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Oxygen free, high
conductivity (OFHC) copper is a common backing plate material.
It has good electrical and thermal characteristics, is easy
to machine and is readily available at economic prices.
Aluminium, molybdenum
and stainless steel can also be used for backing plate fabrication
when copper is not appropriate. As an example, the desired
sputtering target material may have a non-compatible coefficient
of expansion compared to that of copper which can cause the
bonded target assembly to fail irrecoverably. In such a case,
the use of an alternative backing plate metal is essential.
In many instances,
backing plates can be retrieved from spent sputtering target
backing plate assemblies. The recovered backing plate is then
inspected to ensure it is within specification, cleaned and
re-bonded to a new sputtering target.
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