Mechanical reliability of polyimide insulated interconnections in epoxy encapsulated package under temperature cycle test

Deformation mechanism of polyimide insulated Al alloy lines in epoxy encapsulated package was clarified using temperature cycle test. A shrinkage stress due to the resin on top of the chip creates cracks in the epoxy-resin around the chip corners, and the resin delaminates from the chip to shrink. This causes the polyimide film to tear-off, and the 1st level alloy lines to deform, while upper levels enveloped by the polyimide film move without deformation. Following the model, reliability was improved by preventing the cracks being created in the resin, and/or increasing resin adhesion on chip surface