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Fabrication and reliability evaluation of a novel package-on-package (PoP) structure based on organic substrate

The package-on-package(PoP) stacking technique with the advantages of printed-circuit-board(PCB) space saving, flexible combination and assembly has become a kind of mainstream solution for the high density package. However, the conventional PoP technology is limited with constraint aspect ratios of I/O density between the top and base packages under conventional solder ball interconnection approach. In this paper, a multilayer PoP structure was designed and fabricated. This design has an organic substrate with a cavity which allowed the package using fine pitch interconnection solder balls and consequently improved the interconnection I/O density between the neighboring packages and reduced the thickness. Also four reliability tests were applied to three-layer PoP samples to evaluate the reliability of this design.