Embodiments of the invention provide a head gimbal assembly (HGA) capable of effecting solder ball connection with use of low energy. In one embodiment, the HGA includes a head/slider. In the head/slider, slider pads and lead wire pads are connected to each other by reflow of solder balls under the radiation of a laser beam. Lead layers are connected to a magnetic head and electrode studs are connected to the lead layers, respectively, and are also connected to the slider pads. The diameter R (m) of a solder ball and a sectional area S (m.sup.2) of an electrode stud are in a relation of R.sup.2.gtoreq.4S.