Adhesion and delamination of interfaces

• Published in: Journal of physics. D, Applied physics Vol. 44; no. 3; p. 030301
• Main Authors: Bull, S J, Balk, L J
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 26.01.2011; Institute of Physics
• Subjects: Adhesion; Adhesion tests; Applied sciences; Coatings; Condensed matter: structure, mechanical and thermal properties; Delaminating; Delamination; Electronics; Exact sciences and technology; Laminates; Mechanical and acoustical properties; Physical properties of thin films, nonelectronic; Physics; Reinforcement; Stacks; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Testing, measurement, noise and reliability; Thin films; Mechanical properties; Microelectronics; Coatings; Delamination
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/44/3/030301

Thin films and coatings are used for a variety of purposes and their adhesion to the underlying substrate is essential in nearly all applications. Consequently, the need for reliable techniques to quantitatively measure adhesion is paramount. As coating systems become more complex, with, for instance, multilayered and graded architectures now commonplace in MEMS devices, there is a need to improve on existing techniques in order to assess the adhesion of the coating stack to the substrate, but also the delamination of individual interfaces within a coating stack. This requires methods to cause failure, to characterise the locus and extent of any interfacial disbond, and the models necessary to extract quantitative adhesion data from these observations. Similar challenges are faced in bulk composite materials where the adhesion between matrix and reinforcement phase or the delamination behaviour of interfaces between plies will dictate the overall mechanical response of the system There has been considerable activity in devising ways to assess adhesion in the past few decades. In fact, a survey of the literature in 1995 indicated that over 350 different techniques were available ranging from the mundane to the very sophisticated. In spite of this proliferation of techniques there has often been considerable discord amongst people working in the area as to what exactly is being measured in an adhesion test and how reliable the quantification is. In reality, the reason that there are so many techniques is that no one technique is universally applicable, and the adhesion measurements obtained on the same system using different techniques are not always directly comparable. The best adhesion test method is often that which most closely matches the intended application and therefore it will depend on the conditions to which the coated material is exposed. Given the plethora of available measurement and interpretation techniques and recent developments in techniques for characterisation of interfacial failure, we felt that it was timely to assemble a cluster of papers in the area showcasing the latest research and offering some insights in the selection of an appropriate adhesion test. The papers in this issue were solicited from major researchers in the area and represent a snapshot of the current state-of-the-art–we hope they will provide an excellent introduction to the topic for a more general audience.