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Improvements in the electromechanical properties of stretchable interconnects by locally tuning the stiffness

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Details

Original languageEnglish
Article number015004
JournalFlexible and Printed Electronics
Volume5
Issue number1
DOIs
Publication statusPublished - 2020
Publication typeA1 Journal article-refereed

Abstract

Recent advances in materials science and structural design have changed electronic applications from being bulky and rigid objects to small and soft products that have emerged for a wide range of applications, especially human-related products for which mechanical adoption is the key requirement. A typical stretchable application consists of small-sized, rigid IC-chips and passive components interconnected by conductive tracks on soft substrates. The early failure of such devices initiates from the rigid-soft interface due to the accumulation of stress. Therefore, special attention is needed to reduce the strain concentration at the interface. In this paper, stretchable interconnects were fabricated using a screen-printing method and surface mounted devices (SMDs) were bonded using an isotropic conductive adhesive. By partially removing material from the substrate in areas a little way from the rigid components, the stiffness is locally reduced, and this leads to an increase in the local stiffness around the SMDs and hence shields the soft-rigid interface against the stress. Materials can be removed by two different patterns. A finite element analysis and experimental data show 11%-19% improvements in single pull-up tests for the modified samples. This approach makes the electromechanical behaviour independent of encapsulation properties.

Keywords

  • electromechanical properties, finite element (FE) analysis, printed electronics, screen-printing, strain concentration, stress distribution, stretchable electronics

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