Print and roll : A technique for rapid production of stretchable liquid alloy circuits

Abstract: Liquid alloy circuitry is an exciting new field of research. It is one of the technologies that strives to make a commercial production of reliable, stretchable circuits possible. The making of liquid alloy circuits is, today, a somewhat tedious handicraft that is time-consuming and not suited for mass production. In this diploma thesis a new method to produce liquid alloy circuitry is presented; print and roll. The circuits consists of Galinstan paths embedded in polydimethylsiloxane (PDMS). Conductive paths are printed in a two step sequence on semi-cured PDMS and then covered with uncured PDMS and exposed to a final curing step. Print and roll produces circuits that are of equal quality as the circuits made with the old method, with a speed and ease superior to the old method. Furthermore advantages and disadvantages with printing on partly cured PDMS substrates are discussed. Partly cured PDMS substrates is important for the print and roll process since it enables the use of uncured PDMS to cover the printed circuit. Using uncured PDMS as a cover-material makes it possible to print the circuits on flat substrates and to use a pick and place machine to place components on the circuit-paths. Some tests with pick and place placing of both large and small components were conducted with varying results.