Part-Scale Simulation of Heat-Affected Zone Evolution and Part Formation in a Microscale Metal Additive Manufacturing System

Abstract The microscale selective laser sintering (μ-SLS) system is a microscale powder bed fusion (PBF) technology capable of producing fine-resolution, high aspect ratio copper interconnect structures for use in semiconductor packaging and MEMS fabrication. Despite these capabilities, the feature resolution of the μ-SLS system is currently limited by unwanted heat transfer in the nanoparticle bed during laser sintering. A full part-scale thermal model has been developed to predict the thermal evolution in the sintering particle bed in response to a given laser exposure pattern and sintering duration. A thin copper particle layer is modeled atop a thick glass substrate to simulate the sintering domain, and previously developed nanoparticle property relationships allow the model to capture material property changes that accompany nanoparticle sintering. The model is used to predict both temperature change and part densification in response to a variable laser exposure pattern. These temperature and part predictions provide the information needed to preoptimize laser exposure patterns and reduce unwanted heat spread and sintered part error.