Development of Next Generation Stretchable Materials for Flexible Hybrid Electronics (FHE)

This paper will show the benefits of the latest stretchable inks and z-axis adhesives for flexible hybrid electronics (FHE) applications. These stretchable inks and z-axis adhesives will be used to build a simple multilayer flashing LED assembled on a thermoplastic urethane (TPU) substrate using standard electronic packaging methods and evaluated for tensile, strain testing, and effects of humidity and temperature.The results from the previous study of single layer silver based and carbon-based structures showed materials remain conductive over large strain however resistance did change for elongation testing and strain testing. Silver based materials had a greater resistance to change compared to carbon-based materials. However, the later had a better resistance recovery.For humidity and temperature evaluations, the silver based single layer samples showed small decrease in resistance under temperature and humidity while the carbon based single layer showed small decrease during the initial twenty-four hours then remained constant for the remainder of the test.Same tests profiles were carried on three assembled multilayer LED flashing circuit with three configurations: non-encapsulated SMD components, encapsulated with old formulation (encapsulant A), and with a new formulation (encapsulant B). Results show that fully encapsulated samples with encapsulant B have the highest resistance to mechanical and environmental stresses.