Thin film capacitor and electronic circuit substrate having the same

A thin film capacitor comprising:

• a metal foil having one roughened main surface and a non-roughened center part including a plurality of crystal particles;
• a dielectric film covering the one main surface of the metal foil and having an opening through which the metal foil is partly exposed;
• a first electrode layer contacting the metal foil through the opening;
• and
• a second electrode layer contacting the dielectric film without contacting the metal foil,
• wherein the non-roughened center part is exposed from a side surface of the metal foil such that parts of the plurality of crystal particles protrude from an inner wall of the side surface,
• wherein a particle diameter of at least one of the plurality of crystal particles is less than 15 μm in a planar direction parallel to the one main surface and less than 5 μm in a thickness direction perpendicular to the one main surface, and
• wherein the one of the plurality of crystal particles has a long side having a particle diameter in the planar direction of 15 μm or less and a short side having a particle diameter in the planar direction smaller than that of the long side.