An LED device includes a substrate, a number (N) of flip-chip LED die(s), an electrical conductive structure and a lens structure. The substrate has upper and lower surfaces and is formed with multiple through holes. A ratio of LED die(s) surface area to an area of the upper surface of the substrate ranges from 22.7% to 76.2%. The electrical conductive structure includes a number (N) of upper bonding pad assembly (assemblies), a number (N+1) of lower bonding pads and a number (2N) of interconnectors. Each upper bonding pad assembly includes two upper bonding pads electrically connected to the LED die(s). The interconnectors are disposed in the through holes and interconnect the upper and lower bonding pads. The lens structure covers the LED die(s).