Abstract: A mounting board includes an electrode pad and an insulating protective film on an insulating resin layer. In a plan view, the electrode pad includes first and second sides running parallel in a first direction. The insulating protective film includes an opening including first and second regions adjoining each other in the first direction. The first region lies over the electrode pad to expose part of the electrode pad. The second region exposes part of the insulating resin layer. The first region is defined by third and fourth sides that are between the first and second sides in a second direction perpendicular to the first direction and run parallel in the first direction. The maximum dimension of the second region in the second direction is greater than the distance between respective ends of the third and fourth sides at which the first region adjoins the second region.

Abstract: A mounting board includes an electrode pad and an insulating protective film on an insulating resin layer. In a plan view, the electrode pad includes first and second sides running parallel in a first direction. The insulating protective film includes an opening including first and second regions adjoining each other in the first direction. The first region lies over the electrode pad to expose part of the electrode pad. The second region exposes part of the insulating resin layer. The first region is defined by third and fourth sides that are between the first and second sides in a second direction perpendicular to the first direction and run parallel in the first direction. The maximum dimension of the second region in the second direction is greater than the distance between respective ends of the third and fourth sides at which the first region adjoins the second region.