Thin films can be defined as coatings with a thickness from 10 microns (µm) down to one nanometer or less.
Even the slightest degree of uneven pull stress distribution is disastrous for the adhesion test results for thin films. On a nanometer scale there is obviously no elasticity in the coatings which can correct some of the negative effects of test equipment with uneven pulling action.
The PAT test equipment lends itself particularly well to these coatings since stress distribution is ensured regardless of the coating thickness.
Thin film adhesion testing is normally carried out on purpose-made test panels but testing can also be done in accordance with ASTM-C633 (pulling apart two test cylinders which are glued together)
Testing of thin films can successfully be done either with a manual or an automatic adhesion tester. The recommended models are the following:
1) Manual testing
Testing with the Ø8.16mm test element gives a certified testing range of up to 102 MPa. If a film with a much lower adhesion strength than that is to be measured it is advisable to use a larger test element in order to use as much of the gauge scale as possible.
Adhesion testing of thin films can also be done with larger test elements, e.g. the Ø25mm size.
2) Automatic Tensile Pull Testing
The most popular all-round tester which is also suitable for thin films.
Required if testing of high strength films with the Ø25mm (one inch) test element this is required.
The most powerful testing machine in the range. Used for the high tensile films.
Automatic testing using very small test elements (from Ø2.8mm)