Test methods for measuring tensile strength and ductility of electroplated and electroless copper deposits

A number of specialised techniques for measuring the tensile strength and ductility of electroplated and electroless copper deposits have been developed over previous years. There is however no universally favoured test, which can fulfil all the requirements, such as simplicities in specimen preparation, equipment operation and result interpretation, reliability and reproducibility of the result, and adaptability to deposits before and after detachment from the substrates. Consequently, the selection of test methods has to depend on the film condition and the requirements of the application. In this paper, descriptions of the principles, advantages, and disadvantages of various test methods for measuring tensile strength and ductility of electroplated and electroless copper deposits are presented. According to the way a specimen is deformed during testing the test methods are summarised into seven categories: tension testing, hydraulic and mechanical bulge tests, fatigue testing of ductility, bend tests, modified Erichsen cup test, and indentation testing.