I am trying to develope a laminate using a sheet of polyimide adhesive bonding two pieces of 1 mil constantan together. When I do a 12" x 24" sheet, I get vertical lines of very small blisters (running up the 12" width all along the 24" length. When I do a 12" x 12" sheet, I get blisters around the outer perimeter(1/8" to 1/4" in diameter). I cannot figure out what is causing these blisters. I have baked the material out, scrubbed it and then dryed it, but I keep getting the same results. I now believe it may be outgassing of the polyimide adhesive sheet. There isn't much technical info available for this adhesive sheet either. Any thoughts or tests I could perform? Thanks for you time.
I haven't been "doing adhesives for awhile"
May be the substrate too...
Is the Polymide in a solvent? It is a sheet? Does that mean it is already "dry"?
The blisters and lines could be "memory" on the Canstantan -
try Monsanto Chemists
They are really good...
Have you tried heating the adhesive in an oven or used a blow dryer to help the lamination. Also look at the adhesive under magnification looking for dots of gunk or myer rod streaks. ( groove like ). When coating the use a wire wound rod.. If its not clean or thirty are running fast they are common.