantly lower cost than the sliver inks available today. 

PHASE I: The goal of Phase 1 is to demonstrate a copper solution that can be deposited in ambient conditions. If a post-deposition heat treatment is required, the solution/ink should be compatible with a standard oven at temperatures lower than 130C. The copper features should achieve not less than half the bulk conductivity of copper, should be compatible with a broad range of substrates (e.g., PET, polyimide, fiberglass, cellulose, textiles), and accept solder without degradation. Phase 1 should demonstrate copper ink deposition on at least two relevant substrates with feature sizes smaller than 50 microns. 

PHASE II: Phase 2 will focus on the migration of the copper solution/ink and low-cost manufacturing process into an inline assembly process. Processing protocols will be developed and demonstrated that are compatible with low-cost and scalable deposition methods typically employed by the EMS industry. Phase 2 should include an integrated package relevant to the Air Force customer that is assembled in a small scale production process. The assembly should meet Air Force operational and robustness requirements and should have a clearly specified manufacturing plan. 

PHASE III: Demonstrate the process at an industrially-relevant scale and transition to an EMS partner. 

REFERENCES: 

1: Rosen, Y., Grouchko, M., Magdassi, S., "Printing a Self-Reducing Copper Precursor on 2D and 3D Objects to Yield Copper Patterns with 50% Copper's Bulk Conductivity, Adv. Mater. Interfaces, 2: 1400448.

2:  Giuseppina Polino, Robert Abbel, Santhosh Shanmugam, Guy J.P. Bex, Rob Hendriks, Francesca Brunetti, Aldo Di Carlo, Ronn Andriessen, Yulia Galagan, A benchmark study of commercially available copper nanoparticle inks for application in organic electronic devices, Organic Electronics, Volume 34, 2016, Pages 130-138, ISSN 1566-1199.

KEYWORDS: Copper, Printing, Ink 

CONTACT(S): 

Benjamin Leever (AFRL/RXAS) 

(937) 255-9141 

benjamin.leever@us.af.mil 

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