Using obfuscation and post-processing for IP protection in 3D printed electronics

• Noah Durbin, Computer Engineering, University of Delaware

• Nathan Lazarus, Electrical and Computer Engineering, University of Delaware

Additive Manufacturing (AM) has significantly advanced, with affordable 3D printers widely available and specialized, high-resolution printers accessible through external vendors. Similar to these high-end printers, CMOS foundries are expensive, leading many companies to outsource fabrication to dedicated overseas foundries. This outsourcing poses risks of intellectual property (IP) theft and counterfeiting. To mitigate these risks, cheaper obscuring interconnect layers can be created at trusted foundries to secure the final design. This research aims to develop 3D-printed electronic devices with obfuscation and post-processing to prevent unauthorized replication by untrusted facilities. The proposed approach involves a front-end-of-line (FEOL) design with complex structures outsourced to potentially untrustworthy foundries, while a simpler back-end-of-line (BEOL) interposer, made at a trusted facility, connects components to complete the design. Liquid metal traces can be drawn in the interposer layer as post-processing to connect components. The designs use a FEOL layer of conductive PLA and flexible TPU plastics, and a BEOL design of TPU with liquid metal traces. These designs achieved strong electrical contact with resistances in the 10kOhm range, sufficient to power simple circuit components like LEDs. Though resistances are high, they can be reduced with electroless plating. A universal FEOL was created with varying interposer layers to illuminate separate LEDs, demonstrating that outsourced foundries can produce FEOL layers without accessing critical design properties that define device functions. This successful use of obfuscated designs and post-processing shows the potential to protect IP in 3D-printed electronics. Future steps include developing 3D geometries such as cylinders or cubes and increasing feature density beyond a single LED.