Mechanical Limitations of Materials for Steel Foil Based Flexible Electronics

Abstract

This work investigates mechanical limitations of thin film materials on steel foil substrates for flexible electronic applications. A three layer structure consisting of 100μm thick stainless steel foil as the substrate, followed by 1μm thick spin-on-glass passivation layer and 0.3μm thick patterned aluminum interconnect layer on top with varying widths between 10-35μm. A collapsing radius test method was adopted for the bending experiment and an elliptical curve fit was used to facilitate the strain measurement. The failure strain of aluminum interconnect layer was detected by monitoring the continuity of the test circuit during the experiment. The corresponding results reveal that the passivation layer cracked at a tensile strain of 0.46% and delaminated at a compressive strain of 0.68%. The metal interconnect layer ruptured at a tension strain of 1.26% and delaminated from the substrate at a compressive strain of 1.22% due to the delamination of the passivation layer underneath.

Investigation of the reliability of nano-nickel/niobium oxide-based multilayer thin films deposited on polymer substrates for flexible electronic applications

“…4 Although thin metal substrates offer considerable mechanical strength, corrosion resistance, and high temperature tolerance, 5 they suffer from limited bendability and overall achievable thickness. 6 Silicon/glass substrates offer high temperature resistance. 7 Thin glass substrates also offer high light transmittance.…”