Electrostatic discharge (ESD) protection is a significant concern in the chemical and electronics industries. In electronics, ESD often causes integrated circuit failures due to rapid voltage and current discharges from charged objects, such as human fingers or tools.
With the help of 3D printing techniques, researchers at Lawrence Livermore National Laboratory (LLNL) are "packaging" electronics with printable elastomeric silicone foams to provide both mechanical and electrical protection of sensitive components. Without suitable protection, substantial equipment and component failures may occur, leading to increased costs and potential workplace injuries. The team's research is featured on one of the covers in the October issue of Applied Materials & Interfaces.
3D printing is a rapidly growing manufacturing method that enables the production of cellular foams with customizable pore architectures to achieve compressive mechanical properties that can be tailored to minimize permanent deformation by evenly distributing stress throughout the printed architecture. In addition to precise control of print architecture, 3D printing is amenable to custom resins that can be tuned to precisely control the material's intrinsic properties (properties that do not change based on the amount of material present).
Within the breadth of 3D-printing techniques, direct ink writing (DIW) can be used to print many classes of materials including silicone resins. DIW is an extrusion process wherein a paste with controlled rheological properties (elasticity, plasticity and viscosity) is deposited in a layer-by-layer manner to build up three-dimensional structures.
In this work, silicone resins are of interest due to their low volatility, good elasticity, broad thermal stability and more; they have also already been successfully processed via DIW and used in wearable technologies, soft robotics and other structural components.
To print an ESD-protective packaging using DIW, the research team conducted mixing studies to come up with a unique silicone resin formulation containing carbon nanotube (CNT) concentrates and rheological modifiers (thickeners) that could not only achieve printability but also reach the conductivity needed for ESD. CNTs are good conductive additives used to control the build-up of static electricity while rheological modifiers allow for the 3D printing of structures with tailored porosities at high resolutions.
With the specially formulated resin, researchers printed the ESD structure directly onto a circuit board. In addition to providing electrical protection of sensitive circuitry, the printed structure also acts as a cushion, which was tested by striking the circuit board with a hammer.
While the team noted that improvements will be made in future iterations, the printed structure still functions as intended. These packaging capabilities may prove useful for specialized equipment such as those used in medical, robotic and other applications.
LLNL co-authors of the paper include Jeremy Armas, Michael Ford, Kenton Foster, Terence Hall, Colin Loeb, Spencer Schmidt, Stanley Williams, Kathlyn Baron, Lemuel Pérez Pérez, Fangyou Xie, Taylor Bryson and Jeremy Lenhardt.
-Shelby Conn
