Abstract: A light-emitting element mounting substrate includes an insulative substrate, a pair of wiring patterns formed on one surface of the substrate, and a pair of filled portions including a metal filled in a pair of through-holes to contact the pair of wiring patterns and to be exposed on a surface of the substrate opposite to the one surface, the pair of through-holes penetrating through the substrate in a thickness direction. The pair of filled portions includes a protruding portion that protrudes outward from the pair of wiring patterns when viewed from the one surface side of the substrate.

Abstract: A light-emitting element mounting substrate includes an insulative substrate including a single-sided printed circuit board, a pair of wiring patterns formed on one surface of the substrate, the wiring patterns being separated with a first distance, a pair of through-holes penetrating through the substrate in a thickness direction, the through-holes being separated with a second distance, and a pair of filled portions including a metal filled in the pair of through-holes to contact the pair of wiring patterns and to be exposed on a surface of the substrate opposite to the one surface. Each of the pair of filled portions has a horizontal projected area of not less than 50% of an area of each the pair of wiring patterns.