A Voice Coil Motor (VCM) basically performs head tracking inside an HDD. Facing the growing advancements in track density growth, the increase in the speed for reading and writing and additionally the head alignment accuracy and head speed caused by high disturbance, the future advancements in performance for VCM are close to their limitations. This is due to the carriage block fs mass that carries multiple heads and coils plus the low resonance characteristic the carriage block has. The requirements mentioned above are also desired for suspensions. Under such circumstances, Micro-Actuator (MA) suspensions have been developed as one way to advance head tracking.

The purpose of MA suspensions is to place a MA, which is quite small and light, on the carriage for each HGA. Servo zone tracking will be improved by driving the MA to expand and repress disturbances there by increasing both speed and accuracy. In an MA configuration the seeking motion is covered by a VCM as a MA cannot cover this movement range. The MA will therefore support quick and accurate track following. The division of roles described therefor create what is called DSA (Dual Stage Actuator) suspensions.

Mentioned in the opening paragraph, the necessity for MA was been discussed for over 10 years and trial production has been conducted several times. However, due to the improvements of HDD mechanisms and control systems, and the low performance of early MA, implementation of MA has been passed over.

Regarding the development of MA suspensions, there are two types of designs.