Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1992-11-16
1993-11-16
Gallagher, John J.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156150, 156234, 156246, 156268, 156280, 264259, 264311, 427240, 427250, B32B 3116
Patent
active
052619770
ABSTRACT:
A method of fabricating free-standing thin films of polyimide by casting a polyamic acid solution onto a substrate that is free of parting agents and release agents is disclosed. The polyamic acid film is imidized on the substrate. The thickness of the polyimide film can range from about 200 .ANG. to about five microns. A frame is adhered to the polyimide film while the film still attached to the substrate, and the frame, film, and substrate assembly is immersed in an aqueous based liquid bath for several hours wherein the liquid bath is free of reactive chemical agents. The liquid bath is heated, preferably, to a temperature within the range 30.degree. to 100.degree. C. The liquid is prevented from contacting the polyimide film within the interior region of the frame. Next, the assembly is removed from the water bath. The film is scored around the outside edge of the frame with a cutting tool; this cutting step may be performed either prior to, during, or after the immersion step. The frame is then detached from the substrate by first lifting only one side of the frame and then pivoting on the edge 180 degrees opposite. The process uses the frame itself to peel the film off the substrate, thereby producing a frame-supported and free-standing polyimide film. The present method omits the use of chemical agents, release agents, parting agents, and other detachment means whose purpose would have been to loosen the bond between the film and the substrate. The polyimide film may be metallized by vacuum evaporation or by sputtering to create a metal-polyimide composite. Free-standing thin polyimide films find particular utility in x-ray optics as bandpass filters and proportional counter entrance windows.
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