To restrain and absorb shear stress on the connection terminals or pads of a relay board so as to protect the pads and solder on the board and soldered parts adjacent to joints against damage to improve the relay board in connection reliability, wherein the relay board is interposed between a board and a mounting board so as to connect them together.

A structure, slits, notches or grooves are provided to a relay board main body 4 so as to relax shear stress imposed on the connection terminals or pads of a board 1, whereby shear stress is restrained from being induced and absorbed to enhance the relay board 1 in connection reliability. When stress imposed on the connection terminals or pads of the board 1 gets stronger as the relay board 1 gets larger in size, the enlarged relay board is shaped like an aggregate composed of small relay boards by this invention, whereby shear stress on the connection terminals or pads on the board 1 is restrained and absorbed, so that pads and solder formed on the board 1 and soldered parts near to joints are protected against damage, and the relay board 1 can be improved in connection reliability.