Novel electrical re-connection of very thin fine pitch ball grid array (VFBGA) package for advanced backside fault isolation

With the development of the semiconductor industry, the layers of the metal interconnection increased, and the front-side package dimension shrunk. All these trends are emphasizing the importance of the backside Fault Isolation (FI) in advanced product Failure Analysis (FA). However, electrical signal reconnection when handling the repackage becomes the primary challenge in handling the backside FA. In this paper, an innovated method for electrical reconnection, which can be effectively applied on Very Thin Fine Pitch Ball Grid Array (VFBGA) package for backside FI is introduced. By engraving a pattern (for example holes, blocks and trenches) on the surface of the package, and depositing metal into the pattern, electrical signals can be re-connected out from bond pads to metal blocks on the package surface through metal lines embedded in the pattern. Detailed processes, operation parameters and experiment results are well represented.