NASA has demonstrated a method for automated fabrication of flexible, electrically conductive patterns on cloth substrates. The products developed using this method are instances of a technology known as "e-textiles." For many applications, including high-speed digital circuits, antennas, and RF circuits, an e-textile should be capable of exhibiting high surface conductivity, tight tolerances for control of characteristic impedance, and geometrically complex conductive patterns.

Unlike prior methods, NASA's new method satisfies all three of these criteria. Typical patterns can include circuit structures such as RF transmission lines, antennas, filters, and other conductive patterns equivalent to those of conventional printed circuits.

In fact, geometrically complex antennas have exhibited performance levels that are indistinguishable from identical designs on conventional materials.
A typical fabrication process according to the present method, involves selecting the appropriate conductive and non-conductive fabric layers to build the e-textile circuit. It uses commercially-available woven conductive cloth with established surface conductivity specifications.

Dielectric constant, loss tangent, and thickness are some of the parameters to be considered for the non-conductive fabric layers. The circuit design of the conductive woven fabric is secured to a non-conductive fabric layer using sewing, embroidery, or an adhesive. The portion of the conductive fabric that is not part of the circuit is next removed using an automated machine such as a printed-circuit-board milling machine or a laser cutting machine. Multilayer circuits can be built starting with the inner layer and using conductive thread to make electrical connections between layers.

For more information, download the Technical Support Package at www.techbriefs.com/tsp under the Manufacturing & Prototyping category.

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