Aspects include features for improving the reliability of a reflective base structure for light emitting diodes (LED) chip-on-board (COB) array products. The reflective base structure reduces reflective material of a reflective layer (e.g., silver) from migrating into adjacent layers. In one configuration used to reduce the migration of reflective material, a reflective base for a light-emitting diode (LED) may comprise a substrate, a reflective layer, and a diffusion barrier layer between the substrate and the reflective layer. In another configuration used to reduce the migration of reflective material, a reflective base for an LED comprising: a substrate, a reflective layer; and a planarizing layer between the substrate and the reflective layer, a thickness of the planarizing layer between the substrate and the reflective layer being less than 70 nm.