Plastic encapsulated semiconductor packages may crack if interval delamination occurs during the reflow soldering process, and adhesion integrity evaluation of plastic packages is becoming increasingly important. A new method of estimating the adhesion integrity between epoxy molding resin and silicon chips for plastic packages is proposed. First, three-dimensional stress analysis was carried out to obtain stress distributions in quad flat packages (QFPs) during the reflow soldering process. Next, resin adhesion strength tests were carried out. The shearing load acting on a resin cube molded on a silicon chip was measured, and the maximum shearing load at breakage was obtained. Finally, it was proposed that the stress distributions near the adhesion resin edge of the resin in the test specimen at breakage be used as the criterion for adhesion integrity evaluation of the packages. The adhesion integrity for some QFPs was predicted by comparing the analytical stress distribution in the package and the criterion calculated from the results of the adhesion strength test. The results of reliability tests on the package showed that the new criterion allowed effective evaluation.
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