The influence of MWNT composite on the stretchability of conductive nanopaste screen-printed on elastomeric substrate

Abstract

A hybrid silver (Ag)-multiwalled carbon nanotube (MWNT) nanopaste was screen-printed onto a thermoplastic polyurethane (TPU) substrate to create a stretchable electronic interconnection. The effects of various ratios of MWNT contents on the direct current electrical resistivity and the stretchability were investigated by a four-point probe method and a single tensile test, respectively. Square and dog-bone patterns were fabricated by using a 400-mesh stencil mask on a TPU substrate. All samples were pre-dried and then sintered at 140 °C for 1 h in air. The experimental results showed the electrical resistivity of the hybrid Ag-MWNT nanopaste increased with increasing MWNT volume fraction. On the other hand, the hybrid Ag-MWNT nanopaste containing a higher composite ratio of MWNT showed larger tensile resistance. Through optical microscope (OM) observation, we found there were Ag nanoparticles on the MWNT networks under a tensile load of 5%. Prior to rupture-failure, the maximum displacement rate was measured to evaluate the stretchability. The hybrid Ag-MWNT pattern containing 1.2 wt% of MWNT showed the largest displacement rate, 3.4%, this is a 2.70 times increase compared to the Ag nanopaste without MWNTs. To improve both the electrical and mechanical properties of the hybrid Ag-MWNT nanopaste, further research is required.