Role of an interface crack for the blistering mode of a stiff film

A stiff thin film deposited over an underlying compliant substrate is susceptible to blistering when it is subjected to excessive in-plane compressive stresses.

Various glass containers in a laboratory.
A type of UV cured transparent coating was prepared. Image source: PublicDomainPictures - Pixabay (symbol image).

Two kinds of blistering modes (wrinkling and buckling) have been revealed in experiments, depending on the properties of film/substrate pair as well as that of interface adhesion. The purpose of the work was to quantify the role of an interface crack for the selection of such blistering modes in compressed thin films. By a semi-analytical approach, the transitional size of an interface crack was identified at which both wrinkling mode and buckling mode may arise.

Theoretical estimations were validated

The mode selection diagram was constructed and characterised with respect to the normalised interface crack size and compressive strain. The theoretical estimations were validated by a finite element method incorporating an interface cohesive zone model and were demonstrated to be in reasonable agreement with experimental observations in previous literature. The results of the work are expected to be helpful in the effective design and evaluation of thin-film devices.

The study has been published in Journal of Coatings Technology and Research, Volume 19, 2022.

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