Patent attributes
A holding member or a base member, through which stem pins are passed and one surface of which is held by the holding member, is joined to the stem pins and the holding member by fusion by the melting of the base member. Upon melting, a volume of the base member is made to escape into a base member seep portion, and a stem is arranged as a two-layer arrangement formed by the holding of the base member by the holding member. When the holding member is joined to the inner surface of the base member, the inner surface of the stem is improved in positional precision, flatness, and levelness, while when the holding member is joined to the outer surface of the base member, the outer surface of the stem is improved in positional precision, flatness, and levelness.
