This paper describes mechanical means for enhancing the adhesion between the epoxy molding compound and the die and die pad in plastic packages. By introducing patterns of holes and slots along the periphery of the die pad, better anchoring between the plastic and the die and die pad is achieved. Interfacial delamination, as determined by scanning acoustic tomography, is minimized. The improved adhesion reduces wire bond fatigue failures and minimizes the risk of moisture accumulation under the die pad that often leads to plastic cracking during solder reflow. Higher packaging reliability can thus be achieved. Finite element modeling of the different design configurations yields stress profiles and deformation patterns which agree qualitatively with the experimental results.

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