Time-resolved in-situ temperature measurement and analysis for continuous-wave laser sintering of carbon nanotube – Metal composites on a polymer substrate

Abstract

Previous research work shows that metal nanocomposite thin films fabricated by laser sintering of mixtures of metal nanoparticles (NPs) and carbon nanotubes (CNTs) on a polymer substrate have a great potential to help enhance reliability and durability of metal components in flexible electronic devices. To gain a good relevant fundamental understanding, it is important to know the material thermal history during laser sintering. However, an in-situ temperature measurement has been rarely reported in a paper in the literature for laser sintering of metal NP-CNT mixture thin films on a polymer substrate. Such temperature measurements are reported in this paper, which are performed using a two-color pyrometry system set up by the authors to overcome related technical challenges such as high spatial and temporal resolution requirements. The measurement method is non-contact, and by measuring thermal radiation in two wavelength ranges it does not require the value of the target surface emissivity. The electrical resistivities of composite material sintered with different laser scanning speeds are also measured. Under the conditions studied, it has been found that as the laser scanning speed increases significantly, the average melted material temperature in the measurement spot only slightly decreases, but the melting duration drops significantly. The average electrical resistivity of sintered composite material first decreases and then increases with the laser scanning speed. The measured material surface temperatures for laser sintering of CNT and silver NP mixtures are similar to those for laser sintering of silver NPs with the same laser scanning speed.