Embodiments described herein may be related to apparatuses, processes, and techniques related to hydrophobic features to block or slow the spread of epoxy. These hydrophobic features are placed either on a die surface or on a substrate surface to control epoxy spread between the die in the substrate to prevent formation of fillets. Packages with these hydrophobic features may include a substrate, a die with a first side and a second side opposite the first side, the second side of the die physically coupled with a surface of the substrate, and a hydrophobic feature coupled with the second side of the die or the surface of the substrate to reduce a flow of epoxy on the substrate or die. In embodiments, these hydrophobic features may include a chemical barrier or a laser ablated area on the substrate or die. Other embodiments may be described and/or claimed.