US Patent 7595961 Base member and information storage apparatus

In an information storage apparatus, a relatively thin attachment member has a cylindrical boss section projecting from a surface thereof and a path passing through the attachment member and reaching the extreme end of the boss section and is attached to a relatively thick base member. The base member has a through hole which passes therethrough in the thickness direction thereof and into which the boss section is inserted. The attachment member is caulked to the base member by plastically deforming the boss section by causing a caulking ball whose diameter is larger than that of the path to pass therethrough in the state that the boss section is inserted into the through hole. The through hole has an escape section into which a part of the plastically deformed boss section escapes, thereby a large amount of plastic deformation of the boss section can be suppressed.