A method for conductively bonding a printed circuit board to a metal back plate is provided. The ball-joint also comprises a first contact layer, applied to the spherical surface of one of the rings, and a second contact layer, applied to the spherical surface of the other ring. The conductivity sensor can employ two or four electrodes and may have a temperature sensitive element disposed on the distal surface. The nozzle member includes a post-cutoff controllable vibrator assembly connected to a controller for selectively enabling clean cutoff of powder flowing into the container without post-cutoff dribbling. The hook and the depressing slot engage with each other, when the insulative block is damaged, the user can remove the insulative block away from the junction box by levering the hook. The guide pin is employed for initial positioning of the tool on the bone.