The present invention provides a baseplate comprising a cylindrical hub, a flat flange, and one or two circular notches of a “V” or “U” shape etc. formed in said flange. This baseplate has the advantages of smaller deformation and larger retention torque during swage operation. Also it is easy to make and has no further cost in production. Moreover, the present invention further provides an arm and suspension assembly equipped with the baseplate and a hard disk drive equipped with the arm and suspension assembly.