Case Study: Analyzing Polymer Layers in Multilayer Foil Laminate Barrier Packaging

THE PROBLEM:

A multilayer foil laminate barrier packaging was received with the request that we determine the composition and thickness of the layers.

THE ANALYSES:

Fourier Transform Infrared Spectroscopy (FTIR) using a diamond ATR objective was used to obtain infrared spectra of the outer layers. Delamination of the inner polymer layer was accomplished with a tungsten needle, and infrared spectra were obtained from each polymer layer.

Cross-sectioning with a razor blade revealed that there were a total of 3 polymer layers and one metal layer). The razor cut was sufficient to show the major layers present and indicated thinner bonding layers may be present.

A JEOL SM 09010 ion mill was used to produce a polished cross section with no smearing, revealing the thin bonding materials present between each layer.

The bonding materials were too thin (less than 3 micrometers) for analysis by FTIR.   A motorized and automated WITec Alpha 300 Confocal Raman microscope was used to analyze the composition of the thicker polymer layers and the thinner bonding materials present between each layer.

The Raman microscope is ideally suited for this type of analysis as it uses an automated reflectance mode that can directly analyze and chemically map the ion milled cross section while resolving chemical phases 200 nanometers in size.

THE OUTCOME:

FTIR analysis was able to identify the three thickest polymer layers present in the multilayer foil laminate barrier packaging. Using ion mill cross-section polishing and Confocal Raman microscopy, all of the polymer layers were characterized. Images of the multilayer foil laminate barrier packaging ion milled cross-section were easily obtained using either darkfield reflected light or electron microscopy for layer thickness measurements.