Comparison of the shear strength and reliability between gold-plated and bare copper lands of a BGA package

In this study, we focus on the possibility that the land of bare copper in plastic ball grid array (PBGA hereafter) packages may be used instead of the gold-plated land. Comparison of the shear strength of the balls on the two types of the land is made every 100 cycles of the temperature cycling test. The result shows that the shear strength of bare copper lands with oxidization during the standard process of PBGA is almost as comparable as that of gold-plated lands within experimental error range. Surface analysis of the lands before ball attachment and after ball detachment is presented. A possible process development using copper wire is suggested.