Terminal structure and wiring substrate

A terminal structure, comprising:

• a wiring layer;
• a protective insulation layer that covers the wiring layer;
• an open portion that extends through the protective insulation layer in a thickness-wise direction to expose part of an upper surface of the wiring layer;
• and
• a connection terminal formed on the wiring layer exposed from the open portion, wherein:
• the open portion includes
• a wall surface extending downward from an upper surface of the protective insulation layer,
• a depression depressed into the protective insulation layer from the wall surface toward an outer side of the open portion, and
• a projection formed under the depression, continuously with the depression, and projected from the depression into the open portion further inward than the wall surface in a plan view;
• the depression is filled with the connection terminal
• the wiring layer includes a recess formed in the upper surface of the wiring layer and connected with the open portion;
• the recess exposes a lower surface of the projection;
• the recess is filled with the connection terminal;
• the open portion has a first opening width at an open end located at an upper end of the wall surface and a second opening width at the depression;
• the recess has an opening width at a recess open end located at the upper surface of the wiring layer;
• the opening width of the recess is larger than the first opening width and smaller than the second opening width;
• the wall surface is inclined from the upper surface of the protective insulation layer toward the depression so as to approach a planar center of the open portion;
• the depression includes
• an innermost end that is a deepest part of the depression, and
• an inner surface extending from a lower end of the wall surface toward the outer side of the open portion to the innermost end,
• wherein an interior angle between the wall surface and the inner surface is an obtuse angle.