Quantitative Measurement of Thin Film Adhesion Force

Thin film and micro-fabricated devices are increasingly being used in actuators, sensors, and processors deployed in smart materials. The physical survival of these devices is paramount to their usefulness but existing methods for testing and analysis are limited and challenging due to their properties. The most common test involve the manual application and removal of (unspecified) tape but does not provide a result in scientific units and has large variation (> 35%). This paper presents a study into the effects of parameters of tape application and peeling on the adhesion strength of the tape. This information was then used to create a test methodology using commonly available laboratory equipment, which would control these parameters to minimize variation and produce repeatable quantitative results. Experiments using this test methodology were performed with tape directly adhered to several different substrates as well as tape adhered to a thin film which was then peeled off of a backing. Ongoing work is seeking to identify and address different forms of failure including adhesive failure, cohesive failure, or survival.

Polymer thin film adhesion utilizing the transition from surface wrinkling to delamination

A novel measurement technique is presented that utilizes the transition between surface buckling instabilities (wrinkles to delaminations) to simultaneously quantify the modulus of the film and adhesion of the film to the substrate.

Improvement of Thin Film Adhesion Due to Bombardment by Fast Argon Atoms

A new hollow cathode sputtering system is used for beam-assisted deposition of thin films on dielectric substrates. A copper target placed at the hollow cathode bottom is uniformly sputtered by argon ions from the glow discharge plasma filling the cathode. Through an emissive grid, sputtered copper atoms leave the cathode together with accelerated argon ions. On their way to the substrate, the ions—due to charge exchange collisions—turn into fast argon atoms bombarding the growing film. With increasing argon ion energy, continuous bombardment results in the film adhesion improvement and reduction of the deposition rate down to zero, at an energy of about 2 keV. The pulsed bombardment does not influence the film deposition rate, and results in a monotonic growth of the film adhesion up to 20 MPa when increasing the fast atom energy up to 10 keV.

One-Dimensional Constrained Blister Test to Measure Thin Film Adhesion

A rectangular film is clamped at the opposite ends before being inflated into a blister by an external pressure, p. The bulging film adheres to a constraining plate with distance, w0, above. Increasing pressure expands the contact area of length, 2c. Depressurization shrinks the contact area and ultimate detaches the film. The relation of (p, w0, c) is established for a fixed interfacial adhesion energy.