Drawing electronic circuits – The production of electronic components with embedded direct written circuits using holographic beam manipulation

This work describes the fabrication of silver/polymeric matrix conductive tracks on both glass and low density polyethylene (LDPE) structure using laser direct writing technology. This has enabled the direct writing of 3 dimensional small circuit boards when discrete electronic components are included into the writing process. In this project, the laser beam was reconstructed by Diffractive Optical Elements (DOE) to a desirable energy distribution which can generate even heat distribution in the paste. The deposited silver paste was scanned by laser beam, using different input energies and scanning speeds. The DSC and TGA tests of the paste was used to identify its thermal properties. The resistivity of the conductive track was measured by 4-point probe technique; meanwhile, the surface topography and cross-section microstructure were investigated by Alicona InfiniteFocus and field emission gun scanning electron microscopy (FEG-SEM), respectively. And the generation of the bubbles during laser curing process was observed by high speed camera. The results showed that by using the DOE, the paste can be cured rapidly and the achieved conductive track shows a low resistivity when compared with the oven cured one (at 200°C for 0.5h); and a more stable curing process with unobvious sputtering phenomenon was achieved when compared with the Gaussian beam. Meanwhile, a circuit board prototype is successful generated using LDPE powder and silver paste.