Photo-patternable non-conductive adhesives (NCAs) for electronic packaging applications

Photo-patternable NCAs have been newly developed. The new photo-patternable and thermo-curable NCAs were coated on a wafer and selectively exposed to deep ultra violet (UV). Without post exposure bake, the final products on exposed area were dissolved into a sodium carbonate solution and those on unexposed area were not dissolved. As a result, the new NCAs on a wafer were patterned without curing. After a photo-lithography, the wafer with patterned NCA was singulated and the diced chips were flip chip assembled on flexible printed circuit boards (FPCBs). Flip chip assembly using the new photo-patternable NCAs showed the same stable contact resistance and adhesion strength as conventional NCA flip chip assembles.