Maskless additive manufacturing of micro structures by laser sintering of nanoparticles

The focus of this study was to investigate an alternate microfabrication process of sintering nanoparticles using a patterned laser light to generate two dimensional (2D) and three dimensional (3D) geometries. With trends of producing electronic and medical devices using cheaper and faster technologies, a new procedure was developed to deposit and bond miniature patterns of silver nanoparticles onto silicon substrates. The process consists of spraying silver nanoparticles onto the substrate while a patterned or modulated laser beam is focused onto the sprayed nanoparticles. These nanoparticles exposed under the modulated laser light undergo partial melting or sintering and adhere to the substrate. The substrate is then cleaned to remove the unexposed nanoparticles from the surface. The deposition thus obtained from the process yields a 2D micropattern. 3D parts are produced using a layer by layer manufacturing process in which a two dimensional pattern is deposited over another pattern repeatedly until the desired elevation is obtained. The initial part of the thesis will discuss the experimental investigation on the influence of process parameter (i.e. flowrate, electric field distance, standoff distance and extractor size) on controlling the length, size and distribution of the spray to deposit nanoparticles. Later, the results of deposition and fabrication of microstructures using the process are presented --Abstract, page iii