Damage of Flexible Electronic Line Under Mechanical and Electrical Stress Loading

Flexible printed circuits (FPCs) are widely used in electronic devices such as movable part line or wearable sensor. Inkjet printing is attracting attention because it can draw electric lines of any shape without a photo mask. The mechanical characteristics such as flexibility or durability of electric lines have been evaluated by bending and tensile tests. Moreover, the reliability characteristics of metal particle ink lines under electric current loading have been recently evaluated. However, the electronic line has not been evaluated under both the mechanical stress due to bending deformation and the electrical stress due to electric current. According to scaling down of electric devices, the current density and Joule heat in interconnect line increase and electromigration (EM) damage becomes a serious problem. EM is a transportation phenomenon of metallic atoms caused by electron wind under high-density electric current. Reducing EM damage is extremely important to enhance device reliability. In this study, high-density current loading tests of flexible electronic line were conducted under bending deformation of the substrate in order to investigate the effect of mechanical stress on the EM damage of the electronic line. As the results of current loading tests, the specimens with bending deformation became open circuits in shorter time than that without bending deformation. Therefore, it is considered that the bending deformation is affected on the electric reliability characteristic of the flexible electronic lines reflecting EM damage.

An Improved Electronic Line Shafting Control for Multimotor Drive System Based on Sliding Mode Observer

As the computation delays between the reference torques and the load torques, the speed and position synchronous errors of the multimotor drive system employed traditional electronic line shafting (ELS) control would become significant during the process of large load disturbances. Therefore, an improved ELS control strategy is proposed in this paper. In this strategy, the load torques observed by the sliding model observers are fed back to the virtual motor directly, so as to shorten the adjusting time and improve the antidisturbance performance of entire control system. Meanwhile, to reduce the chattering of the sliding mode observer, a novel exponential reaching law is designed in this paper. The experimental results show that the improved ELS control strategy could reduce the speed and position synchronous errors effectively.