Flip chip bonding on stretchable printed substrates; the effects of stretchable material and chip encapsulation. (1st March 2023)

• Record Type: Journal Article
• Authors: Malik, Muhammad Hassan; Kaczynski, Jaroslaw; Zangl, Hubert; Roshanghias, Ali
• Is Part Of: Flexible and printed electronics. Volume 8:Number 1(2023)
• Publication Date: 2023-03-01
• Subjects: stretchable hybrid systems (SHS) -- ultra-thin chips (UTC) -- hybrid integration -- printed electronics -- anisotropic conductive paste (ACP) -- stretchable -- Beyolex; Flexible electronics -- Periodicals; Printed electronics -- Periodicals; Flexible electronics; Printed electronics; Electronic journals; Periodicals; 621.381
• DOI: 10.1088/2058-8585/acb2d9
• Languages: English
• ISSNs: 2058-8585

Abstract

Abstract: Stretchable printed electronics have recently opened up new opportunities and applications, including soft robotics, electronic skins, human-machine interfaces, and healthcare monitoring. Stretchable hybrid systems (SHS) leverage the benefits of low-cost fabrication of printed electronics with high-performance silicon technologies. However, direct integration of silicon-based devices on conventional stretchable substrates such as thermoplastic polyurethane (TPU) and polydimethylsiloxane (PDMS) is extremely challenging due to their restricted low-temperature processing. In this study, a recently developed thermoset, stretchable substrate (Beyolex TM ) with superior thermal and mechanical properties was employed to realize SHS via direct flip chip bonding. Here, ultra-thin chips (UTC) with a fine-pitch, daisy-chain structure was flip-chip bonded by using anisotropic conductive adhesives, while the complementary circuitry was facilitated via screen-printed, stretchable silver tracks. The bonded samples successfully passed reliability assessments after being subjected to cyclic 30% stretch tests for 200 cycles. The potential benefits of chip encapsulation after integration with the stretchable substrate to withstand larger strains were demonstrated by both mechanical simulation and experimental results.