Abstract
This paper discusses a passive vibration control method to improve the shock tolerance of hard disk drives (HDDs) in operating condition (op-shock tolerance). Past works in improving the HDDs’ op-shock tolerance includes (i) parking the head when shock is detected, (ii) installing a lift-off limiter, (iii) structural modification of the suspension, and (iv) installing an external vibration isolation. Methods (i) and (iv) have practical issues, method (ii) works only on single shock direction, and method (iii) requires major engineering design/manufacturing work. Compared to these works, this paper proposes a method which has no practical issues and without requiring major engineering design/manufacturing work. The proposed method is to apply a polymer-based dampening layer on the backside of the baseplate with the purpose of increasing the damping ratio of the 1st bending mode of the baseplate. The location of the dampening layer on the baseplate is first determined by modal analysis and then fine-tuned by non-op-shock tests. The op-shock tolerance improvement is confirmed by op-shock tests where 2.5″ HDD with the dampening layer on the baseplate can withstand a 300G 0.5-ms shock without failure while unmodified HDD can only withstand 250G 0.5-ms shock without failure.
Highlights
The demand for higher density hard disk drives (HDDs) pushes the requirements for the head–disk spacing
This paper proposes a method of external HDD shock isolation that neither changes the footprint of the standard HDD form factor nor change the HDD’s design
A strategy to apply dampening layer on the baseplate of the HDD to increase its opshock tolerance has been presented in this paper
Summary
The demand for higher density hard disk drives (HDDs) pushes the requirements for the head–disk spacing. The greater the HDDs’ density, the smaller the head–disk spacing required (see [1,2,3]). The head–disk spacing can be designed by setting the slider’s flying height. The flying height of the slider affects the stiffness of the air bearing, and more importantly, the shock response of the HDDs (see [4]). HDDs need to be protected from failures which are caused by external disturbance, i.e., external shock. Studies on HDDs’ failure mechanism due to external shock can be found in [5, 6] and the references therein. HDDs fail when the head is touching the disk
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