Laser Sintering Direct Ink Write Silver Nanoflake Ink for On-Demand Manufacturing of Electronics in Space

Abstract

Developing manufacturing methods for flexible electronics will enable and improve the large-scale production of flexible, spatially-efficient, and lightweight devices. Laser sintering is a promising post-processing method to produce consolidated films for flexible electronic devices while reducing power consumption compared to standard thermal sintering. This work further explores laser sintering of direct ink write (nScrypt) printed silver as a continuation of previous studies on nScryptprinted silver and aerosol jet-printed gold, platinum, and titanium dioxide for manufacturing printed electronics on the International Space Station. Four different laser wavelengths are studied for laser sintering nScrypt silver nanoflake ink on flexible polyimide and rigid glass substrates. The laser systems investigated are continuous wave (CW) 808 nm, CW 445 nm, CW 1064 nm, and pulsed femtosecond (fs) 1040 nm lasers. The laser power and scanning speed are varied to compare the laser systems and optimize laser sintering parameters for the silver ink. The resistivity of the laser-sintered silver NPs is compared to the resistivity of the unsintered silver to demonstrate the effectiveness of laser sintering. An optimal resistivity of 5.81×10 -8 Ω-m is achieved for the nScrypt silver laser sintered using a fs 1040 nm laser.