Development of Stretchable Conductive Adhesive for Flexible Hybrid Electronics (FHE)

This paper describes the development of a conductive adhesive which can be cured at low temperature and has a low modulus as a component mounting application on a flexible substrate. With the expanding wearable market, the demand for flexible hybrid electronics (FHE) applications has been growing steadily. FHE applications have several issues with existing materials. It is that a flexible bonding material is required to mount rigid components on a flexible substrate, and that most substrates used for flexible applications, such as thermoplastic polyurethane (TPU), cannot endure high temperatures. In order to solve these issues, conductive adhesives which have flexible / stretchable properties and low temperature curability are being developed. The developed conductive adhesive can perform low temperature curing at 80 degrees Celsius and has low Modulus of 850 MPa, so it can follow the movement of the flexible substrate. In a packaging test imitating actual applications, even when the base material was stretched by 20%, the sample mounted with our developed stretchable conductive adhesive showed integrity of the component up to 20% elongation and still showed good conductivity.