Scratch Testing of Hard Drive

Introduction
A common failure of a hard drive
occurs when a computer is moved or
dropped and the read heads come into
contact with the hard disk platters.
If permanent deformation is caused
from this contact you may get the
infamous blue screen. To protect the
disks and sliders, a diamond-like-
carbon (DLC) coating is applied to
each component. The coatings on the
hard disks are usually 4nm to 30nm
of thickness and the coatings on the
sliders are typically 2nm to 4nm of
thickness. Manufacturing conditions
greatly affect the mechanical
properties and the durability of the
DLC coatings. Typically, instrumented
indentation testing (nanoindentation)
is used to determine the mechanical
properties of thin fi lms; however, due
to overwhelming substrate infl uence,
nanoindentation will not provide
substrate independent mechanical
properties of the ultra-thin DLC fi lms.