INFLUENCE IN SOLVENT COMPOSITION ON MICROSTRUCTURAL INTEGRITY AND FATIGUE RESISTANCE OF PRINTED GNP/Ag CONDUCTIVE INKS

Zikriah Zakaria; Nor Azmmi Masripan; Mohd Zaid Akop; Nurfaizey Abd Hamid; Chonlatee Photong; Alan Watson; Mohammed Hussin  AL-Mola; Mohd Azli Salim

Zikriah Zakaria Unit Akademik dan Pendidikan Berterusan, Kolej Komuniti Rompin, Kuala Rompin, Pahang, Malaysia.
Nor Azmmi Masripan Fakulti Teknologi dan Kejuruteraan Mekanikal, Universiti Teknikal Malaysia Melaka, Melaka, Malaysia.
Mohd Zaid Akop Fakulti Teknologi dan Kejuruteraan Mekanikal, Universiti Teknikal Malaysia Melaka, Melaka, Malaysia.
Nurfaizey Abd Hamid Fakulti Teknologi dan Kejuruteraan Mekanikal, Universiti Teknikal Malaysia Melaka, Melaka, Malaysia.
Chonlatee Photong Faculty of Engineering, Mahasarakham University, Thailand.
Alan Watson Power Electronics and Machines Centre, The University of Nottingham, United Kingdom.
Mohammed Hussin AL-Mola College of Agriculture and Forestry, University of Mosul, Iraq.
Mohd Azli Salim Fakulti Teknologi dan Kejuruteraan Mekanikal, Universiti Teknikal Malaysia Melaka, Melaka, Malaysia.

Keywords: GNP/Ag, hybrid conductive ink, torsional, microstructural degradation, printed electronics

Abstract

Conductive inks are essential for flexible and wearable electronics, however their mechanical durability under torsional fatigue remains poorly understood. This study investigated the formulation and mechanical behaviour of hybrid graphene nanoplatelet and silver conductive inks to address this gap. Three ink formulations were developed using fixed ratios of graphene nanoplatelets at 0.5 g, silver flakes at 4.292 g, and silver acetate at 0.42 g, with varying butanol-to-terpineol solvent ratios of 5:10, 10:10 and 15:10 corresponding to samples labelled as 5-B, 10-B and 15-B respectively to influence viscosity and filler dispersion. The inks were screen-printed onto copper substrates and thermally cured at 250 °C for five hours. Cyclic torsional fatigue testing, conducted up to 16,000 cycles at an angle of 90 degrees and speed of 211 cycles per minute to assess resistance stability under repeated mechanical stress. The results revealed that solvent composition played an important role in determining the mechanical and electrical performance of the printed inks. The 10-B sample with a 10:10 butanol-to-terpineol drops improved filler network formation, leading to enhanced conductivity and structural cohesion. Scanning electron microscopy (SEM) at ×800 and ×2000 magnifications identified microstructural failure modes such as cracking, filler agglomeration, and void formation, with more severe degradation observed in formulations in the 5-B sample. Among the tested samples formulations of 5-B, 10-B and 15-B, the optimised 10-B formulation exhibited an excellent resistance stability with initial resistance of 0.325 ohms and after 16,000 cycles, which increased to 0.520 ohms with minimal physical deterioration, confirming its superior fatigue endurance. This work highlights the importance of solvent-engineered rheology and filler interaction in achieving mechanically robust and electrically stable conductive inks.