The overall goals of this research were to establish better selection criteria for the use of polymeric coatings and to develop unique material characterization techniques to measure the properties of thin polymer films. The main focus was on establishing structure/processing/property relationships for novel anisotropic polyimide coatings and measuring their in-plane and out-of-plane properties. This involved understanding the effect of processing conditions on the state of stress and on the material properties, and determining the anisotropic elastic constants. The materials investigated were a variety of polyimides, including some novel fluorinated polyimides. Extensive processing and testing of these materials has been carried out. Residual and thermal stresses have been measured using the technique of vibrational holographic interferometry. The stresses have also been measured under different temperature, humidity, and processing conditions. These polymers are very anisotropic with widely different in-plane and out-of-plane properties. The primary goal of this research was the determination of anisotropic elastic constants--tensile moduli, shear moduli and Poisson's ratios--to aid in reliable modeling of polymers in actual applications. All these constants have been determined using existing as well as new unique techniques. The structure/processing/property relationships for these materials have also been investigated. The anisotropy in properties results from a preferred in-plane orientation in polyimides. The effect of polymer structure, film thickness, and processing conditions on the orientation, and hence on the material properties, has been studied. The material properties have been evaluated by physical, mechanical, and thermal testing. The orientation has been characterized by wide angle x-ray diffraction (WAXD) and birefringence measurements. Another important aspect of reliability of polymeric coatings is the adhesion between coating and substrate. The adhesion of these polyimides to a silicon wafer substrate has been evaluated by a self-delamination method. The improvement in adhesion strength of the polyimide-silicon interface by using a silane coupling reagent has been studied.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-2806 |
| Date | 01 January 1996 |
| Creators | Sheth, Kapil Chandrakant |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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