Imaging element mounting board, producing method of imaging element mounting board, and mounting board assembly

An imaging element mounting board for mounting an imaging element, comprising:

• a wire region including:
• a first insulating layer having an imaging element opening portion,
• a metal wire disposed at one side in a thickness direction of the first insulating layer, and
• a second insulating layer disposed at one side in the thickness direction of the metal wire,
• wherein an equivalent elastic modulus of the wire region is 5 GPa or more and 55 GPa or less,
• wherein a difference of thermal expansion coefficients between the metal wire and the first insulating layer is 10 ppm/K or less,
• wherein a difference of thermal expansion coefficients between the metal wire and the second insulating layer is 10 ppm/K or less,
• wherein the imaging element mounting board includes a conductive pattern having an imaging element connecting terminal and the metal wire,
• wherein the imaging element connecting terminal integrally includes an outer peripheral portion that is disposed at an outer periphery of the imaging element opening portion and an inner side portion that is disposed at an inside of the imaging element opening portion so as to be recessed from the outer peripheral portion inwardly, and
• wherein an exposed surface of the inner side portion is exposed from the imaging element opening portion at the other side in the thickness direction of the first insulating layer.