Stretchable circuit board and strain sensor

A stretchable circuit board comprising:

• a stretchable conducting film disposed on one surface of a stretchable substrate;
• and
• a covering material disposed on the one surface of the stretchable substrate so as to cover a part of the stretchable conducting film and at least a part of an electric element,
• wherein a first thickness of a first cross section of the stretchable substrate along an outer circumference of the covering material in a plan view is larger than a second thickness of the stretchable substrate at a location spaced apart from the outer circumference of the covering material.

A stretchable circuit board comprising:

• a stretchable conducting film disposed on one surface of a stretchable substrate, the stretchable conducting film extending in a first direction;
• a covering material that covers a part of the stretchable conducting film and at least a part of an electric element;
• and
• a reinforcing member elongated in the first direction, the reinforcing member making the stretchable substrate harder to expand,
• wherein the reinforcing member is located at a location outwardly spaced apart from an outer circumference of the covering material in a second direction orthogonal to the first direction in a plan view.