A head 4 includes a socket 10 and a weight body 12. The dielectric layer so formed can be used to form electronic devices such as MOSFETS and CMOSFETS that require gate dielectrics of different thicknesses. The metal stud bumps include a bump region and a tail region coupled to the bump region. Each first contact includes a main portion received in the corresponding first passageway and a tail portion located at the cavity in condition that at least one side wall of the tail portion is exposed to the outside for excellent heat dissipation. The signal for each of the sub-jobs includes information about the respective sub-job and its priority.