Patent ID: 8553367

Claim:
A partially depopulated head stack assembly (HSA) comprising: first and second actuator arms; a first head gimbal assembly attached to the first actuator arm, the first head gimbal assembly including a read head; a dummy mass not having a read/write head, wherein the dummy mass is attached to a distal end of the second actuator arm, the dummy mass including a mounting plate portion defining a mounting plate width; a neck portion defining a neck width and a neck length; and a distal mass portion defining a distal mass width and a distal mass length; wherein the neck width is less than the mounting plate width and the neck width is less than the distal mass width; and wherein the neck portion is disposed between the mounting plate portion and the distal mass portion, and the neck portion connects the mounting plate portion to the distal mass portion wherein the mounting plate width, the neck width, the neck length, the distal mass width and the distal mass length are selected in accordance to one or more dimensions of the first head gimbal assembly, such that the partially depopulated HSA has dynamic characteristics similar to those of a fully populated HSA.