Dual-function conductive silver paste: application of an epoxy system based on curing resistance evolution in packaging and flexible electronics

Abstract

Epoxy resin-based silver paste (SP) has garnered widespread attention in chip packaging owing to its superior mechanical properties and interfacial adhesion. Nevertheless, the regulatory rules of the curing process, the formation mechanism of the conductive network, and the reliability of dual-functional SP in chip packaging as well as its adaptability in flexible sensing remain unresolved research gaps. In this study, an epoxy resin-based SP was developed. By integrating Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), real-time resistance monitoring technology, and process parameter optimization experiments, the correlation between the curing mechanism of the conductive SP and the formation of the conductive network was systematically elucidated, and the optimal curing process was determined. Moreover, the synergistic regulation mechanism of the formula components was investigated, and an SP applicable to both electronic packaging and flexible sensing was successfully prepared. The as-prepared SP exhibits ultra-low volume resistivity (2.95 × 10⁻⁵ Ω cm), a shear strength of 30 MPa, low porosity, and 5B-level adhesion. Additionally, the flexible sensing unit fabricated with silver paste-coated cotton yarn (SP-CY) demonstrates excellent stability and high sensitivity in human motion monitoring. This work fills the aforementioned research gaps and provides critical technical support for high-end electronic packaging and flexible wearable devices.