Spring and switch

A switch comprising:

• a substrate;
• a first fixed contact disposed on the surface;
• a second fixed contact disposed so as to surround the first fixed contact;
• a spring disposed above the first fixed contact, and in contact with the second fixed contact at the longitudinal ends;
• a case disposed on the substrate, and formed a housing portion with the substrate in which the first fixed contact, the second fixed contact, the spring and presser are put;
• and
• a protective cover adhered to the surface of the case so as to cover the housing portion, wherein the spring has
• a dome portion having a dome shape bulging convexly toward the upward,
• an outer peripheral portion disposed along an entire periphery of the dome portion,
• a first support portion and a second support portion disposed at both ends of the outer peripheral portion,
• a valley bending portion disposed between the dome portion and the outer peripheral portion, and bent concavely upward,
• a first crest bending portion disposed between the outer peripheral portion and the first support portion, and bent convexly upward, and
• a second crest bending portion disposed between the outer peripheral portion and the second support portion, and bent convexly upward, wherein
• the outer peripheral portion includes a first side end portion and a second side end portion which are not connected with the first support portion and second support portion, and
• the valley bending portion disposed between the dome portion and the first and second side end portions extends linearly or curved inwardly in a longitudinal direction.